JPH0739042B2 - Curved surface forming method - Google Patents

Description

The present invention relates to a curved surface forming method.

[Background of the Invention]

Conventionally, as a curved surface cutting device, machine research, No. 35
Vol. 1, No. 1 (1983) pp. 179-185, with the work piece mounted on the end face of the rotating spindle, as discussed in the article by Hiroshi Suzuki entitled "Current State of Ultra-Precision Removal Machines and Their Utilization". There is a lathe method in which a workpiece and a cutting tool are relatively moved in the axial direction of the rotary spindle and in a direction orthogonal to the rotary spindle while rotating at a high speed to perform cutting of a curved surface.

However, in such a curved surface cutting apparatus, the size of the apparatus becomes extremely large when processing a workpiece having a large outer diameter, and the cutting speed becomes zero at the rotation center of the workpiece, When cutting is impossible, uncut residue occurs, and when processing non-axisymmetric curved surfaces other than the rotationally axisymmetric curved surface, it is necessary to mount the work piece away from the axis of the rotary spindle, and If the radius of curvature of the axisymmetric curved surface is large, the distance between the axis of the rotating main shaft and the surface of the workpiece to be machined must be increased, and the scale of the apparatus is significantly increased.

FIG. 4 shows another conventional curved surface cutting machine (Japanese Patent Laid-Open No. 60-52201).
No.) principle explanatory diagram. In the figure, 1 is a work piece, 2 is a work surface of a work piece, 3 is a cutting tool, the cutting tool 3 is attached to a rotary spindle (not shown), and the cutting tool 3 is a feeding device. By (not shown), the workpiece 1 is moved relative to the cutting direction, that is, the direction perpendicular to the z direction, that is, the x direction and the z direction. 4 is a micro displacement device of the cutting tool 3, 5 is a diamond tool attached to the end of the displacement device 4, and the displacement device 4 uses the electrostrictive effect of the piezo element, and a plurality of piezo elements are laminated. However, when the voltage applied to the displacement device 4 is changed, the position of the tip of the cutting tool 5 in the z direction is displaced by the amount of deformation of the displacement device 4. Also, a rotates the cutting tool 3,
The locus of the tip of the cutting tool 5 when no voltage is applied to the displacement device 4, C is the center point of the locus a, b is the movement locus of the center point C, and the movement locus b is substantially parallel to the work surface 2. It is set arbitrarily.

Here, the movement amount of the center point C in the x direction is X, and the center point C is z.
The moving amount in the direction is Z = u (X), the distance between the center point C and the tip of the cutting tool 5, that is, the turning radius of the cutting tool 3 is r, and the trajectory a
When the angle formed by the line connecting the upper point P and the center point C and the y direction orthogonal to the x direction and the z direction, that is, the rotation angle of the cutting tool 3 is α, the position of the point P is calculated by the following equation. .

x = X + r sinα y = r cosα (1) z = u (X) The function of the curved surface to be cut is expressed by the following equation.

ξ = f (x, y) (2) Since the turning radius r is constant in the equation (1), the equation (2) can be rewritten as the following equation.

ξ = g ₁ (X, α) (3) Therefore, the deformation amount of the displacement device 4 required for processing the curved surface represented by the equation (3), that is, the displacement amount S _{1 at} the tip position of the cutting tool 5 is Given in.

_{S 1 = ξ-z = g} 1 (X, α) -u (X) (4) Thus, the cutting tool 3 is rotated by a rotary spindle, cutting such that the center point C by a feeding device passes over the moving locus b By moving the tool 3 and changing the displacement amount S _{1 according} to the position of the cutting tool 5 with respect to the workpiece 1, that is, the movement amount X and the rotation angle α, it is possible to cut a curved surface of an arbitrary shape. Moreover, even if the outer diameter of the work piece 1 is large, or if the work surface 2 is a non-axisymmetric curved surface and has a large radius of curvature, the size of the device does not increase, and there is no uncut portion.

However, when the radius of curvature of the surface to be processed 2 in the cross section perpendicular to the x direction of the workpiece 1, that is, the radius of curvature of the yz plane, decreases, the maximum displacement amount S _1max increases, whereas
Since the maximum deformation amount of the displacement device 4 is at most several tens of μm, when the yz plane curvature radius is small, the curved surface cannot be cut.

[Object of the Invention]

The present invention has been made to solve the above problems, and an object of the present invention is to provide a curved surface forming method capable of cutting a curved surface regardless of the radius of curvature.

