JP2020082278A - Machine tool and cutting method - Google Patents

Abstract

To provide a machine tool that can finish a concaved cylindrical surface of a work-piece with a small surface roughness, and scan shorten a processing time by eliminating a grinding process with a grindstone.SOLUTION: A cutting tool T1, which has a curved cutting edge which is linear when viewed from an X direction and is convexed toward a concaved cylindrical surface Wb when viewed from a Y direction, is moved in any one of the Y direction, a synthesis direction of the Y direction and a Z direction, a synthesis direction of the Y direction and the X direction, and a synthesis direction of the Y direction, the Z direction and the X direction, the curved cutting edge is displaced with respect to a bus line on the concaved cylindrical surface Wb along the Z direction when viewed from the X direction, and cutting of the concaved cylindrical surface Wb is performed while a cutting point on the bus line is displaced.SELECTED DRAWING: Figure 1

Description

The present invention relates to a machine tool and a cutting method.

A lathe, which is one of machine tools, holds a work to be processed on a rotary shaft, and performs cutting and the like with a cutting tool such as a cutting tool while rotating the work. With this lathe, a cutting tool with a straight cutting edge is used to move the cutting tool in the tangential direction of the workpiece (direction intersecting the axis of rotation) to move the cutting point of the cutting edge relative to the workpiece. The processing method of cutting the is adopted (for example, refer to Patent Document 1). According to this processing method, since the cutting edge of the cutting tool shifts into the work while cutting, the surface roughness of the work surface of the work can be reduced.

Japanese Patent No. 6206504

The processing method of Patent Document 1 described above is intended for a work having a cylindrical surface. On the other hand, in the case of processing a work having a concave cylindrical surface, it becomes difficult for the above-described processing method to perform cutting while moving the cutting point with the linear cutting edge with respect to the concave cylindrical surface of the work. Therefore, the machining amount is regulated according to the surface shape of the concave cylindrical surface, the machining tool is moved in the rotation axis direction to perform cutting along the concave cylindrical surface, and then the concave cylindrical surface is ground with an angular grindstone or the like. The desired surface roughness is obtained by finishing with this method.

However, when finishing with a grindstone after performing pre-processing with a lathe as described above, it is necessary to set the work on the grinder again after removing the work from the lathe. It will be long. When rotating a workpiece on a grinding machine, the peripheral speeds of the small diameter side and the large diameter side of the concave cylindrical surface differ, so the amount of grinding when the angular grindstone abuts on the small diameter side and the large diameter side of the inclined surface. Will be different. Therefore, the surface roughness is not uniform, and it may be difficult to obtain the required surface roughness.

The present invention is to provide a machine tool and a cutting method capable of finishing a concave cylindrical surface of a work to a small surface roughness and shortening a processing time by omitting a grinding step by a grindstone. To aim.

A machine tool according to an aspect of the present invention holds a machine body that holds a workpiece having a concave cylindrical surface and that has a spindle that rotates about an axis in the Z direction, and a cutting tool that cuts the workpiece that is held by the spindle. A tool rest that can be used and a tool rest that is provided on the machine body in the Z direction, the X direction that is orthogonal to the Z direction and that regulates the cut amount for the workpiece, and the Y direction that is orthogonal to both the Z direction and the X direction. And a moving mechanism for moving the cutting tool. The cutting tool has a curved cutting edge that is linear when viewed from the X direction and convex toward the concave cylindrical surface when viewed from the Y direction. The tool rest is held in a state of being inclined with respect to the Z direction when viewed from the X direction, and the tool rest is in the Y direction, the combined direction of the Y and Z directions, the combined direction of the Y and X directions, and Y. Direction, the combined direction of the Z direction and the X direction, the cutting edge of the curved cutting edge is displaced with respect to the generatrix on the surface of the concave cylindrical surface along the Z direction when viewed from the X direction The concave cylindrical surface is cut while the cutting points on the line are displaced.

In addition, the cutting tool is a curved cutting edge whose projected shape viewed from the Y direction is a machining surface on the concave cylindrical surface, or a curved cutting edge whose projected shape viewed from the Y direction is smaller than the machining surface on the concave cylindrical surface. May have. Further, the moving mechanism includes a Z-axis guide provided in the machine body along the Z-direction, a Z-axis slider movable in the Z-direction along the Z-axis guide, and a Z-axis slider provided in the Z-direction. Along the X-axis guide, an X-axis slider that can move in the X direction along the X-axis guide, and a Y-axis guide that is provided on the X-axis slider and that extends in the Y direction and can move in the Y direction along the Y-axis guide. The Y-axis slider may be provided, and the tool rest may be provided on the Y-axis slider and movable in the Z direction, the X direction, and the Y direction, respectively.

