Machine tool

Abstract

To provide a technique for suppressing occurrence of thermal demagnetization in a linear motor.SOLUTION: A machine tool includes a linear motor. The linear motor includes a magnet plate, and a slider provided with a plurality of coils. The slider is configured to be slidable on the magnet plate by acting a magnetic field generated by applying a current to the plurality of coils on the magnet plate. The machine tool further includes a detection part for detecting the position of the slider, and a control device for controlling the machine tool. The control device executes processing of: driving the linear motor, on the basis of a command value related to a current; integrating a command value for a section to which the position of the slider belongs among a plurality of sections where a movable region of the slider is divided; and outputting a predetermined command, on the basis of an integrated value of the command value within a predetermined time exceeding a predetermined threshold, in any section of the plurality of sections.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present disclosure relates to machine tools.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2002-223587 (Patent Document 1) discloses a linear motor used in railways. The linear motor includes a mover and a plurality of stators. Each stator is provided with a coil, and the linear motor moves the mover by sequentially passing an electric current through each coil.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a linear motor in which coils are provided on the mover side instead of the stator side. The linear motor includes a magnetic plate that functions as a stator and a slider that functions as a mover. The slider is provided with a plurality of coils. The slider slides on the magnetic plate by applying a magnetic field generated by applying an electric current to the plurality of coils to the magnetic plate.

[0005] The heat generated in the slider is transferred to the magnetic plate. At locations where the slider easily passes, the temperature of the magnetic plate rises, and there is a possibility of thermal demagnetization. Therefore, a technique for suppressing the occurrence of thermal demagnetization in the linear motor is desired.

Means for Solving the Problems

[0006] In one example of the present disclosure, a machine tool including a linear motor is provided. The linear motor includes a magnet plate and a slider provided with a plurality of coils. The slider is configured to be slidable on the magnet plate by causing a magnetic field generated by applying a current to the plurality of coils to act on the magnet plate. The machine tool further includes a detection unit for detecting the position of the slider and a control device for controlling the machine tool. The control device executes a process of driving the linear motor based on a command value related to the current, a process of integrating the command value for a section to which the position of the slider belongs among a plurality of sections obtained by dividing the movable region of the slider, and a process of outputting a predetermined command based on the fact that an integrated value of the command value within a predetermined time exceeds a predetermined threshold value in any one of the plurality of sections.

[0007] In one example of the present disclosure, the integrating process includes a process of integrating the command value for an adjacent section of the section to which the slider belongs. The command value integrated for the adjacent section is smaller than the command value integrated for the section to which the slider belongs.

[0008] In one example of the present disclosure, the predetermined command includes a command for stopping the driving process.

[0009] In one example of the present disclosure, the predetermined command includes a command for notifying a warning.

[0010] In one example of the present disclosure, the machine tool further includes a spindle for rotatably holding a workpiece or a tool. The linear motor is used to drive the spindle.

[0011] In one example of the present disclosure, the machine tool further includes a table for placing a workpiece. The linear motor is used to drive the table.

[0012] In an example of the present disclosure, the machine tool further includes a loader for transporting members. The linear motor is used to drive the loader.

[0013] The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention understood in connection with the accompanying drawings.

Brief Description of the Drawings

[0014]

Figure 1

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Embodiments for Carrying Out the Invention

[0015] Hereinafter, each embodiment according to the present invention will be described with reference to the drawings. In the following description, the same parts and components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated. In addition, each embodiment and each modification described below may be selectively combined as appropriate.

[0016] <A. Appearance of Machine Tool 100> First, with reference to FIG. 1, a machine tool 100 according to an embodiment will be described. FIG. 1 is a diagram showing the appearance of the machine tool 100.

[0017] As used herein, the "machine tool" is a concept encompassing various devices having a function of processing a workpiece. The machine tool 100 may be a horizontal machining center or a vertical machining center. Alternatively, the machine tool 100 may be a lathe, or other cutting machines, grinding machines, composite machining machines, 5-axis machining machines, etc. Further, the machine tool 100 is not limited to performing only removal machining, and may perform additional machining in addition to removal machining.

[0018] The machine tool 100 includes, for example, a cover body 130 and an operation panel 200. The cover body 130, also called a splash guard, forms the appearance of the machine tool 100 and partitions the machining area AR of the workpiece.

[0019] The machine tool 100 processes a workpiece while discharging coolant into the machining area AR. The coolant used for machining causes the chips of the workpiece to flow from the machining area AR to the chip conveyor 150. The chip conveyor 150 separates the chips of the workpiece from the coolant and discharges the chips outside the machine tool 100 through the discharge port 27. The coolant from which the chips of the workpiece have been removed is reused for machining the workpiece.

