JP6638915B2 - Spindle head elevating device and machine tool - Google Patents

Description

  The present invention relates to a spindle head elevating device and a machine tool. More specifically, the present invention relates to an electro-pneumatic hybrid type spindle head elevating device having an electric drive mechanism for elevating and lowering the spindle head, and a balance cylinder for bearing the weight of the spindle head, and a machine tool having the spindle head elevating device. .

In a machine tool, a spindle head elevating device for elevating and lowering a spindle head is used.
Conventionally, a drive mechanism mainly including an electric motor has been used for raising and lowering the spindle head.
In recent years, an electro-pneumatic hybrid type spindle head elevating device has been developed in which an air cylinder is added in parallel with a drive mechanism using an electric motor so that the weight of the spindle head is borne by the air cylinder.

  For example, in a machine tool, a spindle head is supported so as to be able to move up and down along a guide surface of a column, and an urging force corresponding to the weight of the spindle head is generated by a balance cylinder. 2. Description of the Related Art There is known a machine tool capable of smoothly moving up and down with a light force (see Patent Document 1).

In Patent Literature 1, a balance device that balances the weight of a spindle head with a balance cylinder reduces air from an air supply source to a predetermined pressure with a pressure reducing valve and then supplies the air to a balance cylinder to balance the weight of the spindle head with the balance. Let it. On the other hand, when the pressure in the control circuit increases, the relief valve operates, and the pressure in the control circuit is maintained at a predetermined pressure.
However, the balance device as disclosed in Patent Document 1 has a problem that the accuracy of the pressure reducing valve is not sufficient and the response speed is slow.

On the other hand, there has been proposed a spindle device and a machine tool capable of stabilizing a pressure change of a balance cylinder caused by a vertical movement of a spindle head with high speed and high accuracy (see Patent Document 2).
In Patent Document 2, extremely high precision and responsiveness are realized by performing pressure feedback control of a flow rate inside pressure feedback control using a pressure regulator with a flow rate control for pressure control of a balance cylinder.

  In the pressure regulator that controls the servo valve by such double feedback of the flow rate and the pressure, the pressure control is performed in response to a small change in the outflow flow rate downstream, that is, a small change in the balance cylinder. Thus, a control system that is resistant to disturbance and has high response can be configured. As a result, the pressure change of the balance cylinder caused by the vertical movement of the spindle head can be stabilized at high speed and with high accuracy.

JP-A-5-138419 JP 2013-99816 A

  However, when a pressure regulator that controls a servo valve by dual feedback of a flow rate and a pressure is used as a pressure regulator that controls a balance cylinder as in Patent Document 2 described above, extremely precise and high responsiveness can be obtained. In some cases, the pressure fluctuation at rest in the balance cylinder becomes large.

  This is because the pressure loop, that is, the air does not flow in the stationary state basically, does not function, so the inner loop of the double feedback does not function. As a result, the control becomes the same as the conventional control using only the feedback of the outer pressure, and the accuracy and the response to the pressure fluctuation cannot be sufficiently obtained.

Furthermore, since only feedback of pressure is performed in a stationary state, balance may be determined when the stop position of the balance cylinder deviates from the target position. When such a deviation from the target position occurs, it is necessary to perform a correction for returning to the target position by an electric drive mechanism that should originally be assisted by the balance cylinder.
That is, in order to maintain the expected stop position, it is necessary to continuously supply useless current, which is not desirable as an electropneumatic hybrid type spindle head elevating device.

  An object of the present invention is to provide an electro-pneumatic hybrid type spindle head elevating device and a machine tool capable of reducing pressure fluctuations at the time of standstill and driving and reducing current consumption for suppressing the pressure fluctuations.

A spindle head elevating device according to the present invention includes an electric drive mechanism that raises and lowers a spindle head of a machine tool, a balance cylinder that bears the weight of the spindle head, and a pressure adjustment device that controls the pressure of the balance cylinder. A spindle head elevating device, wherein the pressure adjusting device includes a pressure regulator for stabilizing the pressure of the pressurized gas from the pressurized gas source, and a main regulator for adjusting the pressure of the pressurized gas stabilized by the pressure regulator. Servo valve, having a control device for controlling the pressure regulator and the main servo valve, the control device has a main servo valve control unit for controlling the main servo valve, the main servo valve control unit, the a FF control unit that performs feedforward control of the main servo valve based on the current position of said balance cylinder, a target pressure of the balance cylinder rose Currently a PI controller for performing a proportional integral control based on the feedback pressure Sushirinda, that the relationship between the target pressure and the current pressure and a, and a control switching unit that switches the Disable Enable of the PI control unit It is characterized by.

