JP2018008323A - Cutting processing device, cutting tool, processing support device and processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cutting processing device, a cutting tool, a processing support device, and a processing method capable of high efficiency processing by improving the roughness of a processing surface formed of a curved surface shape.SOLUTION: A plurality of cutting parts 71 project on a circumference of a bottom part of an end mill 7. Each of the cutting parts 71 comprises a nose part cutting edge 72 and a wiper part cutting edge 73 continuous with it. Assuming a curvature of a curve forming a convex toward a target processing surface TS is positive and a curvature of a curve forming a concave is negative, the nose part cutting edge 72 has a curvature sufficiently larger than a curvature 1/Rw in a feeding direction of the target processing surface TS, and the wiper part cutting edge 73 has a curvature sufficiently smaller than the curvature of the nose part cutting edge 72 and slightly larger than the curvature 1/Rw in the feeding direction of the target processing surface TS. For forming a finishing surface 61 on a cutting object 6, the end mill 7 rotates and moves in the feeding direction while changing its attitude so that a finishing surface generating part of the wiper part cutting edge 73 substantially coincides with the target processing surface TS.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a cutting device, a cutting tool, a processing support device, and a processing method for generating a machining surface having a predetermined radius of curvature in a feed direction by cutting.

  There has been a conventional technique related to a milling cutter in which a cutting insert provided so that a wiper portion is continuous with respect to a nose portion (see, for example, Patent Document 1). In this milling cutter, the workpiece is cut by the nose portion and the wiper portion, and the finished surface is formed by the wiper portion. In the conventional milling cutter, regenerative chatter vibration during cutting can be reduced by the nose portion having a small curvature radius. At the same time, the wiper portion having a large radius of curvature connected to the nose portion can improve the surface roughness of the machined surface after cutting even if the cutter feed is increased.

JP 2005-103710 A

Yoshimi Takeuchi, Manabu Nagasaka, Koichi Mori Shige: 5-axis control machining using the tip and side cutting edges of a ball end mill, Journal of Precision Engineering, Vol. 61, no. 4, 1995, p. 561-565

  However, the above-described milling cutter according to Patent Document 1 is used only for cutting processing in which feeding is given along a linear tool path, and the milling cutter is fed along a curved tool path. It could not be applied to cutting. On the other hand, there has been a cutting method that uses a multi-axis machine to improve the roughness of the finished surface with a large pick feed by means of the straight edge portion of the tool (for example, see Non-Patent Document 1 above). However, in the cutting method according to Non-Patent Document 1, since the long cutting edge of the cutter has a regenerative effect, there is a problem that chatter vibration stability during processing decreases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cutting device, a cutting tool, and a processing support device that improve the roughness of a processing surface formed by a curved surface shape and enable high-efficiency processing. And providing a processing method.

  In order to solve the above-described problem, the invention of the cutting device according to claim 1 is directed to a curved target machining surface (TS) having a predetermined curvature (1 / Rw) in the feed direction in the workpiece (6). ) Is generated by cutting, and when the curvature of the convex curve toward the target machining surface is positive and the curvature of the concave curve is negative, a positive first A curved nose portion cutting edge (72, 82, 91a, 91f) having a curvature (1 / Rn) of 1 and a cutting edge that is continuous with the nose portion cutting edge and has a longer cutting edge length than the nose portion cutting edge The blade has a second curvature (1 / Rt) that satisfies the condition that the difference between the curvature of the target machining surface and the curvature of the target machining surface is within a predetermined range in the feed direction. Curved wiper part cutting edge (73, 83, 91 , 91g) and a finished surface generating portion formed by sweeping the wiper part cutting edge by a cutting motion when machining with the cutting tool (7, 8, 9, 9A). A posture changing unit that changes the posture of the cutting tool with respect to the workpiece in the feed direction so as to match the surface.

  According to this configuration, the regenerative effect can be suppressed and chatter vibration can be reduced by cutting using the nose portion cutting edge. Further, the wiper part cutting edge is formed by a curve having a curvature within a predetermined range with respect to the curvature in the feed direction of the target machining surface, and the posture in which the surface where the wiper part cutting edge is swept matches the target machining surface. Is changed in the feed direction to feed along the curved surface of the target machining surface. As a result, it is possible to increase the feed amount, realize high-efficiency machining, and improve the finished surface roughness.

  In addition, in the invention of the cutting apparatus according to claim 1 described above, the “curved nose portion cutting edge having a predetermined curvature” includes a sharp nose portion cutting edge or a polygonal shape whose tip does not have a curve. Includes nose cutting edge. The same applies to the nose portion cutting edge in the invention of the cutting tool according to claim 6 described later and the nose portion cutting edge in the invention of the processing method according to claim 10.

  Further, the second curvature (1 / Rt satisfying the condition that the difference between the curvature of the target machining surface and the curvature of the target machining surface is not less than a predetermined range in the feeding direction. In the range having the effect of the present invention that the finished surface roughness can be improved, the curved wiper part cutting edge having a) has a curvature slightly different from the curvature in the feed direction of the target machining surface. It includes a wiper section cutting edge formed by a curved line. Therefore, if the radius of curvature of the curve convex toward the target machining surface is positive and the radius of curvature of the concave curve is negative, the curvature radius of the wiper part cutting edge is The radius of curvature is slightly smaller than the radius of curvature in the feed direction. The same applies to the wiper part cutting edge in the invention of the cutting tool according to claim 6 described later and the wiper part cutting edge in the invention of the processing method according to claim 10. The surface including the wiper portion cutting edge is generally perpendicular to the cutting direction, but often has a slight inclination. This inclination includes an inclination around the feed direction (rake angle) and an inclination around the cutting direction (inclination angle). If it is not perpendicular to the cutting direction, the curvature measured in the feed direction of the sweep shape (curved surface) by the cutting motion of the cutting edge corresponds to the curvature of the wiper part cutting edge described above, and the curvature of the cutting edge itself is not Disappear. If a magnitude comparison is made based on the radius of curvature, a contradiction occurs when the sign changes. However, in the present invention, since the magnitude of the curvature is compared, no contradiction occurs.

  Further, in “matching the target machining surface” in claim 1, the surface where the wiper part cutting edge is swept is a machining surface within the range having the effect of the present invention that the finished surface roughness can be improved. The case where it is not completely matched is included. The same applies to the wiper part cutting edge in the invention of the processing method according to claim 10 described later.

  Further, the invention of the cutting tool according to claim 6 is a cutting tool (7, 8, 9) for generating a curved target machining surface (TS) having a predetermined curvature (1 / Rw) in the feed direction by cutting. 9A), a curve having a first positive curvature (1 / Rn) where the curvature of the curve convex toward the machining surface is positive and the curvature of the concave curve is negative. A nose part cutting edge (72, 82, 91a, 91f) and a cutting edge which is continuous with the nose part cutting edge and has a cutting edge length longer than the nose part cutting edge, and the target machining surface in the feed direction Curve-shaped wiper part cutting edges (73, 83, having a second curvature (1 / Rt) satisfying the condition that the difference from the curvature of the target machining surface is within a predetermined range. 91b, 91g).

  Thereby, the reproduction effect can be suppressed and the chatter vibration can be reduced by cutting using the nose portion cutting edge. Also, if the position of the wiper part cutting edge is changed so that the surface swept by the cutting motion matches the machining surface, and the feed is given along the curved surface of the target machining surface, the feed amount is increased. In addition, a cutting tool capable of realizing high-efficiency machining and improving the finished surface roughness can be obtained.

