US2403651A - Method of and apparatus for making bits - Google Patents

Description

July 9, 1946; F. L. FULKE 7 METHOD OF AND APPARATUS FOR MAKING BITS Filed Dec. 6, 1943 2 Sheets-Sheet 1 irrmm frs.

July 9, 1946. F. L. FULKE METHOD OF AND APPARATUS FOR MAKING BjITS I Filed Dec., 6, 1943 2- Sheets-Sheet 2 INVENTOR.

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Patented July 9, 1946 METHOD OF AND APIiglgATUS FOR MAKING Frank L. Fulke, Terre Haute, Ind.

Application December 6, 1943, Serial No. 513,067

7 Claims. (01. 76-108) The present invention relates to a method of and mechanism for forming coal cutting bits or other small steel parts in multiple. Theiprimary objects of the invention are as follows:

1) To provide a method of accurately forming four-point coal cutting bitslike the one illustrated in Fig. 8 of my Patent No. 2,328,134 in. multiple at low cost.

(2) To provide a method of accurately forming four-point coal cutting bits like the ones illustrated in Figs. 1 to 4 inclusive of my Patent No. 2,328,134 in multiple at low cost.

. (3) To provide a method by which other small uniform metal parts may be accurately formed in multiple at low cost.

I factory made and hardenedcoalcutting bitshav v ing a plurality of usable cutting points, the bit be} ing discarded after use, without any attempt to (4) To provide for accurately forming a' multiplicity of such bits in one press stroke without any waste of steel between them or around their-sides, and without subsequent trimming.

(5) To provide mechanism operable to carry out the above-stated objects.

Further objectives of the invention will become apparent from the descriptions and drawings hereof.

To th accomplishment of the above and related objects my invention may be embodied in the forms illustrated, attention being called to the fact, however, that the drawings are illustrative only and that change may be made in the specific constructions illustrated and described. Obviously the advantages of the method and mechanism revealed may be readily adapted to the economical and accurate production of other small parts than coal cutting bits.

In the drawings,

Fig. 1 is a front elevation of one form of bit to the manufacture of which my method is adapted;

Fig. 2 is a side elevation thereof;

Fig. 3 is an end elevation thereof;

Fig. 4 is a view similar to Fig. l, but showing a, somewhat difierent form of bit;

Fi 5 is a side elevation of a still further form of bit which may be made by my method;

Fig. 6 shows a bar of steel which has been formed by my method into a plurality of bits like those illustrated in Fig. 5;

Fig. 7 shows a square bar of steel which has been formed by my method into a plurality of bits like those illustrated in Figs. 3 and 4;

Fig. 8 is a plan View of a forming mechanism useful in practicing my method, in open position;

Fig. 9 is a section taken on line AB of Fig. 8;

Fig. 10 is a plan view of the forming mechanism in closed position;

Fig. 11 is a section taken on line C--D of Fig. 10; and v Fig. 12 is an elevation of the inside face of a confining die used in such mechanism.

In the coal cutting art a great many efforts have been made to provide the mines with small resharpen the points. The number of such bits required at a mine runs into large figures, sometimes a thousand or even two thousand a day. Obviously then a prime requirement is that the bits must be chea enough to permit advantageous use in competition with the usual mine bit of A9." x 1" steel which is resharpened twenty or thirty times at low cost, at the mine.

Factory bits in present widespread use fall into two general classifications; drop forged bits and bits sawed from bar stock. A considerable variety of each has been tried and several of each are in widespread use. Neither type represents the ultimate to be desired in extreme low cost and accuracy of large production. The forged bits require elaborate and costly die maintenance, else the bits get out of dimension, since the hard steel causes the dies to wear fast. There is also a bad flat chopped edge where the bit is punched or trimmed from the flash, and the steel wasted in this method runs from about 25% at best to as high as 50% which is a very bad factor during the war emergency when steel is so vitally needed. The segmented bits also waste steel by the amount cut by the saw blade or the abrasive wheel, and the cost of the saws or the abrasive wheels is a very high factor of production cost. In the sawing methoda bar of steel is sawed at close intervals at a very acute angle, in order to obtain sufficient length of the bit piece, which is not conducive to proper strength immediately rearward of the active cutting point which so frequently snaps oif.