In the present invention, basic pressure control of the balance cylinder is performed by the main servo valve. The control of the main servo valve is performed by feedforward control based on the current position of the balance cylinder by the FF control unit of the main servo valve control unit of the control device.
That is, since a system including a balance cylinder is modeled and a control amount set in advance according to the current position of the balance cylinder is used, pressure fluctuation such as feedback control that refers to the current pressure of the balance cylinder is avoided. can do.

In addition, the pressurized gas supplied to the main servo valve is not directly supplied from the pressurized gas source, but the pressure is regulated by a pressure regulator. When performing control, it is possible to accurately reproduce the prerequisite pressure conditions. By using a servo valve having high responsiveness and high accuracy as the main servo valve, for example, a nozzle flapper valve, the accuracy of feedforward control can be further improved.
As a result, pressure fluctuations during standstill and during driving can be reduced, and the reduction in pressure fluctuations eliminates the need for correction by the electric drive device, thereby reducing current consumption during stoppage.
As the main servo valve of the present invention, any pneumatic servo valve having sufficient responsiveness can be used. In addition to the above-described nozzle flapper valve, for example, a spool having a high dynamic characteristic of about several hundred Hz to 1 kHz can be used. A valve or a diaphragm valve may be used.

In the present invention, the switching condition of the control switching unit may be a case where the current pressure of the balance cylinder is lower than or equal to the target pressure.
In the present invention as described above, when the current pressure of the balance cylinder is insufficient with only the feedforward control, the additional supply of the pressurized gas can be performed by performing the proportional-integral control by the PI control unit.

That is, in a state where the current pressure of the balance cylinder is insufficient by the feedforward control alone, the spindle head cannot be supported by the insufficient pressure of the balance cylinder, and the pressure drops below the target position. In such a case, it is necessary to maintain the balance cylinder at the target position by assisting with the electric drive mechanism and pushing up the balance cylinder.
However, in the present invention, the pressurized gas is additionally supplied by the PI control unit, the current pressure of the balance cylinder for maintaining the balance cylinder at the target position can be recovered, and the assistance by the electric drive mechanism is eliminated. can do.

If the current pressure of the balance cylinder becomes excessive only by the feedforward control, the electric drive mechanism assists to push down the balance cylinder.
In such a case, a case where the current pressure of the balance cylinder is higher than the target pressure may be added as a switching condition of the control switching unit, and the assistance by the electric drive mechanism may be eliminated.
However, in order to avoid pressure fluctuations due to feedback control, a setting is made to prevent the PI control unit from being effective under all pressure conditions, such as switching to feed-forward control only when the balance cylinder is near the target position. It is desirable.

In the spindle head elevating device according to the present invention, it is preferable that the main servo valve is a nozzle flapper valve.
In the present invention, by using the nozzle flapper valve as the main servo valve, high responsiveness, that is, high-speed operation, and high accuracy can be obtained.

  In the spindle head elevating device of the present invention, the pressure regulator is a servo valve that adjusts a pressure of the pressurized gas from the pressurized gas source, and a flow sensor that detects a flow rate of the pressurized gas from the servo valve. An isothermal chamber for temporarily storing the pressurized gas from the flow rate sensor, and a pressure sensor for detecting the pressure of the pressurized gas from the isothermal chamber, the control device, the flow rate value from the flow rate sensor and the It is desirable to have a pressure regulator controller that controls the servo valve of the pressure regulator with a double feedback loop based on the pressure value from the pressure sensor.

  According to the present invention, the pressurized gas introduced into the main servo valve can be stabilized at a constant pressure by the pressure regulator. In particular, in the pressure regulator control unit that controls the pressure regulator, the servo valve of the pressure regulator is controlled by a double feedback loop based on the flow value from the flow sensor and the pressure value from the pressure sensor. Stabilization can be performed. As a result, the feed-forward control in the main servo valve can function more effectively.

