US3797335A

US3797335A - Pneumatic nut running tool with governor shut-off control

Info

Publication number: US3797335A
Authority: US
Inventors: W Wallace; L Amtsberg
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-05-29
Filing date: 1973-05-29
Publication date: 1974-03-19
Anticipated expiration: 1991-03-19
Also published as: CA997597A

Abstract

A pneumatic tool provided with combined nut setting and crimping mechanism which responds to rotation of an air motor in one direction to set a nut and responds to rotation of the motor in an opposite direction to crimp the nut. Shiftable valving mechanism is included to direct operating air flow to drive the motor in one direction or the other. A throttle valve is depressible to initiate air flow to the valving mechanism and becomes pneumatically unbalanced against the force of a spring in open condition. A centrifugal motor speed responsive governor valve controls shifting of the valving mechanism and automatic return of the throttle valve to shut-off condition.

Description

United States Patent, 1191 Amtsberg et a1.

[ Mar. 19, 1974 4] PNEUMATIC NUT RUNNING TOOL WITH GOVERNOR SHUT-OFF coNTRoL [22] Filed: May 29, 1973 [21] Appl. No.2 364,885

Related US. Application Data [62] Division of Ser. No. 138,091, April 28, 1971.

2,931,374 4/1960 Randol 137/54 5/1970 Reynolds 81/10 3,646,837 3,747,441 7 1973 Amtsberg.... 81/10 3,653,802 4/1972 Weiss 1. 29/200 B Primary Examiner-James L. Jones, Jr. Attorney, Agent, or Firm-Stephen J. Rudy 57 1 ABSTRACT A pneumatic tool provided with combined nut setting and crimping mechanism which responds to rotation of an air motor in one direction to set a nut and responds to rotation of the motor in an opposite direction to crimp the nut. Shiftable valving mechanism is included to direct operating air flow to drive the motor in one direction or the other. A throttle valve is depressible to initiate air flow to the valving mechanism andbecomes pneumatically unbalanced .against the force of a spring in open condition. A centrifugal motor speed responsive governor valve'controls shifting of the valving mechanism and automatic return of thethrottle valve to shut-off condition.

4 Claims, 8 Drawin'g Figures PATENTEDIAR 1 9 1914 SHEET 1 BF 3 F/G/A PATENTEB "AR 1 9 I914 sum 2 OF 3 PNEUMATIC NUT RUNNING TOOL WITH GOVERNOR SHUT-OFF CONTROL This application is a division of application Ser. No. 138,091, filed Apr. 28, 1971. v

The term governor as used herein means a mechanism having the usual governor elements, i.e., flyweights, valve means, etc.; however, the governor used in the device of the invention functions to sense and respond to a predetermined speed at which certain valves will be made operative to perform desired operational results, all as will be apparent hereinafter.

BACKGROUND OF THE INVENTION This invention relates to the art of pneumatic nut runners provided with automatically operating air shut off controls.

It is concerned with a pneumatic tool in which nut running and crimping mechanism are combined.

A tool of this type having an automatic air shut-off control is described in our co-pending application Ser. No. 121,867, filed Mar. 8, 1971, which issued as US. Pat. No. 3,747,441 on July 24, 1973. In this known tool, following depression of a throttle valve, the tool runs through a complete cycle having a first stage in which a valving system directs inlet air to run the motor in one direction to set the nut;then responds to a stall condition of the motor to direct the air to run the motor in an opposite direction in a second stage to crimp the nut; and then responds to a stall condition to shut off further air flow to the motor.

