US2074038A - Diamond embedded abrading tool - Google Patents

Description

March 16, 1937.

F. H. WIL LEY DIAMOND EMBEDDED ABRADING TOOL Filed May 29, 1955 I 2 Sheets-Sheet l INVENTOR.

72;. H m'lle q A TTORNE Y.

Margh 1 6, 1937. H. WILLEY I 2,074,038.

DIAMOND EMBEDDED ABRADING TOOL 2 Sheets-SheetZ Filed May 29, 1935 l l h l l PH- IH. II A m, 5 m M WW a M a W. 2 1 y H .HU W v Patented Mar. 16, 1937 V v 2,074,038

U-NiTED STATES PATENT oFFicE DIAMOND EMBEDDED ABRADING TOOL Fay H. Willey, Detroit, Mich.

Application May 29, 1935, Serial No. 24,068

12 Claims. (01. 51-280) This invention relates to abrading, drilling or that, with such sizes as have been suggested, I surfacing tools, theobject being to provide an am enabled to bring the metals to an alloying improved abrading tool. or tip for tools of a hard temperature for a few seconds of time without and tough metal alloy in which a diamond or loss of the diamond as apparently only thesurdiamonds of various sizes may be embedded toface of the diamonds becomes afiected sufficiently is form abrading or surfacing tools, the composito permit the carbon at the surface to be taken tion being of such character that the diamonds up by the tungsten and thus provide what may be are so securely seated in the alloy as to prevent termed an integral seat; that is an actual codisplacement or unseating by pressures or impact heslon between the diamond and the metal rather less than that causing fracture of the diamond than a mere adhesion therebetween as is the and thus provide a more highly ellicient abrading u t at s t n mp a ure f approximat ly tool and one of longer life than has heretofore 350 C. b secured It is further an object of the invention to pro.-

' The invention alsohas for its object to pro- Vide a w n p v pr c s for the manuyide an improved process for t formation of facture of a tool of the character stated which 16 such tool whereby the surfaces of the diamonds consists irrthe placing of a p t or aphite gi p vwrbcm t t alloy and t unite th lined mold having a recess of the desired depth diamond and t alloy as distinguished fmm a and shape in cross section between the electrodes mere adhesion or wetting" of the diamond surof a Welding machine, placing a Small quantity 20 ;f.ace by the metal as has heretofore been the 0f the powdered tungsten, carbon, d nickel 20 method'in this art 7 with diamonds in the cavity, tamping the same,

' 'A feature of the invention is involved in the adding in succession all quantities of the formation of a diamond abrading or cutting tool powdered material d d am nds, a h charge "byhcating powdered tungsten (W), carbon (0). being tamped in Succession until a b y o the nickel (N1) alloying temperature, t compacted powder and diamonds of the desired 25 carbon content being insufilcient to satisfy the length is secured, n. While light Pressure s ptungsten and the diamonds being distributed plied and the material occluded to atmosphere, therethrou'gh; the heating, as hereinafter deheating h mold, d the prepared material to a scribed, being step by step under pressure to a Sumclently high temperature ximately 800 l'fi'nal temperature of the order of 1700 degrees C. degrees to start gas formation and discharge while occluded to atmosphere to prevent oxida of included air and also, due to the pressure, in-

I n and for a short period of time sufficient to creasing f compactness, then cau se the surfaces of the diamonds only to gasify creasing the temperature and Pressure in succesa combine with the tungsten to form sive steps or stages until finally a temperature of ""-sten -carbide seat in cohesive relation with the the order of 1700 degrees Q and a final Pressure dmmon of approximately 10,000 pounds per square inch a heretofore been proposd to form an is attained for a period less than that productive r- -nbr'ading and surfacing tool by mixing diamond of liquefaction of the-metals- ;dust' and diamond particles in a material such By the described manner of compacting is-powdered tungsten-carbide and submitting to the material and heating in Successive stages 40 s sinterlng temperature. My improved tool disunder increasing tempqr-ature and pressure the .finmlishes from such former tools in that the voids usually occurring in the material at sinterdiamonds used are not what is known to the ing temperature are prevented and an actual altrade as diamond dust or diamond particles but Joy of the metals in plasfic state is Secured" are true diamonds usually way of example The process therefore distinguishes from former but not of limitation, more than one-sixteenth pmcesses wherein the material maybe compacted of an inch across the surface in any direction under pressure mold and with the .and ordinarily nearly one-eighth of an inch and ggg g g gflf gg fis nioldtplaced m oftentimes with diamonds of such size, there is m med g th fi ey incorporated a diamond at the very tip or the tool p process e 00 is completed m the matoriallv greater in size surround d b th welding machine first using the machine and the mm diamonds a e y 9 ram or plunger to temp and compact the material and then to apply the pressure under the heat Mlulc, in general, the invention is not limited in the successive stages, as before mentioned, and

