US3484085A

US3484085A - Drop bottom furnace and quench chamber

Info

Publication number: US3484085A
Application number: US626029A
Authority: US
Inventors: Joseph Montagino
Original assignee: Midland Ross Corp
Current assignee: Midland Ross Corp
Priority date: 1967-03-27
Filing date: 1967-03-27
Publication date: 1969-12-16
Anticipated expiration: 1986-12-16
Also published as: ES352015A1; DE1758058A1; BE712382A; FR1559354A

Description

Dec. 16, 1969 J. MONTAGINO 3,484,085

DROP BOTTOM FURNACE AND QUENCH CHAMBER Filed March 2'7. 1967 2' Sheets-Sheet 1 INVENTOR. Jos E PH Mcm'memo AT'TOTENEY Dec. 16, 1969 J. MONTAGINO 3,484,085

DROP BOTTOM FURNACE AND QUENCH CHAMBER Filed March 2'7, 196'? 2 Sheets-Sheet 2 L W m w E. INVENTOR.

JossPH MONTAGINa AT'TGRNEY United States Patent 3,484,085 DROP BOTTOM FURNACE AND QUENCH CHAMBER .Ioseph Montagino, Toledo, Ohio, assignor to Midland- Ross Corporation, Toledo, Ohio, a corporation of Ohio Filed Mar. 27, 1967, Ser. No. 626,029 Int. Cl. (321d 1/62; F27h 9/14 ILS. Ci. 266-4 5 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a furnace adapted to heat treat nonferrous metals at high temperatures and to quench the same without the need of quenching the work support members. The furnace is separated into two chambers, a first chamber for heating metal and a second chamber located below the first chamber for quenching. The metal is supported within the heating chamber by removable alloy members that are able to withstand temperatures in the range of 2000 F. Within the second chamber is a quench medium and an elevator that is provided to move between the two chambers. The elevator is operative to rise above the alloy members and engage work that is supported thereby. The alloy members are then removed and the elevator carries the work into the quench medium. In this way, none of the alloy parts of the heating chamber is subjected to a rapid drop in temperature.

BACKGROUND In the heat treatment of certain metals, it is necessary to heat treat these metals at relatively high temperatures, as, for example, in the solution heat treating of titanium alloys where the temperature requirements may be as high as 2000 F. This heat treating is usually carried out in a drop bottom furnace having a first chamber for heating the metal in a protective atmosphere and a second chamber, or pit, for quenching. As in the example of titanium alloys, after the metal is heat treated, it is normally quenched and then aged at an intermediate temperature such as 900 F. When the temperature requirements exceed 1200 F, the means for supporting the Work within the heat treating chamber has to be a material that is capable of providing structural support while withstanding the high temperatures to which the metals are subjected. Consequently, an alloy of high strength is usually employed and these work supports have been quenched along with the metals being treated. It is well known that high temperature, high strength alloys have poor thermal shock resistance, and because of the severe conditions under which these support members are placed, they are subject to frequent fracturing due to their brittle nature. With the need of frequent replacement of these work support alloys, the heat treatment of high temperature metals becomes quite expensive.

It is, therefore, an object of this invention to provide a furnace for the heat treatment of non-ferrous metals at high temperatures.

It is another object of this invention to provide a furnace for the heat treatment of metals wherein the means for supporting the Work during the heat treatment thereof is not subjected to quenching.

It is still another object of this invention to provide a novel drop bottom furnace.

Other and further objects of the invention will be apparent from the following description of the preferred embodiment thereof, reference being made to the accom panying drawing.