In my Patent 2,328,134 I believe that I have revealed a bit with just about the ultimate in coal cutting power per ounce of steel, or per piece production cost, the steel cost and the bit forming cost being of course the two largely controlling factors in the cost at which the coal mines can employ them. My bit has four successively usable strong yet sharp cutting points, every point bein usable regardless of mutilation of any or all of the others. It has a heel strength behind each point far beyond any tendency for a point to snap off. It possesses unique and extraordinarily desirable qualities for cooperation with a cheap and positive clamping means.

Herein, I disclose a practicabl way of producing the types of bits described in my said patent,

in large quantities at lowest cost.

My bits of Figs. 1 to 4 inclusive could not be economically commercially produced as drop forgings or as upset forgings or by any other manner of forging familiar to me. B the time all the necessary drafts were added to permit employing forging methods the resultant bits would not be usable for coal cutting without a prohibitive amount of grinding or machining to remove those drafts from each bit.

Production of these bits by casting them in sand molds would be commercially impractical because of the drafts and also the prohibitive cost of the steel casting process as applied to small pieces. Then too, steel will not cast into the clean-cut sharply defined cutting points, and edges, and shoulders for clamping the bits that I must have.

I know of no method by which such small parts can be accurately and cheaply produced other than the one to be described herein. If the metal were melted zinc alloy such parts could be made by the die-casting process. But nobody has ever found a way to successfully die-cast steel parts. Hard alloy steel must be employed in making coal cutting bits.

Essentially my method comprises feeding a hot piece of steel into a die organization, then confining it, then squeezing it into the desired form which will be a form dictated by the confining means plus the squeezing means. The result is the same as if I were able to inject the steel inmolten form as in die casting, for it does the same thing as in die casting when it assumes the configuration dictated by the confining means plus the movable squeezing means.

In my method of making four-point coal cutting bits I propose to use ordinary bar steel, preferably square, although round bar steel might also be favorably employed. I propose to confine the steel bar I between a pair of confining dies, 2, 3, then apply pressure upon it by pressure dies 4, 5, 6,1, and others, to force the bar to assume the shape of the ends of the pressure dies.

The pressure dies are square in section and their noses are beveled as at 8. Their shanks 9 take into suitable sockets Ill and may be held therein by set screws l I.

Certain of the pressure dies are slidable in apertures l2 pierced through dies 2 and 3, while others of said pressure dies are slidable in apertures l3 which are defined when dies 2 and 3 are brought together.

The inner faces of dies 2 and 3 are formed so that each has cooperative triangular grooves l4 and cooperative triangular grooves l5 at right angles to grooves l4, so that when dies 2 and 3 are closed grooves l5 form a square trough slightly larger than the steel bar I, and grooves l4 form square apertures 13 slightly larger than the pressure dies slidable therein. A block 46 closes the upper end of the groove in the die 3 and, when the dies are closed, enters the groove l5 ofthe die 2 to provide an abutment for the upper end of the work.

In Figs. 9 and 11 I have shown a feeding device l6 provided for the purpose of interposing heated steel bar I between dies 2 and 3 while they are separated. When dropped into the open upper end of device Hi the steel bar will be guided and supported by a portion ll of said device until its lower end rests on end wall I8 of groove 15 and portion ll will continue to support it until the dies have almost closed together upon it. The feeding device I6 has lugs 19 perforated to slide upon vertical rod 20 which is screwed into die 2. A bracket 2| supports a pin 22 carrying an arm 23 operable to lift pin 24 slidably received in a slot 24' formed in arm 23. An actuating pin 25 suitably located on a wedging element to be described later will move against extended portion 25 of arm 23 to press it down just before dies 2 and 3 close, and so portion ll of feeding device I3 is quickly jerked upwardly out of the way. So small a time element is left then, that steel bar I will stand on its lower end until the dies 2 and 3 have closed upon it.

Pressure rams 4, 4' are carried by a head 2'! and dies 5, 5' are carried by a head 28.

A plurality of pressure dies 1 (only one of which is shown) are carried in a vertical series by a head 29 and a similar series of dies 6 are carried by a head 323. The dies 6 and I are arranged in horizontal planes vertically offset from the planes of the dies 4 and 5, each die 6 mating with its corresponding die 1.

Each head 21, 28, 29, 36 has welded to its rear side a wedge-shaped piece 3!.

