Vacuum furnace for the heat treatment of metallic workpieces

Abstract

The invention relates to a vacuum chamber furnace for the heat treatment of metallic workpieces forming a batch, comprising a furnace housing (1), wherein the furnace housing (2) surrounds a heatable and evacuable treatment chamber (2) for receiving the batch. The treatment chamber (2) has closable cooling gas passages (6, 7) for introducing cooling gas into and exhausting the cooling gas from the treatment chamber (2). A heat exchanger (11) is surrounded by an enclosure (12) which has at least one closable inlet (13a, 13b) for introducing the cooling gas.According to the invention, the treatment chamber (2) and the housing (12) are connected to the heat exchanger (11) to form a block-shaped assembly (15), wherein the assembly (15) comprises at least one cooling gas channel (16a, 16b) which is configured to direct the cooling gas within the assembly (15) between the treatment chamber (2) and the heat exchanger (11), and wherein the assembly (15) is configured to be inserted into the oven housing (1) as a single piece during the construction of the vacuum oven.

Description

[0001] The invention relates to a vacuum chamber furnace for the heat treatment of metallic workpieces forming a batch, comprising a furnace housing with a horizontal main axis, wherein the furnace housing surrounds a heatable and evacuable treatment chamber for receiving the batch, wherein the treatment chamber has at least one closable cooling gas passage opening for introducing the cooling gas into the treatment chamber and at least one closable cooling gas passage opening for venting the cooling gas from the treatment chamber, comprising at least one heat exchanger and a cooling gas fan, which is arranged to circulate cooling gas through the treatment chamber and the heat exchanger during a cooling phase.

[0002] The furnace housing of vacuum chamber furnaces is typically hollow and cylindrical. It can be double-walled and water-cooled. The furnace housing is usually mounted horizontally on a furnace frame and surrounds a treatment chamber, which can be heated and evacuated. The treatment chamber is generally rectangular. Both the furnace housing and the treatment chamber have a loading opening at each end, which can be opened or closed by means of doors.

[0003] Heat treatment refers to processes used to treat workpieces or metallic components. The workpieces are heated in a controlled manner and then cooled or quenched to alter their material properties. Common heat treatments include annealing, tempering, and hardening.

[0004] The heat treatment of metal workpieces or components generally requires rapid cooling after heating, i.e., quenching or quenching. The batch is quenched using a cooling gas, particularly nitrogen or argon, which is introduced into the treatment chamber through at least one cooling gas inlet in a wall of the chamber and discharged from the treatment chamber through at least one further cooling gas inlet.

[0005] The cooling gas is circulated between the treatment chamber and the heat exchanger by a cooling gas fan or blower to cool the batch. After passing through the treatment chamber, the cooling gas is cooled again. The cooling gas fan is connected to a cooling gas source.

[0006] After cooling the batch of workpieces, the cooling gas is directed from the treatment chamber to the heat exchanger through at least one cooling gas passage opening. It is known in practice that the cooling gas flows through the space between the furnace housing and the treatment chamber, so that baffles are located inside the furnace housing to guide the cooling gas.

[0007] The cooling gas passages can be closed by means of closing elements. These closing elements are closed during the heating phase and open during the cooling or quenching phase. The closing elements are generally designed to abut the inner wall of the furnace housing.

[0008] Because the furnace housing is round and the treatment chamber is rectangular, parts of the treatment chamber, especially the sealing elements that extend towards the housing and abut the inside of the furnace housing, must be adapted to the round inner wall of the furnace housing during assembly. This adaptation work is time-consuming, and the manufacturing costs for the vacuum chamber furnace are correspondingly high.

[0009] It is known from practice that the furnace housing directly surrounds the heat exchanger, so the inner surface of the furnace housing must be designed accordingly to guide the cooling gas in the area of ​​the heat exchanger, which is complex from a manufacturing perspective.

[0010] The invention is therefore based on the objective of further developing a vacuum chamber furnace of the type mentioned above in such a way as to reduce the manufacturing effort.

