JPH01310801A - Mirror face machining method - Google Patents

Abstract

PURPOSE:To enhance the yield of manufacture without damaging the finished surface by scraps, by moving a machining tool from near the center to the center, and then toward the periphery. CONSTITUTION:When machining is made from Point S as the starting point of machining till Point O via Point Q, the load applied on the tip of the tool is increased by and by, wherein this gradual increase of the load does not cause damage to the tool. When the tip attains Point O as the center, there are only work surfaces already machined, so that the load applied on the tip will be nullified. Therefore, there is no risk of damaging the tip even though the circumferential speed is zero. After attainment of the center point O as described, the moving direction of the tool is inverted so as to follow O R K to create the surface ORK, which is the finished surface. In this process, the splash generated is thrown to the periphery, not touching the finished surface. Thus it does not damage the finished surface to enhance the yield from manufacture.

Description

[Detailed description of the invention] (Power technology field This invention uses Cu to make a laser reflecting mirror.

This invention relates to an improvement in the method of manufacturing soft metals such as A7 by ultra-precision cutting.

Here, the laser reflecting mirror is a mirror for reflecting the light of a laser that generates infrared light, such as a CO2 laser or a CO laser.

It is not a visible light reflector.

A CO2 laser can oscillate several kinds of light, and for example, it can generate a powerful light of 10.6 μm.

The wavelengths of visible light and infrared light are significantly different. No matter what kind of material it is, it has a different reflectance. In addition, since the infrared laser reflector is irradiated with strong laser power, it generates a lot of heat.

For this reason, infrared laser reflecting mirrors are required to have characteristics that are completely different from those of reflecting mirrors used in visible light optical systems.

Glass with a metal coating deposited on it cannot be used.

Generally, the reflectance of metal increases as the wavelength of light becomes longer. Therefore, many infrared reflecting mirrors utilize metal surfaces.

Furthermore, since the reflectance is not 100%, reflection loss occurs. The loss is converted into heat. In order to eliminate this, it is cooled, but in order to be able to cool it, it is necessary that the splinter has high thermal conductivity.

For this reason, Cu is used as a reflector for infrared lasers.
, Ag, Mo, and Si, and reflectors coated with Au thin films are used.

MOlSi has a hard surface and is difficult to oxidize. The foul rate is also quite high. However, because they are hard, these monthly profits are difficult to process. It is difficult to freely process it into complex shapes,
It is.

Cu, Al are soft metals. Processability is J: Good.

Can be processed into complex shapes. Even though it's a reflective mirror,
In addition to flat mirrors, complex functional curved surfaces such as convex and concave surfaces are required. It is important that the material has good workability.

(a) Prior Art The present invention relates to an improvement in a method for manufacturing a laser reflecting mirror by ultra-precision cutting from materials such as Cu, A, and d.

FIG. 3 shows a conventional cutting method.

A workpiece 2 made of copper, aluminum, etc. is attached to the tip of the spindle 1. This is slightly larger than the final shape of the reflector.

The surface of the work 2 is cut with a diamond cutting tool 3 in order to make the surface of the work 2 mirror-like.

Here, the surface to be processed is shown as a flat surface, but in reality, any surface having arbitrary rotational symmetry such as a concave surface or a convex surface may be used.

Set the center of work 2 to 01 and the outer periphery to K.

The spindle 1 and the workpiece 2 are rotated at high speed, and the diamond cutting tool 3 is applied to the surface of the workpiece 2 to cut the surface of the workpiece.

Conventionally, diamond bi)・3 was set from the outer periphery K to the center 0.
"Move it towards": It was turning.

This is common to any type of processing. Always move bites from the outside to the inside.

(1) Problems to be Solved by the Invention The chips 4 cut by the cutting tool fly toward the outer periphery due to centrifugal force. There will be no problem as long as Kiri 19 Pow 4 is published and removed without any delay.

However, the cutting chips 4 may become entangled with the tip of the cutting tool and may not immediately fly toward the outer periphery. In such a case, some of the chips may come into contact with the already cut surface and damage the cut surface.

Chips often have a spiral shape, and there is a high probability that the free end will come into contact with the finished surface.

Since it is a soft metal surface, even a strong contact with the chips 4 will cause damage. The finished surface must be mirror-like, so there should be no scratches, even the slightest.

