US 3309061 A
Description (OCR text may contain errors)
arch 14, 1967 R. F. PLATTNER STRAPP ING TOOL 3 Sheets-$heet 1 Filed April 9, 1959 gINVENTOR jty iaibzev Boberi March 14, 1967 R. F. PLATTNER STRAPPING TOOL 5 Sheets-Sheet 5 Filed April 9, 1959 United States Patent Ofliice 3,309,061 Patented Mar. 14, 1967 3,309,061 STRAPPING TOOL Robert F. Plattuer, Park Forest, 11]., assignor to Interlake Steel Corporation, a corporation of New York Filed Apr. 9, 1959, Ser. No. 805,173 2 Claims. (Cl. 25451) This invention relates to improvements in stretchers of the type which are used to draw binding strap taut around a package preparatory to uniting the overlapping ends of the strap by means of an interlocking joint or the like.
In many strap stretching tools the strap ends, either singly or together in overlapping relationship, are gripped between a pivoted upper gripping member which can be moved in and out of strap gripping position and a cooperating stationary gripping member or strap seat which is either a part of, or connected to, the main frame of the stretching tool. These co-operating gripping members are so mounted as to present parallel opposing gripping surfaces to the opposite sides of the strap or straps.
These gripping members are self-actuating i.e., they are so mounted that as the tension in the strap loop increases the force with which the gripping members bear against the strap also increases. Since either or both of the gripping members are ordinarily mounted in a cantilever fashion from the main frame of the stretching tool, the force exerted by the co-operating gripping members against each other through the strap tends to deflect the members angularly relative to each other to thereby bring them into non-parallel relationship with one another.
When the co-operating gripping members are not parallel to each other, they grip the strap along one of its edges rather than across its entire width. The consequent reduction in bearing contact permits slippage of the gripping members over the strapwhich causes the teeth of the gripping members to mill off metal from the strap. As the teeth fill up with this metal the slippage increases and makes it diflicult if not impossible to maintain tension in the strap loop. Still a greater problem caused by the uneven or eccentric bearing contact is that it creates cam-her in the strap being tensioned because the gripping members elongate the edge of the strap which they contact, especially as the strap tension increases and the gripping members grip tighter. Camber, or longitudinal curvature transversely of the edges of the strap, is objectionable because it impairs the threading and gripping of the strap in subsequent strapping cycles.
In the embodiment of the invention described in this specification, the upper gripping member is a rotary gripping member or rotary tensioning wheel which performs the double function of gripping the overlapping strap ends and also of drawing the strap loop taut about an object or bundle. However, the problem of maintaining the gripping surfaces of the gripping members in parallel relationship is essentially the same as with nonrotary gripping members and the solution offered by this invention applies equally well to either type.
It is therefore an object of this invention to overcome the problems mentioned by providing means associated with the strap gripping members of a strapping tool for maintaining the gripping surfaces of the upper and lower gripping members in parallel relationship when the strap is under tension, even though deflection occurs in varying amounts. More specifically, it is an object of this invention to provide in a strap stretching tool a strap seat which adjusts itself automatically to remain parallel to the tensioning or gripping members so that the bearing force of the gripping members is distributed evenly across the face of the strap.
Other objects and improvements of the invention should become apparent by referring to the accompanying drawings in which FIG. 1 shows a side elevation of an improved strap stretching tool embodying the present invention with the operating lever in a normal operating position;
FIG. 2 shows a top plan view of the strap stretching tool illustrated in FIG. 1;
FIG. 3 is a somewhat diagrammatic illustration of the use of the tool shown in FIGS. 1 and 2 during the binding of a box or package;
FIG. 4 shows an end elevation of the tool shown in FIGS. 1 and 2;
FIG. 5 shows a sectional view taken on the line 5-5 of FIG 1;
FIG. 6 is a partial sectional view as viewed approximatedly along the line 66 of FIG. 2 and particularly shows details of the gripping members and the ratchet means used for actuating the rotary gripping member, the structure between the rotary gripping member and the ratchet means not being shown for the sake of clarity;
FIG. 7 shows a partial sectional view as viewed along the line 77 of FIG. 6; and
FIG. 8 shows a sectional view as viewed along the line 8-8 of FIG 7.
As illustrated in the drawings, the invention is embodied, as an example, in a strap stretching tool com prising a frame 10 having a base plate 10a adapted to rest upon a box or package or other objects to be bound. This frame is provided with an integrally formed handle 10b which is adapted to be engaged by one hand of the operator for the purpose of holding the tool in its proper operating position on a box or package to be bound, such as the box 11 shown in FIG '3. The base plate 10a is provided with two lateral projections or flanges 10c and 10d which can be referred to as strap seats since they are adapted to underlie the metal binding strap 12 while this strap is being drawn taut around the box or package. The strap 12 may be with-drawn from a coil 13 and it is first extended around the box or package 11 with the free end 12a thereof extending over the flange 10c and somewhat beyond that flange toward the right as viewed in FIG. 3. The supply portion 12b of the strap, after being extended around the box or package 11 into the form of a loop 126, is carried over the flange 10d and above the strap extremity 12a above the flange 100. The loop around the box or package may then be contracted manually to a considerable extent preliminary to the operation of the tool for drawing the strap taut around the box or package.
