US2816751A - Controlled atmosphere furnace muffle - Google Patents

Description

Dec. 17, 1957 e. F. TISINAI ETAL CONTROLLED ATMOSPHERE FURNACE MUFFLE 2 Sheets-Sheet 1 Filed Dec. 29, 1955 ebs I Ma.

ATTORNEY 2 Sheets-Sheet 2 INVENTORS: Geaage 7 'isinai Ham 0' A. B/rkness John R. Krebs Dec. 17, 1957 e. F. TISINAI ETAL CONTROLLED ATMOSPHERE FURNACE MUFFLE Filed Dec. 29, 1955 A TTO/iWEY United States Patent CONTROLLED ATMOSPHERE FURNACE MUFFLE George F. Tisinai, Highland, lnd., Harald A. Birkness, Homewood, Ill., and John R. Krebs, Indianapolis, Ind, assignors to StandardOil Company, Chicago, IlL, a corporation of Indiana Application December 29, 1955, Serial No. 556,135

6 Claims. (Cl. 266-4) This invention relates to heat treating apparatus and, more particularly, to metal treating furnaces. It is concerned with improved means for the transfer of work pieces to and from a mufile while maintaining the work in a protective or processing atmosphere.

It is desirable to conduct certain heat treatments at temperatures in excess of 2000 F. and in an atmosphere other than air. However, apparatus heretofore available has been unsatisfactory for one or more of several reasons. Many such furnaces are not continuous in operation, do not provide for the treatment of several work pieces for varying lengths of time, do not include quenching means which can be utilized without removing the specimen from the protective atmosphere, and have not provided for remote handling of the specimens.

It is, therefore, a primary object of our invention to provide a muffie which permits quenching without removal from the protective atmosphere and with choices of two or more quenching media. A further object is to provide a muffle adapted for continuous transfer of specimens by means of remote handling tongs and retractable radiation shields. Still another object is to provide a furnace mufile adapted for controlled atmosphere heat treatments of several specimens for varying lengths of time. Another object is to provide an apparatus which permits maintaining uniform temperature in the heated section and is of simple construction to avoid thermal lags. These and other objects of the invention will become apparent as the description thereof proceeds.

Briefly, our invention comprises a storage chamber and a mufiie which are both maintained under a controlled atmosphere. A plurality of quench tanks are arranged below the storage and transfer chamber with access to the quench tanks both from within and without the storage chamber. The liquid in the quench tanks serves as a quenching medium and as a seal for the furnace. Thus, samples can be removed from the quenching tanks without interrupting the operation of the muflle. A plurality of bafiles extend across the inlet to the muffle, the bafiles being controllable from the exterior of the apparatus. A pair of handling tongs permit the manipulation of the work pieces within the storage chamber and the mutlie. Further design features and advantages of our apparatus will be described in connection with a preferred embodiment of the invention illustrated in the accompanying drawings wherein:

Figurel is an isometric view of the assembly;

Figure 2 is a top view of the apparatus shown in Figure 1; and

Figure 3 is an enlarged detail of one handling tong assembly.

Referring to Figure 1, we provide a storage chamber having a front panel 11 and a roof or top panel 12. The front panel 11 is provided with a windowed door 13 and the roof 12 with a window 14. An end of the hearth chamber 15 is integral with the storage chamberltland extends through a furnace wall 16 as schematically shown in Figure 2. Within the mufllechamber 15 are a pair 2,816,751 Patented Dec. 17, 1957' of hinged baffles 17 and 18 linked by rod 19. The bafile 17 is hinged to the end of the baflle rod 20 which extends through the panel 11.

When the baffle control rod 20 extending through the front panel 11 is pulled out both baffles 17 and 18 swing outwardly. With such an arrangement, it is preferred that the hinges 43 and 44 be fixed horizontally below the roof 12 of the mufile chamber 15.

A thermocouple well 21 has access from the front panel 11 and extends the length of the storage chamber 10 and muflle chamber 15. A water jacket 22 having inlet 23 and outlet '24 encircles a portion of the hearth chamber 15 adjacent the storage chamber 10. The blanketing gas is introduced by inlet duct 25 and is discharged at the remote end 15a of the muffle chamber 15. The effiuent blanketing gas from the apparatus is vented by means of nipples 26 spaced from each other in roof 12. Con duits (not shown) are connected to the nipples 26and manifolded for flow through a liquid bubble trap (not shown) and vented into a hood.

