Device and method for plasma treatment of metal surfaces

Abstract

The invention relates to a device and a method for the stable plasma treatment of components, in particular large components having a single weight of between 500 kilograms and 40 tons, said device comprising a treatment chamber in the form of a horizontal cylinder having at least one side cylinder cover, and a special sealing system, said special sealing system comprising at least one side cylinder cover and at least one side cylinder cover. The apparatus and method enable stable plasma processing of such parts, in particular large tools, such as large forming tools.

Description

Technical Field

[0001] The present invention relates to plasma treatment of metal surfaces, in particular metal surfaces of large components, in order to produce large components with modified metal surfaces. Background Art

[0002] The components within the scope of the present invention generally refer to any parts or substrates with a metal surface, wherein large components particularly refer to components weighing in the range of 500 kilograms to 40 tons (ie, 500 kg to 40 t).

[0003] Accordingly, within the scope of the present invention, the term “component” is used not only for tools and tool parts, but also for components.

[0004] The plasma treatment according to the invention can be used in particular for modifying the metal surfaces of tools which are used in manufacturing processes such as forming or plastic processing, such as injection molding (also known in English as "Plastic Injection" or "Injection Moulding") and flow pressing processes (in flow pressing processes, in particular long fiber-reinforced thermosetting plastic semi-finished products with a modified metal surface can be used, also referred to as SCM according to their English name "Sheet Molding Compound").

[0005] An important field of application for such components with modified metal surfaces is in forming technology, in particular in the processing of products for the automotive industry. Known products that undergo such processing are, for example, outer skin parts or structural parts for the automotive industry (e.g. doors, covers, side walls, engine hoods). Such forming tools (hereinafter also referred to as tool parts) can weigh, for example, 500 kg to 40 tons per tool part. Therefore, such forming tools are also referred to as large parts in this specification.

[0006] Parts or large components with modified metal surfaces also include those molds that are processed for applications in the plastics industry, such as for processing bumpers, car headlights, plastic parts for interior and exterior of cars and household appliances.

[0007] Within the scope of this description, large components such as gears, rollers and disks can also be treated to produce modified metal surfaces.

[0008] However, the above-mentioned components or large components with modified metal surfaces are merely examples of large components within the scope of the present invention, and therefore should not be considered as limiting the application of the device or method of the present invention to plasma treatment of metal surfaces.

[0009] Depending on the application, different requirements are placed on the component surface.

[0010] For example, in the case of forming tools for metal forming, the requirements are quite high and should at least meet the following requirements:

[0011] High hardness,

[0012] High corrosion resistance and wear resistance,

[0013] Low friction coefficient,

[0014] Fatigue resistance,

[0015] Polishing ability,

[0016] ·Repair capability (repair).

[0017] In the bodybuilding sector, the general trend is to reduce lubricant use, especially during forming, and vehicle weight. The limited use of lubricants, combined with the introduction of high-strength sheet materials and ultra-high-strength sheet materials, leads to continuously increasing requirements on forming tools with regard to improved wear resistance.

[0018] In the past, wear in punching operations was limited by additionally increasing the amount of lubricant in the lubrication of the coil or sheet (using additional lubricants) in order to prevent wear (especially adhesive wear).

[0019] However, high-efficiency lubricating oils usually contain chlorinated paraffin as an extreme pressure additive, which is relatively toxic and has adverse effects on the environment. Therefore, its application has been greatly limited so far, and the trend is to minimize lubrication (minimize additional lubricants).

[0020] Therefore, appropriate surface treatment is useful to protect the tool surface from wear.

[0021] In the case of sheet metal forming, adhesive wear is the main wear mechanism. This type of wear consists in principle of the following stages:

[0022] The sheet material begins to transfer locally to the tool surface,

[0023] The gradual accumulation of migration layers (sheet metal wear debris generated on the tool surface during the sheet forming process) and subsequent abrasive wear on the sheet,

[0024] Transformed into severe adhesive wear.

[0025] Zumkeller et al. in WO 2012 / 072209 A1 disclose a good solution for improving the corrosion resistance of metal surfaces and protecting them from wear, namely nitriding these metal surfaces.

[0026] WO2012 / 072209A1 mentions as In particular, Zumkeller et al. describe in WO 2012 / 072209 A1 a special nitriding process. A special implementation of the process that increases the performance of processed plastic components.

[0027] In this regard, reference is made to patent application WO 2012 / 072209 A1, the content of which is now incorporated into the present application.

