JP2011140111A - Machine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a machine tool which surely prevents the drop of a driving pressure to obtain a stable drive in the case where a fluid used for the different purpose from the drive for an actuator is also utilized for the drive for the actuator, and contributes to the cost reduction, miniaturization and energy saving for the device. <P>SOLUTION: The machine tool includes a coolant pump 61 for supplying coolant liquid to a predetermined flow passage, a discharge port 64 for discharging the coolant liquid supplied to the flow passage to the outside, the actuator 20a which is mounted to the tip end part of a second flow passage L5 branched from the flow passage and driven by the pressure of the coolant liquid supplied through the second flow passage L5, a check valve 67 which is provided in the second flow passage L5 to prevent back-flow of the coolant liquid, and a pressure booster 68 provided between the check valve 67 and the actuator 20a in the second flow passage L5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a machine tool.

  In the field of machine tools, hydraulic drive for various actuators is employed. In this case, a shortage of hydraulic pressure between the hydraulic fluid supply source (hydraulic pump) and the actuator becomes a problem. Therefore, a clamp cylinder, a switching valve for switching the flow direction of the pressurized liquid to reciprocate the clamp cylinder, a pilot check valve provided on a line between the switching valve and the rod side of the clamp cylinder, and the clamp cylinder There is known a clamping device having a pressure-increasing cylinder for supplying pressurized liquid at the time of clamping by (see Patent Document 1).

  There is also known a hydraulic balance device in which a pilot check valve is provided in a pipe line connecting the hydraulic pump and the hydraulic cylinder, and a gas pressure accumulator is connected to the pipe line connecting the pilot check valve and the hydraulic cylinder (Patent Literature). 2).

JP 2002-174201 A JP-A-6-39616

  Here, when a fluid originally used for a purpose different from the driving of the actuator is also used for driving the actuator, the pressure drop between the fluid supply source and the actuator becomes very large, and the driving It becomes difficult to maintain the pressure required for The above-mentioned documents do not deal with such a large pressure drop when a fluid used for a purpose different from the driving of the actuator is also used for driving the actuator. Further, conventionally, in order to compensate for such a large pressure drop, it is necessary to add a dedicated drive source (such as a hydraulic pump) as a configuration in order to stabilize the drive of the actuator. However, the addition of such a dedicated drive source leads to an increase in the cost and enlargement of the machine tool.

  Even if the pressure drop required for driving the actuator is compensated, if the period during which the compensation can be continued is short, the actuator may not be driven stably over a period desired by the operator.

The present invention has been made to solve at least one of the above-mentioned problems, and reliably prevents a decrease in driving pressure when a fluid used for a purpose different from the driving of the actuator is also used for driving the actuator. A machine tool that realizes stable driving and contributes to cost reduction, downsizing, and energy saving of the apparatus is provided.
Further, the present invention provides a machine tool capable of stably performing the compensation over a necessary period when compensating for a decrease in driving pressure on the actuator.

  One aspect of the present invention is a machine tool, a coolant pump that supplies coolant liquid to a predetermined flow path, a discharge port that discharges the coolant liquid supplied to the flow path to the outside, and the flow path Is attached to the tip of the second flow path branched from the actuator, and is driven by the pressure of the coolant liquid supplied through the second flow path, and prevents the coolant liquid from flowing backward provided in the second flow path. And a pressure intensifier provided between the check valve and the actuator in the second flow path.

  According to the present invention, the coolant liquid supplied from the coolant pump to the flow path is discharged from the discharge port, and at the same time, supplied to the actuator at the tip of the second flow path. In this case, since the discharge port is open to the outside, the pressure in the second flow path will greatly decrease unless any countermeasure is taken. However, a check valve for preventing the backflow of the coolant liquid is provided in the second flow path, and a pressure intensifier is provided between the check valve and the actuator. Therefore, even if there is some leakage (back flow) of the coolant from the check valve, the pressure applied to the actuator is accurately maintained. Further, according to the present invention, after the check valve is closed, even if the operation of the coolant pump is stopped, the pressure applied to the actuator is maintained, so that energy required for the operation of the machine tool can be saved. Furthermore, since it is not necessary to add a dedicated drive source (such as a hydraulic pump) as a configuration in order to stabilize the pressure supply to the actuator, it is possible to contribute to cost reduction and downsizing of the machine tool.

  The pressure intensifier includes a first cylinder part, a second cylinder part having a smaller cross-sectional area than the first cylinder part, one end communicating with the first cylinder part, and the other end communicating with the second flow path, A pressure-increasing cylinder having a cylinder part and a movable body that can slide inside the second cylinder part, and having a pressure-increasing cylinder that causes the pressure in the second cylinder part to act on the second flow path. . In the machine tool, after the supply of the coolant liquid from the coolant pump to the flow path and the second flow path is started, the pressure intensifier increases the pressure with the moving body farthest from the other end. The pressure in the second cylinder part may be increased by applying pressure in the cylinder. According to the said structure, the capacity | capacitance of a 2nd cylinder part can be fully used for the pressure compensation (compensation with respect to the pressure drop by the leakage of the coolant etc. from a check valve) in a 2nd flow path, and is suitable.

  Another aspect of the present invention is a machine tool, a coolant pump that supplies coolant liquid to a predetermined flow path, and a coolant liquid that is attached to the tip of the flow path and supplied via the flow path An actuator driven by the pressure of the pressure, a check valve provided in the flow path for preventing the back flow of the coolant, and an increase in pressure in the cylinder acting on the flow path between the check valve and the actuator. A pressure cylinder and a replenishment circuit for supplying a coolant liquid into the pressure increasing cylinder are provided.

  According to this configuration, since the coolant liquid is supplied (supplemented) to the pressure increasing cylinder by the replenishing circuit, pressure compensation for the flow path between the check valve and the actuator by the pressure increasing cylinder is continued. That is, it is possible to stably compensate for the decrease in the driving pressure with respect to the actuator over a period in which the compensation is necessary. In this configuration, the pressure increasing cylinder includes a first cylinder part, a second cylinder part having a smaller cross-sectional area than the first cylinder part, one end communicating with the first cylinder part, and the other end connected to the flow path. And a movable body that can slide inside the first cylinder part and the second cylinder part, and causes the pressure increase in the second cylinder part to act on the flow path.

  With some leakage of the coolant liquid from the check valve or the like, the coolant liquid in the second cylinder part flows out from the other end to the flow path side, and the amount of the coolant liquid in the second cylinder part decreases. Therefore, the replenishment circuit may be configured to supply the coolant liquid into the second cylinder part when the amount of the coolant liquid in the second cylinder part is reduced to a predetermined amount. That is, since the coolant liquid is replenished into the second cylinder part by the replenishment circuit at a timing when the decrease of the coolant liquid in the second cylinder part proceeds by a predetermined amount, the pressure compensation is reliably continued.

  The machine tool includes detection means for detecting that the moving body is closest to the other end, and the replenishment circuit is configured to detect that the moving body is closest to the other end by the detection means. In addition, the coolant liquid may be supplied into the second cylinder part. According to this configuration, when the moving body is closest to the other end (when the pressure compensation by the pressure increasing cylinder is about to end once), the coolant liquid is replenished into the second cylinder portion by the replenishment circuit. The pressure compensation is reliably continued.

  The machine tool may determine that there is an abnormality when the interval at which the replenishment circuit supplies the coolant liquid is shorter than a predetermined set time. According to this configuration, since it is determined that an abnormality occurs when the time for one pressure compensation by the pressure increasing cylinder to continue is shorter than usual, the speed at which the coolant fluid in the second cylinder portion decreases is faster than usual (coolant This contributes to the discovery of abnormal situations such as liquid leaks.

  The machine tool includes an electromagnetic valve disposed at a position closer to the coolant pump than the check valve in the flow path, and a branch from the position closer to the coolant pump than the electromagnetic valve in the flow path. A discharge passage for discharging liquid, a first pressure adjusting means capable of adjusting a pressure in the flow passage on the coolant pump side relative to the electromagnetic valve, and a flow passage on the distal end side from the electromagnetic valve It is good also as a structure provided with the 2nd pressure adjustment means which can adjust an internal pressure. According to this configuration, the pressure in the discharge flow path is independently adjusted by the first pressure adjusting means and the pressure for driving the actuator is independently adjusted by the second pressure adjusting means, with the electromagnetic valve as a boundary. can do.