[0020] The operation panel 200 is a general-purpose computer and has a display 206 for displaying various information related to machining. The display 206 is, for example, a liquid crystal display, an organic EL (Electro Luminescence) display, or other display device. Further, the display 206 is provided with a touch panel and accepts various operations on the machine tool 100 by touch operation.

[0021] <B. Linear motor 5> Inside the machine tool 100, there are various drive bodies such as a spindle and a table. The drive body is driven by, for example, a linear motor.

[0022] Hereinafter, with reference to FIG. 2, a linear motor 5 which is an example of a power source will be described. FIG. 2 is a perspective view showing the linear motor 5 provided inside the machine tool 100.

[0023] As shown in FIG. 2, the linear motor 5 includes a magnet plate 10 and a slider 50.

[0024] The magnet plate 10 functions as a stator and is attached to immovable parts inside the machine tool 100. A plurality of magnets 12 are arranged on the magnet plate 10. For the sake of convenience of explanation, hereinafter, the direction in which the magnets 12 are arranged is also referred to as the X-axis direction. The direction parallel to the surface of the magnet plate 10 and orthogonal to the X-axis direction is also referred to as the Y-axis direction. The direction orthogonal to both the X-axis direction and the Y-axis direction is also referred to as the Z-axis direction.

[0025] Each of the plurality of magnets 12 is arranged on the magnetic plate 10 at a predetermined interval in the X-axis direction. Each of the magnets 12 is a permanent magnet. Each of the magnets 12 is provided on the magnetic plate 10 such that its polarity is opposite to that of the adjacent magnet 12. For example, assume that the front surface of a certain magnet 12 is the N pole and the back surface is the S pole. In this case, for the magnet 12 arranged adjacent to the certain magnet 12, the front surface is the S pole and the back surface is the N pole.

[0026] The slider 50 functions as a mover and is attached to a component to be driven in the machine tool 100. The slider 50 has a plurality of coils 52. The plurality of coils 52 are provided on the slider 50 side by side in the X-axis direction. Also, each of the coils 52 extends in the Y-axis direction and is wound in an oval shape around teeth 53 (see FIG. 4) formed on the slider 50, which will be described later.

[0027] The plurality of coils 52 are provided on the slider 50 so as to face the plurality of magnets 12. In other words, the plurality of coils 52 are provided on the slider 50 so as to overlap the plurality of magnets 12 when viewed from the Z-axis direction.

[0028] The slider 50 receives a thrust by causing a magnetic field generated by applying an alternating current to the plurality of coils 52 to act on the plurality of magnets 12, and slides on the magnetic plate 10 in the X-axis direction. The alternating current is supplied, for example, from a power source (not shown) electrically connected to the coil 52.

[0029] <C. Slider 50> Next, with reference to FIGS. 3 to 5, the above-described slider 50 will be described in more detail. FIG. 3 is a view showing the slider 50 from the Z-axis direction. FIG. 4 is a cross-sectional view of the slider 50 taken along line IV-IV shown in FIG. 3. FIG. 5 is a cross-sectional view of the slider 50 taken along line V-V shown in FIG. 3.

[0030] The slider 50 has a housing 60 that forms its exterior. The housing 60 is made of, for example, resin. Inside the housing 60, a slider core 51, a plurality of coils 52, a cooling pipe 56, and a fixing member 58 are accommodated.

[0031] The slider core 51 is composed of, for example, electromagnetic steel sheets. Also, a plurality of teeth 53 are formed on the slider core 51.

[0032] Each of the teeth 53 protrudes from the lower surface of the slider core 51 (i.e., the surface portion facing the magnetic plate 10) toward the magnetic plate 10. In other words, the plurality of teeth 53 face the above-mentioned magnetic plate 10 and are formed on the slider core 51 so as to overlap the magnetic plate 10 when viewed from the Z-axis direction. Also, each of the teeth 53 extends in the Y-axis direction.

[0033] The teeth 53 include auxiliary teeth 53A that are the outermost teeth in the X-axis direction and on which the coil 52 is not wound, and teeth 53B for coils that are located inside the auxiliary teeth 53A and on which the coil 52 is wound. The coil 52 is wound around the teeth 53B for coils in an oval shape.

[0034] A through-hole H extending in the Y-axis direction is formed in the teeth 53B for coils. The fixing member 58 is inserted into the through-hole H. A screw hole is formed in the fixing member 58 in the Z-axis direction, and a through-hole H communicating with the screw hole of the fixing member 58 is formed in the slider core 51 in the Z-axis direction.

[0035] The shape of the fixing member 58 is arbitrary. As an example, the shape of the fixing member 58 may be a rectangular parallelepiped-shaped angle bar, a cylindrical shape, or other shapes.

