US2626221A - Process of applying hard surfacing material to metal bodies - Google Patents

Description

Jan. 20, 1953 c, LLIO 2,626,221

PROCESS OF APPLYING HARD SURFACIN MATERIAL. TO METAL BODIES Filed Feb. 26, 1948 CHARLL'J hf. ELL/0T7 MIVENTOR ATTORNE Y5 Patented Jan. 20, 1953 PROCESS OF APPLYING HARD SURFACING MATERIAL TO METAL BODIES.

Charles H. Elliott, Houston, Tex., assignor to Reed Roller Bit Company, Houston, Tex., a corporation of Texas Application February 26, 1948, Serial No. 10,974

2 Claims.

plication of granular hard materials to the surface to be hardened.

Heretofore it has been the practice to coat the surface to be hardened with a pasty binder and then embed the granular hard material in the binder. Acetylene hand torches are then employed to heat a small increment of the surface at a time to the point that the granular heating material becomes bonded to the surface. This process is known as puddling in the granular material. From-the standpoint of service, materials processed in this fashion have been satisfactory, but the process is both slow and expensive.

It has been proposed to utilize burner heads having a plurality of jets for playing flames over the surface to be hardened while rotating the flame with respect to the surface to be coated to uniformly distribute the heat to the entire surface. This process has been carried out with some degree of success but has not proved entirely satisfactory in every instance, apparently because the application of heat to the surface to be hardened has not been entirely uniform.

An object of this invention is to provide a process for surface hardening solid metallic bodies wherein substantially all of the area to be hard- .ened is subjected to continuous heating while the heater and work piece are moved with respect to each other in a rotational sense with the work piece serving as the center of rotation and in a reciprocal sense along a straightline. I

Still a further object is to'provide a process for surface hardening solid metallic bodiessuch --as roller cutter bits wherein a granular hard substance is bonded to the surface to be hardened by playing flame continuously oversubstantially the entire surface to be hardened while moving the flame with respect'to each other as if the body were rotated about an axis passing through the body and reciprocated along a straight line. Yet another object is to provide a process for surface hardening roller cutter bits wherein a flame is played over substantially the entire area of the 2 surface to be hardened while the flame and the body are moved with respect to each other as if the body were rotated about its axis and reciprocated along such axis.

Other and further objects to this invention will appear from the description.

In the accompanying drawings, which form a part of the instant specification and are to be read in conjunction therewith and wherein like reference numerals are used to designate like parts in the various views:

Fig. 1 is a schematic fra mentary side elevational view of apparatus embodying this invention with parts shown in section for added clarity:

Fig. 2 is a bottom plan view with parts in section of the apparatus shown in Fig. l. The process of applying hard surfacing material in accordance with this invention includes the steps of securing the hard surfacing material to the metal surface to which it is to be applied. A binder of glue-like substance is employed to retain the surfacing material upon the surface to be hardened and the oil, water or other liquid vehicle is driven from the surface by suitable preliminary heating. The coated surface is then heated, preferably with a gas flame, while the surface and the flame are kept moving with respect to each other as if the body to be surface hardened were rotated about an axis through the body and reciprocated along a straight line passing therethrough. During this heat ng operation. heat rays emanating from the surface under treatment are intercepted by a light or heat ray sensitive element and the flame is controlled in accordance with the intensity of such intercepted heat rays so as to turn off the flame, when the intensity of the heat rays reaches a value which indicates that the surface to be heated has reached the desired temperature at which the hard surfacing material becomes bonded to 'th surface of the body treated.

Any suitable flame may be employed so long as it is given a configuration, such that it will heat the metal surface to which the hard surfacing material is to be applied, and the body-of metal adjacent such surface substantially evenly and uniformly. It is desirable that the surface to which the hard surfacing material is to be applied be heated to a temperature somewhat higher thanthe remainder of the body on which it is carried, but no great differential is required.

It has been found that the uniformness of application of heat to the surface to be treated is unexpectedly increased when the surface to be treated is not only rotated with respect to the flame but is also reciprocated somewhat along a straight line, preferably the axis of rotation. At any rate, it has been found that the end result of the hardening treatment is improved by this reciprocal movement and it is believed that this is due to greater uniformity in heating so that substantially the entire area to be hardened will reach the desired temperature simultaneously without overheating any portion of it.

