US2828117A - Cutter bits having reinforcing ribs - Google Patents

Description

March 25, 1958 A. o. BRUESTLE ET AL 2,823,117

CUTTER BI'Ts HAVING REINFORCING RIBS -Filed Feb. s. 1955 ATTORNEYS.

' BY v 62 41/05 .49; ham-45K,

United States Patent" 2,828,117 CUTTER mrs HAVING REINFORCING urns Armin 0. Bruestle and Claude B. Krekelen. Cincinnati,

Ohio, assignors to The Cincinnati Mine Machinery Company, incinnati, Ohio, a corporation of Ohio ApplicatiomFebruary 3, 1955, Serial No. 485,888

3 Claims. (Ci- 262--33) In the artof making cutter bits for mining. machines it is well known to roll hardenable' steel to a rod of suitable cross" section, and then form individual bits by cutting the; rod intopieces. If the cuts are all parallel to each otherrhomboidal bits are formed requiring one kind of bit holder. If successive cuts have different angularities to the rod axis, trapezoidal bits'are produced, requiring The rod stoek'from which the bits are made may have different cross sectional shapes. A generally diamond shape is usual. The term cutting point is not strictly accurate because the actual cutting ends of'thebits should not come to a pointlbut should have a certain breadth for cutting efiic'iency'and stability. As a consequence the usual diamond shape cross section of the bit rod stock has'comp'aratively widely rounded corners at the ends of its major transverse axisto' give a desirable breadth at the cutting point. where rhomboidal bits are made, the cutting points are to be found at'oppo's'ite sides of the rod; but they are found atthe same side of the rod when trapezoidal bits are being made.

, While bits of the types hereinabove described are relatively inexpensive and are designed to be discarded when both points have become dulled or broken they have suiiered'fro'm the fact that their service life is comparatively shortfsof that the cost of their use is greater than it should be. I

A primary objector this invention is to provide bits of the types outlined which have a very substantially lengthened service life attained at a negligibledncrease in cost.

' This and other objects of the invention which will be set forth hereinafter or will be apparent to one skilled in the art upon reading these specifications, are accomplished by that construction and arrangement of parts and in those procedures of which certain exemplary embodiments will now be described. Reference is made to the accompanying drawings wherein: 7

Figures 1 to Sinclusive are respectively of cross sections of rod stocks which may be employed in the practice of the invention. 1 V

Figure. dis a partial elevational view of a bit having the im roved characteristics. v i

'- Figure 7- tea partial, plan viewthereof;

Figure 8 is a partial end elevation thereof.

Figure 9 is a partial perspective view of another type of improved bit made from the rod stock of Figure 4.

Figure 10 is a partial side elevation of a bit made from the rod stock of Figure 3.

Figure 11 is a partial plan view thereof.

Figure 12 is a side elevation of a rhomboidal bit.

Itwill be understood, of course, that Figure 13 is a side elevation'of a trapezoidal bit.

Figure 14 is a diagrammatic representation illustrative of the attainment ofia suitable clearance.

The invention here involved is based on the discovery that the strength and wearing qualities of the cutting point of a bit are in large measure dependent upon the depth of metal lying immediatelybehindithe cutting edge. The invention is therefore concerned primarily with increasing this depth of metal without'significantly' adding to thecost of manufacture. As has been indicated, the conventional rod stock for bit manufacture will have an edge or. opposed edges rounded or otherwiseconfigured so as to provide a cutting end of desired width when the rod stock. is cut transversely on a slantwise plane; but it Will' be evident that the actual cutting edge or point is relatively thin and has very little metal backing. As a consequence it is subject not only to comparatively rapid wear but also to breakage or the spalling off of end portions. In essence, the present invention contemplates the provision of a rib on the bar stock which extends beyond that edge portion or those edge portions of the stock designed and configured to provide the actual desired cutting edge or point. The removal of an end portion of this rib in the final bit along a plane chosen to provide adequate clearance, results in the backing of the cutting edge or point by a substantial depth of metal, therebyminimizing spalling and breakage and greatly increasing the. wear resistance'. Bits produced in accordance with this invention have a service life averaging several times thatof conventional bits formed by merely cutting the usual bar stock along slantwise planes.

In Figure 1 there is illustrated thecross sectional shape of bar stock having a body 1 and side portions 2 and 3-' suitably configured for the formation of so called cutting points in the ways set forth above. In accordance with the teachings of this application the rod stock is formed with side ribs 4 and 5, somewhat narrower than the edge portions 2 and 3 and projecting therebeyond as shown. The extra ribs 4 and 5 are indicated as rectangular in cross section, which is an advantageous shape. Lateral ribs 6' and 7 are shown in Figure 1 and are useful in some types ofbit holders for locating and stabilizing the bit. In Figure 2 the lateral ribs have been omitted, the body 8 of the rod stock being conventional in cross section excepting for the addition of the ribs 4 and '5. 1

In Figure 3 there is shown a rod stock having a conventional cross section as at 9 excepting for the addition. of edge ribs 10 and 11. These ribs are triangular in cross section and are somewhat more easily rolled than the rectangular ribs 4 and 5.

Figure 4 is illustrative of arod stock 12 of somewhat different cross section inasmuch as various external faces are concave as shown. In this bit stock' the cutting points are designed to be formed at positions indicated in dotted lines at A and B; and the added. ribs are. shown at 13 and 14.

