US3611796A - Torque indicating hex key - Google Patents

Abstract

A HEX KEY WRENCH WITH A TORQUE INDICATING DEVICE WHICH IS ADJUSTABLY ATTACHED TO THE TORQUE APPLYING LEG OF THE WRENCH. THE TORQUE INDICATING DEVICE HAS AN INDICATING ARM EXTENDING ALONG THE TORQUE APPLYING LEG OF THE WRENCH IN SPACED RELATION THERETO TO A POINT ADJACENT THE BOLT ENGAGING LEG OF THE WRENCH. THE TORQUE APPLYING LEG OF THE WRENCH DEFLECTS SLIGHTLY WHEN THE WRENCH IS USED TO TIGHTEN A BOLT AND, SINCE THE INDICATING DEVICE IS FIXED TO THE TORQUE APPLYING LEG AT ONE END, THE END FIXED TO THE TORQUE APPLYING LEG ALSO DEFLECTS THUS CAUSING THE OTHER END OF THE INDICATING ARM TO CONTACT THE RELATIVELY STATIONARY BOLTENGAGING LEG OF THE WRENCH. THE LENGTH AND POSITION OF THE INDICATING ARM IS SELECTED TO BE REPRESENTATIVE OF A PARTICULAR TORQUE AND WHEN THE ARM CONTACTS THE BOLT ENGAGING LEG, A VISUAL INDICATION MAY BE MADE THAT THE DESIRED TORQUE HAS BEEN APPLIED.

Description

Oct. 12, 1971 w HAYWARD 3,611,796

TORQUE INDICATING HEX KEY Filed Nov. 28, 1969 INVI'IIVI' H. WALTER H. HAYWARD ,7 (AI/LL); ATTORNEYS United States Patent US. Cl. 73-139 4 Claims ABSTRACT OF THE DISCLOSURE A hex key wrench with a torque indicating device which is adjustably attached to the torque applying leg of the wrench. The torque indicating device has an indicating arm extending along the torque applying leg of the wrench in spaced relation thereto to a point adjacent the bolt engaging leg of the wrench. The torque applying leg of the wrench deflects slightly when the wrench is used to tighten a bolt and, since the indicating device is fixed to the torque applying leg at one end, the end fixed to the torque applying leg also deflects thus causing the other end of the indicating arm to contact the relatively stationary boltengaging leg of the wrench. The length and position of the indicating arm is selected to be representative of a particular torque and when the arm contacts the bolt engaging leg, a visual indication may be made that the desired torque has been applied.

This invention relates to hand tools and more particularly to a torque indicating wrench used as a production tool wherein the wrench is designed to apply uniformly a predetermined tightening torque to a fastening element, such as a bolt.

In production line applications where the line is set up to mass produce a product and where socket head screws, bolts, or the like are used as a fastening element, the screws or bolts should ideally be seated with the same tightening torque. In many instances, it is imperative that the recommended tightening torque for the bolt be applied to induce the specified design load in order to have product function in the proper manner. In addition, if the bolt is over-torqued there is the possibility that the bolt itself will snap, or that the product will be Brinelled or deformed in some manner and if insufficient torque is applied, the fastening element will be too loose and the parts will not be secured together properly.

The problem of improper seating torque may be obviated by use of a torque wrench. Such wrenches as have been used heretofore have a dial indicator associated with the wrench on which the magnitude of the applied torque in inch-pounds or foot-pounds, can be read directly. These torque wrenches are designed for a wide range of uses and can apply any desired tightening torque Within a specified range. Consequently, these are relatively expensive, usually large and cumbersome to use, are subject to damage and miscalibration when dropped or otherwise subjected to high impact stresses and in general are not feasible for production line use where the range of applicable use is limited, most often to a single value of applied tightening torque. Additionally, since the torque must be read on the dial indicator while the operator is applying the torque, there is a tendency to apply the torque slowly and carefully while watching the dial indicator which adds considerably to production time.

