JPH0132028B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device for creating a paraboloid of revolution by cutting, and its purpose is to use a single-point cutting tool so that the cutting edge of the cutting tool contacts the workpiece creation surface in a line and To generate a highly accurate paraboloid of revolution with high efficiency without leaving any uncut parts on the workpiece generating surface, especially at the center of rotation of the workpiece.

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

In such a conventional device, the cutting speed becomes 0 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:
This is a processing device that creates a rotating paraboloid by rotating a cutting tool.The cutting edge of the cutting tool moves in a circular motion, and in synchronization with the rotation angle of the cutting tool, the work rotation axis swings in a plane parallel to the rotation plane of the cutting tool. , the cutting edge is controlled so that it draws a parabola on the workpiece creation surface.

Figure 2 shows the principle of parabola creation.

Oc is the rotation center of the cutting tool Ow is the swing center of the workpiece P is the cutting edge of the cutting tool θ is the rotation angle of the cutting tool Θ is the swinging angle of the workpiece around Ow α is the focal length = D, = l, = d/2 Then, sinβ=dsinθ/2l, cosβ=D-d/2cosθ/l If the coordinates of point Q on the parabola in the X, Y coordinate system are x, y, then x=sin(β-Θ) =l{sinβcosΘ −cosβsinΘ} =d/2sin(θ+Θ)−Dsinθ……(1) y=cos(β−Θ)−(D−1/2) =d/2−D+l{cosθcosΘ+sinβsinΘ} =d/2−D+DcosΘ−d /2cos(θ+Θ)...(2) However, since there is a relationship of y=x ² /4α, substituting the previous equations (1) and (2) into this, DcosΘ-d/2cos(θ+Θ)+d/2-D = 1/4α {d/2sin (θ+Θ)−DsinΘ} ² ...(3) If the tool rotation angle θ and workpiece swing angle Θ are controlled to maintain the relationship in equation (3) above, a parabola with focal length α is created. be done. In this way, when the workpiece is rotated 180 degrees at low speed with the cutting edge drawing a parabola on the workpiece creation surface, a paraboloid of rotation is created on the workpiece.

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.

10 is a bed, 11 is a tool support device, and this tool support device 11 is connected to a headstock 13 that rotatably supports a spindle 12 around a horizontal axis, and to the spindle 12, and can control the rotation angle and rotation speed in response to a rotation command. The tool shaft 16 includes a rotary motor 14, and a tool shaft 16 having a single point diamond cutting tool 15 fixed to the tip of the main shaft 12 and protruding in the radial direction. The headstock 13 is vertically slidably guided by a column 17 erected on the bed 10, and connected via a feed screw to a cutting means 18 for controlling the depth of cut. Headstock 1
It is fixed on 3. Reference numeral 20 denotes a work supporting device, which has a rotary table 21 having a rotation axis perpendicular to the axis of the main shaft 12, and a surface of the rotary table 21 that is perpendicular to the rotation axis and parallel to the rotation plane of the cutting tool 15. It is rotatably supported on a rocking table 25 that can swing within the shaft. 22 is a drive motor that drives this rotary table 21, and rotates the rotary table 21 at a relatively low speed via a reduction gear. 26 is a servo motor that swings the swing table 25.

Reference numeral 30 denotes a numerical control device that controls the rotary motor 14 and the servo motor 26 by sending out command pulses to maintain the correlation expressed by equation (3).

By calculating the above formula (3) with an electronic computer,
Several pairs of θ and Θ are determined, but the number of pairs to be determined can be increased or decreased depending on the required accuracy, and a large number of points determined by the determined θ and Θ can be connected with a straight line or an arc to form one. The numerical control device 30 performs two-dimensional pulse distribution as a broken line or curve. In this case, the point group data of θ and Θ are programmed in advance and stored in the storage device 31 built into the numerical control device 30. One axis of the simultaneous two-axis pulse train outputted from the numerical control device 30 is connected to the rotary motor 14.
is applied to rotate the tool axis 16, and the other axis is applied to the servo motor 26 to swing the workpiece support device 20, controlling the cutting edge so that it draws a parabola on the creation surface of the workpiece, and rotating the rotary table 21. A desired paraboloid of revolution can be created by rotating at low speed.

