DE102009004089B3 - Method and device for treating workpieces - Google Patents

Abstract

The invention relates to a method for treating workpieces, in which the workpieces to be treated are heated in a furnace in several horizontal oven levels (E ₁ ... E _n ). Each of the vertically stacked oven levels (E ₁ ... E _n ) is in each case at a height (h ₁ ... h _n ) and can accommodate at least one workpiece to be heated. After heating, the workpieces are removed from the oven levels (E ₁ ... E _n ) in a defined sequence. For the removal of the heated workpieces, the oven levels (E ₁ ... E _n ) are moved stepwise vertically, thereby changing the respective heights (h ₁ ... h _n ) of the individual oven levels (E ₁ ... E _n ). The stepwise vertical movement takes place in such a way that the height (h ₁ ... H _n ) of the respective furnace plane (E ₁ ... E _n ), from which at least one heated workpiece is removed, corresponds to a defined removal height h _x and the respective furnace level (E ₁ ... E _n ) is at the extraction height h _x for a time t> 0.

Description

The The invention relates to a method for treating workpieces, in the workpieces in heated in a furnace in several horizontal oven levels, the oven levels are vertically stacked are arranged and each oven level each in a particular Height is located. In this case, each furnace level is designed to accommodate at least one workpiece, and the workpieces become after heating taken in a defined order from the oven levels.

The The invention further relates to a device or a furnace for carrying out this Process.

The important goals of the automotive industry today and in the future include the reduction of fuel consumption, the reduction of CO ₂ emissions and the increase in occupant safety. A common means of reducing fuel consumption and thus reducing CO ₂ emissions is, for example, the reduction of vehicle weight. However, at the same time to achieve an increase in occupant safety, the body panels used must have higher strength at a lower weight.

It There is therefore an increasing interest in bodywork steels a cheap one relationship from strength to weight. This is usually done through the process of the so-called press hardening or also form hardening reached. In this case, a sheet metal part is heated to about 800 ° C to 1000 ° C and then in a chilled Tool deformed and quenched. The strength of the component decreases thereby up to about threefold. The press hardening allows the Building lighter yet stiffer body parts through the combination of heat treatment, Shaping and simultaneous controlled cooling.

For the heat treatment the bodywork steels In the past, different furnace concepts have emerged. In particular, the principle of the continuous furnace is widely used in press hardening found. In this furnace principle to be heated Bodywork steels on Workpiece carriers via conveyors through transported the oven. Come as a conveyor Rolls, chains or ribbons used, with conveyors can be provided in several oven levels.

Bring continuous furnaces but usually the Disadvantage with that they have a high due to their length Have space. Therefore, to save space, you can alternatively also ovens with several, horizontally one above the other arranged oven levels are used, which also referred to as floor ovens become. The individual oven levels can be equipped with drawer elements are provided for loading and unloading workpieces horizontally be pulled out of the oven. The loading and unloading of workpieces from the individual arranged one above the other Oven levels are preferably over one in height movable loading and unloading device.

The German patent DE 10 2006 020 781 B3 for example, describes a deck oven for heating steel blanks having a plurality of horizontally stacked oven levels, each for receiving at least one steel plate, each oven level additionally having means for moving the steel blanks during heating. However, these oven levels are only horizontally movable. A vertical movement of the oven levels is not provided.

For the following Transport of the heated ones workpieces from such a deck oven for subsequent shaping is a needed some time. During this time, a cooling of the Workpieces, while these are moved by the ambient air. Due to the height differences The individual oven levels of the bunk oven are different Times for the transport of the individual workpieces. From these different times result in different high temperature losses for the workpieces. These different temperature losses in turn can cause differences in the quality lead to the body parts to be manufactured.

A The object of the invention is therefore to provide a method with its help workpieces, especially body steels, to be heated can, afterwards to press, without it being too big Fluctuations in quality the finished body parts comes.

The Procedure should include both the time of transfer of the heated workpieces from Furnace to the subsequent shaping for each workpiece as possible keep constant, as well as the space required for the oven for heating the Minimize workpieces.

A The object of the invention is also a device for carrying out a to provide such method.

This object is achieved by a method having the features of independent claim 1. Advantageous developments of the method will become apparent from the dependent claims 2 to 9. The object is further by a device according to Claim 10 solved. Advantageous embodiments of this device will become apparent from the subclaims 11 to 18.

