US3576217A

US3576217A - Air feed nut runner having a travelling gear case

Info

Publication number: US3576217A
Application number: US804192A
Authority: US
Inventors: Raymond J Schaedler
Original assignee: Chicago Pneumatic Tool Co LLC
Current assignee: Chicago Pneumatic Tool Co LLC
Priority date: 1969-03-04
Filing date: 1969-03-04
Publication date: 1971-04-27
Anticipated expiration: 1988-04-27

Abstract

A nut-running tool having a work spindle arranged in a supporting base so as to be advanced by a pneumatically powered piston into engagement with a threaded fastener. As the spindle advances, it is also rotated so as to drive the fastener into the work by means of an air-driven motor acting through a travelling gear train structure. A check cylinder is automatically operable at a predetermined time during the advance of the spindle so as to dampen the advancing speed of the spindle and thereby prevent the latter from ramming into the fastener. A spring-cushioned pin and slot connection between the gear train structure and the spindle permits the gear train structure to advance briefly relative to the spindle when the latter seats upon the fastener. This relative movement stops prior to the time that the fastener is driven into the work. A limit switch is arranged to automatically signal a control circuit when the spindle has completed its advance stroke. The time of operation of the switch may be adjusted. The control circuit responds to the signal to shut off air feed to the piston and motor. A spring responds to the latter action to retract the piston to its normal start position. A second limit switch is arranged to automatically signal the control circuit when the spindle has completed its retract stroke. The control circuit responds to the latter signal to recondition the circuit for the next cycle of operation.

Description

United States Patent [72] Inventor Raymond .LSchaedler Utica, N.Y.

[21] Appl. No. 804,192

[22] Filed Mar. 4, 1969 [45] Patented Apr. 27, 197] [73 1 Assignee Chicago Pneumatic Tool Company New York, NY.

[54] AIR FEED NUT RUNNER HAVING A TRAVELLING Primary Examiner-Ernest R. Purser An0meyStephen J. Rudy ABSTRACT: A nut-running tool having a work spindle arranged in a supporting base so as to be advanced by a pneumatically powered piston into engagement with a threaded fastener. As the spindle advances, it is also rotated so as to drive the fastener into the work by means of an airdriven motor acting through a travelling gear train structure. A check cylinder is automatically operable at a predetermined time during the advance of the spindle so as to dampen the advancing speed of the spindle and thereby prevent the latter from ramming into the fastener. A spring-cushioned pin and slot connection between the gear train structure and the spindle permits the gear train structure to advance briefly relative to the spindle when the latter seats upon the fastener. This relative movement stops prior to the time that the fastener is driven into the work. A limit switch is arranged to automatically signal a control circuit when the spindle has completed its advance stroke. The time of operation of the switch may be adjusted. The control circuit responds to the signal to shut off air feed to the piston and motor. A spring responds to the latter action to retract the piston to its normal start position. A second limit switch is arranged to automatically signal the control circuit when the spindle has completed its retract stroke. The control circuit responds to the latter signal to recondition the circuit for the next cycle of operation.

PATENTEU m2? 15m SHEET 2 OF 2 INVENTOR PAYMOA/0 SCH/450L519 ATTORNEY AIR FEED NUT RUNNER HAVING A TRAVELLING GEAR CIQE BACKGROUND OF THE INVENTION This invention relates to a nut-running tool of a type having a work spindle which is advanced into engagement with a threaded fastener by means of a pneumatically powered piston, and wherein the spindle is simultaneously rotated by means of an air-driven motor to drive the fastener into the work. In the use of a tool of this type, the fastener is initially started by hand into the work.

A feature of the present invention is a travelling gear train structure which couples the spindle with the piston and also with the motor. lt advances with the spindle and simultaneously transmits to it the rotation of the motor.

Another feature of the present invention is a spring-loaded pin and slot connection between the gear train structure and the spindle which operates upon seating of the work end of the spindle upon the fastener to allow the gear train structure to advance briefly relative to the spindle while at the same time maintaining the spindle pressed under the load of the spring upon the fastener.

