JP2013050934A - Machining center and machining method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a machining center and a machining method capable of reducing a machining time by reducing effects of latency caused by executing a spindle rotation instruction for specifying a rotational speed.SOLUTION: When an instruction obtained from a working program is a rotation instruction for a spindle 5A for specifying a rotational speed, a machining center starts rotation of the spindle 5A, and obtains and executes a successive instruction from the working program without waiting until the rotational speed of the spindle 5A reaches a rotational speed threshold. Next, when a cutting movement instruction is obtained from the working program, the machining center determines whether or not the rotational speed of the spindle 5A reaches the rotational speed threshold, and then starts cutting movement for moving the spindle 5A close to a workpiece. The machining center sets a value obtained by multiplying the rotational speed specified by the rotation instruction by a predetermined rate A as the rotational speed threshold, and compares the rotational speed of the spindle 5A with the rotational speed threshold for the determination.

Description

  The present invention relates to a machine tool and a machining method for performing various machining and tool exchange in accordance with a machining program created by a user.

  In general, a machining center (machine tool) performs various processes such as milling and tapping. The machine tool includes a storage unit for storing a plurality of types of tools, and a mechanism for exchanging the tool mounted on the spindle with the tool stored in the storage unit. Various processes are continuously performed while changing the tool. The machining content for the workpiece is given as a machining program created in advance by the user. The machine tool implements a series of machining operations on a workpiece by sequentially reading and executing various commands such as a spindle movement command, a spindle rotation command, a machining position designation, and a tool change command included in the machining program.

  In Patent Document 1, a machine tool is described in which a spindle head on which a tool is mounted is moved in the Z-axis direction between a machining area and an exchange area to perform workpiece machining and tool exchange, respectively. This machine tool starts moving to the machining position when the spindle head reaches the simultaneous operation start position between the machining area and the exchange area. Compared to the conventional machine tool that starts moving to the machining position when the spindle head reaches the Z-axis origin, the machine tool of Patent Document 1 can complete the movement to the machining position at an earlier time. . In the machine tool described in Patent Document 1, the simultaneous operation start position can be designated by a machining program.

Japanese Patent Laid-Open No. 11-48072

  Conventionally, in a machining program for a machine tool, together with a tool change command (or after a tool change command), a rotation command for rotating the spindle with the tool changed by specifying the rotation speed of the spindle (or the number of rotations per unit time). Can be described. The machine tool changes the tool according to the tool change command, and then starts to rotate the spindle according to the rotation command. At this time, the conventional machine tool performs processing related to the next command of the machining program after confirming that the rotation speed of the spindle has reached the rotation speed specified by the rotation command. Since a certain amount of time is required from the start of rotation of the spindle to the designated rotational speed, this waiting time has a problem that the working time is prolonged.

  The present invention has been made in view of such circumstances. The object of the present invention is to reduce the influence of waiting time that occurs when executing a rotation command of a spindle with a specified rotation speed, and to reduce the work time. It is an object to provide a machine tool and a machine method that can be shortened.

  The machine tool according to the present invention stores a main shaft that is rotated with a tool mounted thereon, a moving means that moves the main shaft toward and away from the workpiece, and a command sequence in which commands related to the work are arranged in time series. Included in the instruction sequence, comprising: a storage unit; an acquisition unit that acquires an instruction in a time series from the instruction sequence stored in the storage unit; and a processing unit that executes a process related to the instruction acquired by the acquisition unit In a machine tool that performs processing on a workpiece by executing processing related to commands in a time series, when the acquisition unit acquires a rotation command of the spindle that specifies a rotation speed, the processing unit rotates the spindle The acquisition means continues to acquire the command following the rotation command, and when the acquisition means acquires a movement command to bring the main shaft closer to the workpiece, the rotation speed of the main shaft is changed to the rotation command. The Determination means for determining whether or not a predetermined rotation speed has been reached, and the processing means determines that the rotation speed specified by the rotation command has been reached, and then determines the movement command The main shaft is moved as described above.

  Further, in the machine tool according to the present invention, when the determination means reaches the rotation number obtained by multiplying the rotation speed specified by the rotation command by a predetermined ratio, It is characterized in that it is determined that the designated rotational speed has been reached.

  In the machine tool according to the present invention, the command sequence may include a ratio designation command for designating the predetermined ratio, and the determination means is based on the predetermined ratio designated by the ratio designation command. The rotational speed is determined.

