Control devices, machine tools, control methods, and computer programs

Abstract

The present invention provides a control device, a machine tool, a control method, and a computer program that can achieve both acceleration suppression and reduction of the time required to stop the spindle during operation. [Solution] In a control device for controlling the rotational speed of a spindle, when the control device obtains an upper limit rotational speed indicating the upper limit of the rotational speed of the spindle and an upper limit acceleration indicating the upper limit of the acceleration of the spindle, it determines whether the upper limit rotational speed is less than or equal to a limit rotational speed that is determined according to the upper limit acceleration and at which the spindle can be stopped within a predetermined time while rotating. If it determines that the upper limit rotational speed is not less than or equal to the limit rotational speed, it outputs a signal indicating an abnormality.

Description

Technical Field

[0001] The present technology relates to a control device for controlling the rotational speed of a spindle, a machine tool, a control method, and a computer program.

Background Art

[0002] There is a machine tool including a spindle for mounting a tool, a spindle motor for driving the spindle, and a control device for controlling the spindle. The control device calculates the output torque and acceleration of the spindle motor and estimates the inertia of the tool. When the estimated inertia is greater than a predetermined threshold value, an error is notified. Thereby, the possibility that the connection position between the output shaft of the spindle motor and the spindle is displaced can be reduced (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When a tool with a large inertia is mounted on the spindle and the spindle is rotated, there is a problem that the tool slips in the spindle, causing damage to the drive key or misalignment of the coupling. To avoid this problem, it is conceivable to limit the acceleration of the spindle motor. However, when the acceleration of the spindle motor is small, the time from the start to the completion of the stop of the spindle becomes long. For example, when performing an emergency stop during a power failure, there is a risk that the stop of the spindle will not be completed within a predetermined time during which the power supplied to the control device can be maintained.

[0005] The present disclosure has been made in view of such circumstances, and an object thereof is to provide a control device, a machine tool, a control method, and a computer program capable of achieving both suppression of acceleration and stopping a driving spindle within a predetermined time during which the power supplied to the control device can be maintained. [Means for solving the problem]

[0006] A control device according to one embodiment of the present disclosure is a control device for controlling a spindle on which a tool is mounted. When the rotational speed of the spindle and the tool upper limit acceleration, which indicates the upper limit of the acceleration of the spindle corresponding to the tool, are obtained, the control device performs a calculation process to calculate a limit rotational speed, which is the rotational speed at which the spindle, which is rotating, can be stopped within a predetermined time according to the tool upper limit acceleration, a determination process to determine whether the rotational speed of the spindle is less than or equal to the calculated limit rotational speed, and an output process to output a signal indicating an abnormality if it is determined that the rotational speed of the spindle is not less than or equal to the limit rotational speed.

[0007] In this disclosure, when the spindle speed and the tool's upper limit acceleration are obtained, the limit speed is calculated according to the tool's upper limit acceleration. It is determined whether the spindle speed is below the limit speed, and if it is determined that the spindle speed is not below the limit speed, a signal indicating an abnormality is output.

[0008] A control device according to one embodiment of the present disclosure includes a storage device, the tool upper limit acceleration is provided for each tool, the storage device stores a plurality of tool upper limit accelerations provided for each tool, and the calculation process obtains the tool upper limit acceleration of the tool mounted on the spindle from the storage device and calculates the limit rotation speed according to the tool upper limit acceleration.

[0009] In this disclosure, a tool upper acceleration limit is set for each tool, and multiple tool upper acceleration limits set for each tool are stored. The limit rotational speed is calculated according to the tool upper acceleration limit of the tool mounted on the spindle.

[0010] A control device according to one embodiment of the present disclosure acquires the upper limit acceleration for each tool corresponding to a plurality of tools and calculates the limit rotational speed according to the upper limit acceleration of the tools.

[0011] In this disclosure, the upper limit acceleration of each tool is obtained, and the limit rotational speed is calculated according to the upper limit acceleration of the tool.

[0012] A control device according to one embodiment of the present disclosure includes a storage device, wherein a tool upper limit rotation speed, which is the upper limit of the rotation speed of the spindle, is set for each tool, the storage device stores a plurality of tool upper limit rotation speeds set for each tool, the determination process determines whether the tool upper limit rotation speed of each tool stored in the storage device is less than or equal to the limit rotation speed calculated in the calculation process, and the output process outputs a signal indicating an abnormality if the determination process determines that the tool upper limit rotation speed is not less than or equal to the limit rotation speed.

[0013] In this disclosure, it is determined whether the maximum rotational speed of each tool is less than or equal to the limit rotational speed, and if it is determined that the maximum rotational speed of the tool is not less than or equal to the limit rotational speed, an abnormality is displayed.

[0014] A control device according to one embodiment of the present disclosure acquires a command rotation speed for executing a spindle rotation command, and if the determination process determines that the tool upper limit rotation speed is less than or equal to the limit rotation speed, it executes a second determination process to determine whether the command rotation speed is less than or equal to the tool upper limit rotation speed, and if the second determination process determines that the command rotation speed is not less than or equal to the tool upper limit rotation speed, the output process outputs a signal indicating an abnormality.

[0015] In this disclosure, the command rotation speed for executing the spindle rotation command is obtained, and if it is determined that the tool upper limit rotation speed is less than or equal to the limit rotation speed, it is determined whether or not the command rotation speed is less than or equal to the tool upper limit rotation speed, and if it is determined that the command rotation speed is not less than or equal to the tool upper limit rotation speed, an abnormality is displayed.

[0016] A control device according to one embodiment of the present disclosure acquires the tool's upper limit rotational speed and the tool's upper limit acceleration from a receiving unit that receives information input.

[0017] In this disclosure, for example, an operator inputs information into a reception unit, and the control device obtains the maximum tool rotational speed and maximum tool acceleration from the reception unit.

