JP5412887B2 - Laser cladding valve sheet forming method and laser cladding valve sheet forming apparatus - Google Patents

Description

  The present invention relates to a laser cladding valve sheet forming method and a laser cladding valve sheet forming apparatus.

  For example, in an automobile engine, instead of a conventional method of driving a seat ring as a valve seat, a method of directly depositing a valve seat alloy on a cylinder head (laser cladding processing) has begun to be adopted. As described above, if the valve seat alloy is directly built on the cylinder head, the thermal conductivity can be greatly improved as compared with the seat ring driving method, and the cooling performance can be improved.

  Laser cladding is performed by supplying metal powder (building material) to the valve seat forming part of the cylinder head, or by placing ring-shaped metal powder that has been pressed and shaped in advance into the valve seat forming part. This is a technique in which a metal beam is irradiated with a laser beam to be melted and solidified to build up (for example, see Patent Document 1). Among them, a method of forming a ring-shaped valve seat by performing laser cladding on a valve seat portion of a cylinder head for an internal combustion engine is called laser cladding valve seat processing.

  In order to build up by irradiating with a laser beam while supplying metal powder, it is necessary to rotate the cylinder head and the laser beam relatively in the circumferential direction, so that the processing start portion and the processing end portion overlap each other. It is necessary to stabilize the quality of the overlap part.

  On the other hand, when overlaying is performed by irradiating a laser beam onto metal powder that has been preliminarily pressed into a valve seat shape, the beam width of the ring-shaped laser beam is equal to the valve seat width without laser scanning. In such a case, the energy density becomes small, and the build-up processing becomes difficult.

  Therefore, it is conceivable to increase the output of the laser oscillator as a method of making the ring beam width equal to the build-up width while making the laser energy density a value that can be built-up. However, since there is an upper limit to the output value of a laser oscillator currently on the market, the ring beam width cannot reach the buildup width.

  As another means for increasing the ring beam width to the build-up width, there is a method in which an arc shape obtained by dividing the ring shape is formed by a plurality of laser oscillators, and these are combined into a ring shape (see, for example, Patent Document 2) ).

JP 2005-21908 A Japanese Patent Laid-Open No. 2002-066779 JP 2003-251480 A

  However, in the method of forming a circular arc shape obtained by dividing the ring shape with a plurality of laser oscillators, a plurality of laser oscillators are required, resulting in an increase in equipment costs.

  Therefore, the present invention realizes the build-up with a ring-shaped beam having an energy density that can be built up without scanning with a laser beam, and can improve the quality of the built-up processing portion and suppress the equipment cost. A laser cladding valve sheet forming method and a laser cladding valve sheet forming apparatus are provided.

  In the method for forming a laser clad valve seat according to the present invention, the laser beam is formed into a ring-shaped beam having a diameter approximate to the diameter of the valve seat and smaller than the ring width of the valve seat, and the ring-shaped beam is formed in the entire ring-shaped metal material. Eccentric irradiation is performed.

  The laser clad valve seat forming apparatus according to the present invention has a beam shape in which a circular laser beam irradiated from a laser oscillator is a ring-shaped beam having a diameter approximate to the diameter of the valve seat and smaller than the ring width of the valve seat. A change mirror, and a beam irradiation mirror having an eccentric rotation mechanism for irradiating the entire region of the ring-shaped metal material with an eccentricity.

  According to the method for forming a laser clad valve seat of the present invention, it is not necessary to make the ring-shaped beam width equal to the valve seat width. Can be fully processed. Further, since there is no need to scan the laser beam on the circumference, there is no fear of vacancies and cracks in the overlap portion where the processing start portion and the processing end portion overlap. Therefore, according to the method of the present invention, it is possible to form a high-quality laser clad bulb sheet of the build-up processed portion.

