JP2011022898A - Cutting method for work material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for cutting a work material for minimizing influences by motion precision errors which a variety of mechanisms and structures included in a machining center have on completion size precision of a machined surface. <P>SOLUTION: The method is for forming a machined surface including a curved surface on a workpiece 100 being the work material by using the machining center which includes a main shaft to which an end mill tool 50 is attached and a hold part for holding the workpiece 100 as a work material and cuts the workpiece 100 by moving the main shaft and the hold part synchronously on the basis of NC (Numerical Control) data. The method includes: a step for creating the NC data so that the direction and size of a forward velocity vector Fc of a cut point P where the workpiece 100 is in contact with the end mill tool 50 may become constant on the basis of shape data of the machined surface and a shape of the end mill tool 50; and a step for forming a machined surface on the workpiece 100 on the basis of the NC data created. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cutting method of a work material that uses a machining center that is driven based on NC (Numerical Control) data to form a generating surface including a curved surface on the work material.

  For example, in order to manufacture dies and the like, cutting of a work material (hereinafter also referred to as a workpiece) using a CAM (Computer Aided Manufacturing) system is performed. In workpiece cutting using the CAM system, the 3D data of the created surface created by CAD (Computer Aided Design) and the shape data of the cutting tool attached to the spindle of the machining center are input to the CAM. NC data is created by the CAM, and the machining process is performed by driving the machining center based on the created NC data.

  When manufacturing the above-described mold or the like, an end mill tool which is a kind of rotating tool is generally used as a cutting tool. Therefore, a spindle for rotating the end mill tool around the axis of the spindle is attached to the spindle of the machining center, and the end mill tool is attached to the spindle through the spindle.

  In the conventional CAM system, the end mill tool attached to the main shaft is controlled to move in three translational directions in the X-axis direction, the Y-axis direction, and the Z-axis direction. Creation is possible. In this case, the NC data produced by the CAM becomes the path data of the center position (hereinafter also referred to as the tool center) of the end mill tool attached to the spindle, and the end mill tool moves based on the path data of the tool center. As a result, the workpiece set on the table as the holding portion of the machining center is cut.

  Here, the cutting point at which the end mill tool and the workpiece actually contact each other is a position separated from the tool center by the radius of the end mill tool. Therefore, when the end mill tool is moving linearly (that is, when the generating surface is a flat surface), the tool center moving speed is equal to the cutting point feed speed. The quality of the subsequent processed surface (that is, the created surface) is kept good. However, when the end mill tool performs a curved motion (that is, when the generating surface is a curved surface), the magnitude of the moving speed of the tool center and the magnitude of the feeding speed of the cutting point will be different. There has been a problem in that the quality of the machined surface after cutting is reduced.

  Therefore, in the recent CAM system, the shape data of the surface to be created and the end mill tool so that the path data of the tool center created by the CAM is constant so that the feed rate vector of the cutting point described above is constant. Is calculated based on the shape data. (For example, refer to JP-A-9-29584 (Patent Document 1), JP-A-2002-233930 (Patent Document 2), etc.). As a result, regardless of whether the end mill tool performs a linear motion or a curved motion, the magnitude of the feed rate vector at the cutting point is always kept constant, which reduces the quality of the above-described machining surface. The problem is being solved.

JP-A-9-29584 JP 2002-233930 A

  However, even when NC data is created so that the feed rate vector of the cutting point is constant, motion accuracy errors (for example, a mechanism that drives a spindle or a table) that various mechanisms and structures included in the machining center have. Eliminate motion accuracy errors due to backlash, stick motion, lost motion, etc., motion accuracy errors due to servo delay, motion accuracy errors due to thermal displacement, support rigidity anisotropy, etc.) I can't. For this reason, the movement accuracy error of these various mechanisms and structures causes a shift in the movement locus of the center position of the end mill tool that moves based on the NC data, and as a result, the movement accuracy error is transferred to the machining surface. As a result, the finished dimensional accuracy was reduced.

  Accordingly, the present invention has been made to solve the above-described problems, and motion accuracy errors of various mechanisms and structures included in the machining center are present on the machining surface so that the machining surface can be finished with high accuracy. It aims at providing the cutting method of the work material which can suppress the influence which it has on finishing dimensional accuracy.

