Manufacturing method for vehicle components and valve seats

Abstract

The present invention provides a vehicle component capable of suppressing welding defects during laser cladding and a method for manufacturing a valve seat using the vehicle component. [Solution] The vehicle member according to the present disclosure is a vehicle member that has undergone laser cladding, in which metal powder is sprayed onto a metal vehicle member, and the metal powder is melted by irradiating it with a laser and welded to the vehicle member, comprising a metal main body and a build-up portion formed by the solidified molten metal powder being welded onto the processed surface of the main body, wherein the distance from the edge of the build-up portion to the edge of the processed surface on which the build-up portion is formed is 0 mm or more and 4 mm or less.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing vehicle members and valve seats.

Background Art

[0002] Patent Document 1 discloses a laser cladding method for preventing welding defects caused by poor welding of clad metal adhering to an unprocessed valve seat portion when performing laser cladding on a plurality of valve seat portions in a cylinder head of an automotive engine. The laser cladding method includes a step of removing the clad metal adhering to the unprocessed valve seat portion by using cleaning means after performing processing on the first valve seat portion.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventors of the present invention have found a problem that welding defects occur when unmelted clad metal adheres to an area where laser cladding is planned to be performed in the valve seat portion. Here, in the laser cladding method disclosed in Patent Document 1, it is impossible to prevent the unmelted clad metal from adhering to the area where laser cladding is planned to be performed in the future. Therefore, there is a risk of welding defects occurring due to the clad metal adhering during processing.

[0005] The present disclosure has been made in view of the above circumstances, and provides a vehicle member capable of suppressing welding defects during laser cladding and a method for manufacturing a valve seat using the vehicle member.

Means for Solving the Problems

[0006] A vehicle component relating to one aspect of this disclosure is A vehicle component that has undergone laser cladding, in which metal powder is sprayed onto a metal vehicle component, and the metal powder is melted by irradiating it with a laser and welded to the vehicle component, The main body is made of metal, The system comprises a built-up portion formed by welding the solidified molten metal powder onto the processed surface of the main body, The distance from the edge of the built-up portion to the edge of the machined surface on which the built-up portion is formed is 0 mm or more and 4 mm or less.

[0007] A method for manufacturing a valve seat according to one aspect of this disclosure is: A method for manufacturing a valve seat by forming a built-up portion on the inside of a groove in the cylinder head body using laser cladding, A spraying step in which metal powder is sprayed onto the inside of a groove where the distance from the edge of the built-up portion to the edge of the machined surface on which the built-up portion is formed is 0 mm or more and 4 mm or less, The system includes a melting step in which a laser is irradiated onto the sprayed metal powder to melt the metal powder, The spraying step and the melting step are performed by starting from a part of the groove and continuously moving in a predetermined direction, thereby performing the laser cladding process on the entire groove. In the step of spraying the metal powder, a portion of the metal powder is discharged into the through-holes formed inside the groove, thereby preventing the metal powder from adhering to areas on the side of the movement direction from the area where the laser cladding process is being performed. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a vehicle component capable of suppressing welding defects during laser cladding and a method for manufacturing a valve seat using the vehicle component. [Brief explanation of the drawing]

