US2780894A

US2780894A - Twist drill sharpening attachment for tool grinder

Info

Publication number: US2780894A
Application number: US426157A
Authority: US
Inventors: Clyde K Jensch
Original assignee: Nordberg Manufacturing Co
Current assignee: Nordberg Manufacturing Co
Priority date: 1954-04-28
Filing date: 1954-04-28
Publication date: 1957-02-12
Anticipated expiration: 1974-02-12

Description

:Feb. 12?, 1957 c. K. JENSCH I TWIST DRILL SHARPENING ATTACHMENT F Filed April 28 1954 OR TOOL GRINDER 3 Sheets-Sheet '1 INVENTOR.

.kfevsc Feb. 12, 1957 c. K. JENSCH 2,780,394.

TWIST DRILL SHARPENING ATTACHMENT FOR TOOL GRINDER Filed April 28, 1954 3 Sheets-Sheet 2 INVENTOR.

Feb. 12, 1957 c. K; JENSCH TWIST DRILL SHARFENING ATTACHMENT FOR TOOL GRINDER ,Filed April 28, 1954 s Sheets-Sheet s INVENTOR.

United tates Patent TWIST DRILL SHARPENING ATTACHMENT FOR TOOL GRINDER Clyde K. Jensch, Elm Grove, Wis., assignor to Nordberg Manufacturing Company, Milwaukee, Wis., a corpora- I tion of Wisconsin Application April 28, 1954, Serial No. 426,157

4 Claims. (Cl. 51----96) My invention relates to an improvement in tool sharpeners and is particularly directed to a new and improved apparatus for sharpening twist drill bits.

A major purpose of the present invention is theprovision of a sharpening attachment for twist drills wherein the attachment is so arranged with respect to the peripheral surface of a grinding wheel as to enable an operator properly to sharpen a twist drill.

One object of the present invention is to provide a guiding assembly in which a twist drill bit to be sharpened or surfaced is manually moved to a predetermined position or at a predetermined angle across the moving peripheral surface of one or more grinding wheels.

Another object of the present invention is the provision of a new and improved apparatus for sharpening twist drill bits which can be simply adjusted or regulated to accommodate various sizes of twist drill bits for sharpening.

Another purpose is the provision of a new and improved sharpening apparatus for twist drill bits in which the required cutting surface for the bit is generated automatically by moving the bit through a predetermined path with relation to the peripheral surface of a rotating grinding wheel.

Other purposes will appear from time to time in the course of the ensuing specification and claims.

I illustrate the invention more or less diagrammatically in the accompanying drawings wherein:

Figure 1 is a perspective view of the grinding assembly of the present invention;

Figure 2 is a plan view partly in section of the attachment shown in Figure 1;

Figure 3 is a side elevation view of the attachment shown in Figure 2;

Figure 4 is an end view of the attachment shown in Figure 2 looking toward the grinding wheel shown in Figure 2;

Figure 5 is a plan view of certain supporting elements for the attachment shown in Figure 1;

Figure 6 is a view similar to Figure 3 but showing another operative position of the elements;

Figure 7 is a detail view of the gauging elements em ployed in the present invention;

Figure 8 is a detail view of one of the elements used in the present invention; and

Figure 9 is a side elevation view illustrating the relation of a drill bit to the grinding wheel.

Twist drill bits have a body portion which is formed into a plurality of spiral portions which are separated by spaces or flutes throughout a substantial portion of the bit, The spiral portions terminate in end surfaces which are inclined to the axis of the bit and which merge into the tip of the drill bit. A cutting edge for the drill bit is formed on each of these surfaces. During rotation of the bit, the cutting edge is the leading edge of the surfaces. Each of these cutting edges extends generally from the tip of the drill bit to the outer peripheral surface of the spiraled bit portion.

These drill bits are designed so as to have a particular angle formed between the opposed cutting edges or between the cutting edge and the axis of the bit. It is highly important to maintain this angle intact whenever the drill bit is sharpened. Each of the end surfaces also has a trailing edge or heel. The trailing edges, however, have a smaller angle of inclusion with the axis of the drill bit than the included angle between the cutting edge and that axis. The particular apparatus shown and described herein is particularly adapted to maintain the correct included angle between the cutting edge and the axis of the drill bit and to also maintain the correct included angle between the trailing edge or edges and the axis of the drill bit during the sharpening operation.

Referring specifically now to the drawings and in the first instance to Figure 1, 10 represents a grinding wheel which is mounted for rotation on a frame 10a. 11 is the customary guard for the grinding wheel 10. Any suitable means, such as the belt and pulley assembly 12, may be employed to rotate the grinding wheel. The belt and pulley assembly 12 may be powered by any suitable prime mover, such as an internal combustion engine.

A pair of spaced, generally parallel rods 13 and 14 are formed integrally with a supporting member 15, which is positioned adjacent the peripheral surface of the grinding wheel. The rods 13 and 14 are adapted for reception within correspondingly spaced bores, formed in frame portions 16 and 17. Any suitable means, such as the setscrews 16a and 17a, may be employed to lock the rods at a predetermined position within the bores and thus hold the supporting member 15 in a predetermined spaced relation to the surface of the grinding wheel 10.

