Title:
CONTROL SYSTEM FOR NUTSETTER
United States Patent 3796131
Abstract:
A control system for a pneumatic multiple nutsetter which includes control valves operable to sense motive air pressure at each tool motor inlet port. In response to a predetermined motor inlet pressure the control valves operate to turn on visual indicators and to actuate pneumatic card perforating recording apparatus for registering the completion of a fastener torquing operation. The control system includes pneumatic circuitry operable to shut off the motive air supply to deenergize the nutsetter after all individual motor units have completed their fastener torquing operations. The system also includes circuitry operable to fail to deenergize the nutsetter if a motor does not reach the predetermined inlet pressure and to deenergize the nutsetter if any one motor reaches the predetermined inlet pressure prematurely.
US Patent References:
Alarm system
Schroder - May 1967 - 3318328
Power plants
De Vita - November 1964 - 3154925
TORQUE CONTROL DEVICE FOR AIR WRENCHES
Mitani et al. - March 1969 - 3434547
WORK CONTROL SYSTEM
German - July 1971 - 3590582
APPARATUS FOR TIGHTENING SCREW CONNECTIONS TO A PRECISE TORQUE
Pantel - April 1969 - 3439754
Alarm system
Schroder - May 1967 - 3318328
Power plants
De Vita - November 1964 - 3154925
TORQUE CONTROL DEVICE FOR AIR WRENCHES
Mitani et al. - March 1969 - 3434547
WORK CONTROL SYSTEM
German - July 1971 - 3590582
APPARATUS FOR TIGHTENING SCREW CONNECTIONS TO A PRECISE TORQUE
Pantel - April 1969 - 3439754
Inventors:
Workman Jr., William (Spring Lake, MI)
Boeger, James H. (Spring Lake, MI)
Boeger, James H. (Spring Lake, MI)
Application Number:
05/218607
Publication Date:
03/12/1974
Filing Date:
01/17/1972
View Patent Images:
Export Citation:
Assignee:
Gardner-Denver Company (Quincy, IL)
Primary Class:
Other Classes:
91/35, 91/511, 173/177
International Classes:
B25B21/00; B25B23/145; F01B25/26; B25B23/14; F01B25/00; F01B25/26; F15B21/02
Field of Search:
91/35,370,371,372,433,412,1 173/12
Primary Examiner:
Geoghegan, Edgar W.
Assistant Examiner:
Zupcic A. M.
Attorney, Agent or Firm:
Martin, Michael E.
Parent Case Data:
This is a division of application Ser. No. 841,354, filed July 14, 1969 now U.S. Pat. No. 3,657,964.
Claims:
What is claimed is
1. In a control system for a fluid operated torque producing tool comprising a plurality of fluid operated motors, said motors each having a fluid inlet passage;
2. The invention set forth in claim 1 wherein:
3. The invention set forth in claim 2 wherein:
1. In a control system for a fluid operated torque producing tool comprising a plurality of fluid operated motors, said motors each having a fluid inlet passage;
2. The invention set forth in claim 1 wherein:
3. The invention set forth in claim 2 wherein:
Description:
BACKGROUND OF THE INVENTION
Pressure fluid operated tools for tightening threaded fasteners are extensively used for mechanical assembly operations in many industries. Conventional single and multiple unit tools are characterized by rotary motors drivingly connected to rotary spindle means and operating with compressed air as the motive fluid. Increasingly stringent requirements for structural integrity and quality assurance of automotive vehicles and other types of machinery which are assembled by such tools have made necessary the development of control systems which provide for automatic operation of fastener tightening tools whereby the tool operator may not influence the tool performance. Moreover, it is desirable that evidence of the satisfactory completion of a tool operating cycle be indicated to the tool operator and also permanently recorded for auditing purposes.
Control systems are known in the art of fluid operated multiple fastener torquing tools which include visual indication of the tool operating condition. U.S. Pat. Nos. 3,180,612 to E.G. Spyridakis et al. and 3,322,205 to L.A. Amtsberg et al disclose electrical control circuitry and indicators for indicating the completion of an operating cycle of a fastener tightening tool. It is desirable, however, to utilize the working fluid as a signal producing and control medium in fluid operated tools thereby simplifying the circuitry and eliminating the hazards to operators created by electrical circuits. Moreover, it is desirable to provide control means for multiple nutsetter units which will positively identify the satisfactory or unsatisfactory operation of each individual tool operating cycle and to provide for shutoff of the complete unit if any one tool is inoperable at the onset of an operating cycle.
