Control device and machine tool

Abstract

To provide a control device and a machine tool that automatically execute washing processing according to an operation state of a pump.SOLUTION: A control device comprises: a sensor which is applied to a pump for pressure-feeding liquid in different directions according to normal rotation operation and reverse rotation operation, and detects an operation state of the pump when the pump pressure-feeds and discharges the liquid according to normal rotation operation; and a control unit which switches the pump to reverse rotation operation, if abnormality is determined to have occurred in the pump during normal rotation operation by comparing a detection value inputted from the sensor with a predetermined threshold value, in order to execute washing processing for washing the pump using back-flowing liquid.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present specification relates to a control device and a machine tool. [Background technology]

[0002] A known conventional cleaning liquid filtering device for machine tools (hereinafter simply referred to as a "cleaning liquid filtering device") is disclosed in Patent Document 1 below. This conventional cleaning liquid filtering device is connected to a cleaning liquid passage that supplies cleaning liquid in a tank to a cleaning nozzle, and is provided with a pressurizing path that uses air to pressurize the cleaning liquid passage, between the suction port of the pump and a filter arranged on the pump suction port side.

[0003] In this way, conventional cleaning liquid filtering devices can move the cleaning liquid present between the filter and the pump inlet toward the filter by supplying air from the pressure path to pressurize the cleaning liquid passage between the filter and the pump inlet. As a result, the cleaning liquid that has moved toward the filter flows in the opposite direction, thereby clearing clogging of the filter. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-160304 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional cleaning liquid filtration device described above, for example, an operator operates the device depending on the operating state of the pump to unclog the filter. In other words, in conventional cleaning liquid filtration devices, the operator must manually operate the device when performing maintenance on the pump at their discretion. Furthermore, if the frequency of maintenance, i.e., cleaning, performed by the operator is inappropriate, there is a risk of damage to the pump. Therefore, from the perspective of reducing the man-hours required for pump maintenance and ensuring an appropriate frequency of pump cleaning, it is desirable to automatically perform cleaning depending on the operating state of the pump.

[0006] An object of the present specification is to provide a control device and a machine tool that automatically executes a cleaning process in accordance with the operating state of a pump. [Means for solving the problem]

[0007] This specification discloses a control device that is applicable to a pump that pressurizes liquid in different directions by operating in forward and reverse directions, and that includes a sensor that detects the operating state of the pump when the pump pressurizes and discharges liquid by operating in forward direction, and a control unit that, when it determines that an abnormality has occurred in the pump during forward operation by comparing the detection value input from the sensor with a predetermined threshold, switches the pump to reverse operation and executes a cleaning process to clean the pump with the liquid flowing backward.

[0008] This allows the control device to automatically execute a cleaning process to clean the pump in accordance with the operating state of the pump detected by the sensor. By having the control device automatically and periodically execute the cleaning process in accordance with the operating state of the pump, it is possible to reduce the man-hours required for pump maintenance and ensure that the frequency of the cleaning process is appropriately maintained. This makes it possible to prevent damage to the pump and ultimately reduce the maintenance costs of equipment such as machine tools. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a side view for explaining the configuration of a machine tool including a pump for which a cleaning process is performed by a control device. [Figure 2] 2 is a diagram illustrating the configuration of a hydraulic circuit that includes the pump of FIG. 1 and is used to perform a cleaning process. FIG. [Figure 3] FIG. 3 is a hydraulic circuit diagram of FIG. 2. [Figure 4] FIG. 2 is a functional block diagram for explaining the configuration of the control device of FIG. [Figure 5] 4 is a flowchart of a cleaning processing program executed by the control device. DETAILED DESCRIPTION OF THE INVENTION

[0010] The control device and the machine tool will be described below with reference to the drawings. In this embodiment, a case will be described in which a control device provided in a machine tool forming a machining system controls the operation of a coolant supply device.

[0011] 1. Overall configuration of the processing system 10 As shown in FIG. 1 , the machining system 10 includes a base 20 and a machine tool 30 that is mounted on the base 20 and performs machining on a workpiece W. The machine tool 30 has a coolant supply device 50 that supplies coolant during machining. Note that, although the present embodiment illustrates a case in which one machine tool 30 is mounted on the base 20, it is also possible to mount a plurality of machine tools 30 on the base 20. The machining system 10 also includes an articulated robot 60 (hereinafter sometimes simply referred to as "robot 60") as an automatic workpiece transport device that loads the workpiece W before machining into the machine tool 30 and unloads the machined workpiece W from the machine tool 30.

[0012] 2. Machine tools 30 Machine tool 30 performs machining on workpiece W, which is the object to be machined, by rotating it or by fixing it so that it cannot rotate. Examples of machining include cutting workpiece W, grinding workpiece W, and drilling workpiece W. As shown in FIG. 1 , machine tool 30 includes a movable head 41, a headstock 42, a tool rest 43, a tool rest moving device 44, a machining chamber 45, a traveling chamber 46, an air blow device 47, and a control panel 48.

[0013] The machine tool 30 is also equipped with a coolant supply device 50 that supplies coolant when machining the workpiece W. Here, for example, when a plurality of machine tools 30 are installed on the base 20, the coolant supply device 50 can supply coolant to each of the machine tools 30.

[0014] The movable head 41 moves in the front-to-rear direction on rails (not shown) provided on the base 20 via a plurality of wheels 41a. The headstock 42 rotatably holds the workpiece W. The headstock 42 supports a spindle 42a, which is arranged horizontally along the Z-axis direction (front-to-rear direction), so that the spindle 42a can rotate around the Z-axis. A chuck 42b for holding the workpiece W is provided at the tip of the spindle 42a. The spindle 42a is rotationally driven by a servo motor 42d via a rotation transmission mechanism 42c.

