WO2014171244A1

WO2014171244A1 - Machine tool and cutting method for workpiece having protruding section

Info

Publication number: WO2014171244A1
Application number: PCT/JP2014/056945
Authority: WO
Inventors: 石原正史
Original assignee: 村田機械株式会社
Priority date: 2013-04-16
Filing date: 2014-03-14
Publication date: 2014-10-23
Also published as: JPWO2014171244A1

Abstract

Provided is a machine tool capable of high-precision, high-efficiency machining of a surface to be cut having a cylindrical shape and a protruding section provided on both sides thereof in the axial direction. The machine tool comprises: a main shaft (2) supporting an end section of a workpiece (W) and rotating; a tool (20A) movable relative to the main shaft (2) in the X-axis and Y-axis directions; and a machining control device (30) that controls the movement of the tool (20A). The tool (20A) has a linear blade tip. The blade tip is parallel to the Y-Z plane and is inclined relative to the Z-axis direction. The machining control device (30) causes the tool (20A) to move to a stipulated Y-axis cutting feed start position, then causes the tool (20A) to move in the Y-axis direction such that the blade tip of the tool (20A) passes through the surface to be cut (F1) on the workpiece (W).

Description

Machine tool and method of cutting workpiece with overhang

Related applications

This application claims the priority of Japanese Patent Application No. 2013-085697 filed on Apr. 16, 2013, which is incorporated herein by reference in its entirety.

The present invention relates to a machine tool suitable for cutting a cylindrical surface to be cut, such as a bearing support portion such as a camshaft, a crankshaft, etc., having an overhanging portion projecting outward on both sides in the axial direction. The present invention also relates to a method for cutting a workpiece with an overhang using the machine tool.

In the workpiece W with an overhanging portion as shown in FIG. 8A, when cutting a cylindrical surface to be cut F between the two overhanging portions Wa and Wb, a cutting edge 20a such as a normal turning tool or the like. In the conventional machining using the tool 20 with a thin tip, as shown in FIGS. 2B and 2C, by feeding from the center of the surface to be cut F toward both overhang portions Wa and Wb. Then, each side is processed with

separate tools

20 and 20.

Japanese Patent No. 3984052

According to the above-described conventional processing using the tool 20 having a thin tip of the blade edge 20a, a streak-shaped feed mark is generated every round. Therefore, in order to obtain high surface roughness, the feed speed of the tool 20 cannot be increased. There was a limit to increasing productivity. When the required high surface roughness cannot be obtained, it is necessary to perform grinding later, and the productivity further deteriorates. In order to increase productivity, two tools 20 are simultaneously processed, but this requires a mechanism for moving each tool 20 individually, which complicates the configuration.

An object of the present invention is to provide a machine tool capable of machining a cylindrical surface to be cut having overhang portions on both sides in the axial direction with high accuracy and high efficiency, and a cutting method for a workpiece with an overhang portion. It is.

Hereinafter, in order to facilitate understanding, the present invention will be described with reference to the reference numerals of the embodiments for convenience.

The machine tool according to the present invention has overhang portions (Wa, Wb, Wc) projecting to the larger diameter side than the surfaces to be cut (F1, F2) on both sides in the axial direction of the cylindrical surfaces to be cut (F1, F2). , Wd) is a machine tool (1) for cutting the cut surface (F1, F2) of a work (W) having a spindle (2) that supports and rotates an end of the work (W). And the X-axis direction that is perpendicular to the Z-axis direction that is the direction of the axis (O1) of the main shaft (2) and that is the cutting direction of the workpiece (W) into the cut surface (F1, F2), And a tool (20A) movable relative to the main shaft (2) in the Y-axis direction, which is a direction orthogonal to the Z-axis direction and the X-axis direction, and the movement of the tool (20A) is controlled. And a machining control device (30). The tool (20A) has a linear cutting edge (20Aa), and the cutting edge (20Aa) is parallel to a YZ plane which is a plane including the Y-axis direction and the Z-axis direction, and Z It is inclined with respect to the axial direction. In the machining control device (30), the position of the cutting edge (20Aa) of the tool (20A) is a position in the Z-axis direction within the range of the cut surface (F1, F2) of the workpiece (W), And it is a position in the X-axis direction where a cutting depth determined with respect to the cut surface (F1, F2) of the workpiece (W) is obtained, and is determined in the Y-axis direction with respect to the workpiece (W). The tool (20A) is moved to the Y-axis cutting feed start position at a certain distance, and then the cutting edge (20Aa) of the tool (20A) passes through the cut surface (F1, F2) of the workpiece (W). Thus, the tool (20A) is moved in the Y-axis direction.