  According to the laser clad valve seat forming apparatus of the present invention, a laser beam which is formed into a ring-shaped beam having a diameter approximate to the diameter of the valve seat and smaller than the ring width of the valve seat by the beam shape changing mirror Since the beam irradiation mirror having the eccentricity irradiates the entire area of the ring-shaped metal material, the cylinder head rotating mechanism for scanning the laser beam on the circumference can be eliminated, and the apparatus configuration is greatly simplified and reduced. Cost can be increased.

FIG. 1 is a perspective view showing a laser cladding valve sheet forming apparatus. FIG. 2 is a schematic configuration diagram of an optical system mechanism portion of the laser cladding valve sheet forming apparatus shown in FIG. FIG. 3 is an enlarged perspective view of a main part showing a state before the metal powder ring body is arranged in the ring-shaped concave groove formed in the valve seat forming portion of the cylinder head shown in FIG. FIG. 4 is a diagram showing the relative dimensional relationship of the beam diameter and beam width with respect to the metal powder ring body when the laser beam irradiated to the metal powder ring body is a ring-shaped beam. FIG. 5 is a view when the laser beam is irradiated with eccentric rotation over the entire metal powder ring body. FIG. 6 is a perspective view of a beam irradiation mirror rotated by an eccentric rotation mechanism. It is a figure at the time of changing the irradiation direction of a beam irradiation mirror, and carrying out laser clad processing of the metal powder ring body arranged in the adjacent valve seat formation part which carried out laser clad processing previously.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

“Description of Laser Cladding Valve Seat Forming System”
First, the configuration of the laser cladding valve sheet forming apparatus will be described. 1 is a perspective view showing a laser cladding valve sheet forming apparatus, FIG. 2 is a schematic configuration diagram of an optical system mechanism part of the laser cladding valve sheet forming apparatus shown in FIG. 1, and FIG. 3 is a valve seat of the cylinder head shown in FIG. FIG. 4 is a main part enlarged perspective view showing a state before the metal powder ring body is arranged in the ring-shaped concave groove formed in the formation site, and FIG. 4 shows a beam when the laser beam irradiated to the metal powder ring body is a ring-shaped beam. FIG. 5 is a diagram showing the relative dimensional relationship of the diameter and beam width with respect to the metal powder ring body, FIG. 5 is a diagram when the laser beam is irradiated with eccentric rotation over the entire area of the metal powder ring body, and FIG. It is a perspective view of the beam irradiation mirror rotated.

  As shown in FIG. 1, the laser clad valve seat forming apparatus includes a laser irradiation device 3 that irradiates a valve sheet forming portion 2 of a cylinder head 1 of an internal combustion engine for an automobile, for example, with a laser beam hv.

  The laser irradiation device 3 includes a laser oscillator 4, a laser oscillator control unit 5 that controls the intensity of the laser output from the laser oscillator 4, an NC control device 6, and a valve seat forming part by condensing the laser. 2, and an optical system mechanism unit 7 that irradiates 2.

  The laser beam hv output from the laser oscillator 4 is controlled by the laser oscillator control unit 5 and supplied to the optical system mechanism unit 7. The optical system mechanism unit 7 converts the laser beam hv into a ring-shaped beam and irradiates the valve seat formation part 2. Is done. In this laser clad valve seat forming apparatus, a laser oscillator 4, a laser oscillator control unit 5, and an NC control apparatus 6 are controlled by a computer 8, respectively.

  As shown in FIG. 2, the optical system mechanism unit 7 includes a beam shape changing mirror 9 that uses the laser beam hv output from the laser oscillator 4 as a ring-shaped beam, and builds up the laser beam hv that uses the ring-shaped beam. A condensing lens 10 that increases the energy density to a possible energy level, a beam irradiation mirror 12 having an eccentric rotation mechanism 11 that eccentrically irradiates a laser beam hv with an increased energy density, and a condensing lens 10 to the beam irradiation mirror 12. And a total reflection mirror 13 for sending a laser beam hv having an increased energy density.

