Bolt anchor and method for making same

Claim 2

An expansion anchor assembly for a mine roof comprising: a. a bolt including a threaded portion; b. a camming plug Threaded on said bolt; c. a plurality of formed metal fingers disposed about said camming plug; d. said fingers each having a series of coined outwardly disposed teeth thereon with the height of the teeth increasing proceeding along said fingers away from said camming plug, certain of said teeth each having a recess in the obverse face thereof; e. said fingers each having a planar bearing surface engageable with said expansion plug, said recesses being in said bearing surface; f. an extension of a line tangent to said teeth intersecting the plane of said bearing surface at a small acute angle; and g. one tooth having a wall thickness, along at least one radial line, which is greater than the wall thickness, along a corresponding radial line, of a tooth further from said collar position than said one tooth.

Claim 3

An expansion anchor assembly as defined in claim 1 wherein said teeth include a plurality of planar facets defining sides thereof, and crests of said teeth defined by intersections of facets of said tooth sides, said crests extending generally transversely of said fingers.

Claim 4

An expansion anchor assembly as defined in claim 2 wherein said crests are defined by three planar facets forming one side of said teeth and three corresponding planar facets forming said other side of said teeth, the intersections of said facets defining crests comprised of three straight line segments approximately a segment of a circle.

Claim 5

An expansion anchor assembly as defined in claim 1 and wherein said fingers are formed continuously with a sheet metal body and project cantilever fashion from said body toward said expansion plug, said fingers further including a relatively unworked flexible stem portion extending between teeth and said body.

Claim 6

An expansion anchor assembly as defined in claim 4 wherein said body is bent intermediate ends thereof so that said fingers and said body define a generally polygonal tubular expansion shell having one leaf on each side of said polygon.

Claim 7

An expansion anchor assembly as defined in claim 5 wherein said ends of said body are disposed adjacent each other to define an end gap in said body.

Claim 8

An expansion anchor comprising: a. a plug forming a camming member; b. an expansion shell having a plurality of fingers; c. each finger having a toothed portion with a camming surface in engagement with the member and teeth projecting from the obverse surface thereof; d. each toothed portion having a plurality of recesses formed in its camming surface with each recess being defined by inner surfaces of a tooth; e. each camming surface including an elongated, longitudinally straight, strip extending uninterruptedly, longitudinally of its toothed portion near a side of, and past both ends of, one tooth whereby to prevent longitudinal collapse of the one tooth upon application of anchoring pressure; f. each camming surface also including a straight transverse strip extending transversely of its finger near an end of, and past both sides of, a certain tooth whereby to prevent transverse collapse of said certain tooth upon the application of anchoring pressure; g. each finger having a base; h. a selected tooth having a wall thickness as measured along a radial line greater than the wall thickness of other teeth on the same finger as measured along corresponding radial lines; i. said selected tooth being closer to the base of its finger than said other teeth; and, j. said shell including means joining the fingers together near the bases thereof.

Claim 9

An expansion anchor comprising: a. a plug forming a camming member; b. an expansion shell having a plurality of fingers; c. each finger having a toothed portion with a camming surface in engagement with the member and teeth projecting from the obverse surface thereof; d. each toothed portion having a plurality of recesses formed in its camming surface with each recess being defined by inner surfaces of a tooth; e. each camming surface including an elongated, longitudinally straight, strip extending uninterruptedly, longitudinally of its toothed portion near a side of, and past both ends of, one tooth whereby to prevent longitudinal collapse of the one tooth upon application of anchoring pressure; f. each camming surface also including a straight transverse strip extending transversely of its finger near an end of, and past both sides of, a certain tooth whereby to prevent transverse collapse of said certain tooth upon the application of anchoring pressure; g. each finger having a base; h. a selected tooth having a wall thickness as measured along a radial line greater than the wall thickness of other teeth on the same finger as measured along corresponding radial lines; i. said selected tooth being closer to the base of its finger than said other teeth; and, j. said shell including means joining the fingers together near the bases thereof.

Claim 10

An expansion shell as defined in claim 7 wherein said fingers further include stem portions between said collar and said teeth, said stem portions having a sectional thickness which is substantially the same as that of said collar.

Claim 11

The expansion shell of claim 7 wherein the teeth are each comprised of a series of upper and lower planar facets, the upper facets being of greater surface area than the lower facets anD being at a lesser angle with respect to the longitudinal extent of said structure than said lower facets, thereby to permit said teeth to grip varying types of strata in functional different manner.

Claim 12

The anchor of claim 7 wherein said joining means comprises a soft metal collar of square configuration in a plane transverse to said shell, said collar having spaced ends at one corner of the square.

Claim 13

The anchor of claim 7 wherein said plug has a plurality of planar camming surfaces and the camming surfaces of said fingers are complemental to the plug camming surfaces.

Claim 14

The anchor of claim 7 wherein each said longitudinal strip extends substantially the entire length of its toothed portion.

Claim 15

The anchor of claim 11 wherein each finger has two such longitudinal strips.