A further feature of the present invention is actuating means which is cooperable at a predetermined time during the travel of the gear train structure to actuate a dampening device so as to check the advancing speed of the spindle before it engages with the fastener. This is of advantage in that it permits gentle engagement of the spindle with the fastener and avoids damage to the latter which might otherwise occur were the spindle to advance under a high inertial load at a rapid rate into the fastener.

A still further feature of the invention is an arrangement of switch elements which is automatically operable to signal a control circuit when the spindle has completed its advance stroke and also when the spindle has completed its return stroke.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FlGS. l and IA which are in continuation of one another represent a longitudinal section through an air feed nut runner embodying the invention;

FIG. 2 is a bottom plan of the supporting base and associated elements;

FIG. 3 is a section on line 3-3 of FIG. 1 with some portions broken away;

FIG. 4 is a detail of the V-coupling with the head end of the splined shaft engaged therein;

FIG. 5 is a schematic showing of a gang of the tools in sideby-side arrangement; and

FIG. 6 is a view similar to FIG. 5 but shows the tools in angular array.

DESCRIPTION OF PREFERRED EMBODIMENT The tool disclosed in the drawing as embodying the invention includes an oblong supporting base 10 having parallel sidewalls 11, and upright front and rear end walls respectively designated 12 and 13. A channel 14 is defined between the walls; it opens through the top and bottom areas of the base. The front face and the bottom surface of the base are flat, either of which may be used for mounting the tool to a stationary support. The outer surfaces of the sidewalls 11 are also flat whereby a gang of the tools may be arranged upon a support in side-by-side relation as in FIG. 5. The front and rear walls have upper

triangular sections

15 and 16 extending in parallel relation to each other above the level of the sidewalls. This triangular configuration enables a gang of the tools to be arranged in compact angular array upon a support as in FIG. 6. Because of this mounting capacity of the tool, work requiring multiple fasteners therein to be set in close relation to one another may be subjected to the advantages of a gang application of the tool.

A work spindle 17 is associated by means of an axially travelling gear case 18 with a reciprocable piston 19 whereby the spindle may be axially advanced and retracted relative to the work. The spindle is connected through a gear train 21, supported within the gear case, with the drive of a rotary motor 22 whereby the spindle may be simultaneously rotated as it is being advanced by the piston. The gear case is disposed in the channel 14 of the supporting base; and it is limited therein to axial travel between the end walls 12 and I3.

The motor 22 is of a conventional air-driven type. lts housing is fixed at its forward end (FIG. 1) by means of an adapter 23 to the rear wall 13 of the base and extends axially rearward therefrom. lts drive shaft 24 has a splined driving connection 25 with a coupling 26. The coupling in turn drivingly engages the head 27 of an elongated straight splined shaft 28.

Here, the coupling (FIGS. 1, 4) is of a V-type. It has an annular forwardly extending skirt body 29 provided with a pair of diametrically opposed V-slots 31, the wider ends of which slots open through the forward end of the coupling. The head 27 of the spline shaft has a cylindrical body which is slidably received in the recess 32 of the coupling and is formed with a pair of opposed wedge or V-ribs 33 on its surface, which ribs are slidably seated in the V-slots. The spline shaft 28 serves as a supporting rail for the travelling gear case [8 and also serves to transmit the drive of the motor through the gear train to the spindle. The spindle shaft extends axially with a sliding spline connection 34 through a pinion member 35 of the gear train. The pinion is journaled in suitable bearings of the gear case. A smooth terminal cylindrical end portion 36 of the spline shaft is slidably received and supported in a complementary recess 37 of a stub bearing shaft 38. The latter is retained by opposed nut and shoulder elements 39 and 41 in a bearing 42 mounted in the front base wall 12. A compression spring 43, seated between the bottoms of recesses 37 and 45 respectively of the stub shaft 38 and the spline shaft 28, normally biases the spline shaft rearwardly so as to seat the head 27 of the spline shaft at the bottom of the V-slots of coupling 26, as in FIGS. 1 and 4.