  In recent years, in addition to the above-described motion control of the end mill tool in the three translational directions, either the table on which the workpiece is set or the main shaft to which the end mill tool is attached is any two of the axes in the three translational directions described above. A so-called five-axis control machining center that controls motion around an axis has become widespread. However, how to create NC data in the CAM system including the 5-axis control machining center has not been sufficiently developed yet, and the added rotation axis is used only for indexing a slope or the like. Its use remains within the scope of use. The present inventors perform a motion control in at least two translational directions and one rotational direction of the five-axis control machining center, thereby keeping the direction of the feed velocity vector at the cutting point or the size constant in addition thereto. The present invention has been completed with the idea of being able to do so.

  That is, the cutting method of the work material based on 1st aspect of this invention is equipped with the main axis | shaft to which the cutting tool was attached, and the holding part holding a work material, The said main shaft and the said holding | maintenance based on NC data By using a machining center that cuts the work material by bringing the cutting tool and the work material into contact with each other by moving the parts synchronously, a work that forms a generating surface including a curved surface on the work material A method of cutting a material, wherein a direction of a feed speed vector of a cutting point at which the work material and the cutting tool come into contact is constant based on the shape data of the generating surface and the shape data of the cutting tool. The step of creating the NC data and the step of forming the generating surface on the work material by moving the cutting tool and the holding portion in synchronization based on the created NC data. Obtain.

  A cutting method for a work material according to the second aspect of the present invention includes a main shaft to which a cutting tool is attached and a holding portion for holding the work material, and the main shaft and the holding based on NC data. By using a machining center that cuts the work material by bringing the cutting tool and the work material into contact with each other by moving the parts synchronously, a work that forms a generating surface including a curved surface on the work material A method of cutting a material, wherein the direction and magnitude of a feed speed vector of a cutting point at which the work material and the cutting tool are in contact with each other are determined based on the shape data of the generating surface and the shape data of the cutting tool. The step of creating the NC data to be constant and the generating surface is formed on the work material by moving the cutting tool and the holding unit synchronously based on the created NC data. Ste And a flop.

  In this way, when creating NC data, the NC data is created so that the direction of the feed rate vector at the cutting point where the work material and the cutting tool are in contact with each other or the size thereof is always kept constant. By driving the machining center based on the created NC data, among the movement accuracy errors of various mechanisms and structures included in the machining center, the movement accuracy error that occurs along the same direction as the direction of the feed velocity vector at the cutting point Transfer to the work material can be surely prevented. Therefore, it is possible to finish the processed surface with higher accuracy than in the past.

  Preferably, in the work material cutting method according to the first and second aspects of the present invention, as the machining center, the main shaft is moved along the three translational directions of the X-axis direction, the Y-axis direction, and the Z-axis direction. In addition, a 5-axis control machining center is used in which the holding portion is rotated and moved along two rotation directions around the B axis and the C axis. Thus, using a so-called 5-axis control machining center as the machining center, motion control in at least two of the three translational directions in the X-axis direction, the Y-axis direction, and the Z-axis direction described above, By synchronously performing motion control in at least one of the two directions of rotation around the axis, the direction of the feed velocity vector at the cutting point or the size thereof in addition to this is always kept constant. It is possible to create any three-dimensional shape.

  Preferably, in the work material cutting method according to the first and second aspects of the present invention, an end mill tool rotating around the axis of the main shaft is used as the cutting tool. Thus, by using an end mill tool as a cutting tool, it is possible to manufacture a mold or the like with higher accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, the influence which the motion accuracy error which the various mechanisms and structures contained in a machining center have on the finished dimensional accuracy of a processed surface can be suppressed, and it becomes possible to finish a processed surface with high precision.

