US2312403A - Tempering furnace for small parts - Google Patents

Description

March 2, 1`943.

R. GRGER TEMPERING FURNACE FOR SMALL PARTS Filed March s, 1941 2 sheets-sheet 1 www,

.NQWYW/ March 2, 1943. R. GRGER 2,312,403

I TEMPERING FURNACE FOR SMALL PARTS Filed March 3. 1941 2 Sheets-Sheet 2 Patented Mar. 2, 1943 UNITED STATS TEMPERING FURNACE FOR SIWALL PARTS Rudolf Grger, Hanau, Germany; vested in the Alien Property Custodian 3 Claims.

Thisrinvention relates to tempering furnaces, andmore particularly to such furnaces which are adapted especially for the tempering of small objects, such as balls, screws, rivets and the like.

In the past furnaces for the treatment of small objects have usually been of two types, the drum type, and the push through type. The drum type furnace presents the drawback that a careful separation of the objects treated is necessary following termination of the heat treatment, This is necessary since, in many cases, various kinds of small objects are treated simultaneously in the rotary drum. The problem is particularly difficult during the simultaneous treatment in the drum of ball bearings, the sizes of which may vary from standard by, for example, 0.1 mm.

With the push through furnace, as the name implies, the articles are placed in containers and as they are conveyed through the furnace they are heat treated. The use of such furnaces gives rise, however, to important heat losses caused by the great space requirements, but chiefly from the .absorption of heat by the containers for the articles treated.

A principal object of the present invention is to provide a furnace for the treatment of small articles, which furnace obviates the disadvantages of the furnaces of the drum type and push through type.

Another important object of the invention is the provision of such a furnace 'which makes possible the simultaneous but separate treatment of small objects of various sizes and shapes and thereby an improved utilization of the furnace capacity and simplification of operation by eliminating the necessity for subsequent sorting.

Still a further object of the invention resides in the provision of a furnace which avoids unnecessary heat losses, and for the same capacity makes possible about a three-fold output as compared with a rotary drum furnace.

Other objects of the invention Will be evident from the following description and claims when read on the accompanying drawings in which:

Fig. l is a face view of a furnace embodying the invention;

Fig. 2 is a plan View, partially in section, of the furnace of Fig. 1;

Fig. 3 is a vertical section taken on the line 3 3 of Fig. 4; and

Fig. 4 is a Vertical section taken on the line 4 4 of Fig. 3.

As may be noted from these drawings, perhaps the characteristic dierence between known types of furnaces and those constructed in accordance with the present invention resides in the fact that in accordance with the present inE vention similar articles to be tempered are placed in pocket-like receptacles disposed vertically within the furnace and exposed to the tempering treatment by means of air circulation. These receptacles, which may take other shapes (such as a pipe-shape) are built rigidly within the furnace. Each of the plurality of receptacles n the furnace can' hold small objects and all of the objects placed in any one receptacle should be of the same size. This avoids the necessity for subse-A quent separation.

In the present invention the articles to be treated are heated by hot air. The air is pref erably drawn around the receptacles by a suc.- tion fan and then, by the same fan, forced past heating members located for example at the sides of the furnace, and thence back to the recep, tacles. By using specially provided guide plates it is possible for all of the receptacles to be bathed uniformly by the hot air,

Referring now specifically to the drawings, the furnace II is mounted a suitable distance above the floor by supports I2. The furnace is generally rectangular in shape, with the exception however that the bottom, as shown ,in Fig. 3, has a central portion I4 which slopes downwardly from. back to front, and side portions I6 which, as shown in Fig. 4, slope downwardly and inwardly from the side walls Il of the furnace.

Referring now to Fig. 3, the articles to be tempered, which may be ball bearings, screws, rivets, or the like, are placed in pocket-like receptacles I8 through openings 23 in the receptacles, which openings extend through Vthe top of the recep-f tacles and are adapted to be closed by lids or closure members 25. 'The bottoms ofthe receptacles slide forwardly and terminate in openings 2| to assure a complete emptying of the receptacles. As-shown in the drawings, the receptacles may have two similar walls in the form of parallelograms, which Walls are spaced a relatively small distance apart. The receptacles are emptiedv through means which can be actuated from the outside of the furnace. In the drawing figures such means are shown to be comprised of slide closures 26, one for each receptacle. 'I'he inner end of each slide 2S is adapted to block the corresponding opening 2I in the bottom of the receptacle I8. The outer end of each slide extends through the front Wall I5 of the furnace and terminates in a suitable handle 28. When the handle of a slide closure 26 is grasped and drawn forwardly the slide no longer blocks its corresponding opening 2| and the small articles which have been disposed in that receptacle I8 fall into the bottom of the furnace and thence into a collection box disposed below the opening 32 at the base of the furnace. Because of the slanting portions I4 and IB of the bottom as heretofore described, the articles falling from the receptacles I8 travel toward the opening 32. It is therefore necessary to have only one opening 32 regardless of the number of individual receptacles I8 disposed in the furnace.