  Moreover, invention of the process assistance apparatus (2) which produces | generates the process data which concerns on Claim 9 is a cutting apparatus (1) of Claim 3. WHEREIN: Based on the curvature which each said cutting tool has, each said cutting A curvature range (1 / Rs1, 1 / Rs2, 1 / Rs3) that can be cut by the tool is set, and based on the curvature range and product drawing data, each of the target machining surfaces is set to one of the curvature ranges. A machining surface dividing unit (S101) that divides into a plurality of corresponding regions, and a tool setting unit that applies the cutting tool to be used to each part of the target machining surface based on the divided regions ( S102), based on the fitted cutting tool and the product drawing data, a feed amount setting unit (S104) for setting the feed amount (f) of the cutting tool, and the fitted cutting tool and the product drawing data. Base Includes the a posture setting section for setting the orientation of the cutting tool with respect to the cuttings (S105), the.

  Thereby, a tool to be used can be selected from a plurality of usable cutting tools based on the shape of the target machining surface TS. That is, by forming machining data that can substantially match the surface where the wiper part cutting edge has been swept to the target machining surface, high-efficiency machining can be realized and the finished surface roughness can be improved. Processing can be automated.

  The invention of the machining method according to claim 10 is for generating a curved target machining surface (TS) having a predetermined curvature (1 / Rw) in the feed direction by cutting in the workpiece (6). The nose portion having a positive first curvature (1 / Rn) when the curvature of the curve convex toward the target machining surface is positive and the curvature of the concave curve is negative. A cutting edge (72, 82, 91a, 91f) and a cutting edge that is continuous with the nose part cutting edge and has a cutting edge length longer than the nose part cutting edge, and the curvature of the target machining surface in the feed direction ( 1 / Rw) or more and a curved wiper part cutting edge (73, 83, 91b, 91g) having a second curvature (1 / Rt) that satisfies the condition that the difference from the curvature of the target machining surface is within a predetermined range. Cutting tools (7, 8, 9, A) is used to operate at least one of the cutting tool and the workpiece to cut the workpiece, and the finished surface generation portion of the surface swept by the wiper portion cutting edge is the target. By moving at least one of the cutting tool and the workpiece while changing the posture of the cutting tool relative to the workpiece so as to match the machining surface, the cutting tool is moved to the machining surface. Are moved relative to each other in the feed direction along the curved surface.

  Thereby, the reproduction effect can be suppressed and the chatter vibration can be reduced by cutting using the nose portion cutting edge. In addition, the wiper part cutting edge is formed by a curve having a curvature within a predetermined range with respect to the curvature of the target machining surface in the feed direction, and the posture is changed so that the surface swept by the wiper part cutting edge matches the machining surface. The feed is given along the curved surface of the target machining surface. Thereby, while being able to increase feed amount and implement | achieve highly efficient processing, it can be set as the processing method which can improve finishing surface roughness.

The block diagram showing the whole cutting system by Embodiment 1 of this invention 1 is an external perspective view of the NC machine tool device shown in FIG. Schematic diagram showing the cutting method using the end mill shown in FIG. Part IV enlarged view of FIG. The figure showing the flowchart which showed an example of the processing flow for forming CL data with a CAD / CAM apparatus Enlarged view showing the finished surface after cutting with an end mill Schematic diagram to show how to calculate the radius of curvature of the wiper part cutting edge Schematic diagram to show how to calculate the radius of curvature of the wiper part cutting edge in the pick feed direction Schematic diagram when the end mill shown in Fig. 8 is viewed in the feed direction Schematic diagram of the finished surface cusp of the end mill when only leads are used Diagram showing the finished surface cusp of the end mill when both lead and tilt are included. The enlarged view which showed the cutting part of the end mill by the modification of Embodiment 1. The schematic diagram showing the cutting method of the end mill by Embodiment 2 Schematic diagram for explaining how to set the clearance angle in a cutting tool The figure which looked at the cutting tool shown in Drawing 14 from the lower part Enlarged view showing the cutting edge of the insert shown in FIG. The figure which showed other embodiment Partial enlarged view of FIG.

<Configuration of Embodiment 1>
(Configuration of cutting system)
Based on FIG. 1, the cutting system 1 by Embodiment 1 of this invention is demonstrated. The cutting system 1 corresponds to the cutting apparatus of the present invention. As shown in FIG. 1, the cutting system 1 includes a CAD / CAM device 2, an NC data creation device 3, an NC control device 4, and an NC machine tool device 5. The CAD / CAM device 2 corresponds to a processing support device. The CAD / CAM device 2 may be separated into a CAD device and a CAM device. The CAD / CAM device 2 forms CL data, which is data for specifying a moving method of a cutting tool such as an end mill, in accordance with a machining procedure determined based on product drawing data. The CL data is formed by a movement trajectory of a cutting tool moving on the processing surface and a posture vector of the cutting tool at a point on the movement trajectory. The CL data corresponds to the processing data. The CAD / CAM device 2 is preferably one that automatically selects a cutting tool according to the present invention to be described later and automatically generates its operation. In this case, the CAD / CAM device 2 corresponds to the tool selection unit of the present invention. The NC data creation device 3 creates NC data capable of multi-axis control of the NC machine tool device 5 based on the CL data from the CAD / CAM device 2 and supplies the NC data to the NC control device 4. As described above, it is desirable to create NC data with the support of the CAD / CAM device 2 and the NC data creation device 3, but the NC data may be created without the assistance of either or both of them. Further, the CAD / CAM device 2 and the NC data creation device 3 may be integrated into one by limiting the number of control axes and the machining shape, or may be integrated into the NC control device. In this case, the CAD / CAM device 2 and the NC data creation device 3 or the NC data creation device 3 correspond to the tool selection unit of the present invention. The NC control device 4 controls the NC machine tool device 5 shown in FIG. 2 in accordance with the NC data formed by the NC data creation device 3.

(Configuration of NC machine tool device)
Hereinafter, the NC machine tool device 5 will be described with reference to FIG. As shown in FIG. 2, the horizontal direction in FIG. 2 is the X-axis direction of the NC machine tool device 5, and the vertical direction is perpendicular to both the Z-axis direction, the X-axis direction, and the Z-axis direction of the NC machine tool device 5. Is the Y-axis direction of the NC machine tool device 5. The NC machine tool device 5 is formed by a machining center capable of simultaneous multi-axis control. The NC machine tool device 5 includes a column 51 and a Y-axis feed table 52 provided on the base 50, and an X-axis feed table 55 provided on the Y-axis feed table 52. The Y-axis feed table 52 engages with a Y-axis rail 50a formed on the base 50, and is supported so as to be movable in the Y-axis direction with respect to the base 50. The base 50 is provided with a ball screw mechanism 53A, and a Y-axis motor 54A is attached to the ball screw mechanism 53A. The Y-axis motor 54A corresponds to a pick feed unit. The Y-axis motor 54A incorporates a Y-axis sensor (not shown) that detects its rotational position. The NC control device 4 described above controls the operation of the Y-axis motor 54A based on the value detected by the Y-axis sensor, and moves the Y-axis feed table 52 in the Y-axis direction (in this embodiment, the pick-feed direction (feed direction and later described). Corresponding to the direction perpendicular to both normal directions of the target machining surface TS to be moved).

  An X-axis feed table 55 is provided on the Y-axis feed table 52. The X-axis feed table 55 is engaged with an X-axis rail 52a formed on the Y-axis feed table 52, and is supported so as to be movable in the X-axis direction with respect to the Y-axis feed table 52. The Y-axis feed table 52 is provided with a ball screw mechanism 53B, and an X-axis motor 54B is attached to the ball screw mechanism 53B. The X-axis motor 54B corresponds to a tool feeder. The X-axis motor 54B incorporates an X-axis sensor (not shown) that detects its rotational position. The NC control device 4 controls the operation of the X-axis motor 54B based on the value detected by the X-axis sensor, and moves the X-axis feed table 55 in the X-axis direction (in this embodiment, in the feed direction as will be described later). Move to the appropriate). Even in the case where the X-axis direction is the feeding direction, a slight movement also occurs in the Z-axis direction because of the curved shape. A workpiece 6 to be described later is fixed on the table 55.

