US2523883A - Heat-treating machine - Google Patents

Description

5 Sheets-Sheet 1 HEAT-TREATING MACHINE D. M. STRAUCHEN ETAL Sept. 26, 1950 Filed June 20, 1947 INVENTOR.

ATTORNEYS mm a My 00 WW m P 1950 D. M. STRAUCHEN ET AL 2,523,383

HEAT-TREATING MACHINE Filed June 20, 1947 5 She'cs-Sheet 3 Sept. 26, 1950 D. M. STRAUCHEN ETAL 2,523,883

l-IEAT-TREATING MACHINE BY fzfy ja 3 2 9 V W AZ'ZWIZNIXS Patented Sept. 26, 1950 HEAT-TREATIN G MACHINE David M. Strauchen and Milton Garvin, Cincinnati, Ohio, assignors to The Cincinnati Milling Machine 00., Cincinnati, Ohio, a corporation of Ohio Application June 20, 1947, Serial No. 755,944

6 Claims.

A of the part to be hardened.

A more specific object of this invention is to provide a new and improved apparatus for performing surface hardening operations of the nitriding type at high speed and automatically.

Another object of this invention is to materially reduce the time for effecting surface hardening operations involving chemical changes by providing an automatic machine in which the operator merely has to load the work, and the machine automatically performs the process and ejects the work from the machine. 4

Other objects and advantages of the present invention should be readily apparent by reference to the following specification, considered in conjunction with the accompanying drawings formin a part thereof, and it is to be understood that any modifications may be made in the exact structural details there shown and described, within the scope of the appended claims, without departing from or exceeding the spirit of the invention.

Referring to the drawings in which like reference numerals indicate like or similar parts:

Figure l is an elevation of a machine embodying the principles of this invention.

Figure 2 is an end view of the machine shown in Figure 1.

Figure 3 is an enlarged sectional view through the work spindle of the machine.

Figure 4 is a detail section on the line 4-4 of Figure 1.

Figure 5 is a sectional view through one of the torch supports.

- Fi ure 6 is a detail section on the line 8-8 of Figure 5.

Figure 7 is a detail view of the conveyor belt guides.

Figure 8 is a section on the line 8-8 of Figure Figure 9 is a diagrammatic view of the general control circuit. a

Figure 10 is a diagrammatic view of the electrical control circuit.

One of the processes in heat treating of steel is known as surface hardening in which the metal at or near the surface of an article is hardened perceptibly more than the central portion, and this process is particularly advantageous for surfaces subjected to wear.

In general, there are two types of surface hardening processes which are differentiated by the fact that in one no chemical change is effected in the composition of the material near the surface, and in the other a chemical change is effected.

In the first type of process the material at the surface is simply heated to its critical temperature and then quenched before the heat has fully penetrated the core of the body, the hardening being effected by an allotropic change in the material rather than a chemical change.

Surface hardening operations of the second type involving chemical changes are generally known as case hardening which for present purposes may be considered to include carburizing, cyaniding, and nitriding. Chemical changes result from these operations because additional material, such as carbon, carbon and nitrogen, or nitrogen alone is added to or absorbed in chemical combination with the material of the part being treated.

The present conventional practice of these processes requires considerable time and special apparatus, and it is well known that nitriding operations, for instance, take as long as three to nine hours. It should be noted in connection with nitriding that this operation cannot be carried out in the presence of free oxygen that will cause oxidation of the surface especially during heating because nitriding cannot be performed upon an oxidized surface. Therefore, in the past special apparatus has been required to provide a nonoxidizing atmosphere.

In the carburizing process, special packing operations are necessary in order to pack the material, from which the carbon is to be absorbed, in adjacent relation to the part being treated which requires considerable time as well as special apparatus. The same is generally true of cyaniding operations.

By means of this invention any of these hardening operations which involves chemical change can be performed easily and quickly in a very short length of time and on a continuous production basis. In addition, a combination of operations may be simultaneously performed. For instance, in nitriding perations it is the general practice at present to harden the part in one operation and then nitride the part in a second operation. By means of this invention the surface may be simultaneously hardened and nitrided.

This invention will first be explained in connection with its utilization for effecting high speed nitriding operations.

Although such operations have been carried out in the past by means of ovens in which special precautions were taken to keep out the air or to neutralize whatever air did enter through openings by which parts were introduced into or removed from the oven, in the present invention the perator merely places the part to be treated on a spindle in the open air. Since this invention is more particularly adapted for treating surfaces of revolution, a gear may be taken as a good example of a part to be treated for explanatory purposes. After placing the part on the spindle, the periphery of the gear is smothered b a heating zone created by the combustion of an oxyacetylene gas in which the oxygen is burned to completion, leaving no residue to oxidize the surface of the part. This heating zone thus automatically creates 9. non-oxidizing atmosphere around the periphery of the article to be treated due to its smothering effect of excluding the surrounding air. Into this zone nitrogen is introduced in such form that it will chemically react with the iron in the article to be treated. This may be accomplished in different ways.

The nitrogen may be in any combining form thereof such as chemically pure anhydrous ammonia, or chemically pure anhydrous ammonia dissociated. A practical way is to introduce commercially pure anhydrous ammonia in sufllcient quantity to saturate the heating zone, the heat of which will automatically efiect dissociation of the ammonia in the heating zone, thus providing nascent nitrogen which will immediately react with the iron. It is perfectly practicable to eflect the dissociation in the heating zone because as the temperature of the work increases during heating, the anhydrous ammonia will begin to dissociate or decompose fairl rapidly at a temperature of approximately 550 degrees F. so that it will be dissociated by the time that the work reaches a temperature of around 900 degrees F. at which temperature the chemical reaction of the nitrogen on the iron becomes active.

