US1783156A - Heat-treating apparatus - Google Patents

Description

Nov. 25, 1930 R. E. TALLEY 1,783,156

HEAT TREATING APPARATUS Original Filei May 11 192 5 Sheets-Sheet l WITNESS HEAT TREATING APPARATUS Original ed May 11, 19,28 6 Sheets-Sheet 2 I INVENTOR wrmssS a I M8.7: -41 a NOV. 25, 1930 R TALLEY 1,783,156

HEAT TREATING APPARATUS Origiiial iled May 11, 19 6 Sheets-Sheet 3 Nov. 25, 1930.

WITNESS R.E.TALLEY HEAT TREATING APPARATUS INVENTOR i ma a. 11.4

Nov. 25, 1930.

WITNESS R. E. TALLEY HEAT TREATING APPARATUS o i i l Filed May 11, 1928 6 sheets sheet 5 NOV. 25, 1930. R. TA 1,783,156

HEAT TREATING APPARATUS Origi al Filed May 11 192 6 Sheets-Sheet 6 WITNESS INVENTOR @Mei. 7%

J W M41,

Patented Nov. 25, 1930 UNITED STATES PATENT OFFICE BAND'AL'E. TALLEY, OF IRWIN, PENNSYLVANIA, ASSIGNOR TO GEORGE J. HAGAN COM- PANY, 0F PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA HEAT-TREATING APPARATUS Application filed May 11, 1928, Serial No. 276,922. Renewed June 13, 1930.

This invention relates to improvements in heat treating, more particularly to apparatus for automatically heating, quenching and drawing the articles to be-treated.

This invention is particularly adapted for automatically heat treating crank shafts by and subjected to a drawing temperature, and

from which they are automatically discharged.

To obtain proper control of the heat cycle and to secure uniform treatment, the rotary furnaces and conveyor mechanism are 00- ordinated in their function and their drive mechanism which are electrically operated are electrically interlocked to secure the proper sequence of operation through all stages of the heat treating process.

In the accompanying drawings constituting a part hereof and in which like reference characters designate like parts, Fig. 1 is a plan view diagrammatically illustrating hardening and drawing furnaces with a cooperating conveyor mechanism embodying the principles of this invention; Fig. 2 is a top plan view of the charging and discharging mechanism which is the same in both furnaces; Fig. 3 is a sectional elevational View of the charging mechanism; Fig. 4 is a similar View of the discharge mechanism; Fig. 5 is a diagrammatic view illustrating the conveyor mechanism; Fig. 6 is a detail view of the discharge end of the conveyor and Fig. 7 is a view diagrammatically illustrating a control circuit for the automatic operation of the rotary furnaces, conveyor mechanism and charging and discharging mechanism in accordance with the stated objects of the invention.

Referring to Fig. 1 of the drawing, the hardening furnace is generally designated at 1 and the draw furnace at 2. These furnaces are similar in construction and are operated through suitable gear reduction mechanisms and rotary hearth indexing pawls generally designated at 3 by electric motors 4.

The operation of the hardening furnace is under control of an automatically repeating time clock which closes a contact successively at predetermined intervals to energize the drive motor which advances the hearth of the hardening furnace one stationby means of the indexing pawl.

The furnace is then charged and discharged in a manner hereinafter explained and the heated article is delivered into a quenching tank from which it is carried by the conveyor mechanism generally designated at 5 tothe charging trough 6 of the drawing furnace 2.

The conve or mechanism is operated throughsuita le gear mechanism driven by a motor 7 which is electrically interlocked with the motor 4 of the draw furnace. The electric control of the respective motors will be explained in detail in connection with the diagram shown in Fig. 7.

As shown in Fig. 1, a charging trough 8 receivesthe material to be charged into thefurnace 1 and a receiving trough 9 is provided adjacent the conveyor mechanism 5 upon which the heated shaft is placed when discharged from the heating furnace 1. Similarly, a receiving trough 10 receives the treated shaft when discharged from the drawing furnace 2 from which it is placed on a conveyor mechanism 11 which carries it to the next operation to which the finished treated shaft is subjected after heat treatment.

The article to be treated such as a crank shaft, is charged and discharged into and out of the furnace by the mechanism illustrated, in Figs. 2, 3 and 4 of the drawing, which also provides for the automatic opening and closing of the furnace doors at properly timed intervals to reduce the loss of heat in the furnace chamber to a minimum. It will be seen from an inspection of Fig. 2 of the drawing that the charging and discharging mechanism as well as the door opcrating mechanism are operated by a single motor 13 which is connected through a system of gearing 14 to shafts 15 and 16 on which are mounted crank arms-17 and 18 that are connected by links 19 and20 to pusher heads 21 and 22 which respectively operate to move the material from the charging trough into the furnace and from the furnace into the discharging-troughs.

