BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to a cutting bit designed for being rotatably retained within a socket mount. This invention also relates to a socket mount having retained therein a pick type cutting bit useful in mining and/or construction having a working head and a cylindrical shank including an annular recess in which is retained a split tubular spring sleeve partitioned from the working head by a spacer. Description of the Related Art Cutting bits according to the present invention are well known in many industries. For example, one type of cutting bit useful in the cutting industry has a working head of a generally conical shape having a shoulder with the apex of the head having secured thereto by brazing an axially disposed insert of cemented tungsten carbide. Depending from the shoulder of the working head is a shank which is inserted into a socket mount.

The cutting bit is generally utilized in a mining or construction machine having a power driven cutter wheel. In these machines, the power driven wheel is mounted on a horizontal shaft with the plane of the wheel disposed vertically. The wheel has on its periphery an array of pick type cutting bits mounted in a plurality of permanent socket mounts adapted to hold

the carbide tipped cutting bits. The socket mounts typically include a bore of a cylindrical shape having . either a conical opening or simply a substantially cylindrical opening. The cutting bits are mounted generally tangentially on the peripheral rim of the supporting wheel so that through the rotation of the wheel about its axis, the cutting bits may attack the material to be broken up by the horizontal reach of the cutting bits operating in a vertical plane. While the machines are in operation, it is beneficial that the cutting bits rotate freely in the socket mounts. This allows the wear upon the cutting bits and the carbide inserts to be distributed evenly allowing the cutting bits to retain a symmetrical shape.

One attempt at providing a support mount allowing for the free rotation of a cutting bit having a working head and depending shank is disclosed in U.S. Patent No. 4,201,421. U.S. Patent No. 4,201,421 discloses a spring sleeve of cylindrical form with a slot extending the full length of the spring sleeve along substantially all of the shank of the cutting bit. The cutting bit is inserted into the socket mount shank first until a shoulder having a chamfered shape is near the conical opening of the socket mount. The spring sleeve frictionally engages the inside wall of the socket mount keeping the cutting bit in a working position on the rim of the wheel.

Free rotation of the cutting bit is provided due to the impact of the cutting bit against the material to be worked. However, the impact of the cutting bit against the socket mount also has a tendency to deform a portion of the socket mount between the working head and spring sleeve. This portion of the socket mount at the juncture of the conical opening and cylindrical shaped bore deforms into the adjacently positioned gap between the

chamfered shoulder and the spring sleeve as the chamfered shoulder of the working head impacts against the conical opening. This deformity has the appearance of a raised ridge on the interior socket mount wall surface. The deformity makes the removal of a cutting bit having a spring sleeve from the socket mount difficult resulting in increased machine downtime and expense. Moreover, in many instances the socket mount must be replaced because of the deformity. It will be appreciated that at the opening of a socket mount having a substantially cylindrical shape, a similar portion of the socket mount also has a tendency to deform into the adjacently positioned gap between a cutting bit having a straight shoulder and the spring sleeve as the straight shoulder of the working head impacts against the entrance to the socket mount.

To alleviate the aforementioned problems, we have invented a cutting bit having a working head and a supporting shank depending therefrom. The supporting shank has an annular recess in which is retained a spring sleeve of cylindrical form with a slot extending the full length of the spring sleeve. The annular recess and spring sleeve are partitioned from the working head by a spacer which substantially conforms to the size and shape of the interior surface of the socket mount at the opening of the cylindrical shaped bore. Because the spacer substantially conforms to the size and shape of the interior surface of the socket mount at the entrance of the opening and cylindrical shaped bore and the annular recess is partitioned from the working head by the spacer, the formation of a ridge is minimized or prevented at the interior surface of the socket mount between the working head and spring sleeve as the cutting bit repeatedly impacts upon a material to be worked. Furthermore, the area of the shank contiguous the chamfered end of the working head

of the cutting bit is strengthened by the increased cross-section of the spacer.

