Machine tool, tool replacement method for machine tool, and computer program

Abstract

Provided is a machine tool that makes it possible to safely perform tool replacement, even when a non-rotary tool has been installed on a principal shaft and an absolute position for the principal shaft has not been established. A machine tool according to the present invention comprises a principal shaft, a principal shaft head, a principal shaft motor, a tool replacement device, and a control device that performs control such that a rotation operation of the principal shaft motor that is for establishing an absolute position for the principal shaft is performed before execution of a tool replacement operation. The control device has a tool determination unit that determines whether a tool that is installed on the principal shaft is a non-rotary tool, an absolute position determination unit that determines whether the principal shaft has established the absolute position, and a tool replacement operation execution unit that executes the tool replacement operation. When it has been determined that a non-rotary tool is installed on the principal shaft and it has also been determined that the principal shaft has not established the absolute position, the tool replacement operation is begun without execution of the rotation operation of the principal shaft motor that is for establishing the absolute position of the principal shaft, the non-rotary tool is removed from the principal shaft, and the rotation operation of the principal shaft motor that is for establishing the absolute position is executed without another tool having been installed on the principal shaft.

Description

Machine tool, tool changing method for machine tool, and computer program

[0001] The present disclosure relates to a machine tool, a tool changing method for a machine tool, and a computer program.

[0002] Tools attached to the spindle of a machine tool include rotating tools that perform cutting processes on a workpiece by rotating, and non-rotating tools that perform turning processes on a workpiece by rotating the workpiece without rotating the tool itself. Non-rotating tools are attached to the spindle head in a state where they are mechanically prevented from rotating.

[0003] When changing tools in a machine tool, an indexing operation is performed to determine the specific phase of the spindle for properly transferring the tool based on the absolute position of the spindle. The absolute position of the spindle is detected by an encoder attached to the spindle motor. If the encoder is an incremental type, when changing tools after powering on, it is necessary to rotate the spindle to perform an absolute position recovery operation and then perform an indexing operation in order to establish the absolute position of the spindle. In this case, if a non-rotating tool is attached to the spindle, the spindle cannot rotate, and therefore the absolute position recovery operation and indexing operation cannot be performed.

[0004] Conventionally, there has been known a machine tool that has a means for determining whether a tool attached to a spindle is a rotating tool or a non-rotating tool before a tool change, and for prohibiting rotation of the spindle up to a specific position if it is determined to be a non-rotating tool (see, for example, Patent Document 1).

[0005] Patent No. 5994681

[0006] In order to smoothly carry out machining operations on machine tools, it is desirable to establish the absolute position of the spindle and complete the indexing operation when changing tools, as this will minimize the risk of tool change errors such as the tool being dropped.

[0007] An object of the present disclosure is to provide a machine tool, a tool changing method for a machine tool, and a computer program that are capable of safely changing tools even when a non-rotating tool is attached to the spindle and the absolute position of the spindle has not been established.

[0008] One aspect of the present disclosure provides a tool changer including a spindle to which a tool can be attached, a spindle head that rotatably holds the spindle, a spindle motor that rotates the spindle, a tool changer that replaces the tool attached to the spindle with another tool, and a control device that controls the spindle motor to perform a rotational operation to establish an absolute position of the spindle before a tool change operation is performed by the tool changer, the control device including a tool determination unit that determines whether the tool attached to the spindle is a non-rotating tool that does not rotate with the rotation of the spindle, an absolute position determination unit that determines whether the spindle has established the absolute position, and a control device that controls the tool changer to perform a rotational operation to establish an absolute position of the spindle. and a tool change operation executing unit that executes a tool change operation on the spindle by a tool change device, wherein, when the tool determination unit determines that the non-rotating tool is attached to the spindle and the absolute position determination unit determines that the spindle has not established the absolute position, the tool change operation executing unit starts a tool change operation without executing a rotation operation of the spindle motor to establish the absolute position of the spindle, and in a state where the non-rotating tool is removed from the spindle and the other tool is not attached to the spindle.

[0009] One aspect of the present disclosure is a tool changing method for a machine tool, in which, before executing a tool changing operation to replace a tool attached to a spindle rotated by the spindle motor with another tool, the method performs a rotational operation of the spindle motor to establish an absolute position of the spindle, the method determining, before the tool changing, whether the tool attached to the spindle is a non-rotating tool that does not rotate due to the rotation of the spindle, and determining whether the spindle has established the absolute position, and if it is determined that the non-rotating tool is attached to the spindle and the spindle has not established the absolute position, the method starts the tool changing operation without performing the rotational operation of the spindle motor to establish the absolute position of the spindle, and then, with the non-rotating tool removed from the spindle and the other tool not attached to the spindle, performs the rotational operation of the spindle motor to establish the absolute position.

