Device for supporting metallic workpieces and method for thermochemical treatment

Abstract

Device (1) for supporting metallic workpieces (10) during thermochemical treatment, comprising a ring (2) with a first and second end face (2A, 2B), wherein the first end face (2A) has a flat support surface, the second end face (2B) is equipped with 20 to 100 support elements (3), the support elements (3) delimit a support plane (4) which is plane-parallel to the support surface, the ring (2) and the support elements (3) are formed in one piece, the ring (2) has a cross-section with an inner circle of diameter D i and an outer circle with diameter D a , where the difference in diameter D a - D i 4 to 400 mm, each support element has a flat support surface, the sum of the support surfaces of all support elements is 10 to 40% of the area π 4 ( D a 2 − D i 2 ) and the support surfaces of the support elements (3) have a flatness of ≤ 10 µm.

Description

[0001] The present invention relates to a device for supporting metallic workpieces during thermochemical treatment and to a method for thermochemical treatment of one, two or more metallic workpieces.

[0002] In the state of the art, it is common practice to thermochemically treat metallic workpieces, such as gears. One of the most commonly used processes is case hardening (https: / / de.wikipedia.org / wiki / Einsatzhärten), in which workpieces made of steel or other alloys are carburized, diffused, and quenched to create a layer with a specific, preferably martensitic, microstructure on the surface of the workpieces. Other thermochemical processes include carbonitriding, in which carbon and nitrogen are introduced into the workpieces, and nitriding, in which only nitrogen is introduced.

[0003] In thermochemical treatment by carburizing and carbonitriding, the workpieces are kept at temperatures in the range of 800 to 1100 °C for a period of 30 minutes to several hours.

[0004] Thermochemical treatment typically involves batches of a few tens to a few hundred workpieces in specially designed systems with one or more lock, furnace, and quenching chambers. In exceptional cases, such as gear wheels with a diameter of more than 600 mm or machine parts with high precision requirements, the workpieces are treated serially (one-piece flow), with each individual workpiece undergoing each of the thermochemical processing steps in a treatment chamber.

[0005] Small components with non-critical manufacturing tolerances are often processed in bulk batches ranging from a few hundred to a few thousand workpieces. In contrast, larger and higher-value components are arranged in an orderly fashion on batch carriers to ensure controlled and as homogeneous process conditions as possible. In particular, the goal is to achieve a homogeneous temperature distribution and exposure of the workpieces to carbon- and nitrogen-containing process gases, as well as a uniform flow of quenching fluid around the workpiece surface.

[0006] The charge carriers are usually designed as grid-like grates and are made of a high-temperature-resistant material such as graphite, carbon fiber reinforced carbon (CFRC), or high-nickel steel. Manufacturing the charge carriers is complex and cost-intensive. To ensure cost-effective thermochemical treatment, the charge carriers are used for as long as possible, i.e., for treating numerous workpiece batches, and are exposed to high mechanical and thermal stress. Loading and unloading the charge carriers with workpieces results in mechanical abrasion. In addition, the numerous heating and quenching processes cause cumulative thermal distortion. The progressive mechanical and thermal stress leads to the surface of the charge carriers exhibiting minor unevenness and distortions after just a few production runs.

[0007] Depending on the steel grade, steel workpieces are forgeable, i.e., plastically deformable under the action of force, at temperatures in the range of 500 to 800 °C. For the purposes of the present invention, this temperature is referred to as the "softening temperature" or "softening point," in reference to plastics.

[0008] During carburizing and carbonitriding, the workpieces are regularly kept at a temperature above their “softening point” for a considerable period of time.

[0009] A workpiece resting on a charge carrier and heated above its "softening point" clings to the surface of the charge carrier under the influence of its own weight. If the surface of the charge carrier is sufficiently flat, so that the local curvature is very small or the local radius of curvature is very large compared to the dimensions of the workpiece, the heat treatment distortion of the workpieces is minor and lies within specified tolerances. However, if the surface of the charge carrier has one or more irregularities with significant curvature or a radius of curvature below a critical limit, the heat treatment distortion of the workpieces can exceed the tolerances and cause a significantly increased scrap rate.

[0010] Methods and devices for hardening and / or heat treating workpieces are disclosed, for example, in KR 10 1994 0 011 706 B1, CN 201 581 117 U, DE 10 2009 041 041 A1, EP 3 144 622 A1, DE 103 12 802 B3, JP H05 - 96 048 U and US 3 314 666 A.

