Process box for thermally coating a metallic interior surface, coating system for thermally coating a cylinder crankcase for an internal combustion engine and method for thermally coating a metallic interior surface of an object

Abstract

Process box (500) for thermally coating a metallic interior surface (10) of an object (22), comprising at least one coating system (400), which includes a coating lance (200) with at least the following elements: - Plasma nozzle (11) for generating a hot gas jet (12), wherein the hot gas jet (12) has a predetermined temperature, velocity and central axis orientation (17); - Feeding device (13) for feeding coating material in solid phase towards the hot gas jet (12); and - Holding lance (15), wherein the holding lance (15) has an insertion direction (16), wherein a jet angle (18) enclosed with the holding lance (15) is formed between the insertion direction (16) of the holding lance (15) and the central axis alignment (17) of the hot gas jet (12), which is less than 90°, and a masking shield (300), wherein in the coating operation of the coating lance (200) the portion of the conical jet (19) applied above a top surface (25) of the mask device (300) is directed at a shallow deflection angle (31) to the top surface (25), wherein the deflection angle (31) between the portion of the conical jet (19) and the top surface (25) is less than 10° or negative, wherein a negative deflection angle (31) is inclined away from the top surface (25), wherein at least one coating system (400) is integrated into a closed, extractable housing (32), wherein the coating-effective conical jet (19) has a jet end (34) in the jet direction (33), behind which the conical jet (19) is no longer coating-effective, and wherein the coating-effective conical jet (19) up to the jet end (34) can only hit the top (25) of the masking shield (300) or a surface unsuitable for adhesion.

Description

[0001] The invention relates to a process box for thermally coating a metallic interior surface, a coating system for thermally coating a cylinder crankcase for an internal combustion engine and a method for thermally coating a metallic interior surface of an object. Technical field

[0002] Thermal coating is a process belonging to the category of thermal spraying. This includes, among others, powder plasma spraying processes, such as atmospheric plasma spraying (APS), and wire plasma spraying processes, such as plasma transfer wire arc (PTWA) and rotating single-wire spraying (RSW). Other relevant thermal coating processes include arc wire spraying (LDS) and high-velocity oxygen fuel spraying (HVOF). These differ fundamentally in the supply of the cold, i.e., solid, coating material as a powder (APS) or as a wire (RSW) or rod. In wire spraying processes, the coating material must be completely melted in order to be separated from the feed material and thus accelerated as particles against the surface to be coated.In contrast, with powder spraying, it is possible, but not mandatory, to simply melt the individual powder particles and obtain a cold, i.e., solid, core. Furthermore, the shape, size, and even composition of the particles can be freely adjusted in powder spraying. Typically, in powder plasma spraying, the particles are melted in a plasma jet at temperatures up to 15,000 K, accelerated by the plasma gas, and applied to the workpiece or surface to be coated. The energy of the particles is adjusted via the spray distance and plasma parameters so that the particles strike the surface in a barely liquid or pasty state, transfer their energy to the base material with the impact impulse, and solidify immediately.A disadvantage is the dependence of the orientation and scattering angle or scattering cone of the coating-effective conical jet on the material, size and shape of the supplied particles, as well as the supply direction and supply speed.

[0003] All thermal coating and plasma jet coating processes share the common feature of using a hot gas jet, containing at least partially ionized gas, such as a flame, to both heat the material being processed and to accelerate the particles in a controlled manner. These processes typically include a cathode and an anode, between which an electric arc is generated to ionize and / or ignite a cold or preheated gas. Alternatively, a gas at a desired temperature can be supplied at a high temperature. In the wire spraying processes PTWA and RSW, the wire itself acts as an anode, so an electric arc is used between the cathode (burner) and the anodically connected wire to melt the wire. In the LDS process (two-wire process), an electric arc is ignited between an anodically and a cathodically connected wire, and both wires are melted.In all wire processes, an atomizing gas (compressed air or an inert gas such as argon or nitrogen) is used to atomize and accelerate the sprayed material towards the surface to be coated. Thermal coating differs from cladding welding primarily in that the heat input into the surface to be coated is at least so low that it does not melt, or is usually so low that the microstructure of the material to be coated is not altered. State of the art

[0004] Such a coating lance and masking shield are known, for example, from WO 2016 / 0015922 A1, which deals with a device and a method for metallic coating as well as a receiving unit for this device, for example on page 2, first to third paragraphs. There, the problem is described that increased overspray is generated when switching on and off a metal plasma beam, and layer thickness deviations can occur on the workpiece. As can be seen on page 3, last paragraph, the metal plasma beam should therefore not be switched off or should be switched on and off outside the surface to be coated.

[0005] Overspray sometimes refers to the pure dust component, which merely causes contamination through passive adhesion, for example, due to static charge or molecular bonding to freshly applied, still molten coating material. However, it primarily refers to material that is sprayed into areas where no coating should or may adhere when exiting the coating area (e.g., a cylinder bore) and is thus removed. This includes areas such as the crankcase, top deck (water chambers, oil channels, etc.), or material freely sprayed into the space (e.g., when the burner enters and exits the cylinder bore between individual coating overflows at the reversal points outside the cylinder bore, or when the burner is moved to the next cylinder bore or the next area to be coated).Additionally, the portion of the cone jet that is effective for coating is also referred to as overspray, which, due to the reduced particle count in this mantle edge region, leads to an undesirably rough surface coating. Hereafter, the latter definition will be used, and the narrower first definition will be referred to as dust.

[0006] In WO 2016 / 0015922 A1, the last paragraph of page 3 proposes the use of a suction bell containing an annular or drum-shaped receiving unit for the accumulation of metal particles. According to page 3, third paragraph, this receiving unit must be replaced regularly due to the accumulation. Furthermore, on page 10, second paragraph, the following is also mentioned: Fig. Figure 4 describes that a masking shield is provided, consisting of a ring flange 42 with a conical surface 44 of approximately 30° relative to the workpiece's contact surface. This conical surface is designed to deflect any metal particles striking it towards the drum-shaped receiving unit 50, causing the metal particles to adhere there as desired. To prevent adhesion to the conical surface, it is provided with an unspecified non-stick coating. Fig. 3 and Fig. 4 The conical surface 44 is adjacent to a lower edge element 58 with a gap and is arranged in a spring-like manner relative to this element, as described in the first paragraph on page 10, for precise and flexible placement on a workpiece. As described in the first paragraph of page 11, the edge element 58 ensures that metal particles do not escape downwards from the receiving unit 50.

[0007] From EP 1 141 438 B1, which deals with an auxiliary device for the thermal coating of interior surfaces, the person skilled in the art can see, for example, in column 13, paragraph

[0041] , that the coating material applied above the interior to be coated must adhere to a wear sleeve in order to reliably prevent overspray particles from entering the cylinder bore unmelted. This would lead to irregularities and defects in the coating to be achieved. For this purpose, it is proposed that the wear sleeve 116, which according to Fig. 6, which is directly adjacent to the cylinder crankcase shown there, is to be equipped with particularly good adhesive properties.