[0010] One aspect of the present disclosure is a computer program causing a computer to execute the following steps: before executing a tool change operation to replace a tool attached to a spindle rotated by a spindle motor with another tool, determining whether the tool attached to the spindle is a non-rotating tool that does not rotate due to the rotation of the spindle; determining whether the spindle has established an absolute position; when it is determined that the non-rotating tool is attached to the spindle and the absolute position of the spindle has not been established, starting the tool change operation without executing a rotational operation of the spindle motor to establish the absolute position of the spindle; and, with the non-rotating tool removed from the spindle and the other tool not attached to the spindle, executing a rotational operation of the spindle motor to establish the absolute position.

[0011] FIG. 5 is a schematic diagram showing a machine tool according to the present embodiment; FIG. 6 is a block diagram showing a control device for the machine tool according to the present embodiment; FIG. 7 is a perspective view showing a state in which a rotating tool is mounted on the spindle of the machine tool according to the present embodiment, as viewed from below; FIG. 8 is a perspective view showing an example of a non-rotating tool; FIG. 9 is a perspective view showing a state in which the non-rotating tool shown in FIG. 4 is mounted on the spindle, as viewed from below; FIG. 10 is a side view showing a state in which the non-rotating tool shown in FIG. 4 has been completely mounted on the spindle; FIG. 11 is a perspective view showing a state in which another non-rotating tool is mounted on the spindle of the machine tool according to the present embodiment, as viewed from above; FIG. 12 is a perspective view showing a state in which a further another non-rotating tool is mounted on the spindle of the machine tool according to the present embodiment; 10 is a flowchart illustrating a second example of a tool changing operation by the machine tool according to the embodiment. FIG. 11 is a diagram illustrating a start position of an absolute position restoration operation by the second example of a tool changing operation by the machine tool according to the embodiment.

[0012] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Fig. 1 is a schematic side view of a machine tool 100. The machine tool 100 includes a lifting mechanism 2, a spindle head 3, and a tool changer 4 arranged above a workpiece table 1 on which a workpiece (not shown) to be machined is placed.

[0013] The lifting mechanism 2 has a feed shaft 21 and a feed shaft motor 22. The feed shaft 21 is, for example, a ball screw, and is arranged along the vertical direction (the up-and-down direction in FIG. 1 ). The vertical direction, which is the length direction of the feed shaft 21, is the Z-axis direction of the machine tool 100. The Z-axis direction is the direction in which the feed shaft 21 approaches and moves away from a workpiece (not shown) placed on the mounting table 1. The feed shaft motor 22 is connected to the upper end of the feed shaft 21. The feed shaft 21 rotates in forward and reverse directions as the feed shaft motor 22 rotates in forward and reverse directions.

[0014] The spindle head 3 is threadedly engaged with the feed shaft 21 via a nut 31. When the feed shaft 21 rotates forward or backward, the nut 31 moves up and down along the feed shaft 21. This causes the spindle head 3, which is integrated with the nut 31, to move up and down in the Z-axis direction. However, the Z-axis direction is not limited to the vertical direction. The Z-axis direction may be a direction intersecting the vertical direction, for example, a horizontal direction, or may be an oblique direction inclined relative to the vertical direction.

[0015] The spindle head 3 rotatably holds a spindle 32. The spindle 32 is rotatably disposed inside the spindle head 3 and extends in the vertical direction (Z-axis direction). A tool 5 is detachably attached to the tip (lower end in FIG. 1 ) of the spindle 32. The spindle 32 rotates around a rotation axis along the Z-axis direction by rotation of a spindle motor 33 disposed above the spindle head 3, thereby rotating the tool 5 attached to the tip. The spindle motor 33 has an incremental type encoder (not shown). This encoder acquires position information (rotation angle information) about the rotation axis of the spindle motor 33 and the spindle 32.