The invention comprises a method for treating workpieces, in which the workpieces to be treated are heated in a furnace in a plurality of horizontal furnace planes (E ₁ ... E _n ), which are arranged vertically one above the other. Each furnace level (E ₁ ... E _n ) is in each case at a certain height (h ₁ ... h _n ) and can accommodate at least one workpiece to be heated. After heating, the workpieces are removed from the oven levels (E ₁ ... E _n ) in a defined sequence. For the removal of the heated workpieces, the oven levels (E ₁ ... E _n ) are moved stepwise vertically, thereby changing the respective heights (h ₁ ... h _n ) of the individual oven levels (E ₁ ... E _n ). The stepwise vertical movement takes place in such a way that the height (h ₁ ... H _n ) of the respective furnace plane (E ₁ ... E _n ), from which at least one heated workpiece is removed, corresponds to a defined removal height h _x and the respective furnace level (E ₁ ... E _n ) is at the extraction height h _x for a time t> 0.

In one embodiment of the method, the position of the oven levels (E ₁ ... E _n ) is fixed in relation to the oven, and the oven is incrementally adjusted by means of adjusting means for removing the heated workpieces from the oven levels (E ₁ ... E _n ) moved vertically. In another embodiment of the method, however, the position of the furnace levels (E ₁ ... E _n ) in relation to the furnace is variable, and the furnace levels (E ₁ ... E _n ) are for the removal of the heated workpieces by adjusting means within the Furnace gradually moved vertically. One embodiment of the method uses a lifting system for these two variants as adjusting means, while another embodiment uses a pulling system.

The heated workpieces are removed in a development of the method by means of a transfer device on the removal height h _x from the respective furnace levels (E ₁ ... E _n ). The removal takes place in such a way that the transfer _device picks up the workpieces at the defined removal height h _x and at least partially removes them horizontally. For example, the workpieces are removed horizontally at the defined removal height h _x .

In a further development of the method, after the removal of a heated workpiece from one of the oven levels (E ₁ ... E _n ), a new workpiece to be treated is introduced into the same oven level (E ₁ ... E _n ). In a further embodiment of the method, the workpieces are introduced into drawer elements which are arranged on the individual oven levels. In this case, a drawer element on the removal height h _x horizontally moved out, removed a workpiece and then moved back the drawer element.

The invention further comprises a device for treating workpieces, comprising a furnace with a plurality of horizontal furnace levels (E ₁ ... E _n ), which are arranged vertically one above the other and in which workpieces are heated. Each furnace level (E ₁ ... E _n ) is located at a height (h ₁ ... h _n ) and is designed to receive and remove at least one workpiece. The device has adjusting means for stepwise vertical movement of the oven levels (E ₁ ... E _n ), which are designed such that they correspond to the respective heights (h ₁ ... H _n ) of the individual oven levels (E _{1 n} ) can change. The adjusting means can move the oven levels (E ₁ ... E _n ) stepwise vertically such that the height (h ₁ ... H _n ) of a respective oven level (E ₁ ... E _n ) corresponds to a defined discharge height (h _x ) and that the respective furnace level (E ₁ ... E _n for a period t> 0 can be maintained at the extraction height h _x .

In one embodiment of the device, the position of the oven levels (E ₁ ... E _n ) is fixed with respect to the oven, and the adjusting means are designed so that they can move the oven stepwise vertically. In another embodiment of the device, in turn, the position of the oven levels (E ₁ ... E _n ) is variable relative to the oven, and the adjusting means are arranged so as to define the oven levels (E ₁ ... E _n ) within the oven can move gradually vertically. For both variants, one embodiment comprises a lifting system as adjusting means, while another embodiment comprises a pulling system.

The device according to the invention preferably comprises a transfer device for removing heated workpieces from the oven levels (E ₁ ... E _n ) at the removal height h _x . This transfer device is also designed to charge the oven levels with workpieces to be heated. In this case, the transfer device has means to take the heated workpieces at the defined removal height h _x and remove them at least partially horizontally. For example, the transfer device may have means for transporting workpieces horizontally at the defined removal height h _x .

In a further development of the device, after the removal of a heated workpiece from one of the oven levels (E ₁ ... E _n ), the transfer device can introduce a new workpiece to be heated into the same oven level (E ₁ ... E _n ). In a further embodiment of the device, the oven levels (E ₁ ... E _n ) comprise drawer elements which are provided for receiving workpieces and on the Extraction height h _{x are moved} horizontally.