[0015] The tool rest 43 is a device that holds cutting tools 43a and applies a feed motion to the cutting tools 43a. The tool rest 43 is a so-called turret-type tool rest (tool rest), and has a tool holding portion 43b to which a plurality of cutting tools 43a for cutting the workpiece W are attached. The tool rest 43 also has a rotation drive portion 43c that rotatably supports the tool holding portion 43b and can be positioned and fixed at a predetermined cutting position.

[0016] The tool table moving device 44 is a device that moves the tool table 43 and therefore the cutting tool 43a along the X-axis direction (up and down) and the Z-axis direction (front and back). The tool table moving device 44 has an X-axis driving device 44a that moves the tool table 43 along the X-axis direction, and a Z-axis driving device 44b that moves the tool table 43 along the Z-axis direction.

[0017] X-axis driving device 44a has an X-axis slider 44a1 attached to a column provided on movable head 41 so as to be slidable in the vertical direction, and a servo motor 44a2 for moving X-axis slider 44a1. Z-axis driving device 44b has a Z-axis slider 44b1 attached to X-axis slider 44a1 so as to be slidable in the front-rear direction, and a servo motor 44b2 for moving Z-axis slider 44b1.

[0018] The machining chamber 45 is a space for machining the workpiece W, and accommodates a chuck 42b and a tool stand 43 (cutting tool 43a, tool holder 43b, and rotary drive unit 43c). The machining chamber 45 is partitioned by a front wall 45a, a ceiling wall 45b, left and right walls, and a rear wall (none of which are shown in the figure). An entrance / exit 45a1 through which the workpiece W enters and exits is formed in the front wall 45a. The entrance / exit 45a1 is opened and closed by a shutter 45c driven by a motor (not shown). The open state (open position) of the shutter 45c is indicated by a solid line, and the closed state (closed position) is indicated by a two-dot chain line.

[0019] The travel chamber 46 is a space provided facing the entrance / exit 45a1 of the machining chamber 45. The travel chamber 46 is partitioned by a front wall 45a and a front panel 31. The robot 60 can travel inside the travel chamber 46. The air blow device 47 blows positive pressure air inside the machining chamber 45 onto the cutting tool 43a and the workpiece W before or during cutting processing.

[0020] Control panel 48 has, as its main components, a control device (for example, a PLC) that controls the operation of rotation drive unit 43c, tool table moving device 44, air blow device 47, etc. Control panel 48 is also capable of communicating with a control device 54 of coolant supply device 50, which will be described later, and outputs various information indicating the operating state of machine tool 30 to control device 54.

[0021] The control panel 48 is equipped with a display device (not shown) that can display to the operator the operating status (including abnormality warnings) of the machine tool 30 and the coolant supply device 50. The control panel 48 is also equipped with an input device (not shown) that allows the operator to input commands to the machine tool 30 and the coolant supply device 50.

[0022] 3. Coolant supply device 50 The coolant supply device 50 is a device that mainly supplies coolant liquid when machining a workpiece W in the machine tool 30. As shown in Figures 1, 2, and 3, the coolant supply device 50 includes a tank 51 as a first tank, a coolant pump 52 as a pump, supply piping 53, and a control device 54. As shown in Figures 2 and 3, the coolant supply device 50 also includes a coolant container Y that stores clean coolant liquid as a second tank, and a maintenance tool M that is used in manual maintenance work by an operator.

[0023] For the sake of explanation, this embodiment will exemplify a case in which the coolant supply device 50 supplies coolant to one machine tool 30. However, as described above, when multiple machine tools 30 are installed on the base 20, it is also possible for one coolant supply device 50 to supply coolant to each of the machine tools 30.

[0024] 3-1. Tank 51 Tank 51 stores coolant liquid in a circulable manner to be supplied toward the machining point of workpiece W and cutting tool 43a in machine tool 30. As shown in Fig. 2, the interior of tank 51 is divided by screen filter 51a into a first chamber R1 that stores coolant liquid pumped out and supplied by coolant pump 52 during machining in machine tool 30, and a second chamber R2 into which coolant liquid returned from machining chamber 45 and coolant liquid that flows back through coolant pump 52 during a cleaning process described below are discharged.

[0025] In this embodiment, the coolant collected in the second chamber R2 of the tank 51 is filtered by the screen filter 51a and then stored in the first chamber R1. As a result, foreign matter such as large chips has been removed by the screen filter 51a from the coolant stored in the first chamber R1, i.e., the coolant supplied to the machining chamber 45 of the machine tool 30 by the coolant pump 52.

[0026] 3-2. Coolant pump 52 The coolant pump 52 as a pump pumps coolant stored in the tank 51 in different directions depending on whether it is operating in forward or reverse rotation. The coolant pump 52 is disposed in a first chamber R1 of the tank 51, as shown in Fig. 2. As a result, during forward rotation, the coolant pump 52 draws up coolant from a strainer 52a disposed below, as indicated by the thick solid arrow in Fig. 2, and pressure-feeds the drawn-up coolant from a first port 52b via the supply piping 53 to the machine tool 30. The first port 52b is the discharge side from which the coolant pump 52 discharges coolant during forward rotation.

[0027] Here, supply pipe 53 opens inside machining chamber 45 of machine tool 30, and discharges and supplies coolant toward the machining point between workpiece W and cutting tool 43a (see FIG. 1). For this reason, supply pipe 53 is provided with a check valve 53a that only allows the flow of coolant from coolant pump 52 toward machining chamber 45 of machine tool 30. Supply pipe 53 is also provided with a pressure switch 53b that operates in response to the pressure P of the coolant discharged from coolant pump 52. Note that, because pressure switch 53b operates in response to the pressure P of the coolant supplied from coolant pump 52, it can also function as a sensor that detects the operating state of coolant pump 52.