An idler gear 46joumaled in the gear case drivingly engages pinion 35 with a pinion part 47 of a pinion shaft 48. The latter is journaled in the gear case. Pinion 35, gear 46, and pinion shaft 48 are suitably restrained in position endwise of the gear case by thrust bearings (not designated The gear case 18 has an axial forward tubular projection 49 through which the pinion shah 48 extends into a spindle tube 5 l. The latter is relatively long. It is threadedly fixed at its rear end 52 in the gear case projection 49; and slidably extends at its forward end through a bore 53 in the upper triangular front wall portion [5. The work spindle 17 is slidably received in the spindle tube 51; and has at its rear end an internal axial sliding spline connection 54 with the pinion shaft 48 whereby rotation of the latter is transmitted to the spindle. Forwardly of the spline connection 54. a pin 55 anchored in the spindle extends transversely through a slot 56 in the pinion shaft. A compression spring 57, limited between the rear end of the spindle and a shoulder of the pinion shaft, biases the spindle forwardly so as to limit the pin 55 against the forward wall of the slot 56. in this normal condition of the spindle, the forward end of the pinion shaft 48 is located by the space 59. This space is about one-fourth of an inch in its axial dimension and is slightly less than the axial extent of the slot 56 at the rear of the pin. This pin and slot arrangement permits limited forward movement of the pinion shaft relative to the spindle at certain times during axial advance of the spindle as when the spindle socket 61 (broken line) seats upon the head of a fastener preparatory to driving the fastener into the work. The relative forward movement of the pinion shaft at such times is cushioned by the spring 57 so as to avoid an undesirable strong thrust of the spindle against the fastener. When the pinion shaft is relatively advanced in this action, its forward end will limit against the recessed bottom 58 of the spindle; but the pin 55 will not at any time engage the rear wall of slot 56. A bearing cage 62, threadedly engaged on the forward end of the spindle tube 51, provides a supporting bearing for a forward end portion of the spindle projecting beyond the spindle tube.

The piston 19, which serves to advance the spindle. is reciprocable in a cylinder 63. The latter is threadedly fixed by means of an adapter 64 at its forward end in a bore 65 of the rear upper triangular portion 16 of the base wall 13. The cylinder extends axially rearwardly from the base wall; and its longitudinal axis is parallel to and coplanar with that of the motor. A forward end of the piston is received in a rear tubular projection 66 of a gear case cover 67. The latter is bolted fast to the gear case. The piston is rigidly retained in the tubular projection 66 by means of a retaining bolt 68. A return spring 69 acting upon the piston head 71 biases the piston to a normal retracted position, as in FlGS. 1, 1A, wherein the projection 66 of the gear case cover abuts a stop 72 defined by a forward face of the rear base wall 13.

In the operation of the tool, live air fed concurrently to inlets 73 and 74 respectively of the piston cylinder 63 and the housing of the motor 22 advances the piston 19 and concurrently operates the motor. Rotation of the motor is transmitted through the spline shaft 28 and the gear train 21 to the spindle 17. While the spindle is rotating, the piston advanca the gear case 18 slidingly along the spline shaft. The spindle tube 51 and spindle advance forwardly as a unit with the gear case. The spring load 43, acting on the spline shaft 28, normally maintains the head end 27 of the latter seated in the coupling 26 and normally restrains the spline shaft from being frictionally carried along with the travelling gear case. Eventually, the socket end 61 of the advancing spindle seats over the head of a fastener, not shown; (the fastener is initially hand started into the work). As the socket seats upon the fastener, axial resistance offered by the fastener causes the pinion shaft 48 through the pin and slot connection 55, 56 to advance against the bias of the spring 57 to the extent of the space 59.

At times, because of burrs or nicks on the fastener, the fastener may offer more than normal torque resistance to its being entered into the work and may cause a reactionary torque to be transmitted back through the gear train 21 to the spline shaft 28. This reactionary load may frictionally bind or lock the pinion member 35 of the gear train to the spline shaft so as to prevent sliding travel of the gear case over the splines 75 of the spline shaft. When this condition develops, the gear train nevertheless continues to operate under the torque of the motor to rotate the spindle. To avoid ineffective rotation of the spindle at this time relative to the fastener without accompanying advancement of the spindle because of a locked condition of the gear case with the spline shaft, the particular V-coupling 26 has been provided between the motor drive and the spline shaft. The V-slots 31 of the coupling cooperate with the V-ribs 33 of the head of the spline shaft under the developed torque overload to force the head of the spline shaft forwardly in the coupling. ln this action, the spline shaft advances axially into the stub bearing shaft 38 against the bias of the spring 43 and, as it advances, it carries the gear case 18 with it to continue without interruption advance and rotation of the spindle. Should the binding or locked condition of the gear train and spline shaft become relaxed, spring 43 will respond to reseat the head end 27 of the spline shaft in the coupling.

