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Publication numberUS3195702 A
Publication typeGrant
Publication dateJul 20, 1965
Filing dateNov 16, 1960
Priority dateNov 16, 1960
Publication numberUS 3195702 A, US 3195702A, US-A-3195702, US3195702 A, US3195702A
InventorsAlexander Robert H
Original AssigneeRockwell Mfg Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for controlling tightness of fasteners
US 3195702 A
Abstract  available in
Images(3)
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Claims  available in
Description  (OCR text may contain errors)

July 20, 1955 R. H. ALEXANDER I 3,195,702

APPARATUS FOR CONTROLLING TIGHTNESS OF FASTENERS Filed NOV. 16, 1960 3 Shegts-Sheet l July 20, 1965 R. HQ ALEXANDER APPARATUS FOR CONTROLLING TIGHTNESS OF FASTENERS July 20, 1965 R. H. ALEXANDER APPARATUS FOR CONTROLLING TIGHTNESS OF FASTENERS Filed Nov. 16, 1960 3 Sheets-Sheet 5 IN VEN TOR. ROBERT H. ALEXANDER I ATTORNEYS zez 3 United States Patent M 3,195,132 APPARATUS FOR CQNTRGLLENG TEGHTNESS 0F FASTENERS Robert H. Alexander, Miarnishurg, (lhio, assignor, by

mesne assignments, to Rockwell P/lauufacturing Company, Pittsburgh, Pa, a corporation of Pennsylvania Filed Nov. 16, well, Ser. No. 69,756 14 Qlaims. (Cl. 192-.tl%)

The present invention relates to an apparatus for controlling the tightening of fasteners, particularly threaded fasteners such as nuts, bolts, certain types of screws, and the like.

Experiments in the field of control tensioning of fasteners have shown that in many instances there is less variation between the tension in like fasteners if a constant or relative uniformly controlled energy is used for tightening like fasteners. The precise reasons for this have not been determined, however experiments have shown this to be a fact. The present invention provides such a constant energy source for use in tightening fasteners to provide a substantially uniform tension in like fasteners, and this invention also provides a method whereby like fasteners may be tightened to produce substantially uniform tensions therein.

Accordingly, the primary object of this invention is to provided a novel apparatus for tightening fasteners, in

which a substantially constant tension is induced in such fasteners by controlling the amount of energy imparted thereto in tightening.

Another object of the invention is to provide a rotary impacting tool which may be regulated to strike a predetermined number of blows automatically and then to stop, requiring resetting by the operator before further impacts can be delivered.

Another object of this invention is to provide a novel rotary impact tool in which the lapse of time of operation of the tool following the first impact blow delivered thereby can be adjusted, followed by automatic shut oii of the tool to prevent further impacting.

Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings:

FIG. 1 is a view of a rotary impacting tool constructed in accordance with the invention, with the drive mechanism and a portion of the control therefor broken away and shown in vertical section;

FIG. 2 is a view similar to FIG. 1 with the parts in relatively moved position;

FIG. 3 is a vertical section taken through the rear of the apparatus, and particularly through the rotary pneumatic motor and the control valves therefor;

FIG. 4 is a sectional view of the control valves taken on line 4-4 of FIG. 3;

PEG. 5 is a vertical section on an enlarged scale through the handle and adjacent portions of the tool body, show ing the controls for the tool in accordance with the invention;

FIG. 6 is a view similar to PEG. 5, showing the parts in a moved position;

FIGS. 7 and 8 are sectional views on a somewhat reduced scale showing further positions of portions of the controls shown in FIG. 5;

FIG. 9 is a sectional view of a portion of the controls shown in FIGS. 5 and 6, with the parts in a further moved position;

FIG. 10 is a sectional view on a reduced scale, taken on line 1i1ll of FIG. 5;

HG. 11 is a sectional view similar to FIG. 5, of a modified form of the invention; and

dddEflhZ Patented July 2%, 1965 FIG. 12 is a somewhat schematic View of a further modification of the invention, showing an electrical equivalent of the pneumatic apparatus shown particularly in FIGS. 1-8.