In Fig. 3 the charging mechanism is illustrated in detail. In this view, 25 illustrates a trough shapedcasting mounted on the rotary hearth of the furnace, and the door 26 for controlling the passage 27 through which the material is charged into the furnace chamber. The charging trough 8 is in alinement with the passage 27 and a crank shaft when deposited on the trough 8 is pushed through the passage 27 by the pusher head 21 which is operated through a: lever 28 that operates through a pantograph to provide a straight line movement of the head 21 as illustrated bythe extended portion of lever 28 shown in dotted lines. The linkage connecting the lever 28 is pivotally connected to a slide block at 30 and the slide block is pivotally connected at 31 to the link 19, the

. slide blockoperating in a guide 32.

The furnace doors 26 are adapted to be raised and lowered through a cam mechanism which comprises a cam 34 mounted to rotate with shaft 15 that operates the pusher head. A cam follower 35 cooperates with the cam 34 and constitutes one end of a bell crank 36, the other end of which carries an arm 37 that is pivotally mounted to a link 38 at 39 which iii operates the doors.

The cam 34 is designed to raise the door 26 through the arm 37 as the head 21 moves 1nwardly to push the crank shaft on the furnace hearth and in like manner the door 26 is lowered when the head 21 is withdrawn from the furnace. With this arrangement the operation of the door and charging head are coordinated to control the time during which the door is open thereby reducing loss of heat through passage 27.

In Fig. 4 is shown the structural elements of the discharge mechanism which is operated through the same motor that drives the charging mechanism shown in Fig. 2. By the arrangement of Fig. 4 a door 40, controlhng the discharge passage 41 leading to the furnace chamber, is operated through a lever 42 that is actuated by the movement of a cam follower 43 cooperating with a cam 44 carried by the shaft 16 that operates the crank 18 of pusher head 22. The crank 18 is connected through a pantograph linkage to a lever 45 that actuates the head 22 to push the crank shaft from the hearth 25 of the furnace through the discharge passage 41 onto the receiving trough 9 or 10 of the conveyor mechanism and as is the case of the charging mechanism the door 40 1s opened and closed in accordance with the movement of the head 22. The pusher head 22 of the discharge mechanism carries a contact 46 gages a pusher head 47 that releases a latch when it is moved by contact with the pusher head 22 in its extended position. The latch is designed to release a quenching cradle 48,

Fig. 5, pivoted at 49 to the conveyor support and the cradle which is normally biased by a counterweight 50 to the horizontalposi-' tion', becomes unbalanced by the weight of the shaft and lowers the shaft into the quenching medium which is contained in a tank-51 in which the conveyor mechanism 5 is mounted. When the shaft has droppedfrom the cradle 49 it again assumes its normal horizontal position and is secured by the latch which is operated by the pusher head 47.

The conveyor for transferring the shaft out of the'quenching tank 51 is of the endless chain or belt type shown at 53 and is mounted on sprockets, one pair of..which is adjustable through a screw mechanism 54 to take up the slack. The shafts in passing out of the quench are passed undef' a plurality of apron switches 55, 55 and 56 which control the motor circuit of the drawing furnace hearth as well as the motor for operating the charging and discharging mechanism for the drawing furnace. The shafts are placedby the conveyor 53 on the charging trough 6 of the draw furnace 2 from which they are automatically charged into the furnace by the mechanism described in connection with Fig. 3 of the drawing and when a shaft is charged into the draw furnace a treated shaft is'discharged from the furnace to the receiving trough 10 from which it is dropped on a conveyor leading from the draw furnace.

' The various operations as hereinafter explained are conducted in their proper sequence through the electric interlocking of the hearth, drive motors, and the conveyer drive mechanism in the manner illustrated in Fig. 7 of the drawing which is as follows: A plurality'of limit switches 61, 62 and 63 are mounted on the hearth drive and operated by a cam on the hearth drive main shaft.

hearth drive pawl is actually moving the hearth. The contacts are closed while the pawl is returning through the idle part of its stroke. Switches. 62 and 63 are operated by cams in such manner that the switchesare permitted to close for a short momentary con- The contacts of switch 61 are open while the tact, only once during one revolution of the hearth drive shaft. Switch 62 is for the purpose of stopping the hearth drive motor and switch 63 for starting the charger motor. The purpose of switch 61 is to provide a hearth interlock as hereinafter explained.

' A limit switch 64 which is a duplicate of the switch 62 is mounted on the charger drive shaft and operates to close the contacts only once during one revolution of the shaft. The purpose of switch 64 is to stop the charger drive.

