US2614441A

US2614441A - Cutter and method of forming the same

Info

Publication number: US2614441A
Application number: US739268A
Authority: US
Inventors: Emmons A Goddard
Original assignee: GODDARD AND GODDARD CO
Current assignee: GODDARD AND GODDARD CO
Priority date: 1947-04-04
Filing date: 1947-04-04
Publication date: 1952-10-21
Anticipated expiration: 1969-10-21

Description

Oct. 21, 1952 GODDARD 2,614,441

CUTTER AND METHOD OF FORM ING THE SAME Filed April 4, 1947 E LET-J- I N VEN TOR. [MMO/VS 4. 5000/: RD

ATTORNEY Patented Oct. 21, 1952 signor l I This invention relates generally to cutters and refers mor particularly to metal disc type outters having hub portions. Y I

Although it will be apparent as this descriptionproceeds thatthe invention is notlimited to any specific type of cutter, nevertheless, it finds particular utility whenemployed in the manufacture of -circular disc type cutters, such for example, as circular saws-having hub por tions at the center and having ra'dially outwardly extendingrerelatiyely thin, web portions.

Circular cutters of the above general type have been diflicult to economically manufacture to the close. tolerances required for many uses of such cutters. Much of thedifi iculty heretofore encountered in producing circular cutters is'Tdueto the non-uniform rate .o'f cooling of the cutters subsequent to'the heat' treating and/or side grinding operations; This uneven rate of cooling is caused by the differences in mass of the hub and web portions; of the cutter.' The mass of the hub portion ordinarily exceedsthe mass of the web portion, andas a consequence, cools at a, rate which is slow comparison to the rate of cooling of thewvveb portionlThis differential. sets up strains in the cutterwhich are'frequently sufli'ciently severe to cause distorltion'iof the cutter beyond repair. l T j Inorder to overcome the above difilculties, complicated and expensive heat treating techniques have been proposed- One heat treating Process advocated is to provide some means for accelerating the rate of cooling-.of thev hub to suchan extent that this rate approximates the rate of cooling of the relativelythin web. Another process is to attemptitoqhold the cutter against warping or distorting by maintainingthe cutter clamped between heavy plates during the heating and cooling cycles of the heat treating operation. Still another process is to leave sufficient stock on the cutter so that any buckle or distortion created during heat treating may be subsequently removed by grinding before the thickness of the cutter becomes undersize.

Even where unusual care is taken in the performance of the above heat treating processes, the results obtained are unsatisfactory. Moreover, such special heat treating processes are not conducive to producing cutters on a high production basis, and at best add materially to the cost of finished cutters.

With the above in view, it is an object of this invention to overcome the above diificulties experienced in producing heat treated circular Emmons -'A'. Goddard, Birmingham, 'Mich -"as to"- Goddard & Goddard Company, De-

etroit, Mich., a corporation of Michigan i Application April4, 1947, Serial No 739,268 1 -3Claims. (01.7 5101) j 4' A more detailed, object of this invention is to provide a. circular cutter .offthe general type stated, wherein the mass of the hub portion approxir'nates the mass ofthe radially extending web portion so that, practically speaking, the rate oifcooling of "the'hub and rim portions are these-me or nearly so. Thus the cutter-maybe heat treated by, the simplestproc'es'ses without buckling warping or otherwise "distorting the cutter.. Moreover,'less'heat is generatedin the "ubs'equent side grinding operation, and the tendency of the cutter to distort during grinding is reduced, to a minimum. It follows,'therefore, that clos'e tolerances may beheld on dimensions of .1 thickness, flatness and concavity, Which. are prerequisites, ofsatisfactory'cuttersI t he foregoing as well. as other objects will be made more apparent as this description proceeds, especially when consideredin connection with the accompanying drawing, .whereinp Figure 1v is asid elevational .view of ac rcular disc type cutter constructed in accordance with this i invention;

1 QEigure 2 is a sectionalview taken ori-the line 25-2 of Figural; .Figure 3 is a side'elevationalview ofamodifiedli m-r utt r; a 1

'ew taken on the line ,Figure 4' is a sectional 4 4 ofFigurefi. 7 I 1 5 For the purpose of illustrating this invention, acircular disc ,type saw is selected, although it will be understood as this description proceeds that the invention may. be successfully employed in the production of various othertYDfiS Ofcutters. Referring first to the embodiment of the invention shown inFigures 1 and 20f the drawing, it will be noted that'the reference numeral I0 designates 'a cutter in the form of a circular disc type saw formed of metal, such for example, as high speed steel or any other type of steel possessing the required characteristics.