  Furthermore, the machine tool may be configured to include third pressure adjusting means capable of adjusting the pressure applied to the flow path between the check valve and the actuator by the pressure increasing cylinder. According to this configuration, the pressure adjusted by the second pressure adjusting means and the pressure acting on the flow path between the check valve and the actuator can be matched by the pressure increasing cylinder, and as a result, the actuator is driven. The pressure can be kept at the desired value.

  The actuator may open and close a gripping tool used for gripping the workpiece by the pressure of the coolant liquid. According to this configuration, since the pressure of the coolant liquid applied to the actuator is maintained, the gripping force is maintained when the actuator is driven and the gripping tool is closed, and the workpiece can be securely gripped.

  The technical idea of the present invention can be realized by means other than machine tools. For example, it is possible to grasp an invention of a method having processing steps executed by each configuration of the machine tool described above, and an invention of a program for controlling each configuration of the machine tool described above to realize each processing step.

It is the figure which showed schematic structure of NC lathe. It is the figure which showed the circuit diagram of the hydraulic control system arrange | positioned by NC lathe. It is the figure which showed an example of the holding tool. It is the figure which showed the other example of the holding tool. It is the figure which showed the other example of the circuit diagram of the hydraulic control system arrange | positioned at NC lathe. It is the figure which illustrated the sensor attached to the pressure increase cylinder. It is the figure which showed the other example of the circuit diagram of the hydraulic control system arrange | positioned at NC lathe.

Embodiments of the present invention will be described with reference to the drawings.
First embodiment:
FIG. 1 illustrates a schematic configuration of an NC (Numerical Control) lathe 100 according to this embodiment from one side. The NC lathe 100 is a kind of machine tool. The housing 100a of the NC lathe 100 houses the machining chamber 30, the coolant liquid tank 40, and the like. In the machining chamber 30, roughly, a headstock 10, a tool headstock 12, an automatic tool changer (ATC) 14, a tool stage 16, a tool magazine 18, and an intermediate station 21 are in predetermined positions, respectively. It is arranged. In the example shown in FIG. 1, the coolant liquid tank 40 is provided below the processing chamber 30 and stores therein coolant liquid as cutting oil. However, the coolant liquid tank 40 may exist outside the casing 100a.

  The NC lathe 100 includes an NC device 50 outside (but may be inside) the casing 100a. The NC device 50 is mainly composed of a computer, and further includes a display (not shown) as a display screen for the user and an operation receiving unit (not shown) such as a button for receiving an operation from the user. The NC device 50 sends commands to the components such as the head stock 10, the tool head stock 12, the ATC 14, the tool stock 16, the tool magazine 18, and the intermediate station 21 according to a predetermined machining program. The position and operation state (movement, rotation, turning, etc.) of each component can be individually numerically controlled. The NC device 50 can control the operation of each switching valve (solenoid valve), hydraulic pump, and the like, which will be described later.

  The headstock 10 has a main shaft 11 facing the Z-axis direction, and performs rotation control of the main shaft 11 (rotational speed control or rotation angle control called C1 axis control). In the example shown in FIG. 1, the Z-axis is directed in the left-right direction (horizontal direction). The main shaft 11 can grip a workpiece W as a processing target by a chuck 11a at the tip thereof.

  The tool spindle stock 12 has a tool spindle 13. In the initial position shown in FIG. 1, the tool spindle stock 12 has its axis directed in the vertical direction (X-axis direction). The tool spindle stock 12 performs rotation control around the axis of the tool spindle 13 (rotational speed control or rotation angle control called C2 axis control). The tool head stock 12 can move in the respective axial directions of Z, which is the axial direction of the spindle 11, and X, X, which are advance and retreat directions of the tool 19 with respect to the workpiece W, and Y which is orthogonal to Z. The Y-axis direction shown in FIG. 1 is precisely a direction perpendicular to the paper surface. Furthermore, the tool head stock 12 can control the turning angle (B-axis control) about the Y-axis. In other words, the tool head stock 12 can turn on a plane perpendicular to the Y-axis direction.

  The ATC 14 holds the tool 19 used for machining the workpiece W held by the spindle 11 with respect to the tool spindle 13 of the tool spindle table 12 at the initial position, and the grip used for holding the workpiece W before or after the predetermined machining. A tool (chuck) 20 can be appropriately mounted, and the mounted tool 19 and gripping tool 20 can be detached from the tool spindle 13. Although simplified in FIG. 1, a plurality of types of tools 19 and gripping tools 20 are mounted on the tool magazine 18. For example, the ATC 14 acquires the tool 19 and the like from the tool magazine 18 by the turning unit 15, and uses the acquired tool 19 and the like to the tool spindle 13 by the turning operation of the turning unit 15 (in the example shown in FIG. 1, the turning operation in the horizontal plane). The tool is aligned and mounted on the tool spindle 13. Further, the ATC 14 removes the tool 19 and the like from the tool spindle 13 by the turning unit 15 and turns the turning unit 15 to return the removed tool 19 and the like to the tool magazine 18 side. An intermediate station 21 is interposed between the ATC 14 and the tool magazine 18. The intermediate station 21 realizes delivery of the tool 19 and the like from the tool magazine 18 side to the ATC 14 side and delivery of the tool 19 and the like from the ATC 14 side to the tool magazine 18 side.

  The tool table 16 includes a tool 17 used for processing the workpiece W gripped by the spindle 11 and the workpiece W gripped by the gripping tool 20. In the example of FIG. 1, the tool table 16 is disposed below the main shaft 11. A so-called turret is formed on the tool table 16. The turret is provided with a plurality of surfaces, and a tool 17 is provided on each surface. The tool 17 may be a fixed tool or a rotary tool. In the example of FIG. 1, the tool 17 protrudes toward the X-axis direction. The tool 17 is disposed on a plane that includes the axis of the main shaft 11 and is perpendicular to the Y-axis direction. In such a situation, the tool table 16 can move in the X-axis direction and the Z-axis direction. Further, the tool table 16 may be movable in the Y-axis direction.

  Although omitted in FIG. 1, a coolant liquid discharge nozzle is disposed in the housing 100 a in the vicinity of the machining position with respect to the workpiece W (for example, a predetermined position in the vicinity of the tool 17). During machining of the workpiece W according to the machining program, coolant liquid is appropriately discharged from the nozzle. The coolant liquid is effective for lubrication, cooling, chip removal, etc. during processing. In this embodiment, such coolant liquid can be supplied also to the tool spindle 13 side, and the hydraulic pressure of this coolant liquid is used as a drive source for opening and closing the gripping tool 20 attached to the tool spindle 13.

  FIG. 2 illustrates a circuit diagram of a hydraulic control system disposed in the NC lathe 100. As shown in FIG. 2, a pipe L <b> 1 for supplying the coolant liquid is formed from the coolant liquid tank 40, and the coolant liquid (high pressure coolant liquid) pressurized by the hydraulic pump (coolant pump) 61 is provided. It is sent out into the pipe line L1. The pipe line L <b> 1 is piped so that the end thereof returns to the coolant liquid tank 40. Further, a relief valve 62 and a pressure gauge 63 are provided on the pipe line L1 for maintaining the hydraulic pressure in the circuit at a predetermined value.

  From the middle of the pipe line L1, the pipe line L2 is branched and formed, and a first switching valve 65 is provided at the end of the pipe line L2. The first switching valve 65 is an electromagnetic valve and is connected to the pipe line L2 at its P port. The T port of the first switching valve 65 is connected to a pipe line L11 which is a return flow path to the coolant liquid tank 40. The A port of the first switching valve 65 is connected to a pipeline whose end is blocked, and the B port of the first switching valve 65 is connected to a pipeline L3. The end of the pipe L3 is a discharge port 64. The discharge port 64 is a nozzle port for discharging the coolant liquid described above, and is open to the outside. That is, in the NC lathe 100, the flow path of the coolant liquid can be switched by controlling on / off of the solenoid of the first switching valve 65. Specifically, by connecting the P port and the B port of the first switching valve 65 and switching to the state where the T port and the A port are connected, the coolant liquid flows from the pipe line L2 to the pipe line L3. It discharges with respect to the said process position from the exit 64. FIG. Therefore, the flow path formed by the pipe lines L1, L2, and L3 corresponds to the predetermined flow path in claim 8 of the claims.

