Laser cladding apparatus

Abstract

To suppress the occurrence of non-weld in laser cladding.SOLUTION: A laser cladding apparatus 100 for applying laser cladding to a valve seat part 10 of a cylinder head H comprises: a cylinder head holding part 1 for holding a cylinder head H; a laser processing head 2 for irradiating a processing site W with a laser beam L, and for discharging a powder material on the processing site W; a rotary part 3 rotating about the central axis of the valve seat part 10; and a powder material supply part 4 for supplying the laser processing head 2 with a powder material P. The powder material supply part has a first supply pipe and a second supply pipe for supplying the powder material P. The first supply pipe is placed in front of the second supply pipe in a moving direction of the laser processing head, and a supply amount of the powder material supplied from the second supply pipe is smaller than a supply amount of the powder material supplied from the first supply pipe.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a laser cladding processing apparatus.

Background Art

[0002] For example, a laser cladding processing apparatus for performing laser cladding processing on a valve seat portion of a cylinder head is known (see, for example, Japanese Patent Application Laid-Open No. 2005-21908). The laser cladding processing apparatus includes a cylinder head holding portion that tilts and holds the cylinder head so that the central axis of the valve seat is in the vertical direction, a laser processing head that irradiates a laser beam onto a processing portion of the valve seat and discharges a powder material onto the processing portion, a rotating portion that rotates around the central axis of the valve seat, and a powder material supply portion that supplies the powder material to the laser processing head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the prior art, there is a possibility that an unwelded portion may occur at the bottom of the groove in the valve seat portion. The present invention provides a laser cladding processing apparatus capable of suppressing the occurrence of unwelding at the bottom of the groove in the valve seat portion.

Means for Solving the Problems

[0005] A laser cladding processing apparatus according to an aspect of the present invention is a laser cladding processing apparatus that performs laser cladding processing on a valve seat portion of a cylinder head, and includes a cylinder head holding portion that holds the cylinder head such that the central axis of the valve seat portion is in the vertical direction, a laser processing head that irradiates a laser beam onto a processing portion of the valve seat portion and discharges a powder material onto the processing portion, a rotating portion that rotates the laser processing head around the central axis of the valve seat portion in a state inclined with respect to the vertical direction, and a powder material supply portion that supplies the powder material to the laser processing head. The powder material supply portion is connected to the laser processing head at positions different from each other and has a first supply pipe and a second supply pipe that supply the powder material. The first supply pipe is disposed in front of the second supply pipe in the moving direction of the laser processing head, and the supply amount of the powder material supplied from the second supply pipe is smaller than the supply amount of the powder material supplied from the first supply pipe.

Effects of the Invention

[0006] According to an aspect of the present invention, generation of non-welding can be suppressed at the bottom of the groove of the valve seat portion.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0008] As shown in FIG. 1, the laser cladding processing apparatus 100 includes a cylinder head holding unit 1, a laser processing head 2, a rotating unit 3, and a powder material supply unit 4. As shown in FIG. 2, the laser cladding processing apparatus 100 is an apparatus that performs laser cladding processing on the valve seat portion 10 of the cylinder head H. The cylinder head holding unit 1 holds the cylinder head H in an inclined manner. The laser processing head 2 irradiates the processing site W with a laser beam L and discharges the powder material P. The rotating unit 3 holds the laser processing head 2 inclined with respect to the vertical direction and rotates the laser processing head 2 around an axis along the vertical direction. The powder material supply unit 4 supplies the powder material P to the laser processing head 2.

[0009] The cylinder head holding unit 1 has an inclined portion that inclines the cylinder head H so that the central axis of the valve seat portion 10 is in the vertical direction, and an XY stage that can move the cylinder head H along the X-axis direction and the Y-axis direction along the horizontal plane. The inclined portion has, for example, an air cylinder and can change the posture of the cylinder head H. The inclined portion can change the inclination of the cylinder head H. The valve seat portion 10 includes an intake valve seat and an exhaust valve seat. The inclined portion can change the inclination of the cylinder head H so that the central axis of the valve seat portion 10 is in the vertical direction. The inclined portion can change the inclination of the cylinder head H so that the central axis of the exhaust valve seat is in the vertical direction. The XY stage can appropriately change the position of the cylinder head H.

