JP2003025079A - Method for grooving surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for grooving surface which is capable of forming a groove of an adequate shape suitable for the conditions required when a work is actually used to the work surface. SOLUTION: While the inside surface of a bore is irradiated with a laser beam at a prescribed pulse frequency, the laser beam is moved at a prescribed speed, by which the fine groove is formed along the moving direction. At this time, a cutting tool size S defined by a 'working speed/pulse frequency' and expressed as the distance between pulses is set at 5.6 to 28 μm, by which the continuous groove and a built-up section 33 built up from the inside surface of the bore at the circumference of the groove are formed. The depth b of the formed groove 32 is above the height c of the built-up section 33 on the basis of the inside surface 31 of the bore. The average output of the laser beam is set at a range from 10 to 50 W.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a groove processing method using laser light for forming fine grooves by irradiating the surface of a work with laser light.

[0002]

2. Description of the Related Art For example, a cylinder block as a work has a condition of preventing seizure of a piston as a condition required when the work is actually used. In order to meet this condition, an oil reservoir dent is formed on the inner surface of the bore of the cylinder block.

As a processing method for forming an oil sump, honing is known in which a fine mesh-shaped oil sump is formed by a honing grindstone, but the entire inner surface of the bore is processed while the honing grindstone is rotated and moved up and down. Therefore, it is difficult to deeply form only the depression of a part of the area where the lubricating oil needs to be positively retained.

Therefore, laser processing has also been proposed in which a portion of the inner surface of the bore where the lubricating oil needs to be positively retained is irradiated with laser light to form an oil reservoir depression in that area. ing. According to the groove processing method using laser light, a groove having a desired shape can be formed only in a necessary region. A groove processing method using laser light is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-40068.

[0005]

By the way, from the viewpoint of preventing seizure of the piston, it is better to increase the depth of the recess of the oil sump to enhance the function of retaining the lubricating oil. If the value is larger than necessary, the consumption of lubricating oil will increase. In addition, since the amount of lubricating oil retained varies depending on the shape of the depression, the shape of the depression affects the coefficient of friction with the piston and greatly affects the power performance of the engine.

Therefore, in the laser processing, it is necessary to form the recess of the oil sump in an appropriate shape so as to prevent the seizure and improve the power performance while reducing the consumption of the lubricating oil. is there.

The present invention has been made under such a background, and it is possible to form a groove on the surface of a work which can form a groove having an appropriate shape suitable for the conditions required when the work is actually used. An object is to provide a groove processing method.

[0008]

The objects of the present invention are achieved by the following means.

(1) In the groove processing method using laser light for forming fine grooves by irradiating the work surface with laser light, the work surface irradiated with laser light is
A continuous groove and a raised portion that rises from the work surface around the groove are formed, and the depth of the groove based on the work surface is equal to or higher than the height of the raised portion. Groove processing method using laser light.

(2) In the groove processing method using laser light, in which fine grooves are formed along the moving direction by moving the work surface at a predetermined moving speed while irradiating the work surface with laser light at a predetermined pulse frequency, The bite size, which is defined by "moving speed / pulse frequency" and expressed as a distance between pulses, is set to 5.6 μm to 28 μm, and a continuous groove is formed on the work surface and the work surface is surrounded by the groove. A groove processing method using a laser beam, characterized in that a ridge of a ridge is formed, and the depth of the groove with respect to the surface of the work is equal to or higher than the height of the ridge.

(3) The average output of the laser light is 10 W to 5
The groove processing method using laser light according to the above (2), wherein the groove width is 0 W.

(4) After setting a predetermined bite size within the range of the bite size to form a continuous groove on the surface of the work and a raised portion that rises from the work surface around the groove, The laser according to the above (2), characterized in that the cutting tool is set to a bite size larger than the previous one in the range of the bite size, and the groove formed by the previous machining is irradiated with laser light again. Groove processing method using light.

(5) The groove processing method using laser light according to the above (4), wherein the bite size when the laser light is irradiated again is about 28 μm.

(6) The above-mentioned (1) to (5) are characterized in that after the groove is formed on the surface of the work by laser light, the raised portion is removed by honing.
A groove processing method using a laser beam according to any one of 1.

(7) The groove machining method using a laser beam according to any one of (1) to (6), wherein the work surface is an inner surface of a bore of an engine cylinder block.

