JP2000198001A - Cutting tool and cutting work method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting tool capable of providing a worked surface having the uniform roughness and the shape of high accuracy by using a linear tool having an edge of the shape same as the surface shape of a workpiece when observed from the advance direction of the tool inclined at a specific angle to the advance direction of the tool. SOLUTION: A cutting tool 15 is provided with the desired shape of an edge observed from the tool advance direction P when the tool is inclined by a predetermined angle 90+θ deg. to the tool advance direction P in the cutting work of a workpiece 8 by a shaping method without turning. Concretely the contour shape projected to the cross section orthogonal to the working point focus, of the cutting edge contour 16 is formed into the elliptical shape with a circular arc of radius of curvature R of high accuracy. This cutting tool 15 is straightly moved on the workpiece 8 in the tool advance direction P while inclined by an angle 90+θ deg. to the tool advance direction to cut the workpiece 8. Whereby the worked surface can be prevented from being scratched by chips and the shape of high accuracy can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting tool and a curved surface cutting machine suitable for manufacturing, for example, a free-form lens mold or a microlens array and its mold, a mold master, a single rotationally symmetric curved mold. Related to processing method.

[0002]

2. Description of the Related Art A microlens array 1 as shown in FIG. 8, for example, is a workpiece to be formed into an axially asymmetric curved surface shape. This microlens array (workpiece) 1
Is formed by arranging a plurality of microlenses 3 having an axially asymmetric curved surface shape with curvature radii R1 and R2 on the surface to be processed 2 as shown in the AA 'sectional view and the BB' sectional view of FIG. ing.

A method of forming a plurality of such axially asymmetric curved surfaces on a surface to be processed by arranging them at arbitrary positions includes a milling method in which a cutting tool is continuously rotated to perform cutting, and a continuous rotation operation of the cutting tool. There is a mold cutting method that is not accompanied.

Among these, a milling method for performing cutting by continuously rotating a cutting tool is, for example, an X milling machine such as an NC milling machine.
A cutting device is used for continuous rotation of a cutting tool using a processing device having three linear axes that can be driven in three orthogonal directions of YZ. The cutting tool is, for example, a ball end mill or a single-cut fly. Using a rotary tool such as a cutting tool, a curved surface is formed by 2.5-dimensional or 3-dimensional cutting.

[0005] On the other hand, in the die cutting method, a curved surface is formed by 2.5-dimensional or 3-dimensional cutting using a single-cutting-edge tool having a fixed posture. FIGS. 9 (a) and 9 (b) are configuration diagrams of a processing apparatus using such a mold cutting method, where FIG. 9 (a) is a diagram viewed from above, and FIG. 9 (b) is a diagram viewed from the side. is there. A Y table 5 is provided on the X table 4 so as to be movable in the X direction, and a cutting tool 6 is mounted on the Y table 5. A workpiece 8 is attached to the Z table 7, and the workpiece 8 and the cutting tool 6 are arranged to face each other. Cutting using such a processing apparatus is XY
Each of the tables 5 to 7 of Z is moved, and the cutting tool 6 is moved.
10, the cutting tool 6 is moved to a, b,..., E in a state where the posture is fixed with respect to the workpiece 8 as shown in FIG.
At this time, the cutting is performed in a state where the posture of the cutting edge rake face 6a of the cutting tool 6 is fixed.

As a method of forming a single rotationally symmetric curved surface, there is a cutting method using a lathe.

[0007]

However, when a plurality of axially asymmetric curved surface shapes are formed on the surface to be processed, the milling method has a curved surface shape of, for example, 0.1 mm or less in diameter and a radius of curvature of the curved surface. If it is 0.1 mm or less, the rotating diameter of the tool must be 0.1 mm or less, but it is difficult to manufacture a rotating tool such as a ball end mill that satisfies this dimension.

On the other hand, in the mold cutting method, since the position of the tool cutting edge is always fixed with respect to three axes orthogonal to each other of the processing apparatus, the processing point normal on the curved processing surface and the cutting edge of the cutting tool 6 are fixed. It is not possible to keep the rake angle geometric relationship constant. For this reason, the rake angle of the tool action system is not kept constant, and the surface roughness of the machined surface varies.

In the case where a single rotationally symmetric curved surface is formed by a cutting method using a lathe, a cutting tool having an arc-shaped cutting edge is used as a cutting tool. For example, when processing a high-precision lens mold, the circular contour of the cutting edge is transferred to the processing surface, so that a single-crystal diamond tool having a circular contour accuracy of the order of 0.1 μm is used. In this case, in order to transfer the arc contour of the cutting edge to the processing surface, the cutting tool is mounted so that the rake face of the cutting tool is parallel to the tool operation plane. For this reason, the flow direction of the chips continuously generated during cutting cannot be controlled, and as a result, the chips are wrapped around the cutting edge of the cutting tool, and scratches are generated on the processing surface due to the contact of the chips.

