US1697144A - Heat treatment apparatus - Google Patents

Description

"J. SCHONBRUNN ET AL HEAT TREATMENT APPARATUS Filed Sept. 8, 1927 2 Sheets-Sheet 1 72167076 '@bzz%e5 ladle,

a 661 mm Jan. 1, 1929.

J. SCHONBRUNN ET AL HEAT TREATMENT APPARATUS Filed Sept. 8, 1927 2 Sheets-Sheet 2 Patented Jan. 1', 1929 UNITED STATES JAKOB SGHONBBUNN, or AABAU, AND Go'r'rLIEB KELLER, or BRUGG, SWITZERLAND,

nssrenons T0 AKTIENGESELLSCHAFT BROWN novnnr & era, 01* BADEN, swI'rzEE- LAND, A JOINT-STOCK COMPANY or SWITZERLAND.

7 HEAT TREATMENT APPA ATUS.

Application filed September 8, 1927, Serial 2N0.

This invention relates to heat treatment apparatus, particularly furnaces such as may be employed for annealing or other heat treatments of various materials.

The general object is the provision of a furnace apparatus which is adapted to increase production byvirtue of provision of means for expediting the cooling of a charge while itis still within the furnace and protected from undesirable efiects of atmosphere, dust, contam'inatiorQ, or the like.

Another object is the provision of an apparatus which is adapted to expedite and regulate cooling of a charge in the furnace without involving excessive loss of heat in subsequent heating of a succeeding charge.

A further object is the provision of apparatus having the characteristics specified which may be easily and rapidly operated to accommodate charging and discharging and WhlCll expedites coohng and heating of charges. 1

Other and further objects will be pointed out or indicated hereinafter, or Will appear to one skilled in the-art upon an understanding of the invention or its employment in practice.

In the drawing forming a part of this specification we illustrate three structural embodiments of the invention but it is to be understood that these are presented for purpose of illustration only and are not to be accorded any interpretation calculated to limit the claims short of the true and most comprehensive scope ofthe invention in the art.

In said drawings, u

Fig. 1 is a sectional elevation, shown diagrammatically, of one form of apparatus cover is provided with an elevating mechaembodying the invention, the furnace being in the closed condition, as fpr heating of a charge;

Fig. 2 is a similar diagrammatic sectional elevation representing the furnace in con dition for cooling of a charge therein;

Fig. 3 is a similar sectional elevation of a,

second embodiment of the invention, the furnace being shown in the condition when closed for heating of a charge; and' Fig. 4 is a sectional elevation of a third embodiment of the invention with the furnace closed for the heating of a charge.

Certain heattreatment processes require that the cooling down of the charge should 218,158, and in Germany September 10; .1926.

take place within the furnace itself. For example, if certain metallic articles are required to be bright (unoxidized) after the heat treatment, care must be taken to exclude all air from them durin the heating and cooling periods. To keep own the heat loss during the heating period, the furnace walls must be made of material having a low heat conducting capacity, and while ex edit- 1ng heating of a charge, this has the e ect of rendering the cooling period disproportionately long, far longerthan is necessary for the requisite cooling down of the charge The productive ca acityof such' a heat losses will be great, and the economy under such conditions will be low.

- According to the present invention, the furnace may be well insulated, and the heating costs kept within an economical range, while at the same time rapid cooling of the charge. may be elfected, with complete exclusion ,of air during heating and cooling.

The nature of the invention will be ascentained from the examples illustrated in the accompanying drawings. Figs. 1 and 2 represent one construction of apparatus in which the furnace is of pit form having the walls and'bottom 10 with heat insulating lining 10, and the removablev cover 11 with linin 11. Of course, the walls and cover may made throughout of material having the necessary heat insulating qualities. The

nism including the sheaves 12 over which run suspension members 14 i which carry the cover, the weight of the latter being almost completely counterbalanced'by the weights 15, so that it may be raised with the appllcation of but little power.v The sheaves may be actuated in slillitable fashion to raise the cover to the c argiug position, Suitable heating means, such'as the electricalheating elements 16, are provided for heating the furnace chamber mteriorly, and the furnace may be rendered gas tight by enclosing its walls and bottom with a metal shell 17. A pipe 18 is provided throughwhich an'inert 'gas may be supplied to the furnace under 7 rounded by a chamber 22 formed by enclosing the furnace within a tank 24, said chamber being adapted to hold liquid, such as water, which may be introduced through a pipe 25, to fill the chamber to the overflow 26. A

