JPH10277761A - Laser cladding method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cladding near both ends in the width direction of a cladding when supplying a cladding powder to a valve seat portion of a cylinder head and irradiating a laser beam to form the cladding. The height is prevented from decreasing, and the yield and the like are improved. SOLUTION: A build-up powder is supplied to a valve seat portion of a cylinder head 1, and a laser beam is oscillated on the supplied build-up powder in a width direction (L) perpendicular to a build-up direction (P). When irradiating and simultaneously melting a part of the cylinder head and the build-up powder 3 to form a build-up portion, the apparent power density distribution peak position in the build-up region of the laser beam and the build-up region The peak position of the supply density distribution in the width direction (L) perpendicular to the direction of the overlay of the supplied overlay powder 3 is set to a corresponding position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for laser-building a valve seat on which an intake / exhaust valve of an engine is seated by using metal powder.

[0002]

2. Description of the Related Art In an aluminum alloy cylinder head of an automobile engine, when a valve seat, which is a seat surface of an intake / exhaust valve, is formed by overlaying, as shown in FIG. The laser beam 4 for processing is applied to the cylinder head 1 while supplying metal powder 3 as a buildup material from the supply nozzle 6 to the cylinder head 1.
Of the metal powder 3 and the metal powder 3 at the same time,
Is formed.

[0003] This type of overlaying is performed to improve the heat resistance, abrasion resistance, corrosion resistance and the like of the valve seat. The metal powder used for this overlaying and the technique of forming the overlay are as follows. JP-A-8-35027,
An example is disclosed in Japanese Patent Application Laid-Open No. 2-150014.

In this conventional laser cladding method, as shown in FIG. 2, while the cladding powder 3 is supplied from a supply nozzle 6 having one powder outlet 6a, the powder is perpendicular to the cladding direction P. The laser beam 4 oscillated with a predetermined swing width in the width direction L is used to perform the overlaying.

[0005]

However, in the conventional laser cladding method, the cladding powder supplied from the supply nozzle 6 to the cladding region 2 is swung in the oscillation direction L of the laser beam 4. The area corresponding to both ends of the width is low, and the area corresponding to the center of the swing width is high.

Therefore, for example, when forming a valve seat of an engine, if the laser beam 4 is applied to the overlaid powder which is deposited at a high central portion as described above and the overlaid powder is processed, especially the laser beam is oscillated. In some cases, the build-up height is not sufficient in both end regions in the direction, and even if machining is performed on the build-up portion to finish the shape of the valve seat, a missing portion may occur, and the required shape may not be obtained.

[0007] Further, if this build-up processing is performed in a slightly displaced state with respect to the build-up area where the build-up is required, the generation of the above-mentioned defective portion is further promoted.

As a result, in the above-mentioned conventional overlaying method, there is a problem that the yield is lowered and the manufacturing cost is increased.

[0009] In view of the above problems of the prior art, the present invention provides:
It is an object of the present invention to provide a laser cladding method and a device capable of stably obtaining a required cladding shape and having excellent productivity.

[0010]

According to a first aspect of the present invention, there is provided a laser cladding method, comprising: supplying a cladding material to a cladding region of a base material; A laser cladding method for irradiating a material while oscillating a laser beam in a width direction perpendicular to the cladding direction to form a cladding part by simultaneously melting a part of the base material and the cladding material. The peak position of the apparent power density distribution in the overlaid area of the laser beam and the peak position of the supply density distribution in the width direction perpendicular to the overlaid direction of the overlaid material supplied to the overlaid area. It is characterized in that it is set at a corresponding position.

Further, the laser cladding method according to the present invention comprises:
According to a second aspect of the present invention, the profile of the apparent power density distribution and the profile of the supply density distribution of the overlay material are set to have substantially the same shape.

Further, the laser cladding method according to the present invention comprises:
As described in claim 3, the overlay material is:
It is characterized in that it is supplied to the build-up area via at least two passages divided at its supply outlet.

Further, the laser cladding method according to the present invention comprises:
As described in claim 4, the center position of each of the exits of the two passages and the center position of each of the spots at both ends in the oscillating direction of the laser beam are matched.

Further, in the laser cladding apparatus according to the present invention, as set forth in claim 5, a supply means for supplying a cladding material to a cladding region of a base material, and a supplied cladding material. A laser beam irradiating means for irradiating a laser beam while oscillating the laser beam in a width direction perpendicular to the cladding direction, and forming a cladding portion by simultaneously melting a part of the base material and the cladding material. In a cladding apparatus, the supply means includes a supply nozzle forming at least two passages at its supply outlet.