It is therefore an object of this invention to provide a torque wrench that will overcome the above difiiculties. It is another object of the invention to provide a torque wrench including indicating means calibrated to effect a desired predetermined tightness of the fasteners. It is still another object of the invention to provide a device of this character which is simple construction and durable in use.

In accordance with a preferred embodiment of the present invention, a torque wrench is provided which comprises an L-shaped wrench having one leg adapted to engage the socket of a socket head screw and a second torque applying leg or handle. Usually such wrenches have a hexagonally shaped exterior to conform to the hexagonally shaped wrenching surface of a socket head bolt. A torque indicator, including a torque indicating arm is slidably mounted on the torque applying leg whereby the indicating arm extends along the second leg, spaced slightly therefrom, to a point adjacent the engaging leg. As tightening torque is applied, the torque applying leg deflects slightly and since the torque indicator is fixed on this leg, it also deflects with respect to the bolt engaging leg. The indicating arm is removably mounted and is of a preselected length, proportional to the desired predetermined torque and, upon deflection of the torque applying leg, will contact the engaging leg. Since the deflection is proportional to a preselected tightening torque to be applied to the bolt, the indicating arm may thus be used to indicate the predetermined value of the preselected tightening torque.

The construction of such a preferred embodiment as well as the advantage thereof, which includes simplicity of design and economy of manufacture, ready adaptability to rapid production line applications, relative ease in changing indicating arms to increase versatility in order to indicate varying torques, and simplicty of use, will become further apparent from the following specification when considered in conjunction with the accompanying drawing wherein:

FIG. 1 is a plan view showing the torque indicating wrench of the present invention in engagement with a socket head screw;

FIG. 2 is a plan view of the device showing the deflection of the wrench handle and the contact of the indicator arm and engaging leg;

FIG. 3 is an elevational view of the device of FIG. 1;

FIG. 4 is a front view of the device of FIG. 1; and

FIG. 5 is a sectional view taken on line 55 of FIG. 3.

With reference to the drawing, there is shown an L- shaped hex key wrench 10 having a bolt engaging leg 12 and a handle or torque applying leg 14. The leg 12 is shown positioned in the socket of a bolt or screw 16 which is threadably received in a work piece 18.

A torque indicating device 20 is slidably positioned on the leg 14 and includes a mounting portion 22 and an indicator arm 24. As seen in FIG. 5, mounting portion 22 has a hexagonally shaped bore 26 to snugly but slidably receive leg 14. The indicator arm 24 is removably attached to the mounting portion 22 at one end 30 by pins 28, or other well-known detachable fastening means, and extends longitudinally along and somewhat below the leg 14. The free end of arm 24, as seen in FIG. 1, is located adjacent the bolt engaging leg 12 and the entire arm is spaced slightly from the legs of the wrench. Set screws 32 serve to fix the entire torque indicating device in a predetermined position on leg 14 as will be more fully described below. Clearly, any other slidably mounting means, such as a spring clip, may be used in lieu of portion 22 and set screws 32.

To engage bolt 16 in work piece 18, the engaging leg 12 is inserted in the socket 25 of the screw and torque is applied to the wrench as by grasping leg14 and turning the wrench. As the wrench is turned, the handle 14 and indicator device 20 will rotate with the engaging leg 12 until the screw is seated but when tightening torque is applied, the leg 14 will deflect slightly with respect to leg 12. Since the torque indicating device 20 is mounted on leg 14, it too will deflect slightly with respect to leg 12. Deflection of the device 20 will cause the indicator arm 24 to be moved into contact with leg 12, as indicated at 3 34 in FIG. 2. The deflection of the leg 14 to the leg 12 is proportional to, and indicative of, the applied torque.

The material used for the wrench is resilient and the resilient characteristics thereof are of such predetermined value that the length of the indicator arm may be chosen so that its free end will contact the leg 12 upon application of the desired predetermined torque and corresponding deflection of leg 14. Upon such contact the torque applied to the handle 14 by the operator is released and the handle and indicator device 20 returns to their normal position as shown in FIG. 1 and the tool removed from the head of the screw 16.

