Machine tool

Abstract

A machine tool (1) includes: a cutting fluid supply unit (7) that supplies cutting fluid discharged from the tip of a tool mounted on a spindle (3); a detection unit (9) that detects information for determining that the cutting fluid has reached the tip of the tool; and a control unit that determines the arrival of the cutting fluid based on the information detected by the detection unit (9) and controls the cutting fluid supply unit (7). The control unit causes the supply speed of the cutting fluid from the start of the supply of the cutting fluid by the cutting fluid supply unit (7) until the arrival of the cutting fluid is determined to be higher than the supply speed after the determination is made.

Description

Technical Field

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

[0002] Conventionally, a machine tool has been known which supplies cutting fluid to the tip of a tool through the central axis of the tool (for example, see Patent Document 1).

[0003] In this machine tool, supply conditions are stored in advance for each tool, and the supply conditions are such that the cutting fluid supply amount during the initial operation time when starting the machining operation is larger than the cutting fluid supply amount during the subsequent stable operation time.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2001-334438 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] In the case where supply conditions are stored for each tool and are stored separately according to whether the tool is newly used or used, the more tools are used, the greater the labor required for setting operations. In addition, even when the same tool is used, when the type of cutting fluid is changed or when the temperature of the cutting fluid changes, the viscosity of the cutting fluid changes, and therefore, even for the same time, the supplied cutting fluid supply amount changes.

[0009] Therefore, it is desired to reduce the labor required for setting the cutting fluid supply amount and to be able to quickly supply an appropriate amount of cutting fluid even when various conditions change.

[0010] Means for Solving the Problems

[0011] One aspect of the present invention is a machine tool including: a cutting fluid supply unit that supplies cutting fluid discharged from the tip of a tool mounted on a spindle; a detection unit that detects information for determining that the cutting fluid has reached the tip of the tool; and a control unit that determines that the cutting fluid has reached based on the information detected by the detection unit and controls the cutting fluid supply unit, and the control unit makes the supply speed of the cutting fluid from the start of the supply of the cutting fluid by the cutting fluid supply unit until the determination that the cutting fluid has reached higher than the supply speed after the determination.

[0012] According to the above configuration, even when conditions change, it is possible to quickly supply cutting fluid to the tip of the tool. Brief Description of the Drawings

[0013] Figure 1 It is an overall structure diagram of a machine tool showing an embodiment of the present invention.

[0014] Figure 2 It is to illustrate the setting in Figure 1 A longitudinal sectional view of the spindle, chuck, and tool flow path of the machine tool.

[0015] Figure 3 It is a longitudinal sectional view showing the state where the tool is installed in Figure 2 the chuck.

[0016] Figure 4 It schematically shows Figure 1 a block diagram of the machine tool.

[0017] Figure 5 It is to illustrate Figure 1 the relationship between the pressure value detected by the pressure sensor provided in the machine tool and the rotational speed of the pump.

[0018] Figure 6 It is Figure 5 a modified example, and it is a diagram illustrating the relationship between the flow rate value detected by the flow rate sensor and the rotational speed of the pump in the case where a flow rate sensor is installed instead of the pressure sensor.

[0019] The description of the reference numerals is as follows.

[0020] 1: Machine tool

[0021] 3: Spindle

[0022] 7: Pump (cutting fluid supply section)

[0023] 8: Pipe (flow path)

[0024] 9: Pressure sensor (detection section)

[0025] 10: Control section

[0026] 13: Through hole (flow path)

[0027] 15: Through hole (flow path)

[0028] 17: Air supply path (cutting fluid removal section)

[0029] 18: Air pressure source (cutting fluid removal section)

[0030] L: Cooling liquid (cutting fluid)

[0031] S: Tool Detailed implementation mode

[0032] Hereinafter, a machine tool 1 according to an embodiment of the present invention will be described with reference to the drawings.

[0033] As shown Figure 1 As shown in the figure, the machine tool 1 of the present embodiment includes: a worktable 2 that places a workpiece and moves the workpiece in the horizontal direction; a spindle 3 that rotatably supports a tool S for machining the workpiece in a detachable manner; a lifting mechanism 4 that moves the spindle 3 in the vertical direction; and a turret 5 that supports a plurality of tools S in a replaceable manner.

[0034] In addition, the machine tool 1 includes: a coolant tank 6 that stores coolant (cutting fluid) L; a pump (cutting fluid supply unit) 7 that sucks the coolant L in the coolant tank 6; and a pipe (flow path) 8 that connects the pump 7 and the spindle 3. In addition, the machine tool 1 includes: a pressure sensor (detection unit) 9 that detects the pressure (information) in the pipe 8; and a control unit 10 that controls the pump 7 based on the pressure detected by the pressure sensor 9.