Referring to the drawings, which illustrate preferred embodiments of the invention, a preferred form of the tool is a pneumatic impact wrench of the rotary type, adapted to operate from a suitable source of compressed air, and as shown in FIGS. 110, having a main body or casing 10 and depending handle 12 which the operator may grasp to hold and manipulate the apparatus. Adjacent the juncture of the handle with the body there is a trigger 15 slidably mounted in the handle and positioned for manipulation by a finger of the operator. The nose portion of the body Till, shown particularly in FIGS. 1 and 2, carries a bushing 17 within which there is mounted a rotary anvil 18 including an output connector 19 of irregular cross-section adapted to be coupled to a suitable driving tool such as a socket, bit, or the like. The portion of anvil 18 located within housing it), and of larger diameter, includes a plurality of lugs it? which project rearwardly thereof and form abutments for receiving blows from a hammer 22 which in turn is provided with complementary striking lugs or surfaces 23.

The hammer is rotated, in either direction as selected, by a rotary spindle 24 having a driving head 25 in which are formed a plurality of grooves 2s receiving balls 28. These balls in turn are seated within complementary grooves 29 in the hammer, and the grooves 25 and 29 are formed of generally V-shape, along the axis of rotation, such that if the hammer 22 is held stationary continued rotation of the spindle in either direction will produce a withdrawing axial movement of hammer 22 against the bias of spring 38. Further details and a complete eX- planation of such a system are found in United States Patent No. 2,166,150, issued May 30, 1939.

The spring 39 seats upon a stationary ring 31 which is carried by a retainer bushing 32, which in turn rests against the enlarged portion 34 of the spindle. This portion forms the cage element of a planetary gearing system which may be incorporated in the tool, and this cage in turn carries a plurality of planet gears, one of which is shown at 35 mounted upon bearings 36 through which extends planet shaft 37, and these shafts are in turn held in place by engagement with the bushing 32 and against a portion of the rear supporting ball bearing 38 which carries the rearward end of the driving spindle. The planet gears mesh with a stationary internal gear 4t) which is suitably held in stationary position within the housing it), and these gears are driven by a pinion 4-2 formed on a drive shaft of a reversible rotary pneumatic motor indicated by the general reference numeral 47 (FIG. 3

This motor includes a cylinder or barrel 48 mounted within the rear of the casing It and a rotor 50 which is located eccentrically within the barrel 48 and attached to drive the shaft 45. A plurality of blades 52 are carried by rotor 50, axially slidable therein, and engage with the walls of the barrel 48 as shown. The barrel also cooperates with casing it) to form the chambers within which a pressure fluid, such as compressed air, is introduced through the inlet chamber 54 and passage 55 to produce rotation of rotor Si by reaction against the blades 52. An exhaust port 56 is provided at the opposite sides of the motor, opening into an exhaust chamber 57 (FIG. 1), and which may lead to suitable muffler constructions (not shown) to muffie any obiectionable sound of the air under pressure exhausting from the tool.

At the base of the handle 12 there is a connector or internally threaded plug all for coupling to a source of pressure fluid for driving motor 47. A suitable source, for example, might be a flexible hose connected to a high pressure air system operating, for example, at around 90 psi. The upper end of the plug member 60 is formed with an internal chamber 62, and a ball control valve 65 is located within this chamber, normally biased to close against a seat '66 by .a spring 67. This spring is held within the chamber by a retainer ring 68 threaded into the plug member 60. At the lower end of. chamber 62, around the spring 67, there are a number of radially extending passages 69 which open into into an annular groove or passage 70 about the side of the plug member 69, and when this member is seated properly in place the passage 70 communicates with a control passage 72 leading upwardly through the handle to a short cross passage 73 which in turn opens into a cavity 74 for receiving the housing '75 of the trigger 15 and the servo ball valve 77 which is controlled by the trigger. r

The housing 7-5 includes a :rear chamber 89 into which the ball 77 is received, and which communicates with the cross passage 73, and a seat 82 against which the ball 77 is normally urged by the pressure of air in passage 72. Thus, pressure fluid is normally cut off from the forward control chamber 85 in housing 75, and within this chamber there is an extension or control rod 86 of reduced diameter projecting from the rear of trigger 15 and surrounded by a spring 87 which normally biases the trigger forward into the position shown in FIG. 5, such that the rod-like portion 86 will not interfere with seating of ball 77. Movement of the trigger is limited by a pin 88 mounted crosswise in housing 75 and extending partially into a crossed slot 89 formed in the trigger 15. Thus, when the trigger is depressed by an operator, ball 77 will be unseated to admit pressure air to chamber 35 and this air then flows outwardly throughthe outlet passage 90 to initiate opera 'tion of the tool.

