US 3744694 A
Description (OCR text may contain errors)
United States Patent 1 Karnes et al.
[ July 10,1973
[ APPARATUS FOR MOVING WIRE  Inventors: Donovan Karnes; Marion F.
Centliver, both of Troy, Ohio  Assignee: Hobart Brothers Company, Troy,
 Filed: May 7, 1971  App]. No.: 141,290
Related US. Application Data  Continuation-impart of Ser. No. 40,l89, May 25,
 U.S. Cl. 226/168, 74/25  Int. Cl B65h 17/24  Field Of Search, 226/168, 195, 181,
 References Cited UNITED STATES PATENTS 3,424,012 H1969 Hirmann 74/25 2,152,518 3/1939 Wolff 74/25 Primary ExaminerRichard A. Schacher Assistant ExaminerGene A. Church Attorney-Marechal, Biebel, French & Bugg  ABSTRACT An apparatus for moving cylindrical members, particularly welding wire, includes a rotary to linear actuator having a body with an axially extending opening through which the wire is fed and a plurality of rollers mounted to rotate with the actuator body, the axis of each roller being skewed or inclined relative to the axis of rotation to impart a component of force to the wire to move it in a linear direction through the actuator as the actuator is rotated. At least one roller is carried on a movable arm mounted on the actuator body. This arm includes sufficient mass to counterbalance substantially the centrifugal force imposed on the roller as the actuator body is rotated. ln one preferred embodiment, the arm is pivotally mounted on the actuator body. Biasing means, such as torsion bars or small springs, provide force to urge the rollers against the wire. In another embodiment, a centrifugal weight on the mounting arm provides additional force to urge the rollers against the wire. The actuator body is rotated by a motor having an axially extending opening in its armature through which the wire may pass.
31 Claims, 28 Drawing Figures PATENIEU JUL 1 0191s SHEU 1 W 5 m/vsurons DONOVAN KARNES a LHK MARION F. CENTLIVER BY W m PATENIH) JUL 101913 SHEET 2 0f 5 PATENIEU JUL 1 0191s SHEEI t Of 5 FIG-22 FIG-23 APPARATUS FOR MOVING WIRE RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 40,l89 now abandoned, filed May 25, 1970.
BACKGROUND OF THE INVENTION In some welding situations, it is convenient to use a hand held welding gun which supplies a consumable welding wire at a controlled rate to the weld. Such guns may also include means for supplying a shielding gas to envelop the weld and means for supplying electrical current to the consumable wire. One such welding gun is shown in U.S. Pat. No. 3,093,728.
Since the operator must hold the gun continuously during welding, it is desirable that the gun be made as lightweight as possible. Also, reducing the size of the gun simplifies storage and handling.
In prior art welding guns, a consumable welding wire is usually passed between feed rolls, at least one of which is knurled and driven by a motor. Frequently, one or more rolls are spring biased toward the driven rolls to insure that enough frictional force is available to move the wire. Thus, as the wire is initially fed into the gun, the bias of the springs must be overcome before the wire will pass between the rollers. With this type of gun, however, slippage between the rolls and the wire tends to abrade the wire and remove its protective coating. Also, the residue from such abrasion may eventually cause a malfunction of the gun.
In prior art welding guns, the output from the small motors commonly used is directed to minature speed reduction gear boxes. These speed reducers are expensive and frequently give trouble because of the small size of the gears and bearings employed. In addition, these small gear boxes are inefficient and therefore a considerable portion of the torque available from the motor is absorbed in the speed reducer.
SUMMARY OF THE INVENTION This invention relates to an improved apparatus for moving small diameter cylindrical members and employs a novel rotary to linear actuator. The invention is particularly useful in a welding gun since it permits the gun to be lightweight and small in diameter to facilitate use by the operator.
Rotary to linear actuators have been employed which use inclined contact rollers engaging a rigid cylindrical member. When the inclined rollers are rotated around the cylindrical member, they will follow a helical path relative to the member, and since the rollers are prevented from moving in the axial direction, a part of the rotary motion is converted to linear movement of the member. The greater the angle the axis of the rollers make with respect to the axis of the cylindrical member, the greater will be the linear velocity imparted to the cylindrical member for a given rotational speed. One such rotary to linear motion device is shown in U.S. Pat. No. 2,152,518.
The rotary to linear motion actuator of this invention includes a body having an axially extending opening therethrough and a plurality of rollers mounted for rotation with the body. At least one of the rollers is carried by a movable arm mounted on the actuator body. This arm includes sufficient mass properly located to counterbalance substantially the centrifugal force acting on the roller as the body is rotated. In one embodiment, this arm is pivotally mounted on the body. In another embodiment, the ann is torsionally mounted on the body.
When the actuator is used to move wire of only one diameter, the wire may be centered within the actuator body with only one of the rollers mounted on a movable arm. When the actuator is used to move wires of different diameters, however, it is preferred that all of the rollers be mounted on movable arms in order to provide proper centering of the wire within the actuator body.
The centrifugal forces acting upon the roller is substantially counterbalanced by proper design of the roller supporting arm. When the centrifugal force is exactly counterbalanced, the only force exerted by the rollers on the wire will be due to biasing means and will be independent of the speed of rotation of the actuator. In other cases, it may be desired that the centrifugal force acting upon the arm be used to force the roller into the wire so that more force is applied to the wire as the rotational speed of the actuator is increased.
The biasing means may include small springs which are positioned either between the actuator body and the centrifugal weights or between the weights on one arm and the roller supporting part of the arm supporting the other roller of the mutually opposed pair of rollers. The biasing means may also include torsion bars pivotally supporting the rollers and weight carrying arms with the torsion bars being arranged to bias the rollers against the wire.
In one embodiment of this invention, the rotary to linear motion actuator includes a body having a wire receiving opening extending therethrough which is coaxial with its axis of rotation. At least a pair of opposed rollers are mounted on the body in mutually opposed relation to the opening and spaced radially from the axis of rotation of the body, with the axis of the rollers being skewed or inclined so that a portion of the rotary motion of the rollers around the axis of the body will impart linear motion to a wire fed through the opening in the body. The rollers are carried by arms pivotally mounted to the actuator body, and each arm includes a weight which, as the actuator body is rotated, will move outwardly due to centrifugal force to force the rollers against the wire. Thus, as the actuator is rotated, a component of velocity is imparted by the rollers to the wire in the axial direction in direct proportion to its rotational speed. In this embodiment, the biasing means assist in urging the rollers into positive contact with the wire for initial starting and continued operation at low rotational speeds of the body.