[0036] The fixing member 58 is composed of a member of a type different from that of the slider core 51. As an example, while the slider core 51 is composed of laminated steel plates, the fixing member 58 is composed of a metal other than laminated steel plates. As an example, the fixing member 58 may be composed of iron or other types of metals.

[0037] The cooling pipe 56 is provided on the surface portion on the side opposite to the side facing the magnetic stone plate 10. The cooling pipe 56 has a refrigerant inlet and a refrigerant outlet. The inlet and the outlet are connected to a cooler (not shown). The refrigerant flows from the inlet of the cooling pipe 56 to the outlet of the cooling pipe 56 to cool the slider 50. The refrigerant that has reached the outlet is sent to the cooler and cooled. Thereafter, the cooled refrigerant is sent again to the inlet of the cooling pipe 56. In this way, the refrigerant discharges waste heat from the slider 50 by circulating on the upper surface of the slider core 51. The refrigerant is, for example, a liquid containing water or the like.

[0038] The cooling pipe 56 is composed of, for example, a metal pipe with good thermal conductivity. As an example, the cooling pipe 56 may be composed of a copper pipe, an aluminum pipe, or a stainless steel pipe.

[0039] Note that FIG. 4 shows an example in which the cross-sectional shape of the cooling pipe 56 is circular, but the cross-sectional shape of the cooling pipe 56 is arbitrary. The cross-sectional shape of the cooling pipe 56 may be, for example, a polygon or other shapes.

[0040] <D. Summary> The heat generated in the slider 50 is transmitted to the magnetic stone plate 10. At the location on the magnetic stone plate 10 where the slider 50 easily passes, the temperature rises and there is a possibility of thermal demagnetization. When thermal demagnetization occurs, the magnetic force of the magnetic stone plate 10, which is a permanent magnet, decreases. Therefore, the machine tool 100 according to the embodiment monitors the position of the slider 50 and, when there is a bias in the position of the slider 50, executes a process for dealing with thermal demagnetization.

[0041] Hereinafter, with reference to FIGS. 6 to 8, a process for dealing with thermal demagnetization will be described. FIG. 6 is a diagram schematically showing the flow of signals between the control device 1 and the linear motor 5.

[0042] As shown in FIG. 6, the machine tool 100 includes a control device 1 and a linear motor 5. As described above, the linear motor 5 is composed of a magnet plate 10 and a slider 50.

[0043] The linear motor 5 is provided with a position detection mechanism 70 for detecting the position of the slider 50. Any mechanism capable of detecting the position of the slider 50 can be adopted for the position detection mechanism 70.

[0044] As an example, an electromagnetic linear scale, an optical linear scale, or other mechanisms may be adopted for the position detection mechanism 70. The position detection mechanism 70 is composed of, for example, a scale provided on a stator (for example, the magnet plate 10) and a sensor head provided on a mover (for example, the slider 50). The sensor head can detect the position of the slider 50 by reading the scale. The detected position is periodically output to the control device 1.

[0045] The control device 1 controls the drive of the linear motor 5 based on the current command value defined by a program. At this time, the control device 1 integrates the current command value for the section to which the position of the slider 50 belongs within a plurality of sections obtained by dividing the movable region of the slider 50. Then, the control device 1 outputs a predetermined command for dealing with thermal demagnetization based on the fact that the integrated value of the current command value within a predetermined time exceeds a predetermined threshold value in any one of the sections.

[0046] With reference to FIGS. 7 to 9, a specific example will be described. FIG. 7 is a diagram showing the relationship between the current command value and the movement of the linear motor 5. In FIG. 7, the movable region of the slider 50 is divided into sections RA to RN. The lengths of each of the sections RA to RN may be the same or different from each other. FIG. 8 is a diagram showing the change in the integrated value of the current command value in each of the sections RA to RN.

[0047] Assume that the current command value was constant from time “T0” to time “T1” (see FIG. 7). Assume that the position of the slider 50 detected by the position detection mechanism 70 during that time belonged to section RA. In this case, the control device 1 integrates the current command value for section RA (see FIG. 8). On the other hand, the control device 1 does not integrate the current command value for sections RB to RN other than section RA. Note that the value to be integrated does not necessarily have to be the current command value itself, and may be a physical quantity correlated with the current command value.

[0048] Thereafter, assume that the current command value was constant from time “T1” to time “T2” (see FIG. 7). Assume that the position of the slider 50 detected by the position detection mechanism 70 during that time belonged to section RB. In this case, the control device 1 integrates the current command value for section RB (see FIG. 8). On the other hand, the control device 1 does not integrate the current command value for sections RA, RC to RN other than section RB.

[0049] FIG. 9 is a diagram showing the transition of the integrated value of the current command value in each of the sections RA to RN. The control device 1 calculates the integrated value of the current command value within a predetermined time ΔT for each of the sections RA to RN. The length of the predetermined time ΔT may be set in advance or may be arbitrarily set by the user.