A machine tool according to the present invention includes the above-described spindle head elevating device according to the present invention.
In such a machine tool of the present invention, it is possible to obtain the same effects as described in the spindle head elevating device of the present invention described above.

  According to the present invention, it is possible to provide an electropneumatic hybrid type spindle head elevating device and a machine tool capable of reducing pressure fluctuations at the time of standstill and driving and reducing current consumption for suppressing the pressure fluctuations.

FIG. 1 is a perspective view showing a machine tool according to an embodiment of the present invention. FIG. 4 is a side view showing the spindle head elevating device of the embodiment and its peripheral portion. FIG. 2 is a block diagram showing a pressure adjusting device of the embodiment. FIG. 2 is a block diagram showing a pressure regulator of the embodiment. FIG. 3 is a block diagram showing control of the pressure regulator of the embodiment. FIG. 2 is a block diagram showing a main servo valve of the embodiment. FIG. 3 is a block diagram showing control of a main servo valve of the embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The present embodiment is an example in which the present invention is applied to a machine tool including an electro-pneumatic hybrid type spindle head elevating device.

[Machine tool 1]
In FIG. 1, a machine tool 1 includes a table 13 on which a work W is placed, a base 10 supporting the table 13, a portal column 20 provided across the base 10 and the table 13, and a portal column 20. And a spindle device 30 supported by the horizontal beam 20A.

An X-axis guide mechanism 11 and an X-axis linear motor mechanism 12 are provided between the table 13 and the base 10, and the table 13 is movable in the X-axis direction with respect to the base 10.
The X-axis guide mechanism 11 includes a guide rail 11A disposed on the upper surface of the base 10 in parallel with the X-axis direction and a slide member 11B provided on the lower surface of the table 13 so as to be slidable along the guide rail 11A. It is comprised including.

  The X-axis linear motor mechanism 12 includes a magnet 12A arranged in parallel with the guide rails 11A on the upper surface of the base 10 and a coil 12B attached to the lower surface of the table 13 with a gap between the magnets 12A. And a linear motor.

The spindle device 30 has a saddle 33, and a Y-axis guide mechanism 21 and a Y-axis linear motor mechanism 22 are installed between the saddle 33 and the horizontal beam 20A. It is movable in the axial direction.
As shown in FIG. 2, the Y-axis guide mechanism 21 includes a guide rail 21 </ b> A arranged parallel to each other along the Y-axis direction on the upper surface of the horizontal beam 20 </ b> A of the portal column 20 and a guide And a slide member 21B slidably provided along the rail 21A.

  The Y-axis linear motor mechanism 22 includes a magnet 22A arranged in parallel with the guide rails 21A on the upper surface of the horizontal beam 20A of the portal column 20, and a lower surface of the spindle device 30 with a gap between the magnets 22A. It is constituted by a linear motor including the attached coil 22B.

The spindle device 30 has a spindle head 43 on one side of the saddle 33 and a balance weight 47 on the opposite side.
The spindle head 43 has a spindle head main body 51, a spindle 52 rotatably supported by the spindle head main body 51, and a rotation drive source 53 for driving the spindle 52 to rotate. A tool 54 is detachably attached to the main shaft 52. The rotation drive source 53 is configured by an electric motor.

[Spindle head elevating device 40]
In order to move the spindle head 43 up and down with respect to the saddle 33, the spindle device 30 includes a spindle head elevating device 40.
The spindle head lifting / lowering device 40 is of an electro-pneumatic hybrid type, has a Z-axis guide mechanism 41 and a Z-axis linear motor mechanism 42 (electric drive mechanism), a balance cylinder 44 that bears the weight of the spindle head 43, and a pressure adjustment. An apparatus 46 and an air supply 45 are provided.

A Z-axis guide mechanism 41 and a Z-axis linear motor mechanism 42 are provided between the spindle head 43 and the saddle 33, and the spindle head 43 can be driven to move up and down in the Z-axis direction with respect to the saddle 33.
The Z-axis guide mechanism 41 includes a guide rail 41A disposed parallel to each other on the back surface of the spindle head 43 along the Z direction, and a slide member 41B fixed to the front of the saddle 33 and slidably guiding the guide rail 41A. It is comprised including.

