DE102008050927B4 - Energetically optimized process, in which workpieces are heated, as well as workpiece conveyor and heat transfer unit - Google Patents

Abstract

Method, in particular industrial process, wherein workpieces (16, 17) are heated before and / or during treatment and / or processing and are cooled after treatment and / or processing, the thermal energy of the treated and / or processed workpieces (17) is used to provide thermal energy and / or to generate electrical energy, characterized in that the thermal energy from a workpiece (17) to be cooled and also from this workpiece (17) originating waste and / or scrap is transferred to a yet to be treated and / or workpiece to be processed (16) is transferred.

Description

The present invention relates to a method, in particular industrial process, wherein workpieces are heated before and / or during a treatment and / or processing and cooled after treatment and / or processing, wherein the thermal energy of the treated and / or machined workpieces to provide Heat energy and / or used to generate electrical energy.

Furthermore, the invention relates to a workpiece conveyor for carrying out the method according to the invention and to a heat transfer unit for carrying out the method according to the invention and / or for a workpiece conveyor according to the invention.

There are a variety of industrial processes are known in which workpieces are first heated to then a treatment and / or processing and then supplied to a cooling. It may be z. B. to hardening or tempering treatments for metallic workpieces, especially steel.

Particularly common in this context is the machining of metal workpieces by means of rolling and / or forging processes. The workpieces to be machined are referred to in this context as blanks or possibly as semi-finished products. In addition, workpieces fed to a forging process are also referred to as blocks or billets (in particular when forging crankshafts). However, methods are also known in which non-metallic workpieces are first heated, then processed and finally cooled again.

By way of example only, a method according to the prior art will be described in the following, in which said blocks or billets are fed to a so-called forging line and brought there into the desired shape.

Usually, the workpieces to be processed are first heated in a forging heater to the forging temperature, for example. About 1100 ° C, heated. Thereafter, the heated workpieces go through the other stations of the forging line, where they are transformed. These stations may include a stretching roll, a preforming press, a main press, a trimming press and a sizing press. Thereafter, the finished forged workpieces are placed at the end of the forging line in a cooling conveyor. In the cooling conveyor, the still hot workpieces are gradually cooled during transport to the ambient air by heat radiation and air convection, whereby approximately room temperature can be achieved. Thereafter, the forged workpieces are storable or marketable or can be supplied to further treatment and / or processing steps.

However, the industrial processes known from the prior art are associated with disadvantages. Thus, the workpieces are heated in a heater or oven with high energy input to very high temperatures. The achieved temperature difference between the input and output of the heater can be over 1000 Kelvin. After treatment and / or processing of the workpieces, this thermal energy is dissipated again. As a result, a generic process is only particularly energy-intensive operable.

Furthermore falls during the cooling of the still hot workpieces in industrial operation on a large amount of heat. As a result, the operating site heats up so that employees may not be able to stay close to the workpieces to be cooled. Alternatively, cost-intensive insulation and / or shielding and / or suction measures must be provided here.

From the US 4,032,365 A is a generic method known. According to this method, workpieces are heated before and / or during a treatment and / or processing and cooled after treatment and / or processing. The thermal energy of the treated and / or machined workpieces is used to provide heat energy and / or to generate electrical energy. It has also already been recognized that the energy required to heat workpieces can be significantly reduced, in which the waste heat to be cooled workpieces is also used to heat the aufzuwärmenden workpieces. For this purpose, the initially cold workpieces are introduced into a heat transfer unit and conveyed in countercurrent to the already processed workpieces over to an induction furnace. It is disadvantageous that the existing heat energy is used only insufficient. The heat transfer between the hot and cold workpieces takes place only after the processing of the hot workpieces. During machining, however, the mass of hot workpieces decreases. Thus, the cold workpieces in the heat transfer, a smaller amount of heat available.

Out DE 42 34 285 A1 For example, a method of heat treating metallic material in a roller furnace is known. The metallic material is transported through a roller furnace to a subsequent cooling zone. The heat released during the cooling of the material is returned to the burners within the roller kiln in the form of preheated air. This leads to a Heat recovery and you can reduce energy consumption accordingly.

The US 5,020,208 A shows a method for reheating cast semis. Cold semi-finished products are preheated in the process by heat transfer from already processed hot workpieces. The heat transfer takes place via heat radiation or direct contact of both workpieces.

The present invention is now based on the object to enable an energy-optimized and cost-effective treatment and / or processing of workpieces.

