US 3897834 A
Wrench apparatus capable of applying extra rotation to a part to be tightened, for example, a bolt or nut located in an environment in which tightness is essential. The apparatus comprises a motor driven drive shaft having spline teeth that are drivingly engaged with a tubular worm telescoped over the drive shaft and operable to drive a worm gear so as to achieve an initial torque. A fluid-operated cylinder assembly is connected in a coaxial relation to the worm and is operable to move the worm axially of the drive shaft so as to drive the worm gear and rotate the wrench through a predetermined angle over and above the torque that the motor driven drive shaft is capable of imparting to the worm gear.
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Description (OCR text may contain errors)
United States Patent Swopsher et a1.
TORQUE AND TURN WRENCH APPARATUS Inventors: John A. Swopsher, Holly; Vernon A. Riddell, Mt. Clemens both of Mich Assignee: La Salle Machine Tool, 1nc.,
Filed: Mar. 27 1974 Appl. No; 455.277
Aug. 5, 1975  ABSTRACT Wrench apparatus capable of applying extra rotation to a part to be tightened, for example, a bolt 01' nut located in an environment in which tightness is essential. The apparatus comprises a motor driven drive shaft having spline teeth that are drivingly engaged with a tubular worm telescoped over the drive shaft and 0perable to drive a worm gear so as to achieve an initial torque. A fluid-operated cylinder assembly is connected in a coaxial relation to the worm and is operable to move the worm axially of the drive shaft so as to drive the worm gear and rotate the wrench through a predetermined angle over and above the torque that the motor driven drive shaft is capable of imparting to the worm gear 5 Claims, 2 Drawing Figures TORQUE AND TURN WRENCH APPARATUS BACKGROUND OF THE INVENTION In some mechanical apparatus, tightening of the nuts and bolts in the apparatus much tighter than usual is desirable. Prior art apparatus available for this purpose has been found to be particularly complex and expen sive. The object of the present invention. therefore, is to provide torque wrench apparatus which is capable of operating automatically in assembly line systems to achieve the extra torque that is required to tighten nuts and bolts much tighter than is usual.
SUMMARY OF THE INVENTION The apparatus of this invention comprises one or more torque wrench units, each of which includes a drive shaft having external spline teeth, a tubular worm telescoped over the drive shaft and having internal spline teeth that mesh with the spline teeth on the drive shaft, and a worm gear arranged in a driven relation with the worm and in a driving relation with the wrench. A fluid motor drives the drives the drive shaft and is mounted so that when a peak torque is obtained on the drive shaft, the motor housing will rotate a small distance thereby signaling the fact that the peak torque has been achieved. The motor is then stopped so as to prevent further rotation of the worm.
A fluid-actuated cylinder assembly is disposed in a coaxial relation with the worm and is connected through a rotatable joint to the worm. When the peak torque signal occurs, the cylinder assembly is actuated so as to move the worm axially on the drive shaft spline teeth so as to move the worm gear through a predetermined angle thereby rotating the wrench through the same angle without direct consideration for ultimate torque on the part. During axial movement of the worm, it does not rotate, but functions like a rack to rotate the worm gear which in turn functions like a pinion.
The cooperation of the cylinder assembly with the splined drive shaft, and the tubular worm thus provides simple, easily maintained apparatus capable of achiev ing the desired extra wrench rotation after the initial torque has been achieved. An extra angular movement of the nut or bolt is thus obtained. The fluid motor and the cylinder assembly are interconnected by a simple switch arrangement which provides for automatic oper ation of the drive motor and the cylinder assembly to achieve the desired cycle of operation.
Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:
FIG. 1 is a side elevational view of the apparatus of this invention;
FIG. 2 is a fragmentary sectional view on a reduced scale of the apparatus of this invention as seen from substantially the line 22 in FIG. 1', and
FIG. 3 is a fragmentary sectional view of a portion of the apparatus of this invention as seen from the line 3-3 in FIG. 1.
With reference to the drawing, the torque wrench apparatus of this invention, indicated generally at in FIGS. 1 and 2, is illustrated as consisting of a pair of torque wrench units 12 and 14, but it is to be understood that the apparatus 10 can be embodied in any number of units and consequently only one of the units will be described in detail herein since all units are identical and operate independently. As shown in FIG. 2, the unit 14 consists of a hydraulic motor 16 keyed to a drive shaft 18 provided with external spline teeth 20. A tubular worm 22 having internal spline teeth 24 is telescoped over the drive shaft 18 so as to mesh the teeth 24 with the teeth 20. The external gear teeth 26 on the worm 22 mesh with a worm gear 28 mounted in the housing 30 in which the unit 14 is enclosed. The worm gear 28 is drivingly connected to a driven shaft 32 which drives a conventional torque wrench head 34 (FIG. 1).
A fluid-actuated cylinder assembly 36 has its cylinder 38 mounted on the housing 30 and its piston rod 40 connected through a rotatable joint 42 to the worm 22 which is located in a coaxial relation with the piston rod 40. The cylinder assembly 36 is capable of moving the joint 42 between the solid and broken line positions shown in FIG. 2 to thereby achieve axial movement of the worm 22 with a resultant rotation of the worm gear 28 for reasons hereinafter explained in detail in connection with the description of the operation of the ap paratus 10. The unit I2 is identical to the unit 14 and is disposed in a side-by-side relation therewith for driving a wrench head identical to the wrench head 34. Like numerals are therefore used in the drawing to indicate parts of the unit I2 that are like similarly numbered parts of the unit 14.
