US2138672A - Method for pulverizing cemented carbides - Google Patents

Description

w th states PATENT QFFHCE METHOD FOR PULVERI ZING CEMENTED CARBIDES Frank F. White, Scotia, N. Y., assignor to General Electric Company, a corporation of New York No Drawing. Application March 30, 1935, Serial No. 13,931

8 Claims. (Cl. 83-94) The present invention relates to sintered hard tained for a short period of time until the cemetal compositions and more particularly to cemented carbide pieces are heated throughout at mented carbides and to a, method for treating this temperature after which the pieces are such carbides whereby they may be easily cooled. They then may be crushed easily in any crushed or pulverized. convenient manner, for example in an ore 5 A cemented carbide is a sintered composition crusher. generally consisting of hard metal carbide par- When the cemented carbide pieces consist subticles cemented together by binder metal having stantially of tungsten carbide and cobalt, the a lower melting point than carbide particles. heating temperature employed is preferably Binder metals commonly employed in cemented above 1600 C. and generally in the neighborhood 10 carbide compositions are metals of the iron group of 1700 C. and the heating period ab0ut'30 secor combinations of metals of the iron group with onds. If a temperature lower than 1600 C. is other metals such for example as metals of the employed there may be some difficulty in crush- 6th group of Mendelejeffs Periodic Table of eleing the material while if the temperature is ma- 5 ments and the quantity of such binder material terially higher than 1700 c. the cemented caremployed usually varies from about 3 to 25% of bide when cooled solidifies into a very hard mass. the weight of the composition although higher The heat treatment employed is generally carpercentages of binder material may be employed ried out in a carbon receptacle so as to provide a if desired. carbonaceous atmosphere and to thereby pre- Cemented carbides generally are employed as vent any appreciable reduction in the carbon 20 metal cutting tools or as wire drawing or bendcontent of the heat treated material. ingjdies. When employed as a metal cutting tool The crushed material provided by the present the cemented carbide is usually in the form of a process may be pressed into desired shapes and small tip which is copper brazed to a supporting sintered into a hard tough mass in a manner steel shank. Since cemented carbide tools are well known in the art. The invention moreover generally quite brittle there is a considerable is not limited to any specific cemented carbide amount of breakage of s uch tools. Broken or composition but may be applied generally to any worn tools heretofore have been salvaged by composition of that character. methods disclosed in the patent to Taylor No. What I claim as new and desire to Secure by 1,895,354, January 24, 1933, and in the patent to Letters Patent of the United States, is: 30 Billings No. 31,895,364, January 24, 1933. How- 1. In a method for pulverizing a hard ceever, it usually is desirable in salvaging such tools mented carbide composition, the steps which that thepieces of the cemented carbide be recomprise heating aid c mented carbide in a duced to a finely divided or pulverized condition. carbonaceous atmosphere and at a. temperature This can be done, as disclosed in the Taylor patsufiiciently high to cause said cemented carbide 35 ent, by crushing the cemented carbide in a morto assume a spongy condition and thereafter tar, the crushing being followed by long ball cooling said spongy material. milling. As a rule the cost of the crushing and 2-. In amethod for pulverizing a hard cemented ball milling is very high and may exceed the cost carbide composition, the steps which comprise 40 of providing an equal weight of new ingredients heating said cemented carbide in a carbonaceous 40 in powdered form. atmosphere and at a temperature sufficiently It is an object of the present invention to prohigh to cause said cemented carbide to assume vide a method whereby worn or broken cemented a spongy condition, cooling said spongy material carbide compositions may be pulverized in a r and pulverizing it.

simple, efilcient and inexpensive manner and 3. In a method for pulverizing hard cemented 45 thereafter pressed into any desired shape and carbide compositions, the steps which comprise sintered into a hard compact mass. heating said cemented carbide in a carbon tube In carrying out the present invention, pieces at a temperature sufficiently high to cause said of cemented carbide to be salvaged or pulverized cemented carbide to assume a spongy condition are placed, in any desired quantity, in a closed and then cooling said spongy material. 50 carbon receptacle which for example may be in 4. In a method for pulverizing cemented carthe form of a tube about 3" x 6" with walls. bide compositions, the steps which comprise heat- The tube when loaded is heated to a temperature ing said cemented carbide in acarbon tube at a at which the cemented carbide pieces become temperature sufficiently high to causesaid cespon y or bloated. This temperature is mainmented carbide to assume a spongy condition, 55

ing said cemented carbide in a closed carbon recooling said spongy material ing it.

5. In a method for pulverizlng cemented carbide compositions, the steps which comprise heatand then pulveriztime, cooling the hard metal composition from that temperature and pulverizing it. i 7. The method for pulverizing a sintered hard metal composition containing about 3 to 25% cobalt, the remainder of the composition con- 5 sistlng substantially of tungsten carbide which comprises placing the sintered material in a closed carbon receptacle and heating the receptacle to a temperature in the neighborhood ceptacle at a temperature of about 1600 C. to about 1700 C. and cooling the cemented carbide from that temperature.

6. A method for pulverizing a sintered hard metal composition consisting substantially of of 1600" C. to 1700 C. for about 30 seconds, 0001- 10 hard metal carbide particles cemented together ing the heated material and then pulverizing it.

by a binder metal having a lower melting point 8. A method for crushing a cemented carbide, than the carbide particles which comprises heatsaid method comprising heating said carbide to lug said sintered composition in a closed carbon a temperature between about 1600 C. and receptacle at a temperature sufiiciently high to 1700 C., cooling said carbide and then crushcause said hard metal composition to become ing it.

FRANK F. WHITE.