Accordingly, an object of the present invention is to provide a cutting tool and a curved surface cutting method capable of obtaining a fixed surface roughness and processing a high-precision shape.

[0011]

According to the first aspect of the present invention, when the workpiece is inclined at a predetermined angle with respect to the tool advancing direction, the linear shape having the same edge shape as the surface shape of the workpiece viewed from the tool advancing direction. It is a cutting tool.

According to the second aspect, the cutting edge of the cutting tool according to the first aspect has a circular shape when viewed from the tool advancing direction.

According to the third aspect, the cutting tool according to the first aspect is advanced in the tool advancing direction at a predetermined angle with respect to the tool advancing direction on the workpiece to freely cut the workpiece. This is a method of cutting a curved surface.

According to a fourth aspect, the cutting tool according to the first aspect is advanced in the tool advancing direction at a predetermined angle with respect to the tool advancing direction on the workpiece, and the cutting edge rake face of the cutting tool is provided. And the normal line at the processing point of the workpiece are always maintained in a constant angular relationship, and the cutting of the free-form surface that cuts the workpiece by changing the posture of the cutting tool according to the curved surface shape that processes the cutting tool It is a processing method.

According to the fifth aspect, the cutting rake face of the cutting tool and the normal at the processing point of the workpiece are always maintained in a predetermined angular relationship, and the cutting tool is formed in accordance with the curved surface shape on which the cutting tool is processed. This is a free-form surface cutting method for cutting a workpiece by changing the posture of the workpiece.

[0016]

(1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a processing apparatus.
(a) is a front view, and (b) is a side view. X table 1
At 0, a Y table 11 is provided so as to be linearly movable in the X direction. The Y table 11 has a moving holder 12
Are provided so as to be linearly movable in the Y direction, and the workpiece 8 is held by the movable holding body 12. Further, a Z table 13 is provided.
4 are provided. The C-axis table 14 is turned by a rotation angle indexing operation around the Z-axis, and a cutting tool 15 is attached to an end face of the C-axis table 14.

When the workpiece 8 is cut by a continuous turning operation by the operation of the C-axis table 14, that is, a cutting method without turning, as shown in FIG. Predetermined angle 90 + θ °
When the tool is tilted only by a predetermined angle, the desired cutting edge shape viewed from the tool advancing direction P, that is, as shown in FIG.
The contour shape projected on the (surface) is formed in an elliptical shape that is an arc having a highly accurate radius of curvature R. Therefore, the rake face of the cutting tool 15 has an angle of 90 to the tool advancing direction P.
It is attached to the C-axis table 14 at an angle of + θ °. In this case, θ may be either positive or negative, but is adjusted so that the rake face is oriented in the previously processed direction on the workpiece. That is, when the tool is moved in a direction that intersects the cutting direction of the tool, it is desirable to carry the tool in a direction opposite to the direction in which the rake face of the tool faces with the cutting direction interposed therebetween.

The NC control device 17 uses a mold cutting method that does not operate the C-axis table 14 and does not involve the continuous rotation of the cutting tool 15. The NC control device 17 controls the X table 10, the Y table 11, and the moving holder 12. By controlling the operation, the cutting tool 15
At an angle 90+ with respect to the tool advancing direction P on the workpiece 8
The workpiece 8 is tilted by θ ° and advanced in the tool advance direction P.
Has the function of cutting.

Next, the operation of the above-configured device will be described.

The NC controller 17 stops the continuous rotation operation of the C-axis table 14, and the X table 10, the Y table 1
The cutting tool 15 is tilted by an angle of 90 + θ ° with respect to the tool advancing direction P on the workpiece 8 as shown in FIG. Then, the workpiece 8 is cut.

The NC controller 17 controls the operation of the X table 10, the Y table 11, or the movable holder 12, changes the position of the cutting tool 15, and positions the cutting tool 15 adjacent to the previously cut one. Then, the cutting tool 15 is again inclined at an angle of 90 + θ ° with respect to the tool advancing direction P on the workpiece 8 and linearly advances in the tool advancing direction P to cut the workpiece 8.

Thereafter, the workpiece 8 is cut by repeating the above-mentioned cutting.