In another embodiment of the invention, two sets of rollers are employed to provide additional force to move the wire. The second set of rollers is preferably so positioned that at least one if not all of the rollers will form a track on the wire which is coincident to the track formed by the first set of rollers. It has been found that this arrangement is particularly desirable when feeding aluminum wire.
In another embodiment, the inclined rollers engage the wire in a plane perpendicular thereto, and 'the centrifugal weights are so designed to balance substantially the centrifugal force acting on the rollers so that the entire force acting on the wire is due to the biasing means and is independent of the speed of rotation of the actuator. If the unit has sufficient column strength, the rollers may engage the wire at points outside of this perpendicular plane. This structural arrangement may be necessary when the size of the rollers used prevents them from lying in the same plane without interference with each other.
This invention is useful in many applications, such as a hand held welding gun or as a device for moving wire. For example, it may be desirable to place a reel of wire at one location and move this wire through a substantial length of cable to another location. Since frictional forces increase with the length of the cable, merely providing a source of motive force at either end of the cable may not be sufficient to move the wire without damage. A wire feeding mechanism of the type described above could be installed at one or more intermediate locations to provide the additional force needed to move the wire under these circumstances.
It is desirable to maintain the wire in tension throughout the length of the cable due to the low column strength of small diameter wires, and for this reason, the intermediate wire feeding mechanisms located closest to the wire source are designed to tend to move the wire at slightly slower speeds than those located further from the wire source.
In other applications, it may be desirable to maintain the wire in compression throughout its length, and to do this, the intermediate wire feeding devices are designed to move the wire at a slightly higher speed than the wire feeding device located at the output end of the cable. Of course, the force exerted by these intermediate devices should be less than that which will over come slipping within the output device.
It has been found that by using one device to push the wire into a cable, and another device to withdraw the wire from the cable, the total energy required to move the wire may be reduced considerably over those installations where only one such device is used. This decrease in the power required is primarily due to minimizing the frictional contact of the wire with the internal surfaces of the cable.
Also, the wire feeding apparatus of this invention may be designed so that it will not damage the wire if the wire is restrained from movement while the rotary to linear actuator continues to rotate. In other words, an intermediate source of motive force could be run continuously, if desired, even though the wire may be stalled, thus eliminating the need for extra switching circuits, or it may be operated as a constant torque device with' appropriate electrical circuitry.
For steel wire, the contact force between the rollers and the wire may be set to permit the actuator to run at a constant speed while allowing the wires to slip relative to the actuator without damaging the wire. It is also within the scope of this invention to increase the force exerted by the biasing means on the rotors so that the rollers will track with the wire and to provide a constant torque device so that the actuator will rotate at different speeds, as determined by the wire feed rate.
For aluminum wire, however, it has been found that the actuator should not be allowed to run at constant speed with the rollers slipping on the wire since this causes spalding. It has also been found that if the force exerted by the biasing means is reduced, sufficient force to feed the wire is not available. If too much biasing force is provided, then the wire might be damaged.
Sufficient force to move the wire may be obtained by providing a plurality of sets of inclined rollers, thus distributing the forces along the wire. In order to obtain the sufficient driving force for wires having low tensile strength, such as aluminum, while at the same time avoiding distorting or damaging the wire, several pairs of inclined rollers may be used with each roller exerting less force than those rollers which are used to move steel wire. In one embodiment of the invention, four pairs of mutually opposed inclined rollers are used for steel while eight pairs of mutually opposed rollers are used to impart the same driving force to aluminum wire.
It has been found that in some situations, especially where it is not intended that the wire slip relative to the actuator, it is preferred that the biasing force exerted by the rollers be increased to cause significant deformation of the surface of the wire at the point of engagement with the rollers. In some embodiments, this biasing force is increased until there is some yielding of the surface of the wire. As a result, the driving force imparted to the wire will be greater than that which would be expected if only the coefficient of friction between.
the wire and the rollers is considered.
In a welding gun, a gas passageway for inert shielding gas may be formed in the gun housing to direct the gas around the motor and the rotary to linear actuators.
The gas flow will cool the motor and remove dirt and wire surface contaminates carried by the wire which may be knocked loose by the inclined wire engaging rollers and would otherwise build up in the gun housing.
By using the rotary to linear actuator of this invention, the gear box normally employed between the motor and the drive roll has been eliminated and the motor connected directly to the wire actuator with the speed of the wire feed controlled by the speed of the.
motor and the angle of contact between the wire feeding rollers and the wire.
Accordingly, it is an object of this invention to provide an improved feeding device for cylindrical members comprising a rotatably mounted body having means defining a member receiving opening therein, a plurality of member engaging free turning drive rollers mounted for rotation with said body and positioned with respect to the opening through said body to engage a cylindrical member fed therethrough.
Another object of this invention is to provide an improved feeding apparatus of the type described including the combination of a drive motor having an axially extending opening in its armature through which a cylindrical member may freely pass and a rotary to linear actuator including a plurality of wire engaging rollers with the axis of the rollers radially spaced from and at an angle to the axis of rotation of the actuator to engage the cylindrical member and move it linearly in response to the rotation of the actuator.
Another object of this invention is to provide an improved wire feeding apparatus employing the rotary to linear motion actuator as described above wherein the means for driving the actuator is axially aligned with the actuator, thus providing feeding apparatus of small cylindrical dimensions.
Another embodiment of this invention is to provide a wire moving device wherein a plurality of rollers are mounted for rotation with a body having an axial opening through which wire may pass, the rollers having their axis inclined to the axis of rotation of the body and engaging the wire to impart a linear component of force as the body is rotated, and means urging the rollers into engagement with the wire to cause sufficient deformation of the surface of the wire at the point of engagement with the rollers whereby the driving force imparted to the wire is greater than that which would exist if only frictional forces were present.
