DE3726802A1 - Method of heat treatment of metal workpieces as well as device for implementing the method - Google Patents

Abstract

An industrial furnace contains at least one heatable furnace chamber which is filled with a treatment atmosphere and has at least one opening via which, when the door is open, charges comprising one or more workpieces are to be introduced into the furnace chamber. Situated in the furnace chamber between the openings for introducing and removing the charges is a transport path, along which the charges can be moved by means of a transport arrangement. In order to make possible different dwell times of the charges in the furnace chamber, at least one storage place for a charge is arranged next to the one transport path in the furnace chamber. By means of a transverse conveying arrangement assigned to this storage place, a charge can be transported from its transport path onto the storage place and back.

Description

The invention is based on a method for heating treat metallic workpieces in a little industrial furnace containing at least one furnace chamber, especially for carburizing, according to the characteristics len the preamble of claim 1. Also be the invention meets a device for performing tion of the method according to the preamble of claim ches 6.

To work simultaneously in an industrial furnace pieces to treat, the different treatment time required, it is from DE-PS 35 06 131 known to use a rotary hearth furnace, and diejeni workpieces that require the same treatment time, to assemble into batches. These batches will be one after the other in the order in which they arrive abandoned the rotary hearth of the rotary hearth furnace and lead in the oven chamber until their respective Treatment time is reached. If this condition for a corresponding batch, the Rotary hearth set in motion until the corresponding one Batch appears in front of the removal opening. After this The batch then opens the removal opening removed from the oven chamber, causing on the spin a free parking space is created, which is replaced by a other new batch can be taken. To this  The purpose of the rotary hearth continues or in the opposite set direction until the free parking space in front the loading opening is.

The order of removal of each workpiece batch is independent of the order of their on and depends only on how long each one Batch to be treated in the oven. The rotary hearth furnace makes it very easy to choose free access to individual batches, which is why is easily possible, almost the same at all times to treat a wide variety of workpieces in good time, as long as they require the same furnace atmosphere and differ only in the duration of treatment. Ins This well-known is particularly suitable for small series Furnace and the procedure to be carried out with it. Since the Throughput through the rotary hearth furnace etc. from its opening capacity depends on the known This arrangement is necessary for large series, because the rotary hearth ovens are only up to a limited size of some to operate economically. Larger rotary hearth furnaces take up an unreasonable amount of space and are in the manufacturing costs disproportionately expensive. The Known methods are therefore suitable for large ones only with significant restrictions. About that In addition, rotary hearth furnaces are difficult if successive process phases in heat treatment workpieces must be linked together. The facilities for removing the batches compared to, for example, a continuous or a push-through furnace, relatively expensive.

Based on this, it is an object of the invention to Process for heat treatment of metallic work to create pieces that take up little space high throughputs for the apparatuses of batches to be treated equally, while at the same time also batches in the same system softening treatment time can be heat-treated can. It is also an object of the invention to Specify device for performing the method.

According to the invention, this object is achieved by the method with the features of claim 1 or with the help the device with the features of claim 6 solved.

Because within the furnace chamber such batches, the one require longer treatment time from the stream of through the furnace continuously or quasi continuously Lich batches passing through are affected such batches do not affect the lead time of the other batches. In addition, the need is unnecessary on all Char in the oven chamber to have random access, which is why together with the equipment required within the furnace can be kept ring. In particular it is deswe not necessary that the transport track in a closed loop is designed so that each any batch can be removed. The batches rather, with the shortest treatment time, similar to a continuous or pusher furnace, one after the other through the furnace chamber and only the batches with the longer treatment time who the inside of the furnace, to be right  in time before the end of the treatment period to be deferred. Because of the usual long treatment times can easily flow in the flow Batch free spaces are generated by the fact that Advance the chain or batch of batches the space that becomes free in the loading opening is occupied, but only on the next but one free a batch is entered again. The empty space then moves in the rhythm of the batches movement up to that, originally from the stream removed batch in order to then be removed from the taken batch to be taken. This wanders then gradually along with the other batches to the removal opening in order to be removed from there when the individual treatment time has expired fen is.

Reinstalling one inside the oven chamber decommissioned batch can be more conveniently timed Correlation also happen because this batch occupies a free space in the stream, released another batch to be decommissioned Has.

In the simplest case, the method according to the invention with any type of linearly educated industry furnace, such as continuous, push-through or roller hearth furnace u. Like. Are executed, only next to the Transport path at least one, preferably a lot number of memory locations is provided. Anyone Storage locations is a cross conveyor arranges to select batches from the conveyor to create the storage space and back. Before the number of memory locations corresponds approximately to the number number of batch locations on the transport track, so  a batch from the electricity at any point can be removed in a storage space beforehand set the storage space is empty.