The mechanism by which the strap is drawn taut is actuated by a lever 15 which is provided at one end with a ball 15a adapted to be engaged by one hand of the operator and which is adapted to be reciprocated in a vertical plane to actuate the strap tightening mechanism.
This actuating mechanism comprises a yoke 16 which is pivotally mounted upon a pin 17 extending through apertures in two lugs c and 10] which are formed integrally with the base plate 10a. The yoke 16 has two parallelarms 16a and 16b which extend transversely to provided atits lower end with two spaced side plates b and 15c which extend between the arms 16a and 16b of the yoke and which are apertured for engagement by portions of theshaf-t 19. The side plate 15b is rotatably mounted upon the reduced portion 19a and the side plate 150 is rotatably mounted upon an enlarged ring portion 19b ,of the'shaft. Between the parts 19a and 19b, the shaft 19 is provided with a fluted portion 19c which has a splined engagement with a ratchet wheel 20 adapted to be operated by the reciprocation of the lever 15 for the purpose of effecting the rotation of the shaft. The reduced portion 19a of the shaft terminates in a threaded part 19d which is engaged by a washer 21 and a nut 22 for holding the shaft in position in its bearing.
An enlarged portion 190 of the shaft which extends loosely through the aperture 16c of the arm 16b, is connected to a fluted portion 19 which has a splined engage-s ment with the disk 25a of a cup-shaped gripping wheel or rotary tensioning wheel 25. The arm 16b of the yoke is provided with a cylindrical projection 16d upon which a cylindrical bearing member 26 is secured with a press fit and the cylindrical gripping portion 25b of the gripping member is journalled upon the bearing member 26. The shaft 19 terminates internally of the gripping member 25 and bears against a washer 27 which contacts the head of a screw 28 which is threaded into the shaft'19 to hold thev grippingmember in driving engagement with the shaft. The cylindrical portion 25b of the gripping member is provided with an annular series of diagonal teeth 1 25c which are adapted to engage the upper side of the strap 12 above the flange 10c of the frame. This flange 100 is provided with a recess 60in the form of a channel.
having two side walls 60a and 60b connected to a bottom wall 60c and extending transversely of the tool from the lug 10f'out to the free edge of the flange 10c. Within this recess is mounted a gripping plate 29 which is provided along a portion of its upper surface, immediately below the region of the cylindrical gripping member 25, with upwardly projecting teeth 29a which are arranged along an upwardly convex arch as best viewed in FIG. 6,, the arched shape extending transversely from one side of the gripping plate 29 to the other. These teeth 29a are adapted to coact with the underside of the strap end 12a to hold it against endwise movement above the flange 10c of the frame during the rotation of the gripping wheel 25 for the purpose of drawing the supply strap end 12b across the strap end 12a and drawing the strap loop 12c taut about an object being bound.
The gripping plate 29 is provided with two surfaces 29c and 29d which extend slightly angularly upward from a ridge 29e which extends transversely across the bottom of the gripping plate plate recess 60. While resting on this ridge 292, the gripping plate 29 can be rocked on the ridge 2912 as a pivot or fulcrum angularly relative to the bottom wall 600 of the recess 60, the limits of the angular movement being determined by contact of either the surface 29c or 29d with the bottom wall 600. The purpose of the angular or rocking movement is to permit the upper level of teeth 29a in contact with the strap end 12a to remain parallelto the level of the teeth 25c on the cylindrical gripping member 25 eventhough the flange 10c deflects downward angularly relative to the member 25 asrindicated in phantom' lines at 10c in FIG. 7. (It is assumed that deflection of the supporting structure for the member 25 also occurs. However, it is the resulting relative angular positions of the, member 25' and the flange 10c which is compensated 29 and along which the gripping 29 ordinarily rests on the bottom wall 600 of the.
4.7 for, regardless of which part deflects or deflects the most.) Experience has shown that'severe deflection of the parts occurs especially at high strap tensions, and increases as,
the tensionincreases. With the arrangement of this invention characterized by the rocking movement of the gripping plate 29, the gripping plate 29 and the gripping member 25 remain parallel to the strap and to each other even though deflection of the parts occurs and regard- This pin 62 consists of a wrapped spiral of a stripof.
resilientsteel or other metal, which spiral shape is shown in FIG. 8. The purpose of the pin 62 is to, first, retain the gripping plate 29 in the recess 60 and, second, to deflect and yield by contraction and expansion of the spiral to permit the rocking movement mentioned of the gripping plate 29 relative to the flange 100. It is conceivable that other forms of this pin are possible and it is not intended that the invention be limited to this particular shape shown.