[0028] It is known that corrosion resistance and wear resistance can be increased by means of plasma nitriding, in which the substrate to be nitrided is exposed to a plasma containing hydrogen and nitrogen ions under vacuum conditions. It is also known to carry out nitriding using pulsed plasma. Pulsing likewise offers a number of advantages: On the one hand, the process temperature can be selected within a wide range depending on the power coupling by controlling the pulse duration, without having to change other process parameters, such as the inter-electrode voltage; on the other hand, the generation of sparks during the nitriding process can be substantially prevented by means of pulsing.

[0029] Nitriding is carried out by the diffusion of nitrogen to the surface of the parent material, thereby forming a nitrided zone, in which the nitrogen near the surface forms a compound with the workpiece material, or at a deeper level, the nitrogen (in addition to forming nitrides with alloying elements) forms an interstitial solid solution with the parent material. Therefore, the nitrided zone is generally composed of a compound layer and a diffusion zone. In the compound layer, there are mainly nitride compounds. In the case of an iron-containing substrate, for example, ε-nitride (=Fe 2(3) N) and / or γ-nitride (=Fe4N).

[0030] The present invention is directed to improving the plasma nitridation process to efficiently and reliably produce components with optimally modified metal surfaces for different applications.

[0031] This improvement is an improvement over the one described in WO 2012 / 072209 A1 Further development of the plasma nitridation process. Summary of the invention

[0032] The object of the present invention is to provide a device (hereinafter also referred to as an apparatus) for plasma surface treatment (especially nitridation) of components, which is suitable for processing large components, wherein the device should include a processing chamber that can avoid or completely eliminate common problems in the sealing process of large processing chambers.

[0033] Therefore, this is particularly difficult because a very large processing chamber 200 needs to have a sufficiently large opening 250 (see Figure 1 and 3) to load the corresponding size of the parts to be processed. For example, the equipment built by the applicant is in the shape of a horizontal cylinder with a length of 10 meters and a diameter of 4.2 meters. Therefore, through the cylinder (whose cover 150 is a removable design, see Figure 3 ) bottom surface 100, heavy parts can be fed into the processing equipment, such as side wall tools made of cast iron or steel, with dimensions of length (L≤10 meters)×width (B≤2.9 meters), and a single piece weight of up to 40 tons. Therefore, when the cover is closed, the circumference (π×D, i.e., about 3.14×4.2 meters=13 meters) must be vacuum-tightly sealed. The applicant has protected the appearance of such equipment in European design application number 002071415.

[0034] The present invention aims to solve this sealing problem.

[0035] Another object of the present invention is to provide a method for avoiding or effectively controlling arc discharge or spark breakdown (also known as “plasma breakdown” in English “Arcing”) commonly seen in plasma treatment processes.

[0036] The plasma treatment process can be carried out, for example, at an operating voltage of up to approximately 1000 V (ie approximately 1 kV), wherein a pressure value of, for example, between 0.5 mbar and 4.5 mbar, for example 1.9 mbar, is usually set for carrying out the process.

[0037] In the context of these process parameters, and depending in particular on the geometry of the component to be treated, the temperature distribution and the unavoidable outgassing due to contaminants that cannot be removed, plasma breakdown can sometimes occur, manifesting itself as localized lightning that can damage the component to be treated, especially at the point of impact.

[0038] The present invention also aims to solve this problem.

[0039] The underlying object of the present invention is therefore to specify a surface treatment device (in particular a device for plasma treatment of substrates) by means of which large workpieces to be treated (also referred to as large components to be treated) can be subjected to plasma treatment, wherein in the device:

[0040] - by means of the measures of the invention, the negative pressure required for the treatment can be generated and stably maintained, and

[0041] - The steps of the present invention can be taken to prevent plasma breakdown from frequently occurring on the parts to be treated. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The object of the invention is achieved by providing a device according to claim 1 and a method according to claims 2 to 7 .

[0043] Figure 1A perspective view showing the exterior appearance of an apparatus constructed by the applicant, wherein the process chamber is in a closed state.

[0044] FIG. 2 is a schematic diagram showing a solution of the present invention to the above-mentioned sealing problem.

[0045] Figure 3 Shown with Figure 1 A perspective view of the exterior of the same device is shown, wherein the process chamber is in an open state and the cover of the process chamber has been correspondingly separated from the rest of the process chamber.