In the tool described herein, a governor controlled valve unit is connected in a shiftable valving system. In this tool following depression of a throttle valve, the tool runs through a complete cycle having a first stage in which the valving system directs inlet air to run the motor in a nut tightening direction. In this first stage, the governor unit responds to a rapid acceleration of the motor speed in excess of ten per cent of its free speed to open its valve so as to maintain the throttle valve pneumatically unbalanced in an open condition; next, when the motor becomes loaded by reaction torque in the nut tightening operation and its speed drops below ten per cent of its freespeed, the governor unit responds or senses the loaded condition and closes its valve to cause the valving system to direct the inlet air so as to operate the motor in an opposite direction for the nut crimping stage. Before the throttle valve can, as this second stage begins, become pneumatically balanced and shut off while the governor controlled valve is closed, the governor unit again responds to 1 This employment of the governor controlled valve unit represents a decided advance in this unit, in that it results in a precise pre-torque control over the operation of the motor. The governor unit begins to operate momentarily before final torque is delivered to the nut in each stage of operation, that is, when the motor speed drops below ten per cent of its free speed. The

motor stops operating precisely at the time of final torque delivery.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawing:

FIGS. 1 and .lA, combined, comprise a pneumatic nut running and crimping tool illustrating an embodimentof the invention, portions of the toolbeing shown in section and broken away in part for clarity of illustration;

FIG. 2 is a section on line 2--2 of FIG. 1;

FIG. 3 is a section on line 3-3 of FIG. 1;

FIG. 4 is a section on line 4-4 of FIG. 1;

FIG. 5 is a detail of the governor unit viewed from its valve end, portions being broken away and sectioned for clarity;

FIG. 6 is a detail of a governor weight; and

FIG. 7 is a detail of the association of the stem portion of the governor weight with the governor valve.

DESCRIPTION OF PREFERRED EMBODIMENT Reference is directed to the accompanying drawing, wherein there is disclosed a pneumatically powered tool (FIGS. 1 and 1A combined) having a general housing 10, to the front end of which is detachably coupled an angle-head section 11.

Within the housing is a conventional reversible air driven rotary stall motor, generally indicated at 12, of the radially slidable vane type. Rotation of themotor is transmitted through conventional reduction gearing, generally indicated at 13 (FIG. 1A) and through a splined driving connection 14 to a spindle 15. The spindle extends axially into one arm 16 of the angle-head, wherein it is supported in

bearings

17 and 18. A beveled pinion 19 on the spindle drivingly engages a bevel gear member 21 of a combined nut running and nut crimping mechanism 22. The mechanism is shown as arranged in a second arm 23 of the angle head, which arm extends at right angles to the longitudinal axis of the general housing of the tool.

The mechanism 22 has a first stage of operation upon application of torque to it in one direction by the spindle 15 to run a nut 24 down to a predetermined value of tightness; and the mechanism 22 has a subsequent second stage of operation to crimp the nut upon torque being applied to the mechanismby the spindle in an opposite or nut crimping direction. a

The mechanism 22 is described in detail in our co pending application Ser. No. 121,867, filed Mar. 8, 1971, for a Pneumatic Tool Having Combined Nut Running and Crimping Mechanism.

The beveled gear member 21 of mechanism 22 is joumaled in a bearing 25; and has a splined driving connection 26 with a slidable dog member 27 of a clutch 28. The dog is normally biased out of clutched engagement with'a drive-nutmember 29 of the clutch by means of a spring 31. The drive-nut member is supported by bearings 32, 33. Upon admission of live air through a passage 35 to a chamber 36, a piston 34 is movable to slide the dog into clutched driving engagement with the drive-nut.

The drive-nut has an internal helically splined or screw drive connection 37 with an upper screw portion of a travel-wedge 38. The wedge terminates at its lower end in a wedge head 39 which has a splined connection 40 about its upper area with an internal channelled wall 41 of a jaw holding sleeve 42. The sleeve is mounted in I housing,

the lower end of the angle head for relative rotation. Pivotally mounted in a lower end of the sleeve is a group of jaw elements or levers 43 spaced circumferentially equally apart.

