US2009481A - Heat treating machine - Google Patents

Description

July 30, 1935. w. A. DARRAH HEAT TREATING MACHINE Filed Feb. 19, 1932 4 Shgfiets-Sheet 1 [711/9 12 tor.

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Patented 1.1, so, 1935 UNITED STATES PATENT OFFICE 17 Claim.

This invention relates to processes, methods and equipment for heat treating and while it is particularly applicable to the heat treating of steel, this invention may be applied in many cases to heat treatment of other metals or indeed of many other materials.

The object of my invention is to provide a simple, compact and economical apparatus and method for subjecting steel or other materials to a pre-determined cycle, typical examples of which will be described later in this specification.

One of the objects of my invention is to provide mechanical means for insuring exactness of the cycle, both as to heating timeatransfer times, temperatures and other important details.

One important feature of my invention is the provision of mechanical transfer means which will be positive, simple and permit easy reduction of speed and other factors. Other features of 20 my invention involve a utilization of the fuel with a high degree of economy.

By utilizing mechanical transfer and moving means I also eliminate the many variable factors which result from manual operation which is at present almost universally the case in this field. f In order to explain my invention I will select a specific case of heat treating steel, although it should be distinctly understood that the methods and apparatus here set forth can be applied 'with equal success to many other materials by making certain obvious changes.

Referring to the drawings, Figure 1 shows a plan view of one form of my invention. Some portions of the equipment are shown broken away 35 and partly in section in order to more clearly set forth the details of construction.

\ Figure 2 shows a vertical elevation partly in Referring to the drawings, l indicates a frame or structure which supports the mechanism. A

motor 2 driving a speed reducing device 3 serves to activate shaft 4. A series of bevel gears or the equivalent 5, 6, I, and 8 serve to operate respectively shafts 9, l0, H and i2. Each of these shafts carries an arm as for example l3, I4, I 5

and I6. These arms which may be substantially identical although difierent in length if desired, carry near their outer end an engaging pin as for example IT. The pin is substantially similar on all of the arms. The arms may be so arranged as to show a definite angular displacement at any 5 one time for purposes to be later discussed.

Located beneath the frame I are a series of containers for carrying on the various operations. One of these containers is indicated as a metal pot I8, which may be formed from steel or alloy 10 and which is supported by a refractory setting l9 and heated by means of a burner 20 arranged for oil, gas, powder 2d coal or other desiredfuel. The setting IQ for pot It, may be insulated'as required for example by the insulation 2i. The 15 products of combustion after leaving the combustion space in setting I! beneath pot l8, may pass by. means of flue 22 to outlet 23 which for purposes of clearness'may be called the preheat position. eflue 22, preheat position 23, set- 20 ting l9 and e pot l8 may be housed in a suitable shell or other material, as indicated by 24. I have shown housing 24 resting on the floor or ground although obviously this may be raised to any desired height. v 25 In pot I 8 I have'shown a liquid indicated by 25 which may be a fused salt such as cyanide, nitrate, chloride, etc. or it can be a molten metal such as lead or in certain cases zinc, tin, etc. may be employed. In these latter cases the oper- 30 ation would involve a coating or covering of the material placed in the pot as well as the heat treating. Adjacent to pot 18 I have shown a container 26 filled to level 21 with a cooling or quenching 35 liquid such as oil or water. This container should preferably be somewhat larger than pot l6 and some means such as coil 26 should be provided to remove the heat which is liberated from time to time. In place of coil 28 I may as an alter- 4 hate introduce the cooling medium through inlet 29 and remove it through outlet 30. On cooling the oil or other medium it may be returned to container 26 or in the case of water, it may be run to waste.

Adjacent to container 26 I have shown an additional container 3| filled with a cleaning or washing solution 32 and provided with inlet flange 33 and outlet flange 34. Steam coils 35 maybe provided for maintaining the solution a: at the de- 50 sired temperature. The solution may consist of water containing various cleaning solutions such as sodium silicate, tri-sodium phosphate, soaps or dilute acids or alkalies.

