JP7476684B2 - Machine tool and pressure relief method - Google Patents

Description

This disclosure relates to a machine tool and a method for depressurizing.

Machine tools use tools attached to the spindle to perform various processes, such as cutting, on workpieces. Machine tools cool the workpiece that generates heat during processing by ejecting a coolant (cutting fluid) from the tool, and remove chips generated by processing from the workpiece. (See Patent Document 1)

JP 2001-198772 A

When the above-mentioned machine tool stops discharging the coolant, pressurized coolant remains in the coolant flow path due to the residual pressure at the time of discharge. The worker operating the machine tool removes the coolant flow path, for example, for maintenance of the machine tool. Since pressurized coolant remains in the coolant flow path, there is a risk of the coolant spraying out when the flow path is removed.

The present disclosure aims to provide a machine tool etc. that can prevent the coolant from spraying out when removing the coolant flow path.

The machine tool according to the present disclosure is a machine tool that discharges coolant from a tool attached to a spindle, and includes a tank for storing the coolant, a pump for supplying the coolant stored in the tank, a coolant flow path that connects a spindle flow path provided in the spindle to the pump and through which the coolant flows, a coolant valve provided in the coolant flow path, a first drive unit that drives the coolant valve when the coolant is discharged, and a second drive unit that drives the coolant valve when the coolant flow path is depressurized, and the spindle flow path is connected to a tool flow path provided in the tool.

In the present disclosure, the pump supplies the coolant stored in the tank to the spindle passage through the coolant passage. When the machine tool discharges the coolant, the first drive unit drives, i.e., opens and closes, the coolant valve. When the coolant valve opens, the machine tool uses the pump to discharge the coolant from the tool through the coolant passage, the spindle passage, and the tool passage. When the coolant valve closes, the machine tool stops discharging the coolant. At this time, the pump stops. The coolant that was pressurized by the pump during discharge remains between the coolant valve and the pump in the coolant passage. Therefore, the internal pressure between the coolant valve and the pump in the coolant passage is high. When the coolant passage is depressurized, the second drive unit opens and closes the coolant valve. When the coolant valve opens, the coolant remaining in the coolant passage can be discharged from the tool through the spindle passage and the tool passage. After the coolant is discharged, the internal pressure between the coolant valve and the pump in the coolant passage is lower than the internal pressure between the coolant valve and the pump in the coolant passage before the coolant is discharged. The coolant passage can be depressurized. This prevents the coolant from spraying out when the coolant flow path is removed.

The machine tool according to the present disclosure includes a bypass flow path that branches off from between the pump and the coolant valve in the coolant flow path and connects to the tank, a bypass valve provided in the bypass flow path, and a bypass valve drive unit that drives the bypass valve.

In the present disclosure, the bypass valve drive unit opens and closes the bypass valve. When the machine tool discharges the coolant, the bypass valve is closed. After the discharge of the coolant is stopped, pressurized coolant remains between the coolant valve and the pump in the coolant flow path. By opening the bypass valve, the remaining coolant flows into the tank through the bypass flow path, so that the coolant flow path can be depressurized. Therefore, it is possible to prevent the coolant from spouting out when the coolant flow path is removed. The coolant that flows into the tank can be reused. For example, when the tool flow path is clogged by cutting chips, in addition to between the coolant valve and the pump in the coolant flow path, pressurized coolant remains between the coolant valve and the spindle flow path in the coolant flow path, in the spindle flow path, and in the tool flow path. By opening the coolant valve and the bypass valve, the coolant remaining between the coolant valve and the spindle flow path in the coolant flow path, in the spindle flow path, and in the tool flow path flows into the tank through the bypass flow path together with the coolant remaining between the coolant valve and the pump in the coolant flow path. In addition to depressurizing the coolant flow passages, it is possible to depressurize the spindle flow passage and the tool flow passage.

In the machine tool disclosed herein, the coolant valve and the bypass valve are driven by compressed air, and the bypass valve drive unit controls the supply and cut-off of the compressed air to the bypass valve.

In the present disclosure, the coolant valve and the bypass valve are opened and closed by compressed air. For example, the coolant valve and the bypass valve are opened by the supply of compressed air and closed by the cutoff of compressed air. The bypass valve drive unit controls the supply and cutoff of compressed air to the bypass valve, i.e., the supply and cutoff of compressed air. The coolant is generally oil, which may be ignited by electricity. The coolant valve and the bypass valve do not use electricity to open and close, so the safety of the machine tool can be further improved. The coolant may contain foreign matter such as cutting chips. The foreign matter may adhere to or accumulate on at least one of the coolant valve and the bypass valve. Since the coolant valve and the bypass valve are opened and closed by compressed air, the opening and closing forces of the coolant valve and the bypass valve are large. Therefore, even if foreign matter adheres to or accumulates on the coolant valve, the coolant valve is easy to open and close. Even if foreign matter adheres to or accumulates on the bypass valve, the bypass valve is easy to open and close.

In the machine tool disclosed herein, the first drive unit is connected to a supply device that supplies the compressed air, and includes a solenoid valve that controls the supply and cut-off of the compressed air to the coolant valve.

