GB2158688A

GB2158688A - Apparatus for cooling roller paths and/or the side walls of a wafer baking oven

Info

Publication number: GB2158688A
Application number: GB08511524A
Authority: GB
Inventors: Sen Franz Haas; Franz Haas; Johann Hass
Original assignee: Haas Franz Waffelmaschinen Industrie GmbH
Current assignee: Haas Franz Waffelmaschinen Industrie GmbH
Priority date: 1984-05-08
Filing date: 1985-05-07
Publication date: 1985-11-20
Also published as: BR8502174A; GB8511524D0; DE3516379A1; ATA150684A; DE3516379C2; AT380150B; DD232810A5

Abstract

Apparatus for cooling roller paths and/or the side walls (5) of a wafer baking oven comprises revolving baking tongs (2), which form an endless chain and are provided with laterally disposed rollers (4) resting on track rails (6), which extend in the wafer baking oven close to its side walls. In order to reduce the energy consumption in the wafer baking oven, pipes or tubes (11) are provided for conducting air and have openings (12 and 16, 14, 15) which respectively cool rollers (14), cam followers (13) and side walls (5). Alternatively, a closed cooling circuit using water or oil and including heat exchanger and pump may be used. <IMAGE>

Description

SPECIFICATION Apparatus for cooling roller paths and/or the inside surfaces of the side walls of a wafer baking oven comprising revolving baking tongs Background of the invention Field of the invention This invention relates to apparatus for cooling roller paths and/or the inside surfaces of the side walls of a wafer baking oven comprising revolving baking tongs, which are connected in series to form an endless chain of baking tongs and are provided with laterally disposed rollers resting on track rails, which extend in the wafer baking oven close to its side walls.

Description of the prior art In connection with gas-fired wafer baking ovens having revolving baking tongs it is known to prevent an overheating of the side walls of the oven and of the rollers of the baking tongs in that the volume of gas sucked from the oven chamber through the exhaust greatly exceeds the volume of gas which corresponds to the rate of heating gas required to obtain the temperature desired in the oven chamber and the rate of water vapor generated by the baking operation. That additional rate of gas being exhausted is due to an admission of secondary air, which is sucked into the oven chamber between individual elements of the side walls of the oven andior the secondary air admitted at a high rate between the lower longitudinal edges of the wafer baking oven and the floor on which the oven is supported.That secondary air prevents a rise of the local temperature in the baking oven adjacent to the side walls of the oven and adjacent to the track rails above a critical value but involves also a high consumption of energy because the secondary air must be heated too.

Summary of the invention It is an object of the invention to reduce the energy content of a wafer baking oven.

This is accomplished in accordance with the invention by the provision of apparatus which is of the kind described first hereinbefore and which is characterized in that means are provided for conducting coolant streams along the paths for the rollers and/or the side walls and in contact with or in shielding relation to the rollers and/or the corresponding inside surface of the adjacent side wall.

Within the scope of the invention, a film of cooling air may be formed on the inside surfaces of the side walls of the oven and may rise on the inside surface of the side wall of the oven and may form an air layer that shields andlor insulates the inside surface of the oven wall from the interior of the oven and said film may be continuously renewed by additional cooling air and at the top end of the side wall of the oven may be deflected to the interior of the oven and may be sucked through the gas outlet of the oven chamber together with the baking atmosphere.Similarly, a stream of cooling air may be directed to the roller paths to form on the track rails and'or rollers a film of cool air, which adheres to said rails and;or rollers for a short time and rises therefrom only as it is progressively heated and which is continuously renewed from the stream of cooling air. When the cooling action of the air stream directed to the roller tracks has ceased, that air stream is also sucked with the baking atmosphere. The rate at which air is required to maintain a given film of cooling air is much lower than the rate at which secondary air was previously sucked into the oven so that the heating of the air supplied by the stream of cooling air is not significant in the energy balance of the wafer baking oven.

Within the scope of the invention, shielding means for shielding the roller paths and for the inside surface of the adjacent side wall of the wafer baking oven may also be provided so that the heating power to be generated by the means installed in the oven can be distinctly reduced and it is not necessary to heat air which is not required for the baking operation proper.