[0016] The tool changer 4 is an automatic tool changer (ATC) that automatically changes the tool 5 attached to the spindle 32 for another tool 50. The tool changer 4 is disposed in front of and diagonally above the spindle head 3 (on the left side in FIG. 1 ). The tool changer 4 has a rotatable, disk-shaped turret 41 and multiple tool magazines 42 arranged on the outer periphery of the turret 41. The axial direction of the rotation axis J of the turret 41 intersects with the Z-axis direction and is disposed so as to incline downward as it moves forward from the spindle head 3. Each of the multiple tool magazines 42 is assigned a tool number. The tool magazine 42 is pre-loaded with multiple tools 50 for replacement.

[0017] 2 shows the control device 6 of the machine tool 100. The control device 6 is, for example, a numerical control device that controls the operation of the machine tool 100. The control device 6 has an input unit 61 that receives various inputs from an operator, a tool determination unit 62, an absolute position determination unit 63, a tool replacement operation execution unit 64, and a memory unit 65.

[0018] The control device 6 is mainly composed of a processor such as a CPU (Central Processing Unit). The control device 6 performs various processes by executing programs stored in a memory unit 65. The memory unit 65 is a storage device such as a ROM (Read Only Memory) that stores an OS (Operating System), application programs, etc., a RAM (Random Access Memory), a hard disk drive, or an SSD (Solid State Drive) that stores various other information. The processes of a tool determination unit 62, an absolute position determination unit 63, and a tool replacement operation execution unit 64, which will be described later, are performed by the CPU executing predetermined programs stored in the memory unit 65.

[0019] Control device 6 may include a reading unit that reads a program from a recording medium (not shown) on which the program is recorded. The recording medium is a computer-readable recording medium such as an optical disk, a magnetic disk, or a non-volatile semiconductor memory, and records a program for executing various processes of machine tool 100.

[0020] The tool determination unit 62 determines the type of tool 5 attached to the spindle 32. More specifically, the tool determination unit 62 determines whether the tool 5 attached to the spindle 32 is a rotating tool or a non-rotating tool.

[0021] The rotary tool is a tool that rotates with the rotation of the spindle 32 and performs cutting or other processing on a workpiece. Figure 3 shows an example of a rotary tool 5A that is attached to the spindle 32. The rotary tool 5A has a tapered portion 51 at its upper portion. The spindle 32 has a tapered tool attachment hole 321 at its lower end that corresponds to the tapered portion 51. The rotary tool 5A is held on the spindle 32 by inserting the tapered portion 51 into the tool attachment hole 321. When the spindle motor 33 rotates and the spindle 32 rotates, the rotary tool 5A rotates and performs cutting or other processing on a workpiece (not shown).

[0022] A non-rotating tool is a tool that performs turning or the like by rotating a workpiece (not shown) without rotating the tool itself. FIG. 4 shows an example of a non-rotating tool. Like the rotating tool 5A, the non-rotating tool 5B has a tapered portion 51 at its upper portion, but also has a flange portion 52 that protrudes toward one side intersecting the tool axial direction of the non-rotating tool 5B (the vertical direction in FIG. 4). An engaging protrusion 53 protrudes upward from the upper surface (the surface on the side where the tapered portion 51 is located) of the tip of the flange portion 52. The engaging protrusion 53 has a tapered shape that narrows toward the tip, but it does not have to have a tapered shape.

[0023] 3 and 5, the spindle head 3 has a rotation prevention portion 34 on the side of the tip of the spindle 32. The rotation prevention portion 34 has a cylindrical engagement portion 341 that protrudes downward parallel to the spindle 32. An engagement recess 342 having an internal shape that can engage with an engagement protrusion 53 of the non-rotating tool 5B is formed at the lower end of the engagement portion 341. The engagement recess 342 can engage with the engagement protrusion 53 when the tapered portion 51 is inserted into the tool mounting hole 321. The engagement recess 342 has a notch 342a formed by cutting out half of the outer periphery of the lower end of the engagement portion 341. As a result, the engagement recess 342 is open downward and to the side of the engagement portion 341. 6, the non-rotating tool 5B is mounted non-rotatably on the spindle 32 by inserting the tapered portion 51 into the tool mounting hole 321 of the spindle 32 and inserting the engaging protrusion 53 into the engaging recess 342 of the anti-rotation portion 34. The notch 342a does not necessarily have to be provided.