In the present disclosure, the solenoid valve controls the supply and cut-off of compressed air to the cooling liquid valve. Since the solenoid valve has excellent responsiveness in opening and closing, the supply and cut-off of compressed air to the cooling liquid valve can be switched more quickly. Therefore, the responsiveness in opening and closing the cooling liquid valve can be improved.

In the machine tool according to the present disclosure, the first drive unit includes a first compressed air flow path that connects the coolant valve and the solenoid valve and through which the compressed air flows, the bypass valve drive unit includes a valve body that connects to the supply device and a second compressed air flow path that connects the valve body and the bypass valve and through which the compressed air flows, and the second drive unit includes a third compressed air flow path that branches off from the second compressed air flow path and connects to the first compressed air flow path, and a check valve provided in the third compressed air flow path.

In the present disclosure, the cooling liquid valve opens and closes depending on whether compressed air flows through the first compressed air flow path. When compressed air flows through the first compressed air flow path, the cooling liquid valve is open because compressed air is supplied to the cooling liquid valve. When compressed air does not flow through the first compressed air flow path, the cooling liquid valve is closed. By opening and closing the valve body, a state in which compressed air flows through the second compressed air flow path and a state in which compressed air does not flow through the second compressed air flow path are switched. The bypass valve opens and closes depending on whether compressed air flows through the second compressed air flow path. When compressed air does not flow through the second compressed air flow path, the bypass valve is closed. When compressed air flows through the second compressed air flow path, the bypass valve is open because compressed air is supplied to the bypass valve. The compressed air flowing through the second compressed air flow path flows through the first compressed air flow path via the third compressed air flow path. Therefore, by opening and closing the valve body, it is possible to control the supply and cut-off of compressed air to the cooling liquid valve and the supply and cut-off of compressed air to the bypass valve. The coolant valve and bypass valve can be opened and closed by opening and closing the valve body once.

The depressurization method according to the present disclosure is a method for depressurizing a machine tool that discharges coolant from a tool attached to a spindle, in which a coolant valve provided in a coolant flow path that connects a pump that supplies the coolant stored in a tank and a spindle flow path provided in the spindle is driven by a first drive unit when the coolant is discharged, and the coolant valve is driven by a second drive unit when the coolant flow path is depressurized.

In the present disclosure, an operator who operates a machine tool drives, i.e., opens and closes, the coolant valve by the first drive unit when discharging the coolant. When the coolant valve is opened, the machine tool uses a pump to discharge the coolant stored in the tank from the tool through the coolant passage, the spindle passage, and the tool passage. When the coolant valve is closed, the machine tool stops discharging the coolant. The coolant that was pressurized by the pump during discharging remains between the coolant valve and the pump in the coolant passage. Therefore, the internal pressure of the coolant passage is high. When depressurizing the coolant passage, the operator opens and closes the coolant valve by the second drive unit. When the coolant valve is opened, the coolant remaining in the coolant passage flows out of the tool through the spindle passage and the tool passage. The above-mentioned remaining coolant flows out of the tool, thereby depressurizing the coolant passage. Therefore, when removing the coolant passage, it is possible to prevent the coolant from spraying out.

According to the present disclosure, it is possible to prevent the coolant from spraying out when removing the coolant flow path.

FIG. 2 is a perspective view illustrating a machine tool body provided in the machine tool. FIG. 2 is a front cross-sectional view of the front part of the spindle head. FIG. 2 is a circuit diagram showing a circuit relating to a coolant and compressed air of a machine tool. FIG. 11 is a circuit diagram showing a circuit relating to a cooling fluid and compressed air of a modified example of a machine tool.

(Embodiment 1)
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the following description, up/down, left/right, and front/rear directions are indicated by arrows in the drawings. Fig. 1 is a perspective view showing a machine tool main body 1 provided in a machine tool.

The machine tool main body 1 includes a base 11. A column 12 extending in the vertical direction is provided on the rear of the base 11. The column 12 supports a spindle head 13 at its front. The spindle head 13 protrudes forward and can move in the vertical direction along the front surface of the column 12. The column 12 includes, for example, a feed screw shaft extending in the vertical direction into which the rear of the spindle head 13 screws, and a motor connected to the feed screw shaft. Driven by the motor, the feed screw shaft rotates around an axis parallel to the vertical direction. The spindle head 13 moves in the vertical direction in response to the rotation of the feed screw shaft.

The spindle head 13 holds the spindle 2 (see Figure 2), which can rotate around an axis parallel to the vertical direction. A spindle motor 14 connected to the spindle 2 is fixed to the top of the spindle head 13. Driven by the spindle motor 14, the spindle 2 rotates around an axis parallel to the vertical direction. A tool 3 is removably attached to the lower end of the spindle 2. A workpiece holding section 15, which can move left and right and forward and backward, is provided on the front of the base 11. The workpiece holding section 15 holds a workpiece. The spindle 2 is disposed above the workpiece holding section 15. As the spindle 2 rotates, the tool 3 rotates, machining the workpiece held by the workpiece holding section 15.

A turret-type tool magazine 16 is provided in front of the spindle head 13. The tool magazine 16 holds a number of tools 3 around the periphery of the tool magazine 16. In FIG. 1, the tools 3 held by the tool magazine 16 are omitted. The tool magazine 16 attaches and removes the tools 3 to and from the spindle 2. A rectangular control device 17 is attached to the rear of the column 12. The control device 17 controls each operation of the machine tool main body 1.