The described method and the device for treating workpieces have the advantage that workpieces can be heated in a furnace with a reduced space requirement and can always be removed from the oven after heating at the same height. For this purpose, the furnace comprises several furnace levels (E ₁ ... E _n ), which can be changed in their height (h ₁ ... H _n ) and thus adapted to a fixed removal height h _x . The respective height (h ₁ ... H _n ) of the oven levels (E ₁ ... E _n ) is thereby changed such that it corresponds in each case to the removal height h _x , so that workpieces from the oven levels are always removed at the removal height h _x and preferably also be charged. The required stepwise vertical movement of the oven levels (E ₁ ... E _n ) is made possible by the use of adjusting means.

The Invention thus turns away from continuous furnaces, in which the workpieces for Heat be successively moved through an oven. She turns further from height-adjustable removal devices, the at floor ovens to remove the heated workpieces Find use.

One Advantage of the invention over usual Method for preventing variations in the quality of the Production of body components is always the same time for the Transfer of workpieces from the oven for further shaping. A continuous furnace also offers this possibility, However, it has a corresponding length extension and an associated length high space requirement.

Of the reason for this is the construction of a continuous furnace. In this oven principle the to be heated workpieces successively on workpiece carriers via conveyors transported horizontally on a furnace level through the oven. Next other parameters determine both the heating time as well as the number of to be heated Parts the required length of the continuous furnace. The longer It takes until the workpieces the required heating temperature have reached and the more workpieces to be heated, the greater the length extension of the continuous furnace.

These size Linear expansion of the continuous furnace would be compensated by the use of a stack oven. Because with this Oven principle, the individual furnace levels are vertically above each other, is located each workpiece for heating in a different altitude, for removing the heated workpieces of a removal device must be approached. From the different ones Heights of Oven levels results for each oven level another transfer path from the oven to further shaping. The longer the transfer way is, the longer it takes it, however, until the heated workpiece the further shaping is achieved and the greater the temperature loss of the heated Workpiece. Size Temperature losses can too big Fluctuations in quality cause the body components to failure of the parts.

The invention solves this problem advantageously by a height adjustment of the oven levels to a fixed extraction height h _x . Each furnace level is moved to this removal height h _x for removal of the heated workpiece and held there for a time t> 0 so that the transfer path from the furnace to further shaping is the same for each removed workpiece. This results in a comparable temperature loss for each removed workpiece, resulting in reduced variations in the quality of the body components.

The aforementioned and other advantages, special features and expedient developments of Invention will also be apparent from the embodiments which will be described below with reference to the figures.

From the figures shows:

1 a schematic representation of a height-adjustable oven with multiple furnace levels for heating workpieces;

2 a schematic representation of a ball screw drive;

3a a schematic flow diagram representing the sequence in the equipping of a furnace;

3b a schematic flow diagram, which shows the sequence in the repeated assembly and removal of workpieces;

3c a schematic flow diagram representing the process of completion of the heating of workpieces;

4 a schematic representation of various components of a plant for press hardening of workpieces; and

5 a schematic representation of a plant for press hardening workpieces with two ovens.

In 1 is schematically the example of a height-adjustable furnace 101 for heating workpieces, which typically has a Ge housing with an opening for the assembly and removal of the workpieces to be heated. The oven also comprises any number n of horizontal oven levels (E ₁ ... E _n ), on each of which at least one workpiece can be heated. The oven levels (E ₁ ... E _n ) are separated from each other and lie vertically one above the other. This in 1 Example shown shows seven oven levels.

Each of the oven levels (E ₁ ... E _n ) contains at least one receptacle for storage of the workpieces during heating. The design of the images is variable and depends, inter alia, for example, on the shape of the workpieces to be heated. The workpieces are in the receptacles during heating and are removed again after heating. The recordings are, for example, drawers 102 that has a horizontal movement 103 can be retracted and retracted. In 1 is the example of an extended drawer 104 shown in which is a workpiece 105 located. For heating, the drawer is with a workpiece 105 equipped, for heating the workpiece 105 retracted and then extended again.