Also within the scope of the invention, cooling air lines are provided, which extend along the side walls and are have outlet openings or nozzles, which face the inside surface of the adjacent side wall and serve to discharge a stream of cooling air.

The cooling air lines may be disposed at the lower end of the adjacent side wall of two cooling air lines may be provided at each side wall and distributed over the height of the side wall in order to produce a film of cooling air of uniform thickness along the inside surface of the side wall.

Also within the scope of the invention, cooling air lines are provided, which extend along the roller paths and have lateral openings or nozzles which face the rollers and'our the inside surfaces of the side wall and serve to discharge a stream of cooling air. The cooling air lines are suitably disposed close to the side walls adjacent to the track rails so that the outflowing stream of cooling air impinges directly on the inside surface of the side wall and on the track rails and the rollers resting on said track rails.

Also within the scope of the invention the cooling air lines may be constituted by tubular sections of the oven frame so that said lines are integrated in the oven frame.

Also within the scope of the invention, the means for shielding the roller paths may consist of cooling shells, which are flown through by a coolant and partly surround the roller paths. With that design the access of the baking atmosphere to the roller paths is rendered more difficult and the regions which are close to the roller paths are directly cooled.

Also within the scope of the invention the cooling shells consist of tubular sections, which partly surround the profile of the rollers and, if desired, carry the respective track rail. In that case each cooling shell may constitute a C-shaped structure embracing the roller path so that the rollers have three sides moving past cooled surfaces whereas the open fourth side is substantially closed by the chain links interconnecting the rollers. The rollers thus move in a cooled tunnel, which is closed with the exception of narrow longitudinal slots.

Also within the scope of the invention the cooling shells, which are optionaily provided with lateral outlet openings, may be interconnected by pipelines in at least one open air cooling system, which is open outside the baking oven and connected to a blower. In that case the advantage will be afforded that the ambient air around the wafer baking oven at the oven site can be sucked forced by the blower directly through the cooling shells by pressure or suction so that the apparatus in accordance with the invention constitutes a simple structure.

Within the scope of the invention a recovery of the heat dissipated via the cooling shells can be effected in that the cooling shells are interconnected by pipelines in a closed cooling circuit flown through by coolant and incorporating a circulating pump and a heat exchanger. The coolant may consist, e.g., of water or oil.

The invention provides simple means by which the temperature in the bearings of the rollers and/ or the cam follower rollers for closing the baking tongs can be kept below 150cm during the operation of the wafer baking oven without a need for sucking secondary air at a high rate so that a wafer baking oven provided with apparatus in accordance with the invention may be operated with a heating power which is not in excess of the power required for the baking operation.

Brief description of the drawing Figure 1 is a transverse sectional view showing the oven chamber of a wafer baking oven provided with apparatus in accordance with the invention for supplying a stream of cooling air to the rollers of the baking tongs and to the inside surface of the side wall of the oven.

Figure 2 is a transverse sectional view showing a wafer baking oven comprising cooling shells which embrace the rollers.

Detailed description of the preferred embodiments Illustrative embodiments of the invention will now be explained more in detail with reference to the drawing.

The drawing shows a wafer baking oven 1 comprising revolving baking tongs 2, which are connected in series to form an endless chain of baking tongs. The oven 1 defines an elongate parallelepipedic oven chamber 3, in which the baking tongs 2 travel along two superimposed paths in mutually opposite directions and are heated by heating elements, which are not shown on the drawings for the sake of clearness. As the baking tongs 2 travel through the oven chamber 3, the baking tongs 2 are supported by laterally mounted rollers 4 on track rails 6, which extend in the longitudinal direction of the oven chamber and are mounted close to respective side walls 5 of the oven. The track rails 6 are secured by angle sections 7 or tubular sections 8 to the carrying frame 9 of the wafer baking oven.That carrying frame 9 consists, e.g., of tubular sections and carries the side walls 5 of the oven as well as the top wall 10 of the oven.