It is a block diagram of the CAM system which implement | achieves the cutting method of the workpiece in embodiment of this invention. It is a schematic diagram which shows the structure of the process part of the machining center contained in the CAM system shown in FIG. It is a schematic diagram which shows the concept of the cutting method of the workpiece in embodiment of this invention. It is a flowchart which shows the process sequence at the time of following the cutting method of the workpiece in embodiment of this invention. It is a schematic diagram for demonstrating the algorithm at the time of creating NC data in the cutting method of the workpiece in embodiment of this invention. (A) is a schematic diagram for demonstrating the operation | movement in the process part of the machining center in a comparative example, (B) is a schematic diagram for demonstrating the operation | movement in the process part of the machining center in an Example. (A) is a figure which shows typically the locus | trajectory of the movement of the end mill tool in a comparative example, (B) is a figure which shows typically the locus | trajectory of the movement of an end mill tool and a workpiece | work in an Example. (A) is a figure which shows the result of having actually measured the locus | trajectory of the movement of the end mill tool in a comparative example from the outside including a motion accuracy error, and (B) is the roundness of the machining surface formed on the workpiece in the comparative example. It is a figure which shows the result of having measured this. (A) is a figure which shows the result of having actually measured the movement locus | trajectory of the end mill tool in an Example also including a motion precision error, (B) is the roundness of the process surface formed in the workpiece | work in an Example. It is a figure which shows the result of having measured this.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or common portions are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a block diagram of a CAM system that realizes a cutting method of a work material according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a configuration of a machining part of a machining center included in the CAM system shown in FIG. FIG. First, with reference to these FIG. 1 and FIG. 2, it demonstrates in detail about the structure of the CAM system which implement | achieves the cutting method of the workpiece in this Embodiment, and the structure of the process part of a machining center.

  As shown in FIG. 1, the CAM system 1 mainly includes a computer 10 and a machining center 30. Among these, the input device 22, the output device 24, the external storage device 26 and the like are connected to the computer 10. The input device 22 is, for example, a keyboard or a mouse, and the output device 24 is, for example, a display or a printer. The external storage device 26 is various media (for example, a magnetic disk, an optical disk, a flash memory, etc.), and the external storage device 26 includes shape data (for example, point sequence data) of a creation surface separately created by CAD. Etc.) are stored.

  The computer 10 includes a CPU (Central Processing Unit) 12, a RAM (Random Access Memory) 14, and a ROM (Read Only Memory) 16. Here, an NC data creation program is stored in the ROM 16, and the CPU 12 reads out the NC data creation program from the ROM 16 to the RAM 14 and executes it to create NC data to be described later. The created NC data is temporarily stored in the ROM 16 and output to the machining center 30 based on a user command. When creating NC data, the shape data of the generating surface stored in the external storage device 26 is read and used, and the shape data of the cutting tool stored in advance in the ROM 16 is read and used.

  As shown in FIGS. 1 and 2, the machining center 30 includes a spindle (not shown) to which an end mill tool 50 as a cutting tool is attached, a table 60 as a holding unit that holds a workpiece, and various drive mechanisms 40 to 45. And various control units 32 and 34 for controlling operations of these various drive mechanisms 40 to 45 are mainly provided.

  A main shaft rotation drive mechanism 40 made of, for example, a spindle is attached to the main shaft, and the end mill tool 50 described above is attached to the main shaft via the main shaft rotation drive mechanism 40. Thereby, the end mill tool 50 is driven to be rotatable around the axis of the main shaft. Further, an X-axis direction feed drive mechanism 41, a Y-axis direction feed drive mechanism 42, and a Z-axis direction feed drive mechanism 43 using, for example, a motor as a drive source are attached to the main shaft. Thereby, as shown in FIG. 2, the end mill tool 50 is driven to be movable in three directions of the X-axis direction, the Y-axis direction, and the Z-axis direction.

  Here, the operation of the spindle rotation driving mechanism 40 described above is controlled by the tool rotation control unit 32. More specifically, the tool rotation control unit 32 controls the rotational motion of the end mill tool 50 by driving the spindle rotation driving mechanism 40 based on the NC data input from the computer 10. On the other hand, the operations of the X-axis direction feed drive mechanism 41, the Y-axis direction feed drive mechanism 42, and the Z-axis direction feed drive mechanism 43 described above are controlled by the feed control unit 34. More specifically, the feed control unit 34 drives the X-axis direction feed drive mechanism 41, the Y-axis direction feed drive mechanism 42, and the Z-axis direction feed drive mechanism 43 based on the NC data input from the computer 10. The translation of the spindle is controlled, thereby controlling the movement of the end mill tool 50.