tofthe size of t e diamonds yet it is pointed out at the final heat, the article is completely formed requiring only removal from the mold and the surface cleaned. The process is therefore more rapid than former processes of which I have any knowledge, is of less labor cost and a more serviceable tool ls secured due to the density of the product and the seating of the diamonds in place which are so solidly secured that fracture will occur along the cleavage plane of the diamond before it can be loosened.

These and other desirable objects and features of the invention are hereinafter more fully described and claimed, it being understood that the specific embodiments of the invention described are by way of illustration and not of limitation as the methods involved and the components of the alloy may be varied considerably without departing from the spirit and scope of the invention.

In the accompanying drawings:

Fig. 1 is a side elevation partly in section of an electric welding machine suitable for manufacture of my improved tool or tip.

I Fig. 2 is a section taken on line 2-2 of Fig. 1.

Fig. 315 an elevation taken from the right hand side of Fig. 1.

Fig. 4 is an enlarged section showing a graphite lined mold with the formed tip therein.

Preferably, the invention is described in conjunction with the use of tungsten as an element of the alloy but other elements that have the necessary hardness and tendency to absorb carbon may be utilized with any of the iron group such as nickel, cobalt or iron. The preferred composition is tungsten (W), carbon (C), nickel (N1), the tungsten being unsatisfied with carbon and the nickel being used to form an alloy to provide toughness and preventative of cracking or shatter of the tool through impact or shock.

' The invention may be best understood from the following description of the method of producing the article.

The mechanism for producing the article may be an electric welding machine such as is shown in Fig. 1 having the water cooled electrodes l and 2. The crucible, as indicated at 3, is positioned therebetween and may rest upon a water cooled base t. The electrode 8 is supp rted in a carrier 5 which is movable on the base of the machine by means of a hand wheel l, the electrode i being retracted to permit introduction. of the crucible and then moved forward by means of the screw until the crucible is held in pressure contact between the electrodes. The crucible may be carbon or graphite or a metal crucible lined with carbon or graphite. In either case, the, graphite element is recessed as indicated at ii in Fig. 4 and is preferably slightly coned at the bottom 9. A vertically reciprocalble plunger it has a molybdenum or other hard metal tip for entering the recess and is supported by the holder i i reciprocable in the bracket i2 attached to the standard It which in turn is supported on the base 6. The bracket it supports the holder from lateral displacement and sustains it in truly vertical position. The upper end of the standard l3 has a chambered head It secured thereto within which is a coiled spring It. Theupper end of the chambered member is threaded to receive a plug it having a central projection l'l engaging in the end coil of the spring and centering the same and this may be adjusted to increase or decrease the normal tension on the spring.

At the bottom of the chambered member I 4 is a spring seat I8. having a projection entering the bottom coil of the spring to center the same and the member i8 is centrally threaded to receive'a threaded sleeve l9 which is adjustable longitudinally in the spring seat [8. A stub shaft 20 extends through the sleeve and is secured in place by the nut 2|. The lower end thereof is in the form of a yoke 22 which receives a plate 23 pivoted thereto by a pin 24. The opposite end of the plate is formed with a yoke 25 in which an end of the link 26 is pivoted, the opposite end being pivoted to the upper end of the holder II by the pin 21. To the plate is secured a handle 28. The link and plate form a toggle between the yoke 25 at the upper end and the holder Ii at the lower end and by operation of the handle, the holder and the plunger member or tamp I 0 may be reciprocated. The normal position of the parts is indicated by dotted lines in Fig. 1 and when pressure is applied to the material in the crucible I or mold, the handle 28 is moved downwardly as indicated by full lines in Fig. 1. In order that pressures to be applied may be determined, the screw seat I8 is provided with a finger 29 extending through a slot 30 in the chambered member 14 and a calibrated gauge plate 3| is secured to the member it across which thefl'nger is movable enabling the operator to determine the pressure applied by downward movement of the handle 28. The pivot pins 24 and 21 extend to one side of the leverage mechanism as shown in Fig. 3, and a coiled spring 32 is attached thereto tending normally to hold the handle up with the plunger i0 out of the recess of the crucible as shown in dotted lines in Fig. 1.

