US1893963A - Electrically heated drying furnace for casting cores and the like - Google Patents

Description

E. F. RUSS Jan. 10, 1933.

ELECTRICALLY HEATED DRYING FURNACE FOR CASTING GORES AND THE LIKE Filed Oct. 25, 1930 Patented Jan. 1@, 1933 EMIL FRIEDRICH RUSS, OF OGLOG-NE-MARIENBUBG, GERMANY ELECTRIGALLY HEATED DRYING FURNACE FOR CASTENG COBES AND THE LIKE Application filed October 23, 1930, Serial No. 480,725, and. in Germany October 19, 1929.

This invention relates to electric furnaces for drying casting cores and the like with vertical elevator travelling through an O-shaped shaft divided by a centre wall, in which elevator the cores are moved upwards from a 0 also by the waste gases from the cones.

It is difiicult in such endless O-shaped shaft spaces with continuously travelling material, to introduce fresh air and, separate there from, to lead of the used moist furnace air without considerable loss of air, as also at the same time, whilst guiding the drying air in counter current to the travelling material, to cool the dried material or to preheat the fresh air.

According to the invention a channel, provided with electric heating elements and with a ventilating blower, branches off the conveying shaft from the charging port serving at the same time as fresh air port at a distance suliicient for cooling the finished dried material, or for recovering the heat in front of a narrowed portion of the conveyer shaft, said branch channel having the smallest possible passage aperture and again branching into the shaft. above the narrowed portion so that heated air is fed continuously into the furnace shaft during the tr veling movement of the elevator.

It is known in drying furnaces, to close the feeding and discharging apertures for the material by narrowed channel parts.

According to the invention however these narrowed portions are intended to force the heated drying air into a certain determined current path without requiring self acting air valves. and the like.

An embodiment of the invention is illustrated by way of example in the accompanying drawing in which:

Fig. 1 shows the Vertical shaft chamber in longitudinal section.

Fig. 2 is a cross section through the shaft.

Fig. 3 shows the arrangement of the blower.

Fig. 4c shows the arrangement of the trays or supporting brackets.

In the drawing 1 represents the vertical shaft insulated towards the outside, in which an elevator 3 travels in the direction of the arrow 2 over suitable chain driving wheels 1 and 5. 6 is the service opening, which is preferably arranged at arms height above the floor 7. This service opening 7, through which the material to be dried is charged and removed, serves also as fresh air port. The air is guided through this fresh air port in the direction of the arrows 8 in counter flow to the travelling movement of the elevator.

According to the invention av branch channel 9 is arranged at a suiiicient distance from the fresh air port 6, at the end of which channel a ventilating blower 10 is arranged. The channel 9 111L1Sl3 be dimensioned and pro portioned, as regards its passage cross section, as compared with the neighbouring travelling channel for the elevator so that the air flow 19 moves through the outward branch 11 into the channel 9 and consequently is led through the inward branch 12 again into the furnace channel. This can be effected in various manners. In the example illustrated the conveyer shaft is narrowed near the channel 19 by a second short conveyer shaft 13 arranged therein and of narrower cross section, so that the elevator can be moved therethrough with very little clearance. This narrowed shaft 13 must be sufficiently large, so that the furnace channel above and below this reduced portion has a suiiicient reduction of the air resistance. For further labyrinth-like packing in this narrowed channel 13 the trays or supporting brackets are provided with a sheet metal strip 20 (Fig. 41)