[Outline of Invention]

The gist of the present invention is to rotate a cutting tool having a cutting piece attached via a displacement means, to relatively move the cutting tool and a workpiece in a direction perpendicular to the cutting direction, and to position the tip of the cutting piece. Is displaced in the direction parallel to the rotation main axis of the cutting tool according to the relative positional relationship between the cutting piece and the workpiece by the displacement means, and the surface of the workpiece is cut by the cutting piece. By performing a curved surface forming method for forming a desired curved surface, the cutting tool is rotated by tilting the rotary spindle of the cutting tool at a predetermined angle with respect to the cutting direction to perform the cutting process. The method for forming a curved surface is characterized in that

Example of Invention

FIG. 1 is an explanatory view of the principle of the curved surface forming method according to the present invention. In the figure, 1 is the axis of the rotary spindle of the cutting tool 3,
The axis l lies in the xz plane, and the axis l is inclined with respect to the z direction, that is, the cutting direction. Therefore, the shape of the locus a when viewed from the x direction is an ellipse.

Here, when the inclination angle of the axis l with respect to the z direction is θ, the position of the point P is expressed by the following equation.

x = X + r cos θsinα y = r cosα (5) z = u (X) + r sin θsinα Since the radius of gyration r and the inclination angle θ are constant in equation (5), the function of the curved surface to be cut is as follows. Represented by.

ξ = g (X, α) (6) Therefore, the displacement amount S for processing the curved surface represented by the equation (6) is given by the following equation.

S = ξ−z = g (X, α) −u (X) −r sin θsinα (7) Therefore, the cutting tool 3 is rotated by the rotary spindle, and the center point C is moved by the feeding device on the movement locus b. While moving the cutting tool 3, the tip end position of the cutting tool 5 is displaced by the displacement device 4 in a direction parallel to the axis l of the rotary spindle of the cutting tool 3, and the displacement amount S is calculated based on the equation (7), that is, the movement amount. By changing X and rotation angle α,
A curved surface of any shape can be cut. Since the shape of the locus a viewed from the x direction is elliptical, the maximum displacement amount S _max can be made extremely small by setting the inclination angle θ according to the yz plane curvature radius of the curved surface to be cut. Therefore, even if the radius of curvature of the yz plane is small, the curved surface can be cut.

FIG. 2 is a view showing a curved surface cutting apparatus for carrying out the curved surface forming method according to the present invention. In the figure, 6 is a chuck for fixing the workpiece 1, 7 is a guide provided in the x direction, 8 is an x table guided by the guide 7,
9 is a feed screw for moving the x table 8 in the x direction,
Reference numeral 10 is a motor for rotating the feed screw 9, and the x table 8, the motor 9 and the like constitute a feed device in the x direction. 11 is a z-table mounted on the x-table 8 so as to be movable in the z-direction, and 12 is a drive device for moving the z-table 11 in the z-direction.
The z-table 11 and the driving device 12 constitute a z-direction feeding device. 13 is a rotating device for rotating the cutting tool 3,
The rotating device 13 is composed of a rotary spindle to which the cutting tool 3 is attached, a precision rotary bearing that supports the rotary spindle, and a motor that drives the rotary spindle. The rotary device 13 is a z-table that is rotatable in the xz plane. It is attached to the z-table 11 and can be fixed to the z-table 11 by a means such as a vacuum suction device or an electromagnetic chuck after being rotated by a predetermined angle. 14 is a position detector that detects the amount X of movement of the center point C in the x direction, 15 is a rotary encoder that detects the rotation angle α of the cutting tool 3, 16 is a computer, 17 is a computer 16
An operation panel connected to the computer 16, a memory connected to the computer 16, a numerical control device 19 connected to the computer 16, and the numerical control device 19 is also connected to the position detector 14 and the rotary encoder 15. 20 is a driver for inputting a signal of the numerical control device 19 and applying a voltage corresponding to the signal to the driving device 12, and 21 is for inputting a signal of the numerical control device 19 and outputting a voltage according to the signal Driver, 22 is driver
It is a slip ring for transmitting the voltage output from 21 to the displacement device 4.

Next, a method of processing a curved surface with this curved surface cutting device will be described. First, the rotating device 13 is tilted and fixed to the z table 11. Next, data such as the functions g (X, α), u (X), the tilt angle θ, and the turning radius r are input to the computer 16 by the operation panel 17, and the computer 16 calculates the movement amount Z and the displacement amount S in advance. Then, the value is stored in the memory 18. Then, the cutting tool 3 is rotated by the rotating device 13.
While rotating at a constant rotation speed (600 ~ 4000 rpm),
The cutting tool 3 is moved in the x direction at a constant speed by the feeding device in the x direction. In this case, the position detector 14 detects the movement amount X, the movement amount X is input to the numerical control device 19, and the rotary encoder 15 detects the rotation angle α, and the rotation angle α is also detected by the numerical control device 19. Input, movement amount X,
The movement amount Z and the displacement amount S corresponding to the rotation angle α are called from the memory 18, and the numerical control device 19 outputs the movement amount Z and the displacement amount S. Then, the voltage corresponding to the movement amount Z is set by the driver 20.
V _Z is output and the cutting tool 3 is supplied with voltage by the z-direction feed device.
It is moved in the z direction according to V _Z, and the voltage V _S corresponding to the displacement amount _S is output by the driver 21, and the voltage V _S is applied to the displacement device 4 via the slip ring 22 to cause the displacement device 4 to move. It deforms according to the voltage V _S. Therefore, the curved surface is cut on the workpiece 1.