[0046] Reference numerals:

[0047] 1. Sealing element (inner sealing ring in inner sealing groove 3 and outer sealing ring 1 in outer sealing groove 2);

[0048] 2 External sealing groove;

[0049] 3 inner sealing groove;

[0050] 4 middle slot;

[0051] 6 (in the outer sealing groove 2) a sealing lip on the outer sealing ring 1 facing the external environment 10, and (in the inner sealing groove 3) a sealing lip on the inner sealing ring 1 facing the inner cavity 20 of the processing chamber;

[0052] 7 (in the outer sealing groove 2) the sealing lip on the outer sealing ring 1, and (in the inner sealing groove 3) the sealing lip on the inner sealing ring facing the auxiliary vacuum chamber 40;

[0053] 8 the annular surface of the chamber, the front side of each sealing member 1 being pressed against the annular surface;

[0054] 10 External environment (also called external environment atmosphere or external environment);

[0055] 20 treatment chamber inner cavity;

[0056] 30 pressurized chamber (inner groove area of ​​the sealing groove);

[0057] 40 A vacuum chamber or an auxiliary vacuum chamber in a sealing system;

[0058] 100 bottom surface, on which the parts to be processed are loaded;

[0059] 150 A removable cartridge cover for the treatment chamber;

[0060] 200 horizontal cylindrical treatment chamber;

[0061] 250 Opening of the processing chamber. DETAILED DESCRIPTION

[0062] The special seal 1 is placed in the outer sealing groove 2 and the inner sealing groove 3. The seal is not an inflatable seal. The rear sealing lips 6 and 7 of the seal 1 are pressed against the sealing wall of the groove only by applying gas (such as nitrogen) and with their front side against the device flange (or the annular surface 8 of the device flange).

[0063] The vacuum generated in the auxiliary vacuum chamber 40 or vacuum chamber 40 is also called auxiliary vacuum because it assists the sealing at the sealing lip 7. The sealing lip 7 is pulled toward the groove by the vacuum in the vacuum chamber 40, thereby assisting the sealing in the vacuum chamber 40.

[0064] The device (equipment) according to the present invention comprises a cylindrical treatment chamber for plasma-assisted surface treatment of large components, wherein the cylindrical treatment chamber has a bottom surface, through which the large components to be treated can be loaded and fixed, and the treatment chamber is constructed in the form of a horizontal cylinder, which has at least one lateral cylinder cover that can be opened and vacuum-tightly closed, wherein the cylinder cover is arranged at one of the two ends of the horizontal cylinder, and the circumference of the cylinder cover is at least 8m, preferably between 10 meters and 15 meters, so that when the cylinder cover is open, the components to be treated can be loaded into the treatment chamber through the lateral opening, and the cylinder cover comprises an annular cover sealing surface opposite to the cylinder remainder, and the cylinder remainder comprises an annular cylinder remainder sealing surface opposite to the cover sealing surface, wherein, in order to seal at the sealing surface to achieve vacuum-tight closure, the following sealing system is provided, that is, a plurality of grooves (preferably three grooves in total) are milled on one of the sealing surfaces, so that the following conditions are met:

[0065] · Realize a first annular groove, hereinafter also referred to as outer groove 2 (or sealing groove 2),

[0066] · Realize a second annular groove, also referred to below as inner groove 3 (or sealing groove 3),

[0067] The diameter of the circle represented by the inner groove is smaller than the diameter of the circle represented by the outer groove,

[0068] A third groove is provided between the outer groove 2 and the inner groove 3, hereinafter also referred to as the middle groove 4,

[0069] The circle represented by the middle groove is smaller than the circle represented by the outer groove,

[0070] The circle represented by the middle groove is larger than the circle represented by the inner groove,

[0071] The three grooves are formed in a mutually non-intersecting manner around a center point, preferably the same center point,

[0072] The outer groove and the inner groove are respectively provided with sealing rings 1 extending around the grooves.

[0073] At least one of the sealing rings 1, but preferably both sealing rings, has a shape such that when the cover is pressed against the annular surface of the rest of the chamber, the planar sealing surface is compressed, and the sealing ring has an outward sealing lip (also called the outward flange of the sealing ring) and an inward sealing lip (also called the inward flange of the sealing ring) in the groove depth direction, and these sealing lips are close to the groove wall, and

[0074] ·The arrangement is designed in the following way: when the sealing surface of the cover and the sealing surface of the rest of the barrel are pressed against each other, a gap space system is formed, and the gap space system is closed relative to the external environment 10 and relative to the inner cavity 20 of the barrel of the device (that is, the chamber or the processing chamber or the vacuum processing chamber), wherein the gap space system includes two pressurized chambers 30 and one vacuum chamber 40, and a so-called auxiliary vacuum is generated in the vacuum chamber 40, and wherein the sealing system includes a mechanism for applying an overpressure of at least 0.1 mbar to 1 mbar (that is, 0.1 mbar to 1 mbar), preferably at least 0.1 bar, more preferably at least 0.2 bar, and more particularly preferably at least 0.3 bar to the pressurized chamber 30.