  On the other hand, the table 60 is supported by a table support member 70, and the work is held together with the fixing jig by attaching the work to the upper surface of the table 60 via a fixing jig (not shown). For example, a C-axis feed driving mechanism 45 using a motor or the like as a drive source is attached to the table 60, and a B-axis feed driving mechanism 44 using a motor or the like as a drive source is attached to the table support member 70, for example. It has been. As a result, the table 60 is driven to rotate in two directions around the B axis and the C axis, as shown in FIG. Here, the B axis is an axis that matches the Y axis described above when the table 60 is in the initial position, and the C axis is an axis that matches the Z axis described above when the table 60 is in the initial position. It is.

  Here, the operations of the B-axis feed driving mechanism 44 and the C-axis feed driving mechanism 45 described above are controlled by the feed control unit 34. More specifically, the feed control unit 34 controls the rotational movement of the table 60 by driving the B-axis feed mechanism 44 and the C-axis feed drive mechanism 45 based on the NC data input from the computer 10. This controls the movement of the workpiece. The feed control unit 34 controls the translational motion of the spindle and the rotational motion of the table 60 in synchronization.

  As shown in FIG. 1, the machining center 30 includes a tool position detection unit 46 and a table position detection unit 47 in addition to the functional blocks described above. The tool position detection unit 46 detects the position of the end mill tool 50 along the three translational directions, and outputs this to the feed control unit 34. The table position detection unit 47 detects the position of the table 60 along the two rotation directions, and outputs this to the feed control unit 34. The feed control unit 34 servo-controls the various feed drive mechanisms 41 to 45 as necessary based on the position information input from the tool position detection unit 46 and the table position detection unit 47, and thereby the spindle and the table. 60 positions are controlled.

  FIG. 3 is a schematic diagram showing the concept of the cutting method of the work material in the present embodiment. FIG. 3A is a side view of the end mill tool and the workpiece along the plane including the X axis and the Y axis. FIG. 3 (B) is a plan view of the end mill tool and workpiece taken along a plane including the X axis and the Z axis. Next, the concept used in the cutting method of the work material in the present embodiment will be described with reference to FIG. In FIG. 3, the tool center that is the center position of the end mill tool 50 is indicated by reference numeral 50a, and the workpiece center that is the center position of the workpiece 100 is indicated by reference numeral 100a.

  As shown in FIG. 3, in the cutting method of the work material in the present embodiment, the contact point between the workpiece 100 and the end mill tool 50 that is located on the surface S orthogonal to the central axis of the end mill tool 50. The direction and the magnitude of the feed speed vector Fc at the cutting point P are unchanged during the scanning of the end mill tool 50 around the workpiece 100 once. In order to realize this, it is necessary to rotate the workpiece 100 around the Z axis (that is, around the C axis). In the cutting method of the work material in the present embodiment, the end mill tool 50 is rotated once. During the scanning, the movement control of the end mill tool 50 in the two translational directions in the X-axis direction and the Y-axis direction and the movement control in the rotation one direction around the C-axis of the table 60 are performed in synchronization. . As a result, as shown in FIG. 3B, the direction and magnitude of the feed speed vector Fc at the cutting point P are the same regardless of whether the rotation angle of the workpiece 100 is 0, θ, or θ ′. Will be maintained.

  In addition, in order to facilitate understanding, in the above description, the case where the workpiece is contoured has been described as an example, but in the case where the workpiece is subjected to scanning line processing, helical processing, radial processing, etc., Similarly, by performing the motion control of the end mill tool and the motion control of the table in synchronism, cutting can be performed in a state where the direction and the magnitude of the feed rate vector of the cutting point described above are constant. However, when the cutting point is scanned three-dimensionally, for example, when helical machining is performed, the motion control of the end mill tool 50 in the three translational directions in the X-axis direction, the Y-axis direction, and the Z-axis direction, and the table 60 are performed. It is necessary to synchronize the motion control in the two rotation directions around the B axis and the C axis.