[0016]

The present invention configured as described above has the following effects.

According to the first aspect of the invention, the surface of the work is irradiated with laser light to form a continuous groove and a raised portion that rises from the work surface around the groove,
Since the depth of the groove with respect to the work surface is equal to or higher than the height of the raised portion, conditions required when the work is actually used, for example, a fluid such as lubricating oil must be held. It is possible to form a groove having an appropriate shape that meets the condition that the work does not occur on the work surface.

According to the second or third aspect of the present invention, the bite size is set to 5.6 μm to 28 μm, and continuous grooves are formed on the surface of the work, and the work surface rises around the grooves. Since the depth of the groove that forms a raised portion and the surface of the work as a reference is equal to or higher than the height of the raised portion, conditions required when the work is actually used, such as lubricating oil It is possible to form a groove on the surface of the work piece having an appropriate shape that meets the requirement that the above fluid must be retained.

According to the invention of claim 4 or 5, by performing the laser processing in a plurality of stages, it is possible to form a deep groove while reducing the height of the raised portion generated by the laser processing. .

According to the invention of claim 6, even if the raised portion is removed by honing, a groove having a predetermined depth remains on the surface of the work.

According to the invention described in claim 7, it is possible to form a groove having a high function of holding the lubricating oil and suitable as a recess of the oil sump.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a view showing a state in which a laser beam is irradiated from a laser processing device 10 to a bore inner surface 31 to form fine grooves, and FIG. 2 is a bore inner surface. Three
It is a perspective view which shows the area | region where laser processing is given among 1st. In addition, in FIG. 2, the region to be laser-processed is indicated by a chain double-dashed line.

As shown in FIG. 1, a laser processing apparatus 10
Is a laser oscillator 11, an irradiation mirror 12, a condensing unit 14 having a condensing lens 13 built-in, a transmission mirror 15 provided at the lower end of the condensing unit 14 in the figure, and an axis line around the condensing unit 14. Drive device 16 for rotating and vertically moving in the axial direction
And. The laser light 20 output from the laser oscillator 11 is reflected by the irradiation mirror 12 toward the condensing unit 14, condensed by the condensing lens 13, and transmitted by the transmission mirror 15.
Then, the inner surface 31 of the bore of the engine cylinder block 30 (corresponding to the work surface) is irradiated.
By moving the condensing part 14 at a predetermined speed while irradiating the laser light 20 on the bore inner surface 31 at a predetermined pulse frequency, fine grooves continuous in the moving direction are formed on the bore inner surface 31.

As shown in FIG. 2, the groove processing by the laser light 20 is performed on a region of a predetermined size from the opening end on the cylinder head side. Since this region corresponds to the vicinity of the top dead center of the piston, thermal shock is large, and seizure should be most prevented.

When the groove is processed by the laser beam 20, a bulge portion (referred to as "debris") is inevitably formed around the groove due to expansion and evaporation by heating. If such a raised portion remains on the bore inner surface 31, smooth sliding of the piston is hindered. Therefore, after the laser processing, the raised portion formed on the inner surface 31 of the bore is completely removed by honing or the like to form the inner surface 31 of the bore smoothly. This honing process is performed by a conventionally known device and method.

As a result, a series of processes for forming the recess of the oil sump in the predetermined region of the inner surface 31 of the bore is completed.

Next, the laser processing conditions in the groove processing by the laser light 20 will be considered.

(Specification 1 of Laser Processing Condition) FIG. 3 is a diagram showing the relationship between the number of repetitions of irradiation of the laser beam 20 and the processed shape in the specification 1 of laser processing condition. The processed shape is, as shown in FIG. 6 (A), a groove 32 indicated by reference numeral a.
Groove width (μm), the depth (μm) of the groove 32 based on the bore inner surface 31 indicated by the reference sign b, and the height (μm) of the raised portion 33 based on the bore inner surface 31 indicated by the reference sign c. ) Was measured. The triangles in FIG. 3 indicate the measured values of the groove width (μm), the circles indicate the measured values of the depth (μm) of the grooves 32, and the squares indicate the measured values of the height (μm) of the raised portion 33, respectively. Shows.

The laser processing condition specification 1 has an average output of 5
0 W, the processing speed is 15 m / min. Under this condition,
The number of repetitions (pulse frequency) of irradiation of the laser light 20 is 1
The frequency was changed from kHz to 90 kHz.