The torque that is indicated can be varied by selecting indicating arms of different lengths, calibrated in accordance with the predetermined torque in terms of footpounds or inch pounds. The slidable mounting of the indicator device 20 thus permits the free end of the indicator arm to be adjacent the point of contact 34, no matter which length arm is chosen. This capacity to interchange indicating arms in order to vary the selected torque is particularly advantageous since no gauge or dial readings need be taken by the operator who must only note the contact of the free end of arm 24 and leg 12 to determine that the preselected torque, determind by his prior choice of the indicator arm according to its length, has been applied.

Alternatively, a single indicator arm 24 may be employed wherein the arm may be calibrated and scribed or legened to indicate a range of preselected tightening torques. In this embodiment, the preselected torque scribed on the arm 24 is positioned adjacent the contact point 23 as by sliding the mounting portion 22 on leg 14 and locking the same at the desired position by means of set screws 32. With this type indicator, the preselected point along the arm intermediate its ends will contact the engaging leg 12 upon application of the predetermined torque. Thus, a single indicator arm may be utilized to indicate varying predetermined torques.

Should the hex key or wrench itself become broken, Worn-out or for any other reason become unusable, the torque indicating device can be removed therefrom and used on another wrench of like size and stock characteristics.

In addition, it is noted that the screw engaging portion 38 of the wrench may be a blade for reception in the slot of a screw or it may be a socket for positioning over the head of a screw. The screw-engaging portion of the tool may, of course, be of still other equivalent configurations.

From the above description and the accompanying drawing, it may thus be seen that an operator using the indicating torque wrench can uniformly apply the same tightening torque in a production operation by applying a tightening torque until the indicating arm 24 contacts the leg 12.

What is claimed is:

1. A torque indicating Wrench assembly comprising:

a generally L-shaped Wrench including a first leg portion integral with and extending at a generally right angle from a second leg portion, said first leg portion being adapted to transmit an applied tightening torque to a fastening element and said second leg portion being adapted to receive an applied tightening torque;

an indicator arm carried by said second leg portion and extending parallel thereto, said indicator arm termimating in a free end adjacent to and spaced from the side of said first leg portion whereby upon the application of a tightening torque said second leg portion and said indicator arm are deflected relative to said first portion and said indicator arm is in contact with said first leg portion, said contact being indicative of the applied tightening torque, said indicator arm movable along said second leg portion to different positions whereby different applied tightening torques may be indicated.

2. A torque indicating wrench assembly according to claim 1 wherein said indicator arm means is calibrated and legended in increments of torque whereby said indicator arm may be adjusted along said second leg portion to indicate a predetermined torque.

3. A torque indicating wrench assembly according to claim 1 wherein said indicator arm is removable from said second leg portion whereby indicator arms of various lengths may be carried on said second leg portion and whereby diflerent applied tightening torques may be indicated.

4. A wrench adapted to be used as a production tool to indicate a predetermined tightening torque for a threaded fastening means comprising:

a wrench including a first portion adapted to engage said threaded fastener and a second portion adapted to receive said tightening torque.

an indicator means mounted on said second portion and including an arm means extending to a position adjacent to and in spaced relation with said first portion,

said wrench having the characteristic that upon application of said preselected tightening torque said second portion deflects with respect to said first portion in direct relation to the torque applied to said fastener whereby said arm contacts said first portion to indicate the application of said predetermined torque,

said indicator means including a mounting portion adjustably and removably mounted on said second portion,

said arm means being calibrated and legended in increments of torque intermediate its ends, said adjustable mounting portion being positionable to associate a selected torque legended on said arm means with said first portion whereby upon application of said predeterminal torque that portion of the arm legended indicating said selected torque is in contact with said first portion.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 6/1939 Germany 87a-66 RICHARD C. QUEISSER, Primary Examiner I. WHALEN, Assistant Examiner US. Cl. X.R. 8152.5

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