This reaction will remain active up to a temperature of approximately 1100 degrees F. after which it will begin to slow down.

The percentage of dissociation of the ammonia is important, and it has been found that between 30 and 40% is the most satisfactory. Control of the percentage of dissociation can be obtained by controlling the rate of flow of the anhydrous ammonia to the heating zone.

After the article has been heated to its critical temperature, as in the case of parts which have not been previously hardened, the heating zone is extinguished, and the part is automatically quenched. In the case of articles which have been previously heat treated, it is not necessary to raise the temperature of the work to its critical temperature, but the part may be cooled at any point after the temperature of the work has passed approximatel 1100 degrees F. since the amount of nitrogen absorbed by the article and its degree of penetration determines the depth of the case hardened surface, it will be obvious that byslowing down the rate of heating of the article after it has reached 900 degrees F. that more time becomes available for greater absorption of the nitrogen and thereby a deeper case hardened surface.

Mir

relative to the sleeve.

struction is that after the work has been treated The nitrogen may be introduced in combination with the oxyacetylene gas through the same torches, but it has been found to be more practical to provide separate torches for er'fecting the introduction of the nitrogen.

Referring now to the drawings, Figure 1 shows a machine embodying the principles of this invention. In this figure, the reference numeral l0 indicates the bed of the machine having a top table portion II and a box-like column portion I2 which uprises from the rear of the bed. A work piece, such as a gear I3, is mounted upon the end of an arbor H which, as shown in Figure 3, is provided with a tapered end 15 for insertion in a tapered socket l6 attached to the end of the work spindle I1. The arbor I4 is replaceable by other arbors, the object being to provide an arbor, the end of which is of proper diameter to fit the size of hole in the work piece. The end l5 of the arbor is provided with a fixed key H! as shown in Figure 1 which will fit the keyway in the work piece for imparting rotation thereto. It has been found that if the end of the arbor has a reasonably close sliding fit with the hole in the work that it is not necessary to provide additional means for holding the work piece on the arbor during its rotation.

The spindle l! is supported for a sliding fit in a sleeve l9, Figure 3, and is provided with a spline receiving a key 2| fixed in the sleeve IS. The sleeve I9 is journaled in bearings 22 and 23 of the housing 24, and is adapted to be rotated on these bearings by a power driven member 25 secured to the end of the sleeve. It will be noted that the sleeve is held against axial movement while the spindle I1 is subject to axial movement The purpose of this conit may be automatically ejected by withdrawing the spindle ll. To facilitate ejection, the housing 24 has a fixed tubular housing 26 attached to its forward end so that as the spindle is withdrawn the work piece will engage the end 21 of the housing 26 and be held while the arbor is withdrawn from the work piece, after which the work piece will fall by gravity into the quenching tank.

Withdrawal of the spindle is effected by a piston 28 which is slidably mounted in a cylinder 29 attached to the housing 24, the piston being connected by a piston rod 30 and bracket 3| to the end of the spindle H by means of an anti-friction bearing 32. Thus the spindle may rotate freely with respect to the bracket 3|, but the bracket is so connected that it may efiect withdrawal of the spindle.

Rotation of the spindle is efiected by a motor 33, which, as shown in Figure 2, is suitably supported within the column l2 and is connected by means of a driving chain or belt 34 to the member Heating of the work piece and creation of the non-oxidizing heat zone is effected by oxyacetylene gas which is supplied to the work by suitable torches, one being shown on each side of the work piece and indicated by the reference numeral 33' in Figure 1. These torches each have a plurality of burner tips, one of which is indicated by the reference numeral 3| in Figure 5, and these tips, which may be of different lengths to suit the shape of the work, are threaded in the end of the torch in rows as shown in Figure 4. Although the torch is provided with a plurality of threaded holes for receiving these tips, it is not necessary to utilize all of these holes and some may be closed by suitably threaded plugs. The number of tips utilized, therefore, depends upon the size and shape of the work, the amount of heat that has to be provided to heat the work in a reasonable time, and the number necessary to provide a circumscribing heating zone.

As shown in Figure 5, each torch has a cylindrical neck by which it is clamped in a split bracket 36 which, in turn, is supported upon the end of an arm 31 by means of a clamping bolt 34 which may be loosened to allow rotation of the bracket to permit a certain amount of swinging adjustment of the torch. The arm 31 is supported for rotation and sliding movement upon an upright stud 39 forming part of a slidable member 40. The arm 31 is provided with a clamping bolt 4| for clamping to the stud, and is also provided with an adjusting bolt 42 which is vertically threaded in the end of the stud for adjusting the arm 31 vertically. In addition, the member is provided with an adjusting screw 48 whereby the whole torch assembly may be adjusted relative to the center of the work spindle. Referring to Figure 6, which shows the slideway construction of the member 40, it will be noted that the member 40 is provided with a clamping bolt 44 by which it may be clamped after adjustment.

The gas is supplied to the torches in the following manner. As shown in Figure 9, a source of oxygen gas is connected to a main control valve 45 from which branch extensions 46 and 41 lead to automatic control valves 48 and 49. Each valve has a power shifted valve plunger 50 so that when the valve 48 is opened, the line 48 is connected to line 5i which leads to a mixing chamber 52. Opening of valve 49 connects branch 41 to pipe 53 which leads to a second mixing chamber 54.

