JP2006057163A - Method for manufacturing cylinder block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a cylinder block, which secures an adequate abrasion property even when required to partially change. <P>SOLUTION: A thermal-sprayed film 103 is formed on an internal circumferential surface of a bore 101a of a cylinder liner 101 by the steps of: supplying an orifice gas from an orifice gas feeder 40 to a plasma spraying device 10; converting the orifice gas into a plasma arc 41 by discharge occurring when an electric current supplied from a power supply 30 is applied to the plasma spraying device; spouting the plasma arc from a nozzle 13a of a thermal spraying gun 13 of the plasma spraying device 10; heating and melting a powder of a thermal spray material delivered from a thermal spray material feeder 20, with the plasma arc 41 spouted from the nozzle 13a; and spouting the material to the internal circumferential surface of the bore. At this time, a thermal spraying parameter is controlled according to an abrasion property which is required to be partially changed in the thermal-sprayed film 103 in a predetermined way, to control the porosity, oxide amount and hardness of the thermal-sprayed film 103. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a cylinder block of an engine, and more particularly to a method for manufacturing a cylinder block in which a thermal spray coating is formed on a bore inner peripheral surface by a thermal spraying method.

  For example, a piston connected to a crankshaft via a piston pin and a connecting rod is mounted on a bore inner circumferential surface of a cylinder liner provided in a cylinder block body of an engine so as to be reciprocally movable along a bore center line direction. The inner circumferential surface of the bore of the cylinder liner is basically processed to have a uniform surface roughness in order to ensure sliding characteristics with respect to the piston ring and the piston.

  However, in such an engine, a piston thrust force in the direction of the bore center line acts on the piston pin as the crank shaft rotates, so that the piston swings around the piston pin. Therefore, the contact between the piston and the cylinder liner causes not only the sliding between the piston ring and the bore inner peripheral surface of the cylinder liner, but also the collision between the piston skirt portion and the bore inner peripheral surface of the cylinder liner.

  Therefore, recently, the surface roughness of the bore inner peripheral surface of the cylinder liner may be partially changed in order to improve friction loss, fuel consumption, and scuff resistance. For example, the surface roughness of the bore inner circumferential surface portion of the cylinder liner on which the piston ring slides is made smaller than the surface roughness of the bore inner circumferential surface portion of the cylinder liner on which the piston skirt slides. Some have improved sliding characteristics and scuff resistance by retaining oil in the larger bore inner peripheral surface.

  On the other hand, if the bore inner peripheral portion on the cylinder head side is rougher than the bore inner peripheral surface portion on which the piston ring, which is the upper end portion of the bore inner peripheral surface of the cylinder liner, slides, unburned gas accumulates in this portion. Since NOx is likely to be generated, the surface roughness between the upper end portion of the bore inner peripheral surface and the upper portion of the piston ring at the top dead center may be made smaller than the surface roughness of other portions.

  In this way, when honing the bore inner peripheral surface of the cylinder liner where the surface roughness is partially changed with a grindstone provided at the tip of the honing head, the grindstone expansion pressure of the grindstone in the region where the surface roughness is small is There is known a method of performing honing by lowering the grindstone expansion pressure of a grindstone in a large area. In addition, the method of honing by making the grindstone particle size corresponding to the low surface roughness region finer than the grindstone particle size corresponding to the high surface roughness region, the low surface roughness region and the high surface roughness region A cylinder block finishing method is known in which only a region having a small surface roughness is subjected to a roller burnish finish after the honing process is performed (see, for example, Patent Document 1).

  Further, in order to improve the scuff resistance against the piston ring and the piston skirt, there is a thermal spraying method in which a thermal spray coating is formed by spraying powder of a thermal spray material on the inner peripheral surface of the bore of the cylinder liner. When forming a thermal spray coating by this thermal spraying method, manufacture a cylinder block in which the inner peripheral surface portion of the bore where the piston skirt part that requires scuffing resistance slides is a high hardness region and the other part is a low hardness region A method is known (for example, Patent Document 2).

JP-A-7-54707 JP-A-8-246944

  According to the cylinder block finishing method described in Patent Document 1, when the inner surface of the cylinder liner is honed with a grindstone, it is provided at the tip of the honing head according to the surface roughness of the bore inner peripheral surface of the cylinder liner. Only the region with small surface roughness after honing the bore inner peripheral surface by changing the grinding wheel expansion pressure of the grindstone or by honing using a grindstone with a grain size corresponding to the surface roughness of the bore inner peripheral surface Can be machined on the inner peripheral surface of the bore of the cylinder liner where the surface roughness changes partially.