[0075] The pressurization does not use a gas pressure system (no compressed air), because such a system may bring many adverse effects, such as oxygen in the air entering the process chamber, which may lead to poor nitriding results. Therefore, according to the present invention, a specified gas (or gas mixture) is applied to the pressurization chamber, wherein the gas or gas mixture does not contain oxygen. Preferably, nitrogen between 0.1 mbar and 1 mbar is applied to the pressurization chamber.

[0076] The device according to the invention therefore comprises, according to a first aspect of the invention, a cover which is sealed as described above by means of a sealing system. At the position where the cover is pressed against the treatment chamber, the chamber has a torus, for which a mating surface is provided in the cover. A first annular groove is milled in the surface of the cover, which is also referred to as the outer groove 2 (also referred to as the sealing groove 2) in this specification. A second annular groove is also milled in the surface of the cover, which is also referred to as the inner groove 3 (also referred to as the sealing groove 3) in this specification. The diameter of the circle represented by the inner groove is smaller than the diameter of the circle represented by the outer groove. A third groove is provided between the outer groove and the inner groove, which is also referred to as the middle groove 4 in this specification. The circle represented by the middle groove is smaller than the circle represented by the outer groove. However, the circle represented by the middle groove is larger than the circle represented by the inner groove. All three grooves (inner groove, middle groove and outer groove, respectively) are substantially around the same center, so they do not intersect each other.

[0077] Sealing rings 1 are respectively arranged around the inner side of the outer groove and the inner groove. At least one of the sealing rings 1, but preferably both sealing rings have the following shape: when the cover is pressed against the annular surface of the remaining chamber, the flat sealing surface is pressed, and in the groove depth direction, the sealing ring has an outward flange and an inward flange, which are close to the groove wall.

[0078] In the diagram shown in Fig. 2, a partial cross section of such a combination of a cover and a processing chamber is shown. It is clear here that, due to the seal 1 provided in the outer groove 2 and the inner groove 3, a cavity system is formed between the grooves, which is isolated and sealed from both the external environment 10 and the indoor cavity 20, and includes three cavities (two pressurized cavities 30 and one vacuum cavity 40), wherein the vacuum cavity 40 includes the middle groove 4.

[0079] In this specification, the vacuum chamber 40 is also referred to as an auxiliary vacuum chamber 40 .

[0080] According to an important feature of the invention in this respect, the processing device includes a mechanism for applying an overpressure gas to each pressurized chamber. According to the invention, the above-mentioned mechanism includes at least one gas supply source, preferably a nitrogen supply source, so that each pressurized chamber can be applied with a gas, preferably nitrogen, having an overpressure of 0.1 mbar to 1 mbar, for example 0.3 mbar. By applying to the special seal 1 (a seal that is not an inflatable seal and is preferably designed to be placed in the outer sealing groove 2 and the inner sealing groove 3 as described above), the respective rear sealing lips 6 and 7 of the sealing ring 1 are pressed onto the sealing wall 10 of the corresponding groove 2, 3, and the seal 1 is simultaneously pressed toward the processing chamber, so that the sealing ring 1 is significantly more effectively and better pressed to the annular surface 8 of the chamber.

[0081] The flange (sealing lip) of the seal ring prevents the nitrogen from continuing to flow in a manner similar to a valve disc.

[0082] According to a preferred embodiment, the overpressure is applied to the pressurized chamber at least twice: at the beginning of the evacuation step in order to position the sealing ring substantially sufficiently in advance, and at the end of the evacuation process, i.e., when no mechanical displacements occur during the evacuation process due to forces acting on the device and the seal and in particular the flange (sealing lip) and / or the flat component should finally be in the correct position. A vacuum, i.e. an auxiliary vacuum, is generated in the intermediate groove.

[0083] Then, nitrogen gas is applied only to the pressurizing chamber 30 (the seal member 1 in the outer tank 2 and the inner tank 3 ), and the outer tank 4 is in a vacuum state.

[0084] According to another aspect of the present invention, a method is proposed to suppress or at least reduce the above-mentioned spark discharge phenomenon that is harmful to the substrate.

[0085] The method is carried out in the above-mentioned device (also called apparatus or plasma treatment device), which includes a powerful pulsed plasma generator with an integrated automatic safety control system, so that precise control of the process and reliable treatment of the components to be treated are ensured.