SUMMARY OF THE INVENTION
The present invention provides a control system for a pneumatic multiple unit fastener tightening tool which utilizes the working fluid to provide a visual indication and permanent record of the completion of a satisfactory operating cycle of each individual motor unit in the tool. The control system of the present invention provides for actuating a pneumatic visual indicator and a pneumatic document perforating apparatus in response to sensing a predetermined pressure of the motive fluid at the motor inlet port of each individual motor. In making the aforementioned provision, the present invention utilizes improvements in control valve means for fluid operated tools disclosed in U.S. Pat. No. 3,493,056 by J.H. Boeger et al.
The control system of the present invention also provides for an automatic operating cycle of a multiple nutsetter unit which is operable to detect operator interference or premature removal of the tool from the workpiece. Failure of the operator to allow completion of the tool operating cycle will result in the absence of a visual indication and the failure of the pneumatic document perforating apparatus to record.
The control system of the present invention further provides means for shutting off the supply air to a multiple spindle nutsetter in the event that any one individual tool motor stalls prior to a predetermined time period in an operating cycle. Indication and recording of the prematurely stalled spindle is also provided.
In accordance with the present invention there is also provided a control system for a pneumatic multiple unit nutsetter which is operable to vary the predetermined motor inlet pressure sensing value which operates to signal the completion of a fastener tightening operation.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE is a schematic diagram of the control system of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The control circuitry shown in the drawing is represented largely by current U.S.A. Standard fluid power graphic symbols for components which are well known in the art of fluid control systems. Referring to the drawing the numeral 10 generally designates a multiple spindle pneumatic powered nutsetter. The nutsetter 10 comprises individual tool units 12 mounted on a frame 14. The tool units 12 are of a general type well known in the art of fluid operated tools and comprise compressed air operated motors 16 adapted to rotatively drive spindles 18 to which are attached wrench sockets 20. The tools 12 are operative to produce torque to drive threaded fasteners 22 to a predetermined degree of tightness in making up a mechanical joint represented by the members 24 and 26.
The motors 16 are operable to receive motive air by way of motor inlet passages 37 from a supply conduit 28 which in turn is operable to be in communication with a supply conduit 30 by way of a shutoff valve 32. Conduit 30 is operable to receive a supply of compressed air at constant pressure from a source, not shown. The valve 32 as a typical example is a two position valve operable to be shifted to position a by a spring actuator 34 and to position b by a pneumatic actuator 36.
As discussed in the disclosure of the aforementioned U.S. Pat. No. 3,493,056 the motive air pressure in the inlet passage of conventional rotary motor fastener torquing tools is responsive to the amount of torque applied to the fastener being tightened. Accordingly, motor inlet pressure may be sensed and used as a signal to shut off the supply of motive fluid to the tool when a predetermined pressure valve at the motor inlet is achieved thereby controlling the torque output of a normally operating tool. In accordance with the present invention as herein disclosed, motor inlet pressure may also be used to effect the operation of indicating and recording means when a predetermined minimum value has has been exerted on a threaded fastener.
In the control system of the FIGURE the inlet pressure of motors 16 are sensed by the conduits 38 and 40 which are in communication with passages 37 and the fluid operated actuators of two-position valves 42 and 44, respectively. The valves 42 and 44 are similar in operating principle to the control valve disclosed in U.S. Pat. No. 3,403,056. That is, a preset pressure is operable to hold valves 42 and 44 in position a. When said preset pressure value in exceeded by the pressure at the inlet of motors 16 valves 42 and 44 are shifted to position b. Pressure air at the preset biasing pressure is supplied to the position a actuators of valves 42 and 44 by way of a pressure regulator valve 46 having a settable constant pressure output. Alternatively, a pressure regulator valve 48 may be in communication with the position a actuators of valves 42 and 44 by way of the two-position valve 50 and shuttle valve 52.
The control system of the present invention also includes a two-position servo valve 54 spring biased to position a and pressure air biased to position b. The pressure air actuator of valve 54 is operable to receive a pressure signal at supply pressure from either valve 42 or 44 in position a, by way of a servo circuit comprising shuttle valve 56 and conduits 55, 57 and 58. A two-position signal switching valve 60 having a spring bias to position a and a pressure air actuator for shifting to position b is also part of the control system. Conduit 62 leading to the pressure air actuator of valve 60 includes a variable time delay device 64 which is operable to control the flow of pressure air to the actuator of valve 60. The control system further includes a second servo valve 66 and a valve 68 both of which are pressure air actuated to be in both positions a and b.