In Figure 5 a bar stock of diamond shape cross section is shown at 15. The cutting points are designed to fall at positions C and D; but the edge portionsof the mining machinery or the like, the bar stock from which the bits are produced is so dimensioned that the actual cutting points or edges (2, 3 in Figure 1; A, B in Figure be the cutting away of the extra rib adjacent the actual cutting end. Figure 6 illustrates this. The bit having the body portion 1 and the cutting end portion 2 has the extra rib 4 cut away along a plane 20. which lies .at a slight angle to the direction of cutting motion of. the bit in use as exemplified by the arrow E... This results not only in the provision of a suitable clearance but in the backing of the actual cutting end portion 2 of thebit with a substantial thickness of metal extending backwardly of the direction of cutting. This is shown in both Figures 6 and7. Figure 8 is a partial end elevation illustrative of the fact that the rib 4, cut away as shown, does not in any way interfere with the cutting action of the actual cutting end; but reinforces it against wear and breakage. The cutting'away of the rib 4 is most conveniently done by grinding prior to the hardening of the bit although it may be'accomplished in other ways.

The cross sectional shape shown in Figures 2 to inclusive may be similarly treated. Figure 9 illustrates the manner in which the extra rib 13 of the cross sectional shape of Figure 4 is cut away along the plane 21, the cutting direction in this instancebeing shown by the arrow F. The bit shown in Figure 9 is a rhomboidal bit, so that at the opposite corner (not shown). the extra rib 14 will be similarly cut away.

Figure is a partial side elevation of a bit made from the stock of Figure 3, the extra rib 1% being cut away on the plane 22. Figure 11 is a partial top plan view of the same structure. Because of the triangular cross section of the extra rib 10 the cut plane 22 is also triangular in shape, but of very substantial depth. Figures 10 and 11 illustrate a bit which has been tipped with a hard alloy as at 23.

Figure 14 is a diagrammatic illustration showing a portion of a bit having a body 24 and a cutting end 25 together with an extra rib 26. The rib adjacent the point is cut away along a plane 27, the line of travel of the cutting bit in use being illustrated by the line 28. As illustrated, in order to obtain proper clearance, the angularity between the plane 27 and the line of travel 28 should be definitely greater than 0 but preferably less than about in order to secure maximum reinforcement. The dimensions of the extra rib 26 should preferably be such as to give to the plane 27 a length in the line of travel of the bit of at least ,4, inch, but preferably inch or more as illustrated at G.

The bar stock for forming the improved bits of this invention can be made for relatively little added cost of rolling; and since the extra ribs are small in cross section the added Weight of metal is minor, costwise. The bar stock is ordinarily formed by rolling, although it may be otherwise produced as by forging or machining. The cutting of the bar stock is performed as usual, and there is no modification of the steps of heat treating and hardening it current in the art. The steps of grinding away end portions of the extra rib or ribs, preferably done before the hardening step, is of minor cost. Thus the bits of the invention are not significantly more costly than ordinary while providing a greatly enhanced service life. Where hard alloy tipping is practiced, this may be done by procedures current in the art.

The bits moreover may for the most part be used interchangeably with conventional bits in the bit holders current in the art; and if such bit holders require modification at all this can readily be accomplished by recessing them for the accommodation of the uncut away portions of the extra rib or ribs.

Modifications may be made in the invention without departing from the spirit of it. The invention having been described in certain exemplary embodiments, what is claimed as new and desired to be secured by Letters Patent is:

1. A rolled steel rod stock for the formation of cutter bits, said stock being substantially diamond-shaped in cross-section with major and minor transverse axes, the said stock being of a width at points adjacent to but spaced inwardly from the ends of its major transverse axis to provide cutting ends, the said stock terminating at the ends of its major transverse axis in reinforcing ribs of substantially rectangular cross-sectional configuration extending lengthwise of the stock, the said reinforcing ribs being of reduced cross-section with respect to the width of the stock at said cutting ends, but having a depth at least substantially equal to the width of the cutting ends.

2. A rolled steel rod stock for the formation of cutter bits, said stock being substantially diamond-shaped in cross-section with major and minor transverse axes, the said stock being of a width at points adjacent to. but spaced inwardly from the ends of its major transverse axis to provide cutting ends, the said stock terminating at the ends of its major transverse axis in reinforcing ribs extending lengthwise of the stock, the said reinforcing ribs being of substantially less width than the said cutting ends whereby said ribs are demarked from said.

cutting ends by shoulders, said ribs having a depth at least substantially equal to the width of the said cutting ends.

3. A cutter bit having a metallic body substantially diamond-shape in general cross-section, said body being defined in side elevation by upper and lower parallel edge portions, and face planes meeting said upper and lower edge portions respectively at acute and obtuse angles, said face planes having major and minor transverse axes and being of a width at a point adjacent to but spaced inwardly from an end of the major axis to provide a cutting end, the said face planes terminating at the ends of their major transverse axes in reinforcing ribs extending along said edge portions, the said reinforcing ribs being of reduced cross-section with respect to the width of the said face planes at the said cutting ends, but having a depth at least substantially equal to the width of the cutting ends, the said reduction in cross-section providing shoulders at the juncture of said ribs and the remainder of said body, the said ribs being cut away adjacent the said cutting ends at an angle to provide cutting clearance, whereby remaining portions of said ribs adjacent said cutting ends serve to provide a backing for said cutting ends.

4. The structure claimed in claim 3 in which the said ribs are substantially rectangular in cross-section.

5. The structure claimed in claim 3 wherein the said ribs are substantially triangular in cross-section.

6. The structure claimed in claim 3 wherein the said bit is generally trapezoidal in side elevation.

7. The structure claimed in claim 3 wherein said bit is substantially rhomboidal in side elevation.

8. The structure claimed in claim 3 wherein the said bit has protruding side ribs providing shoulders at the ends of the minor axes of said face planes.

References Cited in the file of this patent UNITED STATES PATENTS 2,483,220 Morrow Sept. 27, 1949 2,483,221 Morrow Sept. 27, 1949 2,645,471 King July 14, 1953

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