In order to better explain the dies let us say that the confining dies 2, 3 each move inch toward each other from their open position, to close their faces together. Let us say that all the pressure dies 4, 5, 6, l and the similar pressure dies in line below them will move 1 /2 inches to bring the points of their noses almost, but not quite, together.

In order to provide for the movement of th pressure dies four wedges 32 attached to the head of a powerful press have wedging surfaces 33 cooperating with wedge pieces 3!, so that when the head of the press descends a lateral movement of 1 inches of all the heads 21, 28, 29, 3!] toward a common center will be caused.

Cup-shaped steel casting 35 has vertical surfaces 34 against which wedges 32 thrust while their downward pressure is transferred to the lateral pressure necessary to shove the heads.

It is to be understood that suitable conventional guide pins or other guiding elements are provided to accurately confine the movement of the confining dies as well as the pressure dies to their proper lines of motion. I do not show them in order to avoid complicating the drawings, since they require no more than the application of ordinary mechanical skill.

The confining dies 2, 3, and all the heads 21, 28, 29, 3B are slidable upon the floor of casting 35, which is perforated at 39 to permit the steel bar to drop through after pressin it.

Powerful springs 36 attached to casting 35 will retract all the heads 21, 28, 29, 33 to their open positions and springs 3'! connecting the confining dies 2, 3 to their respective heads will cause these dies to retract to their open positions when their heads retract. 1

Heads 29 and 3B differfrom heads 2? and 28 in order to provide means for closing dies 2, 3 together and locking them tightly closed while the pressure dies are squeezing the steel bar. This may be clearly understood from Figs. 8 and 10. The head 29 has apairof arms 40, 4| and the head 33 has a similar pair of arms 49', 4|, each pair of arms being spaced apart a distance equal to the thickness of the pair of dies 2, 3 when they are tightly closed. These arms terminate in outwardly flared surfaces 42, 43' and 42', 43', respectively. When the heads 29, 39 move toward each other the camming surfaces 42, 42 will engage the die 3 while the surfaces =33, 43' will engage the die 2 to draw the dies together. The movement of the heads 29 and 30 then continues to bring the parallel inner walls 44 and 45 of the arms 40 and 4| and the parallel inner walls 44' and 45' of the arms 46' and 41' into gripping engagement with the rear surfaces of the dies 2 and 3 in the manner of a vise, before the pressure of the forming die acts upon the steel bar.

' It will be seen that some of my forming dies move-with a pair of heads on one line and some of them move With another pair of heads on another line at right angles to the first-mentioned line, andthat'th'etwo said linesintersecta the longitudinal axis of the steel bar. This arrangement will transform the steel bar into a bar of formed four-pointed bits as illustrated in Fig. 7, which are bits like those of Fig. 4. Bits like'those illustrated in Figs. 1 to 3 could be made in this manner by employing round bar stock-and-making grooves I 5 half round. The dies as I have illustrated them will at one press stroke completely form four of the four-pointed bits. However, it may be readily understood thatby simply increasing the number. of die pairs, any reasonable number of such bits may be formed at one stroke.

It is especially to be noted that there i no flash or Waste of steel around these bits as with drop forgings, so there will be no trimming operation or steel loss required to separate the pieces from flash steel. A simple sh'ear'at the thin point 38 will separate the bits of each group.

It will also be noted that the cross-sectional dimensions of the apertures I 2 and I4, and of the steel bar, and the angularity of the noses of the pressure dies, may all be calculated to provide that, when the pressure dies have squeezed the steel bar thin as at 38, the displaced metal will exactly form itself to the shape of the nose of each of the pressure dies and to the walls of the" associated aperture, so that the particular configuration of bits like those illustrated in Figs. 3 and 4 will be obtained. The peculiarly formed shoulders thus defined are of importance with regard to clamping one of the bits in a coal cutting chain link.

Bits .like those illustrated in Figs. 5 and 6 are formed similarly but do not require one of the pairs of heads, since they will require only one pair of heads movable upon one line intersecting the longitudinal axis of the steel bar. I preferably dispense with heads 21 and 28 in order to avoid the perforated square openings l2 through die 2 and 3. It will be easier to form the triangular grooves M which will provide a square aperture when the dies close.