Operation of the control system disclosed is initiated by a start valve 70 interposed in conduit 72 between the main supply conduit 30 and the position b actuator of valve 68. The start valve 70 includes a manual actuator 74 for moving to position b, and is spring biased to position a. A device known as an impulse valve designated by numerals 76 and 78 operates in response to receiving a pressure air signal from valve 70 to provide a momentary signal to shift valve 68 to position b after which impulse valve 76 shifts to position b blocking further supply of signal air from the start valve 70 and venting the position b actuator of valve 68. A second manually actuated valve 80 is operable, when actuated to position b, to supply pressure air from conduit 30 to the position a actuators of valves 66 and 68.
The control system of FIG. 1 provides bimodal register means operable to indicate visually and to record the functioning or malfunctioning of the individual tools 12 as they are operated to tighten threaded fasteners to a predetermined degree of tightness. Visual indicators 82 and 84 are respectively in communication with control valves 42 and 44 and are operable to turn "on" in response to said valves shifting to position b. The indicators 82 and 84 are somewhat similar in operating principle to the fluid operated visual indicator disclosed in U.S. Pat. No. 3,372,501 to G.B. Greene and more particularly to the disclosure of U.S. Pat. No. 3,492,968 to W. Workman, Jr. A third indicator 86, similar to indicators 82 and 84, is operable to receive a pressure signal from valve 54, in position a, to indicate the completion of operation of both tools 12.
The pressure air signals receivable by indicators 82, 84 and 86 are respectively operable to be transmitted to pressure fluid operated recording means 87 represented schematically in the FIGURE by the single acting, spring return, actuators 88, 90 and 92. In response to receiving a pressure signal the actuators 88, 90 and 92 are operable to make machine readable perforations in a document such as a data processing card 94 or similarly a paper tape, not shown, by means of their respective perforating elements 91, 93 and 95. In so doing a record of the completion of operation is made for the individual tools 12 as well as a record that all tools, if operating normally, have completed torquing their respective fasteners to a predetermined degree of tightness. The indicator and recording means is also operable to register the malfunction of each tool as will be described herein.
It is believed that the system may be better understood by a description of the operations which the system is intended to perform. Prior to commencement of an operating cycle and with pressure air available in the main supply conduit 30, supply valve 32 would be in position a, control valves 42 and 44 would be biased to position a by regulated pressure air from regulator valve 46 by way of shuttle valve 52. Spring biased valves 50, 60, 70, 76 and 80 would be in position a, and valves 66 and 68 would be in position a as a result of completion of the previous operating cycle. Valve 54 would be biased to position b by pressure air from a supply conduit 96 through either valve 42 or 44, in position a, and shuttle valve 56. Indicators 82, 84 and 86 would be vented and "off," and the perforating actuators 88, 90 and 92 would have their respective perforating elements retracted away from card 94. Upon applying the spindles 18 to the fasteners 22 the tool operator would actuate start valve 70 to position b providing pressure air to shift valve 68 to position b. Valve 76 would only provide a momentary signal to valve 68 as pressure air, after a brief delay caused by time delay 78, would shift valve 76 to position b thereby precluding the continued biasing of valve 68 to position b by the operator holding valve 70 in position b. Shifting of valve 68 to position b provides pressure air from supply conduit 30, conduit 96, and conduit 98 through valve 66, in position a, to the actuator of valve 32 shifting same to position b. Valve 32 in position b provides for supply air to flow to motors 16 whereby the fasteners 22 are operated on to be tightened. Pressure air from valve 68 also flows through conduit 62 to the actuator of valve 60. However, a pressure signal of sufficient magnitude to shift valve 60 to position b is delayed by time delay 64.