[0024] FIG. 7 shows another example of a non-rotating tool. The non-rotating tool 5C is similar to the non-rotating tool 5B in that it has a tapered portion 51 and a flange portion 52, but the flange portion 52 has an engagement recess 54. The engagement recess 54 shown in FIG. 7 is a through-hole provided in the flange portion 52. However, the engagement recess 54 may be a groove that does not pass through the flange portion 52. The anti-rotation portion 34 of the spindle head 3 to which this non-rotating tool 5C is attached has a cylindrical engagement protrusion 343 that protrudes downward and parallel to the spindle 32. A tapered portion 343a is formed at the lower end of the engagement protrusion 343 to facilitate insertion of the flange portion 52 into the engagement recess 54.

[0025] 8 shows another example of a non-rotating tool 5D. The non-rotating tool 5D is similar to the non-rotating tool 5C in that the flange portion 52 has an engagement recess 55 penetrating the flange portion 52. However, the engagement recess 55 of the non-rotating tool 5D has a notch shape that opens to the side of the flange portion 52.

[0026] The non-rotating tools 5C and 5D are mounted non-rotatably on the spindle 32 by inserting the tapered portion 51 into the tool mounting hole 321 of the spindle 32 and engaging the engaging recesses 54 and 55 with the tapered portion 343a of the engaging protrusion 343.

[0027] Whether the tool 5 attached to the spindle 32 is a rotating tool 5A or a non-rotating tool 5B, 5C, or 5D is determined by checking the information on the restriction function of the tool 5 corresponding to the tool number of the tool magazine 42 in which the tool 5 was attached when the tool 5 is transferred from the tool changer 4 to the spindle 32.

[0028] 9 shows an example of information defining the relationship between the tool numbers T01, T02, ... assigned to the tool magazine 42 of the tool changer 4 and the restriction functions of the tools attached to the tool magazine 42 corresponding to those tool numbers. This information is stored in advance in the memory unit 65 of the control device 6.

[0029] For example, in FIG. 9 , tool number T01 indicates a rotary cutting tool that rotates to perform cutting. Because this tool is a rotary tool, there are no restrictions. That is, when the tool with tool number 01 is attached to the spindle 32, the spindle 32 can rotate. Tool T02 is a turning tool that does not rotate itself, but rotates the workpiece to perform turning. Because this tool is a non-rotating tool, there is a restriction that rotation is prohibited. That is, when the tool with tool number 02 is attached to the spindle 32, the spindle 32 cannot rotate. Tool T03 is a touch probe, and there is a restriction that continuous rotation is prohibited.

[0030] This information is input in advance by the operator to the control device 6 via the input unit 61 and stored in the memory unit 65. When the tool 5 is transferred from the tool magazine 42 of the tool changer 4 to the spindle 32, the tool determination unit 62 reads, from the memory unit 65, information on the restriction function defined for the tool 5 corresponding to the tool number in the tool magazine 42, and determines whether the tool 5 is a rotating tool or a non-rotating tool. The tool determination unit 62 may also determine that a tool such as tool T03, which is prohibited from continuous rotation, is a non-rotating tool.

[0031] The absolute position determination unit 63 determines whether the spindle 32 has established an absolute position. The absolute position is the origin position around the rotation axis of the spindle 32. The absolute position of the spindle 32 is established by slightly oscillating the spindle motor 33 or by rotating the spindle motor 33 several times and reading the position information of the spindle 32 at that time with an encoder. This rotation operation of the spindle motor 33 for establishing the absolute position of the spindle 32 is referred to in this specification as an "absolute position recovery operation."

[0032] The absolute position restoration operation is normally executed after power is turned on, before the tool changer 4 performs the first tool replacement operation based on a tool replacement command. The tool replacement command is issued based on a machining program executed by the control device 6. When the absolute position restoration operation is executed, predetermined parameters or system variables are created in the control device 6. The absolute position determination unit 63 determines whether the current absolute position of the spindle 32 has been established by checking the parameters or system variables created by the execution of the absolute position restoration operation.

[0033] The tool change operation execution unit 64 starts the tool change device 4 based on the tool change command and executes a tool change operation for the spindle 32. When the tool change command is issued, the tool change operation execution unit 64 rotates the feed axis motor 22 in the forward and reverse directions to move the spindle head 3 up and down.

[0034] Here, with reference to FIGS. 10 to 12 , the position of the spindle head 3 during a tool changing operation of the machine tool 100 will be described. As shown in FIG. 10 , in the machine tool 100, a machining area is defined below the movement area of ​​the spindle head 3 along the Z-axis direction, and a tool changing area is defined above it. When performing a predetermined machining operation using a tool 5, the spindle head 3 moves into the machining area and performs the predetermined machining operation within the machining area. When a tool changing operation is performed, the spindle head 3 rises from the machining area toward the tool changing area. When the spindle head 3 rises to the spindle head lower end position for tool changing, the tool changer 4 moves toward the spindle head 3. To receive the tool 5 attached to the spindle 32, the tool changer 4 brings an empty tool magazine 42 of the turret 41 close to the spindle 32, and the tool 5 attached to the spindle 32 is gripped by the tool magazine 42.