[0008] DE 10 2010 053 327 A1 discloses a method for thermal spray coating of a surface using an arc wire torch. For this purpose, a spray bar is aligned across the surface opposite to a feed direction of a torch, and the spray jet angle of the torch is adjusted as a function of the feed direction such that an angle of impact is established between an imaginary boundary line, which lies in the feed direction between a focused spray area and a non-focused spray area of ​​the spray jet, and the surface with respect to the feed direction, which lies in the range of 90° to 110°.

[0009] EP 2 455 510 A2 further discloses a device for the thermal coating of cylinder inner surfaces in crankcases, comprising a coating tool that can be inserted into the area of ​​at least one of the cylinder inner surfaces and a suction device connected to a vacuum source and arranged opposite the end face of the cylinder inner surface, with a suction opening directed towards the cylinder inner surface.

[0010] Further lance-guided coating devices are known, for example, from EP 0 336 630 A1, DE 10 2009 023 605 A1 and DE 10 2012 105 521 A1. Object of the invention

[0011] The invention is based on the objective of guiding the coating jet of a coating lance of the type mentioned above in such a way that the deposition of particles from the coating jet on a masking shield is largely avoided. This is achieved by ensuring that, during operation of the coating lance and while the coating lance is in a non-coating position, i.e., outside the area to be coated, the coating jet does not strike a counter surface until it reaches its end, or strikes a counter surface at a shallow angle of less than 10°. Solution to the task

[0012] This problem is solved by a process box according to claim 1, a coating system according to claim 5 or a method according to claim 6. Advantageous embodiments of the invention are characterized in the dependent claims. Description of the invention

[0013] According to the invention, a process box for thermally coating a metallic interior surface is proposed, which has at least one coating system comprising a coating lance with at least the following elements: - Plasma nozzle for generating a hot gas jet, wherein the hot gas jet has a predetermined temperature, velocity and central axis orientation; - Feeding device for supplying coating material in solid phase to the hot gas jet; and - Holding lance, wherein the holding lance has an insertion direction, wherein a jet angle enclosed to the holding lance is formed between the insertion direction of the holding lance and the central axis alignment of the hot gas jet, which is less than 90°, and a masking shield, wherein in the coating operation of the coating lance the portion of the conical jet applied above a top surface of the mask device is directed at a shallow deflection angle to the top surface, wherein the deflection angle between the portion of the conical jet and the top surface is less than 10° or negative, wherein a negative deflection angle is inclined away from the top surface, where at least one coating system is integrated into a closed, extractable housing, wherein the coating-effective conical jet has a radiating end in the direction of the jet, behind which the conical jet is no longer coating-effective, and wherein the coating-effective conical jet can only hit the top of the masking shield or a surface unsuitable for adhesion up to the radiating end.

[0014] The coating lance head is a separate component designed for connection to a holding lance. For this purpose, the coating lance head has connections for supplying the coating jet, such as a gas connection for the hot gas jet's gas (mixture), a coating material connection, connections for cooling and jacket gases (e.g., compressed air or inert gases), an electrical connection, and optionally one or more coolant connections. Furthermore, the coating lance head preferably has one or more sensors and / or one or more connections for a detection device, thus enabling the monitoring of at least one process parameter.

[0015] The coating lance head features a plasma nozzle designed to align and accelerate the hot gas jet. The plasma nozzle is supplied with gas (or a gas mixture) for the hot gas jet via a suitable gas connection. Furthermore, the plasma nozzle is often configured to generate an electric arc, acting as both the anode and / or cathode. The plasma nozzle is designed for either pure gas transport or the transport of a gas (or gas mixture) already containing particles. The shape and type of the plasma nozzle are readily apparent to those skilled in the art from generally known technology. The shape and velocity of the hot gas jet, as well as its central axis orientation, are determined by the type and shape of the plasma nozzle. This is typically the extension of the central axis of a rotationally symmetrical plasma nozzle.

[0016] The feed unit integrated into the coating lance head can be supplied with suitable coating material via a coating material connection, allowing the coating material to be fed to the hot gas jet at the desired speed and orientation. For example, a desired orientation of the feed unit results in a feed direction at a right angle, approximately 90° to the central axis of the hot gas jet. Suitable materials include metals, ceramics, ceramic-metal alloys, and metal alloys containing friction-reducing components such as molybdenum disulfide (MoS₂) or similar substances. The coating material is supplied in powder, rod, or wire form and is either melted or partially melted by the hot gas jet.In the case of a typically lateral feed, for example perpendicular to the central axis, of a powdered coating material, the conical jet of the coating material deviates from the hot gas jet in many process configurations, offset and / or inclined relative to the central axis of the hot gas jet; specifically, away from the outlet of the feed device. These parameters can also be determined by a person skilled in the art from generally known prior art and, if necessary, reproducibly adjusted through manageable experiments.

[0017] The coating lance head also features an angled bracket by which the angular position of the central axis alignment of the hot gas jet, as defined by the plasma nozzle used, is fixed or freely adjustable relative to the insertion direction of a holding lance. Preferably, the angled bracket includes the connections described above. Alternatively, in one embodiment, the angled bracket has a connection surface oriented transversely to the insertion direction of the holding lance and connectable, preferably detachably, to a correspondingly designed counter-connection surface. Those skilled in the art understand that the shape and inclination of the angled bracket are freely selectable and only need to be adapted to a correspondingly designed counter-connection surface for setting or adjusting the desired angular position of the central axis alignment of the hot gas jet.Preferably, the connections of the type described above with respect to the coating lance head are provided in the corresponding connection and counter-connection surfaces, and particularly preferably, the connections of the coating lance head and the corresponding counter-connections of the holding lance can be directly connected to each other when fastened together. In one embodiment, for example, for use with liquid media, at least one check valve or at least one self-closing line is used.

[0018] In many applications, particularly when coating an internal surface such as a cylinder bore in the crankcase of an internal combustion engine, and in other confined spaces, the insertion direction of the holding lance, and thus of the coating lance head, coincides with the axial straight extension of the holding lance. However, in other applications, it may be advantageous to use a free-form holding lance. In this case, the insertion direction is the direction of movement required for a desired coating result. The trajectory of such movement may deviate from a straight line.

[0019] In operation with the angled bracket, the jet angle between the feed direction and the central axis of the hot gas jet is less than 90°, preferably less than 80°, and particularly preferably less than 70°. Preferably, the feed device is inclined accordingly, so that, for example, an angle of approximately 90° is established between the central axis and the feed direction. The choice of the jet angle is preferably determined by the type and inclination of a shielding top surface of a masking shield, such that the coating jet does not strike a counter surface in a non-coating position up to a certain point, or strikes a counter surface at a shallow angle of less than 10°. The point of the jet is the end of the conical jet beyond which, in the direction of the jet, the conical jet is no longer effective for coating.