[0028] Furthermore, when the coolant pump 52 is operating in the reverse direction, it pumps up the coolant liquid using a branch pipe 55 connected to the supply pipe 53, as shown by the thick dashed arrow in Figure 2. Here, the branch pipe 55 is provided with a stop valve 55a that is closed when the coolant pump 52 is operating in the forward direction and is open when the coolant pump 52 is operating in the reverse direction.

[0029] As a result, with the stop valve 55a switched to the open state, the coolant pump 52 operates in reverse to pump up the coolant liquid stored in the first chamber R1 through the branch pipe 55. The pumped up coolant liquid flows back through the supply pipe 53 and flows inside the coolant pump 52 from the first port 52b.

[0030] The coolant that has flowed inside the coolant pump 52 is then discharged to the discharge pipe 56 via the second port 52c, as indicated by the thick dashed arrow in Fig. 2. As a result, the coolant that has circulated in reverse inside the coolant pump 52 is discharged into the second chamber R2 of the tank 51 via the discharge pipe 56. The discharge pipe 56 is provided with a check valve 56a that only allows the coolant to flow from the coolant pump 52 toward the second chamber R2 of the tank 51.

[0031] 3, the coolant pump 52 of this embodiment includes a motor 81, a low-pressure pump 82 and a high-pressure pump 83 driven by the motor 81, a filter 84, and a relief valve 85. The motor 81 is driven by current supplied from a power supply (not shown). The current supplied to the motor 81 is monitored by a thermal relay or the like to prevent damage due to, for example, an overload.

[0032] The low-pressure pump 82 pumps up the coolant liquid stored in the first chamber R1 of the tank 51 through the strainer 52a and supplies the coolant liquid to the high-pressure pump 83 through a filter 84. The high-pressure pump 83 pressurizes the coolant liquid supplied through the filter 84 and sends it under pressure from the first port 52b to the supply pipe 53.

[0033] The filter 84 is, for example, a turbulence filter, and filters the coolant flowing from the low-pressure pump 82 to the high-pressure pump 83 when the coolant pump 52 is operating in the forward direction. Therefore, the filtering surface 84a of the filter 84 on the low-pressure pump 82 side removes foreign matter such as fine chips contained in the coolant stored in the first chamber R1 of the tank 51. The relief valve 85 appropriately limits the pressure of the coolant pumped from the high-pressure pump 83.

[0034] Here, when coolant pump 52 operates in the forward direction, motor 81 drives low-pressure pump 82 and high-pressure pump 83 to operate in the forward direction, and pressurized coolant liquid is discharged from first port 52b to supply pipe 53. As a result, coolant liquid is pressure-fed to machining chamber 45 of machine tool 30 via supply pipe 53.

[0035] Furthermore, when the coolant pump 52 operates in the reverse direction, the low-pressure pump 82 and the high-pressure pump 83 operate in the reverse direction due to the drive of the motor 81, and the coolant pumped up via the branch pipe 55 is supplied from the first port 52b toward the filter 84. In this case, when the coolant pump 52 operates in the reverse direction, the coolant pressurized mainly by the high-pressure pump 83 flows backward through the filter 84.

[0036] For this reason, when the coolant pump 52 is operating in the reverse direction, foreign matter adhering to the filtering surface 84a of the filter 84 is caused to flow toward the second port 52c along with the coolant. Therefore, the foreign matter adhering to the filtering surface 84a of the filter 84 is discharged into the second chamber R2 via the discharge pipe 56. Furthermore, when the coolant pump 52 is operating in the reverse direction, the reverse operation of the low-pressure pump 82 causes a portion of the coolant pumped up via the branch pipe 55 to be supplied toward the strainer 52a. For this reason, when the coolant pump 52 is operating in the reverse direction, the coolant passes through the strainer 52a and is discharged into the first chamber R1, thereby removing foreign matter adhering to the strainer 52a.

[0037] 3-3.Control device 54 4, the control device 54 has an operation status acquisition unit 541, an operation status determination unit 542, an operation control unit 543, a retry abnormality determination unit 544, and a stop control unit 545. Here, the operation status acquisition unit 541, the operation status determination unit 542, the operation control unit 543, the retry abnormality determination unit 544, and the stop control unit 545 form the "control unit" of the control device 54.

[0038] The operating state acquisition unit 541 acquires the operating state of the coolant pump 52 when the coolant pump 52 is operating in the normal direction to pump and discharge the coolant liquid. In this embodiment, the operating state of the coolant pump 52 in the normal direction is represented by the magnitude of the pressure P detected by a pressure sensor 57 provided in the supply pipe 53, as shown in FIG.

[0039] Therefore, in this embodiment, the operating state acquisition unit 541 acquires the pressure P detected by the pressure sensor 57 as the operating state of the coolant pump 52 in forward operation. Here, the pressure P detected by the pressure sensor 57 can be the pressure (positive pressure) of the coolant liquid discharged by the coolant pump 52 to the supply pipe 53, or the pressure (negative pressure) of the coolant liquid pumped by the coolant pump 52 from the tank 51.

[0040] The operating state of the coolant pump 52 in normal rotation can also be represented by, for example, the on or off state of the pressure switch 53b. In this case, the operating state acquisition unit 541 can acquire the on signal (or off signal) output from the pressure switch 53b as the operating state of the coolant pump 52 in normal rotation.

