US2874520A - Manually operated grinding attachment - Google Patents

Description

Feb. 24, 1959 v. N. HOERST MANUALLS} OPERATED GRINDING ATTACHMENT 10 Sheets-Sheet 1 Filed May 27', 1957 m mii Feb. 24, 1959 v. N. HOERST .MANUALLY OPERATED GRINDING ATTACHMENT 10 Sheets-Sheet 2 Filed May 27, 1957 After/1g I Feb. 24-, 1959 v. N. HOERST 2,374,520 MANUALLY OPERATED GRINDING ATTACHMENT Filed law 27; 1957 10 Sheets-Sheet "3 Feb, 24; 1959" r v. N. HOERST 2,874,520

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MANUALLY OPERATED GRINDING ATTACHMENT Filed May 27, 1957 7 1O Sheets-Sheet '10 zhven'io/ Valenfme lYm/(o/as l/oe/zsf Aomgy MANUALLY OPERATED GRINDING ATTACHMENT Valentine Nickolas Hoerst, Cincinnati, Ohio Application 27, 1957 Serial No. 661,665 5 Claims. (Cl. 51-219) This invention relates to apparatus for holding and grindingcutting tools for grinding the cutting edges ablehowever that the surface be convex to provide more metal adjacent the cutting edge to reinforce the edge and conduct away heat generated in cutting. In a drilling bit for instance, it is highly desirable that distance from the conical plane formed by rotating the cutting edge, to the ground surface increaseuniformly and gradually from the cutting edge to the trailing edge of the surface and further that this distance which is called the clearance be uniform along any radial line on the'surfacerdrawn from the point of the bit. Thepreferable clearance for a bit varies with the metal to be drilled, and in general the softer the metal the greater the clearance should, be.

It is believed that this convexly curved ground surface which greatly, increases the'strength and life of the cut-. ting edge has only been obtained by careful and skillful hand grinding and by the use of highly complicated apparatus in which the surface is ground from the trailing edge to the cutting edge, a procedure which is unsatisfactory in that it tends to chip the cutting edge.

.It is the object of this invention to provide apparatus for holding and guiding a machine tool for sharpening thereof against a. rotating grinder whereby'at least one of the. surfaces forming the cutting eclge'is ground to a conv exly curved surface thus providing-a cutting edge of {maximum strength and life. 7 v r It is a further object of the invention to provide apparatus for holding and guiding a machine tool for sharpening thereof against a grinder whereby a. cutting edge may be formed having anydesired angle relative to the axis of the tool and at least one of the surfaces forming the cutting edge may be ground to a curved surface having any desired clearance.

Broadlythe invention comprises a frame, a forward block mounted on said frame having a pair of recesses extending transversely therein, a rearward block having a concavely curved Cavasurfaceextending angularly and transverselythereona rigid cutting tool carrying support a rocker member fixed forwardly to said support having a pair of jaws for rocking engagement with said recesses and a cam follower fixed rearwardly to said support arranged to traverse said cam surface.

' The invention w'illbe described with relation to the accompanying drawings in which Fig.1 is a side elevation partly in section of a device in accordance with the invention.

Fig. 2 is a front end elevation of the device.

' Fig. 3 is" a sectional elevation taken along line 3-3,

of Fig. 2.

eotFiglr 2,874,520 Patented Feb. 24, 1959 Fig. 10 is a partial plan view of the device showing a cutter in grinding position.

- Figs. 11 and 12 are elevational views showing a cutter in position for right hand grinding.

Fig. 13 is a partial plan view of the apparatus showing a cutter in left hand grinding position.

Fig. 14 is an elevation view of the apparatus shown in Fig. 13.

Fig. 15 is a rear eievation view of the apparatus.

Fig. 16 is a sectional elevation of the cam block showing the mounting thereof and a portion of the cam follower.

'Fig. 17 is a perspective view of an upper slide member with cam and rocker blocks thereon.

Fig. 18 is a perspective view of a side plate for the rocker block.

Fig. 19 is a perspective view of a positioning spring for the rocker arm.

Fig. 2D is another perspective view of a side plate for the rocker block.

Figs. 21, 22, 23 and 24 correspond to Figs. 17, 18,

'19 and 20 respectively but with parts arranged for left hand grinding.