[0086] Despite very high processing powers of up to 1000 kW, the temperature gradients during heating (up to 530°C) and cooling can be adjusted as desired, so that even with the largest dimensions, internal component stresses (tool stresses in the case of tools) remain low or can even be eliminated. In addition, not only do extremely high pulse powers contribute to optimal processing results, but the plasma control, which reacts very quickly in the range of a few hundredths of a second, ensures an extremely careful interaction between the high-energy plasma and the functional surfaces of the component (e.g., tool functional surfaces). By combining arc management (management of arc discharges or sparkovers) of the plasma source with a controlled system control, a reliable response is achieved in the event of a sparkover and the surface of the processed substrate (e.g., a forming tool) is thus protected from damage.

[0087] The device is operated at a predetermined typical operating voltage. According to the applicant, this is generally a maximum of 1000 V. In the case of frequent spark discharges (for example, spark discharges in the range of 7 to 25 times within a time interval of 250 milliseconds), the inventors surprisingly found that in many cases, a sudden reduction in the operating voltage, for example, to a voltage value in the range of 10 V to 100 V, preferably 10 V to 70 V (such as a sudden drop in the operating voltage of 50 V), so that the spark discharge phenomenon stops, to be precise, even if the operating voltage is then slowly (i.e. for a period of more than 1 minute) and in stages restored to the initial value of the operating voltage. In addition, the device is operated at a predetermined operating pressure of X millibars. In this example, it is generally 1.9 millibars. The inventors further surprisingly found that a step-by-step increase or decrease in pressure can also help to reduce the spark discharge phenomenon. For example, the pressure can be increased from 1.9 mbar to 2.5 mbar in 6 steps of 0.1 mbar or decreased from 1.9 mbar to 1.0 mbar in 9 steps of 0.1 mbar. Despite the parameter changes, the system continues to operate stably. Then, it can be slowly restored to the typical operating pressure at a later time.

[0088] The inventors have determined that an operating voltage drop, in particular a voltage value in the above-mentioned preferred range (10 V to 70 V), brings the advantage that the risk of plasma extinguishing is lower (depending on the load and process parameters).

[0089] The inventors have proposed the following hypothesis: a sudden change in conditions within the device, at least involving voltage and pressure, can eliminate the prerequisites for the occurrence of spark discharges, so that they no longer occur.

[0090] According to another aspect of the invention, the method is improved in that a cleaning step is added under pre-vacuum before the plasma ignition, wherein the cleaning step includes plasma-free heating in such a way that oil and dirt on the substrate are cracked before the plasma ignition, so that no pre-annealing of the component is required.

[0091] This is primarily to avoid the otherwise unavoidable but in principle harmful preliminary annealing treatment (also called pre-annealing), which is accompanied by heating and cooling slopes that are usually too steep and therefore carry inherent stress risks. More importantly, the harmful surface and grain boundary oxidation that can be caused by pre-annealing (always carried out in air) is avoided, which can only be eliminated to a limited extent even by costly intermediate polishing. In addition, the elimination of pre-annealing reduces the risk of material growth, which is particularly important in the case of thermodynamically unstable pearlitic cast iron types.

[0092] In order to achieve the most reliable treatment results, the improved method is carried out in such a way that oil, residual paint and plastic in the component to be treated (such as a forming tool) are cracked in a plasma-free heating process and condensed in the low-temperature area.

[0093] Here, careful and controlled heating of the tool is achieved by measuring the temperature in the component to be treated and implementing an optimized ramp function. This is followed by a plasma step, which can be easily started thanks to the preceding inventive step (cleaning step in plasma-free heating) and quickly and evenly covers the tool surface, thus achieving a uniform heat input.

[0094] According to another aspect of the invention, the method is developed in such a way that the occurrence of hydrogen embrittlement is significantly reduced by adjusting the process gas composition.

[0095] A key issue in plasma surface treatment of metal surfaces is hydrogen embrittlement. This refers to the phenomenon that hydrogen enters and deposits in the metal lattice, causing changes in the strength of the metal. Because large components to be treated (such as forming tools) usually have areas that have been modified by cladding in the early stage, hydrogen embrittlement may cause the risk of falling off, especially at the interface where there is a preferred diffusion path. Combined with thermal stress, this increases the tendency of the material to fail prematurely. The inventors were surprised to find that this risk can be significantly reduced by adjusting the process gas composition (precursor composition) from N2 / H2=1:3 to N2 / H2=1:1, or N2 / H2 in the range of 1.15:1 to 1:1.15.

