US3769861A

US3769861A - Stud wrench

Info

Publication number: US3769861A
Application number: US00250420A
Authority: US
Inventors: A Kisle; G Brase
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-05-04
Filing date: 1972-05-04
Publication date: 1973-11-06
Anticipated expiration: 1990-11-06

Abstract

A wrench for gripping and turning threaded studs to cause their removal from other structure comprises a main body for engaging the stud and a tapered pin extending transversely through the main body and through a jaw maans within the body. With the pin in a fully inserted transverse position, the main body is threaded to the stud until it engages the lower end of the jaw means. A take-up nut having left handed threads is threaded into the upper end of the main body until it bears against the jaw means. The tapered pin and the internal jaw means are movable a small amount axially within the main body so that when the takeup nut is tightened the lower end of the jaw means will bear firmly against the end of the stud, thereby locking the main body to the stud and enabling the turning of the main body to unscrew the stud. Transverse movement of the pin in the main body serves to release the wrench from the stud.

Description

United States Patent Kisle et al. 1 Nov. 6, 1973 STUD WRENCH [76] Inventors: Adolph J. Kisle, 27855 Via Ventana, [57] ABSTRACT 52: ???g ggg g fi z g? kgt g% A wrench for gripping and turning threaded studs to Mountain View Calif 94640 cause then removal from other structure comprises a main body for engaging the stud and a tapered pin ex- [22] Filed: May 4, 1972 tending transversely through the main body and through a jaw maans within the body. With the pin in [21] Appl 250420 a fully inserted transverse position, the main body is threaded to the stud until it engages the lower end of [52] US. Cl. til/53.2, 29/240 the jaw means. A take-up nut having left handed [51] Int. Cl B25b 13/50 threads is threaded into the upper end of the main body [58] Field of Search 81/532; 29/240 until it bears against the jaw means. The tapered pin and the internal jaw means are movable a small amount [56] References Cited axially within the main body so that when the take-up UNlTED STATES PATENTS nut is tightened the lower end of the jaw means will 1 549 041 8/1925 Berg 81/532 bear firmly against the end Ofthe Stud thereby locking 7/1931 Roche," 81/532 the main body to the stud and enabling the turning of 2 33 157 12/1943 Bayes I U 1 532 the main body 120 unscrew the stud. Transverse move- 2,775,153 12/1956 Parhaniemi 81153.2 ment of the p in the m y serves to release the Primary Examiner-James L. Jones, Jr. Att0rney-Roger W. Erickson wrench from the stud.

10 Claims, 7 Drawing Figures STUD WRENCH BACKGROUND OF THE INVENTION This invention relates to an improved wrench for removing threaded studs from structures. When such studsare usedfor holding members together in various structures they are usually installed with considerable torque so as to be tightly secured in place. Consequently, when it later becomes necessary to remove them for replacement or salvage, an equal amount or perhaps even more torque may be required to accomplished the job. In order to apply adequate removal torque it isessential to grip the stud firmly and preferably in a manner that does not damage the stud threads. One general object of the present invention is to provide a wrench that will solve this problem.

Yetanother object of the present invention isto provide a stud wrenchthat is compact, easy to use and economical to manufacture.

Another object of the present invention is to provide a stud wrench that can be easily attached to a stud, that can be tightened with a high torsional force to grip the stud firmly without damaging its threads so as to enable it to be unscrewed from supporting structure.

Another object of the present invention is to provide a wrench that may be quickly and easily released from the stud after the stud has be loosened.