[0050] In the example of FIG. 9, the period from time “Tα” to time “Tβ” is shown as the predetermined time ΔT. Typically, time “Tβ” is the current time. The control device 1 calculates the integrated value (increase amount) of the current command value in the time ΔT from the past time “Tα” to the current time “Tβ”.

[0051] Then, the control device 1 determines whether the integrated value of the current command value within a predetermined time ΔT exceeds a predetermined threshold value th. The threshold value th may be set in advance or may be arbitrarily set by the user. Also, the threshold value th may be the same for each of the sections RA to RN, or may be different for each of the sections RA to RN.

[0052] Based on the integrated value of the current command value within a predetermined time ΔT exceeding the predetermined threshold value th in any one of the sections RA to RN, the control device 1 outputs a predetermined command for dealing with thermal demagnetization. In the example of FIG. 9, in section RB, the integrated value of the current command value within a predetermined time ΔT exceeds the predetermined threshold value th. In this case, the control device 1 outputs a predetermined command for dealing with thermal demagnetization.

[0053] Thereby, the machine tool 100 can suppress thermal demagnetization when there is a bias in the position of the slider 50. To achieve this, it is not necessary to provide a temperature sensor on the magnetic plate 10. If a temperature sensor is used to suppress thermal demagnetization, it is necessary to provide a temperature sensor at every location of the magnetic plate 10. The machine tool 100 according to the embodiment can predict the temperature rise of the magnetic plate 10 based on the position of the slider 50 and the current command value of the slider 50. In this way, the machine tool 100 can suppress the thermal demagnetization of the linear motor 5 without providing extra hardware such as a temperature sensor.

[0054] When the integrated value of the current command value within a predetermined time ΔT exceeds the predetermined threshold value th, the control device 1 outputs a predetermined command for dealing with thermal demagnetization. An example of the predetermined command is a command for stopping the drive process of the linear motor 5. Thereby, the drive of the linear motor 5 is stopped, and the temperature rise of the magnetic plate 10 is suppressed. As a result, thermal demagnetization is suppressed.

[0055] As another example of the above-mentioned predetermined command, there is a command for notifying a warning indicating that the temperature of the linear motor 5 exceeds the allowable range. The warning notification means is arbitrary. As an example, the notification process is realized by displaying a message on the above-described display 206. As another example, the notification process is realized by causing a lamp (not shown) provided on the machine tool 100 to emit light. As still another example, the notification process is realized by outputting sound from a speaker (not shown) provided on the machine tool 100. By the above-described notification process, the operator can recognize that the temperature of the linear motor 5 exceeds the allowable range.

[0056] In the examples of FIGS. 7 to 9 described above, the example in which the current command value is integrated only for the section to which the position of the slider 50 belongs has been described. However, the current command value may also be integrated for sections adjacent to the section to which the position of the slider 50 belongs. In this case, the current command value integrated for the adjacent section is smaller than the current command value integrated for the section where the slider 50 exists. That is, the farther the section is from the slider 50, the smaller the added current command value becomes. Since the amount of heat transfer from the slider 50 is larger for sections closer to the slider 50, the control device 1 can more accurately determine whether or not the temperature of the linear motor 5 exceeds the allowable range.

[0057] While referring to FIG. 7 described above, a specific example will be described with reference to FIG. 10. FIG. 10 is a diagram showing changes in the integrated values of the current command values in each of the sections RA to RN.

[0058] As shown in FIG. 7, assume that the current command value was constant from time “T0” to time “T1”. Assume that during that period, the position of the slider 50 detected by the position detection mechanism 70 belonged to section RA. In this case, the control device 1 integrates the current command value for section RA and section RB adjacent to section RA (see FIG. 10). At this time, the current command value integrated for the adjacent section RB is smaller than the current command value integrated for section RA where the slider 50 is present. On the other hand, the control device 1 does not integrate the current command value for a section that is a certain distance or more away from section RA (for example, section RN) (see FIG. 10).

[0059] Thereafter, assume that the current command value was constant from time “T1” to time “T2”. Assume that during that period, the position of the slider 50 detected by the position detection mechanism 70 belonged to section RB. In this case, the control device 1 integrates the current command value for section RB and sections RA and RC adjacent to section RB (see FIG. 10). At this time, the current command value integrated for the adjacent sections RA and RC is smaller than the current command value integrated for section RB where the slider 50 is present. On the other hand, the control device 1 does not integrate the current command value for a section that is a certain distance or more away from section RB (for example, section RN) (see FIG. 10).