This object is initially achieved with respect to a method having the features of patent claim 1.

The method according to the invention is characterized in that the thermal energy of each of a workpiece to be cooled and of waste and / or rejects originating from this workpiece is transferred to a workpiece which is still to be treated and / or processed.

The workpiece conveyor according to the invention is characterized by the features of the independent claim 11, according to which it serves to carry out the method according to the invention.

According to the invention, it has been recognized that the thermal energy stored in the heated or treated and / or machined workpieces can be used in a meaningful manner, namely in the form of heat energy and / or for the generation of electrical energy. Accordingly, can be dispensed with a sole cooling of the workpieces by means of convection and / or radiation. Rather, the thermal energy of the workpieces can be specifically taken up and fed to a further use.

The heat energy is transferred from a respective workpiece to be cooled and also waste and / or rejects originating from this workpiece to a workpiece still to be treated and / or processed. In other words, in this case a heat transfer is realized in which exactly one hot workpiece is always assigned a cold workpiece. Thereafter, a heat transfer can take place between these two workpieces in a precisely predictable manner, whereby the cooling and heating curve of the respective workpiece can be predetermined. For this purpose, the two merged workpieces can also be "encapsulated" in terms of apparatus, for example. Thermal insulation can be produced with respect to the environment.

It is possible to use the thermal energy of cooling workpieces for preheating still workpieces to be treated. As a result, the amount of primary energy used in heating or in the furnace can be significantly reduced. Alternatively or additionally, one or more thermal cycles can be operated according to the principle of the Organic Rankine Cycle (ORC) with the waste heat to be cooled workpieces.

In addition to the energy saving or recovery, the invention achieves that the operating site or the immediate surroundings of the workpieces to be cooled is no longer heated excessively. As a result, the adverse effect on employees is minimized and costly protective measures are unnecessary.

Consequently, a method, in particular an industrial process, specified, with which an energy-optimized and cost-effective treatment and / or processing of workpieces is possible.

The inventive method proves to be particularly advantageous if workpieces made of metal, especially steel, treated and / or processed. Due to the comparatively large heat capacity of metallic workpieces, the amount of thermal energy stored in heated workpieces is also large. Therefore, it makes sense in particular to make sensible use of the thermal energy of metallic workpieces. It should be understood, however, that the method of the invention is not limited to processes in which metallic workpieces are treated and / or processed.

In a development of the method, a processing line for workpieces, in particular a forging and / or rolling line, is used. It has already been shown that the method according to the invention is particularly suitable for forging and / or rolling processes. Metallic workpieces, which are processed in forging lines, usually have to be heated to very high temperatures (about 1100 ° C). This is associated with a high use of primary energy. Therefore, it is particularly advantageous here to recover the thermal energy of the treated workpieces.

Heat energy from workpieces to be cooled is transferred to workpieces still to be treated and / or processed. As a result, the stored thermal energy of the machined workpieces can be utilized and the use of primary energy in the heater or furnace can be reduced since workpieces still to be processed can be preheated with the recirculated thermal energy.

In this context, it is also proposed to transfer heat energy from waste and / or waste arising during treatment and / or processing to workpieces still to be treated. These may be on the one hand to workpieces that have been processed incorrectly and are usually recycled as scrap in the metal recycling. It is proposed to use the thermal energy of such rejects prior to recycling in the recycling process for preheating workpieces. It is also preferable to energetically, burrs, chips or the like. Waste materials from machined work also to use for preheating new workpieces. For this purpose, a machined workpiece initially remain together with the removed waste material, namely to be able to preheat with its entire original mass a workpiece still to be machined.

With regard to a high throughput of the method according to the invention and in the sense of a continuous process management, an embodiment is preferred in which the workpieces are conveyed during the heat transfer, in particular wherein a workpiece conveyor is used. The work conveyor can pick up workpieces to be cooled at the end of a line, in particular a forging line, and feed them away from the end of the processing line. During conveyance, the machined workpieces can be cooled down to the desired temperature. Thereafter, the workpieces are removed from the workpiece conveyor and supplied for further processing, use or storage. For the purposes of the present invention, a workpiece conveyor can now be used which is designed such that the thermal energy of processed workpieces within the workpiece conveyor is made usable. For this purpose, the workpiece conveyor can, for example, absorb and convey cold workpieces still to be machined, with heat being transferred from the machined to the workpieces still to be machined within the workpiece conveyor and the latter being preheated as a result. Alternatively or additionally, a medium, for example a working medium of an ORC cycle, can be heated and / or vaporized in the workpiece conveyor. This makes it possible to obtain further heat energy and / or electrical energy from the workpieces to be cooled.