Placed adjacent to containers ll, 26 and II is 55 a drawing chamber 36 enclosed by wall 31 with insulation 38 and connected by air moving device 39 so as to draw a portion of the products of combustion from setting l9 and thereby supply controlled heat to drawing chamber 36 through duct 40. The arrows indicate the direction of circulation of the heated mixture of air and gases. It will be noted the hot gases-after travelling through the drawing chamber 36 return in large measure to the vent 39A where they are reheated and then recirculated through fan 39 to chamber 36.

The material to be treated is to be loaded in baskets or containers 4| which are carried by rod a2 provided at its upper end with a socket 43 arranged to engage pin Socket 43 also carries a-pair of rollers 44 and 45 for purposes to be later described Rollers 44 and 45 are arranged to rest on supporting angle or track 46 and to slide on inclined track 41 for conveying the material after leaving the various baths.

It will be understood that I may use any part of the equipment here shown and described without the entire assembly. For example in many cases the drawing chamber 36 with its associated equipment may be omitted in which case the articles being treated would be passed through the hot bath 25, the quench 21 and the washing 32 after which the operation would be complete. It is also evident that if the drawing chamber 36 is employed the washing bath 32 may be omitted or if desired the washing bath 32 may also serve as the quench medium. I may, therefore, make many arrangements and alterations in the apparatus which I have disclosed, without departing from the spirit of my invention.

In case the drawing chamber 36 is omitted the return portion of track 41. indicated by 48 should be continued so that the treated material will return by gravity to the starting point, otherwise track 41 is terminated at point 43 with a stop 49. In this case shaft 50 carrying arm 5| which is similar to arms l4, l5, l6, etc. already described, serves to remove the material from track 48 and place it on track section 52. On this track it is rolled through drawing chamber 36 by means of chain 53 and at the end of drawing chamber 36 the work is elevated by means of arm 54 actuated by shaft 55 and replaced in the position indicated by member 56A on track 51. From this point the container or basket travels by gravity to the starting point. Shafts 50 and 55"are shown driven by means of shaft 56A and the pairs of bevel gears 51 and 56. Shaft 56 is in turn caused to revolve by means of chains 59, 60 and 6| using the obvious means of sprockets and countershafts as illustrated. Chain 53 is shown passing in a close circuit around sprockets 62 and 63 which may be driven in any convenient manner, preferably from original motor 2.

In operating my equipment the material to be treated is loaded in container or basket 4|. A

a series of rods or shafts represented by 65 are used to illustrate the load. These may be placed in a vertical position which is quite desirable for both heating and quenching.

A cover 66 is shown permanently attached to supporting member 42 in the position indicated.

After loading the work in container 4| it is allowed to stand a pre-determined time over the preheat position 23. In this position the waste heat of a portion of the products of combustion of pot l6 pass around and in contact with the material 65.

It will be understood that basket 4| is either constructed merely as a frame work or is fully perforated so as to provide ready access and exit for gases or for the liquids during the treating process. When it is desired to operate the equipment a timing mechanism or other desired form of switch closes an electric circuit setting motor 2 in operation. Shaft 4 is then caused to revolve and in turn each of the counter-shafts 9, III, II and I2 and associated equipment begin to revolve. The arms l3, l4, l5 and I6 then engage with the upper end of the carriers of the baskets or containers in each of the respective positions and successively lift the container from the washing tank 3 I, placing it on track 41 so that it travels into position for the drawing operation. As every rotation continues arm I4 lifts the preceding container from the quench bath 26 and places it in the washing condition. In the same way arm I5 lifts the container from the pot containing the heated bath and quickly transfers it into the quenching position while the first arm lifts the hanger from its position on track 66 the preheat position and places it into the quench tank. Each of these operations is carried out as the shafts make a revolution not exceeding After a revolution of 180 has been made a limit switch opens the electric circuit and the equipment remains at rest until the timing device or the equivalent manually operated switch again starts the apparatus in motion and the cycle .is repeated.