According to this configuration, after executing the approach operation of moving the tool (20A) so that the position of the cutting edge (20Aa) of the tool (20A) becomes the Y-axis cutting feed start position by the machining control device (30), The tool (20A) is moved in the Y-axis direction so that the cutting edge (20Aa) of the tool (20A) passes the work surface (F1, F2) of the work (W), and the work surface of the work (W) ( A Y-axis cutting feed operation for cutting F1, F2) is executed. Since the tool (20A) has a linear cutting edge (20Aa), a single cutting feed operation can be performed in a wide range in the Z-axis direction of the surface to be cut (F1, F2), for example, overhang portions (Wa, Wb on both sides). , Wc, Wd), the entire width of the cut surface (F1, F2) can be cut. Since the cutting edge (20Aa) of the tool (20A) is parallel to the YZ plane and is inclined with respect to the Z-axis direction, the workpiece cutting points at the cutting edge (20Aa) of the tool (20A) are continuous. Process while shifting. Therefore, the feed mark can be reduced and the surface roughness can be processed satisfactorily. Moreover, since the workpiece cutting point is continuously shifted, the frictional heat due to the chips does not concentrate on one point of the cutting edge (20Aa). As a result, the machining speed can be increased, a cylindrical surface to be cut having overhangs on both sides in the axial direction can be machined with high accuracy and high efficiency, and the durability of the tool can be improved.

In this invention, the tool (20A) is relatively movable in the Z-axis direction with respect to the main axis, and the width of the work surface (F1, F2) of the workpiece (W) in the Z-axis direction is When the width of the cutting edge (20Aa) of the tool (20A) is wider than the Z-axis direction, the machining control device (30) moves the tool (20A) in the Y-axis direction while moving the tool (20A) in the Z-axis direction. May be.
Thereby, the to-be-cut surface (F1, F2) whose width in the Z-axis direction is wider than the cutting edge (20Aa) of the tool (20A) can be cut by only one cutting feed operation.

The method of cutting a workpiece with an overhang portion according to the present invention includes an overhang projecting on both sides in the axial direction of a cylindrical surface to be cut (F1, F2) to the larger diameter side than the surface to be cut (F1, F2). It is a method of cutting the said to-be-cut surface (F1, F2) of the workpiece | work (W) which has a part (Wa, Wb, Wc, Wd). In this cutting method, the direction of the axis (O1) of the main shaft (2) that supports and rotates the end of the workpiece (W) is the Z-axis direction, and the workpiece ( When the cutting direction of W) into the cut surface (F1, F2) is the X-axis direction and the direction perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction, the straight line of the tool (20A) The tool (20A) is held so that the cutting edge (20Aa) is parallel to the YZ plane, which is a plane including the Y-axis direction and the Z-axis direction, and is inclined with respect to the Z-axis direction In this state, the position of the cutting edge (20Aa) of the tool (20A) is a position in the Z-axis direction within the range of the cut surface (F1, F2) of the workpiece (W), and the workpiece (W ) To obtain a cutting depth determined for the cut surface (F1, F2) An approach process in which the tool (20A) is moved to a Y-axis cutting feed start position that is in a direction and at a distance defined in the Y-axis direction with respect to the workpiece (W), and the Y-axis cutting feed start Y-axis cutting that moves the tool (20A) in the Y-axis direction so that the cutting edge (20Aa) of the tool (20A) passes through the cut surface (F1, F2) of the workpiece (W) from the position. A feeding process.