The relationship becomes particularly simple and flexible se when the industrial furnace has two Trans port lanes, one of which is completely shut down is and the storage in the shutdown state places created. The batches migrate from the active transport track on the shutdown transport train and in good time before the end of your treatment time back on the active transport track. Other on the one hand, it is with such an industrial furnace possible batches on both transport lanes treat each other simultaneously of the same kind, whereby however, both transport lanes on different Clock speeds can be set. Here through two simultaneous large series in the furnace be treated. Since the oven is straight or in white is essentially straightforward, at least none The loop created for the transport path is Space utilization much better than with a shoot stove with comparable throughput.

The flexibility can be achieved with a slight increase The parking space requirement is further enhanced by the introduction a third, to the other two transport increase the parallel transport path. in the Case of operation of the batch treatment furnace with very different treatment times middle transport track in the stopped state as Storage for the batches with longer dwell times. This middle path can easily be done by either lanes arranged to the side of it can be reached.  The transport and positioning of the batches in within the furnace chamber or in front of the cross conveyor is particularly easy if your further trans port within the oven chamber using clock rods takes place through which the equidistant distribution batches along the transport path in a simple manner Way is inevitably achieved. At the end of the job The strokes of the baton stand the batches reliably in the right position.

Except the use of industrial furnaces with quiescent Stove also come with a movable stove, for example wise with a roller hearth, in question. Such an approach Ordering is an advantage when the free space is in the stream of batches that are generated immediately That is supposed to be done by simply starting all those batches first are not transported for a cycle, which is between the loading opening and the Storage space to be emptied. There move all other batches one place, ent there is an empty space immediately in front of the storage space, into which the paused batch can be inserted. In the next cycle, the entire current runs again batches one place further. So that the short batches not moved in the long term do not heat for too long Experience treatment, you need in an appropriate temporal grid can be entered, which without white teres by means of a process control, which also the Space management and control within the furnace takes over, can be realized.

The cross conveyor is in the case of a Rol lenherdes in the simplest case from between difference Lichen adjacent roles raised and lowered Neten lifting elements, which he batches from below  grab and lift off the rollers to get them sideways from the movement path of the passing batches bring out. The lifting elements are located at for example in the form of walking beams, on swivel bar-supported struts, two of which are each together with the walking beam of a parallelogram form leadership. When swiveling this parallelo the required movement is inevitable of the batches. The lifting links can also be opened Lift trucks can be moved parallel to the rollers. In the new device can be used to carry out the new process the furnace chamber both a straight the as well as an appropriately angled course to have.

In the drawing are exemplary embodiments of the counter state of the invention. Show it:

Fig. 1 an industrial kiln according to the invention in a longitudinal section along the line II of Fig. 2,

Fig. 2 cut the industrial furnace according to Fig. 1 in a cross along the line II-II of FIG. 1,

Fig. 3 shows the industrial furnace according to Fig. 1 in a Horizon talschnitt along the line III-III of FIG. 1, illustrating the different operating mode with batches treatment duration,

Fig. 4 shows the industrial furnace according to Fig. 1 in a depicting lung corresponding to FIG. 3 in the operating mode with two streams of batches, the same within each treatment period current aufwei sen,

Fig. 5 is a industry furnace according to the invention with three adjacently disposed conveying paths in a representation corresponding to Fig. 2,

Fig. 6 shows the industrial furnace according to Fig. 5 in a Horizon talschnitt along the line VI-VI of Fig. 5,

Fig. 7 shows a section of a further industrial oven according to the invention with two stacked roller hearths in a longitudinal section and

Fig. 8 the industrial furnace according to Fig. 7 in a cross section along the line VIII-VIII of FIG. 7.

In FIGS. 1 through 4 as a pusher furnace ausgebil deterministic industrial furnace 1 is shown, having a heatable and with a corresponding furnace gas to be filled oven chamber 2, which has an elongated, rectangular in cross section or square shape. At the front of the straight or stretched furnace chamber 2 there are a loading opening 3 and a removal opening 4 , both of which can be sealed gas-tight by lifting doors 5 and 6 . The lifting doors 5 and 6 are lighted by not illustrated, known drives for opening or closing the openings 3 and 4 either to raise or lower.