  However, the bore inner peripheral surface is further honed by changing the grinding wheel expansion pressure according to the surface roughness region of the bore inner peripheral surface or by using a grindstone having a particle size corresponding to the surface roughness region of the bore inner peripheral surface. Then, since the region having a small surface roughness is roller burnished, the processing becomes complicated and a step may be formed in a portion where the surface roughness changes. In addition, honing is performed by reciprocating the grindstone provided at the tip of the honing head with a predetermined stroke in the bore center line direction, so if the surface roughness partially changes, the stroke is in a very small range. However, there is a concern that workability is reduced and the manufacturing cost is increased.

  On the other hand, according to Patent Document 2, scuff resistance can be ensured by heating the inner peripheral surface of the bore where scuff resistance is required by the sprayed coating to a high hardness region and the other portion to a low hardness region, and the melted material is heated and melted. Since the thermal spray coating is formed by spraying the powder of the thermal spray material, a step between the high hardness region and the low hardness region can be suppressed by forming an intermediate hardness region between the high hardness region and the low hardness region.

  However, the porosity of the thermal spray coating increases as it shifts from the high hardness region to the low hardness region, and this hole becomes an oil reservoir, so the amount of oil retained becomes excessive in the low hardness region where the porosity is large. On the other hand, in a high hardness region where the porosity is small, the amount of oil retained decreases and becomes a factor inducing wear. That is, when the wear characteristics change partially, it is not possible to cope with it sufficiently, and there is a concern that good wear characteristics of the bore inner peripheral surface cannot be secured.

  Accordingly, an object of the present invention made in view of such a point is to provide a method of manufacturing a cylinder block that can ensure wear characteristics having a partial change in the bore inner peripheral surface.

  The invention of the cylinder block manufacturing method according to claim 1, which achieves the above object, comprises a plasma spraying device and a spraying material supply device for feeding powders of different types of spraying materials to the plasma spraying device by a carrier gas. And a working gas supply device for supplying different types of working gas to the plasma spraying device, and a power supply device for supplying power to the plasma spraying device, from the working gas supply device to the plasma spraying device. The supplied working gas becomes a plasma arc by discharge due to application of current supplied from the power supply device, and is sprayed from a nozzle that opens in a spray gun of the plasma spraying device, and the spraying is performed by the plasma arc sprayed from the nozzle. The powder of the thermal spray material fed from the material supply device to the plasma spraying device is heated and melted and blown to the inner peripheral surface of the bore. In the cylinder block manufacturing method for forming the spray coating on the inner peripheral surface of the bore, the spray material supply device, the working gas supply device, and the power supply device based on the required wear characteristics that change partially in the preset spray coating The thermal spraying conditions are controlled by controlling at least one of the above, and the porosity, oxide amount, and hardness of the thermal spray coating formed on the inner peripheral surface of the bore are controlled.

  The invention according to claim 2 is the cylinder block manufacturing method according to claim 1, wherein the spraying conditions are controlled by powder blending of a plurality of types of spraying materials supplied to the plasma spraying device by the spraying material supply device. Control of ratio, control of supply amount of sprayed material powder by the spraying material supply device, control of supply amount of carrier gas by the spraying material supply device, kind of working gas supplied to the plasma spraying device by the working gas supply device Switching control, control of the mixing ratio of a plurality of working gases by the working gas supply device, and control of the amount of power supplied to the plasma spraying device by the power supply device. Features.

  According to the first aspect of the present invention, the spraying conditions are controlled on the basis of a preset required wear characteristic of the sprayed coating, and the porosity and oxide amount of the sprayed coating formed on the inner peripheral surface of the bore are controlled. By controlling the hardness, it is possible to manufacture a cylinder block formed with a sprayed coating that can ensure a partially changing wear characteristic on the inner peripheral surface of the bore.

  The invention of claim 2 exemplifies the specific control of the thermal spraying condition of claim 1, and according to the requirement by performing each control individually or in parallel with a plurality of controls according to the required wear characteristics. A sprayed coating having excellent wear characteristics can be formed on the inner peripheral surface of the bore.

  Hereinafter, an embodiment of a cylinder block manufacturing method according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic configuration diagram of a thermal spray coating forming apparatus according to the present embodiment, and FIG. 2 is a diagram illustrating a main part of the thermal spray coating forming apparatus.