Referring particularly to FIGS, 3, 4, 5, 6 and 9, immediately above the seat 66 in the plug body 60 there are a number of cross passages 92 extending from a central cavity 93 on the opposite side of seat 66 from ball 65, and opening into an annular passage 94. This passage in turn opens into a motor air supply passage 95, portions of which are shown in FIGS. and 6, and the upper portion of which is shown in FIGS. 3, 4 and 10. passage terminates at its upper end in the bore 97 in body which extends'lengthwise of the body adjacent to the juncture of the handle 12 therewith. The directional control valve 100 is rotatably received in a sleeve 1&1 within the bore 97, and is suitably slotted on opposite sides, as shown generally at 102 such that air may be directed selectively to either the motor air supply line 55, for forward rotation, or to the reverse rotation supply passage 55a, and the 0p- -posite supply passage connected to exhaust to prevent a recompression resistance from air carried by the blades past theexhaust port 56. Details of such a reversing valve are 'well known in the art, and the rotation of the plug valve 100 to produce such selective direction of the pressure air supply is under the control of a conventional knob 193 extending outwardly beyond the portion of the housing which contains the valve.

Accordingly, opening of valve 77 by depression of trigger will not directly supply pressure air to motor 47 but will serve only to initiate opening of valve 65, as will presently be described, to provide for passage of motive pressure fluid into chamber 95 and thus to the directional control valve 100 for driving the motor in the desired direction. As noted, valve 65 is normally biased closed by spring 67. On the opposite side of the ball valve 65 there is a control pin 105 having an enlarged head 106 received within chamber 93 and adapted to engage ball 65. This pin is slidably mounted within an extension 108 of the plug body 60, and about this timed operation of the impacting tool.

extension there is a cutoff control piston 116 which is freely slidable about the extension 198 and within a counterbore 112 formed in the end of a control mechanism housing 114. This housing is received in stationary relation within the bore 115 which projects upwardly through the handle toward the trigger mechanism, and into which is threaded the plug body 61) at the lower end of the handle.

The housing 114 includes an upper chamber 119 in which is mounted a servo piston 120, and this chamber opens into the servo outlet passage 94 from the trigger. Piston 120 is normally biased upward, toward the top of chamber 119, by a spring 122, and the piston includes a rod portion 123 extending slidably through a bore 124 in the housing, and terminating in a carrier 125 which is of generally inverted U-shape, the forward arm thereof being broken away in FIGS. 5, 6 and 9, while the other "arm is shown in elevation. This carrier provides a mountcontrol. pin 105, as shown particularly in FIG. 5. Be-

neath the carrier and the pawls, surrounding the extension 108 and slidably mounted thereon, is the main cutoff control piston 1 10, and this piston is suitable sealed to both the extension-108 and the counterbore 112 within which it slides as shown. A main positioning and control spring 133 surrounds the carrier and the pawls, and seats at one end upon piston 110 and at its other end against the housing 114.

The piston 110 is provided with an annular control cam surface 149 which is adapted to engage within the cam surfaces 135 on the pawls, and when forced between the pawls to separate their lower ends against the force of spring 132, to open or separate the lugs 136 and permit control pin to pass therebetween, as shown particularly in FIG. 9. The power for so moving the control piston 110 is provided by selectively supplying air under pressure to chamber 142 beneath this piston, and above plug body 69, through a control passage 145, portions of which are seen in FIGS, 5, 6, 9 and 10.

Accordingly, when the trigger 15 is depressed and servo ball valve 77 unseated thereby, air under pressure enters through passages 72 and 73, and through chamber 80 past the servo valve into the servo outlet passage 9t). This pressure air acts upon ser-vo piston 120 to depress it against spring 122, and carrier 125 likewise moves downwardly carrying pawls 130 into engagement with the control pin 105, and since spring 132 is active to bring the actuating lugs 136 toward each other, these lugsengage the pin and depress and open the main air supply ball valve 65. Motive fluid is thus supplied through passages 92 and 95 to the directional selective valve 160, and thence to motor 47.

The motor will drive the spindle 24 in the selected direction, and this spindle in turn, through the ball and V-groove connection 26, 28, 29, will rotate hammer 22. Once the fastener being operated upon otters sufiicient resistance to rotation of anvil 18, the anvil will be stopped and the ball and V-groove mechanism will cause hammer 22 to retract against spring 36 until the lugs 23 and 20 disengage, whereupon the hammer will accelerate forward in both a rotary and axial direction to reengage the lugs 30 a d 23,, Striking a blow on the anvil 18.