A machining method according to an aspect of the present invention retains a machine body including a spindle that holds a workpiece having a concave cylindrical surface and rotates around an axis in the Z direction, and a cutting tool that cuts the workpiece held by the spindle. A tool rest that can be used and a tool rest that is provided on the machine body in the Z direction, the X direction that is orthogonal to the Z direction and that regulates the cut amount for the workpiece, and the Y direction that is orthogonal to both the Z direction and the X direction. A method of cutting a concave cylindrical surface using a machine tool comprising: a moving mechanism for moving the concave cylindrical surface, the cutting tool being linear when viewed from the X direction and directed toward the concave cylindrical surface when viewed from the Y direction. It has a convex curved cutting edge, and the curved cutting edge is held on the tool post in a state of being inclined with respect to the Z direction when viewed from the X direction. The tool post is divided into the Y direction, the Y direction and the Z direction. The surface of the concave cylindrical surface along the Z direction when viewed from the X direction by moving in any one of the combining direction, the combining direction of the Y direction and the X direction, and the combining direction of the Y direction, the Z direction, and the X direction. The cutting of the concave cylindrical surface is performed while the cutting edge of the curved cutting edge is displaced with respect to the upper generatrix and the cutting point on the generatrix is displaced.

According to the machine tool and the machining method of the present invention, by using the cutting tool having the curved cutting edge described above, the cutting edge of the curved cutting edge with respect to the generatrix on the surface of the concave cylindrical surface along the Z direction when viewed from the X direction. Deviation and the cutting point on the generatrix shifts, the concave cylindrical surface is cut, so by moving the workpiece and the cutting tool relative to each other, the cutting edge of the curved cutting edge shifts with respect to the workpiece. Therefore, the surface roughness of the work surface of the work can be reduced. Further, since the machined surface is finished to have a small surface roughness, it is possible to omit the conventional grinding step for finishing and shorten the time required for machining the work.

In addition, the cutting tool has a curved cutting edge whose projected shape viewed from the Y direction is a machining surface on the concave cylindrical surface, or a curved cutting edge whose projected shape viewed from the Y direction is smaller than the machining surface on the concave cylindrical surface. With the configuration having, the concave cylindrical surface can be easily cut into a desired processing surface by the curved cutting edge. The moving mechanism includes a Z-axis guide, a Z-axis slider, an X-axis guide, an X-axis slider, a Y-axis guide, and a Y-axis slider, and the tool rest is provided on the Y-axis slider. , Z-direction, X-direction, and Y-direction, respectively, the tool post can be accurately and stably moved in the Z-direction, X-direction, and Y-direction by the guide and slider in each direction. ..

It is a front view showing an example of a machine tool concerning a 1st embodiment. It is the side view which looked at the machine tool from the Z direction. (A) shows a state of the cutting tool viewed from the +X direction, and (B) shows a projected shape of the cutting tool viewed from the Y direction. It is a figure which shows the state which saw the cutting tool from the Y direction. It is a top view which shows an example of the movement of a cutting tool when it sees from a X direction, (A) is a figure before cutting, (B) is a figure during cutting, (C) is a figure after cutting is there. It is a top view which shows an example of the movement of a cutting tool when it sees from Z direction, (A) is a figure before cutting, (B) is a figure during cutting, (C) is a figure after cutting is there. It is a figure which shows the example which the cutting point on a generatrix in a concave cylindrical surface moves when the workpiece W is seen from the Y direction. (A) shows the state which saw the cutting tool which concerns on 2nd Embodiment from +X direction, (B) is a figure which shows the state which saw the cutting tool which concerns on 2nd Embodiment from Y direction. .. It is a top view which shows an example of the movement of a cutting tool when it sees from a X direction, (A) is a figure before cutting, (B) is a figure during cutting, (C) is a figure after cutting is there. It is a top view which shows an example of the movement of the cutting tool when it sees from a direction, (A) is a figure before cutting, (B) is a figure during cutting, (C) is a figure after cutting. .. It is a figure which shows the example which the cutting point on a generatrix in a concave cylindrical surface moves when the workpiece|work W is seen from a Y direction. It is a figure which shows the other example of the cutting tool when it sees from a Y direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the modes described below. Further, in the drawings, in order to explain the embodiment, a part of the drawing is enlarged or emphasized, and the scale is appropriately changed. In each of the following drawings, the directions in the drawings will be described using an XYZ coordinate system. In this XYZ coordinate system, the plane parallel to the horizontal plane is the YZ plane. On the YZ plane, the axis AX direction of the main shaft 7 (opposing axis 8) is referred to as the Z direction, and the direction orthogonal to the Z direction on the horizontal plane is referred to as the Y direction. Further, the direction perpendicular to the YZ plane is referred to as the X direction. The X direction is a direction that defines the cut amount for the work W. In each of the X-direction, the Y-direction, and the Z-direction, the direction indicated by the arrow is the + direction, and the opposite direction is the − direction.

<First Embodiment>
The machine tool 100 according to the first embodiment will be described with reference to the drawings. FIG. 1 is a front view showing an example of a machine tool 100 according to the first embodiment. FIG. 2 is a side view of the machine tool 100 shown in FIG. 1 viewed from the Z direction. The machine tool 100 shown in FIGS. 1 and 2 is a lathe. 1 and 2, the +Y side of the machine tool 100 is the front side, and the -Y side is the back side. The +Z side and the −Z side of the machine tool 100 are side surfaces, and the Z direction is the left-right direction of the machine tool 100.