[0011] The problem underlying the invention is solved with a vacuum chamber furnace having the features of claim 1.

[0012] According to the invention, the heat exchanger is surrounded by an enclosure which has at least one closable inlet for introducing the cooling gas, wherein at least the treatment chamber and the enclosure are connected to the heat exchanger to form a block-shaped assembly, wherein the assembly comprises at least one cooling gas channel which is configured to guide the cooling gas within the assembly between the treatment chamber and the heat exchanger, and wherein the assembly is configured to be inserted into the oven housing as a single piece or in its entirety during the construction of the vacuum furnace.

[0013] The housing and the cooling gas duct form a closed flow path for the cooling gas between the treatment chamber and the heat exchanger within the assembly. This allows the block-shaped assembly to be completed and assembled outside the furnace housing. The assembly can include any additional components required for the cooling function. The assembled assembly can be easily inserted into the furnace housing and connected to the cooling gas fan. Complex modifications to components for guiding the cooling gas inside the furnace housing are avoided. Consequently, the manufacturing effort for the furnace housing is significantly reduced.

[0014] The heat exchanger can be of any design. Within the scope of the invention, all suitable heat exchanger designs can be used.

[0015] An advantageous further development of the invention consists in the fact that the heat exchanger connects to the treatment chamber in the direction of the main axis of the furnace housing, that the cooling gas fan can be connected to the heat exchanger centrally on the suction side and to the cooling gas channel on the pressure side.

[0016] Preferably, the assembly comprises at least one heat exchanger flap by means of which the inlet can be opened or closed, wherein the heat exchanger flap is pivotably mounted and preferably pivotable into the cooling channel by means of an actuator.

[0017] An advantageous further development of the invention consists in the fact that the housing has two inlets, that each inlet can be opened or closed with a heat exchanger flap, that preferably an actuator acts on each heat exchanger flap, which is preferably configured to open or close the heat exchanger flaps during the cooling phase alternately with the reversal of the flow direction of the cooling gas at predetermined intervals.

[0018] Preferably, the assembly has at least one treatment chamber flap with which the cooling gas passage opening for introducing the cooling gas into the treatment chamber can be opened or closed, and at least one further treatment chamber flap with which the cooling gas passage opening for venting the cooling gas from the treatment chamber can be opened or closed, wherein each treatment chamber flap is pivotably mounted and pivotable into the cooling channel.

[0019] Advantageously, the actuators are designed to keep the treatment chamber valves open during the cooling phase.

[0020] The cooling gas inlet opening in the treatment chamber for introducing the cooling gas into the treatment chamber and the cooling gas outlet opening for releasing the cooling gas from the treatment chamber are preferably arranged in opposite walls of the treatment chamber, in particular in the top wall and the bottom of the treatment chamber. Any other arrangement is possible within the scope of the invention.

[0021] In a further development of the invention, the vacuum furnace is characterized in that the assembly comprises a cooling gas channel for directing the cooling gas towards the treatment chamber and a further cooling gas channel for directing the cooling gas from the treatment chamber towards the heat exchanger.

[0022] Preferably, the at least one cooling gas channel runs along the outside of the treatment chamber and the housing in the direction of the longitudinal axis of the assembly.

[0023] Preferably, each cooling gas channel has an outer wall. This wall, together with a bottom wall, forms a closed flow path for the cooling gas. The outer wall can include side walls and a top wall.

[0024] The cross-section of the cooling channel can be rectangular, for example. The bottom wall can be formed at least partially by a wall of the treatment chamber, a treatment chamber flap, and at least partially by a wall of the enclosure and a heat exchanger flap.

[0025] In a preferred further development, the treatment chamber flaps are arranged to form part of the outer wall of the at least one cooling gas channel, in the position in which the treatment chamber flaps release the cooling gas passage openings.

[0026] Preferably, the heat exchanger flaps are arranged to form part of the outer wall of the at least one cooling gas channel.