Since the workpieces are not heated horizontally next to one another but vertically above one another, the size of the base surface of the furnace can be achieved with such an oven principle 101 be minimized. This leads to a reduction in the space required for the oven 101 , Furthermore, with this furnace principle, the size of the surface of the furnace 101 be minimized, which in turn leads to a reduction in energy consumption through reduced surface losses.

The oven 101 also has a lifting system, with which the oven levels (E ₁ ... E _n ) can be moved by an up and down movement. At the in 1 exemplified height adjustable oven 101 is the lifting system on the bottom outside of the oven 101 attached, so that the movement of the furnace levels (E ₁ ... E _n ) by a movement of the entire furnace 101 is implemented. This has the particular advantage that the lifting system is not exposed to the prevailing in the furnace high temperatures T of up to 1000 ° C and thus need not have required for these temperatures temperature resistance. Another advantage is that the housing of the furnace 101 only the oven levels (E ₁ ... E _n ) with all necessary accessories for heating workpieces 105 must enclose. This eliminates the need for extra volume within the oven 101 to heat, which among other things, to optimize the energy needs of the furnace 101 leads.

In another embodiment, however, there is also the possibility of the lifting system used inside the furnace 101 to install and only the oven levels (E ₁ ... E _n ) within the oven 101 to move. This has the advantage that the lifting system is not the weight of the entire furnace 101 but only the weight of the oven levels (E ₁ ... E _n ) must move.

The lifting system is for example Versteilmittel 106 indicating the height of the furnace 101 about a vertical movement 107 can influence. In 2 is an example of an adjustment 106 a ball screw shown. Ball screws are helical gears for converting a rotational movement 201 in a translatory movement 202 , One component of the ball screw is a ball screw 203 that of a motor 204 is driven and the rotational movement 201 performs. The ball screw 203 consists of a ball screw rod 205 in the form of a cylindrical round bar on which a ball screw 206 is applied. On the ball screw spindle 203 there is a non-rotatably mounted spindle nut 207 that the translational movement 202 performs. roll 208 go through a ball circulation 209 for ball return within the spindle nut 207 ,

By means of a ball screw very large forces can be applied. This is especially in view of the high weight of the furnace 101 , which must be moved at a height adjustment, advantage. In addition, the use of a ball screw because of its high mechanical efficiency of> 90% is particularly advantageous for the required cycle times from the assembly to the removal of the workpieces, which are in the range of about 10 seconds. Further advantages of the ball screw are in particular a low wear and associated high durability of the transmission, in a high positioning and repeatability and in high speeds, which can be implemented.

In one embodiment, the spindle nut 207 from a motor 204 driven and thus against the ball screw 203 emotional. This leads the spindle nut 207 the rotational movement 201 out, the non-rotatably mounted ball screw 203 however, the translatory movement 202 , In another embodiment, instead of the ball screw, a roller screw is used, in which instead of the balls 208 Rollers are used, but there are also other adjustment 106 used.

Alternatively, any other suitable devices can be used as traction means. Another embodiment of the invention verwen det for height adjustment of the oven 101 For example, pulleys or chain hoists with lifting chains. In particular at locations with existing installations for traction means can result in corresponding cost savings. To reduce the drive power and thus the energy demand in traction means counterweights can be used, for example.

In another embodiment, shear chains come to adjust the height of the furnace 101 for use. Thrust chains are special chains which, in contrast to the known tension chains, stiffen in the direction of thrust, but remain deflectable via sprockets. The ability to push is made possible by specially shaped chain links, which interlock positively and support each other with little play. Due to the geometry of the link plates, a buckling under pressure due to the weight of the furnace 101 prevented. Push chains thus work like a conventional linear drive as a rigid telescopic drive rods. But they are extremely flexible when it comes to storage. The chains can be redirected to where there is room, and they can be wound up to save space. Advantages of push chains are, in particular, the implementation of uniform jolt-free movements of the oven levels (E ₁ ... E _n ) during height adjustment, holding an absolute position for removing the workpieces 105 as well as a compact storage possibility of the push chains.

The schematic sequence of a process for heating workpieces in a height-adjustable furnace show the 3a - 3c an example. There are 3a the steps in equipping the furnace up to a process point 1 again. Before the start of the process is the oven 101 heated to a defined temperature T, which is usually at 800 ° C to 1000 ° C during press hardening. After reaching the defined temperature T, a lifting system changes the height of the furnace 101 until the height h _{1 of} the furnace level E ₁ corresponds to a defined height h _x , in which the furnace level E ₁ then remains for a time t> 0.