SUMMARY OF THE INVENTION In order to overcome the shortcomings of prior furnaces used to heat treat metals at relatively high temperatures, a novel furnace is provided wherein the work support means need not be quenched during the heat treating cycle. The furnace comprises a housing defining a first chamber having a retractable door at the bottom thereof. The first chamber is a heat treating chamber wherein the work may be raised to a temperature in the range of 2000 F. A pit, or second chamber, is disposed below the first chamber and contains a quench medium therein. An elevator is provided that comprises a plurality of plates, which elevator may be moved vertically between the heat treating chamber and the pit. The work supports include a plurality of retractable, heavy alloy beams that extend parallel to the elevator plates and through which the elevator plates may extend to eventually engage the work when the elevator is in its uppermost position. After the work is heat treated, the door separating the two chambers is removed and the elevator is raised into the heat treating chamber so that the elevator plates extend between the support means to engage the work. After the elevator engages the work, the work supports are retracted and the elevator is dropped so that the work is submerged within the quench medium. With completion of the quenching, the elevator is then raised and the work returned to the heat chamber, the work supports are inserted once more into the housing, and the elevator is removed so that the work may be aged by being heated to an intermediate temperature.

DESCRIPTION OF THE DRAWING In the drawing:

FIG. 1 is a vertical section through a heat treating furnace constructed in accordance with this invention.

FIG. 2 is a view of the furnace taken along the lines 22 of FIG. 1.

DETAILED DESCRIPTION Referring now to the drawing, a heat treating furnace embodying the principles of this invention is shown generally at It The furnace 10 comprises a housing 12 that defines a heat treating chamber 14. The housing 12 is supported above the ground by a plurality of legs 15 over a pit 16 defining a quenching chamber 18. Attached near the bottom of the housing 12 is a pair of horizontally spaced sleeves 20 that receive retractable work supports 22 on each side of the housing 12 immediately above an opening 23 of the housing. Each work support 22 is disposed within a sleeve 20 and is supported by a plurality of bearing members 24 that are received within grooves 26 on the underside of the work supports. Attached to the outer end of each work support 22 is a rod 28 that extends through the sleeve 20 into the atmosphere where it is engaged by a rolling member 30 that is slidably disposed within a track 32 supported by a frame member 34. Secured within the sleeves 20 immediately above the work supports are adjustable guide members 36 that keep the work supports 22 level by taking the upward thrust when the work supports have a load thereon.

Aligning the interior side walls of the housing 12 are a plurality of heating elements 38 capable of raising the temperature of the first chamber from 900 F. to 2000 F., depending upon the heat treat requirements. These heating elements 38 may be either electric resistance heaters or gas fired radiant tubes. A shroud 39 is provided within the chamber 14 immediately adjacent the heating elements 33. Means is provided to supply a protective atmosphere, such as argon, to the chamber 14 (such means not being shown), and a fan 40 is provided to circulate the atmosphere within the chamber.

Immediately below the heat treating chamber 14 is a loading zone 42 wherein the work 44 is introduced into and discharged from the furnace 10. During the heat treating phase, the atmosphere within the chamber 14 is retained by a door 46 that seals off the chamber from the air. The door 46 is made of refractory brick 48 that has a shoulder 50 on the sides thereof and is supported by a metal brace 52. A pair of spaced horizontal frame members 54 is disposed below the opening 23 of the housing 12 and receives therein a metal carriage member 56 having wheels 58 connected to a carriage member by bearings 60 for sliding movement Within the frame members 54. A plurality of linkage members 62 provides a connection between the brace 52 and the carriages 56, each end of the linkage members being rotatably connected to a

bearing

63 and 64 secured to either a brace 52 or a carriage 56, respectively, thereby providing pivotal movement of the linkage members relative thereto. The frame members 54 have an upwardly curved portion 6-6 at one end thereof and at the same end the brace 52 has connected thereto a horizontally disposed guide member 68 with a wheel 70 that is received within the curved portion 66 of the frame member 54. Attached to the bottom portion of the housing 12 and disposed about the opening 23 is a seal lip 71 that is received within an annular vessel 72 having a soft resilient material 73 therein to provide a seal for the chamber 14 when the door 46 is positioned within the opening 23. Through the construction just recited, the door may be moved in and out of the opening 23 of the housing 12 by moving the carriage 56 horizontally. When the door 46 is positioned within the opening 23 to seal the chamber 14 and it is to be removed, the carriage member 56 is moved within the frame member 54 to the left as viewed in FIG. 1 and the guide member 68 is directed downwardly by the curved portion 66. The linkage members 62 will pivot ab ut their

respective bearings

63 and 64 so that the carriage 56 moves to the left and the door 46 moves vertically downwardly. After the door 46 is removed from the Opening 23 and the guide member 68 has reached the bottom of the curved portion 66, the brace 52 will rest on the carriage 56 and the two are moved to the left, thus removing the door 46 from the furnace working area.

