Machine tool

Abstract

A machine tool according to one aspect of the present disclosure is provided with: a plurality of servo motors; a plurality of servo amplifiers that respectively drive the servo motors; and a control device that inputs a command value to the plurality of servo amplifiers according to a machining program, wherein the control device has a safety information acquisition unit that acquires safety information indicating the safety on excitation stop of the servo motors, and a stop control unit that, when the machining program is not running, stops the excitation of the servo motors indicated to be safe by the safety information.

Description

machine tools

[0001] The present invention relates to a machine tool.

[0002] In machine tools, multiple servo motors are operated in coordination to machine workpieces. Generally, servo motors are driven by current supplied from servo amplifiers that correspond one-to-one to each other. Even when the output shaft of a servo motor is not being displaced, it is excited, and the output is adjusted to match the rotational position with the target position at that time.

[0003] As described above, servo motors in machine tools are normally energized and consume power at all times. However, there has been proposed an exceptional technique for cutting off the power supply to the servo motor when an abnormality is detected in order to prevent the feed axis from colliding (interfering with other axes or the movement limit) in the event of a power outage or the like (see, for example, Patent Document 1).

[0004] JP 2014-96929 A

[0005] In recent years, there has been a growing demand for energy conservation, and further energy conservation in machine tools is being sought. Therefore, technology that can reduce the power consumption of servo motors is desired.

[0006] A machine tool according to one aspect of the present disclosure comprises a plurality of servo motors, a plurality of servo amplifiers that respectively drive the servo motors, and a control device that inputs command values ​​to the plurality of servo amplifiers in accordance with a machining program, wherein the control device has a safety information acquisition unit that acquires safety information that indicates safety regarding stopping excitation of the servo motors, and a stop control unit that stops excitation of the servo motors for which the safety information indicates safety when the machining program is not being executed.

[0007] FIG. 1 is a block diagram illustrating a configuration of a machine tool according to an embodiment of the present disclosure.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present disclosure will now be described with reference to the accompanying drawings. Fig. 1 is a schematic diagram showing the configuration of a machine tool 1 according to an embodiment of the present disclosure.

[0009] The machine tool 1 comprises a plurality of servo motors 11, 12, 13, 14, a plurality of servo amplifiers 21, 22, 23, 24 that drive the servo motors 11, 12, 13, 14 respectively, one or more ancillary devices 30 that are not servo-driven, driven members 41, 42, 43, 44, 45 that are driven by the servo motors 11, 12, 13, 14 or the ancillary devices 30 respectively, a plurality of status sensors 51, 52, 53, 54, 55, 56 that detect the safety of the servo motors 11, 12, 13, 14 against excitation stop, and a control device 60 that inputs command values ​​to the plurality of servo amplifiers 21, 22, 23, 24 according to a machining program.

[0010] The servo motors 11, 12, 13, and 14 may include a spindle motor that rotates the tool and workpiece relative to each other, a plurality of positioning axis motors that move the tool and workpiece relative to each other, a servo motor that drives a peripheral device such as a door, etc. In the simplified diagram of Fig. 1, the number of servo motors 11, 12, 13, and 14 and servo amplifiers 21, 22, 23, and 24 shown is four, but the actual number is not limited and is usually more than four.

[0011] The servo amplifiers 21, 22, 23, and 24 are provided in one-to-one correspondence with the servo motors 11, 12, 13, and 14, and supply excitation currents that excite the windings of the corresponding servo motors 11, 12, 13, and 14. The servo amplifiers 21, 22, 23, and 24 can be configured to adjust the currents input to the servo motors 11, 12, 13, and 14 so that the speeds of the servo motors 11, 12, 13, and 14 match the speeds indicated by command values ​​input from the control device 60.

[0012] The servo amplifiers 21, 22, 23, and 24 are each supplied with power from a power supply device 25. Primary breakers 211, 221, 231, and 241 operated by the control device 60 may be provided on electrical paths that supply power from the power supply device 25 to the servo amplifiers 21, 22, 23, and 24, respectively.