In front of the loading opening 3 , a loading lock 7 is arranged, which, as shown in FIG. 3, contains side loading openings 8 and 9 . These loading openings 8 and 9 can also be opened or closed by optionally operating doors 11 and 12 . Similarly to the feed lock 7 , the removal opening 4 is followed by a removal lock 13 , which is also provided with two lateral, opposite discharge openings 14 and 15 , which are to be closed by doors 16 and 17 . With the help of the two locks 7 and 13 schematically illustrated batches 18 can be introduced into or removed from the furnace chamber 2 without the hot furnace atmosphere contained in the furnace chamber 2 being able to flow outside through the opened lifting doors 5 and 6 .

The furnace chamber 2 is except for the removal and loading opening 3 and 4 on all sides by refractory and heat-insulating walls, namely the two parallel spaced side walls 19 and 21 and the roof 22 and the floor 23 enclosed.

Above the floor 23 , two transport tracks 24 and 25 run parallel to one another at the same height and pull the furnace chamber 2 over its entire length from the loading opening 3 to the removal opening 4 . Both transport tracks 24 and 25 are constructed identically to each other and each contain two parallel with each other horizontally extending slide rails 26 and 27 or 28 and 29 , which are fixed in the furnace chamber 2 and the surface lying in a common plane, the sliding surface for the batches 18 to be moved thereon. The two adjacent rails 27 and 28 of the two transport tracks 24 and 25 are connected to one another over their entire length, at least in sections, so that in these sections, as illustrated at 31 , there is a continuous flat surface that the two transport tracks 24 and 25th with each other that connects.

In the space between the guide rails 26 to 29 and the top of the bottom 23 , two bars 32 and 33 are longitudinally displaceable by means of rollers 34 , each bar 32 , 33 is assigned to one of the two transport tracks 24 , 25 . Each of the cycle bars 32 , 33 carries a number of transport pawls 35 pivotally connected to the associated cycle bar 32 , 33 , which are distributed equidistantly along the cycle bar 32 , 33 and are at a distance from one another which corresponds to the center distance of the batches 18 along the two conveyor tracks 24 and 25 corresponds. The transport pawls 35 protrude with their upper end through the rails formed between the corresponding guide 26 and 27 or 28 and 29 upwards to come into engagement with this upper end with a rear stop surface of the batches 18 . By means of suitable counterweights, the transport pawls 35 are biased in the direction that their upper end, which comes into engagement with the batches 18, protrudes between the transport rails 26 to 29 , but when the clock rod 32 , 33 is returned to the starting position from the batches 18 can be pressed so that the clock bar 32 , 33 can run back freely without changing the position of the batches 18 . The drive of the bars 32 and 33 is done with the help of two linear drives 36 , which are fastened on an end wall 38 of the loading gate 7 opposite the loading opening 3 . Because of the illustration in FIG. 1, only the linear drive 36 of the clock rod 32 can be seen. The bars 32 and 33 together with the pawls 35 and the Antriebseinrichtun conditions 36 , which give the bars 32 and 33 a reciprocating longitudinal movement, form trans port devices to the batches 18 along the trans port tracks 24 and 25 from the loading opening 3 to to move to the removal opening 4 . The stroke that the clock bars 32 and 33 perform is slightly larger than the pallets or baskets in or on which the workpieces to be heat-treated are arranged, which together form a batch 18 . In this way, by the position of each transport pawl 35 in the most advanced in the direction of the removal opening 4 advanced end position of the rod 32 and 33 , a place for a batch 18 de is defined. It is understood that for this purpose the containers or pallets, in which the workpieces are combined in batches, each have the same base area.

Seen in the direction of transport of the batches 18 , with the exception of the first two places behind the charging opening 3, for each place of a batch 18 Querför dereinrichtung 39 a to 39 g for the transport track 24 and 41 a to 41 g for the transport track 25 are provided. These cross conveyor devices 39 and 41 are designed as cross bumpers, equally distributed among themselves and distributed equidistantly along the furnace chamber 2 . It is therefore sufficient to write the cross conveyor 41 a be. This includes a mounted on one on the outside of the side wall 19 of bracket 42 mounted gear housing 43, which is located at a distance from the outside of the side wall 19th From the gear housing 43 , a tube 44 leads to the side wall 19, in which an extension 45 of the tube 44 is provided. In the tube 44 is a longitudinally displaceably mounted, for example as a rack made of thrust member 46 which carries on its end projecting into the furnace chamber 2 a push member 47 . The drive of the pushing member 46 is done by means of a gear transmission included in the transmission case 43, which rotatably optionally le by means of a clutch 48 with a Antriebswel 49 to be coupled, which by all Getriebegehäu se 43 of the cross conveyors 41 a g to 41 passes. The drive shaft 49 is rotated by a gear motor 51 if necessary.

