JP2002321102A - Method for elliptic cutting of work piece using lathe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technological means by which elliptic cutting of external and internal peripheries of a work piece can be efficiently and accurately carried out using a lathe. SOLUTION: The employed lathe has a main spindle the angular position of which can be fixed at a required position, and a rotary tool spindle 10 mounted on a tool post 5 so that a swivel angle of the rotary tool spindle 10 about the Y-axis is adjustable. When elliptic cutting of an external periphery is carried out, blades 11 which rotate about the axis of the rotary tool spindle and have a cutting edge directed inward are attached to the rotary tool spindle, the main spindle is fixed, the rotary tool spindle is fixed at such angular position that the axes of the rotary tool spindle and the main spindle intersect, and then the tool post 5 is fed in the Z-axis direction while the rotary tool spindle is rotating. When elliptic cutting for an internal periphery is carried out, blades 12 which rotate about the axis of the rotary tool spindle and have a cutting edge directed outward are attached to the rotary tool spindle. Because the cutting edge traces a circle on a plane intersecting the axis of the main spindle, the work piece is machined to produce an ellipse. Machining of high productivity is possible by employing a milling cutter having a plurality of throw-away tips on a periphery of the cutter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for performing elliptical processing on an outer periphery or an inner periphery of a work held on a spindle by using a lathe.

[0002]

2. Description of the Related Art Conventionally, when a lathe is used to form an elliptical shape on the outer periphery or inner periphery of a work, as shown in FIGS. 6 and 7, a tool post having a rotary tool shaft in a Z-axis direction (a main axis direction). The rotary tool shaft is mounted with a straight end mill 15 and the tool rest 16 is reciprocated twice in the X-axis direction (cutting feed direction) in synchronization with the rotation of the main spindle for one rotation of the main spindle. The reciprocating motion of the tool rest is controlled by the NC device, but it is necessary to perform reciprocating motion with smooth acceleration / deceleration such as simple vibration.

In machining pistons of internal combustion engines, etc.,
It is required that the cross section be processed into a slightly elliptical cross section. This takes into account that the thermal deformation becomes non-uniform due to the positional relationship between the adjacent cylinders and the heat radiating device during the operation of the internal combustion engine, and that the cylinder cross section deviates from a perfect circle. Since the piston is heated substantially uniformly in the circumferential direction as compared with the cylinder, it is required to process the cross section of the piston to a shape deviated from a perfect circle in accordance with the cross section of the cylinder during operation.

[0004]

However, in the conventional machining method using a straight end mill, the reciprocating motion of the tool post is controlled by the NC device, so that the machining program of the NC device is complicated to obtain an accurate machining shape. Since programming takes time and the tool escapes (bends) due to the cutting reaction force, errors occur in the cross-sectional shape and radial dimension in the axial direction of the work, resulting in poor machining accuracy and easy vibration of the tool. However, there is a problem in that the processing speed and productivity are low, for example, it is not possible to increase the feed speed of the blade, and it takes a long processing time to further increase the surface accuracy.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a technical means capable of performing accurate elliptical machining with high efficiency and high surface accuracy.

[0006]

According to a method for machining an ellipse of a workpiece according to the present invention, a main shaft capable of fixing a rotation angle at a predetermined position is provided, and a position in an X-axis direction (a direction perpendicular to the main axis) and a Z-axis direction (a main axis direction) are provided. A lathe having a rotary tool shaft 10 capable of controlling the deflection angle around the Y-axis is used on a tool rest 5 capable of controlling the rotation angle. When performing elliptical machining on the outer periphery of the workpiece, the rotary tool shaft 10
A cutting tool 11 having a cutting edge 11c having an inward cutting edge that rotates around the tool axis is mounted on the tool, and the main shaft holding the work is fixed, and the direction of the axis of the rotary tool shaft 10 intersects with the main shaft axis. In this state, the tool rest 5 is fed in the Z-axis direction while rotating the rotary tool shaft 10 to perform machining.

When performing elliptical machining on the inner periphery of a work, a lathe having the above-described structure is used, and a rotary tool shaft 10 has a cutting edge 12 having an outwardly directed cutting edge which rotates around the tool axis.
c, the main spindle holding the workpiece is fixed, the direction of the axis of the rotary tool shaft 10 is fixed in a direction intersecting the main axis, and the tool rest 5 is rotated while the rotary tool axis 10 is rotated. Is moved in the Z-axis direction to perform processing.

[0008] As the cutting blades 11c and 12c, when processing an accurate ellipse, a cutting blade having a sharp cutting edge is used. When it is desired to efficiently process an ellipse having a high surface accuracy, a cutting blade having an arc-shaped cutting edge can be used. When using a cutting edge with an arc-shaped cutting edge, the minor diameter of the ellipse to be machined is slightly shorter in outer machining, and slightly longer in inner machining, but when the intersection angle between the rotary tool axis and the main spindle is small. Is negligible.

As shown in the illustrated embodiment, the cutting blades 11c and 12c are more productive by using a milling cutter having a plurality of indexable inserts on a circumference centered on the axis of the rotary tool shaft 10. High processing can be performed.

[0010]

FIG. 5 is a perspective view showing an example of a lathe used in the present invention. The figure shows the Z axis, X
The directions of the axis and the Y axis are shown. The arrangement of the bed 1, the headstock 2, the spindle 3, and the tool rest 5 is the same as that of a general lathe, and the tool rest 5 can be moved and positioned in the Z-axis and X-axis directions.

