JP4872855B2 - Screw rotor processing method and processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To process a workpiece with good precision even when a tool wears. <P>SOLUTION: A screw rotor processing method includes a tool path setting step for setting target tool path data for processing a workpiece (120) into a screw rotor shape, an NC data generation step for generating NC data for causing a tool (110) and the workpiece (120) to move by a processing apparatus (100) from a target tool path, and a processing step for processing the workpiece (120) with the tool (110) while causing the processing apparatus (100) to move the tool (110) and the workpiece (120) based on the NC data. The screw rotor processing method further includes a shape measurement step for measuring a shape of the workpiece (120) after completion of processing, and a tool path resetting step for calculating shape errors from a desired screw rotor shape based on the shape of the workpiece (120) after completion of processing, for resetting the target tool path based on the shape errors. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a screw rotor processing method and a processing apparatus for processing a screw rotor of a screw compressor.

  Conventionally, a single screw compressor has been used as a compressor for compressing refrigerant and air. For example, Patent Document 1 discloses a single screw compressor including one screw rotor and two gate rotors.

  This single screw compressor will be described with reference to FIG. As shown in the figure, the screw rotor (440) is formed in a substantially cylindrical shape, and a plurality of spiral grooves (441) are carved on the outer peripheral portion thereof. The gate rotor (450) is generally formed in a flat plate shape, and is disposed on the side of the screw rotor (440). The gate rotor (450) is provided with a plurality of rectangular plate-shaped gates (451) radially. The gate rotor (450) is installed such that its rotation axis is orthogonal to the rotation axis of the screw rotor (440), and the gate (451) is engaged with the spiral groove (441) of the screw rotor (440).

  Although not shown in FIG. 16, in the single screw compressor, the screw rotor (440) and the gate rotor (450) are accommodated in the casing, the spiral groove (441) of the screw rotor (440), and the gate rotor (450). ) And the inner wall surface of the casing form a compression chamber. When the screw rotor (440) is rotationally driven by an electric motor or the like, the gate rotor (450) rotates with the rotation of the screw rotor (440). Then, the gate (451) of the gate rotor (450) moves relatively from the start end (left end in the figure) to the end (right end in the figure) of the meshed spiral groove (441), and the closed state is reached. The volume of the compressed chamber is gradually reduced. As a result, the fluid in the compression chamber is compressed.

  A screw rotor (440) constituting a part of such a single screw compressor is manufactured by a processing apparatus as shown in Patent Document 2.

The processing apparatus disclosed in Patent Document 2 includes a tool support portion that supports a tool so as to be linearly movable along three orthogonal axes, and a work support portion that supports a workpiece so as to be rotatable about two axes. The workpiece is processed with the tool while the workpiece and the workpiece are relatively moved linearly along the three axes and are rotated relatively around the two axes to produce the screw rotor (440).
JP 2002-202080 A US Pat. No. 6,122,824

  By the way, since the screw rotor has a complicated shape in which a spiral groove is formed as described above, it is necessary to relatively move the workpiece and the tool with high accuracy when machining the workpiece.

  However, if the processing of the screw rotor by the processing device is continued, the tool will eventually wear out. As the tool wears, the cutting resistance increases, and the force acting between the tool and the workpiece during cutting also increases. Then, the degree of bending of the tool and the workpiece at the time of cutting changes, and the shape of the spiral groove processed into the workpiece is different even if the movement path of the tool is the same. That is, the shape of the spiral groove processed into the workpiece may be different before and after the tool is worn.

  This invention is made | formed in view of this point, The place made into the objective is to process a workpiece | work accurately, even when a tool is worn.

In the first invention, the work (120) is screw-compressed by using the processing device (100) for processing the work (120) with the tool (110) by relatively moving the tool (110) and the work (120). The target is the screw rotor processing method that processes the screw rotor (40) of the machine (1). A tool path setting step for setting a target tool path of the tool (110) with respect to the workpiece (120) for processing into a desired screw rotor shape, and the tool by the processing device (100) from the target tool path. (110) and numerical data generation step for generating numerical data for moving the workpiece (120), respectively, and the machining device (100) is configured to use the tool (110) and the workpiece (120) based on the numerical data. ) Are moved to measure the shape error between the machining step of machining the workpiece (120) with the tool (110) and the shape of the workpiece (120) after the machining is completed and the desired screw rotor shape. the shape error measurement step, the shape error measurement step based on the measured shape errors in viewing including the tool path resetting step of resetting the target tool path, the tool rerouting process, the shape error In addition to decomposing into a plurality of pre-patterned shape error modes, a mode decomposing step for obtaining a composition ratio of each shape error mode, and a correction value prepared in advance corresponding to each shape error mode a correcting step for correcting the original target tool path at a value obtained by multiplying the composition ratio of each shape error mode shall have Nde free.

In the case of the above configuration, the shape error of the workpiece (120) after completion of machining is obtained, and the target tool path is reset based on the shape error, thereby machining the workpiece (120) on and after the next time with high machining accuracy. can do. Moreover, even if the shape error is complicated by resetting the target tool path that is the basis of the numerical value data, such as origin correction, which is not simply the translation of the numerical data, the target tool corresponding to the shape error route, Ru can be re-set and hence the numerical data.

For pre SL configurations, rather than directly modifying the target tool path from the determined shape error, by decomposing the shape error in a plurality of shape error mode seek the ratios of the shape error mode. Each shape error mode has a corresponding correction value prepared in advance, and the original target tool path is corrected using a value obtained by multiplying the correction value and the composition ratio of each shape error mode. Yes. In other words, instead of recalculating the target tool path from the beginning, the calculation error is calculated by decomposing the shape error into a plurality of shape error modes and correcting the original target tool path with a correction value corresponding to the shape error mode. Can be greatly reduced.

In a second aspect based on the first aspect, in the mode decomposition step, the shape error is approximated to a plurality of shape error modes by approximating the shape error with a linear combination of basis vectors corresponding to the shape error mode. The component ratio of each shape error mode is obtained by decomposition .

  According to a third aspect, in the first aspect, the tool path resetting step is performed when the predetermined timing has arrived and the processing of the workpiece (120) being processed at that time is completed. It is assumed that the route is reset.

  In the case of the above configuration, the resetting of the target tool path in the tool path resetting process is not performed during the machining of the workpiece (120), but is performed when the machining of the workpiece (120) is completed. Then, the target tool path is reset only when necessary by setting the predetermined timing to an appropriate timing according to the wear of the tool, for example, when the machining time has elapsed. Therefore, the machining of the workpiece (120) and the resetting of the target tool path can be performed efficiently.