The machine tool has a cover (not shown) that surrounds the machine tool body 1. The cover prevents the coolant from splashing around the machine tool when the coolant is discharged, as described below.

Figure 2 is a front cross-sectional view of the front part of the spindle head 13. A hollow cylindrical housing 13a that is open at the bottom is provided at the front part of the spindle head 13. The housing 13a extends in the vertical direction. A hollow cylindrical spindle 2 that also extends in the vertical direction is provided in the hollow part of the housing 13a. The spindle 2 is attached to the housing 13a via a bearing 13b so that it can rotate around an axis in the vertical direction.

The spindle 2 is formed with a spindle hole 2a that extends in the vertical direction. A circular tool holder mounting hole 20 that opens downward is formed in the lower part of the spindle 2. The tool holder mounting hole 20 is tapered, the diameter of which decreases from the lower part of the spindle 2 to the upper part of the spindle 2. The upper part of the tool holder mounting hole 20 is connected to the spindle hole 2a.

A cylindrical drawbar 21 extending vertically is inserted into the main shaft hole 2a. An O-ring 22 is provided around the drawbar 21. The O-ring 22 abuts against the drawbar 21 and the main shaft 2. A circular drawbar through hole 21a is formed in the drawbar 21. The drawbar through hole 21a passes through the drawbar 21 in the vertical direction. The upper part of the drawbar through hole 21a is connected to a coolant flow path 53 (see Figure 3) through which the coolant flows, which will be described later. The diameter of the lower part of the drawbar through hole 21a is larger than the diameter of the upper part of the drawbar through hole 21a.

A cylindrical nozzle 23 extending in the vertical direction is inserted into the lower part of the drawbar through hole 21a. An O-ring 24 is provided around the nozzle 23. The O-ring 24 abuts against the nozzle 23 and the drawbar 21. The nozzle 23 is formed with a nozzle through hole 23a that penetrates the nozzle 23 in the vertical direction. The nozzle through hole 23a is connected to the drawbar through hole 21a. Since the drawbar through hole 21a is connected to the cooling liquid flow path 53, the cooling liquid flows through the drawbar through hole 21a and the nozzle through hole 23a. The drawbar through hole 21a and the nozzle through hole 23a correspond to the main shaft flow path. Hereinafter, the drawbar through hole 21a and the nozzle through hole 23a are collectively referred to as the main shaft flow path 25.

A tool 3 is attached to the bottom of the spindle 2. The tool 3 has a cylindrical tool holder 31 and a pull stud 32 that extends in the vertical direction. The top of the tool holder 31 tapers in diameter toward the top and fits into the tool holder mounting hole 20. A circular holder through hole 31a is formed in the tool holder 31. The holder through hole 31a passes through the tool holder 31 in the vertical direction. The diameter of the top of the holder through hole 31a is larger than the diameter of the bottom of the holder through hole 31a. The bottom of the pull stud 32 fits into the top of the holder through hole 31a.

The pull stud 32 has a pull stud through hole 32a that passes through the pull stud 32 in the vertical direction. The pull stud through hole 32a is connected to the holder through hole 31a. When the upper part of the tool holder 31 is fitted into the tool holder mounting hole 20, the upper part of the pull stud 32 abuts against the lower part of the nozzle 23. At this time, the upper part of the pull stud through hole 32a and the lower part of the nozzle through hole 23a are connected via a seal member 34, such as an O-ring.

The tool 3 further comprises a tool body 30 for machining the workpiece, and a tool flow passage 33. The tool body 30 is a rod-shaped body extending in the vertical direction, and is attached to the lower part of the tool holder 31. A body through hole 30a is formed in the tool body 30, passing through the tool body 30 in the vertical direction. An outlet 30b is formed in the lower part of the tool body 30, which is connected to the body through hole 30a. The upper part of the body through hole 30a is connected to the lower part of the holder through hole 31a. In other words, the body through hole 30a and the pull stud through hole 32a are connected via the holder through hole 31a.

The tool flow passage 33 includes the pull stud through hole 32a, the holder through hole 31a, and the main body through hole 30a. Because the upper part of the pull stud through hole 32a is connected to the lower part of the nozzle through hole 23a, the coolant flows through the pull stud through hole 32a, the holder through hole 31a, and the main body through hole 30a. In other words, the coolant flows through the tool flow passage 33. The coolant flowing through the tool flow passage 33 flows out from the discharge port 30b.

As described above, the spindle 2 rotates, causing the tool 3 to rotate and the tool body 30 to machine the workpiece. When machining the workpiece, the tool body 30 and the workpiece generate heat. When machining the workpiece, the machine tool cools the tool body 30 and the workpiece by discharging coolant from the discharge port 30b. By discharging coolant as described above, the machine tool also removes chips generated by machining the workpiece and prevents the chips from accumulating on the workpiece. In other words, the coolant cools the tool body 30 and the workpiece. Also, the coolant removes chips generated by machining the workpiece and prevents the chips from accumulating on the workpiece.