[0041] The operating state determination unit 542 compares the pressure P acquired by the operating state acquisition unit 541 with a preset threshold value Pb. Then, the operating state determination unit 542 determines whether the operating state of the coolant pump 52 is normal or abnormal based on the comparison between the pressure P and the threshold value Pb. Here, the threshold value Pb is a value that can be set arbitrarily, and is a value that is determined based on the pressure of the coolant liquid when it is sprayed onto the machining point in the machining chamber 45 of the machine tool 30, for example.

[0042] That is, when the detected pressure P is greater than the threshold value Pb, the coolant is being appropriately pumped from the coolant pump 52 to the supply pipe 53. In other words, the coolant pump 52 pumps up and pressurizes the coolant stored in the first chamber R1 of the tank 51 without causing clogging due to foreign matter in the strainer 52a and the filter 84, for example. Therefore, when the pressure P is greater than the threshold value Pb, the operating state determination unit 542 outputs a normal signal Sn to the operation control unit 543, which indicates that the operating state of the coolant pump 52 is normal.

[0043] Furthermore, if the detected pressure P is equal to or lower than the threshold value Pb, the coolant pump 52 is not properly pumping the coolant to the supply pipe 53. In other words, the coolant pump 52 is not able to pump up and sufficiently pressurize the coolant stored in the first chamber R1 of the tank 51, for example, because the strainer 52a and the filter 84 are clogged with foreign matter. Therefore, if the pressure P is equal to or lower than the threshold value Pb, the operating state determination unit 542 outputs an abnormality signal Sa to the operation control unit 543, indicating that the operating state of the coolant pump 52 is abnormal.

[0044] The operation control unit 543 operates the coolant pump 52 in the forward direction or in the reverse direction to perform a cleaning process, which will be described later, depending on the determination result by the operation state determination unit 542. That is, when the operation control unit 543 receives a normal signal Sn from the operation state determination unit 542, it outputs a normal rotation operation command Rc1 to the coolant pump 52 and mainly operates the coolant pump 52 in the forward direction. Note that the operation control unit 543 may periodically operate the coolant pump 52 in the reverse direction when not performing a cleaning process, in other words, even when the operation control unit 543 receives a normal signal Sn.

[0045] Furthermore, when the operation control unit 543 receives the abnormality signal Sa from the operation state determination unit 542, it outputs a reverse rotation operation command Rc2 to the coolant pump 52 to operate mainly the coolant pump 52 in the reverse direction. When performing a cleaning process, in other words, even when the operation control unit 543 receives the abnormality signal Sa, the operation control unit 543 may operate the coolant pump 52 in the forward direction as necessary.

[0046] When the number N of repetitions (i.e., retries) of switching the coolant pump 52 from reverse rotation to forward rotation as a cleaning process by the operation control unit 543 is equal to or greater than a predetermined number Nd, a retry abnormality determination unit 544 outputs a retry abnormality signal Sra to the stop control unit 545. Here, the predetermined number Nd is a value that can be set arbitrarily to 2 or greater, and is a value determined, for example, based on the cleaning effects obtained when various experiments are performed.

[0047] When the stop control unit 545 of this embodiment acquires the retry abnormality signal Sra from the retry abnormality determination unit 544, it outputs a stop command Rt to the coolant pump 52. As a result, the coolant pump 52 of this embodiment stops operating in the event of a retry abnormality. In addition, in response to the output of the stop command Rt, the stop control unit 545 outputs an abnormality alarm A to the control panel 48 of the machine tool 30 to notify that the coolant pump 52 has stopped.

[0048] Here, even if the cleaning process is repeatedly executed until the number of retries N reaches or exceeds the predetermined number of retries Nd, the operating state of the coolant pump 52 may not return to normal. In this case, it is highly likely that, for example, replacement of the filter 84 or strainer 52a of the coolant pump 52, replacement of the coolant liquid stored in the tank 51, cleaning of the inside of the tank 51, or manual maintenance using the maintenance tool M is required.

[0049] Therefore, based on the retry abnormality signal Sra, the retry abnormality determination unit 544 can output a replacement request Re, a cleaning request Rw, or a manual maintenance execution request Rm to the control panel 48 of the machine tool 30. This makes it possible to notify the operator, via a display device or the like provided on the control panel 48, of the need to replace the filter 84 or strainer 52a of the coolant pump 52, replace the coolant liquid stored in the tank 51, clean the inside of the tank 51, or perform manual maintenance.

[0050] 3-4. Maintenance Tool M The maintenance tool M is used by an operator to perform manual maintenance on the coolant pump 52 when the coolant pump 52 does not return to normal operation even after automatic cleaning processing by reverse operation of the coolant pump 52. Therefore, the maintenance tool M is usually stored, for example, near the machine tool 30 together with the coolant container Y, and is connected to the coolant supply device 50 when manual maintenance is performed.

[0051] 2 and 3, the maintenance tool M has a maintenance pipe M1 for supplying clean coolant liquid stored in a coolant container Y. The maintenance pipe M1 is provided with a coupler M2 for liquid-tight connection to a connection joint 53c provided on the supply pipe 53. The maintenance pipe M1 is provided with a check valve M3 that allows only clean coolant liquid to flow from the coolant container Y toward the connection joint 53c of the supply pipe 53.

[0052] When performing manual maintenance, an operator immerses one end of the maintenance pipe M1 in a coolant container Y that stores clean coolant liquid, and then liquid-tightly connects the coupler M2 at the other end to the connection joint 53c. Then, the operator manually (individually) operates an operation panel (not shown) provided on the control panel 48, for example, to reverse the coolant pump 52. As a result, in the maintenance tool M, the maintenance pipe M1 supplies clean coolant liquid from the coolant container Y to the supply pipe 53, i.e., the coolant pump 52, via the connection joint 53c, as shown by the thick dashed dotted arrow in FIG. 2.

