Swarf-dividing lathe-turning control device and machine tool provided with same

Abstract

[Problem] To provide: a swarf-dividing lathe-turning control device capable of easily controlling division of swarf during lathe-turning and providing stable cutting quality; and a machine tool using the same. [Solution] This lathe-turning control device is characterized by comprising: a means for controlling lathe-turning in a spiral shape for N times, which is a natural number, until a cut depth d (mm) is achieved while causing the same to gradually move proportionally in an X direction, when F (mm / rev) represents the feed amount in a Z direction per revolution, X represents the cutting direction, and d (mm) represents the cut depth; a means for controlling the lathe-turning in a spiral shape for N times until a cut depth -d (mm) is achieved while causing the same to gradually move proportionally in the -X direction; and a means for controlling reversal of the feeding by said feeding amount F (mm / rev).

Description

Chip-breaking turning control device and machine tool equipped with same

[0001] The present invention relates to a control device for turning, and more particularly to a control device for breaking chips.

[0002] Turning is a cutting method in which a turning tool is pressed against a rotating workpiece. In this case, the chips cut by the turning tool are generated continuously and thinly, which can wrap around the workpiece or scratch it.

[0003] For example, Patent Document 1 discloses a technique in which cutting is stopped once at a point where the workpiece has moved a distance L2 along the Z axis, then the workpiece is reversed a distance shorter than L2, and then the workpiece is moved forward a distance L2 from that point, repeating this process. However, the NC-controlled turning process disclosed in this publication has a technical problem in that the forward and reverse stop positions change depending on the cutting speed and depth of cut, resulting in unstable quality of the turned surface.

[0004] Japanese Patent Application Publication No. 6-285701

[0005] An object of the present invention is to provide a chip breaking control device that can easily control chip breaking during turning and can provide stable cutting quality, and a machine tool using the same.

[0006] The chip breaking control device according to the present invention is a turning control device, characterized in that it comprises: means for controlling spiral turning N times (a natural number) up to the depth of cut d (mm) while gradually moving proportionally in the X direction, where F (mm / rev) is the Z-direction feed amount per rotation, X is the cutting direction, and d (mm) is the cutting amount; means for controlling spiral turning N times up to the depth of cut -d (mm) while gradually moving proportionally in the -X direction; and control means for reversely looking up the feed amount F (mm / rev). Here, the natural number N is preferably in the range of 3 to 6.

[0007] Here, "turning spirally N times" refers to cutting by linearly changing the cutting depth by the machining length NF (mm) until the cutting depth reaches d (mm), and then cutting by NF (mm) while linearly changing the cutting depth in the -X direction until the cutting depth reaches -d (mm). Next, by reversing the feed in the reverse direction by the same feed amount F (mm), the position and phase of the spiral caused by the rotary feed become the same, which stabilizes the turning separation position (separation point) of the chips. When this type of control is expressed in an NC program, the spindle angle at the starting point is specified using the phase setting function of the spindle that holds the workpiece in the chuck, and biaxial linear motion is alternately performed at a specified command speed relative to the XZ cross section.

[0008] Such control can be performed by an NC program and is applicable to NC-controlled machine tools.

[0009] In the control device according to the present invention, the cutting edge is turned spirally with a biaxial linear motion in the XZ cross section with the position of the cutting edge facing the X direction, then turned spirally in the -X direction for the same machining length, and then turned in the reverse direction by a feed amount F (mm), repeating these steps while cutting, so that chips are broken at regular intervals of the machining length. Such a control device can be applied to machine tools such as multi-tasking machines with turning functions.

[0010] An explanatory diagram of the cutting path is shown. An explanatory diagram of the breaking points of turning chips is shown. The breaking of chips using a cutting edge nose R0.4 is shown. (a) shows normal cutting, and (b) shows a workpiece with a breaking operation. The measurement results of the surface roughness of the cut surface using a cutting edge nose R0.4 are shown. (a) shows normal cutting, and (b) shows breaking cutting. The breaking of chips using a cutting edge nose R0.8 is shown. (a) shows normal cutting, and (b) shows cutting with a breaking operation. The measurement results of the surface roughness of the cut surface using a cutting edge nose R0.8 are shown. (a) shows normal cutting, and (b) shows breaking cutting.

[0011] An example of chip-breaking turning control according to the present invention will be described below with reference to the drawings. FIG. 1 shows an explanatory diagram of the cutting path. The cutting direction is X, the cutting depth is d (mm), and the feed rate per revolution is F (mm / rev). The spindle angle at the starting point is specified using the spindle phasing function, and a biaxial linear motion command is issued for the XZ cross section, cutting is performed so that the cutting depth is d mm in the X direction. Under these conditions, spiral turning is performed N times. Next, a similar motion command is issued to achieve -d (mm) in the -X direction, and spiral turning is performed N times. Next, turning is performed in reverse (reverse turning) by the feed rate F (mm / rev). This operation is shown in FIG. 1, with oblique turning indicated by the α hypotenuse and reverse turning indicated by the F feed arrow. The relational equations at this time are as follows: Here, N is preferably a natural number between 3 and 6. As a result, it can be seen that there are chip separation points at every predetermined processing length, as shown by the circle marks in Figure 2.

[0012] Next, a comparison was made between conventional cutting (a) consisting of continuous turning using a non-breaker-type cutting tip and the segmented cutting according to the present invention (b). The cutting conditions were as follows: cutting speed V 200 m / min, feed rate F 0.1 mm / rev, cutting length 31 mm, and finishing allowance ap 0.1 mm. Example 1: When a non-breaker tip with a cutting tip nose radius of 0.4 mm was used, the chips produced in conventional cutting were continuous and wrapped around each other, as shown in Figure 3(a). In contrast, the segmented cutting according to the present invention produced chips segmented into uniform sizes, as shown in Figure 3(b). The results of measuring the surface roughness of the cut surface are shown in Figure 4. There was no significant difference between conventional cutting and segmented cutting. Example 2: A non-breaker tip with a cutting tip nose radius of 0.8 mm was used to compare conventional cutting and segmented cutting. Figure 5 shows the state of the chips, with the segmented cutting producing chips of the specified size. Figure 6 shows the results of measuring the surface roughness of the cut surface. No significant difference was observed between normal cutting and segmented cutting.

[0013] The present invention can perform turning while breaking up chips, and therefore can be used in machine tools such as multi-tasking machines.

Claims

1. A control device for turning processing, characterized in that, where the Z-direction feed amount per revolution is F (mm / rev), the cutting direction is X, and the cutting amount is d (mm), the control device has: means for controlling spiral turning N times (in natural numbers) up to the cutting amount d (mm) while gradually varying proportionally in the X direction; means for controlling spiral turning N times up to the cutting amount -d (mm) while gradually varying proportionally in the -X direction; and control means for reversely looking up only the feed amount F (mm / rev).

2. The chip breaking turning control device according to claim 1, wherein the natural number N is 3 to 6.

3. A machine tool comprising the chip-breaking turning control device according to claim 1 or 2.

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