US1866315A - Method of making a cutter - Google Patents

Description

' y 1932- RD. MERRILL 1,866,315

METHOD OF MAKING A CUTTER Filed July 18, 1930 ,.o 26 WW! 21 i ll w Patented July 5, 1932 UNITE. s'rrs AENT PATTERSON D. MERRILL, OF SOUTH BEND, INDIANA, ASSIGNOR TO M. B. SKINNER, ('10., OF SOUTH BEND, IN DIANA, A CORPORATIONOF INDIANA METHOD OF MAKING A GUTTER These improvements relate to cutters for such devices as valve reseating tools, and to a method for making same.

The chief objects of the invention are to reduce the cost of manufacture and to provide a longer-lived and otherwise more satisfactory cutter. Other objects and advantages will appear hereinafter.

In the drawing Figure 1 shows in face view the preferred form of blank for the cutter;

Fig. 2 is a face View of the cutter complete;

Fig. 3 is an edgeview of the cutter with fragments of dies used in the forming operation, the lower or seating die being in medial vertical section;

Fig. & is an enlarged cross section of one of the radial leaf-like formations or parts, between forming dies; and

Fig. 5 is an elevation, with parts broken away, of a well-known form of valve-reseating tool illustrating an application of the present invention.

It is old to provide a cutter of the general character of the 'oneillustrated herein. In my practice heretofore I have made them from circular plate-like discs, with integral upstanding radially-directed cutter elements pressed out therefrom. According to the older practice the flat disc of cutter steel is placed in dies following the general illustration of dies in Figs. 3 and 4:, the top surfaces of the elongated rib-like projections being, however, on straight-across lines instead of being slanted away as illustrated herein. In order to press out such cutting elements from the hard steel disc, as distinguished from the present spider-like form, such an enormous pressure is required as from two hundred fifty tons to three hundred tons per approximate square inch of surface. Even with such pressures it is nnpracticable to produce a cutter rib which rises more than a slight distance above the general surface of the body part and, furthermore, that part of the rib which eventually defines the cutting edge is so poorly pressed into the sharp corner of the die thereat that the ensuing grinding operation for slanting off the top surface of the rib to relieve the cutting edge forproper action must be a substantially deep cut, further lessening the height of the cutter rib.

The results therefore have been that according to the older practice there has been very little clearance for' the shavings, and but slight opportunity forregrinding the cutter when it becomes dull, and there have been requirements of: heavy and expensive machinery, and the use of considerable power, with breakdowns in practice usually incident u to the use of excessive power. 0 The present objects include the overcoming of such objections and disadvantages.

Referring to Fig. 1 the blank 10 may be considered to be of flat sheet steel of the kind ordinarily used for such cutting tools. It is blanked out cold by means of dies shaped accordingly. In the device of Fig. 5 the cutter marked 11 may be considered to be about seven eighths of an inch to an inch across on any diameteri'c line. For such a cutter the blank of Fig. 1 would be of the same size. The thickness of the steel in my practice is usually three sixteenths of an inch for outters of this kind. There is no limitation, however, within reasonable limits, as to these diameters or thicknesses of material.

The blank 10 is formed with recesses 12 eX- tending inward a materially great distance from marginal portions of the blank, and these recesses are preferably substantially V- shaped whereby'the opposite edges 13 and 14 of the radially-extending leaf-like parts 15 are substantially parallel to each other. I have shown the recesses 12 as extending inward to a place which is approximately 'mid- 4 way between the center and the periphery of the blank, which is found satisfactory in practice. This produces a spider-like blank having a solid interior and radiating arms.

The leaf-like parts 15 defined by the contiguous recesses 12 have substantial width in the circumferential directions, for the purpose of strength and rigidity.

In Fig. 2 the body of the cutter complete is denominated 20, the recesses 21, the leaflike radially-directed formations 22, and continuous, elongated, upstanding, radially-directed ribs or cutting elements 23.

Fig. 4. clearly shows that the top surface 23a of any one of these ribs 23 is slanted 0ft rearward from the cutting edge 24. I find that according to these improvements the metal is so well forced into the sharp corners of the dies that I may press the ribs substantially into their final shape, so that merely a very light grinding cut will suffice, if any at all be necessary. Furthermore, the rib is materially higher than according to the older practice, so that there is better clearance for cuttings, and resurfacing of the cutting ribs may frequently be had, and the tool as a whole has longer life in service.

These and other advantages result from the provision of recesses as 12 in the blank. The blank is seated in the nesting die 26 and when the pressure is applied by the forming die 27 the metal of the blank has space into whichto flow. The downwardly slanting side walls 28 and 29 show that at the top and gradually less toward the bottom the metal is extruded into the space of the adjoining recess 21. At 30, Fig. 3, similar overhang occurs at the free end of the leaflike extensions 22. It occurs also at the crotches 31 of the respective recesses. Fig. 2 showsthat the recesses 21 are smaller'in top View. than are the recesses 12 of the blank, which is due to such flow or extrusion of the metal.

Accordingly I am able to effect quite notable savings in cost, while producing a more efficient and otherwise more satisfactory tool.

A hole 33, Fig. 2, is bored centrally of the cutter for affixing it to a shaft as 3-1, Fig. 5, and such hole is usually screw threaded. Such central hole may be provided in the blank, but I prefer to bore it after the pressing operation, as producing a somewhat cleaner ob.

I contemplate as being included in these improvements all such changes, variations and departures from what is illustrated and described herein as fall within the scope of the appended claim.

I claim:

The method of making a cutter of the character described which comprises forming a blank in substantially thick spider-like form from suitable material such as steel, such blank having materially deep recesses extending inward from marginal portions of the blank to define a central body and substantially radially-directed integral arms, and then extruding metal from the face of the blank to provide a plurality of elongated substantially radially-directed upstanding integral cutting elements on the face surface of the blank with the cutting elements respectively rising from and extending longitudinally upon the respective arms from near the center of the body to near the ends of the arms respectively.

PATTERSON D. MERRILL.

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