US2732198A

US2732198A - Mining machine cutter bit

Info

Publication number: US2732198A
Authority: US
Publication date: 1956-01-24
Anticipated expiration: 1973-01-24

Description

Jan. 24, 1956 J. F. JOY

MINING MACHINE CUTTER BIT Filed April 10, 1948 L 5/ "I Fig.3. 1

IHIIi'iiQlllI Q 132216727507: (Ewe 972E Joy.

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United States Patent 7' 7 MINING MACHINE CUTTER BIT Joseph F. Joy, Pittsburgh, Pa., assignor to Joy Manufacturing Company, Pittsburgh, Pa., a corporation of Penn!- sylvania Application April 10, 1948, Serial No. 20,254

4 Claims. (01.262-33) This invention relates to a mining machine cutter bit.

In cutter bits, such as those used with the cutter chain of a coal mining machine, the cutting points are subjected to severe stress loads and abrasion during the cutting operation, and the conventional single pointed, shank type bits become rapidly worn and frequently broken during use, necessitating frequent replacement. Hard facing material has been applied to thefaces of the cutting points, with resultant increase in bit life, and, in known instances, hard metal inserts have been brazed on the cutting tips to resist excessive wear. Even with such hard metal inserts, it has been-found necessary to resharpen the cutting points by grinding at intervals, and difiiculty has been encountered in the provision of adequate support for. the insert while' attaining the desired cutting clearances. The present invention contemplates, improvements over, such known types of cutter bits in that a cutter bit is constructed in a novel manner whereby a self-sharpening cutting point is provided, resulting in a greatly increased bit life. Also by the improved construction, a hard metallic substance is firmly embedded in a novel location in the cutting portion of the cutter bit, not only resulting in longer bit life but also greatly increasing cutting efliciency while maintaining the cost of manufacture at a minimum as compared with known types of cutter bits with hard metal inserts.

An object of the present invention is to provide an improved cutter bit. Another object is to provide an improvedcutter bit especially designed for use with a mining machine cutter chain, having a hard metallicsubstance embeddedin the cutting point in a novel manner. A further object is to provide an improved cutter bit having a hard metallic core in its cutting portion to procure aself-sharpening cutting point. Yet another object is to provide an'improved'cutter bit having a hard metallic substance which is inserted in position on the bit blank prior to the formation of the cutting point. A further object is to provide an improved cutter bit wherein a hard metallic substance is firmly embedded in the cutting point during the heating and forging process and so located that after forging, a self-sharpening cutting point is provided. Another object is to provide a hard metallic substance embedded in the cutting portion of a cutter bit, which substance may relatively freely flow when heated during forging, so that repeated reforging of the cutting portion as the point wears away is possible, resulting in an improved cutter bit having relatively long life. These and other objects and advantages of the invention will, however, hereinafter more fully appear.

In the accompanying drawing there is shown for purposes of illustration one form which the invention may assume in practice.

In this drawing:

Fig. 1 is a view, partially in side elevation and partially in longitudinal section, of the improved cutter bit.

Fig. 2 is a view, partially in end elevation and partially in longitudinal section, of the cutter bit shown in Fig. 1.

2,732,198 Patented a... 24, 1956 Fig. 3 is a view, partially in side elevation and partially in longitudinal section, of a partially formed bit blank which has been drilled to receive a hard metallic substance and which has had such a substance inserted therein.

Fig. 4 is an end elevational view of the bit blank shown in Fig. 3.

Figs. 5, 6 and 7 are detail sectional views taken respectively on lines 5-5, 6-6 and 7-7 of Fig. 1.

The improved cutter bit may be made in various manners but as shown in Figs. 3 and 4, the same, for illustrative purposes, is made up of a metal blank 1 which is first cut from suitable rectangular shaped bar stock to provide a bit shank 2, and the outer portion of the blank is preformed, as by forging, to provide a tapered outer end at 3. The partially formed blank is then longitudinally drilled, or otherwise formed, to provide a hole 4 in parallelism with the front face of the bit shank and preferably located at a point nearer to the front face of the shank. than to the rear face, as shown in Fig. 3. The drilled hole 4 is then filled with a wear resisting hard fac ing material 5, which, in this instance, may consist of a piece of standard hard facing rod, as for example, standard B rod or other similar suitable material now available. Such hard facing rod may comprise a cylindrical tube of a suitable welding alloy and containing tungsten carbide crystals. Also, the hard metallic substance may comprise loose tungsten carbide crystals or pellets mixed with a suitable welding compound and inserted in the drilled hole without employing the outer tube. The bit blaukis preferably brought up to a welding temperature ina highifrequency furnace or other suitable heating apparatus, 'as to cause the metallic substance to be welded or fused into place during the heating process. When the outer tube of Weldable alloys is used, a very effective welding or fusing of the hard metallic substance to the bit body is attained. Under certain conditions, it may be necessary to bring only the point of the bit up to a fusable temperature prior to forging. Upon completion of the welding process and while the point is still at a forging temperature, the partially formed bit may be given its final form by a forging operation, as by running it through a conventional roller type cutter bit sharpener (see the patent to Johansen 1,604,414), the roller die of which is shown in broken lines at 6 in Fig. 3, to provide a forwardly and outwardly inclined tapered cutting portion 7.