The transverse conveyor devices 39 are actuated by means of a drive shaft 52 and an associated geared motor 53 .

More cross bumpers 54 and 55 is located on the end wall 38 of the feed lock 7 and serve to promote contained in the feed lock 7 Char gen 18 in the furnace chamber 2 . This cross bumpers 54 and 55 are formed in a known manner and therefore do not need to be described here.

In order to move the finished batches completely out of the furnace chamber 2 into the removal lock 13 , a transverse puller 56 is provided, which is also designed in a known form and is therefore not described in more detail here.

The heating of the furnace chamber 2 is done by electrically or fossil-fueled jet pipes 57 , which are arranged at a corresponding distance above the two transport tracks 24 and 25 in the furnace chamber 2 , namely that they are inserted through an associated opening through the side wall 19 and in the opposite side wall 21 supports.

If batches 18 with the same parameters are to be treated with the industrial furnace 1 described so far, the mode of operation takes place as is illustrated in a highly schematic manner in FIG. 4. It is assumed that the batches 18 require a treatment time of 180 minutes, so that with a capacity of nine parking spaces per transport path 24 , 25, the cycle time of each cycle bar 32 , 33 is to be set to 20 minutes. The two clock bars 32 , 33 then carry out a working stroke every 20 minutes, as a result of which the batches 18 can be advanced to the next place in the direction of the removal opening 4 . As a result of the nine possible positions within the range shown industrial furnace 2, thus a Verweilheit within the furnace chamber 2 for a total of 180 minutes.

Assuming for the moment, the furnace is state in the operation and empty, the two doors 11 and 12 are opened, and it will from the side not-illustrated with the aid of devices, the batches 18 a and 18 b in the load lock 7 is performed. After closing the doors 11 and 12 and the same in the atmosphere in the lock chamber 7 to the atmosphere in the furnace chamber 2 , a central control device 59 causes the lifting door 5 to open. By starting the two transverse bumpers 55 and 54 by the central control 59 , the two batches 18 a and 18 b are pushed through the open feed opening 5 into the furnace chamber 2 onto the first two parking spaces immediately adjacent to the loading opening 3 . The transport pawls 35 of the two bars 32 and 33 are depressed and the batches 18 a and 18 b pushed so far on the guide rails 26 to 29 until the transport pawls 35 are released again behind the batches 18 . In this position, the two batches are labeled 18 c and 18 d . After the 20 minutes have passed, the central control 59 sets the two linear drives 36 in motion for the bars 32 and 33 , causing the batches 18 c and 18 d to move from their position in the immediate vicinity of the loading opening 3 by one parking space be pushed forward towards the removal opening 4 . The transport pawls 35 attack the adjacent rear edge of the batch and press the two batches 18 c and 18 d into the next position. This position is reached at the end of the actuation stroke of the two bars 32 and 33 . The batches are now designated 18 e and 18 f . The bars 32 and 33 are then retracted from the linear drives 36 set in motion in the opposite direction into the starting or rest position, the Transportklin ken 35 freely running back under the batches 18 e and 18 f . Immediately behind the batches 18 e and 18 f , two parking spaces have thereby become available, which after opening the lifting door 5 are occupied by the central control 59 from the loading lock 7 with the help of the cross pusher 54 and 55 by new batches 18 a and 18 b . After insertion of the batches 18 a and 18 b in the oven chamber 2, the central controller 59 causes the closing of the charging opening. 3 As soon as 20 minutes have elapsed again, the central control 59 initiates the next movement stroke of the cycle rods 32 and 33 , which together allows the batches 18 c to 18 f to advance one parking space. Batches 18 e and 18 f thus become batches 18 g and 18 h .

By repeating this interplay several times, the batches 18 are gradually synchronized next to each other through the oven chamber 2 until they finally appear in front of the removal opening 4 , in order to be advanced from the oven chamber into the removal lock 13 at the next cycle of the cycle rod 32 , 33 . The puller 56 there moves the corresponding batches completely into the extraction lock 13 , from which they can finally be removed laterally after closing the lifting door 6 and opening the doors 16 and 17 .

From the description it is clear that the batches 18 a , 18 c , 18 e , 18 g , etc., a stream of batches and the other batches 18 b , 18 d , 18 f , 18 h , etc. through a further stream of batches represent the industrial furnace 1 , which, since the drive and transport devices for the transport tracks 24 and 25 are independent of one another, can also be clocked through the furnace chamber 2 at different speeds. For example, a stream of batches can be moved on the conveyor track 24 , the length of time in the furnace chamber, as explained above, is 180 minutes, while, for example, a stream of batches runs in steps or cycles on the other conveyor track 25 , which has a treatment time of nine hours; the cycle or cycle time of the associated rod 33 is then corresponding to one hour.