  In the pipeline L1, the pipeline L4 is further branched and formed, and a second switching valve 66 is provided at the tip of the pipeline L4. The second switching valve 66 is also an electromagnetic valve, and is connected to the pipeline L4 at its P port. The T port of the second switching valve 66 is connected to the pipeline L11. The A port of the second switching valve 66 is connected to the pipeline L6 whose end is blocked, and the B port of the second switching valve 66 is connected to the pipeline L5. The pipe line L5 extends to the tool spindle 13, and an actuator 20a is attached to the tip of the pipe line L5. The actuator 20a is built in the gripping tool 20, and is a mechanism for opening and closing the gripping tool 20 by the hydraulic pressure of the coolant liquid. The actuator 20a is, for example, a cylinder incorporating a piston and a spring.

  In the pipe line L5, a check valve 67 for preventing the backflow of the coolant liquid is provided. The check valve 67 is a pilot check valve. Further, in the pipe line L5, a pressure intensifier 68 is provided between the check valve 67 and the tip. That is, as shown in FIG. 2, when the gripper 20 (actuator 20a) is mounted on the tool spindle 13, the pressure intensifier 68 is interposed between the check valve 67 and the actuator 20a. The flow path formed by the pipe lines L4 and L5 corresponds to the second flow path in the claims. In the NC lathe 100, by controlling on / off of the solenoid of the second switching valve 66, the P port and the B port are connected, and the T port and the A port are switched to a connected state. The liquid flows from the line L4 to the line L5. The coolant liquid flowing into the pipe line L5 passes through the check valve 67 and is supplied to the actuator 20a. The actuator 20a closes the gripping tool 20 when the coolant is supplied and is in a pressurized state.

  On the other hand, in the NC lathe 100, when the solenoid of the second switching valve 66 is controlled to be turned on and off, the P port and the A port are connected and the T port and the B port are connected to each other. The pressure is established in the pipe line L6. In this case, the check valve 67 is opened by the pressure generated in the pipe L6, and the backflow of the coolant liquid is allowed (the coolant liquid flows out from the pipe L5 to the pipe L11). The actuator 20a opens the gripping tool 20 when the coolant liquid thus flows out of the pipe line L5 and is in a reduced pressure state.

  As described above, the discharge port 64 is open to the outside. Therefore, under a situation where the coolant liquid is supplied to the discharge port 64 (a situation where the pipeline L2 and the pipeline L3 are connected), the hydraulic pressure in each pipeline after the hydraulic pump 61 is greatly reduced. In this case, if no countermeasure is taken on the second flow path, the hydraulic pressure in the second flow path, that is, the pipes L4 and L5, is greatly reduced, and the gripping force of the gripping tool 20 by the actuator 20a is reduced. In the present embodiment, as described above, the check valve 67 is provided in the pipe line L5, thereby preventing the backflow of the coolant liquid when the coolant liquid is supplied to the pipe line L5, and the hydraulic pressure between the check valve 67 and the actuator 20a. The decline is prevented. Furthermore, in this embodiment, as described above, the pressure increaser 68 is provided between the check valve 67 and the actuator 20a to compensate for a decrease in hydraulic pressure due to leakage of the coolant liquid from the check valve 67.

  The pressure booster 68 includes a pressure boosting cylinder 68a, a third switching valve 68b, a pressure supply source 68c, and a tank 68d. The pressure increasing cylinder 68a has a first cylinder part 68a1 and a second cylinder part 68a2. The second cylinder part 68a2 has a smaller cross-sectional area of the cylinder than the first cylinder part 68a1. The second cylinder portion 68a2 has one end communicating with the first cylinder portion 68a1 and the other end communicating with a predetermined position between the check valve 67 and the actuator 20a on the pipe L5. A moving body including a first piston 68a3, a second piston 68a5, and a rod 68a4 connecting the first piston 68a3 and the second piston 68a5 is accommodated in the pressure increasing cylinder 68a. The moving body is slidable in the pressure increasing cylinder 68a. The diameter of the first piston 68a3 corresponds to the inner diameter of the first cylinder portion 68a1. The first piston 68a3 divides the inside of the first cylinder portion 68a1 into a first chamber 68a6 and a second chamber 68a7. The diameter of the second piston 68a5 corresponds to the inner diameter of the second cylinder portion 68a2. When the second piston 68a5 moves back and forth in the second cylinder part 68a2, the volume of the third chamber 68a8 in the second cylinder part 68a2 changes. The coolant liquid flows into the third chamber 68a8 from the pipe line L5.

  The pressure supply source 68c supplies a pressurized fluid (compressed air or pressure oil) through the line L7. Here, the pressure supply source 68c supplies pressure oil. A third switching valve 68b is provided at the tip of the pipe line L7. The third switching valve 68b is also an electromagnetic valve and is connected to the pipe line L7 at the P port. The T port of the third switching valve 68b is connected to the pipe L9, and the pipe L9 is connected to the tank 68d. The A port of the third switching valve 68b is connected to the first chamber 68a6 of the first cylinder portion 68a1 through the pipe line L8. The B port of the third switching valve 68b is connected to the second chamber 68a7 of the first cylinder portion 68a1 via the pipe line L10.

In such a configuration, in the NC lathe 100, when the workpiece 20 is gripped by closing the gripping tool 20 mounted on the tool spindle 13 in parallel with the discharge of the coolant liquid from the discharge port 64, the following sequence is performed. Execute.
First, the pressure intensifier 68 moves (retreats) the moving body to a position farthest from the other end of the second cylinder portion 68a2. The pressure intensifier 68 connects the P port and the B port and switches to the state in which the T port and the A port are connected by controlling on / off of the solenoid of the third switching valve 68b, for example. Then, pressure oil is supplied from the pressure supply source 68c to the second chamber 68a7, and the moving body moves backward. As a result, the volume of the first chamber 68a6 is minimized, and the volume of the third chamber 68a8 is the maximum volume that the third chamber 68a8 can take in the second cylinder portion 68a2. Next, the NC lathe 100 switches the state in which the pipe L2 and the pipe L3 are connected by controlling on / off of the solenoid of the first switching valve 65, and turns on / off the solenoid of the second switching valve 66. By switching off, the state is switched to the state in which the pipe line L4 and the pipe line L5 are connected, and the supply of the coolant liquid from the hydraulic pump 61 to the discharge port 64 and the actuator 20a is started.

  The pressure intensifier 68 is connected to the line L7 and the line L8 by controlling on / off of the solenoid of the third switching valve 68b after a lapse of a predetermined time after the coolant liquid supply is started. Switch. And the pressure oil set to the predetermined pressure from the pressure supply source 68c is supplied to the first chamber 68a6. A predetermined pressure is generated in the first chamber 68a6, and the coolant in the third chamber 68a8 is increased at a pressure increase rate corresponding to the area ratio between the first piston 68a3 and the second piston 68a5. As a result, the check valve 67 is supplied even though the hydraulic pressure is reduced in the section of the pipe lines L1 to L3 and the section of the check valve 67 of the pipe lines L4 to L5 due to the supply of the coolant liquid to the discharge port 64. -The hydraulic pressure drop between the actuators 20a is prevented, and the gripping force by the gripping tool 20 is appropriately maintained.

  When the coolant leaks from the check valve 67, the moving body moves (advances) to the other end side of the second cylinder portion 68a2 by an amount corresponding to the leakage amount. Thereby, the coolant is supplied between the check valve 67 and the actuator 20a. Therefore, the hydraulic pressure applied to the actuator 20a is compensated. Furthermore, in the present embodiment, as described above, the third chamber 68a8 has the maximum volume when the pressure increase by the pressure increase cylinder 68a is started. Therefore, even when there is a lot of coolant leakage from the check valve 67, the hydraulic pressure compensation by the advance of the moving body can be continued to the maximum.

