Method for turning a workpiece, machine tool, and machining program

Abstract

To make it possible to suppress boundary wear with inexpensive constitution in even a side cutting edge.SOLUTION: A CNC lathe feeds a tool 5 in a rotary shaft direction and a radial direction of a work-piece 3, and in a prescribed inclination direction A that is not parallel to a final processed surface 31 of the work-piece 3, thereby performing turning so that an entering angle α, which is an angle between a straight line part of a side cutting edge 52 and the inclination direction A, becomes less than 90°.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for turning a workpiece using a machine tool, and a machine tool and a machining program capable of executing the method. [Background technology]

[0002] When turning workpieces such as SUS, titanium alloy, heat-resistant alloy, etc., there is a problem that the tool life is shortened due to the occurrence of notch wear. As a countermeasure, it is known that making the cutting angle of the insert small (for example, less than 90°) is effective, as disclosed in Non-Patent Document 1. However, when turning a workpiece with a stepped shape including a small diameter portion and a large diameter portion, if the cutting angle is small, interference occurs between the insert and the workpiece near the end face of the large diameter portion that connects to the small diameter portion, resulting in uncut portions. This means that the uncut portions must be machined with a separate tool, which increases the number of tools and lengthens the machining time. Therefore, Patent Documents 1 and 2 disclose a processing method that suppresses notch wear by changing the feed rate of the tool to move the boundary portion. Patent Document 3 discloses a processing method that enables continuous processing by rotating a tool spindle equipped with a round insert tool around the B axis to sequentially change the cutting edge position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-19701 [Patent Document 2] JP 2003-71601 A [Patent Document 3] JP 2006-68874 A [Non-patent literature]

[0004] [Non-Patent Document 1] 342nd Seminar "Demand is growing! Advanced machining technology a la carte for difficult-to-machine materials (superalloys, ceramics, composite materials)", Text pp. 6-7, "High-speed, high-performance cutting tools for aircraft jet engine parts", June 10, 2010, Japan Society for Precision Engineering Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the machining methods of Patent Documents 1 and 2, the depth of cut is constant, so there is a problem that the notch wear of the side cutting edge cannot be suppressed. In the machining method of Patent Document 3, a mechanism for rotating the tool around the B axis is required, which is a problem that the machine tool is expensive.

[0006] Therefore, an object of the present disclosure is to provide a method for turning a workpiece, a machine tool, and a machining program that are inexpensive and capable of suppressing notch wear even on side cutting edges. [Means for solving the problem]

[0007] In order to achieve the above object, a first configuration of the present disclosure is a machine tool that rotates a workpiece and feeds a tool having an insert including a straight portion on a side cutting edge in the direction of the rotation axis and / or the radial direction of the workpiece to cut the workpiece. , so that the final machining surface can be obtained as preset. A method for turning, comprising the steps of: The tool is moved in the axial direction and the radial direction of the workpiece. The above This method is characterized by performing turning by feeding in a predetermined inclined direction that is not parallel to the final machining surface, so that the cutting angle, which is the angle between the straight portion of the side cutting edge and the inclined direction, is less than 90°. Another aspect of the first configuration of the present disclosure is the above-mentioned configuration, For the final machined surface The angle of the inclination direction is The above It is characterized in that it is determined from the shape of the final machined surface and the shape of the insert. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, the machine tool automatically generates a machining program based on the determined angle of the inclination direction, and performs turning according to the machining program. Another aspect of the first configuration of the present disclosure is characterized in that, in the above configuration, a feed operation in the inclined direction is included as part of a series of processing steps from the start of processing to the end of processing. In order to achieve the above object, a second configuration of the present disclosure is characterized in that it is a machine tool capable of executing any of the workpiece turning methods described in the first configuration. In order to achieve the above object, a third configuration of the present disclosure is a machining program characterized in that it causes a control device of a machine tool capable of turning a workpiece by rotating the workpiece and feeding a tool having an insert including a straight portion on its side cutting edge in the direction of the rotation axis and / or in the radial direction of the workpiece to execute the method of turning a workpiece described in the first configuration. Effect of the Invention