When the number of repetitions is changed from 1 kHz to 90 kHz, the processed shape is not discontinuous, that is, a pattern in which dot-like depressions are formed, a pattern in which the surface is continuous depressions, or a depression. It changes to a pattern where the surface is raised or a pattern where the surface is a continuous shallow depression.

In the pattern, the depth b of the groove 32 relative to the bore inner surface 31 is smaller than the height c of the raised portion 33 (b <c). Therefore, if the raised portion 33 is removed by the honing process performed after the laser processing,
The groove 32 has a remarkably low function of holding the lubricating oil, and is not suitable as a depression of the oil sump.

On the other hand, in the pattern, the depth b of the groove 32 with respect to the bore inner surface 31 is not less than the height c of the raised portion 33 (b ≧ c). For this reason, even if the raised portion 33 is removed after the laser processing, the groove 32 has a high function of retaining the lubricating oil, which is suitable as a depression of the oil sump. That is, the groove 3 having an appropriate shape that meets the conditions required when actually using the cylinder bore as the work.
It becomes 2.

Therefore, by performing the processing in the frequency band of the pattern of about 9 kHz to about 45 kHz, the continuous groove 32 and the raised portion 33 rising from the bore inner surface 31 around the groove 32 are formed. The depth b of the groove 32 with respect to the inner surface 31 of the bore is equal to or greater than the height c of the raised portion 33, and it is possible to form a depression in the oil pool for preventing seizure, which has a high function of retaining lubricating oil. all right.

(Specification 2 of Laser Processing Condition) FIG. 4 is a diagram showing a relationship between the number of repetitions of irradiation of the laser beam 20 and the processed shape in the specification 2 of laser processing condition.

In the laser processing condition specification 2, the average output is 1
0 W, the processing speed is 15 m / min. Under this condition,
The repetition rate was changed from 1 kHz to 90 kHz.

When the number of repetitions is changed from 1 kHz to 90 kHz, the processed shape is, as shown in the figure, a discontinuous pattern, that is, a pattern in which point-like depressions are formed, a pattern in which the surface has continuous depressions, or a depression. It changes with the pattern that the surface rises.

Similar to the specification 1, in the pattern, the depth b of the groove 32 with respect to the bore inner surface 31 is not less than the height c of the raised portion 33 (b ≧ c). In the pattern,
The depth b of the groove 32 based on the bore inner surface 31 is smaller than the height c of the raised portion 33 (b <c).

Therefore, by performing processing in the frequency band of the pattern of about 9 kHz to about 40 kHz, a continuous groove 32 and a raised portion 33 that rises from the bore inner surface 31 around the groove 32 are formed. The depth b of the groove 32 with respect to the inner surface 31 of the bore is equal to or greater than the height c of the raised portion 33, and it is possible to form a depression in the oil pool for preventing seizure, which has a high function of retaining lubricating oil. all right.

(Specification 3 of Laser Processing Condition) FIG. 5 is a diagram showing the relationship between the number of repetitions of irradiation of the laser beam 20 and the processed shape in the specification 3 of laser processing condition.

In the laser processing condition specification 3, the average output is 1
0 W, the processing speed is 5 m / min. Under this condition, the repetition rate was changed from 1 kHz to 90 kHz.

When the number of repetitions is changed from 1 kHz to 90 kHz, the processed shape is not discontinuous, that is, a pattern in which point-like depressions are formed, a pattern in which the surface has continuous depressions, or a depression. It changes with the pattern that the surface rises.

Similar to the specification 1, in the pattern, the depth b of the groove 32 with respect to the inner surface 31 of the bore is not less than the height c of the raised portion 33 (b ≧ c). In the pattern,
The depth b of the groove 32 based on the bore inner surface 31 is smaller than the height c of the raised portion 33 (b <c). Further, in this specification 3, the groove 32 may not be formed (b =
0).

Therefore, by performing processing in the frequency band of the pattern of about 3 kHz to about 12 kHz, a continuous groove 32 and a raised portion 33 that rises from the bore inner surface 31 around the groove 32 are formed. The depth b of the groove 32 with respect to the inner surface 31 of the bore is equal to or greater than the height c of the raised portion 33, and it is possible to form a depression in the oil pool for preventing seizure, which has a high function of retaining lubricating oil. all right.