Claim 16

An expansion anchor assembly for a mine roof comprising: a. a bolt having a head and a spaced threaded portion; b. a camming plug threaded on the bolt and including a plurality of flat camming surfaces tapering toward said head; c. a sheet metal expansion shell having a collar around the bolt between the plug and the bolt head; d. said shell having a plurality of fingers each extending longitudinally from the collar away from the bolt head; e. each finger having a toothed portion connected to the collar by a stem; f. each toothed portion having a plurality of hardened teeth extending from an outer surface and an inner surface extending from an outer surface and an inner surface including a camming section complemental to, and in surface engagement with, one of said plug camming surfaces; g. certain of said teeth having surfaces defining: i. as part of its toothed portion inner surface, a recess disposed outwardly of the plane of the camming section of its toothed portion; ii. and as part of its toothed portion outer surface, a tooth crest; and, h. each of said certain teeth having a wall thickness greater than the thickness of the metal surrounding the tooth when measured along a radial line intersecting a tooth crest. 15 The assembly of claim 14 wherein said wall thickness of each of said certain teeth as measured along such radial line through its crest is greater than the radial wall thickness of said stems.

Claim 17

An expansion anchor assembly for a mine roof comprising: a. a bolt including a threaded portion; b. a camming plug threaded on said bolt; c. a plurality of formed, metal fingers disposed about said camming plug; d. said fingers each having a series of coined, outwardly disposed teeth thereon with the height of the teeth increasing proceeding along said fingers away from said camming plug; e. said fingers each having a planar bearing surface engageable with said camming plug, an extension of a line tangent to said teeth intersecting the plane of said bearing surface at a small acute angle; f. bail means for supporting the fingers relative to said expansion plug in the end of the bolt, said bail means including a wirelike member having a middle section extending across and into the bolt and in engagement therewith; g. the wirelike member including leg portions extending from said middle section generally parallel to the bolt and past the plug with each leg portion being disposed between an adjacent pair of fingers; h. said bail means further including bent end portions on the remote ends of said leg portions overlying and engaging shoulders formed on said adjacent fingers; and, i. said bail means maintaining said assembly in an assembled condition and being disposed within a contour generated by the expansion shell whereby entire assembly may be inserted in the bore hole and setting of the anchor in a bore hole can be effected without detrimental interference by the bail. 17 An expansion anchor assembly comprising: a. a bolt; b. a camming plug threaded on the bolt; c. an expansion shell comprising a collar portion around the bolt and a plurality of spaced fingers extending longitudinally from the collar generally paralleling the bolt; d. said fingers having end portions in engagement with exterior surfaces of said plug and being adapted to be expanded into locking engagement with a surrounding bore hole on advance of the plug relative to the shell toward said collar; e. a bail retaining said assembly in an assembled condition, said bail comprising; i. a bridge portion spanning an end of the plug and engaging the plug to maintain it in contact with said expansion shell; ii. leg portions extending from the bridge portion toward the collar and disposed in spaces between adjacent fingers of the plugs; iii. said bail including end portions at the ends of the legs remote from the spanning portion and projecting into spaces between adjacent fingers, said bent end portion engaging shoulders on said fingers whereby to maintain said assembly in an assembled condition; and f. said bail being disposed within a generally-cylindrical contour generated by said expansion shell, whereby to maintain said assembly in an assembled condition as it is inserted in a bore hole without interference with such insertion.

Claim 18

An expansion anchor assembly for a mine roof comprising: a. a bolt including a threaded portion; b. a camming plug threaded on said bolt; c. a plurality of formed, metal fingers disposed about said camming plug; d. said fingers each having a series of coined, outwardly disposed teeth thereon with the height of the teeth increasing proceeding along said fingers away from said camming plug; e. said fingers each having a planar bearing surface engageable with said camming plug, an extension of a line tangent to said teeth intersecting the plane of said bearing surface at a small acute angle; f. bail means for supporting the fingers relative to said expansion plug in the end of the bolt, said bail means including a wirelike member having a middle section extending across and into the bolt and in engagement therewith; g. the wirelike member including leg portions extending from said middle section generally parallel to the bolt and past the plug with each leg portion being disposed between an adjacent pair of fingers; h. said bail means further including bent end portions on the remote ends of said leg portions overlying and engaging shoulders formed on said adjacent fingers; and, i. said bail means maintaining said assembly in an assembled condition and being disposed within a contour generated by the expansion shell whereby entire assembly may be inserted in the bore hole and setting of the anchor in a bore hole can be effected without detrimental interference by the bail. 17 An expansion anchor assembly comprising: a. a bolt; b. a camming plug threaded on the bolt; c. an expansion shell comprising a collar portion around the bolt and a plurality of spaced fingers extending longitudinally from the collar generally paralleling the bolt; d. said fingers having end portions in engagement with exterior surfaces of said plug and being adapted to be expanded into locking engagement with a surrounding bore hole on advance of the plug relative to the shell toward said collar; e. a bail retaining said assembly in an assembled condition, said bail comprising; i. a bridge portion spanning an end of the plug and engaging the plug to maintain it in contact with said expansion shell; ii. leg portions extending from the bridge portion toward the collar and disposed in spaces between adjacent fingers of the plugs; iii. said bail including end portions at the ends of the legs remote from the spanning portion and projecting into spaces between adjacent fingers, said bent end portion engaging shoulders on said fingers whereby to maintain said assembly in an assembled condition; and f. said bail being disposed within a generally-cylindrical contour generated by said expansion shell, whereby to maintain said assembly in an assembled condition as it is inserted in a bore hole without interference with such insertion.