[0010] The laser processing head 2 includes a laser generation unit 21, a coaxial nozzle 22, and an optical system. The laser generation unit generates a laser beam L. The coaxial nozzle 22 allows the laser beam L to pass through and discharges the powder material P. The optical system condenses the laser beam L. The laser generation unit and the coaxial nozzle 22 are integrally connected via the optical system. A supply pipe 43 for supplying the powder material P to the coaxial nozzle 22 is connected to the coaxial nozzle 22. As will be described later, the supply pipe 43 is branched into a plurality of flow paths. A plurality of supply pipes 43 may be connected to the coaxial nozzle 22.

[0011] The laser generation unit 21 includes a semiconductor laser oscillator. The optical system 34 includes a collimation lens and a condenser lens for shaping the laser beam L. The semiconductor laser oscillator may include, for example, a gallium arsenide-based semiconductor laser element.

[0012] The coaxial nozzle 22 has an irradiation port for irradiating the laser beam L and a plurality of discharge ports for discharging the powder material P. The coaxial nozzle 22 may be formed in a conical shape. The plurality of discharge ports discharge the powder material P together with the carrier gas. The irradiation port is formed, for example, at the center when viewed in the axial direction of the coaxial nozzle 22. The plurality of discharge ports are arranged around the irradiation port. The plurality of discharge ports include a discharge port arranged forward and a discharge port arranged rearward in the moving direction of the laser processing head 2. The moving direction of the laser processing head 2 is the processing direction in laser cladding processing.

[0013] The rotating unit 3 has a motor as a drive source, a power transmission mechanism for transmitting the rotational driving force by the motor, a rotating shaft that rotates around a predetermined axis when the rotational driving force is transmitted, and a support unit that is connected to the rotating shaft and supports the laser processing head 2. The rotating shaft is arranged, for example, along the vertical direction. The rotating unit 3 can hold the laser processing head 2 and rotate the laser processing head 2 around the rotating shaft.

[0014] Further, the laser processing head 2 is movable in the vertical direction along the irradiation axis of the laser beam L. In the laser cladding processing apparatus 100, the relative distance between the cylinder head H and the laser processing head 2 may be adjusted.

[0015] FIG. 3 is a schematic view showing the powder material supply unit 4. The powder material supply unit 4 supplies the powder material P to the laser processing head 2 by the pressure of the carrier gas. The powder material supply unit 4 has a hopper 41, a feeder 42, a supply pipe 43, and connectors 44A to 44C.

[0016] The hopper 41 stores the powder material P and supplies the powder material P to the feeder 42. The feeder 42 supplies the powder material P in a fixed quantity. The supply pipe 43 connects the feeder 42 and the coaxial nozzle 22. The supply pipe 43 includes a plurality of supply pipes 43A to 43G. The supply pipes 43A to 43G may be, for example, flexible hoses. The supply pipe 43A connects the feeder 42 and the connector 44A. The supply pipe 43A branches into the supply pipes 43B and 43C via the connector 44A. The supply pipe 43B branches into the supply pipes 43D and 43E via the connector 44B. The supply pipe 43C branches into the supply pipes 43F and 43G via the connector 44C. The supply pipes 43D to 43G are each connected to the coaxial nozzle 22. The supply pipes 43D to 43G are an example of the first supply pipe and the second supply pipe. In the moving direction of the laser processing head 2, the supply pipes 43D to 43G arranged in the front are the first supply pipes, and the supply pipes 43D to 43G arranged in the rear are the second supply pipes. The first supply pipe and the second supply pipe are interchanged according to the moving direction of the laser processing head 2.

