US1700366A - Supporting finger for annealing furnaces - Google Patents

Description

Jan.- .29,929. I

'F. A. 'FAHRENWALD", 'suP-P RTING FINGER. FOR "-ANNEALING-I FURNACES Filed A ril 20, 1928 so made.

atented Jan. 29, 1929.

STATES FRANK A; FAHRENWALD, OF CHICAGO, ILLINOIS.

SUPPORTING FINGER FOR ANNEALING- FURNACES.

Application med April 20, 1928. Serial No. 271,451.

This invention relates to furnaces employed for heating sheets or other objects that have to be supported above the hearth of the furnace during the heating operation,

x and particularly to a novel construction of upstanding support in the form of a finger, a plurality of which at suitably spaced intervals are presented within the furnace chamber by endless chain carriers traveling in slotted conduits which are constructed in the hearth.

It has long been the practice to arrange a suitable number of endlesslink carriers in position to travel through slotted conduits incorporated in the hearth structure, and to provide thesecarriers with upstanding fingers that afford support to the sheet or other object at suitably spaced intervals. But these fingers, under the severe stresses set up in them by unequal heating and cooling as they pass from outside atmosphere into the furnace andfrom the furnaceback to the atmosphere, are subject to cracking, spalling, and distortion which makes them comparatively short lived and involves considerable expense in removing the spent fingers and introducing new ones into the links of the chains, not to mention the shutting down of the furnace while the replacement is being The object of the present invention is to provide a construction of finger for the purpose stated, which will enable the finger to withstand the aforesaid temperature influences; and the invention is based upon the discovery that the failure of fingers heretofore used is due to the 'more rapid changes in the exterior portions of the finger than the interior portion thereof, so that the interior portion becomes a resistance or fulcrum against which the exterior portion must drag in expanding and contracting, and this sets up surface stresses of sufiicient tension totear the metal asunder and thus gradually render the finger useless. Accordingly, the invention proceeds upon the principle of giving to the finger a frame-like construction of such form that it will have an open interior throughout the portion which encounters serious heat effects and receive its essential strength from spaced vertical legs of sufficiently reduced transverse section to enable the entire section of each leg to act more nearly asa unit in expanding and contracting under changes of temperature, and which will be sufliciently spaced apart in their union, with the body or baseportion of the finger, as well as the supporting seat which is provided by the upper end of the finger, that each will sustain the other transversely without causing a drag or resistance to its expansion or contraction, so that even if they should not expand and contract in unison, and one leg should expand or contract relativelyto the other, the other leg can yield transversely within its elastic limit and the two legs thus become mutually compensating.

In the accompanying drawing, in which the preferred and a modified construction of the invention are shown by way of illustration,

igure 1 is a conventional representation, in vertical transverse section, of a heating furnace suitable for annealing metal sheets and in which are installed endless conveyors provided with fingers constructed in accord-v ance with the present invention.

Figures 2 and 3 are, respectively, a side elevation and a top plan view of a section of one of the conveyors employed in Figure 1, drawn on an enlarged scale; and

Figure 4 is a detail view representing in side elevation a finger of slightly different construction from that shown in Figure 2.

A represents a furnace of conventional construction, having a hearth B, and C represents a series of endless chain conveyors traveling in conduits D embodied in the structure of the hearth and communicating with the furnace chamber through transversing slots E that permit the passage of upstanding supporting fingers 1 carried by the endless chains.

According to one embodiment of the pres ent invention as shown in Figure 2, each finger 1 while inserted in the socket 2 of the carrying chain C and-there secured by any suitable means, such as rivets 4, in accordance with known practice is constructed, particularly inits upper portion which is subjected to severe heat, of upstanding spaced legs 5, such, for instance, as would be left by forming a longitudinally extending transverse opening 6 through the Finger 1, and a yoke 7 uniting the upper ends of the legs 5 and constituting the seat upon which the workpiece rests while in support upon the conveyors. Legs 5 will preferably be integral 'with the body 1 of the finger, as well as with the yoke 7.

, As shown in Figure 4, a finger may consist of the body 1 secured in socket 2 by means of rivet 3 and constructed with upstanding legs 5*- that are united not onlyat their upper or 5 and the cooling influence of the opening 6 or 6 are such that expansion and contraction will proceed with such correspondence in the two legs-that each will not only expand encounterat any one time,

and contract as a whole section, but neither will impose anyserious resistance tothe expansion or contraction of the other, first, be-

cause there will be little difference in the heating and cooling influences which they and, secondly, because if either should expand or contract relatively to the other,.the other can flex Within its elastic limit transversely and thereby compensatethe temporary diiference in longitudinal dimension.

I claim: y I 1. A finger for supporting conveyors of heating furnaces, comprising an upstanding member of frame-like construction embodying in that portion of the finger which is subected to excessive temperature changes, vertical legs with intervening cooling space.

2. A finger for supporting conveyors of heating furnaces, comprising an upstanding member of frame-like construction embodying in that portion of the finger'which is subjected to excessivetemperature changes,

vertical legs with intervening cooling'space; said legs being unitedat top by a seat for the workpiece that is to be supported.

3. A finger for supporting carriers'of heating furnaces, consisting of a member adapted to be mounted upon the carrier in upstandjing position and comprising a body portion,

a seat-forming arch, and upstanding legs with a cooling space between them; said legs ,being integrally united above and below by said arch and said body portion.

4. A finger for supporting carriers of heatin furnaces, consisting of a member adapted lto ioemounted upon the carrier in upstanding position and comprising a body-portion, a seat-forming arch, 'and upstanding legs with a cooling space between them; said legs being integrally united aboveand below by said arch and said body portion, and intermediately connected by a bridging member which divides the cooling space between them. Signed at Chicago, Illinois, this 6th day of April, 1928. I

FRANK A. FAHRENWALD.

Images