  FIG. 4 is a flowchart showing a processing procedure when the cutting method of the work material according to the present embodiment is followed. FIG. 5 is a diagram illustrating creation of NC data in the cutting method of the work material according to the present embodiment. It is a schematic diagram for demonstrating the algorithm at the time of doing. Next, with reference to these FIG. 4 and FIG. 5, the processing procedure in the case of following the cutting method of the work material in this Embodiment, and the specific algorithm at the time of creating NC data are explained in full detail.

  As shown in FIG. 4, in the work material cutting method according to the present embodiment, first, the shape data of the generating surface and the shape data of the end mill tool 50 are read by the CAM (step S1).

Next, the CAM calculates temporary tool feed data in which the magnitude of the feed speed vector Fc at the cutting point P is constant based on the read shape data of the generating surface and the shape data of the end mill tool 50 (step S2). . More specifically, as shown in FIG. 5A, the CAM has each point (..., P _n-1 , P _n ) of the point sequence data of the finished surface (that is, the generated surface) given from the CAD. , P _{n + 1} , P _{n + 2} ,...)), A virtual offset surface is set where the radius r of the end mill tool 50 is lifted, and the tool center 50a of the end mill tool 50 passes through this offset surface. In addition, the feed speed at the center of the end mill tool 50 is determined so that the magnitude of the feed speed vector of the end mill tool 50 at each point of the point sequence data on the finished surface is constant, and the temporary tool is based on these. Calculate the feed data.

Next, the CAM calculates table feed data so that the direction of the feed speed vector Fc at the cutting point P is constant based on the shape data of the generating surface, and the temporary tool feed based on the calculated table feed data. The tool feed data is calculated by correcting the data (step S3). More specifically, as shown in FIGS. 5 (A) and 5 (B), the CAM is the direction change angle of the feed speed vector of the end mill tool 50 between adjacent points in the point sequence data of the finished surface. (..., Α _n , α _{n + 1} , α _{n + 2} ,...) Are calculated (in FIG. 5B, the direction change angle α _{n +} between the points P _n and P _{n + 1.} display only _1), this was calculated table feed data to send the direction change angle amount corresponding table 60 based, as always end mill tool 50 is in contact against the workpiece to be rotated, based on the calculated table feed data Tool feed data for feeding the end mill tool 50 is calculated by correcting the temporary tool feed data.

  Next, the CAM outputs the calculated tool feed data and table feed data to the machining center 30 as NC data (step S4). Thereafter, the machining center 30 operates based on the input NC data to cut the workpiece 100 (step S5).

  By using the cutting method of the work material in the present embodiment described above, it is possible to suppress the influence of the motion accuracy error of various mechanisms and structures included in the machining center 30 on the finished dimensional accuracy of the machining surface. It is possible to finish the machined surface with high accuracy. The reason will be described in detail below with reference to FIG.

  As shown in FIG. 3, by using the cutting method of the work material in the present embodiment, the direction of the feed speed vector Fc at the cutting point P, which is the contact point between the end mill tool 50 and the workpiece 100, is being cut. Are always maintained in the same direction (here, the direction matching the direction of the feed velocity vector Fc at the cutting point P is the minus direction along the Y axis in FIG. 3). This means that the end mill tool 50 is always in contact with the workpiece 100 from the same direction at the cutting point P, which is the contact point between the end mill tool 50 and the workpiece 100 (here, the end mill tool). The direction in which the tool 50 contacts the workpiece 100 is the minus direction along the X axis in FIG. 3).