[0020] In the case of a cylinder crankcase, a non-coating position of the coating jet is, for example, a position along the extension of the axis of rotation of a cylinder bore to be coated, where the coating jet is not directed at a wall of the cylinder bore. Due to the conical shape of the coating jet, this condition of impact on a counter surface also applies in a position where part of the coating jet is still directed at the wall of the cylinder bore and another part is already being applied outside the cylinder bore. The steeper the jet angle is chosen, the steeper the shielding surface of a masking shield can be and / or the smaller the radial dimension of the masking shield can be, because the radial extent of the coating jet to the end of the jet is smaller.

[0021] According to an advantageous embodiment of the coating lance head, in coating operation the supplied coating material forms a coating-effective conical jet as a result of acceleration by means of the hot gas jet, and an enclosed maximum angle is formed between the generatrix of the conical jet inclined maximally away from the insertion direction of the holding lance and the insertion direction of the holding lance, which is equal to or less than 90°.

[0022] The coating process is the state in which a stable, coating-effective conical jet is generated by means of the hot gas jet and the coating material. This is independent of whether a surface is being coated or the conical jet is being applied away from a surface to be coated.

[0023] The coating-effective conical jet is the portion of the coating material accelerated by the hot gas jet that can produce a desired coating on the surface to be coated, or at least one that is acceptable within tolerances. The coating-effective conical jet has an approximate conical shape, which, due to gravity and / or the material feed, may have an elliptical base and / or an inclined cone height on the jet side. The cone height of the conical jet may be offset from and / or inclined away from the central axis of the hot gas jet. This is generally the case in a powder spraying process when the powder is fed laterally to the hot gas jet. The coating-effective conical jet is bounded by a lateral surface.The precise location of the surface can be determined, for example, by examining the deposit pattern of a point deposit or one or more line deposits. Alternatively, lateral images can provide this information. A person skilled in the art can draw upon extensive, generally known prior art for this determination.

[0024] The generatrix that is furthest inclined away from the insertion direction forms the maximum angle with the insertion direction. With a perpendicular orientation of the insertion direction, the generatrix inclined at maximum distance lies below the cone height when the cone jet is pivoted from above (i.e., the side of the holding lance) towards the horizontal, and, at least if the coating-effective cone jet forms a circular cone, within the plane spanned by the insertion direction and the cone height. For a coating-effective cone jet with an elliptical base rotated about the cone height relative to this plane, the maximum angle is formed by the generatrix that lies in the plane containing the generatrix inclined furthest downwards from the insertion direction.The coating-effective conical jet therefore has no line that is inclined further away from the insertion direction than the generatrix which forms the maximum angle with the insertion direction.

[0025] Between the insertion direction and the maximally inclined generatrix, a maximum angle of 90° or less exists when using the angled bracket, preferably less than 80°, and particularly preferably less than 70°. The choice of the maximum angle is preferably determined by the type and inclination of a shielding top surface of a masking shield, such that the coating-effective conical jet does not strike a counter surface in a non-coating position until the end of the jet, or strikes a counter surface at a shallow angle of less than 10°.

[0026] In this embodiment, the adhesion of particles to an inclined, shielding top surface of a masking shield is almost completely eliminated or at least reduced to the portion of the coating-effective conical jet that strikes a counter surface at an angle of over 10°.

[0027] Deposits are further reduced by suitable extraction or airflow. The coating lance head is preferably configured for one of the following processes: - Atmospheric Plasma Spraying (APS); - Rotating single-wire syringes (RSW); - Plasma transfer wire arc injections (PTWA); - Arc wire spraying (LDS); - High-velocity oxygen fuel spraying (HVOF); and - Flame spraying

[0028] Atmospheric plasma spraying (APS) is a process in which a solid powder is fed laterally, sometimes with multiple injections, from the rear, from above, and / or from below into an ionized hot gas jet, such as a flame. Besides the advantages of highly variable and cost-effective process control, as described earlier, this powder-based process is characterized by a large opening angle of the coating-effective cone jet. Therefore, even with a shallow opening angle of a conventional through-hole in a masking shield, coating-effective particles from a conventional coating lance, when extended from the interior to be coated, strike the material at a relatively steep angle.As a result, these particles can adhere to this conventional through-hole or, due to the opening angle, re-enter the area of ​​the surface to be coated as dust particles. There, they can become embedded in the applied layer during the ongoing coating process, leading to large defects and thus scrap. These particles cannot be removed, or not without damage, even in subsequent washing processes. Consequently, the surface no longer fulfills the desired properties, particularly regarding reduced friction. The prevailing opinion has therefore been that atmospheric plasma spraying can only be used with good adhesion properties when a sacrificial ring follows directly behind the surface to be coated in the feed direction.By negatively angling the central axis of the hot gas jet, or even the maximum angle of the coating-effective cone jet, a solution has been found that prevents adhesion and eliminates the risk of dust adhering to the area of ​​the workpiece being coated. The non-stick properties of the masking shield do not need to be optimal to minimize overspray. This makes the device very cost-effective. These advantages can also be applied to wire spraying processes by using steeper angles of the through-hole and / or a less expensive non-stick material.

[0029] According to a further aspect of the invention, a coating lance for thermally coating a metallic surface is proposed, which has at least the following elements: - Plasma nozzle for generating a hot gas jet, wherein the hot gas jet has a predetermined temperature, velocity and central axis orientation; - Feeding device for supplying coating material in solid phase towards the hot gas jet; - Holding lance, wherein the holding lance has an insertion direction, wherein an enclosed jet angle inclined towards the holding lance is formed between the insertion direction of the holding lance and the central axis alignment of the hot gas jet, which is less than 90°.

[0030] The coating lance has lines for supplying a coating jet, such as a gas line for the gas (mixture) of the hot gas jet, lines for cooling and jacket gases (e.g., compressed air or inert gases), a coating material line, an electrical line, and optionally one or more coolant lines. Furthermore, the coating lance preferably has one or more sensors and / or one or more connections for a detection device, thereby enabling the monitoring of at least one process parameter.

[0031] The coating lance features a plasma nozzle designed to align and accelerate the hot gas jet. The plasma nozzle is supplied with gas (or a gas mixture) for the hot gas jet via a suitable gas line. Furthermore, the plasma nozzle is often configured to generate an electric arc, acting as both the anode and / or cathode. The plasma nozzle is configured as described above with reference to the coating lance head, and in this respect, please refer to the description above.

[0032] The feed unit integrated into the coating lance can be supplied with suitable coating material via a coating material line, allowing the coating material to be fed to the hot gas jet at the desired speed and in the desired direction. Suitable materials and the orientation of the feed unit are described above with reference to the coating lance head, and in this respect, reference is made to the above description.

[0033] The coating lance includes a holding lance designed to keep the plasma nozzle and feed unit precisely aligned during the coating process. The holding lance also incorporates the main part of the lines described above and, where applicable, the sensors and / or connectors described above.