[0011] The present invention has the object of providing a device for reducing dimensional and shape changes or distortion of metallic workpieces during thermochemical treatment.

[0012] This object is achieved by a device for supporting metallic workpieces during thermochemical treatment, comprising a ring with a first and second end face, wherein the first end face has a flat support surface, the second end face is equipped with 20 to 100 support elements, the support elements delimit a support plane which is plane-parallel to the support surface, the ring and the support elements are formed in one piece, the ring has a cross section with an inner circle with a diameter D i and an outer circle with diameter D a , where the difference in diameter D a - D i 4 to 400 mm (4 mm ≤ D a - D i ≤ 400 mm), each support element has a flat support surface, the sum of the support surfaces of all support elements is 10 to 40% of the area π4(Da2−Di2) and the support surfaces of the support elements have a flatness (axial runout) of ≤ 10 µm.

[0013] Advantageous embodiments of the device according to the invention are set out below.

[0014] Device as described above, wherein the support elements are designed as webs.

[0015] Device as described above, wherein the support elements are designed as circular webs.

[0016] Device as described above, wherein the support elements are designed as radial webs.

[0017] Device as described above, wherein recesses are arranged between adjacent support elements.

[0018] Device as described above, wherein grooves are arranged between adjacent support elements.

[0019] Device as described above, wherein the second end face has circular recesses.

[0020] Device as described above, wherein the second end face has circular grooves.

[0021] Device as described above, wherein the second end face has radial recesses.

[0022] Device as described above, wherein the second end face has radial grooves.

[0023] Device as described above, wherein the second end face has circular and radial recesses.

[0024] Device as described above, wherein the second end face has circular and radial grooves.

[0025] Device as described above, wherein the support elements are designed as round bars.

[0026] Device as described above, wherein the ring has a circular or polygonal cross-section.

[0027] Device as described above, wherein the ring is made of graphite or carbon fiber reinforced carbon (CFRC).

[0028] Device as described above, wherein the support elements are made of graphite, carbon fiber reinforced carbon (CFRC), oxide ceramic fiber composite material (OCMC) or another ceramic material.

[0029] Device as described above, wherein a surface of the support elements is provided with particles of a ceramic material and the particles have an equivalent diameter in the range of 5 to 1000 nm.

[0030] Device as described above, with channels for the passage of fluids which connect the first and second end faces.

[0031] Device as described above, wherein the channels are formed as bores.

[0032] Device as described above, wherein the support elements are round bars with a circular cross-section with a diameter D s are formed, the receptacles are designed as grooves and have a cross-section in the form of an isosceles triangle with a base side of length c and an apex angle γ, the apex angle γ is in the range of 60° to 120° (60° ≤ γ ≤ 120°) and the length c has the relation D s cos(γ / 2) < c < D s · cot(45°-γ / 4) is fulfilled.

[0033] Device as described above, wherein the support elements are round bars with a circular cross-section with a diameter D sare formed, the receptacles are designed as grooves and have a cross-section in the form of a symmetrical trapezoid with a long base side of length a and a short base side of length b, an angle ε included by the trapezoidal legs is in the range of 60° to 120° (60° ≤ ε ≤ 120°), the length a has the relation D s cos(ε / 2) < a < D s · cot(45°-ε / 4) and the length b satisfies the relation 0 < b < D s · cot(45°+ε / 4) is fulfilled.

[0034] Device as described above, wherein each support element has a flat support surface and the support surfaces of the support elements are of equal size.

[0035] Device as described above, wherein the mounting surface has a flatness (axial runout) of ≤ 10 µm.

[0036] Device as described above, wherein the second end face has a flatness (axial runout) of ≤ 10 µm.

[0037] Device as described above, wherein a distance between the support surface and a support plane delimited by the support elements is 10 to 200 mm.

[0038] Device as described above, wherein an average value of the diameters of the inner and outer circles of the cross section of the ring is in the range of 20 to 1000 mm (20 mm ≤ (D a + D i ) / 2 ≤ 1000 mm).

[0039] Device as described above, wherein each support element has a flat support surface and the sum of the support surfaces of all support elements is 10 to 30% of the area π4(Da2−Di2) amounts.

[0040] Device as described above, wherein each support element has a flat support surface and the sum of the support surfaces of all support elements is 10 to 20% of the area π4(Da2−Di2) amounts.