[0060] <E. Hardware Configuration of CPU Unit 20> Next, with reference to FIG. 11, the hardware configuration of the CPU unit 20, which is an example of the control device 1 shown in FIG. 6 described above, will be described. FIG. 11 is a diagram showing an example of the hardware configuration of the CPU unit 20.

[0061] The CPU unit 20 includes a control circuit 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, communication interfaces 104 and 105, and an auxiliary storage device 120. These components are connected to an internal bus 109.

[0062] The control circuit 101 is constituted by, for example, at least one integrated circuit. The integrated circuit can be constituted by, for example, at least one CPU, at least one GPU (Graphics Processing Unit), at least one ASIC (Application Specific Integrated Circuit), at least one FPGA (Field Programmable Gate Array), or a combination thereof.

[0063] The control circuit 101 controls the operation of the CPU unit 20 by executing various programs such as the control program 122. The control program 122 is a program for realizing the various processes described in this specification. The control circuit 101 reads the control program 122 from the auxiliary storage device 120 or the ROM 102 into the RAM 103 based on receiving an execution instruction of the control program 122. The RAM 103 functions as a working memory and temporarily stores various data necessary for the execution of the control program 122.

[0064] The communication interface 104 is an interface for performing periodic communication with an external device using a field network. The external device includes, for example, the motor drivers 241A to 241H (see FIGS. 14 to 16) described later. As the field network, for example, EtherCAT (registered trademark), EtherNet / IP (registered trademark), CC-Link (registered trademark), or CompoNet (registered trademark) is adopted.

[0065] A LAN, an antenna, etc. are connected to the communication interface 105. The CPU unit 20 is connected to a network via the communication interface 105. Thereby, the CPU unit 20 exchanges data with an external device connected to the network. The external device includes, for example, the operation panel 200 and a server (not shown) described above.

[0066] The auxiliary storage device 120 is a storage medium such as a hard disk or a flash memory, for example. The auxiliary storage device 120 stores a control program 122 and the like. Note that the storage location of the control program 122 is not limited to the auxiliary storage device 120, and it may be stored in the storage area of the control circuit 101 (for example, cache memory), ROM 102, RAM 103, an external device (for example, a server), or the like.

[0067] Further, the control program 122 may be provided not as a single program but incorporated into a part of an arbitrary program. In this case, various processes according to the present embodiment are realized in cooperation with an arbitrary program. Even a program that does not include such a part of the module does not deviate from the gist of the control program 122 according to the present embodiment. Furthermore, some or all of the functions provided by the control program 122 may be realized by dedicated hardware. Furthermore, the control device 1 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the control program 122.

[0068] <Hardware Configuration of F.CNC Unit 30> Next, with reference to FIG. 12, the hardware configuration of a CNC unit 30, which is an example of the control device 1 shown in FIG. 6 described above, will be described. FIG. 12 is a diagram showing an example of the hardware configuration of the CNC unit 30.

[0069] The CNC unit 30 includes a control circuit 301, a ROM 302, a RAM 303, a communication interface 304, and an auxiliary storage device 320. These components are connected to an internal bus 309.

[0070] The control circuit 301 is constituted by, for example, at least one integrated circuit. The integrated circuit can be constituted by, for example, at least one CPU, at least one GPU, at least one ASIC, at least one FPGA, or a combination thereof.

[0071] The control circuit 301 controls the operation of the CNC unit 30 by executing various programs such as the control program 322. The control program 322 includes, for example, a workpiece processing program. The control circuit 301 reads the control program 322 from the ROM 302 into the RAM 303 based on receiving an execution instruction of the control program 322. The RAM 303 functions as a working memory and temporarily stores various data necessary for the execution of the control program 322.

[0072] The communication interface 304 is an interface for realizing communication with other devices, either wired or wireless. As an example, the CNC unit 30 communicates with various drive units for realizing workpiece processing via the communication interface 304.

[0073] The auxiliary storage device 320 is a storage medium such as a hard disk or a flash memory, for example. The auxiliary storage device 320 stores the control program 322 and the like. The storage location of the control program 322 is not limited to the auxiliary storage device 320 and may be stored in the storage area of the control circuit 301 (for example, cache memory), the ROM 302, the RAM 303, an external device (for example, a server), or the like.

[0074] Also, the control program 322 may be provided incorporated not as a single program but as a part of any program. In this case, the control processing defined in the control program 322 is realized in cooperation with any program. Even a program that does not include such a part of the module does not deviate from the gist of the control program 322 according to the present embodiment. Furthermore, part or all of the functions provided by the control program 322 may be realized by dedicated hardware. Furthermore, the machine tool 100 may be configured in a form such as a so-called cloud service in which at least one server executes a part of the processing of the control program 322.