As the motors 16 operate to tighten fasteners 22 pressure at the motor inlet passages is sensed in conduits 38 and 40. Upon reaching a predetermined value, greater than the regulated pressure from regulator 46 biasing valves 42 and 44 to position a, a pressure signal from said inlet passages operates to shift the valves 42 and 44 to position b. In position b valves 42 and 44 provide a pressure signal to the respective indicators 82 and 84 and, accordingly, to the respective document perforating actuators 88 and 90 operating same to perforate the card 94. When both valves 42 and 44 have shifted to position b a pressure signal is no longer provided to hold servo valve 54 biased in position b. The position b actuator of valve 54 is operable to vent through valve 42 or 44. Valve 54 thereby shifts to position a and provides a signal from supply conduit 30 and conduit 98 to operate master indicator 86 and perforating actuator 92. A pressure signal also flows through conduit 100 to hold valve 66 in position a and shift valve 68 to position a whereby the position b actuator of valve 32 is vented to atmosphere and valve 32 operates to position a to shut off flow of motive fluid to motors 16. Orifice 99 prevents rapid loss of pressure through valve 80, in position a. A time delay 102 retards the signal to shift valve 68 to position a to assure that equal torquing of all fasteners is accomplished. Unequal torquing by multiple motor unit nutsetters often results from one fastener reaching a predetermined tightness before another whereby mating surfaces of two members being joined are misaligned. When subsequent motors have stalled, the surfaces are realigned thereby often relaxing the degree of tightness of the fastener associated with the first stalled motor.
In a normal operating cycle as described above, time delay 64 would be set to provide an adequate pressure signal to shift valve 60 to position b before the shifting of any one of control valves 42 and 44 to position b. However, if a motor 16 or spindle 18 were locked due to a damaged tool component or fastener a motor inlet pressure sufficient to shift its respective control valve to position b would be quickly sensed due to the stalled condition of said motor. Accordingly, pressure air would flow through a second servo circuit comprising conduits 101 or 103, conduit 105, shuttle valve 104, and valve 60, the latter still in position a as a result of the delay in shifting to position b caused by time delay 64. Pressure air from the control valve of the stalled motor would then operate to shift servo valve 66 to position b thereby venting the actuator 36 of valve 32 causing same to shut off motive air to the tools 12. A pressure signal from the faulty tool would also operate to turn on its respective indicator and to record which tool had malfunctioned by means of its respective perforating actuator. Furthermore, pressure air could not be supplied to restart the motors without operator acknowledgment of the malfunction by actuation of reset valve 80 to position b.
In the event of a stripped thread condition or if a fastener would be missing altogether the associated motor would not achieve the predetermined inlet pressure sufficient to shift its respective control valve to position b consequently failing to indicate or record a satisfactory torquing operation. Moreover, servo valve 54 would remain in position b thereby failing to provide for operation of shut-off valve 32 to shutoff motive air to the motors 16. Under such a condition all motors would be exerting a torque effort on their respective fasteners and removal of the unit from the work would be difficult. Further operator acknowledgment of the condition would be required by actuation of the reset valve 80 whose operation is explained herein.
The control system of the present invention also includes means for automatically changing the biasing pressure which operates to hold control valves 42 and 44 in position a in opposition to the pressure at the motor inlet ports. The multiple spindle nutsetter 10 is typical of conventional nutsetters in the sense that normally all tool motors will not reach their maximum torquing effort or approach stalling simultaneously. Therefore, a motor may slow down or approach a stalling condition whereby less motive air is being consumed by that motor and consequently more motive air is now available at the inlet ports of the remaining motors which may still be driving their respective fasteners. The reduced consumption of motive air caused by the aforementioned condition usually results in a momentary rapid increase or pulse of motive air pressure at the inlet ports of the motors which are still running. This momentary pressure increase is often sufficient to effect shifting of the respective control valves of the motors which are still running even though the motors themselves have not had the increased pressure imposed on them sufficiently long enough for proper torquing of their respective fasteners.
To overcome the above mentioned premature shutoff condition in the nutsetter 10 the time delay means 64 is set to operate to shift valve 60 to position b before either valve 42 or 44 shifts to position b in a normal fastener tightening operation. With valve 60 in position b when either valve 42 or 44 shifts to position b pressure air will flow through shuttle valve 104 and valve 60 to the pressure air actuator of valve 50 shifting same to position b. Pressure regulator valve 48, which is set to produce a predetermined constant output pressure greater than the constant output pressure of regulator 46, will provide an increased biasing pressure supply through valve 50, in position b, and shuttle valve 52. Valves 42 and 44 will then have a greater biasing pressure operating to bias them in position a. Since one of valves 42 or 44 has already operated to position b to initiate the change in bias pressure as described above, a momentary reshifting of said one valve to position a may occur. However, said one valve has already operated to register a satisfactory predetermined torquing effort of its associated tool motor by means of the recording apparatus 87.