Under the force of the piston 19, the spindle initially advances at a rapid rate toward the work. It is undesirable to have the spindle socket 61 ram into the fastener at this rapid rate while under a high inertia load. To avoid this, a conventional hydraulic check cylinder 76 is arranged in the base to check or dampen the advancing speed of the spindle at a predetermined distance before the spindle engages its socket with the fastener. The check cylinder is pivoted at its forward end 77 between the lower areas of the sidewalls of the base. It is supported at its opposite end by means of a collar 78 fitted in an axial bore 79 of the rear base wall 13. A plunger rod 81 of the check cylinder extends part way into bore 79 wherein it abuts the head end 82 of an actuating rod 83. The shank of the actuating rod extends with a slide fit through a switch support block 84 mounted in extension of the rear wall 13 of the base. An externally projecting threaded portion 85 of the actuating rod is threaded through the lower end 86 of a bar support 87. The upper end 88 of the support is slidably engaged upon the shank of an advance control screw 89. A locknut 91 fixes the position of the support bar upon the actuating rod. The control screw is relatively elongated and passes slidably through the block 84 and the rear base wall 13 into the channel 14 of the base 10 in parallel and coplanar relation to the actuating rod 83. The forward end of the control screw is threadedly engaged in a nut 92 positioned in a bottom bifurcation 93 of the gear case. A pin 94 restrains the nut in the bifurcation against relative rotation.

It can be seen during operation of the tool, that the control screw 89 will advance as a unit with the gear case 18 as the latter is advanced by the piston. After the gear case has been advanced a predetermined distance, a head 95 on the control screw will engage the bar support 87 to cause axial advance of the actuating rod 83 and consequent actuation of the plunger 81 of the check cylinder. As the plunger is forced into the check cylinder, the advancing speed of the piston and spindle is slowed. The time of cooperation of the control screwhead 95 with the actuating rod bar support 87 may be adjusted by making an axial adjustment of the control screw relative to the nut 92 so as to bring its head 95 selectively nearer or further away from the bar support 87. The limited axial movement allowed by slot 59 between the spindle and the pinion shaft enables the socket to pick up the fastener without exerting excessive thrust upon the fastener. The check cylinder is caused to function just prior to the socket engaging the fastener; and its operation is such that it permits the thrust upon the fastener to always take out the limited axial movement allowed by slot 59.

It is apparent during operation of the tool that when the air feed to the motor and the piston cylinder is shut off and the pressurized condition of the piston cylinder 63 is relaxed, further rotation and advance of the spindle 17 will cease; and the spindle will be drawn from the work back to its normal position as the piston is retracted into its cylinder by the return spring 69. In this action, the control screw 89 will be returned to its normal position to carry its head 95 away from the actuating rod bar support 87; and the plunger rod 81 of the check cylinder will restore to normal in conventional manner by means of its internal spring mechanism as the control screw restores.

Limit signalling switches 96 and 9'! are provided to automatically signal to a conventional electrical control circuit CC completion of both the advance and retraction strokes in a cycle of the spindle. The advance limit switch 96 is mounted to the support block 84. It has a rearwardly facing plunger 98. The retract limit switch 97 is also mounted to block 84 and has a forwardly facing plunger 99. The means for actuating the advance limit switch includes a bracket 101 which is slidably mounted at its lower end 102 upon the check cylinder-actuating rod 83. At its upper end, the bracket is slidably supported upon the control screw 89 by means of a forwardly extending sleeve portion 103. The sleeve extends slidably into a complementary recess of the support block 84. The lower end of the bracket carries a plunger case 104 containing a spring loaded pin 105, the head of which is axially aligned with and abuts the plunger 98 of the advance limit switch. It can be seen that, as the spindle 17 is advanced by the piston-actuated gear case 18, the head 95 of the control screw 89 eventually cooperates with the actuating rod bar support 87. As the latter is forced forwardly by the control screw, it eventually abuts the bracket 10! and slides it forwardly causing the pin [05 to be carried into abutment with the advance switch limit plunger 98, whereupon the plunger 98 is actuated sufiiciently to cause a signal to be transmitted to the control circuit CC indicating completion of the advance stroke. Spring 106 has a higher preload than the force required to operate the plunger 98 of switch 96. The spring cushioned pin 105 is designed as a safety measure to avoid damage to the switch which might otherwise occur as a result of some overtravel of pin 105 following its actuation of switch 96. The signal to the control circuit will be effected at about the time that the work or fastener is driven "home." A precise time for actuating the advance limit switch 96 may be obtained by selective adjustment of the control screw 89 relative to its nut 92. When the signal is received by the circuit, the latter responds in suitable manner to cause termination of operating airflow to the piston cylinder 63 and to the motor 22, and to cause relaxing of the pressurized condition of the piston cylinder. When the circuit thus responds, the spindle [7, gear case 18 and piston 19 will be returned to normal retracted position by the piston spring 69.

