US2825258A - Mine roof bolt having wedge sections mounted on a t-headed shank - Google Patents

Description

March 1953 c. P. MOCABE ETAL 2,825,258

MINE ROOF BOLT HAVING WEDGE SECTIONS MOUNTED ON A T-HEADED SHANK Filed July 23, 1954 2 Sheets-Sheet 1 V I a 61! n /A 4.6

I I ll 4 Arro /m5) c. P. MOCABE ET AL 2,825,258 BOLT HAVING WEDGE s nous MOUNTED March 4, 1958 MINE ROOF Filed July 23. 1954 ON A T-HEADED SHANK 2 Sheets-Sheet 2 United States Patent MINE, ROOF BOLT T HAVING; WEDGE: .ESECTIONS MOUNTED ONAuTHEADED SHANK':

Charles P. McCabe, Bay Village, and OdinWerther, East Cleveland, Ohio, assignors to Republic Steel Corporation, Cleveland, Ohio, a corporation of-Ne'w Jersey Application .July 23, 1954,.= Serial-No.. 445,262 7 3 Claims. (Cl; 85*2.4) t

Thisinvention relates to the construction of wedge head bolts, and particularly to bolts of a typeadapted for use asmine roof bolts.v v

There is disclosed in ;the copending application of Charles P. McCabe, Serial No. 358,'4l4, file'd.'iMay 29, 1953, now Patent No. 2,787,931, issued'April 9;"1957;

mains behind, and then cooperates with'th'e wedging surfaces on the wedge head to anchor the bolt firmly in the hole.

Bolt heads are commonly formed integrally with the shank of the bolt by a forging operation on the end of the piece of bar stock from which the bolt is made. The bolt head is formed during the forging operation by a flow of bar stock material. This type of forging operation to form a bolt head has limitations as. to the size of the head which can be successfully formed on bar stock of a given diameter.

A wedge head bolt of the type described in the McCabe application mentioned above requires a large amount of material. For that reason, it has been found that such a bolt head is difficult to make as a single forging.

An object of the present invention is to provide an improved wedge head bolt structure of the type described.

A further object of the invention is to provide an improved method of constructing such a wedge head bolt by making it in separate parts and assembling them.

Another object is to provide an improved bolt of the type described capable of withstanding substantial stresses between the bolt head and the shank.

Another object is to provide a method of forming a bolt head of the type described which is economical and rapid and adaptable to mass production.

The foregoing and other objects of the invention are attained in the method and apparatus described herein by forming a bolt with a simple T-head of relatively small dimensions. On the arms of this T-head are mounted two complementary wedge sections. Each wedge section consists of a wedge-shaped. body having a central aperture to receive one arm of the T-head and a recess along its inner side to receive one side of the shank of the bolt. After the wedge sections are assembled on the T-head, the ends of the T, which project through the apertures in the wedge sections, are flared to grip the wedge sections tightly and hold them on the Thead.

Other objects and advantages of the invention will become apparent from a consideration of the accompanying specification, claims and drawings.

In the drawings:

Fig. 1 is an elevational view of a complete mine root bolt assemblyincluding a wedge head bolt. constructed in accordance with the invention, with certain parts broken away and shown in section to illustrate details of the as- Fig. 2 is an elevational view of a complete wedge head bolt assembly embodying the invention;

Fig. 3 is a plan view of the. bolt of Fig.2;

Fig.4 is a right-hand elevational view of the boltjof Fig. 2, certain parts being shown in section;

Fig. 5 isan elevational view of a T-head bolt which comprises an essential partof thewedge headbolt assembly of Fig. 2; r

Fig. 6 is a plan view of the T-head bolt of Fig. 5;

Fig. 7 is aright-handelevational view of the T-h'ead bolt. of Fig. 5;

Fig. 8'is an elevational view of one of the wedge sections inthe wedge head bolt' assembly of Fig. 2;

Fig. 9 is a plan view. of. the wedge head section of Fig. 8;

Fig. 10 is a sectional 'view on theline .XX of the wedge section of Fig. 8;and

Fig. 11 is a cross-sectional view taken on the line XIXI of Fig. 8, looking in the direction of the arrows Referring to. thedrawings, there is shown in Fig. 1, a

complete mine roof bolt'including a bolt 1 having a Wedge head 2 and a pair of anchor shell sections 3 supported on;

the wedge head. The shell sections 3 are provided on their upper ends with bent-over tangs 3a which are .re-,

ceived in a central recess 2a formed in the wedge-head 2.

