CA2080266A1 - Gripping impact wrench socket - Google Patents

Abstract

ABSTRACT OF THE INVENTION
A gripping impact socket wrench comprising a housing symmetrically formed about an axis, a socket for receiving the driver of an impact wrench driving tool at a proximal end of the housing, and a cup portion formed at the distal end of the housing including a plurality of symmetrically positioned cam surfaces formed circumferentially around the interior wall of the housing; a plurality of jaws slidably positioned within the cup portion, each jaw having four substantially flat exterior surfaces, a cam surface mating with one of the cam surfaces at the interior of the housing, and a gripping face evenly scored for defining a generally cylindrical arc surface, thereby defining the shape of the jaw which is generally a solid pie-sector of a cylinder; a unitary generally cylindrically shaped cage member held in the housing cup portion for partial rotation about the axis of the housing and for maintaining the jaws in symmetrically opposed positions circumferentially around the interior of the cup, which unitary cage holds the jaws through substantially flat surface-to-surface sliding engagement with the exterior surfaces of the jaws; a centrally acting ring spring acting with generally uniform tension on each of the jaws to hold the jaws outwardly against the cam surfaces in the interior of the cup.

Description

TEC~NICAL FIELD OF THE INV~NTION
The present invention relates to a gripping impact wrench socket and in particular to a socket assembly driven by an impact wrench with automatic inwardly clamping jaws for gripping studs, threaded collars, couplers, and other cylindrical fasteners and the like for non-destructive removal andior tightening thereof.

BACKGROUND OF THE INVENTION
Previously known impact wrench sockets, of the type for automatically gripping coupling collars, have been substantially complex in construction and subject to breakage and malfunctions. One such complex gripping socket was disclosed in U.S. Patent No. 4,932,292 which required eight internal moving parts including three cam driven jaws, each jaw having an ear or guide pin ~ormed on one surface thereof for circumferential spacing and radial motion guidance through an interface with radial ;
channels formed in a guide bushing. The jaws were biased :.
in an outward direction so that an exterior cam face of the jaw inter~aced with an interior cam face of the housing. The outward bias was pro~ided by coiled compression springs positioned inside the bushing member guide channel, so that each spring pressed outwardly against a separate tab or guide pin formed on each gripping jaw. The spacing between the jaws circumferentially around the wrench was maintained by the spacing of the guide channels in the bushing member such that the guide tabs or pins were subject both to radial tension from the spring and also to rotary impact loading due to inevitable uneven distribution of twisting forces among the jaws. Further, the entire internal working mechanism was held in place using a cover plate which was ' attached using threaded fasteners.

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While it was theorized by others that the number of jaws could be reduced to two from the three previously known, the resulting reduction of the internal parts from eight to six only resulted in a partial savings of manu~acturing costs. Yurther, the reduction o~ the number of shoes was found to result in further uneven distribution of twisting forces and thereby exacerbated the problem of guidance tab breakage. Thus, completely successful use of two jaws prior to applicants' inventive impact gripping socket wrench construction was not successfully accomplished. Moreover, the advantageous construction of applicants' invention can also be applicable to a plurality of gripping jaws with many of the same advantages over the prior known gripping impact wrench sockets, including reduced jaw breakage, reduced manufacturing cost, and increased reliability and durability.