[0053] The clean coolant flows through the first port 52b of the coolant pump 52 and is discharged from the second port 52c to the second chamber R2 of the tank 51 via the discharge pipe 56. Therefore, the clean coolant flows back through the filter 84 and strainer 52a of the coolant pump 52, removing foreign matter such as chips. An operator can change the time for which the clean coolant is allowed to flow back toward the coolant pump 52, the number of times the clean coolant is allowed to flow back, and other parameters based on, for example, experience. Therefore, when an operator performs manual maintenance, the coolant pump 52 may be more likely to return to normal operation than when the cleaning process is performed automatically.

[0054] 4. Operation of the coolant supply device 50 The control device 54 (more specifically, the "CPU"; the same applies below) starts executing the cleaning process program shown in Fig. 5 in step S100. Then, in step S101, the control device 54 performs predetermined operational preparations for operating the coolant supply device 50 (for example, checking the amount of coolant liquid stored in the tank 51), and completes preparations for operating the coolant supply device 50.

[0055] Next, in step S102, control device 54 (more specifically, operation control unit 543) outputs a reverse rotation operation command Rc2 to coolant pump 52 to operate coolant pump 52 in the reverse direction until operation time T reaches predetermined time Ts1. As a result, in coolant pump 52, before actually supplying coolant to machining chamber 45 of machine tool 30 (before machining is performed), coolant pump 52 can automatically clean coolant pump 52 by causing coolant pumped up via branch piping 55 to flow back from first port 52b to second port 52c. Then, after operating coolant pump 52 in the reverse direction for predetermined time Ts1, control device 54 (operation control unit 543) executes the step processing of step S103.

[0056] In step S103, the control device 54 (more specifically, the operation control unit 543) outputs a forward rotation operation command Rc1 to the coolant pump 52 to operate the coolant pump 52 in the forward direction. As a result, the coolant pump 52 switches from reverse rotation operation to forward rotation operation in response to receiving the forward rotation operation command Rc1, and continues the forward rotation operation. Then, after operating the coolant pump 52 in the forward direction, the control device 54 (operation control unit 543) executes the step processing of step S104.

[0057] In step S104, the control device 54 (more specifically, the operating state acquisition unit 541 and the operating state determination unit 542) determines whether the pressure P detected by the pressure sensor 57 is greater than a preset threshold value Pb. That is, in step S104, the control device 54 (operating state determination unit 542) determines whether the operating state of the coolant pump 52, which starts supplying coolant liquid, is normal.

[0058] Specifically, the operating state acquisition unit 541 acquires a pressure P representing the operating state of the coolant pump 52 from the pressure sensor 57. The operating state determination unit 542 compares the pressure P acquired by the operating state acquisition unit 541 with a threshold value Pb, and if the pressure P is greater than the threshold value Pb, in other words, if the coolant pump 52 is normal, the operating state determination unit 542 determines "Yes" and executes the step processing of step S105. On the other hand, if the pressure P acquired by the operating state acquisition unit 541 is equal to or less than the threshold value Pb, in other words, if the coolant pump 52 is abnormal, the operating state determination unit 542 determines "No" and executes the step processing of step S110 and subsequent steps.

[0059] In step S105, control device 54 (more specifically, operation control unit 543) continues the normal rotation operation of coolant pump 52, for example, based on communication with control panel 48, in synchronization with the start of a machining cycle in which machine tool 30 sequentially machines a plurality of workpieces W. As a result, coolant pump 52 supplies coolant liquid via supply piping 53 to the machining point between workpiece W and cutting tool 43a inside machining chamber 45 of machine tool 30. After continuing the normal rotation operation of coolant pump 52, control device 54 then executes the step processing of step S106. Note that the situation in which coolant pump 52 is operated in the normal rotation in step S105 occurs when it is determined in step S104 above and in step S112, described later, that the operating state of coolant pump 52 in the normal rotation operation is normal.

[0060] In step S106, control device 54 (more specifically, operating state acquisition unit 541 and operating state determination unit 542) determines whether or not pressure P detected by pressure sensor 57 is greater than preset threshold value Pb while machine tool 30 has started a machining cycle. That is, in step S106, control device 54 (operating state determination unit 542) determines whether or not the operating state of coolant pump 52 is normal while coolant liquid is being supplied toward machining chamber 45 of machine tool 30, in other words, while machine tool 30 is machining workpiece W.

[0061] Specifically, the operating state acquisition unit 541 acquires a pressure P representing the operating state of the coolant pump 52 from the pressure sensor 57. The operating state determination unit 542 compares the pressure P acquired by the operating state acquisition unit 541 with a threshold value Pb, and if the pressure P is greater than the threshold value Pb, in other words, if the coolant pump 52 is normal, the operating state determination unit 542 determines "Yes" and executes the step processing of step S107. On the other hand, if the pressure P acquired by the operating state acquisition unit 541 is equal to or less than the threshold value Pb, in other words, if the coolant pump 52 is abnormal, the operating state determination unit 542 determines "No" and executes the step processing of step S110 and subsequent steps.

[0062] In step S107, the control device 54 determines, for example, based on communication with the control panel 48, whether or not machining of one workpiece W by the machine tool 30 has been completed. That is, if machining of one workpiece W by the machine tool 30 has been completed, the control device 54 determines "Yes" and executes the step processing of step S108. On the other hand, if machining of one workpiece W by the machine tool 30 has not yet been completed, the control device 54 determines "No." Then, the control device 54 repeatedly executes the determination processing of step S106 until machining of one workpiece W by the machine tool 30 has been completed.