The -peed of transfer is so adjusted that th 180 revolution is made in a few seconds preferably a period ranging from '3 to 10 seconds. This time is of course controlled by the speed of revolution of the shafts, carrying the various lifting arms. It will be noted that the material being .treated remains in each of the positions substantially the same length of time and that this period is accurately duplicated each cycle. Tlus I consider of great importance. The maximum time required for any one step in the cycle naturally controls the time of all of the apparatus.

While the shafts 9, ||I, II and I2 are in operation transferring the material being treated from one basket to the next, shafts 56 and '55 *are revolving, one (shaft 50) placing a new basket in the drawing chamber 36 while the other (shaft 55) serves to withdraw a basket from chamber 36 placing the trolley which carries this basket in the position indicated by 56A in track 51.

A typical cycle which I have found very effective in treating certain steels, consists in preheating the material over duct 23 until it reaches a temperature between 600 and 700 F. The material is then automatically transferred as explained, into pot I8 which may contain fused cyanide maintained at a temperature of approx imately 1520 F. It will be noted that the preheating time is suf'icient to materially raise the temperature of the articles, thereby lessening the thermal shock when they are placed in the high temperature bath and also reducing the amount of thermal work which must be done in bath 16. It is desirable in most cases, however, to keep the temperature of the articles during the preheating period below the point at which scale or oxide will form.

In treating small shafts or rods having a diameter ranging from to inch, a heating time ranging from fifteen to twenty minutes in each of the positions has proven very satisfactory. A transferring period of five to six seconds is desirable particularly from the fused bath 2| into the quench solution 21.

For many purposes it is desirable to use for the quenching medium oil, maintained at a temperature between 90 and 100 F. This period should also be in the neighborhood of fifteen to twenty minutes. The time required for washing or rinsing likewise is ordinarily between fifteen and twenty minutes and a good cleaning solution maintained at a temperature close to the point and at boiling water will readily obtain the desired results. For drawing, I prefer to use a considerable longer period than that provided in the other operations. In many cases I wish to employ two temperatures ranging from 400 to 600 F. and a heating time ranging from a minimum of perhaps forty-five minutes to a maximum of perhaps an hour and a half.

It should be understood that the composition of the steel or material being treated, the results which it is desired to obtain and the purpose for which the apparatus will be used all have an important part in controlling both time periods and temperatures.

As an aid to efficiency cover 66 is so located that it will close the top of the various containers as for example I8, 26, 3|, etc. when they are in the proper position. In order to obtain a proper register cover 66 is movably supported on rod 42 being located by lugs 69. This permits the cover 66 to engage with the top portions of the various containers while the basket itself seeks its proper level. The use of cover member it not only serves to prevent heat loss, but also effectively retains fumes, vapors, etc. which would ordinarily come from the fused bath, the quench bath and the washing solution.

-I have found with my equipment that one operator can handle the work ordinarily required of from four to six men by present methods. The saving in labor, therefore, is very great. The\ labor saving is of course due to the elimination of manual labor and the fact that the equipment not only mechanically transfers the material treated from each stage to the next, but also returns the finished work to substantially the position occupied by the operator.

By means of using a portion of the products of combustion to preheat the incoming cold work and another portion to draw the finished articles, the recovery of the heat is extremely high. It will be understood that in the drawing operation additional fuel is burned to supplement the waste heat from the products of combustion, and the controlled temperature is held under automatic control by means of increasing or decreasing .the fuel suppliedfrom the auxiliary burner I0. As a result of this arrangement I obtain great economy of fuel.

By reason of the mechanical transfer and the automatic timing each step in the operation of time equipment is carried out without-manual care on the part of the operator. It will be apparent, therefore, that all materials treated pass through exactly the same cycle and, therefore, there will be no defective work as in the case of present manual apparatus. By giving a quick transfer, which is possible with the ap aratus and process I have invented, the change of condition during the transfer time is relatively small; This is of great importance as for example a slow transfer between pot l8 and container 26 would cause the material to lose considerable heat, so that the results of the quenching operation would naturally be irregular and uncontrollable.

' Since my apparatus substantially duplicates the transfertimeineachcase,thisdimcultyis eliminated.