  In a fourth aspect based on the first aspect, the tool path resetting step resets the target tool path every time machining of one workpiece (120) is completed.

  In the case of the above configuration, the resetting of the target tool path in the tool path resetting process is performed every time the machining of one workpiece (120) is completed. Since the tool wears even if it is processed even a little, by re-setting the target tool path for each workpiece (120), the shape error can be suppressed as much as possible, and the processing accuracy can be further improved. it can.

The fifth invention is a screw rotor machining in which the tool (110) and the workpiece (120) are relatively moved to process the workpiece (120) into the screw rotor (40) of the screw compressor (1) with the tool (110). The device is the target. And while setting the target tool path | route of the tool (110) with respect to the workpiece | work (120) for processing into a desired screw rotor shape, the said tool (110) and the said workpiece | work (120) are made from this target tool path | route. A control unit that creates numerical data for moving each, moves the tool (110) and the workpiece (120) based on the numerical data, and causes the tool (110) to process the workpiece (120) (500) and a shape measuring means (110C) for measuring the shape of the workpiece (120) after the completion of processing, and the control unit (500) is after the completion of processing measured by the shape measuring means (110C). The shape error between the shape of the workpiece (120) and the desired screw rotor shape is calculated, the shape error is decomposed into a plurality of pre-patterned shape error modes, and the composition ratio of each shape error mode Seeking Corresponding to each shape error mode by modifying the original target tool path at that by multiplying the composition ratio of each of the shape error mode correction value prepared in advance by, as to reset the target tool path To do.

In the case of the above configuration, the shape error of the workpiece (120) after completion of machining is obtained, and the target tool path is reset based on the shape error, thereby machining the workpiece (120) on and after the next time with high machining accuracy. can do. Moreover, even if the shape error is complicated by resetting the target tool path that is the basis of the numerical value data, such as origin correction, which is not simply the translation of the numerical data, the target tool corresponding to the shape error route, Ru can be re-set and hence the numerical data.

For pre SL configurations, rather than directly modifying the target tool path from the determined shape error, by decomposing the shape error in a plurality of shape error mode seek the ratios of the shape error mode. Each shape error mode has a corresponding correction value prepared in advance, and the original target tool path is corrected using a value obtained by multiplying the correction value and the composition ratio of each shape error mode. Yes. In other words, instead of recalculating the target tool path from the beginning, the calculation error is calculated by decomposing the shape error into a plurality of shape error modes and correcting the original target tool path with a correction value corresponding to the shape error mode. Can be greatly reduced.

In a sixth aspect based on the fifth aspect, the control unit (500) approximates the shape error by a linear combination of basis vectors corresponding to the shape error mode, thereby correcting the shape error to a plurality of shape errors. It is assumed that the component ratio of each shape error mode is obtained by decomposing into modes .

  In a fifth aspect based on the fifth aspect, the control unit (500) sets the target when a predetermined timing has arrived and the machining of the workpiece (120) being machined at that time has been completed. The tool path shall be reset.

  In the case of the above configuration, the resetting of the target tool path is not performed during the machining of the workpiece (120), but is performed when the machining of the workpiece (120) is completed. Then, the target tool path is reset only when necessary by setting the predetermined timing to an appropriate timing according to the wear of the tool, for example, when the machining time has elapsed. Therefore, the machining of the workpiece (120) and the resetting of the target tool path can be performed efficiently.

  In an eighth aspect based on the fifth aspect, the controller (500) resets the target tool path every time machining of one workpiece (120) is completed.

  In the case of the above configuration, the resetting of the target tool path is performed every time the machining of one workpiece (120) is completed. Since the tool wears even if it is processed even a little, by re-setting the target tool path for each workpiece (120), the shape error can be suppressed as much as possible, and the processing accuracy can be further improved. it can.

  According to the present invention, the shape error of the workpiece (120) is measured in the shape error measurement step after the machining of the workpiece (120) is completed, and the target tool path is determined based on the shape error of the workpiece (120) in the tool path resetting step. By resetting, even if the shape error is complex, the target tool path according to the shape error, and thus the numerical data, can be reset, and the next workpiece (120) will be machined with high machining accuracy. can do.

Further , the shape error is decomposed into a plurality of shape error modes in the mode decomposition step, and the original target tool path is determined according to the composition ratio of each shape error mode using the correction value for each shape error mode in the correction step. By modifying, it is possible to easily create a target tool path by reducing the amount of calculation at the time of modification.

  According to the third invention, when the predetermined timing has arrived and the machining of the workpiece (120) being machined at that time is completed, the target tool path is reset, so that the workpiece (120 ) And resetting the target tool path can be performed efficiently.

  According to the fourth invention, the shape error can be suppressed as much as possible by resetting the target tool path every time the machining of one workpiece (120) is completed, and the machining accuracy is further improved. be able to.

  According to the fifth invention, after the machining of the workpiece (120) is completed, the shape of the workpiece (120) is measured to calculate the shape error of the workpiece (120), and the target tool path is reset based on the shape error. Thus, even if the shape error is complicated, the target tool path according to the shape error, and thus the numerical data can be reset, and the workpiece (120) from the next time can be machined with high machining accuracy. .

In addition , the shape error is decomposed into a plurality of shape error modes, and the original target tool path is corrected according to the composition ratio of each shape error mode using the correction value for each shape error mode. Therefore, the target tool path can be easily created.

  According to the seventh invention, when the predetermined timing has arrived and the machining of the workpiece (120) being machined at that time is completed, the target tool path is reset, so that the workpiece (120 ) And resetting the target tool path can be performed efficiently.

  According to the eighth invention, the shape error can be suppressed as much as possible by resetting the target tool path every time the machining of one workpiece (120) is completed, and the machining accuracy is further improved. be able to.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  A screw rotor (40) manufactured by a screw rotor processing apparatus (100) according to an embodiment of the present invention is used in a single screw compressor (hereinafter simply referred to as a screw compressor) (1). First, the screw compressor (1) will be described.

  The screw compressor (1) is provided in a refrigerant circuit that performs a refrigeration cycle and compresses the refrigerant. As shown in FIGS. 2 and 3, the screw compressor (1) is configured in a hermetic type. In the screw compressor (1), the compression mechanism (20) and the electric motor that drives the compression mechanism (20) are accommodated in one casing (10). The compression mechanism (20) is connected to the electric motor via the drive shaft (21). In FIG. 2, the electric motor is omitted. Further, in the casing (10), a low-pressure gas refrigerant is introduced from the evaporator of the refrigerant circuit and the low-pressure space (S1) for guiding the low-pressure gas to the compression mechanism (20), and the compression mechanism (20) A high-pressure space (S2) into which the discharged high-pressure gas refrigerant flows is partitioned.