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SUMMARY OF THE INVENTION
Various drawbacks of the prior known gripping socket wrenches have been overcome by the present invention in which the number o~ internal moving parts has been reduced by using a unitary cage, a single ring spring and a plurality of shoes.
Preferably only two shoes are usea. The tubular wrench housing has been constructed for maximum strength at the cam housing and at the anvil. The weight of an extension tube portion which allows elongated threaded studs to be traversed by the gripping jaws for maximum effectiveness has been minimized. The cage and gripping shoe assembly is held in place at the distal end of the cam housing for ease of assembly and disassembly while maintain-ing axial pulling strength.
More specifically, the invention provides improved simplified construction gripping socket wrench for use with an impact tool driver, the socket wrench of the type having a generally cylindrical one piece housing, a driving socket at a proximal end of the housing, internal cam sur~aces symmetrically positioned about an interior of the housing adjacent a distal end of the housing, and symmetrically positioned clamping jaws held within the housing at the distal end, each having an interior gripping face actuated inwardly by relative partial rotation between the symmetrically positioned clamping jaws and the internal cam surfaces, the improved construction comprising: -(a) a unitary cage for holding the clamping jaws symmetrically positioned for opposed radially inward actuation by the internal cam surfaces, th~e unitary cage having a cylindrical body with solid sector openings formed therein for slidably holding the clamping jaws, and spaced apart cylindrical sector interior surfaces interposed between the sector openings, each interior sector sur~ace having a spring groove formed to a predetermined depth thereinto, centrally located and circum~erentially aligned with each other spring yroove in each other interior sector surface of the cage; ~b) an arc shaped groove formed centrally located in the gripping face of each of the clamping jaws which arc snaped groove is undercut a predetermined depth corresponding in location and depth to the central location and the predetermined depth of the spring ~roo~e formed in ~he cylindrical sector interior surfaces of the unitary cage: and ~c) a ring spring having a thiekness less than the predetermined depth of ~he spring groove and the arc shapea grooves in the interior cage sur~ace and the gripping faces o~ the clamping jaws and having a diameter sufficient to put tension on the jaws outwardly against the symmetrically positioned cam surfaees.
The invention also provides a gripping impaet. soeket wrench of the t~pe with a hammer-receiving anvil for use with an impact wrench driving tool of the type having a driving hammer thereon, the impact socket wrench comprising: (a) a housing symmetrically formed about an axis, with a socket defining an anvil for receiving the hammer of the impact wrench driving tool at a proximal end of the housing, and a cup portion having an interior opening and an interior wall formed at a distal end of the housing including a plurality of symmetrically positioned internal cam surfaces formed circumferentially around the interior wall of the cup portion; (b) a plurality of jaws slidably positioned within the cup portion, each jaw formed ., , .:

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generally in the shape of a solid sector o~ a cylinder having two substantially flat parallel end eXterior SUr~aCeS and two substantially flat an~led side exterior surfaces, an outer cam surface mating with one of the internal cam surfaces at the interior of the cup portion of the housing, and an inner gripping ~ace evenly scored for defining a generally cylindrical arc sur~ace, 'hereby defining a shape of the ~aw which is generally a solid sector of a cylinder; (c) a unitar~ generally cylindrically shaped cage member held in the housing cup portion for partial rotation about a central axis of the housing and for maintaining the jaws in symmetrically opposed positions circum- -ferentially around the interior opening of the cup, which unitary cage holds the jaws through substantially flat surface-to-surface sliding engagement with the side and end exterior flat surfaces of the jaws; and ~d) a centrally acting ring spring acting with generally uniform tension on each of the jaws to bias the jaws ~ -outwardly against the internal cam surfaces on the interior walls of the cup portion. `
A further preferred feature of the gripping impact socket wrench is the addition of a retaining pin to the combina-tion socket wrench disclosed, which pin extends diametricall~
through the anvil receiving end. The pin is inserted through a corresponding orifice in the anvil and through the hammer of the impact driver to hold the socket wrench in place on the impact driver. The pin is retained using a resilient ring member positioned in a groove correspondingly covering both ends ~f the orifice formed for the pin. This socket retention mechanism in cooperation with the gripping mechanism which maintains its grip through frictional cam tension on the rod or coupler being removed allows the entire assembly to be safel~ withdrawn without releasing the coupler before desired by the operator. The cage is constructed with a flat angled stop surface which upon driving the wrench in reverse pushes the gripping shoes outwardly thereby releasing the frictional grasp on the stud or coupler being removed.

BRIEF DESCRIPTION OF TH~ DRAWINGS

These and other a~vantages and objects of the present invention will be more fully understood with reference to the detailed description below and the drawings in which like numerals represent like elements and in which:
Figure 1 is an exploded perspective view of the inventive impact socket wrench assembly; `

Figure 2 is a schematic cross-sectional view showing the operation oE the gripping impact wrench in a non-gripping position; and `
Figure 3 is a schematic cross-sectional view of the inventive wrench showing the operation of the various features of the wrench while in its gripping position.