  A spindle support portion 56 is attached to the Z-axis rail 51b formed in the column 51 via a Y-axis rotation angle motor 54D and an X-axis rotation angle motor 54F so as to be movable in the Z-axis direction with respect to the column 51. . The Y-axis rotation angle motor 54D rotates the main shaft support 56 around the Y axis. The X-axis rotation angle motor 54F rotates the spindle support part 56 around the X axis. The Y-axis rotation angle motor 54D and the X-axis rotation angle motor 54F correspond to the posture changing unit of the present invention. Note that in order to change the tool orientation in the feed direction without changing the position of the tool tip (generally the center point of the cutting edge arc), the X and Z axes also move greatly, and the tool orientation in the pick feed direction In order to change, the Y axis and the Z axis also move greatly. A ball screw mechanism 53C is provided inside the column 51, and a Z-axis motor 54C is attached to the ball screw mechanism 53C. The Z-axis motor 54C incorporates a Z-axis sensor (not shown) that detects its rotational position. The NC control device 4 controls the operation of the Z-axis motor 54C based on the value detected by the Z-axis sensor, and moves the spindle support portion 56 in the Z-axis direction together with the Y-axis rotation angle motor 54D and the X-axis rotation angle motor 54F. .

  The Y-axis angle motor 54D described above incorporates an angle sensor (not shown) that detects its rotational position. The NC control device 4 controls the operation of the Y axis rotation angle motor 54D based on the detection value by the angle sensor, and rotates the spindle support portion 56 around the Y axis with respect to the column 51. The Y-axis rotation angle motor 54D controls to change the posture in the feed direction, and the X-axis rotation angle motor 54F controls to change the posture in the pick feed direction. Further, instead of rotating the spindle support portion 56, the workpiece 6 may be rotated.

  A chuck device 57 is provided at the lower end of the spindle support portion 56, and the end mill 7 is attached to the chuck device 57. A spindle motor 54E is attached to the upper end of the spindle support portion 56, and the spindle motor 54E rotates the end mill 7 together with the chuck device 57. The spindle motor 54E has a built-in spindle sensor, and the NC control device 4 controls the operation of the spindle motor 54E based on the detection value of the spindle sensor. The end mill 7 corresponds to a cutting tool.

  A tool change unit 58 and a tool magazine 59 are attached to the side surface of the column 51. The tool magazine 59 is a device that accommodates one or more waiting cutting tools, and includes an end mill 7 for cutting the workpiece 6, and includes a plurality of different tool diameters, tool material types, cutting edge shapes, and the like. The cutting tools 7A and 7B are formed so as to be stockable. The tool change unit 58 is a device for replacing one of the waiting cutting tools accommodated in the tool magazine 59 with the cutting tool being used, and corresponds to the tool replacing portion of the present invention. Moreover, the tool magazine 59 corresponds to the tool accommodating part of this invention. The cutting tools 7A and 7B stored in the tool magazine 59 include various types such as an end mill, a face milling cutter, and a reamer. In addition to this, the tool magazine 59 has the same type of cutting tool, but has different curvatures of the wiper part cutting edge 73 described later corresponding to the curved surface shape of each processing part of the workpiece 6. It is housed in multiple stages. When the workpiece 6 is machined, when the cutting process by the end mill 7 is completed, the tool changing unit 58 causes the other cutting tools 7A and 7B stored in the tool magazine 59 to be transferred to the chuck device 57 instead of the end mill 7. After the replacement, the next cutting process is started. The operation of the tool change unit 58 is controlled by the NC control device 4 based on NC data created based on the shape of the processed surface of the workpiece 6.

(Configuration of end mill and processing method using end mill)
Hereinafter, based on FIG. 3 and FIG. 4, the structure of the end mill 7 and the processing method using the end mill 7 are demonstrated. 3 corresponds to the X-axis direction of the NC machine tool device 5 described above, the direction perpendicular to the paper surface corresponds to the Y-axis direction, and the vertical direction corresponds to the Z-axis direction. Further, the description will be made assuming that the lower side in FIG. 3 is the lower side of the end mill 7 and the feed direction of the end mill 7 (right side in FIG. 3 and indicated by a white arrow) is the front side.

  The end mill 7 is formed in a substantially cylindrical shape using high-speed tool steel, cemented carbide, ceramics, or the like, and a cutting portion 71 is provided at the bottom as shown in FIG. In the present embodiment, a plurality of cutting portions 71 are formed on the circumference of the end mill 7. However, the end mill 7 is not limited to this embodiment, and may be a single-edged cutting tool. The end mill 7 according to the present embodiment is a cutting tool for forming a target machining surface TS formed by a concave curved surface having a predetermined curvature radius Rw in the feed direction on the workpiece 6 by bottom edge machining. . The target machining surface TS is a shape on the product drawing that the cutting system 1 aims for cutting. The target machining surface TS corresponds to a curved machining surface. In the present specification, the curvature or radius of curvature of a curve that protrudes toward the target machining surface TS is positive, and the curvature or radius of curvature of a concave curve is negative.

  As shown in an enlarged manner in FIG. 4, each cutting portion 71 has a nose portion cutting edge 72 and a wiper portion cutting edge 73 smoothly and continuously behind the nose portion cutting edge 72. In the end mill 7, the workpiece 6 is cut by the nose portion cutting edge 72 and the wiper portion cutting edge 73, and the finished surface is formed by the wiper portion cutting edge 73. The nose portion cutting edge 72 is formed in a curved shape having a positive curvature 1 / Rn that is sufficiently larger than the curvature 1 / Rw in the feed direction of the target machining surface TS. The curvature 1 / Rn of the nose portion cutting edge 72 is set to be sufficiently large so as to suppress the reproduction effect and reduce chatter vibration. Further, the large curvature 1 / Rn has an effect of reducing the cutting force by shortening the cutting edge length involved in cutting, and suppressing static deformation and forced vibration. The tip of the nose portion cutting edge 72 may have a sharp shape without having a curve.

  On the other hand, the wiper portion cutting edge 73 has a curved shape having a curvature 1 / Rt that is sufficiently smaller than the curvature 1 / Rn of the nose portion cutting edge 72 and slightly larger than the curvature 1 / Rw in the feed direction of the target machining surface TS. Is formed. The curvature 1 / Rt of the wiper portion cutting edge 73 may substantially coincide with the curvature 1 / Rw in the feed direction of the target machining surface TS. The wiper portion cutting edge 73 is a curved shape having a positive first curvature (1 / Rn) when the curvature of the curve that is convex toward the target machining surface TS is positive and the curvature of the concave curve is negative. The cutting edge is continuous with the nose part cutting edge 72 and has a longer cutting edge length than the nose part cutting edge 72, and is equal to or greater than the curvature (1 / Rw) of the target machining surface TS in the feed direction. A curved shape having a second curvature (1 / Rt) that satisfies the condition that the difference between the two values is within a predetermined range is applicable. That is, 1 / Rt ≧ 1 / Rw and the difference is within a predetermined range, and the difference is preferably as small as possible. The predetermined range refers to a range having the effect of the present invention that the finished surface roughness can be improved.

  Note that the target machining surface TS, the nose portion cutting edge 72, and the wiper portion cutting edge 73 described so far have a curved shape in the left-right direction in FIG.

  As shown in FIG. 3, an uncut portion 62 is present on the workpiece 6 so as to be continuous with the concave finish surface 61 already formed by cutting. In the state shown in FIG. 3, the cutting part 71 is in the process of cutting the uncut part 62 from now on. At this time, the nose portion cutting edge 72 of the end mill 7 is positioned forward in the feed direction with respect to the wiper portion cutting edge 73.