Designated generally at 15a are a plurality of roller members which are adapted to receive and support a car riage of a tool holder. The rollers form no part of the present invention. This form of support, which is carried by the grinding wheel assembly, is known to the art and it is illustrated as one form of convenient support for the present attachment invention. The present invention makes use of this form of supporting member in an assembly for sharpening twist drill bits.

A plate 18 is joined to the supporting member 15. The plate 18 has a pair of

spaced bores

19 and 20 formed therein for the reception of a pair of correspondingly spaced

rods

21 and 22 of an adapter 23 for a twist drill bit holder (Figure 8). The adapter 23 includes a sleeve 24 which extends generally in the direction of the peripheral surface of the grinding wheel 10. It may be inclined slightly to the axis of the grinding wheel 10 as will be seen in Figure 2 and also inclined to the plane of the grinding wheel 10. By the term plane of the grinding wheel 1%, I mean that plane which is perpendicular to the axis of rotation of the wheel 10 and that which passes through the middle of the peripheral surface of the wheel.

A twist drill bit holder 25 includes a rod 26, formed unitarily with a plate like portion 25a, and insertable within the sleeve 24. The holder includes a second portion 251: pivotally connected with the rod 26 as at 28 and a generally elongated groove 29 formed therein. The axis of the groove 29 is disposed in the same general plane as the axis of the rod 26. The groove 29 is adapted to receive a twist drill bit 36. An adjusting screw 31 is mounted in one end of the portion 25b and has one end portion bearing against the end portion of a twist drill bit 39 lying in the groove 29. Indicated at 32a is a lock nut to. hold the screw 31 at any desired position of adjustment.

The holder also includes a member 33 which is hingedly mounted on the portion 25b as at 34 to clamp the drill bit 30 in the desired position of adjustment. Any suitable hockingmeans 35- (Fig. '9) may be carried by the member 25b and engageable with the member. 33- to hold the member 33 in its'closed position. The member 33 carries anadjustable abutment 33a (Fig. 4), which cooperates with the groove 29 to hold the bit in any desired position of adjustment.

According to the principles of the invention, the axis of the sleeve 24, axis of thedrill bit 30 and extension of the drill bit 30 with relation to the holder 25 and wheel 1 are soarranged that in the initial or normal position, the axis of the drill bit; is inclined to the plane of the grinding wheel but spaced fromtthe peripheralsurface of the grinding wheel 10. In this. position it is important thatthe drill bit end face opposed to the surface of the grinding wheel has the cutting edge. thereof disposed upwardly and away from the grinding wheel. The drill bit must also be rotated to an initial position such that during rotation about the axis of the sleeve 24 the trailing edge of the end face will first make contact with the wheel to form an angle between the axis of the bit and the line of intersection of the end face with the wheel less than the desired angle of the cutting edge with the axis. Thus, as theholder is rotated about the axis of the sleeve 24, the trailing edge of that end face will first make contact with the peripheral surface of the grinding wheel and the end face will be ground to the correct configuration.

As the holder is rotated upwardly, from the position shown in Figure 1, about the axis of the sleeve 24, the grinding wheel makes progressive contact with the entire end face of the drill hit. As the holder is rotated, and. as material is removed from the end face, the line of intersection between the grinding wheel and the end face moves downwardly on the grinding wheel to a point Where the angle formed between the axis of the drill bit and the line of intersection is equal to the desired angle of inclusion between the cutting edge and the axis of the drill bit. The invention takes advantage of the curvature of the peripheral grinding surface to form both the correct cutting angle of the bit and an end face which falls away from the cutting edge.

Suitable locking means designated generally at 36 and 37 may be employed to maintain the correct included angle between the axis of the sleeve 24 and the axis of the drill bit 39. As shown, the locking means 36 is adapted to lock the holder 25 at the proper position for a /8" drill bit and A drill bit and the locking means 37 may be employed to lock the holder 25 at the proper position for a 9 drill bit. The bores in the plate 25a are spaced a smaller distance apart than the spacing of the pins 36 and 37 so that. only one ofthe pins may be engaged at a single time. The spacing corresponds to a slight angular difference between the axis of the sleeve and the axis of the; bit for the various sizes of bits. For convenience, I have-shown the locking means in the form of pins selectively received within spaced bores formed in the portion- 25a.

The invention includes gauging means for setting up the proper extended position of the drill bit within the holder and to also set up the proper angular position of the drill bit within the holder. The gauging. means l1]? cludes a bracket 33 pivotally mounted upon the portion 2512 as at 39. The bracket includes a portion 4% adapted to extend transversely of the axis of the drill bit 30. Indicated generally at 41, 42 and 43 are individual flute positioners each of which is pivotally mounted upon the transverse portion 40 as at 44. As shown, these flute positioners 41-, 42 and 43 are for use with 91 /2" and drills respectively. As shown, the fiute positioners are=positioned so that when the junction of the cutting edge and peripheral surface of the drill bit indicated at 45 are aligned with the flute positioner, the drill bitisat its proper extended position. Each of the flute positioners includes a lower surface 41a, 42a and 43a. These surfaces are adapted to rest upon the opposite edges'of the flutes in the drill bit. When the drill bit is in its proper extended position, the operator rotates the drill bit until the gauging edge of the particular flute positioner for the particular drill bit contacts the edge at each side of the flute. The drill bit is then in its proper angular position for the sharpening operation.