The cover member 06 may serve to retard and prevent the loss of heat during the transfer period both by supplying radiation and restricting the circulation of currents of cooler air.

By using the preheating arrangement and doing less thermal work'in pot I8, I am able to operate this pot at a materially lower temperature than would otherwise be possible. This-results in a materially increased length of pot life. I have been able to obtain a pot life exceeding 2000 to 3000 hours, while under normal conditions with the same amount of work the pot life would only be slightly in excess of 1000 hours.

By placing the arms I3, l4, l and It at diflerent angular relations, I am enabled to so arrange to get a rapid transfer which would be quite impossible with an apparatus of this kind, if the motion were continuous. For example a continuous motion of arm l5 sufliciently slow to give the requisite time for the material in bath 25 would seriously cool the material during the transfer period and the quenching operation would be quite unsatisfactory.

I, therefore. consider the intermittent operation of my device of considerable importance in containers or pots may be interchanged as desired.

In order to control the extent of the preheat obtained over outlet 23, I have provided damper l5 connecting outlet flue 23 to the outside air by means of duct 16. By opening or closing damper I5 varying amounts of outside cold air can be drawn into: the preheating chamber thereby diluting the hot products of combustion and lowering their temperature. It will .be apparent that this device permits controlling the temperature of the kettle in the preheat position without effecting the amount of fuel burned under pot. It. It will also be apparent that unless I have some such means for controlling the temperature of the mixed gases passing upward over the work, V

the material being preheated may at times reach undesirable temperatures.

Referring to Figure 5, 10 indicates the main line conductors which for purposes of illustration are shown as indicating a three wire or three phase alternating current electrical circuit. I9 indicates diagrammatically a squirrel cage or induction type motor used for driving the equipment. 80 indicates the automatic timer which may be considered as consisting of any standard device for this purpose now on the market. These devices ordinarily consist of a clock mechanism either electrically driven or by spring in the usual manner. They are so arranged as to close an electrical circuit at intervals. The circuit to be closed in this case is indicated by 8|. The relay contacts being closed are shown as 82. The limit switch employed to stop the equipment after each revolution of the lifting arms is shown diagrammatically by the lever 83 pivoted at 84 and carrying on its upper portion a gravity actuated switch member 85 indicated on the drawings as a mercury contact switch. The limit mechanism is housed in container 86 shown for purposes of clearness in dotted lines. A pair of fusesB'l may be provided to protect this equipment in case of short circuit or other failure. Lever member 83 is rotated out of the normal position by means of 9, lug 88, which is indicated diagrammatically in Figure 5, but which in practice wouldbe mounted on one of the moving arms as for example I6.

As previously explained, the automatictimer 88 periodicallycloses the contact 8|, threby actuating relay 82 which in turn energizes coil 89 thereby closing switch 90 and-setting the motor I8 in operation. After any of the moving arms have completed one revolution the contact of lug 88 on moving arm I6 tips lever 83, thereby closing a circuit which opens relay 82 in turn opening switch 98, stopping motor 19.

In the past, in carrying out operations similar to those for which my equipment and process is designed, it has been customary to depend on manual estimates of time, temperature and other factors. It will be noted, however, that my equip ment offers means of rigidly and mechanically maintaining any desired cycle including all of the various steps; and such cycles cannot be varied by the workmen. 0n the other hand, the timing of my equipment can be instantaneously changed by merely setting a hand on the automatlc timer 80 for any desired cycle. My equiping, heating and drawing operations and serve to retain fumes and vapors in the quenching or cleaning operations.

It will be apparent that by making motor 2 of the variable speed type and following any of the well known constructions for this kind of device, I can at will change the speed of rotation of transfer arms such as l3, l4, l5 and I8 and can, therefore, very readily adjust the transfer time without affecting other constants of the heat treating cycle, such as the time in the heating bath, drawing oven, etc. I, therefore, consider one of the advantages of my device the ability to vary the transfer time independently of other factors in the heat treating cycle.