Note that the rotary motor 14 does not have to be rotated by a pulse command output from the numerical control device 30, 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 tool axis, and the detected rotation angle signal is given to the numerical control device 30 to command the swing angle Θ corresponding to the rotation angle θ. is output to the servo motor 26.

Further, in the embodiment described above, the swinging angle Θ is given to the swinging table 25 having the workpiece support device 20.
This swing angle Θ may be given as a relative movement between the cutting tool and the workpiece, and it is also effective to provide a swing table having a tool support device 11 and give the swing angle Θ to this. Further, a workpiece support device 20 and a tool support device 1
It is also effective to provide both of 1 so as to be swingable, and to provide the swing angle Θ as a composite movement of the swing movements of both. When the swing angle Θ is given as a composite motion of the swing motion of both, the swing angle of each swing table can be halved by swinging both in opposite directions, and the unit rotation angle of the cutting tool is It is possible to improve the responsiveness of the rocking motion to the

According to the present invention, by rotating a single-point cutting tool and swinging the workpiece side according to the rotation angle of the cutting tool, the cutting edge of the cutting tool draws a parabola on the workpiece creation surface, and is rotated by slow rotation of the workpiece. Since it creates a parabolic surface, the cutting edge of the cutting tool contacts the workpiece creation surface in a line, and since the cutting 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 is reduced. Moreover, since no uncut parts are left at the center of rotation of the workpiece, it is possible to create and efficiently create a paraboloid of revolution with high precision, which cannot be obtained with conventional equipment.

[Brief explanation of drawings]

FIG. 1 is a plan view of a conventional device, FIG. 2 is a diagram of the principle of parabola creation, and FIGS. 3 and 4 are a front view and a right side view of a processing device showing an embodiment of the present invention. 11... Tool support device, 12... Spindle, 13...
... Headstock, 14 ... Rotating motor, 15 ... Bit, 16 ... Tool shaft, 20 ... Work support device,
21...Rotary table, 22...Drive motor, 2
5... Rocking table, 26... Servo motor, 30...
Numerical control device.

Claims (1)

[Scope of Claims] 1. A work support device that rotatably supports a workpiece in which a paraboloid of rotation is formed, a tool support device that rotates a cutting tool around an axis perpendicular to the rotational axis of the workpiece, and the workpiece support device. Machining for cutting a rotating paraboloid having a device and a swinging means that swings and displaces the tool support device relative to one point on the workpiece rotation axis in a plane parallel to the rotating plane of the cutting edge of the cutting tool. For the device, when the focal length α of the paraboloid of revolution, the rotational diameter d of the cutting tool, and the distance D between the rotation center of the cutting tool and the center of swing are given, the rotation angle θ of the tool and the swing angle Θ are given. DcosΘ−d/2cos(θ+Θ)+d/2−D=1/4α{
d/2sin(θ+Θ)−DsinΘ} ² The invention is characterized by comprising a numerical control device that controls the rotation angle of the cutting tool and the relative swinging angle of the cutting tool and the work by the swinging means so as to maintain the relationship: d/2sin(θ+Θ)−DsinΘ}2 Rotating paraboloid cutting equipment. 2. The paraboloid of revolution cutting apparatus according to claim 1, wherein the swinging means includes a workpiece support device swinging means for swingingly displacing the workpiece support device. 3. The paraboloid of revolution cutting apparatus according to claim 1, wherein the swinging means includes a tool support swinging means that swings and displaces the tool support device. 4. Claim 1, characterized in that the swinging means includes a swinging means for swinging each of the workpiece support device and the tool support device simultaneously about the same swing center and in mutually opposite directions. The paraboloid of revolution cutting device described above.