[0035] 11 , when the spindle head 3 rises further, the tool 5 held in the tool magazine 42 is removed from the spindle 32 by the lifting operation of the spindle head 3 and held in the tool magazine 42. The spindle head 3 then rises to the spindle head upper end position for tool change. Because the spindle head 3 rises further after the tool 5 is removed from the spindle 32, the spindle head upper end position for tool change can be said to be a position where no tool is reliably attached to the spindle 32.

[0036] When another tool 50 is to be attached to the spindle 32, as shown in Figure 12, the turret 41 of the tool changer 4 rotates and the tool magazine 42 holding the tool 50 is positioned below the spindle 32. Thereafter, the spindle head 3 is lowered toward the tool 50 to the spindle head lower end position for tool changing. The tool 50 held in the tool magazine 42 is attached to the spindle 32 by the lowering movement of the spindle head 3. This completes the tool changing operation. The position control of the spindle head 3 in the Z axis direction is performed by the control device 6 detecting the position of the spindle head 3 in the Z axis direction using a position detection sensor or the like (not shown) and controlling the rotation of the feed axis motor 22.

[0037] 13 and 14, a first example of a specific flow of a tool changing operation by machine tool 100 will be described. The following tool changing operation is performed by control device 6 executing a predetermined tool changing program.

[0038] The spindle head 3 is disposed in the machining area. When a tool change command is issued, the control device 6 causes the tool determination unit 62 to determine the type of tool 5 attached to the spindle 32 of the spindle head 3, i.e., whether a non-rotating tool is attached to the spindle 32 (step S1). If it is determined that a non-rotating tool is not attached to the spindle 32 (step S1; NO), the spindle 32 is rotatable, and therefore the process proceeds to a normal tool change operation.

[0039] In a normal tool changing operation, the control device 6 determines whether the absolute position of the spindle 32 has been established by the absolute position determination unit 63 (step S2). If it is determined that the absolute position of the spindle 32 has been established (step S2; YES), the control device 6 does not execute the absolute position restoration operation (step S3), but executes the indexing operation of the spindle 32 to properly transfer the tool 5 (step S4).

[0040] If it is determined that the absolute position of the spindle 32 has not been established (step S2; NO), the control device 6 executes an absolute position restoration operation (step S5). Here, since it is determined that the tool 5 currently attached to the spindle 32 is a rotary tool and is rotatable, the control device 6 executes the absolute position restoration operation by slightly oscillating the spindle motor 33 or by rotating the spindle motor 33 several times. Thereafter, the control device 6 executes an indexing operation of the spindle 32 to properly transfer the tool 5 (step S4).

[0041] After the indexing operation of the spindle 32 is completed, the control device 6 causes the tool changing operation execution unit 64 to rotate the feed axis motor 22 and move (raise) the spindle head 3 from the machining area toward the tool changing area. During the movement of the spindle head 3, the tool magazine 42 of the tool changer 4 grips the tool 5, and the spindle 32 moves further (raises) to remove the tool 5. As a result, the tool magazine 42 receives the tool 5, which is a rotary tool attached to the spindle 32 (step S6).

[0042] After the tool magazine 42 receives the tool 5, the control device 6 rotates the turret 41 of the tool changer 4 using the tool change operation execution unit 64 while the spindle head 3 is moving, and indexes the turret 41 so that the tool magazine 42 holding the tool 50 to be next attached to the spindle 32 is positioned below the spindle 32 (step S7).

[0043] Thereafter, the control device 6 moves (lowers) the spindle head 3 again toward the machining area. During this movement, the tool 50 held in the tool magazine 42 is handed over to the spindle 32 (step S8). As a result, a new tool 50 is attached to the spindle 32, and the tool changing operation is completed.

[0044] On the other hand, in step S1, if the tool determination unit 62 determines that a non-rotating tool is attached to the spindle 32 (step S1; YES), the spindle 32 cannot rotate, so the control device 6 generates a command to prohibit the rotation of the spindle 32 and controls the tool replacement operation execution unit 64 not to perform the absolute position recovery operation and indexing operation of the spindle 32 within the machining area (step S9).