Further, in the laser cladding apparatus according to the present invention, as set forth in claim 6, the supply nozzle comprises two nozzles arranged in a width direction perpendicular to the cladding direction. Features.

Further, the laser cladding apparatus according to the present invention is characterized in that it has an adjusting means for adjusting the center-to-center distance at the outlets of the two nozzles.

[0017]

According to the laser cladding method according to the first aspect of the present invention, the peak position of the apparent power density distribution in the cladding region of the laser beam and the cladding material supplied to the cladding region. Is set at a position corresponding to the peak position of the supply density distribution in the build-up width direction, so that more build-up material is supplied to the high energy region of the laser beam.

Therefore, the energy of the laser beam is efficiently used to melt the build-up material and the like, and a build-up portion having a desired height can be stably formed even near both ends in the width direction of the build-up. Thereby, an excellent effect that the yield and productivity of the overlaid product can be improved is brought about.

According to the laser cladding method of the present invention, the profile of the apparent power density distribution in the cladding region of the laser beam and the cladding of the cladding material supplied to the cladding region. Since the profile of the supply density distribution in the width direction is set to have substantially the same shape, the build-up material is more uniformly supplied to the build-up area, and the energy of the laser beam is used more efficiently to build up. By melting the material or the like, an excellent effect is obtained that a build-up portion having a desired height can be formed more stably even in the vicinity of both ends in the build-up width direction.

According to the laser cladding method of the third aspect of the present invention, since the cladding material is supplied to the cladding region through at least two passages divided at the supply outlet, Two peaks can be provided on both sides off the center in the supply density distribution of the overlay material,
This provides an excellent effect that the two peak positions can easily correspond to the peak positions of the power density distribution of the laser beam.

According to the laser cladding method according to the fourth aspect of the present invention, the respective center positions at the outlets of the two passages for supplying the cladding material and the respective centers of the spots at both ends in the oscillating direction of the laser beam. Matching the position will result in the region of the laser beam having the highest energy corresponding to the region where the build-up material is supplied the most, thereby more uniformly guiding the energy of the laser beam to the entire build-up material. As a result, an excellent effect of being able to form a built-up portion having a more uniform height is provided.

According to the laser cladding apparatus of the fifth aspect of the present invention, the cladding material is supplied to the cladding region through the supply nozzle forming the passage divided at the outlet. The build-up material can be supplied in a dispersed manner in the width direction, thereby providing an excellent effect that a build-up portion having a desired height can be easily formed even in the vicinity of both ends in the width direction of the build-up. Brought.

According to the laser cladding apparatus of the sixth aspect of the present invention, the supply nozzle for supplying the cladding material is formed by two nozzles arranged in the width direction of the cladding. Of course, the filling material can be distributed in the width direction and supplied, and the center-to-center distance at the outlets of the two nozzles is set in advance to a desired size corresponding to both peak intervals of the apparent power density distribution of the laser beam. It can be set and formed, which brings about an excellent effect that the overlaid portion having the desired height as described above can be formed stably.

According to the laser beam deposition apparatus according to the seventh aspect of the present invention, since the adjusting means for adjusting the center-to-center distance at the outlets of the two nozzles is provided, various laser beams having different oscillating widths can be used. There is an excellent effect that the center position of the two nozzles can be easily matched with the peak position of the power density distribution.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 3 shows a cylinder head port portion 1a of a cylinder head 1 as a base material on which a build-up is formed.
d, around which are formed two large-diameter intake valve seats 1b and two small-diameter exhaust valve seats 1c. Further, FIG. 3 shows a state in which the overlaid portion 5 is formed on one valve seat portion 1b for the intake valve, but is not limited to this, but is overlaid on the valve seat portion 1e for the exhaust valve. A part may be formed.

FIG. 4 is a partial perspective view of a cladding material (powder) supply device 9 which forms a part of the laser cladding device. As shown in the figure, the powder supply device 9 has a supply port 10a,
11a, each having two nozzles 10, 11 having an inner diameter of 2 mm,
It is formed by processing a copper pipe having an outer shape of 3 mm. The nozzles 10 and 11 are respectively provided with nozzle holders 12 and
13, the nozzle holders 12, 1
Reference numeral 3 denotes two parallel guide grooves 1 formed on the apparatus main body 14 and forming a part as an adjusting means for adjusting the distance between nozzle centers.
The movement can be adjusted in the L direction, that is, in the oscillation direction of the laser beam, along 4a and 14b.

