US2345100A - Drill bit sharpening mechanism - Google Patents

Description

March 28, 1944. El. COTTON 2,345,100

DRILL BIT SHARPENING MECHANISM Filed March 16, 1943 2 Sheets-Sheet l H ll 1 i I l i --l r1 /4 EARL Corn/v INVENTOR I ATTORNEY l6 m: EARL ro/v .INVEN R March 28, 1944. E. l. COTTON 2,345,100

, DRILL B IT SHARPENING MECHANISM Filed March 16, 1945 2 Sheets-Sheet 2 )8 ATTORNEY Patented Mar. 28, 1944 UNITED STATES PATENT OFFICE Earl 1. Cotton, Lucerne, Wash. Application March 16, 1943, Serial No. 479,322

4 Claims.

This invention relates .to drill bit sharpening mechanism and, more particularly, to a sharpening mechanism for dull, detachable drill bits.

While it was conventional in the reshanpening of drill steel having the drill bit integrally formed on one end thereof by forging means, when such conventional steel was displaced by detachable drill bits, the sharpening of such dulled bits has always been accomplished either by grinding or milling operation, but not by true forging practices. An important problem to overcome in resharpening a dull detachable drill bit is the prevention of damage to the usual threaded skirt by which the bit is attached to a drill rod for use. The skirt and the threads formed therein must not be altered or changed in size and shape in any way, and this limitation has so far been insurmountable in previous known attempts to employ forging, since the application of force to the cutting wings or teeth of the drill bit is all too easily applied to this threaded skirt to its damage or reduced utility.

Having in mind the defects of the prior art, it is an object of my invention to provide means for reconditioning worn, detachable drill'bits'by the employment of forging practices in such a way as not to injure or alter the threaded skirt of the drill bit.

Another object of my invention is to provide, in a drill bit shaping mechanism of the type described, a pressure receiving element which will sustain the force applied to the face being reshaped while at the same time preventing the application of that force to the threaded skirt.

A still further and more specific object of my invention is to provide, in a mechanism of the type described, an element for receiving the force applied to the drill bit face which element also serves to extrude the drill bit when reshaped from the reshaping die.

The foregoing objects and others ancillary thereto I prefer to accomplish as follows:

According to a preferred embodiment of'my invention, I dispose in the upper portion of a column a female die which has movable thereto and therefrom a mating male die and the two.

are adapted to be brought together with force to reshape a drill bit placed in a female die.

Specifically, this column has a longitudinally movable bar which fits into the female die to receive the bit being reshaped in a manner to relieve the application of pressure to the threaded skirt of the drill bit. I also include means for longitudinally moving this bar to extrude the drill bit from the female die. In addition, means.

are provided for supporting this longitudinally movable bar during periods when pressure will be applied to it in such a manner that it is directly transferred to the foundation of the column and so as not to damage the mechanism whereby the bar is moved.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood from the following description of the specific embodiment when read in connection with the accompanying drawings, in which Figure 1 is a side viewlof my drill bit reshap-' ing mechanism,-

Figure 2 is a perspective view of a typical drill bit of the type reshaped'in my. device,

- Figure 3 is a plan'view of a female die employed in my invention, 7

Figurel is an enlarged fragmentary sectional View through the female die of Figure 3 and the upper end of its supportingcolumn,

Figure 5 is a vertical sectional view through the male and female die and showing a portion of the cam follower employed in my device,

- Figure 6 is a fragmentary vertical sectional view taken on line 6-6 of Figure 1, r

, Figure '7 is a fragmentary sectional View taken on line 1-1 of Figure 6. a

a A ,drillreshaping mechanism, to overcome the defect hereinbefore enumerated, must have at least two totally distinct characteristics; it must be capable of performing the reshaping opera-v tion with speed and ease, and it also must provide means for protecting the threaded skirt of, the drill bit while reshaping pressure is applied to the drillbit. 7 7

Accordingly, .a preferred embodiment of my invention,=referring to Figures 1 and 2 of the drawings, is constituted by a mechanism which includeszthe foundation foot I0 having rising thereabove'zthe column I2 which terminates in an upper capital or head M, in which is formed the socket l5. =:On either sidethe base H! has. a pairof upstanding lugs or'ears l6 which are drilled at 18 for the reception of bolts to securelyattach the deviceto a suitablefo-undation or base. The column l2 has an axial bore 20 which communicates with the cam receiving slot 22 near the foot of the column. Laterally through the base is opening or slot 24 which inter sects the axisof thecolumn. Mounted in the slot 24'is the cam shaft which has secured thereto the cam 28 that is attached by means of set screws 30, or in any other suitable manner. The cam has a cup 29 in a portion of its face and also includes the wedge face 3|. In Figure 7 the cup 29 is set so that its lowest point in relation to its axis of rotation is in line with the axial bore 20 of the column.

Each end of the cam shaft 26 is supported in the journals 34 which are here shown to be vertically adjustable. Each side of the journals has a tongue 35 which fits into guideways 36 formed in the bracket 38. Roughly the bracket 38 is U-shaped and in its lower portion a screw 40 is threaded to press against the under side of the journal for variable positioning of the journal vertically. A look nut 42 on each of the screws 40 is employed to secure the bolt or screw in its adjusted position. Secured to one end of the shaft 26 is the lever 48 which is employed to rotate the shaft and which has the foot pedal 50 on its outer end. In the drawings the key 52 is employed to secure the lever to the shaft 26. A spring 54 biases the lever upwardly and at one end the spring has a hook engaged in the opening 56 in the lever shank and at its other end a similar hook engages in an opening of the bracket 60 on the column l2. An adjustable stop screw 62 mounted in the lug. 64 on the lever [presses between the lever and a portion of the column to maintain the lever in a predetermined raised position, so that the cam when at rest will lie as desired.