The machine tool 100 has a base 1 which is a machine body. The base 1 is provided with a headstock 2 and a tailstock 4. The headstock 2 supports the main shaft 7 in a rotatable state by a bearing or the like (not shown). The headstock 2 is fixed to the base 1, but may be configured to be movable in the Z direction, the X direction, the Y direction, etc., and moved by the driving of a motor or the like. A chuck drive unit 9 is provided at the +Z side end of the main shaft 7. The chuck driving section 9 moves the plurality of grasping claws 9 a in the radial direction of the main shaft 7 to hold the work W. In FIG. 1, the work W is gripped by using the three grasping claws 9a arranged at equal intervals around the axis line AX of the main shaft 7, but the present invention is not limited to this form, and the number or shape of the grasping claws 9a is Any configuration capable of holding the work W can be applied. The work W held by the grasping claw 9a is formed in, for example, a cylindrical shape that can be grasped by the grasping claw 9a, and has a concave cylindrical surface Wb on a part of its surface Wa.

The −Z side end of the spindle 7 projects from the headstock 2 in the −Z direction, and the pulley 11 is attached to this end. A belt 13 is stretched between the pulley 11 and the axis of the motor 12 provided on the base 1. The main shaft 7 is rotated by a motor 12 via a belt 13. The rotation speed and the like of the motor 12 is controlled by an instruction from the control device CONT. As the motor 12, for example, a motor having a torque control mechanism is used. The main shaft 7 is not limited to being driven by the motor 12 and the belt 13, and the drive of the motor 12 is transmitted to the main shaft 7 by a gear train or the like, or the main shaft 7 is directly rotated by the motor 12. May be.

The tailstock 4 is formed so as to be movable along the Z-axis guide 3 installed on the base 1. The tailstock 4 supports the opposing shaft 8 in a rotatable state by a bearing or the like (not shown). The axis AX direction of the main shaft 7 and the axis line direction of the counter shaft 8 are in the Z direction. A center 10 is attached to the −Z side end of the tailstock 4 so as to abut against the +Z side end surface of the work W. The opposing shaft 8 may be fixed to the tailstock 4 and used as a dead center.

When the work W is long (long in the Z direction), the end portion of the work W on the +Z side is held by the center 10 of the tailstock 4. Since the long work W rotates while being sandwiched between the main shaft 7 and the opposing shaft 8, the work W can be stably rotated during cutting. When the work W is short (short in the Z direction), the work W is held and rotated only by the grasping claws 9a of the spindle 7. In this case, the tailstock 4 may not be used. Therefore, in this machine tool 100, the tailstock 4 may be omitted.

The moving mechanism 20 includes a Z-axis guide 5, a Z-axis slider 17, an X-axis guide 18, an X-axis slider 15, a Y-axis guide 16, a Y-axis slider 19, a Z-direction drive system M1, and an X-direction. It has a drive system M2 and a Y-direction drive system M3. The base 1 is provided with two Z axis guides 5 arranged in the Z direction. As shown in FIGS. 1 and 2, the two Z axis guides 5 are arranged side by side in the vertical direction (X direction), and are provided so as to extend in the Z direction.

The Z-axis guides 5 are not limited to being provided in the upper and lower two as shown in the drawing, and may be provided in one or three or more. Further, the two Z axis guides 5 may be arranged side by side in the Y direction above the Z axis slider 17. The Z-axis guide 5 is provided with a Z-axis slider 17 that can move in the Z direction along the Z-axis guide 5. The Z-axis slider 17 moves in the Z-direction by being driven by the Z-direction drive system M1 (moving device), and is held at a predetermined position. For the Z-direction drive system M1, for example, a drive device such as an electric motor or a hydraulic device is used.

Two X-axis guides 18 are formed on the +Y-side surface of the Z-axis slider 17. The two X axis guides 18 are provided so as to extend in the X direction so as to be parallel to each other at a predetermined interval. The X-axis guide 18 is provided with an X-axis slider 15 that is movable along the two X-axis guides 18. The X-axis slider 15 moves in the X-direction by being driven by the X-direction drive system M2 (moving device), and is held at a predetermined position. As the X-direction drive system M2, for example, a drive device such as an electric motor or a hydraulic device is used.

Two Y-axis guides 16 are formed on the −X side surface of the X-axis slider 15. The two Y-axis guides 16 are provided so as to extend in the Y-direction so as to be parallel to each other at a predetermined interval. The Y-axis guide 16 is provided with a Y-axis slider 19 that is movable along the two Y-axis guides 16. The Y-axis slider 19 moves in the Y-direction by being driven by the Y-direction drive system M3 (moving device), and is held at a predetermined position. As the Y-direction drive system M3, for example, a drive device such as an electric motor including a ball screw mechanism or a hydraulic device is used. The Z-direction drive system M1, the X-direction drive system M2, and the Y-direction drive system M3 described above are controlled by the controller CONT.

A plate-shaped turret (turret) 21 is provided on the mounting surface 19a, which is the −X side surface (lower surface) of the Y-axis slider 19. The plate-shaped tool rest 21 is disposed above the main shaft 7 in the vertical direction (+X side). The plate-shaped tool rest 21 is formed in a plate shape from a material such as metal. The plate-shaped tool rest 21 can mount the cutting tool T1 on the lower surface (the surface on the −X side) 21a via the holder 24. Note that the above-described moving device is an example, and any configuration capable of moving the plate-shaped tool rest (cutting tool T1) in the X direction, the Y direction, and the Z direction may be applied.