[0096] A particularly preferred method according to the invention for producing a component having a modified metal surface preferably comprises the following steps:

[0097] a. providing at least one substrate to be treated (at least one component, such as a large forming tool) having at least one substrate surface to be treated,

[0098] b. Optionally, polishing the surface of the substrate to be treated (pre-polishing),

[0099] c. loading the at least one substrate to be processed into a vacuum chamber (of a plasma processing device), wherein,

[0100] The at least one substrate is fixed in an electrically insulating manner relative to the vacuum chamber wall, so that the vacuum chamber wall can form an anode and the at least one substrate can at least partially form a cathode,

[0101] d. closing the vacuum chamber by sealing one or more openings through which the at least one substrate to be treated is loaded into the vacuum chamber,

[0102] e. evacuating the vacuum chamber to a working pressure (preferably to 0.05 mbar),

[0103] f. heating the substrate in the vacuum chamber by means of an electric heater, wherein the substrate is heated to a substrate temperature of 100° C. to 300° C., thereby carrying out a cleaning step in which oil and dirt on the substrate are cleaved before the plasma is ignited (this method step is also referred to within the scope of the invention as an integral cleaning step or a substrate cleaning step without plasma heating, wherein, as described above, heating is preferably carried out to a temperature of between 100° C. and 300° C., or a temperature of between 220° C. and 300° C., for example to 250° C.),

[0104] g. passing a gas mixture into a vacuum chamber, wherein the gas mixture preferably contains hydrogen and nitrogen in elemental form and / or compound form, and the process gas composition in the vacuum chamber is preferably in the range of N2 / H2 from 1.15:1 to 1:1.15, or N2 / H2=1:1,

[0105] h. igniting the plasma at a substrate temperature of 100°C to 300°C,

[0106] i. the nitriding treatment is performed by applying a pulse voltage between the anode and the cathode, ionizing the gas mixture and forming a plasma in the vacuum chamber, the nitriding by pulsed DC plasma preferably being carried out at a substrate temperature of 300 to 560° C., depending on the type, size, weight and material of the substrate (e.g. steel or cast iron),

[0107] j. Cooling,

[0108] k. Optionally, polish (post-polishing).

[0109] The invention allows the treatment of workpieces in such a way that, in the case of forming tools for metal forming, all of the above-mentioned requirements are met. Thus, it is also possible to repair (partial welding) the tool or forming tool treated according to the invention without having to carry out a prior denitriding. In addition, the invention allows the treatment of the tool or forming tool in such a way that the conventionally used additional lubricants can be virtually dispensed with, thereby achieving a maximum lubrication minimization.

[0110] In particular, the present invention relates to an apparatus and a method for plasma processing a component, wherein the apparatus is particularly suitable for plasma processing a large component, and the method is suitable for performing excellent and stable plasma processing on a component (especially a large component).

[0111] A device for plasma processing a component in a plasma processing chamber, comprising a cylindrical processing chamber for plasma-assisted surface processing of the component, wherein the cylindrical processing chamber has a bottom surface, through which the component to be processed can be loaded and fixed, and the processing chamber is constructed in the form of a horizontal cylinder, and has at least one side cylinder cover that can be opened and vacuum-tightly closed, wherein the cylinder cover is arranged at one of the two ends of the horizontal cylinder, and the circumference of the cylinder cover is at least 8 meters, so when the cylinder cover is opened, the component to be processed can be loaded into the processing chamber through the lateral opening, and the cylinder cover is provided with a circular cover sealing surface opposite to the cylinder remainder, and the cylinder remainder is provided with a circular cylinder remainder sealing surface opposite to the cover sealing surface, wherein, in order to seal at the sealing surface to achieve vacuum-tight closure, the following sealing system is provided, that is, a plurality of grooves are milled on one of the sealing surfaces, so as to meet the following conditions:

[0112] · Realization of a first annular groove, also referred to below as outer groove 2,

[0113] · Realization of a second annular groove, also referred to below as inner groove 3,

[0114] The diameter of the circle represented by the inner groove is smaller than the diameter of the circle represented by the outer groove,

[0115] A third groove is provided between the outer groove 2 and the inner groove 3, hereinafter also referred to as the middle groove 4,

[0116] The circle represented by the middle groove is smaller than the circle represented by the outer groove,

[0117] the circle represented by the middle groove is larger than the circle represented by the inner groove,

[0118] The three grooves are formed in a mutually non-intersecting manner around a center point, preferably the same center point,

[0119] · Sealing rings 1 are provided along the inner sides of the outer groove and the inner groove.