  The machine tool according to the present invention is characterized in that the movement command for bringing the spindle close to the workpiece is a cutting movement command.

  In addition, the machining method according to the present invention includes a machine tool having a spindle that rotates with a tool mounted thereon and a moving unit that moves the spindle close to / separated from the workpiece. In a machining method for machining a workpiece by acquiring commands in a time series from the command sequence received and executing processing related to the acquired command, when acquiring the rotation command of the spindle that specifies the rotation speed, When the rotation command of the main shaft is started and the command following the rotation command is continuously acquired and the movement command for moving the main shaft closer to the workpiece is acquired, the rotation speed of the main shaft is determined by the rotation command. It is determined whether or not a specified rotation speed has been reached, and after determining that the rotation speed specified by the rotation command has been reached, the spindle according to the movement command is moved. .

In the present invention, when a command is acquired in a time series from a command sequence (machining program) stored in the storage unit, and the acquired command is a rotation command of a spindle with a specified rotation speed, the machine tool rotates the spindle However, the acquisition and execution of the next instruction is continued without waiting for the rotation speed of the spindle to reach the specified rotation speed. After that, when a movement command to move the spindle closer to the workpiece (that is, a machining start command) is acquired, it is determined whether or not the rotation speed of the spindle has reached the rotation speed specified by the rotation command. Move to move closer to the workpiece (start machining).
Even if a spindle rotation command with a specified rotation speed is acquired, the determination whether the spindle rotation speed has reached the specified rotation speed is postponed until the spindle movement command is executed By doing so, it becomes possible to execute another command between the rotation command and the movement command of the spindle. For this reason, it is possible to effectively utilize the time from the start of rotation of the spindle until the designated rotational speed is reached, and the working time can be shortened.

Also, when moving the spindle for machining with tool change, it takes a certain amount of time for the tool mounted on the spindle to move to the machining position where it contacts the workpiece from the standby position after tool exchange. At the start of spindle movement for machining, the spindle rotation speed does not necessarily reach the specified rotation speed. The spindle rotation speed does not necessarily reach the position where the tool contacts the workpiece. It is sufficient if the specified rotation speed is reached.
Therefore, in the present invention, before executing the spindle movement command, it is determined whether or not the rotation speed obtained by multiplying the rotation speed specified by the rotation command by a predetermined ratio has been reached, and the rotation speed multiplied by the predetermined ratio. If it has reached, the movement of the spindle is started. The predetermined ratio can be determined in advance at the design stage of the machine tool based on the moving speed of the main shaft and the rotational acceleration of the main shaft. Thereby, since the movement of the spindle for machining can be started at an earlier timing, the machining time can be further shortened.

  In the present invention, the user can specify the predetermined ratio by a machining program. The machine tool uses a value obtained by multiplying the designated predetermined ratio by the rotation speed designated by the rotation command as a threshold for determination. Thereby, the freedom degree of creation of the machining program by a user improves.

In the present invention, the movement command for bringing the spindle close to the workpiece is a cutting movement command. When the movement command for moving the spindle closer to the workpiece is a cutting movement command, if the cutting movement command is executed without the rotation speed of the spindle reaching the rotation speed specified in the rotation command, The change of the rotation speed becomes larger. If the change in the rotation speed of the main spindle becomes large during workpiece machining, there is a problem that machining patterns are conspicuous on the workpiece machining surface and machining defects occur.
In the present invention, the cutting movement command is not executed until the rotational speed of the main shaft is such that no machining pattern is generated on the machining surface of the workpiece, so that no machining failure occurs.

  In the case of the present invention, even if a spindle rotation command specifying the rotation speed is acquired, it is determined whether or not the spindle rotation speed has reached the specified rotation speed by executing the spindle movement command. By adopting a configuration in which it is advanced to the front, other commands can be executed during the period from the start of rotation of the spindle until the designated rotational speed is reached, so that the working time can be shortened.