[0034] In many applications, particularly when coating an internal surface such as a cylinder bore in the crankcase of an internal combustion engine, and in other confined spaces, the insertion direction of the holding lance, and thus of the coating lance, coincides with the axial straight extension of the holding lance. However, in other applications, it may be advantageous to use a free-form holding lance. In this case, the insertion direction is the direction of movement required for a desired coating result. Under certain circumstances, the trajectory of such movement may deviate from a straight line.

[0035] The coating lance is designed in such a way that the angular position of the central axis alignment of the hot gas jet, as defined by the plasma nozzle used, is fixed or freely adjustable in relation to the insertion direction of a holding lance.

[0036] In operation, the jet angle between the injection direction and the central axis of the hot gas jet is less than 90°, preferably less than 80°, and particularly preferably less than 70°. The jet angle and the injection direction are configured as described above with respect to the coating lance head, and reference is made to the description above.

[0037] According to an advantageous embodiment of the coating lance, in coating operation the supplied coating material forms a coating-effective conical jet as a result of acceleration by means of the hot gas jet, and an enclosed maximum angle is formed between the generatrix of the conical jet inclined maximally away from the insertion direction of the holding lance and the insertion direction of the holding lance, which is equal to or less than 90°.

[0038] The features mentioned in the previous paragraph are described above with reference to the coating lance head, and in this respect reference is made to the above description.

[0039] The coating lance is preferably set up for one of the following processes: - Atmospheric Plasma Spraying (APS); - Rotating single-wire syringes (RSW); - Plasma transfer wire arc injections (PTWA); - Arc wire spraying (LDS); - High-velocity oxygen fuel spraying (HVOF); and - Flame spraying

[0040] The procedures mentioned in the previous paragraph are described at the outset and subsequently with reference to the coating lance head, and in this respect reference is made to the above description.

[0041] In one embodiment, the angle bracket has a connection surface oriented transversely to the insertion direction of the holding lance and is connectable, preferably detachably, to a correspondingly designed counter-connection surface of the holding lance. Those skilled in the art understand that the shape and inclination of the angle bracket are freely selectable and only need to be adapted to a correspondingly designed counter-connection surface for setting or adjusting the desired angular position of the central axis alignment of the hot gas jet. Preferably, the connections of the type described above with respect to the coating lance head are provided in the corresponding connection surface and counter-connection surface, and it is particularly preferred that the connections of the coating lance head and the corresponding counter-connections of the holding lance can be directly connected to each other during assembly.

[0042] According to a further aspect of the invention, a masking shield for shielding predetermined surfaces of an object during thermal coating is proposed, which has at least the following elements: - Underside for placement on a surface to be shielded; - Top side facing a coating lance when the coating lance is in an extended position; - Through-hole with an axial extension from the top to the bottom, through which a coating lance can be immersed to coat the object, wherein the top forms an enclosed opening angle to the axial extension of the through-hole which is greater than 75°; - Anti-stick coating on the top and, if necessary, on the underside in the area of ​​the opening.

[0043] In a preferred embodiment, the top surface borders radially outside without gaps against an outer surface, wherein the outer surface slopes away from the top surface and runs parallel to or towards the bottom surface.

[0044] For example, the top surface has no bend and is thus formed as a continuous surface. In a preferred embodiment, the top surface has one or more bends, so that the top surface is divided into several sub-surfaces, each with a different angle. The opening angle is that of the sub-surfaces directly adjacent to the through-opening or the total slope of the sub-surfaces, up to whose transition to the next sub-surface or the exterior area the coating-effective conical jet extends to its end point.

[0045] The upper surface, and preferably also the lower surface, exhibits a non-stick property at least in a partial area adjacent to the through-hole, such that adhesion between the upper surface and the particles is made difficult or even prevented as a result of the material pairing. This partial area extends radially at least to the tip of the conical jet.

[0046] In a preferred embodiment, the non-stick property is achieved by providing the upper surface with a non-stick coating. This makes it difficult or impossible for splash particles and dust particles to adhere. The shallow angle of the upper surface proposed here also has the advantage that particles lying on the upper surface cannot, or at least cannot easily, fall into the area of ​​the surface to be coated, with the aforementioned disadvantages, due to gravity. Instead, they remain in place or even move radially outwards, i.e., upwards, following the momentum of the hot gas jet.

[0047] In a further preferred embodiment, the underside is provided with a non-stick coating, at least in the area of ​​the through-opening, for example over a border of at least 1 cm, or over the entire contact surface. This prevents the adhesion of particles that are unlikely to enter the gap between the surface to be shielded and the masking shield.

[0048] The masking shield differs from all previously known designs in that a sacrificial ring is unnecessary, because adhesion of coating material and damage to the areas to be coated or already coated by dust or overspray entering these areas can be prevented. This also advantageously applies to powder spraying processes, such as atmospheric powder spraying (APS).

[0049] The underside of the masking shield is designed to rest on a surface to be protected, for example a top deck surface of a cylinder crankcase, which may have openings for a water space and oil return lines.

[0050] The top side faces a coating lance, so that in a state where a coating jet is not completely directed at a surface to be coated, the top side can be partially struck by particles that are effective for coating. This state is referred to here as the "exposed position".

[0051] A through-opening extends through the masking shield, penetrating both the top and bottom surfaces. This opening serves two purposes: firstly, it provides a passage for the coating lance, and secondly, it acts as a template, allowing for the precise application of a defined edge around the opening to the surface of the object to be coated. This edge area is then also coated, resulting in edge coating. This edge coating enhances the mechanical strength of the coating in the interior compared to chamfering, which typically occurs directly or indirectly after the coating process when post-processing a cylinder crankcase. This chamfered edge area must be designed so that it is completely removed by chamfering, for example, by a milling tool.On the other hand, the edge area must not be too narrow or too irregular, otherwise sufficient mechanical strength will not be achieved and the remaining coating in the interior may be damaged. Alternatively, the diameter of the through-hole must be exactly equal to or smaller than the diameter of the cylinder to be coated.

[0052] Masking systems are known in the prior art that incorporate a sacrificial ring which is axially directly adjacent to the surface to be shielded. This sacrificial ring exhibits explicitly good adhesive properties for the coating material in order to prevent dust from falling into the interior to be coated and thus causing damage. Due to the narrow tolerance between the maximum and minimum edge widths, and also the reduction in adhesive properties caused by sacrificial coating, such sacrificial rings must be replaced very frequently, for example, after one to six coating processes.

[0053] A solution is described in the aforementioned WO 2016 / 0 015 922 A1. However, this still requires the use of a receiving drum to be coated. Furthermore, the proposed opening angle of 60° at the through-hole is not suitable for all spraying processes, and in particular not for powder spraying. Instead, it leads to deposits and the embedding of dust in the coating.

