JPH0132030B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for generating a paraboloid of revolution, and its purpose is to use a single-point tool so that the cutting edge of the tool contacts the workpiece generating surface in a line, and The object of the present invention is to efficiently create a highly accurate paraboloid of revolution without leaving any uncut parts on the surface, especially at the center of rotation of the workpiece.

Conventionally, in order to create a paraboloid of revolution, a workpiece W is attached to the end face of a spindle 2 and a spindle device 1 for rotating it at high speed is provided so as to be movable in the axis direction of the spindle, as shown in FIG. It is fixed on a slide table 4 that can move in a direction perpendicular to the spindle axis, and the slide table 4 and spindle device 1 are fed by numerical control so that the cutting edge draws a predetermined parabola to form a paraboloid of rotation. There is something to create.

In such a conventional device, the cutting speed becomes zero at the center of rotation of the workpiece, so cutting cannot be performed, resulting in uncut parts. Furthermore, since the cutting edge of the cutting tool cannot be aligned with the normal direction of the curved surface within the cutting range, the position of the cutting edge changes, making it difficult to improve the surface roughness.

In order to eliminate such conventional drawbacks, the present invention has the following features:
The tool rotation radius r is changed according to the rotation angle θ of the tool, and the tool cutting edge is rotated to draw a parabola within the range of the workpiece diameter, thereby creating a paraboloid of revolution.

In Figure 2, if the parabola is Z=x ² /4α α: focal length, the rotation angle θ and the tool rotation radius r are However, when θ=0, the relationship r=ro holds.

With this relationship, the rotation angle θ and rotation radius r of the tool
If you control this, the tool tip will rotate in a parabola, and if you rotate it in a parabola within the range of the workpiece diameter and rotate the workpiece at a low speed around the Z axis, the workpiece surface will have a rotating paraboloid. A surface Z=1/4α(x ² +y ² ) is created.

Here, the above equation (1) can be derived as follows.

In Figure 2, parabola Z=x ² /4α ...(2) If the coordinates of any point P are (X, Z), then from =r x=rsinθ z=ro−rcosθ Substitute into equation (2) Then, the above equation (1) is obtained.

Furthermore, if θ=0, then r=ro from equation (3).

An embodiment of a processing device to which the principle of creating a paraboloid of revolution is applied is shown in FIGS. 3 and 4. In FIG. 3, 10 is a bed, 11 is a workpiece support device, and the workpiece support device 11 includes a headstock 12 and a rotating spindle 13 that is rotatably supported on the headstock 12 and has a chuck 14 at one end that supports the workpiece W. The work supporting device 11 is provided on a cutting table 16 so as to be movable in a direction parallel to the axis of the rotating main shaft 13. ing. This cutting table 16 is provided with a cutting device 17 .
20 is a column erected on the bed 10, 21 is a tool headstock fixed to the side of the column 20, 22
is a rotating spindle rotatably supported on the tool headstock 21,
It has a rotation axis perpendicular to the rotation axis of the workpiece. A tool 23 is provided at one end of the rotating main shaft 22 to protrude in the radial direction, and rotates within a plane that includes the workpiece rotation axis. The tool 23 is provided so as to be movable in the radial direction relative to the main shaft 22, and a rotation radius adjustment mechanism for this tool is provided within the main shaft. As shown in FIG. 4, this adjustment mechanism has a sliding shaft 25 that is inserted into a through hole 22a protruding from the center of the tool spindle 22 and is allowed to move only in the axial direction, and one end of this sliding shaft 25. An inclined surface 25a that is inclined with respect to the axis is formed on the radially inner end 2 of the tool 23.
3a is pressed against this inclined surface 2 by the pressing force of the spring 27.
It abuts and engages with 5a. The other end of the sliding shaft 25 is projected to the outside of the main shaft 22, and is guided by a support cylinder 26 fixed to the tool headstock 21 so as to be slidable in the axial direction, and is prevented from rotating by a sliding member 27 that is prevented from rotating. They are allowed to move together in the axial direction. A female threaded member 28 is fixed to the sliding member 27, and a male threaded member 29 that is screwed into the female threaded member 28 is supported by a holder 30 protruding from the column 20 so that only rotation is allowed, and the rotation angle and rotation speed are controlled. It is connected to a servo motor 31 that can be controlled arbitrarily. By controlling the rotation of this servo motor 31, the sliding member 27 and the sliding shaft 25 can be moved in the axial direction by screw action, and the tool 23 can be moved in the radial direction along the inclined surface 25a.
The rotation radius of the tool cutting edge can be adjusted arbitrarily. The tool spindle 22 is supported by bearings 35, 35 on the tool spindle stock 21, and supports radial and thrust loads. A drive gear 36 is fixed to the outer periphery of the tool spindle 22 and meshes with a pinion 38 provided on an output shaft 37a of a servo motor 37 fixed to the headstock 21. Servo motor 3
1 and 37 are connected to the numerical control device 40 and are controlled by the control commands output from the numerical control device 40 as described in (1) above.
The rotation is controlled according to the relationship shown in the following equation, and the cutting edge of the tool is rotated in a parabolic manner within the diameter range of the workpiece, as shown in FIG. Note that outside the workpiece diameter range, it is sufficient to keep the rotation radius of the tool constant and perform circular motion.