  In order to form the finished surface 61 on the workpiece 6, the end mill 7 is rotated around its central axis φ by the spindle motor 54 </ b> E of the NC machine tool device 5 described above. When the end mill 7 is rotated by the spindle motor 54E, the nose portion cutting edge 72 and the wiper portion cutting edge 73 can cut the workpiece 6. Further, since the workpiece 6 is moved in the X-axis direction (left side in FIG. 3) by the X-axis motor 54B, the end mill 7 moves relative to the workpiece 6 while rotating. The end mill 7 moves in the aforementioned feed direction along the curved surface of the target machining surface TS (feed). When the end mill 7 advances in the feed direction, the posture of the workpiece 6 with respect to the workpiece 6 is changed so that the surface swept by the wiper portion cutting edge 73 by the rotation (cutting motion) substantially matches the target machining surface TS. That is, as the end mill 7 moves to the right in FIG. 3, the cutting portion 71 at the lower end portion swings to the right with respect to the upper end portion corresponding to the position on the target machining surface TS generated by cutting. It will be moved. In FIG. 3, the position and orientation of the end mill 7 at a certain time are indicated by broken lines, and the position and orientation of the end mill 7 after a predetermined time are indicated by solid lines. The swing of the end mill 7 is executed by the Y-axis rotation angle motor 54D described above. At the same time, the end mill 7 also moves in the Z-axis direction by the Z-axis motor 54C corresponding to the position on the target machining surface TS that is being cut.

  When the end mill 7 is sent to the end of the workpiece 6, the workpiece 6 is moved by a predetermined pitch in the Y-axis direction by the Y-axis motor 54A. As a result, the end mill 7 moves relative to the workpiece 6 (pick feed). The end mill 7 that has been pick-feeded moves in the opposite direction (leftward in FIG. 3) along the target machining surface TS while rotating around the central axis φ. Also in this case, the end mill 7 changes its posture so that the finished surface generation portion of the wiper portion cutting edge 73 substantially matches the target machining surface TS. Alternatively, in order to avoid the deterioration of the roughness of the finished surface 61 due to the change in the motion error characteristic of the machine tool, the workpiece 6 may not be processed when moving to the left in FIG. Hereinafter, the end mill 7 forms the finished surface 61 by reciprocating on the workpiece 6. Further, generation of the finished surface 61 having a curvature 1 / Rw in the feeding direction (however, 1 / Rw is not limited to a practical value and may be in a range close to 1 / Rt that does not exceed 1 / Rt). When the end mill 7 is replaced with the other cutting tools 7A and 7B on the tool magazine 59 by the tool changing unit 58, the other parts of the workpiece 6 are cut.

  In some cases, the tool magazine 59 does not contain (hold) a cutting tool having a curvature that matches the curvature 1 / Rw in the feed direction of the target machining surface TS. In this case, the NC control device 4 is closest to the curvature (1 / Rw) of the target machining surface TS among the cutting tools housed in the tool magazine 59 based on the CL data formed by the CAD / CAM device 2. The target machining surface TS is cut using a cutting tool having a curvature (1 / Rt). Specifically, the curvature of the wiper part cutting edge is greater than or equal to the curvature of the machining surface (1 / Rw) among a plurality of usable (that is, standby or in use) cutting tools and the difference from the curvature of the machining surface. A cutting tool that satisfies the condition of the second curvature (1 / Rt) that is within a predetermined range and that has the smallest difference is selected.

  In FIG. 3, when feeding the workpiece 6 to the end mill 7 and changing the posture of the end mill 7 with respect to the workpiece 6, the workpiece 6 is moved instead of the end mill 7. Alternatively, both the end mill 7 and the workpiece 6 may be moved.

  Further, in the embodiment shown in FIG. 3, when the end mill 7 is fed, the finish surface generation portion (the portion in the processing region) of the ridge line of the wiper portion cutting edge 73 is substantially parallel to the minute portion of the target processing surface TS. It is moved to become. However, in order to prevent the wiper part cutting edge 73 from coming into contact with the previously cut surface 61 again, the nose part cutting edge 72 is slightly cut with respect to the target machining surface TS, and the rear of the wiper part cutting edge 73 is inserted. The target machining surface TS may be slightly separated. Alternatively, the burnishing may be performed by slightly biting, and the wiper portion cutting edge 73 is again in contact with and pressed against the previously finished finishing surface 61.

  The operation control of the end mill 7 described so far is executed by the NC control device 4 based on the NC data converted from the CL data formed by the CAD / CAM device 2 described above. Hereinafter, an example of a processing flow for forming CL data for realizing the above-described operation control by the CAD / CAM device 2 illustrated in FIG. 5 will be described. First, in step S101, based on the product drawing data and the curvature each of the cutting tools 7, 7A, 7B accommodated in the tool magazine 59, the target machining surface TS is divided into a plurality of regions each having a predetermined curvature range. Divide (processed surface dividing step). Specifically, the curvature 1 / Rw in the feed direction of the target machining surface TS is analyzed, and the distribution of the curvature 1 / Rw on the target machining surface TS (1 / R1 ≧ 1 / Rw> 1 / R4) is obtained. In other words, a tool with a maximum of 1 / R1 is prepared and a range up to a minimum of 1 / R4 is set. The curvatures of the wiper part cutting edges 73 of the cutting tools 7, 7A, 7B held by the NC machine tool device 5 are 1 / R1, 1 / R2, 1 / R3 (1 / R1> 1 / R2> 1 / R3), the curvature ranges 1 / Rs1, 1 / Rs2, and 1 / Rs3 that can be cut by the cutting tools 7, 7A, 7B are respectively 1 / R1 ≧ 1 / Rs1> 1 / R2, 1 / R2 ≧. 1 / Rs2> 1 / R3 and 1 / R3 ≧ 1 / Rs3> 1 / R4 are set. As can be seen from the above, the respective curvature ranges 1 / Rs1, 1 / Rs2, and 1 / Rs3 correspond to the curvatures 1 / R1, 1 / R2, and 1 of the wiper portion cutting edge 73 of each cutting tool 7, 7A, and 7B. / R3 or less and set to be within a predetermined range. Next, the target machining surface TS is divided into a plurality of regions corresponding to any one of the curvature ranges 1 / Rs1, 1 / Rs2, and 1 / Rs3. In the above calculation, instead of the curvature 1 / Rw in the feed direction of the target machining surface TS and the curvature 1 / R1, 1 / R2, 1 / R3 of the wiper part cutting edge 73 of the cutting tools 7, 7A, 7B, Each radius of curvature may be used. In actual machining, if the tool cannot be used due to other constraints such as tool-work material interference, the constraint of the curvature in the pick feed direction described later, or there is a region with a small curvature and a small area in a continuous curved surface. If there is a tool with a small curvature and the feed amount is increased, the machining time can be shortened against the required roughness by machining the area by reducing the feed amount without changing the tool. A tool with a large curvature may be selected.

  Next, in step S102, any one of the cutting tools 7, 7A, 7B to be used is automatically applied to each part of the target machining surface TS based on the divided areas (tool setting step). ). At this time, if the tool magazine 59 does not hold a cutting tool having a curvature that matches the curvature 1 / Rw of the target machining surface TS, the target machining surface TS among the held cutting tools 7, 7A, 7B. It is possible to apply a cutting tool having the closest curvature within a range that does not fall below the curvature 1 / Rw. Next, in step S103, it is confirmed whether or not the feed direction and the pick feed direction on the workpiece 6 are appropriate according to the applied cutting tools 7, 7A, 7B (feed direction confirmation step). Here, the pick feed direction must satisfy the curvature constraint as well as the feed direction. As a constraint condition of the curvature, 1 / Re ≧ 1 / Rp is always satisfied. Here, as will be described later, 1 / Re is the curvature in the pick feed direction of the surface of the wiper portion cutting edge 73 swept by the cutting motion (tool rotational motion), and 1 / Rp is the pick feed of the target machining surface TS. The curvature of the direction. Here, the constraint condition 1 / Re ≧ 1 / Rp is confirmed. If the constraint condition is not satisfied, a tool having a larger curvature and having the smallest curvature among the tools satisfying the constraint condition is newly added. Apply to If there is no tool that satisfies the conditions, a normal tool having no wiper part may be selected, or an alarm or the like may be displayed to interrupt the processing flow.

