US2787174A - Method of manufacturing a cutter disk - Google Patents

Description

April 2, 1957 R. w. HYDE 2,787,174

METHOD OF MANUFACTURING A CUTTER DISK Filed Dec. 14, 1955 fijfum A1 TOENEYS.

METHGD OF MANUFACTURING A CUTTER DISK Robert W. Hyde, incinnati, Ohio, assiguor, by mesne assignments, to American Radiator & Standard Sanitary Corporation, New York, N- Y., a corporation of Delaware Application December 14, 1953, Serial No..397 ,984

3 Claims. (Cl. 76-.-.-104) This invention is directed to a cutter disc and the method of manufacturing the same. -The cutter disc has particular utility in garbage disposal units of the type disclosed in my copending patent application Serial No. 392,873, filed November 18, 1953.

The garbage disposal unit of my copending patent application operates npon the principle of subjecting food waste to the cutting action of a spinning disc which has a plurality of teeth extending upwardly from the upper surface thereof. The disc is mounted for rotation about vertical axis and is disposed at'the lower end of a casing, which, with the disc, defines the comminuting chzufnber of the disposal unit. inside of the casing a pair of vanes which are disposed diametrically opposite to one another, overhang the outer edge of the disc. The purpose of the vanes is to prevent food waste whic is on the spinning disc from attaining the rotational speed of the disc so as to maintain relative motion between the food waste and the cutter disc. The vanes also serve to direct food waste which is on the outer edge of the spinning disc downwardly and inwardly from the inner wall of the casing onto .the spinning disc. 'Thus, contrary to the accepted practice, the disposal unit of the copending application cuts up or comminutes the food waste by means of, a dynamic, spinning element, and utilizes static or vane-like elements to direct the food waste toward the cutting element. In the past, the relationship has been the reverse. s oecalled hammers, vanes or ribs mounted upon a spinning impeller have been used to forcibly throw or direct food waste against stationary cutting teeth formed as a part of, or mounted upon, a. casing surrounding the impeller.

in the type of operation disclosed in my copending application, the efficiency of the unit is dependent upon the effectiveness of the cutter teeth which are on the spinning disc. Their effectiveness, of course, is directly related to their sharpness and. their ability to hold an edge. Accordingly the primary objective of the present invention is to provide "a method of manufacturing a highly improvedcutting disc having exceedingly sharp cutting teeth which are adapted to maintain their sharpness over prolonged and hard use.

A further objective has been to provide a cutter disc of the type described which can be manufiactured at low cost utilizing readily available material and production line techniques.

ther objects and advantages will be readily apparent to those s tilled in the art from the following detailed description of the drawings in which:

Figure l is a top plan view illustrating a cutter disc made in accordance with the techniques of the present method.

Figure 2 is a fragmentary cross sectional View taken on the line 2,-2 of Figure 1 illustrating the first step in the manufacture of the present cutter disc,

Figure 3 is a diagrammatic view, in perspective, illushired States Patent 2,787,174 "i iPatented Apr. 2, 1957 ICC 2 trating the means utilized in-the second step of the method.

Figure 4 is a view similar to Figure 2 showing the tooth at the completion of the second step in the method.

Figures 5, 6. and 7 are views similar to Figure 4'illu-s trating three addition'alsteps in the method, Figure 7 showing a finished tooth.

in general the cutter disc, which is indicated 'at 10 in Figure 1, consists of a'oircular plate having an aperture 11 in the center thereof by whichit may be-affixed-t-o the drive shaft of a garbage disposal unit. A flat 12 is formed in aperture 11 tokey it to the shaft. The central area of the disc preferably is depressed' with respect to the plane of the upper surface'of the disc to provide a circular boss 13 at the-underside thereof which seats on top of a packing gland in the disposal unit. Preferably, the under surface of the boss 13 is polished to reduce wear between the disc and the packing gland.

A plurality of substantially"V-shaped teeth or barbs 14- extend from the upper surface of the disc. These teeth may 'be disposed in a random pattern in the annular area of the disc between the depressed central area and the outer edge. It is preferred, however, that the teetl are oriented so that they either present the apex of their rough, V-shape or a sideedge thereof in the direction of the rotation of the installed disc. The disc shown also has a plurality of radially disposed slits such as those indicated at 15 which are cut in the outer edge thereof to make it possible to strike downwardly areas ahead of the slits in the direction of rotation of the discs to expose shearing edges at thetop and outer ends of the slits. The exact configuration and purpose of the slits 15 is set forth in detail in the copending patent application re ferred to above and for this reason is not discussed here. Briefly, however, the edges provided .by the slits 15 cooperate with a shearing ring in the disposal unit, the edges and ring resulting in unifQIm particle size in the comminuted material discharged from h Unit.

The present invention concerns primarily the formation and shape of the teeth which are indi ated at 14. The end sought is to provide knife-like sharp edges on thecutter teeth which are elfective to rapidly reduce the particle size of food waste by cutting the waste into tiny bits and which are sufficiently hard and tough to not show appreciable wear over a lifetime of ordinary domestic use.