This problem arises from the fact that the mirror surface is finished using ultra-precision cutting.

It is good as long as the chips do not come into contact with the surface of the lily.

In order to do this, contrary to the conventional method, from the center 0 point,
All you have to do is move the bite toward the point on the outer periphery. If you do this, the cutting surface will always be on the inside of the cutting edge, so the chips won't come into contact with the cutting edge.

However, in reality, such cutting is impossible.

The circumferential speed of the workpiece 2 at the center 0 is 0. When a cutting tool is applied here, the cutting speed is 0. Cutting speed is the relative speed between the cutting tool and the workpiece. (b) - If the distance between the contact point and the center O is R, and the angular velocity of the work 2 and spindle 1 is Ω, the cutting speed ■ is given by RΩ.

Even though the cutting speed is O, this part must be dug down to some extent.

You can't do something like this. If you apply excessive force,
The tip of the cutting tool is chipped. Even if this is not the case, there will always be a portion with poor cutting near the center.

For this reason, it is not possible to start cutting from center 0.

B) Method of the present invention The cutting method of the present invention starts cutting from a point near the center O,
First, the cutting tool is moved inward to reach the center 0, and then the cutting tool is moved outward from the center O toward a point K on the outer periphery.

In this way, the circumferential speed is not 0 at the cutting start point, so
Cutting can be started smoothly.

FIG. 1 is a cross-sectional view of the central part of the workpiece, about 3 digits apart.

The first side of the workpiece is indicated by O'H. Assume that the thickness to be cut is D. In other words, it is assumed that the surface after cutting is OK. Take point R on the half line OK.

The movement of the byte in the conventional method is H-+→R→0. If you try to move the bite from the center, O'→Q −+
It becomes R-+K. This proves to be impossible.

In the present invention, cutting is started from a certain fixed point S near the center O. Here, since the cutting speed is not 0, cutting is possible.

It is not just about starting from the cutting starting point S.

The present invention has another device.

Unlike the conventional method (H-+K), the cutting tool is not moved vertically from the beginning to cut the entire cutting thickness D.

Instead, the cutting tool is moved inward from the cutting start point S, and the cutting depth d is increased with the amount of movement.

In other words, the locus SQO of the cutting edge of the cutting tool moving inward from point 8 to point 0 is made into a circular arc, quadratic curve, etc. that touches OK at the center O.

Let ops = s. Assume that the cutting edge of the cutting tool is at the midpoint Q of O8. The vertical foot drawn from Q to the half line O'S is Q
'. Let SQ'-w. W is the amount of movement.

Let it be 0'Q'-X. w + x = s.

When the cutting tool is at 8 points, the cutting depth d is O.

As the point approaches 0 from 8, d approaches D.

The conditions are: (1) 8 points d-O(1) (ii) 0 points d = D
(2) d increases monotonically between 0 and 80 widths. (3) means that the locus SQO touches the half-line OK at the 0 point.

Any function shape of the cutting depth may be used as long as it satisfies the conditions (1) to (3).

The simplest one is a parabolic quadratic curve.

Instead of the cutting depth d, if we express the function form using the height y from the OK surface and X, then y = D - d (4) x = s
-w (5) However, this quadratic curve is expressed by using O as the origin. The slope y' of the curve at the cutting start point S (x=s) is as follows. D is the cutting thickness, which is extremely small on the order of several μm. Therefore, the slope y' of the curve at 8 points is small.

Furthermore, there is another simple example. OQS to yen
), and can be expressed as the origin with the center 0. The slope y' of the curve at the cutting start point (8 points) is as follows. D ((s), so (8) is almost equal to (7), but slightly larger.

Since the cutting depth is O at the cutting start point S, almost no force is applied to the cutting tool. There is no shortage of bites here.

When moving from point 8 to point Q and toward the center point 0, the load on the cutting edge gradually increases. This is because the cutting depth d becomes deeper.

This slow increase in load will not cause the cutting edge to become overloaded.

Then the cutting edge of the cutting tool moves to the center 0 point. When the zero point is reached, only the surface of the workpiece that has already been cut is present at the cutting edge. In other words, at this time, the load applied from the workpiece to the cutting edge of the cutting tool is O. Therefore, even if the circumferential speed is 0, there is no risk of chipping of the tool cutting edge.