By calculating the above formula (1) with an electronic computer,
Although several pairs of θ and r are determined, the number of pairs to be determined may be increased or decreased depending on the required accuracy. Two-dimensional pulse distribution is performed by the numerical control device 40 by connecting a large number of points determined by the obtained θ and r with a straight line or circular arc to form one broken line or curve. The point group data of θ and r in this case is programmed in advance and stored in the storage device 41 within the numerical control device 40. Out of the simultaneous two-axis pulse train output from the numerical control device 40, one axis is applied to the servo motor 37 to rotate the tool spindle 22, and the other axis is applied to the servo motor 31 to move the tool 23 in the radial direction. A desired paraboloid of rotation can be created by controlling the cutting edge to rotate in a parabolic manner and rotating the workpiece W at a low speed while applying a predetermined cut using the cutting device 17.

Note that the servo motor 37 for driving the main shaft does not have to be rotated by a pulse command output from the numerical control device 40, but can also be rotated by a normal motor. In this case, a position coder or encoder is provided to detect the rotation angle of the rotating main shaft, and a rotation angle signal detected by the encoder is provided to the numerical control device 40 to issue a control command for the rotation radius r corresponding to the rotation angle θ. It outputs to the servo motor 31.

According to the present invention, a single-point tool is rotated, the tool rotation radius is controlled according to the spindle rotation angle to impart parabolic rotation to the tool cutting edge, and the workpiece is rotated at a low speed to create a rotation paraboloid. Since the cutting edge of the tool is in linear contact with the workpiece creation surface, and the tool can be aligned in the normal direction of the curved surface, the contact point of the cutting edge does not change and the surface roughness can be lowered. Moreover, since no uncut parts are left at the center of rotation of the workpiece, it is possible to create a paraboloid of revolution with high precision and high efficiency, which cannot be obtained with conventional equipment.

[Brief explanation of drawings]

Fig. 1 is a plan view of a conventional processing device, Fig. 2 is an explanatory diagram of the principle of parabola generation at the cutting edge of a tool, Fig. 3 and the following show an embodiment of the present invention, and Fig. 3 is an overall front view of the processing device. 4 is a longitudinal cross-sectional view of the tool head stock, and FIG. 5 is a view taken in the direction of arrow A in FIG. 3. 11... Work support device, 16... Cutting table,
21... Tool headstock, 22... Rotating spindle, 23...
...Tool, 25...Sliding shaft, 25a...Slope, 2
7...Sliding body, 28...Female thread member, 29...Male thread member, 31, 37...Servo motor, 40...
...Numerical control device.

Claims (1)

[Scope of Claims] 1. A workpiece support device that supports and rotates a workpiece in which a paraboloid of rotation is formed, and a rotational spindle supported on a tool headstock so as to be rotatable about an axis perpendicular to the rotational axis of the workpiece. a tool position adjusting means within the rotary spindle for adjusting the position of a cutting tool supported by the rotary spindle and rotating in a plane passing through the workpiece rotation axis in the radial direction of the rotary spindle; and a control command unit rotatably connected to the rotary spindle. A device for creating a paraboloid of revolution, comprising a first servo motor that operates in response to a control command, and a second servo motor that is connected to the tool position adjustment means and operates in response to a control command. Assuming that the focal length of the surface is α, the first
The rotation angle θ of the rotating main shaft by the servo motor and the rotation radius r of the cutting tool by the second servo motor.
and However, when θ=0, a numerical control device that controls the rotation angle of the rotating main shaft by the first servo motor and the radial position of the cutting tool by the second servo motor in a related manner so as to maintain the relationship r=r0. A paraboloid of revolution creation processing device characterized by comprising: 2. The tool position adjustment means includes a sliding shaft that is slidably guided to the center of the rotating main shaft, a motion conversion mechanism that moves the cutting tool in the radial direction according to the axial movement of the sliding shaft, and The screw mechanism according to claim 1, further comprising a screw mechanism that allows rotation with a moving shaft, is integrally connected in the axial direction, and converts the rotational input from the second servo motor into an axial movement displacement. Paraboloid of revolution creation processing device.