The rotation of the gripping wheel 25 is effected through the shaft 19 by the ratchet wheel 20, which, in turn, is actuated by the reciprocating lever 15 through a pawl- 33 which has an arm 33a adapted to be engaged by the fingers of the operator and a tooth 33b adapted to engage the teeth 20a of the ratchet wheel 20. The pawl 33 is pivotally' mounted on a pin 34 which extends between the side plates 15b and 15c of the lever 15. A coil spring 35 is mounted on the pin 34 within a slot 330 which exends transversely through the pawl 33. This spring has one arm 352 which engages a shoulder 15d on the lever and it'has another arm 3512 which engages one wallof the slot 330 so that the. spring acts normally to move thepawl 33 into a position where .thetooth 33b engages a tooth 20a of the ratchet wheel as shown in FIG. 1. In the nor-maloperation of the tool, the lever 15 is reciprocated toward andfrom the handle 10b with the result that the tooth 33b of the pawl engages the ratchet wheel teeth to effect the rotation of the ratchet Wheel 20 upon the movement of the lever 15 toward the handle 10b, but upon reverse movement of the lever, the tooth 33b then slides over the teeth of the ratchet wheel as permitted by the compression of the spring 35.
Between successive tensioning strokes of the hand lever 15, the ratchet wheel 20 and the feed wheel 25 are both held in positions to whichfthey have been advanced by means of a' detent 37, best, shown in FIGS. 2, 4 and 6, which is. pivoted on a pin 38 extendingbetween the upstanding lugs 10c and 10fin which the pin .17 is mounted. The .detent 37 has a tooth 37a which is adapted to engage the teeth 20a of the ratchet wheel to hold the ratchet wheel and the feed wheel against reverse rotation. During a forward stroke of the hand lever 15 toward the right as viewed in FIG. 1, the detent 37 slides over the teeth of the ratchet wheel with which it is normally maintained in contact by a coil spring 39 mounted on the. pin 38 in a slot which is formed in the detent.
The feed wheel 25 is norm-ally maintained in contact with the strap 12 being operated upon by means of a coil spring Aflwhichextends between thelug 10 of the where the peripheral surface, 25b of the feed wheel will engage the upper surface of the uppermost strap 12b seated on the flange 10c of the frame. This normal feeding position of the feed wheel 25 is adapted to be regulated by an adjusting screw 43 which extends through a threaded aperture of the frame to engage the lower edge of the yoke 16 at a point removed from the pivot pin 17, as shown particularly in FIG. 1. Thus, the normal gripping position of the feed wheel 25 may be regulated to cause this member to perform properly upon metal straps of various thicknesses.
For the purpose of elevating the gripping wheel 25 away from the strap and from the flange 100, which is desirable when the stretching tool is about to be removed from a box or package which has just been strapped, means are provided for swinging the yoke 16 upwardly about the pivot pin 17 until it occupies an elevated position with the rotary gripping member 25 well above the strap gripping position. For this purpose, the pawl 33 is provided adjacent to the tooth 33b-with a cam surface 33d. The normal retracted position of the hand lever is shown by full lines in FIG. 1, but when the lever is swung beyond this position to that shown by the dotted lines in FIG. 1 the cam surface 33d engages a fiat cam surface 10g which is formed on the handle 10b, so that the tooth 33b of the pawl then coacts with a tooth of the ratchet wheel to raise the yoke 16 upwardly with the heel of the cam 33d resting on the flat cam surface 10g.
From the foregoing description it will be apparent that there has been provided a strap stretching tool operated by a hand lever which is reciprocated to effect a gradual tightening of a strap around an object being bound and that the tensioning mechanism is automatically held during the reverse strokes of the hand lever. After the strap has been drawn taut, a joint between the overlapping end portions of the strap may be formed either in the region 48, at the left of the tool as shown in FIG. 3, or in the region 49 between the flanges 10c and 10d. The location of the joint in the latter position may be preferable because it involves some saving in the strap which may be cut off from the supply at the left of the flange 10c, as viewed in FIG. 3.
It should also be apparent that an improvement has been provided in such a tool which is also applicable to other tools of the same general nature for tensioning a binding strap about an object to be bound. The particular nature of the improvement concerns itself with providing a gripping plate 29 which can pivot on its support to compensate for deflection of parts of the tool it is associated with in order to insure uniform pressure across the entire width of strap being gripped between another gripping member and the gripping plate 29, and thereby eliminate slippage of the strap over the gripping members and resultant formation of camber in the strap due to uneven gripping pressure as otherwise might prevail.
Although only one form of the invention is shown and described by way of illustration, it will 'be understood that it may be constructed in various other ways without departing from the true scope of the appended claims.