A supply of acetylene gas is connected to a main control valve 55 from which branch connections 56 and 51 lead to automatic control valves 58 and 59. Each valve has an automatically actuated valve plunger 60 so that when the valve 58 is opened, the branch 55 is connected by pipe 6| to mixing chamber 52; and when the valve 58 is opened, branch 51 is connected by pipe 62 to the mixing chamber 54. The mixing chambers are adjusted to establish the proper ratio of oxygen to acetylene to create preferably a neutral flame, that is, one in which all of the gas supplied is consumed by combustion. The mixing chamber 52 is connected by a suitable channel 53 to one torch, and the mixing chamber 54 is connected by a suitable channel 54 to the other torch.

Automatic control means are provided for igniting the gas at the burner tips. This is accomplished by an electric spark which is generated by spark coils 65 and 66, shown in Figure 9, which are connected in parallel to the secondary of a transformer 61. The spark gap is created by connecting one lead 68 from the spark coil to the construction shown in Figure 4 where the lead wire 58 is threaded through a tube 69 and connected to a spark gap rod I0 which projects in adjacent relation to the torch 33' in such a manner as to cause the spark to jump from the wire Ill to the metal of the torch which is grounded. The tube 69 passes through a sleeve H and is adapted to be axially adjustable relative to the sleeve so that the correct spark gap distance can be created between the end of the rod 10 and the torch. The sleeve H is axially slidable in a bore 12 of a tubular bracket 13 which is welded or otherwise secured to a fixed part of the frame 14 of the machine. A key I5 prevents rotation of the sleeve.

The end of the sleeve is connected by a bracket 15 to a solenoid plunger whereby the sleeve 1| may be withdrawn to remove the wire "Hi from the heating zone. The bracket 15 has an upstanding support 11 secured thereto in which is mounted a set screw 18 for clamping the tube 89 after its relative adjustment with respect to the sleeve H. A spring 19 is connected between the parts 16 and the fixed part 14 to hold the spark gap wire 10 in its advanced position. It will be noted that separate spark gaps are provided for each torch.

After the heating zone has been created by ignition of the gas, it is saturated with nitrogen, which in the present instance is obtained by connecting a; source of anhydrous ammonia to a main control valve as shown in Figure 9, which is a manually adjustable valve, and this valve has a connection 8| .to an automatic control valve 82 which when opened connects the supply of ammonia to a series of supply pipes 83, 84, 85, and 86 which are arranged at suitable spaced intervals around the heating zone. As previously suggested, the control valve 80 may be adjusted to control the percentage of dissociation of the ammonia.

During heating of the work, its temperature is continuously and automatically measured with the aid of an electric thermopile which is mounted in the thermopile housing 81, which has an extension in the form of a viewing tube 88 which is pointed toward the periphery of the work. In order to prevent the flame of the heating zone from entering the tube, and in order to prevent the flame from interfering with the true radiation of heat from the heated work piece, means are provided for creating a downward flow of air through the viewing tube of suflicient intensity to clear the flame away from the viewing area of the work. This is accomplished by connecting a source of compressed air to a main control valve 89 which has a branch connection 9|! to a second control valve 9| which may be manually adjusted to determine the rate of flow of air through the pipe 92 which leads to the viewing tube. Since the work is continuously rotating, the heat radiation measurement will be an average of the temperature of the entire periphery of the work.

The thermopile is electrically connected by a pair of wires 92' and 93 for operation and movement of a movable indicator 94 of a temperature control instrument 95 which is of a known commercial type and which has a preset indicator 96. It is suillcient to say at this time that when the movable indicator 94 reaches a position in juxtaposition to the presettable indicator 96 that a normally closed electric switch 91 in the instrument will be opened.

The manner in which the various control devices and the temperature control instrument are coupled together to obtain automatic operation of the machine will now be explained in connection with the electrical control circuit shown in Figure 10'.

This automatic control circuit makes it possible to operate the machine on a production basis, the operator merely loading the work piece on the spindle and the machine automatically ejecting the work after proper treatment, and since a piece can be treated in approximately eight to ten seconds, it will be apparent that a very high rate of production can be obtained.

The automatic cycle or the machine is initiated by the operator pressing the start button 90 and, with the selector switch 99 set on the automatic operation selector contact I00, a circuit is completed from the power main IOI through line I02 which contains in series the normally closed instrument switch 91, switch 99, a line I03 and control relay CR1 to power main I04. Operation of relay CR'I closes contacts CRII completing a circuit from line I05 to line II which is connected in parallel through relays CR4 and CR4A to line I04. Energization of relay CR4 closes its latching contacts CR4-I which maintains the circuit closed after the push button is released and contacts CRII open.

Relay CR4A closes its contacts CR4A--l in line I08, thereby energizing relay CRII. The relay CRH has a pair of normally closed contacts CRI I-I in line I09 which leads to work ejector control relay CR2. The line I09 is adapted to be connected to the power main IOI through a selector switch I I0 which selects between instant and time operation of the retraction of the work spindle. As shown, there is provided a pair of contacts III and H2 for selective engagement by the switch member H0, and the contact III is connected to the main line IN by switch contacts TI-A of timer relay TI; and switch point H2 is connected through switch CRG-I which switch is part of control relay CRIi. For the purposes of this description it will be assumed that the switch H0 is set on contact H2 for instant retraction of the work spindle upon the closing of switch CR5I.

The work ejector control relay CR2 has a set of contacts CR2I and CR22, shown in Figure 9, in lines H3 and H4, which lead to solenoid H5. This solenoid controls operation of a reversing valve H6 which determines operation of the work ejector piston 28 which is operatively connected to the work supporting arbor I4 as previously described. The valve H6 has a pressure port H'I which is supplied with pneumatic pressure by way of the main control valve 89 and an individual control valve H8. The reversing valve H6 is connected by a pair of channels H9 and I20 to opposite ends of the cylinder 29.