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DETAILED DESCRIPTION OF T~IE PREFERRED EMBODIMENTS
Figure 1 shows an exploded perspective view of the inventive socket assembly 10 which comprises a cylindrical housing 12 having an anvil 14 at its proximal end. In this disclosure a terminology convention will be adopted in which the direction toward the impact driving tool will be termed "proximal" and the direction away from the impact driving tool will be termed "distal".
Extending from the anvil 14 there is an extension member 16 which is preferably genèrally cylindrical for convenience of operation and holding of the tool. A
connector pin 18 is advantageously inserted diametrically through a pin hole 20 to engage the hammer of the driving tool to avoid axial detachment of the wrench from the driving tool. The connector pin 18 is advantageously retained with a resilient retaining ring 22 which expandably slides over the exterior of anvil 14 and down into a circular groove adjacent both ends of the pin hole 20. The anvil 14 will be formed in the proxlmal end 25 of the wrench and, at the distal end 28, a cup housing portion 30 will be formed having a distal lip 32 thereby defining the opening of a hollow cavity therein.
Adjacent at the proximal end o~ cup 30 is a proximal slide surface 34 which may be generally disc shaped for ;~
sliding support of a unitary cage 54 as will be described ~`
more fully below. Adjacent to the slide surface 34, a `
cage support rim 36 is advantageously formed which is generally cylindrical in the preferred embodiment and which corresponds in diameter to the proximal end of cage 54. Adjacent lip 32 is a distal cage cylindrical support ~
surface 38 which is sized for sliding engagement with the ;
distal end of unitary cage 54 as will be described more fully below.
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Within cup portion 30, there is a first internal cam surface 40 and a second internal cam surface 42. The internal cam sur~aces are pre~erably integrally ~ormed within cup portion 30 of the cylindrical housing 12.
While two internal cam surfaces are shown diametrically opposed in the preferred embodiment of figure 1, some of the advantages of the inventive wrench construction according to the present invention can also be obtained with a plurality of cam surfaces formed symmetrically tO about the tool axis 11 and evenly spaced circumferentially around the interior of cup 30.
Each o~ the cam surfaces forms the same cross- .
sectional shape with a progressively decreaslng radius from a first cam maximum radius 46 to a first cam minimum radium 48. Similarly, the second cam radius decreases progressively from the maximum second cam radius 50 to the minimum second cam radius 52. In the preferred embodiment shown, in which two internal cam surfaces are provided, the maximum first cam radius 46 is ..
~0 substantially immediately adjacent the second cam minimum radius 52.
A unitary cage 54 is provided in the assembly. :
Unitary cage 54 preferably has a distal cage end 56 which in the preferred embodiment comprises a cylindrical rim formed generally disc shaped adjacent end 56, with a cylindrically shaped first bearing surface 58 formed around the periphery thereof. The bearing surface 58 is sized for partial rotary sliding engagement with internal cylindrical cage support surface 38 of cup 30.
The proximal cage end 60 preferably includes a second cylindrical bearing surface 62 which is formed around the periphery of a disc-shaped proximal end surface 61. Upon assembly the cage 54 is inserted into the cup 30 such that the disc-shaped proximal end 61 is . .