In use, the flute positioners which are not employed for the particular drill bit are swung out of position and held there by means of any-suitable locking pins or screws 46 (Fig. 9).

After the drill bit is correctly positioned, the flute positioners, along with thebracket, are swung tothe inoperative position about the pivot 39.

Whereas I have shown and described an operative form of my invention, I wish it to be understood that this showing and description is to be taken in an illustrative or diagrammatic sense. only. There are many modifications of the invention which will fall within the scope and spirit of the invention which will be apparent to those skilled in the art. The scope of the invention, therefore, should be limited only by the scope of the hereinafter. appended claims.

The. use and' operation of my invention are as follows:

I disclose a method and an apparatus for sharpening twist drill bits which requires only a simple movement for the sharpening cycle. The twist drill bit is initially positioned with its axis. inclined to the general plane of the grinding wheel. In this initial position the cutting tip or end' of the bit is spaced from .the peripheral surface. of the grinding wheel and the trailing edge or heel of the end surface of the bit is closest to the grinding wheel.

The bit is then bodily rocked about an axis (as defined by the axisof the. sleeve 24) which is located in the same plane as the axis of the bit but inclined thereto and. inclined to the. general plane of the grinding wheel. The bit isrocked in a direction such as to bring the end face of the cutting tip of the bit into contact with the peripheral surface of the grinding wheel.v As the bit first makes contact with the grinding wheel and as it moves through the sharpening cycle it describes generally a helical path of intersection between the end surface and the grinding wheel and grinds the end face to the proper configuration. Thus with a simple rocking movement the operator or person performing, the method can sharpen the bit.

The attachment has been found particularly advantageous in connection with sharpening of twist drill bits with an included angle on the order of degrees between the cutting edges of the bit.

When the attachment is used. the holder is first inserted in the sleeve 24 and a drill bit is inserted in the groove 29. Assuming, for example, that the operator wishes to sharpen a /2. drill bit, he moves the holder about the pivot 28 and engages the locking means 36. The gauge and the. bracket are swung to the position indicated in Figure 2 and theflute positioner 41 is positioned transversely of the groove 29. The adjustment screw 31 is rotated until the drill bit moves to its proper extended position. The drill bit is then rotated to a position where the lower surface 41a of the flute positioner 41 contacts the edge at each side of the flute of the bit.

After thus positioning the drill bit, the operator rotates theholder 25 about the axis of the sleeve 24. During this rotational movement, the end face of the drill bit contacts the peripheral surface of the grinding wheel and grinds the end surface, forming a sharp cutting edge between the end face and the flute. The operator then returns the holder to the initial inoperative position. The clamping means for the drill bit may then be loosened and the bit rotated to present theother face of the drill bit. for asimilar sharpening operation.

I claim:

g 1. A twist drill bit sharpening assembly including a grinding wheel and means for rotating it about a preeyscreoa determined axis, a support positioned adjacent said wheel, a twist drill bit holder including pivotally connected portions, one of said portions including a rod insertable in a sleeve on said support, said sleeve having its axis inclined to the general plane of the grinding wheel and extending toward the peripheral surface of said wheel, the other portion of said holder having a trough adapted to receive a twist drill bit, the axis of said trough lying in the same plane with the axis of said rod, means cooperating with said trough to hold a twist drill bit therein 7 at a predetermined position, means cooperable with said portions for holding the axis of said trough at a predetermined inclination to the axis of said rod and a gauging element pivotally mounted on a bracket and presenting a surface extending perpendicular to the axis of said trough, said surface being adapted for contact with opposed edges of the flute of a drill bit in said trough, said bracket being pivotally mounted on said other portion.

2. The assembly set forth in claim 1 wherein said looking means includes pins carried by said second named portion and selectively insertable in spaced apertures in said first named portion.

3. The assembly set forth in claim 1 wherein said sleeve is removably mounted on said support.

4. The assembly set forth in claim 1 characterized by including a plurality of gauging elements carn'ed by said bracket portion, each element having a surface alignable with opposed edges of a drill bit flute carried by said trough, each of said elements being movable into and out of contacting relation with a drill bit positioned in said trough.

References Cited in the file of this patent UNITED STATES PATENTS 2 9,433 Smith et al May 27, 1884 622,212 Dutton Apr. 4, 1899 643,703 White Feb. 20, 1900 690,389 Chandler M Jan. 7, 1902 743,033 Ridderhof Nov. 3, 1903 1,093,028 Bogart Apr. 14, 1914 1,106,692 Wincrantz Aug. 11, 1914 2,511,055 Ganz June 13, 1950 2,583,159 Swanson Ian. 22, 1952 2,607,172 Roulle Aug. 19, 1952 2,632,983 Kapnick Mar. 31, 1953 FOREIGN PATENTS 236,272 Switzerland June 1, 1945