The energization of relay CR4 closed a first set of contacts CR4-4 in line I2I to initiate rotation of the work spindle. In order to complete this circuit the relay CR1 through closing of its contacts CRI2 completed a circuit from line IOI through line I22 and branch I23 to relay CRA. The relay CRA closed its contacts CRA'I, thereby latching in the circuit through CR4-4 and a serially arranged stop switch I23 which is necessary because the relay CR1, it will be remembered, opens as soon as the operator releases the start button whereby the switch CR'I--2 will also open.

The relay CRA has a, pair of contacts CRA2 as shown in Figure 9 for connecting a source of power such as the power mains I24 and I25 to a starter coil I25 to energize the same and closed switch I21 to the spindle motor 33, the direction of rotation having been previously selected by closing one of the direction controlled switches I28 or I29.

The relay CRA has another pair of contacts CRA-3 in line I30 which is a branch of line I22, but since these contacts are normally closed, energization of the relay CRA will open these contacts and break the circuit to a control relay CR8 which controls the switch CR5I previously recited.

A timer relay T3 which is connected in parallel with the relay CRA is simultaneously energized therewith and this relay has a pair or contacts T3--I in series with the control relay CRO. The relay T3 is of the type which upon energization instantly closes and has a timed opening whereby the contacts T3-I will close simultaneously with the opening of the contacts CRA-3 but upon deenergization of the relays CRA and T3 the contacts T3-I will remain closed alter the closing or contacts CRA-3, thus causing momentary operation of relay CR6 and the closing of its contacts CRE-I which will complete the circuit to the retraction control solenoid H5, first to cause retraction of the work spindle and ejection of the work therefrom, and upon opening of the timer relay contacts T3-I return of the work spindle to its normal position.

Energization of the relay CR1 by the starting button results in the closing of a second pair of contacts CRII in line I3I, causing operation of control relay CR3. This relay latches itself in through closing of its contacts CR3-I which completes a circuit beginnin with the line I2I, switch CR44, stop button I23, switch CRA-I, line I32, line I33, auxiliary stop button I34 to switch CR3I.

Energization of the relay CR3 closes contact CR3-2 in line I35 and serially arranged in this line is another pair of contacts CR4-2 which were closed when the relay CR4 was energized by the push button 98. This completes a circuit to line I36 which has parallel connections to timer relay T2, timer relay TB, control relay CRI and timer relay T5.

Energization of relay CRI will close switch CRII which is in series with normally closed switch CR5I of control relay CR5 that governs the control of the acetylene valves. This would momentarily complete a circuit from line I36 through line I31, line I38, and line I33 to relay CR5. Operation of this relay, however, would immediately open the closed switch CR5I. Therefore, the timer relay T5, which is energized simultaneously with the relay CRI, closes its contacts T5I in line I40 which is connected to the power main IM and thereby completes a circuit or maintains the circuit to relay CR5. As shown in Figure 9, the relay CR5 has a pair of contacts CR52 and CR5-3 which complete a circuit from power main I24 through line I, branch lines I42 and I43 to control solenoids I44 and I45 respectively for the acetylene control valves 58 and 59. Thus operation of these valves turns on the acetylene gas. The return lines I45 and I4! terminate in selector switches I48 and I49 whereby either or both switches may be closed, depending upon whether one or both valves are utilized. These switches complete a circuit to line I50 and thereby to power main I25.

Operation of the control relay CRI also closes contacts CRI2, which is located in series between the line I39 and timer relay T6. The timer relay T6 is of the type which times closes and instantaneously opens. Therefore, the contact T6--I will be delayed in closing until after operation of the acetylene gas control relay CR5, and thus delay operation of the oxygen control relay CR8. Referring to Figure 9, the oxygen control relay CR8 has a pair of contacts CROI, CRI2 which respectively control energization of solenoids I5I and I52 connected with the oxygen control valves 48 and 49 respectively. One side of these solenoids is connected directly to line I as shown, and the lines I" and I are connectable by selector switches III and I" respectively to the other power line I50. These switches are manually operable and are selectively closed by the operator when he is setting up the machine and determining whether he is going to use one or both torches.

It will now be seen that the oxygen is admitted to the torches momentarily later than the acetylene, which gives an opportunity to light the acetylene gas before the oxygen is added, thereby reducing the noise and explosive effects upon lighting the gas.

As previously stated, the gas is ignited by means of spark coils, and energlzation of these spark coils is determined by switches which, as shown in Figure 9, are serially arranged in one of the control lines I51 and I! leading to the transformer 61. As shown, the line I51 has a pair of contacts CR3-3 which are closed upon the previous operation of the relay coil CR3. The timer relay T2 which is simultaneously energized with the control rela CR--I has a pair of contacts T2-I and T2--2 serially arranged in line IS! with the switch CR3--3.

The contact T2-2 is normally closed and has a timed delay opening upon energization of the relay and the switch T2-I is instantly closed upon operation of the relay. It will, therefore, be seen that a circuit is momentarily established to the spark coils for the length of time that it takes to open the contacts T2-2 which will then break the circuit.

After the flame has been ignited to create the heating zone around the work it is desirabl to withdraw the spark gap rods from the heating zone, and this is done by the mechanism shown in Figure 4. This retraction is effected by a pair of solenoids I59 and I60, one for each spark rod, and these solenoids are connected in parallel to the power lines I and I50 and controlled by switches CRIS-I and CRI62 which are separate sets of switch contacts on the rela CRIS. This relay is connected by line IGI to power main IIlI as shown in Figure and in this line is a air of normally closed switch contacts Til-I associated with the timer relay T8 which is energized simultaneously with the control relay CRI. The relay T8 is of the type which has a delayed closing and an instantaneous opening whereby upon energization the contacts T8--I are delayed in closing a sufficient amount of time to permit ignition of the gas after which the contacts close, causing energization of the relay CRIB and retraction of the spark gap rods.