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in sliding engagement with disc--shaped slide surface 34 of the cup housing 30 and each of the cylindrical bearing surfaces 58 and 62 will be in s;Liding angagement with corresponding cage support surfaces 36 and 38 respectively.
In the preferred embodiment both the cylindrical housing 12 and the cage 54 will be constructed of durable surface hardened steel so that sliding engagement between the two surfaces is achieved with minimum wear.
While the interior material provides durable non-brittle strengthr the unitary cage 54 has a plurality of openings including a ~irst opening 64 and a second opening 66 with each opening in the shape of a solid -~
sector of a cyllnder for holding gripping j aws 74 and 76 15 in the preferred embodlment as shown . It being understood that additional solid cylindrical shaped sector openings may be constructed for corresponding additional cam surfaces and gripping jaws. However, it has been found that the present inventive construction advantageously permits a two jaw construction. The two jaw construction allows the jaws 74 and 76 to be diametrically opposed thereby maximizing gripping power.
Further, it has been found that a unitary cage provides a maximum cage strength when constructed for two jaws which thereby reduces cracking and breakage of the cage assembly during the impact operation. The cage 54 advantageously supports the jaws 74 and 76 for axial and radial alignment during operation. The cylindrical cage body 68 is of a diameter less than the minimum diameter of the cam suxfaces so that the gripping jaws are held within open sectors 64 and 66 and extend therethrough.
Thus the gripping jaws 74 and 76 can be actuated through a full range of radial movement corresponding to the cam slope. A further advantage of a two jaw construction is that a more shallow cam slope produces great clamping force. Thus the twisting power of the impact wrench is multiplied through the shallow slope cam surfaces to provide maximum gripping. For a given cam slope the amount of radial movement is increased with the circumference covered by the cam such that two cams provide more radial travel than three.
The cage includes a hollow cage opening 70 through - which a work piece, such as a stud, a rod, or a coupler can be inserted. The hollow cage opening 70 is preferably sized to correspond to a hollow opening 72 in the extension tubing 16. This allows threaded studs and similar work pieces having external threads to be inserted into the extension so that the gripping jaws can clamp onto a solid exterior surface of a rod and avoid any potential thread damage. Also it has been found that for studs threaded into a surface, it is preferable to grip the studs immediately adjacent the surface to reduce the chance of stud twisting or fracture and to maintain axial stability while the tool is being operated.
The cage movably holds a first gripping shoe 74 and a second gripping shoe 76, each shoe generally having a cylindrical gripping surface which is formed with a scored matrix for non-slipping grip of the work piece, stud or coupler. Each shoe 74 and 76 also has an external cam surface correspondingly shaped to interface along the entire internal cam surface of the cup 30. For convenience and clarity the structure of each gripping shoe will be described in connection with a single gripping shoe it being understood that the same structure is intended for each of a plurality of shoes. Each external cam surface 80 has a leading edge 82 and a trailing edge 84. The radial shoe thickness decreases progressively from the leading edge 82 to the trailing . . .: :: .-: .:: .: . . : :

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edge 84. There is a generally flat angled push surface 86 which when assembled forms a radial plane substantially aligned with the axis o~ the tool. There is a corresponding cage pushing surface 88, which operates against gripping shoe surface 86 as will be more fully explained with reference to figures 2 and 3 below.
Each open pie-sector of the cage also has a radial proximal radial slide surface 90 and a distal radial slide surface 92 which are spaced apart in the cage corresponding to the distance between a proximal shoe end 94 and a distal shoe end 96. The two shoe ends 94 and 96 and the two cage radial slide surfaces 90 and 92 define sectors of a plane perpendicular to the axis of the tool.
The cylindrical gripping surface 78 projects adjacent to the internal cage opening 98 for access to the stud or coupler rod to be gripped. An outwardly biased ring spring lO0 is provided to push outwardly to hold the shoes radially outwardly such that the cylindrical gripping surface is projecting only slightly into the hollow cylindrical opening 70 of the cage 54. In this manner any stud, rod, coupler or the like which can be -inserted through the opening of the cage will also push past the gripping jaws in the outwardly biased non-torquing position. It has been found advantageous to use a single ring spring lO0 pushing centrally against both of the shoes simultaneously. Thus a central shoe spring groove is formed in each cylindrical gripping surface which groove is in the shape of an arc parallel to the proximal and distal shoe ends and substantially halfway therebetween. Thus the outward tension of the spring acts evenly against the entire shoe and does not tend to tilt it or twist it as springs on one side or the other of the shoe~ would tend to do. Also, the single spring has advantages over having springs at both ends of each ., shoe as the tension in one spring may be different or may be lost during operation such that uneven radially outward pressure is placed on the shoes thereby causing them to tilt. Tilting gripping shoes may lead to malfunctions and breakage during operation. The cage construction includes a cage spring groove 104 such that the spring loo is below the sur~ace exterior to the hollow cage opening 7 0 and does not inter~ere with insertion of a work piece.
Thus during clamping operation the cage pushing surface 88 acts upon the entire push surface 86 of the gripping shoes evenly forcing the entire shoe cam surface 80 to slide along the interior cam surface 40 or 42 o~
the housing. The sloped progressive decrease in diameter o~ the cam surfaces force the jaws inwardly thereby clamping against the work piece. The construction is symmetrical such that the jaws 74 and 76 will clamp substantially evenly with even force against the work piece. The cage 54 has a stop surface 106 which acts together with pushing surface 88 to prevent the shoe from extending inwardly too far. This prevents the gripping jaw cam surface from moving beyond the trailing edge 48 or 52 of the cup housing cam surfaces in a manner which might cause denting or excessive wear in the cam surface thereby maintaining the durability and smooth operation -of the tool for multiple uses. As indicated previously, the range of sizes is maximized through the unique ability of the unitary cage construction to permit two shoe impact wrench to be constructed. However, when the maximum size range is exceeded alternate size wrenches can be constrllcted.
The cage 5~ is advantageously held axially within cup 30 with a circular clip 108 inserted or "snapped"
into an annular groove 110. This assembly replaces . : .; , .- : " , , : . , ~ . . .: .