[0063] In step S109, the control device 54 determines whether or not the machining cycle has ended, for example, based on communication with the control panel 48. That is, if there is a next machining cycle, the control device 54 determines "No" and executes the step processing from step S105 to step S107. On the other hand, if the machining cycle has ended, that is, if machining has been completed for all workpieces W, the control device 54 determines "Yes." Then, the control device 54 executes the step processing of step S109.

[0064] In step S109, as the machining cycle by machine tool 30 ends, control device 54 (more specifically, operation control unit 543) outputs a reverse rotation operation command Rc2 to coolant pump 52 to operate coolant pump 52 in the reverse direction until operation time T reaches predetermined time Ts1. As a result, after machine tool 30 has performed machining, coolant pump 52 causes the coolant liquid pumped up via branch piping 55 to flow back from first port 52b to second port 52c.

[0065] That is, the control device 54 (operation control unit 543) can automatically clean the coolant pump 52 when the coolant pump 52 is not in use. After the control device 54 (operation control unit 543) operates the coolant pump 52 in the reverse direction for a predetermined time Ts1, the control device 54 (operation control unit 543) executes the step process of step S116, thereby ending the execution of the cleaning process program.

[0066] If it is determined in the determination process of step S104 or step S106 that the pressure P is equal to or less than the threshold value Pb (if the determination is "No"), the control device 54 executes the processes of steps S110 and onward. As a result, the control device 54 executes the cleaning process of the coolant pump 52.

[0067] In step S110, the control device 54 (more specifically, the operation control unit 543) outputs a reverse rotation operation command Rc2 to the coolant pump 52 to operate the coolant pump 52 in the reverse direction until the operation time T reaches a predetermined time Ts2. Here, the predetermined time Ts2 is set to be longer than the predetermined time Ts1. As a result, the coolant pump 52 causes the coolant pumped via the branch pipe 55 to flow backward from the first port 52b to the second port 52c until the predetermined time Ts2 has elapsed, thereby automatically cleaning the coolant pump 52. Then, after operating the coolant pump 52 in the reverse direction for the predetermined time Ts2, the control device 54 (the operation control unit 543) executes the step processing of step S111.

[0068] In step S111, the control device 54 (more specifically, the operation control unit 543) outputs a forward rotation operation command Rc1 to the coolant pump 52 to operate the coolant pump 52 in the forward direction. As a result, the coolant pump 52 switches from reverse rotation operation to forward rotation operation in response to receiving the forward rotation operation command Rc1, and continues the forward rotation operation. Then, after operating the coolant pump 52 in the forward direction, the control device 54 (operation control unit 543) executes the step processing of step S112.

[0069] In step S112, the control device 54 (more specifically, the operating state acquisition unit 541 and the operating state determination unit 542) determines whether or not the pressure P detected by the pressure sensor 57 is greater than a preset threshold value Pb when cleaning is performed by reverse rotation for the predetermined time Ts2 in step S110 and then forward rotation is performed in step S111. That is, in step S112, the control device 54 (operating state determination unit 542) determines whether or not the operating state of the coolant pump 52 has returned to normal from abnormal.

[0070] Specifically, the operating state acquisition unit 541 acquires a pressure P representing the operating state of the coolant pump 52 from the pressure sensor 57. The operating state determination unit 542 compares the pressure P acquired by the operating state acquisition unit 541 with a threshold value Pb, and if the pressure P is greater than the threshold value Pb, in other words, if the coolant pump 52 has returned to normal, the operating state determination unit 542 determines "Yes" and executes the process of each step from step S105 to step S109. On the other hand, if the pressure P acquired by the operating state acquisition unit 541 remains equal to or less than the threshold value Pb, in other words, if the coolant pump 52 remains abnormal, the operating state determination unit 542 determines "No" and executes the process of step S113.

[0071] In step S113, the control device 54 (more specifically, the retry abnormality determination unit 544) determines whether the number of times N of the series of repeated operations (i.e., retry operations) in which the reverse rotation operation in step S110 and the forward rotation operation in step S111 are performed is less than a predetermined number Nd (e.g., about 2 times). That is, if the number of times N of the retry operations is less than the predetermined number Nd, the retry abnormality determination unit 544 determines "Yes" to perform the retry operation again. As a result, the control device 54 (more specifically, the operation control unit 543) executes step S110 and step S111 again. Then, in step S112, the control device 54 (more specifically, the operation state determination unit 542) determines whether the operation state of the coolant pump 52 has returned to normal after the retry operation.

[0072] Furthermore, if the number of times N of retry operations is equal to or greater than the predetermined number Nd, the retry abnormality determination unit 544 determines "No" because there is little possibility that the operating state of the coolant pump 52 will return to normal even if a retry operation is performed again. Then, the control device 54 executes the step processing of step S114.

[0073] In step S114, the control device 54 (more specifically, the stop control unit 545) acquires the retry abnormality signal Sra output from the retry abnormality determination unit 544 in response to the "No" determination in step S113, and stops the coolant pump 52. That is, the stop control unit 545 outputs a stop command Rt to the coolant pump 52, and stops the coolant pump 52. As a result, the coolant pump 52 stops from its normal rotation operation in response to the acquisition of the stop command Rt.

[0074] Furthermore, as coolant pump 52 stops, stop control unit 545 outputs abnormality alarm A to control panel 48 of machine tool 30 to notify that coolant pump 52 has stopped. This causes control panel 48 to stop operation of machine tool 30, i.e., to stop the machining cycle. When stop control unit 545 outputs stop command Rt and abnormality alarm A in this way, control device 54 executes the step processing of step S115.

[0075] In step S115, the control device 54 (more specifically, the retry abnormality determination unit 544) outputs a replacement request Re for the filter 84, strainer 52a, and coolant liquid, a cleaning request Rw for the tank 51, or a manual maintenance execution request Rm to the control panel 48 of the machine tool 30. This notifies the worker performing work using the machine tool 30 of the need for replacement, cleaning, or manual maintenance. Then, after outputting the replacement request Re, cleaning request Rw, or execution request Rm, the control device 54 ends execution of the cleaning treatment program in step S116.