  The beam shape changing mirror 9 changes the circular laser beam hv output from the laser oscillator 4 or passed through a collimation lens (not shown) to a ring shape beam. In this embodiment, as shown in FIG. 3, a metal powder ring that is a ring-shaped metal material made of a copper alloy previously pressed into a valve seat shape in a ring-shaped concave groove 14 formed in the valve seat forming portion 2. After the body 15 is arranged, the laser beam hv is irradiated with the laser beam hv which is a ring-shaped beam without scanning the laser beam hv along the circumference of the valve seat forming portion 2.

  At this time, as shown in FIG. 4, the laser beam hv is a ring-shaped beam having a diameter approximate to the diameter of the valve seat (here, corresponding to the metal powder ring body 15) and a width W2 smaller than the ring width W1 of the valve seat. And For example, when the inner diameter of the metal powder ring body 15 is φ1, the outer diameter is φ2, and the center diameter of the ring-shaped beam (the diameter of the center position of the beam width W2) is φ3, the relationship is φ1 <φ3 <φ2. . Specifically, the center diameter φ3 of the laser beam hv that is a ring-shaped beam is set to be approximately the same as the center diameter of the metal powder ring body (valve seat) 15 (the diameter at the center position of the ring width W1). Further, when the ring width W1 of the metal powder ring body 15 is 4 mm, the beam width W2 of the laser beam hv used as a ring-shaped beam is set to 0.5 mm. These numerical values are examples, and are not limited to the above numerical values.

  The condensing lens 10 is provided in front of the beam shape changing mirror 9, and increases the energy density of the laser beam hv, which is a ring-shaped beam, to an energy density that can be built up. Since the beam width W2 of the laser beam hv applied to the metal powder ring body 15 is not the same as the ring width W1 of the metal powder ring body 15, an energy density lower than the output energy density is sufficient. The energy density at this time is an energy density at which the metal powder ring body 15 can be melted, that is, can be built up.

  The total reflection mirror 13 is provided in front of the condenser lens 10. The total reflection mirror 13 functions to send the laser beam hv whose energy density has been increased by the condenser lens 10 to the beam irradiation mirror 12.

  The beam irradiation mirror 12 irradiates the metal powder ring body 15 disposed in the ring-shaped concave groove 14 with a laser beam hv having a ring-shaped beam with an increased energy density. The beam irradiation mirror 12 is eccentrically rotated with respect to the metal powder ring body 15 by the eccentric rotation mechanism 11 to irradiate the laser beam hv.

  As shown in FIG. 6, the beam irradiation mirror 12 has one end 16A gathered at the same point, and the other end 16B fixed to a peripheral portion of the beam irradiation mirror 12 whose circumferential portion is approximately divided into three parts. Three support members 16 are attached. The three support members 16 have a conical shape as a whole. Then, the intersection 17 with the beam irradiation mirror 12 when the perpendicular H is drawn to the beam irradiation mirror 12 from the part where the one ends 16A of the three support members 16 are gathered, is the center point 18 of the beam irradiation mirror 12. Is eccentric. The perpendicular H is set as the turning center line of the beam irradiation mirror 12.

  The eccentric rotation mechanism 11 has a mirror driving means including three or more cylinders installed on the back surface or side surface of the beam irradiation mirror 12. The beam irradiation mirror 12 can change the direction of the mirror by driving a plurality of cylinders installed on the back surface or side surface. In this embodiment, the center of the laser beam hv by the ring-shaped beam shown in FIG. 4 is not shifted from the center O of the metal powder ring body 15 as shown in FIG. The metal powder ring body 15 is irradiated with the beam eccentrically.