[0041] A further object of the invention is to provide a method for the thermochemical treatment of metallic workpieces with a reduced change in dimensions and shape or distortion compared to known methods.

[0042] This object is achieved by a method for the thermochemical treatment of one, two or more metallic workpieces, wherein each workpiece is designed as a gear wheel with a gear ring and a flange and an end face of the flange is supported by means of a device as described above, wherein 20 to 70% of the end face of the flange is in mechanical contact with the device.

[0043] Advantageous embodiments of the method according to the invention are set out below.

[0044] A method as described above, wherein the device comprises three or more support elements which are in mechanical contact with the workpiece.

[0045] A process as described above, wherein one, two or more workpieces are carburized together.

[0046] Process as described above, wherein one, two or more workpieces are carburized together at temperatures of 900 to 1050 °C.

[0047] Process as described above, wherein one, two or more workpieces are carburized together in a carbon-containing gas atmosphere with a pressure of less than 200 mbar.

[0048] Process as described above, wherein one, two or more workpieces are carburized together in a carbon-containing gas atmosphere with a pressure of less than 50 mbar.

[0049] A method as described above, wherein one, two or more workpieces are carburized together in a furnace chamber and one workpiece at a time is arranged in a vertical direction between an upper and lower wall of the heating chamber.

[0050] Process as described above, wherein one, two or more workpieces are carbonitrided together.

[0051] Process as described above, wherein one, two or more workpieces are carbonitrided together at temperatures of 800 to 1050 °C.

[0052] Process as described above, wherein one, two or more workpieces are carbonitrided together in a nitrogen-containing gas atmosphere with a pressure of less than 200 mbar.

[0053] A method as described above, wherein one, two or more workpieces are carbonitrided together in a furnace chamber and one workpiece at a time is arranged in a vertical direction between an upper and lower wall of the heating chamber.

[0054] A process as described above, wherein one, two or more workpieces are carburized and / or carbonitrided together and subsequently quenched together.

[0055] A method as described above, wherein one, two or more workpieces are quenched together by means of a gas.

[0056] A process as described above, wherein one, two or more workpieces are quenched together using nitrogen.

[0057] A process as described above, wherein one, two or more workpieces are quenched together by means of helium.

[0058] A process as described above, wherein one, two or more workpieces are quenched together using argon.

[0059] A method as described above, wherein one, two or more workpieces are quenched together by means of a gas under a pressure of 1 to 40 bar.

[0060] A method as described above, wherein one, two or more workpieces are quenched together by means of a gas under a pressure of 2 to 20 bar.

[0061] A method as described above, wherein one, two or more workpieces are quenched together in a quenching chamber and one workpiece at a time is arranged in a vertical direction between an upper and lower wall of the quenching chamber.

[0062] A method as described above, wherein one, two or more workpieces are quenched together by means of a liquid, such as an oil.

[0063] Method as described above, wherein one, two or more devices, each with a workpiece supported on the device, are arranged together on a carrier.

[0064] A process as described above, wherein the support is made of graphite, carbon fiber reinforced carbon (CFRC) or high nickel steel.

[0065] Method as described above, wherein the carrier is formed in a grid-like manner.

[0066] A method as described above, wherein each workpiece is formed as a gear wheel having a gear rim and a flange, and an end face of the flange is supported by the fixture, wherein 20 to 40% of the end face of the flange is in mechanical contact with the fixture.

[0067] A method as described above, wherein each workpiece is formed as a gear wheel having a gear rim and a flange, and an end face of the flange is supported by the fixture, wherein 30 to 50% of the end face of the flange is in mechanical contact with the fixture.

[0068] A method as described above, wherein each workpiece is formed as a gear wheel having a gear rim and a flange, and an end face of the flange is supported by the fixture, 40 to 60% of the end face being in mechanical contact with the fixture.

[0069] A method as described above, wherein each workpiece is formed as a gear wheel having a gear rim and a flange, and an end face of the flange is supported by the fixture, wherein 50 to 70% of the end face of the flange is in mechanical contact with the fixture.

[0070] Method as described above, wherein the workpieces are designed as gears and have a gear ring and a flange with outer diameter D 2 include.

[0071] Method as described above, wherein the device is designed as a ring and a diameter D a an outer circle of a cross-section of the ring smaller than the outer diameter D 2 of the flange of the gears.