  The spray coating apparatus 1 forms a spray coating 103 on a bore inner peripheral surface 101a of a cylinder liner 101 provided in a cylinder block body of an engine.

  The thermal spray coating apparatus 1 sprays a thermal spray material toward the bore inner peripheral surface 101 a of the cylinder liner 101 to form the thermal spray coating 103, and supplies the thermal spray material 10 with powder of the thermal spray material. Thermal spray material supply device 20, electric power supply device 30 that applies a current for melting the thermal spray material to plasma spray device 10, and working gas supply device 40 that supplies a working gas for flying the molten thermal spray material to plasma spray device 10 The thermal spray material supply device 20, the power supply device 30, and the working gas supply device 40 are provided with a thermal spray control device 50 and a thermal spray gun attitude control device 60.

  The plasma spraying apparatus 10 supports a spraying gun holding robot 11 and a spraying gun 13 that is supported by the spraying gun holding robot 11 and extends in the vertical direction, and that is rotated around the axis L thereof. The tip of the spray gun 13 is a cylinder along the bore center line of the cylinder liner 101 set in a holding jig (not shown) by lowering the spray gun rotating device 12 along the axis L by the spray gun holding robot 11. It is inserted into the bore 102 of the liner 101. The raising and lowering and lowering speeds of the spray gun 13 by the spray gun holding robot 11, that is, the gun feed speed and the rotation speed of the spray gun 13 by the spray gun rotating device 12 are set in advance according to the type and specification of the cylinder liner 101 to be sprayed. It is controlled by a control signal from the spray gun attitude control device 60 according to the spraying conditions.

  The thermal spray material supply device 20 is composed of a plurality of different types of thermal spray material powders, in this embodiment, two types of thermal spray materials, that is, a relatively low melting point powder A and a relatively high melting point powder B, respectively. Alternatively, both the powder A and the powder B mixed at the set blending ratio are fed to the plasma spraying apparatus 10 by the carrier gas.

  The supply amount of powder A and powder B, the blending ratio of powder A and powder B, and the supply amount of carrier gas in the spray material supply apparatus 20 are set in advance according to the type and specification of the cylinder liner 101 to be sprayed. It is controlled by a control signal from the thermal spray control device 50 according to the conditions.

The working gas supply device 40 includes a plurality of kinds of working gases such as Ar, N ₂ , and H ₂ , and in the present embodiment, the two kinds of first gas and second gas are used alone or in a set blending ratio. One gas and the second gas are supplied to the plasma spraying apparatus 10. The switching between the first gas and the second gas supplied to the plasma spraying device 10 in the working gas supply device 40, the supply amounts of the first gas and the second gas, the blending ratio of the first gas and the second gas, and the like are set in advance. It is controlled by a control signal from the thermal spray control device 50 according to the thermal spraying conditions set according to the type and specification of the cylinder liner 101 to be sprayed.

  The electrical control from the power supply device 30 that applies a current for melting the spray material to the plasma spraying device 10 is performed in accordance with the spraying conditions set in accordance with the type and specification of the cylinder liner 101 to be sprayed in advance. This is performed in accordance with a control signal from 50.

  Next, the manufacturing method of the cylinder block using the sprayed-film formation apparatus 1 comprised in this way is demonstrated.

  First, as a pretreatment step of the thermal spraying process for forming the thermal spray coating 103 by the thermal spray coating apparatus 1, in order to improve the adhesion strength of the thermal spray coating 103, the bore inner peripheral surface 101a of the cylinder liner 101 is granular with compressed air. A shot blasting process is performed by spraying a blasting material to clean and roughen the bore inner peripheral surface 101a of the cylinder liner 101.

  Next, the pretreated cylinder liner 101 is set on a holding jig (not shown) of the spray coating apparatus 1.

  In the thermal spraying process, the thermal spray gun holding robot 11 of the plasma thermal spraying apparatus 10 positions the thermal spray gun 13 at an intended position that is coaxial with the bore center line of the cylinder liner 101 set on the holding jig.

  Then, as shown in FIGS. 1 and 2, the spray gun 13 is lowered along the axis L by the spray gun holding robot 11 that is controlled by a control signal from the spray gun attitude control device 60 in accordance with preset spray conditions. Is inserted into the bore 102 of the cylinder liner 101. Further, the spray gun 13 is given rotation by the spray gun rotating device 12 and feed along the axis L direction by the spray gun holding robot 11.