extending all round the bottom and beaded or similarly shaped on its lower edge, in order to be able to bear almost entirely against the shaft wall of the narrowed channel 13 for the purpose of reducing to the greatest possible extent the clearance between the supporting brackets and the shaft wall. Heating elements 14 are suspended in the channel 9 so that the elevator travelling from the service opening 6 over the hot cores in the direction of the arrow 2 is cooled by this air flow which is at the same time preliminarily heated, whereupon after being strongly overheated by the heating elements 14, it is forced by the ventilating blower 10 into the furnace channel. Consequently the already strongly preheated cores travel on the elevator travelling in the direction of the arrow 2 in counter flow to this hot air current flowing in the direction of the arrow 15. A similar narrowed portion is obtained above the service opening (3 with the aid of inserts 16, which act similarly to the sheet metal inserts 13. Above this reduced portion of the shaft the suction blower 17 is arranged, which exhausts the moist and used air from the furnace shaft. The reduced portion of the furnace shaft above the service opening 6 prevents, on the one hand, consumed air being again circulated by the blower 10 and, on the other hand, the suction blower 17 exhausting fresh air upwarm from the service opening 6. This prevention of air deflection cannot be entirely avoided by these shaft reduced portions 13 and 16, but a sufficient shutting off is obtained so that small erring quantities of air are harmless.

By this arrangement it will be possible, to allow the elevator to run continuously, the speed having to be so adjusted in consideration of the length of the furnace channel that the material fed is dried in travelling once through the furnace, and so that both the dried material can be removed and the fresh material to be dried inserted. In spite of this uninterrupted travel of the material to be dried, a continuous current of air is sucked from the service opening 6 over the portions of the elevator to be cooled, is heated in the shaft 9 heating elements 14 and then conducted through the furnace channel in counter flow, during which the heat absorbed from the electric heating elements 1 1 is imparted to the material to be dried, so that the used air can be continuously exhausted by the blower 17. An uninterrupted working, especially as regards the heated air current, is important in order to prevent heat differences or heat impulses occurring in the material to be dried through intermittent working.

There is nothing to prevent additional heating elements 18 being arranged. above the branch channel 9 between the elevator and the furnace wall 1, in order to subsequently heat the air and the material.

Fig. 3 shows the construction of the air agitator 10, which imparts the movement to the hot air. A blade wheel driven by an electric motor sucks in axial direction the air to be circulated and ejects it around its circumference. The suction blower 17 may be evident-1y replaced by a suction draught, for example a chimney stack.

a The arrangement of the trays or supporting brackets is shown in Figs. 2 and 4. In

by the these figures the narrowed portions 13 and 16 of the conveyer shaft are shown, seen from above, as also the manner in which the sheet metal strips 20 arranged around the circumference of the bottom of the support-- ing brackets bear against the sheet metal walls 13 and 16 respectively of the narrowed portions of the shaft, in order to thus produce a labyrinth-like packing therein, as several trays or supporting brackets are desired guided tightly in the narrowed por tions of the channel.

I claim 1- 1. An electrically heated drying furnace for casting cores and the like, comprising in combination a shaft, a partition dividing said shaft into two sections, a vertical elevator adapted to circulate in said shaft, a service opening in said shaft for charging on and removing the cores from said elevator, a narrowed portion in the section of said shaft remote from said service opening adapted to prevent the upward flow of air in this section of the shaft, a branch channel bridging said narrowed portion adapted to conduct the air out of and back into the shaft around said narrowed portion, heating elements in said branch channel adapted to heat the air passing through said channel, and a ventilating blower in said branch channel adapted to suck the air from said shaft into said branch channel and to return this air into said shaft after being heated by said heating elements.

2. A drying furnace as specified in claim 1, comprising in combination with the shaft having a partition and a fresh air port serving as service opening, a reduced portion of said shaft above said port narrowed to the smallest possible diameter adapted to prevent the upward flow of air from said port, and a suction ventilator above said narrowed portion adapted to suck in fresh air through said port and exhaust the moist furnace air after passing around said partition.

3. A drying furnace as specified in claim 1, comprising in combination with the elevator and the narrowed portions of the shaft, trays for said elevator, and resilient scraping elements on said trays bearing against the wall of and adapted to produce a labyrinth packing in said narrowed portions of the shaft.

4. A drying furnace as specified in claim 1, comprising in combination with elevator, the shaft wall and the outwardly branching heating channel, an air exhaustor, and a plurality of electric heating elements between said outwardly branching heating channel and said exhaustor between said elevator and said shaft wall.

In testimony whereof I aflix my signature.

EMIL FRIEDRICH RUSS.

Images