[0072] Method as described above, wherein the device is designed as a ring and a diameter D aan outer circle of a cross-section of the ring 50 to 99% of the outer diameter D 2 of the flange of the gears is (0.5 D 2 ≤ D a ≤ 0.99 D 2 ).

[0073] Method as described above, wherein the device is designed as a ring and a diameter D a an outer circle of a cross-section of the ring 60 to 99% of the outer diameter D 2 of the flange of the gears is (0.6 D 2 ≤ D a ≤ 0.99 D 2 ).

[0074] Method as described above, wherein the device is designed as a ring and a diameter D a an outer circle of a cross-section of the ring 70 to 99% of the outer diameter D 2 of the flange of the gears is (0.7 D 2 ≤ D a ≤ 0.99 D 2 ).

[0075] Method as described above, wherein the device is designed as a ring and a diameter D a an outer circle of a cross-section of the ring 80 to 99% of the outer diameter D 2 of the flange of the gears is (0.8 D 2 ≤ D a ≤ 0.99 D 2 ).

[0076] Method as described above, wherein the device is designed as a ring and a diameter D a an outer circle of a cross-section of the ring 90 to 99% of the outer diameter D 2 of the flange of the gears is (0.9 D 2 ≤ D a ≤ 0.99 D 2 ).

[0077] Method as described above, wherein the workpieces are designed as gears with a gear rim and a flange and a distance T between a first and second end face of the device is greater than a distance ΔH between an end face of the flange and an end face of the gear rim adjacent thereto.

[0078] The invention makes it possible to support each workpiece in a planar or flat manner during thermochemical treatment, significantly reducing dimensional and shape changes and distortion. The device according to the invention is simple in design and can be manufactured with little effort. Furthermore, the device is resistant to high temperatures, mechanically robust, and designed for a long service life. In preferred embodiments of the invention, the contact area between the workpiece and the device, relative to the support surface, is small, thus ensuring an intensive and largely conformal flow of a quenching fluid, such as nitrogen or oil, over the workpiece surface. Furthermore, the device is preferably designed such that the supported workpiece surface is practically completely carburized. This reliably prevents a "shielding effect," also known as "masking," for the carbon during low-pressure carburization.

[0079] The flatness or axial runout of the device according to the invention is determined in accordance with DIN EN ISO 12181-1:2011-07 and DIN EN ISO 12181-2:2011-07 using a gear inspection system or a coordinate measuring system.

[0080] The invention is explained in more detail below with reference to figures and examples. Identical, similar and / or functionally identical parts are provided with the same reference numerals. Fig. 1, Fig. 3 schematic plan views and sectional views of devices according to the invention; Fig. 2 a schematic plan view and sectional view of a device not according to the invention; Fig. 4 a perspective view of a device according to the invention; Fig. 5 a gear supported according to the invention; Fig. 6 a device not according to the invention with cylindrical support elements; Fig.7 - 8 Sectional views of support elements not according to the invention mounted in recesses.

[0081] Fig. 1 shows a schematic top view and a sectional view of a device 1 according to the invention, comprising a ring 2 with a first end face 2A and a second end face 2B. Circular support elements 3 are arranged on the second end face 2B. Each pair of support elements 3 is separated from one another by a circular recess or groove 5. The first end face 2A is delimited by a flat surface or support surface. The support elements 3 are designed such that at least three points on the surface of each support element 3 are arranged at a vertical distance T from the support surface of the first end face 2A, and a vertical distance of each point on the surface of the support elements 3 from the support surface of the first end face 2A is less than or equal to T. The support elements 3 delimit a support plane 4.

[0082] The Ring 2 of the Fig. The device 1 shown in Figure 1 essentially has the shape of a circular cylinder with an outer and inner circle with diameter D a and respectively D i . The Fig. The device 1 shown in Figure 1 is formed in one piece and made of a high-temperature-resistant material, such as graphite or carbon fiber reinforced carbon (CFRC).

[0083] The device 1 is expediently manufactured by machining, in particular by turning or circular milling and, if necessary, linear milling, from plates or cylindrical discs made of graphite or carbon fiber reinforced carbon (CFRC).

[0084] Fig. 2 shows a schematic plan view and a sectional view of a device 1 not according to the invention with a disc 2. Apart from the disc 2, the Fig. 2 shown device 1 in the same way as that of Fig. 1 trained.