  On the other hand, the working gas in which the first gas or the second gas, or the first gas and the second gas are mixed at a set mixing ratio from the working gas supply device 40 by the control signal from the thermal spray control device 50 is supplied to the plasma spraying device 10. When the current is applied by the power supply device 30 and supplied from the working gas supply device 30, the working gas supplied from the working gas supply device 40 becomes a plasma arc 41 due to discharge, and the nozzle 13 a opened at the tip of the spray gun 13 at high speed. It is injected toward the bore inner peripheral surface 103a.

  The powder A or powder B of the thermal spray material supplied from the thermal spray material supply device 20 or the powder A and the powder B mixed at a set blending ratio are fed to the vicinity of the tip of the thermal spray gun 13 by the carrier gas, and plasma It is heated and melted by the arc 41 and flies while atomizing, and is welded to the bore inner peripheral surface 101 a of the cylinder liner 101. As a result, a sprayed coating 103 having a predetermined thickness is formed on the bore inner peripheral surface 101a.

  Here, the porosity, oxide amount, and hardness of the thermal spray coating 103 are changed by changing the thermal spray material supplied from the thermal spray material supply device 20 to the plasma thermal spray device 10 by a control signal from the thermal spray control device 50 during the thermal spraying, that is, The powder A and the powder B, which are the thermal spray materials supplied from the thermal spray material supply device 20 to the plasma thermal spray device 10, are emptied individually or by mixing and supplying the powder A and the powder B in a set blending ratio. Porosity, oxide production, and hardness can be easily controlled.

Further, by changing the spraying conditions so as to lower the spraying temperature when spraying, for example, the control signal from the spray control device 50 lowers the current value supplied from the power supply device 30 to the plasma spray device 10 or supplies the working gas. For example, when the first gas is Ar (argon) and the second gas is H ₂ (hydrogen), the working gas supplied from the apparatus 40 to the plasma spraying apparatus 10 is reduced by reducing the second gas or the first gas. It is possible to control to increase the porosity of the thermal spray coating 103 by increasing. Further, by changing the thermal spray material supplied from the thermal spray material supply apparatus 20 to the plasma thermal spray apparatus 10 from the powder A having a relatively low melting point to the powder B having a relatively high melting point, the molten state of the powder is changed and the thermal spray coating 103 is formed. Porosity increases. Further, by changing the blending ratio of the powder A and the powder B to the side where the powder A having a relatively low melting point is decreased and the powder B having a relatively high melting point is increased, the molten state of the powder is changed. Porosity increases.

  On the other hand, the current value supplied from the power supply device 30 to the plasma spraying device 10 is increased or the working gas is supplied by changing the spraying conditions so as to increase the spraying temperature when spraying, for example, by a control signal from the spraying control device 50. The porosity of the thermal spray coating 103 can be reduced by increasing the second gas of the working gas supplied from the apparatus 40 to the plasma spraying apparatus 10 or by decreasing the first gas. Further, by changing the thermal spray material supplied from the thermal spray material supply apparatus 20 to the plasma thermal spray apparatus 10 from the relatively high melting point powder B to the relatively low melting point powder A, the blending ratio of the powder A and the powder B is further increased. The porosity of the thermal spray coating 103 can be reduced by changing to the side where the powder A having a relatively low melting point increases and the powder B having a relatively high melting point decreases.

  In addition, the spraying material supplied to the plasma spraying device 10 is increased by increasing the carrier gas in the spraying material supply device 20, or the feed rate of the spraying gun 13 by the spraying gun holding robot 11 is reduced and the spraying gun rotating device 12. The thickness of the thermal spray coating 13 is controlled to increase by decelerating the rotational speed of the thermal spray gun 13.

  On the other hand, the spraying material supplied to the plasma spraying device 10 is decreased by reducing the carrier gas in the spraying material supply device 20, or the feed rate of the spraying gun 13 by the spraying gun holding robot 11 is increased and the spraying gun rotating device. By increasing the rotational speed of the thermal spray gun 13 by 12, the thickness of the thermal spray coating 13 is controlled to decrease.

  Therefore, in the spraying process in which the spraying gun 13 of the plasma spraying device 10 is rotated while being fed in the direction of the axis L, and the spraying material is welded to the bore inner peripheral surface 101a of the cylinder liner 101 to form the sprayed coating 103, an experiment or Based on the partially changed required wear characteristics of the thermal spray coating 103 set by simulation or the like, it becomes possible to control the porosity, oxide amount and hardness of the thermal spray coating 103 by controlling the thermal spraying conditions. A sprayed coating 103 having wear characteristics can be formed on the bore inner peripheral surface 101a.