It is a perspective view which shows the external appearance of a machining center (machine tool). It is a front view which shows the structure of the principal part of a machining center. It is a block diagram which shows the electrical structure of a machining center. It is a schematic diagram which shows an example of the processing program memorize | stored in EEPROM. It is a timing chart for explaining an example of operation of a machining center. It is a flowchart which shows the process sequence of the processing program by a machining center. It is a flowchart which shows the process sequence of the processing program by a machining center. It is a schematic diagram which shows an example of the processing program which concerns on a modification.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. FIG. 1 is a perspective view showing an appearance of a machining center (machine tool). FIG. 2 is a front view showing the configuration of the main part of the machining center. The machining center according to the present embodiment can perform desired machining (for example, slicing, drilling, cutting, etc.) on a workpiece by relatively moving a workpiece (not shown) to be processed and a tool. It is a machine tool that can. The machining center includes a metal base 1, and legs are provided at the four corners of the lower part of the base 1, and these four legs are installed on the floor or the like, so that the machining center is installed at a predetermined place. The The base 1 is a rectangular parallelepiped casting that is long in the front-rear direction of the machining center.

  A column seat 3 is provided on the rear portion of the base 1 of the machining center, and a columnar column 4 extending vertically upward is erected on the column seat 3. The column 4 is provided with a spindle head 5 that can move up and down along the front surface thereof. The spindle head 5 is provided with a spindle 5A on which a machining tool 6 is mounted, and a tool exchange mechanism 7 for exchanging the tool 6 mounted on the spindle 5A with another tool 6. Although not shown in FIG. 1, a Z-axis motor 44 (see FIG. 3) is provided at the top of the column 4, and the spindle head 5 can be moved up and down by the rotation of the Z-axis motor 44.

  A spindle 5A corresponding to a machining axis is rotatably mounted on the spindle head 5, and a spindle motor 41 (see FIG. 3) for rotationally driving the spindle 5A is provided at the top. A tool 6 is detachably attached to the lower end of the main shaft 5A, and the main shaft 5A is rotationally driven by the main shaft motor 41, whereby the tool 6 rotates and a workpiece fixed to the table 8 is processed. The spindle 5A moves between an upper exchange position and a lower machining position by the vertical movement of the spindle head 5. The tool change mechanism 7 holds and conveys a tool magazine 14 that stores a plurality of tool holders that support the tool 6, a tool holder that is mounted on the spindle 5A, and another tool holder that is stored in the tool magazine 14, And a tool changing arm 15 for changing the tool.

  Further, on the base 1, a table 8 is disposed below the spindle head 5 so that a work can be detachably fixed. The table 8 is controlled to move in the X-axis direction (left-right direction) and the Y-axis direction (front-rear direction) by an X-axis motor 42 and a Y-axis motor 43 (see FIG. 3) which are servo motors. Specifically, a rectangular parallelepiped support base 10 is provided below the table 8, and the support base 10 is provided with a pair of X-axis feed guides extending along the X-axis direction, and a pair of X-axis feed guides. A table 8 is movably supported on the top. In addition, a pair of Y-axis feed guides extending in the longitudinal direction (Y-axis direction) is provided on the upper portion of the base 1, and the support base 10 is movably supported on the pair of Y-axis feed guides. . A Y-axis motor 43 provided on the base 1 moves and drives the support base 10 in the Y-axis direction along the Y-axis feed guide, and an X-axis motor 42 provided on the support base 10 follows the X-axis feed guide. Then, the table 8 is driven to move in the X-axis direction.

  The X-axis feed guide is provided with telescopic covers 11 and 12 that contract telescopically on both the left and right sides of the table 8. In the Y-axis feed guide, a telescopic cover 13 and a Y-axis rear cover are provided on the front and rear sides of the support base 10, respectively. The X-axis feed guide and the Y-axis feed guide are always covered by the telescopic covers 11, 12, 13 and the Y-axis rear cover, regardless of which direction the table 8 and the support base 10 are moved. The telescopic covers 11, 12, 13 and the Y-axis rear cover are for preventing chips or the like scattered from the workpiece processing region from dropping onto the X-axis feed guide, the Y-axis feed guide, and the like.

  A box-shaped control box 9 is provided on the back side of the column 4, and a control unit 20 (see FIG. 3) for controlling the operation of the machining center is accommodated in the control box 9. FIG. 3 is a block diagram showing an electrical configuration of the machining center. The control unit 20 of the machining center includes a CPU 21, a ROM 22, a RAM 23, an EEPROM 24, an input interface 25, an output interface 26, and the like.

  The CPU 21 reads the control program stored in the ROM 22 into the RAM 23 and executes it, thereby performing workpiece machining processing, tool change processing, and the like. The ROM 22 is a non-volatile memory element such as a mask ROM or EEPROM, and stores a control program executed by the CPU 21 and various data necessary for processing. The RAM 23 is a memory element such as SRAM or DRAM, and temporarily stores a control program read from the ROM 22 and various data generated in the process. The EEPROM 24 is a non-volatile memory element that can rewrite data, and stores various data necessary for processing. Particularly in the present embodiment, a machining program (described later) in which machining procedures and machining conditions for the workpiece are described is stored in the EEPROM 24. Note that a nonvolatile memory element such as a flash memory may be used instead of the EEPROM 24.