Accordingly, it is an object of the present invention to provide a cutting bit useful for mining and/or construction having a spacer which substantially conforms to the size and shape of the interior surface of a socket mount at the juncture of the opening and cylindrical shaped bore of the socket mount and partitions a spring sleeve from the working head of the cutting bit to minimize or prevent a ridge from forming on the interior surface of the socket mount between the working head and spring sleeve as the cutting bit repeatedly impacts upon a material to be worked.

It is another object of the present invention to provide a high strength steel spring sleeve retained within an annular recess of a cutting bit such that the annular recess is partitioned from the working head of a cutting bit by a spacer wherein the cutting bit is allowed to rotate within the spring sleeve which is frictionally held on the inside wall of the socket mount while keeping the cutting bit in a working position on the rim of a wheel.

Another object of the present invention is to provide a cutting bit including a working head having a shoulder and a shank of circular cross-section depending therefrom wherein the shank of the cutting bit has a spacer contiguous with the shoulder.

Another object of the invention is to provide a mining and/or construction machine with cutting bits mounted on the periphery of a mining and/or construction wheel in such a fashion as to be readily removed and replaced at a relatively low cost keeping the machine in prime working condition with a minimum amount of down time. A further object of the invention is to provide a cutting bit and a socket mount which will increase the life of the unit by reducing the stress

and wear on the cutting bit and the socket mount by providing a high strength steel spring sleeve partitioned from the working head by a spacer.

SUMMARY OF THE INVENTION Briefly, according to this invention, there is provided a cutting bit and a socket mount to rotatably support the cutting bit. The socket mount includes a bore of a cylindrical shape having either a substantially conical opening or a substantially cylindrical opening at a front end thereof. The cutting bit has a working head having a shoulder and a shank of circular cross section depending therefrom for insertion into the socket mount. The shoulder of the cutting bit may be either chamfered or straight. The shank of the cutting bit includes a spacer positioned contiguous with the shoulder of the working head, an annular recess positioned contiguous with the spacer, and an annular retainer positioned contiguous with the annular recess. The annular recess has a circumference smaller than the circumference of the spacer and the annular retainer has a circumference larger than the circumference of the annular recess. The spacer partitions the annular recess from the working head such that the shoulder and the spacer in cooperation, substantially conform to the size and shape of the interior surface of the socket mount at the juncture of the opening and cylindrical shaped bore to minimize or prevent a ridge from forming on the interior surface of the socket mount between the working head and a spring sleeve disposed within the annular recess.

The spring sleeve is nonrotatable and has an unstressed diameter greater than the diameter of the spring sleeve when the spring sleeve is disposed within the socket mount with the latter diameter greater than that of the circumference of the shank adjacent the spring sleeve when the spring sleeve is disposed on the

shank so as to allow rotation of the shank in the spring sleeve. The spring sleeve is spaced from the opening of the socket mount and adapted to expand radially relative to the shank against the cylindrical shaped bore and to abut endwise against the spacer to retain the shank of the cutting bit within the socket mount.

BRIEF DESCRIPTION OF THE DRAWINGS Further features and other other objects and advantages of the invention will become clear from the following description made with reference to the drawings in which:

Figure 1 is a perspective view of the cutting bit and socket mount located on the periphery of a mining and/or construction machine wheel;

Figure 2 is a longitudinal view of the cutting bit including a spring sleeve;

Figure 3 is an exploded, partly sectional view of the socket mount, spring sleeve and cutting bit;

Figure 4 is a partly sectional view of a cutting bit including a spring sleeve located in a socket mount; and

Figure 5 is a fragmentary sectional view of a cutting bit, spring sleeve and socket mount.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in which the reference characters refer to similar parts throughout the several views, Figures 1-5 show a cutting bit 10, spring sleeve 12 and socket mount 14 in accordance with the present invention. As shown in Figures 4 and 5, The socket mount 14 for the cutting bit 10 contains a cylindrical shaped bore 16 having a front opening 18 of either a conical shape, Figures 4 and 5, or a straight shape, Figure 3. The socket mount 14 may be located on a mining or construction wheel 20 as shown in Figure 1. The opening 18 is formed within the front face of the

socket mount 14 at a front end of the cylindrical shaped bore 16.