The retract signal switch 97 is designed to signal the circuit when this normal condition of the piston is reached. The means for actuating the retract signal switch includes a slide pin slidable through the rear wall l3 of the base. The slide pin has a forward end projecting into the channel 14 of the base, which end is abuttable by a depending tail 108 (FIGS. 1, 3) of the gear cue as the gear case is retracted by the piston. The opposite end of the slide pin projects into a recess 109 (FIG. 2) in the rear face of the wall [3 of the base. The switch plunger 99 under the load of its internal spring abuts the end of the slide pin and normally biases the slide pin forwardly through the block to a nonnal position in which a stop 11] on the slide pin abuts the bottom of the recess 109. It can be seen that in the retracting movement of the gear case by the piston, the tail end 108 of the case will eventually engage the slide pin 107 and actuate the plunger 99 of switch 97. Switch 97 will be actuated at about the time that the projection 66 at the rear of the gear case abuts the stop 72 provided by the inner face of the rear base wall 13. The control circuit will respond to the signal transmitted by the actuated switch to indicate completion of the retract stroke by reconditioning the circuit preparatory to the next cycle of the tool. The switches 96 and 97 are conventional air switches. It is apparent that other conventional plunger type switches may be used.

lclaim:

l. In an air feed nut runner including a supporting base, a work spindle supported in the base for axial movement toward and away from the work and for rotative movement to drive the work, a piston cylinder fixed to the base, a piston reciprocable in the cylinder through an advance stroke and a return stroke, a gear case fixed to the piston for unitary movement with the latter, means coupling the spindle with the gear case for axial movement of the spindle as a unit with the gear case, a rotary motor having a drive shaft, an elongated spline shaft extending axially through the gear case, a slide coupling drivingly connecting the motor drive shaft with the spline shaft, a gear train carried by the gear case drivingly connecting the spline shaft with the spindle and allowing axial movement of the gear case along the spline shaft; and dampening means actuable by the gear case at a predetermined point in the axial movement of the spindle during an advance stroke of the piston to dampen the advancing speed of the spindle; wherein the slide coupling has a pair of V-slots, the spline shaft is axially slidable relative to the coupling and has a head provided with a pair of wedge ribs slidably received in the V-slots, and a spring load normally biases the spline shaft so as to seat the wedge ribs at the bottom of the V-slots, the axial dimension of the wedge ribs being substantially less than that of the V-slots.

2. In an air feed nut runner as in claim 1, wherein the dampening means is a check cylinder having an operating plunger, a slide rod is supported in the base for movement against the plunger to operate the check cylinder, and abutment means is carried by the gear case for engaging the slide rod and pressing it against the plunger.

3. In an air feed nut runner as in claim I, wherein the gear train includes a pinion shaft having a driving spline connection with the spindle.

4. In an air feed nut runner as in claim 1, wherein the means coupling the spindle with the gear case includes a pinion shaft member of the gear train restrained in the gear case against relative axial movement having an axial sliding splined driving connection with the spindle, an abutment carried by the spindle engageable with a stop carried by the pinion shaft to prevent axial sliding release of the spindle from the pinion shaft, and a spring load between the pinion shaft and the spindle biasing the spindle axially so as to engage the abutment with the stop and adapted to transmit axial movement of the gear case to the spindle.