[0120] At least one of the sealing rings 1, but preferably both sealing rings, has a shape such that when the cover is pressed against the annular surface 8 of the remaining chamber, the flat sealing surface is pressed, and in the depth direction of the groove, the sealing ring has a sealing lip 6 facing outwards (wherein "facing outwards" means facing the external environment 10 or the inner cavity 20 of the barrel, such as Figure 2b ) and an inwardly facing sealing lip 7 (wherein "inwardly facing" means toward the auxiliary vacuum chamber 40, as shown Figure 2bshown), they are close to the groove wall,

[0121] The arrangement is designed in the following manner: when the sealing surface of the cover and the sealing surface of the remaining part of the barrel are pressed against each other, a gap space system is formed, which is closed relative to the external environment 10 and relative to the inner cavity 20 of the barrel of the device, wherein the gap space system includes two pressurized chambers 30 and an auxiliary vacuum chamber 40, and wherein the sealing system has a mechanism for applying a gas with an overpressure of 0.1 to 1 mbar, preferably nitrogen, to the pressurized chambers 30.

[0122] A method for plasma treatment of a component in a plasma treatment chamber, wherein, in order to produce a component having a modified metal surface, the method comprises the following steps:

[0123] a. providing at least one substrate to be treated (at least one component, such as a large forming tool) having at least one substrate surface to be treated,

[0124] b. polishing the surface of the substrate to be treated (i.e. possible pre-polishing) as required,

[0125] c. loading the at least one substrate to be processed into a vacuum chamber of a plasma processing device, wherein the at least one substrate is fixed in an electrically insulated manner relative to a vacuum chamber wall so that the vacuum chamber wall can form an anode and the at least one substrate can form at least a portion of a cathode,

[0126] d. closing the vacuum chamber by sealing one or more openings through which the at least one substrate to be processed is loaded into the vacuum chamber,

[0127] e. evacuating the vacuum chamber to a working pressure (preferably to 0.05 mbar),

[0128] f. heating the substrate in the vacuum chamber by means of an electric heater, wherein the substrate is heated to a substrate temperature of 100° C. to 300° C., thereby performing a cleaning step in which oil and dirt on the substrate are cleaved before the plasma ignites,

[0129] g. passing a gas mixture into the vacuum chamber, wherein the gas mixture preferably contains hydrogen and nitrogen in elemental form and / or compounds, and the process gas composition in the vacuum chamber is preferably in the range of N2 / H2 from 1.15:1 to 1:1.15, or N2 / H2=1:1,

[0130] h. igniting the plasma at a substrate temperature of 100°C to 300°C,

[0131] i. plasma treatment (wherein the plasma treatment is in particular nitriding or comprises at least one nitriding) is performed by applying a pulsed voltage between the anode and the cathode, ionizing the gas mixture and forming a plasma in the vacuum chamber, the nitriding preferably being performed by a pulsed direct current plasma and preferably at a substrate temperature of 300 to 560° C., wherein the substrate temperature depends on the type, size, weight and material of the substrate (e.g. steel or cast iron),

[0132] j. Cooling,

[0133] k. Optionally, polishing (ie possible post-polishing).

[0134] According to a preferred embodiment, when performing the above step i, a method is adopted that allows the plasma treatment to be stably performed.

[0135] According to the invention, the method for allowing stable execution of plasma treatment is a method for plasma treatment of a component at a predetermined working voltage and a predetermined process pressure in a plasma treatment chamber, wherein, in the case of frequent occurrences of arc discharges that need to be suppressed, the value of the working voltage is suddenly reduced by a voltage value in the range of 10V to 100V, and then the working voltage is readjusted to the initial working voltage through a step-by-step process lasting at least one minute, wherein a number of arc discharges occurring in the range of 7 to 25 times within a time interval of 250 milliseconds is identified as frequent occurrences. According to a preferred embodiment of the method, additionally, the working pressure is temporarily increased stepwise, preferably in steps of 0.1 mbar, to a maximum value of 2.5 mbar, and / or the working pressure is reduced stepwise in steps of 0.1 mbar to a minimum value of 0.5 mbar, wherein the initial working pressure is 0.5 mbar to 4.5 mbar.

[0136] The above-described method of the invention is preferably carried out in the above-described apparatus of the invention.

[0137] According to the invention, the substrate to be treated is preferably a tool for forming or plastic processing.

[0138] However, the invention is not limited to plasma treatment of such tools.