[0085] Fig. 3 shows a further device 1 according to the invention with a ring 2 and support elements 3, which are separated from each other by circular recesses 5 and radial recesses 6.

[0086] Fig. Figure 4 shows a schematic perspective view of a device 1 with a circular ring 2 with an outer circle of diameter D a and an inner circle with diameter D i and support elements 3, which are separated from each other by circular and radial grooves 5 and 6, respectively.

[0087] Fig. 5 shows a perspective full and sectional view of a gear 10 supported on a device 1 with a gear rim 11 and a flange 12. The Fig. The device 1 shown in Figure 5 is designed in the same way as that of Fig. 4. The diameter D a of an outer circle of the device 1 is smaller than an outer diameter D 2of the flange 12. The outer diameter of the flange 12 is smaller than or equal to the inner diameter of the gear ring 11. Only one end face of the flange 12 is supported by support elements 3 of the device 1. However, the support elements 3 are not in contact with the gear ring 11. Furthermore, Fig. 5 shows a grid-shaped support 20 on which the device 1 with the gear 10 is arranged. The support 20 is usually made of graphite or carbon fiber reinforced carbon (CFRC).

[0088] A thickness or a distance T between a support surface facing the carrier 20 and a support plane of the device 1 facing the gear 10 is greater than a distance ΔH between lower end faces of the gear ring 11 and the flange 12. This ensures that the gear 10 does not touch the carrier 20.

[0089] Fig.Figure 6 shows schematic perspective views of a device 1 not according to the invention in a simple representation and in the manner of an exploded view. The device 1 comprises a ring 2 with receptacles or bearings 7 for cylindrical support elements 3. The receptacles or bearings 7 are designed as radially oriented grooves with a trapezoidal cross-section. In an alternative, in Fig. In the embodiment of the device 1 not shown in Figure 6, a longitudinal axis of the receptacles or bearings 7 is rotated by an angle of up to 45 degrees relative to the respective radial direction in a plane parallel to the support surface of the ring 2. Preferably, the cylindrical support elements 3 are made of a high-temperature-resistant material, such as graphite, carbon fiber reinforced carbon (CFRC), oxide ceramic fiber composite material (OCMC), or another ceramic material.

[0090] Fig.7 shows a sectional view of a device not according to the invention with a ring 2 with a receptacle 7 for a cylindrical support element 3 with outer diameter D s . The receptacle 7 is designed as a groove with a cross-section in the shape of an isosceles triangle. A base side of the isosceles triangle has a length c, and an apex angle γ opposite the base side lies in the range of 60° to 120° (60° ≤ γ ≤ 120°). The receptacle 7 is designed such that a support element 3 mounted in the receptacle 7 projects beyond an end face 2' of the ring 2. Accordingly, the length c satisfies the relation D s cos(γ / 2) < c < D s · cot(45°-γ / 4).

[0091] Fig. 8 shows a sectional view of a further device not according to the invention with a ring 2 with a receptacle 7 for a cylindrical support element 3 with outer diameter D s. The receptacle 7 is designed as a groove with a cross-section in the shape of a symmetrical trapezoid. A long and short base side of the symmetrical trapezoid have a length a and b, respectively. An angle ε enclosed by the trapezoidal legs lies in the range of 60° to 120° (60° ≤ ε ≤ 120°). The receptacle 7 is designed such that a support element 3 mounted in the receptacle 7 projects beyond an end face 2' of the ring 2. Accordingly, the lengths a and b satisfy the relations Ds⋅cos(ε / 2) <a<Ds⋅cot(45°−ε / 4) and respectively 0 <b<Ds⋅cot(45°+ε / 4). Example

[0092] 72 untreated steel gear wheels with a shape as shown in Fig.5, with a gear rim with a 378 mm tip diameter, a flange, and an internal bore. For each of the transmission gears, the radial runout (i.e., the circular radial runout tolerance) at the tip diameter (or the outer tooth flanks) and the axial runout (i.e., the circular axial runout tolerance) on an end face of the gear rim were measured in accordance with DIN EN ISO 12181-1:2011-07 and DIN EN ISO 12181-2:2011-07. The measurements were performed on a Gleason 300 GMS P gear inspection system.