[0018] In one embodiment of the present disclosure, the control device performs the following when the spindle, which is equipped with a tool whose upper limit rotational speed is less than or equal to the limit rotational speed, is performing rotational processing at a predetermined rotational speed, a change determination process to determine whether or not a change command to change the rotational speed has been obtained; a rotational speed determination process to determine whether or not the changed rotational speed is less than or equal to the limit rotational speed, if it is determined that the change command has been obtained; a rotational speed change process to rotate the spindle at the changed rotational speed, if the changed rotational speed is less than or equal to the limit rotational speed, and a limit rotational speed change process to rotate the spindle at the limit rotational speed, if the changed rotational speed is not less than or equal to the limit rotational speed.

[0019] In this disclosure, if the changed rotational speed of the tool mounted on the spindle is less than or equal to the limit rotational speed, the spindle is rotated at the changed rotational speed; if the changed rotational speed is not less than or equal to the limit rotational speed, the spindle is rotated at the limit rotational speed.

[0020] In one embodiment of the present disclosure, when a control device reads and executes a command to rotate the spindle from a program for machining a workpiece, it obtains the upper limit rotational speed of the tool mounted on the spindle and the upper limit acceleration of the tool mounted on the spindle from the program, and if it determines that the upper limit rotational speed of the tool is not less than or equal to the limit rotational speed, it performs a signal output process that outputs a signal to stop the spindle.

[0021] In this disclosure, when a command to rotate the spindle is read from a program for machining a workpiece and executed, the program obtains the upper limit rotational speed of the tool mounted on the spindle and the upper limit acceleration of the tool mounted on the spindle, and if it is determined that the upper limit rotational speed is not less than or equal to the limit rotational speed, a signal to stop the spindle is output.

[0022] In one embodiment of the present disclosure, the control device determines that the tool's upper limit rotational speed is not less than or equal to the limit rotational speed, and then executes a display signal output process that outputs a signal indicating the tool's upper limit rotational speed.

[0023] In the present disclosure, when it is determined that the upper limit rotational speed of the tool is not less than the limit rotational speed, the upper limit rotational speed of the tool is displayed and notified to the operator.

[0024] In a machine tool according to an embodiment of the present disclosure, which includes a spindle for mounting a tool and a control device for controlling the spindle, when the control device acquires the rotational speed of the spindle and the tool upper limit acceleration indicating the upper limit of the acceleration of the spindle corresponding to the tool, the control device determines whether the rotational speed of the spindle is less than or equal to a limit rotational speed determined according to the tool upper limit acceleration and indicating the rotational speed at which the rotating spindle can stop within a predetermined time, and when it is determined that the rotational speed of the spindle is not less than or equal to the limit rotational speed, executes an output process of outputting a signal for displaying an abnormality.

[0025] In the present disclosure, when the rotational speed of the spindle and the tool upper limit acceleration are acquired, the limit rotational speed is calculated according to the tool upper limit acceleration. It is determined whether the rotational speed of the spindle is less than or equal to the limit rotational speed, and when it is determined that the rotational speed of the spindle is not less than or equal to the limit rotational speed, a signal for displaying an abnormality is output.

[0026] In a control method according to an embodiment of the present disclosure, in a control method for controlling a spindle for mounting a tool, when the rotational speed of the spindle and the tool upper limit acceleration indicating the upper limit of the acceleration of the spindle corresponding to the tool are acquired, the control method determines whether the rotational speed of the spindle is less than or equal to a limit rotational speed determined according to the tool upper limit acceleration and indicating the rotational speed at which the rotating spindle can stop within a predetermined time, and when it is determined that the rotational speed of the spindle is not less than or equal to the limit rotational speed, executes an output process of outputting a signal for displaying an abnormality.

[0027] In the present disclosure, when the rotational speed of the spindle and the tool upper limit acceleration are acquired, the limit rotational speed is calculated according to the tool upper limit acceleration. It is determined whether the rotational speed of the spindle is less than or equal to the limit rotational speed, and when it is determined that the rotational speed of the spindle is not less than or equal to the limit rotational speed, a signal for displaying an abnormality is output.

[0028] A computer program according to one embodiment of the present disclosure is a computer program that can be executed by a control device that controls a spindle on which a tool is mounted, and causes the control device to perform a determination process to determine whether the rotation speed of the spindle is less than or equal to a limit rotation speed that indicates a rotation speed at which the spindle can be stopped within a predetermined time, when it has obtained the rotation speed of the spindle and the upper limit acceleration of the spindle corresponding to the tool, and if it has determined that the rotation speed of the spindle is not less than or equal to the limit rotation speed, it performs an output process to output a signal indicating an abnormality.

[0029] In this disclosure, when the spindle speed and the tool's upper limit acceleration are obtained, the limit speed is calculated according to the tool's upper limit acceleration. It is determined whether the spindle speed is below the limit speed, and if it is determined that the spindle speed is not below the limit speed, a signal indicating an abnormality is output. [Effects of the Invention]

[0030] In a control device, machine tool, control method, and computer program according to one embodiment of this disclosure, an abnormality is displayed if it is determined that the tool's upper limit rotational speed is not below the limit rotational speed. Therefore, it is possible to achieve both the suppression of acceleration and the safe stopping of the spindle during operation within a predetermined time in which the power supplied to the control device can be maintained. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic perspective view of a machine tool according to Embodiment 1. [Figure 2] This is a block diagram illustrating the configuration of the control device. [Figure 3] This is an example of a table storing tool number, tool maximum rotational speed, tool maximum angular acceleration, and a flag indicating that the tool number has been exceeded, as well as an example of an input screen for the tool number, tool maximum rotational speed, and tool maximum angular acceleration displayed on the display unit. [Figure 4] This graph shows the relationship between the upper limit angular acceleration of the tool and the limit rotational speed. [Figure 5]This is a front view of the display unit that shows error information. [Figure 6] This figure shows the table after changing the maximum tool rotation speed, and an example of the input screen. [Figure 7] This is a flowchart illustrating the editing process for compiling information about tools. [Figure 8] This is a flowchart explaining the process of changing the rotation speed when overriding. [Figure 9] This is a flowchart illustrating the rotational speed determination process when executing the machining program according to Embodiment 2. [Modes for carrying out the invention]

[0032] (Embodiment 1) The present invention will be described below based on the drawings showing a machine tool according to Embodiment 1. In the following description, the directions up, down, front, back, left, and right in the figures will be used. Up, down, front, back, left, and right in the figures are examples of direction indications, and the direction indications are not limited to these. Figure 1 is a schematic perspective view of a machine tool. Note that the tool magazine for storing replacement tools is not shown in Figure 1.