[0017] A cylinder filled with carrier gas is connected to the feeder 42. Carrier gas is supplied to the feeder 42, and the powder material P is supplied to the supply pipe 43A together with the carrier gas. The powder material P and the carrier gas flowing through the supply pipe 43A are branched by the connector 44A and flow into the supply pipe 43B and the supply pipe 43C. The powder material P and the carrier gas flowing through the supply pipe 43B are branched by the connector 44B and flow into the supply pipe 43D and the supply pipe 43E. The powder material P and the carrier gas flowing through the supply pipe 43C are branched by the connector 44C and flow into the supply pipe 43F and the supply pipe 43G. The powder material P and the carrier gas introduced into the coaxial nozzle 22 from the supply pipes 43D to 43G are discharged from separate discharge ports.

[0018] Valves are provided on the downstream sides of connectors 44A to 44C. By adjusting the valve opening, the flow rate of the powder material P can be changed. Connector 44A can provide a difference between the flow rate of the powder material P flowing through supply pipe 43B and the flow rate of the powder material P flowing through supply pipe 43C. Connector 44B can provide a difference between the flow rate of the powder material P flowing through supply pipe 43D and the flow rate of the powder material P flowing through supply pipe 43E. Connector 44C can provide a difference between the flow rate of the powder material P flowing through supply pipe 43F and the flow rate of the powder material P flowing through supply pipe 43G.

[0019] The laser cladding processing apparatus 100 includes a control unit 50 that controls the entire laser cladding processing apparatus 100. The control unit 50 can control the operations of the laser processing head 2, the rotating unit 3, and the powder material supply unit 4. The control unit 50 has a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The control unit 50 realizes various functions by, for example, executing a program stored in the storage unit with the CPU. The storage unit includes the ROM and the RAM.

[0020] The control unit 50 can control the flow rate of the powder material P flowing through the supply pipes 43D to 43G. The control unit 50 can control the flow rate of the powder material P such that the supply amount of the powder material P supplied from the supply pipes 43F and 43G to the coaxial nozzle 22 is less than the supply amount of the powder material P supplied from the supply pipes 43D and 43E to the coaxial nozzle 22. The control unit 50 can control the flow rate of the powder material P such that the supply amount of the powder material P supplied from the rear to the processing site W is less than the supply amount of the powder material P supplied from the front to the processing site W in the moving direction of the laser processing head 2. The control unit 50 can adjust the flow rate of the powder material P by controlling the valve opening degrees of the connectors 44A to 44C. The control unit 50 can change the flow rate of the powder material P flowing through the supply pipes 43D to 43G according to the moving direction of the laser processing head 2. The control unit 50 can change the balance between the supply amount of the powder material P discharged in front of the processing site W and the supply amount of the powder material P discharged behind the processing site W.

[0021] Next, problems in the prior art will be described. In the prior art, there is a possibility that unwelded portions are formed at the bottom 14 of the valve seat groove. Unwelded portions are portions where the welding between the clad layer 12 and the base material 15 is insufficient. The base material 15 is the base material of the valve seat portion 10 and may be, for example, aluminum.

[0022] In the prior art, powder accumulations occur in front of the molten pool. The molten pool moves in the moving direction of the laser processing head 2 as the irradiation position of the laser beam L moves. The molten pool passes over the powder accumulation in front, and at this time, the powder accumulation is melted. Since the heat of the molten pool is taken away by the powder accumulation, the base material cannot be melted and the welding becomes insufficient. The powder accumulation is generated because the powder material supplied from the rear of the molten pool does not enter the molten pool, and the powder material P bounced by the bead jumps forward due to the gas.

[0023] Next, the operation and effect of the laser cladding processing apparatus 100 will be described. The laser cladding processing apparatus 100 according to the present embodiment is a laser cladding processing apparatus that performs laser cladding processing on the valve seat portion 10 of the cylinder head H, and includes a cylinder head holding portion 1 that holds the cylinder head H such that the central axis of the valve seat portion 10 is in the vertical direction, a laser processing head 2 that irradiates a laser beam L onto the processing site W of the valve seat portion 10 and discharges a powder material P onto the processing site W, a rotating portion 3 that rotates the laser processing head 2 around the central axis of the valve seat portion 10 in a state inclined with respect to the vertical direction, and a powder material supply portion 4 that supplies the powder material P to the laser processing head 2. The powder material supply portion 4 is connected to the laser processing head 2 at mutually different positions and has supply pipes (first supply pipe and second supply pipe) 43D to 43G that supply the powder material P. The supply pipes 43D and 43E are arranged in front of the supply pipes 43F and 43G in the moving direction of the laser processing head 2. The supply amount of the powder material P supplied from the supply pipes 43F and 43G is less than the supply amount of the powder material P supplied from the supply pipes 43D and 43E.