[0054] The axial extent of the through-hole is preferably perpendicular to the plane defined by the underside. However, this can be adjusted accordingly for different geometries of the object to be coated. Preferably, when coating the running surface of a cylinder crankcase, the axial extent is congruent with the axis of rotation of a cylinder bore during operation.

[0055] It is proposed here to provide an opening angle greater than 75°, preferably greater than 85°, including the axial extent of the through-hole. To keep the masking shield as narrow as possible and thus achieve short feed paths, it is generally not advantageous to provide an angle shallower than 90°, i.e., a negative inclination towards the underside. Furthermore, it is intended to use the masking shield in conjunction with a suction system (i.e., negative pressure) or an air supply (i.e., directed compressed air). The resulting dust should be directed away from the interior to be coated, advantageously at an angle of less than 90°.

[0056] In a powder spraying process, such as atmospheric powder spraying (APS), it is advantageous to use a particularly shallow opening angle of 85° to 88°. This reduces the probability or frequency of adhesion and thus increases the service life of the masking shield.

[0057] In one embodiment, the masking shield is plate-shaped and extends at least as far as the coating-effective conical jet reaches to its tip. This prevents coating-effective particles from adhering to the surfaces of the object to be coated that are to be shielded.

[0058] In a particularly preferred embodiment, the masking shield is asymmetrically designed and covers the entire surface to be shielded and / or the surfaces that are not yet to be coated or are already coated at the specific time of treatment. It must be ensured that the surfaces to be coated or already coated remain accessible for extraction, for example, from the crankcase in the case of a cylinder crankcase. For this purpose, the masking shield is designed to allow air to flow in or out to the surfaces to be coated or already coated.

[0059] For some applications, it is advantageous to provide a chamfer between the top and bottom surfaces, with the chamfer having a steep angle of contact. This facilitates a cleanly defined coating of the edge during interior coating. When the masking shield is lifted after the coating process, the coating material adheres to the surface to be coated due to the cohesive effect and detaches from the masking shield without leaving any residue. This chamfer exhibits a non-stick property, as described above with reference to the top surface, preferably by using the same material or coating.

[0060] The masking shield is unsuitable for the adhesion of coating material applied by a hot gas jet, at least at the transition from the through-opening, and preferably across the entire upper surface. Preferably, it has a surface made of, or is formed from, solid material of: Polytetrafluoroethylene (PTFE); or compounds containing at least one of the following materials: - diamond-like carbon [DLC]; - Silicon DLC [Si-DLC] - Metal DLC - tetrahedral hydrogen-free amorphous carbon layer [ta-C] - diamond-like carbon layers - Titanium nitride [TiN]; - Titanium boron nitride [TiBN]; - Titanium boroide [TiB2]; - Titanium aluminum nitride [TiAlN] - Chromium nitride [Cr2N] or alloys, with the following main component: - Copper; - Brass; - Bronze.

[0061] The choice of suitable material depends on the desired service life, the selected opening angle, and the coating process. It is known to those skilled in the art which materials exhibit better or worse adhesion properties for the respective plasma spraying process. Particularly in combination with the chamfer for a steep contact angle at the transition from the top surface to the through-hole, temperature-stable diamond-like carbon (DLC) coatings, silicon DLC (Si-DLC), or metal DLC coatings are advantageous, achieving particularly low adhesion. A suitable material should possess the following properties: In addition to the aforementioned non-stick properties, it should form a scratch-resistant and abrasion-resistant surface, be temperature-stable up to 500 °C, and exhibit suitable chemical resistance.

[0062] If the masking shield has an intermediate surface, for example a chamfer, between the top and bottom surfaces, this surface is designed with the aforementioned non-stick properties according to this embodiment. To further improve service life, a corresponding non-stick property is also provided for the top surface, preferably the entire top surface including the opening angle. For some applications, it is more cost-effective to use different materials or coatings because the probability of coating-effective particles impacting the shield varies geometrically.Thus, in an area with a high probability of impact, a material with poor adhesion properties, such as PTFE, diamond-like carbon (DLC) coatings, silicon DLC (Si-DLC) coatings, or metal DLC coatings, should be used, while in another area with a lower probability of impact, a material with potentially better adhesion properties, such as bronze, should be used. This selection should be based on the desired service life and the costs of the materials and manufacturing.

[0063] According to an advantageous embodiment of the masking shield, the upper surface extends with the opening angle to the through-opening.

[0064] It is proposed here that the top surface with the shallow opening angle should be positioned directly adjacent to the underside, i.e., during operation, the surface of the object to be coated that is to be shielded. This ensures that the masking shield has no area that could be subject to increased adhesion.

[0065] According to an advantageous embodiment of the masking shield, the underside has a recessed area which has low roughness and high flatness, preferably polished.

[0066] For easy and effective application of the masking shield to the surface to be shielded, the underside should be made particularly smooth. Placing it on an equally smooth surface to be shielded then results in a reliable seal at the gap between the masking shield and the object to be coated, preventing any particles that could affect the coating, and also little to no dust, from penetrating.

[0067] However, such a surface is complex to manufacture. Therefore, it is proposed here to design the contact area, i.e., the underside that acts as the contact surface, as small as possible and to make it just large enough to completely enclose the through-hole. This creates a sealing ring. Additionally, it is advantageous to provide stabilizing surfaces and / or struts extending radially outwards from the sealing ring. This promotes, for example, a defined, smooth contact surface. In this way, even with a particularly thin design, the opening angle of the top surface is maintained.

[0068] According to a further aspect of the invention, a coating system for the thermal coating of a metallic interior surface is proposed, comprising a coating lance and a masking shield, preferably as described above. During coating operation, the portion of the conical jet dispensed above the top surface by the coating lance is directed at a shallow angle to the top surface, wherein the angle between the portion of the conical jet and the top surface is less than 10° or negative, preferably between 5° and -45°.

[0069] The coating system comprises a coating lance according to the prior art together with a masking shield according to the above description, or conversely, a coating lance according to the above description and a masking shield according to the prior art, or a combination of a prior art masking shield and a prior art coating lance, such that in each case the discharge angle is less than 10°. Alternatively, both system components are designed according to the above description. Reference is also made to the above definitions in the case of an embodiment with prior art elements.

[0070] The coating lance is designed for immersion into an interior space, such as the cylinder bore of a cylinder crankcase. The coating lance is to be started outside the interior space to be coated and generate a stable, effective conical spray pattern before the spray pattern is directed onto the surface to be coated. Likewise, the spray pattern should only be switched off after coating is complete once the spray pattern is outside the interior space. The metallic interior surface is, for example, an aluminum surface, which is preferably roughened beforehand, for example by sandblasting.

[0071] The respective angle, i.e., the center axis alignment or the maximum angle and, respectively, the opening angle, must be adjusted accordingly. This prevents or at least reduces the adhesion of coating-relevant particles to the masking shield to such an extent that the service life of the masking shield is multiplied, for example, from currently requiring manual replacement of the sacrificial ring after one to six coats to one to six months. The service life refers to the entire masking shield or at least the top surface with the opening angle, whereby the other components of the masking shield have equally long or longer service lives.