suitable valve control 27 is arranged to per mit discharge of the liquid from the chamber 22. The movable cover carries a bell 28 which has relatively thin walls made of material having good heat conductivity and adapted to move in telescopic relationship with the walls of the furnace, completely encompassing the same, said bell adapted to travel in'the chamber 22, and carrying at its lower end a float 29, arranged to permit the lower margin of the bell 28 to dip below the surface of the liquid in the chamber 22 to an extent sufficient to fornran effective air seal. The float has suflicient buoyancy to support the difference in weight between the cover and bell on the one hand and the counterweights 15 on the other hand, so that the cover and bell may be elevated by liquid introduced into the sealing chamber 22. I

In operation, the cover, together with the bell, is elevated to a suflicient extent to permit the charge to be introduced into the furnace chamber and the cover is lowered to the position illustrated in Fig. 1, the sealing chamber 22 being nearly empty of liquid to permit this, The furnace chamber is filled with the inert gaging-ress of air being prevented by the seal afforded by the liquid in which the lower end of the bell is submerged. The heat is then applied and the charge brought to the requisite temperature. Then,

. for the cooling down of the charge, liquid is introduced through the pipe 25 into the sealing chamber 22, resulting in't he elevation ofthe cover and the bell to a position such as illustrated in Fig. 2, wherein the gas enclosed within the furnace chamber and the bell, which nowforms substantially an extension of the furnace chamber, is exposed to the cooling effect of the bell, the walls of which are relatively thin and of good heat conducting material and are cooled exteriorly. Thus the charge may be cooled much more rapidly than would be possible by the normal progress of radiation through the poorly conducting walls of the furnace. At the same time, ingress of air is prevented, so that the charge may be cooled to the proper degree without exposure to oxidation or dust or other contamlnating influences outside the furnace.

When the charge is sufficiently cooled, the confined inert gas may be withdrawn through pipe-20, and the cover and bell then elevated to the position permitting discharge and recharging of the furnace. I When again closed, the furnace and the new charge may be heated quickly to the desired temperature without undue loss of heat through the furnace walls. Thus, it will be observed, the output of the furnace may be greatly increased due to the shortening of the heating and cooling down periods.

In the embodiment illustrated in Fig. 3, the movable cover 11 is adapted to close the sealing chamber 22 as well as the furnace chamber, thus contributing to the heat insu-' lation of the furnace during the heating period, the encompassing walls 24' in this lnstance being made also of material of low heat condiictivity. The other parts shown in this embodiment are as described in reference to the form shown in Figs. 1 and 2, and operate in similar fashion. By the provisions ilustrated in this embodiment, the furnace chamber walls may be less massive than nor- 0 Inally required, and the time necessary for coolingthereby still further reduced. The cooling may be expedited by using the sealing liquid also as a cooling medium, by passing it continuously into and out of the sealing chamber during the cooling period.

A third embodiment is illustrated in Fig. 1 4, wherein the furnace chamber walls are comparatively thin, to facilitate the escape of heat during the cooling period, the insulating effect during the heating period being contributed by the downward extensions 11 of the cover, which extensions encompass the furnace chamber walls when the cover is in the closed position. The bell28 is formed as an extension from the lower end ofthis cover skirt and has thin walls of good heat the lowered position. The accessories forv the embodiments illustrated in Figs. 3 and 4 may be the same as in Figs. 1 and 2, and the operation is substantially the same.

What We claim is: v

1. Heat treatment apparatus comprising the combination of a furnace chamber, means for heating the same interiorly, a movable closure for the chamber, and a heat-conductive extension carried by the closure and movable therewith to maintain the chamber closed to atmosphere when othe cover is removed therefrom.

2. Heat treatment apparatus comprising the combination. of a heat-insulated furnace chamber, means for heating the same interiorly, a heat-insulating movable closure for the chamber, and aheat-conducting closure I portion movable into exposure to the atmospheres inside and outside the furnace chamchamber and to support the former in a se- 65 ber to' f a cilitate transfer of heat between them.

3. Heat treatment apparatus comprising the combination of a heat-insulated furnace chamber, and a closure for same comprising a heat-insulating portion and a heat conducting portion, said closure being movable to a position wherein the chamber is closed by the heat-insulating portion and to another position wherein the confined atmosphere is exposed to the heat-conducting portion.