According to this method, the surface to be cut (F1, F2) of the workpiece (W) is machined with the tool (20A) having the linear cutting edge (20Aa), so that the surface to be cut in one Y-axis cutting feed process. A wide range of (F1, F2) in the Z-axis direction, for example, the entire width of the surface to be cut (F1, F2) between the protruding portions (Wa, Wb, Wc, Wd) on both sides can be cut. Since the cutting edge (20Aa) of the tool (20A) is parallel to the YZ plane and inclined with respect to the Z-axis direction, the workpiece cutting point at the cutting edge (20Aa) of the tool (20A) is continuously set. Process while shifting. Therefore, the feed mark can be reduced and the surface roughness can be processed satisfactorily. In addition, since the cutting point on the workpiece is continuously shifted and the cutting portion that is the contact portion between the workpiece and the cutting edge is substantially linear, frictional heat due to chips may be concentrated on one point of the cutting edge (20Aa). Absent. As a result, the machining speed can be increased, a cylindrical surface to be cut having overhangs on both sides in the axial direction can be machined with high accuracy and high efficiency, and the durability of the tool can be improved.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be understood more clearly from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.

It is the figure which added the block diagram of a control system to the partially broken front view of the machine tool concerning one Embodiment of this invention. It is a partially broken side view of the machine tool. (A) is the front view of the tool holder and tool of the machine tool, (B) is the side view, (C) is the bottom view of the tool for special processing. (A) is a side view of an example of a workpiece | work, (B) is the front view. It is a block diagram which shows the structure of the processing control apparatus of the machine tool. It is explanatory drawing which shows the process of an example of the process using the tool for the said special processing with the machine tool. It is explanatory drawing which shows the process of a different example of the process using the tool for the said special processing with the same machine tool. It is explanatory drawing which shows each process of the conventional process.

An embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a partially broken front view of a machine tool according to this embodiment, and FIG. 2 is a partially broken side view thereof. This machine tool is a lathe, and a spindle 2 extending in the left-right direction in a front view is rotatably installed on a bed 1 (FIG. 2) via a spindle stock 3 (FIG. 1). A rotation center 5 (FIG. 1) supported by the core presser 4 (FIG. 1) is provided on an extension line of O1. One end of the work W is gripped by a chuck 2 a (FIG. 1) that is a part of the main shaft 2 provided at the tip of the main shaft 2, and the center of the other end is supported by the rotation center 5. The main shaft 2 is rotationally driven via a transmission mechanism 7 (FIG. 2) by a main shaft motor 6 (FIG. 2) composed of a servo motor or the like.

A pair of processing means 10 are provided above and below the position where the workpiece W is supported by the spindle 2. Each processing means 10 moves the turret-type tool holder 14 in the Z-axis direction with respect to the bed 1 via the Z-axis feed base 11 (FIG. 2), the X-axis feed base 12, and the Y-axis feed base 13. It is installed so as to be movable in three axial directions orthogonal to the X-axis direction and the Y-axis direction. The Z-axis direction indicates the direction of the axis O1 of the main shaft 2. The X-axis direction refers to the cutting direction of the workpiece W into the cut surface F1 (FIG. 1). The Y-axis direction refers to a direction orthogonal to the Z-axis direction and the X-axis direction. In this embodiment, the X-axis direction is the vertical direction, the Y-axis direction is the front-rear direction, and the Z-axis direction is the left-right direction.

The Z-axis feed base 11 is installed on a guide 1a (FIG. 2) in the Z-axis direction provided on the bed 1 so as to freely advance and retreat, and includes a Z-axis servo motor 16a (FIG. 1) and a feed screw mechanism (not shown). Driven back and forth in the Z-axis direction by the Z-axis moving mechanism 16 (FIG. 2). The X-axis feed base 12 is installed on a guide 11a (FIG. 2) in the X-axis direction provided on the Z-axis feed base 11 so as to freely advance and retreat, and an X-axis servo motor 17a (FIG. 1) and a feed screw mechanism (not shown). Are driven forward and backward in the X-axis direction by the X-axis moving mechanism 17 (FIG. 2). The Y-axis feed base 13 is installed on a guide 12a in the Y-axis direction provided on the X-axis feed base 12 so as to be able to advance and retreat, and comprises a servo motor 18a (FIG. 1) and a feed screw mechanism (not shown). The mechanism 18 is driven back and forth in the Y-axis direction.