[0009] [Figure 1](a) A schematic perspective cross-sectional view of a vehicle member according to an embodiment of the present disclosure before the formation of a built-up portion. (b) A schematic perspective cross-sectional view of a vehicle member according to an embodiment of the present disclosure after the formation of a built-up portion. (c) A schematic perspective cross-sectional view of a vehicle member according to an embodiment of the present disclosure before the formation of a built-up portion. (d) A cross-sectional view of a vehicle member according to an embodiment of the present disclosure. [Figure 2] This is a flowchart of a method for manufacturing a valve seat according to an embodiment of the present disclosure. [Figure 3] (a) A schematic perspective cross-sectional view of a vehicle member during laser cladding according to an embodiment of the present disclosure. (b) An enlarged view of the laser cladding location in a vehicle member according to an embodiment of the present disclosure. (c) A cross-sectional view of a vehicle member having unwelded areas. (d) An enlarged view of the laser cladding location in a vehicle member according to an embodiment of the present disclosure. [Figure 4] This graph shows the relationship between the horizontal distance d from the edge of the built-up portion to the tip of the protrusion and the welding rate in a vehicle member according to the embodiment of this disclosure. [Figure 5] (a) A cross-sectional image of a vehicle member according to an embodiment of the present disclosure. (b) A binarized image of the cross-sectional image of a vehicle member according to an embodiment of the present disclosure. [Figure 6] (a) A cross-sectional view of the vehicle member according to the embodiment of the present disclosure when the shape of the protrusion is changed. (b) A cross-sectional view of the vehicle member according to the embodiment of the present disclosure when the shape of the protrusion is changed. [Modes for carrying out the invention]

[0010] The following describes specific embodiments of this disclosure in detail with reference to the drawings. However, this disclosure is not limited to the following embodiments. Also, for clarity, the following descriptions and drawings have been simplified as appropriate.

[0011] <Vehicle component configuration> Figure 1(a) is a schematic perspective cross-sectional view of a vehicle member according to the present disclosure before the formation of the built-up portion. Figure 1(b) is a schematic perspective cross-sectional view after the formation of the built-up portion. The right-handed xyz Cartesian coordinate system shown in Figures 1(a) and (b) is for convenience in showing the positional relationships of the components. The positive z-axis is vertically upward, and the xy-plane is the horizontal plane. This is common to all drawings from Figures 1 to 6, including Figures 1(c) and (d), Figure 3 and Figure 6, which will be described later.

[0012] The vehicle component 1 comprises a main body portion 11, a groove portion 12, a protrusion portion 13, and a build-up portion 14. Vehicle component 1 is a cylinder head used as an engine component for a vehicle, for example, having two, four, or other number of grooves 12 in a single main body 11. When vehicle component 1 is a cylinder head, the grooves 12, protrusions 13, and the built-up portion 14 formed by solidified metal powder in the grooves 12 are the valve seat portion of the cylinder head. In addition, the valve seat portion is formed by laser cladding, in which the metal powder is melted by irradiating it with a laser and welded to the vehicle component 1. However, vehicle component 1 only needs to be a component that requires the process of forming the built-up portion 14 by laser cladding.

[0013] The main body 11 is the body of the vehicle component 1, and its external shape and size are determined according to the intended use of the vehicle component 1. The material of the main body 11 is, for example, iron or ferrous metals such as carbon steel, or alloy steel such as stainless steel.

[0014] The groove 12 is formed on the surface of the main body 11. Although omitted in Figure 1(a), the groove 12 may have a bottom surface on the negative z-axis side, in which case the groove 12 becomes a recess. Alternatively, the groove 12 may not have a bottom surface on the negative z-axis side, in which case the groove 12 becomes a through hole formed to penetrate from the first surface of the main body 11 to the second surface of the main body 11. However, if the vehicle member 1 is a cylinder head, for example, the groove 12 is preferably a through hole because a mixture of fuel and air passes through it.

[0015] The convex portion 13 is formed on the inner surface of the groove portion 12. More specifically, the convex portion 13 is formed by protruding in a direction narrowing the inner diameter of the groove portion 12 over the entire circumferential direction on the inner surface of the groove portion 12. Here, the side surfaces of the convex portion 13, that is, the surfaces on the positive z-axis side and the negative z-axis side of the convex portion 13 in FIG. 1(a), are machined surfaces. The material of the convex portion 13 is, for example, an iron-based metal such as iron or carbon steel, or an alloy steel such as stainless steel.