As described above, in the first embodiment, the cutting tool 15 having an arc edge shape when viewed from the tool advancing direction P when inclined at an angle of 90 + θ ° with respect to the tool advancing direction P is used. The cutting tool 15 is inclined at the above-mentioned angle with respect to the tool advancing direction P on the workpiece 8 and is advanced in the tool advancing direction P to cut the workpiece 8. Can be controlled,
The generation of scratches on the processing surface due to chips can be prevented.

Further, since the cutting tool 15 having an elliptical cutting edge whose contour shape projected in the tool advancing direction P of the cutting tool cutting edge is a high-precision arc is used, the NC data used during machining uses The handling of the blade shape can be an arc, which simplifies NC data creation or tool diameter correction work. Therefore, the machining N
A highly accurate shape can be easily processed using C data. (2) Next, a second embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 4 is a block diagram of the processing apparatus.

The NC control unit 20 includes an X table 10, a Y table
The operation of the table 11, the movable holder 12, and the C-axis table 14 is controlled so that the cutting tool 15 is set at a predetermined angle with respect to the tool advancing direction P on the workpiece 8 in the same manner as in the first embodiment. In other words, the cutting tool 15 is inclined in the direction of the tool advancing P at an angle of 90 + θ °, and the cutting edge rake face 15a of the cutting tool 15 and the normal to the processing point Q of the workpiece 8 are always at a fixed angle as shown in FIG. Relationship, eg tool cutting rake face 1
In particular, the C-axis table 14 is set so that the angle between the normal line 5a and the processing point Q is always 0 ° (the rake angle of the tool action system is always 0 °).
Is rotated to change the attitude of the cutting tool 15 in accordance with the shape of the curved surface on which the cutting tool 15 is to be machined, thereby controlling the machining of the workpiece 8.

Next, the operation of the above-configured apparatus will be described.

The NC control device 17 has the X table 10, the Y table
The operation of the table 11, the moving holder 12, and the C-axis table 14 is controlled so that the cutting tool 15 is inclined at an angle of 90 + θ ° with respect to the tool traveling direction P on the workpiece 8 as shown in FIG. It proceeds linearly in the direction P.

With the linear movement of the cutting tool 15, NC
The control device 17 causes the C-axis table 14 to rotate,
As shown in FIG. 5, the cutting edge rake face 15a of the cutting tool 15 and the normal line at the processing point Q of the workpiece 8 are always in a fixed angular relationship, for example, the tool cutting edge rake surface 15a and the normal line of the processing point Q. The angle is always controlled to 0 °, and a curved surface shape for processing the cutting tool 15, for example, a free-form lens mold or microlens array having an axially asymmetric curved surface shape and its mold, or a mold master, a single rotation The machining of the workpiece 8 is controlled by changing the attitude of the cutting tool 15 in accordance with the shape of a curved surface such as a symmetric curved surface mold.

As described above, in the second embodiment, the angle 90+
The tool is tilted by θ ° to advance in the tool advancing direction P, and the cutting rake face 15a of the cutting tool 15 and the normal line at the machining point Q of the workpiece 8 are controlled so as to always have a constant angular relationship. Since the machining of the workpiece 8 is controlled by changing the posture of the cutting tool 15 in accordance with the curved surface shape on which the cutting tool 15 is machined, the same effects as those of the first embodiment can be obtained, and It is possible to always maintain a constant angular relationship between the cutting edge rake face 15a of 15 and the normal line of the processing point, and to maintain a constant rake angle of the working system, that is, the working system rake angle, which affects the relative attitude between the processing surface and the tool cutting edge. This makes it possible to obtain a certain surface roughness of the machined surface.

Further, the first clearance angle of the cutting edge of the cutting tool 15 can be reduced, and the cutting edge strength can be increased. (3) Next, a third embodiment of the present invention will be described with reference to the drawings. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 6 is a configuration diagram of the processing apparatus.

The cutting tool 21 is mounted on the C-axis table 14 so that the cutting edge rake face 21a is perpendicular to the tool advancing direction P as shown in FIG.

As shown in FIG. 7, the NC control device 22 always makes a constant angular relationship between the rake face 21a of the cutting tool 21 and the normal line at the processing point Q of the workpiece 8, for example, the tool cutting edge. The angle between the rake face 21a and the normal to the machining point Q is always 0
° (the rake angle of the tool action system is always 0 °), in particular, by rotating the C-axis table 14 to change the posture of the cutting tool 21 according to the curved surface shape on which the cutting tool 21 is machined. 8 has a function of controlling the cutting process.

Next, the operation of the device configured as described above will be described.

