JP2007098482A - Safety device of machine tool and machine tool including the safety device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a safety device of a machine tool, functioning as a means for striking a balance of an elevating member and a shock absorbing means for preventing drop and a sudden rise of the elevating member in one device. <P>SOLUTION: This safety device of a machine tool includes: a hydraulic cylinder 151 interlocking with the elevating operation of the elevating member; and a lock mechanism 16, wherein the lock mechanism includes: a lock member 160 for regulating lowering of a piston rod 152a of the hydraulic cylinder 151 when power supply interruption occurs; a pressure chamber 161 for releasing locking of the lock member 169 by a pressure fluid supplied from a second fluid supply part 166; and a pressure reducing part 163 for reducing the pressure of a fluid in the pressure chamber 161 when power supply interruption or the like occurs to lock the piston rod 152a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a machine tool having a lifting and lowering member such as a spindle and a turret that can be moved up and down, while maintaining the weight balance of the lifting and lowering member, and preventing the lifting and lowering member from dropping when the power is cut off during a power failure or the like. The present invention relates to a device and a machine tool provided with the safety device.

As a machine tool having a lifting and lowering member such as a spindle and a tool post that can be raised and lowered, for example, a spindle head that rotatably supports the spindle, a ram that supports the spindle head, and a lifting means that lifts and lowers the ram A tool that is mounted on the tip of the spindle and that processes a workpiece fixed to a table below the ram is known (see, for example, Patent Document 1).
JP-A-11-347873

FIG. 7 is a schematic view of the machine tool described in Patent Document 1 described above.
A column 3 is erected on the bed 1, and a guide 5 a extending in the Y direction (a direction perpendicular to the paper surface) is provided on the front surface (the left surface in the drawing) of the column 3. Further, a saddle 4 that moves forward and backward in the Y direction while being guided by the guide 5a is provided on the front surface of the column 3.
A spindle 9 on which a tool T for machining a workpiece fixed to the table 2 is mounted at the lower end is rotatably supported by the spindle head 8. The spindle head 8 is attached to a ram 7 that moves up and down on the front surface of the saddle 4. The ram 7 moves up and down in the Z direction while being guided by a guide 6 provided in the Z direction (vertical direction) on the front surface of the saddle 4.

A linear motor 10 as a driving body for raising and lowering the ram 7 includes a magnet 10b attached to the rear surface of the ram 7 and a coil 10a disposed on the front surface of the saddle 4 so as to face the magnet 10b. By supplying electric power, the ram 7 moves up and down while being guided by the guide 6.
In the illustrated machine tool, a spring 11 as an urging means is provided below the ram 7 in order to reduce the load on the linear motor 10 when raising and lowering the heavy ram 7. 7 is always biased upward.

In the machine tool having the above configuration, when the power supply to the coil 10a of the linear motor 10 is interrupted due to a power failure or the like, the ram 7 is pushed up by the spring 11 and collides with the upper end of the saddle 4 to cause the spindle head 8 and the spindle 9 , The ram 7 or the saddle 4 may be damaged.
Therefore, in the machine tool described in Patent Document 1, a cylinder device 12 that prevents the ram 7 from colliding with the saddle 4 is provided at the upper end of the saddle 4 so that the ram 7 does not rise when the power is shut off. .

The cylinder device 12 includes a cylinder 121 having a liquid or gas as a working medium as a main component. The tip of a piston rod 122 a that allows the cylinder 121 inserted into the upper end of the saddle 4 to move forward and backward is connected to the upper end of the ram 7.
The inside of the cylinder 121 is partitioned into a first chamber 121a and a second chamber 121b by a piston 122 to which a piston rod 122a is attached, and the first chamber 121a and the second chamber 121b are connected in a communication manner by a fluid pipe 124. Has been.

An electromagnetic valve 123 is provided in the middle of the fluid pipe 124, and the flow of fluid between the first chamber 121a and the second chamber 121b is restricted by switching the electromagnetic valve 123 when the power is shut off. Be able to.
According to the cylinder device 12 configured as described above, during normal operation, the ram 7 is lifted and lowered by driving the linear motor 10 while being biased by the spring 11. At this time, the cylinder 121 has the first chamber 121 a. Since the fluid freely moves between the second chamber 121 b and the second chamber 121 b, the piston 122 moves following the raising and lowering of the ram 7, and a large load does not act on the ram 7 from the cylinder 121.

  When the power supply is cut off due to a power failure or the like, the solenoid valve 123 is instantaneously switched to restrict the flow of the fluid in the fluid piping 124 so that the piston 122 does not move. Although the ram 7 tends to be lifted by the urging force of the spring 11, since the movement of the piston 122 is restricted, the inconvenience of colliding with the upper end of the saddle 4 can be avoided.