The cutting tool T1 has a curved cutting edge H1 at the end on the −X side. FIG. 3A shows the cutting tool T1 viewed from the +X direction. As shown in FIG. 3A, the curved cutting edge H1 is linear when viewed from the X direction, and is arranged in a state of being inclined at an angle θ with respect to the Z direction. That is, in the curved cutting edge H1, for example, the end on the +Z side is arranged on the −Y side, and the end on the −Z side is arranged on the +Y side. The tilt angle θ with respect to the Z direction viewed from the X direction is set, for example, in the range of 5 degrees to 85 degrees, the range of 15 degrees to 75 degrees, or the range of 30 degrees to 60 degrees. , Can be set arbitrarily. The curved cutting edge H1 has a dimension in the Z direction slightly larger than, equal to, or substantially equal to the dimension in the Z direction of the concave cylindrical surface Wb of the work W when viewed from the X direction. As shown in FIG. 3A, the curved cutting edge H1 is longer than the dimension of the concave cylindrical surface Wb in the Z direction by a dimension a on the +Z side and a dimension b on the −Z side. .. The size a and the size b may be the same or different.

FIG. 3B shows a projected shape of the cutting tool T1 viewed from the Y direction. As shown in FIG. 3(B), the cutting tool T1 has a curved cutting edge H1 having a shape in which the projected shape (shape projected on the XZ plane) viewed from the Y direction becomes the processing surface Ws on the concave cylindrical surface Wb. is doing. That is, the projected shape of the curved cutting edge H1 shown in FIG. 3(B) becomes the processing surface Ws after the concave cylindrical surface Wb is cut by the cutting tool T1. In the figure, for simplification, the processed surface Ws is shown as the same surface as the concave cylindrical surface Wb. Further, when the cutting tool T1 is viewed from the E direction in FIG. 3A, it has an elliptical shape with a downward convex shape. By tilting the cutting tool T1 having such a curved cutting edge H1 at an angle θ with respect to the Z direction as shown in FIG. 3A, the projected shape of the curved cutting edge H1 viewed from the Y direction is a predetermined value. It has an arc shape with a radius of curvature (see FIG. 4).

FIG. 4 is a diagram showing a state in which the cutting tool T1 is viewed from the Y direction. As shown in FIG. 4, the curved cutting edge H1 has an arc shape that is convex toward the concave cylindrical surface Wb when viewed from the Y direction. The concave cylindrical surface Wb of the work W has a radius of curvature R1. The curved cutting edge H1 has an arc shape with a radius of curvature R2 along the concave cylindrical surface Wb when viewed from the Y direction. That is, in the present embodiment, the radius of curvature R1 of the concave cylindrical surface Wb of the work W and the radius of curvature R2 of the curved cutting edge H1 when viewed from the Y direction are the same, or the radius of curvature R2 is slightly smaller than the radius of curvature R1. It is set to be large. The radius of curvature R2 of the curved cutting edge H1 is the processing surface Ws of the concave cylindrical surface Wb after processing, and is set to a desired dimension.

Next, the operation of the machine tool 100 configured as above will be described. In the following description, the contents of FIGS. 1 to 4 will be referred to as appropriate. 5A and 5B are plan views showing an example of the movement of the cutting tool T1 when the workpiece W is viewed from the X direction, where FIG. 5A is a drawing before cutting, FIG. 5B is a drawing during cutting, and FIG. ) Is a diagram after cutting. 6A and 6B are plan views showing an example of the movement of the cutting tool T1 when the workpiece W is viewed from the Z direction. FIG. 6A is a drawing before cutting, FIG. 6B is a drawing during cutting, and FIG. ) Is a diagram after cutting. FIG. 7 is a diagram showing an example in which the cutting point C1 on the generatrix L on the concave cylindrical surface Wb moves when the work W is viewed from the Y direction.

First, the work W to be processed is held on the spindle 7. After gripping the work W, the motor 12 is driven to rotate the main shaft 7, thereby rotating the work W around the axis line AX. When the work W is gripped by the main shaft 7 and the counter shaft 8, the main shaft 7 and the counter shaft 8 are rotated in synchronization with each other. Further, the rotation speed of the work W is appropriately set according to the processing.

Then, the position of the cutting tool T1 in the X direction is adjusted. In this adjustment, the plate-shaped tool rest 21 is moved in the X direction by the X-direction drive system M2 so that the curved cutting edge H1 corresponds to the concave cylindrical surface Wb of the work W. The position of the curved cutting edge H1 in the X direction defines the cut amount of the work W with respect to the concave cylindrical surface Wb. The cut amount with respect to the concave cylindrical surface Wb may be set to a value preset by the control device CONT, or may be set manually by an operator.

Subsequently, when the rotation of the work W is stable, the cutting tool T1 is aligned in the Y and Z directions. The positioning of the cutting tool T1 in the Y direction and the Z direction and the movement in the Y direction are performed by moving the Z axis slider 17 in the Z direction and moving the Y axis slider 19 (plate-shaped tool rest 21) in the Y direction. Done by The cutting tool T1 is aligned according to the generatrix L of the concave cylindrical surface Wb of the work W. As shown in FIGS. 5A and 6A, the −Y side end H1a of the curved cutting edge H1 of the cutting tool T1 is arranged near the +Y side of the generatrix L of the workpiece W.