  FIG. 3 and FIG. 4 each schematically show an example of the gripping tool 20 attached to the tool spindle 13 in a partial sectional view. In FIGS. 3 and 4, hatching of the cross-sectional portion is omitted for easy viewing of the drawings. Further, the tool spindle 13, the tool spindle stock 12, and the pipe line L5 are indicated by a two-dot chain line. 3 and 4, the illustration of the workpiece W gripped by the gripping tool 20 is omitted.

  First, the gripping tool 20 shown in FIG. 3 will be described. The gripping tool 20 includes a main body 20b mounted on the tool spindle 13, a collet chuck 20c accommodated in the main body 20b, and an actuator 20a accommodated in the main body 20b. The collet chuck 20c can grip the workpiece W by contacting the workpiece W with the inner surface F thereof. The actuator 20a includes a chuck sleeve 20a1, a spring receiving portion 20a2, and a spring 20a3. However, in the gripping tool 20 shown in FIG. 3 (and FIG. 4), the definition of the actuator 20a does not have to be limited, and the components necessary for opening and closing the gripping tool 20 according to the hydraulic pressure of the coolant liquid are not necessary. What is necessary is just to include all or a part. The spring receiving portion 20a2 is disposed on the rear end side of the collet chuck 20c, and houses the spring 20a3 in a concave portion having an opening facing the rear end side (tool spindle 13 side) of the gripping tool 20. The chuck sleeve 20a1 has a shape that covers the outer surface of the collet chuck 20c and the spring receiving portion 20a2 inside the main body portion 20b, and is urged toward the rear end side of the gripping tool 20 by the spring 20a3.

  As described above, when the coolant liquid is supplied from the pipe L5 to the actuator 20a, the coolant liquid flows between the main body portion 20b and the chuck sleeve 20a1. The flowing coolant liquid presses the chuck sleeve 20a1 against the urging force of the spring 20a3, and moves the chuck sleeve 20a1 toward the distal end side of the gripping tool 20 substantially along the center line CL (the spring 20a3 contracts). A space 20d into which the coolant liquid flows is formed between the main body 20b and the chuck sleeve 20a1 in accordance with the movement. A tapered surface 20a11 for tapering the chuck sleeve 20a1 from the rear end side toward the front end side of the gripping tool 20 is formed on the side facing the collet chuck 20c at the front end portion of the chuck sleeve 20a1. A tapered surface 20c1 substantially parallel to the tapered surface 20a11 is formed on the collet chuck 20c side facing the tapered surface 20a11.

  As the chuck sleeve 20a1 moves toward the tip side due to the inflow of the coolant liquid, the tapered surface 20c1 of the collet chuck 20c is pushed by the tapered surface 20a11 of the chuck sleeve 20a1. The collet chuck 20c is prohibited from moving in the direction of the central axis CL in the main body 20b. Therefore, when it is pushed by the tapered surface 20a11, it moves in a direction approaching the central axis CL. As a result, the inner diameter of the collet chuck 20c is reduced (the holding tool 20 is closed), and the workpiece W is held. On the other hand, when the check valve 67 is opened and the backflow of the coolant is started, the coolant flows out from the space 20d to the pipe L5, and the chuck sleeve 20a1 is urged by the biasing force of the spring 20a3 accordingly. To the rear end side, the inner diameter of the collet chuck 20c is expanded (the gripping tool 20 is opened).

  Next, the gripping tool 20 shown in FIG. 4 will be described. The gripping tool 20 shown in FIG. 4 includes a main body 20e attached to the tool spindle 13, a chuck claw 20f, a master jaw 20g, a shifter 20h, and an actuator 20a accommodated in the main body 20e. The chuck claws 20 f can grip the workpiece W by contacting the workpiece W. The actuator 20a shown in FIG. 4 includes a piston 20a4 and a spring 20a5. In addition, spaces 20i and 20j for allowing the coolant liquid to flow in are formed in the main body 20e. The spaces 20i and 20j communicate with a part of the piston 20a4 through a passage extending obliquely from the central axis CL side and the rear end side of the gripping tool 20 in a direction away from the central axis CL and toward the front end side of the gripping tool 20. is doing. Of the spaces at both ends of the passage, the space on the center axis CL side and the rear end side of the gripping tool 20 is the space 20j, and the other space is the space 20i. The spring 20a5 is disposed in the space 20j and urges the piston 20a4 toward the distal end side of the gripping tool 20.

  As described above, when the coolant liquid is supplied from the pipe L5 to the actuator 20a, the coolant liquid flows into the space 20j and further flows into the space 20i through the passage. Here, the diameter of the portion of the piston 20a4 pressed by the coolant liquid flowing into the space 20i is r1, while the diameter of the portion of the piston 20a4 pressed by the coolant liquid flowing into the space 20j is r2. As can be seen from FIG. 4, r1> r2. In this case, the area where the coolant liquid flowing into the space 20i presses the piston 20a4 is superior to the area where the coolant liquid flowing into the space 20j presses the piston 20a4. As a result, the entire piston 20a4 is aligned with the center line CL. It moves substantially along the rear end side of the gripping tool 20 (spring 20a5 contracts).

  The piston 20a4 and the shifter 20h are coupled with a bolt or the like (not shown). Accordingly, the shifter 20h moves together with the piston 20a4. On the side facing the master jaw 20g of the shifter 20h, a tapered surface 20h1 is formed to taper the shifter 20h from the rear end side to the front end side of the gripping tool 20. Further, a tapered surface 20g1 substantially parallel to the tapered surface 20h1 is formed on the master jaw 20g side facing the tapered surface 20h1. The master jaw 20g is slidably disposed in a direction perpendicular to the central axis CL while being prohibited from moving in the central axis CL direction in the main body 20e. If the shifter 20h is retracted, the master jaw 20g is moved to the central axis CL. Move in the direction of approach. A chuck claw 20f is fixed to the master jaw 20g.

  Accordingly, as described above, when the piston 20a4 and the shifter 20h move to the rear end side due to the inflow of the coolant liquid into the spaces 20i and 20j, the master jaw 20g approaches the center axis CL by a predetermined distance, and at the same time the chuck claw 20f also A predetermined distance approaches the central axis CL (the gripping tool 20 is closed). On the other hand, when the check valve 67 is opened and the reverse flow of the coolant is started, the coolant flows out from the spaces 20i and 20j to the pipe L5. Then, in response to the outflow, the piston 20a4 and the shifter 20h move to the distal end side of the gripping tool 20 by the biasing force of the spring 20a5. As a result, the taper surface 20g1 of the master jaw 20g is pushed by the taper surface 20h1 of the shifter 20h, and the master jaw 20g and the chuck claw 20f move by a predetermined distance in the direction away from the central axis CL (the gripping tool 20 opens).

  As described above, according to the present embodiment, the coolant liquid supplied from the hydraulic pump 61 to the pipe L1 passes through the pipe L2 and the pipe L3 connected to the pipe L2 by switching the flow path using the first switching valve 65. While being discharged from the discharge port 64, the pipe L5 and the pipe L5 connected to the pipe L4 by switching the flow path by the second switching valve 66 in parallel with this are connected to the tip of the pipe L5. It is also supplied to the actuator 20a. In the pipe L5, a check valve 67 is provided, and a pressure intensifier 68 is provided between the check valve 67 and the actuator 20a. For this reason, although the hydraulic pressure is reduced in the section of the pipe lines L1 to L3 and the section of the check valve 67 of the pipe lines L4 to L5 due to the coolant liquid discharge from the discharge port 64, it is between the check valve 67 and the actuator 20a. The hydraulic pressure can be prevented from lowering, and the actuator 20a can appropriately maintain the gripping force by the gripping tool 20.

  Further, according to the present embodiment, in the situation where the backflow prevention is achieved by the check valve 67, the hydraulic pressure between the check valve 67 and the actuator 20a is maintained even when the operation of the hydraulic pump 61 is stopped. The energy consumed by the NC lathe 100 during the work W gripping period can be saved. Furthermore, in this embodiment, when supplying the coolant liquid from the coolant tank 40 to the discharge port 64 and the actuator 20a, a dedicated drive source (such as a hydraulic pump) is further added to stabilize the pressure supply to the actuator 20a. Since it is not necessary, it can contribute to cost reduction in manufacturing the NC lathe 100 and miniaturization of the NC lathe 100. Further, as described above, by providing the pressure intensifier 68, the hydraulic pressure applied to the actuator 20a can be freely set regardless of the hydraulic pressure of the coolant liquid by the hydraulic pump 61.