[0033] The machine tool has a rectangular base 1 that extends front to back. A support device 3 for supporting the workpiece is provided on the front side of the upper part of the base 1. The support device 3 comprises a base 3a, an A-axis motor 3b, a C-axis motor 3c, and two support plates 3d. The two support plates 3d are positioned on the left and right sides of the base 1. Base 3a is positioned between the two support plates 3d and is connected to the support plates 3d so as to be rotatable around the A-axis. The A-axis extends in the left-right direction. Driven by the A-axis motor 3b, base 3a rotates around the A-axis.

[0034] The base 3a has a support surface 3e that supports the workpiece, and the C-axis motor 3c is located below the base 3a in Figure 1. The support surface 3e is parallel to the A-axis. The C-axis extends in a direction perpendicular to the support surface 3e. The support surface 3e rotates around the C-axis when driven by the C-axis motor 3c.

[0035] A support base 2 is provided on the rear side of the upper part of the base 1. A Y-axis movement mechanism 10 is provided on the upper part of the support base 2. The Y-axis movement mechanism 10 comprises two tracks 11 extending in the front and rear directions, a Y-axis screw shaft 12, a Y-axis motor 13, and a bearing 14.

[0036] Tracks 11 are provided on the left and right sides of the upper part of the support base 2. The Y-axis screw shaft 12 extends front to back and is provided between the two tracks 11. Bearings 14 are provided at the front end and in the middle of the Y-axis screw shaft 12. The bearing in the middle is not shown in the diagram. The Y-axis motor 13 is connected to the rear end of the Y-axis screw shaft 12.

[0037] A nut (not shown) is screwed onto the Y-axis screw shaft 12. Multiple sliders 15 are slidably mounted on each track 11. A movable plate 16 is connected to the top of the nut and sliders 15. The movable plate 16 extends horizontally. The rotation of the Y-axis motor 13 causes the Y-axis screw shaft 12 to rotate, the nut to move in the front-back direction, and the movable plate 16 to move in the front-back direction.

[0038] An X-axis movement mechanism 20 is provided on the upper surface of the movable plate 16. The X-axis movement mechanism 20 comprises two tracks 21 extending to the left and right, an X-axis screw shaft 22, and an X-axis motor 23 (see Figure 2).

[0039] Tracks 21 are provided on the front and rear of the upper surface of the movable plate 16. The X-axis screw shaft 22 extends to the left and right and is provided between the two tracks 21. The left end and the middle section of the X-axis screw shaft 22 are supported by bearings 24. The bearings 24 are fixed to the movable plate 16.

[0040] A nut (not shown) is connected to the X-axis screw shaft 22. Multiple sliders 26 are slidably mounted on each track 21. A vertical column 4 is connected to the upper part of the nut and sliders 26. The vertical column 4 is columnar in shape. The rotation of the X-axis motor 23 (see Figure 2) rotates the X-axis screw shaft 22, causing the nut to move left and right, and the vertical column 4 to move left and right.

[0041] A Z-axis movement mechanism 30 is provided on the front of the vertical column 4. The Z-axis movement mechanism 30 comprises two vertically extending tracks 31, a Z-axis screw shaft 32, a Z-axis motor 33, and a bearing 34.

[0042] Tracks 31 are provided on the left and right sides of the front of the vertical column 4. The Z-axis screw shaft 32 extends vertically and is located between the two tracks 31. Bearings 34 are provided at the lower end and in the middle of the Z-axis screw shaft 32. The bearing in the middle is not shown in the diagram. The Z-axis motor 33 is connected to the upper end of the Z-axis screw shaft 32.

[0043] A nut (not shown) is screwed onto the Z-axis screw shaft 32. Multiple sliders 35 are slidably mounted on each track 31. The spindle head 5 is connected to the front of the nut and sliders 35. The rotation of the Z-axis motor 33 causes the Z-axis screw shaft 32 to rotate, the nut to move vertically, and the spindle head 5 to move vertically.

[0044] A spindle 5a extending vertically is installed inside the spindle head 5. The spindle 5a rotates around its axis. A spindle motor 6 is installed at the upper end of the spindle head 5. A tool is attached to the lower end of the spindle 5a. The rotation of the spindle motor 6 causes the spindle 5a to rotate, and the tool to rotate as well. The rotated tool processes the workpiece supported by the support device 3.

[0045] The machine tool is equipped with a tool changer (not shown) for changing tools. The tool changer exchanges the tool stored in the tool magazine (not shown) with the tool mounted on the spindle 5a.

[0046] Figure 2 is a block diagram illustrating the configuration of the control device 50. The control device 50 comprises a control unit 51, a main memory unit 52, an auxiliary memory unit 53, and an input / output interface 54. The control unit 51 includes, for example, a processor or logic circuit. The processor includes, for example, a CPU, MPU, or GPU. The logic circuit includes, for example, an FPGA or ASIC. The main memory unit 52 includes RAM. When an operator operates the operation unit 7, a signal is input from the operation unit 7 to the input / output interface 54. The operation unit 7 is, for example, a keyboard, buttons, a touch panel, etc. The operation unit 7 constitutes a reception unit that accepts information input. The input / output interface 54 outputs a signal to the display unit 8. The display unit 8 displays characters, figures, symbols, etc. The display unit 8 is, for example, a liquid crystal display or an organic EL display.

[0047] The auxiliary storage unit 53 includes a rewritable storage device, such as an EEPROM, flash ROM, or hard disk. The auxiliary storage unit 53 stores the control program. The control program is stored in a storage medium 65, such as an optical disc, flash memory, or hard disk, and may be downloaded from the storage medium 65 to the auxiliary storage unit 53. Alternatively, it may be downloaded from an external server to the auxiliary storage unit 53 via a network connected to the machine tool. The control unit 51 reads the control program from the auxiliary storage unit 53 into the main storage unit 52 and controls the drive of each motor. The processing by the control program may be implemented, for example, by an external server or external terminal connected to the control device 50 via a network, or by distributed processing by an external server and devices other than the external server, such as an external terminal and the control device 50, or by a quantum computer.