  The Z-axis linear motor mechanism 42 includes a magnet 42A arranged in parallel with guide rails 41A on the back surface of the spindle head 43, and a coil 42B attached to the front of the saddle 33 with a gap between the magnets 42A. And a linear motor including: The periphery of the coil 42B is covered with a heat shielding member 42C. The heat shielding member 42C is formed in a box shape using a material such as aluminum or plastics.

The balance cylinders 44 are arranged as a pair on both sides of the spindle head 43 and are installed in parallel with the Z-axis guide mechanism 41 and the Z-axis linear motor mechanism 42.
Each of the pair of balance cylinders 44 has a cylinder main body 44A whose upper end is supported by the saddle 33 via a bracket 55, and a piston which is slidably housed in the cylinder main body 44A at the upper end. And a piston rod 44B connected to the lower end.

The balance cylinder 44 generates an urging force for supporting at least a part of the weight of the spindle head 43. An air supply source is provided via a pressure adjusting device 46 in a lower chamber of the cylinder body 44A defined by the piston. Pressurized air from 45 is supplied.
In the balance cylinder 44, an urging force that balances the weight of the spindle head 43 is applied upward to the spindle head 43 by pressurized air supplied from the pressure adjusting device 46 and the air supply source 45.

In such a spindle head elevating device 40, the pressure of the balance cylinder 44 is controlled by the pressure adjusting device 46.
Hereinafter, pressure control of the balance cylinder 44 in the spindle head elevating device 40 of the present embodiment will be described.

[Pressure adjusting device 46]
In FIG. 3, a pressure regulator 46 includes a pressure regulator 70 for stabilizing the pressure of pressurized air (pressurized gas) from an air supply source 45 (pressurized gas source), and a pressure regulator stabilized by the pressure regulator 70. It has a main servo valve 80 for adjusting the pressure of the compressed air, and a control device 90 for controlling the pressure regulator 70 and the main servo valve 80.
The control device 90 stores a pressure regulator control unit 91 that controls the pressure regulator 70, a main servo valve control unit 92 that controls the main servo valve 80, and control data including a target pressure Pref of the balance cylinder 44. And a unit 93.

[Pressure regulator 70]
In FIG. 3, a pressure regulator 70 stabilizes pressurized air introduced into a main servo valve 80.
In FIG. 4, a pressure regulator 70 detects a servo valve 71 for adjusting the pressure of pressurized air (pressurized gas) from an air supply source 45 (pressurized gas source), and detects a flow rate of air from the servo valve 71. It has a flow sensor 72, an isothermal chamber 73 for temporarily storing the air from the flow sensor 72, and a pressure sensor 74 for detecting the pressure of the air from the isothermal chamber 73.

Although not shown, the isothermal chamber 73 is provided with a pressure differentiator (including a combination of a pressure gauge and a differential calculator) for detecting a pressure differential value dP / dt of the internal air.
As such a pressure regulator 70, for example, a pressure regulator disclosed in JP-A-2009-110033 can be used. However, a pressure regulator having another configuration may be used as long as the target pressure can be maintained at high speed and precisely and the performance is sufficient to stabilize the pressurized air introduced into the main servo valve 80.

[Pressure regulator control unit 91]
FIG. 5 shows a control block diagram of the pressure regulator control section 91.
The pressure regulator control unit 91 controls the pressure regulator 70 by a double feedback loop, outputs a command value Cr to the servo valve 71 of the pressure regulator 70, and sends the command value Cr to the main servo valve 80 via the isothermal chamber 73. The pressurized air is adjusted to the pressure Pr.

The pressure regulator control section 91 has a pressure loop 911 for feeding back the pressure Pr from the pressure sensor 74 and a flow loop 912 for feeding back the inflow flow rate Gin from the flow rate sensor 72.
The pressure loop 911 is a main feedback loop of the pressure regulator control section 91, and feeds back the pressure Pr of the air sent out from the isothermal chamber 73 detected by the pressure sensor 74 to the target pressure Pref. Performs integral control.
The flow rate loop 912 is set inside the pressure loop 911, and the flow rate Gin of the air flowing from the servo valve 71 into the isothermal chamber 73, the flow rate Gin of the air, and the differential pressure value dP / dt of the air in the isothermal chamber 73. The proportional integral control of the servo valve 71 is performed based on the outflow flow rate Gout of the air flowing out of the isothermal chamber 73 calculated based on the following equation.