  The machining center includes an input device 31, an arm sensor 32, a Z-axis sensor 33, a main shaft sensor 34, and the like, and these are connected to the input interface 25 of the control unit 20. The input device 31 uses a keyboard or a touch panel, and accepts user operations. The arm sensor 32 detects whether or not the tool change arm 15 has been raised to the origin (uppermost position). The Z-axis sensor 33 detects whether or not the main shaft 5A has moved up to the replacement position for replacing the tool 6. The main shaft sensor 34 detects the rotational speed of the main shaft 5A. The input interface 25 gives information output from the input device 31, arm sensor 32, Z-axis sensor 33, and spindle sensor 34 to the CPU 21. Instead of the Z-axis sensor 33 and the spindle sensor 34, feedback information of the Z-axis motor 44 and the spindle motor 41 may be used.

  The machining center includes a spindle motor 41, an X-axis motor 42, a Y-axis motor 43, a Z-axis motor 44, a tool change motor 45, a display device 46, and the like, which are connected to the output interface 26 of the control unit 20. . The main shaft motor 41 is for rotating the main shaft 5A, and can thereby process a workpiece using the tool 6 attached to the main shaft 5A. The X-axis motor 42 and the Y-axis motor 43 are motors for moving the table 8 in the X direction and the Y direction. The Z-axis motor 44 is a motor for vertically moving the spindle head 5 with respect to the column 4 in the vertical direction. The tool change motor 45 is a motor for performing tool change operations such as attachment / detachment of the tool 6 to / from the main shaft 5A, vertical movement and rotation of the tool change arm 15, and gripping of the tool 6. The display device 46 is a liquid crystal panel or the like, and displays an operation state of the machining center or a message to the user.

  FIG. 4 is a schematic diagram illustrating an example of a machining program stored in the EEPROM 24. The machining program is created in advance by the user in accordance with the machining content of the workpiece, and is stored in the EEPROM 24 in advance. The CPU 21 of the machining center reads the machining program one line at a time and processes the commands described in each line in order. For example, G100 described in the N1 line of the illustrated machining program indicates a tool change command, T1 indicates that the identification number of the tool 6 to be mounted next on the spindle 5A is No. 1, and Z200 indicates after tool change. It shows that the standby position in the Z-axis direction is 200. In the N1 line, a rotation command M3 for the main shaft 5A is described following the tool change command, and S10000 designates 10,000 rotations / minute as the rotation speed of the main shaft 5A. The tool change command and the spindle rotation command may not be described on the same line in the machining program but may be described on different lines.

  M77 described in the N2th line is an instruction to fix the processing jig to the clamp device. Each command of M400 described in the N3 line, M494 described in the N4 line, and M8 described in the N5 line is the removal and cooling of chips by discharging coolant (cutting fluid). Is for doing. The machining center is provided with a plurality of mechanisms for discharging the coolant, and the commands in the N3th to N5th lines operate the coolant discharge mechanism in order. M400 is a chip shower discharge command, M494 is a CTS coolant discharge command, and M8 is another coolant discharge command. The CTS is provided with a flow path through which coolant flows in the main shaft 5A, and discharges the coolant from the tip of the tool 6 by connecting this flow path and the flow path provided in the tool 6. The chip shower prevents the accumulation of chips around the table 8 by discharging coolant from a chip shower pipe arranged in the machining center. A detailed description of these coolant discharge mechanisms will be omitted.

  G1 described in the N6th line is a cutting movement command of the main shaft 5A, and Z198 indicates that the machining position in the Z-axis direction is 198. By this command, the spindle 5A that has been waiting at the position 200 in the Z-axis direction according to the command in the N1th line is lowered to the position 198 in the Z-axis direction, and the workpiece is processed by the tool 6 attached to the spindle 5A. .

  The conventional machining center waits until the designated rotational speed is reached after driving the spindle motor 41 to start the rotation of the spindle 5A when processing the rotation command of the spindle 5A in the N1th row. N2 line and subsequent instructions were processed. On the other hand, the machining center according to the present embodiment starts the rotation of the main shaft 5A by driving the main shaft motor 41 in response to the rotation command of the main shaft 5A, and then determines the rotation speed of the main shaft 5A. Can be read and processed.