[0027] Preferably, the housing of the heat exchanger and the cooling gas duct are made of sheet metal.

[0028] Preferably, the assembly has rollers for moving the assembly within the oven housing.

[0029] Advantageously, the furnace housing contains attachment points for the assembly consisting of the enclosure, heat exchanger, treatment chamber and at least one cooling gas channel.

[0030] Within the scope of the invention, the features described above can also be used in other combinations or individually. Further details and advantages of the subject matter of the invention will become apparent from the following description in conjunction with the drawing, which describes a preferred embodiment of the invention. The invention is not intended to be limited by the embodiment shown.

[0031] The drawing shows in Fig. 1 a schematically represented vacuum chamber furnace; Fig. 2 a schematic view of a building unit according to the invention.

[0032] Fig. Figure 1 shows a vacuum chamber furnace for the heat treatment of metallic workpieces forming a batch. A hollow cylindrical pressure-tight furnace housing 1 is arranged horizontally, i.e., lying on a furnace frame 1a. The furnace housing surrounds a treatment chamber 2, which has a rectangular cross-section and is thermally insulated in a manner known per se. The treatment chamber 2 is heated in a manner not shown and can be evacuated.

[0033] The furnace housing 1 has a first door 3 on its front side and the treatment chamber 2 has a second door 4 on its front side for loading and unloading.

[0034] The treatment chamber 2 has a cooling gas passage opening 6 in the base 8 for introducing the cooling gas into the treatment chamber 2 and a cooling gas passage opening 7 in the top wall 5 for venting the cooling gas out of the treatment chamber 2.

[0035] The cooling gas passage opening 6 is closed or opened by a treatment chamber flap 9a. The cooling gas passage opening 7 is closed or opened by a treatment chamber flap 9b. The treatment chamber flaps 9a and 9b are pivotally mounted on the treatment chamber 2.

[0036] During the heating phase, the treatment chamber flaps 9a, 9b are closed and during the entire length of the cooling phase or the quenching phase they are open.

[0037] A cooling gas fan 10 is driven by a motor 10a and is connected to a cooling gas source (not shown). The cooling gas fan 10 serves to circulate the cooling gas to cool a batch (not shown) in the treatment chamber 2.

[0038] A rectangular heat exchanger 11 is attached to the rear of the treatment chamber 2 in the direction of the horizontal main axis of the furnace housing 1. The heat exchanger 11 is connected internally to the suction side 10b of the cooling gas fan 10.

[0039] The heat exchanger 11 is designed to cool the cooling gas flowing out of the treatment chamber 2 during the cooling phase of the heat treatment, before it is fed back into the treatment chamber 2.

[0040] The heat exchanger 11 is surrounded by a housing 12 which has an inlet 13a and an inlet 13b for the cooling gas.

[0041] The inlet 13a can be closed or opened with a heat exchanger flap 14a and the inlet 13b can be closed with a heat exchanger flap 14b.

[0042] As in Fig. 1 and Fig. As shown in Figure 2, the treatment chamber 2 and the housing 12 with the in Fig. The two heat exchangers 11 (not shown) are connected to form a block-shaped assembly 15, which is designed to be inserted into the oven housing 1 as a single unit during the construction of the vacuum oven. The assembly 15 is completed or assembled outside the oven housing 1 and then inserted into the oven housing 1 as a single unit. The oven housing 1 contains (not shown) attachment points for the assembly 15.

[0043] The assembly unit 15 comprises two cooling gas channels 16a and 16b, which are designed to direct the cooling gas within the assembly unit between the treatment chamber 2 and the heat exchanger 12.

[0044] The treatment chamber valves 9a, 9b are actuated by actuators 17a and 17b, which are designed to keep the treatment chamber valves 9a, 9b open during the entire cooling phase.