[0048] The control device 50 includes a spindle control circuit 60 that corresponds to the spindle motor 6. The spindle motor 6 is equipped with an encoder 6a. Based on a command from the control unit 51, the spindle control circuit 60 outputs a command indicating the amount of current to the spindle motor 6. The spindle motor 6 is driven based on this command. The encoder 6a outputs a position feedback signal to the spindle control circuit 60. Based on the position feedback signal, the spindle control circuit 60 performs feedback control.

[0049] The control device 50 includes a Y-axis control circuit 56 that corresponds to the Y-axis motor 13. The Y-axis motor 13 is equipped with an encoder 13a. Based on a command from the control unit 51, the Y-axis control circuit 56 outputs a command indicating the amount of current to the Y-axis motor 13. The Y-axis motor 13 is driven based on this command. The encoder 13a outputs a position feedback signal to the Y-axis control circuit 56. Based on the position feedback signal, the Y-axis control circuit 56 performs feedback control.

[0050] The control device 50 includes an X-axis control circuit 55 that corresponds to the X-axis motor 23. The X-axis motor 23 is equipped with an encoder 23a. The X-axis control circuit 55, X-axis motor 23, and encoder 23a are the same as those for the Y-axis, so their explanation is omitted.

[0051] The control device 50 includes a Z-axis control circuit 57 that corresponds to the Z-axis motor 33. The Z-axis motor 33 is equipped with an encoder 33a. The Z-axis control circuit 57, Z-axis motor 33, and encoder 33a are the same as those for the Y-axis, so their explanation will be omitted. The control device 50 controls the rotational speed and vertical, horizontal, forward, backward, and left-right position of the spindle 5a, that is, it controls the spindle 5a.

[0052] The control device 50 includes an A-axis control circuit 58 corresponding to the A-axis motor 3b. The A-axis motor 3b is equipped with an encoder 3ba. The A-axis control circuit 58, A-axis motor 3b, and encoder 3ba are the same as those for the Y-axis, and their description is omitted.

[0053] The control device 50 includes a C-axis control circuit 59 that corresponds to the C-axis motor 3c. The C-axis motor 3c is equipped with an encoder 3ca. The C-axis control circuit 59, C-axis motor 3c, and encoder 3ca are the same as those for the Y-axis, so their description is omitted. The control device 50 also performs the same feedback control on the spindle motor 6 as on the Y-axis motor 13.

[0054] Figure 3 shows a table storing the tool number, tool maximum rotational speed, tool maximum angular acceleration, and a flag indicating that the maximum rotational speed has been exceeded, and an example of the input screen for the tool number, tool maximum rotational speed, and tool maximum angular acceleration displayed on the display unit 8. The upper part of Figure 3 shows the table, and the lower part shows the input screen. The auxiliary storage unit 53 stores table T. Table T includes a column (field) Ta for storing the tool number, a column Tb for storing the tool maximum rotational speed, a column Tc for storing the tool maximum angular acceleration, and a column Td for storing the flag indicating that the maximum rotational speed has been exceeded. The tool number is a number that identifies the tool to be mounted on the spindle 5a. The tool number column Ta stores, for example, a number. The tool maximum rotational speed is the upper limit of the rotational speed of the spindle 5a. The operator operates the operation unit 7 and inputs the tool maximum rotational speed for each tool number. The tool maximum angular acceleration is the upper limit of the angular acceleration of the spindle 5a, and indicates the upper limit of the magnitude of the angular acceleration used when accelerating or decelerating the spindle 5a. The tool maximum angular acceleration constitutes the upper limit acceleration. The operator operates the control unit 7 to input the tool's upper limit angular acceleration for each tool number. The control unit 51 stores 0 in the column Td of the upper limit rotation speed exceeding flag for each tool number if the tool's upper limit rotation speed corresponding to the tool's upper limit angular acceleration is less than or equal to the limit rotation speed described later, and stores 1 in the column Td of the tool's upper limit rotation speed exceeding flag if the tool's upper limit rotation speed corresponding to the tool's upper limit angular acceleration is not less than or equal to the limit rotation speed described later.

[0055] The machine tool is equipped with a power storage unit, such as a capacitor, which is different from the normal power supply. If the power supply from the power source is interrupted, for example in the event of a blackout, the machine tool can be driven for a predetermined time, i.e., a power holding time, using power supplied from the power storage unit. In this embodiment, the power holding time is also the time required for the spindle 5a, which is currently in operation, to stop. The length of the power holding time increases as the capacity of the power storage unit increases.

[0056] Figure 4 is a graph showing the relationship between the tool's upper limit angular acceleration and the rotational speed limit. The rotational speed limit is a rotational speed determined according to the tool's upper limit angular acceleration, and is the rotational speed at which the spindle 5a can be stopped within the power holding time when the spindle 5a is decelerated by the tool's upper limit angular acceleration. As shown in Figure 4, the relationship between the tool's upper limit angular acceleration and the rotational speed limit is linear. The rotational speed limit can be expressed, for example, by the following equation (1). Limited rotation speed [min -1 ] = Power holding time [s] × (60 / 2π) × Upper limit angular acceleration [rad / s 2 ]··(1) For example, the limit rotational speed for the tool's upper limit angular acceleration a1 is A1. That is, when the tool's upper limit angular acceleration a1 is set, if the rotational speed of the spindle 5a is less than or equal to the limit rotational speed A1, i.e., if the spindle 5a rotates at a rotational speed less than or equal to the limit rotational speed A1, the spindle 5a will stop within the power holding time by decelerating it with the tool's upper limit angular acceleration a1. Equation (1) is stored in the auxiliary storage unit 53 or the main storage unit 52.

[0057] For example, when editing information about a tool, the operator operates the control unit 7. Based on this operation, the control unit 51 reads table T from the auxiliary storage unit 53. As shown in the lower part of Figure 3, the display unit 8 displays the input screen 8a. In the initial state, no information is stored in each field of the read table T. The operator operates the control unit 7 and enters the tool number on the input screen 8a. Note that the tool number may already be stored in the column Ta of the read tool number.