  Various modifications of the present invention are conceivable. For example, a P port check valve may be provided on the upstream side (line L4) of the P port instead of the pilot check valve 67 provided on the downstream side (line L5) of the B port. Further, after switching the third switching valve 68b and connecting the A port and the T port with the pressure supply source 68c stopped, the moving body of the pressure intensifier 68 is retracted by the hydraulic pressure of the coolant liquid applied to the pipe L5. It is good also as a structure which performs.

Second embodiment:
Next, a second embodiment of the present invention will be described.
FIG. 5 is a circuit diagram of a hydraulic control system arranged on the NC lathe 100 (FIG. 1), and shows an example different from the circuit diagram (first embodiment) of FIG. In the second embodiment, portions different from the first embodiment will be mainly described, and descriptions of common portions will be omitted as appropriate. 5, the same components as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

  In the second embodiment, as shown in FIG. 5, a pipe line L1a for supplying the coolant liquid is formed from the coolant liquid tank 40, and the coolant liquid pressurized by the hydraulic pump 61 is supplied to the pipe line. L1a is sent out. A relief valve 62a and a pressure gauge 63a are provided on the pipe line L1a. Further, the pipe line L1a is piped so that the T port of the relief valve 62a returns to the coolant liquid tank 40. The relief valve 62a corresponds to the first pressure adjusting means in the claims.

  From the middle of the pipe L1a, the pipe L2 is branched and formed, and the first switching valve 65 is provided at the tip of the pipe L2 as in the first embodiment. The T port of the first switching valve 65 is connected to a pipe line L11a serving as a return flow path to the coolant liquid tank 40. Pipe lines L2 and L3 in FIG. 5 correspond to discharge channels for discharging coolant liquid to the outside. From the pipe L1a, pipes L12 and L13 are further branched between the pipe L2 and the relief valve 62a. A fourth switching valve 70 is provided at the end of the pipe L12. The fourth switching valve 70 is an electromagnetic valve, and is connected to the pipeline L12 at its P port. The T port of the fourth switching valve 70 is connected to the pipe line L11a. The A port of the fourth switching valve 70 is connected to a pipeline whose end is blocked, and the B port of the fourth switching valve 70 is connected to a pipeline L14. The pipe line L14 is connected to the pipe line L5, and a check valve 73 is provided in the pipe line L14 to prevent the backflow of coolant liquid (flow toward the fourth switching valve 70 side). Although details will be described later, the pipes L12 and L14 also correspond to discharge channels for discharging the coolant liquid to the outside.

  A fifth switching valve 71 is provided at the end of the pipe line L13. The fifth switching valve 71 is an electromagnetic valve, and corresponds to an electromagnetic valve disposed at a position closer to the coolant pump than the check valve (check valve 67) in the flow path. The fifth switching valve 71 is connected to the pipeline L13 at its P port. The T port of the fifth switching valve 71 is connected to the pipe line L11a. The A port of the fifth switching valve 71 is connected to a pipeline whose end is blocked, and the B port of the fifth switching valve 71 is connected to the pipeline L1b. A relief valve 62b and a pressure gauge 63b are provided on the pipe line L1b. Further, in the pipe L1b, the T port of the relief valve 62b is piped to the tank 40a. The relief valve 62b corresponds to the second pressure adjusting means in the claims.

  In the pipe line L1b, the pipe line L4 is branched and formed, and a second switching valve 66 ′ is provided at the tip of the pipe line L4. The second switching valve 66 ′ is an electromagnetic valve substantially corresponding to the second switching valve 66 in the first embodiment, but its specification is different from that of the second switching valve 66. Specifically, the second switching valve 66 ′ is a double solenoid type electromagnetic valve. Similarly to the second switching valve 66, the second switching valve 66 'is connected to the pipe L4 at the P port, connected to the pipe L6 at the A port, and connected to the pipe L5 at the B port. ing. The T port of the second switching valve 66 ′ is connected to a pipe line L11b that is a return flow path to the tank 40a.

  The pressure intensifier 68 ′ shown in FIG. 5 substantially corresponds to the pressure intensifier 68 in the first embodiment, but further includes a pilot check valve 68f and a relief valve 68e in the pipe line L8 as compared with the pressure intensifier 68. The relief valve 68e corresponds to the third pressure adjusting means in the claims. Further, in the pipe line L16 that connects the other end of the second cylinder part 68a2 (the tip of the pressure increasing cylinder 68a) and the pipe line L5, the inflow of the coolant liquid from the pipe line L5 to the second cylinder part 68a2 is prevented. A check valve 74 is provided. Moreover, the pressure gauge 63c is provided in the pipe line L5.

  Further, a pipe L15 for supplying the coolant liquid to the pressure increasing cylinder 68a (second cylinder part 68a2) is formed from the coolant liquid tank 40. A hydraulic pump 72 is disposed on the pipeline L15, and the coolant liquid pressurized by the hydraulic pump 72 is supplied to the second cylinder portion 68a2 through the pipeline L15. In the pipe line L15, a check valve 75 for preventing the coolant liquid from flowing from the second cylinder portion 68a2 to the coolant liquid tank 40 side is provided. Such a circuit (pipe line L15, hydraulic pump 72, check valve 75, etc.) for supplying the coolant from the coolant tank 40 to the pressure-increasing cylinder 68a corresponds to the refill circuit in the claims.

In such a configuration, in the NC lathe 100, when the gripping tool 20 mounted on the tool spindle 13 is closed to grip the workpiece W (when the NC device 50 issues a “close” command for the gripping tool 20). The following sequence is executed.
Step 0: As a premise, first, the pressure intensifier 68 'is in a state in which the moving body is retracted to the position farthest from the tip of the pressure intensifying cylinder 68a, as in the first embodiment. That is, the pressure booster 68 ′ connects the P port and the B port, and the T port and the A port of the third switching valve 68b by switching the solenoid of the third switching valve 68b to the on state (excitation state). As a result, the pressure oil is supplied from the pressure supply source 68c to the second chamber 68a7 via the pipelines L7 and L10, and the moving body moves backward. At this time, the pilot check valve 68f is opened by the pressure generated in the pipe L10, and the pressure oil is discharged from the first chamber 68a6 to the tank 68d via the pipes L8 and L9. As a result, the volume of the third chamber 68a8 becomes the maximum volume that the third chamber 68a8 can take in the second cylinder portion 68a2. It is assumed that the third chamber 68a8 is filled with the coolant liquid by starting the hydraulic pump 72 before the moving body is retracted to the position farthest from the tip of the pressure increasing cylinder 68a.

  Step 1: The NC lathe 100 starts the operation of the hydraulic pump 61 and at the same time switches the solenoid of the fifth switching valve 71 and the solenoid b (see FIG. 5) of the second switching valve 66 ′ to the ON state. As a result, the P port and the B port of the fifth switching valve 71 are connected, the P port and the B port of the second switching valve 66 ′ are connected, and the pipelines L 1 a, L 13, L 1 b, L 4 and L 5 are connected from the hydraulic pump 61. The coolant liquid is supplied to the actuator 20a via the relay.

  Step 2: Next, the NC lathe 100 stops the operation of the hydraulic pump 61 after a predetermined time has elapsed since the operation of the hydraulic pump 61 in Step S1, and at the same time, the solenoid of the fifth switching valve 71 and the second switching valve. 66 'solenoid b is switched off. As a result, the supply of further coolant liquid to the actuator 20a is stopped, but since the check valve 67 is provided in the pipe line L5, the check valve 67 prevents the backflow of the coolant liquid, and the check valve 67 -The hydraulic pressure between the actuators 20a is maintained (the gripping tool 20 is kept closed). However, the NC lathe 100 does not stop the operation of the hydraulic pump 61 in step S <b> 2 when discharging the coolant from the discharge port 64 in parallel with the closing of the gripping tool 20. Even when the NC lathe 100 discharges the coolant liquid from the discharge port 64 in parallel with the closing of the gripping tool 20, the NC lathe 100 is in the closing operation of the gripping tool 20 (the gripping tool 20 is in the closed state from the open state). During the transition to (2), the coolant liquid is not discharged from the discharge port 64 in order to secure the necessary oil pressure to the actuator 20a. On the other hand, in the state where the gripping tool 20 is closed, the coolant liquid can be discharged from the discharge port 64.