[0076] Here, if a replacement request Re is notified in step S115, the worker replaces the filter 84 or strainer 52a of the coolant pump 52, or replaces the coolant liquid stored in the tank 51. Also, if a cleaning request Rw is notified in step S115, the worker cleans the inside of the tank 51 and removes foreign matter such as chips present inside the tank 51.

[0077] Furthermore, when the execution request Rm is notified in step S115, the worker prepares the maintenance tool M and the coolant container Y and manually performs maintenance on the coolant pump 52. That is, the worker connects the maintenance piping M1 of the maintenance tool M to the supply piping 53 and manually operates (individually) the operation panel to reverse the coolant pump 52, thereby causing clean coolant liquid to flow backward from the coolant container Y inside the coolant pump 52. Then, the worker can manually perform maintenance of the coolant pump 52, i.e., the cleaning process, by appropriately changing the number of times and the time for which the coolant liquid is reversed, for example, based on experience, etc.

[0078] As can be understood from the above description, the control device 54 is applied to the coolant pump 52 that pressure-feeds coolant liquid in different directions by operating in a forward direction and in a reverse direction. The control device 54 includes a pressure sensor 57 that detects the operating state of the coolant pump 52 when the coolant pump 52 pressure-feeds and discharges coolant liquid by operating in a forward direction. The control device 54 also includes an operating state acquisition unit 541, an operating state determination unit 542, an operation control unit 543, a retry abnormality determination unit 544, and a stop control unit 545 that, when determining that an abnormality has occurred in the coolant pump 52 during forward rotation by comparing the pressure P, which is a detection value input from the pressure sensor 57, with a predetermined threshold value Pb, switch the coolant pump 52 to reverse operation and execute a cleaning process to clean the coolant pump 52 with the coolant liquid flowing backward.

[0079] This allows the control device 54 to automatically execute a cleaning process for cleaning the coolant pump 52 in accordance with the pressure P that indicates the operating state of the coolant pump 52, detected by the pressure sensor 57. The control device 54 automatically and periodically executes the cleaning process in accordance with the operating state of the coolant pump 52, thereby reducing the number of steps required to maintain the coolant pump 52 and ensuring an appropriate frequency for executing the cleaning process. This makes it possible to prevent damage to the coolant pump 52, and ultimately reduces the maintenance costs for equipment such as the machine tool 30.

[0080] 5. Variations 5-1. First variant In the embodiment described above, the control device 54 is provided as a separate unit from the control panel 48 of the machine tool 30. Alternatively, the control device 54 may be provided as an integral part of the control panel 48 of the machine tool 30.

[0081] In the above-described embodiment, the control device 54 is mounted on the machine tool 30 on which the coolant supply device 50 is provided. However, the control device 54 may be installed anywhere as long as it can receive a signal from the pressure sensor 57 (or pressure switch 53b) serving as a sensor and output a forward rotation operation command Rc1 or a reverse rotation operation command Rc2 to the coolant pump 52 serving as a pump. For example, the control device 54 may be installed in a factory separate from the factory in which the machine tool 30 and the coolant supply device 50 are installed. In this case, the signals from the sensors and the forward rotation operation command Rc1 and reverse rotation operation command Rc2 are transmitted and received, for example, via a network line. Therefore, the first modified example also provides the same effects as those of the above-described embodiment.

[0082] 5-2. Second variant In the embodiment described above, a manual maintenance execution request Rm is output after the abnormality alarm A is output. As a result, the worker performs manual maintenance on the coolant pump 52 using the maintenance tool M in accordance with the execution request Rm output in accordance with the operating state of the coolant pump 52. However, manual maintenance may also be performed periodically by the worker without relying on the execution request Rm that is automatically output.

[0083] Even in this case, the control device 54 can execute the cleaning process by automatically outputting the reverse rotation operation command Rc2 in accordance with the operating state of the coolant pump 52. This makes it possible to prevent clogging of the filter 84 and damage to the coolant pump 52, even in the case of the second modified example. Therefore, in the case of the second modified example, preventive manual maintenance of the coolant pump 52 is performed, and therefore the same effects as those of the above-described embodiment can be expected.

[0084] 5-3.Third modified example In the embodiment described above, the operation control unit 543 of the control device 54 performs the retry operation by the coolant pump 52 a plurality of times in the step processing of step S113 in the cleaning treatment program, with the number of retries N by the coolant pump 52 being less than the predetermined number of times Nd. However, the operation control unit 543 of the control device 54 can also execute the cleaning treatment program without performing the step processing of step S113.

[0085] That is, if the coolant pump 52 does not return to normal even though the cleaning process by reverse rotation has been performed for the predetermined time Ts2 (if "No" in step S112), the coolant pump 52 is abnormal, and operation of the coolant pump 52 is immediately stopped in step S114. This makes it possible to prevent damage to the coolant pump 52 even in the third modified example. Therefore, the same effects as those of the above-described embodiment can be expected in the third modified example as well.

[0086] 5-4.Fourth modified example In the above-described embodiment, the pressure sensor 57 that detects the pressure P is used as the sensor that detects the operating state of the coolant pump 52. As described above, it is also possible to use the pressure switch 53b that operates in response to the pressure P as the sensor that detects the operating state of the coolant pump 52.