Subsequently, the curved cutting edge H1 of the cutting tool T1 is moved in the -Y direction to perform the cutting process on the concave cylindrical surface Wb of the work W. The curved cutting edge H1 of the cutting tool T1 moves from the +Y side to the −Y side with respect to the generatrix L in the Z direction on the concave cylindrical surface Wb of the workpiece W, and the −Y side end H1a of the curved cutting edge H1. The vicinity (a portion displaced from the end H1a by the dimension a toward the −Z side) first comes into contact with the work W, and the concave cylindrical surface Wb is cut near the end H1a. At this time, as shown in FIG. 7, the cutting point C1 on the generatrix L on the concave cylindrical surface Wb becomes the end portion C1s of the concave cylindrical surface Wb in the −Z direction. Subsequently, the cutting tool T1 performs the cutting work of the work W while moving in the −Y direction. Further, the cutting tool T1 moves in the −Y direction while keeping the tangential direction of the cutting point C1 of the cutting edge of the curved cutting edge H1 parallel to the tangential direction of the cutting point C1 on the generatrix L.

As shown in FIGS. 5(B) and 6(B), the curved cutting edge H1 moves in the −Y direction along the concave cylindrical surface Wb, so that the cutting portion on the work W is cut from the end H1a to the end. It gradually shifts toward the portion H1b. Furthermore, while the curved cutting edge H1 moves in the −Y direction, the cutting point C1 on the generatrix L on the concave cylindrical surface Wb of the work W is along the generatrix L in the −Z direction, as shown in FIG. Proceed to. That is, when the cutting tool T1 moves in the −Y direction, the cutting point C1 on the curved cutting edge H1 moves. In the present embodiment, the concave cylindrical surface Wb and the curved cutting edge H1 have the same radius of curvature when viewed from the Y direction, or have an arc shape with a radius of curvature R2 slightly larger than the radius of curvature R1. Therefore, when the curved cutting edge H1 cuts the concave cylindrical surface Wb at the intermediate portion between the end H1a and the end H1b, for example, the central portion C1n in the Z direction having the smallest diameter in the concave cylindrical surface Wb is the cutting point. Becomes

After that, as shown in FIG. 7, a portion of the curved cutting edge H1 near the end H1b (a portion deviated from the end H1b to the +Z side by a dimension b) reaches the −Z side end C1e of the bus L, and As shown in FIGS. 5(C) and 6(C), the cutting of the concave cylindrical surface Wb by the cutting tool T1 is completed at the stage where the end C1e is separated from the −Y side. As shown in FIGS. 5 to 7, since the cutting tool T1 moves in the Y direction, the processing surface Ws of the concave cylindrical surface Wb cut by the curved cutting edge H1 is the curved cutting edge H1 viewed from the Y direction. The projected shape (see FIG. 3B) is obtained. In the cutting operation described above, the curved cylindrical cutting edge H1 of the cutting tool T1 is used to cut the concave cylindrical surface Wb using the entire end H1a to H1b, but the present invention is not limited to this form. The concave cylindrical surface Wb may be cut by using a part of the curved cutting edge H1. Further, in the present embodiment, the cutting tool T1 is moved in the Y direction, but the cutting tool T1 may be moved in a direction obtained by slightly adding the Z direction to the Y direction (combined direction).

As described above, according to the machine tool 100 of the present embodiment, by moving the cutting tool T1 having the curved cutting edge H1 in the Y direction, the concave cylindrical surface Wb along the Z direction when viewed from the X direction. Since the curved cutting edge H1 is displaced with respect to the generatrix L on the surface of the workpiece and the cutting point C1 on the generatrix is displaced while the concave cylindrical surface Wb is cut, the curved cutting edge H1 of the cutting tool T1 with respect to the workpiece W is By making a smooth cut, the surface roughness of the processed surface Ws of the work W can be reduced. Further, since the processed surface Ws is finished to have a small surface roughness, it is possible to omit the conventional grinding process for finishing, and it is possible to shorten the time required for processing the work W.

<Second Embodiment>
Next, a second embodiment will be described with reference to the drawings. In this embodiment, the configuration of the cutting tool T2 is different from that of the cutting tool T1 of the first embodiment, and the other configurations are the same as those of the first embodiment. Therefore, the same components as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified. FIG. 8A shows the cutting tool T2 according to the second embodiment as viewed from the +X direction. The cutting tool T2 has a curved cutting edge H2 at the end on the -X side.

As shown in FIG. 8A, the curved cutting edge H2 is linear when viewed from the X direction, and is arranged in a state of being inclined at an angle θ with respect to the Z direction. That is, in the curved cutting edge H2, for example, the end portion on the +Z side is arranged on the −Y side, and the end portion on the −Z side is arranged on the +Y side. The tilt angle θ with respect to the Z direction viewed from the X direction is set, for example, in the range of 15 degrees to 75 degrees or in the range of 30 degrees to 60 degrees, but the tilt angle can be set arbitrarily. The curved cutting edge H2 has a dimension in the Z direction smaller than that of the concave cylindrical surface Wb of the work W in the Z direction when viewed from the X direction.