  In such a pressure regulator control section 91, when the pressure Pr of the pressurized air sent from the pressure regulator 70 to the main servo valve 80 is the target pressure Pref, the servo valve 71 flows out of the outlet of the isothermal chamber 73. The opening is adjusted to balance the outflow flow rate Gout and the inflow flow rate Gin flowing from the inflow port.

Here, if the pressure Po of the air from the air supply source 45 fluctuates or the flow rate Gout of the air flowing out of the isothermal chamber 73 fluctuates, the pressure of the isothermal chamber 73 changes, and the pressure regulator The pressure Pr of the pressurized air sent from 70 to the main servo valve 80 also changes and deviates from the target pressure Pref.
On the other hand, the pressure regulator control unit 91 adjusts the opening of the servo valve 71 of the pressure regulator 70 by a double feedback loop, and causes air to flow into the isothermal chamber 73 at an inflow flow rate Gin according to the opening. . Thereby, the pressure Pr of the pressurized air sent from the isothermal chamber 73 to the main servo valve 80 can be returned to the target pressure Pref.

[Main servo valve 80]
3 and 6, the main servo valve 80 directly controls the pressure of the balance cylinder 44.
The main servo valve 80 is composed of a nozzle flapper valve with high responsiveness, that is, high-speed operation and high accuracy. As such a nozzle flapper valve, for example, a nozzle flapper type three-way valve AS110-135 (35L) manufactured by PSC Corporation can be used.
The main servo valve 80 is not limited to the nozzle flapper valve, but may be another type of servo valve as long as high speed and high accuracy similar to those of the nozzle flapper valve can be obtained.

[Main servo valve control unit 92]
In FIG. 6, a main servo valve control unit 92 controls the main servo valve 80, outputs a command value Cs to the main servo valve 80, and outputs pressurized air sent from the main servo valve 80 to the balance cylinder 44. The pressure is adjusted to Ps.
The control in the main servo valve control section 92 is mainly feedforward control, and is configured to combine proportional-integral control according to conditions.
For this purpose, the main servo valve control unit 92 includes an FF control unit 921, a PI control unit 922, and a control switching unit 923.

The FF control unit 921 performs feedforward control of the main servo valve 80 based on the current position Xc of the balance cylinder 44.
The PI control unit 922 performs proportional-integral control based on the target pressure Pref of the balance cylinder 44 and the feedback of the current pressure Pc of the balance cylinder 44.
The control switching unit 923 switches the validity / invalidity of the PI control unit 922 from the relationship between the target pressure Pref and the current pressure Pc.

FIG. 7 shows a control block diagram of the main servo valve control unit 92.
In the main servo valve control unit 92, basically, feedforward control by the FF control unit 921 is performed.
First, when the pressure Pc of the balance cylinder 44 is higher than the target pressure Pref, the control switching unit 923 invalidates the PI control unit 922. As a result, the main servo valve control unit 92 performs feedforward control only by the FF control unit 921.
The feedforward control by the FF control unit 921 is an open loop control based on the current position Xc of the balance cylinder 44, and does not refer to the feedback of the pressure Pc of the balance cylinder 44.

On the other hand, when the pressure Pc of the balance cylinder 44 is equal to or lower than the target pressure Pref, the control switching unit 923 enables the PI control unit 922. As a result, the main servo valve controller 92 performs the feed-forward control by the FF controller 921 and the proportional-integral control by the PI controller 922.
That is, the feedforward control based on the current position Xc of the balance cylinder 44 is performed by the FF control unit 921, and the feedback of the pressure Pc of the balance cylinder 44 is referred to by the PI control unit 922, and the proportional integral control is performed. The control output is added and sent to the main servo valve 80 as a command value Cs.
The balance cylinder 44 can be controlled to the desired pressure Pc based on the target pressure Pref by the main servo valve control unit 92 and the main servo valve 80 as described above.