  The compression mechanism (20) includes a cylindrical wall (30) formed in the casing (10), a single screw rotor (40) disposed in the cylindrical wall (30), and the screw rotor (40). And two gate rotors (50) meshing with each other. The drive shaft (21) is inserted through the screw rotor (40). The screw rotor (40) and the drive shaft (21) are connected by a key (22). The drive shaft (21) is arranged coaxially with the screw rotor (40). The tip of the drive shaft (21) is rotatably supported by a bearing holder (60) located on the high pressure side (right side in FIG. 2) of the compression mechanism (20). The bearing holder (60) supports the drive shaft (21) via a ball bearing (61).

  As shown in FIGS. 4 and 5, the screw rotor (40) is a metal member formed in a substantially cylindrical shape. The screw rotor (40) is rotatably fitted to the cylindrical wall (30), and the outer peripheral surface thereof is in sliding contact with the inner peripheral surface of the cylindrical wall (30). A plurality (six in this embodiment) of spiral grooves (41) extending spirally from one end to the other end of the screw rotor (40) are formed on the outer periphery of the screw rotor (40).

  Each spiral groove (41) of the screw rotor (40) has a left end in FIG. 5 as a start end, and a right end in the figure ends. Further, the screw rotor (40) has a left end portion (end portion on the suction side) in FIG. In the screw rotor (40) shown in FIG. 5, the start end of the spiral groove (41) is opened at the left end face formed in a tapered surface, whereas the end of the spiral groove (41) is not opened at the right end face. .

  In the spiral groove (41), of the side wall surfaces (42, 43) on both sides, the one located on the front side in the traveling direction of the gate (51) is the first side wall surface (42), and the traveling direction of the gate (51) What is located on the rear side is the second side wall surface (43).

  Each gate rotor (50) is a resin member in which a plurality (11 in this embodiment) of gates (51) formed in a rectangular plate shape are provided radially. Each gate rotor (50) is symmetrically disposed on the outside of the cylindrical wall (30) with the screw rotor (40) interposed therebetween, and the axis is perpendicular to the axis of the screw rotor (40). Each gate rotor (50) is arranged so that the gate (51) penetrates a part of the cylindrical wall (30) and meshes with the spiral groove (41) of the screw rotor (40).

  The gate rotor (50) is attached to a metal rotor support member (55) (see FIG. 4). The rotor support member (55) includes a base portion (56), an arm portion (57), and a shaft portion (58). The base (56) is formed in a slightly thick disk shape. The same number of arms (57) as the gates (51) of the gate rotor (50) are provided and extend radially outward from the outer peripheral surface of the base (56). The shaft portion (58) is formed in a rod shape and is erected on the base portion (56). The central axis of the shaft portion (58) coincides with the central axis of the base portion (56). The gate rotor (50) is attached to a surface of the base portion (56) and the arm portion (57) opposite to the shaft portion (58). Each arm part (57) is in contact with the back surface of the gate (51).

  The rotor support member (55) to which the gate rotor (50) is attached is accommodated in a gate rotor chamber (90) defined in the casing (10) adjacent to the cylindrical wall (30) (FIG. 3). See). The rotor support member (55) disposed on the right side of the screw rotor (40) in FIG. 3 is installed in such a posture that the gate rotor (50) is on the lower end side. On the other hand, the rotor support member (55) disposed on the left side of the screw rotor (40) in the figure is installed in such a posture that the gate rotor (50) is on the upper end side. The shaft portion (58) of each rotor support member (55) is rotatably supported by a bearing housing (91) in the gate rotor chamber (90) via ball bearings (92, 93). Each gate rotor chamber (90) communicates with the low pressure space (S1).

  In the compression mechanism (20), a space surrounded by the inner peripheral surface of the cylindrical wall (30), the spiral groove (41) of the screw rotor (40), and the gate (51) of the gate rotor (50) is compressed. (23) The spiral groove (41) of the screw rotor (40) is open to the low pressure space (S1) at the suction side end, and this open part is the suction port (24) of the compression mechanism (20).

  The screw compressor (1) is provided with a slide valve (70) as a capacity control mechanism. The slide valve (70) is provided in a slide valve housing portion (31) in which a cylindrical wall (30) bulges radially outward at two locations in the circumferential direction. The slide valve (70) is configured such that its inner surface forms part of the inner peripheral surface of the cylindrical wall (30) and is slidable in the axial direction of the cylindrical wall (30).

  When the slide valve (70) slides to the right in FIG. 2, an axial gap is formed between the end surface (P1) of the slide valve housing (31) and the end surface (P2) of the slide valve (70). This axial clearance serves as a bypass passage (33) for returning the refrigerant from the compression chamber (23) to the low pressure space (S1). When the slide valve (70) is moved to change the opening of the bypass passage (33), the capacity of the compression mechanism (20) changes. The slide valve (70) has a discharge port (25) for communicating the compression chamber (23) and the high-pressure space (S2).

  The screw compressor (1) is provided with a slide valve drive mechanism (80) for slidingly driving the slide valve (70). The slide valve drive mechanism (80) includes a cylinder (81) fixed to the bearing holder (60), a piston (82) loaded in the cylinder (81), and a piston rod ( 83), a connecting rod (85) for connecting the arm (84) and the slide valve (70), and a spring for urging the arm (84) rightward in FIG. 86).

  In the slide valve drive mechanism (80) shown in FIG. 2, low pressure pressure acts on the left space of the piston (82), and high pressure pressure acts on the right space of the piston (82). The slide valve drive mechanism (80) controls the movement of the piston (82) by adjusting the gas pressure acting on the left and right end faces of the piston (82), and adjusts the position of the slide valve (70). It is configured.

-Driving action-
The operation of the single screw compressor (1) will be described.

  When the electric motor is started in the single screw compressor (1), the screw rotor (40) rotates as the drive shaft (21) rotates. As the screw rotor (40) rotates, the gate rotor (50) also rotates, and the compression mechanism (20) repeats the suction stroke, the compression stroke, and the discharge stroke. Here, the description will be given focusing on the compression chamber (23) shaded in FIG.