[0024] In the laser cladding processing apparatus 100, a laser beam L is irradiated onto a processing site W while a powder material P is discharged, and laser cladding processing can be performed on the valve seat portion 10 of the cylinder head H. In the laser cladding processing apparatus 100, a difference can be provided in the supply amount of the powder material P before and after in the moving direction of the laser processing head 2 with respect to the processing site W. According to the laser cladding processing apparatus 100, in the laser cladding processing apparatus 100, the supply amount of the powder material P discharged behind the molten pool can be made less than the supply amount of the powder material P discharged in front of the molten pool. In other words, the supply amount of the powder material P discharged in front of the molten pool can be made more than the supply amount of the powder material P discharged behind the molten pool. Thereby, in the laser cladding processing apparatus 100, the powder material P that jumps from behind the molten pool to the front can be reduced, and the formation of a powder pile in front of the molten pool can be suppressed. Therefore, by suppressing the heat transfer from the molten pool to the powder pile, the amount of heat transfer from the molten pool to the base material 15 can be ensured. As a result, a sufficient amount of heat can be supplied to the base material 15, and non-welding at the bottom 14 of the valve seat groove can be suppressed.

[0025] Next, a modified example of the powder material supply unit 4 will be described. The control of the flow rate of the powder material P in the powder material supply unit 4 is not limited to using a valve. For example, by moving the connection portion between the connector 44A and the supply pipes 43B and 43C in the vertical direction, the supply amount of the powder material P may be changed. By lowering the connection portion with the supply pipe 43B and raising the connection portion with the supply pipe 43C, the flow rate of the powder material P flowing through the supply pipes 43B, 43D, and 43E can be increased, and the flow rate of the powder material P flowing through the supply pipes 43C, 43F, and 43G can be decreased. By changing the height positions of the connection portions, a difference can be provided in the flow rate.

[0026] In the powder material supply unit 4, the powder material P is supplied from one feeder 42 to the supply pipes 43B, 43D, 43E and the supply pipes 43C, 43F, 43G. However, the laser cladding processing apparatus 100 may be provided with a plurality of feeders 42. The powder material supply unit 4 may include a feeder 42 that supplies the powder material P to be supplied in front of the processing site W and a feeder 42 that supplies the powder material P to be supplied behind the processing site W, respectively. The powder material supply unit 4 may be configured to include a plurality of supply pipes 43 without branching the supply pipes.

[0027] As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to these embodiments, and various modifications or changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0028] 100... laser cladding processing apparatus, 1... cylinder head holding part, 2... laser processing head, 3... rotating part, 4... powder material supply unit, 10... valve seat part, 43D to 43G... supply pipes (first supply pipe and second supply pipe), H... cylinder head, P... powder material, W... processing site.

Claims

[Claim 1] A laser clad processing apparatus for performing laser clad processing on a valve seat portion of a cylinder head, a cylinder head holding portion that holds the cylinder head so that a central axis of the valve seat portion is aligned vertically; a laser processing head that irradiates a laser beam onto a processing portion of the valve seat portion and ejects a powder material onto the processing portion; a rotating unit that rotates the laser processing head around a central axis of the valve seat portion while tilting the laser processing head with respect to the vertical direction; A powder material supply unit that supplies a powder material to the laser processing head, The powder material supply unit includes a first supply pipe and a second supply pipe that are connected to the laser processing head at different positions from each other and supply the powder material, The first supply pipe is disposed forward of the second supply pipe in a moving direction of the laser processing head, A laser clad processing apparatus, characterized in that the amount of powder material supplied from the second supply pipe is smaller than the amount of powder material supplied from the first supply pipe.

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