In any condition of operation of the control system of the FIGURE the motive air supply to the nutsetter 10 may be interrupted and the system reset to the condition at which a normal operating cycle begins. Manual actuation of the reset valve 80 to position b operates to provide pressure air to actuate valves 66 and 68 to position a simulating, except for operation of the register means, the completion of a normal operating cycle by venting the actuator 36 of supply valve 32. Valve 32, accordingly, shifts to position a shutting off the motive air supply to the motors 16. The actuator of valve 60 is vented through valve 68 thereby returning valve 60 to position a. The position b actuators of valves 42 and 44 are operable to be vented internally through motors 16 thereby providing for said valves to be biased to position a by regulated pressure air from valve 46.
For purposes of clarity the disclosed control system of the FIGURE is shown as being operable to control a multiple tool nutsetter having two individual tool units. Those skilled in the art of designing fluid control circuits will appreciate that virtually any number of tool units may be controlled by the system of the FIGURE by the addition of a control valve, indicator, and perforating actuator for each additional tool unit. Moreover, additional shuttle valves may be suitably arranged in circuit with valve 56 and one another to provide a signal to the position b actuator of valve 54 as long as at least one tool has not reached the predetermined control valve position b shifting pressure. In a similar manner additional shuttle valves would be required to be in circuit with valve 104 to provide a signal to the position b actuator of valve 50 by way of valve 60.
Pressure fluid operated tools for tightening threaded fasteners are extensively used for mechanical assembly operations in many industries. Conventional single and multiple unit tools are characterized by rotary motors drivingly connected to rotary spindle means and operating with compressed air as the motive fluid. Increasingly stringent requirements for structural integrity and quality assurance of automotive vehicles and other types of machinery which are assembled by such tools have made necessary the development of control systems which provide for automatic operation of fastener tightening tools whereby the tool operator may not influence the tool performance. Moreover, it is desirable that evidence of the satisfactory completion of a tool operating cycle be indicated to the tool operator and also permanently recorded for auditing purposes.
Control systems are known in the art of fluid operated multiple fastener torquing tools which include visual indication of the tool operating condition. U.S. Pat. Nos. 3,180,612 to E.G. Spyridakis et al. and 3,322,205 to L.A. Amtsberg et al disclose electrical control circuitry and indicators for indicating the completion of an operating cycle of a fastener tightening tool. It is desirable, however, to utilize the working fluid as a signal producing and control medium in fluid operated tools thereby simplifying the circuitry and eliminating the hazards to operators created by electrical circuits. Moreover, it is desirable to provide control means for multiple nutsetter units which will positively identify the satisfactory or unsatisfactory operation of each individual tool operating cycle and to provide for shutoff of the complete unit if any one tool is inoperable at the onset of an operating cycle.
SUMMARY OF THE INVENTION
The present invention provides a control system for a pneumatic multiple unit fastener tightening tool which utilizes the working fluid to provide a visual indication and permanent record of the completion of a satisfactory operating cycle of each individual motor unit in the tool. The control system of the present invention provides for actuating a pneumatic visual indicator and a pneumatic document perforating apparatus in response to sensing a predetermined pressure of the motive fluid at the motor inlet port of each individual motor. In making the aforementioned provision, the present invention utilizes improvements in control valve means for fluid operated tools disclosed in U.S. Pat. No. 3,493,056 by J.H. Boeger et al.
The control system of the present invention also provides for an automatic operating cycle of a multiple nutsetter unit which is operable to detect operator interference or premature removal of the tool from the workpiece. Failure of the operator to allow completion of the tool operating cycle will result in the absence of a visual indication and the failure of the pneumatic document perforating apparatus to record.
The control system of the present invention further provides means for shutting off the supply air to a multiple spindle nutsetter in the event that any one individual tool motor stalls prior to a predetermined time period in an operating cycle. Indication and recording of the prematurely stalled spindle is also provided.