  Therefore, a motion accuracy error of the drive mechanism that drives the end mill tool 50 in a direction that matches the direction of the feed speed vector Fc at the cutting point P (for example, backlash, stick motion, lost motion included in the mechanism that drives the spindle) Motion accuracy error due to the above, etc.), motion accuracy error due to servo delay in a direction that matches the direction of the feed speed vector Fc at the cutting point P, and the direction of the feed speed vector Fc at the cutting point P Movement accuracy errors due to thermal displacement of various structures in the direction, anisotropy of support rigidity, and the like appear in the tangential direction on the surface of the workpiece 100 and do not appear in the normal direction of the surface of the workpiece 100. As a result, the movement accuracy error component of the drive mechanism and various structures can be suppressed from being transferred to the workpiece 100, and the machined surface can be finished with high accuracy. Moreover, in the cutting method of the work material in this Embodiment, since not only the direction of the feed rate vector of a cutting point but the magnitude | size is made constant, the quality of a processed surface will also be maintained favorable.

  FIGS. 6 to 9 are diagrams showing a verification test method and results conducted for verifying whether or not the above-described effect is actually obtained. Hereinafter, the method of the verification test and the result thereof will be described in detail. In this verification test, a workpiece as a work material was cut into a cylindrical shape using the CAM system as in the above-described embodiment.

  Here, in the comparative example, the end mill tool attached to the spindle of the machining center is translated along two directions of the X-axis direction and the Y-axis direction so that only the magnitude of the feed rate vector at the cutting point is constant. The workpiece was cut in a state where the table on which the workpiece was controlled and the workpiece was mounted was fixed without the motion control. On the other hand, in the embodiment, the end mill tool attached to the spindle of the machining center is moved along the two directions of the X axis direction and the Y axis direction so that both the direction and the magnitude of the feed speed vector at the cutting point are constant. The workpiece was cut by controlling the movement of the table to which the workpiece was attached along the C axis.

  FIG. 6A is a schematic diagram for explaining the operation in the machining part of the machining center in the comparative example, and FIG. 6B is a schematic diagram for explaining the operation in the machining part of the machining center in the example. is there. As shown in FIGS. 6A and 6B, in both the comparative example and the embodiment, fixing jigs 80A and 80B for fixing the workpiece 100 are mounted on the table 60, and the fixing is performed. The workpiece 100 is held by using the jigs 80A and 80B. Here, in the comparative example, the workpiece 100 is arranged on the central axis (that is, the C axis) of the table 60 using the fixing jig 80A, and in the embodiment, the workpiece 100 is mounted using the fixing jig 80B. The table 60 is decentered by a predetermined amount from the center axis (that is, the C axis).

  FIG. 7A is a diagram schematically showing a trajectory of movement of the end mill tool in the comparative example. As shown in FIG. 7A, in the comparative example, first, the end mill tool 50 is moved from the initial position along the path M1 to contact a predetermined position on the peripheral surface of the workpiece 100, and then along the path M2. The end mill tool 50 is moved around the Z axis so as to rotate counterclockwise in the circumferential direction, and the end mill tool 50 makes one turn around the work 100, and the end mill tool 50 makes one turn around the work 100. At that time, the end mill tool 50 was retracted from the workpiece 100 along the path M3 and returned to the initial position. In this comparative example, since the table 60 to which the workpiece 100 is attached is not rotated as described above, the cutting by the end mill tool 50 around the workpiece 100 is completed by the above operation. In the cutting process, as shown in FIG. 7A, the direction of the feed speed vector Fc at the cutting point P changes at any time.

  FIG. 7B is a diagram schematically illustrating a trajectory of movement of the end mill tool and the workpiece in the embodiment. As shown in FIG. 7B, in the embodiment, first, the end mill tool 50 is moved from the initial position along the path M1 to contact a predetermined position on the peripheral surface of the workpiece 100, and then along the path M2. The end mill tool 50 is swung counterclockwise around the Z axis, and the workpiece 100 is swung counterclockwise around the C axis along the path M2 ′, whereby the end mill tool 50 is rotated once around the workpiece 100. When the end mill tool 50 made one round of the workpiece 100, the end mill tool 50 was retracted from the workpiece 100 along the path M3 and returned to the initial position. In this embodiment, as described above, the table 60 to which the workpiece 100 is attached rotates in the direction of the arrow c in the figure around the C axis, so that the cutting by the end mill tool 50 around the workpiece 100 is completed by the above operation. become. In the cutting process, as shown in FIG. 7B, the direction of the feed speed vector Fc at the cutting point P is always in the same direction.