[0016] In FIG. 1(a), due to the convex portion 13 protruding with a predetermined thickness in the z-axis direction, corner portions, which are boundary portions between the inner surface of the groove portion 12 and the side surfaces of the convex portion 13, are formed on the positive z-axis side and the negative z-axis side as viewed from the convex portion 13. However, for example, as shown in FIG. 1(c), the convex portion 13 may be formed so as not to form a corner portion on the negative z-axis side as viewed from the convex portion 13 and to narrow the inner diameter of the groove portion 12 at a predetermined location. That is, a concave portion or a through hole having a shape with a narrowed inner diameter at a predetermined position may be formed by the integrated groove portion 12 and convex portion 13. The shape is formed, for example, by forming a concave portion or a through hole having a predetermined inner diameter in the main body portion 11 as the groove portion 12 and expanding the inlet portion of the formed groove portion 12 to a diameter larger than the inner diameter of the groove portion 12. The shape of the corner portion may be an R shape as shown in FIG. 1(a) or a shape bent substantially vertically.

[0017] The build-up portion 14 is formed as a solidified body of molten metal powder at the boundary portion between the inner surface of the groove portion 12 and the side surface of the convex portion 13 as shown in FIG. 1(b). That is, the build-up portion 14 is formed on the machined surface. Here, for example, when the vehicle member 1 is a cylinder head, the build-up portion 14 is formed at the boundary portion on the positive z-axis side among the boundary portions between the inner surface of the groove portion 12 and the side surface of the convex portion 13, and functions as a valve seat portion of the cylinder head. The material of the build-up portion 14 may be any material that is melted by the laser irradiated in laser cladding processing, and is, for example, an alloy containing metals such as aluminum, iron, nickel, cobalt, chromium, molybdenum, and tungsten. Also, a material in which a metal such as cobalt or molybdenum is combined with an inorganic substance such as a carbide or an oxide may be used.

[0018] Figure 1(d) is a cross-sectional view of a vehicle member according to the embodiment of this disclosure, when cut by a plane parallel to the yz plane. The build-up portion 14 is formed at the boundary between the inner surface of the groove portion 12 and the side surface of the protrusion portion 13, as shown in Figure 1(d). Here, the horizontal distance from the inner surface of the groove portion 12 to the tip of the protrusion portion 13 (i.e., the edge of the processed surface) is defined as D (mm), and the horizontal distance from the edge of the build-up portion 14 to the tip of the protrusion portion 13 (i.e., the edge of the processed surface) is defined as d (mm).

[0019] <Manufacturing method for vehicle components> Next, a method for manufacturing a valve seat according to an embodiment of this disclosure will be described with reference to Figure 2. Figure 2 is a flowchart of the method for manufacturing a valve seat according to an embodiment of this disclosure.

[0020] First, metal powder is sprayed onto the boundary between the inner surface of the groove 12 and the side surface of the protrusion 13 of the vehicle member 1 (step S1). Step S1 is performed, for example, by discharging metal powder and shielding gas from a nozzle. By discharging shielding gas together with the metal powder in step S1, the metal powder is supplied to the laser cladding position along with the flow of shielding gas. As the shielding gas, for example, air is used, but an inert gas such as nitrogen gas or argon gas may also be used.

[0021] Next, a laser is irradiated onto the sprayed metal powder to melt it (step S2). In step S2, the molten metal powder solidifies, forming the build-up portion 14. Here, for example, if the vehicle component 1 is a cylinder head, by performing steps S1 and S2, the build-up portion 14 is formed inside the groove portion 12 by laser cladding, and the valve seat portion is manufactured. The type of laser used for irradiation can be, for example, a CO2 laser or a semiconductor laser. Alternatively, the metal powder may be dissolved by irradiating it with an electron beam instead of a laser.

[0022] Steps S1 and S2 may be performed simultaneously. In the laser cladding process used in the embodiments of this disclosure, for example, as shown in Figure 3(a), a build-up portion 14 is formed by simultaneously spraying metal powder M and irradiating with a laser L on the boundary portion between the inner surface of the groove portion 12 and the side surface of the protrusion portion 13. At this time, the laser cladding process is performed by starting the process from a part of the boundary portion between the inner surface of the groove portion 12 and the side surface of the protrusion portion 13, and continuously moving the metal powder M spraying position and the laser L irradiation position in a predetermined direction of movement. Here, by performing laser cladding from a part of the boundary portion between the inner surface of the groove portion 12 and the side surface of the protrusion portion 13 over the entire circumference, the entire boundary portion is laser cladded.