In addition to this mode of operation of the industrial furnace 1 with homogeneous streams of batches, mixed operation is also possible, which is schematically explained with reference to FIG. 3. In the case of mixed operation, the one, for example the transport path 25 , is shut down, so that the batches 18 can only advance on the transport path 24 . Accordingly, the loading lock 7 is preferably only fed through the opened door 11 so that the batch 18 a is located directly in front of the active transport path 24 . At the central controller 59 , the cycle or cycle time of the cycle rod 32 is set in mixed operation so that the product of the cycle time and the number of parking spaces in the furnace chamber 2 is equal to the time that the batch with the shortest treatment time in the Oven chamber 2 has to stay. Again, for simplicity, let's assume that this time is 180 minutes. If a batch with, for example, 360 minutes is also to be dealt with in this stream of batches with 180 minutes of treatment time, these are classified in the sequence of their arrival in the stream of batches waiting in front of the loading lock 7 . These batches with twice the treatment time are also fed to the furnace chamber 2 via the feed lock 7 , as described above. You then move every 20 minutes from the loading opening 3 via the position 18 c , the position 18 e to the position which is adjacent to the cross conveyor 39 a . As soon as the batch with the 360-minute treatment time has reached this point, which is the case 40 minutes after entering the furnace chamber 2 , the central controller 57 starts the cross conveyor 39 a by switching on the geared motor 53 and that in the cross conveyor 39 a existing clutch engages. As a result, the associated thrust member 46 a is pushed into the furnace chamber 2 , whereby the thrust member 47 a comes into engagement with the batch 18 g , so that upon further advancement of the thrust member 46 a the batch 18 g from the transport path 24 down onto the transport path 25 is pushed. The batch 18 g now has the position corresponding to the batch 18 h in the operation according to FIG. 4. Since the transport device of the transport path 25 has been set, the batch 18 h remains unchanged in the furnace chamber 2 , while during the next cycle of the cycle rod 32 batch 18 e and finally batch 18 c migrate past batch 18 h . The stream of batches 18 migrating on the transport track 24 contains a gap which the removed batch has left for 18 hours . If in the course of time a further batch appears in the stream, which also has a different treatment time, it can, as soon as it faces a free parking space on the transport path 25 during the gradual advancement on the transport path 24 , by one of the corresponding cross conveyor devices 39 of the Trans portbahn 24 down to the transport track 25 over. This is shown, for example, by the further batches 18 o , 18 g and 18 u in FIG. 3.

As can be seen in the mixed operation according to FIG. 3, the transport track 25 serves as a storage track for batches 18 that have a dwell time that is above the throughput time of the batches on the active transport track 24 .

Corresponding to the mixing ratio of batches of different treatment times, gaps occur in the stream of batches 18 on the active transport track 24 at more or less large intervals, which leave batches which are transferred from the active transport port track 24 to the transport track 25 serving as storage .

In good time before the end of the respective individual dwell time of the batches on the paused transport path 25 , the individual batches 18 located there are again placed in the stream of batches on the active transport path 24 . In the case of a batch of 18 hours , this must be done 140 minutes before the end of the dwell time in the selected numerical example. If, in this case, the batch does not coincide with the batch 18 h anyway, there is a gap in the stream of batches on the transport path 24 , this gap can be created in that no batch is transferred from the feed lock 7 into the furnace chamber 2 beforehand, corresponding to two cycles of the cycle rod 32 becomes. Two bars later or in the selected numerical example 40 minutes later, the resulting gap between adjacent batches will be 18 hours compared to the batch. The central controller 59 then sets the Ge geared motor 51 in gear and engages the clutch 48 so that the associated thrust member 46 a of the cross conveyor 41 a is advanced to the batch 18 h back into the stream of the 24 moving on the transport batches 18 to bring. Since the batch 18 h , which was brought back in the area of the cross conveyor 41 a in the migrating stream of batches, it still needs another 120 minutes to finally exit through the removal opening 4 from the furnace chamber 2 , thus reaching a total of 360 minutes has been.

A gap in the flow of batches 18 on the transport port 24 , which arises, for example, when the batch is parked for 18 hours , can also be used with a favorable time correlation to resume one of the batches 18 o , 18 q or 18 u , if the temporal correlation is corresponding.