  FIG. 8A is a diagram showing the result of actual measurement of the movement path of the end mill tool in the comparative example including the motion accuracy error, and FIG. 8B is the machining surface formed on the workpiece in the comparative example. It is a figure which shows the result of having actually measured roundness of this. On the other hand, FIG. 9 (A) is a diagram showing the result of actually measuring the trajectory of the end mill tool in the example including the motion accuracy error, and FIG. 9 (B) is formed on the workpiece in the example. It is a figure which shows the result of having actually measured the roundness of the process surface.

  As shown in FIG. 8A, in the comparative example, the backlash and stick motion included in the X-axis direction feed drive mechanism and the Y-axis direction feed drive mechanism that drive the main shaft along the X-axis direction and the Y-axis direction. It can be seen that lost motion or the like appears as a relatively large motion accuracy error at the timing when the feeding direction is reversed. Here, in the comparative example, since the main shaft to which the end mill tool is attached passes through a trajectory of one rotation around the workpiece, the motion accuracy error is Y-axis plus side motion accuracy error, X-axis minus side motion accuracy error. , Y-axis minus side motion accuracy error and X-axis plus side motion accuracy error are generated every 90 ° in order, and each of these motion accuracy errors has a size of about 2.5 μm to 4 μm.

  On the other hand, as shown in FIG. 8B, the workpiece processed in the comparative example includes the above-described Y-axis plus side motion accuracy error, X-axis minus side motion accuracy error, Y-axis minus side motion accuracy error, and A Y-axis plus-side quadrant protrusion, an X-axis minus-side quadrant protrusion, a Y-axis minus-side quadrant protrusion, and an X-axis plus-side quadrant protrusion are formed at positions corresponding to the positions where the X-axis plus side motion accuracy error has occurred. I understand that. For this reason, in the comparative example in which the work material is cut by motion control in only two translational directions, the motion accuracy error of various drive mechanisms included in the machining center cannot be excluded, and the motion accuracy error It is understood that is transferred to the processed surface as it is. The size of the four quadrant protrusions is also about 2.5 μm to 4 μm, which corresponds to the four motion accuracy errors described above.

  On the other hand, as shown in FIG. 9A, also in the embodiment, the backlash included in the X-axis direction feed drive mechanism and the Y-axis direction feed drive mechanism that drives the main shaft along the X-axis direction and the Y-axis direction, It can be seen that stick motion, lost motion, etc. appear as relatively large motion accuracy errors at the timing when the feed direction is reversed. Here, also in the above embodiment, since the main shaft to which the end mill tool is attached passes through a trajectory of one rotation around the workpiece, the motion accuracy error is the Y axis plus side motion accuracy error, the X axis minus side motion accuracy error. , Y axis minus side motion accuracy error and X axis plus side motion accuracy error are generated every 90 ° in order, and each of these motion accuracy errors has a size of about 3 μm to 5 μm.

  On the other hand, as shown in FIG. 9B, the workpiece machined in the embodiment has a position corresponding to the position where the above-described X-axis minus side movement accuracy error and X-axis plus side movement accuracy error occur. Although the X-axis minus-side quadrant protrusion and the X-axis plus-side quadrant protrusion are respectively formed, the quadrant protrusion is at a position corresponding to the position where the Y-axis plus-side movement accuracy error and the Y-axis minus side movement accuracy error occur. It turns out that it is not formed. From this, in the embodiment in which the work material is machined by the motion control in the two translational directions and the one rotational direction, a part of the motion accuracy error of various drive mechanisms included in the machining center can be eliminated. It was confirmed that the machined surface can be finished with higher accuracy than the comparative example in which the work material was cut by motion control in only two translational directions. The size of the two quadrant protrusions is also about 3 μm, which corresponds to the four motion accuracy errors described above.

  Further, as shown in FIG. 9B, in the workpiece machined in the embodiment, machining in the vicinity of the position corresponding to the position where the above-described Y-axis plus side movement accuracy error and Y-axis minus side movement accuracy error occur. It can be seen that the roundness of the surface is greatly improved. This is because in addition to the motion accuracy errors of the various drive mechanisms described above, other motion accuracy errors of various mechanisms and structures included in the machining center (for example, motion accuracy errors due to servo delays, thermal displacement and support rigidity). It is judged that this is because the movement accuracy error due to the anisotropy of the first embodiment can be eliminated in the embodiment.