[0093] After the measurement, the gear wheels were heated in a ModulTherm system ®The parts were carburized at 950 °C under low pressure at approximately 15 mbar by ALD and subsequently quenched using compressed nitrogen. The duration of the thermochemical treatment, including the process steps of heating, carburizing, diffusion, and quenching, was 2 hours. 36 of the 72 gear wheels were mounted on devices according to the invention throughout the entire process. As shown in Fig. As shown in Figure 5, the flange of each of the 36 gear wheels was supported by a graphite ring equipped with circular and radial support webs, with the entire gear ring projecting freely in the radial direction over the graphite ring.

[0094] The remaining 36 gear wheels were placed in the conventional manner directly on the lattice-shaped carrier made of carbon fiber reinforced carbon (CFRC).

[0095] After the thermochemical treatment, the radial and axial runout of each of the 72 gears was measured again. The mean values ​​of the measurement results after the thermochemical treatment are shown in Table 1. Table 1 Mean value after thermochemical treatment Concentricity Plan run without support (36 parts) 62 µm 71 µm with support (36 parts) 46 µm 40 µm

[0096] It can be seen from Table 1 that with the support according to the invention, the radial and axial distortion of the 36 gear wheels supported according to the invention and the associated increase in the radial and axial runout fluctuations due to the thermochemical treatment are 26% and 44% lower, respectively, compared to the 36 gear wheels placed directly on the carrier. List of reference symbols 1 support device 2 disc or ring 2' End face of the disc or ring 2 2A first front side / footprint of device 1 2B second end face of the device 1 3 Support element 4 support levels 5 circular recess 6 radial recess 7 Holder for support element 3 10 gear 11 sprocket 12 Flange 20 carriers T Distance between first end face 2A and support surface 4 D i Diameter of the inner circle of ring 2 D a Diameter of the outer circle of the disc or ring 2 D 2 Outer diameter of the flange 12 ΔH Height difference between gear rim 11 and flange 12 D s Diameter of cylindrical support elements 3 c Base of a triangular cross-section of a recording 7 γ apex angle of a triangular cross-section of a recording 7 a long base side of a trapezoidal cross-section of a receptacle 7 b short base side of a trapezoidal cross-section of a receptacle 7 ε apex angle of a trapezoidal cross-section of a recording 7

Claims

[1] Device (1) for supporting metallic workpieces (10) during thermochemical treatment, comprising a ring (2) with a first and second end face (2A, 2B), wherein the first end face (2A) has a flat support surface, the second end face (2B) is equipped with 20 to 100 support elements (3), the support elements (3) delimit a support plane (4) which is plane-parallel to the support surface, the ring (2) and the support elements (3) are formed in one piece, the ring (2) has a cross section with an inner circle with a diameter D i and an outer circle with diameter D a , where the difference in diameter D a - D i 4 to 400 mm, each support element has a flat support surface, the sum of the support surfaces of all support elements is 10 to 40% of the area π4(Da2−Di2) and the support surfaces of the support elements (3) have a flatness of ≤ 10 µm. [2] Device (1) according to claim 1, characterized by that the support elements (3) are designed as webs. [3] Device (1) according to claim 1 or 2, characterized by that the ring (2) and the support elements (3) are made of graphite or carbon fiber reinforced carbon, CFRC. [4] Device (1) according to one or more of claims 1 to 3, characterized by that a surface of the support elements (3) is equipped with particles of a ceramic material and the particles have an equivalent diameter in the range of 5 to 1000 nm. [5] Process for the thermochemical treatment of one, two or more metallic workpieces (10), characterized bythat each workpiece (10) is designed as a gear wheel with a gear ring (11) and a flange (12) and an end face of the flange (12) is supported by means of a device (1) according to one or more of claims 1 to 4, wherein 20 to 70% of the end face of the flange (12) is in mechanical contact with the device (1). [6] Method according to claim 5, characterized by that one, two or more workpieces (10) are carburized together in a furnace chamber and one workpiece (10) is arranged in a vertical direction between an upper and lower wall of the heating chamber. [7] Method according to claim 5, characterized by that one, two or more workpieces (10) are carbonitrided together in a furnace chamber and one workpiece (10) is arranged in a vertical direction between an upper and lower wall of the heating chamber. [8] Method according to claim 5, 6 or 7, characterized bythat one, two or more workpieces (10) are quenched together in a quenching chamber and one workpiece (10) is arranged in a vertical direction between an upper and lower wall of the quenching chamber.

Images