DE2757864A1 - PROCEDURE FOR ADJUSTING THE DURATION OF A GOOD IN A PUSH FURNACE - Google Patents

Description

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ALKEM GmbH 2 My reference Hanau VPA 77 P 8543 BRD

Method for setting the length of time a product remains in a pusher furnace

The present invention relates to a method for precisely maintaining the dwell time of an item to be heated, in particular of nuclear fuel pellets to be sintered in a pusher furnace. Push-through ovens are generally tunnel ovens, in which the material to be treated is preferably stored on transport boats by the new transport to be added chi ff is pushed into the oven and moved through it. The drive device is always located outside the oven. There are no moving ones in the furnace itself Parts. Such furnaces are preferred for high temperature treatment of workpieces, e.g. for sintering ceramic material, such as nuclear fuel tablets, used. The dwell time of the goods to be treated depends on the feed speed of the drive system, that e.g. on pneumatic, hydraulic or electrical Principle can be built. The frictional forces of the transport boats inside the furnace can increase speed Changes in the drive result, which ultimately result in differences in the length of time the goods remain inside the furnace, especially in the Hot zone of the same, cause and thus for quality differences of the good can be responsible.

Mü 2 Ant / December 19, 1977

9 & 9826/0377

ORIGINAL INSPECTED

-Z- VPA 77 P 8543 BRD

The task was therefore to create a system that was as simple as possible To find a method for maintaining the retention time of the goods in such an oven, with the least possible effort of control engineering effort.

This object was achieved in that a discontinuous transport of the furnace material is provided, for the control of which the feed of the material is provided at a higher feed rate than necessary for a continuous run, switched on at pre-selected, exact time intervals λt and after the run a preselected distance a - is switched off again before the expiry of the current time cycle At-. Its real Control of the speed is therefore not carried out.

To further illustrate this method, reference is made to the accompanying figure, in which, in addition to an example shy illustration of a continuous furnace the associated one Travel time diagram of the goods in transit is shown 1st. Of the Furnace is designated with 1, in its central part lies the sintering zone 3. Its length is divided into individual, similar distances a, see also the ordinate of the diagram, which is denoted by s. The item to be treated in the oven is 2 stacked on boats that are pushed into the oven by a drive (not shown) and that already in it Push the goods in front of you. The goods to be inserted, which can have different linear expansion, are with Markings 4 provided, which are attached at intervals a from each other will. In the entrance area of the furnace, the triggers 5 and 6 are again at a distance a or a multiple away from each other by a.

9,99826 / 0377

- -? * - VPA 77 P 8543 BRD

The time t is plotted on the abscissa of the diagram, in individual steps ^ t. At the beginning of a new λ t section, a timer, in a manner not shown, issues a switch-on command to the drive device, not shown, for the furnace.

To set the exact dwell time of the goods to be treated within the furnace, it would theoretically suffice to use to travel at a constant speed, which is represented by the line VO. By unavoidable frictional forces or However, such a course cannot be maintained either for other disturbances, so that the actual length of stay is always could be longer.

According to this invention, the drive speed is therefore selected from the outset to be greater than VO. Let it be V1, for example, so that the ^{distance a assigned to the time cycle Δ} t has already been reached before this time cycle has elapsed. This is reported via the triggers 5 and 6, which shut down the drive. At the beginning of the new cycle, the timer gives an impulse and thus switches the drive device on again, which pushes the material to be treated further forward. Here, for example, a speed V2 is established, so that the second path section a will probably be reached a little later, but still within the time cycle Ät.

Again, the triggers 5 and 6 stop the Drive and then switch on again via the clock generator, after which a speed V3 may result, etc. From this diagram it can be seen that the specified path sections a always in a shorter time than the time cycle Δι accordingly are run through and thus always shorter or longer downtimes of the goods to be moved occur. However, since the individual speed curves V1-V8 always run steeper than those of the ideal speed VO, will thereby an exact adherence to the dwell time of the goods to be treated in the oven is achieved with the simplest means.

9,99826 / 0377

VPA 77 P 8543 BRD

The interaction of markings 4 on the item to be moved and on the triggers 5 and 6 can be mechanical, ie e.g. via knobs and limit switches or optically, e.g. via light barriers or inductively or capacitively. These Mechanisms are generally known, so that a more detailed description of them can be omitted here. What kind of Markings and triggers are used ultimately depends on the type of goods to be moved, possibly under certain circumstances the markings on the goods themselves can be dispensed with if transport boats of the same length are always used. In In this case, it is then advisable to adapt the preselected distance a to the length of the transport boat. The triggers can then, for example, be designed as a feeler lever of limit switches and built into the fixed slide of the transport boat be.

This type of control of the dwell time of the transport boat of the transported goods within a pusher oven there is also the possibility that manually in the sequence of movements action is taken, if, for example, in the case of the clock signal that switches on the movement, the feed movement is caused by the Triggers 5 and 6 had not yet been switched off, which means that the advanced path a is still in the relevant time cycle could not be covered, so obviously larger obstacles were responsible for these irregularities An alarm signal then causes the operating personnel to determine the fault and, if possible, through direct intervention to eliminate in the feed mechanism.

This method thus not only makes it possible, in the simplest possible way, to adhere to the exact dwell times of the goods and thus to precisely guarantee their uniform quality, but also to automatically report any disruptive irregularities in operation.
3 claims
1 figure

9 & 9826/0377

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Claims (3)

-JST- VPA 77 P 8543 BRD claims 9 7 ζ 7 8 R Λ 1. Procedure for the exact adherence to the length of stay of a Goods to be heated, in particular of nuclear fuel to be sintered tablets, characterized in that a discontinuous transport of the oven goods is provided is to control the feed of the goods at a higher feed rate V1 - V8 than for continuous Run (VO) necessary at pre-selected, exact time intervals Δΐ switched on and switched off again after running a preselected distance a - before the expiry of the current time cycle ^ t- will. 2. The method according to claim 1, characterized in that the furnace material (2) before its entry into the furnace (1) at a distance the preselected route a is provided with markings (4), the respective arrival of which in the case of fixedly installed triggers (5 and 6) switching off the movement of the goods and the following sequence of the controlled by any timer Time cycle at a w ed he start of the movement of the Causes good. 3. Device for performing the method according to claims 1 and 2, characterized in that the markings (4) and the triggers (5 and 6) interact mechanically, optically, inductively, capacitively. 9θ 9826/0377 ORIGINAL INSPECTED