So far in the automatic cycle the oxy-acetylene gas has been turned on, ignited by the spark, and the spark gap rods retracted. The nitrogen is now added to the heating zone automatically in the following manner.

When the relay T5 closed its contact T5I. it also completed a circuit from line I39 in parallel through three timer relays TRIS, TRII, and TRIB. These relays are connected by a common line IGI' and closed selector switch I62 to the power line I04. The timer rela TRIS is instantly actuated upon energization and closes a contact TRI5I which is in branch line I63 of line I2I. It will be noted that this contact closes a by-pass circuit by means of the connection I64 around the contact CRl-l whereby a circuit may be maintained in case contact CRl-l .should open.

The timer relay TR-Il instantly closes also upon energization and thereby closes its contact TRII-I which is in line I65 leading to relay CRIS. The timer relay TRIO has a contact TRI8I also in line I I5 and in serial relation with contact TRI'I-I. This relay is of the type that instantly opens upon energization and therefore holds the circuit open to relay CRIB until it is closed. If the timing on relay TRIO is shortened it will close immediately after it opens and thereby immediately complete a circult to relay can whichcontrols the admittance of the nitrogen gas. When relay CRIS- operates, it closes a contact CRI5-I located in parallel with the contact TRIB-I, and thereby latches itself in around the contact TRI8--I. Referring to Figure 9 the relay CRIB has a second contact CRIS-2 in line I66 which closes and completes a circuit to solenoid I61 which automatically opens the control valve 82. Since, as previously stated, the nascent nitrogen will not begin to chemically combine with the iron until a temperature of around 900 degrees has been reached, it may be desirable to conserve on the use of the nitrogen gas by not turnin it on until this approximate temperature has been reached. It is for this reason that the timer relay TRIS is inserted in the line to instantly open and since it is of the time closed variety it may be timed to close at approximately the time the work reaches a temperature of 900 degrees. Once it has operated and closed the relay CRIS it becomes inefiective for the rest 01' the cycle due to th fact that it is latched out by the contact CRIB-I.

V The timer relay TRII, which instantly closed, may be timed to open at any point where it is desired to shut off the nitrogen gas. In some cases it may be desirable to shut off the gas at around 1100 degrees, and in other cases it may be allowed to stay on until the work has reached its maximum temperature or for even a slight time after that. This makes a flexible arrangement for controlling the admittance of the nitrogen gas.

It is desirable that the electro-thermopile in housing 81 only be energized during the automatic cycle and therefore a normally closed contact CRI'I-I is connected across lines 92' and 93 to short circuit the thermopile. It is, therefore,\necessary to open these contacts upon initiation of an automatic cycle and this is accomplished by providing a timer relay T1 in parallel with the oxygen control relay CR8 for simultaneous energization therewith. This coil, however, is of the type that has a timed closing whereby it may be adjusted to determine how soon after the heating zone has been created that it is desirable to turn on the thermopile. When the relay does close, it closes a contact TI-I in series with relay CR" and when this relay is energized it opens the contact CRI'I-I and renders the thermopile effective for measuring the work temperature.

When the work has been heated to the preselected temperature, the normally closed switch 91 in the instrument 95 opens, thereby breaking the circuit in line I02 to the relay CRII as well as breaking the circuit through lines I05 and I01 to relay CR4 and CRlA. These relays will thus open simultaneously. This will break the circuit in line III by the opening of contact CRl-4 to the spindle control relay CRA as well as timer relay T3 and TI9, which will immediately stop rotation of the work unless the timer relay TRIS has been so timed as to maintain the contact 11 TRIS-I closed after contact CR4-4 opens whereby the spindle may continue to rotate for a short time after the heatin zone has been extinguished.

The deenergization of relay CR4 opens contact (IRA-2 in line I35, thereby breaking the circuit through line I36 to the relays T2, T8, CRI, T5 and the circuit through branch line I31A.

The deenergization of timer relay T2 resets contacts in the spark coil circuit by opening the contacts T2I and closing the contacts T2-2. The deenergization of the timer relay T8 opens the contacts T8I in line I6I leading to the spark rod retraction control relay CRIB, thus opening the contacts CRI6I and CRIB-2 shown in Figure 9, thereby deenergizing the retraction solenoids I59 and I60 whereby the spark rods return to an operative position.

Deenergization of relay CRI opens contact CRII in line I31 and also CRI-2 leading to timer relay T6. The opening of contact CRII produces no eilect, because contact Til-I is still closed but the opening of CRI2 deenergizes relay TB. This immediately resets contact T6-I to its open position. The deenergization of relay CR8 breaks contact CR8I and CR8-2 to the oxygen control solenoids I5I and I52, allowing these valves to close and thus shut off the oxygen supply. The timer relay T5, when it is deenergized, has a timed opening, thereby delaying the opening of the contact T5-I to maintain the circuit to relay CR5 and thus delay the breaking of contacts CR52 and CRIS-3 in the circuit to the acetylene valve control solenoids I44 and I45 whereby the acetylene valves close after the oxygen valves have closed whereby the acetylene gas is shut off after the oxygen.

The breaking of the circuit to timer relay TI causes it to immediately open contact TII breaking the circuit to control relay CRI'I, thereby closing the short circuit contact CRII-I which thus cuts ofi current to the electricthermopile in housing 81.