A height h designates the distance of an object point from a reference line or reference surface. The distance between object point and reference line is preferably determined by the direct comparison of the distance to be determined with a scale. In this case, for example, serve as a reference line, the bottom surface on which the furnace is placed, so that the height h _x corresponds to a certain distance from the ground. The variable heights of the oven levels are adjusted to this height h _x by a vertical movement of the oven.

After adjusting the height of the oven 101 becomes the drawer 102 the furnace level E ₁ extended, with a workpiece to be heated 105 equipped and then retracted again. This is followed by another change in the height of the oven 101 by the lifting system, so that thereafter the height h _{2 of} the furnace level E ₂ corresponds to the height h _x , in which then the furnace level E ₂ remains for a period t> 0. After completed height adjustment of the oven 101 becomes the drawer 102 the furnace level E ₂ extended, with a workpiece to be heated 105 equipped and then retracted again. This process is repeated gradually until the drawers 102 All oven levels (E ₁ ... E _n ) are equipped by the oven levels are each moved to the defined height h _x .

The so in the height-adjustable oven 101 introduced workpieces 105 are heated in the oven within a defined residence time to a defined temperature T, which is exemplified for some body steels 860-980 ° C. If at least the first workpiece to be removed has reached the required temperature, the in 3a illustrated process point 1 reached.

Is the heating of the workpieces 105 at the process point 1 completed, follows, as in 3b reproduced, a repeated change in the height of the furnace 101 through the lifting system until the height h _{1 of} the furnace level E ₁ again corresponds to the height h _x , in which the furnace level E ₁ then remains again for a time t> 0. The drawer 102 the furnace level E ₁ is extended and the heated workpiece 105 taken from it. If the whole process is not over yet, the drawer will become 102 again with a workpiece to be heated 105 equipped and then retracted again. This is followed by another change in the height of the oven 101 so that thereafter the height h _{2 of} the furnace level E ₂ corresponds to the height h _x , in which the furnace level E ₂ then remains again for a time t> 0. The drawer 102 the furnace level E ₂ is extended, the heated workpiece 105 taken from it, the drawer 102 with a workpiece to be heated 105 equipped and then retracted again. This process is repeated gradually until the drawers 102 all oven levels (E ₁ ... E _n ) again with workpieces to be heated 105 are fitted, which are then heated within the defined residence time to the defined temperature T.

The process of repetitive heating of workpieces 105 in a height-adjustable oven 101 is ended when the in 3b illustrated process point 2 is reached and after a successful removal no further workpieces 105 for heating in the oven levels E _{n are} introduced. After that, the oven can 101 for example, be cooled. The steps at the The last removal of heated workpieces from the individual oven levels are in 3c shown.

Within the process of heating workpieces 105 In a further development, the possibility exists of the oven levels (E ₁ ... E _n ) in any desired and also varying order with workpieces 105 to equip and / or workpieces 105 refer to. This has the advantage that different workpieces 105 , for example, workpieces 105 can be treated with different thickness, with different residence times in the oven within a process, which is realized by a corresponding control of the furnace.

In one embodiment, it is also possible, all oven levels (E ₁ ... E _n ) with workpieces 105 to load, the workpieces after heating from the oven levels (E ₁ to E _n ) and remove only when all workpieces from the oven levels (E ₁ to E _n ) were removed, the oven levels (E ₁ to E _n ) again to refit. In another embodiment, not all oven levels (E ₁ to E _n ) for heating workpieces 105 used. This is particularly advantageous if only a few parts to be heated. Furthermore, it is possible to remove workpieces from the oven levels (E ₁ to E _n ) even in the event of incidents, even if the oven levels (E ₁ to E _n ) are not at the height h _x . These different embodiments can be realized in a control of the entire arrangement, which is freely programmable.

For the workpieces to be heated 105 These are, in particular, sheet metal parts made of body steel for press-hardened body components in the automotive industry. However, other or non-formed workpieces of other materials may also be heated.

One embodiment provides workpieces 105 to produce with partially different properties, which are particularly advantageous for the aforementioned body parts in the automotive industry. This will be a drawer 102 some time before the actual removal of the workpiece 105 partially moved out, so that the workpiece 105 partially cooled to a temperature below the austenite or hardening temperature and in a subsequent press hardening in the already cooled part does not form a very hard martensite, but a perlite-ferrite structure. This structure has significantly higher strain rates and is less susceptible to breakage in the event of a vehicle crash.