As shown in FIG. 3, the tool holder 14 is of a turret type, and can turn around a turning axis O2 parallel to the axis O1 (FIG. 1) of the main shaft 2. The tool holder 14 has a polygonal shape as viewed from the direction along the turning axis O2, and a plurality of tool mounting portions 14a are provided on the outer periphery thereof. The tool mounting portion 14 a may be a part of the tool holder 14 or may be a tool holder provided separately from the tool holder 14. A tool 20 is mounted on each tool mounting portion 14a. A machining position P in which an arbitrary tool 20 among the plurality of tools 20 mounted on each tool mounting portion 14a is determined by rotating the tool holder 14 around the rotation axis O2 by an index drive mechanism (not shown). (Fig. 2).

For the plurality of tools mounted on each tool mounting portion 14a of the tool holder 14, cutting is performed while moving the tool holder 14 in the Y-axis direction in addition to the normal processing tool 20 such as a cutting tool and a rotary tool. A special processing tool 20A is included. 1 and 2, a special processing tool 20 </ b> A is attached to the tool holder 14 of the upper processing means 10. As shown in FIG. 3, the special processing tool 20A has a linear cutting edge 20Aa. The tool holder 14A has a tool holder 14A so that the cutting edge 20Aa is parallel to the YZ plane, which is a plane including the Y axis direction and the Z axis direction, and is inclined with respect to the Z axis direction during processing. It is attached to.

1 and 2, the machine tool is entirely covered with a machine body cover 22, and a space in which the headstock 3 and the tool holder 14 are installed in the machine body cover 22 is a machining area Q. The entire bottom surface of the processing region Q is formed in an inclined hopper-like portion 23 (FIG. 2), and one end 24a (FIG. 2) is formed under an opening (not shown) portion of the bottom surface of the hopper-like portion 23. The chip conveyor 24 (FIG. 2) located extends to the rear of the machine tool through a space penetrating the front and back of the lower surface of the bed 1. The front surface of the processing area Q can be opened and closed by an opening / closing door 25 provided on the machine body cover 22.

As shown in FIG. 1, this machine tool is controlled by a machining control device 30. The processing control device 30 includes a computer-type numerical control device and a programmer controller, and controls a normal processing control unit 31 that controls processing by a tool 20 other than the special processing tool 20A, and processing by the special processing tool 20A. And a special processing control unit 32. The special machining control unit 32 includes an approach control unit 33 and a Y-axis cutting feed control unit 34. Based on the command determined by the normal machining control unit 31 or the special machining control unit 32, the

servo motors

17a, 18a, and 16a are driven through the X-axis driver 35, the Y-axis driver 36, and the Z-axis driver 37. .

For example, when the tool 20 is a tool, the normal machining control unit 31 adjusts the position of the tool holder 14 in the X-axis direction so that the cutting edge of the tool 20 has a predetermined cutting depth with respect to the workpiece W. It is a control part which performs the well-known process which moves the tool holder 14 to a Z-axis direction, and performs a cutting process.

The special machining control unit 32 is a control unit that cuts the cut surfaces F1 and F2 of the workpiece W as shown in FIG. The workpiece W has a cylindrical surface to be cut F1 and F2, and projecting portions Wa, Wb, and Wc that protrude to the larger diameter side of the surfaces to be cut F1 and F2 on both sides in the axial direction of the surfaces to be cut F1 and F2. , Wd. The workpiece W in the illustrated example is a camshaft of an engine, and the surfaces to be cut F1 and F2 are bearing support portions in which a bearing is fitted on the outer periphery. In addition to the camshaft, the present invention is also applied to the machining of the bearing support portion of the crankshaft.