In view of a particularly effective heat transfer between the workpieces, an embodiment is favored in which workpieces to be cooled are conveyed countercurrently to workpieces to be treated and / or processed. Due to the countercurrent flow always the greatest possible temperature difference between the two streams is realized. The principles of countercurrent heat transfer are familiar to those skilled in the art. Specifically, hot, removed from a processing line workpieces can be introduced into a work conveyor in the form of a thermally insulated tunnel. At the other end of the workpiece conveyor, however, cold, still to be machined workpieces can be abandoned and then promoted above the hot workpieces in countercurrent. With a process-controlled air circulation and precise control can also be ensured that the hot workpieces heat is removed from the specifications and requirements of the desired metallurgical microstructure transformation and passed on to the cold workpieces.

In concrete terms to the latter embodiment of the method according to the invention, a development is proposed in which a processing line is used in U-shape. The construction of the machining line, in particular a forging and / or rolling line, in U-shape ensures that the input of the workpieces is positioned in the machining line in the vicinity of the output of the machined workpieces. This avoids long transport routes.

As an alternative to heat transfer in countercurrent, in view of a simple technical solution and a high material throughput, it is preferred that workpieces to be cooled be conveyed in cocurrent with workpieces still to be treated and / or processed. For this purpose, for example, a workpiece conveyor can be used, which - as already described - is designed substantially as an elongated, heat-insulated tunnel. In it, cold workpieces above hot, cooled workpieces can be promoted. In this embodiment of the method, a maximum temperature difference between hot and cold workpieces is achieved at the entrance of the workpiece conveyor.

In this connection, an embodiment of the method is preferred in which a workpiece conveyor is used in ring form. In other words, the workpiece conveyor may be designed as an endless loop. The conveyor can pick up hot workpieces at the exit of a processing line and feed preheated workpieces to the input of the processing line. During production, heat energy can be transferred from the hot, already machined workpieces to the cold workpieces, preheating them.

It is proposed that the workpiece to be cooled - and waste and / or scrap originating from this workpiece - and the workpiece still to be treated and / or processed be introduced together in a heat transfer unit. Such a heat transfer unit may, for example, have the form of a box with heat-insulated walls. The heat transfer unit may have a receptacle for a cold workpiece in the upper area and a receptacle for a hot workpiece in the lower area. Furthermore, at least one flap is to be provided for charging the heat transfer unit. The heat transfer unit can also have two flaps, namely an overhead for the cold or preheated workpiece and a lower for the hot or cooled workpiece. If the heat transfer unit is charged, it is closed via the flap or the flaps. In the unit then takes place by convection and radiation heat transfer between the hot and the cold workpiece. The heat transfer unit can be used in discontinuous operation. So the unit can be equipped with a hot and a cold workpiece and then parked in the camp until the desired temperature compensation is completed. With regard to a continuous process control, however, it is preferred that several of the heat transfer units are part of an aforementioned work piece conveyor, in particular a work conveyor in ring form. The ring conveyor can convey the heat transfer units from the loading station of the heater or oven to the end of the processing line for the workpieces and back again. The heat transfer units can then be charged at the various points of the processing line with hot and cold workpieces or can be unloaded preheated or cooled workpieces from the heat transfer units.

With regard to the generation of electrical energy from the thermal energy of the hot workpieces, an embodiment of the method according to the invention is finally proposed in which the heat energy of the workpieces to be cooled is used to generate steam in an ORC process, possibly multi-stage and / or cascaded. The use of thermal energy in an ORC process can represent the sole utilization of the heat of the hot workpieces. However, it is preferred to provide heat utilization in an ORC process in addition to the heat transfer between hot and cold workpieces described in detail above. Thus, in terms of energy, it is particularly advantageous to use the residual heat of the already partially cooled workpieces (after heat transfer with a workpiece to be preheated) in an ORC process. In both cases, energy from hot workpieces can be fed to the evaporator of an ORC plant. In this case, the evaporator can be arranged in an insulated, tunnel-like workpiece conveyor. The working fluid to be heated and evaporated can be passed through the work conveyor in countercurrent to the workpieces to be cooled. The ORC cycle usually can have an efficiency of at most about 20%. However, due to the high operating temperature of the hot workpieces, it is conceivable to carry out up to three ORC processes with different working media (and thus different evaporation temperatures) in cascade form. The three evaporators can be arranged sequentially within a single work conveyor.