[0035] As shown Figure 2 As shown in the figure, the spindle 3 includes: a chuck 11 that has a tool changing mechanism at its lower end; and a motor 12 that rotationally drives the chuck 11 around a vertical axis. A through hole (flow path) 13 that penetrates vertically is provided at the center of the chuck 11 and the rotor 12a of the motor 12. At the upper end of the through hole 13 of the rotor 12a, a pipe 8 for supplying the coolant L to the through hole 13 is connected by a rotary joint 14.

[0036] A through hole (flow path) 15 that penetrates from the front end to the base end of the tool S along the central axis is also provided in the tool S mounted on the chuck 11. As shown Figure 3 As shown in the figure, when the tool S is mounted on the chuck 11, the through hole 15 of the tool S is connected to the through hole 13 of the chuck 11. Thus, the coolant L supplied via the pipe 8 is discharged from the front end of the tool S via the through hole 13 of the chuck 11 and the through hole 15 of the tool S.

[0037] As shown Figure 4 As shown in the figure, a first one-way valve 16 and an air supply passage (cutting fluid removal unit) 17 are provided in the pipe 8. The first one-way valve 16 allows the coolant L to flow from the pump 7 toward the rotary joint 14 and prohibits backflow. The air supply passage (cutting fluid removal unit) 17 supplies pressurized air between the first one-way valve 16 and the rotary joint 14. A second one-way valve 19 and a solenoid valve 20 are provided in the air supply passage 17. The second one-way valve 19 allows the pressurized air to flow into the pipe 8 from the air pressure source (cutting fluid removal unit) 18 and prohibits backflow into the air supply passage 17. The solenoid valve 20 switches the supply and stop of the pressurized air from the air pressure source 18.

[0038] The pump 7 is a centrifugal pump capable of controlling the rotational speed.

[0039] The control unit 10 includes at least one processor and a memory. In the memory, a first rotational speed of the pump 7 when starting to supply the coolant L and a second rotational speed of the pump 7 during subsequent steady operation are stored. The first rotational speed is set to a value sufficiently larger than the second rotational speed, for example, twice as large.

[0040] In accordance with an instruction to start machining based on a pre-taught program, the control unit 10 rotates the pump 7 at the first rotational speed and monitors the pressure value detected by the pressure sensor 9 at a predetermined sampling time interval. And, as Figure 5 shown, at the moment when the pressure reaches a peak, the control unit 10 switches the rotational speed of the pump 7 to the second rotational speed and starts machining the workpiece. Thereby, while discharging the coolant L from the tip of the tool S, the workpiece can be machined using the tool S.

[0041] In addition, in accordance with an instruction to replace the tool S, the control unit 10 controls the solenoid valve 20 to supply pressurized air from the air supply passage 17 into the pipe 8. Thereby, pressurized air can be supplied to the flow paths 8, 13, 15 from the first one-way valve 16 to the tip of the tool S, and the coolant L remaining in the flow paths 8, 13, 15 can be discharged from the tip of the tool S.

[0042] After discharging the coolant L, the control unit 10 operates the turret 5 to replace the tool S.

[0043] Thus, according to the machine tool 1 of the present embodiment, before replacing the tool S, the coolant L remaining in the through holes 13 in the spindle 3 and the through hole 15 of the tool S is removed from the pipe 8. Thereby, it is possible to prevent the coolant L from adhering to the gripping surface of the chuck 11 from which the tool S has been removed and the outer surface such as the taper shank of the tool S removed from the chuck 11.

[0044] By preventing the coolant L from adhering to the gripping surface of the chuck 11 or the outer surface of the tool S, it is possible to prevent a decrease in the frictional force when installing the tool S on the chuck 11, and thus prevent the tool S from sliding relative to the chuck 11. In addition, it is possible to prevent poor installation of the tool S on the chuck 11 due to chips mixed in the coolant L, or poor conditions such as damage to the gripping surface of the chuck 11 and the outer surface of the tool S. Moreover, it is possible to suppress rust and abnormal wear due to the adhesion of the coolant L.

[0045] In addition, when installing a new tool S on the chuck 11, since no coolant L remains in the through holes 13, 15 of the spindle 3, the above-mentioned poor conditions do not occur, and the installation can be performed more reliably.