Fig. 25 is an elevation view of the rocking assembly for right hand grinding.

Fig. 26 is a bottom plan view of the structure shown: in Fig. 25.

Fig. 27 is an end elevation of the structure shown in Fig. 25.

Figs. 28, 29 and 30 correspond to Figs. 25, 26 and 27 respectively but with parts arranged for left hand grinding.

Fig..31 is a front elevation of the tool carrying support may be provided in the base plate to secure the stud Fixed upon the stud is a lower elongated member 13 upon which is slidably mounted'an upper slide 14. It will be observed that members 13 and; i 14 are keyed together to provide longitudinal reciprocat ing movement of the upper slide 14. 7

in adjusted position.

Reciprocating movement is applied to slide 14 by 13 and slide 14 intermediate the ends thereof as by a T-bolt 19 and nut 18, such stops 17 being mutuallyengageable as shown.

Fixed to the forward end of s1ide'14is an'upright rocker block 20. .Block 20 maybe permanently fixed to .Slide 14 or it may be attached thereto for replacement ,or interchange as desired. The rearward face of block. p 20 is provided with a transversely extending slot 27 and t the forward face of block 20 is provided with a trans vcrsely extending slot: 28. The top and bottom walls of each slot 27 and 28 are irregularly curved as shown.

Fixed permanently or interchangeably, as by bolts 45 to the rearward end of slide-14 is an upright cam block 31 having a cam surface 30. Cam surface 36 is generally concave and its contour is smooth and irregularly curved. It will be observed that the surface 36 faces in a generally upward and rearward direction. The lower edge of the surface 36 is inclined laterally from side to side of the block 31. Thus the surface 39 is curved in substantially vertical, horizontal and laterally inclined directions. Development of the cam surface 30 is carried out as a complement to the surface to be ground.

A rocker arm 48 has a depending member 21 at one end thereof fixed permanently or interchangeably thereto. Member 21 has jaws rockably engaging the slots 27 and 28 which constitute pathways therefor. The jaws of member 21 have resilient engagement with the perpendicular walls of slots 27, 28 by means of pins 22 which are urged into engagement with such walls by springs 2.4, each of which bears upon an adjusting screw 25. An additional pin 23, with spring 24 and screw 26 may be provided.

Rocker arms 21 has curved longitudinal sides to which the inner surfaces of side plates 32 and 33 correspond. Side plates 32 and 33 are secured to rocker block 20 by suitable fastening means 34. Strip springs 35 and 36 are fastened to side plates 32 and 33 centrally thereof by fastening means 37, such springs bearing upon the rocker member 21 to stabilize its rocking movement.

Rocker arm 48 is also provided with a depending cam follower 29 having a lower curved surface for engagement with cam surface 30.

Rocker arm 48 has tool supporting means comprising a V-shaped trough forming, as shown, a 90 included angle. Each wall of the trough has an outwardly extending flange. A tool 49 to be sharpened is held in position in the trough by means of front and rearlocking assemblies. The front locking assembly comprises a bracket 56 slidable on the flanges and securable thereto by set screw 57 and locking bolt 55 centrally and threadedly mounted in bracket 56 to abut the top of tool 49. Rear locking assembly comprises bracket 60 slidable on the flanges and secured thereon by set screw 57, and locking bolt 59 which carries an arbor 61 for engagement with the end of the tool.

A handle 58 is slidably positioned somewhat centrally on arm 48 and is securable thereto as by set screws 57.

A positioning member 63 is preferably provided for the tool to be sharpened, such member being generally L.-shaped with an included angle of about 135. The member 63 has a slot in one of its arms to receive a screw 62 mounted in one wall of the tool receiving trough. The other arm of member 63 is adapted to bear upon one of they flutes in the tool to position its cutting edge in generally horizontal position. It will be apparent that the member 63 may be secured in such tool holding position by tightening the screw 62. The slot in member 63 makes it adaptable for use with tools of varying sizes.

Insharpening cutters, a bar 54 is secured in the trough of arm 48 and the cutter 51 (see Figure is mounted conventionally in the bar 54 as by set screw 53. obvious that thebar 54 may be bent at right angles for mounting milling cutters and the like for sharpening.