With the features of claim 11, an inventive workpiece conveyor for performing a method according to the invention is given.

To avoid repetition, reference is expressly made to the statements relating to the method according to the invention with regard to the features and advantageous embodiments of the workpiece conveyor.

Thus, according to a first development, a workpiece conveyor is initially proposed in which workpieces to be cooled can be conveyed countercurrently to workpieces to be treated and / or processed, and where the processing line for the workpieces optionally has a U-shape.

In a further advantageous embodiment, workpieces to be cooled in the workpiece conveyor according to the invention can be conveyed in cocurrent with workpieces still to be treated and / or machined. In this case, a ring shape of the workpiece conveyor proves to be particularly advantageous.

In a particularly preferred development, the workpiece conveyor according to the invention has at least one previously described heat transfer unit, in which a workpiece to be cooled and waste and / or rejects originating from this workpiece and a workpiece still to be treated and / or to be machined can be introduced.

With the features of claim 15, finally, a heat transfer unit according to the invention is given.

With regard to features and advantageous embodiments of the heat transfer unit, to avoid repetition, reference is first expressly made to the statements relating to the method according to the invention and with reference to the workpiece conveyor according to the invention.

Particularly advantageous is a heat transfer unit, which has a substantially cuboidal configuration and / or heat-insulated side walls.

In a further expedient embodiment, the heat transfer unit has at least one flap for introducing workpieces.

Finally, an embodiment of the heat transfer unit is preferred, which has at least one inner receptacle for a workpiece.

There are now various possibilities for designing and developing the teaching of the present invention in an advantageous manner. For this purpose, on the one hand to the respective subordinate claims, and on the other hand to refer to the following explanation in each case an embodiment of the workpiece conveyor according to the invention and the heat transfer unit according to the invention with reference to the drawing. In connection with the explanation of the preferred embodiments of the invention with reference to the drawing, preferred embodiments and further developments of the method according to the invention are explained. In the drawing shows

1 a schematic representation of a forging line with a workpiece conveyor in ring form for preheating cold workpieces and for feeding the forging line with preheated workpieces, and

2 a partially schematic front view of a preferred embodiment of a heat transfer unit according to the invention.

1 shows a schematic representation of a forging line with a workpiece conveyor in ring form for preheating cold workpieces and for feeding the forging line with preheated workpieces.

In the first place, the interaction according to the invention of a processing line is in a very general sense 1 for workpieces, which here as a forging line 2 is configured with a workpiece conveyor according to the invention 3 shown. The forge line 2 is a schematic representation of an elongated processing line with various stations for machining workpieces. The forge line 2 is charged at point A with preheated workpieces. Point B, on the other hand, indicates the exit of the forging line 2 ,

First, workpieces of suitable size with the help of a saw 4 made from the starting material. Thereafter, cold and / or already preheated according to the invention workpieces are the forge heater 5 fed, where the workpieces are heated by the use of primary energy to the forging temperature, which may be about 1100 ° C.

The heated and thus prepared for the actual forging process workpieces are subsequently a stretching roller 6 , a main press 7 , a trimming press 8th and a sizing press 9 fed. The mentioned processing stations are known per se from the prior art and require no further explanation at this point.

In point B, the machined and hot workpieces are from the forging line 2 taken.

It's a forge line 2 in a continuous loop surrounding workpiece conveyor 3 provided, which in this embodiment as a ring conveyor 10 is designed. Here is the embodiment of the ring conveyor 10 as an endless loop around the entire forging line 2 merely to be understood as an example. So can the through the ring conveyor 10 also formed any other suitable design within or around the processing line 1 accept around.

The ring conveyor 10 consists of a large number of heat transfer units 11 , which each have a thermally insulated box. This box has a receptacle for a cold, vorzuwärmendes workpiece (blank) in the upper part and a receptacle for a hot, already processed and cooled workpiece in the lower area. The boxes are inside the ring conveyor 10 promoted according to the power-and-free process. Alternatively, the heat transfer units can be 11 also as part of a monorail conveyor.

The ring conveyor 10 promotes heat transfer units according to the invention 11 from the forging station of the forge heater (point A) to the end of the forging line (point B) and back again.