1. A tool for applying tension to associated strapping encircling an object to be bound, said tool comprising in combination a frame having a laterally extending foot adapted to engage the object and provided with a recess on the surface thereof disposed away from the object, a clamping member carried by said foot and disposed in said recess and adaptedfrictionally to engage a first longitudinally extending run of strapping in overlying relation with respect thereto, said clamping member being mounted upon said foot for rocking movements laterally of the longitudinal axis of the first run of strapping, a tensioning wheel carried by said frame and positioned opposite said clamping member and adapted to overlie a second longitudinally extending run of strapping disposed in overlying sliding contact with the first run of strapping, said tensioning wheel having a substantially cylindrical outer surface adapted frictionally to engage the adjacent surface of the second run of strapping, said tensioning wheel being mounted upon said frame for rotation about its own axis extending laterally of the second run of strapping, said mounting of said tensioning wheel upon said frame accommodating movement of said tensioning wheel toward said clamping member and into clamping position with both runs of strapping disposed between said tensioning wheel and said clamping member and accommodationg movement of said tensioning wheel away from said clamping member and into releasing position with the runs of strapping, means for rotating said tensioning Wheel in a strapping tensioning direction When it occupies its clamping position, whereby the outer surface of said tensioning wheel in frictional engagement with the second run of strapping slides the same longitudinally along the adjacent surface of the first run of strapping in order to effect tightening of the strapping around the encircled object, said mounting of said clamping member upon said foot accommodating rocking movements of said clamping member laterally of the runs of strapping in order to maintain the parallelism between the facing surfaces of said clamping member and said tensioning wheel when said tensioning wheel occupies its clamping position and is rotated in the tensioning direction, and a pin interconnecting said clamping member and said foot to hold said clamping member in said recess while accommodating the rocking momevents thereof, the surface of said clamping member disposed toward said foot and the surface of said foot disposed toward said clamping member having cooperating rocking parts within said recess to accommodate the rocking movements of said clamping member laterally of the runs of strapping, wherein said pin is resilient and yields readily to accommodate the rocking movements of said clamping member with respect to said foot.
2. A tool for applying tension to associated strapping encircling an object to be bound, said tool comprising in combination a frame having a laterally extending foot adapted to engage the object and provided with a recess 0n the surface thereof disposed away from the object, a clamping member carried by said foot and disposed in said recess and adapted frictionally to engage a first longitudinally extending run of strapping in overlying relation with respect thereto, said clamping member being mounted upon said foot for rocking movements laterally of the longitudinal axis of the first run of strapping, a tensioning wheel carried by said frame and positioned opposite said clamping member and adapted to overlie a second longitudinally extending run of strapping disposed in overlying sliding contact with the first run of strapping, said tensioning wheel having a substantially cylindrical outer surface adapted frictionally to engage the adjacent surface of the second run of strapping, said tensioning wheel being mounted upon said frame for rotation about its own axis extending laterally of the second run of strapping, said mounting of said tensioning wheel upon said frame accommodating movement of said tensioning wheel toward said clamping member and into clamping position with both runs of strapping disposed between said tensioning wheel and said clamping member and accommodating movement of said tensioning wheel away from said clamping member and into releasing position with the runs of strapping, means for rotating said tensioning wheel in a strapping tensioning direction when it occupies its clamping position, whereby the outer surface of said tensioning wheel in frictional engagement with the second run of strapping slides the same longitudinally along the adjacent surface of the first run of strapping in order to effect tightening of the strapping around the encircled object, said mounting of said clamping member upon said foot accommodating rocking movements of said clamping member laterally of the runs of strapping in order to maintain the parallelism between the facing surfaces of said clamping member and said tensioning wheel when said tensioning wheel occupies its clamping position and is rotated in the tensioning direction, and a pin interconnecting said clamping member and said foot to hold said clamping member in said recess while accommodating the rocking movements thereof, the surface of said clamping member disposed toward said foot and the surface of said foot disposed toward said clamping member having cooperating rocking parts within said recess to accommodate the rocking movements of said clamping member laterally of the runs of strapping, wherein said pin is in the form of a fiat metal strip wound into a spiral, said clamping member and said foot having aligned openings therein receiving said pin therein, said pin winding and. unwinding slightly in response to the pressure supplied to said clamping member to accommodate the rocking movements thereof.
References Cited by the Examiner UNITED STATES PATENTS 2,638,314 5/1953 McFe'rren et al 2545l 2,9343 18 4/1960 Schultz 2- 254-51 2,964,295 12/1960 Hall et a1. 254-51 FOREIGN PATENTS 524,055 4/ 1956 Canada; 721,177 12/ 1954 Greatt Britain.
WILLIAM FELDMAN, Primary Examiner.
OTHELL M. SIMPSON, Examiner.