Another object of this invention is to provide an improved wire moving apparatus which includes a body having an axially extending opening through which wire may pass, a plurality of rollers mounted on the body for rotation therewith, the axis of each roller being inclined relative to the axis of the body, and at least one movable arm mounted on the body for supporting one of the rollers, the movable arm including sufficient mass properly located to counterbalance at least the centrifugal force acting on the roller as the body is rotated.
Another object of this invention is to provide an improved wire moving apparatus of the type described wherein at least one of the wire engaging rollers is carried by an arm mounted on the body, the mass of the arm being designed to counterbalance substantially the centrifugal force acting on the roller, and biasing means to urge the roller into contact with the wire so that the contact force is due substantially entirely to the biasing means and is substantially independent of the speed of rotation of the body.
Another object of the invention is to provide an improved wire moving apparatus of the type described wherein at least one roller is mounted upon an arm the mass of which is designed so that the force of the roller against the wire will increase as the rotational speed of the body is increased.
Another object of this invention is to provide an improved rotary to linear actuator for feeding cylindrical members, such as wire, of the type described wherein a pair of opposed inclined rollers are carried by arms pivotally mounted to a rotating body, one end of each arm including centrifugal weights which will urge the rollers into positive engagement with the member as the body is rotated to impart linear motion to the member.
It is another object of this invention to provide an improved apparatus for moving a cylindrical member of the type described including biasing means for urging the roller against the member. In one embodiment, each roller supporting arm is mounted on the body by a torsion bar which is arranged to preload and urge the roller into engagement with the member. In another embodiment, springs preload the rollers into positive contact with the member.
It is a further object of this invention to provide a feeding mechanism of the type described which is selfthreading, that is, which readily accepts and thereafter moves a cylindrical member fed into the actuator and which accepts wire diameters over wide ranges due to its self adjusting construction.
Another object of this invention is to provide an improved apparatus for moving wire, particularly for moving welding or filler wire through substantial lenghts of cable while maintaining the wire in tension.
by designing or operating the wire feeding mechanism located closest to the source of wire to move the wire at a slightly slower speed than those wire feeding mechanisms located further from the wire source.
Another object of this invention is to provide an improved wire moving apparatus whereby the wire feeding mechanism located closest to the source of wire tends to move the wire at a slightly higher speed than those wire feeding mechanisms located further from the wire source thereby to keep the wire in compression.
Another object of this invention is to provide a novel rotary to linear actuator wherein the force for moving a wire can be increased by adding additional rollers, while maintaining the contact force of the rollers against the wires below that which would cause damage or substantial yielding of the wire surface.
Another object of this invention is to provide a novel rotary to linear actuator wherein a plurality of sets of rollers may be employed to move the wire with one or more of the rollers of subsequent sets forming tracks on the wire which are coincident with the tracks formed by previous sets of rollers thereby to minimize distortion of the wire surface due to contact with the rollers.
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS wire feeding apparatus of this invention contained in a spot welding gun; FIG. 3 is a cross sectional view taken along line 3 -3 in FIG. 2; 7
FIG. 4 is a view of a gas diffuser used in the embodi-.
ment of FIG. 3;
FIG. 5 is an end view of an end connector for inert gas, welding current and motor power for use in the embodiment of FIG. 3;
FIG. 6 is an enlarged view of a wire feeding assembly employing two pairs of mutually opposed rollers;
FIG. 7 is a view of the wire feeding assembly taken along line 7--7 in FIG. 6;
FIG. 8 is another view of the wire feeding assembly taken along line 8-8 in FIG. 6;
FIG. 9 is a view of another embodiment showing an alternate placement of biasing springs relative to the roller supporting arms;
FIG. 10 is a view showing the body member of the wire feeding assembly of this invention and one of the supporting bearings for mounting the assembly in a welding gun;
FIG. 11 is a view showing particularly an inclined roller and its relation to the actuator body member;
FIG. 12 is a perspective view of a roller supporting arm and centrifugal weight;
FIG. l3 is a view of the roller carrying arm showing particularly a slot formed therein;
FIG. 14 is a diagrammatic view showing the relationship of the wire engaging rollers to each other and to the welding wire;
FIGS. ISa-lSc show various cross sectional configurations of rollers which may be used in this invention;
FIG. 16 is a pictorial view showing an embodiment of the roller carrying arm and centrifugal weight when the roller is inclined in the opposite direction;
FIG. 17 is an end view of another embodiment of the invention wherein a torsion bar is employed to mount the roller carrying arms on the body;
FIG. 18 is a side view showing the relationship of the torsion bar to the body and to the roller carrying arms;
FIG. 19 is a cross sectional view taken along lines l919 of FIG. 18;
FIG. 20 is an end view of a portion of an actuator showing another embodiment of the invention wherein each arm is mounted on the body by a torsion bar;
FIG. 21 is-a cross sectional view taken along line 21-21 in FIG. 20;
FIG. 22 is a view showing four pairs of mutually opposed inclined rollers mounted on a single body member;
FIG. 23 is a view showing an alternative embodiment wherein a single motor rotates two rotary to linear actuators in opposite directions and wherein the rollers of one actuator are inclined in a direction opposite of the rollers of the other actuator in order to eliminate any tendency for twisting the wire as it is moved linearly through the actuator;
FIG. 24 is a view, partly in cross section, of a spot welding gun wherein the rotary to linear actuators run continuously and wire movement controlled by wire gripping means;
FIG. 25 is an exploded perspective view of still another embodiment of the invention wherein two sets of rotary to linear actuators are employed, each set including three rollers spaced 120 about the wire;
FIG. 26 is a cross sectional view taken on a line through one set of inclined rollers;
FIG. 27 is a cross sectional view taken along line 27-27 in FIG. 26; and
FIG. 28 is a cross sectional view taken along line 28-28 in FIG. 27.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, the wire moving apparatus of this invention may be included in either a hand held welding gun 10 or in one or more boosters or intermediate wire moving assemblies 12 located between the hand held gun 10 and a reel of welding wire 14, as shown in FIG. 1. Welding wire 15 is moved through a cable 17 which is also adapted to carry shielding gas and electrical current to the welding gun 10. The wire and the gas is directed under the control of an operator through a nozzle 18 to a workpiece 20.