In this embodiment, the diamond bite 5 is used as the cutting piece, but other cutting pieces may be used. Further, in this embodiment, the minute displacement device 4 is used as the displacement device, but another displacement device may be used. Furthermore, although the cutting tool 3 is moved in the x direction and the z direction in this embodiment, the workpiece 1 may be moved in the x direction and the z direction. Further, although the cutting tool 3 is moved in the x direction and the z direction in this embodiment, the cutting tool 3 may be moved only in the x direction. For example, when cutting a cylindrical surface, the inclination angle θ is determined according to the radius of curvature of the cylindrical surface, the cutting tool 3 is moved only in the x direction, and the locus a and the arc shape viewed from the x direction are obtained. The displacement amount S may be changed according to the rotation angle α by the amount of difference. Further, in this embodiment, the axis l is tilted in the xz plane, but the axis l may be tilted with respect to the xz plane, that is, the axis l may be tilted with respect to the z direction. Further, although the case where the concave curved surface is cut is described in this embodiment, the present invention can be applied to the case where the convex curved surface is cut. Further, in this embodiment, the displacement amount S is obtained by the equation (7), but if the displacement amount S is obtained by the following equation, the curved surface can be cut more accurately.

S = {g (X, α) −u (X) −r sin θ sin α} / cos θ Further, in this embodiment, the case where the movement amount Z and the displacement amount S are controlled by the open loop is explained. If the closed loop control is performed using the technique, it is possible to perform more accurate cutting. Further, in this embodiment, the case where the memory 18 is provided outside the computer 16 and the movement amount Z and the displacement amount S are controlled using the data calculated in advance has been described. However, the movement amount X and the rotation angle α are detected. It is also possible to calculate the amount of movement Z and the amount of displacement S based on the signals and use the results to control in real time.

FIG. 3 is a boundary diagram showing a range in which a cylindrical surface can be cut. With the conventional lathe method, the radius of curvature that can be processed is 10 ³ mm or less even with the world's largest processing device (areas I and II).
Nothing more. Further, in the processing apparatus described in JP-A-60-52201, when the turning radius of the cutting tool is 100 mm and the maximum displacement of the displacement device is 10 μm, the workable radius of curvature is 5 × 10 ⁵ mm or more ( Limited to Region III). On the other hand, in the curved surface forming method according to the present invention, the turning radius of the cutting tool is 100 mm and the maximum deformation amount of the displacement device is 10 μm.
And the radius of curvature is 10 ² to 10 ⁶ mm (regions II to IV)
It is possible to cut a wide range of cylindrical surfaces.

〔The invention's effect〕

According to the present invention, desired curved surface cutting can be performed even when the displacement amount of the displacement means provided in the cutting tool is small and the radius of curvature of the curved surface to be processed is small.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the curved surface forming method according to the present invention, FIG. 2 is a view showing a curved surface cutting apparatus for carrying out the curved surface forming method according to the present invention, and FIG. FIG. 4 is a boundary diagram showing the range, and FIG. 4 is a principle explanatory diagram of a conventional curved surface cutting apparatus. 1 ... Workpiece, 2 ... Work surface 3 ... Cutting tool, 4 ... Micro displacement device 5 ... Diamond tool 13 ... Rotating device

Claims (1)

[Claims] 1. A cutting tool having a cutting piece attached thereto via a displacement means is rotated to relatively move the cutting tool and a workpiece in a direction perpendicular to a cutting direction, and a tip position of the cutting piece is moved. By the displacement means, the cutting piece is displaced in a direction parallel to the rotation main axis of the cutting tool in accordance with the relative positional relationship between the cutting piece and the workpiece, and the surface of the workpiece is cut by the cutting piece. By this, in a curved surface forming method for forming a desired curved surface, the cutting tool is rotated in a state in which the rotary spindle of the cutting tool is inclined by a required angle with respect to the cutting direction to perform the cutting process. A method for forming a curved surface, characterized in that the method is performed.