However, in the machine tool configured as described above, the weight of the ram 7 is balanced by the spring 11. However, since the urging force of the spring 11 changes depending on the amount of deformation, the urging force that acts on the ram 7 depends on the position of the ram 7. In contrast, particularly near the lower end of the guide 6 where the urging force of the spring 11 is large, there is a problem that a large load acts on the linear motor 10 to make smooth and quick lifting operation difficult.
In addition, since the spring 11 for balancing the weight of the ram 7 and the cylinder device 12 are provided separately, the device configuration of the machine tool becomes complicated and there is a problem that the machine tool is enlarged.

  The present invention has been made in view of the above problems, and means for balancing the weight of a lifting member that moves up and down, such as a ram and a spindle, and prevents the lifting member from dropping or suddenly rising when the power is shut off. A safety device for a machine tool that can perform shock absorbing means for preventing damage to the device with a single device, and can make the weight balance constant regardless of the position of the elevating member, and the safety device It aims at providing the machine tool provided with.

In order to solve the above-described problems, the safety device of the present invention is provided in a machine tool including a lifting member that is lifted and lowered by a motor or other driving means, and prevents the lifting member from falling when a power interruption occurs. A safety device, which is provided above or below the elevating member and includes a fluid pressure cylinder in which a piston rod that can move forward and backward moves in conjunction with the elevating operation of the elevating member, and the fluid pressure cylinder. A piston that moves forward and backward in the fluid pressure cylinder together with the piston rod; a first chamber and a second chamber that are provided in the fluid pressure cylinder and partitioned by the piston; A first fluid supply unit configured to supply a fluid having a pressure and the first chamber; A first pressure holding means having a pressure equality maintaining means for maintaining a pressure equal to the pressure of the pressure rod, and a piston pressure rod that is provided in the middle of the forward / backward movement path of the piston rod. And a pressure chamber that is filled with a predetermined pressure fluid supplied from a second fluid supply unit and that separates the lock member from the piston rod by the predetermined pressure fluid. And a pressure-reducing part that depressurizes the fluid pressure in the pressure chamber and locks the piston rod by the lock member when a power interruption occurs, and a pressure of the fluid in the second chamber Second pressure holding means for holding a constant pressure different from the pressure of the fluid in the first chamber, and the pressure of the fluid in the first chamber and the second chamber The thrust of the piston caused by the difference between the pressure of the fluid, there a size configuration in accordance with the weight balance of the elevation member.
The pressure reducing unit may be a switching valve that communicates the pressure chamber and the second fluid supply unit during normal operation of the machine tool and opens the pressure chamber to the atmosphere when the power is shut off.

According to this configuration, during normal operation of the machine tool, the pressure difference between the first chamber and the second chamber is always kept constant, and the thrust of the piston generated by this pressure difference is used as the weight balance of the lifting member. Can be sized accordingly.
Therefore, regardless of the position of the elevating member, the elevating member can be lifted with a constant force at all times. Further, since the pressure difference has a magnitude corresponding to the weight balance of the elevating member, a smooth and quick elevating operation of the elevating member can be realized between the lowest lowered position and the highest raised position.
Further, since the lock mechanism is engaged with the piston rod so that the piston rod does not move up and down even when the power is shut off, it is possible to prevent the raising and lowering members such as the ram and the main shaft from falling.

Here, “at the time of normal operation of the machine tool” includes a case where the power supply state to the machine tool when the power is turned on is normal and the pressure of fluid such as air used in the safety device is also normal.
Further, “when the power is shut off” includes not only the case where the power is turned off but also the case where the pressure of the fluid such as air used in the safety device is abnormal.
Further, the first fluid supply unit and the second fluid supply unit may be provided in the machine tool or may be provided outside the machine tool.

  The first fluid supply unit is provided with pressure adjusting means such as a regulator, and the pressure of the fluid supplied to the first chamber is adjustable by the pressure adjusting means, so that the thrust of the piston of the fluid pressure cylinder Can be adjusted to an appropriate size according to the weight balance of the elevating member. Further, even if the weight of the elevating member is changed by exchanging a tool or the like, the pressure of the fluid can be adjusted according to the changed weight balance.

  In the present invention, the pressure holding means of the second chamber may be configured as a communication portion that allows the second chamber to communicate with outside air. By doing in this way, the pressure of the second chamber can always be maintained at atmospheric pressure regardless of the type of fluid supplied to the first chamber.

In addition, the fluid supply unit may be connected to the second chamber similarly to the first chamber so that the pressure can be kept constant by the fluid supply unit.
Specifically, the second pressure holding means is provided between the second chamber and a third fluid supply unit that supplies a fluid having a constant pressure to the second chamber, and the pressure of the second chamber is reduced. It is preferable to have a pressure equality maintaining means for maintaining a pressure equal to the pressure of the fluid in the third fluid supply unit.