The specimens to be treated are initially introduced into the storage chamber 10 by way of door 13 as described and then into hearth chamber 15. This may be done in two steps or stages. First the tongs 27 may be used to move the specimen from the storage chamber 10 to a point in front of the baffle 17. Window 14 in the top panel 12 and a light projected through port 28 facilitate the manipulation of the samples.

A second pair of tongs 29 can then be used to transfer the work pieces from the storage chamber 10 into the muffle chamber 15. This is accomplished by first retracting baffle rod 20 to open the baffies 17 and 18, after which the tongs 29 are used to carry the work piece into the mufiie chamber 15. During this operation, the water jacket 22 assists in preventing excess heat transfer into the storage chamber 1t and quench tanks 30 through floor ports 31.

It will be noted that each of tongs 27 and 29 are provided with flexible bellows 32 and 33 adjacent the front panel 11. This permits considerable freedom of movement with the specimen tongs and enables the operator to readily manipulate the specimens within the storage space, to and from the hot zone of the muffle chamber 15 and into the quench tanks 30 and 3011. If desired the shorter tongs 27 can be mounted in side wall 34 of the storage chamber 10.

Tong support plate 35, removably fixed to the front panel 11 is provided with a window 36 which further facilitates the observation and manipulation of the work pieces. When it is desired to withdraw a treated sample, the procedure is reversed and the treated specimen is carried rearwardly to a point adjacent the quench ports 31 and 31a. Tongs 27 or 29 may be used to drop a heattreated sample into the selected quench tank 30 or 30a. The depending fixed ballles 3'7 and 38 provide, with the quenching media, a liquid seal between the storage chamber 14 and the ambient atmosphere.

Referring to Figure 3, the tongs 29 (and 27) comprise a pair of handles 40 with a rod-in-tube assembly 41 connected to the corresponding jaw 42 and 42a.

In operation the muffle chamber 15 is projected through a furnace wall 16. The furnace is started and as heating progresses, the quench tanks 30 and 3th: are filled, the specimens are introduced through door 13 and the cooling water flow rate through the jacket 22 is adjusted. The apparatus is purged with the gas desired for a protective atmosphere and when the desired temperature, as indicated by a thermocouple located in the thermocouple well 21', has been reached the specimens are placed within the hot zone of the muffle chamber 15 for the required time and treatment. During the treatment, the baffles 17 and 18 are arranged in their closed position. A refractory 3 panel can be provided on the battle faces toward the hearth chamber 15.

The space within the storage chamber allows the operator to place a considerable number of samples within the apparatus and then a few at a time can be introduced into mufile chamber without cooling the apparatus each time a new batch of samples is to be placed in the hot zone. Also, the space within the storage chamber 10 provides ample room for cooling in the protective atmos phere.

When the treatment is completed, the baflles 17 and 1B are opened long enough to retrieve the samples with the tongs 29 and then closed. The specimen may then undergo normal cooling within the protective atmosphere within storage chamber 10 or be dropped into one of quench tanks 30 or 30a and removed therefrom through access ports 46 and 46a by any suitable tongs (not shown).

Although we have described our invention with respect to a preferred embodiment thereofillustrated in the drawings, it should be understood that this is by way of example only and that our invention is not necessarily limited thereto. Further, it is contemplated that modifications can be made in the apparatus and in the mode of operation of the apparatus in view of our disclosure and that such modifications can be made without departing from the spirit and scope of the invention.

What we claim is:

1. An improved furnace muffle including an elongated hearth chamber closed at one end and open at the other, said chamber comprising the treating zone of the mufile, storage chamber means having a port therein merging with the open end of said hearth chamber, water jacket means encircling the hearth chamber adjacent said port, dual quench tank means disposed subjacent to said storage chamber means and projecting laterally of a side wall of said storage chamber, access port means in the floor of said storage means into said subjacent quench tank means, a pair of removable panel means on a front wall of said storage chamber means, one of said panel means including a window and being adapted to be removed to introduce the specimens to be stored before being heat treated, the second of said panel means comprising a second window and supporting a flexible bellows through which a tong means extends into said storage chamber and into said hearth chamber, and conduit inlet and outlet means for flowing controlled atmospheres longitudinally of said hearth chamber to be introduced into said hearth chamber adjacent the closed end thereof and to be vented from said storage chamber.