The opening of contact T5-I also broke the circuit to timer relays TRI-5. TRII, and TRI8. Timer relay TRIS has a delayed opening whereby its contact TRI5-I in line I53 will maintain a circuit around open contact CR44, stop switch I23 and the closed latching contact CRA--I of relay CRA which controls rotation of the spindle.

In other words, if it is desired that the work continue to rotate for a short time after the heating zone has been extinguished the relay TRIS is set to accomplish this. Otherwise, the

relay is set to instantly open upon its deenergization.

The timer relay TRI'I also has a timed opening which may be set to delay the opening of contact TRIT I and thereby delay the opening of relay CRI5. The relay CRI 5 controls the closing of the nitrogen control valve 82 and if it is desired that the flow of nitrogen gas be continued alter the heating zone has been extinguished while the work piece is still red hot and while it is cooling down to some temperature such as 1100 degrees F., the timer relay TRI'I may be adjusted to delay operation of relay CRI5, and since in such a situation it is desirable that the work piece continue to rotate it will be further evident why the timer relay TRIS is also provided with a timed opening to maintain rotation of the work for the purpose specified. The deenergization of the timer relay TRI8 merely reopens the contact TRI8--I but this circuit at 12 this time is under control of the latching contact CRI 5I of relay CRIS.

The ejection of the work from the work spindle is automatically controlled in the following manner. When the instrument switch 8! opened it broke the circuit to relay CRI I, and this relay closes its contact CRI II in line Ill leading to the work ejection control relay CR2. At this time the contact CRS-I, in the branch of the circuit indicated for instant operation and terminating in the contact II 2, is open. When the spindle control relay CRA is finally deenergized it closes its contact CRA-3 which is a normally closed contact. At the same time that the relay CRA is deenergized, the timer relay T3 connected in parallel with it is also deenergized but this has a delayed opening whereby it delays the opening of its contact T3--I, in line I30, and in series with normally closed contact ORA-3. This momentarily completes a circuit to relay CR which becomes energized and closes contact CRB-I whereby the work ejector control relay CR2 is energized to close contacts CR2-I and CR22 which, as shown in Figure 9, are in lines II: and III leading to the control solenoid H5 01' the work ejector control circuit. The timer relay T3 will subsequently open, thereby breaking the circuit to relay CR6 whereby the circuit to the solenoid II5 will be broken and the reversing control valve will be returned by its spring to normal position and reposition the spindle for receiving the next work piece.

As previously set forth, it may be desirable to maintain rotation of the work in a nitrogen atmosphere after the heating zone has been extinguished, or it may be desirable to delay ejection of the work for other reasons. In such case the selector switch IIII would be set on button III whereby the operation of the control relay CR2 would be governed by contact TIA. This contact is controlled by the timer relay TI which is connected in parallel with relay CR6 but independently controlled by a contact TI9--I which is associated with the timer relay TIS connected in parallel with the spindle control relay CRA. In other words, when the control relay CRA is deenergized, relay TI! is also deenergized. The relay TI9 has a delayed opening so that it will open after the operation of relay CRA and thus establish a circuit to timer relay TI. The timer relay TI upon energization has a delayed closing which thereby delays the closing of contact TIA after the spindle has stopped rotating.

The machine is provided with a conveyor belt, indicated generally by the reference numeral I 68 in Figure 1, which is operable by an electric motor I69. The operation of this motor is controlled by a starter relay LEB in Figure 10, and this relay is in series with two switch contacts CR4-3, and normally closed contact T4I. The contact CRl-3 is closed when the machine is started by the operation of relay CR4 and this completes a circuit through the normally closed contact Tl-I to the starter LEB which initiates operation of the conveyor. At the same time a timer relay Tl connected in parallel with the starter LEB is energized. This relay, however, has a delayed closing which may be timed to determine the length of operation of the conveyor since it is not necessary that it be running all the time. Therefore, when the timer relay does close, it opens the normally closed contact Tl-I, thereby breaking the circuit to the starter LEB. At the same time this will break the circuit to relay T4 which will instantly open and reclose contact T4--I. Another time interval will begin depending upon the timing of the relay T4 before the next operation of the conveyor begins. Should, however, the cycle end or the machine shut down, the relay contact CR4--3 will open, thereby interrupting any further operation of the conveyor.

The wire conveyor belt I88 has a sprocket chain I attached to each edge of the belt and these sprocket chains run over pulleys I'll as shown in Figure 1 which are journaled on a shaft I12 which is supported in brackets I13 which are integrally secured to the side wall of the bed. At the other end, the sprocket chains run over a pair of sprocket wheels I14 which are mounted on a shaft I15 that is journaled in suitable brackets I16 which are also secured to the side wall of the bed. The shaft I15 is provided on one end with a suitable driving pulley I11 that is connected by a suitable motion transmitting belt I18 to the drive pulley I18 of the motor I88. In order to maintain suitable tension in the belt and to change its direction there is provided a pair of guide shoes I80 and I8I which are shown more particularly in F gure 7, there being a pair 01' these shoes for each side of the belt. The curved shoe I80 has a guide strip I82 secured to the bottom of it and adapted to engage the rollers I82 of thesprocket chain. The shoe I80 is secured to a fixed part of the bed by suitable bolts I83. The lower shoe I8I is secured by a bolt I84 to a guide block I85 which is slidable in a T slot guideway I88 formed in a fixed block I81. A tension regulating bolt I88 is threaded in a fixed block I88 and so positioned that the end I80 of the bolt engages the top of the block I85. By applying a suitable wrench to the head I 8| of the bolt I88 the tension of the entire chain may be regulated. The clamping nut I82 serves to secure the parts after adjustment.