In the operation of the apparatus 10, the cylinder assembly 36 is initially actuated to position the rotable joint 42 in the solid line position shown in FIG. 2. The wrench head 34 is engaged with the nut or bolt to be tightened and the motor 16 is operated to rotate the drive shaft 18 to in turn rotate the head 34 and tighten the nut or bolt. When a peak torque is achieved at the wrench head 34, corresponding to the maximum torque that the motor 16 is capable of applying, the motor housing 44 will rotate on the housing 30 on which it is supported in a counter-clockwise direction as viewed in FIGv I so as to move a pin 46 thereon from the illustrated broken line position to the solid line position. During such movement of the pin 46 it engages one end of a plunger 48 and moves the plunger 48 against the pressure of a spring 50 to a position in which a pin 49 associated with the spring 50 will engage the actuating arm 52 for a switch 54. As shown in FIG. I, the pin 49 is mounted on threads 51 so it can be adjusted to thereby adjust the torque at which the switch 54 will be actuated.
Actuation of the switch 54 causes the cylinder assembly 36 to retract the piston 40 so as to move the rotatable joint 42 to the broken line position shown in FIG. 2 and thereby move the worm 22 axially of the drive shaft 18. This axial movement of the worm 22 rotates the worm gear 28 through a predetermined angle necessary to move the wrench head 34 and the nut or bolt being tightened through the same angle. In a preferred embodiment of the invention, this predetermined angle is [20 but it is to be understood that any desired angle can be achieved with the apparatus 10.
As shown in FIG. 2, the piston rod 40 is connected to the rotatable joint 42 by a link 56 which carries an arm 58. The arm 58 is in turn connected to a rod 60 (FIG. 3) which is slideably mounted on the housing 30 and extends into a switch box 62 mounted on the housing 30. when the piston rod 40 is actuated to move the rotatable joint 42 to the broken line position shown in FIG. 2, the arm 58 is similarly moved to the broken line position shown in FIG. 3 to in turn move the rod 60 to a position in which an actuating nut 64 thereon trips an actuating lever 66 for switch 68.
Actuation of the switch 68 terminates operation of 5 the cylinder assembly 36 and shuts off the motor 16. The wrench head 34 is disengaged from the nut or bolt being tightened and the cylinder assembly 36 is reverse operated to return the rotable joint 42 to the solid line position shown in FIG. 2 in preparation for the next cycle of operation of the apparatus 10. When the rotatable joint 42 is in the proper position, a nut 70 on the rod 60 trips the actuating lever 72 for a switch 74 that signals the location of the joint 42 in the desired position. When the motor 14 was shutoff, the actuating pin 46 returned to its broken line position shown in FIG. 1 so that the apparatus is now in condition for repeating the cyle described above.
The initial torque to be applied by the motor 44 is readily adjustable by adjusting the position of pin 49. Likewise the position of the nut 64 can be adjusted to vary the extra angle that is to be achieved by axial movement of worm 24.
From the above description it is seen that this inven tion provides torque wrench apparatus 10 that is capable of imparting a predetermined torque and turn movement to the wrench head 34. This desirable objective is accomplished in a relatively simple manner by virtue of the cooperative arrangement of the worm 22 with the coaxial drive shaft 18 and piston rod 40. This arrangement provides the apparatus 10 with the sim plicity that is wanted in automation apparatus capable of operating efficiently over a prolonged service life. The apparatus 10 is also capable of operation to loosen a part by engaging the wrench head 34 with the part when the piston rod 40 is retracted and then extending the piston rod. If necessary. this step can be repeated.
The apparatus 10 can then be moved through the above described cycle to re-torque and turn the part.
What is claimed is:
1. Apparatus comprising a drive shaft having external spline teeth. a tubular worm telescoped over said drive shaft and having internal spline teeth meshingly engaged with said drive shaft spline teeth, a worm gear arranged in a driven relation with said worm, motor means connected in a driving relation to said drive shaft and operable to rotate said drive shaft to in turn rotate said worm and drive said worm gear, and power means connected to said worm and operable to move said worm axially of said drive shaft so as to drive said worm gear.
2. Apparatus according to claim I wherein said power means comprises a fluid actuated cylinder assembly disposed in a coaxial relation with and spaced longitudinally from said worm.
3. Apparatus according to claim 2 further including rotatable joint means connected to and extending between said cylinder assembly and said worm and operable to transmit axial forces to said worm while enabling relative rotational movement between said cylinder assembly and said worm.
4. Apparatus according to claim I wherein said motor means comprises a fluid motor. support means for said fluid motor having said fluid motor mounted thereon so that in response to a predetermined load on said drive shaft. said motor will move on said support, switch means responsive to said motor movement, and means responsive to actuation of said switch means providing for operation of said cylinder assembly.
5. Apparatus according to claim 4 further including control switch means for said cylinder assembly and adjustable means responsive to operation of said cylinder assembly for actuating said switch assembly.