  More specifically, the beam irradiation mirror 12 is changed with respect to the turning center line (the above-mentioned perpendicular H) to change the inclination angle of the mirror back and forth and left and right (change the mirror inclination angle to an arbitrary angle). It is moved by the mirror driving means. In this way, the beam irradiation mirror 12 is swung at a position where the mirror center point 18 is not aligned with the center O position of the metal powder ring body 15 (the ring-shaped beam is changed by changing the mirror inclination). Swirl). At this time, the beam irradiation mirror 12 is rotated so that a part of the irradiated laser beam hv overlaps so that almost the entire metal powder ring body 15 is irradiated with the laser beam hv by the ring-shaped beam. Further, the eccentric rotating mechanism 11 performs the beam irradiation so that the irradiation range of the ring-shaped beam is within the range of the width W1 of the metal powder ring body 15 (the range between the inner diameter and the outer diameter of the metal powder ring body 15). The mirror 12 is rotated eccentrically.

“Description of Laser Cladding Valve Sheet Forming Method”
Next, a laser clad valve sheet forming method will be described. First, as shown in FIG. 3, a metal powder ring body 15 that has been preliminarily pressed into a valve seat shape is disposed in a ring-shaped concave groove 14 formed in the valve seat forming portion 2 of the cast cylinder head 1. In FIG. 3, since the engine structure has two intake and exhaust valves per cylinder, four laser clad valve seats are formed per cylinder.

  Next, the laser oscillator 4 is driven to output the laser beam hv to the optical system mechanism unit 7. The intensity of the output of the laser beam hv is controlled by the laser oscillator controller 5. The output laser beam hv is changed from a circular shape to a ring shape beam by the beam shape changing mirror 9. Further, as shown in FIG. 4, the laser beam hv formed into a ring-shaped beam has a diameter approximate to the diameter of the valve seat (metal powder ring body 15) and the ring width W1 of the valve seat (metal powder ring body 15). Is a ring-shaped beam having a small width W2.

  Then, the laser beam hv converted into a ring shape beam by the beam shape changing mirror 9 is increased to an energy density that can be built up by the condenser lens 10 arranged in front of the beam shape changing mirror 9.

  Next, the laser beam hv whose energy density has been increased by the condenser lens 10 is sent to the beam irradiation mirror 12 by the total reflection mirror 13 arranged in front of the condenser lens 10. Then, the beam irradiation mirror 12 irradiates the laser beam hv, which is a ring-shaped beam having an increased energy density, with the eccentric rotation mechanism 11 eccentrically rotated with respect to the metal powder ring body 15 as described above. To do. At this time, the trace (irradiation trace) of the laser beam hv irradiated to the metal powder ring body 15 is irradiated so as to overlap each other as shown in FIG. When the entire metal powder ring 15 is irradiated with the laser beam hv, the driving of the laser oscillator 4 is stopped and the irradiation of the laser beam hv is ended. The metal powder ring body 15 is melted by the irradiation of the laser beam hv. Thereafter, the metal powder ring body 15 melted by natural cooling is solidified to become a cladding layer, that is, a laser cladding valve sheet.

  When the first laser clad valve seat is formed, this time, the irradiation direction of the beam irradiation mirror 12 is changed from the solid line position of FIG. The metal powder ring body 15 disposed in the part 2 is subjected to laser cladding. By repeating this process, the laser powder hv is irradiated to the metal powder ring bodies 15 arranged in all the valve seat forming portions 2 formed in the cylinder head 1 to form a laser clad valve seat.

"Effect of the embodiment"
In the laser clad valve sheet forming method of the present embodiment, the laser beam formed as a rectangular beam is not scanned in the circumferential direction with respect to the valve sheet forming portion, but the laser beam hv formed as a ring-shaped beam is used as a metal powder ring body. Since the irradiation is performed so that the beam center is decentered with respect to the center of the metal powder ring body 15 and swirled over the entire area, the processing start portion and the processing end portion are overlapped to generate an empty space generated in the overlap portion. Holes and cracks can be eliminated. As a result, according to the method of the present invention, a high-quality laser clad valve seat can be obtained, and the yield can be improved.

  Further, in the laser clad valve sheet forming method of the present embodiment, it is not necessary to make the ring-shaped beam width equal to the valve seat width, so there is no need to increase the energy density by making the laser output high and energy that can be built up. It is possible to fully build up with density. As a result, laser cladding valve seat processing can be performed with a single laser oscillator 4, and equipment costs can be greatly reduced as compared with a technique using a plurality of laser oscillators 4.