No attempt has been made to show the electric circuit for the electrodes or the means of supplying water thereto for cooling the same, such elements being usual in welding machines.

One of the purposes of use of the welding ma-.

chine or like instrumentality is to enable the article to be completely formed therein. It has heretofore been the practice to compact a material and even to heat it somewhat in a machine of this character and then remove the mold or crucible and complete the temperature treatment in a furnace or to remove the material after heating sufliciently to retain its shape and subjecting it to a sintering temperature in a furnace. However, in the method hereinafter described and in order to secure a tool of the proper hardness and density, the entire treatment of the material is completed in the welding machine thus not only saving the labor cost of handling but also saving considerable equipment and permitting the tool to be completed under a high pressure while it is at a temperature above the sintering temperature and it also enables the entire process to be performed while the material is prevented from oxidation as it is occluded from atmosphere during the forming operation and also by being encased in a graphite crucible and at the temperature attained creates a. reducing atmosphere. This in turn unites with the oxygen present to form carbon dioxide which is driven off as a gas by the pressure obtained thereby removing the oxide from the material.

As an instance and not by way of limitation, I form a powder containing approximately to 70 per cent tungsten (W) and 8 to 5 per cent carbon (C) and the balance nickel (Ni) and ball mill the, same for a number of hours sumcient to produce a'very fine powder. Usually theinaterial is placed in the mill in more or less of a granular form and ball milled for upwards of hours. Where a tool having a high abrasive quality is required, diamonds are utilized and one method of procedure in forming a tool embedded with diamonds is as follows:

A diamond of any desired size, preferably of larger size than the remainder, is first placed in the crucible in which it centers due to its having a coned seat. Additional small diamonds maybe placed about this central diamond if desired.

In either case, subsequent to placement of the diamond or diamonds, a small quantity of powder of the above composition, or the equivalent of the above composition, is placed on the diamonds and tamped as before stated. The diamonds are' protected from being broken due to the cushioning efiect of the powdered material placed thereon. When the first tamping has been completed, several other small diamonds are placed on the top thereof, an additional charge of powdered material placed thereover and tamped, and thus,

in several steps or stages, the material is brought" up to the required depth in the mold to form an article of the desired length. Subsequent to tamping, current is turnedv on during application of the pressure by the tamping implement l0 until at a temperature of about 800 degrees C. is attained which may be determined by color or otherwise which starts the gasiflcation and drives oif included air and then it is allowed to cool to below said temperature. Then a higher pressure The diamond is therefore held in place by practically an integral association of the diamond. tungsten and nickel. This association -is so complete that I have in many experiments attempted picking the diamond out of thematerial but in every instance of a tool made under the high pressures and temperatures and manner hereindescribed, it is not possible to unseat the diamond as only particles thereof will break out leaving particles of thediamonds in the surface of the recess.-

It is apparent from an examination of the completed article that the diamonds give up carbon to the tungsten at the surface forming a thin "skin of a very hard tungsten-carbide encasing the diamond which is readily distinguished by the unaided eye from the contiguous metal with which it is united.

I prefer to use diamonds not smaller than would pass a 20-mesh screen and suchdiamonds, when embedded in the metal by my improved process, appear in a whole state in the finished article and apparently uninjured in structure by the heat and pressure to which they have been subjected. i

The method above described results in the formation of a tip of longer life than the usual sintered tungsten-carbide tools of the prior art due to greater compactness, less liability of fracture and greater hardness and when employed with diamonds as in the formation of the drills or abrading tools for the trueing of the grinding wheels and such general service as is required in the industrial arts, I have provided a diamond embedded tip which, in so far as the metals are concerned, has all of the desirable qualities above mentioned in respect to the alloy and due to'the inclusion of the diamonds has a higher abrading characteristic with practically no liability of diamonds becomingunseated as it is not possible to unseat the diamonds except by fracturing the same under anexcessive pressure and even then they are not truly unseated. Thus the tool is of a quality highly desirable in the arts as its efiflciency is not destroyed by loss of diamonds in the ordinary uses to which the tool is subjected and thus may be efliciently used through a much longer period of time than the usual diamond embedded tools of the prior art which are usually sintered and thus have a considerable number of voids and are more brittle than a tool formed after the manner above described in which the material is actually alloyed and practically free from voids.