  FIG. 5 is a timing chart for explaining an example of the operation of the machining center, and shows the operation corresponding to the machining program shown in FIG. The upper part of FIG. 5 shows the coordinates (position) of the main shaft 5A in the Z-axis direction, and the lower part shows the rotational speed of the main shaft 5A. The CPU 21 of the machining center reads the tool change command on the N1th line of the machining program, thereby driving the Z-axis motor 44 to raise the spindle 5A to the tool change position in the Z-axis direction (0 to t1). The tool is changed by driving the motor 45 (t1 to t2). After completing the tool change, the CPU 21 starts to lower the spindle 5A by driving the Z-axis motor 44 to the standby position 200 in the Z-axis direction designated by the tool change command (t2).

  In the machining center, the spindle 5A cannot be rotated at the tool change position, and the spindle 5A can be rotated below a predetermined rotatable position. The CPU 21 that has started to lower the spindle 5A after completing the tool replacement, when the position of the spindle 5A in the Z-axis direction reaches the rotatable position (t3), follows the rotation command described in the N1th line of the machining program in accordance with the spindle motor. 41 is driven to start the rotation of the main shaft 5A. As a result, the rotational speed of the main shaft 5A increases at a substantially constant acceleration.

  When the spindle 5A continues to descend in the Z-axis direction and reaches the standby position specified in the N1 line of the machining program (t4), the CPU 21 sequentially issues the commands in the N2 line to the N5 line of the machining program. (T4 to t5). After finishing the processing on the N5th line of the machining program, the CPU 21 reads the cutting movement command on the N6th line. At this time, the CPU 21 determines that the rotation speed of the spindle 5A detected by the spindle sensor 34 is the rotation speed (0 <A ≦ 1) multiplied by the rotation speed specified by the rotation command in the N1th row. Hereinafter, it is determined whether or not the rotation speed threshold value has been reached. When the rotation speed of the spindle 5A has not reached the rotation speed threshold, the CPU 21 waits for execution of the cutting movement command. When the rotation speed of the main shaft 5A reaches the rotation speed threshold (t6), the CPU 21 drives the Z-axis motor 44 to start lowering the main shaft 5A to the position in the Z-axis direction designated by the cutting movement command. . Thereafter, the rotational speed of the main shaft 5A reaches the rotational speed specified by the rotation command of the N1 line, and the position of the main shaft 5A in the Z-axis direction reaches the position specified by the cutting movement command of the N6 line. Machining for the workpiece is started.

  The predetermined ratio A for determining the rotation speed threshold is the rotation acceleration of the main shaft 5A, the moving speed of the main shaft 5A in the Z-axis direction, the standby position specified by the tool change command on the N1 line, and the N6 line. It can be calculated according to the distance between the machining positions designated by the cutting movement command. That is, when the spindle 5A moves in the Z-axis direction and reaches the machining position (or before reaching), the rotational speed estimated to reach the target rotational speed is calculated backward to obtain the rotational speed threshold value. The ratio of the rotation speed threshold to the target rotation speed may be set to the predetermined ratio A. As the predetermined ratio A, a predetermined value may be used, or the CPU 21 may dynamically calculate the predetermined ratio A.

  As described above, the machining center according to the present embodiment only starts the rotation of the spindle 5A even when the rotation command of the spindle 5A with the rotation speed specified in the N1th line of the machining program is read. The next instruction (N2 line to N5 line) of the machining program is executed without determining whether or not the rotation speed of the spindle 5A has reached the specified rotation speed. Thereafter, the machining center determines whether or not the rotation speed of the spindle 5A has reached the rotation speed threshold when the cutting movement command is read in the N6th line of the machining program, and when the rotation speed threshold is reached, the spindle Start cutting movement of 5A. As a result, the machining center parallels the rotation (acceleration) of the spindle 5A to the specified rotation speed and other commands (such as commands in the N2 to N5 rows) until the cutting movement command is read. Therefore, the working time can be shortened.

  6 and 7 are flowcharts showing the processing procedure of the machining program by the machining center. First, the CPU 21 of the machining center reads out an instruction for one line from the machining program stored in the EEPROM 24 (step S1). Next, it is determined whether or not the read command is a command to end the work (step S2). If the read command is a work end command (S2: YES), the CPU 21 ends the work processing for the workpiece.