[0075] <G. Flowchart> Next, with reference to FIG. 13, the display process of the machine tool 100 will be described. FIG. 13 is a flowchart showing the flow of the display process of the machine tool 100.

[0076] The process shown in FIG. 13 is executed by the above-described CPU unit 20 which is an example of the control device 1. Alternatively, the process shown in FIG. 13 is executed by the above-described CNC unit 30 which is an example of the control device 1. Alternatively, the process shown in FIG. 13 is realized by the cooperation of the CPU unit 20 and the CNC unit 30 which are examples of the control device 1. In other aspects, part or all of the process may be executed by the operation panel 200, circuit elements, or other hardware.

[0077] In step S110, the control device 1 drives the linear motor 5 based on the current command value defined in the program.

[0078] In step S112, the control device 1 acquires the position of the slider 50 constituting the linear motor 5 from the above-described position detection mechanism 70.

[0079] In step S114, the control device 1 specifies the section to which the slider 50 belongs within a plurality of sections RA to RN obtained by dividing the movable region of the slider 50 based on the position of the slider 50 acquired in step S112.

[0080] In step S116, the control device 1 integrates the current command value for driving the linear motor 5 for the section specified in step S114. Preferably, the control device 1 also integrates the current command value for other sections according to the distance from the section specified in step S114. At this time, the current command value integrated for the other section becomes smaller as the distance from the section specified in step S114 becomes longer.

[0081] In step S120, the control device 1 determines whether the execution timing of the abnormality determination process has arrived. The execution timing arrives, for example, at regular intervals during the driving of the linear motor 5. When the control device 1 determines that the execution timing of the abnormality determination process has arrived (YES in step S120), it switches the control to step S122. Otherwise (NO in step S120), the control device 1 returns the control to step S110.

[0082] In step S122, the control device 1 calculates the integrated value of the current command value within a predetermined time for each of the sections RA to RN.

[0083] In step S130, the control device 1 determines whether the integrated value of the current command value within a predetermined time exceeds a predetermined threshold in any of the sections RA to RN. When the control device 1 determines that the integrated value of the current command value within a predetermined time exceeds a predetermined threshold in any of the sections RA to RN (YES in step S130), it switches the control to step S132. Otherwise (NO in step S130), the control device 1 returns the control to step S110.

[0084] In step S132, the control device 1 outputs a predetermined command for dealing with thermal demagnetization. As an example of the predetermined command, a command for stopping the driving process of the linear motor 5 can be mentioned. As another example of the predetermined command, a command for notifying a warning indicating that the temperature of the linear motor 5 exceeds the allowable range can be mentioned.

[0085] <H. Application Example of Linear Motor 5> Next, with reference to FIGS. 14 to 16, the application example of the above-described linear motor 5 will be described. The linear motor 5 can be used, for example, to drive components within the machine tool 100.

[0086] When the linear motor 5 is used within the machine tool 100, the magnetic plate 10 that functions as a stator is attached to the stationary parts within the machine tool 100. On the other hand, the slider 50 that functions as a mover is attached to the part to be driven within the machine tool 100. In this case, a bolt is passed through the part to be driven, and the bolt is fitted into the threaded hole formed in the above-described fixing member 58 formed within the slider 50. Thereby, the part to be driven is fixed to the slider 50.

[0087] (H1. Spindle) First, with reference to FIG. 14, an example of applying the linear motor 5 to the drive of the spindle will be described. FIG. 14 is a diagram showing an example of the device configuration of the machine tool 100.

[0088] The linear motor 5 is used, for example, to move the position of the spindle 250 for rotatably holding a workpiece or a tool. The spindle 250 may be a workpiece spindle for rotating a workpiece or a tool spindle for rotating a tool.

[0089] For the sake of convenience of explanation, hereinafter, the coordinate system based on the spindle 250 is represented by the X'-axis, Y'-axis, and Z'-axis. The X'-axis, Y'-axis, and Z'-axis are orthogonal to each other.

[0090] As shown in FIG. 14, the machine tool 100 includes a control device 1, a drive unit 240A, and a spindle 250.

[0091] The drive unit 240A is a mechanism for driving the spindle 250. The device configuration of the drive unit 240A is arbitrary. The drive unit 240A may be composed of a single drive unit or a plurality of drive units. In the example of FIG. 14, the drive unit 240A is composed of motor drivers 241A to 241C, linear motors 242A to 242C, and position detection mechanisms 243A to 243C. Each of the linear motors 242A to 242C corresponds to the above-described linear motor 5. Each of the position detection mechanisms 243A to 243C corresponds to the above-described position detection mechanism 70.

[0092] The motor driver 241A controls the drive of the spindle 250 in the X' axis direction. The motor driver 241A receives an input of a current command value from the control device 1 and outputs a current corresponding to the current command value to the linear motor 242A.