For sharpening left handed tools, a structure such as shown in Figures 21 to 24 and 28 to 30 is employed,

such structure being similar in all respects to that already described but in which the various parts are reversed. Instead of rocker block 20, a block 40 is employed with slots or-recesses 38 and 39 in reversely'directed position. Instead. of cam block 31, cam block 42 with cam surface 41 is used. Similarly,,rocker jaw member 47. and

It is cam follower 46 are employed on rocker arm 48, plates 32 and 33v being interchanged.

Preferably, cam surfaces 30 and 41 are formed on separate plates as shown in Figure 16, such plate being adjustable relatively to the block 31 or 42 by means of screws 44 and being also spring pressed outwardly as by plurality of coil springs 43 seated in sockets in the block 31 or 42. Such a resiliently mounted plate ensures close contact therewith of the cam follower as it traverses various portions of the cam surface.

In operation, the tool to be sharpened, such as 49 or 54, is secured in position in the rocker arm assembly 48. The elevation of the apparatus is adjusted by means of the bolt 12 to position the tool opposite the circumfcrential face of grinder 50. Then the apparatus is rotated relative to the grinder by rotating the stud 11 in its socket to set the cutting edge of the tool at the desired angle to the grinder. The apparatus is then locked in such position by means of the set screw provided.

The desired clearance setting is obtained by adjusting the screws 44 in cam plate 30. To increase the clearance the screws 44 adjacent thelong curve or wide side of the cam surface are loosened and the springs 43 force the cam plate outwardly. The grinder being rotated, the handle 58 is manually manipulated to rock the tool carrying assembly.

The cam follower 29 moves in a three dimensional curved path over cam plate 30 and the rocker arm rocksin recesses 27 and 28 and between plates 32 and 33. The cuttingedge of. the tool is thus moved in a curved path including vertical, transverse and longitudinal move-. ment relative to the grinding face to obtain a sharpened cutting edge at the desired angle to the axis of the tool, and a convexly curved surface having the desired clearance. The tool may be rotated in the trough to present another cutting edge for sharpening.

The path of movement of the surface to be ground against the grinder is governed by the curvature of cam plate 30, and the curved faces of recesses 27 and 28 and rocker member 32. These curves are machined in re lation to known mathematical formulae and will vary in size and shape with the diameter of the grinder.

The use of apparatus which provides for substantially ertical movement of the cutting face of the tool with respect to the grinding wheel (as compared with conventional crosswise movement with respect to the wheel) results in the production of the greatly improved convex cutting face as set forth. Moreover, the apparatus described makes it possible to grind cutters with a convex cutting face rather than the conventional fiat or concave cutting face on such tools.

I claim:

1. In sharpening apparatus for cutting tools, a device for holding and guiding a cutting tool comprising a supporting plate, a rocker block fixed to one end of said plate, a cam block fixed' to the other end of said plate and having a generally concave irregularly curved cam surface, a cutting tool support having a depending jaw member at one end rockably engaging said rocker block and a depending cam follower at the other end for sliding engagement with said cam surface to guide rocking movement of said support, said cutting tool support being freely and. manually movable in any path determined by engagement of said cam follower with said cam surface, and a handle fixed to said cutting tool support for effecting manual movement thereof.

2. A device for holding and guiding a cutting tool as defined in claim 1, said camblock having a resiliently mounted plate on which. said cam surface is formed.

3. A device for holding and guiding a cutting tool as defined in claimv 1, saidrocker block having a pair'of transversely extending slots and saidjaw member-having jaws extending into said slots. I

4. A devicefor holding and guiding, a euttingtool as defined in claim 1, said rocker block having a of:

transversely extending slots, each said slot having irregularly curved walls, said jaw member having jaws extending into said slots and resiliently mounted portions engaging said slot walls.

the other end of said supporting plate and having a concave, irregularly curved, cam surface, a rocker arm having a depending jaw member rockably engaging said rocker block and a depending cam follower arranged to slidably engage said cam surface, and means carried by said rocker arm for clamping tool thereto.

References Cited in the file of this patent UNITED STATES PATENTS 2,178,441 Swanson Oct. 31, 1939

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