The tangs 3a are of spring material and bias the skirts of the shell sections 3 outwardly. The arrangement is such that when the bolt with the shell sections mounted on it is inserted into a hole, the shell sections are pressed back against the bolt by the sides of the hole, so that the shell sections move into the hole with the bolt. When the head of the bolt has been inserted to the desired depth, it is then pulled outwardly slightly, and the inclined surfaces 2b of the wedge head 2 cooperate with wed-ging surfaces 311 formed on the shell sections 3 to force the latter tightly against the sides or wall of the hole, thereby anchoring the bolt firmly in the hole.

Referring now to Figs. 2 to 11, it may be seen that the wedge head bolt generally indicated by the reference numeral 1 is built up from a T-head bolt 4 and two wedge sections 5. The T-head bolt 4 comprises a shank 4a and two oppositely projecting arms 412. Each wedge section 5 consists of a generally wedge-shaped body having a central aperture 5a adapted to receive one of the arms 4b of the T-head, and a longitudinally extending recess 5b, which is adapted to receive and engage tightly the shank 4a.

The arms 41) of the T-head are tapered outwardly, i. e., their diameter is greater at the shank than at the free endt'he purpose being to provide greater shear strength at the shank and to facilitate forming the head. The apertures 5a in the wedge section 5 are similarly tapered so that the wedge sections fit snugly on the T-head. After the Wedge sections are mounted on the T-head, the ends of the T may be flared by striking them sharply with a convex surfaced tool, thereby spreading their edges so that they grip the wedge sections 5 tightly and hold them in place.

The wedge sections 5 are provided with fiat abutting surfaces 50. When both wedge sections are in place on the T-head bolt 4, the surfaces 5c abut against each other and are held in firm engagement when the ends of the T-head arms 4b are flared.

The recesses 5b conform in contour to one-half the shank 4a. In the structure shown, the shank 4a is cylinclrical and the recesses 5b are semi-cylindrical.

.The recesses 5b extend throughout the length of the wedgesections 5, as shown in Figs. 8 and 10. The upper Patented Mar. 4, 1958 ends of these recesses 5b are above the upper end of the T-head bolt 4, and cooperate to define a cylindrical recess 2a in the upper end of the wedge head bolt. The cylindrical recess 2a is adapted to receive the tangs 3a supporting the shell sections 3, as illustrated in Fig. 1.

Each of the principal parts of the wedge head boltdescribed herein may be formed readily and accurately by a simple forging operation. Thisstructure is economical of material and may be assembled rapidly. When assenr bled, the parts remain permanently in place, even though severe stresses may be applied to the wedging surfaces.

While we have shown and described a preferred embodiment of our invention, other modifications thereof will readily occur to those skilled in the art, and we therefore intend our invention to be limited only by the appended claims.

We claim: i

1. A wedge head mine roof bolt construction comprising a shank having at one end two oppositely projecting arms defining a T-head, and two complementary wedge sections, each wedge section comprising a body having an aperture receiving one of said T-arms, a recess to receive one side of said shank, said recess intersecting said aperture, and two inclined wedging surfaces extending longitudinally of the section and parallel to the axis of said aperture and converging toward a point spaced along the shank from said T-arms, said wedge section bodies having abutting surfaces, said arms being flared at their ends after assembly of the wedge sections thereon to hold the wedge sections in place, said recesses extending beyond said T-head and providing a generally cylindrical aperture in the end of the wedge head.

2. A wedge head mine roof bolt construction comprising a shank having at one end two oppositely projecting arms defining a T-head, and two complementary wedge sections, each wedge section comprising a body having an aperture receiving one of said T-arms, a plane surface extending at an angle to the axis of said aperture and adapted to abut a similar surface on the other wedge section, and two inclined plane surfaces extending longitudinally of the section and parallel to the axis of said aperture and converging toward a point spaced along the shank from said T-arms.

3. A wedge section adapted for mounting on a T-head mine roof bolt including a body having an aperture adapted to receive one of the T-arms of said T-head mine roof bolt and a recess adapted to receive the shank of the belt, a plane surface extending at an angle to the axis of said aperture and adapted to abut a similar surface of a complementary wedge section similarly adapted for mounting on said T-head mine roof bolt, and two inclined plane surfaces extending longitudinally of the section and parallel to the axis of said aperture and converging toward a point spaced along the shank-receiving recess from said T-arms.

References Cited in the file of this patent UNITED STATES PATENTS 13,177 Loudon et al July 3, 1855 347,921 Connolly Aug. 24, 1886 448,224 Glover Mar. 17, 1891 680,609 Marquardt Aug. 13, 190i 1,699,546 Scheibli Jan. 22, 1929 1,851,292 Rasmussen Mar. 29, 1932

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