Figure 1 shows the upper path for the baking tongs 2. A pipeline 11 for cooling air extends along each track rail above the rollers 4 resting on the track rail 6 and is secured to the carrying frame 9.

The pipeline 11 is provided with outlet openings 12, which face the rollers 4 and direct the outflowing cooling air from above directly to the rollers.

The pipeline 11 for cooling air is diposed on that side of the baking tongs which is provided with the cam follower rollers 13 for closing the baking tongs. That pipeline 11 is also provided with outlet openings 14, which direct cooling air directly to the cam follower roller 13.

Figure 1 shows also the lower path for the baking tongs 2. Adjacent to that lower path the cooling air lines 11 are constituted by tubular sections 8, which carry the track rails 6. Each tubular section 8 is provided with lateral openings 15 facing the inside surface 5" of the adjacent side wall 5 and with top openings 16 extending through the track rails 6 and directed toward the rollers 4. That tubular section 8 which extends close to the cam follower rollers 13 for closing the baking tongs 2 is also provided with openings 17 for directing cooling air toward the cam follower rollers 13.

In the illustrative embodiment shown in Figure 2, cooling shells 18 extend along the roller paths for the rollers 4 of the baking tongs 2 and shield each roller from its immediate environment. The cooling shells 18 are bipartite and each of them consists of a tubular section 19 disposed above the track rail 6 and a tubular section 20 disposed below the track rail. The cooling shells 18 may be directly flown through by air at a temperature below the temperature in the oven chamber. That air may be forced through the cooling shells 18 by a blower. Alternatively, as is shown in Figure 2 in association with the lower path for the baking tongs, the cooling shells may contain passages 21, in which a coolant is conducted and which are connected in a closed cooling circuit with a heat exchanger and a circulating pump.

The cooling shells 18 consisting of tubular sections 20 may constitute load-carrying sections, to which the hardened track rails 6 are secured.

It will be understood that the varients of the apparatus embodying the invention shown at the bottom and top in Figures 1 and 2 may be used in any desired combinations.

Claims

1. Apparatus for cooling roller paths and/or the inside surfaces of the side walls of a wafer baking oven comprising revolving baking tongs, which are connected in series to form an endless chain of baking tongs and are provided with laterally disposed rollers resting on track rails, which extend in the wafer baking oven close to its side walls, characterized in that means are provided for conducting coolant streams along the paths for the rollers and/or the side walls and in contact with or in shielding relation to the rollers and'our the corresponding inside surface of the adjacent side wall.

2. Apparatus according to claim 1, characterized in that cooling air lines are provided, which extend along the side walls and have outlet openings or nozzles, which face the inside surface of the adjacent side wall and serve to discharge a stream of cooling air.

3. Apparatus according to claim 1, characterized in that cooling air lines are provided, which extend along the roller paths and have lateral openings or nozzles which face the rollers and/or the inside surfaces of the side wall and serve to discharge a stream of cooling air.

4. Apparatus according to claim 2 or 3, characterized in that the cooling air lines are constituted by tubular sections of the oven frame.

5. Apparatus according to claim 1, characterized in that the means for shielding the roller paths consist of cooling shells, which are flown through by a coolant and partly surround the roller paths.

6. Apparatus according to claim 5, characterized in that the cooling shells consist of tubular sections, which partly surround the profile of the rollers and, if desired, carry the respective track rail.

7. Apparatus according to claim 5 or 6, characterized in that the cooling shells, which are optionally provided with lateral outlet openings, are interconnected by pipelines in at least one open air cooling system, which is open outside the baking oven and connected to a blower.

8. Apparatus for cooling roller paths and/or the inside surfaces of the side walls of a wafer baking oven comprising revolving baking tongs, which are connected in series to form an endless chain of baking tongs and are provided with laterally disposed rollers resting on track rails, which extend in the wafer baking oven close to its side walls, substantially as described hereinbefore with reference to or as shown on the accompanying drawing.

9. A wafer baking oven prodived with apparatus according to any of claims 1 to 8.