Overall, in the system described, as many batches can be processed at the same time with a longer dwell time than the shut down parallel transport path 25 can accommodate at the same time or how cross conveyors 39 and 41 are present.

The embodiment of the industrial furnace according to FIGS. 5 and 6 differs from the previously described be characterized in that in addition to the conveyor track 25 , a further third conveyor track 58 is provided. This is mirror-symmetrical to the transport track 24 builds up. Therefore, their structure need not be explained in detail; the description for the Trans portbahn 24 applies mutatis mutandis. In such an arrangement, three different streams of equal batches 18 are to be treated simultaneously in the industrial furnace 1 . In the case of a mixed operation, the trans port lanes 24 and the transport lanes 58 remain active, while the middle one, between these two run the transport lane 25 , is stopped. that is, in the case when 18 batches are added to the two streams of batches carried over the transport tracks 24 and 58 , which have a residence time which deviates upwards.

So that the batches can now be conveyed back from the now middle conveyor track 25 to both the conveyor track 24 and the conveyor track 58 , the cross conveyor devices 39 and 41 are not designed as simple cross bumpers, but as combined cross bumpers and have a transport pawl 60 which is alternatively reversible in order to advance the batches 18 from the outer two transport tracks 24 and 58 onto the middle transport track 24 or to pull them back down onto the transport track 24 and 58 from the middle transport track. In this case, the guide rails of the transport tracks are interrupted in the transverse direction in order to allow the passage of the transport pawls 59 .

The mixed operation of the plant according to FIG. 5 is illustrated schematically in FIG. 6, from which it can be seen how batches 18 can optionally be transported from the two transport tracks 24 and 58 to the transport track 25 or back. Since the same components are used as in the previous embodiment example, there is no need for a new description and, where necessary, the same reference numerals are used.

FIGS. 7 and 8 illustrate an industrial furnace, which is designed to contrast with the previous Ausführungsbei not play as a pusher furnace, but hearth furnace as rollers, are disposed at the two rolling herd above the other.

In the furnace chamber 2 , rollers 61 are mounted in the side walls 19 and 21 so as to be rotatable about axes parallel to one another in an upper plane. The rollers 61 are driven synchronously with one another step by step, so that a cyclical movement of the batches 180 resting on them takes place. The width of the rolls is such that two streams of batches 180 can run through the furnace chamber 2 side by side at the same time.

Below the roller hearth formed by the rollers 61 there is another roller hearth, formed by rollers 62 , which are also arranged in one plane and are rotatably mounted in the side walls 19 and 21 about axes parallel to one another. The bearings of the rollers 62 are schematically indicated at 63 and 64 . The synchronous drive of the rollers 62 is done via continuous drive links running through on both sides, such as roller link chains 65 and 66 , which run over sprockets or pulleys 67 or 68 connected in a rotationally fixed manner to the rollers 62 . The Rol len 62 of the lower roller hearth are cyclically driven, with each start of the rollers 62, the batches 18 resting on them are transported further by a place in the direction of the removal opening.

In this way, with the industrial furnace 1 according to FIGS. 7 and 8, four streams of batches 18 and 180 can be treated at the same time, the two streams on the upper roller hearth and the two streams on the lower roller hearth differing dwell times or transport speeds can have.

To the roller kiln according to FIGS. 7 and 8 take the mixed operation described before forth, which permits the sprinkling in batches with large machining-up time, 18 lifting devices 71 are arranged under the space formed by the rollers 62 roller hearth at each parking space of a batch . These lifting devices 71 have three parallel lifting beams 72 , 73 and 74 , which are attached to a common base plate 75 . The base plate 75 of each lifting device 71 is on two visible in Fig. 8 pairs of support struts 76 and 77 , which are mounted on the one hand with the base plate 75 and on the other hand pivoted on the top of the bottom 23 . All axes of the support struts 76 and 77 run at right angles to the axis of rotation of the rollers 62 , so that overall there is a parallelogram guide on each side of the base plate 75 , which can be seen in its Seitenan view in FIG. 8. Overall, each base plate 75 is supported by two support struts 76 and two support struts 77 , one pair of which faces the removal opening and the other pair of the loading opening. The pivoting of the support struts 76 and 77 is done with the help of linear drive devices, for example fluid cylinders 78 , which are flanged on the side wall 21 outside and the piston rod 79 through a corre sponding opening in the side wall 21 into the oven chamber 2 , where it projects with the adjacent support strut 76 are articulated at 81.