. , :: : : ~ ~ , --previously known cover plates thereby reducing construction cost, reducing material weight and avoiding bulky and aw~ward end construction.
With reference to figures 2 and 3, the operation of the inventive wrench can be better understood in which figure 2 is a schematic section view showing the impact socket wrench in a non gripping position. It can be seen that spring 100 holds the shoes outwardly against the maximum radius of the external cam surfaces, preferably this maximum radially outward extension corresponds to the cylindrical gripping surfaces forming an opening equivalent to the hollow cage opening 70.
With reference to figure 3 which is a schematic section view showing the shoes and cup moved into a gripping position it can be seen that partial rotation of the tool as indicated by arrow 112 moves pushing surface 88 of the cage 54 against the pushed surface 86 of the shoes. This rotates the shoes in a direction 114 relatively opposite from the direction of rotation of the wrench 108. The radially inward motion of the gripping jaws, schematically depicted as arrow 114, provides substantial clamping force due to the multiplied force ramping effect of the shallow cam slope or angle. `~
The shallow angle and the scored gripping ;
cylindrical sur~ace of the shoes act together with standard compressibility, yielding, and elasticity of the metal material of studs and couplers to thereby maintain the shoes clamped inwardly against the work piece even ;
after the torquing of the impact driver tool in the direction of arrow 112 is released. This allows the wrench to be pulled back thereby maintaining a grip on the work piece so that it does not inadvertently drop out of the end of the wrench. The wrench as described previously is held in place with a retaining pin 182 and ::~

the cage and jaws are held in place with clip 108 so that the entire assembly can be used in any position without fear of dropping the work piece or the wrench into hard to reach places or into areas where damage may occur.
Release o~ the tool against the work piece is easily accomplished through counter rotating the tool such that the stop surface 106 of the cage pushes against the trailing ~dge 84 of the shoe thereby moving the cam surfaces into a non clamping position. The tension from ring spring lO0 quickly and uniformly disengages the socket from the work piece.
While the invention has been described in connection with preferred embodiments, it is not intended to be limited to the preferred embodiments disclosed but to the contrary is intended to cover such alternatives and equivalent embodiments which fall within the scope of the following claims.