Claims

1. An apparatus for plasma processing a component in a plasma processing chamber, the apparatus comprising a cylindrical processing chamber for plasma-assisted surface processing of a component, wherein: The cylindrical treatment chamber has a bottom surface, through which the components to be treated can be loaded and fixed, and the treatment chamber is configured in the form of a horizontal cylinder, and the horizontal cylinder has at least one side cylinder cover that can be opened and vacuum-tightly closed, wherein the cylinder cover is arranged at one of the two ends of the horizontal cylinder, and the circumference of the cylinder cover is at least 8 meters, so that when the cylinder cover is opened, the components to be treated can be loaded into the treatment chamber through the lateral opening, and the cylinder cover is provided with an annular cover sealing surface for being opposite to the cylinder remainder, and the cylinder remainder is provided with an annular cylinder remainder sealing surface for being opposite to the cover sealing surface, wherein, in order to seal at the sealing surface to achieve vacuum-tight closure, the following sealing system is provided, that is, a plurality of grooves are milled on one of the sealing surfaces to meet the following conditions: · Realizing a first annular groove, also referred to below as outer groove (2), · Realization of a second annular groove, also referred to below as inner groove (3), the diameter of the circle represented by the inner groove is smaller than the diameter of the circle represented by the outer groove, A third groove is provided between the outer groove (2) and the inner groove (3), hereinafter also referred to as the middle groove (4), the circle represented by the middle groove is smaller than the circle represented by the outer groove, the circle represented by the middle groove is larger than the circle represented by the inner groove, The three grooves are formed in a mutually non-intersecting manner around a center point, preferably the same center point, The outer groove and the inner groove are each provided with a sealing ring (1) extending along the groove, at least one of the sealing rings (1), but preferably both sealing rings, has a shape such that when the cover is pressed onto the annular surface (8) of the rest of the chamber, the flat sealing surface is pressed, and in the depth direction of the groove, the sealing ring has an outwardly facing sealing lip (6) and an inwardly facing sealing lip (7), They cling to the tank walls. This arrangement is designed in the following way: when the sealing surface of the cover and the sealing surface of the remaining part of the barrel are pressed against each other, a gap space system is formed, which is closed relative to the external environment (10) and relative to the inner cavity (20) of the barrel of the device, wherein the gap space system includes two pressurized chambers (30) and an auxiliary vacuum chamber (40), and wherein the sealing system has a mechanism for introducing gas into the pressurized chamber (30), preferably using nitrogen, with an overpressure of 0.1 to 1 mbar.

2. A method for plasma processing a component in a plasma processing chamber at a predetermined operating voltage and a predetermined processing pressure, characterized in that: When arc discharges occur frequently and need to be suppressed, the value of the working voltage is suddenly reduced by a voltage value in the range of 10V to 100V, and then the working voltage is readjusted to the initial working voltage through a step-by-step process lasting at least one minute, wherein arc discharges occurring in the range of 7 to 25 times within a time interval of 250 milliseconds are identified as frequent occurrences.

3. The method according to claim 2, characterized in that Additionally, the working pressure is temporarily increased stepwise, preferably in steps of 0.1 mbar, to a maximum value of 2.5 mbar, and / or the working pressure is reduced stepwise in steps of 0.1 mbar to a minimum value of 0.5 mbar, wherein the initial working pressure is 0.5 mbar to 4.5 mbar.

4. A method for plasma processing a component in a plasma processing chamber, characterized in that: To produce a component having a modified metal surface, the method comprises the following steps: a. providing at least one substrate to be treated, which has at least one substrate surface to be treated, b. Pre-polishing the surface of the substrate to be treated as needed, c. loading the at least one substrate to be processed into a vacuum chamber of a plasma processing device, wherein the at least At least one substrate is fixed in an electrically insulating manner relative to the vacuum chamber wall so that the vacuum chamber wall can form an anode. a cathode, and the at least one substrate is capable of forming at least a portion of a cathode, d. Closing the vacuum chamber by sealing one or more openings, through which the at least one The substrate to be processed is placed in the vacuum chamber. e. evacuating the vacuum chamber to a working pressure (preferably to 0.05 mbar), f. heating the substrate in a pre-vacuum by means of an electric heater, wherein the substrate is heated to a substrate temperature of 100° C. to 300° C., thereby performing a cleaning step in which the substrate is heated to a substrate temperature of 100° C. to 300° C. Oil and dirt on the material are cracked before the plasma ignites. g. passing a gas mixture into the vacuum chamber, wherein the gas mixture also contains and / or hydrogen and nitrogen in the form of compounds, h. igniting the plasma at a substrate temperature of 100°C to 300°C, i. by applying a pulse voltage between the anode and the cathode, so that the gas mixture is ionized and Plasma is formed in the vacuum chamber, thereby performing plasma processing, wherein the plasma processing means or includes nitriding, j. Cooling, k. Perform post-polishing as needed.

5. The method according to claim 4, characterized in that When performing step i, the method according to claim 2 or 3 is adopted.

6. The method according to any one of claims 2 to 5, characterized in that The method is performed in the device according to claim 1.

7. The method according to any one of claims 4 to 7, characterized in that The substrate to be treated is a tool for forming or plastic processing.

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