[0058] The operator operates the control unit 7 and inputs tool numbers 1, 2, ..., n (where n is a natural number, and the same applies hereafter). As shown in the upper part of Figure 3, 1, 2, ..., n are stored in the tool number column Ta. The operator operates the control unit 7 and inputs r1, r2, ..., rn as the tool upper limit rotational speeds corresponding to tool numbers 1, 2, ..., n. r1, r2, ..., rn are stored in the tool upper limit rotational speed column Tb. The operator operates the control unit 7 and inputs a1, a2, ..., an as the tool upper limit angular accelerations corresponding to tool numbers 1, 2, ..., n.

[0059] The control unit 51 applies the input tool upper limit angular acceleration to equation (1) for each tool number to calculate the limit rotation speed. The control unit 51 determines for each tool number whether the input tool upper limit rotation speed is less than or equal to the limit rotation speed. If the tool upper limit rotation speed is less than or equal to the limit rotation speed, it stores 0 in the field of column Td of the upper limit rotation speed exceedance flag corresponding to the tool number. In other words, the operator sets a tool upper limit rotation speed that is less than or equal to the limit rotation speed for the tool.

[0060] The control unit 51 also stores the tool's maximum rotational speed corresponding to the tool number for which the field of column Td contains a value of 0 in the auxiliary storage unit 53. If the tool's maximum rotational speed is not less than or equal to the limit rotational speed, that is, if the tool's maximum rotational speed is greater than the limit rotational speed, the control unit 51 stores a value of 1 in the field of column Td of the maximum rotational speed exceedance flag corresponding to the tool number. In other words, the operator sets a tool's maximum rotational speed greater than the limit rotational speed for the tool.

[0061] For example, if the upper limit rotational speed r1 of the tool is not less than or equal to the limit rotational speed A1 corresponding to the upper limit angular acceleration a1 of the tool, the control unit 51 stores 1 in the field of the upper limit rotational speed exceedance flag corresponding to tool number 1, as shown in the upper part of Figure 3. If the upper limit rotational speed r2 of the tool is less than or equal to the limit rotational speed corresponding to the upper limit angular acceleration a2 of the tool, the control unit 51 stores 0 in the field of the upper limit rotational speed exceedance flag corresponding to tool number 2, as shown in the upper part of Figure 3.

[0062] When an operator operates the control unit 7 and inputs an instruction to finish editing the tool information, the control unit 51 determines whether the field for the upper limit rotation speed exceeding flag is set to 1. If the field for the upper limit rotation speed exceeding flag is set to 1, the control unit 51 displays error information on the display unit 8 indicating that the entered tool upper limit rotation speed is an abnormal value, i.e., that the entered tool upper limit rotation speed is greater than the limit rotation speed. The error information includes the tool number for which the upper limit rotation speed exceeding flag is 1, and the limit rotation speed corresponding to the tool upper limit angular acceleration of the tool number for which the upper limit rotation speed exceeding flag is 1.

[0063] Figure 5 is a front view of the display unit 8 that displays error information 8b. For example, as shown in Figure 3, when the field for the upper limit rotation speed exceeding flag in the record for tool number 1 stores 1, the control unit 51 displays the error information 8b on the display unit 8, as shown in Figure 5. The error information 8b includes, for example, "Tool upper limit rotation speed error", "Tool number 1", and "Limited rotation speed A1".

[0064] Figure 6 shows an example of table T after the tool maximum rotation speed has been changed, and an example of the input screen 8a. If error information 8b is displayed, the operator can change the tool maximum rotation speed for the tool number indicated by the error information 8b. For example, as shown in the lower part of Figure 6, the operator operates the operation unit 7 and changes the tool maximum rotation speed from r1 to r1' on the input screen 8a. The control unit 51 changes the tool maximum rotation speed r1 to r1' in table T. Note that r1' is a rotation speed less than or equal to A1. The control unit 51 changes the maximum rotation speed exceeding flag in the record for tool number 1 to 0 due to the change to r1'.

[0065] When the operator operates the control unit 7 and inputs an instruction to finish editing the tool information, the control unit 51 determines whether the field for the upper limit rotation speed exceeding flag contains 1. If the field for the upper limit rotation speed exceeding flag does not contain 1, the control unit 51 stores the edited table T in the auxiliary storage unit 53. Note that each upper limit rotation speed exceeding flag stored in column Td does not need to be stored in the auxiliary storage unit 53.

[0066] Furthermore, when editing tool-related information after storing table T in the auxiliary storage unit 53, the table T read from the auxiliary storage unit 53 to the main storage unit 52 may be table T in which information is stored in the fields. When changing the value of a field in which information is stored, the value is changed by overwriting. Also, in the initial state, information may be stored in each field of the read table T. In this case as well, when changing the value of a field in which information is stored, the value is changed by overwriting.

[0067] Figure 7 is a flowchart illustrating the editing process for editing tool information. The control unit 51 determines whether or not the editing mode has been selected (S1). The editing mode is a mode for editing tool information for machining operations that have not yet been performed.

[0068] For example, if the machine tool is not currently performing a machining operation, the operator operates the control unit 7 to select an edit mode for the machining operation to be performed next, or for a second machining operation to be performed after the first machining operation while the machine tool is performing the first machining operation. If no edit mode is selected (S1:NO), the control unit 51 returns to step S1.

[0069] If editing mode is selected (S1:YES), the control unit 51 reads table T from the auxiliary storage unit 53 (S2). At this time, the control unit 51 displays an input screen 8a on the display unit 8 for entering values ​​into the fields of table T. For example, the operator can operate the operation unit 7 while looking at the input screen 8a to input the tool's upper limit rotational speed and the tool's upper limit angular acceleration.

[0070] The control unit 51 determines whether the input of the tool's upper limit rotational speed and tool's upper limit angular acceleration has been completed (S3). In step S3 of Figure 7, the tool's upper limit rotational speed is simply displayed as rotational speed, and the tool's upper limit angular acceleration is simply displayed as angular acceleration. For example, when the operator has completed inputting the tool's upper limit rotational speed and tool's upper limit angular acceleration for all tools, they can operate the operation unit 7 to input information indicating that the input of the tool's upper limit rotational speed and tool's upper limit angular acceleration has been completed.