  In the double solenoid type second switching valve 66 ', even if the solenoid b is turned off as described above, the port P and the port A are connected unless the other solenoid a (see FIG. 5) is turned on. Therefore, the check valve 67 is not opened due to the pressure in the pipe L6. Such a configuration of the second switching valve 66 'is also effective for power failure countermeasures. That is, even if a power failure occurs while the gripping tool 20 is closed, the solenoid a is kept off so that the connection between the P port and the B port of the second switching valve 66 'is maintained. Therefore, even if the P port of the second switching valve 66 'is supplied with the coolant liquid and is in a pressure increasing state at that time, the P port and the A port are connected and the line L6 is not pressurized. Therefore, it is possible to prevent a situation in which the check valve 67 is opened and the gripping tool 20 is opened (the workpiece W gripped by the gripping tool 20 falls) at the time of a power failure.

  Step S3: After a lapse of a minute time (for example, several milliseconds) from Step S2, the pressure intensifier 68 ′ connects the line L7 and the line L8 by switching the solenoid of the third switching valve 68b to the OFF state. State. Then, the pressure oil set to a predetermined pressure is supplied from the pressure supply source 68c to the first chamber 68a6 of the pressure increasing cylinder 68a. The pressure oil passing through the pipe line L8 toward the first chamber 68a6 is depressurized by the relief valve 68e as compared with the pressure setting in the pressure supply source 68c. The reduced pressure oil (pressure adjusted by the relief valve 68e) is supplied to the first chamber 68a6. The pressure adjusted by the relief valve 68e is generated in the first chamber 68a6, and the coolant in the third chamber 68a8 is increased by a pressure increase rate corresponding to the area ratio between the first piston 68a3 and the second piston 68a5. Is done. Such pressure increase acts on the pipe line L5 between the check valve 67 and the actuator 20a via the pipe line L16, and compensation of the hydraulic pressure applied to the actuator 20a is started.

  As described above, in the check valve 67, a leak of the coolant liquid occurs although the amount is small. Further, a minute amount of coolant liquid may be leaked to the outside from places other than the check valve 67, for example, details of the actuator 20a. After the step S3, the moving body moves forward to the front end side of the pressure increasing cylinder 68a in response to such leakage, so that the hydraulic pressure compensation by the pressure increasing cylinder 68a is continued. In other words, a period until the moving body moves from a position farthest from the tip of the pressure increasing cylinder 68a to a position closest to the tip of the pressure increasing cylinder 68a is one-time hydraulic pressure compensation by the pressure increasing cylinder 68a. In the second embodiment, such hydraulic pressure compensation is repeatedly generated instead of once so that gripping with an appropriate force by the gripping tool 20 is continued during a necessary period.

Step S4: The NC lathe 100 detects that the moving body has moved to a position closest to the tip of the pressure increasing cylinder 68a. The detection is realized by, for example, a sensor attached to the pressure increasing cylinder 68a.
FIG. 6 illustrates a state in which the forward movement sensor 76 and the backward movement sensor 77 are attached to the pressure increasing cylinder 68a. The forward sensor 76 is attached in the vicinity of the end of the first cylinder part 68a1 on the second cylinder part 68a2 side (the tip of the first cylinder part 68a1), and the reverse sensor 77 is a second cylinder of the first cylinder part 68a1. It is attached in the vicinity of the end portion (the rear end of the pressure increasing cylinder 68a) far from the portion 68a2.

  The advance sensor 76 detects the first piston 68a3 when the first piston 68a3 of the moving body that moves in the first cylinder 68a1 approaches the tip of the first cylinder 68a1. That is, in the NC lathe 100, when the first piston 68a3 is detected by the advance sensor 76, it is detected that the moving body has moved to a position closest to the tip of the pressure increasing cylinder 68a. The advance sensor 76 corresponds to the detection means in the claims.

  Step S5: When it is detected that the moving body has moved to a position closest to the tip of the pressure increasing cylinder 68a, the pressure intensifier 68 'moves the moving body backward by switching the solenoid of the third switching valve 68b to the on state. Let In the second embodiment, a check valve 74 is provided between the second cylinder portion 68a2 and the pipe line L5. Therefore, the coolant liquid is prevented from flowing into the second cylinder portion 68a2 from the pipe line L5 side in the process of moving the moving body, and the pressure applied to the actuator 20a is maintained. When it is detected that the moving body has moved to the position closest to the tip of the pressure increasing cylinder 68a, the NC lathe 100 starts the operation of the hydraulic pump 72, and the moving body is positioned farthest from the tip of the pressure increasing cylinder 68a. Move to.

  Step S6: The NC lathe 100 detects that the moving body has moved to a position farthest from the tip of the pressure increasing cylinder 68a. The reverse sensor 77 detects the first piston 68a3 when the first piston 68a3 of the moving body approaches the rear end of the pressure increasing cylinder 68a. That is, in the NC lathe 100, when the first piston 68a3 is detected by the reverse sensor 77, it is detected that the moving body has moved to a position farthest from the tip of the pressure increasing cylinder 68a.

  Step S7: The NC lathe 100 stops after the hydraulic pump 72 has been operated for a predetermined fixed time necessary for filling the third chamber 68a8 having the maximum volume with the coolant liquid. Specifically, the NC lathe 100 stops the hydraulic pump 72 after a predetermined time has elapsed after detecting that the moving body has moved to the position farthest from the tip of the pressure increasing cylinder 68a in step S6. As a result of the above steps S5 to S7, the third chamber 68a8 whose volume is maximized by the retreat of the moving body is filled with the coolant liquid via the pipe line L15. It should be noted that the timing for starting the operation of the hydraulic pump 72 may be the same as when the moving body starts to move backward by switching the solenoid of the third switching valve 68b to the ON state, or from the start of the backward movement. It may be delayed timing (during the retreating period of the moving body).

  When the moving body starts to move backward by switching the solenoid of the third switching valve 68b to the on state (step S5), negative pressure is generated in the third chamber 68a8 of the second cylinder portion 68a2. Therefore, even without the hydraulic pump 72, the coolant liquid is supplied from the coolant liquid tank 40 to the third chamber 68a8 through the pipe L15 by the negative pressure as the moving body moves backward. Therefore, the hydraulic pump 72 is not an essential component in the replenishment circuit. However, when the coolant liquid is supplied to the third chamber 68a8 only by the inflow due to the negative pressure, when the bubbles are mixed in the pipe line L15, the coolant liquid is injected into the third chamber 68a8 only by the inflow due to the negative pressure. Since it is conceivable not to fill, it is better to use the hydraulic pump 72 that applies a certain pressure to the fluid. Further, when the hydraulic pump 61 and the hydraulic pump 72 are compared, the pressure generated by the hydraulic pump 72 may be lower, so that the hydraulic pump 72 basically has a lower capacity than the hydraulic pump 61 (consumption). Adopt a pump with low energy and low cost.

  Step S8: After the hydraulic pump 72 is stopped (or after the third chamber 68a8 is filled with the coolant liquid), the pressure intensifier 68 ′ switches the solenoid of the third switching valve 68b to the OFF state by switching the line L7. The pipe L8 is connected, and the pressure oil set at a predetermined pressure is supplied from the pressure supply source 68c to the first chamber 68a6 of the pressure increasing cylinder 68a via the pipes L7 and L8. That is, the hydraulic pressure compensation accompanied by the advance of the moving body is performed again. Thereafter, in the NC lathe 100, steps S4 to S8 are repeated until the gripping tool 20 is opened (until the NC device 50 issues an “open” command for the gripping tool 20).