The first fluid supply unit that supplies fluid to the first chamber and the third fluid supply unit that supplies fluid to the second chamber may be the same fluid supply unit. In this case, the pressure of the fluid supplied to the first chamber may be made different from the pressure of the fluid supplied to the second chamber by a pressure adjusting means such as a regulator.
When the fluid supplied to the first chamber and the second chamber is a fluid having a high compressibility and expandability such as a gas such as air, if the weight of the elevating member suddenly changes due to attachment / detachment of a tool, the first There is a problem that the fluid in the chamber is compressed or expanded and the fluid in the second chamber is expanded or compressed to move the lifting member together with the piston. Therefore, by supplying a constant pressure of fluid from the fluid supply unit not only to the first chamber but also to the second chamber, and setting the pressure of the fluid in the first chamber and the second chamber to be high in advance, The amount of compression and expansion of the fluid in the chamber and the second chamber can be reduced, and the amount of movement of the piston and the lifting member can be reduced.

In addition, when the fluid supplied to the first chamber and / or the second chamber is a liquid, fluid recovery means for recovering the fluid discharged from the discharge port may be provided.
In this way, the fluid discharged from the discharge port can be returned to the fluid supply unit and reused.

  In the present invention, the first fluid supply unit and the second fluid supply unit may be a common fluid supply unit. Then, the switching valve is connected to the first chamber and the pressure chamber from the fluid supply unit, or the fluid from a confluence of air piping for supplying air to the first chamber, the second chamber and the pressure chamber. You may provide in the supply part side.

  The pressure equalization maintaining means of the first pressure holding means and / or the second pressure holding means includes an inlet connected to the fluid supply unit, an outlet connected to the first chamber and / or the second chamber, The fluid discharge port, the first passage that connects the inlet and the outlet in a communication manner, the second passage that connects the outlet and the discharge port in a communication manner, the first passage, and the second passage A valve body that selectively switches between the passages, and when the pressure of the fluid on the outlet side becomes higher than the pressure of the fluid on the inlet side, the valve body closes the first passage and When the pressure of the fluid on the outlet side becomes lower than the pressure of the fluid on the inlet side, the valve body opens the second passage. Close and open the first passage, fluid flows from the inlet to the outlet And so it may be configured to maintain the thrust of the piston to a certain magnitude corresponding to the weight balance of the elevation member.

  With this configuration, even if the piston moves in the fluid pressure cylinder following the lifting / lowering operation of the lifting / lowering member by the motor or other driving means, the fluid in the first chamber and / or the second chamber is moved. The pressure can always be the same as the pressure of the fluid supplied from the fluid supply unit.

The machine tool of the present invention is configured to include any one of the safety devices described above.
According to the machine tool of the present invention, even if a power interruption such as a power failure occurs, the elevating member is not dropped by the safety device and can be held at the position when the power failure occurs.

Since the present invention is configured as described above, it is possible to always maintain a weight balance with a constant biasing force with respect to elevating members such as the main shaft and ram, and smooth and quick elevating regardless of the position of the elevating member. The action can be performed.
In addition, even when the power is cut off due to a power failure or the like, the lock mechanism immediately controls the lifting and lowering of the piston rod, so that the problem that the lifting member falls and damages the device can be prevented.

Furthermore, since it is possible to perform weight balance and prevent the lifting member from being dropped by a single safety device, the machine tool is not enlarged or complicated.
According to the machine tool of the present invention, even if a power interruption such as a power failure occurs during operation of the machine tool, the elevating member does not stop at the position where the power interruption occurs and does not fall down. Work can be performed safely during maintenance and inspection without damaging the components.

DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing an example of a machine tool provided with the safety device of the present invention. In the following description, the same members and parts as those of the machine tool shown in FIG.
As shown in FIG. 1, in the machine tool of this embodiment, a safety device 15 having an air cylinder 151 is provided between the lower end of the saddle 4 and the ram 7. The ram 7 is supported from below by a piston rod 152a that allows the air cylinder 151 to move forward and backward.
The piston rod 152a and the ram 7 may be connected. However, when the air cylinder 151 is disposed below the ram 7 as in this embodiment, the ram 7 is placed on the piston rod 152a. Good.
As described above, if the ram 7 and the piston rod 152a are disconnected, for example, when trouble occurs in the machine tool, the operator can manually move the small ram to quickly repair the trouble. There is an advantage that you can.