Other objects, advantages and features of our invention will become apparent from the following detailed description of one preferred embodiment taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE INVENTION In broad terms our stud wrench comprises a main body having a bore at its lower end with internal threads for engaging a stud to be removed. At its upper end is another bore with internal left-handed threads for a take-up nut. Situated internally between the upper and lower threaded bores is a smooth bore section for retaining a pair of jaw members. These jaw members have matching tapered recesses that are aligned with aligned transverse openings in the opposite sides of the main body and located at the level of the smooth section. A transverse tapered pin extends through the aligned openings in the sidewalls and the recesses of the jaw members. When the main body of thewrench is initially attached to the stud being removed the tapered pin is pushed transversely so that its larger end portion is between the jaw members and its narrower end extends from the side of the main body. When torque is applied to the takeupnut it engages the upper jaw member which bears against the pin and transmits a downward force against the lowerjaw member and also the end of the stud. A continued application of torque causes the main body threads to grip those of the stud, so that eventually sufficient torque in the same direction will cause the stud to unscrew from its supporting structure. When the stud has been loosened, the pin is moved by the application of force to its small end to the position where its large end will not protrude from the other side of the main body. This affords sufficient clearance to release the grip of the main body on the stud threads, thereby facilitating easyremoval of the wrench.

DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded view in perspective showing a stud wrench embodying the principles of the present invention as it appears just before being attached to a stud to be removed;

FIG. 2 is a view in side elevation and partially in cross section of the stud wrench of FIG. 1 after it has been attached to the stud;

FIG. 3 is a view similarto FIG. v2 showing the wrench with its elements in the stud gripping position;

FIG. 4 is a view in section taken along line 3-3 of FIG. 3;

FIG. 5 is a fragmentary view in section showing the pin after it has been moved to its releasing position;

FIG. 6 is a lower end view of the lower jaw member of our wrench; and

FIG. '7 is a view in perspective of an adapter to enable use of the wrench on various sizes of studs.

Referring to the drawing, FIG. 1 shows a stud wrench 10 embodying the principles of thepresent invention as it appears just prior to being applied to a stud 12 which is threadedly secured in some other structure 14. Usually, when it is necessary to remove such a stud it is because the stud has become broken and corroded or otherwise damaged. Also, it is usually tightly gripped by the surrounding structure so that considerable torque is required to loosen and remove it. The wrench 10 provides a means for firmly gripping the stud so that the necessary torque can be readily applied. If the stud was previously broken it may be desirable to file its exposed end 16 so thatit is essentially flat.

The stud wrench 10 comprises a main body member 18 which preferably has the external shape of a standard hex nut. Although it could be cylindrical, this hex shape or some other suitable flat side configuration is preferred in order for the body member to be readily gripped for turning by a conventional tool. The body 18 is fairly long, being around lrto 2 or more times its diameter, and at its lower end it is provided with an axial bore having internal threads 20 that are right-hand threads of standard design so as to engage the stud that is to be removed. These latter threads extend into the lower end of the body portion for a distance that is somewhat less than one half of its total length and they terminate at the lower end of a cylindrical cavity 22 which is smaller in diameter than the threads 20. Extending downwardly from the upper end of the body member 18 is another axial bore having a series of internal threads 24 that are left-handed. These threads extend downwardly within the body member for a distance that is less than one half of its length and they terminate at the upper end of the cylindrical cavity 22. Engaged with the threads 24 is a take-up nut 26 preferably having astandard hex head portion 28 that is smaller in diameter than the main body member. At its lower end this take-up nut, which is somewhat shorter in length than the upper axial bore, has a convex tip 30 so that its downward thrust can apply a concentrated force near its center axis.

Now, within the cylindrical cavity 22 is a pair of upper and lower

cylindrical jaw members

32 and 34 that serve to transmit axial force from the take-up nut 26 to the end of the stud being removed. The outer diameter of these jaw members is such that they provide anormal sliding fit with the wall ofthe'cylindrical cav ity. The inner end faces 36 and 38 of

thejaw members

32 and 34 are spaced apart to form a gap 40. In each of these end faces is a transverse: tapered recess 42 whose axis is perpendicular to the longitudinal axis of the jaw members. When the jaw members are made, they are first formed or machined as a single unit. Then, a transverse bore hole having a small, constant taper (e.g., an outer surface having an angle of about three degrees with the pin axis) is made through this unit near its axial center. Now, the unit is severed to form the two jaw members by removing (as by sawing) a transverse slice of material in a plane that includes the centerline of the tapered bore hole. The thickness of this slice may be around percent of the mean diameter of the bore hole so that the recess of each jaw member is not a full one half of a tapered bore hole.