[0071] For example, the operator can input information indicating that the input of the tool's maximum rotational speed and tool's maximum angular acceleration has been completed by operating a completion button displayed on a keyboard, switch, or touch panel. If information indicating that the input of the tool's maximum rotational speed and tool's maximum angular acceleration has been completed is input, the control unit 51 determines that the input of the tool's maximum rotational speed and tool's maximum angular acceleration has been completed. If it determines that the input of the tool's maximum rotational speed and tool's maximum angular acceleration has not been completed (S3:NO), the control unit 51 returns to step S3.

[0072] If the control unit 51 determines that the input of the tool upper limit rotation speed and tool upper limit angular acceleration has been completed (S3: YES), the control unit 51 applies the input tool upper limit angular acceleration to equation (1) for each tool number and calculates the limit rotation speed (S4). The control unit 51 determines for all tools whether the input tool upper limit rotation speed is less than or equal to the limit rotation speed (S5). For example, if the control unit 51 has 1 entered in at least one field of the column Td of the upper limit rotation speed exceeding flag (see Figure 3, top), it determines that the input tool upper limit rotation speed is not less than or equal to the limit rotation speed. If the control unit 51 has 0 entered in all fields of the column Td of the upper limit rotation speed exceeding flag (see Figure 6, top), it determines that the input tool upper limit rotation speed is less than or equal to the limit rotation speed.

[0073] If it is determined that the entered tool maximum rotation speed is less than or equal to the limit rotation speed for all tools (S5: YES), the editing process is terminated. In step S5 of Figure 7, the entered tool maximum rotation speed is displayed as the input rotation speed. If it is determined that the entered tool maximum rotation speed is not less than or equal to the limit rotation speed for all tools (S5: NO), that is, if it is determined that the entered tool maximum rotation speed is greater than the limit rotation speed for at least one tool, the control unit 51 outputs a signal to the display unit 8 to display error information 8b (S6). The display unit 8 receives the signal and displays the error information 8b.

[0074] The operator can see the error information 8b and change the tool's upper limit rotation speed, which is higher than the limit rotation speed. The control unit 51 determines whether the change to the limit rotation speed has been completed (S7). For example, the operator can change the tool's upper limit rotation speed, which is higher than the limit rotation speed, to a tool upper limit rotation speed that is less than or equal to the limit rotation speed. For example, the operator can operate the complete button displayed on the keyboard, switch, or touch panel to input information indicating that the change to the tool's upper limit rotation speed, i.e., the input of the tool's upper limit rotation speed, has been completed. If information indicating that the input of the tool's upper limit rotation speed has been completed is input, the control unit 51 determines that the change to the tool's upper limit rotation speed has been completed.

[0075] If it is determined that the change in the rotational speed limit has not been completed (S7: NO), the control unit 51 returns to step S6. If it is determined that the change in the rotational speed limit has been completed (S7: YES), the control unit 51 determines for all tools whether the input tool upper limit rotational speed is less than or equal to the rotational speed limit (S8).

[0076] If it is determined that the input tool maximum rotation speed is less than or equal to the limit rotation speed for all tools (S8:YES), a signal to terminate the display of error information 8b is output to the display unit 8 (S9), and the editing process is terminated. The display unit 8 terminates the display of error information 8b. If it is determined that the input tool maximum rotation speed is not less than or equal to the limit rotation speed for all tools (S8:NO), that is, if it is determined that the input tool maximum rotation speed is greater than the limit rotation speed for at least one tool, the control unit 51 returns to step S6.

[0077] Note that the column Td for the upper limit rotation speed exceeding flag is optional. In this case, in steps S5 and S9, the control unit 51 compares the entered tool upper limit rotation speed with the limit rotation speed for each tool number and determines whether the entered tool upper limit rotation speed is less than or equal to the limit rotation speed for all tools.

[0078] Figure 8 is a flowchart illustrating the rotational speed change process during override. When a machine tool is performing a machining operation, the current rotational speed or current travel speed of the spindle 5a during the machining operation can be changed. Changing the current rotational speed or current travel speed of the spindle 5a during a machining operation is called override. For example, the operator operates the control unit 7 and inputs a command to change the current rotational speed or current travel speed of the spindle 5a during the machining operation. Note that the tool upper limit angular acceleration and tool upper limit rotational speed are set for each tool. The spindle 5a is equipped with a tool whose tool upper limit rotational speed is less than or equal to the limit rotational speed. That is, the control unit 51 executes the rotational speed change process shown in Figure 8 for each tool after determining that the tool upper limit rotational speed is less than or equal to the limit rotational speed.

[0079] The control unit 51 determines whether the spindle 5a is currently performing a machining operation (S11). If the spindle 5a is not currently performing a machining operation (S11: NO), the process ends. If the spindle 5a is currently performing a machining operation, i.e., if the spindle 5a is rotating at a predetermined current rotational speed (S11: YES), the control unit 51 determines whether it has received a command from the operation unit 7 to change the current rotational speed of the spindle 5a (change command) (S12). The command to change the current rotational speed of the spindle 5a includes the changed rotational speed. If the command to change the current rotational speed of the spindle 5a has not been received (S12: NO), the control unit 51 ends the process.

[0080] If a command to change the current rotational speed of the spindle 5a is received (S12: YES), the control unit 51 determines whether the changed rotational speed is less than or equal to the limit rotational speed of the tool mounted on the spindle 5a (S13). As mentioned above, the limit rotational speed is determined based on the upper limit angular acceleration of the tool set for the tool mounted on the spindle 5a.

[0081] If it is determined that the changed rotation speed is not less than or equal to the limit rotation speed (S13: NO), the control unit 51 rotates the spindle 5a at the limit rotation speed (S14) and terminates the process. If it is determined that the changed rotation speed is less than or equal to the limit rotation speed of the tool mounted on the spindle 5a (S13: YES), the control unit 51 rotates the spindle 5a at the changed rotation speed (S15) and terminates the process.