In mixed operation of the roller hearth furnace 1 , the right area of the roller hearth formed by the rollers 62 is left free and not loaded with continuous batches 18 , based on FIG. 8. As long as there are no batches in the stream of batches j 8 traveling over the left side of the rollers 62 which require a longer residence time in the furnace chamber 2 , all the lifting devices 71 are in the position drawn in full lines and shown in FIG. 8, in which the upper edges of the lifting beams 72 , 73 and 74 are set back from that plane which form the outer peripheral surfaces of the rollers 62 . Once device via a respective hub 71, a charge 18 is received, which has a longer residence time, activates the corresponding lifting device 71 from the central controller 59, the drive cylinder 78 that is in motion ge sets and the corresponding lifting device 71 in the in Fig. 8 dashed lines indicated position brought. Here, the pairs of support struts 76 and 77 around their bottom bearings clockwise a bit around, whereby on the one hand, the walking beams 72 , 73 and 74 from below between the corresponding adjacent Rol len 62 surface to the corresponding batch 18th to take from below. Simultaneously with this upward movement, there is a lateral pivoting movement in the direction of the side wall 19 , so that in the other end position of the pairs of support struts 76 and 77 of the corresponding lifting device 71, the raised batch 18 from the position 18 'to the position 18 '' is transferred. The batch is thus out of engagement with the rollers 62 and outside of the stream of batches 18 running over the left side of the rollers 62 . In the position 18 '', the batch can be held according to the desired dwell time, without impeding the flow of batches 18 passing through the rollers 62 on the left side. When the dwell time for the batch 18 'located in the position 18 ', the batch 18 , as before the batch 18 , is returned to the current flowing through on the left side of the rollers 62 in order to pass through the furnace chamber 2 together with these batches 18 . and to be transported out of it.

If the rollers 62 are not, as explained, driven by common continuous drive means, but individually in groups, there is the possibility of queuing a paused batch 18 , as shown at 18 '' , to generate the necessary gap in that the before the batch 18 '' batches 18 stopped and only the remaining batches are transported in the direction of the removal opening.

Claims (22)

