US1222793A - Method of annealing articles. - Google Patents

Description

A. L. POLLARD.

METHOD OF ANNEALING ARTICLES.

APPLICATION FILED DEC-1| 1916.

1,222,?93, Patented Apr. 17, 1917.

l VENTDFE 7 /6 by Z9414 ATT DRNEY.

ARTHUR L. POLLARD, OF BATAVIA, NEW YORK.

METHOD OF ANNEALING ARTICLES.

Application filed December 1, 1916.

To all whom it may concern:

Be it known that l, ARTHUR L. POLLARD, a citizen of the Unitec States, residing at Batavia, in the county of Genesee and State of New York, have invented new and useful Improvements in Methods of Annealing Articles, of which the following is a specification.

This invention relates to a method of annealing castings of iron or similar material so as to render the same soft or malleable.

lileretofore annealing of castings has generally been effected either by placing the articles to be annealed in a pot of iron or steel arranged in an oven with or without the addition thereto of a protective or active material such as slag or mill scale, or the castings were charged loosely into a muflie oven together with a suitable protecting material after which the oven is heated a suflicient length of time to thoroughly heat the castings under treatment and then the heat is shut off and the ca stings are allowed 'to cool slowly. The use of such pots involves considerable expense and the heating of the castings therein as well as the heating of castings when charged loosely into a mufile oven necessitated the placing the pots filled with casting in the oven or charging the loose castings and protecting material in the oven while the heat was practically cut off from the same, and as the entire mass was usually very thick an undue length of time was required for thoroughly heating the castings, it being necessary in most instances to heat the same from about two days to about a week in orderto accomplish this purpose. This necessarily involved undue loss of time and increased the cost of the product accordingly.

It is the object of this invention to provide a method of annealing castings or other articles of this character whereby the time in which the heating of the castings is very materially reduced and a corresponding reduction in the cost of annealing the same is efiected;

ln carrying out this improved process the heating 01 the casting or similar articles along with the protective material is effected by charging the castings into the oven together with a comparatively thin layer of protecting material over the same while the furnace is under fire or being heated. Inasmuch as the castings at this time are separated from the heating agent by a thin layer Specification of Letters Patent.

Patented Apr. 17, 191%.

Serial No. 134,290.

of protecting material the heat is able to penetrate this protecting material and reach the castings and heat them to the proper eX- tent in a comparatively short time suitable for rendering the same soft or malleable. In most cases the time required for heating the castings while protected by a thin layer of mill scale, slag or similar material is about two hours. After this the'heating agent is cut off and the oven is permitted to cool down slowly in the usual manner being usually from about two days to about one Week depending upon the character and size of the castings which are being annealed.

When a large quantity of castings is to be annealed in accordance with my improved process the castings and protecting material are charged in alternate layers into the even while the same is under heat, these layers being superposed, and the heating of each layer of castings with a covering of pro tecting material above the same being continued for a su'llicient length of time to thoroughly anneal the respective layer of castings before another layer of unannealed castings together with a protecting covering of mill scale or slag is charged into the oven. These successive layers of castings and protecting material are charged alternately into the oven until the latter is filled and then the heating of the entire mass is continued until the uppermost layer of castings has been sufiiciently heated to render the same soft or malleable. Each of the several layers of castings is in this manner heated very quickly inasmuch as the same at the time of heating is only separated from the heat of the oven by a thin layer of protecting material. Each layer of castings therefore requires only about two hours of heat treatment in order to render the same soft or malleable, thereby enabling the time for heating a large number of superposed and alternating layers of castings and protecting material to be reduced considerably as compared with a process in which a large and comparatively thick mass of castings and protecting material is heated at one time, inasmuch as the heating of such a large mass must be continued for a much longer period of time in order to enable the heat to penetrate the mass and reach and properly heat the castings in the innermost part of the same.

After the layers of castings and protecting covering have been successively charged into the oven while the latter is under heat and the last batch or layer of such castings has been heated the required extent, the heat supplied to the furnace is shut down and the castings are allowed to cool slowly and for a sufficient length of time to retain the malleability in the castings.

The oven by which my improved method of annealing castings or similar materials is effected may be variously constructed but that shown in the accompanying drawings is typical of one form which is suitable for this purpose.

In these drawings:

Figure 1 is a horizontal section taken on line 11, Fig: 3 showing one form of annealingoven whereby my improved method may be practised. Fig. 2 is a vertical longitudinal section of the same taken on line 2-2, Fig. 3. Fig. 3 is a vertical transverse section taken on line 33, Fig. 2.

In the following description similar characters of reference refer to like parts in the several figures.

1 represents the foundation of the oven, 2, 2 the upright longitudinal side walls thereof, 3, 4- the front and rear end walls thereof, 5 the roof connecting the side and end walls at the top thereof and 6 a fire wall or bridge extending transversely across the interior of the oven at a distance rearvmrdly from the front wall and dividing the interior of the oven into a front furnace or heater 7 and a rear charging or annealing chamber 8 which receives the castings to be annealed and the protecting material for covering the castings.

The heat may be generated in any suitable manner, for instance by a grate 9 upon which hard fuel. is placed through a feed opening 10 in the front wall, the ashes of the fuel being removed through a delivery opening 11 formed in the front wall below the grate. It is to be understood, however, that any other suitable heating means, agent or medium may e employed instead of burning hard fuel over the grate. The top of the partition 6 is separated from the roof of the oven by a heat passage 12 connecting the furnace with the annealing or charging chamber.