[0082] In the machine tool according to Embodiment 1, if it is determined that the tool's upper limit rotational speed is not below the limit rotational speed, error information 8b, i.e., an abnormality, is displayed. If it is determined that the tool's upper limit rotational speed is below the limit rotational speed, the tool's upper limit rotational speed is set. Therefore, it is possible to achieve both acceleration suppression and safe stopping of the spindle while it is in motion within the power holding time.

[0083] Furthermore, if it is determined that the tool's maximum rotational speed is not below the limit rotational speed, error information 8b is displayed, which in turn displays the limit rotational speed and notifies the operator. The operator can then check the limit rotational speed and set the tool's maximum rotational speed to be below the limit rotational speed.

[0084] Furthermore, when overriding, if the modified spindle speed 5a is less than or equal to the maximum rotational speed of the tool attached to spindle 5a, spindle 5a will rotate at the modified speed. If the modified speed is not less than or equal to the maximum rotational speed of the tool attached to spindle 5a, spindle 5a will rotate at the maximum rotational speed. The process in step S4 corresponds to calculation processing. The processes in S5 and S8 correspond to judgment processing, and the process in S6 corresponds to output processing. The process in S12 corresponds to change judgment processing, the process in S13 corresponds to rotation speed judgment processing, the process in S15 corresponds to rotation speed change processing, and the process in S14 corresponds to limit rotation speed change processing.

[0085] (Embodiment 2) The present invention will be described below based on drawings showing a machine tool according to Embodiment 2. In the configuration of Embodiment 2, components similar to those in Embodiment 1 are denoted by the same reference numerals, and their detailed descriptions are omitted. The operator can select a machining program execution mode. Figure 9 is a flowchart illustrating the rotational speed determination process when executing a machining program. The machining program execution mode is a program that performs machining on a workpiece based on a machining program stored in the auxiliary storage unit 53. The machining program includes tool upper limit angular acceleration and tool upper limit rotational speed corresponding to each tool (each tool number). No process is performed to determine whether the tool upper limit rotational speed provided in the machining program is below the limit rotational speed.

[0086] The control unit 51 determines whether or not the machining program execution mode has been selected (S21). If it determines that the machining program execution mode has not been selected (S21: NO), the control unit 51 terminates the process. If it determines that the machining program execution mode has been selected (S21: YES), the control unit 51 reads commands from the machining program (S22). The machining program has multiple commands. The control unit 51 reads the multiple commands in order.

[0087] The control unit 51 determines whether the read command is a spindle rotation command to rotate the spindle (S23). Note that a spindle rotation command includes the number of rotations used to rotate the spindle 5a, i.e., the commanded rotation speed. If it is determined that it is not a spindle rotation command (S23: NO), the control unit 51 determines whether the read command is a termination command (S29). If it is determined that the read command is not a termination command (S29: NO), the control unit 51 executes the read command (S30) and returns to step S22. If it is determined that the read command is a termination command (S29: YES), the control unit 51 terminates the process.

[0088] In step S23, if it is determined that the command is to rotate the spindle (S23:YES), the control unit 51 applies the tool's upper limit angular acceleration to equation (1) for each tool number and calculates the limit rotation speed (S24). The process in step S24 constitutes the calculation process. The control unit 51 determines whether the tool's upper limit rotation speed corresponding to the tool currently mounted on the spindle 5a is less than or equal to the limit rotation speed (S25). If it is determined that the tool's upper limit rotation speed is not less than or equal to the limit rotation speed (S25:NO), the control unit 51 outputs a signal to the display unit 8 to display the first error information (S31). The first error information is the same as the error information 8b. The control unit 51 outputs signals to the spindle control circuit 60, X~Z axis control circuits 55~57, A axis control circuit 58, C axis control circuit 59, etc., to stop the operation of the components for moving the tool and workpiece, i.e., the spindle 5a, support device 3, X~Z axis movement mechanisms 10~30, etc. (S28), and terminates the process.

[0089] If the control unit 51 determines that the tool's upper limit rotational speed corresponding to the tool mounted on the spindle 5a is less than or equal to the limit rotational speed (S25: YES), it determines whether the commanded rotational speed is less than or equal to the tool's upper limit rotational speed corresponding to the tool mounted on the spindle 5a (S26). If it determines that the commanded rotational speed is less than or equal to the tool's upper limit rotational speed (S26: YES), the control unit 51 rotates the spindle 5a at the commanded rotational speed (S32) and returns to step S22.

[0090] If the control unit 51 determines that the commanded rotation speed is not less than or equal to the tool's upper limit rotation speed (S26: NO), it outputs a signal to the display unit 8 to display second error information (S27). The second error information is, for example, that the commanded rotation speed is greater than the tool's upper limit rotation speed. The display unit 8 displays that the commanded rotation speed is greater than the tool's upper limit rotation speed.

[0091] The control unit 51 outputs signals to the spindle control circuit 60, X-Z axis control circuits 55-57, A axis control circuit 58, C axis control circuit 59, etc., to stop the operation of the components for moving the tool and workpiece, namely the spindle 5a, support device 3, X-Z axis movement mechanisms 10-30, etc. (S28), and terminates processing.

[0092] Furthermore, in step S32, if the operator overrides the rotation speed of the spindle 5a during machining, i.e., the commanded rotation speed, the control unit executes the rotation speed change process shown in Figure 8. The process in S24 corresponds to the calculation process. The process in S25 corresponds to the determination process. The process in S26 corresponds to the second determination process. The processes in S27 and S31 correspond to the output process. The process in S28 corresponds to the signal output process. The process in S31 corresponds to the display signal output process.

[0093] In the machine tool according to Embodiment 2, the tool's upper limit rotational speed and tool's upper limit angular acceleration are obtained from the program for machining the workpiece, and if it is determined that the tool's upper limit rotational speed is not below the limit rotational speed, an abnormality is displayed and the spindle is stopped. In each of the embodiments described above, the angular acceleration (rad / s) is used as the acceleration of the spindle 5a. 2 ) is used, but distance acceleration (m / s 2 You may use ).