2. A controlled atmosphere muflle which comprises in combination a specimen storage chamber, a hearth chamber closed at its remote end, conduit means between said hearth chamber and said storage chamber, cooling jacket means on said hearth chamber adjacent said storage chamber, tandem radiant heat bafiles interposed said hearth chamber and said cooling jacket, rod means extending exterior of said storage chamber adapted to manipulate said baflies, quench tank means disposed below said storage chamber, first quench tank access port means in the floor of said storage chamber, tong means slidably extending through a wall of said storage chamber and adapted to be manipulated within said hearth chamber, second access port means for said quench tank means exterior of said muffie, said quench tank means including a liquid seal means comprising 21 depending extension of a side wall of said storage chamber, conduit means for flowing a controlled atmosphere into and through said muflle from the closed end of said hearth chamber into said storage chamber, and vent means in said muflle by which said controlled atmosphere may be discharged.

3. A furnace muflle comprising unitary treating chamber means and storage chamber means, said treating chamber means being elongated and adapted to be supported within a furnace, radiant heat bafile means disposed across said treating chamber adjacent said storage chamber, said bafiie means comprising a pair of spaced hinged and articulated doors, baffle control means extending through said storage chamber for manipulating said radiant heat baffle means, quench tank means arranged below a portion of said storage chamber, quench tank port means in the floor of said storage chamber above said tank means, inlet duct means supplying gasiform fluids directly to said treating chamber, outlet means for venting said gasiform fluid from said storage chamber, said inlet duct and outlet conduit means providing circulation of gasiform fluid into and from the mufile, and tong means slidably supported by a wall of said storage chamber and extendable from said storage chamber into said treating chamber.

4. Furnace muflle means including in combination an elongated treating chamber adapted to be supported within a furnace, a storage chamber in communication with said treating chamber and having a portion thereof in alignment therewith, radiant heat bafile means disposed within said treating chamber adjacent said storage chamber, said baflle means including a pair of hinged door members disposed across said treating chamber, a link rod between said doors, and a bafile rod hinged to one of said doors and extending through said storage chamber for manipulating said doors in unison, water jacket means surrounding said treating chamber means between said baffles and said storage chamber, quench tank means disposed below a portion of said storage chamber in alignment with said treating chamber, quench tank port means in the floor of said storage chamber above said quench tank means, access port means to said quench tank means exterior of said storage chamber, windows in said storage chamber, gas inlet and outlet means for circulating a controlled atmosphere through said muflle from a remote portion of said treating chamber into said storage chamber, and tong means supported by a wall of said storage chamber and extendable therethorugh beyond said baffles and into said treating chamber.

5. In a heat treating apparatus comprising a storage chamber adapted to confine a protective atmosphere, an elongated treating chamber extending rearwardly from the rear wall of said storage chamber, and a quench tank means below the storage chamber the improvement which comprises first access port means for said quench tank means in the floor of said storage chamber, second access port means to said quench tank means exterior of said storage chamber and arranged laterally of said first access port means, a bay in said storage chamber disposed laterally of said first access port means and in open communication with said storage chamber, fixed batfle means depending from said storage chamber adjacent said first access port means and extending to a point adjacent but spaced from the bottom of said quench tank means, said fixed baffle together with quench liquid in said quench tank forming a liquid seal between the storage chamber and the ambient atmosphere, a pair of hinged radiant heat bafiles arranged in tandem across the cross-sectional area of said elongated treating chamber, link means for manipulating said tandem radiant heat baflles in unison, conduit means for introducing the protective atmosphere into the remote rear portion of said treating chamber, outlet conduit means in said storage and auxiliary storage chambers for flowing protective atmosphere from the apparatus, and cooling jacket means about said treating chamber intermediate said tandem baffles and said storage chamber.

6. The apparatus of claim 2 which includes a second tong means extendable through a wall of said storage chamber for manipulation of specimens therewithin, and window means in the top wall of said storage chamber to permit viewing such manipulation of specimens in the storage chamber.

(References on following page) 5 6 References Cited in the file of this patent FOREIGN PATENTS UNITED STATES PATENTS 514,106 Great Bl itain Oct. 31, 1939 Brierer Aug. 24,1897 OTHER REFERENCES Allenson Apr. 19, 1910 Gier y 21, 1942 5 on'fhe Iron Age, September 23, 1954 (page 116 rehed Norton Apr. 17, 1945 Holcroft Feb. 16, 1954 'Ipsen May 29, 1956

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