At the first such retraction of the hammer 22, to initiate the impacting operation, a signal is provided to commence operation of the control piston 110, thus beginning the In the embodiment shown in FIGS. 1, 4, 5, 7 and 8, the mechanism are provided for this purpose includes a follower siidably mounted within a housing 152 which in turn is press fitted in a bore 153 (FIG. 5) in the body it). The follower has a projecting ear 155 which extends into an annular slot 157 at the rear of hammer Z2, and thus axial motion of the hammer will produce sliding movement of the follower 15%, while free rotation of the hammer is unimpaired.

Referring particularly to FEGS. 5, 7 and 8, the follower 156 is provided with a slotted rearward end 152; which receives a pawl 160 mounted on a cross pin hi2. This pawl is normally urged to a canted position, engaging one side of the bore within which the follower 15d slides as shown particularly in FIGS. 5 and 7. For this purpose, a ball 163 engages the pawl is pressed by spring led against the back edge of the pawl, offset from the of rotation provided by pin 162..

Rearwardly of the follower and pawl there is a tapered annular cam surface 165 extending into a passage Hi7 of reduced cross-section which in turn opens toward a valve body 163 mounted in bore 153 and threaded thereto at 169. The control rod 179 of a metering valve 172 extends through this passage and centrally through the cam surface 165. The metering valve head is normally seated upon an O-ring 174 or other suitable seal, being held thereon by a light spring 175 which is received in valve sleeve 177 and held in place by a closed retainer cap 179 threaded into the end of the body 163. Air under pressure is supplied to the interior of valve sleeve 177 through radially aligned passages 178 formed in such sleeve and in the body 163, and these passages communicate with a cross passage is!) (FIG. 4) connected into the direction control valve inlet passage 95 such that air is always supplied through this passage regardless of the direction of rotation selected. These passages 178 are sealed oil at opposite sides by the O-ring seals 132 (FIG. 4) to retain the pressure air on the upstream side or" metering valve 172 in non-operating condition. Downstream of the metering valve head and the O-ring seat 174 is a further passage 385' including radially extending passages 187 which open into the main control air supply passage 145, and this passage is confined (around body 1:32) by one of the O-rings 182 and a further forwardly mounted {Hing 1&8 (FIG. 4).

Accordingly, for every axial movement of hammer 22, and thus of follower 150, the pawl 16% will slide against the metering valve control rod 17% and will open the metering valve 172 to admit :air under pressure through the control passage 145 into the chamber 142 below the main control piston 11%. As the follower and pawl continue to move, to the right as viewed in FIGS. 5, 7 and 8, the pawl will engage cam surface 165 and further move ment of the follower and pawl will cause the pawl to be centered by the cam surface and the metering valve control rod 179 will then line up with the internal opening 161 of the pawl, and spring 175 will act to seat and close the starter valve. However, since an amount of air under pressure was thus admitted into the control passage 145 and chamber 142, the main control piston 116 will be pumped up against spring 138 and subsequent closing of the starter valve will seal the control passages and the control piston will remain essentially in its moved position. Subsequently actuations of the starter valve by pawl 160, and further admissions of pressure air into the main control passages will cause the main control piston to rise further, in direct relation to the number of times that the hammer 22 strikes a blow. With the main valve 65 in the open position shown in FIG. 6, as the main control piston 11% continues to rise its cam surface 149 will subsequently engage the cam surfaces 135 on pawls 13a, and the pawls will be urged apart against spring 132. Thus the control pin 185 will be forced upwardly between the pawls by reason of the combined effect of air pressure and the pressure of spring 67 upon the main ball valve 65. This valve will seat and close off the supply passage d5 to terminate the supply of motive fluid to the motor, and the tool will stop.

When the motor stops, the operator will thus know that the timed impacting operation has been accomplished, and that a constant amount of energy, assuming that each blow struck by the hammer upon the anvil produces essentially the same force, has bmn applied to tighten the fastener. When the operator releases trigger 15 it will be returned to its forward position by spring 87, and this will exhaust air from the chamber above servo piston 12%, with such air passing through the servo outlet passage Qtl, the chamber 85, and through an exhaust or venting passage 1% which is opened when the trigger is completely released, as shown in FIG. 5. At the same time, the area below the servo piston and above the main control piston lid is also continuously vented through vent passage 192. and the cross passages 1% to assure that no air is trapped within these parts to prevent completely free movement in response to actuation by either the air pressures thereon or the respective springs.