Figure 3 is a circuit diagram showing the circuits related to the coolant and compressed air of the machine tool. The machine tool is equipped with a tank 50 that stores the coolant, and a pump 51 that supplies the coolant to the spindle passage 25. The tank 50 and the suction port of the pump 51 are connected via a coolant supply passage 52 for supplying the coolant to the pump 51. The discharge port of the pump 51 is connected to the drawbar through hole 21a, i.e., the spindle passage 25, via a coolant passage 53. The coolant flows through the coolant supply passage 52 and the coolant passage 53. The coolant supply passage 52 and the coolant passage 53 are formed, for example, by hoses.

The pump 51 is, for example, a gear pump. The machine tool uses the pump 51 to discharge the cooling liquid stored in the tank 50 from the discharge port 30b, i.e., the tool 3. In detail, the pump 51 supplies the cooling liquid stored in the tank 50 to the spindle passage 25 via the cooling liquid passage 53. The cooling liquid flows through the spindle passage 25 and the tool passage 33, and flows out from the discharge port 30b. For example, the control device 17 controls the start and stop of the pump 51. In FIG. 3, the signal line connecting the control device 17 and the pump 51 is omitted. The pump 51 starts when the cooling liquid is discharged, and stops when the discharge of the cooling liquid stops. Note that the pump 51 is not limited to a gear pump.

The coolant flow path 53 is provided with a coolant valve 54. The coolant flow path 53 includes a first coolant flow path 53a that connects the pump 51 and the coolant valve 54, and a second coolant flow path 53b that connects the coolant valve 54 and the spindle flow path 25.

The coolant valve 54 is driven by compressed air, i.e., opens and closes. When compressed air is supplied, the coolant valve 54 opens. When compressed air is cut off, the coolant valve 54 closes. The coolant valve 54 is a so-called airless-close valve, or a normally-closed valve. As will be described in detail later, the coolant valve 54 opens when the coolant is discharged, and closes when the discharge of the coolant stops. It also opens when the coolant flow path 53 is depressurized, which will be described later.

The machine tool is provided with a bypass flow path 55 through which the coolant flows. The bypass flow path 55 branches off from the first coolant flow path 53a and connects to the tank 50. That is, the bypass flow path 55 branches off from the coolant flow path 53 between the pump 51 and the coolant valve 54. The bypass flow path 55 is formed, for example, by a hose. The portion of the coolant flow path 53 where the bypass flow path 55 branches off is formed, for example, by a joint that connects hoses together. The coolant flows into the bypass flow path 55 from the coolant flow path 53.

The bypass flow passage 55 is provided with a bypass valve 56. The bypass flow passage 55 includes a first bypass flow passage 55a that connects the first cooling liquid flow passage 53a and the bypass valve 56, and a second bypass flow passage 55b that connects the bypass valve 56 and the tank 50.

The bypass valve 56 is driven by compressed air, i.e., opens and closes. Like the coolant valve 54, the bypass valve 56 opens when compressed air is supplied and closes when compressed air is cut off. The bypass valve 56 is a so-called airless-close valve or a normally-closed valve. As will be described in detail later, the bypass valve 56 is closed when the coolant is discharged. It also opens when the coolant flow path 53 is depressurized, which will be described later.

Coolant flows through the coolant flow path 53 and the bypass flow path 55. The coolant is generally oil, and may be ignited by electricity. The coolant valve 54 and the bypass valve 56 are driven by compressed air, not electricity, and therefore the safety of the machine tool can be improved. The coolant may contain foreign matter such as cutting chips. The foreign matter may adhere to or accumulate on at least one of the coolant valve 54 and the bypass valve 56. The coolant valve 54 and the bypass valve 56 are opened and closed by compressed air, so the opening and closing forces of the coolant valve 54 and the bypass valve 56 are large. Therefore, even if foreign matter adheres to or accumulates on the coolant valve 54, the coolant valve 54 can be opened and closed easily. Even if foreign matter adheres to or accumulates on the bypass valve 56, the bypass valve 56 can be opened and closed easily. For example, the opening and closing force of an electromagnetic valve is smaller than that of a valve that opens and closes by compressed air. Therefore, if the coolant valve 54 is an electromagnetic valve, the coolant valve 54 may not be able to open or close when foreign matter adheres to or accumulates on the coolant valve 54. If the bypass valve 56 is an electromagnetic valve, the bypass valve 56 may not be able to open or close when foreign matter adheres to or accumulates on the bypass valve 56.

The machine tool includes a first drive unit that drives the coolant valve 54 when discharging the coolant, and a second drive unit that drives the coolant valve 54 when depressurizing the coolant flow path 53. The first drive unit includes a solenoid valve 70 connected to a supply device 6 that supplies compressed air, and a first compressed air flow path 72 that connects the solenoid valve 70 and the coolant valve 54. Details of the second drive unit will be described later.

The supply device 6 is, for example, a compressor. The supply device 6 is installed, for example, in a factory where a machine tool is installed. The supply device 6 is connected to an electromagnetic valve 70 via a compressed air supply flow path 75 for supplying compressed air. The supply device 6 is also connected to a valve body 71 (described below) via a compressed air supply flow path 76 for supplying compressed air. Compressed air flows through the compressed air supply flow path 75 and the compressed air supply flow path 76.