The operator controls the flow of gas and the welding wire by a manually actuated switch 22 carried by the gun It). This switch may be connected to a remotely located control box 25 by wires carried in the cable 17. The control box 25 regulatesthe flow of gas from a gas source 26 and the application of electrical current to the gun 10 through hose 27 and wire 28, respectively.
As shown in FIG. 1, the wire moving apparatus of this invention is used in the hand held gun 10 to draw wire from cable 17 and to direct the wire through nozzles 18 to the workpiece. In thosewelding situations where the distance between the gun It) and the wire source 14 exceeds the capacity of the wire moving apparatus, one or more boosters 12 are used to pull the wire off the reel 14 and to assist in the movement of the wire through cable 17 to the hand held gun 10.
By designing the wire moving apparatus so that substantially no yielding of the wire surface occurs, the booster 12 may be operated continuously, if desired, even though the wire may be stalled since slippage between the wire and the wire moving mechanism of this invention does substantially no damage to the wire of the type which might causewelding problems.
The wire moving apparatus of this invention may be used in many devices, such as the hand held gun 10, an intermediate wire moving assembly or booster l2, and a spot welding gun 30. The automatic or semiautomatic welding gun in FIG. 2 includes a nozzle 31 which is designed to receive and direct shielding gas to the area being welded on the workpiece. This type of gun may be used, for example, in spot or seam welding applications. Welding wire is directed to the workpiece through an electrically conductive guide tube 32 located centrally in the nozzle 31. The details of the wire guide and nozzle form no part of the present invention, however, no electrical current flows through the welding wire 15 until it exits from the wire guide 32 since current is applied through the guide to the wire through a sliding connector.
The wire feeding apparatus of this invention includes two rotary to linear actuators 35 and 36 which are rotated simultaneously by an electric motor 37. It is to be understood that hydraulic or pneumatic motors could also be used if desired. In the embodiment shown in the drawings the rotary to linear actuators 35 and 36 and the motor 37 are provided with axially extending openings through which the welding wire is moved toward and through the wire guide 32.
One end of each rotary to linear actuator 35 and 36 is attached to the armature or rotor shaft 38 of motor I 37. The other end of each actuator is supported by bearings 41, and these bearings are carried by support disks 43. As shown in FIG. 3, each disk 43 includes a plurality of holes 44 surrounding the bearing 41, and these holes provide a passageway for shielding gas to pass around the bearing, through the gun, and into the' nozzle where it is then directed over the weld. A portion of the gas may flow through the guide tube 32 with the wire.
The motor 37 is supported within the gun 30 in a slotted cylindrical inner casing'45 formed in two sections to facilitate assembly of the gun. Disks 43' are surrounded by a cushioning material 46, such as rubber, and are also supported within the gun by the inner casing 45. As shown in FIG. 2, the inner casing 45 is provided with a plurality of longitudinally extending slots 47, the length of whch exceeds the length of the motor in order to provide a passageway around the motor for shielding gas. The entire gun 30 is enclosed with an insulating cylindrical tube 50 which not only protects the mechanism within the gun but also provides electrical insulation and protection to the operator.
The gun 30 includes an electrically conductive male metallic connector 55 located within the cylindrical tube 50 to receive shielding gas, welding wire, control wires, and electrical current from the cable 17. The
connector 55 may be formed integrally with the lower half of the casing 45. Electrical current from cable 17 flows through the connector 55 and casing 45 around 65 are aligned with the openings 59 and support electrical pins 66 which extend through the connector 55 to the exterior of the gun housing. In the preferred embodiment, four such pins are employed and are used for the control of the speed of motor 37. These pins may also be connected to control switches, such as switch 22 shown in FIG. 1. The connector pins are insulated from the metallic connector 55 by epoxy filling the opening 59.
The openings 64 communicate with a recess 68 formed in the diffuser element 63, and shielding gas which passes through opening 58 into the recess 68 then passes through the opening 64 in diffuser element 63 and the holes 44 and disk 43 to the interior of the motor housing. This shielding gas flows around the actuator 35, through the slot 47 surrounding the motor 37, around the actuator 35 and through corresponding openings 44 in the disk 43 at the left end of the assembly and into the nozzle 31 where it is then directed to the weld.
The movement of the gas around the motor 37 tends to cool the motor thus allowing continuous operation of the motor under heavy loads without exceeding its temperature limits. The gas also flows around both rotary to linear actuators 35 and 36 and carries any dirt or wire contamination which might be dislodged by the interaction between the rotary to linear actuators and the wire passing therethrough. This flow of gas therefore removes these contaminates from the gun housing.
Rotary to linear actuator 35 is shown in detail in FIGS. 6 through 13 and includes a mandrel or body 75 having a cylindrical right end 76, a cylindrical left end 77, and a generally centrally located flange 80 which is provided with a plurality of threaded holes 81. As shown in FIG. 10, the left end 77 is pressed into the bearing 41. The body 75 may be machined or formed from either metal or from a synthetic material, such as laminated fiber. As best shown in FIG. 10, an opening or aperture 82 extends completely through the body and is coaxial with the axis of rotation of the actuator 35. The opening 82 is sufficiently large to permit the largest diameter wire to be used in the embodiment shown, to pass through the actuator body without inteference.
The axial opening 82 is enlarged at 83, at the right end of the body as viewed in FIG. 10, to receive the drive shaft 38 of motor 37. In the preferred embodiment, splines prevent relative rotation between the drive shaft 38 and the body 75. Alternatively, the drive shaft 38 could be secured to the body 75 by set screws. The drive shaft 38 is also provided with an axially aligned opening 84 to allow the wire 15 to pass through the motor into the opening 82 and then outwardly from the actuator 35 to the workpiece.
A pair of arcuately shaped arms 90 are pivotally attached to each side of the flange 80 by screws 91 which are received into the threaded openings 81. Preferably, the screws 91 are provided with shoulders which permit them to be tightened securely to the flange 80 while at the same time allowing the arms 90 to pivot freely around the body of the screw. As shown in FIG. 12, each arm 90 is provided with an opening 92 which is slightly larger than the body of the screw 91.