(Study on Byte Size) FIG. 6 (B)
As shown in, the bite size S (μm) represented by the distance between pulses is based on the machining speed and the number of repetitions.
It is defined by "machining speed / pulse frequency". The laser processing condition specifications 1 and 2 have the same processing speed and different laser average outputs. Further, the laser processing conditions of specifications 2 and 3 have the same laser average output but different processing speeds.

FIGS. 3 to 5 also show the byte size S obtained from the above definition. For example, referring to FIG. 3, when the number of repetitions is 9 kHz, which is the boundary between the pattern in which continuous grooves are not formed and the pattern in which continuous grooves are formed in plan view, 15 [m / min] / 60 [ sec] / (9 × 100
From 0) [Hz], the bite size S is about 28 μm. Also, the number of repetitions is 45k, which is the boundary between patterns.
In the case of Hz, 15 [m / min] / 60 [sec] / (45 × 100
From 0) [Hz], the bite size S is about 5.6 μm.

In specifications 1 to 3 of the laser processing conditions, the depth b of the groove 32, which is a continuous groove and is based on the bore inner surface 31, is greater than or equal to the height c of the raised portion 33 (b ≧
The lower limit value and the upper limit value of the byte size S at the boundary of the pattern which is c) are Is.

Here, the lower limit value of the bite size S varies depending on the specifications, but if the laser average output is the same, it should be about the same, and the deviation between the specifications 2 and 3 is the same. There is no significant difference due to measurement error and deviation of the position plotted on the figure.

The average laser output (5
0 W) is 500% of the laser average output (10 W) in the specifications 2 and 3, and although the energy amount is considerably different, the pattern characteristics are almost the same and the processing speed is the same between the specifications 1 and 2. The deviation of the lower limit of the bite size S is only about 11% with respect to the specification 2, which is extremely small compared to the large difference in energy amount (500%), and it is considered that there is no big difference.

From this, the average laser output is 10 W to 50 W.
In the range of W, by setting the pulse frequency so that the lower limit value of the bite size S is 5.6 μm to the upper limit value of 28 μm even when the machining speed is changed, the groove shape of the pattern, that is, the continuous groove And the depth b of the groove 32 with respect to the inner surface 31 of the bore is the raised portion 3
It was found that it is possible to form the depression of the oil pool for preventing seizure having the height c of 3 or more (b ≧ c).

Range of the byte size S above 5.6 μm
Since the depth b of the groove 32 is deep in the range of 8 μm to 12 μm of 28 μm, the bite size S is more suitable when applied to the case of forming the depression of the oil sump having a high function of holding the lubricating oil.

Experiments were carried out for processing speeds of 5 m / min (specification 3) and 15 m / min (specification 1 and specification 2) for the following reasons. In other words, if the machining speed is less than 5 m / min, it will be slower than the conventional machining time, so production efficiency (number of machining per unit time)
Is extremely low. In addition, the processing speed is 15m / min
If the pulse frequency is higher than this, the pulse frequency needs to be increased. However, if the pulse frequency is too high, the laser processing apparatus 10 is heavily worn and the life of the apparatus is shortened. From the above, in consideration of the lower limit value and the upper limit value of the processing speed that can be adopted at the time of actual production, the experiment was performed for the processing speeds of 5 m / min (specification 3) and 15 m / min (specification 1 and specification 2). I went.

Further, an experiment was carried out for the cases where the average laser output was 50 W (specification 1) and 10 W (specification 2 and specification 3), for the following reasons. That is, if the laser average output is less than 10 W, it is not possible to form the groove 32 having a sufficient depth to function as a depression of the oil sump. Further, when the laser average output is larger than 50 W, for example, 100 W, the ineffective component of the laser light 20 becomes large, and only about 50 W can be used. Further, in the current production, a range of 10 W to 50 W is usually used as a range of the laser average output. From the above, further considering the energy saving, the laser average power is 50 W (specification 1) and 1
Experiments were performed for 0 W (specifications 2 and 3).

As described above, whether or not a depression having a sufficient oil reservoir function is formed can be determined based on the bite size S defined by "machining speed / pulse frequency". Even when the speed is changed, by processing in the pulse frequency band in which the bite size S is 5.6 μm to 28 μm, it is possible to easily perform groove processing with the laser light 20 without trial and error.