  Next, another processing flow from the process surface dividing step to the feed direction confirmation step will be described. The curvature 1 / Rw in the feed direction of the target machining surface TS and the curvature 1 / Rp in the pick feed direction are analyzed, and their curvature distribution is obtained. Here, the curvature 1 / Rt in the feed direction of the wiper portion cutting edge 73 and the curvature 1 / Re in the pick feed direction of the surface on which the cutting edge 73 is swept are always 1 / Rt ≧ 1 / Rw (feed direction) as a constraint condition. ), 1 / Re ≧ 1 / Rp (pick feed direction), and the differences 1 / Rt−1 / Rw and 1 / Re−1 / Rp are preferably small. As a specific example, when the product of the difference (1 / Rt-1 / Rw) (1 / Re-1 / Rp) is minimized from the equation (8), the processing time is minimized with respect to a given Rth. (Maximum machining efficiency). Thus, based on the curvature distribution, for the cutting tools 7, 7A, 7B held by the NC machine tool device 5, each tool obtains a machining surface area that satisfies the above two constraint conditions, and a plurality of tools satisfy the constraint conditions. (1 / Rt−1 / Rw) (1 / Re−1 / Rp) (when the curvature changes, √ ((1 / Rt−1 / Rw) (1 / Re− A tool that minimizes the area fraction value 1 / Rp)) is applied. Thereby, the target machining surface TS is divided (machining surface dividing step), and an appropriate tool is applied to each machining surface region (tool setting step). At this time, if it is possible to reduce the machining time for a given Rth by machining a neighboring area without using a tool having a larger curvature without changing the tool, the areas can be combined. good. If there is no tool that satisfies the conditions, a normal tool that does not have a wiper unit may be selected, or an alarm or the like may be displayed to interrupt the processing flow. In addition, a process for confirming (searching) whether there is a more appropriate direction by changing the set feed direction and pick feed direction may be executed (feed direction confirmation step). As a result, a tool having a smaller curvature can be applied, or even if the same tool is used, the value of (1 / Rt-1 / Rw) (1 / Re-1 / Rp) If the value can be reduced, the information is displayed and you are asked to enter the appropriateness of processing continuation, or the feed direction and pick feed direction are automatically changed and processed again from the machining surface division process. You can fix it.

  Next, in step S104, based on the applied cutting tools 7, 7A, 7B and the product drawing data, the feed amount per blade of the cutting tools 7, 7A, 7B so as to satisfy the required roughness of the finished surface 61 f and pick feed amount Pf are set (feed amount setting step). Finally, in step S105, based on the applied cutting tool 7, 7A, 7B and product drawing data, the surface to be cut is made to match the finished surface generation portion of the surface swept by the wiper portion cutting edge 73 with the target processing surface TS. The CL data is completed by setting the postures of the cutting tools 7, 7 </ b> A, 7 </ b> B with respect to the respective processing parts of the object 6 (posture setting step).

(How to set the radius of curvature of the wiper cutting edge)
Hereinafter, based on FIG. 6 and FIG. 7, the setting method of the curvature radius Rt of the wiper part cutting edge 73 is demonstrated. As shown in FIG. 6, cusp height Rth (hereinafter referred to as theoretical roughness Rth) remains on the finished surface 61 of the end mill 7 for each blade of the wiper portion cutting edge 73 with respect to the target machining surface TS. The surface roughness of the finished surface 61 becomes rough. In general, the theoretical roughness Rth is given by the following approximate expression when the radius of curvature of the wiper portion cutting edge 73 is Rt when performing linear feed. However, in the following formula, f is a feed amount per blade of the end mill 7.

  Therefore, from the above equation (1), the following equations (2) and (3) are established in FIG.

  From these, the theoretical roughness Rth can be obtained by the following equation.

  In order to improve the roughness on the finished surface 61, the equation (4) is such that the radius of curvature Rt of the wiper portion cutting edge 73 forming the finished surface 61 coincides with the radius of curvature Rw in the feed direction of the target machining surface TS. Or a very close value. In addition, when the roughness on the finished surface 61 is maintained at the same level, it means quantitatively that high-efficiency machining can be realized by increasing the feed amount f.

  For example, a conventional tool that does not have the wiper part cutting edge 73 and the end mill 7 having a radius of curvature of the nose part cutting edge 72 of 1 mm is used, and the tool posture is such that the finished surface 61 is formed by the nose cutting edge 72. If a target machining surface TS having a radius of curvature Rw = 50 mm is machined with a feed amount f = 0.2 mm, the theoretical roughness Rth = 4.9 μm is obtained from the equation (4). On the other hand, assuming that the end mill 7 having the wiper part cutting edge 73 and having a radius of curvature Rt = 40 mm is used and machining is performed under the same conditions by a tool posture in which the finished surface 61 is formed by the wiper part cutting edge 73. The theoretical roughness Rth = 0.025 μm, and the theoretical roughness Rth decreases to nearly 1/200. On the other hand, when the roughness on the finished surface 61 is maintained at the same level, the feed amount f is 2.8 mm, and high-efficiency machining 14 times is possible.

  Here, conditions for minimizing the machining time will be described. An MRR (Material Removal Rate) representing the machining efficiency is proportional to the feed amount f and the pick feed amount Pf as shown in the equation (5).

  On the other hand, since the following equation (6) can be obtained from the equation (4), and the relationship between the pick feed amount and the theoretical roughness can be obtained from an equation similar to the equation (4), the following (7) An expression can be derived.

  From the above three equations, MRR can be expressed by the following equation (8).

  Equation (8) shows how much the machining efficiency increases when the product (1 / Rt−1 / Rw) (1 / Re−1 / Rp) of the difference between the curvatures is reduced. Therefore, it can be seen that in order to maximize the machining efficiency with respect to the target Rth, that is, to minimize the machining time, it is necessary to minimize the product of the differences between the respective curvatures. Equation (8) indicates that the machining time is proportional to √ ((1 / Rt−1 / Rw) (1 / Re−1 / Rp)), and a curved surface with a constant curvature is represented by a certain theoretical roughness. It can be seen that the time required for finishing is proportional to the value obtained by dividing √ ((1 / Rt−1 / Rw) (1 / Re−1 / Rp)) on the surface.

  Hereinafter, the case where the target machining surface TS is formed in a curved surface having a predetermined radius of curvature Rp in the pick feed direction will be described with reference to FIGS. 8 and 9. In FIG. 8, the feed direction of the end mill 7 is rightward and is indicated by a white arrow. In FIG. 8, the pick feed direction is a direction perpendicular to the paper surface. In FIG. 9, the left-right direction is the pick feed direction, and the feed direction is the direction perpendicular to the paper surface.

  Hereinafter, a method of setting the curvature 1 / Re of the surface on which the wiper part cutting edge 73 is swept with respect to the curved surface in the pick feed direction of the target processing surface TS will be described. Similarly to the curvature 1 / Rt of the wiper portion cutting edge 73 with respect to the curvature 1 / Rw in the feed direction of the target machining surface TS described above, the wiper portion cutting edge 73 with respect to the curvature 1 / Rp in the pick feed direction of the target machining surface TS is swept. The curvature 1 / Re of the formed surface is also set as follows. That is, when the curvature of the curve that is convex toward the target machining surface TS is positive and the curvature of the concave curve is negative, the curvature in the pick feed direction of the target machining surface TS is 1 / Rp or more, and is within a predetermined range. Is set to have a curvature 1 / Re. The predetermined range refers to a range having the effect of the present invention that the finished surface roughness can be improved.

  Further, when the finished surface 61 is formed, the attitude of the end mill 7 with respect to the workpiece 6 is changed in the pick feed direction so that the surface on which the wiper portion cutting edge 73 is swept substantially matches the target processing surface TS.