  In FIG. 6 (A), the compression chamber (23) with shading communicates with the low-pressure space (S1). Further, the spiral groove (41) in which the compression chamber (23) is formed meshes with the gate (51) of the gate rotor (50) located on the lower side of the figure. When the screw rotor (40) rotates, the gate (51) relatively moves toward the terminal end of the spiral groove (41), and the volume of the compression chamber (23) increases accordingly. As a result, the low-pressure gas refrigerant in the low-pressure space (S1) is sucked into the compression chamber (23) through the suction port (24).

  When the screw rotor (40) further rotates, the state shown in FIG. In the figure, the compression chamber (23) with shading is completely closed. That is, the spiral groove (41) in which the compression chamber (23) is formed meshes with the gate (51) of the gate rotor (50) located on the upper side of the figure, and the low pressure space ( It is partitioned from S1). When the gate (51) moves toward the end of the spiral groove (41) as the screw rotor (40) rotates, the volume of the compression chamber (23) gradually decreases. As a result, the gas refrigerant in the compression chamber (23) is compressed.

  When the screw rotor (40) further rotates, the state shown in FIG. In the figure, the shaded compression chamber (23) is in communication with the high-pressure space (S2) via the discharge port (25). When the gate (51) moves toward the end of the spiral groove (41) as the screw rotor (40) rotates, the compressed refrigerant gas is pushed out from the compression chamber (23) to the high-pressure space (S2). Go.

  In the process in which the compression mechanism (20) transitions from the suction stroke to the compression stroke, the gate (51) of the gate rotor (50) passes through the suction groove (24) that opens to the end surface of the screw rotor (40). 41) Enter inside. In the process in which the gate (51) enters the spiral groove (41), the gate (51) first has only a side surface and a front end surface located in front of the traveling direction on the first side of the spiral groove (41). The wall surface (42) and the bottom wall surface (44) face each other, and thereafter, the side surface located rearward in the traveling direction also faces the second sidewall surface (43) of the spiral groove (41).

  In addition, after the gate (51) reaches the position where the compression chamber (23) in the spiral groove (41) is completely closed, the first and second side wall surfaces of the gate (51) and the spiral groove (41). (42, 43) and the bottom wall surface (44) need not physically rub against each other, and there may be a minute gap between them. That is, even if there are minute gaps between the gate (51) and the first and second side wall surfaces (42, 43) and the bottom wall surface (44) of the spiral groove (41), the gap is an oil film made of lubricating oil. As long as it can be sealed, the air tightness of the compression chamber (23) is maintained, and the amount of gas refrigerant leaking from the compression chamber (23) is suppressed to a small amount.

-Screw rotor processing equipment-
Subsequently, a screw rotor processing apparatus (hereinafter simply referred to as a processing apparatus) (100) of the present embodiment will be described.

  As shown in FIG. 7, the machining apparatus (100) includes a tool support unit (200) that supports a tool (110) such as an end mill, and a work support unit (300) that supports a work (120) that is a workpiece. A base (130) on which the tool support unit (200) and the work support unit (300) are disposed, and a control device (500) for controlling the tool support unit (200) and the work support unit (300). (Refer to FIG. 1).

  The tool support unit (200) includes a column (210) disposed on the base (130) and a spindle part (220) attached to the column (210). This tool support unit (200) constitutes a tool support.

  The column (210) is slidably attached to a Z-axis guide rail (140, 140) provided on the upper surface of the base (130), and extends in the Z-axis direction in which the Z-axis guide rail (140, 140) extends. It is movable. Specifically, the column (210) moves while being positioned in the Z-axis direction by a linear servo motor. A Y-axis guide rail (150, 150) extending along the Y-axis extends on the surface of the column (210) facing the work support unit (300). The Y axis extends in the vertical direction.

  The spindle part (220) has a base part (230), a spindle body (240), and a tool holder (250).

  The base part (230) is slidably attached to the Y-axis guide rails (150, 150) of the column (210). The base portion (230) moves while being positioned in the Y-axis direction by a linear servo motor. That is, the spindle part (220) is movable in the Y-axis direction in which the Y-axis guide rails (150, 150) extend.

  A tool holder (250) supporting the tool (110) is detachably attached to the spindle body (240). A servo motor is mounted on the spindle body (240), and the tool holder (250), that is, the tool (110) is driven to rotate at a desired rotational speed by the servo motor.

  As shown in FIG. 8, the spindle body (240) includes a casing (241), a rotating main shaft portion (242) disposed in the casing (241), and a motor that rotationally drives the rotating main shaft portion (242). (Not shown). In the spindle body (240), the base end portion of the casing (241) is attached to the base portion (230) so that the rotation axis of the rotation main shaft portion (242) is parallel to the Z-axis guide rail (140, 140). ing. The tip of the rotating main shaft (242) is exposed to the outside from the tip of the casing (241). An opening is provided at the tip of the rotating main shaft (242), and the tool holder (250) is detachably attached to the opening.

  The base end of the tool holder (250) is attached to the rotation main shaft (242) of the spindle body (240), while a tool (110) such as an end mill is non-rotatably attached to the tip. The tool holder (250) is divided into several types depending on the type of the tool (110) to be attached. For example, FIG. 8 shows an end mill tool holder (250A) to which an end mill (110A) as a rotary tool is attached. The end mill tool holder (250A) is configured such that the end mill (110A) is non-rotatably attached to the tip portion via a chuck. Further, as shown in FIG. 9, the tool holder (250B) for a tool to which a tool (110B) as a non-rotating tool is attached is attached to the tip portion through a side lock screw so that the tool (110B) cannot be rotated. It is configured.

  The spindle body (240) rotates the end mill tool holder (250A) when the end mill tool holder (250A) is attached, while the tool tool (250B) is attached when the tool holder (250B) is attached. The holder (250B) is configured so as to be non-rotatable.

  Specifically, the spindle main body (240) is constituted by a spindle having a servo motor and having an indexing function, and a drive key (243) is provided on the front end surface of the rotating main shaft (242). On the other hand, a base part of the end mill and tool holder (250A, 250B) is provided with a flange part (251) that comes into contact with the distal end surface of the rotary main shaft part (242). ) Is formed with a key groove (252) into which the drive key (243) is fitted.