1. A method for the heat treatment of metallic Werkstüc ken in an industrial furnace containing at least one furnace chamber, in particular for carburizing, annealing and. Like., In which the workpieces are introduced in batches in the industrial furnace, in which they each stay until their respective treatment time is reached before they are removed from the industrial furnace, regardless of the order of their input, the one or more workpieces comprising batches are transported within the industrial furnace from an input opening of the industrial furnace to an output opening of the industrial furnace, characterized in that the batches with the shortest dwell time form a current or a sequence of batches passing through the industrial furnace , the speed of which is selected according to the dwell time of the batches with the shortest dwell time, while the batches with a longer dwell time within the industrial furnace are removed from the stream or sequence and reinserted into the stream or sequence towards the end of their dwell time, such that that the sum of their dwell times in the stream and outside the stream results in their respectively defined treatment time. 2. The method according to claim 1, characterized in that that the Char continuous or quasi-continuous or be moved in cycles. 3. The method according to claim 1, characterized in that to reinsert a batch into the stream or the result there is a corresponding empty space is created in that when the first place after the entry opening in the direction of transport, this place does not go through a new batch is filled in such a way that the thus created empty space itself with the current or to the location of the batch removed moving at the speed of the current, and that as soon as the empty space at the respective ent received batch has arrived, the batch on the empty space in the stream or the episode back is put to with the current or consequence to be transported to the dispensing opening. 4. The method according to claim 1, characterized in that a respective batch in an empty space in the current or the sequence is put back, which is the result of another batch was taken from the stream or sequence. 5. Industrial furnace for carrying out the method according to one or more of the preceding claims, with at least one heatable furnace chamber filled with a treatment atmosphere, which has at least one loading and at least one removal opening, which can be closed or opened by optionally operated doors, and through which the batches, each comprising one or more workpieces, are to be introduced into or removed from the furnace chamber, with at least one conveyor path which is located in the furnace chamber and extends between the loading and removal opening and which is associated with a transport device through which the batches can be moved along the transport path, characterized in that at least one storage space for a batch ( 18 ) is arranged in the furnace chamber ( 2 ) in addition to the transport path ( 24 , 58 , 62 ), and in that a transverse conveyor device ( 39 , 41 , 71 ) is provided, by means of which egg ne batch ( 18 ) from the transport track ( 24 , 58 , 62 ) to the storage space and back can be transported. 6. Industrial furnace according to claim 5, characterized in that along the transport path ( 24 , 58 , 62 ) and in addition to this a plurality of storage locations ( 25 , 62 ) for batches ( 18 ) are available, and that each storage location ( 25 , 62 ) a cross conveyor ( 39 , 41 , 71 ) is assigned. 7. Industrial furnace according to claim 6, characterized in that the number of storage locations corresponds to the maximum number of batches ( 18 ) located on the transport path ( 24 , 58 , 62 ). 8. Industrial furnace according to claim 5, characterized in that in the furnace chamber ( 2 ) in addition to the first trans port track ( 24 , 62 ), a second with constant from running conveyor track ( 25 , 62 ) is arranged, which forms the storage spaces and whose associated transport device ( 32 , 33 , 36 ) can optionally be stopped if the second transport track ( 25 , 62 ) is used to store the batches ( 18 ) with the longer treatment time, and which is in operation when the first ( 24 ) and the second transport path ( 25 , 62 ) batches ( 18 ) with the same treatment time, based on their respective transport path ( 24 , 25 , 62 ), are transported through the furnace chamber ( 2 ). 9. Industrial furnace according to claim 8, characterized in that in addition to the second transport path ( 25 ) a third transport path ( 58 ) with associated Transportein direction is arranged, from which by means of the transverse conveyors ( 39 , 41 ) batches ( 18 ) on free places the second transport path ( 25 ) and back or on the first transport path ( 24 ) and back. 10. Industrial furnace according to one or more of the preceding claims, characterized in that the first and the second or the first, the second and the third transport path ( 24 , 25 , 58 ) are identical to one another. 11. Industrial furnace according to one or more of the preceding claims, characterized in that each of the transport tracks ( 24 , 25 , 58 ) parallel to each other and a substantially horizontal transport plane defining rails ( 26 , 27 , 28 , 29 ), on the top run along the batches ( 18 ). 12. An industrial furnace according to one or more of the preceding claims, characterized in that the transport device (32, 33, 36) of each conveyor track (24, 25, 58) at least extending in the conveying direction stroke rod (32, 33) which are longitudinally displaceably stored and brought by a respective associated drive means ( 36 ) in a reciprocating movement that the movement stroke of each cycle bar ( 32 , 33 ) the transport stroke of the batches ( 18 ) from a place on the transport path ( 24 , 25 , 58th ) corresponds to the next place, and that the cycle bar ( 32 , 33 ) has movable transport pawls ( 35 ) which positively engage the batches ( 18 ) during the working stroke of the cycle bar ( 32 , 33 ) and during the empty or return stroke of the Free running the rod ( 32 , 33 ) opposite the batches ( 18 ). 13. Industrial furnace according to claim 5, characterized in that the transport path is formed by a plurality of horizontally spaced apart and side by side as substantially axially parallel rollers ( 62 ) which are rotatably mounted about a horizontal axis and on the outer circumferential surfaces Batches ( 18 ) preferably run along in cycles. 14. Industrial furnace according to claim 13, characterized in that each cross conveyor ( 71 ) each has at least two lifting members ( 72 , 73 , 74 ) located between different adjacent rollers ( 62 ), which are arranged on means ( 76 , 77 ), through which they can be moved up and down between the rollers ( 62 ) and axially parallel to the rollers ( 62 ). 15. Industrial furnace according to claim 13, characterized in that the rollers ( 62 ) drive devices ( 65 , 66 ) are assigned, through which the rollers ( 62 ) for moving the batches ( 18 ) are either in revolutions or shutdown. 16. Industrial furnace according to claim 13, characterized in that the length of the rollers ( 62 ) is greater than twice the width of the batches ( 18 ). 17. Industrial furnace according to claim 14, characterized in that the lifting members are walking beams ( 72 , 73 , 74 ). 18. Industrial furnace according to claim 14, characterized in that the means for supporting the lifting members ( 72 , 73 , 74 ) parallelogram guides each with at least two, preferably four parallel to each other pivotable support members ( 76 , 77 ), which to the Axles of the rollers ( 62 ) axes are pivotally mounted below the rollers ( 62 ) and are each connected to one another by a cross strut ( 75 ). 19. Industrial furnace according to claim 18, characterized in that the cross strut is a respective lifting beam ( 72 , 73 , 74 ) or the base plate common to the lifting beam ( 75 ). 20. Industrial furnace according to claim 18, characterized in that with one of the support members ( 76 , 77 ) an associated drive device ( 78 ) is coupled in a gearbox. 21. Industrial furnace according to claim 5, characterized in that the furnace chamber ( 2 ) has a straight course. 22. Industrial furnace according to claim 5, characterized in that in front of the loading opening ( 3 ) and after the removal opening ( 4 ) in each case a lock chamber ( 7 , 13 ) is connected.