  Hereinafter, a method of calculating the curvature radius Re in the pick feed direction of the surface on which the above-described wiper portion cutting edge 73 has been swept will be described. As shown in FIG. 8, the center point of the wiper part cutting edge 73 forming the finish surface 61 is C. Approximately, the connection point between the nose portion cutting edge 72 and the wiper cutting edge 73 may be C. When a circle formed by rotating and sweeping the point C is defined as Q, the minor axis radius of the ellipse Qe when the circle Q is viewed in the feed direction tangent L direction of the target machining surface TS is represented by Ra (cos η). The However, Ra represents the rotation radius of the point C, and η represents the angle formed between the rotation axis φ of the end mill 7 and the tangent L. Therefore, the radius of curvature Re of the ellipse Qe at the point C is represented by Re = Ra / (cos η). Therefore, a tool in which Ra and η are set is selected so that the curvature radius Re of the surface on which the wiper portion cutting edge 73 is swept substantially matches the curvature radius Rp in the pick feed direction of the target machining surface TS. In the case of milling, it is desirable to select a direction that satisfies the constraints and has a similar curvature in the pick feed direction as described above.

  In the above description, the simple example in which the tangent line L and the feed direction coincide and the tangent line L and the pick feed direction are orthogonal to each other has been described. In other words, the example in which the rotation axis φ of the end mill is tilted only in the feed direction (example of only the lead) has been described. However, practically, there is a case (tilt) in which it also falls in the pick feed direction. In this case, in FIG. 8 and FIG. 9, it can be defined that a perpendicular line H is drawn on the machining surface TS at the point C, and the tool 7 rotates around the perpendicular line H by an angle ζ. This is equivalent to rotating the feed direction and the pick feed direction around H by an angle −ζ. From the viewpoint of the latter, as is apparent from FIGS. 8 and 9, since the curvature radii Rt and Re of the wiper portion do not change, there is no change in the tool selection method with respect to the target machining surface, and the feed direction as a premise. The pick feed direction is rotated by an angle −ζ. In addition, when the case where the correction is made in S103 and the process returns to the beginning is taken into consideration, the “corrected” direction may be included. Here, FIG. 10 schematically shows the finished surface cusp generated by the end mill when only the lead is included, and FIG. 11 schematically shows the finished surface cusp generated by the end mill when both the lead and tilt are included. Show. The line in the figure shows the cusp ridge. Further, in order to generate a finished surface having the same theoretical roughness as when ζ = 0 (when tilting is not performed), as shown in FIG. 11, the feed amount increases by 1 / cos (−ζ) times. Since the pick feed amount is reduced by a factor of cos (−ζ), there is no change in the machining efficiency.

  In the first embodiment, since the feed amount f can be made extremely large, the shoulder portion existing between the flank surface of the end mill 7 and the finished surface 61 and the uncut portion 62, which are surfaces just processed. In order to avoid interference with the existing cutting tool, it is necessary to make the clearance angle larger than that of the existing cutting tool. Since the clearance angle setting method has been described in detail in the second embodiment to be described later, the description thereof will be omitted in this embodiment.

(Configuration of end mill according to modification of embodiment 1)
As a modification of the cutting part 71 of the end mill 7, as shown in FIG. 12, a configuration having a burnishing part 74 may be adopted. The burnishing part 74 is provided so as to be continuous with respect to the wiper part cutting edge 73 with respect to the rear part of the wiper part cutting edge 73 at a position opposite to the nose part cutting edge 72. The burnishing part 74 is formed by a curve or a straight line having the same radius of curvature as the wiper part cutting edge 73. The burnishing part 74 may be formed by extending the rear end part of the wiper part cutting edge 73. The burnishing part 74 can burn and finish the finishing surface 61 by mainly pressing the finishing surface 61 formed by the wiper part cutting edge 73.

<Effect of Embodiment 1>
The processing system 1 of the present embodiment is a cutting device for cutting a curved target processing surface (TS) having a predetermined curvature (1 / Rw) in the feed direction in the workpiece 6, A curved nose portion cutting edge 72 having a positive first curvature (1 / Rn), where the curvature of the curve convex toward the target machining surface is positive and the curvature of the concave curve is negative; and A cutting edge that is continuous with the nose portion cutting edge 72 and has a longer cutting edge length than the nose portion cutting edge 72 and is equal to or larger than the curvature (1 / Rw) of the target machining surface in the feed direction and the difference from the curvature of the target machining surface And a cutting tool 7 having a curved wiper part cutting edge 73 having a second curvature (1 / Rt) that satisfies the condition that is within a predetermined range, and when the cutting tool 7 performs machining, the wiper part cutting edge 73 sweeps. The finished surface generation part formed by To match the target working surface, and a posture changing unit for changing the attitude of the cutting tool 73 with respect to the cuttings in the feed direction (54D).

  According to the present embodiment, the regenerative effect can be suppressed and chatter vibration can be reduced by cutting using the nose portion cutting edge 72 having a very small positive curvature radius Rn. Further, the wiper part cutting edge 73 is formed by a curve having a curvature radius Rt slightly smaller than the curvature radius Rw in the feed direction of the concave target machining surface TS in the feed direction, and the wiper part cutting edge 73 is swept in the cutting direction. The posture is changed so that the surface substantially matches the target machining surface TS, and feed is given along the curved surface of the target machining surface TS. As a result, it is possible to increase the feed amount f and realize high-efficiency machining, and to improve the finished surface roughness.

  Also, a tool magazine 59 that houses one or more waiting cutting tools 7 and the like, and a tool exchange unit 58 that replaces one of the waiting cutting tools accommodated in the tool magazine 59 with a cutting tool in use. A CAD / CAM device that selects a tool to be used from a plurality of cutting tools that can be used (that is, waiting or in use) based on the shape of the target machining surface TS 2 is provided. That is, the CAD / CAM device 2 forms CL data that allows the surface of the wiper portion cutting edge 73 swept to substantially match the target machining surface TS, thereby realizing high-efficiency machining and finishing. Cutting that can improve surface roughness can be automated.

  In particular, the CAD / CAM device 2 has a curvature of the wiper portion cutting edge 73 out of a plurality of usable (that is, waiting or in use) cutting tools 73 with a curvature (1 / Rw) or more of the target machining surface TS. A tool that satisfies the condition of the second curvature (1 / Rt) that the difference from the curvature of the target machining surface is within a predetermined range is selected.

  Moreover, if the cutting part 71 has the burnishing part 74 which presses in the feed direction with respect to the finishing surface 61, the finishing surface 61 whose roughness is improved by the wiper part cutting edge 73 will be further smoothed. Can do.

  Further, the surface on which the wiper portion cutting edge 73 is swept is substantially matched not only with the feed direction but also with the curved surface in the pick feed direction of the workpiece 6, thereby increasing the pick feed amount. Higher efficiency machining can be realized, and the finished surface roughness on the workpiece 6 can be further improved.

<Configuration of Embodiment 2>
Hereinafter, based on FIG. 13, the end mill 8 by Embodiment 2 is demonstrated. The end mill 8 corresponds to a cutting tool. The end mill 8 is formed in a substantially cylindrical shape, and a plurality of cutting portions 81 are formed on the circumference. Each cutting part 81 is formed mainly on the side surface of the end mill 8, and the end mill 8 is for forming a convex target machining surface TS on the workpiece 6 by side edge machining.

  Each cutting part 81 has a nose part cutting edge 82 and a wiper part cutting edge 83 smoothly and continuously behind the nose part cutting edge 82, similarly to the end mill 7 according to the first embodiment. The nose portion cutting edge 82 has a small positive radius of curvature Rn. The tip of the nose portion cutting edge 82 may have a sharp shape without a curve.

  On the other hand, the wiper portion cutting edge 83 is formed by a curve having a curvature radius Rt slightly smaller than the curvature radius Rw of the target machining surface TS. The radius of curvature Rt is larger in absolute value than Rw, but has a negative value because the curve of the wiper portion cutting edge 83 is concave toward TS, and is similarly smaller than Rw, which is a negative value. Become. The curvature radius Rt of the wiper part cutting edge 83 may substantially coincide with the curvature radius Rw in the feed direction of the target machining surface TS. The target machining surface TS, the nose portion cutting edge 82, and the wiper portion cutting edge 83 are curved in the left-right direction in FIG.

