US1860275A - Means and method of cementing tungsten carbide to other metals - Google Patents

Description

Ma;y 24, 1932. w c pm I 1,860,275

MEANS AND METHOD OF CEMENTING TUNGSTEN CARBIDE TO OTHER METALS Filed Nov. 16, 1929 gwvmtoz Patented May 24, 1932 UNITED STATES.

PATENT OFFICE WILLIAM R. CHAIIN, OF INDIANAPOLIS, INDIANA.

MEANS AND METHOD CEMENTING TUNGSTEN CARBIDE TO OTHER METALS Application filed November 18, 1929. Serial No. 407,741.

This invention relates to methods of cementing o'r brazing tungsten carbide and similar materials to a steel shank or base to be used in making various kinds of cutt ng tools, punches, dies, etc.

Heretofore it has been generally believed that tungsten carbide could not be heated to temperatures in excess of 2000 degrees l3.

without serious injury to the tungsten carbide 1c and furthermore that joining tungsten carbide to a steel base of a shank required expensive and special equipment and that the work must be done in anatmosphere of gas which would not affect the tungsten carbide. This belief limited the making of carbide tools to only a few skilled persons familiar with a delicate process and prohibited its use except with expensive apparatus. I have discovered that tungsten carbide tools can 7 2: be cemented to a steel base or shankby a rocess which is simple and easily practiced y any one skilled in this art.

Referring to the 'accompanyin drawing which is made a part hereofthe gure indicates a machine tool shank or base showing a hardened cutting block of tungsten carbide or other hard metal cemented to the'base. In the drawing numeral 10 indicates; a shank of steel having a socket cut out at 11 at to receive a cutting block 12 of suitable hard metal such as tungsten carbide. In carr 'ng .out my process I place in the-bottom o the recess 11 a special cement-which is spread to about of an inch in depth and the tungsten carbide bit 12 which has been polished clean is placed in the recess on the top of the coment. A liberal quantity of dry powdered boric acid or some of its derivatives, such as I borax or borax glass is'sprinkled all over the I top of the bit and completely filling the crevices in the shank around the bit. The tool is 4 then placed in a suitable tool heat treating furnace which is maintained at sufiicient low dently. The tool is then transferred to another ordinary-heat treating furnace and the tool heated to a temperature sufiicientto thoroughlymelt the cementing medium; If the cement is any of those compounds cov- 53 ered by my prior Patents No. 1,699,346-or temperature so as not to heat the bit too sud- 1,362,472 the temperature should be about 2200 to 2350 degrees F. If copper or its compounds are used as a joining medium the temperature need not exceed 2000 degrees F. Since boric acid and its compounds mentioned above melt at a relatively low temperature and become fluid the entire surface of the bit and the joint itself is completely sealed from the gases of the furnace during the heating. When the tool is brought up to the proper high temperature it" is taken from the furnace and the excess o'f the cementing medium is at once squeezed out with a suitable means such as a press vice, etc

If carried out as described in my previous patents this squeezing operation would unduly chill the tungsten carbide bit and cause it to crack. To avoid this danger I place between the bit and the pressv piece of steel of suflicient thickness which is heated to apgroximately the same temperature as the bit. y doing t is thesqueezing operation above mentioned can be carried out without chilling the bit. The pressure is maintained for a short time so as to allow the cementing medium to set and then the tool is laced at ble to cement tungsten carbide to 'a steel shank with the ordinary heat treating equip- -ment now in universal use.

7 It will be obvious to those skilled inthe art that variousc'hanges may be made in' my device without departing from the spirit of the invention and therefore I do not limit myself to what is shown in the drawing and described in the specification, but only as indicated in the appended claims.

Faving thus ully described my, said invention, what I claim as new and desire to secure by Letters Patent, is:

1. The method of cementing a tungsten carbide block to a base which comprises ap plying a cementing compound to the base, pressing the tungsten carbide block thereto, covering the block and the base with a quantity of boric acid, subjecting the whole to a temperature sufficient to melt the boric acid to provide a coating to insulate the block and the base from injurious gases in the furnaces, and then heating the assembled base and block to a temperature suflicient to melt the cementing compound, and removing the shank and tool and subjecting the cementing compound to a pressure while it cools, substantially as set forth.

2. The method of cementing a tungsten carbide block to a base which comprises applying a cementing compound to the base, pressing the tungsten carbide block thereto,

coverin the block and the base with a quan-'- tity of oric acid, subjecting the whole to a temperature suflicient to melt the boric acid, and then heating the assembled base and block to a temperature suflicient to melt the cementing compound, removing the shank and tool and subjecting the cementing compound to a pressure while it cools, and j acketing the assembled unitto prevent rapid cooling, substantially as set forth. 3. The method of cementing a high speed cutting tool to a base which comprises applying a cementing compound to the base, applying the tool thereto, covering the base and the tool with a boric acid derivative, applying a temperature suflicient to melt the boric acid derivative to coat the tool and the base,

tive', subjecting the block to-a temperature suflicient to melt the boric acid derivative, then subjecting the block and the base in a closed chamber to a temperature suficient to melt the cementing compound, then placing the base and the block in a device whereby they may be pressed together and covering the whole with a powder to allow them ing, the base and the block in a device where by they may be pressed together and covering the whole with a powder to allow them to cool slowly, and insulating the block and the base against contact with the pressing means to prevent a sudden cooling of the block, substantially as set forth.

In witness whereof, I have hereunto set my hand at Indianapolis, Indiana, this 14th day of November, D. nineteen hundred and twenty-nine.

WILLIAM R. CHAPIN.

and subjectin the whole assembly to a temperature sufficient to meltthe cementing compound, and sub'ecting the tool and base to a pressure to hol them tight together during the cooling of the cement, substantially as set forth.

,4. The method of cementing a high speed cutting tool to a base which comprises applying a cementing compound to the base, applying the tool thereto, covering the base and the tool with a boric acid derivative, a plying'a temperature sufiicient to melt the lioric acid derivative to coat the tool and the base, subjecting the wholev assembly to a temperature suiiicient to melt the cementing compound, subjecting the tool and base to apressure to hold them'tight-to ther during the cooling of thecement, an applying an insulating powder about the tool and the base to prevent too rapid cooling, substantially as set forth.- i

5. The method of ceinenting a block of hollowing out the base to iit the said block applying cementing compound to the said hollow, placing the block in, the hollow and covering the same with a boric acid derive-

Images