By utilizing the gravity return as previously outlined it is possible to materially reduce the cost of equipment constructed in accordance with my invention and yet accomplish the saving of labor by eliminating necessity for the operator to move from his normal position. It will be apparent that in order to obtain a gravity return, it is necessary for the supporting track on the return side to be inclined with the horizontaland the transfer mechanism which I have em,- ployed permits such inclining in that it is able to lift the trolleys carrying the materials to be treated from a low position and discharge them at a more elevated position. This I consider one of the peculiar advantages of the conveying type of mechanism which I have devised.

It should be understood that while I have describedthe mechanism used in carrying out the heat treating process in the terms ordinarily employed for heat treating equipment, the mechanism I have disclosed can to equal advantage be used in connection with many other operations, such as electro-plating, cleaning, pickling, dye-' ing,'coloring, etc. In general terms, therefore, I designate my equipment as intended for treating materials in order to properly cover the field to which it may be properly applied.

An additional air heater may be employed as indicated to supply heat when the main burner underpot I8 is not operating or does not supply sufficient heat for the operation.

Having now fully described my invention, which I claim as new and wish to secure by Letters Patent, is as follows:

1. An equipment for heat treating consisting of a material carrier, a loading station and a multiple of adjacently arranged housings, the interiors of which are maintained at different temperatures, one of said housings serving to preheat, another to heat, and another to quench and a mechanical timer to control the interval between transfer, said heating housing being adapted to hold a heated liquid bath, and an intermittently operated transfer mechanism arranged to automatically transfer the material carrier and material being treated successively from one housing to the next, and back to said loading station, all as actuated by said automatic timer.

2. An equipment for heat treating consisting of a multiple of adjacently arranged housings, means for maintaining the interior of said housings at different temperatures, an intermittently operated transfer mechanism arranged to automatically transfer the material being treated successively from the interior of one housing to the interior of the next, and gravity operated means for returning said material being treated from a position adjacent the final housing to a position adjacent the initial housing.

3. An equipment for heat treating consisting of a multiple of adjacently arranged housings, means for maintaining the interior of said hous- 11185 at different temperatures, an intermittently operated transfer mechanism arranged to automatically transfer the material being treated successively from the interior ofv one housing to the interior of the next, gravity operated means for returning said material being treated from a position adiacent the final housing to a position adjacent the initial housing and electrically operated automatic timing equipment controlling the interval between operations of the transfer mechanism.

4. An equipment for heat treating consisting of a multiple of adjacently arranged housings, means for maintaining the interior of said housings at different temperatures, an intermittently operated transfer mechanism arranged to automatically transfer the material being treated successively from the interior of one housing to theinterior of the next, gravity operated means for returning said material being treated from a position adjacent the final housing to a position adjacent the initial housing, and means for controlling the speed of transfer from one housing to the next.

5. An equipment for treating materials consisting of a multiple of adjacently arranged housings, means for maintaining the interior of said housings at different temperatures, a conveyor mechanism for transferring the material being heated automatically and successively from the interior of one housing through a vertical curvilinear path into the interior of the next housing and finally'to the elevated portiBn of an inclined track arranged to return said material being treated by gravity to a point adjacent the first of said series of housings.

-6. An equipmentior heat treating consisting-of a multiple of adjacently arranged housings, means for maintaining the interior of said housings at different temperatures, a supporting member arranged to carry the material to be treated, a cover carried by said supporting member and arranged to substantially close said housings, and an intermittently operated transfermechanism arranged to automatically transfer said supporting member successively from one housing to the next.

7. An equipment for heat treating consisting of a multiple of adjacently arranged housings, means for maintaining the interior of said hous ings at diiferent temperatures, a supporting member arranged to carry the material to be treated, a cover carried by said supporting member and arranged to substantially close said housings, an intermittently operated transfer mechanism arranged to automatically transfer said supporting member successively from one housing to the next, and a conveyor for automatically returning said supporting member from the final housing to a position adjacent the initial housing.