Mounted in the axial bore of the column is the cam follower bar 68 which has a lower rounded face that rests against the cam and on its upper end the boss 12 that is adapted to be inserted into the threaded skirt of a detachable drill lblt. A female die block is fitted into the seat H: on the upper end of the column and is indicated by the numeral [4. The die has a central aperture to accommodate the upper end of rod 68 and its boss. The female die is so formed and shaped that by its contours it will receive and shape a heated drill bit which is presented thereto with force, and in a manner to support the wings of the drill bit against distortion.

The length of the boss. 12 is somewhat greater than the depth of the threaded skirt of the drill bit so that when a drill bit as 18 is on the boss it will be supported as shown in Figure 5, in such a manner that the skirt does not receive longitudinal pressure. The bit 18 has a plurality of radial wings 86 which have an outside gauge diameter somewhat greater than the diameter of the skirt of the bit and which therefore are buttressed as indicated at 82. In sharpening such a drill bit which has become dulled it is important not only to replace and renew the sharp or cutting edges of the wings 80, but also to return the \bit to its original gauge diameter or as near to that as is possible, so that such gauge diameter as has been lost by wear will not. be permitted to detract from the usefulness of the .bit in subsequent drillin operations. The male die 90 is so shaped as to conform. to the desired finished contour of a reshaped bit, and includes a centering pin or boss 96 which serves to engage the drill bit being sharpened at its center water hole 98 or by the usual depression at this point. The pin 96 prevents the inward movement of; metal during the swaging operation and also insures, in those cases where the bit has a central hole, that the water hole is not reduced or closed.

It will be understood that means are employed for bringing the male and female dies together with force to reshape a drill bit placed in the female die. It is preferable, according to my method of operation, to move the male memfber, although it will be obvious that movement could be imparted to the female member and the cam follower' against a fixed or approaching male member and the same result obtained.

Method of operation According to my method of operation, a drill bit is heated to a proper forging temperature and is then placed in the female die 14, so that the buttresses of the wings rest on the sloping shoulders I06 in the die block and support those wings. The boss 12 will be adjusted vertically so that it enters the threaded skirt of the drill bit and supports the head of the bit upon which the wings and teeth are being formed and because of its length being greater than the depth of the socket of the bit no pressure can be applied to the threaded skirt. The male die, in the case where it is the movable element, is brought into contact with the face of the bit and into association with the female member with force, so that the heated metal will be pressed and swaged to the configuration of the dies. The metal of the wings will be swaged outwardly and will also be provided with a cutting edge. When the forging operation is complete, and the operator wishes to remove the forged drill bit from the female die, he applies pressure to the lever 48', usually with his foot, and against the force of spring 54 to rotate the cam shaft 26 and to cause the wedge or cam portion 3| to be interposed under the rounded end of the cam follower bar 68. This will extrude the drill from its seat in the female die. g 7

It is to be noted that during the forging operation. some force is applied to the cam follower along its longitudinal axis. This force is then transferred to the cam at its lowest point and in a manner that avoids applying it to the shaft off centerv but directly axial of the cam shaft. This can be seen in Figure '7. This force is then transferred laterally to the journal 34 and thence to the frame or base of the column. When it is necessary to adjust the height of the boss,v rather than doing so by readjusting the relation of the camto the cam follower, the camshaft and cam are raised or lowered. vertically through adjustment of the bearings in. their supporting guides without changing the desired relation between the camand cam follower. In this way no unusual stresses or strains are applied to the cam shaft or the cam to the cam follower bar.

Although I have shown andv described certain specificembodiments of my invention, I am fully aware; that many modifications thereof are possible. My invent-ion,v therefore, is not to be restricted, except insofaras is necessitated by the prior art and by the spirit of the appended claims.

I claim:

1. In a drill bit reshaping. mechanism in which a bit is pressed into a female die and a member is pressed against the bit to extrude it from the die following the shaping. operation, means for supporting and moving said member comprising: a shaft journaled for rotation laterally of the axis of the bit to be pressed, means for rotating said shaft on occasion, a cam on said shaft on the axis of said bit to !be pressed and a cam follower bar between said cam and the boss, said cam having a cupped'face adapted to receive an end of said cam follower bar in a manner to transfer force applied thereto directly to the rotatable shaft and its journals.

2. A reshaping mechanism for detachable drill bits of the type having winged teeth on the cutting face and a threaded skirt therebehind, which mechanism comprises: a column having lower journals on either end of a lateral passage, said column also having an axial passage intersecting said lateral passage, a shaft in said journals, means for rotating said shaft on occasion, a cam on said shaft having a cupped face directed upwardly when the cam is in the at rest position and including a cam wedge to one side of its axis of rotation, a cam follower bar slidably movable in the axial passage of said column and including an upper boss, a female die on said column and having a central aperture for the reception of the boss on the cam follower bar, and a male die to press a bit in said female die to reshape the same.

3. A reshaping mechanism for dulled detachable drill bits of the type having a threaded skirt, which mechanism comprises: a female die shaped to receive and support the wings of a bit to be sharpened, a male die to press the winged face of a drill bit in said female die to shape the cutting edges and swage the drill Wings radially outward, a boss in said female die to support the bit in a manner to prevent the force of the pressing operation upon the winged face being applied to the threaded skirt of the drill bit, and means for forcing said boss outward in said female die to extrude a sharpened bit following the forming operation.

4; In a detachable drill bit reshaping mechani'sm in which the bit being sharpened has a threaded skirt and is pressed into a femal die, a boss to fit into the threaded skirt of the bit 15 being sharpened to support the bit during the re-

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