[0045] Thereafter, the control device 6 determines whether or not the current absolute position of the spindle 32 has been established by the absolute position determination unit 63 (step S10). If it is determined that the absolute position of the spindle 32 has been established (step S10; YES), the control device 6 shifts the process to step S6 and executes the processes of steps S6 to S8 described above.

[0046] If it is determined that the absolute position of the spindle 32 has not been established (step S10; NO), the control device 6 causes the tool change operation execution unit 64 to rotate the feed axis motor 22 and move (raise) the spindle head 3 from the machining area toward the tool change area. During the movement of the spindle head 3, the tool magazine 42 of the tool changer 4 grips the tool 5 attached to the spindle 32, and then the spindle 32 moves further (raises), thereby removing the tool 5 from the spindle 32. As a result, the tool magazine 42 receives the tool 5, which is a non-rotating tool attached to the spindle 32 (step S11).

[0047] At this time, the control device 6 may slow down the speed of the tool changing operation executed by the tool changing operation executing unit 64 compared to the normal speed, specifically, the speed of the tool changing operation executed when a rotatable tool is attached to the spindle 32. This is because at this point, the absolute position of the spindle 32 has not been established and the spindle 32 has not been indexed, which makes it easy for tool changing errors, such as the tool being dropped, to occur during tool changing. By slowing down the tool changing speed, tool changing errors can be prevented and safety during tool changing can be increased.

[0048] Thereafter, the control device 6 determines whether or not the movement to a position where the tool is not reliably attached to the spindle 32 has been completed (step S12). The position where the tool is not reliably attached to the spindle 32 is, for example, the upper end position of the spindle head during tool change shown in Figures 10 to 12. The control device 6 waits for processing until it determines that the movement to a position where the tool is not reliably attached to the spindle 32 has been completed.

[0049] If it is determined that the movement to the position where the tool is not reliably attached to the spindle 32 has been completed (step S12; YES), it is determined that the spindle 32 is reliably rotatable. Therefore, the control device 6 executes the absolute position restoration operation and the indexing operation of the spindle 32 (step S13). Thereafter, the control device 6 shifts the processing to step S7, executes the processing of steps S7 and S8, and then ends the tool changing operation.

[0050] According to the first example of the tool changing operation described above, as shown in Fig. 15 , the tool 5 is removed from the spindle 32, and the spindle head 3 is raised to the spindle head upper end position for tool change, and during the period from when the tool 5 is removed from the spindle 32 and when the spindle head 3 is lowered to the tool mounting position (the period indicated by the hatched arrow in Fig. 15 ), the absolute position restoration operation and indexing operation of the spindle 32 are performed. During this period, the tool 5 is removed from the spindle 32, and another tool 50 has not yet been mounted on the spindle 32. During this period, the spindle motor 33 is rotated to establish the absolute position of the spindle 32, and the absolute position restoration and indexing are completed, so that tool changing errors can be prevented during subsequent tool changing operations, and machining work can proceed smoothly.

[0051] Next, a second example of a specific flow of a tool changing operation by machine tool 100 will be described with reference to Fig. 16. In the flowchart shown in Fig. 16, step S20 is inserted instead of step S12 in the flowchart of the first example shown in Figs.

[0052] That is, after the tool magazine 42 receives the tool 5, which is a non-rotating tool to be mounted on the spindle 32, in step S11, the control device 6 determines whether the tool 5 is not mounted on the spindle 32 (step S20). Whether the tool 5 is not mounted on the spindle 32 can be determined, for example, by detecting a tool no-mount signal that the spindle 32 outputs when a tool is not mounted, not detecting a tool mounted signal that the spindle 32 outputs when a tool is mounted, or by detecting the start of the spindle head 3 rising from the spindle head lower end position (see FIGS. 10 to 12) during tool replacement. The control device 6 waits to execute processing until it determines that a tool is not mounted on the spindle 32.

[0053] If it is determined that a tool is not attached to the spindle 32 (step S20; YES), it is determined that the connection between the spindle 32 and the tool 5 has been released. Therefore, the control device 6 executes the absolute position restoration operation and the indexing operation of the spindle 32 at that time (step S13). Thereafter, the control device 6 shifts the processing to step S7 shown in Fig. 14, executes the processing of steps S7 and S8, and then ends the tool changing operation.