Considering Figs. 8 and 9, it will be apparent that I may at will make the few adjustments to my mechanism which wil1 be necessary to produce a bar of formed four-pointed bits like those illustrated in Fig. 6. I simply substitute for forming dies 2, 3 another pair of similar dies which do not have perforated apertures l2, and remove the pressure dies 4, 4' and 5, 5.

Attention is called to the fact that my drawings are to some extent merely illustrative and not exact working drawings for dies for commercial operation. For example, I have illustrated the confining dies and the four heads which carry the forming dies, as being retractible, after the completion of the press stroke, under the influence of springs. Such springs would hardly sufiice. There should preferably be a mechanical linkage operable by upward movement of the head of the press, to positively retract these elements. Also my illustrated wedge method may preferably be supplanted by a knuckle mechanism operable to powerfully thrust the four heads toward a common center as the press head comes down. Such modifications require only the exercise of mechanical ingenuity, and nothing of invention, therefore I feel it in- 6 advisable to complicate my drawings and description by showing them. a

- -I claim:

.1. The method of forming four-pointed coalcutting bits which comprises the steps of confining a steel bar of uniform cross section, apply ing forming pressure to opposite surfaces of said bar'at each of a plurality of spaced points along.

its longitudinal axis to flowthe metal of said bar'laterally of its axis while producing opposing, parallel transverse grooves in said bar at each of such points, releasing the bar, and cutting said bar at the base of each pair of such grooves. 2. In' a method of forming four-pointed coalcutting bits, the steps of confining a steel bar of uniform cross section, and applying forming pressure to opposite surfaces of said bar at each of a plurality'of spaced points along its longitudinal axis to flow the metal of said bar laterally of its axis while producing opposing, parallel transverse grooves in said bar at each of such points, and while confining the flowing metal to produce, at each end of such groove and on each side thereof, a flat surface retreating sharply from the groove end toward the axis of such bar.

3. The method of making multi-pointed coal cutting bits without Waste from bar stock which comprises the steps of applying pressure to such,

bar stock simultaneously at oppositely aligned regions and on a line perpendicular to the axis of such stock to reduce the thickness of such stock, in the region of pressure, to a low value, While flowing the metal displaced by such reduction of thickness laterally to increase the width of such bar stock symmetrically on opposite sides of such axis and on opposite sides of such region of pressure application, and while confining the flowing metal to produce, at each transverse end of such region of reduced thickness and on each side of such region, a fiat surface retreating sharply from such transverse end toward the axis of such stock, and subsequently segmenting such bar stock at such region of reduced thickness.

4. The method of making multi-pointed coal cutting bits without waste from bar stock which comprises the steps of applying pressure to opposite surfaces of such bar stock simultaneously in each of a plurality of longitudinally-spaced planes normal to the axis of such stock to reduce the thickness of such stock, in each of said planes, to a low value, while flowing the metal displaced by each such thickness reduction laterally to increase the width of such bar stock symmetrically on opposite sides of such axis and on opposite sides of each of such planes, and subsequently segmenting such bar at each such region of reduced thickness.

-5. Apparatus for use in making four-pointed cutter bits from bar stock, comprising a die formed to provide a cavity whose cross-sectional contour substantially correspond with that of such bar stock, said cavity being intersected by a plurality of pairs of aligned slideways, each such pair being disposed on a common axis perpendicular to the axis of said cavity and the respective pairs being axially spaced along said cavity, the intersections of said slideways with said cavity producing transverse enlargements in said cavity, wedge-nosed plungers reciprocably mounted in said slideways, and means for moving said plungers simultaneously toward the axis of said cavity and into close proximity to each other.

' of said cavity and into close proximity to each other.

'7. Apparatus for use in making four-pointed bits from bar stock of quadrangular cross section, comprising a die formed to provide a cavity of quadrangular cross section conforming to that of such stock, said cavity being intersected by a pair of aligned slideways, said. slide- Ways being quadrangular in cross-section, being disposed on a common axis coinciding with a diagonal of said cavity and perpendicular to the axis of said cavity, and each having a diagonal lying in a plane perpendicular to the axis of said cavity, a plunger reciprocable in each of said slideways, each of said plungers being formed with a wedge-shaped nose with its edge parallel with said diagonal of its slideway, and means for moving said plungers simultaneously toward the axis of said cavity and into close proximity to each other.

FRANK L. FULKE.

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