[0094] In Embodiment 2, the commanded rotational speed is input from the spindle rotation command, i.e., the command in the machining program, but the method of inputting the commanded rotational speed is not limited to this. For example, the operator may operate the control unit 7 and input the spindle rotation command along with the commanded rotational speed, or the operator may input a command to change the commanded rotational speed.

[0095] The embodiments disclosed herein should be considered illustrative and not restrictive in all respects. The scope of the present invention is intended to include all modifications within the claims and equivalents thereof. The matters described in each embodiment can be combined with one another. Furthermore, the independent and dependent claims described in the claims can be combined with one another in any combination, regardless of the form of reference. In addition, the claims use a multi-claim format in which claims refer to two or more other claims (multi-claim format), but are not limited thereto. They may also be described using a multi-claim format in which at least one multi-claim refers to another multi-claim (multi-multi-claim format). [Explanation of Symbols]

[0096] 5a main shaft 6. Main shaft motor 7. Operation Unit (Reception Unit) 8 Display 50 Control device 51 Control Unit 52 Main memory 53 Auxiliary storage section

Claims

1. In a control device that controls the spindle on which a tool is mounted, When the rotational speed of the spindle and the tool upper limit acceleration, which indicates the upper limit of the acceleration of the spindle corresponding to the tool, are obtained, a calculation process is performed to calculate a limit rotational speed, which is the rotational speed at which the spindle, while rotating, can be stopped within a predetermined time according to the tool upper limit acceleration, and a determination process is performed to determine whether the rotational speed of the spindle is less than or equal to the calculated limit rotational speed. If it is determined that the rotational speed of the spindle is not below the limit rotational speed, the system performs an output process that outputs a signal indicating an abnormality. Control device.

2. Equipped with a memory device, The aforementioned tool upper acceleration limit is set for each tool. The memory device stores a plurality of tool upper limit acceleration values ​​set for each tool, The calculation process involves obtaining the tool's upper limit acceleration from the storage device and calculating the limit rotational speed according to the tool's upper limit acceleration. The control device according to claim 1.

3. Equipped with a memory device, The upper limit of the spindle rotation speed, which is the tool rotation speed limit, is set for each tool. The storage device stores a plurality of tool upper limit rotation speeds set for each tool, The determination process determines whether the upper limit rotational speed of each tool stored in the storage device is less than or equal to the limit rotational speed calculated in the calculation process, The output process outputs a signal indicating an abnormality if the determination process determines that the tool's upper limit rotational speed is not less than or equal to the limit rotational speed. The control device according to claim 1.

4. The command rotation speed for executing the rotation command of the aforementioned spindle is obtained, If the determination process determines that the upper limit rotational speed of the tool is less than or equal to the limit rotational speed, a second determination process is executed to determine whether the command rotational speed is less than or equal to the upper limit rotational speed of the tool. The output process outputs a signal indicating an abnormality if the second determination process determines that the commanded rotation speed is not less than or equal to the upper limit rotation speed of the tool. The control device according to claim 3.

5. The system acquires the tool's upper limit rotational speed and the tool's upper limit acceleration from the input receiving unit and stores them in the storage device. The control device according to claim 3.

6. When the spindle, which is equipped with a tool whose upper limit rotational speed is less than or equal to the limit rotational speed, is performing rotational processing at a predetermined rotational speed, a change determination process is performed to determine whether or not a change command to change the rotational speed has been received. If it is determined that the aforementioned change command has been received, a rotation speed determination process is performed to determine whether the rotation speed after the change is less than or equal to the aforementioned limit rotation speed, If the changed rotation speed is less than or equal to the aforementioned limit rotation speed, a rotation speed change process is performed to rotate the spindle at the changed rotation speed. If the changed rotation speed is not less than or equal to the aforementioned limit rotation speed, the spindle rotation speed change process is executed to rotate the spindle at the aforementioned limit rotation speed. The control device according to claim 3.

7. When a command to rotate the spindle is read from a program for machining a workpiece and executed, the program obtains the upper limit rotational speed of the tool mounted on the spindle and the upper limit acceleration of the tool mounted on the spindle, If it is determined that the tool's upper limit rotational speed is not less than or equal to the limit rotational speed, a signal output process is executed to output a signal to stop the spindle. The control device according to claim 3.

8. If it is determined that the tool's upper limit rotation speed is not less than or equal to the limit rotation speed, a display signal output process is executed that outputs a signal indicating the tool's upper limit rotation speed. The control device according to claim 3.

9. In a machine tool comprising a spindle on which a tool is mounted and a control device for controlling the spindle, The control device is When the rotational speed of the spindle and the tool upper limit acceleration, which indicates the upper limit of the acceleration of the spindle corresponding to the tool, are obtained, a determination process is performed to determine whether the rotational speed of the spindle is determined according to the tool upper limit acceleration and is less than or equal to a limit rotational speed that indicates the rotational speed at which the spindle can be stopped within a predetermined time. If it is determined that the rotational speed of the spindle is not below the limit rotational speed, the system performs an output process that outputs a signal indicating an abnormality. Machine tools.

10. In a control method for controlling the spindle on which a tool is mounted, When the rotational speed of the spindle and the tool upper limit acceleration, which indicates the upper limit of the acceleration of the spindle corresponding to the tool, are obtained, a determination process is performed to determine whether the rotational speed of the spindle is determined according to the tool upper limit acceleration and is less than or equal to a limit rotational speed that indicates the rotational speed at which the spindle can be stopped within a predetermined time. If it is determined that the rotational speed of the spindle is not below the limit rotational speed, the system performs an output process that outputs a signal indicating an abnormality. Control method.

11. In a computer program executable by a control device that controls the spindle on which a tool is mounted, The control device, When the rotational speed of the spindle and the tool upper limit acceleration, which indicates the upper limit of the acceleration of the spindle corresponding to the tool, are obtained, a determination process is performed to determine whether the rotational speed of the spindle is determined according to the tool upper limit acceleration and is less than or equal to a limit rotational speed that indicates the rotational speed at which the spindle can be stopped within a predetermined time. If it is determined that the rotational speed of the spindle is not below the limit rotational speed, an output process is performed to output a signal indicating an abnormality. A computer program that executes an action.

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