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Claims (6)

1. Improved simplified construction gripping socket wrench for use with an impact tool driver, the socket wrench of the type having a generally cylindrical one piece housing, a driving socket at a proximal end of the housing, internal cam surfaces symmetrically positioned about an interior of the housing adjacent a distal end of the housing, and symmetrically positioned clamping jaws held within the housing at the distal end, each having in interior gripping face actuated inwardly by relative partial rotation between the symmetrically positioned clamping jaws and the internal cam surfaces, the improved construction comprising:
(a) a unitary cage for holding the clamping jaws symmetrically positioned for opposed radially inward actuation by the internal cam surfaces, the unitary cage having a cylindrical body with solid sector openings formed therein for slidably holding the clamping jaws, and spaced apart cylindrical sector interior surfaces interposed between the sector openings, each interior sector surface having a spring groove formed to a predetermined depth thereinto, centrally located and circumferentially aligned with each other spring groove in each other interior sector surface of the cage;
(b) an arc shaped groove formed centrally located in the gripping face of each of the clamping jaws which arc shaped groove is undercut a predetermined depth corresponding in location and depth to the central location and the predetermined depth of the spring groove formed in the cylindrical sector interior surfaces of the unitary cage; and (c) a ring spring having a thickness less than the predetermined depth of the spring groove and the arc shaped grooves in the interior cage surface and the gripping faces of the clamping jaws and having a diameter sufficient to put tension on the jaws outwardly against the symmetrically positioned cam surfaces.

2. A gripping impact socket wrench of the type with a hammer-receiving anvil for use with an impact wrench driving tool of the type having a driving hammer thereon, the impact socket wrench comprising:
(a) a housing symmetrically formed about an axis, with a socket defining an anvil for receiving the hammer of the impact wrench driving tool at a proximal end of the housing, and a cup portion having an interior opening and an interior wall formed at a distal end of the housing including a plurality of symmetrically positioned internal cam surfaces formed circumferentially around the interior wall of the cup portion;
(b) a plurality of jaws slidably positioned within the cup portion, each jaw formed generally in the shape of a solid sector of a cylinder having two substantially flat parallel end exterior surfaces and two substantially flat angled side exterior surfaces, an outer cam surface mating with one of the internal cam surfaces at the interior of the cup portion of the housing and an inner gripping face evenly scored for defining a generally cylindrical arc surface, thereby defining a shape of the jaw which is generally a solid sector of a cylinder;
(c) a unitary generally cylindrically shaped cage member held in the housing cup portion for partial rotation about a central axis of the housing and for maintaining the jaws in symmetrically opposed positions circumferentially around the interior opening of the cup, which unitary cage holds the jaws through substantially flat surface-to-surface sliding engagement with the side and end exterior flat surfaces of the jaws; and (d) a centrally acting ring spring acting with generally uniform tension on each of the jaws to bias the jaws outwardly against the internal cam surfaces on the interior walls of the cup portion.

3. The gripping impact socket wrench of claim 2 wherein:
(a) the unitary cage defines an interior cylindrical surface and a groove centrally located around the interior cylindrical surface for receiving the ring spring such that the ring spring is expanded exterior to the interior cylindrical surface of the unitary cage; and (b) wherein each jaw has an arc shaped groove formed in the gripping surface thereof corresponding in location to the spring receiving groove of the cage such that the gripping cylindrical surface of each jaw is substantially even with the interior cylindrical surface of the cage.

4. The gripping impact socket wrench of claim 2 wherein the plurality of jaws slidably positioned within the cup portion consists of two jaws held diametrically opposed by the unitary cage and with outer cam surfaces corresponding in shape to the internal cam surfaces formed on the interior wall of the housing.

5. A gripping impact socket wrench as in claim 2 wherein the unitary cage member has a first cylindrical bearing surface at a proximal end and a second cylindrical bearing surface at a distal end axially spaced from the first bearing surface and a corresponding interior distal end-cylindrical surface and a corresponding proximal end cylindrical surface in the cup portion of the housing so that the cage is supported for partial rotational sliding with respect to the housing while maintaining axial alignment through the leverage of the spaced apart cylindrical bearing and support interface surfaces.

6. A gripping impact socket wrench as in claim 2 further comprising in combination a retaining pin and receiving hole diametrically through the hammer-receiving anvil of the wrench and a resilient retaining ring positioned in an exterior annular groove so that both ends of the retaining pin hole are covered thereby holding the pin in place so that the wrench can be held from becoming disengaged from an impact driving tool.