A plunger 44 axially slidable in the travel-wedge has a peripheral end lip 45 which presses under the load of a spring 46 upon a lug 47 of each of the jaw elements so as to normally bias an upper tail end 50 of each jaw element inwardly into abutment with an angled surface 48 of the wedge head. In this normal condition, the lower inner faces 49 of the several jaw elements define an open hexagonal socket for reception of the nut 24. The spring 46 also serves to normally bias the wedge upwardly to abut a shoulder 52 thereon against the underside of the gear member 21.

The travel-wedge has rotatable and linear movement. When it rotates, it carries the sleeve 42 and jaw elements 43 about with it as a socket unit to run down and set the nut. When it moves linearly, its angled surface areas 48 cooperate with the tail ends 50 of the several jaw elements to swing their lower jaw faces 49 inwardly to crimp and lock the nut upon a stud.

The general housing section (FIG. 1) of the tool contains in its handle portion a shiftable valving system to be later described. The valving system functions automatically following opening of a throttle valve 54 to cause the tool to pass through a complete cycle of setting and crimping the nut, and then restores to normal condition without intervention of the operator.

A speed responsive centrifugal governor 55, representing a decided advance in this art, is associated with the valving system. It senses the speed of the motor. It functions automatically toward the end of the nut tightening stage to cause the valving system to reverse the directional flow of air to the motor so as to cause the motor to run in a nut crimping direction; and it functions toward the end of the crimping stage to cause the valving system to shut off air flow to the motor and to restore to normal condition.

The governor is arranged in a chamber 56 of the which chamber is continuously vented through the exhaust system of the motor. The governor includes a hollow or tubular cage or body 57 having an enlarged diameter portion 58 at one end in which is axially received the rear end 59 of the rotor shaft of the motor. The cage is fixed by a pin 61 and a threaded connection for rotation as a unit with the rotor shaft. A retaining ring 62 seated in a peripheral groove of the cage over the ends of the pin secures the pin against undesirable endwide movement. A governor valve 63 controlled by the governor has a portion slidably received in the interior of the cage. A governor spring 64 normally biases the valve outwardly of the cage to seat an end portion closed over a relief passage 65 extending through a valve seat defined by a bushing 66. The valve is movable away from its seat by means of centrifugal governor weights 67 pivoted in the cage. A peripheral shoulder 68 about the valve is cooperable with an end wall of the cage to limit the extent of opening movement of the valve away from its seat.

Each governor weight 67, of which there are four, has a heavy segmental head 69 (FIGS. 1, 5-7) provided with a curved back and formed with a curved inner face which overlies the enlarged diameter portion 58 of the cage. Axially extending from the head of the weight is a stem 71 which is pivoted between a pair of radial ears 72 of the cage upon a retainer'pin 73. Each stem 71 terminates in a toe 74 which dips into a peripheral groove 75 about the governor valve. The governor is designed so that, when the motor exceeds approximately 10 per cent of its free speed, the weights will swing outwardly to draw the valve to open condition from its seat so as to communicate an air feed port 70 through the relief passage 65 with the vented governor chamber 56. When the speed of the governor drops below ten per cent of its free speed, the governor spring 64 reseats the valve to closed condition, and in doing so, returns the governor weights to normal condition.

Besides the governor controlled valve 63, the valving system includes the throttle valve 54; a first shiftable directional control valve 76, a second shiftable directional control valve 77, and a third shiftable directional control valve 78.

The throttle valve is designed so that, after it has been manually depressed to open condition against the force of its return spring 79, it will remain pneumatically depressed until completion of the operating cycle of the tool. Then it will be restored automatically to closed condition.

The chamber 81 under the throttle valve is normally connected through

ports

82, 83, 84 (FIGS. 2 and 3) and 85 (FIG. 4) to a vent 86 (FIG. 1). When the throttle valve is depressed to open condition, pressure of inlet air from supply passage 87 developing over the upper area of the valve, exceeds the force of the return spring 79 so as to hold the valve in open condition permitting removal of the operators hand from the valve button.