[0072] Preferably, the masking shield and the coating lance are guided together and can be moved together from one surface to be coated to the other, or each can be fed into the coating system. The coating lance is axially movable along its insertion direction relative to the masking shield, at least when the masking shield is in a sealing position against the surface to be shielded.

[0073] The area above the top surface is the area in which a surface normal of the top surface points.

[0074] The portion of the conical jet projected above the top surface is the entire portion that is not intended to adhere to the surface to be coated. This does not include any portion intended for an edge coating, even if this is removed in a later process step. Rather, in the coating process discussed here, this area is considered the surface to be coated.

[0075] The discharge angle is the angle between any portion of the conical jet ejected above the top surface and the top surface with the opening angle. Along this discharge angle, the ejected particles can be discharged without adhesion. This is facilitated by suction and / or airflow, preferably parallel to the top surface.

[0076] The deflection angle is 0° when a portion of the conical jet is dispensed parallel to the surface. If the portion of the conical jet is inclined away from the top of the masking shield, the deflection angle is negative. The maximum deflection angle is determined by the minimum angle of the coating-effective conical jet that is technically useful for the coating process. The minimum angle is the angle opposite the maximum angle defined above, measured on the surface of the coating-effective conical jet. The maximum fan of the coating-effective conical jet is thus defined by the minimum and maximum angles. The maximum deflection angle is therefore less than (minus) 60°, preferably less than (minus) 45°. The maximum deflection angle is a maximum of 10°, preferably less than 5°.

[0077] According to a further aspect of the invention, a process box for the thermal coating of a metallic interior surface is proposed, which has at least one coating system according to the above description, wherein the at least one coating system is integrated into a closed, extractable housing, wherein the coating-effective conical jet has a radiating end in the direction of the jet, behind which the conical jet is no longer coating-effective, and wherein the coating-effective conical jet, up to the radiating end, can only strike the top of the masking shield or a surface unsuitable for adhesion.

[0078] The process box forms a chamber with a volume accessible solely through the through-hole and air exhaust system. Design-related gaps are disregarded. Thus, the dust generated by the continuously operating cone jet is collected within the process box, unless it is expelled through a rear surface. In the case of a cylinder crankcase, the rear surface is, for example, the crankcase. The volume of such a process box is therefore small compared to coating in an open space. At the same time, no sacrificial ring is required, and no other deposits are expected within the process box that would necessitate a service life of less than one month, preferably less than six months. In particular, it is unnecessary to manually replace a component after one or two coating layers.

[0079] The dust-laden air in the process box is removed by means of an extraction system or air duct and fed to an external separator.

[0080] The through-opening of the process box can be closed when the underside of the masking shield is lifted from the surface to be shielded. Alternatively or additionally, a shielding device is provided to protect the object to be coated from dust accumulation in the area of ​​the surfaces to be coated.

[0081] According to a further aspect of the invention, a coating system for thermally coating a cylinder crankcase for an internal combustion engine is proposed, which comprises at least the following elements: - Delivery system for the aligned delivery of at least one cylinder crankcase, preferably a rotary table; - Process box as described above, which can be lowered as a unit onto at least one cylinder crankcase sealed with the underside of the masking shield; and - Extraction system for extracting coating material applied to the process box.

[0082] The coating system is designed for the fully automated thermal coating of the cylinder bores of a cylinder crankcase. A multi-axis robot is not required to replace or support human movement. Instead, a cylinder crankcase placed on the infeed system is moved to the processing position using a uniaxial movement, for example, by rotating a rotary table. Similarly, the process box is placed onto the cylinder crankcase, which is now in the processing position, using a uniaxial movement, for example, by lowering it vertically from above onto the top deck of the cylinder crankcase. Optionally, for V-engines or W-engines, a swivel axis transverse to the cylinder bore axes is provided, allowing the cylinder bores to be aligned vertically.Regardless, a delivery means can be provided by which the cylinder bores can be delivered to the coating system in a row, or by which the coating system can be delivered to the cylinder bores one after the other.

[0083] The extraction system is designed to remove and preferably filter out the dust generated in the process box and at least parts of the cylinder bore. The extraction system is designed to create a negative pressure in the process box and / or is supported by a compressed air system within the process box.

[0084] According to a further aspect of the invention, a method for thermally coating a metallic interior surface of an object, preferably by means of a coating lance as described above, is proposed, which comprises at least the following steps: a. Operating a stable, coating-effective conical jet using a hot gas jet and a coating material in an extended position, such that an interior surface to be coated is not hit by the conical jet, at least not in a coating-effective manner; b. simultaneously with or before step a., aligned placement of a masking shield, preferably according to the above description, onto a surface of the object to be shielded, with a through-opening aligned in such a way that surfaces of the object to be shielded are protected from coating by means of the masking shield in every axial operating position of the cone jet and an interior surface to be coated is accessible to the cone jet for coating by means of the through-opening; c. subsequently, following steps a. and b., immersion of the coating-effective conical jet into the interior with the interior surface to be coated along an insertion direction, wherein the coating-effective conical jet has a generatrix inclined maximally away from the insertion direction, and wherein the angle of impact on the passage opening side between the maximally inclined generatrix and the interior surface to be coated is equal to or greater than 90°, preferably greater than 95°.

[0085] The method described here refers to the devices explained above for coating an internal surface of an object, such as the cylinder bore of a cylinder crankcase. Reference is made to these devices accordingly. Further steps of the method described here can also be derived from the rest of the description with reference to the devices.

[0086] Step a. ensures that a conical jet is generated, enabling reliable coating quality. Switching the system on and off takes place outside the interior.

[0087] In step b., the masking shield is placed on the surface of the object to be shielded in such a way that the surface to be coated is precisely exposed. For example, in the case of a cylinder crankcase, a cylinder bore is exposed by means of the through-hole, whereby the through-hole is preferably slightly spaced from the upper edge of the cylinder bore, i.e., the diameter of the through-hole is somewhat larger than the diameter of the cylinder bore. This ensures that the desired edge coating is achieved. However, a through-hole with a diameter equal to or slightly smaller than the cylinder bore can also be used.

[0088] In step c., the coating lance is immersed into the interior, and the interior surface is coated once or multiple times using a well-known or professionally determined movement sequence of the coating lance. A coating-effective conical jet is operated stably until the coating is complete. The conical jet is only switched off after the lance has completely re-emerged from the interior. For many applications, the conical jet is operated stably in the re-emerged position (i.e., after being extended from the interior) for multiple coatings and / or multiple interiors.

[0089] Assuming an ideally straight generatrix according to the asterisk theorem, with the insertion direction and the interior surface to be coated aligned parallel, the angle of impact is the supplementary angle to the maximum angle defined above, as described above with reference to the insertion direction. If, for example, the coating lance enters an interior space along the force of gravity, the angle of impact, corresponding to this orientation, is to be measured from above the conical jet relative to the interior surface to be coated, and is therefore an angle greater than 90°. Reference is made to the above description regarding the maximum angle.

