US2040370A - Process of hardening metal - Google Patents

Description

May 12, 1936- w. R. FISHER 2,040,370

PROCESS OF HARDENING METAL Filed June 26, 1955 INVENTOR.

h/ Fancy T llsher- \f ATTORNEY.

Patented May 12, 1936 UNITED STATES PATENT" OFFICE 2,040,370 rnocEss oF HARDENING METAL W. Reuen Fisher, Frankenmuth, Mich.

Application June 26, 1933, Serial No. 677,637

4 Claims. (Cl. 148-14) My invention relates to a new and useful improvement in aprocess of hardening metal and particularly adapted for use in hardening steel and especially high speed steel. With steel and especially high speed steel, it has been found that when the material is raised to a high temperature suflicient for eifecting the hardening operation, because of the action ofthe air and the gases on the material, the steel has a tendency to blister and decarbonize for a depth in some cases ex,- tending from forty to fifty thousandths of an inch so that the surface of the material is damaged to such an extent as to necessitate a removal of the damaged layer or coating after the hardening operation. This removal of the damaged layer is a laborious and expensive operation which can generally be eiected only ina grinding operation, and particularly itis an expensive operation where the material is o f uneven contour. With some types of pieces, lit is impossible to grind -after the hardening operation with, the result that portions of the surface remain in a defective state or condition.

It is an object of the present invention to provide a process whereby hardening of metal and especially steel and high speed steel may be effected without in any manner damaging or disintegrating or deleteriously a'ecting the surface.

Another object of the invention is the provision of a process whereby the material may be raised to any desired temperature and maintained at this temperature without danger of injuring the material since the surface thereof is not affected by any disintegrating action of gases or air.

Another object of the invention is the provision of a process whereby a metal may be raised to the necessary temperature for hardening and maintained at that temperature free from gases ,or air and subsequently quenched while still maintained in the gas and air free condition.

Another object of the invention is the provision of a container in which the material may be positioned and maintained free from contact with gases-and air during the heating operation and in which it may be quenched subsequent to the heating operation.

Another object of the invention is the provision of a process whereby the material to be hardened may be surrounded by heat conducting material during the heating operation which will serve to effectively conduct the heat to the workpiece being heated while at the same time serve to prevent access of air and gases to the workpiece.

Another object of the invention'is the provision of a process of hardening metal whereby, while the workpiece may be heated to and maintained at the desired temperature for a specied length of time free from air and gases, it may also be quickly quenched after the heating operation.

Another object of the invention is the provision of a process of hardening metal and especially steel whereby the metal may be quenched by Water after the heating operation.

Other objects will appear hereinafter.

The invention consists in the combination and arrangement of parts hereinafter described and claimed.

'I'he invention will be best understood by a reference to the accompanying drawing which is a longitudinal central vertical sectional view of a container or cartridge used in carrying out the process.

In the drawing I have illustrated a sleeve or tubular body I which is closed at one end by a cap having the portion 8 adapted to snugly enter 20 the portion I at one end and provided with the peripheral flange portion 9 which is cut away on one face adjacent its periphery as at I0 to provide the beveled surface I I of the end of the tube or container 1, forming a V shaped peripherall groove in which the Weld I2 may accumulate when these parts arewelded together. The workpiece is represented by the body I3 and this workpiece is enclosed in the container or cartridge or tube I packed in a packing I4 of suitable heat conduct- 30 ing material which will serve to exclude air and gases from the container, such as iron filings, graphite or the like. A closure for the opposite end embodying the portion I5 which snugly engages in the end of the sleeve 1 is provided. The 35 peripheral ange I6 is cut away as at I 'I to cooperate with the beveled end I8 of the tube to provide the V shaped groove for reception of the Weld I9. When the material I 3.is sealed in the container, packed in the packing I4, the container or cartridge is then placed in a suitable oven or other source of heat and raised to the desired temperature and maintained at this temperature for the desired period of time. The packing I4 being formed from material of high 45 thermal conductivity will serve to readily raise the body I3 to the temperature of the oven. Since no air or gases have access to the workpiece I3, it is not necessary that particular attention be vpaid to the 1engtn of time the workpiece la is 50 maintained at the elevated temperature asno injury or damage to the surface of the workpiece will be eiiected.v In this regard the present process has a marked advantage over known processes because with known processes it is ordinarily necessary to remove the workpiece from the ovenk after the elevated temperature has been maintained for a definite period of time as further heating of the workpiece will result in further blistering or scaling of the surface and a decarbonization thereof. ,f

After the workpiece has been raised to the desired temperature, it is not necessary to remove the workpiece from the cartridge in order to quench it as the quenchingmay be effected while the workpiece is in thefcartridge. The quenching is, of course, most eicient when the packing I4 is of high thermal conductivity. Furthermore, Since the workpiece I3 is`not brought directly into contact with the quenching material, it becomes possible to quench by use of Water instead of oil or air although it is believed obvious that either oil or air may be used. The advantage, however, is in the fact that water may be used for quenching.

It is of course obvious that the packing material I4 must be of a material possessing a higher melting point than the workpiece I3 which is to be heated.

A workpiece treated inthis manner will be found to possess all of the desired characteristics and when removed from the cartridge or container its surface will be free from any blistering, scaling or decarbonization. The workpiece does not need to be sandblasted as it has a satin silver finish when removed from the container. As a result of this, a workpiece to be hardened may, be-

fore the hardening process be finished to within a few thousandths of an inch of the desired dimensions so that a considerable saving in labor is thus eiected. Furthermore, if the workpiece is to be nitrated, the same may be effected without grinding the workpiece after the hardening operation because of the freedom from decarbonization or scaling.

In removing the workpiece from the container, it is but necessary to mill or machine oi the tube I on the dotted line whereupon the closure may be removed. It is evident therefore that the body 1 may be used again by be'veling off its end prior to the welding of the closure therein.

While I have illustrated and described the preferred form of construction of my invention, I do not wish to limit myself to the precise details of structure shown, but desire to avail myself of such variations and modifications as may come within the scope of the appended claims.

Having thus ldescribed my invention, what I claim as new and desire to secure by Letters Patent, is:

1. A process of hardening materials consisting in enclosing the metal to be hardened in a container, surrounding the metal by an air excluding heat conducting material in friable form, and sealing the container against entry or escape of gases, raising the container with the contents thereof to the desired temperature flor hardening purposes, and subsequently to the heating and, prior to the removal of the metal, quenching the metal while in the container.

2. The process of hardening a metal piece consisting in surrounding the material with a packing of air and gas excluding, heat conducting material, sealing the piece while so packed against entry or escape of gases, raising the piece to an elevated temperature, and subsequently quenching the same while surrounded by the packing.

3. The process of hardening a metal piece consisting in enclosing the metal piece in a packing of gas excluding, heat conducting material with-` walls of said container; welding closures on said container for preventing escape of gases therefrom or thereinto, and raising the temperature of the container with the contents thereof to the desired temperature for hardening purposes, and, subsequently to the heating, quenching the metal piece while in the container and prior to the opening of said container. y

w. REUEN FISHER.

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