In detail the saw It! comprises a hub H and a web I2 extending radially outwardly from the hub. The hub is formed with a central opening l3 therethrough having a key receiving recess 4 and the periphery of the web I2 is formed with a circumferential series of cutting teeth I 5. In accordance with conventional practice, the cutter is heat treated, and any orthodox process may be resorted to for this purpose. In general the cutter is heated to a temperature recommended for the particular metal employed to obtain the desired temper and is then cooled in any suitable manner.

The web I2 is relatively thin in comparison to the thickness of the hub II and sufficient metal 3 is removed from the hub to reduce the mass of the hub to a value approximating the mass of the web. In other words the bulk or quantity of material forming the hub H is substantially the same as the bulk or quantity of material forming the web l2, although the thickness of the hub H is greater than the thickness of the web. In the present instance a pair of annular recesses or grooves I6 is formed in one face of the hub in concentric relation to the axis of the cutter and a second pair of annular grooves H is formed in the opposite face of the hub axially opposite the grooves I6. Also, if desired,

between opposite faces of the cutter in the surface of thecutter surrounding the central opening 13. The amount of metal removed from the hub II bythe above mentioned grooves, or in other words, the size and/or number of grooves is predetermined to provide the hub with a mass approximating the mass of the web 12. Thus during the cooling phase of the heat treat mg. process, the hub I I cools at substantially the same rate as the Web I2, and the tendency for the cutter to buckle, distort or otherwise deform is, reduced to a minimum. It w1ll also be notedthat the side walls'of the grooves provide heat 1 radiating surfaces which facilitate coolingof'the hub II and assist in preventing distortion of the cutterduring finish grinding the latter. a

' The embodiment of the invention shown in Figures 3 and 4ofthe drawing features a disc type cutter ZUidentical to the cutter I0 except that the recesses'are in the form of a multiplicity of openings 2! drilled in the hub. The openings are spaced 'equal distances from each other around the axis of the hub and serve to reduce the mass of the hub sufiiciently to enable the hub to cool atpracticallythe same rate as the web during the cooling phase of the heat treating operation.

It follows from the above that both embodiments of the invention provide a disc type cutter having a hub and a webcharacterized in that the mass of the hub approximates the mass of the web, so that the cutter cools practically uniform- 13 during the cooling phase of the heat treating operation. Thus deformation of the cutter by strains set up in the cutter during the cooling phase is reduced to a minimum, and the production of a cutter to close tolerances'is rendered possible without resorting to special heat treating processes.

What I claim as my invention is:

1.111 a method of producing a heat treated metalcutter having contiguous hub and web portions, the web portion extending radially outwardly from the hub portion and being relatively thin as compared to the thickness of the hub portion, the steps of reducing the mass and increasing the surface area of the hub portion to an extent such that both said portions cool at the same rate from an elevated temperature, the mass of the hub portion being reduced and the surface area thereof being increased without changing the overall thickness of the hub portion, and thereafter subjecting the cutter to a heat treating process including a heating and cooling phase.

2. The method defined in claim 1, in which the mass of the hub is reduced and the surface area thereof is increased by forming openings in said hub portion at points spaced equal distances from each other around the axis of the hub portion.

3. The method defined in claim 1, in which the mass of the hub is reduced and the surface area thereof is increased by forming, concentric annular grooves in at least. one radial face of the hub portion.

. EMMONS A. GODDARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS. Date Number I Name 63,487 Disston Apr. 2, 1867 214,389 Hill Apr. 18, 1879 220,432 Sawyer et a1 Oct. 7, 1879 320,681 I Perkins June 23, 1885 468,742 Erickson Feb. 9, 1892 903,933 Williams Nov. 17, 1908 910,137 Lehmann Jan. 19, 1909 927,164 Pufier July 6, 1909 1,351,499 Takano Aug. 31, 1920 1,837,344 Stauder Dec. 22, 1931 1,861,218 Huther' May 31, 1932 2,064,407 Bird Dec. 15, 1936 2,169,632 Drummond Aug. 15, 1939 2,214,827 Boeet al Sept. 17, 1940 2,297,611 Drummond Sept. 29, 1942 2,338,990 Wenzel Jan. 11, 1944 FOREIGN PATENTS Number Country Date 23,864 Great Britain Mar. 9, 1911 35,906 Sweden Dec. 10, 1913 68,001 Germany June 25, 1892 277,203 Germany July 28, 1914 358,429 France Dec. 18, 19 5 598,793 Germany June 18, 1934