  Therefore, from the results of the above verification test, by applying the present invention, it is possible to suppress the influence of the motion accuracy error of various mechanisms and structures included in the machining center on the finished dimensional accuracy of the machined surface. It was confirmed that it was possible to finish the machined surface.

  In this Embodiment demonstrated above, although the case where the end mill tool which is a kind of rotary tool was used as a cutting tool was illustrated, the application range of this invention is not specifically limited to this. Various cutting tools including rotating tools and non-rotating tools can be used.

  Further, in the present embodiment described above, the case where contour line machining is performed has been described as an example, but the scope of application of the present invention is not limited to this. For example, in addition to this, the present invention may be applied when scanning line processing is performed. In addition to the above-described motion control in the two translational directions and the one rotational direction, the translational direction and / or the rotational direction may be used. The present invention may be applied to a case where helical processing or radial processing is performed by adding motion control.

  Further, the algorithm for calculating NC data in the present embodiment described above shows an example, and it is naturally possible to create NC data using another algorithm.

  Further, in the present embodiment described above, the case of cutting a workpiece using a so-called five-axis control machining center has been described as a specific example, but two or more translation directions and one rotation direction or more are described. As a matter of course, the present invention can be applied to any case where a workpiece is cut using a machine tool capable of multi-axis control (for example, a turning center or a multi-task machine). Is possible.

  Thus, the above-described embodiment disclosed herein is illustrative in all respects and is not restrictive. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 CAM system, 10 computer, 12 CPU, 14 RAM, 16 ROM, 22 input device, 24 output device, 26 external storage device, 30 machining center, 32 tool rotation control unit, 34 feed control unit, 40 spindle rotation drive mechanism, 41 X-axis direction feed drive mechanism, 42 Y-axis direction feed drive mechanism, 43 Z-axis direction feed drive mechanism, 44 B-axis around feed drive mechanism, 45 C-axis around feed drive mechanism, 46 Tool position detector, 47 Table position detector , 50 End mill tool, 50a Tool center, 60 table, 70 Table support member, 80A, 80B Fixing jig, 100 workpiece, 100a Work center.

Claims (4)

A main shaft to which a cutting tool is attached; and a holding portion for holding a work material. The cutting tool and the work material are moved by synchronizing the main shaft and the holding portion based on NC data. Using a machining center that cuts the work material by bringing the work material into contact with each other, a cutting method for the work material that forms a creation surface including a curved surface on the work material,
Based on the shape data of the generating surface and the shape data of the cutting tool, the NC data is created so that the direction of the feed speed vector of the cutting point where the work material and the cutting tool are in contact is constant. Steps,
A method of cutting a work material, comprising: forming the generating surface on the work material by moving the cutting tool and the holding portion in synchronization with each other based on the created NC data. A main shaft to which a cutting tool is attached; and a holding portion for holding a work material. The cutting tool and the work material are moved by synchronizing the main shaft and the holding portion based on NC data. Using a machining center that cuts the work material by bringing the work material into contact with each other, a cutting method for the work material that forms a creation surface including a curved surface on the work material,
Based on the shape data of the generating surface and the shape data of the cutting tool, the NC data is set so that the direction and the magnitude of the feed rate vector of the cutting point at which the work material and the cutting tool are in contact with each other are constant. The steps of creating
A method of cutting a work material, comprising: forming the generating surface on the work material by moving the cutting tool and the holding portion in synchronization with each other based on the created NC data.   As the machining center, the main shaft is moved along the three translational directions of the X-axis direction, the Y-axis direction, and the Z-axis direction, and the holding portion is rotated and moved along the two rotation directions around the B-axis and the C-axis. The method for cutting a work material according to claim 1 or 2, wherein an axis control machining center is used.   The cutting method of the work material in any one of Claim 1 to 3 which uses the end mill tool rotated around the axis line of the said main axis | shaft as said cutting tool.

Images