The upperjaw member 32 has an upwardly extending portion 46 of a reduced diameter which is engaged by the convex tip 30 of the take-up screw 26. The lower jaw member 34 has a similar downwardly extending portion 48 ofa slightly smaller diameter with a knurled annular surface 50 for engaging the exposed end of a stud being removed.

On opposite sides of the main body portion are a pair of aligned

openings

52 and 54 whose axis is coincident with the axis of the tapered recesses 42 and therefore perpendicular to the longitudinal axis of the main body member. These openings are preferably formed with the same degree of taper as the recesses in the jaw members. Extending within the

aligned opening

52 and 54 and through the jaw recesses 42 is a tapered pin 56 also having the same degree of taper as the recesses and the openings. This pin has a length which is substantially greater than the diameter of the main body member with an enlarged head portion 58 at its larger end and an enlarged cap 60 secured to its smaller end, both head portion and cap being larger in diameter than the

openings

52 and 54. Preferably, this pin is made of a ferrous material so that it can be magnetized. The pin is also movable back and forth within the main body portion and when it is in the position with its head portion against the side of the main body portion the

openings

52 and 54 are substantially larger than the pin portions which they surround, thereby forming a considerable clearance around these portions. Obviously, when the pin is moved to its opposite extreme position with its cap 60 against the side of the main body member, as shown in FIG. 5, even more clearance occurs around the pin at the

openings

52 and 54.

The operation of our wrench 10 in removing studs that are held fast in other structures may be readily explained with reference to FIGS. 1 4. Before the wrench 10 is attached to a stud to be removed, the take-up nut 26 is threaded upwardly so that its lower end does not engage the upper jaw member 32. The tapered pin 56 is moved inwardly until its head portion 58 is fully against the side of the main body portion (FIG. 3). Preferably, the lower jaw member 34 is also made ofa ferrous material so that it will remain in position against the pin 56 byits magnetic force even when the wrench is not in use. Now, the main body portion is threaded onto the stud 12 being removed until the end of the stud engages the knurled end 50 of the lower jaw member and pushes the pin upwardly against the

openings

52 and 54. The take-up nut 26 is now rotated counter-clockwise to move it downwardly within the main body member, thereby causing its convex end 30 to engage the upper portion 46 of the jaw member 32. Continued torque applied to the take-up nut causes this upper jaw member to bear against the pin and the pin in turn to bear against the lower jaw member. This forces the knurled end of the lower jaw member to bear against the end 16 of the stud 12. As more torque is applied, the

jaw members

32 and 34 grip the pin and are forced into the end of the stud causing the main body member to grip the stud firmly. Although there may be some slight axial movement of the stud as the tightening force is applied, this can be accommodated by the clearance around the pin afforded by the enlarged holes in the body member. Such movement enables the internal threads 20 to also produce a gripping action on the stud. When the take-up nut has been tightened sufficiently to secure the wrench to the stud, additional torque can be applied directly to the main body member in the same direction by a tool having a longer lever arm. Under such leverage no stud can remain in its threaded position but will ultimately break use.

After the stud has been loosened the wrench 10 may be quickly and easily released from the stud by applying an axial force to the cap 60 of the pin 56. This will move the pin within the main body member and the recesses of the jaw members, thereby immediately creating an axial clearance that releases the force on the end of the studfNow, the take-up nut can be reversed and screwed outwardly and the main body can be unscrewed from the stud in the opposite direction. I

From the foregoing it should be apparent that the present invention provides a highly effective tool for removing old, corroded or damaged studs from various structures. Not only is our wrench easy to apply to a stud but its quick release feature eliminates any timeconsuming problems of removing the wrench from the stud. Moreover, our wrench has relatively few parts and can be readily made in different sizes to handle large or small studs.