The cutting bit 10 is generally short and includes a conically shaped working head 22 having a shoulder 24 and a shank 26 of circular cross-section. The shoulder 24 of the cutting bit 10 may be either chamfered, Figures 2, 4 and 5, or straight, Figure 3. The chamfered shoulder tapers ^■ from the conically shaped working head 22 inward toward a central axis 27 of the shank 26 and the straight shoulder projects perpendicularly from the central axis of the shank. The working head 22 of the cutting bit 10 is usually of a circumference greater than that of the shank 26 thereby precluding the possibility of the working head being forced into the socket mount. At the tip of the working head 22 is a pointed insert 28. The insert 28 is preferably made of a cemented metal carbide such as cobalt tungsten carbide but may be made of any other material suitable for the intended purpose of the cutting bit 10. The shape and composition of the insert may be as shown or of any other known insert shape or composition as exemplified by U.S. Patent Nos. 4,725,098; 4,497,520; 4,859,543; Australian Patent Application No. 77179/87 and Kennametal U.S. Patent Application Serial No. 303,514, filed January 27, 1989.

The shank 26 of the cutting bit 10 is that portion which is inserted in the socket mount 14. The shank 26 is of a circular cross-section and is formed integral with and depends from the shoulder 24 of the working head 22. The shank 26 includes a spacer 30 positioned contiguous with the shoulder 24 of the working head 22, an annular recess 32 positioned contiguous with the spacer 30, and an annular retainer 34 positioned contiguous with the annular recess. The spacer 30 partitions the annular recess 32 from the shoulder 24 of the working head 22 such that the shoulder and the spacer, in cooperation, substantially

conform to the size and shape of the interior surface of the socket mount at the juncture of the opening 18 and cylindrical shaped bore 16 to minimize or prevent a ridge from forming on the interior surface of the socket mount between the working head 22 and the spring sleeve 12. The gap formed between the spacer 30 and the bore 16 should be minimized and is preferably approximately 0.003-0.010 inches. The spacer 30 also provides a stop 36, such as a radially perpendicular surface, abutting the spring sleeve 12 to retain the spring sleeve within the annular recess 32 and provide for the transmittal of axial force upon the circumference of the spring sleeve during insertion of the cutting bit 10 into the socket mount. The spacer 30 is preferably a solid annular ring but may be of any design suitable to partition the spring sleeve 12 from the shoulder 24 as more fully described herein. The shank 26 of the cutting bit 10 terminates at its rear end in an annular retainer 34 which fits slidably within the socket mount 14. Although a cutting bit 10 as described herein may be formed in separate parts and then joined, it is preferable that the entire cutting bit be constructed as a single piece of steel such as that described in Kennametal U.S. Patent Application Serial No. 039,208, filed April 16, 1987.

The spring sleeve 12, shown in its uncontracted state, is longitudinally slotted and is preferably made of a resilient metal such as AISI 1050 spring steel heat treated to Rockwell C 45-50. The spring sleeve 12 should have sufficient resilience when it is contracted to produce an adequate holding force for retaining the spring sleeve in position when disposed around the cutting bit 10 within the socket mount. The ends 13 and 15 of the spring sleeve may be right angled as shown in Figures 3 and 4, or one end of ^' the spring sleeve or both ends of the spring sleeve as shown in Figures 2 and 5, respectively may be chamfered

to assist in contraction of the spring sleeve during insertion as more fully described herein.