[0023] Note that the movement of the laser cladding position A in laser cladding is relative. Therefore, the laser cladding position A may be moved by moving, tilting, or rotating the laser L, or by moving, tilting, or rotating the vehicle component 1. Alternatively, the laser cladding position A may be moved by moving, tilting, or rotating both the laser L and the vehicle component 1. To move, tilt, or rotate the laser L, the laser irradiation device (not shown) that irradiates the laser L may be moved, tilted, or rotated, or the direction of the laser L's movement may be controlled using a reflector or prism.

[0024] Figure 3(b) is an enlarged view of the laser cladding position in Figure 3(a). When laser cladding is performed, some of the metal powder M ejected from the nozzle scatters and adheres to the surface of the vehicle component 1. Here, for example, if the laser cladding position A is moving to the right in Figure 3(b), metal powder M adheres to the area on the side of the laser cladding position A in the direction of movement, i.e., the area to the right of the laser cladding position A. If laser cladding is continued in this state, the amount of metal powder M at the laser cladding position A will be excessive due to the adhered metal powder M. As a result, the irradiation intensity of the laser L will be insufficient, and as shown in Figure 3(c), an unwelded area B will be created on the side of the protrusion 13, which could lead to welding failure.

[0025] To solve this problem, in vehicle member 1, the horizontal distance d from the edge of the build-up portion 14 to the tip of the protrusion 13 is shortened, as shown in Figure 3(d). In other words, in vehicle member 1, the protrusion height of the protrusion 13 is reduced, thereby expanding the diameter of the groove 12 in the direction of the white arrow. As the diameter of the groove 12 is expanded, the flow rate of the shielding gas discharged from the nozzle that flows to the inside of the groove 12, i.e., to the negative z-axis direction, increases. Due to the increased gas flow, some of the metal powder M adhering to the area to the right of the laser cladding position A is discharged to the inside of the groove 12. Therefore, the adhesion of metal powder M to the area to the right of the laser cladding position A is prevented.

[0026] While it is possible to increase the gas flow rate into the groove 12 by increasing the gas flow rate of the shielding gas discharged from the nozzle, in this case, the amount of scattered metal powder M also increases with the increase in gas flow rate. As a result, the amount of metal powder M supplied to the laser cladding position A is unstable, and the welding quality deteriorates. The vehicle member 1 according to the embodiment of this disclosure can increase the gas flow rate into the groove 12 without changing the total amount of gas flow, thus providing the effect of suppressing welding defects during laser cladding.

[0027] Figure 4 is a graph showing the relationship between the horizontal distance d from the edge of the build-up portion to the tip of the protrusion and the welding rate. This graph is drawn by superimposing a scale showing the value of d corresponding to the value of D onto a graph where the horizontal axis is the horizontal distance D from the inner surface of the groove portion 12 to the tip of the protrusion 13 and the vertical axis is the welding rate. However, the welding rate is calculated by cutting the vehicle member 1 at a horizontal plane P with a height of 1.5 mm in the positive z-direction from the side of the protrusion 13 and observing the cross-sectional image of the build-up portion 14 shown in Figure 5(a). Here, the cross-sectional observation of the build-up portion 14 is performed by observing the defects G displayed in black within the build-up portion 14 in the binarized image of the cross-sectional image of the build-up portion 14 shown in Figure 5(b). The welding rate (%) is calculated using the following formula (1) for the binarized cross-sectional image of the build-up portion 14.

number

[0028] As shown by the white arrows in Figure 4, the horizontal distance d from the edge of the build-up portion 14 to the tip of the protrusion 13 is preferably 0 mm or more and 4 mm or less. By performing laser cladding so that the value of d is 0 mm or more and 4 mm or less, the flow rate of gas flowing into the groove portion 12 during laser cladding increases. As a result, as shown in Figure 3(d), the metal powder M that has adhered in the area on the moving side of the area where laser cladding is being performed is discharged beyond the edge of the processed surface. This effect makes it possible to achieve a high welding rate of 94% or more.

