US3030088A - Cutter bit holder - Google Patents

Description

April 17, 19,62 H. A. DEvlNE ET AL 3,030,088

El .lllIlll/f ummm NNNNNNN RS 3,030,038 t CUTTER BET HLDER Hamid Aaron Devine and Asa Lloyd McLaughlin, Carlsbad, N. Mex., assignors to Potash Company oi America, Qarlsbarl, N. Mex., a corporation ot Coiorado Filed Dec. 22, 1958, Ser. No. 782,049 6 Claims. (Cl. 262-33 This invention relates to cutter bit holders, and more particularly bit lfastener assemblies which are arranged to be mounted on continuous mining machines, and the like, utilizing rotary drums, moving chains, and the similar moving mechanisms which carry cutter bits in a disintegrating action against ore in place.

There are diierent types of mining machines operating in the mining industry which utilize a removal cutter -bit mounted on a holder which is secured to a moving means, such as the links of a cutter chain, a rotary drum and the like. Cutter -bits with narrow shanks are placed in the holders and held in position for an attack on the ore face. The cutter bits themselves may take a variety of shapes but lthey all generally include a shank for securing in the holder and a hardened tip which is the cutting surface. ln such mining machines, the cutter bits move at a relatively high velocity and the impact of the cutter bit against the ore face is extremely heavy. While the impact forces are heavy while the cutter bit is in contact with the ore face, the force is exerted by the shoulder of 'the cutter bit against the body of the bit holder and it is only necessary to retain the bit in its recess while it is not in engagement with the Ore face to prevent its loss due to centrifugal force.

ln mechanical mining operations the dust and `lit produced by the operation of the machine is extremely heavy and penetrating. The dust settles and packs in crevices and voids in and around all mechanism that if sufficient dust accumulates in the socket around the holder mechanism, it prevents free action of the holder mechanism which makes it difficult or impossible to insert and withdraw the bits.

Many different types of holders have been proposed for cutter bits which include simple set screws through elaborate spring and plunger combinations. While some of these work satisfactorily for a period of time, the dust soon accumulates in voids lling and packing the same and preventing correct operation of the cutter bits. Also, the assembly and disassembly ot these with the holder is diilicult and time consuming.

According to the present invention we have provided a simplied and highly effective cutter bit fastener assembly which is essentially self-cleaning thus preventing Ithe accumulation of dust and grit. rthe cutter bit fastener assembly, furthermore, provides a simplified and highly effective means for replacing worn cutter bits, so that machine down time for cutter bit replacement is substantially reduced, and in certain instances it is reduced to about a fourth of the time normally necessary. The simplied cutter bit holder assembly is less expensive to make than other quick change bit holders, and it is arranged to replace standard set screws without modiiication of the cutter mounts.

It is an important object of the invention to provide a simplilied and highly eifective mining machine spring loaded, cutter bit fastener assembly.

It is a further object of the invention to provide a mining machine cutter bit fastener assembly which may be used in unmodiied standard cutter bit mounts whereby the fastener assembly of the invention is interchangeable with standard set screws.

A further object of the invention is to provide a simpliiied cutter bit fastener assembly which is essentially self-cleaning under the action of the cutter bit.

w Patented Apr. 17, 1962 A still further object of the invention is to provide a cutter bit fastener assembly which reduces the time and eiiort necessary to replace cutter bits in the mount, and the replacement of such cutter bits is simply and easily accomplished with simple tools.

A still further object of the invention is to provide a simpliiied cutter bit fastener assembly which is completely replaceable with a set screw.

These and other objects and advantages of the inven- -tion may be readily ascertained by referring to the following description and appended illustrations in which:

FIG. 1 is a side elevational View, in partial section, of a cutter bit fastener assembly and a cutter bit mount according to the invention;

FIG. 2 is an end elevation of the device of FIG. 1; and

FiG. 3 is an enlarged detail of the fastener assembly of PEG. 1.

In the device illustrated, a cutter bit 1 is arranged to be mounted in a recess 2 in a cutter bit mount 3. The cutter bit mount may be any shape suitable for mounting on a movable disintegrating member, partially shown at 4. in one form, the cutter bit mount 3 includes a body 16 supported on legs 18 and 19. A threaded recess 5 extends from a side of the body 16 into the recess 2. The disintegrating member may be a chain, drum or the like, and in common practice the mount 3 is welded onto ythe moving member 4.

Threaded into the threaded bore 5 is a set screw 6 which has a square head 7 and an internal bore 8 terminating in an exterior opening 17. A portion 9 of the bore 8 adjacent the head 7 is threaded. A hexagonal jam nut lll is mounted on external threads 11 of the set vscrew 6, and the jam nut is arranged to releasably secure the set screw 6 in position in the bore 5. A helical or coil spring '12 is threadedly engaged with lthe threads 9 of the set screw 6. The spring is slightly compressed as it is engaged with the threads so that it has a snug fit and is securely held therein by the engagement. A round end plunger 14 is threadedly engaged by means of threads i5 with the opposite end of vthe coil spring i2. The plunger 14 is thus arranged for reciprocable movement in the bore 8 and is retained therein by the spring. The rounded end extends beyond the inner end `of set screw 6.