[0054] According to the second example of the tool changing operation described above, as shown in FIG. 17 , the absolute position restoration operation and indexing operation of the spindle 32 can be performed when the tool 5 is removed from the spindle 32. Therefore, the operation of the machine tool 100 that should be performed after the absolute position restoration operation and indexing operation of the spindle 32 are completed can be started early. The absolute position restoration operation and indexing operation of the spindle 32 can be performed during the period from when the spindle head 3, which is disposed at the tool removal position, starts to rise until when it descends to the tool attachment position (the period indicated by the hatched arrow in FIG. 17 ), which is a longer period than in the first example of the tool changing operation. Therefore, the absolute position restoration operation and indexing operation of the spindle 32 can be performed multiple times to ensure greater reliability.

[0055] The following supplementary notes are further disclosed regarding the above-described embodiment and modified examples. (Supplementary Note 1) A tool changer (4) includes a spindle (32) on which a tool (5, 50) can be attached, a spindle head (3) that rotatably holds the spindle (32), a spindle motor (33) that rotates the spindle (32), a tool changer (4) that replaces the tool (5) attached to the spindle (32) with another tool (50), and a control device (6) that controls the spindle motor (33) to perform a rotational operation to establish an absolute position of the spindle (32) before the tool changer (4) executes a tool changing operation, and the control device (6) includes a tool determination unit (62) that determines whether the tool (5) attached to the spindle (32) is a non-rotating tool that does not rotate with the rotation of the spindle (32), and an absolute position determination unit that determines whether the absolute position of the spindle (32) has been established. and a tool change operation executing unit (64) that executes a tool change operation on the spindle (32) by the tool change device (4), and when the tool determination unit (62) determines that a non-rotating tool is attached to the spindle (32) and the absolute position determination unit (63) determines that the spindle (32) has not established an absolute position, the tool change operation executing unit (64) starts the tool change operation without executing the rotation operation of the spindle motor (33) to establish the absolute position, and in a state where the non-rotating tool is removed from the spindle (32) and another tool (50) is not attached to the spindle (32), the tool change operation executing unit (64) executes the rotation operation of the spindle motor (33) to establish the absolute position of the spindle (32).

[0056] (Supplementary Note 2) In the machine tool (100) of Supplementary Note 1, the control device (6) further has a memory unit (61) that stores information regarding limitations on the rotational operation of the spindle motor (33) for a plurality of tools (5, 50), and the tool determination unit (62) determines whether the tool (5, 50) attached to the spindle (32) is a non-rotating tool based on the information stored in the memory unit (65).

[0057] (Supplementary Note 3) In the machine tool (100) of Supplementary Note 1 or 2, when the tool determination unit (62) determines that a non-rotating tool is attached to the spindle (32), the control device (6) slows down the speed of the tool changing operation performed by the tool changing operation execution unit (64).

[0058] (Supplementary Note 4) In the machine tool (100) of any of Supplementary Notes 1 to 3, the control device (6) starts the rotational operation of the spindle motor (33) to establish the absolute position of the spindle (32) when the non-rotating tool is removed from the spindle (32).

[0059] (Supplementary Note 5) In the machine tool (100) of any of Supplementary Notes 1 to 4, the non-rotating tool has an engaging convex portion (53) or an engaging concave portion (54, 55), and the spindle head (3) has an engaging concave portion (342) or an engaging convex portion (343) that engages with the engaging convex portion (53) or the engaging concave portion (54, 55) of the rotating tool attached to the spindle (32) to attach the non-rotating tool so as not to rotate.

[0060] (Supplementary Note 6) A tool changing method for a machine tool (100) that performs a rotational operation of the spindle motor (33) to establish an absolute position of the spindle (32) before executing a tool changing operation to change a tool (5) attached to the spindle (32) rotated by the spindle motor (33) for another tool (50), the method comprising: determining, before the tool change, whether the tool (5) attached to the spindle (32) is a non-rotating tool that does not rotate with the rotation of the spindle (32); and determining whether the spindle (32) has established an absolute position. and if it is determined that a non-rotating tool is attached to the spindle (32) and that the spindle (32) has not established an absolute position, the tool changing operation is started without executing the rotation operation of the spindle motor (33) for establishing the absolute position, and in a state in which the non-rotating tool is removed from the spindle (32) and another tool (50) is not attached to the spindle (32), the rotation operation of the spindle motor (33) is executed for establishing the absolute position of the spindle (32).