In accordance with the present invention there is also provided a control system for a pneumatic multiple unit nutsetter which is operable to vary the predetermined motor inlet pressure sensing value which operates to signal the completion of a fastener tightening operation.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE is a schematic diagram of the control system of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The control circuitry shown in the drawing is represented largely by current U.S.A. Standard fluid power graphic symbols for components which are well known in the art of fluid control systems. Referring to the drawing the numeral 10 generally designates a multiple spindle pneumatic powered nutsetter. The nutsetter 10 comprises individual tool units 12 mounted on a frame 14. The tool units 12 are of a general type well known in the art of fluid operated tools and comprise compressed air operated motors 16 adapted to rotatively drive spindles 18 to which are attached wrench sockets 20. The tools 12 are operative to produce torque to drive threaded fasteners 22 to a predetermined degree of tightness in making up a mechanical joint represented by the members 24 and 26.
The motors 16 are operable to receive motive air by way of motor inlet passages 37 from a supply conduit 28 which in turn is operable to be in communication with a supply conduit 30 by way of a shutoff valve 32. Conduit 30 is operable to receive a supply of compressed air at constant pressure from a source, not shown. The valve 32 as a typical example is a two position valve operable to be shifted to position a by a spring actuator 34 and to position b by a pneumatic actuator 36.
As discussed in the disclosure of the aforementioned U.S. Pat. No. 3,493,056 the motive air pressure in the inlet passage of conventional rotary motor fastener torquing tools is responsive to the amount of torque applied to the fastener being tightened. Accordingly, motor inlet pressure may be sensed and used as a signal to shut off the supply of motive fluid to the tool when a predetermined pressure valve at the motor inlet is achieved thereby controlling the torque output of a normally operating tool. In accordance with the present invention as herein disclosed, motor inlet pressure may also be used to effect the operation of indicating and recording means when a predetermined minimum value has has been exerted on a threaded fastener.
In the control system of the FIGURE the inlet pressure of motors 16 are sensed by the conduits 38 and 40 which are in communication with passages 37 and the fluid operated actuators of two-position valves 42 and 44, respectively. The valves 42 and 44 are similar in operating principle to the control valve disclosed in U.S. Pat. No. 3,403,056. That is, a preset pressure is operable to hold valves 42 and 44 in position a. When said preset pressure value in exceeded by the pressure at the inlet of motors 16 valves 42 and 44 are shifted to position b. Pressure air at the preset biasing pressure is supplied to the position a actuators of valves 42 and 44 by way of a pressure regulator valve 46 having a settable constant pressure output. Alternatively, a pressure regulator valve 48 may be in communication with the position a actuators of valves 42 and 44 by way of the two-position valve 50 and shuttle valve 52.
The control system of the present invention also includes a two-position servo valve 54 spring biased to position a and pressure air biased to position b. The pressure air actuator of valve 54 is operable to receive a pressure signal at supply pressure from either valve 42 or 44 in position a, by way of a servo circuit comprising shuttle valve 56 and conduits 55, 57 and 58. A two-position signal switching valve 60 having a spring bias to position a and a pressure air actuator for shifting to position b is also part of the control system. Conduit 62 leading to the pressure air actuator of valve 60 includes a variable time delay device 64 which is operable to control the flow of pressure air to the actuator of valve 60. The control system further includes a second servo valve 66 and a valve 68 both of which are pressure air actuated to be in both positions a and b.
Operation of the control system disclosed is initiated by a start valve 70 interposed in conduit 72 between the main supply conduit 30 and the position b actuator of valve 68. The start valve 70 includes a manual actuator 74 for moving to position b, and is spring biased to position a. A device known as an impulse valve designated by numerals 76 and 78 operates in response to receiving a pressure air signal from valve 70 to provide a momentary signal to shift valve 68 to position b after which impulse valve 76 shifts to position b blocking further supply of signal air from the start valve 70 and venting the position b actuator of valve 68. A second manually actuated valve 80 is operable, when actuated to position b, to supply pressure air from conduit 30 to the position a actuators of valves 66 and 68.
The control system of FIG. 1 provides bimodal register means operable to indicate visually and to record the functioning or malfunctioning of the individual tools 12 as they are operated to tighten threaded fasteners to a predetermined degree of tightness. Visual indicators 82 and 84 are respectively in communication with control valves 42 and 44 and are operable to turn "on" in response to said valves shifting to position b. The indicators 82 and 84 are somewhat similar in operating principle to the fluid operated visual indicator disclosed in U.S. Pat. No. 3,372,501 to G.B. Greene and more particularly to the disclosure of U.S. Pat. No. 3,492,968 to W. Workman, Jr. A third indicator 86, similar to indicators 82 and 84, is operable to receive a pressure signal from valve 54, in position a, to indicate the completion of operation of both tools 12.