  When opening the gripping tool 20, the NC lathe 100 starts the operation of the hydraulic pump 61 when the hydraulic pump 61 is stopped, and at the same time, the solenoid of the fifth switching valve 71 and the solenoid of the second switching valve 66 '. Switch a to the on state. As a result, in the second switching valve 66 ′, the P port and the A port are connected, and the T port and the B port are connected, and pressure is generated in the pipe line L6. As a result, the check valve 67 is opened by the pressure generated in the pipe L6, and the backflow of the coolant liquid is allowed (the coolant liquid flows out from the pipe L5 to the pipe L11b). The actuator 20a opens the gripping tool 20 when the coolant liquid flows out from the pipe line L5 and is in a reduced pressure state.

  The forward sensor 76 is a means for detecting that the amount of the coolant liquid in the second cylinder portion 68a2 has decreased to a predetermined amount (that the hydraulic pressure compensation by the pressure-increasing cylinder 68a has ended or is about to end). Only. In order to detect that the amount of the coolant liquid in the second cylinder portion 68a2 has decreased to a predetermined amount, means other than the forward sensor 76 may be used. For example, a measuring unit that directly measures the leakage amount of the coolant liquid from the pipe L5 between the check valve 67 and the actuator 20a during the period when the gripping tool 20 is closed is provided. Then, the NC lathe 100 determines that the amount of the coolant liquid in the second cylinder portion 68a2 has decreased to a predetermined amount when leakage exceeding the specified amount is measured by the measuring means (step S4), and the moving body The backward movement may be started (step S5).

  As described above, according to the second embodiment, the NC lathe 100 is provided with the replenishment circuit capable of supplying the coolant liquid to the second cylinder portion 68a2 of the pressure increasing cylinder 68a that realizes the hydraulic pressure compensation for the actuator 20a. And whenever it detects that the quantity of the coolant liquid in the 2nd cylinder part 68a2 fell to the predetermined amount with advance of the moving body in the pressure increase cylinder 68a, it is coolant in the 2nd cylinder part 68a2 by a replenishment circuit. Liquid was supplied so that the oil pressure compensation continued. Therefore, the hydraulic pressure compensation can be reliably continued during a period in which the hydraulic pressure compensation for the actuator 20a is necessary.

  Note that it is possible to extend the hydraulic pressure compensation by the pressure-increasing cylinder 68a by increasing the amount of oil that can be filled in the second cylinder portion 68a2, but the pressure-increasing cylinder 68a itself becomes enormous. According to the second embodiment, by repeating the replenishment of the coolant liquid by the replenishment circuit, it is possible to arbitrarily extend the hydraulic pressure compensation without enlarging the pressure increasing cylinder 68a. Further, in the state where the gripping tool 20 is closed, the leakage of the coolant liquid from the details of the check valve 67 and the actuator 20a (including a portion where the coolant liquid is sealed so as not to leak) is completely eliminated. Is not easy. In order to eliminate such leakage completely, special techniques and many man-hours are required when assembling the NC lathe 100. According to the second embodiment, it is possible to reliably compensate for the decrease in hydraulic pressure during the period of closing the gripping tool 20 on the premise that there is leakage of the coolant liquid, and therefore, the assembly work of the NC lathe 100 is also facilitated and efficient. Is done.

  As described above, the gripper 20 and the tool 19 are alternatively mounted on the tool spindle 13. When the tool 19 is mounted on the tool spindle 13, the tool 19 is used for machining the workpiece W, and during the machining, coolant liquid is discharged to the outside from a coolant liquid discharge hole (not shown) formed in the tool 19. Is done. The pipes L12 and L14 are pipes (discharge channels) used to discharge the coolant liquid from the coolant liquid discharge holes formed in the tool 19 mounted on the tool spindle 13 as described above. When the tool 19 is mounted on the tool spindle 13, a part of the pipe line L5 (a part on the tip side from the junction with the pipe line L14) also serves as a discharge flow path. That is, when the tool 19 is mounted on the tool spindle 13, the NC lathe 100 connects the P port and the B port by turning on the solenoid of the fourth switching valve 70 and connects the pipes L12 and L14. Thereby, the coolant liquid sent out to the hydraulic pump 61 is supplied to the tool 19 via the pipe lines L1a, L12, L14, and L5, and is discharged to the outside from the hole formed in the tool 19. When the coolant liquid is discharged from the tool 19 attached to the tool spindle 13, the solenoid of the fifth switching valve 71 is switched to the off state.

  The hydraulic pressure applied to the coolant liquid discharged to the outside may be different from the hydraulic pressure applied to the actuator 20a to close the gripping tool 20. More specifically, the hydraulic pressure applied to the actuator 20a may be lower than the hydraulic pressure applied to the coolant liquid discharged to the outside in consideration of the risk of damage to the workpiece W gripped by the gripping tool 20. Therefore, in the second embodiment, the hydraulic pressure applied to the coolant liquid discharged to the outside and the hydraulic pressure applied to the actuator 20a can be individually adjusted. In order to enable the individual adjustment, a fifth switching valve 71 is provided, and relief valves 62a and 62b for adjusting the hydraulic pressures of the respective flow paths before and after the fifth switching valve 71 are provided.

  Specifically, in the NC lathe 100, when adjusting the hydraulic pressure applied to the actuator 20a, the hydraulic pump 61 is operated, and the solenoid of the fifth switching valve 71 and the solenoid b of the second switching valve 66 ′ are switched on. And the solenoid of the 1st switching valve 65 and the solenoid of the 4th switching valve 70 are switched to an OFF state. In this state, the operator adjusts the relief valve 62b, so that the hydraulic pressure of the coolant liquid supplied to the actuator 20a through the pipelines L1b, L4, L5 can be adjusted to an appropriate value. On the other hand, in the NC lathe 100, when adjusting the hydraulic pressure applied to the coolant liquid discharged to the outside, the hydraulic pump 61 is operated, and the solenoid of the first switching valve 65 and the solenoid of the fourth switching valve 70 are switched on. And the solenoid of the 5th switching valve 71 is switched to an OFF state. In this state, the operator can adjust the relief valve 62a to adjust the hydraulic pressure of the coolant liquid discharged to the outside through the discharge passage to an appropriate value.

  As described above, in the second embodiment, the hydraulic pressure of the coolant liquid supplied to the actuator 20a is adjusted by the relief valve 62b. For this reason, the hydraulic pressure applied to the pipe line L5 by the pressure increasing cylinder 68a needs to coincide with the hydraulic pressure adjusted by the relief valve 62b. Therefore, the pressure intensifier 68 'includes a relief valve 68e, and the matching is possible by adjusting the hydraulic pressure by the relief valve 68e. As an example, when the hydraulic pressure is adjusted to 6.0 MPa by the relief valve 62b and the area ratio between the first piston 68a3 and the second piston 68a5 of the pressure increasing cylinder 68a is 2: 1, the relief valve 68e is increased. The pressure of the pressure oil supplied to the first chamber 68a6 of the pressure cylinder 68a is set to 3.0 MPa. By performing such setting, the hydraulic pressure in the pipe L5 between the check valve 67 and the actuator 20a when driving the actuator 20a is stabilized at an ideal value (in this case, 6.0 MPa), and the gripping tool 20 is appropriate. The workpiece W can be held with a strong force.

Third embodiment:
Next, a third embodiment of the present invention will be described.
FIG. 7 is a circuit diagram of a hydraulic control system disposed on the NC lathe 100 (FIG. 1), and shows an example different from the circuit diagrams of FIGS. In the third embodiment, portions different from those in the first and second embodiments will be mainly described, and description of common portions will be appropriately omitted. 7, the same components as those in FIGS. 2 and 5 are denoted by the same reference numerals as those in FIGS.

  In the third embodiment, a supplementary circuit different from the second embodiment is provided. As shown in FIG. 7, a pipe L17 is branched from the pipe L1a. A sixth switching valve 78 is provided at the tip of the pipe line L17. The sixth switching valve 78 is an electromagnetic valve, and is connected to the pipe line L17 at its P port. A pressure reducing valve 79 is provided in the middle of the pipe line L17. The T port of the sixth switching valve 78 is connected to the pipe L11a. The A port of the sixth switching valve 78 is connected to a pipeline whose end is blocked, and the B port of the sixth switching valve 78 is connected to a pipeline L18. The pipe line L18 is connected to the second cylinder portion 68a2, and a check valve 75 is provided in the pipe line L18 for preventing the backflow of coolant liquid (flow to the sixth switching valve 78 side). That is, the pipe line L1a, the hydraulic pump 61, the pipe line L17, the pressure reducing valve 79, the sixth switching valve 78, the pipe line L18, and the check valve 75 correspond to the supplementary circuit.

