US2730849A - Drill bit grinding fixtures - Google Patents

Description

Jan. 17, 1956 J. v. NOVAK 2,730,349

DRILL BIT GRINDING FIXTURES Filed Sept. 20, 1952 3 Sheets-Sheet l Inventor JAMES M NpvAK Jan. 17, 1956 J. V. NOVAK DRILL BIT GRINDING FIXTURES I5 Sheets-Sheet 2 Filed Sept. 20, 1952 Inventor JAMES V. NOVAK J. V. NOVAK DRILL BIT GRINDING FIXTURES Jan. 17, 1956 3 Sheets-Sheet 3 Filed Sept. 20, 1952 Inventor JAMES V. Novm han United States Patent DRILL BIT GRINDING FIXTURES James V. Novak, Ber-Wyn, Ill.

Application September 20, 1952, Serial No. 310,640

1 (Ilaim. (Cl. 51-219) This invention relates to drill bit grinding fixtures. It utilizes a novel and unique control linkage, producing high accuracy and efiiciency at minimum cost.

It is a primary object to provide a fixture which allows either fiat or hollow grinding of a well-balanced tool face, with rapid or slow cutting characteristics, as desired.

A further object is to compensate for gradual changes of grinding wheel diameters.

Another object is to minimize irregular wear of grinding wheel surfaces.

Still other objects, and pertinent features and advantages of the new device, will be mentioned in or will appear from the detailed description of a simple embodiment, which follows. In this description and in the drawing illustrating the same specific details are disclosed, for full explanation of the illustrative example. It should be understood that the invention can be embodied in modified forms, which are likely to occur to persons skilled in the art upon a study of the disclosure. The exact scope of the invention will be defined by the claim appended hereto.

In the drawing:

Figure l is a perspective view of a simple embodiment, in operative position to grind the face of a drill bit.

Figure 2 is an enlarged side view of the drill bit and the mechanism directly connected therewith, in the new fixture. Certain parts are omitted while others are shown in section, in a plane indicated by lines 2-2 in Figure 1.

Figure 3 is a partial view of the same device in a different operative position thereof. The view is taken in the same plane as mentioned with respect to Figure 2.

Figure 4 is a plan view of the device.

Figure 5 is a motion diagram, indicating how the device, seen in a view like that of Figures 2 and 3, moves from the position of Figure 2 through that of Figure 3 into a final position.

Figure 6 is a further motion diagram, indicating how the center of the tip of the drill bit, seen in an axial direction, moves over the surface of the grinding wheel, during the motion illustrated in Figure 5.

Figure 7 is a detail section, taken along lines 7-7 in Figure 2.

Figure 8 is another detail section, taken along lines 8-8 in Figure 2.

Figure 9 is a detail view taken along lines 9-9 in Figure 2; and

Figure 10 is a detail section, taken along lines 10-10 in Figure 2.

The device is mounted adjacent a grinding wheel 11, upon a suitable bracket or support 12 to which it may be secured by clamps 13 or the like. A blunted, chipped or generally damaged drill bit 14 lies in an open-top channel 15 of V-shaped cross-section, which is supported and guided by linkage generally shown at 16. This linkage forms an important part of the invention. It is in turn supported and guided by a frame 17, which also serves to steady the channel and the drill bit lying therein. For

2,730,849 Patented Jan. 17, 1956 ice the latter purpose the channel is provided with elongated cheeks or flanges 18, depending from the upper edges of the trough 15 and having sliding fit with the upstanding walls or checks 19 of the frame 17. The bottom 20 of the frame is adjustably secured to a base plate 21 for the entire fixture, for instance by a screw 22, nut 23 and spring washer 24.

As shown in Figure 4 the base plate 21 has a straight side adjacent the grinding wheel, which is best oriented parallel with the grinding surface. The frame 17 is secured to the base plate at an angularity matching the angle of the bit to be ground. For standard drill bits this is 33 /2 degrees, approximately as shown in Figure 4; and it is desirable to cut off one side of the base plate at this standard angularity, as shown, thereby facilitating the re-establishing of the standard angularity. The device can be installed in front of a cylindrical wheel surface as shown, or alternately in front of a flat wheel surface, at similar angularities. The front end of the channel is cut off diagonally so that it is normally parallel with the grinding surface.

The linkage 16 substantially consists in two straight links 25, 26, having slightly different length, for reasons to be explained shortly. Each link 25 and 26 has a lower end secured to the frame 17 at substantially the same elevation above the bottom 20, by pivot pins 27, 28 respectively. At a higher elevation there are additional pivot pins 29 and 3G, securing the upper ends of the links 25, 26 to the flanges 18 of the channel 15, at a shorter distance from one another than is provided between the lower pins 27, 28. The ends 31 of the upper pins 29, are peened flush with the outside surfaces of the channel flanges 18, in order to avoid interference with the frame walls 19, which guide the channel.

The links 25 and 26 are preferably made as short as possible in order to minimize bending moments. In this connection it will be noted that both links are made as channel members. The flanges 32 of these channel members are basically used to provide bearings for the pins 27, 28, 29 and 30. Additionally, the two flanges of each link 25 or 26, reinforced by the intermediate web 33, provide adequate strength against the stresses encountered in the operation of the fixture. The links can be made particularly short by cutting off upper parts of each web in form of a V, as shown at 34 in Figures 8 and 9. In this manner the short, reinforced links 25, 26 and the bottom of the channel 15 are allowed to swing relative to one another and to collapse to an adequate degree, as noticeable mainly from Figure 2. No loss of strength is incurred, the web 33 of each link being cut off only between the flanges 32 and the entire link being suitably reenforced by the web and flanges at the two side edges, where such reenforcement is required.