The pressure air signals receivable by indicators 82, 84 and 86 are respectively operable to be transmitted to pressure fluid operated recording means 87 represented schematically in the FIGURE by the single acting, spring return, actuators 88, 90 and 92. In response to receiving a pressure signal the actuators 88, 90 and 92 are operable to make machine readable perforations in a document such as a data processing card 94 or similarly a paper tape, not shown, by means of their respective perforating elements 91, 93 and 95. In so doing a record of the completion of operation is made for the individual tools 12 as well as a record that all tools, if operating normally, have completed torquing their respective fasteners to a predetermined degree of tightness. The indicator and recording means is also operable to register the malfunction of each tool as will be described herein.
It is believed that the system may be better understood by a description of the operations which the system is intended to perform. Prior to commencement of an operating cycle and with pressure air available in the main supply conduit 30, supply valve 32 would be in position a, control valves 42 and 44 would be biased to position a by regulated pressure air from regulator valve 46 by way of shuttle valve 52. Spring biased valves 50, 60, 70, 76 and 80 would be in position a, and valves 66 and 68 would be in position a as a result of completion of the previous operating cycle. Valve 54 would be biased to position b by pressure air from a supply conduit 96 through either valve 42 or 44, in position a, and shuttle valve 56. Indicators 82, 84 and 86 would be vented and "off," and the perforating actuators 88, 90 and 92 would have their respective perforating elements retracted away from card 94. Upon applying the spindles 18 to the fasteners 22 the tool operator would actuate start valve 70 to position b providing pressure air to shift valve 68 to position b. Valve 76 would only provide a momentary signal to valve 68 as pressure air, after a brief delay caused by time delay 78, would shift valve 76 to position b thereby precluding the continued biasing of valve 68 to position b by the operator holding valve 70 in position b. Shifting of valve 68 to position b provides pressure air from supply conduit 30, conduit 96, and conduit 98 through valve 66, in position a, to the actuator of valve 32 shifting same to position b. Valve 32 in position b provides for supply air to flow to motors 16 whereby the fasteners 22 are operated on to be tightened. Pressure air from valve 68 also flows through conduit 62 to the actuator of valve 60. However, a pressure signal of sufficient magnitude to shift valve 60 to position b is delayed by time delay 64.
As the motors 16 operate to tighten fasteners 22 pressure at the motor inlet passages is sensed in conduits 38 and 40. Upon reaching a predetermined value, greater than the regulated pressure from regulator 46 biasing valves 42 and 44 to position a, a pressure signal from said inlet passages operates to shift the valves 42 and 44 to position b. In position b valves 42 and 44 provide a pressure signal to the respective indicators 82 and 84 and, accordingly, to the respective document perforating actuators 88 and 90 operating same to perforate the card 94. When both valves 42 and 44 have shifted to position b a pressure signal is no longer provided to hold servo valve 54 biased in position b. The position b actuator of valve 54 is operable to vent through valve 42 or 44. Valve 54 thereby shifts to position a and provides a signal from supply conduit 30 and conduit 98 to operate master indicator 86 and perforating actuator 92. A pressure signal also flows through conduit 100 to hold valve 66 in position a and shift valve 68 to position a whereby the position b actuator of valve 32 is vented to atmosphere and valve 32 operates to position a to shut off flow of motive fluid to motors 16. Orifice 99 prevents rapid loss of pressure through valve 80, in position a. A time delay 102 retards the signal to shift valve 68 to position a to assure that equal torquing of all fasteners is accomplished. Unequal torquing by multiple motor unit nutsetters often results from one fastener reaching a predetermined tightness before another whereby mating surfaces of two members being joined are misaligned. When subsequent motors have stalled, the surfaces are realigned thereby often relaxing the degree of tightness of the fastener associated with the first stalled motor.