The first compressed air flow path 72 is formed, for example, by a hose. Compressed air flows through the first compressed air flow path 72. The control device 17 controls the opening and closing of the solenoid valve 70. When the solenoid valve 70 is opened, the supply device 6 supplies compressed air to the cooling liquid valve 54 via the compressed air supply flow path 75, the solenoid valve 70, and the first compressed air flow path 72. The supply of compressed air opens the cooling liquid valve 54. Therefore, when the solenoid valve 70 is opened, the cooling liquid valve 54 opens. When the solenoid valve 70 is closed, the supply of compressed air from the supply device 6 to the cooling liquid valve 54 via the compressed air supply flow path 75, the solenoid valve 70, and the first compressed air flow path 72 is blocked. Therefore, when the solenoid valve 70 is closed, the cooling liquid valve 54 is closed.

The solenoid valve 70 opens and closes to control the supply and cut-off of compressed air to the coolant valve 54, i.e., the supply and cut-off of compressed air to the coolant valve 54. The first drive unit opens and closes the coolant valve 54 by opening and closing the solenoid valve 70. Since the solenoid valve 70 has excellent responsiveness in opening and closing, it is possible to more quickly switch between supplying and cutting off compressed air to the coolant valve 54. This makes it possible to improve the responsiveness in opening and closing the coolant valve 54.

The machine tool includes a bypass valve drive unit that drives the bypass valve 56. The bypass valve drive unit includes a valve body 71 and a second compressed air flow path 73 that connects the valve body 71 and the bypass valve 56. The valve body 71 is, for example, a manual valve. As described above, the valve body 71 is connected to the supply device 6 via the compressed air supply flow path 76.

A third compressed air flow path 74 branches off from the second compressed air flow path 73. Compressed air flows through the second compressed air flow path 73 and the third compressed air flow path 74. The second compressed air flow path 73 and the third compressed air flow path 74 are formed, for example, by hoses. The third compressed air flow path 74 branches off from the second compressed air flow path 73 and is connected to the first compressed air flow path 72. In other words, the third compressed air flow path 74 connects the first compressed air flow path 72 and the second compressed air flow path 73.

A check valve 77 is provided in the third compressed air flow path 74. The check valve 77 regulates the flow of compressed air from the first compressed air flow path 72 to the second compressed air flow path 73 via the third compressed air flow path 74. In other words, because the check valve 77 is provided, compressed air flows from the second compressed air flow path 73 to the first compressed air flow path 72 via the third compressed air flow path 74, but does not flow from the first compressed air flow path 72 to the second compressed air flow path 73 via the third compressed air flow path 74.

When the valve body 71 opens, compressed air flows through the second compressed air flow path 73 via the compressed air supply flow path 76 and the valve body 71. Therefore, when the valve body 71 opens, the supply device 6 supplies compressed air to the bypass valve 56 via the compressed air supply flow path 76, the valve body 71, and the second compressed air flow path 73. Furthermore, the supply device 6 supplies compressed air to the cooling liquid valve 54 via the compressed air supply flow path 76, the valve body 71, the second compressed air flow path 73, the third compressed air flow path 74, and the first compressed air flow path 72. The bypass valve 56 and the cooling liquid valve 54 open when compressed air is supplied. Therefore, when the valve body 71 opens, the bypass valve 56 and the cooling liquid valve 54 open.

When the valve body 71 is closed, it blocks the supply of compressed air from the supply device 6 to the bypass valve 56. Furthermore, the valve body 71 blocks the supply of compressed air to the coolant valve 54 via the compressed air supply flow path 76, the valve body 71, the second compressed air flow path 73, the third compressed air flow path 74, and the first compressed air flow path 72. Therefore, when the valve body 71 is closed, the bypass valve 56 and the coolant valve 54 are closed.

The valve body 71 opens and closes to control the supply and interruption of compressed air to the bypass valve 56. In other words, the bypass valve drive unit controls the supply and interruption of compressed air to the bypass valve 56 by opening and closing the valve body 71, thereby opening and closing the bypass valve 56.

The valve body 71 opens and closes to control the supply and cut-off of compressed air to the bypass valve 56 as well as the supply and cut-off of compressed air to the coolant valve 54. Therefore, when the solenoid valve 70 is closed, both the coolant valve 54 and the bypass valve 56 can be opened by opening the valve body 71. Also, both the coolant valve 54 and the bypass valve 56 can be closed by closing the valve body 71. In other words, both the coolant valve 54 and the bypass valve 56 can be opened and closed by opening and closing the valve body 71 once. Since the valve body 71 is a manual valve, even if the control device 17 breaks down, for example, the operator who operates the machine tool can open and close the valve body 71 to open and close the coolant valve 54 and the bypass valve 56. For example, the operator opens and closes the valve body 71 to open and close the coolant valve 54 and the bypass valve 56 when depressurizing the coolant flow path 53, which will be described later. The second drive unit includes the valve body 71, the second compressed air flow path 73, the third compressed air flow path 74, the check valve 77, and the first compressed air flow path 72.

The discharge of the coolant and depressurization are explained below. Before the machine tool discharges the coolant from the discharge port 30b, for example before the machine tool starts machining the workpiece, the solenoid valve 70 and the valve body 71 are closed. Therefore, the coolant valve 54 and the bypass valve 56 are closed. The supply device 6 is already started.