[Effects of Embodiment]
According to the present embodiment, the following effects can be obtained.
In the spindle head elevating device 40 of the present embodiment, basic pressure control of the balance cylinder 44 is performed by the main servo valve 80 of the pressure adjusting device 46. The control of the main servo valve 80 is performed by the FF control unit 921 of the main servo valve control unit 92 of the control device 90 by feedforward control based on the current position Xc of the balance cylinder 44.
That is, since a system including the balance cylinder 44 is modeled and a control amount set in advance according to the current position of the balance cylinder 44 is used, feedback control such as referring to the current pressure Pc of the balance cylinder 44 is used. Pressure fluctuations can be avoided.

  Further, the pressurized air supplied to the main servo valve 80 is not directly supplied from the air supply source 45 but is stabilized by the pressure regulator 70 so that the pressure Pr is stabilized. When the feedforward control of the valve 80 is performed, the prerequisite pressure conditions can be accurately reproduced.

In this embodiment, the accuracy of feedforward control can be further improved by using a nozzle flapper valve having high responsiveness and high accuracy as the main servo valve 80.
As described above, in the present embodiment, it is possible to reduce the pressure fluctuations at the time of standstill and at the time of driving, and the correction by the Z-axis linear motor mechanism 42 which is an electric driving device is not required due to the reduction of the pressure fluctuations. Current consumption can be reduced.

  In the present embodiment, the main servo valve control unit 92 is provided with the FF control unit 921, the PI control unit 922 and the control switching unit 923 are provided, and the current pressure Pc of the balance cylinder 44 is lower than or equal to the target pressure Pref. With the feedforward control only by the FF control unit 921, when the current pressure Pc of the balance cylinder 44 is insufficient, the PI control unit 922 performs the proportional-integral control to additionally supply pressurized air to the balance cylinder 44, The current pressure Pc can be quickly returned to the target pressure Pref.

That is, when the current pressure Pc of the balance cylinder 44 is insufficient, the balance cylinder 44 cannot support the spindle head 43, and the current position Xc is lower than the target position. In such a case, it is necessary to maintain the balance cylinder 44 at the target position by supporting the Z-axis linear motor mechanism 42 and pushing up the balance cylinder 44.
However, in the present embodiment, additional supply of pressurized air is performed by the PI control unit 922, whereby the balance cylinder 44 can be returned to the target position, and the assistance by the Z-axis linear motor mechanism 42 is cancelled. Current can be reduced.

  In this embodiment, the pressure regulator 70 can stabilize the pressurized air introduced into the main servo valve 80 at a constant pressure. In particular, in the pressure regulator control unit 91 that controls the pressure regulator 70, feedback of the inflow flow rate Gin from the flow rate sensor 72 (flow rate loop 912) and feedback of the pressure Pr from the pressure sensor 74 (pressure loop 911) are performed. By controlling the servo valve 71 of the pressure regulator 70 with a heavy feedback loop, highly accurate pressure stabilization can be performed. As a result, the feed-forward control in the main servo valve 80 can function more effectively.

(Modification)
The present invention is not limited to the above-described embodiment, and modifications and the like within a range that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the switching condition in which the control switching unit 923 enables the PI control unit 922 is a case where the current pressure Pc of the balance cylinder 44 is equal to or lower than the target pressure Pref, that is, low or equal. It is not necessary.

On the other hand, the switching condition for the control switching unit 923 to enable the PI control unit 922 may be a case where the current pressure Pc of the balance cylinder 44 is equal to or higher than the target pressure Pref or higher than the target pressure Pref.
For example, when the current pressure Pc of the balance cylinder 44 becomes excessive only by the feedforward control by the FF control unit 921, it is necessary to assist the electric drive mechanism to push down the balance cylinder 44. By enabling the PI control unit 922 when the pressure is equal to or higher than Pref or higher than the target pressure Pref, assistance by the electric drive mechanism can be eliminated.

  In the present embodiment, a nozzle flapper valve is used as the main servo valve 80. However, any other type of servo valve, such as a servo valve that can obtain high responsiveness, that is, high-speed operation and high accuracy, for example, A spool valve or a diaphragm valve having high dynamic characteristics of about several hundred Hz to 1 kHz may be used.