The preferred plate material for forming the cutter disc is .125 inch thick. The material currently is used for the manufacture of automobile bumpers, and therefore is readily available. The metal is identified as S. A. E. 950.

The cutter disc is first blanked out to produce a circular plate from the stock material. The central boss 13 and the aperture 11 then may be formed by conventional stamping and dieing techniques. At this time, the radial slits 15 may 'be formed and the edge of the plate adjacent to the slits bent down as disclosed in the copending application. These operations are carried out at the upper side of the disc, The first step in the present method to form the cutter teeth isto punch the reverse or .underside of the plate with a plurality of V-shaped punches which are arranged in thev pattern of the teeth illustrated in Figure 2. This operation initially forms the teeth or barbs 14. The condition of a tooth after the punching operation is illustrated in Figure 2. At this time, the tooth or barb is on a slant and. extends above the upper surface of the disc approximately .G9-.l inch. In the next step of the method, the teeth are scrubbed over by means of a tool which is pressod against the. face of the disc while the tool is. being rotated at high speed in he ir cti that he cu ter disc ota es. when t ,i

"being used in disposal Before this is done, however, the plate material is annealed by a heat treatment to soften it to approximately Rockwell B 74. The annealing may be done'at 1240" F. for eight hours and the blank disc cooled slowly from this temperature over a period of eight hours.

The preferred means for scrubbing over the teeth is shown in Figure 3. The tool consists of a heavy circular plate 16 upon which a plurality of half round, tool steel bars 17 are radially disposed. In the present instance,

four such bars, mounted at equally spaced points circumferentially of the plate are employed. The annealed disc is fastened rigidly in place and the rapidly turning plate 16 moved in toward the face of the disc. During such movement the plate 16 is maintained in parallel relation to the cutter disc with its axis of rotation in alignment with the central axis of the disc. The half round bars 17 on plate 16 upon being pressed inwardly toward the disc swage or scrub over the edges of the barbs so that they appear as shown in Figure 4, having a rather long marginal lip portion 18 overhanging in the direction of rotation of the plate 16. The bars 17 should be applied sufiiciently long and under enough pressure to reduce the distance that the teeth extend above the surface of the disc from approximately .09.1 inch to approximately .03-.O4 inch. The overhanging lip 18 at this time is rounded and would not serve as a cutting edge.

In the next step of the operation, the barbs or teeth are flattened back into the plate by a die which engages the upper surfaces thereof. This also is carried out under considerable pressure, sufiicient at least to swage over and slightly round the edges 19 of the plate material beneath the overhanging lips 18. It also serves to flatten out slightly the rounded edges 19. The condition of a tooth under these circumstances is illustrated in Figure 5. Preferably, the teeth are flattened to a point where they extend only approximately .005 above the upper surface of the disc.

After the flattening operation, the barbs or teeth are surface ground to reduce the extent that they extend above the upper face of the disc to approximately .002 maximum. The effect of the grinding is to change the overhanging, rounded lips 18 into exceedingly sharp knife-like edges such as the one indicated at 20. At this time the upper surface of the cutter disc is substantially planar. In the next step, the barbs are again punched outwardly, using the same technique by which the barbs were formed in the first step. When finished, the teeth should be above the upper surface of the disc approximately .09.1 inch. The entire disc is then case-hardened to approximately .0l-.0l5 deep, being quenched, to filehardness preferably as hard as Rockell 88 using the -N scale.

As the last step in the method, the disc may be ltruedup by grinding the outer edge to remove burrs and other small irregularities. The face of the boss 13 may be polished at the same time, care being exercised to insure that it is parallel with the upper surface of the disc.

The scrubbing and grinding to which the teeth are subjected result in considerably less than precisely formed cutting edges. As shown in Figure 2, the edges are irregular or jagged. However, it is found that the unevenness of the edges increases, rather than decreases, the efficiency of the cutter disc in a disposal unit. By scrubbing over the teeth so that they overhang in the direction of rotation of the cutter disc, surprisingly wide knife-like cutting edges are produced. Such wide edges, being file hard, are found to stand up and last exceedingly well in the life tests to which discs made in accordance with the present method have been subjected.

Having described my invention, I claim:

1. The method of manufacturing a cutter disc for use in a cutting operation in which said disc rotates in one direction only, said method comprising the steps of providing a circular plate made of metal which is adapted to be annealed and subsequently case-hardened, punching the underside of said plate to form a plurality of V-shaped barbs which extend from the upper surface of said plate at an angle between ten and thirty degrees, the respective V-shaped barbs being oriented so that either a side thereof or a point thereof is presented in the direction of the rotation of the disc when in use, annealing said plate, subjecting said barbs to the scrubbing action of a blunt tool which is pressed against said barbs while traveling in the direction of the rotation of the disc when in use so as to form lips which overhang the edges of the baths in said direction, flattening said barbs back into the plate so far as the overhanging lips permit, surface grinding the upper surface of said plate to sharpen said overhanging lips, re-punching said barbs as in the second step above, and case-hardening said disc.