The NC control unit 22 has the X table 10, the Y table
The table 11, the moving holder 12, and the C-axis table 14 are moved so that the cutting rake face 21a of the cutting tool 15 and the normal line at the processing point Q of the workpiece 8 are always at a fixed angle as shown in FIG. The relationship, for example, the angle of the normal line between the tool cutting edge rake face 21a and the processing point Q is always controlled to 0 °, and a curved surface shape for processing the cutting tool 21, for example, a free-form lens mold having an axially asymmetric curved surface shape, The machining of the workpiece 8 is controlled by changing the attitude of the cutting tool 21 in accordance with a curved surface shape of a microlens array and its mold, a mold master, a single rotationally symmetric curved mold, or the like.

As described above, in the third embodiment, the cutting rake face 15a of the cutting tool 15 and the normal line at the machining point of the workpiece 8 are controlled so as to always have a constant angular relationship. Since the machining of the workpiece 8 is controlled by changing the posture of the cutting tool 15 in accordance with the curved surface shape on which the cutting tool 15 is machined, the cutting edge rake face 21a of the cutting tool 21 and the normal line of the machining point Q are set. It is possible to always maintain a constant angular relationship, and it is possible to keep the processing conditions, that is, the rake angle of the working system, related to the relative posture of the processing surface and the tool cutting edge, and to obtain a constant processing surface roughness. .

The present invention is not limited to the first to third embodiments, but may be modified as follows.

For example, even if the processed shape is a free-form surface, the same effect can be obtained by applying the method of the present invention. That is, in addition to the C-axis for changing the posture of the cutting tool, the A-axis for performing the rotation around the X-axis or the B-axis for performing the rotation around the Y-axis is added to change the posture of the workpiece. By doing so, it becomes possible to keep the processing conditions (the rake angle of the working system) related to the relative posture between the processing surface and the tool cutting blade constant, and it is possible to obtain a constant processing surface roughness.

[0041]

As described above in detail, according to the present invention, it is possible to provide a cutting tool and a curved surface cutting method capable of obtaining a fixed surface roughness and processing a highly accurate processed surface.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a processing apparatus to which a curved surface cutting method using a cutting tool according to the present invention is applied.

FIG. 2 is a view showing an attachment angle of a cutting tool used in the apparatus.

FIG. 3 is a view for explaining a cutting edge shape of a cutting tool used in the apparatus.

FIG. 4 is a configuration diagram showing a second embodiment of a processing apparatus to which a curved surface cutting method using a cutting tool according to the present invention is applied.

FIG. 5 is a view showing a curved surface cutting method by the same device.

FIG. 6 is a configuration diagram showing a third embodiment of a processing apparatus to which a curved surface cutting method using a cutting tool according to the present invention is applied.

FIG. 7 is a view showing a curved surface cutting method by the same device.

FIG. 8 is a diagram showing a workpiece formed by arranging a plurality of microlenses having an axially asymmetric curved surface shape.

FIG. 9 is a configuration diagram of a processing apparatus using a conventional mold cutting method.

FIG. 10 is a diagram showing a processing method using the same shaving method.

[Explanation of symbols]

 8: Workpiece, 10: X table, 11: Y table, 12: Moving holder, 13: Z table, 14: C-axis table, 15: Cutting tool, 16: Cutting edge contour, 17, 20, 22: NC control device, 21: cutting tool.

Claims (5)

[Claims] 1. A linear cutting tool having a cutting edge shape that is the same as the surface shape of a workpiece viewed from the tool traveling direction when inclined at a predetermined angle with respect to the tool traveling direction. 2. The cutting edge shape of the cutting tool according to claim 1,
A cutting tool having a circular shape as viewed from the tool advancing direction. 3. The cutting tool according to claim 1, wherein the cutting tool is inclined at a predetermined angle with respect to a tool advancing direction on the workpiece and advances in the tool advancing direction to cut the workpiece. Free-form surface cutting method. 4. The cutting tool according to claim 1, wherein the cutting tool is inclined at a predetermined angle with respect to the tool advancing direction on the workpiece and is advanced in the tool advancing direction, and the cutting rake face of the cutting tool and the workpiece are machined. The method always cuts the workpiece by changing the posture of the cutting tool according to the curved surface shape on which the cutting tool is machined, while always maintaining a constant angle relationship with the normal line at the processing point of the object. Free-form surface cutting method. 5. A cutting blade rake face of a cutting tool and a normal line at a processing point of a workpiece are always maintained in a predetermined angular relationship, and the posture of the cutting tool is changed according to a curved surface shape for processing the cutting tool. A method for cutting a curved surface of a free-form surface, the method comprising cutting the workpiece by changing.