[0045] Actuators 18a and 18b are connected to the heat exchanger flaps 14a and 14b. These actuators are configured to alternately open and close the heat exchanger flaps 14a and 14b at predetermined intervals, for example, every 30 seconds, during the cooling phase to reverse the flow direction of the cooling gas. Depending on the position of the heat exchanger flaps 14a and 14b, the flow direction of the cooling gas is reversed.

[0046] In the Fig. 1 and Fig. Figure 2 shows the heat exchanger flap 14a closed and the heat exchanger flap 14b open. The cooling gas fan 10 is in flow communication with the cooling gas channel 16a on the pressure side, so that the cooling gas flows into the treatment chamber 2 through the open cooling gas passage 6. After cooling a batch (not shown) in the treatment chamber, the cooling gas flows through the cooling gas passage 7 into the cooling gas channel 16b, which directs the cooling gas within the assembly to the heat exchanger 11. The cooling gas, which has been cooled in the heat exchanger 11, is drawn in centrally by the cooling gas fan 10 and conveyed back to the treatment chamber 2 on the pressure side.

[0047] Each cooling gas channel 16a, 16b has a bottom wall (not shown) which is formed at least partially by a wall of the treatment chamber 2 and a wall of the enclosure 12.

[0048] Outer walls 19a and 19b define the cooling gas channels 16a and 17b inside the furnace housing 1. The furnace housing 1 does not come into contact with the cooling gas in the area of ​​assembly 15, so no baffles for the cooling gas are required here. This reduces the manufacturing effort for the furnace housing 1.

[0049] The treatment chamber flap 9a is in the open position and forms part of the outer wall 19a of the cooling gas channel 16a. The treatment chamber flap 9b is also open and forms part of the outer wall 19b of the cooling gas channel 16b.

[0050] The heat exchanger flap 14b is in the Fig. 1 and Fig. 2 shown in the open position and forms part of the outer wall 19b of the cooling channel 16b.

[0051] The heat exchanger flap 14a is shown closed and in this position forms part of the bottom wall of the cooling gas channel 16a.

[0052] The housing 12 and the cooling gas channels 16a, 16b are made of sheet metal. The assembly 15 has rollers (not shown) which simplifies the transport of the assembly 15 into the furnace housing 1.

[0053] Modifications to the invention are readily possible. For example, the treatment chamber flaps and the heat exchanger flaps can be designed as desired. The assembly can include further components.

[0054] Finally, it is pointed out that the term “referring to” does not exclude any elements, that the reference marks do not represent a limitation, and that the word “a” or “an” includes a multitude. Reference symbol list 1 Oven housing 1a Oven stand 2 treatment chambers 3 first door 4 second door 5 Cover wall treatment chamber 6 Cooling gas passage openings for introduction 7 Cooling gas through-hole for venting 8 Floor Treatment Chamber 9a, 9b Treatment chamber valve 10 Cooling gas fan 10a Motor for cooling gas fan 10b Suction side 11 heat exchangers 12 Enclosure 13a, 13b Inlet for cooling gas housing 14a,14b Heat exchanger flaps 15 building units 16a, 16b Cooling gas channel 17 actuators for treatment chamber valves 18 actuators for heat exchanger flaps 19a, 19b Outer wall of the cooling gas duct