  The timing of supplying the coolant liquid to the third chamber 68a8 in the second cylinder portion 68a2 by such a replenishment circuit is the same as in the case of the second embodiment. That is, the NC lathe 100 turns on the solenoid of the sixth switching valve 78 at the same timing as the hydraulic pump 72 (FIG. 5) described in the second embodiment starts operating (P of the sixth switching valve 78). The port and the B port are connected and the pipe lines L17 and L18 are connected), and the coolant liquid sent out by the hydraulic pump 61 is supplied to the third chamber 68a8 through the pipe line L18. However, the hydraulic pressure of the coolant liquid passing through the pipe L17 is supplied to the pipe L18 after being reduced by the pressure reducing valve 79 to a value equal to or lower than the hydraulic pressure set value by the relief valve 62b. Then, the solenoid of the sixth switching valve 78 is turned off after a predetermined time required for filling the coolant in the third chamber 68a8 whose volume is maximized. Of course, it is assumed that the hydraulic pump 61 is also operated at least while the solenoid of the sixth switching valve 78 is in the ON state.

Fourth embodiment:
The NC device 50 measures the time interval during which the coolant liquid is supplied by the replenishment circuit. As an example, the NC device 50, when the supply of the coolant liquid to the second cylinder portion 68a2 by the above-described replenishment circuit is completed (when the operation of the hydraulic pump 72 is stopped or the solenoid of the sixth switching valve 78 is turned off). The time from when the coolant is supplied by the replenishment circuit (when the hydraulic pump 72 is started or when the solenoid of the sixth switching valve 78 is turned on) to the next time Measure by Then, the time obtained by the measurement is compared with a predetermined set time, and when the time obtained by the measurement is shorter than the set time, it is determined as abnormal.

  That is, when the time obtained by such measurement is shorter than the set time, it is estimated that there is a lot of coolant leakage from the check valve 67, the actuator 20a, etc. while the gripping tool 20 is closed. In such a case, the NC device 50 determines that there is an abnormality. When the NC device 50 determines that there is an abnormality, the NC lathe 100 stops the operation of the NC lathe 100 while performing predetermined alarm processing (alarm processing by voice, display, etc.) to the outside. By making such an abnormality determination, the operator can easily find and repair the abnormality of the pipe L5 and its peripheral parts (check valve 67, actuator 20a, pipe 18, check valve 75, etc.). Is possible. In addition, the time interval of the supply by the replenishment circuit to be measured by the NC device 50 may be the time from the start of supply of the coolant liquid to the next supply by the replenishment circuit, or the coolant by the replenishment circuit. It may be the time from the end of the supply of the liquid to the end of the next supply, or the time from the end of the supply of the coolant liquid by the replenishment circuit until the first piston 68a3 is detected by the advance sensor 77. Further, it is assumed that the NC device 50 holds in advance an optimal set time for comparison according to the type of measured time.

DESCRIPTION OF SYMBOLS 10 ... Spindle base, 11 ... Spindle, 12 ... Tool spindle, 13 ... Tool spindle, 14 ... ATC, 16 ... Tool stand, 20 ... Gripping tool, 20a ... Actuator, 20a1 ... Chuck sleeve, 20a2 ... Spring receiving part, 20a3 ... Spring, 20a4 ... Piston, 20a5 ... Spring, 20b ... Main body part, 20c ... Collet chuck, 20d ... Space, 20e ... Main body part, 20f ... Chuck claw, 20g ... Master jaw, 20h ... Shifter, 20i, 20j ... Space, 40 ... Coolant liquid tank, 50 ... NC device, 61,72 ... Hydraulic pump, 62a, 62b ... Relief valve, 64 ... Discharge port, 65 ... First switching valve, 66,66 '... Second switching valve, 67 ... Check Valve, 68, 68 '... pressure increaser, 68a ... pressure increase cylinder, 68b ... third switching valve, 68c ... pressure supply source, 68a1 ... first cylinder part, 68 a2 ... second cylinder part, 68a3 ... first piston, 68a4 ... rod, 68a5 ... second piston, 68e ... relief valve, 70 ... fourth switching valve, 71 ... fifth switching valve, 73-75 ... check valve, 76 ... Forward sensor, 77 ... Reverse sensor, 78 ... Sixth switching valve, 79 ... Pressure reducing valve, 100 ... NC lathe, L1, L1a, L1b, L2-L11, L11a, L11b, L12-L18 ... Pipe line, W ... Workpiece

Claims (10)

A coolant pump for supplying coolant liquid to a predetermined flow path;
An actuator that is mounted at the tip of the flow path and is driven by the pressure of the coolant supplied through the flow path;
A check valve provided in the flow path for preventing the back flow of the coolant liquid;
A pressure-increasing cylinder that causes pressure increase in the cylinder to act on a flow path between the check valve and the actuator;
A replenishment circuit for supplying a coolant liquid into the pressure increasing cylinder;
A machine tool comprising:   The pressure increasing cylinder includes a first cylinder part, a second cylinder part having a smaller cross-sectional area than the first cylinder part, one end communicating with the first cylinder part, and the other end connected to the flow path, and the first cylinder 2. The machine tool according to claim 1, further comprising: a movable body that is slidable inside the first cylinder portion and the second cylinder portion, wherein pressure increase in the second cylinder portion is applied to the flow path.   The machine tool according to claim 2, wherein the replenishment circuit supplies the coolant liquid into the second cylinder part when the amount of the coolant liquid in the second cylinder part is reduced to a predetermined amount. A detecting means for detecting that the moving body is closest to the other end;
The said replenishment circuit supplies a coolant liquid in the said 2nd cylinder part, when it is detected by the said detection means that the said mobile body approached the said other end most. 3. The machine tool according to 3.   5. The machine tool according to claim 3, wherein an abnormality is determined when an interval in which the replenishment circuit supplies coolant liquid is shorter than a predetermined set time. An electromagnetic valve disposed at a position closer to the coolant pump than the check valve in the flow path;
A discharge flow path for branching from the position on the coolant pump side relative to the solenoid valve in the flow path, and for discharging coolant liquid to the outside;
First pressure adjusting means capable of adjusting the pressure in the flow path on the coolant pump side than the solenoid valve;
The machine tool according to any one of claims 1 to 5, further comprising: a second pressure adjusting unit capable of adjusting a pressure in the flow path on the tip end side of the electromagnetic valve.   The work according to any one of claims 1 to 6, further comprising third pressure adjusting means capable of adjusting a pressure applied to a flow path between the check valve and the actuator by the pressure increasing cylinder. machine. A coolant pump for supplying coolant liquid to a predetermined flow path;
A discharge port for discharging the coolant supplied to the flow path to the outside;
An actuator that is attached to the tip of the second flow path branched from the flow path and is driven by the pressure of the coolant liquid supplied through the second flow path;
A check valve provided in the second flow path for preventing a back flow of the coolant,
A machine tool comprising: a pressure intensifier provided between the check valve and the actuator in the second flow path. The pressure intensifier includes a first cylinder part, a second cylinder part having a smaller cross-sectional area than the first cylinder part, one end communicating with the first cylinder part, and the other end communicating with the second flow path, A pressure-increasing cylinder having a cylinder part and a movable body that can slide inside the second cylinder part, the pressure-increasing cylinder acting on the second flow path in the second cylinder part;
After the supply of the coolant liquid from the coolant pump to the flow path and the second flow path is started, the pressure intensifier applies pressure to the pressure increase cylinder in a state where the moving body is farthest from the other end. 9. The machine tool according to claim 8, wherein the pressure in the second cylinder portion is increased.   The machine tool according to any one of claims 1 to 9, wherein the actuator opens and closes a gripping tool used for gripping a workpiece by the pressure of the coolant liquid.

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