  In the present embodiment, a pressure regulator 70 having a servo valve 71, a flow sensor 72, an isothermal chamber 73 and a pressure sensor 74 is used as a pressure regulator 70 for stabilizing the inflow pressure of the main servo valve 80. In 91, a double feedback loop of the flow loop 912 and the pressure loop 911 is formed. However, such a pressure regulator 70 is not essential to the present invention, and other types capable of performing high-precision pressure stabilization. May be replaced by a pressure regulator.

  The present invention relates to an electro-pneumatic hybrid-type spindle head elevating device having an electric drive mechanism for elevating and lowering a spindle head, and a balance cylinder that bears the weight of the spindle head, and a machine tool having the spindle head elevating device. Available to

  DESCRIPTION OF SYMBOLS 1 ... Machine tool, 10 ... Base, 11 ... X-axis guide mechanism, 11A ... Guide rail, 11B ... Slide member, 12 ... X-axis linear motor mechanism, 12A ... Magnet, 12B ... Coil, 13 ... Table, 20 ... Gate type Column, 20A: horizontal beam, 21: Y-axis guide mechanism, 21A: guide rail, 21B: slide member, 22: Y-axis linear motor mechanism, 22A: magnet, 22B: coil, 30: spindle device, 33: saddle, 40 ... Spindle head elevating device, 41 ... Z-axis guide mechanism, 41A ... Guide rail, 41B ... Slide member, 42 ... Z-axis linear motor mechanism, 42A ... Magnet, 42B ... Coil, 42C ... Heat shield member, 43 ... Spindle head, 44: balance cylinder, 44A: cylinder body, 44B: piston rod, 45: air supply source, 46: pressure adjustment 47, balance weight, 51, spindle head body, 52, spindle, 53, rotary drive source, 54, tool, 55, bracket, 70, pressure regulator, 71, servo valve, 72, flow sensor, 73, isothermal chamber 74, a pressure sensor, 80, a main servo valve, 90, a control device, 91, a pressure regulator control section, 911, a pressure loop, 912, a flow rate loop, 92, a main servo valve control section, 921, an FF control section, 922 PI control unit, 923: control switching unit, 93: storage unit, Cr: command value, Cs: command value, Gin: inflow rate, Gout: outflow rate, Pc: current pressure of the balance cylinder, Po: from the air supply source Pressure of pressurized air, Pr: pressure of air stabilized by pressure regulator, Pref: target pressure of balance cylinder, Ps: sent to balance cylinder Air pressure, W ... work, the current position of the Xc ... balance cylinder.

Claims (4)

An electric drive mechanism that raises and lowers the spindle head of the machine tool, a balance cylinder that bears the weight of the spindle head, and a spindle head lifting device that includes a pressure adjustment device that controls the pressure of the balance cylinder,
The pressure regulator is a pressure regulator that stabilizes the pressure of the pressurized gas from the pressurized gas source, a main servo valve that regulates the pressure of the pressurized gas stabilized by the pressure regulator, the pressure regulator, A control device for controlling the main servo valve,
The control device has a main servo valve control unit that controls the main servo valve, and the main servo valve control unit performs FF control that performs feedforward control of the main servo valve based on a current position of the balance cylinder. Unit , a PI control unit that performs proportional-integral control based on the target pressure of the balance cylinder and the feedback of the current pressure of the balance cylinder, and whether the PI control unit is enabled or disabled based on the relationship between the target pressure and the current pressure. And a control switching unit for switching the spindle head. The spindle head elevating device according to claim 1 ,
The spindle head elevating device, wherein the main servo valve is a nozzle flapper valve. In the spindle head elevating device according to claim 1 or 2 ,
The pressure regulator is a servo valve that adjusts the pressure of the pressurized gas from the pressurized gas source, a flow sensor that detects the flow rate of the pressurized gas from the servo valve, and a pressurized gas from the flow sensor. An isothermal chamber for temporarily storing, and a pressure sensor for detecting the pressure of the pressurized gas from the isothermal chamber,
A main shaft having a pressure regulator control unit that controls the servo valve of the pressure regulator by a double feedback loop based on a flow value from the flow sensor and a pressure value from the pressure sensor. Head lifting device. A machine tool comprising the spindle head elevating device according to any one of claims 1 to 3 .

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