65 designates the time clock motor which will make a momentary electric circuit through the clock contact 65 at definite and automatically repeated intervals. The intervals may be varied at will from its minimum of five seconds to a maximum of'two and onehalf minutes in steps of five seconds each. The clock relay 66 comprises a small single circuit magnetic switch with interlock 67. The interlock is a flexible connection one end of which is electrically connected to the movable bar of the relay. The source of electric supply comes to the interlock 67 through the circuit a in the diagram. When the relay closes, two circuits are closed starting two motors. When the relay is opened, there is no connection between the two motors and therefore no sneak circuit can exist at this point.

A hearth drive relay and charger drive relay 68 and 68' are provided with two pairs of contacts and two operating coils each. The pair of contacts which close to start a motor will be designated as the normally open contacts and the other. pair as the normally closed contacts. The two pairs of operaing coils consist of a closing coil 69 and opening coil 70 for the hearth drive relay and closing and opening coils 69' and'70' respectively for the charger drive relay. A

hearth drive contactor coil 71 and-charger drive contactor coil 71 are included in the hearth drive and charger drive relay circuits. By opening the normally closed contacts of the drive relays, the circuit through the closing coils 69 and 69 will also open. When the opening coils 70 and 71' are energized the reverse operation takes place, that is, the normally open contacts will open, the normally closed contacts will close and the circuit through the opening coils will be broken. The two drive relays used for the draw furnace are supplied with one extra pair of normally closed contacts. each to provide for interlocking the conveyor as will be hereinafter explained.

The entire heat treating cycle may be d1vid ed into five operations as follows z--- The first operation consists of rotating the hardening furnace until an unoccupied hearth section is in line with the charging door 26, and a heated charge in line with the discharging d or 40. The time clock 65 closes its contact 65 which in turn closes the clock relay 66. This completes the circuit through closing coil 69 of the hearth drive hearth drive contactor 71 to start the motor. 'The current through the drive relay must also pass through limit switch 61 or switch 46 on the discharger head. These two switches are in parallel and the hearth drive motor will run if either or both are closed. Inasmuch as limit switch 61 is closed only while the hearth drive pawl is in the idle part of its stroke, no damage can occur if switch 46 is opened while limit switch 61 is closed.

Moreover, since limit switch 61 is always open while the hearth is actually moving, the hearth motor will stop if switch 46 should open while the hearth is moving. is closed only while the charager and discharger are in their extended outward positions and since the charger takes its control current through these same switches, it is impossible for the hearth and charger to be out of place at the same time. If through accident both should tend to be movingat the same time, both switches will open and the entire equipment is at a stand still until the trouble is located and corrected.

The hearth motor 4 is stopped by switch 62 which completes the circuit through opening coil 70 of the hearth drive relay. This opens the normally open contact of the relay thereby opening the circuit through the drive contactor coil 71. Limit switch 62 is closed momentarily and should be adjusted to make its contact after the hearthhas completed its movement and just before limit switch 61 opens. Allowance should be made in the setting of limit switch 62 so that the drift of the motor will not open limit switch 61. v

The second operation comprises lifting both doors 26 and 40, charging material into the unoccupied hearth section and discharging the heated material into the quench. The doors are lifted by'means of cams 34-44 and the charger-and discharger are operated by cranks 17 and 18, all driven by the motor 13 Switch 46 in the manner explained in connection with 63 closes to the time-when either switch 64 or limit switch 62 closes. The charger motor is stopped by limit switch 64 which makes a momentary contact to complete the circuit through the opening coil 7 of the charger drive relay 68'. This opensthe normally open contacts of the relay thereby opening the circuit through the drive contactor coil 71'. Switch 64 may be adjusted so that the charger and discharger will drift into their extended outward positions and close switch material on the conveyor 5 underneath the quenching medium. The conveyor runs contmuously and when the material reaches a point over the head shaft of the conveyor, it falls into the draw furnace charging trough 6. Material however passes under the apron switches 55-55 and the switch 56. The switch 55 is parallel with one pair of normally closed contacts of the charger drive relay 68' and switch 55 is parallel with one pair of normally closed contacts 9f the hearth I drive relay 68. If both the hearth and are op charger are at rest, the conveyor 5 will continue to run even though switches and 55 en. If these switches are closed, the conveyor will continue to run even though the draw furnace is going through its cycle, therefore the conveyor Wlll stop only ifa charge has entered the draw furnace charger trough 6, thereby starting the furnace cycle by tripping switch 56, and a subsequent charge or material passes under switches 5555 and opens the same before the furnace cycle has been completed. When the cycle is complete and the normally closed contacts of relays 68 and 68 have closed, the conveyor will automatically start. In this manner material is prevented from entering the charger trough before the previous charge has been disposed of. Since the conveyor control circuit is connected through limit switch 61 or switch 46, the conveyor as well as the draw furnace hearth and charger will stop, but these switches are open at the same time in the manner described under the first operation.