With the supply of air to the motor cut off, and thus no further supply of air under pressure to passage 95 the pressure within this line will drop considerably. A cross passage 20% is provided in the handle (FIG. 10) between the motor supply passage 95 and the control passage 14-5 and this cross passage is normally closed by a ball 2&2 seated upon an O-ring 2% due to the high pressure air in motor supply passage d5 when the tool is operating. However, when this pressure drops the pressure air within passage lid-5 and beneath the main control piston 11d will force the ball 262 to unseat, and the spring 133 will then return the control piston 119 to the bottom of the counterbore 112, the position shown in FIG. 5. The tool is then prepared for a further operation, which can be initiated H by depression of the trigger by the operator to start the timed impacting cycle again.

By controlling the size of the orifice defined by the metering valve 172 when it is opened, it is possible to meter a predetermined amount of pressure fluid into the control passage for each impact or blow delivered by hammer 22. Thi may be accomplished conveniently by threading the body 168 to adjust its axial position, thus controlling the spacing between rod 17% and pawl lied, and changing the amount of opening of valve 172 for each stroke of pawl 15%). Accordingly, for each tightening operation the hammer will deliver a predetermined number of impacts, which number is definite and constant for each cycle, and then stop, and an essentially constant or predetermined amount of energy is delivered to tighten the fastener in each cycle or" operation or the tool.

As mentioned at the beginning of the specification, the basic objective is to utilize a substantially constant energy for the tightening of the fasteners. The apparatus above described provides such constant energy tightening by controlling the number of impacts which the rotary impacting tool delivers to the fastener. It is also possible to time the operation of the impacting tool from the first impacting blow and thus to permit the tool to strike impacting blows for a predetermined length of time, the number of impacts delivered thus being dependent upon the lapse of time from the first blow,

FIG. 11 shows a modified form of starter valve, and in this figure like reference numerals have been applied to parts which are identical to those shown in FIGS. l-lt). It will be noted that even the starter valve housing 152 is of the same construction, and all parts not shown in FIG. 11 are of the same construction as previously described. Thus, the operation of the trigger will result in air under pressure being supplied through passage 5 to the radial passages 178 in the housing 152, and these passages are normally closed by a modified starter valve 21th which is slidably received within the housing in place of the sleeve 177. The forward end of this valve is of reduced diameter, as shown, and seats against an O-ring threaded into the handle 12 of the tool.

215 normally closing against passage of pressure fluid into the passage 187. The starter valve also includesa rod like portion 217 which extends forwardly across passages 187 and a forward guiding and control rod 218 which is adapted (in the same manner as control rod 1'70) to be engaged by the pawl 160 upon the first axial movement of the hammer. Spring 219 normally urges the starter valve 210 to its closed position as shown, thus closing off the passages 178,

Upon movement of the hammer at the first impact the pawl 160 will engage control rod 218 and force starter valve 210 rearwardly against spring 219. Thus,

. the passages 17% will be uncovered and air under pressure will enter the central portion of the housing 152 around the reduced diameter portion 210, and this pressure air will act to hold the starter valve open against spring 219, maintaining a passage for pressure air into passage 187 and thence into passage 145. Within this passage, prior to the opening thereof beneath the control piston 119, there is a needle valve 220 which is adjustably mounted within a threaded sleeve 222. This sleeve in turn is The needle valve 220 can be adjusted to control the orifice through which the pressure air must pass to the control piston 110, and thus the rate of fiow through passage 145 can be established in such a way that the time required for the control piston to reach its releasing position, shown in FIG. 9, will be a predetermined interval followingthe first impact, and of-course this interval will be definite and constant for each cycle of operation of the tool.

When the operation of the impacting tool is automatically terminated by the apparatus, the trigger will be released as previously explained to vent passage 145, and the starter valve will be reset by the spring.

FIG..12 shows a modified arrangement for providing constant energy from a rotary impacting tool operated by an electric motor. Essentially the same theory of operation is employed, and the apparatus shown will follow the same mode of operation as previously described. The impacting tool per se is of the same general construction as previously described, and includes a rotatable hammer 240 driven from a spindle 242 which in turn is driven by reduction gearing 243 from a reversible electric motor 245. The hammer 249 carries a follower 247 which operates to close a normally open switch 250 each time the follower is carried toward the rear of the tool by the hammer.