  On the other hand, in the laser clad valve seat forming apparatus of the present embodiment, the laser beam hv is converted into a ring-shaped beam having a diameter approximate to the diameter of the valve seat by the beam shape changing mirror 12 and a width W2 smaller than the ring width W1 of the valve seat. Since the beam irradiation mirror 12 having the eccentric rotation mechanism 11 irradiates the entire region of the metal powder ring body 15, the laser cladding can be performed without rotating the cylinder head 1. The mechanism can be eliminated, and the equipment can be simplified and the equipment cost can be reduced.

  Further, according to the apparatus of the present embodiment, since it is not necessary to rotate the cylinder head 1 itself, by providing a plurality of optical system mechanism portions 7, multiple valves can be processed simultaneously, and one cylinder head can be processed. Processing time can be greatly shortened.

  Further, in the laser clad valve sheet forming apparatus of the present embodiment, the beam irradiation mirror 12 having the eccentric rotation mechanism 11 is disposed on the upper part of the part where the valve sheet forming parts 2 having the same diameter are gathered. Since each valve seat forming part is sequentially processed by changing the inclination, a troublesome mechanism for moving the entire apparatus for each valve seat forming part becomes unnecessary.

  Further, in the laser clad valve sheet forming apparatus of the present embodiment, the beam irradiation mirror 12 is eccentrically rotated so that the irradiation range of the ring-shaped beam is within the range of the width W1 of the metal powder ring body 15, and therefore a wasteful laser is used. Irradiation of the beam hv can be omitted, and the valve seat processing time can be shortened.

  The present invention can be used in a technique for directly depositing a valve seat alloy on a cylinder head.

DESCRIPTION OF SYMBOLS 1 ... Cylinder head 2 ... Valve seat part 3 ... Laser irradiation apparatus 4 ... Laser oscillator 5 ... Laser oscillator control part 7 ... Optical system mechanism part 9 ... Beam shape change mirror 10 ... Condensing lens 11 ... Eccentric rotation mechanism 12 ... Beam Irradiation mirror 13 ... Total reflection mirror 14 ... Ring-shaped concave groove 15 ... Metal powder ring body (ring-shaped metal material)

Claims (4)

A laser clad valve that forms a valve seat by placing a ring-shaped metal material in a ring-shaped concave groove formed in the valve seat formation part of the cylinder head, and then irradiating the metal material with a laser beam to melt and solidify it. In the sheet forming method,
The laser beam is formed as a ring-shaped beam having a diameter approximate to the diameter of the valve seat and smaller than the ring width of the valve seat, and the ring-shaped beam is irradiated eccentrically over the entire metal material. Laser clad valve sheet forming method. A laser clad valve that forms a valve seat by placing a ring-shaped metal material in a ring-shaped concave groove formed in the valve seat formation part of the cylinder head, and then irradiating the metal material with a laser beam to melt and solidify it. In the sheet forming apparatus,
A beam shape changing mirror that converts a circular laser beam output from a laser oscillator into a ring-shaped beam having a diameter approximate to the diameter of the valve seat and smaller than the ring width of the valve seat;
A beam irradiation mirror having an eccentric rotation mechanism for irradiating the laser beam eccentrically over the entire metal material;
A laser cladding valve sheet forming apparatus comprising: The laser clad valve sheet forming apparatus according to claim 2,
The beam irradiation mirror having the eccentric rotation mechanism is disposed above a portion where valve seat forming portions having the same diameter are gathered, and each valve seat forming portion is sequentially processed by changing the inclination of the beam irradiation mirror. Laser clad valve seat forming apparatus. The laser clad valve seat forming apparatus according to claim 2 or 3,
The eccentric rotation mechanism rotates the beam irradiation mirror eccentrically so that the irradiation range of the ring-shaped beam is within the range of the width of the ring-shaped metal material. .

Images