The approach control means 33 of the special machining control unit 32 performs control to move the tool 20A from the standby position to a predetermined Y-axis cutting feed start position. The standby position is not particularly limited, and may be a specific position that is determined, or may be a position where the previous cutting process has been completed. The Y-axis cutting feed start position is a position in the Z-axis direction in which the position of the cutting edge 20Aa of the tool 20A is within the range of the cut surfaces F1 and F2 of the workpiece W, and with respect to the cut surfaces F1 and F2 of the workpiece W The position of the tool 20A when it is a position in the X-axis direction where a predetermined cutting amount is obtained and is a distance determined in the Y-axis direction with respect to the workpiece W. Further, the Y-axis cutting feed control means 34 moves the tool 20A in the Y-axis direction so that the cutting edge 20Aa of the tool 20A passes through the surfaces to be cut F1 and F2 of the workpiece W from the Y-axis cutting feed start position. Take control.

The machining control device 30 is specifically configured as shown in FIG. That is, the machining control device 30 includes a program storage unit 41 and an arithmetic control unit 42. The program storage means 41 stores a machining program 43 for normal machining and a program 44 for special machining. The machining program 43 for normal machining is a program for executing control of the normal machining control unit 31. The special machining program 44 includes an approach program 45 and a cutting feed program 46. The approach program 45 is a program for executing the control of the approach control means 33. The Y-axis cutting feed program 46 is a program for executing control of the Y-axis cutting feed control means 34. The arithmetic control unit 42 decodes and executes the

machining programs

43 and 44, and includes a CPU 47, a memory 48, and the like.

A specific example of processing by the special processing tool 20A will be described with reference to FIG. This figure is an explanatory view in which a broken plan view and a broken front view showing the positional relationship between the workpiece W and the tool 20A in each process of machining are shown together in one figure. Each broken plan view of FIG. 6 is a plan view broken along the VIa-VIa plane of FIG. 3A with reference to the tool 20A. Each broken front view of FIG. 6 is a plan view taken along the VIb-VIb plane of FIG. The same applies to FIG. 7 used in the later description. In addition, the dashed-two dotted line in FIG. 6 (A), (B) shows the target outer diameter of the to-be-cut surface F1 used as a process target.

(1) Approach Process First, the tool 20A is moved from the machining position P (FIG. 2) or the standby position to the Y-axis cutting feed start position under the control of the approach control means 33, and the tool 20A is moved to FIG. 6 (A). Position at the position shown in. The position of the cutting edge 20Aa of the tool 20A at this time is between the overhanging portions Wa and Wb on both sides of the cut surface F1 to be machined in the Z-axis direction, and the target of the cut surface F1 in the X-axis direction. The height is the same as the upper end of the outer diameter, and the Y-axis direction is upstream of the workpiece W in the tool feed direction (left side in the figure).

(2) Y-axis cutting feed process Next, under the control of the Y-axis cutting feed control means 34, the tool 20A is moved from the Y-axis cutting feed start position in FIG. Thus, the Y-axis is fed to the downstream side (right side in the figure) in the tool feeding direction. FIG. 5B shows a state at the time when one end (the upper end in the fracture plan view) of the workpiece W starts to be cut to the target outer diameter by the tip S of the cutting edge 20Aa of the tool 20A. FIG. 6C shows a state in which the Y-axis feed of the tool 20A has been completed and the entire width of the cut surface F1 has been cut to the target outer diameter.

Since the tool 20A has a straight cutting edge 20Aa, it is possible to cut a wide range in the Z-axis direction of the surface F1 to be cut by one cutting feed operation. Since the cutting edge 20Aa of the tool 20A is parallel to the YZ plane and inclined with respect to the Z-axis direction, the workpiece cutting point on the cutting edge 20Aa is processed while being continuously displaced. Therefore, the feed mark can be reduced and the surface roughness can be processed satisfactorily. In the conventional processing using a cutting tool or the like, it was necessary to perform grinding processing later in order to obtain high-precision surface roughness. However, in the processing using the special processing tool 20A, a high-precision surface can be obtained by itself. Since the roughness can be obtained, it is possible to eliminate grinding. Moreover, since the workpiece cutting point is continuously shifted, frictional heat due to chips does not concentrate on one point of the cutting edge 20Aa. Thereby, the processing speed can be increased and the durability of the tool 20A can be improved.

(3) Returning process When the cutting of the cut surface F1 in the cutting feed process is completed, the tool 20A is raised as shown in FIG. Thereafter, the tool holder 14 is moved in the Y-axis direction and the Z-axis direction and returned to the standby position.