[0029] As shown in Figure 6(a), a portion of the side surface of the protrusion 13 may have a shape that is inclined toward the negative z-axis direction. Also, as shown in Figure 6(b), the slope may have a curved shape. Including a portion of the side surface of the protrusion 13 toward the negative z-axis direction also has the effect of increasing the flow rate of the shielding gas discharged from the nozzle in step S1 that flows toward the negative z-axis direction. At this time, it is preferable that the horizontal distance d1 from the edge of the build-up portion 14 to the end of the surface of the side surface of the protrusion 13 that is substantially parallel to the xy plane is 0 mm or more and 4 mm or less. By performing laser cladding so that the value of d1 is 0 mm or more and 4 mm or less, the effect is obtained to discharge the metal powder M attached in the area on the moving side of the area where laser cladding is being performed into the inside of the groove portion 12.

[0030] As described above, the vehicle member according to the embodiment of this disclosure has a reduced protrusion height of the convex portion formed in the groove and an enlarged diameter of the groove. Therefore, it is possible to discharge metal powder adhering to the area on the side of the movement direction from the processing position during laser cladding into the inside of the groove beyond the edge of the processed surface. This makes it possible to provide a vehicle member that can suppress welding defects during laser cladding and a method for manufacturing a valve seat using the vehicle member. [Explanation of Symbols]

[0031] 1. Vehicle components 11 Main body 12 grooves 13 Convex part 14 Meat pile section A Laser cladding position B Unwelded area G Defect L Laser M Metal powder P horizontal plane

Claims

1. A vehicle component that has undergone laser cladding, in which metal powder is sprayed onto a metal vehicle component, and the metal powder is melted by irradiating it with a laser and welded to the vehicle component, The main body is made of metal, The system comprises a built-up portion formed by welding the solidified molten metal powder onto the processed surface of the main body, The distance from the edge of the built-up portion to the edge of the machined surface on which the built-up portion is formed is 0 mm or more and 4 mm or less. Vehicle components.

2. The vehicle member is a cylinder head having a valve seat portion comprising a through hole formed to penetrate from the first surface of the main body portion to the second surface of the main body portion, and a protrusion on the inner surface of the through hole that protrudes in a direction that narrows the inner diameter of the through hole over the entire circumferential direction, The aforementioned build-up portion is formed at the boundary between the inner surface and the protruding surface, The edge of the processed surface is the tip of the protrusion, The vehicle component according to claim 1.

3. The laser cladding process is performed by starting from a portion of the processing surface and moving continuously in a predetermined direction. The vehicle component according to claim 1 or 2.

4. In the laser cladding process described above, when the metal powder is blown onto the processing surface, a portion of the metal powder is discharged beyond the edge of the processing surface in the direction of movement. The vehicle component according to claim 3.

5. A method for manufacturing a valve seat by forming a built-up portion on the inside of a groove in the cylinder head body using laser cladding, A spraying step in which metal powder is sprayed onto the inside of a groove where the distance from the edge of the built-up portion to the edge of the machined surface on which the built-up portion is formed is 0 mm or more and 4 mm or less, The system includes a melting step in which a laser is irradiated onto the sprayed metal powder to melt the metal powder, The spraying step and the melting step are performed by starting from a part of the groove and continuously moving in a predetermined direction, thereby performing the laser cladding process on the entire groove. In the step of spraying the metal powder, a portion of the metal powder is discharged into the through-holes formed inside the groove, thereby preventing the metal powder from adhering to the area on the side of the movement direction from the area where the laser cladding process is being performed. A method for manufacturing valve seats.

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