5. in an air feed nut runner as in claim 4, wherein the abutment is a pin extending transversely through a loss-motion slot in the pinion shaft, a forward wall of which slot defines the stop, and the pinion shaft is adapted during axial movement of the gear case on an advance stroke of the piston to advance relative to the spindle to the extent of the loss-motion of the slot upon the spindle encountering a predetermined degree of resistance to advancement by the work.

6. In an air feed nut runner as in claim 1, wherein the piston is pneumatically operable on its advance stroke and spring returnable on its retract stroke, the motor is air driven, and means is provided to concurrently feed operating air to both the piston and motor.

7. In an air feed nut nmner as in claim 1, wherein means is provided to limit the extent of the advance stroke of the piston, and other means is provided to limit the extent of the retract stroke of the piston.

8. in an air feed nut runner as in claim 1, wherein a circuitcontrolling operation of the nut runner is provided, an advance stroke limit switch is mounted to the supporting base, abutment means carried by the gear case is cooperable with the limit switch at about the time the piston completes its advance stroke to actuate the switch to transmit a signal to the circuit, a retract stroke limit switch is mounted to the supporting base, and slide means is provided with which the gear case is cooperable at about the time the piston completes its retract stroke to actuate the retract limit switch to transmit a signal to the circuit.

9. In an air feed nut runner as in claim 8, wherein means is provided for selectively adjusting the time of cooperation of the abutment means with the advance stroke limit switch.

10. in an air feed nut runner as in claim I, wherein the head of the spline shaft is axially displaceable from the bottom of the V-slots so as to carry the spline shaft forwardly against the bias of the spring load upon the coupling experiencing a predetermined degree of overload torque.

UNITED STATES lA'lEN'l OFFICE CERTIFICATE OF CORRECTION Patent No. 3576217 Dat d April l97 1 Inventor) Raymond J. Schaedler It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 62, "is located by the space 59." should read is located short of a recessed bottom 58 of the spindle as indicated by the space 59.

Signed and sealed this 17th day of August 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents OHM PO-HJSO (IO-69)

Claims

1. In an air feed nut runner including a supporting base, a work spindle supported in the base for axial movement toward and away from the work and for rotative movement to drive the work, a piston cylinder fixed to the base, a piston reciprocable in the cylinder through an advance stroke and a return stroke, a gear case fixed to the piston for unitary movement with the latter, means coupling the spindle with the gear case for axial movement of the spindle as a unit with the gear case, a rotary motor having a drive shaft, an elongated spline shaft extending axially through the gear case, a slide coupling drivingly connecting the motor drive shaft with the spline shaft, a gear train carried by the gear case drivingly connecting the spline shaft with the spindle and allowing axial movement of the gear case along the spline shaft; and dampening means actuable by the gear case at a predetermined point in the axial movement of the spindle during an advance stroke of the piston to dampen the advancing speed of the spindle; wherein the slide coupling has a pair of V-slots, the spline shaft is axially slidable relative to the coupling and has a head provided with a pair of wedge ribs slidably received in the V-slots, and a spring load normally biases the spline shaft so as to seat the wedge ribs at the bottom of the V-slots, the axial dimension of the wedge ribs being substantially less than that of the V-slots.

3. In an air feed nut runner as in claim 1, wherein the gear train includes a pinion shaft having a driving spline connection with the spindle.

7. In an air feed nut runner as in claim 1, wherein means is provided to limit the extent of the advance stroke of the piston, and other means is provided to limit the extent of the retract stroke of the piston.

8. In an air feed nut runner as in claim 1, wherein a circuit-controlling operation of the nut runner is provided, an advance stroke limit switch is mounted to the supporting base, abutment means carried by the gear case is cooperable with the limit switch at about the time the piston completes its advance stroke to actuate the switch to transmit a signal to the circuit, a retract stroke limit switch is mounted to the supporting base, and slide means is provided with which the gear case is cooperable at about the time the piston completes its retract stroke to actuate the retract limit switch to transmit a signal to the circuit.

10. In an air feed nut runner as in claim 1, wherein the head of the spline shaft is axially displaceable from the bottom of the V-slots so as to carry the spline shaft forwardly against the bias of the spring load upon the coupling experiencing a predetermined degree of overload torque.