  The end mill and tool tool holders (250A, 250B) configured in this manner are attached to the rotating main shaft (242) so that the drive key (243) is fitted in the keyway (252). By doing so, the tool holders (250A, 250B) for the end mill and the cutting tool are attached to the rotating main shaft portion (242) so as not to rotate. When the end mill tool holder (250A) is attached, the end mill tool holder (250A) is rotationally driven by the servo motor at a desired rotational speed. On the other hand, when the tool holder for tools (250B) is attached, the rotary spindle (242) is controlled by the servo motor indexing function so that the phase is fixed, and the tool holder for tools (250B) is fixed so that it cannot rotate. .

  The spindle body (240) and the tool holder (250) may be configured as follows. That is, as shown in FIG. 10, a concave engaged portion (244) is formed on the front end surface of the casing (241), while the tool holder (250B) for cutting tool has a front end of the casing (241). A rod-shaped engaging portion (253) extending to the surface is formed. Note that the engagement portion (253) is not formed in the end mill tool holder (250A). That is, the tool holder for tool (250B) is attached to the rotating main shaft (242) so that the tip of the engaging portion (253) is fitted into the engaged portion (244) and rotates with respect to the casing (241). On the other hand, the end mill tool holder (250A) is not restricted by the casing (241) even if it is attached to the rotary main shaft (242).

  In the tool support unit (200) configured as described above, the linear servo motors of the column (210) and the base part (230) are driven and controlled in accordance with a control signal from the control device (500), whereby the tool is (110) is positioned at a desired Y-direction position and Z-direction position, and the servo motor of the spindle body (240) is driven and controlled in accordance with a control signal from the control device (500), whereby the tool (110 ) Is driven to rotate or is supported non-rotatably.

  On the other hand, the workpiece support unit (300) includes a rotary table (310) that is rotatably arranged with respect to the base (130), and a workpiece (workpiece) that is installed on the rotary table (310) and that is a work piece. 120) and a center (330) that is installed on the rotary table (310) and supports the rotation center of the workpiece supported by the clamp part (320). . This work support unit (300) constitutes a work support part.

  The rotary table (310) is slidably attached to an X-axis guide rail (160, 160) provided on the upper surface of the base (130) and extending in the X-axis direction (perpendicular to the Y-axis and Z-axis). It has a base part (311) and a turntable (312) attached to be rotatable about a vertical axis (B) extending in the vertical direction with respect to the base part (311). Specifically, the foundation (311) moves while being positioned in the X-axis direction by the linear servo motor. The turntable (312) rotates and moves while the rotation angle about the vertical axis (B) is positioned by the servo motor.

  The clamp part (320) rotatably supports the work (120) around a horizontal axis (A) extending in the horizontal direction. The horizontal axis (A) intersects the vertical axis (B) that is the center of rotation of the turntable (312). The clamp unit (320) rotates and moves the workpiece (120) while positioning the rotation angle around the horizontal axis (A) by a servo motor.

  The center (330) is slidable along the horizontal axis (A) on the rotary table (310), and the workpiece (120) is supported with respect to the rotation center of the workpiece (120) supported by the clamp part (320). It is comprised so that it may contact | abut from the front end side of (120). That is, the center (330) is centered on the center of rotation at the free end of the workpiece (120) clamped in a cantilevered manner by the clamp part (320), so that the horizontal part (A ) Shaking of the workpiece (120) driven to rotate around is prevented.

  In the workpiece support unit (300) configured as described above, the rotary table (310) is positioned at a desired position in the X direction in accordance with a control signal from the control device (500), and from the control device (500). In accordance with the control signal, the rotary table (312) of the rotary table (310) and the servo motor of the clamp part (320) are driven and controlled, so that the workpiece (120) rotates around the vertical axis (B) and the horizontal axis (A ) Positioned around.

  That is, as shown in FIG. 11, the machining apparatus (100) drives and controls the tool support unit (200) and the work support unit (300) in response to a control signal from the control apparatus (500). The tool (110) and the work (120) are relatively moved, and the work (120) is processed by the tool (110).

  Next, the control device (500) will be described in detail.

  As shown in FIG. 1, the control device (500) includes a tool path setting unit (510) for setting target tool path data, and an NC data generation unit (NC) for generating NC data for controlling the machining device (100). 520), an output unit (530) that outputs the NC data to the machining apparatus (100), a shape error measurement unit (540) that measures the shape error of the workpiece (120) after machining, and a target based on the shape error A tool path resetting unit (550) for resetting the tool path data. This control apparatus (500) comprises a control part.

  The tool path setting unit (510) receives the design data of the spiral groove (41) of the screw rotor (40), the shape of the workpiece (120) before processing, etc., and inputs the design data for the workpiece (120) based on these design data and the like. Calculate and set the target tool path data for the tool (110).

  Here, the target tool path data includes tool position vector data and tool posture vector data. The tool position vector is a vector of the position of the tool (110) in the workpiece coordinate system, for example, in the case of an end mill, the position of the tip of the rotating shaft. The tool position vector data is a set of the tool position vectors, and is data indicating a movement path of the tool (110) in the workpiece coordinate system. The tool posture vector is a vector indicating the posture of the tool (110) in the workpiece coordinate system, that is, the inclination of the tool (110). The tool posture vector data is a set of the tool posture vectors and is associated with the tool position vector data.

  The tool path setting unit (510) does not create and set the target tool path data from the design data of the screw rotor (40), but directly inputs the already determined target tool path data and sets it. It may be configured to.

  The NC data creation unit (520) is configured to generate NC data for driving the tool support unit (200) and the workpiece support unit (300) based on the target tool path data set by the tool path setting unit (510). (Numeric data) is created. This NC data is point group data composed of orthogonal three-axis position command data in the machine coordinate system of the machining apparatus (100) and rotational two-axis angle command data. The orthogonal three-axis position command data is point cloud data obtained by converting the tool position vector data of the target tool path data into the machine coordinate system, and includes the X coordinate of the rotary table (310) in the work support unit (300), and the tool. This corresponds to the Z coordinate of the column (210) and the Y coordinate of the base portion (230) in the support unit (200). Further, the angle command data of the two rotation axes is point cloud data obtained by converting the tool posture vector data of the target tool path data into the machine coordinate system, and is a turntable (310) of the turntable (310) in the work support unit (300). 312) corresponding to the rotation angle around the vertical axis (B) and the rotation angle around the horizontal axis (A) of the clamp part (320). The NC data includes speed command data and the like in addition to position command data and angle command data.

  The output unit (530) outputs a control signal to each linear servo motor and servo motor of the tool support unit (200) and the work support unit (300) based on the NC data from the NC data creation unit (520).