The cutter bit 1 as illustrated includes a head portion 2li which terminates at its upper end in a hardened insert 21 which is the actual cutting member, and a bearing shoulder 22 at the lower end. The head 2t? is attached to a shank portion 23 which is arranged to be inserted inio the recess 2 in the mount. An indentation 24 in the rear portion of shank is in alignment with the bore 5 when shoulder 22 is seated on surface 3a. ln this position the end of the plunger ltd is forcibly engaged with the shank, but is releasable since the plunger may be depressed out of the recess. The shank 23, also, includes a lower sloped surface 26, which is cut away from the lower corner of the rear part of the shank, to permit the cutter to be inserted into the slot and ride over and depress the plunger i4 during insertion thereof.

In one common form of mining machine a set screw is mounted in bore 5 and is forcibly seated on the cutter bit shank for holding same in the recess 2. Obviously, the cutter can only be inserted or withdrawn by backing up the set screw to permit the travel of the cutter bit into and out of the recess 2. The cutter bit is held by tightening the set screw to hold the bit in place in the recess.

The fastening assembly of the invention, which is a set screw with a contained plunger, may replace the normal set screw without modiication of the mount. When in position in the mount, the plunger 14 forcibly rests in the indentation 24 of the cutter bit. The spring loaded plunger permits the cutter to rock or move in the recess during cutting action. Movement of the bit causes movement of the plunger to prevent a build up of dust and grit in the set screw bore and in and around the spring therein. The open end 17 of the set screw 6 permits a free passage of dust and grit, and the piston-like action of the plunger i4 keeps bore clear and prevents packing of the dust and grit therein.

The cutter fastener assembly 3 is illustrated as an essentially cylindrical upper body 16 terminating in lower legs 18 and t9. With this arrangement a space is left between Vthe legs and the body portion into which the lower end f the cutter bit shank extends. This space permits the use of a pry tool for prying out the cutter bit. Since the cutter bit is held under spring load in the recess 2, a pry tool such as a screw driver or other small implement is merely inserted under the end of the cutter and a quick pry pops the cutter out of the recess. The cutter is easily assembled into the recess by merely pushing it or in some instances tapping it slightly to depress the plunger and to permit the cutter to move into position in the recess.

The indentation 24 is shown as a three-sided indentation, it is obvious, however, that this may be any type of indentation to accommodate the rounded end of the plunger 14 for holding the cutter in position in the mount. 'I'he sloped sides of the preferred form of recess aid in removal of the bit Since the plunger will ride up the sloped sides and be depressed permitting withdrawal of the bit.

The modification illustrated shows a preferred form of A closed end on the outer end of the bore may be desirable under certain conditions. However, under ordinary conditions, the open end is the preferable form since the great amount of dust and grit which is produced by the use of the mining machine is easily removed through the open end of the bore by the piston action of the plunger.

While the invention has been illustrated by reference to specific embodiments, there is no intent to limitthe -a set screw with bore extending completely therethrough.

scope or the spirit of the invention to the precise details p so set forth. For example, the set screw is shown with a square head 7 and is secured by a hex jam nut 10. This, however, may be easily modified to provide a standard hex head on the set screw. The set screw may, also, be a standard mild steel bolt, or other common bolt, drilled and tapped to accommodate the spring and plunger. Further, the jam nut may be replaced by any common holding means to lock the bolt or set screw in position for positioning the plunger. For simplicity and ease of manufacture and assembling, the use of the Spring threaded onto the plunger 14 and threaded into the bolt is a preferred form. Other means of attachment may be utilized where replaceability is not a factor. Thus the spring may be welded or otherwise securely fastened to the plunger 14 and similarly fastened in the set screw. Other modifications may occur to those skilled in the art as obvious equivalents and such are intended to be included in the scope and spirit of the appended claims.

We claim:

1. The combination of a cutter bit mount fixed on a movable ore disintegrating member and having a recess for holding the shank of a cutter bit, there being an internally threaded bore extending from an end of said mount into said recess substantially perpendicular to the lengthwise axis of a held cutter bit and in alignment with an indentation on the shank of said bit facing the bore, `a tubular member having an externally threaded shank portion engaged with the threads of said bore and terminating at an outer end, the passage in said tubular member having a threaded portion at least adjacent its outer end, a plunger reciprocably mounted in said passage and having an end extending beyond said shank portion, the inner end of said plunger being connected to a coil spring intermediate the ends of said passage and extending rearwardly therefrom a substantial distance through said passage, the opposite end of said spring being in threaded engagement with the threads of said passage in said tubular member providing an opening through said tubular member opposite said plunger, and means for removably securing said member in said mount in position for forceful engagement of said plunger with the indentation on said shank of the bit.