When it is desired to manually control the machine as for set-up and adjusting purposes the selector control switch 88 shown in Fi ure 10 is set on the contact I83. This eliminates the operation of relay CR1 when the start button 88 is pressed, but the relays CR4. CR4A and CRII will still be energized in the manner nrevously described and the circuit will be latched in by the closing of contact CR4-I.

The operator may then press the s indle control start button I84 which will complete a circuit from line IOI through l ne I 2|, closed contact CR4-4, stop button I23 and line I32 to the control relay CRA. This will start rotation of the work spindle. The button I84 also completed a circuit throu h line I33 and a normally closed stop button I34 to a gas control start button I85. The closure of this button energizes relay CR3 which. as previously described, is a control relav for the c rcuit including lines I35, I38, I31a to the acetylene gas control relay CR5, the oxygen control relay CR8 and the spark control timer relay T2. This circuit will be latched in through the closing of contact CR3-l. When the work has reached the proper temperature and the instrument switch 81 is opened the relay CR4 will be deenergized and automatically break these two control circuits by the opening of CR4-4 in line I2I and contact CR4-2 in line I35.

Either one of these circuits may be individually broken by the respective stop buttons I23 and I34.

By making certain adjustments other types of gas hardening operations may be performed on this machine. For instance, carburizing operations which require excess carbon to be absorbed in the steel of the article being treated may be accomplished by adjusting the flame in a manner to have an excess of acetylene which therebyv yields carbon which will chemically combine with the steel of the article being treated.

In other words, the mixing valve 52 is provided with a first valve stem I88 for adjusting the amount of acetylene and a second valve stem I81 for adjusting the amount of oxygen. The mixing valve 54 may be similarly provided. As previously stated, these valves may be adjusted to provide a neutral flame for nitriding operations but for carburizing operations they may be adjusted to give excess acetylene and in this operation the control valve for the nitrogen is completely shut off.

In cyanide operations carbon and nitrogen are provided for chemically combining with the steel and in this case the mixing valve 52 may be adjusted to give a certain percentage of excess acetylene and the nitrogen control valve may be adjusted to provide a certain percentage of nitrogen and both gases will mix in the heating zone and thereby effect a cyaniding operation.

A cooling circuit has been provided for the machine to reduce excess heating of the parts, and this is accomplished by connecting a source of water supply indicated generally by the reference numeral I88 which may be the ordinary city water supply. A control valve I88 controls the flow of water to branch pipes 200 leading to one of the heads 33' and after circulated through the head the water passes out through the return pipe 202. Similarly, the pipe 20I may be connected to the other head 33' which also has an exhaust pipe 203. The pipe 20I has a branch 204 from which a, pipe 205 leads to a water front 205 located on the front of the machine as shown in Figure 2 between the torch heads and the face of the column. The part 206 is also provided with an exhaust pipe 201. A second branch 208 leads to the housing 81 for cooling the metallic parts thereof and preventing excessive radiation of heat from the parts to the thermopile located in the housing. The water exhausts from this through pipe 208.

All of these various exhaust .pipes may be connected to a .common channel 2| 0 indicated in Figure 2, and this pipe leads to a coil 2 located in a housing 2I2. The coil is connected to a return pipe 2I3 which leads to a suitable basin outside of the machine.

The housing 2I2 serves as a heat interchanger for the quenching oil which is located in the quenching tank inside of the piece I0. This tank has a connection at 2I4 from which oil may be drawn off at the top of the tank through pipe 2I5 of a pump 2I8 driven by a motor 2I1. The delivery 2I8 from the .pump goes to the housing 2 I2 through which it is circulated in contact with the coil and then the oil is forced by pressure through pipe 2I8 into the bottom of the tank.

The operation of the motor 2I1 is controlled by a thermostatically controlled switch 220 which is shown in Figure 10, and when this switch closes it completes a circuit through line 22I to a starter relay 222 which controls operation of a switch 223 shown in Figure 9 which serves to connect the motor 2I1 to the power means.

It will thus be seen that a machine has been provided for carrying out various gas hardening operations involving chemical changes of the material and that the machine may be selectively set up for perfonming nitriding, cyaniding, or carburizing operations.

What is claimed is:

1. In an automatic heat treating machine, the combination of a work support, heating torches supported in circumscribing relation to said work support, power operable means for firing said torches to heat the work and create a non-oxidizing heating zone around said support smothering the work, a heating cycle starting and control circuit for said power operable means including switch means for energizing said circuit to initiate operation of said power operable means, supply pipes supported in circumscribing relation to the work support with their outlets within said zone, valve means for connecting a source of anhydrous ammonia to said pipes for delivery into said zone, power operable means operatively connected to said circuit by timing means for opening said valve means after creation of said heating zone and during heating of the work to effect dissociation of the delivered ammonia, means presettable to select the final temperature to which the work is to be heated including a control switch operatively connected in said circuit to maintain energization thereof established by said switch means, a thermopile supported in relation to the work support to immediately respond to work heat radiation, work temperature indicating means including a movable element electrically connected to said thermopile for movement in response to heat radiation increases thereon, said element being adapted to cause actuation of said control switch when moved into cooperative relationship with the presettable selector to deenergize said starting and control circuit and thereby simultaneously extinguish said heating zone and close said valve means.