  Thus, the control signal is input from the output unit (530) to each linear servo motor and servo motor of the tool support unit (200) and the work support unit (300), whereby the tool support unit (200) and the work support unit ( 300) moves in response to the control signal, and as a result, the tool (110) moves along the desired target tool path with respect to the work (120), and the work (120) has a spiral groove (41). Processing.

  The spiral groove (41) is processed in the order of roughing, side wall finishing, and bottom wall finishing.

  Specifically, first, the end mill (110A) is mounted on the spindle part (220) via the end mill tool holder (250A), and the end mill (110A) is used to mount the work (120) as shown in FIG. 12 (a). Roughly process the spiral groove (41). At this time, a target tool path for rough machining is set as the target tool path of the end mill (110A), and the tool support unit (200) and the work support unit (300) are set according to the target tool path for rough machining. Driven. The solid line in the figure indicates the shape of the groove actually machined into the workpiece (120), and the broken line indicates the shape of the target spiral groove (41) to be machined into the workpiece (120).

  Subsequently, as shown in FIG. 12 (b), the side wall surface of the spiral groove (41) is finished by the end mill (110A). This finishing process is performed separately on both side walls of the spiral groove (41). At this time, different target tool paths are set for processing the first side wall surface (42) of the spiral groove (41) and for processing the second side wall surface (43), and the end mill (110A). Machine each side wall while moving along each target tool path. In addition, you may use the end mill for finishing different from the time of roughing at this time.

  Next, the tool (110B) is mounted on the spindle part (220) via the tool tool holder (250B), and the bottom wall surface of the spiral groove (41) is formed by the tool (110B) as shown in FIG. 12 (c). Finishing processing is performed. Here, the tip of the cutting tool (110B) has the same shape as the tip of the gate (51) of the gate rotor (50), and the tip of the cutting tool (110B) has a spiral groove (41). Cut the bottom wall. At this time, a target tool path corresponding to the finishing process by the cutting tool (110B) is set, and the cutting tool (110B) processes the bottom wall surface while moving along the target tool path. It is not necessary to finish the bottom wall surface of the spiral groove (41) by passing the cutting tool (110B) once, and the position of the spiral groove (41) in the groove width direction (and also the position in the depth direction) is changed. Then, the bottom wall surface of the spiral groove (41) may be finished by passing the spiral groove (41) a plurality of times through the cutting tool (110B).

  Here, in the roughing and side wall finishing by the end mill (110A), the end mill (110A) abuts the workpiece (120) at various angles in order to form desired rough grooves and side walls. Then, the workpiece (120) is cut.

  On the other hand, in the finishing process of the bottom wall surface by the cutting tool (110B), the cutting edge of the cutting tool (110B) was maintained in the same posture as the tip edge of the gate (51) meshing with the spiral groove (41). The workpiece (120) is cut in the state. That is, each gate (51) of the gate rotor (50) does not change the inclination with respect to the plane orthogonal to the rotation axis of the gate rotor (50) (that is, when the gate (51) is horizontal with respect to the orthogonal plane). (While still horizontal), while only changing the angle around the rotation axis of the gate rotor (50), it rotates in a plane perpendicular to the rotation axis. That is, the cutting tool (110B) also processes the bottom wall surface of the workpiece (120) without changing the inclination with respect to the plane orthogonal to the rotation axis of the gate rotor (50).

  As described above, the bottom wall surface of the spiral groove (41) is also cut when the side wall surfaces (42, 43) of the spiral groove (41) are processed by the end mill (110A). However, when processing the side wall surfaces (42, 43), the processing is performed with a focus on processing the side wall surfaces (42, 43) more accurately than the angle of the end mill (110A) with respect to the workpiece (120). And the end mill (110A) is cylindrical, unlike the tip of the gate (51), the bottom wall surface of the spiral groove (41) processed by the end mill (110A) The trajectory of the tip of the gate (51) passing through does not exactly match.

  Therefore, in this embodiment, after processing the side wall surface (42, 43) of the spiral groove (41) with the end mill (110A), the tip (110B) whose tip is the same shape as the tip of the gate (51) Is used to machine the bottom wall surface (44) of the spiral groove (41) while maintaining the same posture of the cutting tool (110B) as the tip of the gate (51) passing through the spiral groove (41). is doing. By doing so, the bottom wall surface (44) of the spiral groove (41) can be formed in the same shape as the locus of the tip of the gate (51).

  Thus, one workpiece (120) is machined into the screw rotor (40). If the machining of this workpiece (120) is continued, the blade of the tool (110) will eventually wear and the cutting force will decrease. When the cutting force decreases, the cutting resistance increases, and the reaction force that the tool (110) receives from the workpiece (120) increases. Then, even if the processing device (100) moves the tool (110) along the desired target tool path with respect to the workpiece (120), the tool (110) and the workpiece are changed according to the wear state of the tool (110). Since the degree of bending of (120) changes, the tool (110) passes through a path that is shifted from the desired target tool path by the amount of change in deflection with respect to the workpiece (120), and has a desired shape, that is, a desired spiral. It becomes difficult to process the groove (41) into the workpiece (120).

  Therefore, every time machining of one workpiece (120) is completed, the machining device (100) measures the shape of the workpiece (120) after machining, and determines the shape error from the desired screw rotor (40) shape. Measurement is performed, and the target tool path data is reset based on the shape error.

  Specifically, when the processing of one workpiece (120) is completed, the shape error measurement unit (540) of the control device (500) places the touch sensor (110C) on the tool support unit (200) as shown in FIG. The shape of the workpiece (120), specifically, the shape of the spiral groove (41) is measured. The touch sensor (110C) is configured to output a detection signal when the spherical tip contacts the workpiece (120), and the detection signal is input to the shape error measurement unit (540). It is configured. This touch sensor (110C) constitutes a shape measuring means.