Here, the passages in both nozzles 10, 11 are:
The passages in the nozzle holders 12, 13 communicate with the passages in the nozzle holders 12, 13, respectively. Further, the passages in the nozzle holders 12, 13 are arranged in the apparatus main body 14 and are movable at least in the L direction at the end surface 14c thereof. This flexible pipe is connected to a pipe (not shown)
At its upstream part, it is connected to one hopper or two hoppers (not shown) for accommodating metal powder as a build-up material.

Therefore, when supplying the powder to the padding area, the powder contained in the hopper passes through the flexible pipe, passes through the passages in the nozzle holders 12 and 13, and further passes through the passages in the nozzles 10 and 11. , Two supply ports 10a, 1
1a.

Further, since the nozzles 10 and 11 can be moved and adjusted in the arrangement direction L, they can be adjusted according to the swing width of the laser beam or the width of the overlaid area.
The distance D between the centers C ₁ and C ₂ of the supply ports 10a and 11a can be adjusted as appropriate.

Here, as for the nozzle for supplying the powder, when the above-mentioned center distance D is fixed and used for a specific overlaying process, as shown in FIGS. 5A and 5B, one nozzle is used. 20 has two outlets 20a, 20b
Alternatively, it is also possible to use a nozzle formed as a single nozzle 21 or a partition wall 21a provided at the outlet end of one nozzle 21 to divide the flow of powder at the outlet end into two.
In the case of the nozzle 21 shown in FIG.
It is preferred to feed the powder with the horizontal.

FIG. 6 is a view for explaining the apparent power density distribution of the laser beam oscillated in the direction L perpendicular to the build-up direction P. Here, in measuring the apparent power density distribution of the laser beam,
A laser beam having a spot diameter of 2 mm, an oscillating width of 6 mm, an oscillating frequency of 130 Hz, and a processing output of 4.5 kW is irradiated onto the acrylic resin 30 as shown in FIG. 6A for 2 seconds, and the resin penetration depth from the bang pattern 31 at that time. Was measured.

At this time, the apparent width W of the laser beam is 8 mm, and 1 mm in the oscillating direction.
The penetration depth of the acrylic resin 30 measured at intervals was as shown in FIG. 6B.

That is, the power peak in the apparent power density distribution of the oscillating laser beam is approximately 2.5 mm from the center of the oscillating laser (the center of the beam swing width).
It was confirmed that it was present at two places on the left and right of the position.

FIG. 7 is a diagram for explaining the deposition state of the powder supplied to the build-up area when supplying the powder using the apparatus of the present invention, that is, a diagram for explaining the powder supply density distribution in the oscillating direction of the laser beam. It is. As shown in the figure, when measuring the density distribution of the powder, the supply device 9 shown in FIG.
The powder was supplied to the upper surface of the smoothing plate 32 at a rate of 5 g / min and a total supply amount of 50 g / min for 2 seconds, and the deposition height of the powder 33 deposited at that time was measured from the flat surface. In this case, the distance D between the centers of the nozzles 10 and 11 was set to 4 mm.

Here, the powder deposition height measured at 1 mm intervals in the arrangement direction of the nozzles 10 and 11 is shown in FIG.
The result was as shown in FIG.

That is, it has been confirmed that the distribution is such that a peak of the deposition height exists at a position corresponding to the centers C ₁ and C ₂ of the supply ports 10 a and 11 a of the two nozzles 10 and 11.

On the other hand, as shown in FIG. 8B, the powder density distribution when powder is supplied using one nozzle 6 as in the prior art shows that the peak of the deposition height is at a position corresponding to the center of the nozzle inner diameter. Is distributed.

The powder supply device 9 according to the present invention as described above.
An embodiment in which the cylinder head 1 is overlaid using a CO ₂ laser with a maximum output of 5 kW that satisfies the conditions shown in Table 1 below will be described below.

[0040]

[Table 1]

The overbuilding process is performed on a cylinder head 1 made of an aluminum cast alloy (JIS standard AC2A material) of a 1998 cc in-line four-cylinder DOHC engine at a total of 16 valve seat portions for intake and exhaust valves. Was.

Further, as the powder material for the build-up, the composition of the components is% by weight, Co: 12.5%, Fe: 6.4.
%, Ni: 12.7%, V: 1.9%, Nb: 2.2
%, Mn: 1.2%, and a copper alloy powder composed of the balance Cu and impurities was used.

Further, in the powder supply device 9, the distance D between the centers C ₁ and C _{2 of} both nozzles 10 and 11 is set to 4 mm, and the amount of powder supplied from each nozzle 10 and 11 is 25 g / mi.
n, powder was supplied to the valve seat at a total supply of 50 g / min.