It is also pointed out that the percentage of tungsten, nickel and carbon may vary somewhat even more than ten per cent above or below the percentages hereinbefore specified, and if one beincreased in percentage another may be reduced in percentage depending entirely upon the character of the tool to be produced. A tool less hard may be used for some operations and of greater hardness for others may be produced and this is usually secured through increasing or decreasing the carbon content. with a diamond embedded tool, I prefer to use as a base a tungsten (W) and thus even though some carbon be utilized in the composition and ball milled as described, the composition still has a high avidity for carbon which is a desirable characteristic in the manufacture of a diamond embedded tool. A major feature of the invention resides in the use of a high degree of pressure at alloying temperature of the metals used, which temperature and pressure so far as I know, has not before been used in the manufacture of diamond embedded tools of this general type.

From the foregoing description it will be realized that the charging of the crucible by successive stages with diamonds and the powdered material, provides a very compact powdered mass prior to application of heat and then by heating and cooling by successive stages of increasing temperatures and pressure up to an alloying temperature and pressure of approximately 10,000 pounds per square inch, great compactness is secured and a tool having a highly carburized surfaceis provided and one of the extreme hardness coupled with toughness preventative of fractureunder normal conditions of operation and use and free from the defects of the sintered compodiamond embedded tool will, at the temperatures arid pressures given, tend to take carbon from the diamond surface and thus unite the diamond and the metal by what may be termed partial graphitization of the diamond. The invention also is not confined to nickel as an element but it is the preferred element of the iron group and in my experience is productive of the most satisfactory tool.

It is further evident from the foregoing description that major features of the invention reside in the formation of an alloy of metals such as tungsten and nickel with insuflicient free carbon to satisfy the tungsten, the alloying being performed while the material is occluded to atmosphere and the diamonds in place in the ma- 10 terial; that the entire series of steps, except the ball milling to form the powder, may be performed in a single purpose machine such as the welding machine herein described, and that the completed tool or tip is characterized by carbul5 rization of the tungsten or like material in contact with the diamond or diamonds.

From the foregoing it is believed evident that the described invention, both in method and article produced, differs from the known art in 20 that tungsten having a certain avidity for carbon is first in very finely divided form compacted with diamonds of a material size which has herein been termed whole diamonds (-that is, not diamond dust or diamond fragments heretofore 25 in use). The compacted material is then heated,

preferably by successive stages in order to eliminate included air and gases formed during the heating process, to such final temperature and high pressure that the tungsten will satisfy its 30 remaining avidity for carbon by taking the same from the diamond. If tungsten carbide be used in the process, the carbon content should first be determined in order that the remaining amount of carbon necessary to satisfy its avidity 5 therefor may be known, it being necessary that the avidity for the tungsten for carbon shall not be entirely satisfied in order that in the steps of the process an when at the necessary temperature, the tungsten will take carbon from the dia- L mond surfaces to securely seat the diamonds in the composition. I, however, prefer to use substantially pure tungsten (W) and provide the required carbon so that the avidity of the tungsten for carbon is materiallyless than would tend 45 to absorb the diamond. Thus in the final heating to which the material and diamonds embedded therein are subjected, only a very small skin surface of the diamond can combine with the tungsten. With the whole diamonds as 50 hereinbefore defined, there is considerable surface in close contact with the carbon covered tungsten particles and this diamond encasingportion of the material, due to carbon being taken from the diamond by the tungsten, is extremely 5 hard and has an integral relation with the diamond while between the several diamonds, the

L metal is softer than'at the diamond seat due to lack of carbon at such points and is thus less brittle and more serviceable in use than would be (50 the case if the tungsten throughout the mass were equally saturated with carbon. There is thus less liability of the tool breaking in use and my improved tool is characterized by this extremely hard tungsten carbide seat for the diamonds and 5 the softer and less hard tungsten carbide between the diamonds.