Supply air then flows through the open throttle valve to a common chamber 88 from where it flows in part through a side port 89 and an external hose connection 91 with passage 35 (FIG. 1A) to pressurize the piston chamber 36 in the angle head. This moves the piston 34 to force the clutch dog 27 into driving engagement with the drive nut 29, as earlier explained. Air also flows from chamber 88 through port 92, chamber 93 of directional control valve 76,

ports

94, 95, 96 (FIGS. 3, 4 and 1) to motor feed ports in the motor endplate 97 to drive the motor in a nut tightening direction. In this action, the rotation of the motor is transmitted through the drive nut 29 and travel-wedge 38 to rotate the sleeve 42 and the jaw elements 43 to tighten the nut 24. The residual exhaust from the motor escapes through port 98 FIGS. 4, 3), port 99 (FIG. 1), chamber 101 of directional valve 77, and vent passage 102 (FIGS. 1, 4) to atmosphere.

Supply air from chamber 88 also flows through ports 103, 104 (FIGS. 2, 3) port 70 (FIGS. 4, l), chamber 105 of directional valve 78, port 106 to the chamber at the top of directional valve 77 and port 107 to the chamber at the'top of valve 76. When the motor, while running in the nut tightening direction, accelerates to above ten per cent of its free speed, the governor weights 67 swing outwardly to open the governor valve 63 against the force of spring 64. This causes air feed port 70 and the chambers atop

valves

76 and 77 to be connected through the open governor valve with chamber 56 and the exhaust system before live air being supplied through port 70 can sufficiently build the pressure atop valve 76 to shift it downwardly against the force of its spring 108.

When the nut is then tightened to a value of torque that will load the motor enough to reduce its speed to a value less than ten per cent of its free speed, the governor spring 64 overcomes the force of the centrifugal weights and closes the governor valve 63 upon its seat. Live air feeding through port 70 now increases the pressure on top of

valves

77 and 76. The pressure on top of valve 76 increases sufficiently to force it to shift downwardly against the force of its spring 108. In this shifting, valve 76 first closes over port 92 permitting the air in the chambers 93 and 109 below both

valves

76 and 77 to be vented through port 95 to the motor. This pneumatically unbalances both

valves

76 and 77, and the air pressure at their top ends forces them both downwardly against their respective stops 110 and 111.

The shifting of

valves

76 and 77 connects air supply port 92 through the upper ends of the chambers of

valves

76 and 77 with' ports 99 and 98 (FIG. 3) leading through further feed ports in the motor end plate 97 causing the motor to now run in the opposite or in a nut crimping direction. The motors residual exhaust now passes through ports 96 and 95 (FIGS. 4, 3, 1), chamber 112 of valve 77 and ports 101 and 102 (FIG. 4) to atmosphere. The chamber at the top of valve 78 is connected by port 113 to port 98 so that live air now passing through port 98 also pressurizes the top of valve 78 causing it to shift down against the force of its spring 114. In this shifted condition, valve 78 disconnects air feed port 70 from the top ends of

valves

77 and 76 and connects it to chamber 81 under the throttle valve 54 through

ports

85, 84, 83, 82 (FIGS; 4, 3, 2, 1). But before chamber 81 can become sufficiently pressurized to close the throttle valve, the motor accelerates in the nut crimping direction to cause the governor weights to unseat the governor valve 63 to connect ports 70 and chamber 81 with the motor exhaust system. The motor continues to run in the nut crimping direction causing the drive nut 29 to move the travel-wedge 44 axially downward between the tail ends 50 of the jaw elements 43 until they are pivoted into contactwith the surrounding wall 40 of the holding sleeve 42. The motor then stalls permitting the governor spring 64 to overcome the force of the governor weights so as to reseat the governor valve 63 to closed condition. Live air is then directed from port 70 and the connecting ports to pressurize chamber 81 forcing the throttle valve 54 to close. This action terminates the air supply to the tool permitting all valves to return to their original position.