FIG. 8B is a diagram showing the cutting tool T2 viewed from the Y direction. As shown in FIG. 8B, the curved cutting edge H2 has an arc shape that is convex toward the concave cylindrical surface Wb when viewed from the Y direction. Further, as shown in FIG. 8B, the projected shape of the curved cutting edge H2 viewed from the Y direction is smaller than the machined surface Ws after the concave cylindrical surface Wb is machined by the cutting tool T2. In the present embodiment, the radius of curvature R3 of the curved cutting edge H2 when viewed from the Y direction is smaller than the radius of curvature R1 of the concave cylindrical surface Wb of the work W. The radius of curvature R3 of the curved cutting edge H2 is smaller than the dimension of the processed surface Ws on the concave cylindrical surface Wb after processing. Note that, when the cutting tool T2 is viewed from the E direction in FIG. 3A, the elliptical shape having a downward convex shape is the same as the curved cutting edge H1 of the first embodiment.

Next, the operation of machining the concave cylindrical surface Wb using the cutting tool T2 having such a curved cutting edge H2 will be described. 9A and 9B are plan views showing an example of the movement of the cutting tool T2 when the workpiece W is viewed from the X direction. FIG. 9A is a drawing before cutting, FIG. 9B is a drawing during cutting, and FIG. ) Is a diagram after cutting. 10A and 10B are plan views showing an example of the movement of the cutting tool T2 when the workpiece W is viewed from the Z direction, FIG. 10A is a drawing before cutting, FIG. 10B is a drawing during cutting, and FIG. ) Is a diagram after cutting. 11A to 11C are diagrams showing an example in which the cutting point C2 on the generatrix L on the concave cylindrical surface Wb when the work W is viewed from the Y direction moves.

First, similarly to the first embodiment, the work W to be processed is held on the spindle 7, and the work W is rotated about the axis AX. Then, the plate-shaped tool rest 21 is moved in the X direction by the X-direction drive system M2 so that the curved cutting edge H2 corresponds to the concave cylindrical surface Wb of the work W.

Subsequently, when the rotation of the work W is stable, the cutting tool T2 is aligned in the Y and Z directions. The positioning of the cutting tool T2 in the Y direction and the Z direction, and the movement in the combined directions P1 and P2 described later are performed by moving the Z axis slider 17 in the Z direction and by moving the Y axis slider 19 (plate-shaped tool rest 21). This is performed by moving in the Y direction and moving the X-axis slider 15 in the X direction. The cutting tool T2 is aligned according to the generatrix L of the concave cylindrical surface Wb of the work W. As shown in FIGS. 9A and 10A, the −Y side end H2a of the curved cutting edge H2 of the cutting tool T2 is in the vicinity of the +Y side of the generatrix L of the concave cylindrical surface Wb and is the generatrix L. It is placed on the +Z side of.

Then, as shown in FIG. 9(A) and FIG. 10(A), the curved cutting edge H2 of the cutting tool T2 is moved in the combined direction P1 that combines the −Y direction, the −Z direction, and the −X direction. .. The combined direction P1 is set, for example, according to the length along the cutting edge of the curved cutting edge H2 and the generatrix L of the concave cylindrical surface Wb. That is, when the cutting tool T2 passes the busbar L from the +Y side to the −Y side (in one pass), the range (cutting range) of the busbar L of the concave cylindrical surface Wb is cut by the curved cutting edge H2. The composite direction P1 is set.

In the present embodiment, the radius of curvature R3 of the curved cutting edge H2 is smaller than the radius of curvature R1 of the concave cylindrical surface Wb. Therefore, in order to process the curved cutting edge H2 along the concave cylindrical surface Wb, the cutting tool T2 is moved in the X direction in addition to the Y and Z directions. As a result, the curved cutting edge H2 can be moved along the concave cylindrical surface Wb whose diameter gradually decreases in the −Z direction. The combined direction P1 is constant when viewed from the X direction, but gradually changes when viewed from the Y direction and the Z direction.

Subsequently, the curved cutting edge H2 of the cutting tool T2 is moved in the synthesis direction P1 to perform the cutting process on the concave cylindrical surface Wb of the work W. The curved cutting edge H2 of the cutting tool T2 moves from the +Y side to the −Y side with respect to the generatrix L in the Z direction on the concave cylindrical surface Wb of the work W, and the end H2a of the −Y side of the curved cutting edge H2. The vicinity (the portion displaced from the end H2a by a predetermined dimension to the −Z side) first comes into contact with the work W, and the concave cylindrical surface Wb is cut at this end H2a. At this time, as shown in FIG. 11A, the cutting point C2 on the generatrix L on the concave cylindrical surface Wb becomes the end C2s of the concave cylindrical surface Wb in the −Z direction. Subsequently, the cutting tool T2 cuts the work W while moving in the synthesis direction P1. The cutting tool T2 moves in the combined direction P1 while keeping the tangential direction of the cutting point C2 of the cutting edge of the curved cutting edge H2 parallel to the tangential direction of the cutting point C2 on the generatrix L.

As shown in FIGS. 9(B) and 10(B), the curved cutting edge H2 moves in the combined direction P1 along the concave cylindrical surface Wb, so that the cutting portion of the work W is cut from the end H2a to the end. It gradually shifts toward the portion H2b. Further, while the curved cutting edge H2 moves in the combined direction P1, the cutting point C2 on the generatrix L on the concave cylindrical surface Wb of the work W is along the generatrix L as shown in FIG. 11(B). -Proceed in the Z direction. That is, when the cutting tool T2 moves in the combined direction P1, the cutting point C2 on the curved cutting edge H2 moves.