(Second Embodiment) The second embodiment is characterized in that the groove processing with the laser beam 20 is repeated twice.
This is different from the first embodiment, which is performed only once.

That is, first, a predetermined bite size S within the range of the bite size (5.6 μm to 28 μm) is set and laser processing is performed, and a continuous groove 32 and the surrounding groove 32 are formed on the bore inner surface 31. The raised portion 33 is formed. The depth b of the groove 32 with respect to the inner surface 31 of the bore is not less than the height c of the raised portion 33.

After that, the byte size range (5.6
(μm to 28 μm), a larger bite size than the first bite size is set, and the same spot as the groove 32 formed by the first machining is irradiated with laser light again to perform laser machining.

Here, in the first laser processing, the bite size S capable of forming the deep groove 32 even if the swell is large.
(Size corresponding to approximately the middle of the pattern). The second laser processing has a small rise (groove 3
2 also becomes smaller), and the bite size S (size corresponding to the side closer to the pattern side in the pattern) capable of processing the continuous groove is set. The bite size S when the laser beam 20 is irradiated again is preferably around 28 μm.

By performing the two-step laser processing, the raised portion 33 generated by the first laser processing.
It has been found that the height of the can decreases.

Since the height of the raised portion 33 is reduced, the removal amount by the subsequent honing processing is reduced, so that the honing processing is facilitated. Moreover, since the time required for honing processing is shortened, it can contribute to the improvement of production efficiency.

It is also possible to perform laser processing in two or more stages.

[Brief description of drawings]

FIG. 1 is a diagram showing a state in which a laser beam is emitted from a laser processing apparatus to the inner surface of a bore to form a fine groove.

FIG. 2 is a perspective view showing a region of the inner surface of the bore where laser processing is performed.

FIG. 3 is a diagram showing the relationship between the number of repetitions of laser light irradiation and the processed shape under laser processing condition specification 1.

FIG. 4 is a diagram showing the relationship between the number of repetitions of laser light irradiation and the processed shape under laser processing condition specification 2.

FIG. 5 is a diagram showing the relationship between the number of repetitions of laser light irradiation and the processed shape under laser processing condition specification 3.

FIG. 6 (A) is an enlarged view showing a groove machining shape, and FIG. 6 (B) is a diagram for explaining a bite size defined by “machining (moving) speed / pulse frequency”. Is.

[Explanation of symbols]

10 ... Laser processing device 20 ... Laser light 30 ... Engine cylinder block 31 ... Inner surface of bore (work surface) 32 ... Groove 33 ... Rising part b ... Groove depth c ... Height of rising part S ... byte size

Claims (7)

[Claims] 1. A groove processing method using laser light for forming fine grooves by irradiating a work surface with laser light, comprising: a continuous groove on the work surface irradiated with the laser light; and a periphery of the groove. And forming a raised portion rising from the surface of the work, and the depth of the groove based on the surface of the work is equal to or higher than the height of the raised portion. 2. A groove processing method using laser light, wherein a fine groove is formed along the moving direction by moving the work surface at a predetermined moving speed while irradiating the work surface with laser light at a predetermined pulse frequency. Moving speed / pulse frequency ", and the bite size expressed as the distance between pulses is 5.6 μm to 28 μm.
μm to form a continuous groove on the surface of the work and a raised portion that rises from the work surface around the groove, and the depth of the groove with reference to the work surface is the depth of the raised portion. A groove processing method using a laser beam, which is characterized by having a height or more. 3. The average output power of the laser light is 10 W to 50 W.
The groove processing method with a laser beam according to claim 2, wherein 4. After setting a predetermined bite size within the range of the bite size and forming a continuous groove on the surface of the work and a raised portion that rises up from the work surface around the groove, 3. The laser according to claim 2, wherein a tool size larger than the first tool size is set within the range of tool sizes, and the groove formed by the first processing is irradiated with laser light again. Groove processing method using light. 5. The groove processing method with laser light according to claim 4, wherein the bite size when the laser light is irradiated again is in the vicinity of 28 μm. 6. The laser light according to claim 1, wherein after the groove is formed on the surface of the work by laser light, the raised portion is removed by honing. Groove processing method. 7. The work surface is an inner surface of a bore of an engine cylinder block.
A groove processing method using a laser beam according to claim 6.