Where the member to be treated is a roller cutter of an earth drill bit which has an axis about which the parts to be surfaced are distributed more or less regularly, it is desirable that the means for moving the surface with respect to the flame be in the form of a spindle which may be used to rotate the member and which may be axially reciprocated. I

Referring more particularly to the drawings, an apparatus capable of carrying out the process described is illustrated diagrammatically, and in this instance the body to which the hard surfacing material is to be applied is in the form of aro'ller cutter I for an earth drill bit. This cutter has radially extending teeth 2 on its outer periphery and in the usual course of procedure in manufacturing these cutters, it is desired that one flank 3 of each such tooth be provided with a hard surface as by the application of tungsten carbide thereto and the bonding of *the tungsten carbide to the metal of the cutter.

The cutter is mounted upon a spindle or work piece holder 4 for rotation thereby and is'secured upon this spindle by means of a cap screw 5 and washerlfi The speed of rotation is not critical but it has been found that a speed of between 25 and 300 R. P.'M. is suitable for the purpose of surfacing the teeth of the cutter of 6 to 8 inches in diameter.

Shaft 4 is journaled in a support 50'and preferably has a ball bearing mounting therein. The

rotated and moved axially at the same time.

The mechanism for imparting axial movement to the shaft includes bar 54 pivoted to a support at 55 and :having at one end a roller which operates in groove 4b at the upper end of shaft 4. The-other end of bar '54 is connected to crank 56 by crank arm or link '51; The crank is secured to the shaft or rotatable member 58, by a suitable bolt. Member .58 may be rotated by-a suitable prime mover not shown in the drawings. With this arrangement it will be readily understood tha't'rotation of 'member 58 will effect axial reciprocation of the work holder or shaft '4 to reciprocally shift the work piece 'I along a straight line, which, in this instance, is the axis for rotation of the'work-p'i'ece.

On each side of the cutter, as mounted upon the spindle 4, there is shown in the illustration suitable supports 1 and 8, similar to a lathe bed,

and adapted to receive supports 9 and Ill mounted forsliding movement toward and away from the spindle 4. The supports '9 and I9 are hollow, and connected with the hollow chamber thus formed in the support'9 are conduits [I and 12 for conveying to -such chamber a combustible fuel such as acetylene gas or the like and, if necessary, oxygen for supporting combustion. Similarly conduits l3 and I4 are connected to the hollow interior of support 10 for supplying a combustible mixture thereto.

Support 9 carries a large burner head [5 and on lateral arms extending from the burner head are carried relatively small auxiliary burner heads l6 and I1. Burner head I5 is positioned to direct a flame radially inwardly toward cutter teeth 2. The auxiliary burner heads are positioned to direct a flame against opposite sides of the body of the cutter adjacent the roots of teeth 2. The auxiliary burner heads are supported from a large burner head and form part thereof by means of hollow arms l8 and I9, respectively.

.Arm It] carries a large burner head 20 directly opposed to the burner head and positioned to direct a flame radially inwardly toward the teeth 2. Auxiliary burner heads 2! and 22 are carried by head and are positioned on opposite sides of the cutter body adjacent the roots of teeth 2.

These auxiliary burner heads are supported by hollow arms .23 and 24, the mounting being similar to that of the mounting of the auxiliary heads 1-6 and IT.

' In order to prevent the back dash of flame into the burner heads, where gas such as acetylene, is employed, there is built into each burner head aflame arrester structure which is preferably .cooledby water .or the like. This coolant is applied to large burner head l5 through conduits 25 to heater 20 through conduits 26 and auxiliary burner heads IE, IT, 2| .and 22 .by conzduits .21, .28, .29 and 38, respectively.

Burner head I 5 is provided with burner tips '31, preferably adjustable, and arranged somewhat in the form of an arc to increase the uniformity of the application of heat to the teeth of the cutter. Large burner head 20 is provided with tips .32, having a like arrangement. Auxiliary burner heads [6, l1, 2| and 22 are provided respectively with burner tips 33, 34, .35 and 36. These latter tips are adjusted to such a position that they will apply heat to those portions of the body adjacent-to the teeth at a rate which willheat such portions of the body of the. cutter at substantially the same rate that the teeth are heated. The opposed tips 33 and 34, 35 and 36 are spaced sufficiently far apart to permit the slight reciprocal movement of the work piece along its axis.

It will be seen that with this arrangement of burner tips that flanks 3 of cutter teeth 2, as well as adjacent cutter surfaces, will be substantially uniformly heated, the rotational and reciprocal movement between the flame and cutter adding to. the uniformity of heat distribution over the surfaces to be treated.