The trigger 252 operates a further normally open switch 254 which will close upon depression of the trigger. The direction of rotation of the motor may be controlled by conventional means, which maybe operated by movement of a reversing cap 255 on the rear of the tool. The electric leads from the motor 245 and switches 250 and 254 are passed from the handle of the tool through a conventional cable, a five conductor cable being required in this instance, to a control arrangement which may be conveniently located in a control box 257 shown in dotted lines in FIG. 12. Electrical power may be supplied from any convenient source, for example 110 volt A.C., through the leads L1 and L2. It will be noted that the lead L2 is connected directly to the conductor. or line 258 which leads to motor 245 and to one contact of the trigger switch 254.

When the trigger 252 is depressed and switch 254 is closed, this will complete a circuit through line 258 and a further line 259 through the coil of a double-acting A.C. relay 260, and this relay will actuate to open its normally closed contacts 262 and to close the normally open contacts 264. This completes a circuit through line 265 to supply power to motor 245, and the impacting tool will operate.

When the hammer strikes its first impacting blow the follower 247 will close switch 256) and complete a DC. circuit through lines 267 and 268 which are connected across a full wave rectifier network 270 supplying DC and receiving AC. power from the lines L1 and L2. Be-

tween line 268 and rectifier network 270 there is. con nected a series circuit including a variable resistor 272 and a capacitor 275. Thus, each time switch 250 is closed the capacitor 275 will be charged somewhat, depending upon the current fiow through the resistor 272.

When the capacitor 275 is charged to its full capacity, the potential difierence across it will be sufficient to fire the cold cathode thyratron 278, which has its cathode connected to rectifier network 270 and capacitor 275, and its grid connected to a point between capacitor 275 and variable resistor 272. The plate circuit of the thyratron includes a DC. relay 280. having normally closed contacts 282 which are in series with the contacts 264 of relay 260. Thus, energizing relay 280 will open the motor circuit and stop the tool. Then, when the trigger is released switch 264 will open and relay 260 will be deenergized, opening contacts 264 and 284 to extinguish the thyratron 278, and completing a discharging circuit through the back contacts 262 to dissipate any residual charge on the capacitor 27 5.

It is also possible to provide a timing circuit in which the lapsed time from the first impact blow determines the amount of energy expended by the tool upon the fastener, or in other words, an electrical equivalent of the modification shown in FIG. 11. Such a modified circuit embodies the same construction shown in FIG. 12, with the addition of a conventional holding circuit connected by the lines 267 and 268 such that once the contacts 250 have been closed, the current flow through the resistor capacitor network is maintained, and the physical constants of this network thus will determine the lapse of time required before the grid potential of the thyratron is sufficiently positive with respect to its cathode to fire the thyratron and shut off the electrical energy supply to the tool motor in the same manner as previously described.

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 scope of the invention which is defined in the appended claims.

What is claimed is:

1. A rotary impact device comprising a rotary motor, a rotary hammer connected for driving thereof by said motor, an anvil mounted for rotary movement in driving engagement with said hammer, parts acting on said hammer and responsive to deceleration of said hammer to disengage said hammer from said anvil and to provide for acceleration of said hammer producing a subsequent blow on said anvil tending t rotate said anvil, means 'connectedto supply power to said motor including a control arranged to govern the supply of power, and cycle control means connected to said power control operative upon initiation of the striking action of said hammer upon said anvil for terminating the power supply to said motor in response to application of a predetermined amount of energy to said anvil by said hammer.

2. A rotary impact tool comprising a rotary motor, a rotary hammer connected for driving thereof by said motor, an anvil mounted for rotarymovement in driving engagement with said hammer, parts acting on said hammer and responsive to deceleration of said hammer to disengage said hammer from said anvil and to provide for acceleration of said hammer producing a subsequent blow on said anvil tending to rotate said anvil, means connected to supply power to said motor including a control arranged to govern the supply of power, and cycle control means connected to said power control operative upon imitation of the striking action of said hammer upon said anvil and responsive to a definite and constant lapse of time for each cycle of operation of the tool following the first actuation of saidhammer parts to terminate the power supply to said motor. I

3. A rotary impact tool comprising a rotary motor, a rotary hammer connected for driving thereof by said motor, an anvil mounted for rotary movement in driving engagement with said hammer, parts acting on said hammer and responsive to deceleration of said hammer to disengage said hammer from said anvil and to provide for acceleration of said hammer producing a subsequent blow on said anvil tending to rotate said anvil, means connected to supply power to said motor including a control arranged to govern the supply of power, cycle control means connected to said power control and responsive to a definite and constant number of actuations of said hammer parts during each cycle of operation of the tool for terminating the power supply to said motor, and power supply means including a trigger controlling the supply of power to said motor and connected to maintain at all times a control over said power supply capable of terminating the actuation or said cycle control means prior to the full number of actuations of said hammer parts for which it is set.