[0090] Preferably, the above-described method is integrated into a multi-station post-processing procedure. For example, coating is preceded by corundum blasting, water blasting, laser beam roughening, or mechanical roughening with a geometrically defined surface, including a washing process, followed by a washing process. Preferably, the objects to be coated are fed automatically, eliminating the need for manual manipulation or the use of a multi-axis robot to replace human movement. Brief description of the drawings

[0091] Exemplary embodiments of the invention are explained in more detail below with reference to the drawing. The drawing shows Fig. 1 in a schematic sectional view a coating lance head on a holding lance in an interior space to be coated, Fig. 2 in a spatial view a coating system with a masking shield placed on a cylinder crankcase, Fig. 3 in a top view a preferred embodiment of a masking shield, Fig. 4 in a side sectional view the masking shield according to Fig. 3, Fig. 5 in the same section view as in Fig. 4 another embodiment of a masking shield, Fig. Figure 6 shows a schematic sectional view of a coating system with a process box above a delivery system. Best way to implement the invention

[0092] In Fig. Figure 1 shows a section of a coating lance 200 with a coating lance head 100. The coating lance head 100 is attached to a holding lance 15 by means of an angle bracket 14 such that a central axis 17 of a hot gas jet 12 is aligned at a jet angle 18 of approximately 70° enclosed between an insertion direction 16 of the holding lance 15 and the central axis 17. The insertion direction 16 is a perpendicular line parallel to the axis of rotation 42 of the interior space 38, shown here schematically, for example, a cylinder bore of a cylinder crankcase, with a metallic surface 10 to be coated, for example, made of aluminum.

[0093] In this illustration, the angle bracket 14 forms a horizontal connection plane to the holding lance 15, in which the following lines, shown here in section, are connected via corresponding connections: a gas line 45 with a gas connection 46, through which a plasma nozzle 11 can be supplied with the gas for the hot gas jet 12; a coolant line 47 with a coolant connection 48, through which, for example, accompanied cooling with compressed air is ensured; a feed line 43 with a feed connection 44, through which coating material, for example a metallic powder, can be supplied, preferably by means of a transport gas.

[0094] The plasma nozzle 11 of the type shown here has a cathode 40, comprising, for example, tungsten, and a nozzle body as the anode 41, between which an electrical voltage can be applied, thus generating an electric arc. The gas flowing through the anode is thereby heated and at least partially ionized, thus generating the hot gas jet 12. The velocity, temperature, and central axis orientation 17 of the hot gas jet 12 are determined by the volume flow through the gas line 45 and the shape of the nozzle body, i.e., the anode 41. Powder is fed laterally and transversely to the hot gas jet 12 by means of a feed device 13, which can be supplied via the feed line 43.The particles of the conical jet 19 thus generated are carried along in the direction 33 by the hot gas jet 12 and propelled against the surface 10 to be coated, where they adhere permanently to create a desired surface property, for example, low roughness and good flatness as a running surface for a piston of an internal combustion engine. In the purely schematic representation shown here, the resulting coating-effective conical jet 19, with a downward-sloping generatrix 20 and an upward-sloping generatrix 39, is laterally offset from the central axis 17 and inclined downwards, with its (not shown) cone height. This is a consequence of the feed velocity of the coating material and the parameters of the hot gas jet 12. The downward-sloping generatrix 20 forms a maximum angle 21 with the feed direction 16. In the present example, the maximum angle 21 is approximately 80°.

[0095] In Fig. Figure 2 shows a masking shield 300 with an asymmetrically arranged through-opening 26 with an axial extent 27 for a coating lance 200. The masking shield 300, with its underside 23 (hidden here), is lowered onto an object 22 (shown only partially), so that a predetermined surface 24 (hidden here) is shielded, but the coating lance 200 can be immersed into the interior 38. The object 22 is, for example, a cylinder crankcase of an internal combustion engine, and the interior 38 is a cylinder bore. The through-opening 26 is slightly larger than the diameter of the interior to be coated, so that edge coating can be produced when the coating lance 200 is immersed and withdrawn. The upper surface 25 is inclined, for example, concentrically to the axial extent 27, and in this example adjoins the through-opening 26 directly.The upper surface 25 transitions seamlessly, for example in one piece, into an outer surface 29 radially outwards. The outer surface 29 is parallel to the lower surface 23 and thus inclined away from the upper surface 25 towards the object 22.

[0096] In Fig. Figure 3 shows a masking plate 300 or a section of a masking plate 300 essentially limited to the top surface 25, shown in a top view. A through-opening 26, concentric with the axial extent 27, is shown centrally to the top surface 25. The top surface 25 transitions into a sloping outer area 29, which is formed here only by a chamfer. A back-mounted, recessed area 30 is indicated by a dashed line with a similarly dashed reference line. In this example, the recessed area 30 is designed as a strip that extends from left to right across the entire width of the masking plate 300 in the illustration and also forms bulges in the vicinity of the through-opening 26, thus creating a predetermined minimum distance to the axial extent 27. A sectioning plane AA is also marked in this illustration, which is shown perpendicular to the axial extent 27.

[0097] In Fig. Figure 4 is a section of a cut along the cutting plane AA of the masking shield 300, as shown in Fig. Figure 3 shows an opening angle 28 of approximately 80°, enclosed by the top surface 25 and the axial extension 27. A particularly preferred embodiment is shown in which the top surface 25 initially transitions at an angle of approximately 5° from the edge of the through-opening 26 to an angle of approximately 15° further outwards, before the top surface 25 transitions into the outer area 29, for example, a chamfer. The recessed area 30, on which the bottom surface 23 is formed, is also shown. In this embodiment, the flat bottom surface 23 and the top surface 25 abut each other directly at the edge of the through-opening 26.

[0098] In Fig. 5 is a similar cut to the one in Fig. Figure 4 shows a different embodiment of the masking shield 300. Reference is made to the preceding description for identical elements with the same reference numerals. In this embodiment, the top surface 25 is flat and formed with an opening angle 28 of approximately 82°. The top surface 25 does not directly abut the bottom surface 23; instead, a chamfer 49 is formed between them. This chamfer 49 has an angle 50 of approximately 45° to the flat bottom surface 23.

[0099] In Fig. Figure 6 shows a purely schematic sectional view of a coating system 600 for a cylinder crankcase 35. This system comprises a coating system 400, consisting of a masking shield 300 and a coating lance 200, which is arranged in a process box 500. The cylinder crankcase 35 is the object 22 to be coated, wherein a first interior space 38, namely a cylinder bore rotationally symmetrical with respect to the axis of rotation 42, has already been provided with a coating 52, shown here as a dashed line, on the surface 10 to be coated. All other surfaces 24 of the object 22 to be coated were shielded during the previous coating process by means of the masking shield 300 or the process box 500.