In a normal operating cycle as described above, time delay 64 would be set to provide an adequate pressure signal to shift valve 60 to position b before the shifting of any one of control valves 42 and 44 to position b. However, if a motor 16 or spindle 18 were locked due to a damaged tool component or fastener a motor inlet pressure sufficient to shift its respective control valve to position b would be quickly sensed due to the stalled condition of said motor. Accordingly, pressure air would flow through a second servo circuit comprising conduits 101 or 103, conduit 105, shuttle valve 104, and valve 60, the latter still in position a as a result of the delay in shifting to position b caused by time delay 64. Pressure air from the control valve of the stalled motor would then operate to shift servo valve 66 to position b thereby venting the actuator 36 of valve 32 causing same to shut off motive air to the tools 12. A pressure signal from the faulty tool would also operate to turn on its respective indicator and to record which tool had malfunctioned by means of its respective perforating actuator. Furthermore, pressure air could not be supplied to restart the motors without operator acknowledgment of the malfunction by actuation of reset valve 80 to position b.
In the event of a stripped thread condition or if a fastener would be missing altogether the associated motor would not achieve the predetermined inlet pressure sufficient to shift its respective control valve to position b consequently failing to indicate or record a satisfactory torquing operation. Moreover, servo valve 54 would remain in position b thereby failing to provide for operation of shut-off valve 32 to shutoff motive air to the motors 16. Under such a condition all motors would be exerting a torque effort on their respective fasteners and removal of the unit from the work would be difficult. Further operator acknowledgment of the condition would be required by actuation of the reset valve 80 whose operation is explained herein.
The control system of the present invention also includes means for automatically changing the biasing pressure which operates to hold control valves 42 and 44 in position a in opposition to the pressure at the motor inlet ports. The multiple spindle nutsetter 10 is typical of conventional nutsetters in the sense that normally all tool motors will not reach their maximum torquing effort or approach stalling simultaneously. Therefore, a motor may slow down or approach a stalling condition whereby less motive air is being consumed by that motor and consequently more motive air is now available at the inlet ports of the remaining motors which may still be driving their respective fasteners. The reduced consumption of motive air caused by the aforementioned condition usually results in a momentary rapid increase or pulse of motive air pressure at the inlet ports of the motors which are still running. This momentary pressure increase is often sufficient to effect shifting of the respective control valves of the motors which are still running even though the motors themselves have not had the increased pressure imposed on them sufficiently long enough for proper torquing of their respective fasteners.
To overcome the above mentioned premature shutoff condition in the nutsetter 10 the time delay means 64 is set to operate to shift valve 60 to position b before either valve 42 or 44 shifts to position b in a normal fastener tightening operation. With valve 60 in position b when either valve 42 or 44 shifts to position b pressure air will flow through shuttle valve 104 and valve 60 to the pressure air actuator of valve 50 shifting same to position b. Pressure regulator valve 48, which is set to produce a predetermined constant output pressure greater than the constant output pressure of regulator 46, will provide an increased biasing pressure supply through valve 50, in position b, and shuttle valve 52. Valves 42 and 44 will then have a greater biasing pressure operating to bias them in position a. Since one of valves 42 or 44 has already operated to position b to initiate the change in bias pressure as described above, a momentary reshifting of said one valve to position a may occur. However, said one valve has already operated to register a satisfactory predetermined torquing effort of its associated tool motor by means of the recording apparatus 87.
In any condition of operation of the control system of the FIGURE the motive air supply to the nutsetter 10 may be interrupted and the system reset to the condition at which a normal operating cycle begins. Manual actuation of the reset valve 80 to position b operates to provide pressure air to actuate valves 66 and 68 to position a simulating, except for operation of the register means, the completion of a normal operating cycle by venting the actuator 36 of supply valve 32. Valve 32, accordingly, shifts to position a shutting off the motive air supply to the motors 16. The actuator of valve 60 is vented through valve 68 thereby returning valve 60 to position a. The position b actuators of valves 42 and 44 are operable to be vented internally through motors 16 thereby providing for said valves to be biased to position a by regulated pressure air from valve 46.
For purposes of clarity the disclosed control system of the FIGURE is shown as being operable to control a multiple tool nutsetter having two individual tool units. Those skilled in the art of designing fluid control circuits will appreciate that virtually any number of tool units may be controlled by the system of the FIGURE by the addition of a control valve, indicator, and perforating actuator for each additional tool unit. Moreover, additional shuttle valves may be suitably arranged in circuit with valve 56 and one another to provide a signal to the position b actuator of valve 54 as long as at least one tool has not reached the predetermined control valve position b shifting pressure. In a similar manner additional shuttle valves would be required to be in circuit with valve 104 to provide a signal to the position b actuator of valve 50 by way of valve 60.