The drill bit 14 is held, against axial pressure applied thereto by the grinding wheel, by a sleeve 35. This sleeve substantially surrounds the channel 15. It can be secured thereto by a thumb screw 36, threaded into a part of, or washer within, the sleeve 35, below the channel 15. Pressure is thus applied against the bottom of the channel 15. The device can be adjusted to various lengths of drill bits by sliding the sleeve 35 along the channel 15. Further, a fine adjustment is provided. Each end of the sleeve 35 has an ear 37, depending into the channel 15; and a screw 38 is threaded in these cars, in a direction parallel with the channel. The head 39 of this screw will properly abut against the shank end of the drill bit. The other end of the screw has an adjustment knob 40 secured thereto.

Proper position of the drill bit is additionally enforced by a finger 41, made of spring steel or the like. This finger is pivoted to the top of the sleeve 35 by a rivet 42. When properly oriented along the channel 15 the finger 7 base plate 21, while the front edge of that plate is set parallel with the grinding surface. The drill bit 14 to be sharpened is then placed in the channel 15, with its rough edge about one-eighth to one and one-half of an inch in front of the front edge of the channel. The required projection of the bit in front of the channel depends mainly on the exact installation of the support bracket adjacent the grinding wheel, and the exact amount of steel to be removed.

Next, the slide 35 is moved up to the shank of the bit, and fastened by turning the thumb screw 36. Finger 41 is then swung in place and fastened at 43. A final fine adjustment of the drill bit, toward the wheel, can be made by turning the knob 40 of the screw 38. 1f the drill bit has a pointed shank end, care must be taken to avoid lifting this end from the channel. The slot in the head of'thescrew 38 may have to be placed in vertical position at the end of the adjustment, or some other obvious precaution may have to be taken, when drill bits of relatively large or relatively small size are handled, as compared with that size which brings the point of the shank end to the exact center of the screw.

In actual'operation, the user of the fixture will generally hold the free end of the channel in his left hand, with his left thumb on the finger 41 and his right thumb on the drill bit between the front and back ends. The starting position of the channel is that wherein the free end is at a low point, due to the weight of the channel and drill bit. This is shown in Figure at 14A. The operator now lifts the free end of the channel, with his left hand, until it reaches the position 14-G. As a result the linkage 16 causes the tip of the drill bit to move downwards. In the side view of Figure 5 the projection of this movement appears as a curve gradually approaching the grinding surface; in the axial view of Figure 6 it appears as a curve a to g sweeping transversely over the grinding surface. The curve lies in the plane defined by the orientation of the frame walls 19, which guide the channel 15. At 14A the drill bit is out of contact with the wheel if the support bracket 12 and baseplate 21 thereon are properly positioned. Contact is made adjacent B or C. Steel is then removed from the worn face of the bit, by the rotating grinding wheel. Between the approximate limits C and D such removal takes place back of the cutting edge of the bit; adjacent D or E the edge itself is finished. This change is gradual. It is obtained by the turning of the bit, incident to the lifting from 14-A to 14-G.

This change tends to produce a face of somewhat convex form, like a cylinder segment that is, a drill bit edge (in Figures 2 and 8, finger 41 has 4 this subframe. slots 48 in the frame walls 19. The adjustment screw 47 is secured against displacement due to vibration, by a compression spring 49 surrounding the shank of this screw and pressing against tabs 51 51, on frames '17, 46 respectively, wherein the screw 47 is held. Upon an adjustment at 47, the extension, location and exact shape of the curve a g is modified but the general character of the motion and action remains the same as described; the shape of the ground bit however being changed, minutely but significantly.

The linkage adjustment 45 can also be used to compensate for the gradual wearing off of a cylindrical grinding wheel surface Minor adjustments of the screw 47 are generally sulficient for this purpose. It will be noted that such adjustments can be made very readily; no pr eparatory loosening of nuts or more complex operations are required.

The wearing of the grinding wheel is not only compensated by this simple adjustment; it is also reduced and balanced by the transverse sweep of the curve a g. irregular wearing and frequent need for truing are practicsily eliminated in this manner.

As a result, excellentdrill bit faces can be produced, often with better quality than originally provided by the drill bit manufacturer. This can be achieved with great economy as to the grinding fixture, and further economy as to the wearing off of the grinding wheel;

The manufacture of the new fixture is simple. Stainless steel sheeting of uniform gauge thickness can be used for all special parts 15, 17, 21, 25, 26, 35 and 46. The material need not be machined; punching and bending is suthcient for practical purposes.

I. claim:

A drill bit grinding fixture comprising a channel; a pair of links of different lengths having their upper ends pivoted to the channel at points spaced from one another longitudinally of the channel, and a base pivoted to the lower ends of the links at points more widely spaced from one another, longitudinally of the channel, than the first mentioned points are spaced; each link substantially consisting in a short channel member the flanges of which are pivoted to the channel and base, and the web of which channel member has a substantially V-shaped recess, the cross section of the channel being similarly substantially V-shaped.

References Cited in the file of this patent UNITED STATES PATENTS 183,798 Champlin Oct. 31, 1876 368,356 Root Aug. 16, 1887 523,897 Kenyon July 31, 1894 571,336 Budlong Nov. 17, 1896 589,398 Ruldolphi Aug. 31, 1897 1,020,860 Vauclain Mar. 19, 1912 1,052,968 Rodgers Feb. 11, 1913 1,063,391 Rodgers June 3, 1913 2,074,733 Porter Mar. 23, 1937 2,152,729 Char-tier Apr. 4, 1939 2,248,263 Wiiliams July 8, 1941 2,394,839 Bowman Feb. 12, 1946 FOREIGN PATENTS 4,554 Great Britain Apr. 13, 1885 199,268 Great Britain June 21, 1923 It is held slidably by horizontal guide

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