To accommodate various sizes of studs with different threads and diameters within a given range we may use an adapter 62, as shown in FIG. 7. This has a hexagonal shaped head 64 and a tubular barrel portion with external threads 66 that will fit the lower internal threads 20 of the main body member. Internal threads 68 of any given type are provided within the barrel portion to accommodate a particular stud size. Obviously, various sized adapters that are relatively inexpensive can be used with a single wrench to accommodate an equal number of different studs.

To those skilled in the art to which this invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

We claim:

1. A wrench for removing threaded studs from supporting structure comprising: i

a main body having a lower bore extending axially upwardly from its lower end with internal threads for engaging the stud to be removed;

an upper bore with left handed internalthreads extending axially downwardly from its upper end, and a passage interconnecting said upper and lower bores;

a take-up nut threadly engaged in said upper bore;

a pair of movable upper and lower jaw members within said passage having opposed, spaced apart and transverse inner faces and tapered recesses exmain body has flat outside surfaces forming a hexagonal shape.

tending diametrically across said opposed, transverse inner faces;

a pair of openings in opposite sides of said body member having aligned axes that extend through said passage, said axes being substantially perpen- 5 dicular to the central axis of said body member and parallel with the axes of said jaw recesses;

and an axially movable tapered pin extending through said main body openings and through said recesses so that said jaw members will grip said pin when said take-up nut is rotated to bear on said upper jaw member while said lower jaw member bears against the end of the stud to be removed.

2. The wrench as described in claim 1 wherein said 3. The wrench as described in claim 1 wherein said 4. The wrench as described in claim 1 wherein said pin has a slightly conical outer wall that tapers at roughly an angle of 3 with respect to its central axis.

5. The wrench as described in claim 1 wherein said pin is magnetized to have the opposite polarity'as said lower jaw member so as to hold it in place when the wrench is not in use.

6. The wrench as as described in claim 1 wherein said passage is a cylindrical smooth sided bore having a smaller diameter than said upper and lower threaded bores.

7. The wrench as described in claim 1 including an adapter means having a tubular body and a head means at one end thereof, said tubular body having outer threads to match the threads of said lower bore and inner threads adapted to fit smaller studs.

8. The wrench as described in claim 2 wherein said take-up nut has a hexagonal shape that is smaller than said main body.

9. The wrench as described in claim 1 wherein said take-up nut has a convex lower end surface that bears against the upper end of said upper jaw member.

10. The wrench as described in claim 1 wherein said lower jaw member has an annular knurled surface on its lower end adapted to engage the end of a stud to be removed.

Claims

1. A wrench for removing threaded studs from supporting structure comprising: a main body having a lower bore extending axially upwardly from its lower end with internal threads for engaging the stud to be removed; an upper bore with left handed internal threads extending axially downwardly from its upper end, and a passage interconnecting said upper and lower bores; a take-up nut threadly engaged in said upper bore; a pair of movable upper and lower jaw members within said passage having opposed, spaced apart and transverse inner faces and tapered recesses extending diametrically across said opposed, transverse inner faces; a pair of openings in opposite sides of said body member having aligned axes that extend through said passage, said axes being substantially perpendicular to the central axis of said body member and parallel with the axes of said jaw recesses; and an axially movable tapered pin extending through said main body openings and through said recesses so that said jaw members will grip said pin when said take-up nut is rotated to bear on said upper jaw member while said lower jaw member bears against the end of the stud to be removed.

2. The wrench as described in claim 1 wherein said main body has flat outside surfaces forming a hexagonal shape.

3. The wrench as described in claim 1 wherein said openings in said main body have substantially the same degree of taper as said pin.

4. The wrench as described in claim 1 wherein said pin has a slightly conical outEr wall that tapers at roughly an angle of 3* with respect to its central axis.

5. The wrench as described in claim 1 wherein said pin is magnetized to have the opposite polarity as said lower jaw member so as to hold it in place when the wrench is not in use.