[0093] More specifically, the control device 1 sequentially outputs a current command value (target speed) to the motor driver 241A. The motor driver 241A calculates the actual speed of the spindle 250 from the position signal of the position detection mechanism 243A and outputs a current to the linear motor 242A so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241A moves the spindle 250 to an arbitrary position in the X' axis direction.

[0094] The motor driver 241B controls the drive of the spindle 250 in the Y' axis direction. The motor driver 241B receives an input of a current command value from the control device 1 and outputs a current corresponding to the current command value to the linear motor 242B.

[0095] More specifically, the control device 1 sequentially outputs a current command value (target speed) to the motor driver 241B. The motor driver 241B calculates the actual speed of the spindle 250 from the position signal of the position detection mechanism 243B and outputs a current to the linear motor 242B so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241B moves the spindle 250 to an arbitrary position in the Y' axis direction.

[0096] The motor driver 241C controls the drive of the spindle 250 in the Z' axis direction. The motor driver 241C receives an input of a current command value from the control device 1 and outputs a current corresponding to the current command value to the linear motor 242C.

[0097] More specifically, the control device 1 sequentially outputs a current command value (target speed) to the motor driver 241C. The motor driver 241C calculates the actual speed of the main shaft 250 from the position signal of the position detection mechanism 243C, and outputs a current to the linear motor 242C so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241C moves the main shaft 250 to an arbitrary position in the Z'-axis direction.

[0098] (H2. Table) Next, with reference to FIG. 15, an example of applying the linear motor 5 to the drive of the table will be described. FIG. 15 is a diagram showing another example of the device configuration of the machine tool 100.

[0099] The linear motor 5 is used, for example, to drive a table 260 provided in a machine tool. The table 260 is a table for placing a workpiece to be processed.

[0100] As shown in FIG. 15, the machine tool 100 includes a control device 1, a drive unit 240B, and a table 260.

[0101] The drive unit 240B is a mechanism for driving the table 260. The device configuration of the drive unit 240B is arbitrary. The drive unit 240B may be composed of a single drive unit or a plurality of drive units. In the example of FIG. 15, the drive unit 240B is composed of motor drivers 241D, 241E, linear motors 242D, 242E, and position detection mechanisms 243D, 243E. Each of the linear motors 242D, 242E corresponds to the above-described linear motor 5. Each of the position detection mechanisms 243D, 243E corresponds to the above-described position detection mechanism 70.

[0102] The motor driver 241D controls the drive of the table 260 in the X'-axis direction. The motor driver 241D receives an input of a current command value from the control device 1, and outputs a current corresponding to the current command value to the linear motor 242D.

[0103] More specifically, the control device 1 sequentially outputs a current command value (target speed) to the motor driver 241D. The motor driver 241D calculates the actual speed of the table 260 from the position signal of the position detection mechanism 243D, and outputs a current to the linear motor 242D so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241D moves the table 260 to an arbitrary position in the X'-axis direction.

[0104] The motor driver 241E controls the drive of the table 260 in the Y'-axis direction. The motor driver 241E receives an input of a current command value from the control device 1, and outputs a current corresponding to the current command value to the linear motor 242E.

[0105] More specifically, the control device 1 sequentially outputs a current command value (target speed) to the motor driver 241E. The motor driver 241E calculates the actual speed of the table 260 from the position signal of the position detection mechanism 243E, and outputs a current to the linear motor 242E so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241E moves the table 260 to an arbitrary position in the Y'-axis direction.

[0106] (H3. Loader) Next, with reference to FIG. 16, an example of applying the linear motor 5 to the drive of a loader will be described. FIG. 16 is a diagram showing another example of the device configuration of the machine tool 100.

[0107] The linear motor 5 is used, for example, to drive a loader 270 for transporting a member. The member may be a workpiece before or after machining, or a tool.

[0108] As shown in FIG. 16, the machine tool 100 includes a control device 1, a drive unit 240C, and a loader 270.

[0109] The drive unit 240C is a mechanism for driving the loader 270. The device configuration of the drive unit 240C is arbitrary. The drive unit 240C may be composed of a single drive unit or a plurality of drive units. In the example of FIG. 16, the drive unit 240C is composed of motor drivers 241F to 241H, linear motors 242F to 242H, and position detection mechanisms 243F to 243H. Each of the linear motors 242F to 242H corresponds to the above-described linear motor 5. Each of the position detection mechanisms 243F to 243H corresponds to the above-described position detection mechanism 70.

[0110] The motor driver 241F controls the drive of the loader 270 in the X'-axis direction. The motor driver 241F receives an input of a current command value from the control device 1 and outputs a current corresponding to the current command value to the linear motor 242F.