After charging a heat transfer unit 11 With a hot and a cold workpiece, heat transfer between the hot workpiece and the still cold blank may occur during transport by convection and radiation. For details regarding the heat transfer unit according to the invention 11 will go to the description 2 directed.

Thus, at point A preheated workpieces from the heat transfer units 11 unload and the forging line 2 fed. These Workpieces are replaced by cold workpieces, which in turn are subsequently preheated. At point B, however, cooled, already processed workpieces from the heat transfer units 11 taken and hot workpieces, which previously in the forging line 2 have been processed, replaced.

The already partially cooled and from the heat transfer units 11 removed workpieces are at point B in addition to a cooling tunnel 12 fed. In this cooling tunnel 12 is arranged an evaporator for an ORC cycle. The partially cooled workpieces pass through the cooling tunnel 12 in countercurrent to the working fluid of the ORC cycle, causing it to be heated and vaporized. This can drive an ORC turbine to generate electrical energy. There may also be several evaporators in a row in the cooling tunnel 12 can be switched so that cascaded ORC processes can be executed. In this case, the ORC work equipment can be selected so that in spite of the further cooling of the workpieces in each case an evaporation of the working fluid succeeds.

Alternatively, the cooling tunnel 12 also be flowed through in countercurrent to the workpieces with a non-boiling medium (such as thermal oil), which absorbs the thermal energy of the further cooling workpieces and for further use on the outside of the cooling tunnel 12 passes.

The ring conveyor 10 usually conveys the received workpieces in a clockwise direction in order to provide the longest possible preheating time for the blanks recorded in point A. The ring conveyor 10 However, it may also - if appropriate - be operated in the opposite direction.

The promotion from point A to point B can be divided into three cycles: At the start of the forging line 2 are all heat transfer units 11 empty. After the first loading of a heat transfer unit 11 with a cold workpiece (blank) at point A moves the heat transfer unit 11 to point B. The recorded blank is not preheated because no hot workpiece is available yet.

The second cycle can be summarized as follows: If a cycle has already been run, a preheated blank is unloaded at point A. At a discharge temperature of machined workpieces from the forging line 2 of 1100 ° C and a temperature of the blank of 20 ° C, the blank can theoretically be preheated to a temperature of 560 ° C. Now, another cold blank is in the heat transfer unit 11 given, in which still the "half" cooled workpiece is present. On the route from point A to point B, the new blank is already preheated. The theoretically achievable equilibrium is 290 ° C.

In the third cycle, the theoretically achievable temperature of the blank is already at 695 ° C, then at constant parameters (temperature of the machined workpieces = 1100 ° C, temperature of the blanks = 20 ° C) at a preheating temperature of about 736 ° C. leveling off.

For the promotion of point B to point A three cycles can also be described:
As already mentioned, during the first cycle, a cold blank reaches point B, where a hot workpiece enters the heat transfer unit 11 is loaded. After the subsequent promotion to point A theoretically a first temperature equilibrium of 560 ° C can be achieved.

During the second cycle, a workpiece cooled down to 290 ° C is removed at point B, and a freshly forged 1100 ° C workpiece is picked up.

In the third cycle, the workpiece to be removed at point B is only cooled to 357 ° C. After further cycles, this temperature will settle at 373 ° C. The machined workpieces cooled from 1100 ° C to approx. 370 ° C can still be used in the cooling tunnel afterwards 12 release more heat energy.

2 shows a partially schematic front view of a preferred embodiment of the heat transfer unit according to the invention 11 ,

The heat transfer unit 11 has the shape of a box, which in turn is a completely thermally insulated housing 13 having. The side walls can consist of steel sheets. Between the inner and outer walls of the housing 13 is a high-performance and temperature-resistant insulation, for example made of mineral wool intended.

The embodiment of the heat transfer unit shown 11 further points to the front 2 sliding doors 14 for opening the heat transfer unit 11 on.

Inside the heat transfer unit 11 are two shots 15 arranged for hot and cold workpieces. It is on the upper intake 15 a cold workpiece 16 (Blank) and on the lower picture 15 a hot workpiece 17 arranged. For loading and unloading a blank 16 can the upper sliding door 14 and for loading and unloading a hot or already partially cooled workpiece 17 the lower slide door 14 to be used.

The heat transfer unit according to the invention 11 allows heat transfer from each one cooled workpiece 17 - and also from this workpiece 17 waste and / or rejects - to a workpiece still to be treated and / or processed 16 , For this purpose, the heat transfer unit 11 with the workpieces 16 . 17 be loaded and then - for example, in a high-bay warehouse - parked.