[0100] The cylinder crankcase 35 was positioned for coating by the coating lance 200 using an automated or manually fed feeding system 36, for example, a rotary table, by rotating it in the direction of rotation 54 about the axis of rotation 53. The process box 500 was placed on the surface 24 to be shielded along the placement direction 55 with the underside 23 of the masking shield 300. Subsequently, the coating lance 200, which was already generating a stable conical jet 19, was immersed through the through-opening 26 into the interior 38 and, by at least one immersion and re-emergence, applied the coating 52 to the surface 10 to be coated. After completion of the coating 52, the coating lance 200 was re-emergended through the through-opening 26 and the process box 500 was lifted along the placement direction 55.

[0101] In the illustrated state, the coating lance 200 is in a fully submerged position, in which the entire coating-effective conical jet 19 is directed into the interior of the housing 32 of the process box 500. Due to the inclination of the conical jet 19 by means of the central axis alignment 18 (see figure 1), the coating lance 200 is fully submerged, and the conical jet 19 is directed into the interior of the housing 32 of the process box 500. Fig.1) The maximum angle 21 is aligned approximately parallel to the opening angle 28 of the top surface 25. The deflection angle 31 between the sloping generatrix 20 and the top surface 25 is therefore approximately 0°. Up to a beam end 34, beyond which, in the illustration further to the left, no more coating-effective particles are present, the conical beam 19 does not encounter a counter surface. Furthermore, the top surface 25 borders a sloping outer area 29, so only a vertical wall of the housing 32 of the process box 500 could form a counter surface. It is highly unlikely that a coating-effective particle would be accelerated beyond the beam end 34 and adhere to it.To ensure that the generated dust does not enter the area of ​​the object 22 to be coated through the opening 26, an extraction system 37 is provided, which extracts the dust via the extraction openings 51 located well outside the coating cone jet 19. The pipes and filters are only shown in sketch form.

[0102] The resulting shallow discharge angle significantly increases the service life, which is limited by adhesion in the prior art, compared to a conventional coating system. Reference symbol list 100 coating lance heads 200 coating lance 10 metallic surfaces 11 Plasma nozzle 12 Hot gas jet 13 Feeding device 14 angle bracket 15 Holding lance 16 Insertion direction 17 Center axis alignment 18 beam angles 19 Cone beam 20 sloping generatrix 21 Maximum angles 300 masking shield 22 objects 23 Underside 24 surfaces to be shielded 25 Top 26 Passage opening 27 axial extension 28 opening angles 29 Outdoor area 30 separated area 400 coating system 31 Discharge angle 500 process box 32 cases 33 Beam direction 34 Radiant 600 coating system 35 cylinder crankcase 36 delivery facility 37 Extraction system 38 Interior 39 inclined mantle line 40 Cathode 41 Anode 42 Rotation axis 43 Supply line 44 Supply connection 45 Gas pipeline 46 Gas connection 47 Coolant line 48 Coolant connection 49th phase 50° angle of contact 51 Extraction opening 52 coating 53 Axis of rotation 54 Direction of rotation 55 Direction of landing movement

Claims

[1] Process box (500) for thermally coating a metallic interior surface (10) of an object (22), comprising at least one coating system (400), which includes a coating lance (200) with at least the following elements: - Plasma nozzle (11) for generating a hot gas jet (12), wherein the hot gas jet (12) has a predetermined temperature, velocity and central axis orientation (17); - Feeding device (13) for feeding coating material in solid phase towards the hot gas jet (12); and - Holding lance (15), wherein the holding lance (15) has an insertion direction (16), wherein a jet angle (18) enclosed with the holding lance (15) is formed between the insertion direction (16) of the holding lance (15) and the central axis alignment (17) of the hot gas jet (12), which is less than 90°, and a masking shield (300), wherein in the coating operation of the coating lance (200) the portion of the conical jet (19) applied above a top surface (25) of the mask device (300) is directed at a shallow deflection angle (31) to the top surface (25), wherein the deflection angle (31) between the portion of the conical jet (19) and the top surface (25) is less than 10° or negative, wherein a negative deflection angle (31) is inclined away from the top surface (25), wherein at least one coating system (400) is integrated into a closed, extractable housing (32), wherein the coating-effective conical jet (19) has a jet end (34) in the jet direction (33), behind which the conical jet (19) is no longer coating-effective, and wherein the coating-effective conical jet (19) up to the jet end (34) can only hit the top (25) of the masking shield (300) or a surface unsuitable for adhesion. [2] Process box (500) according to claim 1, wherein the masking shield (300) comprises at least the following elements: - Underside (23) for placement on a surface to be shielded (24); - Top side (25) which faces a coating lance (200) when the coating lance (200) is in an extended position; - Through-opening (26) with an axial extension (27) from the top (25) to the bottom (23) through which a coating lance (200) can be immersed to coat the object (22), wherein the top (25) forms an enclosed opening angle (28) to the axial extension (27) of the through-opening (26) which is greater than 75° and the top (25) has a non-stick property at least in the area of ​​the through-opening (26). [3] Process box (500) according to claim 2, wherein the top (25) extends with the opening angle (28) to the through opening (26). [4] Process box (500) according to claim 2 or 3, wherein the underside (23) has a recessed area (30) which is polished and has low roughness and high flatness. [5] Coating system (600) for thermally coating a cylinder crankcase (35) for an internal combustion engine, comprising at least the following elements: - Delivery system (36) for the aligned delivery of at least one cylinder crankcase (35); - Process box (500) according to one of the preceding claims, which can be lowered as a unit onto at least one cylinder crankcase (35) sealed with the underside (23) of the masking shield (300); and - Extraction system (37) for extracting coating material applied to the process box (500). [6] Method for thermally coating a metallic interior surface (10) of an object (22) using a process box (500) according to one of claims 1 to 4, comprising at least the following steps: a. Operating a stable coating-effective conical jet (19) by means of a hot gas jet (12) and a coating material in an extended position, such that an interior surface (10) to be coated is not struck by the conical jet (19), at least not in a coating-effective manner; b. simultaneously with or before step a., aligned placement of a masking shield (300) on a surface (24) of the object (22) to be shielded, with a through-opening (26) aligned such that surfaces (24) of the object (22) to be shielded are protected from coating by means of the masking shield (300) in every axial operating position of the cone jet (19) and an interior surface (10) to be coated is accessible to the cone jet (19) for coating by means of the through-opening (26); c. subsequently, following steps a. and b., the coating-effective conical jet (19) is immersed into the interior (38) along an insertion direction (16) with the interior surface (10) to be coated, wherein the coating-effective conical jet (19) has a generatrix (20) inclined maximally away from the insertion direction (16), and wherein the angle of impact on the passage-opening side between the maximally inclined generatrix (20) and the interior surface (10) to be coated is equal to or greater than 90°.

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