2. The method of manufacturing a cutter disc for use in a cutting operation in which said disc rotates in one direction only, said method comprising the steps of providing a circular plate made of metal which is adapted to be annealed and subsequently case-hardened, forming a plurality of V-shaped barbs which extend from the upper surface of said plate at an angle between ten and thirty degrees, annealing said plate, subjecting said barbs to the scrubbing action of a blunt tool which is pressed against said barbs while traveling in the direction of the rotation of the disc when in use so as to form lips which overhang the edges of the barbs in said direction, flattening said barbs back into the plate as far as the overhanging lips permit, grinding the upper surface of said plate to sharpen said overhanging lips, re-forming said barbs as in the second step above, and case-hardening said disc.

3. The method of manufacturing a rotatable cutter disc having teeth. thereon which comprises the steps of providing a circular plate made of metal which is adapted to be annealed and subsequently case-hardened, punching the underside of said plate to form substantially V-shaped barbs which extend from the upper surface of the plate at an angle of between ten and thirty degrees, annealing said plate, subjecting said barbs to the scrubbing action of a blunt :tool which is presented to said barbs while it is traveling in the direction the cutter disc rotates when in use to form a lip on each of said barbs which overhangs the edge thereof, flattening each of said barbs back into the plate as far as said overhanging lip permits, grinding said barbs to sharpen the overhanging lips, re-punching said barbs as in the second step, and case-hardening said disc to file-hardness.

4-. The method of manufacturing a rotatable cutter disc having teeth thereon which comprises the steps of providing a circular plate made of metal which is adapted to he annealed and subsequently case-hardened, punching the underside of said plate to form substantially V-shaped barbs which extend from the upper surface of the plate at at angle of between ten and thirty degrees, annealing said plate, forming a lip on each of said barbs which overhangs the edge thereof in the direction of rotation of the disc, flattening said barbs back into the plate as far as the respective overhanging lips permit, grinding said barbs to sharpen said overhanging lips, re-punching said barbs as in the second step above, and case-hardening said disc to file hardness.

5. The method of manufacturing a cutter disc which comprises the steps of providing a circular metal plate, punching the underside of said plate to form substantially V-shaped barbs which extend from the upper surface of said plate, forming an overhanging lip on each of said barbs, flattening said barbs into the plate as far as the respective overhanging lips permit, grinding the upper surface of said plate to sharpen said overhanging lips, and rte-punching said barbs as in the second step above.

6. The method of manufacturing a rotatable cutter disc which comprises the steps of providing a circular metal plate, punching the underside of said plate to form substantially V-shaped barbs which extend from the upper surface of said plate at an angle of between twenty and thirty degrees, subjecting said barbs to the scrubbing action of a blunt tool to form an overhanging lip on each or said barbs, flattening said barbs into the plate as far as the overhanging lips permit, grinding the upper surface of said plate to sharpen said overhanging lips and repunching said barbs as in the second step above.

7. The method of manufacturing a rotatable cutter disc having teeth thereon which are oriented to present cutting edges in the direction said disc rotates when in use, said method comprising the steps of providing a circular plate made of a metal which is adapted to be annealed and subsequently case-hardened, punching the underside of said plate to form substantially V-shaped barbs which extend angularly from the upper surface of said plate substantially in the direction said disc rotates when in use, said V-shaped barbs being oriented so as to present either a flat side or a point thereof in said direction, annealing said plate, subjecting said barbs to the scrubbing action of a blunt tool which is pressed against said barbs while rotating substantially parallel to the upper surface of said disc and in the direction of rotation of the cutter disc when in use so as to form lips on said barbs which overhang the upper surface of said disc in said direction, flattening said barbs back into the plate as far as said overhanging lips permit, surface grinding the flattened barbs to sharpen said overhanging lips, re-punching said barbs as in step two above, and case-hardening said disc to file-hardness.

8. The method of manufacturing a rotatable cutter disc having teeth thereon which are oriented to present knife-like edges in the direction said disc rotates when in use, said method comprising the steps of providing a circular plate, forming substantially V-shaped barbs which extend from the upper surface of said plate at an angle of between ten and thirty degrees, said V-shaped barbs being oriented so as to present either a fiat side or a point thereof in the direction said disc rotates when in use, forming lips on said barbs which overhang the upper surface of said disc in said direction of rotation thereof, flattening said barbs back into the plate as far as said overhanging lips permit, grinding the flattened barbs to sharpen said overhanging lips, and re-forming said barbs as in step two above.

References Cited in the file of this patent UNITED STATES PATENTS Re. 19,477 Dixon et a1 Feb. 26, 1935 1,719,305 Pardee July 2, 1929 1,845,522 Rowley Feb. 16, 1932 1,972,735 Fischer Sept. 4, 1934 1,979,748 Kimmel Nov. 6, 1934 2,154,650 Wishinsky Apr. 18, 1939 2,182,067 Bruecker Dec. 5, 1939 2,325,205 Molnar July 27, 1943 2,460,901 Newman Feb. 8, 1949 2,477,198 Murray July 26, 1949 2,583,997 Chester Jan. 28, 1952 2,708,376 Booth May 17, 1955 FOREIGN PATENTS 209,465 Germany May 8, 1909

Images