In Fig. 2, which is a plan view of a furnace constructed in accordance with the invention (partially in section), the arrangement of the heating element and the air circulation means are evident. The suction fans and blower 34, supported by the back wall I3 of the furnace, force the air through the chamber 36. Heating elements 38 are disposed in the cham-ber 36. From there the heated air passes into the treating chamber 40 in which the receptacles I8 are disposed. The hot air passes around the receptacles I8 and is then drawn in again by the suction fan and blower where it is ready to start again on its continuous path of movement.

When the Ydimensions of the articles being treat.. ed permit it, the receptacles I8 may be provided with perforations or slots 42 on their end Walls,

their side walls, or both, through which the hot air can be drawn so as to pass in direct contact with the articles within the receptacle. Ordinarily the receptacles are spacedfrom each other, though this arrangement of spaces, of course, is not of such importance when the receptacle walls are perforated or slotted. In so far as spaces may still remain between the receptacles, such spaces may be closed by sheet metal mem-bers or the like so that the hot air must follow a path through the perforations or slots 42 in the receptacles and into contact with the articles of the charge.

From Figs. 2 and 4 it will be seen that the heating elements 38 may be constructed as tubular heating members which are arranged in the side chambers 36. The elements 38, either with or without protecting sheaths or pipes, may be mounted to a cover member 44 so as to be replace; able as a unit, or separately, Without interrupting operation of the furnace.

The furnace shown is also adapted for operation with advantage as an annealing and hardening furnace, at temperatures up to 1000 C. without air circulation.

Each receptacle I 8 may be provided with a time clock 46 and a control lamp 48, mounted in the front Wall of the furnace as shown in Fig. l. By this means each receptacle can be separately adjusted and controlled to the required time of treat--V ment. When a charge is inserted in a receptacle, the corresponding clock therefor is set for the time required for the treatment, and the lamp for that clock will then light when the treatment is completed. In this manner the operator will know when to empty the charge from the receptacle. The simultaneous tempering treatment of a considerable number of various kinds and sizes of receptacles, pipes or chutes could be secured to the receptacles to guide the treated articles from each of the receptacles directly to the placesY where they will be subsequently worked. These and other changes may be made without departing from the principles of the invention, and the invention is not to be limited in scope except by the following claims.

I claim:

l. A tempering furnace for small objects of various sizes, comprising a heating chamber, a plurality of spaced receptacles mounted within said chamber, including at least one receptacle for each size of the small objects to be treated, 4said receptacles being substantially in the shape of parallelograms of relatively narrow thickness and arranged within the chamber with two sides of the parallelograms in vertical position and the other two sides slopngdownwardly, inlet charging means at the uppermost corner of each receptacle and extending through the top of the furnace, outlet emptyingvmeans at the lowermost corner of each receptacle, means extending to the outside of sai-d furnace to control said outlet emptying means separately, heating elements within said furnace, and circulating means for directing air past said heating elements andl into contact with said receptacles to treat the articles within said receptacles, each of said pocket-like receptacles having perforations of a size smaller than the size of the articles to be treated in that particular receptacle, whereby air directed to said receptacles passes into actual contact with the articles treated.

2. A tempering furnace for small objectsv of various sizes, comprising a heating chamber, a plurality of spaced receptacles disposed within said chamber including at least one receptacleV for each size of the small objects to be treated, each of said receptacles having separate charging and emptying openings controlled from the outer Walls of the furnace, said emptying openings in the spaced receptacles being within the furnace, heating means within the furnace, means for directing air in contact with said heating means and thence into contact with said receptacles, a closable discharge opening in the furnace spaced 'below the receptacles and means sloping downwardly toward RUDOLF GRGER,

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