US2280029A

US2280029A - Flame hardening control

Info

Publication number: US2280029A
Application number: US375137A
Authority: US
Inventors: John J Crowe
Original assignee: Air Reduction Co Inc
Current assignee: Airco Inc
Priority date: 1941-01-21
Filing date: 1941-01-21
Publication date: 1942-04-14
Anticipated expiration: 1959-04-14

Description

April 14; 1942. l I J. J. CROWE FLAME HARDENING CONTROL Filed Jan; 21, 1941 INVENTOR John J. Crowe ATTORNE Patented Apr. 14, 1942 FLAME HARDENING CONTROL John J. Crowe, Westfield, N. J., assignor to Air Reduction Company, Incorporated, New York, N. Y., a corporation of New York Application January 21,1941, Serial No. 375,137 I 7 Claims.

In flame hardening operations the amount of heat that must be applied to the work is dependent in large measure upon the mass of metal below the surface. With work pieces that are of diiferent thickness at different regions, a progressive flame hardening operation produces nonuniform results unless some provision is made to compensate for the differences in conduction losses at thin and thick sections of the work piece.

One way in which to compensate for the variation in conduction losses as the heating torch progressesacross the work is to reduce the heat input where the work piece is thin and increase the heat input at the heavier sections where conduction' losses are larger. Withheating torches having mat flames and separate gas distributing chambers for the different rows of flames, some of the flames can be turned off to-reduce the heating effectiveness of the torch, but with single-row torches it is not practical to extinguish any of the flames because .that makes the heating uneven transversely of the work piece.

It is an object of this invention to provide an improved and simplified method and apparatus for controlling a heating torch used for flame hardening, and for varying theheating effectiveness of a single row of flames without extinguish-' duction in the rate of heating by reducing the flow of oxygen and fuel gas to the flames.

With this invention the supply of combustible mixture is reduced without necessarily reducing the velocity of discharge of the mixture from the orifices The invention supplies tothe torch an inert gas, that is, a gas that will not react with either the oxygen or the fuel gas. This inert gas is a diluent in the combustible mixture and reduces the heating to some extent by absorbing sensible heat from the combustion reaction. The

principal function of the diluent gas, however, is

portionately less, the greater the dilution of the mixture with inert gas.

Another object of the invention is to provide an improved automatic control for changing the heating effectiveness of a torch during a flame hardening operation.

Other objects, features and advantages of the invention will appear or be pointed out as the specification proceeds.

In the accompanying drawing, forming part hereof: i

Fig. 1 is a diagrammatic side elevation showing apparatus for flame hardening a work piece in A accordance with this invention.

Fig. 2 is an enlarged sectional view taken on the line 2-2 of Fig; 1. Y

A self-propelled torch carriage Ill has wheels II that run on a track l2, or other suitable support. There is a post l3 at the forward-end of the carriage for holding the supporting brackets of the heating torch and quenching head. The front wheels H of the carriage are driven by a motor l5 equipped with governor It that can be adjusted to regulate the speed at which the. carriage moves along the track.

An arm I8 has a split clamp l9 at one end vertically adjustable on the post l3. Another split clamp 20 at the other end of the arm It holds a stud 2| that comprises the supporting end of a bracket 22. A heating torch 23 and a quenching head 24 are connected to the bracket 22 and supported by the bracket in working relation to the top faceof a work piece 26 located along one side of the track l2.

The heating torch 23 is shown in section in Fig. 2 and includes a mixer 23 that screws into the top of a tip block 29. The mixer 28 is constructed to mix three gases, but the invention can use, as an equivalent construction, a conventional torch mixer and a supply conduit for introducing the diluent into the oxy-fuel gas stream somewhere between the mixer and the tip. There is a distributing chamber 30 within the tip block 29 and a single row of jet passages 3| lead from the distributing chamber 30 and open through the bottom face of the torch.

The mixer 28 has-two

conduits

32 and 33 that come together at equal acute angles to the axis of a common mixing passage 34. Fuel gas is supplied to the conduit 32 from tubing 35, and oxygen is supplied to the conduit 33 from tubing 36 connected with the mixer. The diluent gas is supplied to the mixer through tubing 31 that connects with a passage or conduit 38 in the mixer.

This conduit 38 meets the mixing passage 34 in a discharge passage 39. The

passages

38 and 34 preferably make equal angles with the axis of the discharge passage 39. g

The fuel gas and oxygen are supplied to the

conduits

32 and 33 and preferably at pressures that cause the gases to mix in the most desirable ratio for combustion in the heating flames. When gas is supplied through the passage '38, the pressure of the diluent gas reduces the flow of oxy-fuel gas mixture from the discharge passage 39. In the operation of the torch, therefore, the oxygen and fuel gas supply pressures can be left unchanged, and by varying the supply of diluent gas the amount of oxygen and fuel gas supplied to the tip can be varied over a wide range.

The variation in the supply of diluent gas makes little or no change in the gas pressure in the distributing chamber 30. The velocity of gas flow through the jet passages 3| is, therefore, substantially constant even though the amount of oxygen and fuel gas supplied to the flames varies over a wide range. A constant supply of fluid flows to the quenching head 24 through a hose 40.