[0111] More specifically, the control device 1 sequentially outputs a current command value (target speed) to the motor driver 241F. The motor driver 241F calculates the actual speed of the loader 270 from the position signal of the position detection mechanism 243F and outputs a current to the linear motor 242F so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241F moves the loader 270 to an arbitrary position in the X'-axis direction.

[0112] The motor driver 241G controls the drive of the loader 270 in the Y'-axis direction. The motor driver 241G receives an input of a current command value from the control device 1 and outputs a current corresponding to the current command value to the linear motor 242G.

[0113] More specifically, the control device 1 sequentially outputs a current command value (target speed) to the motor driver 241G. The motor driver 241G calculates the actual speed of the loader 270 from the position signal of the position detection mechanism 243G and outputs a current to the linear motor 242G so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241G moves the loader 270 to an arbitrary position in the Y'-axis direction.

[0114] The motor driver 241H controls the drive of the loader 270 in the Z'-axis direction. The motor driver 241H receives an input of a current command value from the control device 1 and outputs a current corresponding to the current command value to the linear motor 242H.

[0115] More specifically, the control device 1 sequentially outputs a control signal including a target speed to the motor driver 241H. The motor driver 241H calculates the actual speed of the loader 270 from the position signal of the position detection mechanism 243H and outputs a current to the linear motor 242H so that the difference between the actual speed and the target speed becomes small. Thereby, the motor driver 241H moves the loader 270 to an arbitrary position in the Z'-axis direction.

[0116] It should be considered that all aspects of the embodiments disclosed this time are illustrative and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims are included.

Explanation of Reference Numerals

[0117] 1 Control device, 5 Linear motor, 10 Magnet plate, 12 Magnet, 20 CPU unit, 27 Discharge port, 30 CNC unit, 50 Slider, 51 Slider core, 52 Coil, 53 Teeth, 53A Auxiliary teeth, 53B Coil teeth, 56 Cooling pipe, 58 Fixing member, 60 Housing, 70 Position detection mechanism, 100 Machine tool, 101 Control circuit, 102 ROM, 103 RAM, 104 Communication interface, 105 Communication interface, 109 Internal bus, 120 Auxiliary storage device, 122 Control program, 130 Cover body, 150 Chip conveyor, 200 Operation panel, 206 Display, 240A Drive unit, 240B Drive unit, 240C Drive unit, 241A Motor driver, 241B Motor driver, 241C Motor driver, 241D Motor driver, 241E Motor driver, 241F Motor driver, 241G Motor driver, 241H Motor driver, 242A Linear motor, 242B Linear motor, 242C Linear motor, 242D Linear motor, 242E Linear motor, 242F Linear motor, 242G Linear motor, 242H Linear motor, 243A Position detection mechanism, 243B Position detection mechanism, 243C Position detection mechanism, 243D Position detection mechanism, 243E Position detection mechanism, 243F Position detection mechanism, 243G Position detection mechanism, 243H Position detection mechanism, 250 Spindle, 260 Table, 270 Loader, 301 Control circuit, 302 ROM, 303 RAM, 304 Communication interface, 309 Internal bus, 320 Auxiliary storage device, 322 Control program, AR Machining area, H Through hole, RA section, RB section, RC section, RN section, th Predetermined threshold value, ΔT Predetermined time.

Claims

1. A machine tool equipped with a linear motor, The linear motor, includes a magnetic plate, and a slider provided with a plurality of coils, The slider is configured to be slidable on the magnetic plate by applying a magnetic field generated by applying a current to the plurality of coils to the magnetic plate, a detection unit for detecting the position of the slider, and a control device for controlling the machine tool, The control device, based on a command value related to the current, performs a process of driving the linear motor, and within a plurality of sections obtained by dividing the movable region of the slider, performs a process of integrating the command value for the section to which the position of the slider belongs, and in any one of the plurality of sections, based on the fact that the integrated value of the command value within a predetermined time exceeds a predetermined threshold value, outputs a predetermined command. A machine tool that executes the process.

2. The integrating process includes a process of integrating the command value for an adjacent section of the belonging section, The command value integrated for the adjacent section is smaller than the command value integrated for the belonging section. The machine tool according to claim 1.

3. The predetermined command includes a command for stopping the driving process. The machine tool according to claim 1 or 2.

4. The predetermined command includes a command for notifying a warning. The machine tool according to claim 1 or 2.

5. The machine tool further includes a spindle for rotatably holding a workpiece or a tool, The linear motor is used to drive the spindle. The machine tool according to claim 1 or 2.

6. The machine tool further includes a table for placing a workpiece, The linear motor is used to drive the table, and the machine tool according to claim 1 or 2.

7. The machine tool further includes a loader for conveying a member, The linear motor is used to drive the loader, and the machine tool according to claim 1 or 2.

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