  As in the first embodiment, when the workpiece 6 is cut, the end mill 8 rotates in the feed direction indicated by the white arrow along the curved surface of the target machining surface TS while rotating about the rotation axis φ. Feeded. When the end mill 8 advances in the feed direction, the posture of the end mill 8 is changed so that the curved surface obtained by rotationally sweeping the wiper portion cutting edge 83 matches (contacts) the target machining surface TS. Since the other configuration of the end mill 8 according to the present embodiment is the same as that of the end mill 7 according to the first embodiment, further description thereof is omitted.

  The NC control device 4 moves the cutting tool that rotates to move in the feed direction to generate the finished surface 63, and repeats this movement in the pick feed direction to form the finished surface 63 also in the pick feed direction. In this case, the already machined surface existing between the finished surface 63 just generated and the uncut portion 62 remaining in the pick-feed direction is cut again. In addition, when the thickness (cutting amount) of the uncut portion 62 becomes too large, it is divided into a plurality of times, and the surface layer of the workpiece is scraped off little by little, such as roughing, intermediate finishing, and finishing. . In this case, the uncut portion 62 that is the already machined surface is cut again. When the already machined surface is machined again as described above, the spindle speed is different so that the cutting speed when the already machined surface is cut again by the cutting tool is different from the cutting speed when the uncut portion 62 was formed last time. The motor 54E may be controlled. By doing so, it is possible to deviate the frequency at which the vibration trace left on the processed surface 62 at the previous cutting is reproduced as the thickness variation, and to suppress the growth of chatter vibration.

(Setting method of end mill 8 clearance angle)
As described above, according to the present embodiment, since the feed amount f can be made extremely large, the shoulder existing between the flank face of the end mill 8 and the finished surface 63 just created and the uncut portion 62. In order to avoid interference with the portion (the portion processed by the nose portion cutting edge 82), it is necessary to make the clearance angle larger than that of the existing cutting tool. In particular, when the end mill 8 is multi-edged and has a small diameter, the tendency becomes even more remarkable.

  Hereinafter, a method of setting a clearance angle of a cutting edge 91c that is a cutting edge following the nose portion cutting edge 91a in the cutting tool 9 and located on the opposite side of the wiper portion cutting edge 91b will be described with reference to FIGS. . As shown in FIG. 14, the cutting tool 9 having the insert 91 attached to the tip thereof is rotated along the axis center along the target processing surface TS in order to form the target processing surface TS on the workpiece 6. It moves in the feed direction (the direction of the white arrow in FIG. 14). The insert 91 is formed with a wiper portion cutting edge 91b having a curvature radius Rt. The convex target machining surface TS has a radius of curvature Rw in the feed direction. The advance angle θ (shown in FIG. 15) of the cutting edge 91d of the insert 91 can be expressed by the following equation, where F is the feed speed of the cutting tool 9 per unit time and V is the peripheral speed of the cutting edge.

  However, F = N × f × n and V = π × D × n. Here, N is the number of blades of the end mill tool, n is the tool rotation speed, D is the blade tip position where the clearance angle γ is likely to be a problem in the insert 91 (the innermost position in the radial direction among the cutting blades involved in cutting). ) Shows the diameter. Further, f indicates the feed amount per tooth as in the case described above.

  As shown in FIG. 16, in order to avoid interference between the flank 91 e of the insert 91 and the workpiece 6, the clearance angle γ (an angle with respect to the circumferential speed V) of the insert 91 is based on the advance angle θ of the cutting edge 91 d. Must be large, and the following equation must be satisfied.

  As an example, the clearance angle γ is actually calculated using the above equation (10). The diameter D = 12 mm at the cutting edge position where the clearance angle of the insert 91 is a problem, the number of blades N = 4, the radius of curvature Rt = 50 mm of the wiper portion cutting edge 91b, the radius of curvature Rw = 40 mm in the feed direction of the target machining surface TS, The theoretical roughness target value Rtht of the formed finished surface 63 is set to 5 μm. The target value Rtht of the theoretical roughness on the finished surface 63 can be obtained from the above-described equation (4). Therefore, in order to satisfy the target value Rtht of the theoretical roughness, the feed amount f per tooth must be less than 2.83 mm. Therefore, in the above equation (10), when f = 2.83 mm, the clearance angle γ of the insert 91 is calculated as γ> 16.5 ° from the equation (10), which is considerably larger than the existing clearance angle. Large value.

<Effects of Second Embodiment>
According to the present embodiment, the wiper portion cutting edge 83 is formed by a curve having a curvature radius Rt slightly smaller (absolute value is larger) than the curvature radius Rw in the feed direction of the convex target machining surface TS. The posture is changed so that the finished surface generation portion formed by rotating and sweeping the cutting edge 83 substantially matches (or touches) the target machining surface TS, and feed is given along the curved surface of the target machining surface TS. Yes. As a result, it is possible to increase the feed amount f and realize high-efficiency machining, and to improve the finished surface roughness.

  In general, the clearance angle between the flank and the finished surface of the cutting tool is set according to the hardness and elastic modulus of the workpiece and the strength of the cutting edge of the cutting tool. However, in the present embodiment, the clearance angle γ formed in the cutting tool 8 is set based on the feed speed F of the cutting tool 8 or the like. As a result, the clearance angle γ can be increased in response to an increase in the feed amount f. Therefore, even when the cutting system 1 according to the present embodiment is used to increase the feed amount f and perform cutting. The flank 91e of the insert 91 can be prevented from interfering with the shoulder portion existing between the finished surface 63 and the uncut portion 62.

<Other embodiments>
The present invention is not limited to the above-described embodiments, and can be modified or expanded as follows.

  The cutting tool according to the present invention is not limited to an end mill, and can also be applied to a milling cutter, turning, planing, a cutting tool for shaping, and the like. In addition to the machining center, the cutting apparatus according to the present invention can be applied to a turning center, an NC milling machine, an NC lathe, and the like.

  17 and 18 show a case where the present invention is applied to turning. In the figure, the workpiece 6 is rotated about the rotation axis φ. The cutting tool 9A has a nose portion cutting edge 91f and a wiper portion cutting edge 91g continuous thereto at the tip. The cutting tool 9A relatively moves in the feed direction as shown by the white arrow while cutting the workpiece 6. As a result, a finished surface 64 that is a curved surface in the feed direction is formed on the workpiece 6. This embodiment is different from the first embodiment or the second embodiment in that no pick feed is present, but the other configurations are the same and will not be described.

  The NC control device 4 is configured so that the cutting speed when the uncut portion 62 that is a finished surface is cut again by a cutting tool is different from the cutting speed when the uncut portion 62 is formed last time. 54E may be controlled. By doing so, it is possible to deviate the frequency at which the vibration trace left in the uncut portion 62 at the previous cutting is reproduced as the cut thickness variation, and to suppress the growth of chatter vibration.

  In the cutting tool, a pair of wiper part cutting edges may be provided so as to sandwich the nose part cutting edge. Further, a plurality of sets of nose part cutting edges and wiper part cutting edges may be formed in a substantially polygonal shape on the extension of one cutting edge, and their curvature radii may be different.

  In the drawings, 1 is a cutting system (cutting device), 2 is a CAD / CAM device (machining support device), 4 is an NC control device, 6 is a workpiece, 7 and 8 are end mills (cutting tools), 7A, 7B, 9, 9A are cutting tools, 54A is a Y-axis motor (pick feed unit), 54B is an X-axis motor (tool feed unit), 54D is a Y-axis rotation angle motor (posture changing unit), 54E is a spindle motor, 54F Is an X-axis rotation angle motor (posture changing unit), 58 is a tool changing unit (tool changing unit), 59 is a tool magazine (tool receiving unit), 61, 63 and 64 are finished surfaces, 62 is an uncut portion (existing portion) Machining surfaces), 72, 82, 91a, 91f are cutting nose cutting edges, 73, 83, 91b, 91g are wiper cutting edges, 74 is a burnishing section, F is a feed rate, Re, Rt are cutting wiper cutting edges. Swept by movement Rn is the radius of curvature of the nose edge, Rp is the radius of curvature of the target machining surface in the pick feed direction, Rw is the radius of curvature of the target machining surface in the feed direction, TS is the target machining surface, and γ is the clearance angle Show.