FIG. 7 shows an example of machining in the case where the width of the cutting surface F1 in the Z-axis direction is wider than the width of the cutting edge 20Aa of the tool 20A in the Z-axis direction. In this case, the tool 20A is fed in the Z axis while feeding the tool 20A in the process of shifting from the figure (B) to the figure (C). The rest is the same as the processing example of FIG. Thus, in the Y-axis cutting feed process, the tool 20A is fed simultaneously in the Y-axis direction and the Z-axis direction, so that the surface to be cut F1 wider than the cutting edge 20Aa of the tool 20A can be cut only once. Can be cut with.

In this way, this machine tool uses the tool 20A for special machining and feeds the tool under the control of the approach control means 33 and the Y-axis cutting feed control means 34, so that the overhang portions Wa, Wb, Cylindrical surface to be cut F1 and F2 with Wc and Wd can be processed with high accuracy and high efficiency.

As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily assume various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims.

2 ...

Spindle

20, 20A ... Tool 20Aa ... Cutting edge 30 ... Processing control device 33 ... Approach control means 34 ... Y-axis cutting feed control means F, F1, F2 ... Surface to be cut O1 ... Spindle axis W ... Workpieces Wa, Wb , Wc, Wd ... overhang

Claims

A machine tool for cutting the surface to be cut of a workpiece having a projecting portion projecting to a larger diameter side than the surface to be cut on both axial sides of a surface to be cut in a cylindrical surface,
A main shaft that supports and rotates the end portion of the workpiece, an X-axis direction that is perpendicular to the Z-axis direction that is the direction of the axis of the main shaft, and that is a cutting direction of the workpiece into the surface to be cut, and Z A tool that is movable relative to the main axis in the Y-axis direction, which is a direction orthogonal to the axial direction and the X-axis direction, and a machining control device that controls the movement of the tool;
The tool has a linear cutting edge, and the cutting edge is parallel to the YZ plane, which is a plane including the Y-axis direction and the Z-axis direction, and is inclined with respect to the Z-axis direction. Yes,
The processing control device includes:
The position of the cutting edge of the tool is a position in the Z-axis direction within the range of the surface to be cut of the workpiece, and a cutting amount determined with respect to the surface to be cut of the workpiece can be obtained in the X-axis direction. The tool is moved to a Y-axis cutting feed start position at a position and at a distance determined in the Y-axis direction with respect to the workpiece, and then
A machine tool that moves the tool in the Y-axis direction so that a cutting edge of the tool passes through the surface to be cut of the workpiece.
When the tool is relatively movable in the Z-axis direction with respect to the main axis, and the width of the work surface of the workpiece in the Z-axis direction is wider than the width of the cutting edge of the tool in the Z-axis direction, The machine tool according to claim 1, wherein the machining control device moves the tool in the Z-axis direction while moving the tool in the Y-axis direction.
A cutting method for cutting the surface to be cut of a workpiece having a projecting portion projecting to a larger diameter side than the surface to be cut on both axial sides of a surface to be cut in a cylindrical surface,
The direction of the axis of the main shaft that rotates while supporting the end of the workpiece is defined as the Z-axis direction, and the cutting direction of the workpiece into the cut surface perpendicular to the Z-axis direction is defined as the X-axis direction. When the direction perpendicular to the Z-axis direction and the X-axis direction is the Y-axis direction,
In a state where the tool is held such that the linear cutting edge of the tool is parallel to the YZ plane, which is a plane including the Y-axis direction and the Z-axis direction, and is inclined with respect to the Z-axis direction. ,
The position of the cutting edge of the tool is a position in the Z-axis direction within the range of the surface to be cut of the workpiece, and a cutting amount determined with respect to the surface to be cut of the workpiece can be obtained in the X-axis direction. An approach process of moving the tool to a Y-axis cutting feed start position that is a position and is at a distance defined in the Y-axis direction with respect to the workpiece;
A workpiece with a projecting portion having a Y-axis cutting feed process in which the tool is moved in the Y-axis direction so that the cutting edge of the tool passes through the surface to be cut of the workpiece from the Y-axis cutting feed start position. Cutting method.