Thesupply of gas and oxygen through conduits I l [2, I3 and i4 may be manually controlled by suitable valves such as 31 and 38 and additionally are controlled in accordance with this invention by means of an automatic valve 39 which may be of any suitable well-knowntype such as the slide valve-illustrated having a double ported slide 40 therein. It-will beseen that this slide 40 is constantly urged toward its right hand position by spring 4| and when in its right hand position, it will shut off the supply of oxygen and gas to all burners. This valve is intended to be moved to its left hand or open position, in which it is illustrated, by a suitable electromagnet 42 to which power is supplied from a suitable source such as the battery 43. The supply of this power to member 42 'iscontrolled by a relay having a switch arm M and an electromagnet'45, or by any other 5.. conventional device for closing and opening the battery circuit in response to changes in voltage supplied thereto. With the switch arm in illustrated position, electromagnet 42 will beenergized and the valve 39 opened, but when sufflcient current flows through the electromagnet 45, relay arm 44 will be moved to the right and the circuit to the electromagnet 42 opened permitting the spring 4| to close valve 39 and shut off the flames.

The current for electromagnet 45 is supplied by thermopile 46, within a suitable housing 41, and properly positioned, with respect to lens 48 so that heat rays emanating from the teeth of cutter I will be focused upon thermopile 46. This thermopile may be incorporated in a closed circuit, including magnet 45 and recording indicator or ammeter 49. Ammeter 49 may be calibrated in terms of the temperature of that part of the cutter surface from which the heat rays intercepted by the thermopile emanate.

A specific example of this invention has to do with the coating over of the flanks 3 of the teeth of roller cutter l for earth drilling bits with granular tungsten carbide. In this example the surfaces desired to be coated are first covered or painted with a pasty water glass solution and the tungsten carbide in granular form with grains of the size to be applied to the surfaces of the teeth, is sprinkled upon the sodium silicate coating. The sodium silicate with the granular material embedded therein is then thoroughly dried, and while under some circumstances it may be sufficiently dried in air, preferably where the later heat treatment is to be rapid the sodium silicate is subjected to substantial heat in order to drive off as much of the absorbed moisture and water crystallization as possible.

In order to prevent flaking of the binder from the covered surfaces during the drying of the binder, the heating should be from the body outwardly. By this means the moisture on the inner portion of the binder is first driven off before the outer coating becomes substantially solidified facilitating escape of the volatilized vehicle. This may be accomplished by use of infrared rays directed upon the body or cutter. The proper drying may also be accomplished in an oven employing an induction heater to heat the body of the cutter.

The dried and covered cutter is then placed upon spindle 4 and secured in place by cap screw 5 and washer 6. The various burners are started and spindle 4 is rotated and reciprocated axially whereby the heat from the flames is uniformly distributed to the surface of the cutter to be heated.

The heat rays from the cutter teeth, which will heat a little faster and hence are always at a slightly higher temperature than the body of the cutter, will pass from the teeth just as they emerge from the flame of one of the large burners and will be focused by lens 48 upon thermopile 46. The thermopile and relay coil 45 are proportioned so the current from thermopile 46 will not actuate the relay until the intensity of the heat rays intercepted by the thermopile corresponds to the intensity of such rays when the surfaces of teeth 2 will just begin to alloy with the tungsten carbide and fuse along that part thereof which is in contact with the tungsten car bide. When this temperature of the teeth surface is reached relay 45 will automatically .open to de-energize electromagnet 42, whereby spring 4| will move valve member 40 to its closed position, cuttin'g'ofi the source cf'combustible 'mix-' The cutter is then permitted drous sodium silicate serves asra binder to retain the tungsten carbide particles upon the cutter teeth while the metal of the cutter teeth reaches its requisite temperature for the bonding of the tungsten carbide materials thereto. I

It will'be appreciated that by this invention a process of applying hard surfacing material to a metal surface has been provided wherein it is possible to accurately control the application of heat to the metal surface and wherein the surfaces treated will be uniformly heated due to the arrangement of burner jets and the rotational and axial reciprocal movement of the work piece. By maintaining the flames employed in the heating operation as reduction flames the surface of the cutter will not be excessively burned or oxidized.

It is to be understood that while this process is especially adapted to the hard surfacing of the teeth of rotary cutter for earth drilling bits, the process and apparatus of this invention are not limited to such use but may be employed in many other types of work where it is desired to surface harden material wherein the application of heat is relied upon and must be uniformly distributed over the surface treated.