That is, the profile of the apparent power density when the laser beam is oscillated in the direction perpendicular to the cladding direction, and the supply density distribution of the cladding powder supplied to the cladding area. The surface was processed so as to have a peak at or near the position corresponding to each other.

It should be noted that both of the profiles described above can be set so that the peak positions are not only located at the same or near positions in the width direction of the build-up but also have the same shape or an approximate shape.

FIG. 9 shows the result of measuring the build-up height from a predetermined position in the width direction of the build-up portion obtained under the above conditions. As is clear from FIG. 9, the height of the central portion is lower and the both sides in the width direction are formed thicker than the conventional build-up shape indicated by the dotted line.

Therefore, even if machining is performed on both sides in the width direction of the built-up portion, occurrence of a defective portion is prevented, and a desired valve seat shape can be stably obtained.

Further, since the energy of the laser beam is efficiently and uniformly transmitted to the supplied powder, variations in the build-up shape (build-up height) are suppressed, and
A stable and uniform build-up shape can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic view for explaining a conventional laser cladding method.

FIG. 2 is a schematic view for explaining a conventional method of forming a valve seat of an engine by laser overlaying.

FIG. 3 is a perspective view of a cylinder head port portion when a valve seat is formed by using the laser cladding method according to the present invention.

FIG. 4 is a partial perspective view of a powder supply device forming a part of the laser cladding device according to the present invention.

FIG. 5 is a perspective view showing another embodiment of the powder supply nozzle which is a part of the laser cladding apparatus according to the present invention.

FIG. 6 is a diagram for explaining an apparent power density distribution of a laser beam according to the present invention, wherein FIG. 6 (a) shows an acrylic melt shape when an acrylic resin is irradiated with a laser beam; (B) shows the penetration depth with respect to the apparent beam width.

FIG. 7 is a schematic perspective view for explaining a method for measuring a density distribution of a supplied powder according to the present invention.

8 (a) is a diagram showing the deposition height in the width direction of the supplied powder obtained by the measurement method shown in FIG. 7,
(B) is a diagram showing the deposition height in the width direction of the supplied powder when a conventional nozzle is used.

FIG. 9 is a diagram showing the build-up height when a cylinder head of an engine is built using the laser build-up method and apparatus according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder head 1a Cylinder head port part 1b Valve seat part for an intake valve 1c Valve seat part for an exhaust valve 1d Spark plug hole 2 Overlaid area 3 Overlay powder 4 Laser beam 5 Overlay section 9 Powder supply device 10, 11 supply Nozzles 10a, 10b Supply ports 12, 13 Nozzle holders 14 Main body 14a, 14b Guide grooves 20, 21 Supply nozzles 30 Acrylic resin 32 Smooth plate

Claims (7)

[Claims] 1. A cladding material is supplied to a cladding region of a base material, and the supplied cladding material is irradiated with a laser beam while oscillating in a width direction perpendicular to the cladding direction. A laser cladding method for simultaneously forming a cladding portion by melting a part of the cladding material and the cladding material, wherein a peak position of an apparent power density distribution in the cladding region of the laser beam and the cladding region. A laser cladding method comprising: setting a peak position of a supply density distribution in a width direction perpendicular to a cladding direction of a cladding material to be supplied to a corresponding position. 2. The laser beam overlay method according to claim 1, wherein the profile of the apparent power density distribution and the profile of the supply density distribution of the overlay material are set to have substantially the same shape. 3. The laser cladding method according to claim 1, wherein the cladding material is supplied to the cladding region through at least two passages at the supply outlet. . 4. The laser beam thickness according to claim 3, wherein a center position of each of the exits of the two passages coincides with a center position of each of the spots at both ends in the oscillating direction of the laser beam. Serving method. 5. A supply means for supplying a build-up material to a build-up area of a base material, and irradiating the supplied build-up material with a laser beam oscillating in a width direction perpendicular to the build-up direction. A laser beam irradiating means, and a laser cladding apparatus for forming a cladding part by simultaneously melting a part of the base material and the cladding material, wherein the supplying means is divided into at least two at its supply outlet. A laser cladding device comprising a supply nozzle forming two passages. 6. The laser cladding apparatus according to claim 5, wherein the supply nozzle includes two nozzles arranged in a width direction perpendicular to the cladding direction. 7. The laser cladding apparatus according to claim 6, further comprising adjusting means for adjusting a center-to-center distance at outlets of the two nozzles.