In the present embodiment, the concave cylindrical surface Wb and the curved cutting edge H2 are arcuate shapes having different radii of curvature when viewed from the Y direction. The curved cutting edge H2 moves in the combined direction P1 so that, for example, when the intermediate portion between the end portion H2a and the end portion H2b cuts the concave cylindrical surface Wb, the diameter in the concave cylindrical surface Wb becomes the smallest in the Z direction. The central portion C2n is the cutting point. After the center portion C2n of the concave cylindrical surface Wb becomes the cutting point, the curved cutting edge H2 of the cutting tool T2 is moved in the combined direction P2 that combines the −Y direction, the −Z direction, and the +X direction. As a result, the curved cutting edge H2 can be moved along the concave cylindrical surface Wb whose diameter gradually increases in the -Z direction.

The combined direction P1 is constant when viewed from the X direction, but gradually changes when viewed from the Y direction and the Z direction. That is, the combined direction P1 is set such that the component in the −X direction of the combined direction P1 gradually decreases as the cutting tool T2 moves in the combined direction P1. As a result, the curved cutting edge H2 can be moved along the concave cylindrical surface Wb.

After that, as shown in FIG. 11C, the vicinity of the end H2b (the portion deviated from the end H2b to the +Z side by a predetermined dimension) of the curved cutting edge H2 reaches the end C2e of the busbar L on the −Z side. Then, as shown in FIGS. 9(C) and 10(C), the cutting of the concave cylindrical surface Wb by the cutting tool T2 is completed at a stage away from the end C2e toward the −Y side. In this embodiment, the cutting tool T2 is moved from the combined direction P1 to P2. As shown in FIG. 9, when viewed from the X direction, the combined directions P1 and P2 are the same direction. Also, when viewed from the Z direction, the combined directions P1 and P2 are different.

The combined direction P2 is constant when viewed from the X direction, but gradually changes when viewed from the Y direction and the Z direction. That is, the combined direction P2 is set such that the component in the +X direction of the combined direction P2 gradually increases as the cutting tool T2 moves in the combined direction P2. As a result, the curved cutting edge H2 can be moved along the concave cylindrical surface Wb. As described above, as a result of the combined directions P1 and P2 being gradually changed, the cutting tool T2 moves along an arcuate or elliptical locus when viewed from the Y direction. Further, even when viewed from the Z direction, the cutting tool T2 moves with an arcuate or elliptical locus.

In the cutting operation described above, the concave cylindrical surface Wb is cut using the entire curved cutting edge H2 of the cutting tool T2 from the vicinity of the end H2a to the vicinity of the end H2b, but the present invention is not limited to this form. Alternatively, the concave cylindrical surface Wb may be cut using a part of the curved cutting edge H2.

As described above, according to the present embodiment, by moving the cutting tool T2 having the curved cutting edge H2 in the combined directions P1 and P2, the surface of the concave cylindrical surface Wb along the Z direction when viewed from the X direction. Since the curved cutting edge H2 is displaced with respect to the upper generatrix L and the cutting point C2 on the generatrix L is deviated, the concave cylindrical surface Wb is cut, so that the curved cutting edge of the cutting tool T2 is similar to the first embodiment. By smoothly cutting the work W into the work W, the surface roughness of the work surface Ws of the work W can be reduced, and the time required for working the work W can be shortened by omitting the grinding step for finishing. be able to.

Further, the cutting tool usable in the present embodiment is not limited to the curved cutting edges H1 and H2 having an arc shape when viewed from the Y direction, like the cutting tools T1 and T2 described above. The cutting tool may have a curved cutting edge constituted by a free curve (free curved surface) in addition to an ellipse and an ellipse when viewed from the Y direction. FIG. 12: is a figure which shows the other example of the cutting tool when it sees from a Y direction. As shown in FIG. 12, the cutting tool T3 has a curved cutting edge H3 having a wavy projection shape when viewed from the Y direction. The cutting tool T3 is used when cutting the corrugated cylindrical surface (concave cylindrical surface) Wc around the axis AX on the surface Wa of the work W. When using this cutting tool T3, the corrugated concave cylindrical surface Wc is cut by the curved cutting edge H3 by moving the cutting tool T3 in the Y direction, or a combination direction in which the Y direction and the Z direction are combined. be able to. That is, in the present embodiment, it is possible to use any cutting tool having a curved cutting edge in which the projected shape of the curved cutting edge viewed from the Y direction is the concave cylindrical surface of the workpiece W, that is, the processing surface Ws.

Although the embodiments have been described above, the present invention is not limited to the above description, and various modifications can be made without departing from the gist of the present invention. In the above-described embodiment, one cutting tool T1 is held on the plate-shaped tool rest 21 (see FIGS. 1 and 2), but the present invention is not limited to this form, and the plate-shaped tool rest 21 includes a plurality of cutting tools T1. May be held in a state of being arranged in the Z direction, for example. In this case, the plate-shaped tool rest 21 is moved by the moving device (for example, the Z-direction drive system M1) to select the cutting tool T1 or the like to be used, and to prevent other cutting tools T1 and the work W from interfering with each other. A comparison mechanism for comparing the cutting tool T1 of 1 may be provided.