Within the charging or annealing chamber and arranged at a distance from the side walls of the oven are two upright longitudinal partitions 13, 13 which extend from the foundation of the oven upwardly to within a short distance of the roof so as to form longitudinal heat passages 11 between the longitudinal walls of the oven and the longitudinal partitions 13 which passages 1 1 communicate at their upper ends with the top of the charging space between the longitudinal partitions, as clearly shown in Fig. 3.

At different points in the height of the longitudinal walls the same are provided with heat openings or conduits 15 so that the heat can pass freely through these openings when the same are not obstructed by protecting material. The undersides of these heating openings are preferably inclined downwardly toward the center of the oven, so that there is little, if any, tendency for protecting ma erial to lodge in the same.

16, 16 represent the main pipes "of two ex haust flues which are arranged lengthwise and horizontally in the foundation beneath the oven and which have their outlet ends connected with a chimney or other means for exhausting the heated air from these lines while their inlet ends are connected respectively by ineansof a plurality of branch pipes or passages 17 with the lower parts of the longitudinal heat passages 1-1, each of these branch pipes being preferably formed partly in the foundation and partly in the lower ends of the longitudinal oven walls, as shown in Fig. 3. The escape of the heating medium from the main exhaust pipes may be regulated or shut off altogether by means of a closure which in the present instance consists of a vertically movable valve, slide or shutter 18 which is adapted to be moved into and out of a position across the outlet portion of each main flue and which is accessible from above the foundation so that the same may be manipulated. The castings and protecting materials are charged into the charging space of the oven through one or more charging or feed openings 19 ar- 100 ranged in the roof of the oven above the charging space, four of such openings being shown in the drawings and each adapted to be covered by means of a lid 20 when the rcspective opening is not in use.

In operating this oven for annealing iron castings or similar materials or articles in accordance with my intention the furnace is fired and the dampers or shutters 18 are opened so as to cause the heat to pass from the furnace rearwardly into the charging space or annealing chamber and the longitudinal passages 1 1 and transverse openings 15 connecting the same and thence through the branch and main pipes of the exhaust fines to the chimney or other exhausting device leading to the outer atmosphere. After the oven has been heated to the required extent a lowermost layer 21 of protecting material such as slag or mill scale is placed upon the floor or bottom of the charging chamber, then a layer or batch 22 of castings is placed over the lowermost layer of protecting material and then these castings are covered by a comparatively thin layer 23 of protecting material such as slag or mill scale. The charging of this layer of castings with the protecting material into the oven is effected through the openings 19 While the oven is under heat and after this charging operation has been completed the lids 20 are placed over the filling openings and the furnace is operated under heat for a suiiicient length of time to properly heat the layer of castings which has just been introduced into the oven, the time required for this purpose being approximately two hours although this varies according to the particular character or size of the castings which are being treated. After one layer of castings has been heated in the manner described another layer 24 of castings is in like manner charged into the annealing chamber of the oven together with a covering 25 of protecting material while the oven is under heat and then the charging is suspended and the heating of the furnace continued until the last mentioned layer of castings has been softened or rendered malleable, this operation likewise being effected in a comparatively short time by reason of only a thin layer, of protecting material being interposed between the last mentioned layer of castings and the heating agent. This operation is repeated for each successive layer of castings which is introduced into the annealing chamber and covered by a thin layer of protecting material until the annealing chamber has been filled to the top. When the uppermost layer of castings has been heated sufficiently in the manner described the heat is shut off and the dampers 18 are closed so as to prevent further heating of the castings and then the entire mass of castings and protecting material in the annealing chamber is allowed to cool slowly the required length of time to preserve the malleability of the castings. After the castings have been suiliciently cooled the same are removed together with the protecting material from the annealing chamber, this removal being preferably effected through the rear end of the charging chamber by first taking down or removing the rear end wall 4 or so much thereof as may be necessary to accomplish this purpose. After the castings and protecting material have been removed from the charging chamber this rear wall is agaln restored preparatory to annealing another lot of castings when the operation is repeated as before described.

My improved process for annealing iron castings or similar material for rendering the same malleable effects a large saving in the cost of producing such articles by reason of the fact that the oven is capable of yielding a larger output within a given length of time than has been possible heretofore. Furthermore, it permits of employing the attendants of the annealing furnace to greater advantage by reason of a reduction in the length of the intervals of rest which have been necessary in the methods of annealing heretofore used.

Moreover this process dispenses with the use of pots and the expense incident thereto.

I claim as my invention:

The herein described method of annealing articles which comprises placing a layer of articles to be annealed in an oven and covering said layer of articles with a layer of protecting material in the presence of a heating medium and then suspending the further addition of articles and protecting material until said articles have been heated sufficiently to render them malleable, then successively adding another layer of articles to be annealed and another layer of protecting material in the presence of a heating medium and continuing the heating of the same until the last layer of articles has been heated sufiiciently to render them malleable, and then in like manner successively adding further layers of articles to be annealed and layers of protecting material in the presence of a heating medium until the oven has been filled to the required extent and continuing the application of heat thereto until the last layer of articles has been heated sufficiently to render them malleable, and then permitting the whole mass of articles and protect ing material to cool slowly.

ARTHUR L. POLLARI).

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, I). C.

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