US1914403A - Heat treating container - Google Patents

Description

Patented June 20, 1933 NITED STATES PATENT OFFICE FRANK '1. COPE, OF SALEM, OHIO, ASSIGNOR TO THE ELECTRIC FURNACE COMPANY, OF

SALEM, OHIO, A CORPORATION OF OHIO HEAT TREATING- CONTAINER Application filed March 19, 1930. Serial No. 437,058.

The invention relates to containers adapted to accommodate metal objects during heat treatment, and more particularly to a container designed for use when it is desired to heat the objects in contact with a suitable The use of gases in various kinds of heat treatment of metals is well known and the purpose of the gas may be to prevent oxidation, as in annealing, in which case a neutral or reducing gas may be used; or to cause absorption of a hardening agent by the surface of the objects under treatment, as in carburizing, wherein a gas containing the said hardening agent in available form may be used.

In carrying out heat treatments of this nature it is usually undesirable, and frequent ly very detrimental to the material under treatment, to permit access of air, or other gases such as may be encountered in a furnace, to. the interior of the container.

It is, however, necessary to provide means for opening the container in order to charge and empty the same, and some form of seal for said opening is therefore necessary.

If such seal is not substantially gas tight it will result in the consumption of an excessive quantity of gas; danger of explosion when a combustible gas is employed; or discomfort or injury to persons working around the furnace when a noxious or poisonous gas is used in the heat treatment.

It is common practice tomsegaskets and packings for sealing such containers, but

' such means does not provide a seal which remains effective due to warping or distortion of the component parts by exposure to the high temperatures under which the heat treatments are carried out.

Furthermore, such seals usually require bolts or other clamping means which are laborious and often difiicult to operate and which frequently prevent openin of the container as rapidly as may be desira le or necessar after completion of the treatment.

and and clay have lon been used in an effort to eifect the sealing o containers in various treatments but such sealing means at best only hinder and do not prevent diffusion and easily opened and closed when desired.

A further object is to provide such a sealng means, the eflectiveness of which is not impaired by warping or distortion of the parts of the container under high temperatures.

Another object is to provide a seal of this character which effectively prevents any dif fusion between the gas within the container and the furnace atmosphere; and to prevent any appreciable leakage of gas through the seal in order that pressuressomewhat higher than atmospheric may be maintained within the container.

A still further object is to provide means whereby fresh gas may be introduced into the container as required and spent gas removed therefrom during the heat treatment without permitting access of the atmosphere to the container.

or more parts with a separable joint therebetween lying substantially in a horizontal plane, said joint being surrounded with a trough or channel of suitable depth and com taining a suitable sealing material, the cover member of the container having a depending flange adapted to enter the trough or channel and to be imbedded in the sealing material.

For the purpose of supplying gas to the container, a pipe or conduit may communicate therewith and a second pipe or conduit may be provided therein for conducting spent .gas away from the container to any desired point, means such as a throttling valve or the like being provided in the discharge pipe for permitting the gas to be maintained under pressure within the container.

I have found that a satisfactory sealing material consists of mineral matter having a density substantially greater than that of silica sand, and so pulverized as to have a largeproportion thereof substantially as fine as possible. 4

Very satisfactory results may be attained by using chromite or chrome-iron-ore, which has a density about 4.5 times that of water, as compared with silica sand having a density about 2.6 times that of water. Other materials suitable for this purpose are corundum having a specific gravity of approximately 4.4, and hematite with a specific gravity of approximately 5.5.

An embodiment of the invention is illustrated in the accompanying drawing, in which Figure 1 is a vertical sectional view through a furnace, showing the improved heat treating container therein;

Fig. 2, an enlarged fragmentary sectional view through the sealed joint between the container and cover;

Fig. 3, a similar view of the sealed joint between the base and side wall of the container; and

Fig. 4, a view similar to Fig. 2 of a modified form of seal.

Similar numerals refer to similar parts throughout the drawing.

The improved heat treating container to which the invention pertains may be located within a furnace of any type suitable to the treatment which is to be carried on.

As shown in the drawing, the furnace may comprise the bottom wall 10 and side walls 11 mounted upon any suitable structural base as indicated generally at 12, and enclosed Within a metallic shell 13.

A removable roof 14 is adapted to rest upon the upper edges of the side walls and a sand seal is preferably provided between the roof and side Walls, as indicated generally at 15.

The interior of the furnace may be heated by any suitable means such as the electrical resistors 16'and means may be provided in the bottom of the furnace, such as the pier 17 for supporting the improved container to which the invention pertains, illustrated generally at 18.

The improved container may comprise the base 19, side wall section 20 and cover 21, the base and side wall section being preferably separable, in which case a sealed joint is provided between said members.

This joint may be in the form of a channel or trough 22 formed around the edges of the base 19 and adapted to receive the lower edge portion of the side wall section 20, suitable sealing material, as above de' scribed, being provided in .the trough or channel, as indicated at 23, so as to form a .vided with the depending flange 27 adapted to extend into the channel 14 and the cover 21 may have a similar depending flange 28 also extending into the channel 25 whereby a substantially gas-tight seal is provided between the upper end of the container and the cover.

For the purpose of removing the cover, an eye or the like, as shown at 29, may be extended upward from the central portion thereof.

A gas supply pipe 30 may extend from any suitable source of gas supply through a wall of the furnace and communicates with the interior of the container, being preferably centrally located through the base 19, and a gas discharge pipe 31 may communicate with the container, preferably extending through the upper portion of the side wall section thereof and is located through a wall of the furnace for the purpose of carrying such spent gases to a suitable point outside of the furnace or even, if desirable or necessary, outside of the building in which the furnace is located.

For the purpose of maintaining a gas pressure above that of the atmosphere within the container, as well as for preventing the entrance of air to the container through the discharge pipe, a throttling valve 32, or other suitable device, may be provided in the discharge pipe.

The separate or independently movable seal channel or trough 25 is advantageous in some cases because it permits the trough to expand freely without interference from the side walls 20 of the container in cases of nonuniform heating, but for many purposes the trough may be formed integral with or fixed to the side wall, as shown at 25a in Fig. 4, this trough being adapted to hold the sealing material 23 and to receive the depending flange 28 of the cover in order to form a substantially gas-tight seal.

It should also be understood that the base 19 and side Wall section 20 may be fixed to gether or formed integrally although the construction illustrated in Figs. 1 and 3 is of advantage in that it permits relative expansion of the parts while enabling a gastight closure between the same.

It should be understood that I may use any desired number of seals in the container and may locate the seal or seals wherever convenient. For instance, it may be desirable to form a separable joint only at the junction between the side walls and the base, in which case the side walls and top may be formed integral or permanently fastened together. If desired, the side walls may be formed in a plurality of sections using a seal at each junction between such sections.

From the AbOXG it will be obvious that the present improvement overcomes the objections and difficulties referred to in the present practice and fulfills the objects above set forth in that it provides an efiicient seal easily and readily separable when desired, by which entrance of air or other gases maybe rendered impossible and outward leakage substantially prevented; and which permits a considerable excess of pressure to be maintained within the container.

In practice I have found that a seal of convenient depth will retain pressures of the order of four ounces per square inch, which pressures are ample for the requirements usually met in heat treating for which the container is adapted.

I claim:

In a heat treating container adapted to contain gas under pressure and including a separable joint, sealing means for the joint including pulverulent chromite.

In testimony that I claim the above, I have hereunto subscribed my name.

FRANK T. COPE.

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