Further, in the above-described embodiment, the configuration in which the plate-shaped tool rest 21 (cutting tool T1 and the like) is arranged above the work W has been described as an example, but the present invention is not limited to this form. For example, the plate-shaped tool rest 21 (cutting tool T1 or the like) may be arranged below or on the side of the work W. Further, plate-shaped tool rests 21 (cutting tools T1 and the like) are arranged both above and below the work W, and the concave cylindrical surface Wb of one work W is simultaneously cut by a plurality of cutting tools T1 and the like. It may be configured.

Further, in the above-described embodiment, the cutting tool T1 and the like are described as an example in which they are held by the plate-shaped tool rest 21, but the present invention is not limited to this mode. For example, the cutting tool T1 and the like may be held on the peripheral surface of a turret-shaped tool post that is rotatable around a predetermined axis. In this case, the cutting tool T1 or the like to be used may be selected by rotating the turret-shaped tool rest. Further, the turret type tool rest is configured to be movable in the X direction and the Y direction by a moving device, and the cutting tool T1 and the like are moved in the Y direction by a Y direction moving mechanism provided on the peripheral surface of the turret type tool rest. May be applied.

AX... Axis line CONT... Control device C1, C2... Cutting points H1, H2, H3... Curved cutting edge L... Bus line M1... Z direction drive system (moving device)
M2...X direction drive system (moving device)
M3...Y direction drive system (moving device)
P1, P2... Combined directions R1, R2, R3... Curvature radii T1, T2, T3... Cutting tool W... Work Wa... Surface Wb, Wc... Concave cylindrical surface Ws...・Processing surface 1... Base (machine body)
5... Z-axis guide 7... Spindle 15... X-axis slider 16... Y-axis guide 17... Z-axis slider 18... X-axis guide 19... Y-axis slider 20...・Movement mechanism 21...Plate-shaped turret (turret)
24... Holder 100, 200... Machine tool

Claims (4)

A machine body having a main shaft that holds a work having a concave cylindrical surface and rotates about an axis in the Z direction;
A tool post capable of holding a cutting tool for cutting the work held on the spindle.
Provided in the machine body, the tool rest is in the Z direction, the X direction orthogonal to the Z direction and defining the cut amount for the workpiece, and the Y direction orthogonal to both the Z direction and the X direction. And a moving mechanism for moving the
The cutting tool has a curved cutting edge that is linear when viewed from the X direction and has a convex shape toward the concave cylindrical surface when viewed from the Y direction, and the curved cutting edge is viewed from the X direction. Is held on the tool post in a state of being inclined with respect to the Z direction,
Of the Y direction, the combined direction of the Y direction and the Z direction, the combined direction of the Y direction and the X direction, and the combined direction of the Y direction, the Z direction, and the X direction. By moving to any of the above, while the cutting edge of the curved cutting edge is displaced and the cutting point on the generatrix is displaced with respect to the generatrix on the surface of the concave cylindrical surface along the Z direction when viewed from the X direction, A machine tool that cuts a concave cylindrical surface. In the cutting tool, the curved cutting edge having a shape in which a projected shape viewed from the Y direction is a processed surface on the concave cylindrical surface, or a shape whose projected shape viewed from the Y direction is smaller than the processed surface on the concave cylindrical surface. The machine tool according to claim 1, having the curved cutting edge of. The moving mechanism is
A Z-axis guide provided on the machine body along the Z direction,
A Z-axis slider movable in the Z direction along the Z-axis guide,
An X-axis guide provided on the Z-axis slider and extending in the X direction,
An X-axis slider movable in the X direction along the X-axis guide,
A Y-axis guide provided on the X-axis slider and extending in the Y direction;
A Y-axis slider movable in the Y direction along the Y-axis guide,
The machine tool according to claim 1 or 2, wherein the tool rest is provided on the Y-axis slider and is movable in the Z direction, the X direction, and the Y direction, respectively. A machine body having a main shaft that holds a work having a concave cylindrical surface and rotates about an axis in the Z direction;
A tool post capable of holding a cutting tool for cutting the work held on the spindle.
Provided in the machine body, the tool rest is in the Z direction, the X direction orthogonal to the Z direction and defining the cut amount for the workpiece, and the Y direction orthogonal to both the Z direction and the X direction. A method of cutting the concave cylindrical surface using a machine tool comprising:
The cutting tool has a curved cutting edge that is linear when viewed from the X direction and has a convex shape toward the concave cylindrical surface when viewed from the Y direction, and the curved cutting edge is viewed from the X direction. Is held on the tool post in a state of being inclined with respect to the Z direction,
Of the Y direction, the combined direction of the Y direction and the Z direction, the combined direction of the Y direction and the X direction, and the combined direction of the Y direction, the Z direction, and the X direction. By moving it to either of the above, while the cutting edge of the curved cutting edge is displaced and the cutting point on the generatrix is displaced with respect to the generatrix on the surface of the concave cylindrical surface along the Z direction when viewed from the X direction, A cutting method for cutting concave cylindrical surfaces.

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