Claims

[1] Vacuum chamber furnace for the heat treatment of metallic workpieces forming a batch, comprising a furnace housing (1) with a horizontal main axis, wherein the furnace housing (2) surrounds a heatable and evacuable treatment chamber (2) for receiving the batch, wherein the treatment chamber (2) has at least one closable cooling gas passage opening (6) for introducing cooling gas into the treatment chamber (2) and at least one closable cooling gas passage opening (7) for venting the cooling gas from the treatment chamber (2), comprising at least one heat exchanger (11) and a cooling gas fan (10) which is configured to circulate cooling gas through the treatment chamber (2) and the heat exchanger (11) during a cooling phase, characterized by, that the heat exchanger (11) is surrounded by an enclosure (12) which has at least one closable inlet (13a, 13b) for introducing the cooling gas, that at least the treatment chamber (2) and the enclosure (12) are connected to the heat exchanger (11) to form a block-shaped assembly (15), that the assembly (15) includes at least one cooling gas channel (16a, 16b) which is designed to direct the cooling gas within the assembly (15) between the treatment chamber (2) and the heat exchanger (11), and that the assembly (15) is designed to be inserted into the oven housing (1) as a single piece during the construction of the vacuum oven. [2] Vacuum chamber furnace according to claim 1, characterized by , that the heat exchanger (11) connects to the treatment chamber (2) in the direction of the main axis of the furnace housing (1), that the cooling gas fan (10) can be connected to the heat exchanger (11) on the suction side in the center and to the cooling gas channel (16a, 16b) on the pressure side. [3] Vacuum chamber furnace according to claim 1 or 2, characterized by , that the assembly (15) comprises at least one heat exchanger flap (14a, 14b) by means of which the inlet (13a, 13b) in the housing (12) can be opened or closed, that the heat exchanger flap (14a, 14b) is pivotably mounted and preferably pivotable into the cooling channel (16a, 16b) by means of an actuator (18a, 18b). [4] Vacuum chamber furnace according to at least one of the preceding claims, characterized by , that the housing (12) has two inlets (13a, 13b), that each inlet (13a, 13b) can be opened or closed with a heat exchanger flap (14a, 14b), that preferably an actuator (18a, 18b) acts on each heat exchanger flap (14a, 14b), which is preferably configured to open or close the heat exchanger flaps (14a, 14b) during the cooling phase alternately with reversing the flow direction of the cooling gas at predetermined intervals. [5] Vacuum chamber furnace according to at least one of the preceding claims, characterized by , that the assembly (15) has at least one treatment chamber flap (9a) with which the cooling gas passage opening (6) for introducing the cooling gas into the treatment chamber (2) can be opened or closed and has at least one further treatment chamber flap (9b) with which the cooling gas passage opening (7) for venting the cooling gas from the treatment chamber (2) can be opened or closed, wherein each treatment chamber flap (9a, 9b) is pivotably mounted and preferably pivotable into the cooling channel (16a, 16b) by means of an actuator (17a, 17b) each. [6] Vacuum chamber furnace according to claim 5, characterized by , that the actuators (17a, 17b) are set up to keep the treatment chamber valves (9a, 9b) open during the cooling phase. [7] Vacuum chamber furnace according to at least one of the preceding claims, characterized by, that the assembly (15) comprises a cooling gas channel (16a) for directing the cooling gas towards the treatment chamber (2) and another cooling gas channel (16b) for directing the cooling gas from the treatment chamber (2) towards the heat exchanger. [8] Vacuum chamber furnace according to at least one of the preceding claims, characterized by , that the at least one cooling gas channel (16a, 16b) runs outside the treatment chamber (2) and the housing (12) in the direction of the longitudinal axis of the assembly (15). [9] Vacuum chamber furnace according to at least one of the preceding claims, characterized by , that each cooling gas channel (16a, 16b) has an outer wall (19a, 19b). [10] Vacuum chamber furnace according to claim 9, characterized by , that the treatment chamber valves (9a, 9b) are arranged to form part of the outer wall (19a, 19b) of the at least one cooling gas channel (16a, 16b). [11] Vacuum furnace according to claim 9 or 10, characterized by, that the heat exchanger flaps (14a, 14b) are arranged to form part of the outer wall (19a, 19b) of the at least one cooling gas channel (16a, 16b). [12] Vacuum chamber furnace according to at least one of the preceding claims, characterized by , that the housing (12) of the heat exchanger (11) and the cooling gas channel (16a, 16b) are made of sheet metal. [13] Vacuum chamber furnace according to at least one of the preceding claims, characterized by , that the assembly (15) has rollers for moving the assembly (15) in the furnace housing (1). [14] Vacuum chamber furnace according to at least one of the preceding claims, characterized by , that there are anchor points for the assembly (15) in the oven housing (1).

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