Having thus described my improved composition and diamond embedded abrading tool and the process of producing the same, what I claim 7 and desire to secure by Letters Patent of the United States is-- 1. The method of forming a diamond embedded abrasive tool for use in the industrial arts consisting in first forming and mixing together 75 a fine powder consisting of a major portion of .submitting the material to successive stages of tungsten having its avidity for carbon partially satisfied and the balance nickel, adding a desired quantity of whole diamonds to the powdered material, subjecting the powdered materials containing the diamonds to a temperature of in the 5 neighborhood of 2,000 to 1700 degrees C. while occluded from atmosphere and for a period of time tending to cause the diamonds to give up carbon at the surface to combine with the tungsten and produce a tungsten-carbide seat in 10 cohering relation with the diamonds, the time period being less than that resulting in the liquefaction of the metals.

2. The method of forming a hard metal alloy suitable for tools which consists in first reducing a granular composition consisting of tungsten, a quantity of carbon insufficient to satisfy the avidity of the tungsten therefor, and the balance nickel to a finely powdered form, then placing a small quantity of the powdered material in a graphite mold, tamping the material to mechanically compact the same, adding successive small quantities of the material together with a number of whole diamonds and tamping each of said small quantities in succession until the proper quantity of material and diamonds have been placed in the mold and tamped, then, while under a medium pressure, heating the same to about 800 degrees C. for a few seconds of time tending to cause the materials to give off gas and eliminate air, then permitting the heated material to cool, then, in successive stages of increasing pressure and temperature and cooling, and finally heating the material to above 1200 degrees C. while under pressure sufficient to prevent voids.

3. The method of forming a diamond embedded abrasive tool which consists in first reducing a granular composition consisting of a major portion of tungsten therefor, a quantity of carbon insufficientto satisfy the avidity of the tungsten, and the balance nickel to a finely powdered and mixed condition, placing a small quantity of powdered materialin a graphite mold, tamping the material to mechanically pack the same, placing a small number of diamonds on the compacted material, then adding an additional small quantity of material and tamping the same, then adding another small quantity of diamonds and repeating the operation until the desired length of tool and desired quantity of diamonds are compacted together, then, while under a medium pressure, heating the same to about 800 degrees C. to produce a gas and drive off the included air, then permitting the heater material to cool, then increasing temperature and cooling the material between the stages to a final step of heating the material to above 1200 degrees C. while under pressure of the order of 50,000 pounds per square inch, the tungsten in contact with the mold sur- 6 face and the surfaces of the diamonds taking up carbon therefrom to form a very hard surfaced tool and to encase the diamonds with a tungsten-carbide which is united with the diamond on the one side and with the metal on the other.

4. The method of forming a diamond embedded abrasive tool which consists in providing a thoroughly mixed and finely powdered composition consisting of a major proportion of tungsten, carbon in quantity insufficient to satisfy the tungsten, and the balance nickel, placing the material in a graphite mold together with a quantity of diamonds of a size that will pass a 20-mesh screen or larger, the mold being positioned between the 7 electrodes of a welding machine having a hard metal plunger adapted to enter the mold, placing a carbon button on the top of the material to shield the plunger from contact with the metals, then applying an electric current to heat the material and the mold, while under a medium pressure by the plunger, to about 800 degrees 0., then, in successive stages of increasing temperature and pressure and cooling therebetween,

finally applying a pressure of approximately 50,000 pounds to the square inch while at a temperature of the order of 2000 degrees C. to alloy the material, the tungsten taking up carbon from the diamond surfaces and forming thereabout a thin case of tungsten-carbide.

' 5. The method of forming a diamond embedded abrasivetool which consistsin first forming a fine powder of a metal such as tungsten in major quantity, carbon in quantity less than that required to satisfy the avidity of the tungsten therefor, and the remainder a metal such as nickel, then mechanically compacting the powdered material with diamonds distributed therein in the cavity of a graphite mold having an opening through the surface thereof for insertion of a tamping tool, and then, while under pressure applied by the tamping tool, heating the material gradually by successive stages of heating and cooling under successive increasing pressures and,

temperature until a temperature and pressure is attained sumcient to form an alloy of the metals and to cause carburization of the tungsten particles in contact with the diamond.