4 A rotary impact tool comprising a rotary motor, a rotary hammer connected for driving thereof by said motor, an anvil mounted for rotary movement when in driving engagement with said hammer, parts on said hammer normally engaged with said anvil and responsive -to deceleration of said hammer to disengage temporarily from said anvil to provide for acceleration of said hammer producing a subsequent blow on said anvil tending to rotate said anvil, means connected to supply power to said motor including a control arranged to govern the supply of power, cycle control means connected to said power control and responsive to a definite and constant number of actuations of said hammer parts during each cycle of operation of said tool for terminating the power supply to said motor, and means operative on said cycle control means to vary the number of actuations required for response thereof.

5. A rotary impact tool comprising a rotary motor, a rotary hammer connected for driving thereof by said motor, an anvil mounted for rotary movement in driving engagement with said hammer, parts on said hammer normally engaged with said anvil and responsive t deceleration or" said hammer to disengage temporarily from said anvil providing for acceleration of said hammer to produce a subsequent blow on said anvil tending to rotate said anvil, means connected to supply power to said motor including a control arranged to govern the supply of power, automatic cycle. control means connected to said power control and responsive to a definite and constant number of actuations of said hammer parts during each cycle of operation of the tool for terminating the power supply to said motor, a manually actuated power control connected into said power supply means to control the supply of power to said motor prior to said automatic power control means, and a reset connection in said manual power control requiring shut otl" of the power supply by said manual power control before another automatic cycle can be initiated.

6. In a rotary impact tool having an anvil and a motor driving a rotary hammer having parts arranged to deliver successive impacts to said anvil tending to rotate the same, the combination of a manually operable control trigger, means connected to control the supply of power to the motor and operable to initiate the power supply in response to actuation of said trigger, cycle control means responsive to a definite and constant lapse of time following the first impact delivered by said hammer parts during each cycle of operation of the tool and connected to said power control means to cause termination of .the motor power supply at such response to lapse of time, and means forming a reset connection between said cycle control means and said trigger requiring release of said trigger after automatic termination of the power supply to initiate a further operating cycle.

7. In a portable rotary impact tool having a housing including a handle and an anvil and a motor driving a rotary hammer having parts arranged to deliver successive impacts to said anvil tending to rotate the same, the combination of a manually operable control trigger adjacent said handle, means in said housing connected to control the supply or power to said motor and operable to initiate the power supply in response to actuation of said trigger, cycle control means also mounted in said housing and responsive to a definite and constant lapse of time fiollowing the first impact delivered by said hammer parts during each cycle of operation of the tool and connected to aid power control means to cause termination of the motor power supply at such response to lapse of time, and means forming a reset connection between said cycle control means and said trigger requiring release of said trigger after automatic termination of the power supply to initiate a further operating cycle.

8. In a portable rotary impact tool having a housing including a gripping handle, an anvil, a motor in said housing, a rotary hammer driven by said motor and having parts arranged to deliver successive impacts to said anvil tending to rotate the same, a manually operable control trigger carried in said handle, servo system means connected to control the supply of power to the motor and operable to initiate the power supply in response to actuation of said trigger, cycle control means mounted in said housing including parts responisve to a definite and constant number of impacts following the first impact delivered by said hammer parts during each cycle of operation of the tool and connected to said power control means to cause termination of the motor power supply, and means for adiusting said cycle control means to vary the number or" impacts which cause such response thereof.

9. In a portable rotary impact tool having a housing including a gripping handle, an anvil, a motor in said housing, a rotary hammer driven by said motor and having parts arranged to deliver successive impacts to said anvil tending to rotate the same, a manually operable control trigger carried in said handle, servo system means connected to control the supply of power to the motor and operable to initiate the power supply in response to actuation of said trigger, cycle control means mounted in said housing including parts responsive to a definite and constant number of impacts following the first impact delivered by said hammer parts during each cycle of operation of the tool and connected to said power control means to cause termination of the motor power supply, means for adjusting said cycle control means to vary the number of impacts which cause such response thereof, and means forming a reset connection between said cycle control means and said trigger requiring release of said trigger after automatic termination of the power supply to initiate a further operating cycle.