  In the measurement of the shape error, a plurality of predetermined measurement points are set for each of the first and second side wall surfaces (42, 43) and the bottom wall surface (44), and the tool support unit (200) and the work support unit ( 300) is moved, and the shift amount of the wall surface in the normal direction at the measurement point is measured by the touch sensor (110C). Specifically, since the rough shape of the processed workpiece (120), that is, the approximate shape of the screw rotor and the geometric shape and insensitivity of the touch sensor (110C) are known in advance, a predetermined value in the spiral groove (41) of the workpiece (120) is obtained. The tool support unit (200) and the work support unit (300) are moved so that the tip of the touch sensor (110C) contacts the measurement point. At this time, if the workpiece (120) is machined as designed, the movement of the tool support unit (200) and the workpiece support unit (300) is completed (that is, the design shape of the screw rotor and the touch sensor (110C)). The tool support unit (200) and the work support unit (300) in the machine coordinate system up to the position where the tip of the touch sensor (110C) is predicted to reach a desired measurement point based on the geometric shape and the insensitive amount ) Is moved), the tip of the touch sensor (110C) comes into contact with a predetermined measurement point, and the touch sensor (110C) outputs a detection signal. At this time, the amount of displacement of the wall surface at the measurement point is zero. On the other hand, when the wall surface is raised above the target wall shape at the measurement point, the touch sensor (110C) outputs a detection signal before the tip of the touch sensor (110C) reaches the predetermined measurement point. Therefore, the shape error measuring unit (540) is configured to measure the wall surface in the normal direction from the machine coordinates of the tool support unit (200) and the workpiece support unit (300) when the detection signal is output. The amount of deviation is calculated and stored. On the other hand, if the wall surface is sinking below the target wall surface shape at the measurement point, the touch sensor (110C) outputs a detection signal even if the tip of the touch sensor (110C) reaches a predetermined measurement point. Therefore, when the detection signal is output, the shape error measurement unit (540) further moves the tool support unit (200) and the work support unit (300) until the touch sensor (110C) outputs the detection signal. The displacement amount of the wall surface in the normal direction at the measurement point is calculated and stored from the machine coordinates of the tool support unit (200) and the workpiece support unit (300). In this way, the shift amount in the normal direction at a plurality of measurement points for each wall surface is measured as a shape error.

  The shape is measured for each of the first and second side wall surfaces (42, 43) and the bottom wall surface (44), for example, for the first side wall surface (42) from the start side to the end side. Subsequently, the same measurement may be performed on the second side wall surface (43) and the bottom wall surface (44). For example, the first and second side wall surfaces located on the start end side are not distinguished for each wall surface. (42, 43) and the measurement points on the bottom wall surface (44) may be measured, and the measurement points on all the wall surfaces may be measured while moving from there to the terminal side.

  Thus, when the shape error is measured by the shape error measuring unit (540), the tool path resetting unit (550) resets the target tool path data based on the measured shape error. Specifically, the tool path resetting unit (550) decomposes the shape error of each wall surface as shown in FIG. 14 into a plurality of shape error modes that are patterned in advance, that is, a shape error component. For example, in the present embodiment, as shown in FIG. 15, there are six shape error modes, specifically, a mode in which one side in the width direction of the wall surface is raised at the start end side of the spiral groove (41), the width direction, and the like. The mode in which the side is raised, the mode in which one side in the width direction of the wall surface is raised in the middle part of the spiral groove (41), the mode in which the other side in the width direction is raised, and the one side in the width direction are raised at the end side of the spiral groove (41). And a mode in which the other side in the width direction is raised. Further, difference data to be given to the target tool path data in order to generate a corresponding shape error for each shape error mode (that is, a path deviation from the target tool path for generating the corresponding shape error) ΔPi (i = 1 ~ 6) is set.

  First, the error shape Error of each wall surface is approximated by a linear combination of basis vectors Ei (i = 1 to 6) corresponding to each shape error mode, as shown in Expression (1). At this time, the coefficient ei (i = 1 to 6) is obtained so that the residual when the shape error Error is represented by the basis vector Ei is minimized.

Error ≒ e1 × E1 + e2 × E2 + e3 × E3 + e4 × E4 + e5 × E5 + e6 × E6 (1)
Next, using the obtained coefficient ei (i = 1 to 6) and the difference data ΔPi (i = 1 to 6) for each shape error mode, the target tool path data P _n shown in the equation (2) is corrected. Data ΔP is created.

ΔP = e1 × ΔP1 + e2 × ΔP2 + e3 × ΔP3 + e4 × ΔP4 + e5 × ΔP5 + e6 × ΔP6 (2)
Using the correction data ΔP thus obtained, the target tool path data P0 _n is updated and new target tool path data P0 _{n + 1} is reset as shown in the equation (3).

P0 _{n + 1} = P0 _n −ΔP (3)
Note that the shape error mode, basis vectors, and difference data described above are prepared for each wall surface. However, regarding the bottom wall surface (44), most of the shape error caused by the wear of the tool (110) is an error in the depth direction of the spiral groove (41), that is, the normal direction of the bottom wall surface (44). The shape error mode to be prepared may be only one mode for translating the bottom wall surface (44) in the normal direction.

  In re-creating the target tool path data, it is not necessary to adopt the shape error at all measured measurement points, and the target tool path data is re-created using some representative shape errors among all the measurement points. You may create it.

  When the target tool path data is reset by the tool path resetting unit (550) in this way, the NC data generating unit (520) re-creates NC data based on the reset target tool path data. Then, the next workpiece (120) is processed by NC data based on the reset target tool path data. As a result, the machining apparatus (100) includes the tool support unit (200) and the work support unit (300) so that the tool (110) moves along the target tool path after resetting with respect to the work (120). Is controlled. At this time, the tool (110) is bent according to the wear state of the blade, and as a result, the tool (110) is moved by a deflection amount from the reset target tool path, and before the blade is worn, that is, the workpiece is processed. It will move approximately along the initial target tool path. As a result, a desired spiral groove (41) as designed is processed in the workpiece (120).

  Therefore, according to the present embodiment, after the machining of one workpiece (120) is completed, the shape error between the workpiece (120) after machining and the target workpiece shape is measured, and based on the shape error By resetting the target tool path data of the tool (110), when processing the next workpiece (120), the shape error at the time of the previous workpiece (120) processing is taken into consideration, that is, the shape error does not occur. Since the tool (110) processes the workpiece (120) along the target tool path corrected in (i), the workpiece (120) can be accurately processed into a desired shape.

  In addition, the NC data for controlling the machining device (100) is not directly corrected based on the shape error, but by re-setting the target tool path data, the target tool can flexibly cope with complicated shape errors. Route data, and hence NC data can be created. That is, among the shape errors, the shape error based on the deflection amount of the tool (110) and the work (120) due to wear of the tool (110) varies in a complicated manner depending on how the tool (110) is applied to the work (120). The amount of displacement of the shape error and the direction of displacement are not uniform depending on the location of the workpiece (120). Therefore, simply correcting the origin for the NC data only shifts the entire tool path uniformly in a specific direction. Therefore, the tool (110) is moved along the appropriate tool path corresponding to the shape error based on the wear of the tool. It cannot be moved. On the other hand, in this embodiment, since the target tool path data that is the basis of the NC data is recreated, appropriate target tool path data corresponding to a complicated shape error, and thus NC data can be recreated.