[0087] However, detecting the operating state of the pump is not limited to detecting pressure or relying on pressure. For example, it is possible to detect the operating state of the pump by detecting vibrations generated when the pump is operating. In this case, for example, if the magnitude of the detected vibrations is equal to or less than a threshold, it is possible to determine that the operating state of the pump is normal, and if the magnitude of the vibrations is greater than the threshold, it is possible to determine that the operating state of the pump is abnormal. Therefore, even in the case of the fourth modified example, the same effects as those of the above-described embodiment can be obtained. [Explanation of symbols]

[0088] 30...machine tool, 42...headstock, 42a...spindle, 43...tool rest, 43a...cutting tool (tool), 48...control panel, 50...coolant supply device, 51...tank (first tank), 51a...screen filter, 52...coolant pump (pump), 52a...strainer, 52b...first port (discharge side), 52c...second port, 53...supply piping, 53a...check valve, 53b...pressure switch, 53c...connection joint, 54...control device, 541...operation status acquisition unit (control unit), 542...operation status determination unit (control unit), 543...operation control unit (control unit), 544...retry abnormality determination unit (control unit), 545...stop control unit (control unit), 55...branch piping, 55a...stop valve, 56...discharge Piping, 56a...check valve, 57...pressure sensor (sensor), 81...motor, 82...low pressure pump, 83...high pressure pump, 84...filter, 84a...filtration surface, 85...relief valve, M...maintenance tool, M1...maintenance piping, M2...coupler, M3...check valve, Y...coolant container, P...pressure, Pb...threshold value, Sn...normal signal, Sa...abnormal signal, Rc1...forward rotation command, Rc2...reverse rotation command, N...number of retry operations (number of retries), Nd...predetermined number of times, Sra...retry abnormal signal, Re...replacement request, Rw...cleaning request, Rm...manual maintenance execution request, Rt...stop command, A...abnormal alarm, T...operation time, Ts1...predetermined time, Ts2...predetermined time, W...work

Claims

1. It is applied to pumps that pump liquid in different directions by operating in forward and reverse directions. a sensor that detects the operating state of the pump when the pump is operating in the normal direction to pump and discharge the liquid; a control unit that, when it is determined that an abnormality has occurred in the pump during the forward rotation operation by comparing the detection value input from the sensor with a predetermined threshold, switches the pump to the reverse rotation operation and executes a cleaning process to clean a filter provided inside the pump with the liquid flowing backward; A control device comprising:

2. 2. The control device according to claim 1, wherein the control unit switches the pump to the reverse rotation operation during the cleaning process, thereby pressurizing the liquid through the discharge side that discharges the liquid during the forward rotation operation, and cleaning the filter with the liquid flowing backward.

3. The control device according to claim 1 or 2, wherein the control unit operates the pump in the reverse rotation mode until a predetermined time has elapsed during the cleaning process.

4. The control device according to any one of claims 1 to 3, wherein the control unit switches the pump to the forward operation after performing the cleaning process and determines whether the pump is normal by comparing the detection value with the threshold value.

5. The control device according to claim 4 , wherein the control unit operates the pump in the forward rotation mode when the pump is normal.

6. 5. The control device according to claim 4, wherein the control unit switches the pump to the normal operation after performing the cleaning process, and stops operation of the pump if it determines that the pump is abnormal by comparing the detection value with the threshold value.

7. The control device according to claim 6 , wherein the control unit stops operation of the pump when it determines that the pump is abnormal after performing the cleaning process multiple times.

8. the pump pumps the liquid from a tank in which the liquid is stored, The control device according to claim 1 , wherein the control unit operates the pump in the forward rotation operation and the reverse rotation operation to pump the liquid in the different directions.

9. The tank includes a first tank and a second tank, 9. The control device according to claim 8, wherein the control unit causes the pump to pump the liquid stored in the first tank by the forward rotation operation, and causes the pump to pump the liquid stored in the second tank by the reverse rotation operation during the cleaning process, thereby causing a reverse flow.

10. It is applied to pumps that pump liquid in different directions by operating in forward and reverse directions. the pump pumps the liquid from a tank in which the liquid is stored, a sensor that detects the operating state of the pump when the pump is operating in the normal direction to pump and discharge the liquid; a control unit that operates the pump in the forward rotation operation and the reverse rotation operation to pump the liquid in the different directions, and when it is determined that an abnormality has occurred in the pump during the forward rotation operation by comparing the detection value input from the sensor with a predetermined threshold, switches the pump to the reverse rotation operation and executes a cleaning process to clean the pump with the liquid flowing backward; Equipped with The control device, when the control unit determines that the pump is abnormal after performing the cleaning process multiple times, issues at least one of a request to clean the inside of the tank and a request to replace the liquid stored in the tank.

11. the sensor detects a pressure generated when the pump pumps the liquid by the normal rotation operation, The control device according to any one of claims 1 to 10, wherein the control unit compares the detected value with the threshold value and determines that the pump is abnormal if the detected value is equal to or less than the threshold value.

12. the pump includes a low-pressure pump and a high-pressure pump, and a filter provided between the low-pressure pump and the high-pressure pump, the filter filtering the liquid that flows from the low-pressure pump to the high-pressure pump by the normal rotation operation; The control device according to any one of claims 1 to 11, wherein the control unit executes the cleaning process to operate the pump in the reverse operation, and cleans the filter with the liquid that flows back.

13. The control device according to any one of claims 1 to 12, The machine tool is configured so that the pump pumps the coolant liquid by the normal rotation and discharges the coolant liquid toward the machining point between the workpiece and the tool that performs the machining.

14. The machine tool according to claim 13 , wherein the control unit executes the cleaning process before and after the workpiece is machined.

15. 15. The machine tool according to claim 13, wherein the machining is at least one of a cutting process for cutting the workpiece, a grinding process for grinding the workpiece, and a drilling process for drilling a hole in the workpiece.

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