[0013] Furthermore, when a stop signal is input from the control device 60, the servo amplifiers 21, 22, 23, and 24 are configured to cut off the output and stop the excitation of the servo motors 11, 12, 13, and 14. The mechanism for stopping the excitation may be a secondary breaker capable of cutting off the electrical circuit connecting the main body of the servo amplifiers 21, 22, 23, and 24 to the servo motors 11, 12, 13, and 14.

[0014] Furthermore, the servo amplifiers 21, 22, 23, and 24 may be configured to stop communication depending on the value of the communication control signal input from the control device 60, and it is preferable that they are configured to reduce the communication speed depending on the communication control signal input from the control device 60.

[0015] The auxiliary device 30 is one or more devices that consume power, such as a door opening / closing motor that is not servo-driven, a hydraulic pump, a cooling fan, a refrigerator, an air compressor, lighting, a display device, etc. The auxiliary device 30 can be controlled by the control device 60 via, for example, a relay circuit (not shown) or the like.

[0016] The driven members 41, 42, 43, 44, and 45 are driven by servo motors 11, 12, 13, and 14 or ancillary devices 30. Specific examples of the driven members 41, 42, 43, 44, and 45 include a tool chuck, a workpiece holding table, and a door panel. The driven members 41, 42, 43, 44, and 45 may also include other servo motors 11, 12, 13, and 14 to perform multi-axis positioning.

[0017] The status sensors 51, 52, 53, 54, 55, and 56 may be configured to detect the operating status (position, posture, etc.) of the driven members 41, 42, 43, 44, and 45 or a manually operated safety cover. The status sensors 51, 52, 53, 54, 55, and 56 may also be sensors that confirm that no person or object is present in a specific space. The status sensors 51, 52, 53, 54, 55, and 56 may be, for example, photocells, limit switches, etc.

[0018] The control device 60 may be realized by one or more computer devices that include, for example, a memory, a processor (CPU), an input / output interface, a display, etc. and that execute an appropriate control program. Specifically, the control device 60 may be, for example, a numerical control device, a programmable logic controller, a personal computer, etc. The control device 60 includes a command value generating unit 61, a safety information acquiring unit 62, a stop control unit 63, a restart control unit 64, and an enable setting unit 65. These components of the control device 60 categorize the functions of the control device 60, and do not necessarily have to be clearly distinguishable in terms of physical configuration and program configuration.

[0019] The command value generating unit 61 generates command values ​​to be input to the servo amplifiers 21, 22, 23, and 24 based on the machining program. The command value generating unit 61 may be configured to correct the command values ​​to be input to the servo amplifiers 21, 22, 23, and 24 in consideration of feedback signals indicating the actual speeds of the servo motors 11, 12, 13, and 14.

[0020] The safety information acquisition unit 62 acquires one or more pieces of safety information indicating safety against excitation deactivation of the servo motors 11, 12, 13, and 14. Each piece of safety information indicates safety for one or more servo motors 11, 12, 13, and 14, and multiple pieces of safety information may indicate safety for the same servo motors 11, 12, 13, and 14. When multiple pieces of safety information indicate safety for the same servo motors 11, 12, 13, and 14, if all of the safety information have values ​​indicating safety, safety can be guaranteed even if excitation of the corresponding servo motors 11, 12, 13, and 14 is deactivated. "Safety against excitation deactivation" means that no harm is expected even if the driven members 41, 42, 43, and 44 descend due to a loss of torque against gravity, or the driven members 41, 42, 43, and 44 overshoot due to a loss of braking force. The safety information preferably includes the detected values ​​of the status sensors 51, 52, 53, 54, 55, and 56, and may further include information from the encoders of the servo motors 11, 12, 13, and 14, brake operation information from the servo motors 11, 12, 13, and 14 that have brakes, the status of manual switches operated by the user, etc.