  That is, the thermal spray supplied to the plasma spraying apparatus 10 by the thermal spray material supply apparatus 20 by a control signal from the thermal spray control apparatus 50 based on the required wear characteristics that partially change of the thermal spray coating 103 set in advance by experiments or simulations. Control of powder mixing ratio of powder A and powder B of material, control of supply amount of powder A and powder B of sprayed material to plasma spraying device 10, control of supply amount of carrier gas, plasma spraying device by working gas supply device 40 10, switching control between the first gas and the second gas supplied to 10, control of the supply amounts of the first gas and the second gas supplied to the plasma spraying device 10, and supply to the plasma spraying device 10 by the power supply device 30. By performing one of each control of the supplied power amount or a plurality of appropriate controls among these controls in parallel, the spray gun attitude control device 60 further By controlling the feed rate of the spray gun 13 by the spray gun holding robot 11 of the plasma spray device 10 and the rotation speed of the spray gun 13 by the spray gun rotating device 12 according to the control signal, the porosity, oxide amount and hardness of the spray coating 103 are controlled. Therefore, it is possible to form the sprayed coating 103 having wear characteristics according to the demand on the bore inner peripheral surface 101a.

  The cylinder liner 101 on which the thermal spray coating 103 of the bore inner peripheral surface 101a is formed is cast into a cylinder block body made of an aluminum alloy or the like in a casting process to form a cylinder block, whereby the bore inner peripheral surface 101a. A cylinder block can be obtained that can ensure wear characteristics having partial changes in the following.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the invention. For example, in the above-described embodiment, the case where the thermal spray materials are two types of powder A and powder B has been described as an example, but three or more different types may be used. Similarly, the case where the working gas is two types of the first gas and the second gas has been described as an example, but three or more different types can be set. Furthermore, in the above embodiment, the case where the sprayed coating 103 is formed on the bore inner peripheral surface 101a of the cylinder liner 101 has been described as an example. However, the bore inner peripheral surface in which the bore is formed in the cylinder block body without using the cylinder liner. Alternatively, the thermal spray coating 103 can be formed in the same manner as described above.

It is a schematic block diagram of the thermal spray coating formation apparatus explaining embodiment of the manufacturing method of the cylinder block which concerns on this invention. It is a figure which shows the principal part of a thermal spray coating formation apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal spray coating apparatus 10 Plasma spray apparatus 11 Thermal spray gun holding robot 12 Gun rotation apparatus 13 Thermal spray gun 13a Nozzle 20 Thermal spray material supply apparatus 30 Electric power supply apparatus 40 Working gas supply apparatus 41 Plasma arc 50 Thermal spray control apparatus 60 Thermal spray gun attitude control apparatus 101 Cylinder liner 101a Bore inner peripheral surface 102 Bore 103 Thermal spray coating

Claims (2)

A plasma spraying device, a thermal spray material supply device that feeds powders of different types of thermal spray materials to the plasma thermal spray device by a carrier gas, and a working gas that delivers different types of working gases to the plasma thermal spray device A supply device and a power supply device for supplying power to the plasma spraying device, wherein the working gas supplied from the working gas supply device to the plasma spraying device is discharged by applying a current supplied from the power supply device. A plasma arc is sprayed from a nozzle that opens to a spray gun of the plasma spraying device, and the sprayed material powder is heated and melted from the spraying material supply device to the plasma spraying device by the plasma arc sprayed from the nozzle. In the manufacturing method of a cylinder block, sprayed on the inner peripheral surface of the bore to form a sprayed coating on the inner peripheral surface of the bore ,
It is formed on the inner peripheral surface of the bore by controlling the spraying condition by controlling at least one of the above-mentioned sprayed material supply device, working gas supply device, and power supply device based on the required wear characteristics that change partially in the preset sprayed coating. A method for producing a cylinder block, comprising controlling the porosity, oxide amount, and hardness of a thermal spray coating. Control of the above spraying conditions
Control of the powder blending ratio of a plurality of types of thermal spray materials fed to the plasma spraying device by the thermal spray material supply device, control of the amount of powder sprayed by the thermal spray material supply device, and carrier gas by the thermal spray material supply device Control of supply amount, switching control of the type of working gas supplied to the plasma spraying device by the working gas supply device, control of a mixture ratio of a plurality of working gases by the working gas supply device, and the plasma by the power supply device 2. The method of manufacturing a cylinder block according to claim 1, wherein the control is at least one of control of the amount of electric power supplied to the thermal spraying device.

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