Nitrogen can be used as the diluent gas. Air is also suitable even though the air is about 20% oxygen, this addition to the oxygen supply is ordinarily not objectionable. When air is used as the diluent gas, it is the inert constituents of the air that serve as the diluent.

A valve 4| commands the tubing 31 and conduit 38 of the mixer. The valve 4| is located in a valve casing 42 connected with the side of the carriage l0. Gas is supplied to the valve casing 42 through a hose 43. The valve 4| has a bias toward closed position, being preferably urged toward closed position by a spring 44.

When the valve 4| is closed, no from the hose 43 to the tubing 31.

The valve 4| has a stem that projects through the upper wall of the valve casing, and a bell crank 46 has a forward arm that contacts with the valve stem and displaces the stem to open the valve when the bell crank is rocked counterclockwise. The bell crank 46 is connected to the side of the carriage ID by a pivot 41 and the rearward arm of the bell crank 46 projects downward and outward from the side of the carriage and has a cam-follower roller 48 at its lower end.

The roller 48 operates over a cam 50 that is preferably held in place by screws 5| that extend into the side of the track l2 but hold the cam 50 at some distance from the side of the track so that the cam-follower 48 and the lower end of the bell crank 46 do not scrape the side of the track.

The cam 50 is designed for the work piece 26 and has a low mid-portion that causes the bell crank 46 to rock clockwise and close the valve 4| so that there is no diluent gas supplied to the tubing 3'! during the time that the torch 23 is gas can flow traveling across the thick section of the work piece where conduction losses are large.

As the torch 23 passes beyond the heavy section and comes over the thin portion of the work piece beyond the web, there is a rise in the cam 50 that shifts the bell crank counter-clockwise and opens the valve 4| part way. As the torch approaches the end of the work piece where there is a decreasing mass of metal ahead of the flame system, there is a progressive rise in the cam 50 for opening the valve 4| wider to increase tion the work piece 26 with respect to the cam 50;

Changes and modifications can be made in the illustrated embodiment. Terms of orientation are, of course, relative, and some features of the invention can be used without others.

I claim:

1. In a flame hardening operation in which a heating torch is moved progressively across a -work piece, the method of controlling the heat which comprises supplying an oxy-fuel gas mixture to the torch for the heating flames, diluting the oxy-fuel gas mixturewith an inert gas to reduce the heat generated by the torch, and while said torch is moving progressively across the work-piece, varying the dilution inversely to the changes in the conduction losses from the region of the surface over which the torch is operating.

2. In a flame hardening operation inwhich a heating torch is moved progressively across a work piece by a carriage that moves along a support, the method of controlling the heat generated by the torch as ittravels over regions of the surface from which heat is lost by conduction at different rates, which method comprises supplying an oxy-fuel gas mixture to the torch for the heating flames, diluting the combustible mixture with inert gas to reduce the rate of discharge from the torch of oxygen and fuel gas without proportionately reducing their velocity of discharge, and varying the dilution in response to displacementof the carriage along its support.

3. The method of controlling the heat in a flame hardening operation performed by one or more heating flames that move progressively over the surface of a work-piece to be hardened, which method comprises reducing the heat generated, while leaving the number of flames unchanged. by diluting with an inert gas the mixture supplied to the one or more flames, and changing the dilution during the flame hardening operation in accordance with changes in the heat required by the work piece.

4. Flame hardening apparatus comprising a heating torch having a tip and a mixer in which oxygen and fuel gas are brought together and supplied to the tip, a conduit through which a diluent gas is supplied to the torch, a valve com manding said conduit, and automatic means for operating the valve in response to displacement of the torch to change the supply of diluent gas during a flame hardening operation.

5. Flame hardening apparatus comprising a carriage movable along a support, a bracket on the carriage, a torch supported by the bracket in position to move across the surface of a work piece as the carriage moves along said support, a mixer in which oxygen and fuel gas are brought together and supplied to the tip, a conduit through which a diluent gas is supplied-i0 the torch, a, valve on the carriage commanding said conduit, and automatic control means for operating the valve in response to displacement of the carriage lengthwise of the track.

6. Flame hardening apparatus comprising a wheeled carriage, a track on which. the carriage runs, a governor-controlled motor on the carriage for causing the carriage to move along the track at a predetermined speed, a heating torch and a quenching head, a bracket-on the torch for sunporting the heating torch and quenching head above the surface of a work piece, means for supplying Oxygen and fuel gas to, the torch, means in the direction of the track, a cam-follower extending from the carriage and contacting with the cam as the carriage moves along the track,

and valve-operating means on the carriage connected to the cam-follower.

'7. Flame hardening apparatus comprising a heating torch having a tip and a mixer having a mixing passage, an oxygen supply conduit and a fuel gas supply conduit that come together at equal acute angles to the axis of the mixing passa'ge into which said conduits open, another conduit for supplying a diluent gas to the oxy-fuel gas mixture, said other conduit and the mixing passage converging at equal acute angles to a discharge passage through which the mixture of oxygen, fuel gas, and diluent gas flows to a dis-