Claims (13)

A cutting device (1) for cutting a curved target processing surface (TS) having a predetermined curvature (1 / Rw) in a feed direction in a workpiece (6),
A curved nose portion cutting edge (72) having a positive first curvature (1 / Rn) when the curvature of the curve convex toward the target machining surface is positive and the curvature of the concave curve is negative. 82, 91a, 91f), and a cutting edge that is continuous with the nose portion cutting edge and has a cutting edge length longer than the nose portion cutting edge, and the curvature (1 / Rw) of the target machining surface in the feed direction A curved wiper part cutting edge (73, 83, 91b, 91g) having the second curvature (1 / Rt) that satisfies the condition that the difference from the curvature of the target machining surface is within a predetermined range as described above is provided. Cutting tools (7, 8, 9, 9A);
When machining with the cutting tool, the posture of the cutting tool with respect to the workpiece is set in the feed direction so that a finished surface generating portion formed by sweeping the wiper portion cutting edge matches the target machining surface. A posture changing unit (54D, 54F) to be changed;
Cutting device equipped with. A tool storage portion (59) for storing one or more cutting tools (7, 7A, 7B, 8, 9, 9A) on standby;
A tool replacement section (58) for replacing one of the cutting tools on standby stored in the tool storage section with the cutting tool in use;
Comprising:
A tool selection unit that selects a tool to be used based on the shape of the target machining surface from the plurality of cutting tools that can be used;
The cutting apparatus according to claim 1, further comprising:   The tool selection unit has a predetermined difference between the curvature of the cutting edge of the wiper and a curvature of the machining surface (1 / Rw) or more from a curvature of the target machining surface among the plurality of usable cutting tools. The cutting apparatus according to claim 2, wherein a tool that satisfies the condition of the second curvature (1 / Rt) within the range is selected.   The cutting speed when the uncut portion (62) that is a finished surface is cut again by the cutting tool is controlled to be different from the cutting speed when the finished surface is formed. The cutting apparatus according to any one of 3. A pick feed section (54A) for moving the cutting tool relative to the workpiece so as to move in a pick feed direction perpendicular to the feed direction when machining with the cutting tool;
The target machining surface has a curved surface shape having a predetermined curvature (1 / Rp) in the pick feed direction,
The surface formed by sweeping the cutting edge of the wiper portion is a pick feed direction of the target machining surface when the curvature of the curve convex toward the target machining surface is positive and the curvature of the concave curve is negative. A curvature (1 / Re) within a predetermined range in the pick feed direction.
The posture changing unit (54F)
When machining with the cutting tool, the posture of the cutting tool with respect to the workpiece is set to the pick feed direction so that a finished surface generation portion of a surface on which the wiper part cutting edge is swept matches the target machining surface. The cutting apparatus as described in any one of Claims 1 thru | or 4 changed to. A cutting tool (7, 8, 9, 9A) for cutting a curved target machining surface (TS) having a predetermined curvature (1 / Rw) in the feed direction,
A curved nose portion cutting edge (72) having a positive first curvature (1 / Rn) when the curvature of the curve convex toward the target machining surface is positive and the curvature of the concave curve is negative. 82, 91a, 91f),
The cutting edge is continuous with the cutting edge of the nose portion and has a cutting edge length longer than that of the cutting edge of the nose portion, and has a curvature (1 / Rw) or more of the target processing surface in the feed direction and A curved wiper part cutting edge (73, 83, 91b, 91g) having a second curvature (1 / Rt) that satisfies the condition that the difference from the curvature is within a predetermined range;
Cutting tool equipped with.   The cutting tool (9) according to claim 6, wherein the clearance angle (γ) of the cutting tool (9) is set based on a traveling angle (θ) of the cutting tool. The cutting tool (7)
A burnishing portion (74) that is continuous with the wiper portion cutting edge (73) at a position opposite to the nose portion cutting edge (72) and presses the finished surface (61) formed by the wiper portion cutting edge. The cutting tool according to claim 6 or 7, comprising: The machining apparatus according to claim 3, wherein the machining support apparatus generates machining data.
Based on the curvature of each of the cutting tools, set a curvature range (1 / Rs1, 1 / Rs2, 1 / Rs3) that each of the cutting tools can cut, and based on the curvature range and product drawing data, A machining surface dividing unit that divides the target machining surface into a plurality of regions each corresponding to one of the curvature ranges;
A tool setting unit that applies the cutting tool to be used to each part of the target machining surface based on the divided area;
A feed amount setting unit for setting a feed amount (f) of the cutting tool based on the fitted cutting tool and the product drawing data;
A posture setting unit for setting a posture of the cutting tool with respect to the workpiece based on the fitted cutting tool and the product drawing data;
A processing support device comprising: In the workpiece (6), a processing method for cutting a curved target processing surface (TS) having a predetermined curvature (1 / Rw) in the feed direction,
A nose portion cutting edge (72, 82, 72) having a positive first curvature (1 / Rn) when the curvature of the convex curve toward the target machining surface is positive and the curvature of the concave curve is negative. 91a, 91f), and a cutting edge that is continuous with the nose portion cutting edge and has a longer cutting edge length than the nose portion cutting edge, and has a curvature (1 / Rw) or more in the feed direction, and Cutting tool comprising a curved wiper part cutting edge (73, 83, 91b, 91g) having a second curvature (1 / Rt) that satisfies the condition that the difference from the curvature of the target machining surface is within a predetermined range 7, 8, 9, 9A)
At least one of the cutting tool and the workpiece is operated to cut the workpiece, and the finished surface generation portion of the surface swept by the wiper part cutting edge matches the target machining surface. As described above, the cutting tool is moved to the curved surface of the target machining surface by moving at least one of the cutting tool and the workpiece while changing the posture of the cutting tool with respect to the workpiece. A processing method of relatively moving along the feed direction along the line.   The processing method according to claim 10, wherein a cutting speed when the uncut portion (62), which is a processed surface, is cut again by the cutting tool is different from a cutting speed when the processed surface is formed. . When machining with the cutting tool, the cutting tool is also relatively moved in the pick feed direction orthogonal to the feed direction,
The target machining surface is
A curved surface having a predetermined curvature (1 / Rp) in the pick-feed direction;
The surface formed by sweeping the wiper cutting edge of the cutting tool has a curvature (1 / Re) within a predetermined range in the pick feed direction that is equal to or greater than the curvature of the target processing surface in the pick feed direction. And
When machining with the cutting tool, the posture of the cutting tool with respect to the workpiece is set to the pick feed direction so that a finished surface generation portion of a surface on which the wiper part cutting edge is swept matches the target machining surface. The processing method according to claim 10 or 11, wherein the processing method is also changed. A curvature range (1 / Rs1, 1 / Rs2, 1 / Rs3) that each of the cutting tools can cut based on the curvatures of a plurality of usable cutting tools (7, 7A, 7B, 8, 9, 9A). A machining surface dividing step of dividing the target machining surface into a plurality of regions each corresponding to one of the curvature ranges, based on the curvature range and product drawing data;
A tool setting step of applying the cutting tool to be used to each part of the target machining surface based on the divided area;
A feed amount setting step for setting a feed amount (f) of the cutting tool based on the fitted cutting tool and the product drawing data;
A posture setting step of setting a posture of the cutting tool with respect to the workpiece based on the fitted cutting tool and the product drawing data;
The processing method according to any one of claims 10 to 12, further comprising:

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