When the machine tool discharges coolant from the discharge port 30b, for example when the machine tool processes a workpiece, the first drive unit opens the coolant valve 54. More specifically, the control device 17 opens the solenoid valve 70. The supply device 6 supplies compressed air to the coolant valve 54 via the compressed air supply passage 75, the solenoid valve 70, and the first compressed air passage 72, so that the coolant valve 54 opens. For example, the control device 17 starts the pump 51 when opening the solenoid valve 70. The pump 51 supplies the coolant stored in the tank 50 to the spindle passage 25 via the coolant passage 53. The machine tool discharges the coolant from the discharge port 30b.

For example, a recovery device (not shown) provided on the machine tool recovers the discharged cooling liquid into tank 50. The machine tool reuses the discharged cooling liquid. For example, the recovery device includes a filtration device that removes chips from the discharged cooling liquid by filtration. Also, unlike pump 51, the recovery device includes a pump that sends the filtered cooling liquid to tank 50. For example, the above-mentioned foreign matter includes small chips that could not be removed by the filtration device.

When the machine tool finishes discharging the coolant, for example when the machine tool finishes machining the workpiece, the first drive unit closes the coolant valve 54. More specifically, the control device 17 closes the solenoid valve 70. Closing the solenoid valve 70 closes the coolant valve 54. The control device 17 stops the pump 51, for example, when closing the solenoid valve 70.

The coolant flow path 53 contains pressurized coolant discharged by the pump 51. For example, if the pump 51 has a structure for preventing backflow, such as a structure for restricting reverse rotation of the pump 51, or a backflow check valve, pressurized coolant remains in the first coolant flow path 53a and the first bypass flow path 55a. Therefore, the internal pressure of the first coolant flow path 53a and the first bypass flow path 55a is higher than the internal pressure of the tank 50, such as a pressure equal to atmospheric pressure. The same applies when the pump 51 does not have a structure for preventing backflow and the pressure loss in the coolant flow path 53 caused by the pump 51 is large.

The operator opens the valve body 71. The supply device 6 supplies compressed air to the bypass valve 56 via the compressed air supply passage 76, the valve body 71, and the second compressed air passage 73. It also supplies compressed air to the coolant valve 54 via the compressed air supply passage 76, the valve body 71, the second compressed air passage 73, the third compressed air passage 74, and the first compressed air passage 72. Therefore, the bypass valve 56 and the coolant valve 54 are open.

The cooling liquid remaining in the first cooling liquid flow passage 53a and the first bypass flow passage 55a flows out of the discharge port 30b through the cooling liquid valve 54, the second cooling liquid flow passage 53b, the spindle flow passage 25, and the tool flow passage 33. Also, due to the pressure difference between the internal pressure of the first cooling liquid flow passage 53a and the first bypass flow passage 55a and the internal pressure of the tank 50, the cooling liquid flows into the tank 50 through the bypass flow passage 55. The internal pressure of the first cooling liquid flow passage 53a and the first bypass flow passage 55a drops from a pressure higher than the internal pressure of the tank 50 to, for example, the same pressure as atmospheric pressure. By opening the valve body 71, the operator can depressurize the first cooling liquid flow passage 53a and the first bypass flow passage 55a, that is, depressurize the cooling liquid flow passage 53 and the bypass flow passage 55. After depressurizing the cooling liquid flow passage 53 and the bypass flow passage 55, the operator closes the valve body 71 to close the cooling liquid valve 54 and the bypass valve 56. As described above, the cooling liquid valve 54 opens and closes by opening and closing the valve body 71 when depressurizing the cooling liquid flow path 53. That is, the cooling liquid valve 54 opens and closes by the second drive unit when depressurizing the cooling liquid flow path 53. The recovery device described above recovers the cooling liquid that flows out from the discharge port 30b into the tank 50.

For example, instead of opening the valve body 71, the operator may operate the control device 17 via an operating unit (not shown) provided on the machine tool to open the solenoid valve 70. The supply device 6 supplies compressed air to the coolant valve 54 via the solenoid valve 70 and the first compressed air flow path 72. Since the coolant valve 54 opens, the coolant remaining in the first coolant flow path 53a and the first bypass flow path 55a flows out of the discharge port 30b via the coolant valve 54, the second coolant flow path 53b, the spindle flow path 25, and the tool flow path 33. The coolant flow path 53 and the bypass flow path 55 can be depressurized. In this case, the second drive unit includes the solenoid valve 70 and the first compressed air flow path 72.

There is a risk that the tool passage 33 may become clogged due to chips generated during machining of the workpiece. If the tool passage 33 becomes clogged, pressurized coolant remains in the second coolant passage 53b, the spindle passage 25, and the tool passage 33 in addition to the first coolant passage 53a and the first bypass passage 55a. Therefore, the internal pressure of the second coolant passage 53b, the spindle passage 25, and the tool passage 33 is higher than the internal pressure of the tank 50.