  Furthermore, in this embodiment, when re-creating the target tool path data based on the measured shape error, the target tool path data is not directly calculated from the shape error, but a plurality of shape errors are prepared in advance. The target tool path is obtained by adding / subtracting the difference data prepared in advance corresponding to each shape error mode to the original target tool path data according to the composition ratio of each shape error mode. The data is being recreated. By doing so, it is possible to greatly reduce the amount of calculation as compared with the method of directly calculating the target tool path data from the shape error, and it is possible to easily create the target tool path data corresponding to the shape error. .

  In the embodiment, the target tool path is reset every time machining of one workpiece (120) is completed, but the timing for resetting the target tool path is not limited to this. For example, the target tool path may be reset every time machining of a predetermined number of workpieces (120) is completed, or a workpiece that is being machined when a machining continuation time by the machining device (100) has passed a predetermined time The target tool path may be reset after the machining is completed. That is, the target tool path may be reset at an arbitrary timing as long as an unacceptable shape error is generated in the machining apparatus (100).

  Further, the method of re-creating the target tool path data based on the measured shape error is not limited to the above method. In other words, any method can be adopted as long as it can create target tool path data that can correct the measured shape error.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a screw rotor processing method and a processing apparatus for processing a screw rotor of a screw compressor.

It is a block diagram which shows the structure of the principal part of the control apparatus of the screw rotor processing apparatus which concerns on embodiment of this invention. It is a longitudinal cross-sectional view which shows the structure of the principal part of a single screw compressor. FIG. 3 is a transverse sectional view taken along line III-III in FIG. 2. It is a perspective view which extracts and shows the principal part of a single screw compressor. It is a perspective view which extracts and shows the principal part of a single screw compressor. It is a top view which shows operation | movement of the compression mechanism which concerns on embodiment, (A) shows a suction stroke, (B) shows a compression stroke, (C) shows a discharge stroke. It is a schematic perspective view which shows the whole structure of a screw rotor processing apparatus. It is a schematic perspective view which shows schematic structure of a spindle main body. It is a schematic perspective view which shows schematic structure of the tool holder for tools. It is a schematic perspective view which shows schematic structure of another spindle main body and the tool holder for tools. It is a schematic perspective view which shows the screw rotor processing apparatus at the time of a workpiece | work processing. It is a schematic explanatory drawing which shows the process sequence of a spiral groove, (A) shows rough processing, (B) shows the finishing process of a side wall surface, (C) shows the finishing process of a bottom wall surface. It is a schematic perspective view which shows the screw rotor processing apparatus at the time of the shape error measurement of a workpiece | work. It is explanatory drawing which shows the image of the measured shape error. It is explanatory drawing which shows a shape error mode. It is a top view which shows the structure of the principal part of a common single screw compressor.

1 Single screw compressor (screw compressor)
40 screw rotor
100 Screw rotor processing equipment (processing equipment)
110A end mill (tool)
110B byte (tool)
110C touch sensor (shape measuring means)
120 workpieces
500 Control device (control unit)

Claims (8)

Using the processing device (100) for processing the workpiece (120) with the tool (110) by relatively moving the tool (110) and the workpiece (120), the workpiece (120) is screwed into the screw compressor (1). A screw rotor machining method for machining into a rotor (40),
A tool path setting step for setting a target tool path of the tool (110) with respect to the workpiece (120) for processing into a desired screw rotor shape;
From the target tool path, a numerical data creation step of creating numerical data for moving the tool (110) and the workpiece (120) in the processing device (100),
The machining device (100) moves the tool (110) and the workpiece (120) based on the numerical data, respectively, and machining the workpiece (120) with the tool (110),
A shape error measuring step for measuring a shape error between the shape of the workpiece (120) after completion of machining and the desired screw rotor shape;
Look including the tool path resetting step of resetting the target tool path on the basis of the shape error measurement measured shape error in step,
The tool path resetting step includes
A mode decomposition step for decomposing the shape error into a plurality of pre-patterned shape error modes and obtaining a composition ratio of each shape error mode;
Characterized in that has Nde contains a correcting step for correcting the original target tool path at the allowed to correspond to each shape error mode multiplying the composition ratio of each of the shape error mode correction value prepared in advance by the value A screw rotor machining method.   In claim 1,
  In the mode decomposition step, the shape error is approximated by a linear combination of basis vectors corresponding to the shape error mode, so that the shape error is decomposed into a plurality of shape error modes, and the composition ratio of each shape error mode is determined. A screw rotor processing method characterized in that: In claim 1,
The tool path resetting step includes
A screw rotor machining method, comprising: resetting a target tool path when a predetermined timing has arrived and machining of a workpiece (120) being machined at that time is completed. In claim 1,
The tool path resetting step includes
A screw rotor machining method, wherein a target tool path is reset every time machining of one workpiece (120) is completed. A screw rotor processing apparatus for processing a work (120) into a screw rotor (40) of a screw compressor (1) by relatively moving a tool (110) and a work (120),
A target tool path of the tool (110) with respect to the work (120) for processing into a desired screw rotor shape is set, and the tool (110) and the work (120) are respectively moved from the target tool path. A control unit (500) that creates numerical data for causing the tool (110) to process the work (120) by moving the tool (110) and the work (120) based on the numerical data. )When,
And a shape measuring means (110C) for measuring the shape of the workpiece (120) after completion of machining,
The control unit (500) calculates a shape error between the shape of the workpiece (120) after completion of processing measured by the shape measuring means (110C) and the desired screw rotor shape, and the shape error is pre-patterned. Are divided into a plurality of shape error modes that have been formed, and the composition ratio of each shape error mode is obtained, and the configuration of each shape error mode is prepared in advance according to each shape error mode. A screw rotor machining apparatus characterized by correcting an original target tool path by multiplying a ratio and resetting the target tool path.   In claim 5,
  The control unit (500) decomposes the shape error into a plurality of shape error modes by approximating the shape error with a linear combination of basis vectors corresponding to the shape error mode, and forms each shape error mode. A screw rotor processing apparatus characterized by obtaining a ratio. In claim 5,
The control unit (500) resets the target tool path when a predetermined timing has come and when the machining of the workpiece (120) being machined at that time is completed. Screw rotor processing equipment. In claim 5,
The screw rotor machining apparatus, wherein the control unit (500) resets a target tool path every time machining of one workpiece (120) is completed.

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