[0008] According to the present disclosure, by reducing the cutting angle artificially by inclined machining, it is possible to suppress notch wear even in the side cutting edge. In addition, since a rotating mechanism around the rotation axis of the tool is not required, notch wear can be suppressed with an inexpensive configuration. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing the configuration of a turning process using a CNC lathe. [Diagram 2] 1A and 1B are explanatory diagrams of a turning method. [Diagram 3] (A) and (B) are enlarged views of the inclined processed portion. [Figure 4] 1 is a flowchart of a machining program generating method. [Diagram 5] 1A to 1C are explanatory diagrams of a turning method when the workpiece shape is different. [Figure 6] 1A to 1C are explanatory diagrams of a turning method when the workpiece shape is different. [Figure 7] 10A to 10C are explanatory diagrams of a turning method when an insert shape is different. [Figure 8] FIG. 1 is an explanatory diagram showing an example of a conventional turning method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram showing the configuration of a turning process using a CNC lathe, which is an example of a machine tool. The CNC lathe 1 has a chuck 2 for holding a workpiece 3 on a rotating spindle. A tool (such as a cutting tool) 5 is fixed to a tool rest 4 with an insert 51 at its tip, and is controlled by an NC device 6. The insert 51 is rhombic in shape with a straight side cutting edge 52 (main cutting edge). The NC device 6 has a memory unit 7 that stores the product shape and tool shape, a calculation unit 8 that calculates the angle of inclination machining from the product shape and tool shape, a program generation unit 9 that generates a machining program, a program interpretation unit 10 that interprets the machining program, and a machine operation control unit 11 that controls the machine.

[0011] Fig. 2 is a schematic diagram of a turning method for a workpiece 3. In turning, boundary wear of the side cutting edge 52 can be suppressed by using a tool 5 equipped with an insert 51 having a small (acute) cutting edge angle α (the angle between the side cutting edge 52 and the direction of the rotation axis of the workpiece 3) as shown in Fig. 8, and performing a feed operation as in the machining path 30. However, if the workpiece 3 has a stepped shape, a remaining cut portion 33 as shown in Fig. 8 is generated, and therefore it is necessary to machine the remaining cut portion 33 with a separate tool having a cutting edge angle α of a right angle or obtuse angle. This results in an increase in the number of tools and an increase in machining time. 2(A), the machining section 102 performs machining by feeding (which may be a reciprocating motion or a repetitive motion in one direction) in the A direction inclined with respect to the final machined surface 31 of the workpiece 3. This inclined machining reduces the cutting angle α with respect to the A direction to less than 90° in an artificial manner, thereby suppressing the boundary wear.

[0012] In this case, the entire area of ​​the processed portion 102 may be inclined as shown in Fig. 2(A).Also, as shown in Fig. 2(B), in a series of processing steps, the processed portion 102 in the middle may be inclined, and the processed portion 101 at the start and the processed portion 103 at the end, which are both ends of the processed portion, may be cut in the B direction parallel to the final processed surface 31 of the workpiece 3 (parallel processing). In this way, if the feed operation in the inclined direction is included as part of the series of machining steps from the start to the end of machining, it is possible to use inclined machining and parallel machining separately, and achieve a well-balanced machining that takes into account both the machining time and the tool life due to boundary wear. In particular, the machining part 103 at the end can also be turned using the same tool 5, so machining can be completed with one tool 5 without leaving any uncut parts.

[0013] Fig. 3 is an enlarged view of inclined machining. When the machined surface 32 before final machining is machined parallel to the Z-axis direction with an insert 51 having a large cutting angle β as shown in Fig. 3(B), the cutting angle β becomes 90° or more, and boundary wear occurs. However, by performing inclined machining so that the machined surface 32 is inclined from the Z-axis direction at an inclination angle (angle of the inclination direction) 201 as shown in Fig. 3(A), the cutting angle α with respect to the machined surface 32 becomes pseudo-less than 90°. Therefore, boundary wear is suppressed.

[0014] 4 is a flowchart relating to a method for generating a machining program by the NC device 6. In step (hereinafter referred to as "S") 1, the product shape is acquired through input by the operator, etc., and stored in the memory unit 7. In S2, the tool shape (shape of the insert 51) is acquired through input by the operator, etc., and stored in the memory unit 7. In S3, the calculation unit 8 calculates the angle of inclination machining (inclination angle 201) based on the data acquired in S1 and S2. In S4, the program generation unit 9 generates a machining program based on the inclination angle 201 calculated in S3. Therefore, the machine operation control unit 11 controls the tool 5 based on the machining program interpreted by the program interpretation unit 10 to perform turning of the workpiece 3. In this way, by determining the inclination angle 201 from the shape of the final machined surface of the workpiece and the shape of the insert 51 of the tool, the operator's effort in determining the inclination angle 201 can be reduced. Furthermore, if a machining program based on the determined tilt angle 201 is automatically generated and turning is performed according to the machining program, the time and effort required to create the machining program can be reduced.