As was stated previously, the housing 12 is supported by a plurality of legs so that it is positioned a distance above the ground. Immediately below the housing 12 is the loading zone 42 wherein the work 44 may be loaded into the chamber 14 or discharged from the furnace 10 after the heat treating cycle is completed.

Located below the loading zone 42 is a pit 16 that defines a quench chamber 18 within which a quench medium 76 is disposed. An elevator 78 is provided to move vertically between the heat treating chamber 14 and the pit 16 and has a plurality of horizontally extending plates 80 resting upon a pair of beams 82, which beams are in turn secured to a platform 84 by a series of columns 86. The length of the platform 84 is greater than the width of the heat treating chamber 14 so that the ends 85 of the platform extend laterally beyond the housing 12. Attached to each corner of the platform is a bearing rod 88 that is connected to a drive mechanism 98 by a chain 92. The plates 80 have greater height than the work supports 22 and the columns 86 are high enough to allow the plates to extend sufiiciently into the heat treat chamber to engage any work 44 that is resting on the work supports when the elevator is in its uppermost position.

In operation, the elevator 78 is initially positioned within the loading zone 42 and work 44 is placed upon the plates 80. The work 44 may be contained within a tray having an open grid bottom, which tray may be made of an alloy of low strength that is able to withstand the high temperatures of the heat treating chambers 14 and the subsequent quenching. Material with these physical properties may be used since the tray would not be subjected to a heavy load. When the work 44 is positioned within the loading zone 42, the work supports 22 are within their respective sleeves 20 and the door 46 is also removed from the furnace working area. The elevator 7'8 is raised so that the work 44 is positioned within the heat treating chamber 14. After the elevator 78 reaches its uppermost position, the work supports 22 are then inserted into the heat treat chamber 14, interspersing the elevator plates 81). At this time, the opposed work supports 22 are not inserted in an abutting relationship; instead, a space is provided between opposing members to allow room for thermal expansion. Once the work sup ports 22 are in position, the elevator 78 is withdrawn and the work will rest upon the supports. The door 46 is then inserted into the furnace opening 23 and the lip 71 sinks into the resilient member 73 to seal the heat treat chamber 14 from ambient. The chamber 14 may then be given a protective atmosphere, such as argon, and the heating elements 38 heat the atmosphere to the desired temperature, usually in the range of 2000 F., for the solution heat treating of titanium alloy. As the heating elements increase the temperature of the atmosphere, the fan 4-0 is used to circulate this atmosphere in a manner indicated by the arrows to provide more uniform heat distribution throughout. The titanium alloy is heated at these temperatures until the work 44 is in solution throughout its entire volume. When the solution heat treat is complete, the heating elements 38 and fan 40 are turned off so that heat is no longer provided to the chamber 14. After the heat is discontinued, the door 46 is removed from its position in between the heating chamber 14 and the loading zone 42 and the elevator is raised so that the plates engage the tray 84 supporting the work. The hot alloy supports 22 are then moved horizontally away from the furnace center and back far enough to clear the perimeter of the work 44. After this is accomplished, the cold elevator is lowered with the hot work 44 on it and submerged into the quench medium 76, this quench medium usually being water. As soon as the load clears the bottom of the housing 12, the door returns and seals the heat treating chamber 14 once more. After the quenching is complete, the process is reversed and the titanium returned to the furnace chamber 14 where it is then aged at a temperature of 900 F. for several hours.