  When the read command is not a work end command (S2: NO), the CPU 21 determines whether or not the read command is a tool change command (step S3). When the read command is a tool change command (S3: YES), the CPU 21 raises the spindle 5A to the tool change position to change the tool, and then performs a tool change operation for moving the spindle 5A to the standby position (step). S4). In the process of the tool change operation, the CPU 21 determines whether or not the main shaft 5A has reached the rotatable position (step S5). If the spindle 21 has not reached the rotatable position (S5: NO), the tool change operation is continued. . When the main shaft 5A reaches the rotatable position (S5: YES), the CPU 21 further determines whether or not the rotation command for the main shaft 5A is included in the same row as the tool change command (step S6). When the rotation command is not included (S6: NO), the CPU 21 returns the process to step S1 after the tool change operation is completed, and when the rotation command is included (S6: YES), The spindle motor 41 is driven to start rotation of the spindle 5A (step S7), and the process returns to step S1 after the tool change operation is completed.

  When the read command is not a tool change command (S3: NO), the CPU 21 determines whether or not the read command is a rotation command for the spindle 5A (step S8). When the read command is a rotation command (S8: YES), the CPU 21 drives the spindle motor 41 to start the rotation of the spindle 5A (step S7), and returns the process to step S1.

  When the read command is not a rotation command (S8: NO), the CPU 21 determines whether or not the read command is a cutting movement command (step S9). When the read command is a cutting movement command (S9: YES), the CPU 21 determines whether or not the rotation speed of the spindle 5A detected by the spindle sensor 34 is equal to or higher than the rotation speed threshold (step S10). When the rotation speed of the main shaft 5A is less than the rotation speed threshold (S10: NO), the CPU 21 waits until the rotation speed of the main shaft 5A becomes equal to or higher than the rotation speed threshold. When the rotation speed of the main shaft 5A is equal to or higher than the rotation speed (S10: YES), the CPU 21 drives the Z-axis motor 44 to start cutting movement (step S11), and returns the process to step S1.

  When the read command is not a cutting movement command (S9: NO), the CPU 21 performs other operations according to the read command (step S12), and returns the process to step S1. The CPU 21 of the machining center repeatedly performs the processing of steps S1 to S12 until the machining end command of the machining program is read, and performs various machining on the workpiece by processing the commands described in the machining program line by line.

  The machining center having the above configuration starts rotation of the spindle 5A when the command acquired from the machining program is a rotation command of the spindle 5A that specifies the rotation speed, but the rotation speed of the spindle 5A reaches the rotation speed threshold. Without waiting, the next instruction of the machining program is acquired and executed. Thereafter, when the machining center obtains a cutting movement command from the machining program, it determines whether or not the rotation speed of the spindle 5A has reached the rotation speed threshold, and then starts cutting movement that brings the spindle 5A close to the workpiece. Thus, even if it is a case where the rotation command of the main shaft 5A is acquired, the determination as to whether or not the rotation speed of the main shaft 5A has reached the rotation speed threshold value is postponed until the execution of the cutting movement command. Thus, another command can be executed between the rotation command of the spindle 5A and the cutting movement command. For this reason, the time from the start of rotation of the spindle 5A until the rotation speed reaches the rotation speed threshold can be effectively utilized, and the working time can be shortened.

  Further, the machining center is configured to use a value obtained by multiplying the rotation speed designated by the rotation command by a predetermined ratio A as a rotation speed threshold, and to compare the rotation speed threshold when determining the rotation speed of the spindle 5A. The cutting movement command can be started at an earlier timing than in the case of comparing with the designated rotational speed, and the machining time can be further shortened.

  In the present embodiment, a value obtained by multiplying the rotation speed specified by the rotation command by a predetermined ratio A is set as a rotation speed threshold, and it is determined whether or not the rotation speed of the spindle 5A has reached the rotation speed threshold. However, the present invention is not limited to this, and it may be configured to determine whether or not the rotation speed of the spindle 5A has reached the rotation speed specified by the rotation command (that is, the predetermined ratio A = 1). May be). Further, the machining program shown in FIG. 4 is an example, and the present invention is not limited to this. In particular, the command executed between the rotation command of the spindle 5A and the cutting movement command is not limited to the command shown in the N2 to N5 lines in FIG. 4 and may be other various commands.