[0015] In this way, the turning method, CNC lathe 1, and machining program of the above-mentioned form perform turning by feeding the tool 5 in the axial and radial directions of the workpiece 3 and in a predetermined inclined direction A that is not parallel to the final machined surface 31 of the workpiece 3, so that the cutting angle α, which is the angle between the straight portion of the side cutting edge 52 and the inclined direction A, is less than 90°. According to this configuration, by artificially reducing the cutting angle α by inclined machining, it is possible to suppress notch wear even in the side cutting edge 52. In addition, since a revolving mechanism around the rotation axis of the tool is not required, notch wear can be suppressed with an inexpensive configuration. In particular, in this case, inclined machining is performed using a tool 5 having an insert 51 with an infeed angle β of obtuse or right angle to the direction parallel to the rotation axis of the workpiece, so no uncut portion is left on the vertical end face of the large diameter part of the workpiece, and turning can be performed with one tool 5. This makes it possible to reduce the number of tools and the time required for tool replacement.

[0016] In the above embodiment, a workpiece whose final machined surface is parallel to the rotation axis direction is illustrated as an example, but the present disclosure is not limited to this. For example, as shown in FIG. 5, even for a workpiece 3A having a tapered portion 34 inclined with respect to the rotation axis direction, when the workpiece is machined at an angle to the final machined surface 31 shown by the two-dot chain line, the cutting angle α becomes smaller than the cutting angle β when the workpiece is machined parallel to the final machined surface 31. Also, as shown in Figure 6, in the case of a workpiece 3B whose final machined surface 31 is perpendicular to the rotation axis direction, when the tool 5 is attached parallel to the rotation axis direction of the workpiece and fed, if the workpiece is machined at an angle to the final machined surface 31, the cutting angle α will be smaller than the cutting angle β when machined parallel to the final machined surface 31.

[0017] On the other hand, in the above embodiment, an insert is exemplified in which the cutting angle becomes obtuse when the tool is fed parallel to the direction of the rotation axis of the workpiece. However, even in the case of a tool 5 having an insert 51 in which the cutting angle β becomes acute even when the tool is fed parallel to the final machined surface 31 of the workpiece 3 as shown in Figure 7, if the tool is machined at an angle to the final machined surface 31, the cutting angle α will be smaller than the cutting angle β when machined parallel to the final machined surface 31.

[0018] In addition, in the above embodiment, a machining program including inclined machining is automatically generated, but it is also possible to determine in advance by experiment or the like for each tool shape an inclination angle at which boundary wear is unlikely to occur, and to adopt the value of that inclination angle each time. Furthermore, when calculating the inclination angle, parameters of machining conditions such as the machining time and the number of machining cycles may be added, and the calculation results of the machining time and the tool life due to boundary wear may be displayed to the operator, so that the operator can determine the inclination angle. In addition, the machine tool is not limited to a CNC lathe, but may be a multi-tasking machine capable of turning, etc. The shape of the insert is not limited to the rhombus described in the above embodiment, but may be another shape such as a triangle. [Explanation of symbols]

[0019] 1··CNC lathe, 2··Chuck, 3, 3A, 3B··Workpiece, 4··Tool rest, 5··Tool, 6··NC device, 7··Memory unit, 8··Calculation unit, 9··Program generation unit, 10··Program interpretation unit, 11··Machine operation control unit, 30··Machining path, 31··Final machined surface, 32··Machined surface before final machining, 33··Remaining cutting area, 34··Tapered portion, 51··Insert, 52··Side cutting edge, 101··Machined portion at start, 102··Machined portion in the middle, 103··Machined portion at end, 201··Tilt angle, α, β··Cutting angle.

Claims

1. A method for turning a workpiece in a machine tool by feeding a tool having an insert with a straight portion on a side cutting edge in an axial direction and / or a radial direction of the workpiece while rotating the workpiece so as to obtain a preset final machined surface, comprising the steps of: A method for turning a workpiece, characterized in that the tool is fed in the rotational axis direction and radial direction, and in a predetermined inclined direction that is not parallel to the final machined surface of the workpiece, so that the cutting angle, which is the angle between the straight portion of the side cutting edge and the inclined direction, is less than 90°.

2. A method for turning a workpiece as described in claim 1, characterized in that the angle of the inclination direction relative to the final machined surface is determined from the shape of the final machined surface of the workpiece and the shape of the insert.

3. 3. The method for turning a workpiece according to claim 2, further comprising the step of: causing the machine tool to automatically generate a machining program based on the determined angle of the tilt direction; and performing turning according to the machining program.

4. 4. A method for turning a workpiece according to claim 1, wherein a feed operation in the inclined direction is included as part of a series of machining steps from the start of machining to the end of machining.

5. A machine tool capable of executing the method for turning a workpiece according to any one of claims 1 to 4.

6. A machining program for causing a control device of a machine tool capable of turning a workpiece by rotating the workpiece and feeding a tool having an insert including a straight portion on its side cutting edge in the direction of the rotation axis and / or radial direction of the workpiece to turn the workpiece, the control device being configured to execute the method of turning a workpiece described in claim 1.

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