6. The method of ,forming a diamond embedded abrasive tool which consists in first forming a fine powder of a metal such as tungsten in major quantity, carbon in-quantity less than that required to satisfy the avidity of the tungsten therefor, and the remainder a metal such as nickel, mechanically compacting the material with diamonds distributed therein in a cavity of a graphite mold held between electrodes of a welding machine and having an opening through the surface thereof for insertion of a tamping tool, then applying pressure by the tamping tool and current to the electrodes to heat the mold and the material to approximately 800 degrees C. to thereby cause the material to become'further compacted and to drive oil. the included air, then cooling the same, then in several successive stages heating under increasing temperature and pressure, and finally heating the material to in the neighborhood of 1700 degrees C. for a period of about five seconds of time to form an alloy of the metals and carburization of the tungsten particles in contact with the diamond surfaces.

' '7. The method of providing an abrading tool or tip comprising mixing a small quantity of whole diamonds of aosize that will pass a 20- mesh screen with a powdered composition consisting of a metal such as tungsten about to 70 per cent, carbon about 3 to 5 per cent, and the remainder a metal such as nickel, then heating the some while occluded to atmosphere through a number of successive stages of heating and cooling under pressure, the first of which is at low temperature and pressure to cause discharge of the included air from the material, and the final stage at a temperature and pressure suflicient to alloy the metals and to form a tungstencarbide at the surfaces of the diamonds due to avidity thereof for carbon.

8. The method of forming a diamond embedded abrading tool consisting in first preparing tungsten with a predetermined amount of carbon less than will satisfy the avidity of the tungsten therefor, positioning whole diamonds in the said body in spaced relation, submitting the diamond embedded material to pressure and heat, attaining at the end of the heating step a temperature of the order of 1700 degrees C., and a pressure sufflciently high to prevent voids and insure intimate contact of the material with the surface of the diamonds to thereby provide a seat for the diamond surface intimately associated with the encasing tungsten of a high degree of hardness through the taking of the carbon from the diamond surface and a less brittle and hard body of the material in the spaces between the diamond seats.

9. The method of forming a diamond embedded metallic composition which consists in forming a very fine powder of the following ingredientsnamely, a major portion of substantially pure tungsten, a quantity of carbon insuflicient to satisfy the avidity of the tungsten therefor and the balance nickel, positioning a desired quantity of diamonds in spaced relation in the powdered material, and then subjecting the powdered materials and diamonds therein to a temperature approximating 1700 degrees C., for a period to cause the diamonds to give up carbon at the surface to the tungsten and produce cohesion therebetween, and applying a sumciently high pressure to the material while at the high temperature to eliminate gases and prevent. voids.

10. A diamond embedded abrading tool comprising a body formed of tungsten, a metal of the iron group, and carbon in quantity less than that required to satisfy the avidity of the tungsten therefor, diamonds interspersed therein in spaced relation to provide an appreciable thickness of metal between adjacent diamonds, the metal in contact with the diamond surfaces forming a seat of a high degree of hardness practically integral with the diamonds and in integral relation with the metal between the diamonds of a less degree of hardness thereby providing a tool wherein the metal body wears more readily than metal in contact with the diamonds.

11. A diamond embedded abrading tool comprising a body formed of tungsten in major quantity, a metal of the iron group in minor quantity, and carbon in quantity less than that required to satisfy the avidity of the tungsten therefor, diamonds positioned in the composition at approximately the surface of the-body and in ap preciable spaced relation one from the other, the metal forming the core of the body and extending between the diamonds being of less hardness than the metal in contact with the diamond surfaces and providing a tool characterized by having a practically non-brittle metal body of less wear resistant quality than the metal in contact with the diamonds.

12. A diamond embedded abrading tool comprising a body formed of tungsten, nickel and carbon, diamonds interspersed in the composition in appreciable spaced relation one from the other, the metal spacing the diamonds being of greatest hardness at the diamond surface thereby providing a tool having a metal body less wear resistant than the metal in contact with the diamonds.

FAY HJWILLEY.

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