The wire engaging roller 95 is rotatably mounted to the inwardly extending portion 96 of each arm 90 by screws 97. These screws also include a shoulder which allows them to be tightened securely to the arms 90 without restricting the freedom of rotation of the rollers 95. Each of the inwardly extending portions 96 includes a threaded opening 98 which is adapted to receive the screws 97 (FIG. 12). Of course, rivets may also be used to support the rollers 95 for rotation. The inwardly extending portion 96 of each arm 90 also has formed thereon a flat surface 99 which is perpendicular to the axis of the threaded opening 98 to permit free rotation of the roller 95.
The threaded opening 98 is therefore the axis of rotation of the rollers 95 and is seen to be spaced radially outwardly from the wire 15 and is inclined at an acute angle A relative to the axis of rotation of the body 75, as viewed in FIGS. 6 and 11. The angle A mayvary from -0 to 90, however in the preferred embodiments, the angle is normally between 5 and 45.
In the embodiment of the invention shown in the accompanying drawings, rollers are used to move wire which may vary in size from 0.030 to 0.080 inch. These rollers are inclined at an angle of 20 when moving steel wire. This results in a linear movement of 0.039 inch per revolution for 0.035 inch wire. Therefore, at a motor speed of 10,000 rpm, the wire is moved through the actuator at 390 inches per minute. For aluminum wire, the rollers are inclined at an angle of 30 with a corresponding increase in the linear speed of the wire. The angle is chosen according to the desired speed ratio between the angular velocity of the body and the longitudinal feed rate of the wire 15. The rollers 95 on one side of the flange are arranged in mutually opposed relation with respect to the wire 15 to prevent any unnecessary bending of the wire.
Thus, as the body 75 rotates, the rollers 95 will follow a helical path on the wire 15 and since the rollers are prevented from moving longitudinally relative to the body, a component of force will thus be imparted to the wire to move it longitudinally through the opening 82.
As shown in FIG. 14, when more than one pair of mutually opposed pairs of rollers are employed, the rollers are generally evenly spaced around the wire 80. In FIG. 14, the rollers 95 are mutually and diametrically opposed, i.e., their points of contact are perpendicular to wire 80. Rollers 95 are also mutually opposed, longitudinallly spaced from the rollers 95, and their points of contact with the wire are from the points of contact of rollers 95. The spacing between rollers and 95 is preferably such that the rollers 95' will form tracks on the wire which are coincident with the helical tracks formed by rollers 95. When this is not possible, the tracks formed by the pairs of rollers are separated sufficiently that it will not unduly work the surface of the wire. This is particularly important when aluminum wire is being moved by the rotary to linear actuator.
Each arm 90 includes an integrally formed arcuately shaped weight located on the opposite side of the pivot screw 91 from the rollers 95. As the body 75 rotates, the weights 105 will tend to move outwardly due to centrifugal force, and the mass of these weights and of the arms themselves are so designed that they will at least counteract the centrifugal force acting on each roller 95 and that portion of the arm on the other side of the pivot screw 91. In one embodiment of the invention, the centrifugal force is substantially counterbalanced and therefore the force applied by the roller to the wire will be due to external biasing means and will be independent of the speed of rotation of the body. In another embodiment of the invention, the weights 105 cause additional force to be applied. by the rollers against the wire so that this force will increase as the rotational speed of the body is increased. In this embodiment, the mass of the arms 90, the rollers 95 and the weights 105, and the rotational speed of the body, along with any external biasing means, will determine the actual force exerted by each roller against the wire.
Biasing means are provided to urge the rollers 95 against the wire 14. In that embodiment of the invention wherein the centrifugal forces acting on the rollers are substantially counter-balanced, this biasing means supplies substantially all of the biasing force. In the embodiment of the invention wherein the centrifugal force acting on the weights 105 supplies a substantial portion of the bias, the biasing means insures that adequate force is applied to the rollers to urge them against the wire, especially at low rotational speeds of the body 75.
In the embodiment shown in FIG. 7, the biasing means includes small springs 1 which act to push the weights 105 outwardly. These springs also act to push the corresponding roller on the opposite side of the wire into the wire. The springs 110 are received into retaining cups 111 formed in the weight 105 and cups 112 formed on the inwardly extending portion 96. It is also contemplated that the springs could interact between the weights 195 and the body 75 with substantially the same results.
An alternative embodiment is shown in FIG. 9 and includes springs 113 acting between arms 90 and the body 75. The springs are held in place by screws 114 which also are used to adjust the biasing force of the springs.
Each of the arms 90 is also provided with slot 115 positioned opposite the roller of the complementary arm on the same side of the flange 80. This slot provides a relief and permits any accumulation of wire coating compound which may be removed by interaction of the wire with the rollers 95 to be thrown outwardly and away from the actuator 35. This prevents a buildup of dirt and prevents interference between a roller 95 and the weight 105 on the adjacent arm. Movement of inert gas around the actuators also aids in removing this dirt.
The body 75, as shown in FIG. 10, is formed or machined with a slot 120 having sufficient width to accommodate the rollers 95 and a depth such that the opening 82 through the center of the body is exposed. A slot 121 is also provided to accommodate the shaft of the milling tool which forms the opening 120, if this machining process is used, and to accommodate the screw 97 which holds the roller 95 in place. The depth at which the slot 120 is cut depends in part upon the range of wire sizes which are to be accommodated by any particular actuator 35, it being desired that there be no interference between the roller 95 and the body 75 when feeding wires of the smallest diameter is contemplated.
FIG. shows the cross sectional configuration of rollers which may be used with this invention. FIG. 15a is the roller configuration used in the preferred embodiment in that it allows the wire 15 to be easily inserted into and through the actuator since the wire may cam the roller outwardly against the biasing means. The roller shown in FIG. 15b has a narrow contact area and may be used in those situations where high forces per unit area against'the wire are desiredThe roller configuration of FIG. 150 has also been used with the rotary to linear actuators of this invention and give two points of contact for each roller. A tungsten carbide roller surface is preferred due to its wear characteristics.
Another embodiment of the invention is shown in FIGS. 17 through 19 wherein the means for biasing the rollers into engagement with the wire 15 includes torsion bar 140 extending through opening 141 in flange 80. In FIGS. 17 and 18, only one arm on either side of the flange is shown for the purpose of clarity in illustration. It is to be understood, however, that the complementary arms on both sides of the flange will also be installed.