2. A cutter bit fastener assembly comprising a bolt including a head portion arranged to be disposed outside of a bore in which said bolt is mounted, an internal bore extending through said bolt and head portion, and the body of said bolt being arranged for releasably securing the same in a mount; a plunger mounted for reciprocal movement in said bore and having a portion normally extending beyond said body; and a spring held at one end against outward movement from the bore through said head portion and arranged to maintain said bore open, said spring being releasably secured at its opposite end on a rear portion of said plunger intermediate the ends of said internal bore to force the plunger toward its normal extended position.

3. A cutter bit fastener assembly comprising a bolt including a head portion arranged to be disposed outside of a mount in which said bolt is mounted, an internal bore extending through said bolt and head portion and partially threaded adjacent said head portion, and the body of said bolt being arranged for releasably securing the same in said mount; a plunger having a threaded inner portion mounted for reciprocal movement in said bore and having a portion normally extending beyond said body; and a helical spring threaded in said internal bore and arranged to maintain said bore open at the head portion end, said spring being threaded to Said plunger intermediate the ends of said internal bore and arranged to force said plunger toward its normal extended position.

4. The combination of a cutter bit mount fixed on a movable ore disintegrating member and having a recess for holding the shank of a cutter bit, said mount having a surface adjacent said recess arranged as a shoulder for butting relation with an external bearing shoulder on a cutter bit mounted in said recess and having a passage extending from an end of said mount in said recess substantially perpendicular to the lengthwise axis of a held cutter bit and in general alignment with an indentation on the shank of a bit facing said passage, of a bolt assembly having a shank arranged for telescoping engagement in said passage and terminating at its outer end in a head portion, said bolt having a bore extending through the shank and said head portion, a plunger reciprocally mounted in said bore and having one end normally extending beyond said shank in position to contact an indentation on a carried cutter bit, a coil spring disposed in said passage bearing against said plunger at one end intermediate the ends of said bore and held in said bore against outward movement through the head portion at its other end in position to maintain said bore open through said portion, and means for releasably securing said bolt in engagement with the mount whereby to maintain the plunger in forceful engagement with the indentation of a carried cutter bit.

5. The combination with a cutter bit for mining operations having a shank portion fitted in a socket, of a plunger assembly mounted in a threaded opening extend'- ing into said socket at substantially right angles to the lengthwise axis of said shank, said plunger assembly comprising an externally threaded bolt held in said opening and having an internal open-ended bore extending throughout its length, a plunger member disposed in the forward end of said bore with a portion arranged for movement into and out of engagement with said shank, a coil spring mounted on the rear end of said plunger and extending rearwardly therefrom through a major portion of said bore to provide a passage of substantial diameter for relief of dust consituents moving through said socket, and means bearing against the rearward end of said spring within said bore so as to limit movement of the spring therein.

6. A cutter bit fastener assembly comprising a bolt including a head portion arranged to be disposed outside of a passage in which said bolt is mounted, there being a continuous and unobstructed bore of substantially uniform diameter extending throughout said bolt and head portion from one end to the other, means on said bolt for holding the same in said passage means mounted for reciprocal movement at the forward end of said bolt bore and having a bit-engaging portion normally extending outside of said bolt bore,'and a second resilient portion interconnected therewith and disposed intermediate the ends of said bolt bore, said resilient portion extending a substantial distance through said bore from its interconnection With said bit-engaging portion, and means adjacent the rear end of said bore for preventing outward movement of said resilient portion and to maintain it under compression when said bit-engaging portion is in engagement with the shank of a cutter bit, said resilient 6 member forming a continuous and unobstructed passage of substantially uniform diameter within said bore providing a substantial outlet from said passage for unobstructed free outow and discharge of dust and line material from said assembly. A

References Cited in the file of this patent UNITED STATES PATENTS 1,023,490 Beck et al Apr. 16, 1912 1,430,669 Morgan Oct. 3, 1922 1,644,783 Lisset Oct. 1l, 1927 1,859,350 Wilson May 24, 1932 1,904,759 Hueber Apr. 18, 1933 2,139,841 Mennesson Dec. 13, 1938 2,297,715 Nordstrom Oct. 6, 1942 2,316,626 Rothwell Apr. 13, 1943 2,379,528 Kelliher July 3, 1945 2,450,593 Hermes Oct. 5, 1948 2,766,029 Bruestle Oct. 9, 1956 2,907,559 Brown et al Oct. 6, 1959 FOREIGN PATENTS 743,234 Great Britain Jan. 11, 1956

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