In the fourth operation the draw furnace hearth is rotated until an unoccupied section is in line with the charging door 26 and a heated charge in line with the discharging door 40. This operation is a duplicate of operation one on the hardening furnace 1 except that the hearth motor is started by switch 56 instead of the time clock 65. A

. in the same manner.

double throw knife switch is provided to start the draw furnace from the time clock if-desired.

In the fifth operationboth doors of the draw furnace are lifted, material is charged into the unoccupied section and heated material is discharged into the trough 10. This operation is a duplicate of operation 2 on the hardening furnace and is accomplished A knife switch is provided for stopping the conveyor drive by open circuiting the contactor coil 72 and a push button station 73 is provided for the same purpose. Switch 80 is located on'the control panel and the push button station 7 3 is located to be available to the furnace operator.

It is evident from the foregoing description of this invention that by the utilization of automatically controlled hardening and drawing furnaces with a connecting conveyor mechanism, and mechanical and electrical interlocks, articles such as crank shafts may be uniformly-heat-treated by automatically heating, quenching and drawing the same whereby the physical characteristics of the heat treated article are accurately and positively controlled.

One of the advantages of the automatic operation of the furnaces is the economy of heat elfected by controlling the duration of the quench so that the article doesnot require the same amount of heating when it reaches the draw furnace as would be neces: sary to treat it if cold. In the heat treatment of crank shafts, it is desirable to produce a relatively hard surface and a ductile core so that the shaft need not be quenched to a cold state before it is charged into the draw furnace.

Although one of the embodiments of my lUU lUS

invention has been herein illustrated and described, it will be obvious to those skilled in the art that various'modifications may be made inthe details of construction and in the arrangement of the several parts without depart ng from the principlesherein set forth. It Wlll also be evident that the same system of control may be applied to furnaces from which the material is discharged by the tiltmg of trays, or the hearth sections, on which the material is carried.

I claim herein as my invention:

1. Heat treating apparatus comprising in I and discharging the material to and from the hearth of said furnace, and means for stopping the movement of said conveyor when an article is brought to the charging position.

3. Heat treating apparatus comprising in combination a rotary hearth furnace and a conveyor mechanism for conducting material thereto, means for automatically charging and discharging the material to and from the hearth of said furnace, and means for stopping the movement of said conveyor when an article is brought to the charging position and for again starting said conveyor when said article has been charged into the furnace.

4. Heat treating apparatus comprising in combination an annular furnace chamber, a rotary hearth operative in said chamber, means for automatically charging and discharging material into and out of said furnace, and mechanism operated by said charging and discharging means for automatically opening and closing the furnace doors.

5. Heat treating apparatus comprisin in combination an annular furnace cham er, having a charging and discharging passage leading thereto, doors controlling said passages, a rotary hearth operative in saidchamber, and means for automatically charging and discharging material to and from said hearth and for opening and closing said doors.

6. Heat treating apparatus comprising an annular furnace chamber, a rotary hearth operative in said chamber, a drive mechanism for said hearth comprising a motor actuated indexing pawl for advancing the hearth in predetermined increments, a time clock controlling said hearth motor, a charging and discharging mechanism for loading and unoperative in said passages to push material onto and from said hearth, mechanisms for actuatingsaid material moving members, and a pantograph linkage connecting said members and their'actuating mechanism'whereby the material is charged through said passages by a straight line movement in a longitudinal lane. 1 p 9. Heat treating apparatus comprising a rotary furnace having a plurality of passages and a motor driven charging and discharging mechanism for loading material onto and from the furnace hearth, motor driven means for advancing the hearth in predetermined increments, means for interlocking said hearth and charger motors, a conveyor mechanism for conducting material to thecharging mechanism, means operated by said conveyor for stopping the latter when material is placed in the furnace'charging passage and for energizing the charger motor, and

means for automatically starting said conveyor.

In testimony whereof, I have hereunto set m hand.

y RANDAL E. TALLEY.

loading material on the hearth, a motor their hearth rotating and charging and discharging functions.

7. Heat treating apparatus comprising an annular furnace chamber, a rotary hearth operative in said chamber, a drive mechanism for said hearth comprising a motor actuated indexing pawl for advancing the hearthin predetermined increments, a time clock controlling said hearth motor, a charging and discharging mechanism for loading and unloading material on the hearth, a motor driven actuating mechanism therefor, and means for open-circuiting said hearth drive motor when said charging and discharging mechanism is actuated.

8. .Heat treating apparatus comprising an annular furnace chamber, a rotary hearth operative therein, said chamber having charging and discharging passages in alinement with said hearth, material moving members

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