In the in 4 schematically illustrated example is the height-adjustable oven 101 Part of a plant for press hardening of workpieces. A workpiece 105 gets out of the extended drawer after heating 104 an oven level E _{i of} the oven 101 taken at a height h _i = h _x . The removal takes place for example by a transfer device 401 that with at least one gripper 402 is equipped for receiving and storing workpieces. 4 shows an example of a transfer device 402 with four grippers. After removal of the heated workpiece 105 leads the transfer device 402 a movement 403 from the oven 101 to a pressing tool 404 and transfers the workpiece to the pressing tool 404 ,

The pressing process can be carried out by methods and pressing tools that are well known to those skilled in the art. In the pressing tool 404 becomes the workpiece 105 from the transfer device 402 filed, and the transfer device 402 then returns from the pressing tool 404 to the oven 101 back.

A further development provides that the transfer device 401 both for the removal of a workpiece 105 from a furnace level and for further transport to a pressing tool 404 as well as for equipping a furnace level is formed. For this purpose, the transfer device takes 401 on the way from the pressing tool 404 to the oven 101 a workpiece to be heated, it transports to the oven 101 and place it in one of the oven levels.

The height of the pressing tool 404 , based on the floor of his location, for example, is also represented by the height h _x , which is firmly defined and unchangeable. Both for the removal of a heated workpiece 105 from a furnace level E _i as well as for equipping a furnace level E _i with a workpiece to be heated 105 is the height h _{i of} the furnace level E _i to the height h _{x of} the pressing tool 404 customized. The height h _{x of} the pressing tool 404 is thus the determining height for the removal and loading of the oven levels (E ₁ ... E _n ). This has the advantage that the time t from the removal of a heated workpiece 105 from a furnace level E _i until it is deposited in the pressing tool 404 for all oven levels (E ₁ ... E _n ) is comparable and as low as possible. The resulting temperature loss is thus also comparable, which in turn leads to a minimization of fluctuations in the quality of the body components.

5 shows an example of the arrangement of two ovens 101 and 101 ' and a pressing tool 404 , The oven 101 and a comparable oven 101 ' stand in this example so opposite that the associated drawers 102 when extending in each case into the axis of the pressing tool 404 move. During the process, a workpiece becomes in this arrangement 105 after heating off the extended drawer 104 of the oven 101 ' taken and to the pressing tool 404 to hand over. The extended drawer 104 of the oven 101 ' is then re-equipped and retracted. After that, the drawer can 102 of the oven 101 for removing the heated workpiece 105 extended and after the removal and transfer of the heated workpiece to the pressing tool 404 be re-equipped and retracted again. The process of mutual extension of drawers 102 the ovens 101 and 101 ' is repeatable as often as you like.

With this arrangement of the two ovens 101 and 101 ' is achieved that with the same number of oven levels in the ovens 101 and 101 ' halves the cycle time of the process and the output to heated workpieces 105 doubled. If the proposed installation space for the ovens has limited height ratios, it is also possible to adjust the height of the two ovens 101 and 101 ' halve at constant cycle time and so the application of workpieces 105 to keep it constant from the process.

101

height adjustable oven

102

drawer

103

horizontal Move

104

Lifted drawer

105

workpiece

106

adjustment

107

vertical Move

201

rotatory Move

202

translational Move

203

Ball screw

204

engine

205

Ball screw rod

206

ball screw

207

spindle nut

208

Bullet

209

recirculating ball

401

transfer device

402

grab

403

horizontal Move

404

press tool

Claims (18)