However, preferably, a continuous heat transfer between hot workpieces 17 and cold workpieces 16 sought, namely by the heat transfer unit according to the invention 11 Part of a workpiece conveyor 3 , in particular a ring conveyor 10 according to 1 is.

With regard to further advantageous embodiments of the method according to the invention and of the devices according to the invention, reference is made to avoid repetition to the general part of the description and to the appended claims.

LIST OF REFERENCE NUMBERS

A

Entrance (forging line)

B

Exit (forging line)

1

processing line

2

forging line

3

Workpiece conveyor

4

saw

5

Schmiedeerwärmer

6

forging roll

7

Chief Press

8th

trimming

9

sizing

10

The ring conveyor

11

Heat transfer unit

12

cooling tunnel

13

Housing (heat transfer unit)

14

flap

15

Recording (workpiece)

16

cold workpiece (blank)

17

hot workpiece

Claims (18)

Process, in particular industrial process, whereby workpieces ( 16 . 17 ) are heated before and / or during a treatment and / or processing and cooled after treatment and / or processing, the thermal energy of the treated and / or machined workpieces ( 17 ) is used for the provision of heat energy and / or for generating electrical energy, characterized in that the heat energy of each one cooled workpiece ( 17 ) and also from this workpiece ( 17 ) waste and / or broke on a workpiece to be treated and / or processed ( 16 ) is transmitted. Method according to claim 1, characterized in that workpieces ( 16 . 17 ) made of metal, in particular steel, treated and / or processed. Method according to claim 1 or 2, characterized in that a processing line ( 1 ) for workpieces ( 16 . 17 ), especially a blacksmith ( 2 ) and / or rolling line is used. Method according to one of claims 1 to 3, characterized in that the workpieces ( 16 . 17 ) are conveyed during the heat transfer, in particular wherein a workpiece conveyor ( 3 ) is used. Method according to one of claims 1 to 4, characterized in that to be cooled workpieces ( 17 ) in countercurrent to still to be treated and / or machined workpieces ( 16 ). Method according to claim 5, characterized in that a processing line ( 1 ) is used in U-shape. Method according to one of claims 1 to 6, characterized in that to be cooled workpieces ( 17 ) in cocurrent with still to be treated and / or machined workpieces ( 16 ). A method according to claim 7, characterized in that as a workpiece conveyor ( 3 ) an annular conveyor ( 10 ) is used. Method according to one of claims 1 to 8, characterized in that the workpiece to be cooled ( 17 ) - and of this workpiece ( 17 ) waste and / or rejects - and the workpiece still to be treated and / or processed ( 16 ) together into a heat transfer unit ( 11 ) are introduced. Method according to one of claims 1 to 9, characterized in that the heat energy of the workpieces to be cooled ( 17 ) is used for generating steam in a - possibly multi-stage and / or cascaded - ORC process. Workpiece conveyors ( 3 ) for carrying out a method according to one of claims 1 to 10. Workpiece conveyors ( 3 ) according to claim 11, characterized in that workpieces to be cooled ( 17 ) in countercurrent to still to be treated and / or machined workpieces ( 16 ), and where appropriate the processing line ( 1 ) has a U-shape for workpieces. Workpiece conveyors ( 3 ) according to claim 11 or 12, characterized in that the workpieces to be cooled ( 17 ) in cocurrent with still to be treated and / or machined workpieces ( 16 ), in particular wherein the workpiece conveyor ( 3 ) a ring conveyor ( 10 ) having. Workpiece conveyors ( 3 ) according to claim 13, characterized by at least one heat transfer unit ( 11 ) into which a workpiece to be cooled ( 17 ) - and of this workpiece ( 17 ) waste and / or rejects - and a workpiece still to be treated and / or processed ( 16 ) can be introduced. Heat transfer unit ( 11 ) for carrying out a method according to claim 9 or 10 and / or for a workpiece conveyor ( 3 ) according to claim 14. Heat transfer unit ( 11 ) according to claim 15, characterized by a substantially cuboidal configuration and / or by heat-insulated side walls. Heat transfer unit ( 11 ) according to claim 15 or 16, characterized by at least one flap ( 14 ) for introducing workpieces ( 16 . 17 ). Heat transfer unit ( 11 ) according to one of claims 15 or 17, characterized by at least one inner receptacle ( 15 ) for a workpiece ( 16 . 17 ).

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