Having described the invention, what is claimed 1s:

1. The process of applying hard surfacing material to the teeth of a rotary metal cutter for an earth drilling bit, which comprises covering the teeth with a pasty sodium silicate solution, embedding hard surfacing material in a granular form upon the covered surface, heating the sodium silicate by heating th metal of the cutter and utilizing the heat radiating from the metal of the cutter to drive substantially all of the liquid vehicle from the sodium silicate, rotating the cutter and axially reciprocating the cutter while playing a flame upon said teeth, impinging the heat waves emanating from said cutter teeth onto an electric heat responsive element thereby indicating an electric voltage proportional and representative of the intensity of said heat waves, and stopping the heating of the cutter when said electric voltage attains a predetermined value indicating the temperature of the surface of the cutter teeth, at which the metal of the surface forms a bond with the hard surfacing material.

2. The process of applying granular tungsten carbide to a surface of a metallic body, which comprises covering the surface to be hardened with a binder comprising a pasty sodium silicate solution, embedding the hard surfacing material in granular form in the binder cover-ing, applying infrared heat rays to said body to drive substantially all the moisture from the binder solution, rotating the body and axially reciprocating the body while playing a source of heat upon said body to heat the surface thereof, impinging the heat waves emanating from said body surface onto an electric heat responsive element thereby indicating an electric voltage proportional and representative of the intensity of said heat waves and stopping the heating of the body surface when the intensity of said heat waves reaches a. 1.8.1116; indicating; that; the temperature: of the Number the-point ail-which: the,:meta1 of the 1,902,092. surf-ace; W111 become;- bonded; with; the; tungsten. 2043,7211 carbide. $215,576; CHARLES. H. 5 2258394 2,261,228 REEERENCES GIT-ED 2377 541 The following references are of record: in the 5, file of this patent: l0

UNITED STATES. PATENTS 2326103 Number Name Date 2,416,1 I

1,149,917 Jamison et, a1. Aug. 10., 1915 1,280,889 Spang Oct. 8,, 19-18 1,575,635 Meker Mar. 9, 1926 15' Number 1,735,000 Dely- Nov. 12,,1929 540,270 1,824,121: Charlton Sept. 22,1931 596,626

Name; Date,- N0rwood\ Mar. 21-, 1933 wagenhals June 9,1936 Bucknamt e1: a1; Sept. 24, 1940; Janco: 00's., 14,. 1941 Cockrum Nov; 4,,51941 MerIub-Sobel' et a1. Mar. 24', 1942 wissler" Sept. 15', 1942 Wagner Nov. 10, 1942' Quinn June 15; 1943 Snyder Aug. 10, 1943 Beck Feb. 18, 1947' FOREIGN PATENTS" Country Date GreatBritaJin- Oct. 10-, 1941 Great? Britain Jan. 7, 1-948

Claims (1)

1. THE PROCESS OF APPLYING HARD SURFACING MATERIAL TO THE TEETH OF A ROTARY METAL CUTTER FOR AN EARTH DRILLING BIT, WHICH COMPRISES COVERING THE TEETH WITH A PASTY SODIUM SILICATE SOLUTION, EMBEDDING HARD SURFACING MATERIAL IN A GRANULAR FORM UPON THE COVERED SURFACE, HEATING THE SODIUM SILICATE BY HEATING THE METAL OF THE CUTTER AND UTILIZING THE HEAT RADIATING FROM THE METAL OF THE CUTTER TO DRIVE SUBSTANTIALLY ALL OF THE LIQUID VEHICLE FROM THE SODIUM SILICATE, ROTATING THE CUTTER AND AXIALLY RECIPROCATING THE CUTTER WHILE PLAYING A FLAME UPON SAID TEETH, IMPINGING THE HEAT WAVES EMANATING FROM SAID CUTTER TEETH ONTO AN ELECTRIC HEAT RESPONSIVE ELEMENT THEREBY INDICATING AN ELECTRIC VOLTAGE PROPORTIONAL AND REPRESENTATIVE OF THE INTENSITY OF SAID HEAT WAVES, AND STOPPING THE HEATING OF THE CUTTER WHEN SAID ELECTRIC VOLTAGE ATTAINS A PREDETERMINED VALUE INDICATING THE TEMPERATURE OF THE SURFACE OF THE CUTTER TEETH, AT WHICH THE METAL OF THE SURFACE FORMS A BOND WITH THE HARD SURFACING MATERIAL.

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