Claim 19

An expansion shell blank comprising; a. a soft sheet metal collar having a base; b. a plurality of sheet metal fingers extending longitudinally from said collar in a direction away from the base; c. each of said fingers including a toothed portion having a plurality of formed teeth projecting from one face thereof, and a planar camming surface on the obverse face of said fingers, said camming surface having recesses therein each aligned with a projecting tooth, said teeth increasing in height relative to said planar surface proceeding toward said collar; and d. one tooth having a wall thickness, along at least one radial line, which is greater than the wall thickness, along a corresponding radial line, of a tooth further from said collar portion than said one tooth.

Claim 20

An expansion shell blank comprising; a. a soft sheet metal collar having a base; b. a plurality of sheet metal fingers extending longitudinally from said collar in a direction away from the base; c. each of said fingers including a toothed portion having a plurality of formed teeth projecting from one face thereof, and a planar camming surface on the obverse face of said fingers, said camming surface having recesses therein each aligned with a projecting tooth, said teeth increasing in height relative to said planar surface proceeding toward said collar; and d. one tooth having a wall thickness, along at least one radial line, which is greater than the wall thickness, along a corresponding radial line, of a tooth further from said collar portion than said one tooth.

Claim 21

A blank as defined in claim 18 wherein said fingers further include a relatively soft deflectable stem portion between said toothed portion and said collar.

Claim 22

A blank as defined in claim 19 wherein said fingers are bent at the juncture of said stem portion and said toothed portion with said camming surface extending at a slight angle with respect to the plane of said stem portion.

Claim 23

A blank as defined in claim 20 wherein a line tangent to crests of said teeth is substantially parallel to said plane of said stem portion.

Claim 24

A blank as defined in claim 21 wherein said teeth are formed by a plurality of planar facets arranged to provide tooth crests extending generally transversely across said fingers.

Claim 25

A blank as defined in claim 22 wherein said crests are defined by a plurality of straight line segments formed at intersections of said facets, and which line segments approximate a segment of a circle.

Claim 26

A blank as defined in claim 22 wherein said teeth have walls with a sectional thickness which increases proceeding longitudinally toward said crests.

Claim 27

A blank as defined in claim 19 wherein the sectional thickness of said toothed portion is less than the sectional thickness of said stem portion except in the vicinity of crests of said teeth.

Claim 30

A method as defined in claim 1 wherein said step of deforming and flowing said material includes the step of forming a plurality of planar facets defining tooth crests which extend generally transversely of said fingers.

Claim 31

A method as defined in claim 1 and further including the step of deforming said fingers tranversely of their length between the collar portion and said teeth so that a line tangent to crests of the teeth is substantially parallel to the plane of said collar portion.

Claim 32

A method as defined in claim 1 and further including the steps of shearing said collar portion to produce ends on said collar portion, and bending said collar portion intermediate said ends to define a generally tubular, polygonal expansion shell.

Claim 33

A method as defined in claim 1 wherein said step of deforming and flowing said material includes the step of directing said flow of said material toward crests of said teeth whereby the sectional thickness of the crests of said teeth is greater than the sectional thickness of said strip.

Claim 34

The method of claim 1 wherein the working of the fingers is cold working.

Claim 37

the process of claim 32 wherein the working of the finger portions is continued until all parallel surfaces thereof are spaced a distance less than their original spacing and all other surfaces are nonparallel.

Claim 38

The process of forming a finger for an expansion anchor comprising: a. forming a tooth blank including a stem portion from sheet metal; b. working said blank to form a plurality of teeth therein; and c. said working step including deforming and flowing the material to form the teeth having an increasing height relative to the plane of said sheet of material proceeding toward said stem portion the flowing of the material being continued until one tooth has a wall thickness along at least one radial line which is greater than the wall thickness along corresponding radial lines of a tooth further from said stem portion than said one tooth and greater than the thickness of said tooth blank prior to said working step.

Claim 39

The process of forming a finger for an expansion anchor comprising: a. forming a tooth blank including a stem portion from sheet metal; b. working said blank to form a plurality of teeth therein; and c. said working step including deforming and flowing the material to form the teeth having an increasing height relative to the plane of said sheet of material proceeding toward said stem portion the flowing of the material being continued until one tooth has a wall thickness along at least one radial line which is greater than the wall thickness along corresponding radial lines of a tooth further from said stem portion than said one tooth and greater than the thickness of said tooth blank prior to said working step.