[0021] When the machining program is not being executed, the stop control unit 63 stops excitation of the servo motors 11, 12, 13, and 14 for which the safety information indicates safety. In other words, the stop control unit 63 stops output of excitation current to the servo amplifiers 21, 22, 23, and 24 that drive the servo motors 11, 12, 13, and 14 for which it is determined that it is safe to stop excitation based on the safety information. This makes it possible to reduce power consumption of the servo motors 11, 12, 13, and 14 while the machining program is not being executed.

[0022] When the excitation of the servo motors 11, 12, 13, and 14 is stopped, the stop control unit 63 preferably displays a message indicating that the excitation has been stopped so that the user can confirm that the excitation has been stopped.

[0023] The stop control unit 63 may not only stop the output of excitation current from the servo amplifiers 21, 22, 23, and 24 that drive the servo motors 11, 12, 13, and 14, but may also cut off the supply of power to the servo amplifiers 21, 22, 23, and 24, that is, open the primary breakers 211, 221, 231, and 241. This makes it possible to further reduce power consumption.

[0024] The stop control unit 63 may stop or reduce the communication speed of the servo amplifiers 21, 22, 23, and 24 that drive the servo motors 11, 12, 13, and 14 for which the safety information indicates safety. This also reduces the power required for communication by the servo amplifiers 21, 22, 23, and 24.

[0025] The stop control unit 63 may cut off the power supply to the auxiliary device 30 previously linked to the servo motor 11, 12, 13, 14 in synchronization with the excitation stop of the servo motor 11, 12, 13, 14. Examples of devices that can cut off the power supply in synchronization with the servo motor 11, 12, 13, 14 include a display device that displays information about the servo motor 11, 12, 13, 14, lighting for improving the visibility of the servo motor 11, 12, 13, 14, driven members 41, 42, 43, 44, 45, etc., and a cooling fan that cools the servo motor 11, 12, 13, 14.

[0026] The restart control unit 64 monitors the detection values ​​of the status sensors 51, 52, 53, 54, 55, and 56 while the stop control unit 63 is stopping the excitation of the servo motors 11, 12, 13, and 14. When the restart control unit 64 determines, based on the detection values ​​of the status sensors 51, 52, 53, 54, 55, and 56, that stopping the excitation of the servo motors 11, 12, 13, and 14 could cause harm, the restart control unit 64 causes the stop control unit 63 to restart the excitation of the servo motors 11, 12, 13, and 14.

[0027] The activation setting unit 65 activates or deactivates the stop control unit 63 in accordance with an external signal. If the stop control unit 63 starts execution of a machining program while it has stopped the excitation of the servo motors 11, 12, 13, and 14, there is a possibility that a wait time will occur until the excitation of the servo motors 11, 12, 13, and 14 is resumed. Therefore, if the interval between executions of the machining program is short, a decrease in the availability rate can be prevented by deactivating the stop control unit 63 by an external signal from, for example, a management computer.

[0028] As described above, the machine tool 1 is equipped with a stop control unit 63 that stops the excitation of the servo motors 11, 12, 13, and 14 when the machining program is not being executed, thereby reducing the power consumption due to the excitation of the servo motors 11, 12, 13, and 14.

[0029] The following supplementary notes are further disclosed regarding the above-described embodiment and modified examples. (Supplementary Note 1) A machine tool (1) includes a plurality of servo motors (11, 12, 13, 14), a plurality of servo amplifiers (21, 22, 23, 24) that drive the servo motors (11, 12, 13, 14), respectively, and a control device (60) that inputs command values ​​to the plurality of servo amplifiers (21, 22, 23, 24) in accordance with a machining program, and the control device (60) has a safety information acquisition unit (62) that acquires safety information that indicates safety regarding the stop of excitation of the servo motors (11, 12, 13, 14), and a stop control unit (63) that stops excitation of the servo motors (11, 12, 13, 14) for which the safety information indicates safety when the machining program is not being executed.