In this embodiment, torsion bar 140 pivotally supports arms located on either side of the flange 80 and is rigidly secured to each arm, but not to the flange 80. The torsion bar is provided with knurled or splines on each end which are forced into openings 92 in the arms 90. The torsion bar is encircled by a cylinder 142 where the torsion bar passes through the flange 80 in the opening 141, and the torsion. bar and the two roller supporting arms 90 are held in the opening 141 by a ring 145 which completely encircles the flange.
As the wire 15 is moved through the central opening 82 in the body 75, the rollers 95 on opposite sides of the flange which are supported by the arms carried by one torsion bar 140 will be urged outwardly by the wire and will therefore cause the torsion bar to twist. Of course, the twist of the torsion bar is designed to be less than the yield strength of the material from which the torsion bar is made. Typically, a 5 deflection will be all that is needed in order to apply sufficient biasing to the rollers to assist in moving-the wire 15 at low rotational speeds of the body 75.
Another embodiment of the invention wherein a torsion bar is used as the pivotal support for the arm 90 is shown in FIGS. 20 and 21. In this embodiment, flange 80 is provided with an opening 147 which receives the torsion bar 150. The torsion bar has a large diameter section 151 near its head which is splined and received into the opening 147 and is prevented from moving relative to the flange 80 by the splines. A reduced section 152 is allowed to move freely within the opening 147, and a further reduced section 155 is forced into a smaller opening 156 in the arm 90 and is also prevented from movement relative to the arm by splines. Thus, one end of the torsion bar is secured to the flange 80 and its other end is secured to the arm 90.
As previously mentioned, the force per unit area on the wire must be controlled in order to prevent damage to the wire as it moves through the rotary to linear actuators. With some wires of low tensile strength, such as aluminum, it may be desirable to distribute the forces acting on the wire in order to provide the necessary wire moving force. This may be done in several different ways, such as by providing a plurality of actuators 35, as described above, or providing a single actuator having a plurality of rollers mounted thereon.
With wires of higher tensile strength, more force per unit area can be exerted on the wire without causing substantial damage thereto. It has been found that in most cases it is desirable to elastically or plastically deform the surface of the wire at the point of engagement with the rollers since this will improve the wire moving or driving force imparted to the wire over that which can be expected if only frictional forces alone were present. As a practical matter, plastic deformation or yielding of the wire surface will actually occur since the biasing forces acting on the rollers are not controlled to the degree necessary to prevent yielding.
For example, when using a 1/16 inch steel welding wire wiped clean of lubricant, and using a rotary to linear actuator employing three inclined rollers which engage the wire in a plane substantially perpendicular to the direction of wire movement, with each of the rollers being biased by 12 pound springs into the wire, for a total of 36 pounds force acting radially on the wire, it has been found that driving force on the wire equals approximately 3.3 pounds when using the roller design of FIG. 15A, for a ratio of driving force to applied radial force of 0.092. But when using the roller configuration of FIG. 158, the driving force is increased to pounds, or a ratio of 0.56. Similarly, when using 1/16 inch aluminum wire with the same setup, a driving force of 3.0 pounds was obtained using the roller of FIG. 15A for a ratio of 0.083, and a driving force of 14.3 pounds was obtained when using the roller of FIG. 158 for a ratio of 0.40. It was found that the driving force was substantially the same either with the wire being moved through the actuator or with the actuator holding a static load. It is apparent therefore that the roller of FIG. 15B actually causes yielding or plastic deformation of the wire surface to form a thread in the wire and therefore the force imparted to the wire to move it through the actuator is substantially greater than that which is obtained by friction alone.
It has also been found that where a plurality of rollers are used to move the wire, it is desirable that the rollers be so spaced on the wire that they will create the minimum number of tracks. In other words, the set of rollers which engage the wire subsequent to a previous set will be so spaced that they will form tracks on the wire coincident with the tracks formed by the first set. This prevents excessive working of the wire surface and results in a lower power requirement since the surface of the wires does not have to be distorted by the second or subsequent set of rollers.
For small diameter wire, e.g., 0.020 inch and smaller, and with wires of low tensile strength, e.g., solft aluminum or non-heat treated magnesium, there is a tendency for the rotation of the actuator to twist the wire. To eliminate this twisting tendency, the apparatus shown in FIG. 23 may be used. Here, two rotary to linear actuators are rotated in opposite directions by a motor 170 which is mechanically connected to the actuators 171 and 172 through a gear assembly 175. The rollers in the actuator 171 are inclined relative to the wire in a direction opposite to the inclination of the rollers in actuator 172 so that the wire will move in the same direction, from right to left, as viewed in FIG. 23, through the welding gun even though the actuators ar rotating in opposite directions.
FIG. 16 shows an arm 90 which has mounted thereon a roller 95 which is inclined in a direction opposite to a roller mounted on the arm shown in FIG. 12. Of course, the body design and particularly the orientation of the slots 120 and 121 in the body must be modified in order to accommodate this roller orientation. Of course, the body 75 would then have to be rotated in the opposite direction in order to move the wire linearly in the same direction.
In a spot welding application where accurate control of the wire movement is required, it is desirable to eliminate the inertial effects in-starting and stopping the linear actuator and motor used to drive the actuators. Since no substantial damage to the wire occurs while it is stalled, even though the actuators continue rotating, accurate control over the movement of the wire may be obtained by including wire gripping means, such as a solenoid brake, to control the movement of the wire while allowing the actuators to rotate continuously. One embodiment of the invention using this principle is shown in FIG. 24. Here, wire 15 is directed through rotary to linear actuators 35 and 36, and a timer controlled solenoid brake controls the movement of the wire. The actuator motor 37 is supplied with power through a constant voltage source 181 and rotates the actuators continuously. A timer 185 allows movement of the wire for predetermined periods of time, either automatically or under the direction of a separate control circuit 186. For example, the timer 185 may allow the wire to move for 0.4 second at six second intervals or for 0.4 second each time a trigger pulse is generated by the control circuit 186. Accurate movement of the wire through small distance increments is therefore provided by this arrangement.
FIGS. 25 through 28 illustrate another embodiment of the invention which includes two sets of actuators each having three inclined rolls mounted in a single body unit. The device includes a body member 200 having formed therein a plurality of radially extending openings 202-207. The body also includes an axial opening 210 through which wire may pass and about which the body is rotated. As viewed in FIG. 27, the right hand portion of the body member 200 has an enlarged axial opening 211 which is coaxial with and larger in diameter than the opening 210 to accommodate the shaft of a motor. A set screw 212 secures the motor shaft to the body member.