8. In an equipment for treating materials, a series of stations including a loading station, a preheat station, a heating station and a quenching station, means for delivering waste heat from said heating station to said preheating station, a work support for material being treated and an intermittently operated transfer mechanism arranged to automatically transfer said support for said work being treated and said work successively from one station to the next and finally back to the starting point at predetermined intervals, driving means arranged to simultaneously actuate said transfer mechanism and electrically timed means for controlling the interval between successive movements of said transfer mechanism.

9. Arr equipment for treating materials consisting of a multiple of adjacentlyarranged housings, means for maintaining the interior of said housings at different temperatures one of said housings serving to heat said material, and another housing to quench said material, a loading station, a support for said material being treated, a transfer mechanism arrange d'along said housings to automatically and'j -rr'iechanically transfer said support and its lo'ad' offm'aterial successively from the interior'of .onehnusing to the interior of the next, and back to the starting point, and an automatic timing device controlling the time of operationof said mechanism said transfer mechanism being arranged to operate intermittently under the control of said automatic timing device.

.10. An equipment for treating materials comprising a preheat housing, a heating housing and a quenching housing, an intermittently operated transfer mechanism extending above said housings and arranged to automatically transfer the materials being treated successively from one housing to the next and mechanically operated timing means for controlling the interval between successive movements of said intermittently operated transfer mechanism.

11. An equipment for treating materials comprising a preheat housing, a heating housing and a quenching housing, an intermittently operated transfer mechanism extending above said housings and arranged to automatically transfer the materials being treated successively from one housing to the next, mechanically operated timing means for controlling the interval between successive movements of said intermittently operatcd transfer mechanism, and-a conveyor for automatically returning thematerial to be treated from said quenching housing to a position adjacent said preheating housing.

12. An equipment for heat treating consisting of a heating housing adapted to contain molten material, and a quenching tank arranged adjacently to each other, a support for material being treated, means for maintaining the interior of said housing at a controlled temperature, an intermittently operated transfer mechanism arranged to periodically transfer said support and material to be treated successively from a loading station into said heating housing and finally into said quenching chamber, and a conveyor mechanism for mechanically returning said sup-' port and material being treated back to a point adjacent said loading position.

13. An equipment for heat treating consisting of a heating housing constructed to contain liquid material, quenching tank, and a washer arranged adjacently to each other, a support for material being treated, means for maintaining the interior of said housing at controlled tem peratures, 'an intermittently operated transfer mechanism arranged to periodically transfer said .support and material to be treated successively from a loading station into said heating housing, then into said quench tank and finally into said washer, and a conveyor mechanism for mechanically returning said support and material being treated back to a point adjacent said loading position.

14. An equipment for heat, treating consisting 'of a heating housing constructed to contain said drawing oven, and a conveyor mechanism' for mechanically returning said support and material being treated back to a point adjacent said loading position.

15. An equipment for heat treating consisting of a preheating housing, a heating housing constructed to contain molten material, a quenching tank, a washer and a drawing oven all arranged adjacently to each other, a support for material being treated, means for maintaining the interior of said housings at different.

temperatures, an intermittently operated transfer mechanism arranged to periodically transfer said support and material to be treated successively from a loading position into said preheating chamber, said heating chamber, then into said quench tank, said washer and finally through a drawing'oven, and a conveyor mechanism for mechanically returning said support and material being treated back to a point adjacent said loading position.

16. An equipment for heat treating consisting of a preheat housing, a heating housing constructed to contain molten material, and a quenching tank arranged adjacently to each other, a support for material being treated, means for maintaining the interior of said housings at different temperatures, an intermittently operated transfer mechanism arranged to periodically transfer said support and material to be treated successively froma loading position into said preheat housing, said heating chamber and finally into said quenching chamber, and a conveyor mechanism for mechanically returning said support and material being treated back to a point adjacent said loading position.

17. An equipment for heat treating consisting of a multiple of adjacently arranged housings, means for heating some housings, means for cooling other housings, a drawing oven, fluid circulating means for'heating said drawing oven and a mechanical system for intermittently and rapidly transferring the material to be treated from one housing to the next housing successively and into said draw oven and from said draw oven to a point adjacent the first housing.

WIILIAM A. DARRAH.

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