[0030] (Supplementary Note 2) The stop control unit (63) may cut off the power supply to the servo amplifiers (21, 22, 23, 24) that drive the servo motors (11, 12, 13, 14) for which the safety information indicates safety.

[0031] (Supplementary Note 3) The stop control unit (63) may stop communication or reduce the communication speed of the servo amplifiers (21, 22, 23, 24) that drive the servo motors (11, 12, 13, 14) for which the safety information indicates safety.

[0032] (Supplementary Note 4) The machine tool (1) may further include state sensors (51, 52, 53, 54) that detect the operating states of the members (41, 42, 43, 44) driven by the servo motors (11, 12, 13, 14).

[0033] (Supplementary Note 5) The control device (60) may further include a restart control unit (64) that restarts excitation of the servo motors (11, 12, 13, 14) based on the detected values ​​of the state sensors (51, 52, 53, 54).

[0034] (Supplementary Note 6) The control device (60) may further include an enabling setting unit (65) that enables or disables the stop control unit (63) in accordance with an external signal.

[0035] (Supplementary Note 7) When the excitation of the servo motors (11, 12, 13, 14) is stopped, the stop control unit (63) may display that the servo motors (11, 12, 13, 14) are stopped.

[0036] (Supplementary Note 8) The stop control unit (63) may cut off the power supply to the other device (30) in synchronization with the stopping of excitation of the servo motors (11, 12, 13, 14).

[0037] 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 to these embodiments without departing from the gist of the present disclosure or the gist of the present disclosure derived from the content of the claims and their equivalents.

[0038] For example, in the machine tool according to the present disclosure, ancillary devices are not required, and a status sensor that detects the operating status of a driven member that is not driven by a servo motor is also an optional configuration. Furthermore, the machine tool according to the present disclosure may be provided with other configurations for realizing energy conservation, such as activating a screen saver or turning off the power to a pump, independent of the stop control unit.

[0039] REFERENCE SIGNS LIST 1 Machine tool 11, 12, 13, 14 Servo motor 21, 22, 23, 24 Servo amplifier 211, 221, 231, 241 Primary breaker 212, 222, 232, 242 Relay 25 Power supply device 30 Auxiliary device 41, 42, 43, 44, 45 Driven member 51, 52, 53, 54, 55, 56 Status sensor 60 Control device 61 Command value generation unit 62 Safety information acquisition unit 63 Stop control unit 64 Restart control unit 65 Activation setting unit

Claims

1. a control device that inputs command values ​​to the servo amplifiers according to a machining program; The control device includes: a safety information acquisition unit that acquires safety information indicating safety with respect to the excitation stop of the servo motor; a stop control unit that stops excitation of the servo motor when the safety information indicates that the servo motor is safe when the machining program is not being executed; A machine tool having the above structure.

2. 2. The machine tool according to claim 1, wherein the stop control unit cuts off power to the servo amplifier that drives the servo motor for which the safety information indicates safety.

3. 3. The machine tool according to claim 1, wherein the stop control unit stops communication or reduces a communication speed of the servo amplifier that drives the servo motor for which the safety information indicates safety.

4. The machine tool according to claim 1 or 2, further comprising a condition sensor for detecting an operating condition of a member driven by the servo motor.

5. 5. The machine tool according to claim 4, wherein the control device further comprises a restart control unit that restarts excitation of the servo motor based on a detection value of the state sensor.

6. The machine tool according to claim 1 or 2, wherein the control device further comprises an enabling setting unit that enables or disables the stop control unit in accordance with an external signal.

7. 3. The machine tool according to claim 1, wherein the stop control unit displays, when excitation of the servo motor is stopped, that the servo motor is stopped.

8. 3. The machine tool according to claim 1, wherein the stop control unit cuts off power supply to other devices in synchronization with the excitation stop of the servo motor.