The openings 202-204 in one set and the openings 205-207 in the other set are angularly spaced 120 apart. Each opening receives a tubular member 215 which supports a roller 216 for rotation about an axis 217. The axis 217 of each roller is inclined relative to the axial opening 210. Thus, the rollers 216 will engage a wire passing through the axial opening 210 at 120 intervals, and since the axis of these rollers is inclined relative to the wire, rotation of the rollers around the wire will cause the wire to move in a linear direction through the body.
In the embodiment shown in FIGS. 25-28, the rollers engage the wire at points within a plane perpendicular to the wire. It is also contemplated that the rollers may be designed to engage the wire at locations outside of this perpendicular plane if the wire has sufficient column strength to withstand the force exerted by the rollers without significant bending. This may be necessary in some cases where the diameter of the rollers will not permit them to contact the wire in a perpendicular plane without interference with each other.
The upper portion of each of the tubular members 15 is slotted at 220 to receive a bar 221, and this bar has a radially extending opening 222 which receives a cylindrical member 223, and this member is secured to the bar by a pin 224.
An arm 230 is pivotally mounted on the body by a pin 231 which extends through openings 232 in the body and an opening 233 in the arm. The arm includes a bifurcated section 235 which engates a cutaway portion 236 of the cylindrical member 223. Thus, as the arm 230 rotates in a counterclockwise direction as viewed in FIG. 25, this forces the rollers 216 in both sets into the wire.
The arm 230 also includes a cylindrical weight 240 which acts to counterbalance substantially the centrifugal force acting upon the rollers as the body 200 is rotated. As mentioned previously, this weight may also be adjusted to supply additional biasing force to urge the rollers into engagement with the wire as the rotational speed of the device is increased, if this result is desired.
The device also includes biasing means in the form of a spring 245 which acts between the body 200 and the centrifugal weight 240 to urge the arm 230 to rotate in a counterclockwise direction. The magnitude of the biasing force can be adjusted by a set screw 246. In the embodiment wherein the centrifugal weight substantially counterbalances the entire centrifugal force acting on the rollers, the spring 245 provides substantially the entire biasing force of the rollers against the wire, and this force will be independent of the rotational speed of the device.
While only one centrifugal weight assembly is shown in FIG. 25, it is clear from FIGS. 26-28 that three armweight-spring assemblies are included with each assembly cooperating with one roller in each of the two sets of rotary to linear actuators. It is also clear that where only one size of wire is to be accommodated by such a device, two of the three rollers within one set may be mounted so that they do not move radially with the third roller including the centrifugal weight-spring arrangement described above in order to provide the necessary biasing of the rollers against the wire.
By using three rollers supported on radially mounted arms, wires or welding electrodes of different diameters may be accepted by the device while maintaining the wires centered on the axis of rotation of the body. In one embodiment constructed according to the teachings of this invention, wire sizes from 0.30 to 0.93 inch were accepted by the same device without requiring adjustment of the arms or spring tension by the operator.
In still another embodiment of the invention where only one size of wire is to be moved by the rotary to linear actuator, all of the rollers may be mounted so that they do not move radially with respect to the wire. The wire receiving opening which is determined by the wire engaging portions of the rollers would be adjusted so that it is less than the diameter of the wire so that as the wire is fed into the device, distortion of the wire surface will result. In this case, the actuator will impart a driving force to the wire which is greater than that which would exist if only frictional contact were present. As a practical matter, yielding of the wire surface will probably result since the wire diameter is usually not maintained within precise tolerances. The wire may be fed easily into this type of device by taper-ing the rollers, such as shown in FIGS. 15a and 15b.
Thus, a rotary to linear actuator has been described which employs centrifugal weights to counterbalance at least the centrifugal force acting on the rollers as the device is rotated. The rollers are urged into frictional engagement with the wire by springs, torsion bars, or by additional centrifugal weight. The biasing force on the rollers may be adjusted to distort the surface of the wire in the area of engagement to provide a linear driving force which is greater than that which would exist if only frictional forces were present. Also, an improved welding gun or other wire feeding apparatus has been described which includes a motor having a central opening extending axially therethrough to rotate the rotary to linear actuators. Such coaxial construction permits fabrication of welding guns and wire feeding mechanisms having small cross sectional areas.
While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to these precise forms of apparatus, and that changes may be made therein without departing from the scopeof the invention which is defined in the appended claims.
What is claimed is: 1. A wire moving device comprising a body having an axis about which it may be rotated; means defining an axially extending opening in said body through which wire may pass;
at least one free turning roller mounted on said body for rotation therewith, said roller having a wire engaging surface which imparts to the wire a linear component of force to move the wire axially through said body;
an arm mounted on said body for supporting said roller; and
a centrifugal weight on said arm which, as said body is rotated, acts to counterbalance at least the centrifugal force acting on said roller.
2. The device of claim 1 wherein the wire engaging surface of said roller lies in a plane perpendicular to the axis of rotation of said roller and whrein said axis of rotation is inclined relative to the axis of said body.
3. The device of claim 1 further including means for biasing said roller against the wire.
4. The device of claim 3 wherein said biasing means is a spring positioned between said body and said arm.
5. The device of claim 3 wherein said biasing means is a torsion bar mounting said arm to said body to bias said roller against the wire.
6. The device of claim 1 wherein a pair'of rollers are supported on arms pivotally mounted on said body, said rollers engaging the wire at diametrically opposed locations. v
7. The device of claim 1 wherein a set of three rollers are each supported on arms pivotally mounted on said body and engage the wire at points in a plane perpendicular to the wire.
8. The device of claim 1 wherein a pair of rollers are supported on arms and engage the wire at diametrically opposed locations, said device further including springs which act against the centrifugal weights on one of said' pair of arms and against the roller supporting portion of the other of said pair of arms.
9. The device of claim 1 further including means biasing said rollers against the wire with a force to cause 11. The device of claim 1 wherein said centrifugalweight provides a substantial portion of the force said roller exerts against the wire as the body is rotated.