For example, when a tool 3 not having a tool passage 33 is attached to the spindle 2, there is a risk that pressurized coolant may remain in the second coolant passage 53b and the spindle passage 25 in addition to the first coolant passage 53a and the first bypass passage 55a. Therefore, the internal pressure of the first coolant passage 53a and the spindle passage 25 is higher than the internal pressure of the tank 50. Hereinafter, the passages between the first coolant passage 53a, the spindle passage 25, and the tool passage 33, and the passages between the first coolant passage 53a and the spindle passage 25 will be referred to as passages such as the spindle passage 25 without distinction.

When the operator opens the valve body 71, the coolant valve 54 and the bypass valve 56 open. The coolant remaining in the spindle passage 25 and other passages flows into the tank 50 via the bypass passage 55 due to the pressure difference between the internal pressure of the spindle passage 25 and other passages and the internal pressure of the tank 50. Therefore, by opening the valve body 71, in addition to depressurizing the first coolant passage 53a and the first bypass passage 55a, it is possible to depressurize the passages such as the spindle passage 25. Therefore, it is possible to prevent the coolant from spraying out of the spindle passage 25 and the tool passage 33 when removing the tool 3.

When the coolant can flow back through the coolant flow passage 53 and the coolant supply flow passage 52, for example, when the pump 51 can rotate in reverse, the remaining coolant may flow into the tank 50 through the pump 51 and the coolant supply flow passage 52. The remaining coolant includes the coolant remaining in the first coolant flow passage 53a and the first bypass flow passage 55a, or the coolant remaining in the first coolant flow passage 53a, the first bypass flow passage 55a, the spindle flow passage 25, and other flow passages. For example, when the coolant remains in the first coolant flow passage 53a, the first bypass flow passage 55a, the spindle flow passage 25, and other flow passages, the operator opens the solenoid valve 70 as described above. Thus, the coolant valve 54 opens. The coolant remaining in the flow passages such as the spindle flow passage 25 flows into the tank 50 through the coolant supply flow passage 52 together with the coolant remaining in the first coolant flow passage 53a and the first bypass flow passage 55a. Thus, the coolant flow passage 53 and the bypass flow passage 55 can be depressurized. It is also possible to depressurize flow paths such as the main shaft flow path 25.

After the machine tool has finished machining the workpiece, the worker removes the coolant flow path 53 from the machine tool, for example, for maintenance of the machine tool. The worker also removes the bypass flow path 55 from the machine tool. For example, the worker removes the second coolant flow path 53b from at least one of the spindle flow path 25 and the coolant valve 54. The worker also removes the first coolant flow path 53a from at least one of the coolant valve 54 and the pump 51. The worker also removes the first bypass flow path 55a from at least one of the first coolant flow path 53a and the bypass valve 56.

As described above, the coolant flow passage 53 and the bypass flow passage 55 are depressurized. Therefore, when the coolant flow passage 53 is removed, there is no risk of the coolant spraying out of the coolant flow passage 53. When the bypass flow passage 55 is removed, there is no risk of the coolant spraying out of the bypass flow passage 55. That is, when the worker opens the valve body 71, the coolant can be prevented from spraying out of the coolant flow passage 53 when the coolant flow passage 53 is removed. In addition, when the bypass flow passage 55 is removed, the coolant can be prevented from spraying out of the bypass flow passage 55. For example, if the coolant sprays out of the coolant flow passage 53 or the bypass flow passage 55 during the above removal, there is a high risk of the sprayed coolant splashing on the worker or around the machine tool, so there is a high risk of removing the coolant flow passage 53 or the bypass flow passage 55.

For example, when removing the bypass flow path 55, the worker removes the second bypass flow path 55b from at least one of the bypass valve 56 and the tank 50. Since no pressurized cooling liquid remains in the second bypass flow path 55b, no cooling liquid will spray out from the second bypass flow path 55b when the second bypass flow path 55b is removed.

For example, an operator removes the coolant supply passage 52 from at least one of the pump 51 and the tank 50 to perform maintenance on a machine tool. Since no pressurized coolant remains in the coolant supply passage 52, no coolant will spray out of the coolant supply passage 52 when the coolant supply passage 52 is removed.

Even after depressurization, there is a risk that coolant may remain in at least one of the coolant flow passage 53, the bypass flow passage 55, the spindle flow passage 25, and the tool flow passage 33. Therefore, when removing the coolant flow passage 53, there is a risk that coolant may drip from the coolant flow passage 53. When removing the bypass flow passage 55, there is a risk that coolant may drip from the bypass flow passage 55. However, since the coolant flow passage 53 and the bypass flow passage 55 have been depressurized, the coolant does not gush out from the coolant flow passage 53 when removing the coolant flow passage 53. Furthermore, when removing the bypass flow passage 55, the coolant does not gush out from the bypass flow passage 55. Therefore, even if coolant remains after depressurization, there is little risk in removing the coolant flow passage 53 or the bypass flow passage 55.

The machine tool may be equipped with a pressure sensor that detects the internal pressure of the cooling liquid passage 53. For example, the pressure sensor detects the internal pressure of the second cooling liquid passage 53b. For example, if the detection value of the pressure sensor after the end of the cooling liquid discharge is equal to or greater than a predetermined value, the control device 17 determines that pressurized cooling liquid remains in the passages such as the spindle passage 25. In addition, the control device 17 notifies the operator that cooling liquid remains in the passages such as the spindle passage 25. For example, the control device 17 notifies by an alarm. Upon hearing the alarm, the operator opens the valve body 71. The pressure sensor may detect the internal pressure of the spindle passage 25.