Thus, a furnace is provided wherein the alloy parts that are necessary for support within the heating chamber 14 are not exposed to sudden reductions in temperature that would tend to damage these parts. More particularly, the expensive alloy work supports 22 are not quenched and thus are not subject to being shattered after a few heat treating cycles. In fact, there is virtually a complete separation between those parts that are involved in the quench. The only part of the system that would be conveyed to all chambers is a tray that might be used to support the work 44. Such a tray can be made inexpensively from alloy materials having good thermal shock characteristics since high strength is not required. Any trays used in the furnace will tend to warp with frequent use, but they can be straightened easily. The tray would also serve the function of preventing the cold elevator plates 80 from engaging the hot work immediately after the solution heat treat and cause a non-uniform pattern within the work 44.

In the preferred embodiment just described, the work was placed directly upon a plurality of plates 80 of an elevator 78 to be conveyed between the heating chamber 14 and the quenching medium 18. It has been a practice in the heat treating industry to use a car for conveniently loading the work 44 into the furnace 10. The preferred embodiment may be modified by replacing the columns 86 with a pair of rails upon the elevator platform 84 to receive the wheels of a loading car. Through use of such a car, the work may be loaded external to the furnace 10. but when the car is rolled up on said rails, it becomes a part of the elevator 78.

After the work is solution heat treated and quenched, it need not be reloaded immediately in the heat treating chamber 14, but may be stored prior to the final aging operation. In this way, an economical method of production may be achieved, for the heat treating chamber 14 of the furnace may be maintained at the heat treating temperature to accommodate a plurality of loads without the need of frequent temperature cycling. Thus, when a large number of parts are to be heat treated, quenched and aged, they all may be heat treated, quenched and stored, then the furnace temperature may be lowered for the aging process.

Although only the preferred embodiments of this invention have been shown and described, it is understood that changes and modifications can be made therein and this description is illustrative only and not for the purpose of rendering this invention limited to the details illustrated or described except insofar as they have been limited by the terms of the following claims.

I claim:

1. A furnace for the heat treating of metals comprising: wall means defining a first chamber and a second chamber disposed below said first chamber, means for heating said first chamber, first support means disposed in said first chamber, said first support means comprising a plurality of horizontally extending members, a quench medium disposed within said second chamber, second support means comprising at least one member disposed within said wall means, elevator means for vertically moving said second support means between said first and second chambers, said second support means having a height greater than said first support means and assuming a position above said first support means when said elevator means is in its uppermost position, and means for removing said first support means.

2. The furnace of claim 1 wherein said heating means is operative to heat said first chamber to at least 2000" F. and said first support means is made from a high temperature alloy.

3. In a furnace for the heat treating of metallic work, the combination comprising: wall means defining a heat treat chamber having an opening at the bottom thereof, a door adapted to be received within said opening to seal the same, means for moving said door to and from said opening, a plurality of horizontally extending work support members disposed within said wall means immediately above said opening, means for moving said members into and out of said chamber, heating elements disposed within said chamber, wall means located below said heat treat chamber defining a quench chamber having an opening at the top thereof, quenching fluid disposed within said quench chamber, an elevator comprising a plurality of horizontal spaced plates, means for conveying said elevator between said heat treat chamber and said quenching chamber, said plates having a height greater than and being interspaced with said support members.

4. The furnace of claim 3 wherein said work support members are formed from a high temperature alloy having high structural strength.

5. The furnace of claim 4 wherein said heating elements are operative to heat said heat treating chamber to a temperature of 2000 F.

References Cited UNITED STATES PATENTS 1,969,708 8/1934 Betke.

2,639,047 5/1953 Ipsen 2664 X 2,752,147 6/1956 Besselman et al. 266-4 2,856,177 10/1958 Lee 266-4 3,219,330 11/1965 Ackcr 266-4 P. SPENCER OVERHOLSTER, Primary Examiner J. S. BROWN, Assistant Examiner