The cutting bit 10 is inserted into the mount 14 with the spring sleeve 12 positioned within the annular recess 32 between the spacer 30 and the retainer 34, loosely embracing the shank 26. The spring sleeve should be maintained in a contracted state during insertion to maintain the sleeve within the annular recess 32 and to prevent the spring sleeve from extending over the spacer 30. The cutting bit 10 and spring sleeve 12 are simultaneously inserted into the socket mount 14 through the use of axial force in the direction of the socket mount. The spring sleeve 12 initially engages the opening 18 of the socket mount 14. The opening 18 guides the entry of the spring sleeve 12 into the socket mount 14 thereby assisting in the contraction of the circumference of the spring sleeve, such that the spring sleeve is readily capable of sliding into the socket mount. Continued application of axial force completes the insertion of the cutting bit 10 and spring sleeve 12 into the socket mount 14.

As shown in Figures 4 and 5, the cutting bit 10 and spring sleeve 12 are fully inserted in the socket mount 14 and the cutting bit and socket mount are ready to be used for the desired function. The spring sleeve 12 loosely embraces the shank 26 of the cutting bit.10 between the spacer 30 and retainer 34 inside the surrounding cylindrical surface of socket mount 14. The spring sleeve 12 exerts a strong hold on the inner surface of the socket mount 14 and resists axial movement of the cutting bit 10 as the cutter wheel 20 previously described herein rotates. The spring sleeve 12 also provides a bearing surface for receiving and distributing pressure on the cutting bit 10, yet allows the cutting bit to rotate providing for

even wear upon the cutting bit surface thereby prolonging the useful life of the cutting bit.

The spring sleeve 12 acts as a buffer between the cutting bit 10 and the mount 14 absorbing most wear that might result on the socket mount surface or the cutting bit by rotation of the cutting bit or any other interaction between, the cutting bit and the mount. Also, because there is no substantial force tending to pull the spring sleeve 12 and cutting bit 10 out of the socket mount 14, the retaining force of the spring sleeve is at a minimum providing for easy extraction when replacement becomes necessary. Because the retainer 34 of the shank 26 engages the rear end of the spring sleeve 12, extraction of the cutting bit 10 necessarily extracts the spring sleeve adding to the simplicity of such operation.

It will be appreciated that during use the inner surface of the socket mount 14 has a tendency to deform in the shape of a raised ridge at the juncture of the opening 18 and the cylindrical shaped bore 16 due to the constant and repetitious endwise axial pressure caused by the impact of the cutting bit 10 against the material being worked. This raised ridge extends into a gap between the shoulder 24 and the spring sleeve 12 such that withdrawal of the cutting bit 10 from the socket mount 14 is prevented due to the forward edge of the spring sleeve contacting and butting against the raised ridge. The formation of a raised ridge within the cylindrical shaped bore 16 of the socket mount necessitates eventual repair or replacement of the socket mount 14. The present invention alleviates the problem of the formation of a raised ridge by providing a cutting bit 10 having a shoulder 24 and/or a spacer 30 that cooperatively conform to the size and shape of the area at the juncture of the opening 18 and the cylindrical shaped bore 16 of the socket mount 14, thereby minimizing or

preventing the formation of a raised ridge on the cylindrical surface of the socket mount. Moreover, any ridge that may attempt to form on the surface of the cylindrical shaped bore 16 of the socket mount 14 may be easily worn away by the rotation of the cutting bit 10 within the socket mount.

It will be further appreciated that the spacer 30 also strengthens the cutting bit 10 at a most highly stressed area by increasing the cross-sectional area of the shank 26. Furthermore, the spacer 30 provides a bearing surface 38 for receiving and distributing lateral pressure exerted on the cutting bit 10 to the socket mount 14 during the cutting of a material to be worked. For the purpose of clarity the present invention has been described with reference to a cutting bit 10 useful in mining and/or construction. However, it will be appreciated by one skilled in the art that the present invention may also encompass other types of cutting bits utilizing a spring sleeve 12 such as road planing bits, trenching bits and the like.

The patents and patent applications referred to herein are hereby incorporated by reference. Having described presently preferred embodiments of the invention, it is to be understood that it may be otherwise embodied within the scope of the appended claims.