(Modification)
4 is a circuit diagram showing a circuit related to a cooling liquid and compressed air of a machine tool according to a modified example. In the configuration according to the modified example, components similar to those in the first embodiment are given the same reference numerals, and detailed description thereof will be omitted.

In the modified machine tool, a solenoid valve 78 is provided instead of the valve body 71 of the first embodiment. The solenoid valve 78 is a solenoid valve different from the solenoid valve 70. The control device 17 controls the opening and closing of the solenoid valve 78. The compressed air supply flow path 76 connects the supply device 6 and the solenoid valve 78. The second compressed air flow path 73 connects the solenoid valve 78 and the bypass valve 56.

For example, when depressurizing the cooling liquid flow path 53 and the bypass flow path 55, an operator operates the control device 17 via an operation unit (not shown) provided on the machine tool to open the solenoid valve 78. The supply device 6 supplies compressed air to the bypass valve 56 via the compressed air supply flow path 76, the solenoid valve 78, and the second compressed air flow path 73. It also supplies compressed air to the cooling liquid valve 54 via the compressed air supply flow path 76, the solenoid valve 78, the second compressed air flow path 73, the third compressed air flow path 74, and the first compressed air flow path 72. The bypass valve 56 and the cooling liquid valve 54 open when compressed air is supplied. Therefore, the cooling liquid flow path 53 and the bypass flow path 55 can be depressurized by opening the solenoid valve 78.

In the modified machine tool, the second drive unit includes a solenoid valve 78, a second compressed air flow path 73, a third compressed air flow path 74, a check valve 77, and a first compressed air flow path 72. The bypass valve drive unit includes a solenoid valve 78 and a second compressed air flow path 73.

For example, the control device 17 may open the solenoid valve 78 each time the machine tool finishes discharging the coolant or each time the machine tool finishes machining the workpiece. The machine tool may be equipped with a pressure sensor that detects the internal pressure of the coolant flow path 53. For example, the pressure sensor detects the internal pressure of the second coolant flow path 53b. For example, if the detection value of the pressure sensor after the coolant discharge is finished is equal to or greater than a predetermined value, the control device 17 determines that pressurized coolant remains in the flow paths such as the spindle flow path 25. In addition, the solenoid valve 78 is opened to release the pressure from the coolant flow path 53 and the bypass flow path 55. The pressure sensor may detect the internal pressure of the spindle flow path 25.

The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents to the scope of the claims.

REFERENCE SIGNS LIST 1 Machine tool body 2 Spindle 25 Spindle flow passage 3 Tool 33 Tool flow passage 50 Tank 51 Pump 53 Coolant flow passage 54 Coolant valve 55 Bypass flow passage 56 Bypass valve 6 Supply device 70 Solenoid valve 71 Valve body 72 First compressed air flow passage 73 Second compressed air flow passage 74 Third compressed air flow passage 77 Check valve

Claims (6)

A machine tool that discharges a cooling liquid from a tool attached to a spindle,
A tank for storing the cooling liquid;
a pump for supplying the cooling liquid stored in the tank;
a coolant flow path that connects a spindle flow path provided in the spindle and the pump and through which the coolant flows;
a coolant valve provided in the coolant flow path;
a bypass flow path that branches off from the coolant flow path between the pump and the coolant valve and is connected to the tank;
a bypass valve provided in the bypass flow path;
a first drive unit that opens the coolant valve when the coolant is discharged;
a second drive unit that opens the coolant valve and the bypass valve when depressurizing the coolant flow path,
The machine tool, wherein the spindle passage is connected to a tool passage provided in the tool. The second drive unit includes a bypass valve drive unit that drives the bypass valve.
2. The machine tool according to claim 1. the coolant valve and the bypass valve are driven by compressed air;
The machine tool according to claim 2 , wherein the bypass valve driving unit controls supply and cut-off of the compressed air to the bypass valve. 4. The machine tool according to claim 3, wherein the first drive unit is connected to a supply device that supplies the compressed air and includes an electromagnetic valve that controls the supply and cut-off of the compressed air to the coolant valve. the first drive unit includes a first compressed air flow path that connects the coolant valve and the solenoid valve and through which the compressed air flows,
The bypass valve driving unit is
A valve body connected to the supply device;
a second compressed air flow path connecting the valve body and the bypass valve and through which the compressed air flows,
The second drive unit is
a third compressed air flow path branching from the second compressed air flow path and connecting to the first compressed air flow path;
and a check valve provided in the third compressed air flow path. A method for releasing pressure in a machine tool that discharges a coolant from a tool attached to a spindle, comprising the steps of:
a coolant valve provided in a coolant flow passage connecting a pump for supplying the coolant stored in a tank and a spindle flow passage provided in the spindle is opened by a first drive unit when the coolant is discharged;
a bypass valve provided in a bypass flow path that branches off from a portion between the pump and the coolant valve in the coolant flow path and connects to the tank, the bypass valve being driven by a second drive unit when depressurizing the coolant flow path.

Images