During the rolling process, that is, during the formation of the cutting portion, the hard metallic substance is drawn out to provide the cutting tip 8 of the bit, and as it is so drawn out during forging within the bit sharpener, the cylindrical core has a tendency to flatten out and taper in the manner shown in Fig. 1. The hard metallic substance is so located in the cutting portion of the bit that the hard material at the extremity of the cutting portion is drawn to the cutting point of the bit even as the bit point becomes worn during use, and resharpening by forging is necessary. Thus, the hard metallic substance serves to form a hard cutting point throughout the life of the bit even after several forging operations to resharpen the cutting portion after excessive wear occurs. The core of hard metal is firmly bonded to the adjacent walls of the cutting portion of the bit, and due to its tapered shape, there is little possibility of the core becoming torn loose.

As a result of this invention, an improved cutter bit is provided which has a hard metallic substance embedded in the cutting portion of the bit to provide a self-sharpening cutting point. As the metal of the bit which surrounds the hard metallic substance at the point of the bit wears away during use, a new portion of the hard metal is exposed and wear may occur along a substantial part of the in the manner disclosed, repeated reforming operations by forging may be given while a hard cutting point is maintained. By embedding the hard metallic substance in the cutting portion of the bit during the forming process, a substantially integrally formed structure is afforded at the point so that the possibility of the hard metal becoming torn loose from the bit body during use is avoided. By the steps of manufacture disclosed, an improved cutter bit is provided, resulting in the firm embedding of a hard metallic substance in the cutting portion of the bit to provide a self-sharpening cutting point, thereby not only greatly increasing bit life but also substantially reducing the overall cost of cutting while cutting eificiency is substantially increased. By the provision of a hard metallic substance which flows relatively freely when heated to the proper temperature and by locating the substance in the cutting portion of the bit in the manner disclosed, it is possible to repeatedly reform the cutting portion of the bit by passage through the roller sharpener while maintaining the desired hard metal cutting point. These and other advantages of the invention will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice it Wil be understood that this form is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure as Letters Patent is:

1. A cutter bit comprising a bit body having a shank and an integral outer end portion providing a plane front face disposed at an oblique angle with respect to the shank and a receding outer surface, said front face and said receding surface converging forwardly and outwardly at the bit point, said end portion having an opening formed therein centrally between the sides thereof and in close adjacency to said front face and opening outwardly through said bit point, the forward wall of said opening inclined at a slight angle with respect to said front face, said opening being tapered in longitudinal section with its narrow end opening out through the bit point and its wider end extending into the bit shank, and a hard metallic material in said opening and secured by bonding therein and extending to the bit point to provide a wear resisting cutting tip, said forward wall of said opening at and in adjacency to the bit point being relatively thin whereby as the cutting tip wears away during use, the wear resisting material is gradually exposed to provide a tip which is self-sharpening.

2. A cutter bit comprising a bit body having a shank and an integral outer end portion providing a plane front face disposed at an oblique angle with respect to the shank and a receding outer surface, said front face and said 4 receding surface converging forwardly and outwardly at the bit point, said end portion having an opening formed therein centrally between the sides thereof and in close adjacency to said front face and opening outwardly through said bit point, the forward wall of said opening inclined at a slight angle with respect to said front face, and a hard metallic material in said opening and secured by bonding therein and extending to the bit point to provide a wear resisting cutting tip, said opening being circular in cross section at its inner portion and said opening as it extends toward the bit point flattening out into substantially ovate form in transverse section so that at the tip of the bit the wear resisting material in the opening is of substantially greater width than its thickness, said forward wall of said opening at and in adjacency to the bit point being relatively thin whereby as the cutting tip wears away during use, the wear resisting material is gradually exposed to provide a tip which is self-sharpening.

3. A cutter bit comprising a bit body having a shank and an integral head tapering laterally and from front to back, said head providing a plane front face disposed at an oblique angle with respect to the shank and a receding outer surface, said front face and said receding surface converging forwardly and outwardly at the bit point to provide such taper from front to back, said head having a hard metal core disposed centrally between its tapered sides and extending to the bit point, the thickness of said core progressively increasing in longitudinal section as it extends from the bit point rearwardly along lines nearer the front plane face than to said receding surface, and extending into said shank, with the thinner portion of said core which extends to the bit point providing a wear resisting cutting tip.

4. A cutter bit as set forth in claim 3 wherein the width of the transverse cross section of said core is uniform throughout its length.

References Cited in the file of this patent UNITED STATES PATENTS 1,497,097 Everist June 10, 1924 1,677,055 Simons July 10, 1928 1,798,229 Spang Mar. 31, 1931 1,902,513 Meutsch Mar. 21, 1933 1,908,161 Meutsch May 9, 1933 1,908,208 Yassenoif May 9, 1933 2,041,346 Jaques May 19, 1936 2,161,062 Killgore June 6, 1939 2,330,081 Phipps Sept. 21, 1943 2,483,220 Morrow Sept. 27, 1949 FOREIGN PATENTS 592,580 Germany Feb. 10, 1934 670,880 Germany Ian. 26, 1939