The tool rest 5 has a U-shaped bracket 7 in a side view, and a tool driving device 9 is supported by upper and lower turning shafts 8 provided on the bracket 7 so as to fit between the U-shaped brackets. Has been installed. The turning shaft 8 is provided in a direction orthogonal to the Z axis and the X axis, that is, in the Y axis direction.
The lower turning shaft, which is not shown in the drawing, is fixed to the tool driving device 9 and is rotatably supported by the bracket 7.
By connecting a servo-driven turning motor to this turning axis, the swing angle around the turning axis 8 of the tool driving device 9, that is, about the Y axis is controlled. The tool driving device 9 includes a rotary tool shaft 10 facing the main spindle axis of the lathe, and milling tools 11 and 12 are mounted on the rotary tool shaft.

In this type of lathe, a tool magazine and a tool changing device are provided behind the headstock 2, and the tool rest 5 moves leftward while the rotary tool shaft 10 is swung leftward in the drawing. The tool is changed. Milling machine 11 shown in FIG.
Is mounted on the rotary tool shaft 10 by the tool changing device when performing the outer peripheral elliptical machining of the work. When the inner peripheral ellipse machining of the work is performed, the milling cutter 12 of FIG. 3 is mounted on the rotary tool shaft 10 by the tool changing device.

The milling cutter 11 for peripheral processing has a structure in which a plurality of throw-away tips 11c with the cutting edges 11b facing inward are fixed to the peripheral part of a bowl-shaped tool base 11a.
The outer peripheral ellipse processing of the work 13 is performed by gripping the base end of the work 13 with the chuck 4 mounted on the main spindle of the lathe, fixing the main spindle at a predetermined angle, and adjusting the main spindle axis at an angle corresponding to the angle of the ellipse to be processed. The rotary tool driving device 9 is turned around the rotary shaft 8 and fixed so that the axis of the rotary tool shaft intersects, and the tool rest so that the center of the arc connecting the cutting edge 11b of the indexable insert is on the main axis. 5 by moving the tool post 5 in the Z-axis direction while rotating the rotary tool shaft 10. As a result, the outer periphery of the work 13 is
It is processed into an ellipse as exaggerated.

FIG. 3 is a diagram showing an example of inner peripheral ellipse processing. The milling cutter 12 for inner peripheral machining is a disk-shaped tool base 1.
This is a structure in which a plurality of throw-away tips 12c with the cutting edge 12b facing outward are fixed to the outer peripheral portion of 2a. The inner peripheral ellipse machining of the work 14 is performed by gripping the outer periphery of the work 14 with the chuck 4, fixing the main shaft at a predetermined angle, and setting the main shaft axis and the axis of the rotary tool axis at an angle corresponding to the angle of the ellipse to be processed. Are rotated so that the rotary tool driving device 9
Swivel around and fix.
The tool rest 5 is moved so that the center of the arc connecting 2b is on the axis of the spindle, and the tool rest 5 is rotated while rotating the rotary tool shaft 10.
Is moved in the Z-axis direction. Thereby, the inner periphery of the work 14 is processed into an ellipse as exaggeratedly shown in FIG.

In the embodiment shown in the figure, a milling type blade having good productivity is used. However, if a rotary blade capable of adjusting the position of one blade at an eccentric position in the radial direction by a screw device or the like is used, the same blade is used. Oval machining with different diameters is also possible.

[0016]

According to the method of the present invention described above,
Using a lathe, accurate elliptical processing of the outer peripheral surface or inner peripheral surface of the work can be performed, and since the processing is based on the same principle as the turning processing, the productivity can be high and the finished surface accuracy can be high. The angle of the ellipse to be machined can be freely changed by setting the deflection angle of the rotary tool axis around the Y axis, and the X-axis positioning of the tool rest 5 so that the center of the arc connecting the cutting edges does not coincide with the main axis. , An eccentric ellipse can be processed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method of processing an outer peripheral ellipse viewed from a side of a work.

FIG. 2 is an exaggerated front view showing the shape of a workpiece whose outer periphery has been machined;

FIG. 3 is an explanatory diagram showing a cross section of a workpiece showing an inner peripheral ellipse processing method.

FIG. 4 is an exaggerated front view showing the shape of a workpiece whose inner periphery has been machined;

FIG. 5 is a perspective view showing an example of a lathe used in the method of the present invention.

FIG. 6 is an explanatory view of a conventional outer peripheral ellipse processing method viewed from the side of a work.

FIG. 7 is an explanatory view showing a cross section of a work in a conventional inner peripheral ellipse processing method.

[Explanation of symbols]

 5 Turret 10 Rotary tool axis 11 Milling 11C Throwaway tip 12 Milling 12C Throwaway tip

Claims (2)

[Claims] A tool post having a main shaft capable of fixing a rotation angle at a predetermined position and capable of controlling positions in an X-axis direction and a Z-axis direction.
A lathe equipped with a rotary tool axis (10) capable of controlling the deflection angle around the Y axis, and the rotary tool axis has a cutting edge (1
1c) is mounted, the main shaft holding the workpiece is fixed, and the direction of the axis of the rotary tool shaft is fixed in a direction intersecting with the main axis, and the rotary tool shaft is rotated. An elliptical machining method for a workpiece on a lathe, characterized by the following. 2. A tool post having a main shaft capable of fixing a rotation angle at a predetermined position and capable of controlling the position in the X-axis direction and the Z-axis direction.
Using a lathe equipped with a rotary tool axis (10) capable of controlling the deflection angle around the Y axis, the rotary tool axis was provided with a cutting edge (12c) having an outwardly facing cutting edge that turns around the axis. Knife (1
2) mounting, fixing the spindle holding the workpiece and fixing the direction of the axis of the rotary tool axis in a direction intersecting with the axis of the spindle, and rotating the rotary tool axis; Ellipse processing method of the work.