12. The device of claim further including biasing means to urge said roller against the wire to provide sufficient roller engaging force to move the wire at low rotational speeds of said body.
13. The apparatus of claim 1 wherein the axis of rotation of each of said rollers is at an acute angle relative to a plane including the axis of rotation of said body, said angle being selected according to the speed ratio desired between the rotation of the body and the axial movement of the wire.
14. The device of claim 1 further including a second plurality of rollers mounted on said body for rotation therewith in axially spaced relation to said plurality of rollers with one or more of the rollers of said second plurality of rollers forming tracks on the wire coincident with the tracks formed by said plurality of rollers.
15. A wire moving device comprising a body having an axis about which it may be rotated;
means defining an axially extending opening in said body through which wire may pass;
at least one roller mounted on said body for rotation therewith, the axis of said roller being inclined relative to the axis of said body, said roller engaging the wire to impart thereto a linear component of force as said body and said roller are rotated;
an arm mounted on said body for supporting said roller; and
a centrifugal weight on said arm which, as the body is rotated, acts to counterbalance at least the centrifugal force acting on said roller as said body is rotated.
16. A wire moving device comprising a body having an axially extending opening through which wire may pass and about which said body may be rotated; at least one free turning roller mounted for rotation with said body with the axis of said roller being inclined relative to the axis of said body, said roller having an outer circumferential surface which engages the wire to impart thereto a linear component of force to move the wire axially as said body is rotated; and
means urging said roller into engagement with the wire with sufficient force to cause deformation of the surface of the wire at the point of engagement whereby the driving force imparted to the wire will be greater than that which would exist if only frictional forces were present.
17. The device of claim 16 wherein said rollers are urged into engagement with the wire with sufficient force to cause yielding of the surface of the wire at the point of engagement with said rollers.
18. The device of claim 16 wherein said rollers are mounted on said body with the wire receiving opening formedby the wire engaging portion of said rollers being less than the diameter of said wire.
19. The device of claim 16 wherein at least one of said rollers is movably mounted on said body, and wherein said urging means is a spring.
20. The device of claim 16 wherein at least one of said rollers is movably mounted on said body and wherein said urging means includes a torsion arm mounting said rollers to said body.
21. The device of claim 16 further including a second plurality of rollers axially spaced on said body from said plurality of rollers axially spaced from said plurality of rollers so that said second plurality of rollers will form tracks on the wire coincident with the tracks formed by said plurality of rollers.
22. A self-contained wire moving device, comprising a hollow housing having a wire 'entry end and a wire feeding end; a mandrel rotatably mounted in said housing having means therein defining a wire receiving aperture generally axially aligned with said housing for receiving a wire from the wire entry end and delivering the same to said wire feeding end;
a plurality of wire engaging free turning drive rollers mounted for rotation on said mandrel and positioned with respect to said aperture for driving engagement with the surface of the wire and having axes which form a common angle with the axis of said aperture to effect an axial driving force to the wire with the rotation of said mandrel;
means mounting said rollers on said mandrel, said means including arms, one for each of said rollers, with said rollers being mounted adjacent one end of an associated said arm, means pivotally mounting each said arm on said mandrel providing for generally radial movement of the associated said roller with respect to said wire aperture, the opposite ends of said arms comprising counterweights subject to centrifugal force upon rotation of said armature at least counteracting the centrifugal force acting on said rollers; and
means for effecting rotation of said mandrel to cause movement of the wire through said wire feeding end.
23. The wire moving device of claim 22 wherein said common angle is between 5 and 45.
24. The wire moving device of claim 22 further comprising bias means urging said rollers generally radially inwardly against said wire.
25. The wire moving device of claim 22 in which said mandrel rotation means comprises an electric motor received in said housing and having a rotor in axial alignment with said mandrel, means directly coupling said rotor to said mandrel, and means in said rotor defining a wire feed opening in substantial axial alignment with said mandrel aperture providing for substantial unrestricted movement of the wire through said mandrel and said rotor.
26. The wire moving device of claim 25 further including means defining a gas passageway in said housing for directing gas around said motor and said wire moving device thereby to cool said motor and to carry away dislodged wire surface contaminates to the exterior of said housing.
27. A wire moving device comprising a hollow housing having a wire inlet end and a wire outlet end; 7 actuator means mounted for rotation within said housing for moving a wire in a linear direction as said actuator is rotated about the wire;
a motor within said housing for rotating said actuator means; and
means for introducing gas into said housing and for directing said gas over said actuator means and around said motor thereby to cool said motor and to carry wire surface contaminates dislodged by said actuator means to the exterior of said housing.
28. A wire moving apparatus for use especially with small diameter and/or low tensile strength wires including first actuator means for moving a wire linearly in a first direction as said first actuator means is rotated clockwise about the wire;
second actuator means for moving said wire linearly in said first direction as said second actuator means is rotated counterclockwise about the wire; and
means for rotating said first and second actuator means clockwise and counterclockwise, respectively, whreby said wire is moved in a linear direction through said apparatus without any net twisting of said wire due to the rotation of said actuator means about the wire.
29. In a wire moving system including a plurality of actuator means for moving a wire in a linear direction as said actuator means are rotated about the wire wherein the actuator means located closest to the wire source tends to move the wire at a slower speed than for rotation around the wire with the axis of said rollers being inclined relative to the wire to impart thereto a linear component of force, wherein the speed at which said actuator means tends to move the wire is determined by the angle of said rollers, and wherein all of said actuator means are rotated around the wire at the same speed.
Disclaimer 3,7 44,694.-D0n0mm Karnes and Marion F. OfltliUQT, Troy, Ohio. APPA- RATUS FOR MOVING WIRE. Patent dated July 10, 1973. Disclaimer filed Oct. 18, 197 3, by the assignee, H Obart Brothers Company. Hereby enters this disclaimer to claim 28 of said patent.
[Ofiiez'al Gazette May 27,1975.]
Disclaimer 3,744,694.D0n0mm Kames and Marion F. Uenth'wer, Troy, Ohio. APPA- RATUS FOR MOVING WIRE. Patent dated July 10, 197 3. Disclaimer filed Oct. 18, 1973, by the assignee,H0ba1-tBrothers Oompany. Hereby enters this disclaimer to claim 28 of said patent.
[Ofiicial Gazette May 27,1975]