(Modification)
In the above-described embodiment, the predetermined ratio A for calculating the rotation speed threshold is a value dynamically calculated based on information such as the rotation acceleration of the main shaft 5A and the movement speed in the Z-axis direction, or is determined in advance. Although a value is used, the present invention is not limited to this. The machining center according to the modification is configured such that the user can set the value of the predetermined ratio A in the machining program.

  FIG. 8 is a schematic diagram illustrating an example of a machining program according to a modification. In the illustrated machining program, an instruction to set a value of a predetermined ratio A as the N0 line is described before the N1 line tool change instruction (for example, the predetermined ratio A is set to 0.8). ) When the CPU 21 of the machining center according to the modification reads the setting command for the predetermined ratio A from the machining program, the rotation speed based on the predetermined ratio A specified by the setting command in the subsequent rotation speed determination before the cutting movement command. Judgment is performed using a threshold value.

  Thus, by allowing the user to specify a predetermined ratio A for determining the rotation speed threshold for determining the rotation speed of the spindle A in the machining program, the degree of freedom in creating the machining program by the user can be increased. Can be improved. When the predetermined ratio A is not set in the machining program, the machining center may determine the rotation speed using a predetermined default ratio A. In FIG. 8, the setting command for the predetermined ratio A is described immediately before the line in which the rotation command is described, but is not limited thereto, and may be described at least before the cutting movement command.

  In the present embodiment, the machining center using the tool changing arm 15 has been described as an example of the tool changing method. However, the present invention is not limited to this, and the present invention is applied to a machining center employing another tool changing method. May be. For example, the tool mounted on the spindle is mounted on the tool magazine by raising the spindle head, and then the tool magazine is rotated and positioned at a predetermined position, and then the spindle head is lowered so that the tool magazine is gripped by the spindle. It may be a tool change system in which a tool is mounted.

4 Column 5 Spindle head (moving means)
5A Spindle 6 Tool 7 Tool change mechanism 8 Table 9 Control box 14 Tool magazine 15 Tool change arm 20 Control unit 21 CPU (Acquisition means, processing means, determination means)
22 ROM
23 RAM
24 EEPROM (storage unit)
33 Z-axis sensor 34 Spindle sensor 41 Spindle motor 42 X-axis motor 43 Y-axis motor 44 Z-axis motor (moving means)
45 Tool change motor

Claims (5)

A spindle that rotates with a tool mounted thereon, a moving means that moves the spindle closer to or away from the workpiece, a storage unit that stores a command sequence in which commands related to work are arranged in time series, and the storage unit An acquisition means for acquiring instructions in a time series from a stored instruction sequence; and a processing means for executing a process related to the instructions acquired by the acquisition means. In machine tools that perform machining on workpieces,
When the acquisition means acquires the rotation command of the spindle that specifies the rotation speed, the processing means starts rotation of the spindle, and the acquisition means continues to acquire the command following the rotation command,
When the acquisition means acquires a movement command for bringing the spindle closer to the workpiece, the determination means comprises a determination means for determining whether or not the rotation speed of the spindle has reached the rotation speed specified by the rotation command,
The machine tool according to claim 1, wherein the processing means moves the spindle according to the movement command after the determination means determines that the rotation speed specified by the rotation command has been reached. The determination means determines that the rotation speed specified by the rotation command has been reached when the rotation speed of the spindle reaches a rotation speed obtained by multiplying the rotation speed specified by the rotation command by a predetermined ratio. The machine tool according to claim 1, wherein the machine tool is configured as described above. The instruction sequence can include a ratio specifying instruction for specifying the predetermined ratio,
The machine tool according to claim 2, wherein the determination unit is configured to determine the rotational speed based on a predetermined ratio designated by the ratio designation command. The machine tool according to any one of claims 1 to 3, wherein the movement command for causing the spindle to approach the workpiece is a cutting movement command. For a machine tool having a spindle that rotates with a tool mounted thereon and a moving means that moves the spindle close to / separated from the workpiece, commands related to the work are ordered in a time series. In a machining method for machining a workpiece by executing a process related to the obtained command,
When acquiring the rotation command of the spindle that specifies the rotation speed, start the rotation of the spindle and continuously acquire the command following the rotation command,
When obtaining a movement command to bring the spindle closer to the workpiece, it is determined whether or not the rotation speed of the spindle has reached the rotation speed specified by the rotation command;
After determining that the rotation speed specified by the rotation command has been reached, the working method moves the spindle according to the movement command.

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