In this way, between 80 and 80 degrees, the part where the circumferential speed is low is first cut, but since the cutting depth d is smaller than the original cutting depth D, the load is small, and the load becomes O at the 0 point. Again, no strong load is applied to the tip of the cutting tool.

In this way, after reaching the center 0, the direction of movement of the cutting tool is reversed, and the cutting tool is moved in the direction O-+R-)K. This type of byte movement is completely different from conventional methods.

The surface ORK created in this process becomes the finished surface. During this process, chips are generated, but they fly to the outer periphery and do not come into contact with the finished surface.

For example, consider the moment when you are in contact with point R.

OR is the finished surface. The RK portion is still covered by the surface layer. Therefore, there is no problem even if the chips come into contact with the surface layer of the RK.

FIG. 2 shows the direction of movement of the cutting tool according to the method of the present invention.

In cutting from ○ to R-+, the circumferential speed is extremely small near the 0 point. However, since a considerable portion of this part has already been removed like OQS, cutting from point 0 is easy.

(4) Example The method of the present invention was applied to mirror cutting of oxygen-free copper with a diameter of 1.00 mm x ]-0 rnm.

The byte used is Rbyl□ (R = 1.5im
: The tip of the cutting tool is semicircular with a radius of 1. ．． 5mm),
This is a single crystal diamond bite with a rake angle of 0°.

The cutting conditions are as follows.

Spindle rotation speed 100Orpm tool feed (
Movement) Speed 5rnJMn Cutting depth
3μm The cutting edge of the cutting tool is moved from the center 0 point, from a position 5 mm away from the outer circumferential direction (0'S = 5im), along an arc locus (SQO) with a radius of 00ma, from S to O to the center. Then, it was sent toward the outer circumference (ORK).

After folding back, in the process from 0 point to the outer circumference, the point where cutting effectively starts is not 0 point but about 2 points from 0 point.
．． The points are 5 mm apart.

Since S = 5 mm, D = 3ztm, the slope of the curve y'(S) at the starting point of cutting is 1,.2 How about 4 minutes?

Through this kind of cutting, surface roughness"a 0.007μmRa shape accuracy
A mirror surface of o2 μm (measurement length 100 mm) was obtained.

Comparison mirrors that are cut in this order have no damage to the finished surface due to chips, compared to the conventional cutting process from the outer periphery to the center. This resulted in a 30% improvement in retention.

Furthermore, I tried changing the method of inserting the cutting tool tip.

When inserting the tip of the cutting tool into the zero point at the center from a distance closer to the center at an angle of 3o0, rather than from a distance along an arcuate trajectory, the tip of the cutting tool chipped with a probability of about 40%. 30° is the insertion angle at three points.

Since this is too large, chipping occurs.

In the case of the aforementioned circular arc trajectory (radius 100 mm), the probability of chipping occurring was about 5%. This is because the insertion angle is small, so there is little impact on the cutting edge of the tool.

Effect of c When ultra-precisely cutting soft metals such as Cu or Al to obtain a mirror surface, the method of the present invention prevents the cut surface from being scratched by chips.

As a result, production is delayed. This is an excellent method since there should not be even the slightest scratch.

In addition, it is possible to extend the lifespan of a part-time job.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of the vicinity of the center of the workpiece for explaining the order of movement of the cutting tool according to the present invention. FIG. 2 is a diagram showing that chips do not come into contact with the lily surface during cutting by the method of the present invention. Figure 3 is a diagram showing the possibility of chips coming into contact with the cutting surface during cutting using the conventional method. 1... Spindle 2... Work 3... ・Bye) 4... Chip application agent Patent attorney Shigeru Kawase

Claims (1)

[Claims] This is a method of cutting a copper or aluminum workpiece with ultra-precision cutting using a single-crystal diamond cutting tool to create a mirror surface for a reflecting mirror for reflecting infrared laser light. Start cutting by applying the tip of the cutting tool to the workpiece from a distant point S. First, feed the cutting tool from point S to the center point O while gradually increasing the cutting depth from 0. A mirror cutting method characterized in that the differential is set to 0, and the cutting tool is fed while maintaining a uniform cutting depth D from a center point O to a point K on the outer periphery.