[0046] And, at the moment of installing a new tool S on the chuck 11, since the coolant L does not exist in the flow paths 8, 13, 15 from the first one-way valve 16 to the tip of the tool S, machining cannot be started immediately.

[0047] According to the present embodiment, since the pump 7 operates at a first rotational speed higher than the second rotational speed during stable operation according to the start machining instruction, the coolant L can quickly fill the empty flow paths 8, 13, and 15 and be discharged from the tip of the tool S to start machining. And after the coolant L is discharged from the tip of the tool S, by operating the pump 7 at the second rotational speed during stable operation which is lower than the first rotational speed, power consumption can be reduced, and the pressure of the coolant L can be reduced to relieve the load on each part.

[0048] In this case, according to the present embodiment, when it is determined, based on the detection result detected by the pressure sensor 9, that the coolant L is discharged from the tip of the tool S, the switching from the first rotational speed to the second rotational speed is performed. Thereby, even if the supply conditions of the cutting fluid change, such as a change in the tool S, a change in the type of the coolant L, or a change in the temperature of the coolant L, etc., the pump 7 can be driven at the higher first rotational speed until the coolant L is discharged from the tip of the tool S.

[0049] As a result, there are advantages as follows: There is no need to perform the operation of setting the supply conditions of the coolant L for each tool S, and even if the supply conditions change, the coolant L can be quickly discharged from the tip of the tool S, and machining can be quickly started using the tool S. In addition, after the coolant L is discharged from the tip of the tool S, the rotational speed of the pump 7 is reduced and it operates stably at the second rotational speed, so that power consumption can be reduced and the load on each part can be reduced.

[0050] In addition, in the machine tool 1 of the present embodiment, as the detection unit, a pressure sensor 9 that detects the pressure in the flow paths 8, 13, and 15 from the pump 7 to the tip of the tool S is adopted. The pressure sensor 9 can also be disposed at any position in the flow paths 8, 13, and 15. In addition, instead of the pressure sensor 9, a flow sensor can also be provided in the flow path near the discharge port of the pump 7. As Figure 6 shown, in the case of using a flow sensor, the control unit 10 only needs to accumulate the flow values sequentially sent from the flow sensor (the shaded part in the figure). And when the difference between the cumulative value of the flow values and the volume of the flow paths 8, 13, and 15 from the discharge port of the pump 7 to the tip of the tool S becomes equal to or less than a predetermined threshold value, the control unit 10 only needs to switch from the first rotational speed to the second rotational speed. In addition, a flow sensor may not be used, and the flow rate may be estimated based on the rotational speed and current value of the motor.

[0051] In addition, in the present embodiment, as the pump 7, a centrifugal pump capable of controlling the rotational speed is adopted, but instead, a metering pump capable of controlling the rotational speed can also be adopted.

[0052] In addition, in the present embodiment, as the coolant removal unit, pressurized air is supplied from the air supply passage 17 to the passages 8, 13, and 15 to discharge the coolant L in the passages 8, 13, and 15. However, instead of the air pressure source 18, a suction pump may also be used to suck and remove the coolant L in the passages 8, 13, and 15.

Claims

1. A machine tool, characterized in that, Comprising: A cutting fluid supply unit that supplies cutting fluid discharged from the tip of a tool mounted on a spindle; A detection unit that detects information for determining that the cutting fluid has reached the tip of the tool; And A control unit that determines that the cutting fluid has reached based on the information detected by the detection unit and controls the cutting fluid supply unit, The control unit makes the supply speed of the cutting fluid from the start of the supply of the cutting fluid by the cutting fluid supply unit until the determination that the cutting fluid has reached higher than the supply speed after the determination.

2. The machine tool according to claim 1, characterized in that The detection unit detects the pressure in the flow path connecting the cutting fluid supply unit and the tip of the tool, At the moment when the pressure detected by the detection unit becomes the peak value, the control unit determines that the cutting fluid has reached the tip of the tool.

3. The machine tool according to claim 1, characterized in that The detection unit detects the flow rate from the start of the supply of the cutting fluid by the cutting fluid supply unit, At the moment when the difference between the cumulative value of the flow rate detected by the detection unit and the volume of the flow path connecting the cutting fluid supply unit and the tip of the tool becomes equal to or less than a predetermined threshold value, the control unit determines that the cutting fluid has reached the tip of the tool.

4. The machine tool according to any one of claims 1 to 3, characterized in that The machine tool is provided with a cutting fluid removal unit that removes the cutting fluid in the flow path connecting the cutting fluid supply unit and the tip of the tool before replacing the tool.

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