The sleeve valve 117 surrounding the directional valve 76 is a means of lowering the supply pressure to the motor in the nut tightening direction without affecting the supply pressure to the motor in the crimping direction. This enables the 'value of pre-torque applied to the nut to be changed without reducingthe capacity of the motor in the crimping direction. The volume under valve 117 is connected to port thus requiring a sufficient pressure drop between

ports

92 and 95 to overcome the force of spring 118.

What is claimed is:

1. In a pneumatic tool including a reversible rotary air motor, combined nut setting and crimping mechanism operatively connected with the motor having response to rotation of the motor in one direction to set a nut and having response to rotation of the motor in the opposite direction to crimp the nut; valving system having a first condition for feeding operating air to the motor in the one direction, having a shifted condition for feeding operating air to the motor in the opposite direction, and having a shut-off condition shutting off operating air feed to the motor, and centrifugally operable speed responsive governor controlled valve means rotatable by the motor and integrated in the valving system for causing automatic shifting of the valving system from its first condition to its shifted condition and from the latter condition to its shut-off condition.

2. In a pneumatic tool as in claim 1, wherein the valving system includes a manipulative throttle valve for initiating feeding of operating air to the motor in the one direction.

3. In a pneumatic tool as in claim 1, including a pres sure air feed passage for application to the valving system of pressure air to effect the shifting of the valving system from the first condition; wherein the governor controlled valve means includes a governor valve normally blocking communication of the feed passage with an exhaust port, and includes centrifugally movable weight means having response to acceleration of the motor speed above a certain level to move the governor valve to open the feed passage to the exhaust port, and having response to deceleration of the motor speed below said level to cause return of the governor valve to blocking condition.

4. In a pneumatic tool including a reversible rotary air motor, combined nut setting and crimping mechanism operatively connected with the motor having response to rotation of the motor in one direction to set a nut and having response to rotation of the motor in the opposite direction to crimp the nut; valving system having a first condition for feeding operating air to the motorin the one direction, having a shifted condition for feeding operating air to the motor in the opposite direction, and having a shut-off condition shutting off operating air feed to the motor, and centrifugallyoperable speed responsive valve means driven by the motor and integrated in the valving system for causing automatic shifting of the valving system from its first condition toits shifted condition and from the latter condition to its shut-off condition.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,797,335 Dated March 19. 1974 Invent0r(s) LESTER A. AM'ISBERG, ET. AL.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the cover sheet, insert [73] Assignee: Chicago Pneumatic Tool Company, New York, N.Y., a corporation of New Jersey Signed ahdsealed this 13th day of August l974.

(SEAL) Attest: I

MCCOY M. GIBSON; JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents FORM PO-105O (O-69) uscoMM-oc coon-Pug T u.s. GOVERNMENT rnnmuc orncz In! 0$66-33l.

Claims

3. In a pneumatic tool as in claim 1, including a pressure air feed passage for application to the valving system of pressure air to effect the shifting of the valving system from the first condition; wherein the governor controlled valve means includes a governor valve normally blocking communication of the feed passage with an exhaust port, and includes centrifugally movable weight means having response to acceleration of the motor speed above a certain level to move the governor valve to open the feed passage to the exhaust port, and having response to deceleration of the motor speed below said level to cause return of the governor valve to blocking condition.

4. In a pneumatic tool including a reversible rotary air motor, combined nut setting and crimping mechanism operatively connected with the motor having response to rotation of the motor in one direction to set a nut and having response to rotation of the motor in the opposite direction to crimp the nut; valving system having a First condition for feeding operating air to the motor in the one direction, having a shifted condition for feeding operating air to the motor in the opposite direction, and having a shut-off condition shutting off operating air feed to the motor, and centrifugally operable speed responsive valve means driven by the motor and integrated in the valving system for causing automatic shifting of the valving system from its first condition to its shifted condition and from the latter condition to its shut-off condition.