Method for treating workpieces, in which the workpieces are heated in a furnace in a plurality of horizontal furnace planes (E ₁ ... E _n ), the furnace planes (E ₁ ... E _n ) being arranged vertically one above the other and each furnace plane (FIG. E ₁ ... E _n ) in each case at a height (h ₁ ... h _n ) is located, and wherein each furnace level (E ₁ ... E _n ) for receiving at least one workpiece is formed and the workpieces after heating in a defined order from the oven levels (E ₁ to E _n ) are removed, characterized in that for the removal of the heated workpieces, the oven levels (E ₁ ... E _n ) are moved stepwise vertically, so that the respective heights ( h ₁ ... h _n ) of the individual oven levels (E ₁ ... E _n ), whereby the oven levels (E ₁ ... E _n ) are moved stepwise vertically such that the height (h ₁ ... h _n) of the respective furnace plane (e ₁ ... e _n) from which at least one workpiece is removed, a pre-defined Entnahmeh he h _x corresponding to the respective oven and level (E ₁ ... E _n) for a time t> 0 h to the unloading height is _x. The method of claim 1, wherein the position of the oven levels (E ₁ ... E _n ) is fixed in relation to the furnace and the furnace for the removal of the heated workpieces from the oven levels (E ₁ ... E _n ) by adjusting stepwise is moved vertically. A method according to claim 1, wherein the position of the oven levels (E ₁ ... E _n ) is variable relative to the oven and the oven levels (E ₁ ... E _n ) for the removal of the heated workpieces by adjusting means within the oven stepwise be moved vertically. Method according to one of claims 2 and 3, wherein as adjusting means a lifting system or a train system can be used. Method according to one of claims 1 to 4, wherein the workpieces by means of a transfer device on the removal height h _x from the oven levels (E ₁ ... E _n ) are removed. The method of claim 5, wherein the transfer _device picks up the workpieces at the removal at the defined removal height h _x and at least partially removed horizontally. Method according to Claim 6, in which the transfer _device picks up the workpieces during removal at the defined removal height h _x and removes them horizontally at the defined removal height h _x . Method according to one of claims 1 to 7, wherein after the removal of a heated workpiece from one of the oven levels (E ₁ ... E _n ) a new workpiece to be heated in the same furnace level (E ₁ ... E _n ) is introduced. Method according to one of claims 1 to 8, wherein the workpieces for heating in the furnace levels (E ₁ ... E _n ) are introduced into drawer elements, and a drawer element on the removal height h _x horizontally moved out and a workpiece is removed from the drawer element , and then the drawer element is moved back again. Apparatus for treating workpieces, comprising a furnace with a plurality of horizontal oven levels (E ₁ ... E _n ), in which workpieces can be heated, wherein the oven levels (E ₁ ... E _n ) are arranged vertically one above the other and each oven level ( E ₁ ... E _n ) in each case at a height (h ₁ ... h _n ), and wherein each furnace level (E ₁ ... E _n ) is designed for receiving and removing at least one workpiece, characterized in that the device comprises adjusting means for the stepwise vertical movement of the oven levels (E ₁ ... E _n ), wherein these adjusting means are designed so that they the respective heights (h ₁ ... h _n ) of the individual oven levels (E ₁ ... E _n ) and they can move the oven levels (E ₁ ... E _n ) so gradually vertically that the height (h ₁ ... h _n ) of a respective oven level (E ₁ ... E _n ) one fixed defined removal height (h _x ) and the respective furnace level (E ₁ ... E _n ) for a period t> 0 on the sampling height h _x can be maintained. Apparatus according to claim 10, wherein the position of the oven levels (E ₁ ... E _n ) is fixed with respect to the oven and the adjusting means are adapted to be able to move the oven vertically in a stepwise manner. Apparatus according to claim 10, wherein the position of the oven levels (E ₁ ... E _n ) is variable relative to the oven and the adjusting means are adapted to increment the oven levels (E ₁ ... E _n ) within the oven can move vertically. Device according to one of claims 11 and 12, in which the Adjusting means are designed as a lifting system or as a train system. Device according to one of claims 10 to 13, comprising a transfer device, which is designed for removing the workpieces from the oven levels (E ₁ ... E _n ) on the removal height h _x . Apparatus according to claim 14, wherein the transfer device is designed so that it can pick up workpieces at the defined removal height h _x and at least partially remove them horizontally. Apparatus according to claim 15, wherein the transfer device is designed so that they can pick up the workpieces at the defined removal height h _x and haul away horizontally on the defined removal height h _x . Device according to one of claims 14 to 16, in which the transfer device is designed such that, after the removal of a heated workpiece from one of the oven levels (E ₁ ... E _n ), a new workpiece to be heated is introduced into the same oven level (E ₁ . ..E _n ) can bring. Device according to one of claims 10 to 17, wherein in the oven levels (E ₁ ... E _n ) drawer elements are provided for receiving workpieces, wherein a drawer element on the removal height h _{x is} horizontally movable.