4. In heat treatment apparatus, the combination of a heat-insulated furnace chamber, means for heating the chamber interiorly,

a movable cldsure for the chamber, a heatconducting shell movable with said closure in telescopic relationship with the chamber, and means for providing a seal between the shell and chamber for prevention of ingress of external atmosphereinto the latter.

5. In heat treatment apparatus, the combination of a heat-insulated chamber, a heat insulated closure therefor, an extension member in telescopic relationship to the chamber and movable with the closure, said extension member being of heat-transmittin material, and means for maintaining a sea between the extension member and the chamber incident to its movement, to prevent ingress of air into the chamber.

--extension of the chamber, and means coop- 6.'In heat treatment apparatus, the combination of a heat-insulated chamber, means for heating the same interiorly, a movable closure for the chamber, a heat-transmitting member movable with the closure to form an erativewith the heat-transmitting member to prevent ingress of air into the chamber.

7. In heat treatment apparatus, the combination of a heat-insulated chamber, means for heating the same interiorly, a heat-transmitting member adapted to form an extension of the chamber, a movable closure for cooperation with the chamber and heat-transmit ting member, and means for moving the closure to expose the heat-transmitting. member to the internal atmosphere of the chamber.

8. In heat treatment apparatus, the combination of a heat-insulated chamber, a heattransmitting bell adapted to form an extension of the furnace chamber, a closure for closing both the chamber and bell to prevent ingress of air into the chamber, and means for supporting the heat-transmitting member at a selected position with respect tov the chamber.

10. Heat treatment apparatus as specified in claim 8,'wherein'a liquid is employed to form a seal between the bell and the furnace lerted osition with respect to the latter.

11. eat treatment apparatus as specified in claim 8, wherein a liquid is utilized to form a seal between the bell and the furnace I chamber, the bell being buoyantly supported by the liquid and the height of the latter determining the position of the bell.

. 12. Heat treatment apparatus as specified in claim 6, together with means for introducing an inert atmosphere into the chamber.

13.- Heat treatment apparatus as specified in claim8, together with means for introducing an inert gas into the chamber.

14. Heat treatment apparatus as specified in claim/'8, wherein theclosure and bell are movable vertically, together with means for counterbalancing the weight .of the closure and bell, and .a float for supporting them bouyantly on the sealing liquid.

15. In heat treatment apparatus, a heatinsulated chamber, a tank enclosing said chamber in spaced relation thereto, a heatinsulated closure member for said chamber, and a heat-transmitting member secured to said closure member to provide for" varying the capacity of said chamber to permit regulation of the rate of cooling thereof.

16. In apparatus of the character described,

means providing a heating chamber, and

rneans'inovable to difierent positions and operable when in one of said positions to provide a fluid seal for said chamber and operable when in another position to provide a cooling chamber for said heating chamber while maintaining such seal.

17. In .heat treatment apparatus, a chamber, .a tank disposed about and spaced from said chamber, a closure member provided with an extension disposed intermediate said chamber and said tank, and means cooperating with said extension td provide therewith a fluid-seal for said chamber.

' 18. Inapparatus of the char "cter described, means providing a heating ch mber, a closure member for said chamber, and means forming part of said closure member and operable when the latter is in position partially removed from said chamber to rovide a fluidcooling chamber for said heating chamber.

19. In heat treatment apparatus, an insulated closure member for said chamber, and i a heat-conducting portion depending from said closure member into the liquid in such wise .as to provide a fluid trap for said chamber, and means operable to provide a support for said closure member and said heat-conducting portion and including .float means forming part of said heat-conductmg portion and being responsive to level conditions of said liquid.

20. In heat treatment apparatus, an insulated chamber, a tank enclosing and spaced from said chamber, the space between said chamber and said tank being adapted to con- 5 tain a liquid, an insulated closure member for said chamber, and a heat-conducting portion depending from said closure member into the liquid, said heat-conducting portlon having an annular air chamber formed In the lower portion thereof to buoyantly sup- 1' port said heat-conducting portion.

In testimony whereof We have hereunto subscribed our names this 23 day of August A. D. '1927, at Zurich, Switzerland.

JAKOB SCHONBRUNN. GOTTLIEB KELLER.

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