2. In an automatic heat treating machine, the combination of a rotatable work spindle, power operable means for firing a non-oxidizing heating zone around said spindle to heat the work mounted thereon, a heating cycle starting and control circuit for said power operable means including a cycle control relay for energizing said circuit to initiate operation of said .power operable means, supply pipes supported in circumscribing relation to said spindle with their outlets within said zone, valve means for connect-- ing a dissociable gas having a nitrogen element for delivery by said pipes into said zone for dissociation therein to free said nitrogen, power operable means operatively connected in said circuit for opening said valve means during heating of the work, means presettable to the final temperature of the work including a control switch operatively connected in said circuit to maintain energization thereof established by said switch means, a thermopile positioned for response to work heat radiation upon creation of said heating zone, work temperature indicating means including a movable element electricall connected to said thermopile for pro- Hressive movement in accordance with increase of work heat radiation, said element being adapted to cause actuation of said control switch when moved into juxtaposition with the presettable means to deenergize said control circuit and thereby extinguish said heating zone and close said valve means.

3. In an automatic heat treating machine, the

combination of a rotatable spindle, power operable means for firing a non-oxidizing heating zone around said spindle sufilcient to smother the work thereon, additional power operable means for rotating said spindle, a heating cycle starting and control circuit for said power operable means including switch means for energizing said circuit to initiate operation of said power operable means for heating and rotating the work, supply pipes supported in circumscribing relation to the work support with their outlets within said zone, valve means for connecting a dissociable gas having a nitrogen element for delivery by said pipes into said zone for dissociation therein to free said nitrogen, power operable means operatively connected to said circuit by electrical timing means for opening said valve means after said zone has been created and during heating of the work, means presettable to the final temperature of the work including a control switch operatively connected in said circuit to maintain energization thereof established by said switch means, a thermopile positioned adjacent said spindle for response to work heat radiation, work temperature indicating means including a movable element electrically connected to said thermopile for progressive movement in accordance with increase of heat radiation on said thermopile, said element being adapted to cause actuation of said control switch when moved into juxtaposition with the presettable means to deenergize said control circuit and thereby extinguish said heating zone, stop work rotation and close said valve means, and means responsive to deenergization of said control circuit to discharge work from said spindle.

4. In an automatic heat treating machine, the combination of a rotatable work spindle, power operable means for firing a non-oxidizing heating zone around said spindle sufilcient to smother the work thereon, a heating cycle starting and control circuit for said power operable means including switch means for energizing said circuit to initiate operation of said power operable means to heat the work, means forming outlets in circumscribing relation to said spindle and within said zone, valve means for connecting a dissociable gas having a nitrogen element for delivery by said outlets to effect dissociation of said gas by said heating zone to free said nitrogen, power operable means operatively connected in said circuit for opening said valve means during heating of the work, means presettable to the final temperature of the work including a control switch operatively connected in said circuit to maintain energization thereof established by said switch means, a thermopile positioned adjacent said spindle for response to work heat radiation, work temperature indicating means including a movable element electrically connected to said thermopile for progressive movement in accordance with increase in heat radiation on said thermopile, said element being adapted to cause actuation of said control switch when moved into juxtaposition with the presettable means to deenergize said control circuit, and means responsive to deenergization of said control circuit to discharge work from said support.

5. In an automatic heat treating machine, the combination of a rotatable work spindle, power operable means for firing a non-oxidizing heating zone around said spindle sufiicient to smother the work thereon, a heating cycle starting and control circuit for said power operable means including switch means for energizing said circuit to initiate operation of said power operable means, means forming outlets in circumscribing relation to said spindle and within said zone, valve means for connecting a dissociable gas having a nitrogen element for delivery by said outlets to effect dissociation of said gas by said heating zone to free said nitrogen, power operable means operatively connected in said circuit for activation upon energization thereof for opening said valve means during heating of the work, means presettable to the final temperature of the work including a control switch operatively connected in said circuit to maintain energization thereof established by said switch means, a thermopile positioned adjacent said spindle for response to work heat radiation, work temperature indicating means including a movable element electrically connected to said thermopile for progressive movement in accordance with increase in heat radiation on said thermopile, said element being adapted to cause actuation of said control switch when moved into juxtaposition with the presettable means to deenergize said control circuit, and means responsive to deenergization of said control circuit to effect quenching of the work.

6. In an automatic heat treating machine, the combination of a work support, power operable means for firing a non-oxidizing heating zone around the work support suflicient to smother the work thereon, a heating cycle starting and control circuit for said power operable means including switch means for energizing said circuit to initiate operation of said power operable means to start heating of the work, supply pipes supported in circumscribing relation to the work support with their outlets within said zone, valve means for connecting a dissociable gas having a nitrogen element for delivery by said pipes into said zone for dissociation therein to free said nitrogen ele- 18 ment, power operable means operatively connected to said circuit by electrical timing means for opening said valve means during heating of the work, said timing means being adjustable to vary the time of opening and the time of closing of said valve means, means presettable to the final temperature of the work including a control switch operatively connected in said circuit to maintain energization thereof established by said switch means, a thermopile positioned adjacent the work support for response to work heat radiation, work temperature indicating means including a movable element electrically connected to said thermopile for progressive movement in accordance with increase in heat radiation on said thermopile, said element being adapted to cause actuation of said control switch when moved into juxtaposition with the presettable means to deenergize said control circuit.

DAVID M. STRAUCHEN. MILTON GARVIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,487,554 Fry Mar. 18, 1924 1,785,137 Miller et a1 Dec. 16, 1930 1,799,614 Coberly Apr. 7, 1931 2,151,971 Holler Mar. 28, 1939 2,215,576 Bucknam et a1 Sept. 24, 1940 2,220,002 Rollman et a1 Oct. 29, 1940 2,407,230 Furkert Sept. 10, 1946 FOREIGN PATENTS Number Country Date 445,425 Great Britain Apr. 8, 1936

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