[0061] (Supplementary Note 7) A computer program for causing a computer to execute the following steps: before executing a tool changing operation to replace a tool (5) attached to a spindle (32) rotated by a spindle motor (33) with another tool (50), determining whether the tool (5) attached to the spindle (32) is a non-rotating tool that does not rotate with the rotation of the spindle (32); determining whether the spindle (32) has established an absolute position; when it is determined that a non-rotating tool is attached to the spindle (32) and that the spindle (32) has not established an absolute position, starting the tool changing operation without executing a rotation operation of the spindle motor (33) to establish the absolute position; and, in a state in which the non-rotating tool is removed from the spindle (32) and another tool (50) is not attached to the spindle (32), executing a rotation operation of the spindle motor (33) to establish the absolute position of the spindle (32).

[0062] Although the present disclosure has been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0063] 3 Spindle head 32 Spindle 33 Spindle motor 342 Engagement recess of spindle head 343 Engagement protrusion of spindle head 4 Tool changer 5, 50 Tool 53 Engagement protrusion of non-rotating tool 54, 55 Engagement recess of non-rotating tool 6 Control device 62 Tool determination unit 63 Absolute position determination unit 64 Tool change operation execution unit 65 Memory unit 100 Machine tool

Claims

1. A system comprising: a spindle to which a tool can be attached; a spindle head for rotatably holding the spindle; a spindle motor for rotating the spindle; a tool changer for changing the tool attached to the spindle for another tool; and a control device for controlling the spindle motor to perform a rotational operation to establish an absolute position of the spindle before the tool changer performs a tool change operation, wherein the control device has: a tool determination unit for determining whether the tool attached to the spindle is a non-rotating tool that does not rotate with the rotation of the spindle; an absolute position determination unit for determining whether the spindle has established the absolute position; and a tool change operation execution unit for executing the tool change operation for the spindle by the tool changer, a tool change operation execution unit that starts a tool change operation without executing a rotation operation of the spindle motor to establish the absolute position when the tool determination unit determines that the non-rotating tool is attached to the spindle and the absolute position determination unit determines that the spindle has not established the absolute position, and in a state where the non-rotating tool is removed from the spindle and the different tool is not attached to the spindle, executes a rotation operation of the spindle motor to establish the absolute position.

2. The machine tool according to claim 1, wherein the control device further has a memory unit that stores information relating to restrictions on the rotational operation of the spindle motor for a plurality of the tools, and the tool determination unit determines whether the tool attached to the spindle is a non-rotating tool based on the information stored in the memory unit.

3. A machine tool as described in claim 1 or 2, wherein the control device slows down the speed of the tool changing operation performed by the tool changing operation execution unit when the tool determination unit determines that the non-rotating tool is attached to the spindle.

4. A machine tool according to any one of claims 1 to 3, wherein the control device starts the rotational operation of the spindle motor to establish the absolute position of the spindle when the non-rotating tool is removed from the spindle.

5. A machine tool according to any one of claims 1 to 4, wherein the non-rotating tool has an engaging protrusion or an engaging recess, and the spindle head has an engaging recess or an engaging protrusion that engages with the engaging protrusion or the engaging recess of the non-rotating tool attached to the spindle to attach the non-rotating tool so as not to rotate.

6. A tool changing method for a machine tool in which, before executing a tool changing operation to replace a tool attached to a spindle rotated by a spindle motor with another tool, the method rotates the spindle motor to establish an absolute position of the spindle, comprising the steps of: determining, before the tool changing operation, whether the tool attached to the spindle is a non-rotating tool that does not rotate with the rotation of the spindle, and determining whether the spindle has established the absolute position; starting the tool changing operation without executing the rotational operation of the spindle motor to establish the absolute position when it is determined that the non-rotating tool is attached to the spindle and the spindle has not established the absolute position; and executing the rotational operation of the spindle motor to establish the absolute position when the non-rotating tool is removed from the spindle and the other tool is not attached to the spindle.

7. A computer program causing a computer to execute the following steps: before executing a tool changing operation to replace a tool attached to a spindle rotated by a spindle motor with another tool, determining whether the tool attached to the spindle is a non-rotating tool that does not rotate due to the rotation of the spindle; determining whether the spindle has established an absolute position; when it is determined that the non-rotating tool is attached to the spindle and the spindle has not established the absolute position, starting the tool changing operation without executing the rotational operation of the spindle motor to establish the absolute position; and with the non-rotating tool removed from the spindle and the other tool not attached to the spindle, executing the rotational operation of the spindle motor to establish the absolute position.

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