Jill. A rotary impact t-ool having an anvil adapted for connection to rotate fasteners and the like, a hammer having parts arranged to deliver impacts to said anvil, a motor having a driving connection to said hammer, means connected to control the power supply to said motor and operative at rest to prevent supply of power to said motor, a trigger operative to cause said power supply control means to actuate said motor, and cycle control means operable so long as said trigger is actuated and responsive to a definite and constant number of impacts during each cycle of operation of the tool to override the action of said trigger on said power supply control means and to cause termination of the power supply to said motor.

11. A rotary impact tool having an anvil adapted for connection to rotate fasteners and the like, a hammer having parts arranged to deliver impacts to said anvil, a pressure fluid rotary motor having a driving connection to said hammer, a power connection adapted for coupling to a source of pressure fluid, a normally closed servocontrolled main valve connected in series between said power connection and said motor, a servo-operator for 'said main valve including release mechanism therefor, a normally closed servo-valve connected to control supply .of pressure fluid from said source to said operator, a trigger operable in response to continued actuation thereof to open said servo-valve to efifect operation of said servo-operator and opening of said main valve, an impact responsive device connected to supply a predetermined quantity of pressure fluid to said release mechanism in opposition to said servo-valve for each impact delivered by said hammer, said release mechanism being effective to release said main valve and to terminate the motor power supply in response to a predetermined total quantity of pressure fluid supplied from said impact responsive device, and reset apparatus on said servo-operator requiring release of said trigger for eflective subsequent action of said trigger and said servo-Valve on said servo-operator.

12. A rotary impact tool having an anvil adapted for connection to rotate fasteners and the like, a hammer having parts arranged to deliver impacts to said anvil, a pressure fluid rotary motor having a driving connection to said hammer, a power connection adapted for coupling to a source of pressure fluid, a normally closed servocontrolled main valve connected in series between said power connection and said motor, a servo-operator for said main valve including release mechanism therefor, a normally closed servo-valve connected to control supply 'of pressure fluid from said source to said operator, a trigger operable in response to continued actuation thereof to open said servo-valve to eflect operation of said servo-operator and opening of said main valve, an impact responsive device connected to supply pressure fl'uid to said release mechanism in opposition to said servo-valve for a predetermined length of time, following the first impact delivered by said hammer, said release mechanism being effective to release said main valve and to terminate the motor power supply in response to a predetermined total quantity of pressure fluid supplied from said impact responsive device, and reset apparatus on said servo-operator requiring release of said trigger for eifective subsequent action of said trigger and said servovalve on said servo-operator..

-13. A rotary impact tool having an anvil adapted for connection to rotate fasteners and the like, a hammer having parts arranged to deliver impacts to said anvil, an electric rotary drive motor having a driving connection to said hammer, a power supply connection to a source of electrical power, a main control relay having normally open contacts connected between said power connection and said motor, a servo relay having normally closed contacts also connected between said power connection and said motor, a trigger operative to energize said main relay for supplying power to said motor, a charge accumulating circuit connected to said servo relay and responsive to a predetermined quantity of charge to energize said servo-relay and interrupt said power supply, means responsive to each impact to apply a predetermined electrical charge to said accumulator circuit, and reset circuit means responsive to release of said trigger to reset said charge accumulator circuit.

14. A rotary impact tool having an anvil adapted for connection to rotate fasteners and the like, a hammer having parts arranged to deliver impacts to said anvil, an electric rotary drive motor having a driving connection to said hammer,- a power supply connection to a source of electrical power, a main control relay having normally open contacts connected between said power connection and said motor, a servo-relay having normally closed contacts also connected between said power connection and said motor, a trigger operative to energize said main relay for supplying power to said motor, a charge accumulating circuit connected to said servo-relay and responsive to a predetermined quantity of charge to energize said servo-relay and interrupt said power supply, mean responsive to the first impact delivered by said hammer to apply a predetermined electrical charge at a predetermined rate to said accumulator circuit, and reset circuit'means responsive to release of said trigger to reset said charge accumulator circuit;

References Qited by the Examiner Donowick 81--52.3

DON A. WAI-TE, Primary Examiner.

MORRIS M. FRITZ, Examiner,

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Classifications
U.S. Classification173/176, 173/169, 477/18, 173/93, 173/93.6
International ClassificationB25B23/145, B25B23/14, B25B23/147
Cooperative ClassificationB25B23/1453, B25B23/1475
European ClassificationB25B23/147B, B25B23/145B