[First embodiment]
FIG. 2 is a block diagram illustrating the configuration according to the first embodiment of the safety device of the present invention.
The interior of the air cylinder 151 is partitioned into a first chamber 151a (lower part in FIG. 2) and a second chamber 151b (upper part) by a piston 152 that moves forward and backward together with the piston rod 152a.
The second chamber 151b communicates with the outside air through the silencer 157, and the internal pressure is always kept at atmospheric pressure. In this embodiment, the communication portion (hole) that allows the second chamber 151b to communicate with the outside air constitutes a second pressure holding unit that keeps the air pressure in the second chamber 151b constant (atmospheric pressure).

  In addition, by setting the second pressure holding means as such a communication portion, the fluid supplied to the first chamber 151a is an oil other than air, for example, oil regardless of the type of fluid supplied to the first chamber 151a. Even if it is a liquid like water or water, there exists an advantage that the pressure of the 2nd chamber 151b can be kept constant at atmospheric pressure. The air in the outside air enters and exits the second chamber 151b following the movement of the piston 152 as the ram 7 moves up and down.

  The first chamber 151a is connected via an air pipe 154 to a quick exhaust valve 155 that is a pressure uniformity maintaining means and an air tank 156 that is a fluid supply unit. The air tank 156 may be provided in the main body of the machine tool or may be provided outside the machine tool.

The pressure of the air stored in the air tank 156 is the weight balance of the ram 7 by the thrust of the piston 152 generated by the difference between the air pressure in the first chamber 151a and the air pressure (atmospheric pressure) in the second chamber 151b. It becomes the size according to. The air pressure is determined by the force required for weight balance and the area of the piston 152. For example, when the weight of the ram 7 is 80 N and the diameter of the piston 152 is 2 cm (3.14 cm ² ), the air pressure of the first chamber 151a necessary for the weight balance with the ram 7 and the second chamber 151b The difference from the air pressure can be calculated as 0.26 MPa.

  Further, by providing a regulator 156a as a pressure adjusting means in the air tank 156 or an air pipe 154 in the vicinity of the air tank 156, the pressure of the air supplied from the air tank 156 to the first air chamber 151a is optimal for the weight balance of the ram 7 In addition to being able to adjust to a certain pressure, even if the weight of the ram 7 changes due to a difference in tools to be mounted, the air pressure can be finely adjusted according to the change in weight.

  The quick exhaust valve 155 has an inlet (in) side connected to an air tank 156 that stores air at a constant pressure, and an outlet (out) side connected to the first chamber 151a. Then, when the pressure of the fluid on the outlet (out) side becomes higher than the pressure of the fluid on the inlet (in) side, the air pressure in the first chamber 151a is reduced by exhausting the air on the outlet (out) side. The pressure of the air supplied from the air tank 156 is kept equal.

FIG. 3 is a diagram illustrating an example of the quick exhaust valve 155 described above and explaining the principle thereof.
A valve body 155b that moves forward and backward between the inlet (in) side and the exhaust port (ex) side is inserted in the middle portion of the air flow path 155a of the quick exhaust valve 155. The valve body 155b is formed in a substantially truncated cone shape, and is fitted to a conical seat 155c formed in the middle of the air flow path 155a.

  When the pressure of the air on the outlet (out) side is higher than the pressure of the air on the inlet (in) side, the valve body 155b is pressed against the seat 155c so that air does not flow from the air tank 156 to the first chamber 155a. It has become. Further, when the valve body 155b is pressed against the seat 155c, the exhaust port communicating with the outside air opens, and the air corresponding to the pressure increase in the first chamber 151a flows from the outlet (out) side to the exhaust port (ex) side, Released into the open air. As shown in FIG. 2, a silencer 157 for reducing exhaust noise may be attached to the exhaust port (ex) side of the quick exhaust valve 155.

When the air for the pressure increase in the first chamber 151a is exhausted and the pressure in the first chamber 155a becomes slightly lower than the air pressure in the air tank 156, the valve body 155b is pushed by the air pressure on the inlet (in) side. Leaving the seat 155c, the exhaust port is closed. In addition, the air flow path 155a is communicated from the inlet (in) side to the outlet (out) side, so that air can be supplied to the first chamber 151a. Thereby, the pressure of the air in the first chamber 155a is maintained at the same pressure as that of the air tank 156.
In this embodiment, the quick exhaust valve 155, the air tank 156, and the regulator 156a constitute first pressure holding means for keeping the air pressure in the first chamber 151a constant.

[Lock mechanism]
Next, the lock mechanism 16 that restricts the lifting and lowering of the piston rod 152a when the power is shut off will be described.
Above the second chamber 151b, a lock member 160 that engages with the piston rod 152a and restricts the elevation of the piston rod 152a is provided.
The lock member 160 is accommodated in a pressure chamber 161 provided above the second chamber 151b. A second air tank 166 is connected to the pressure chamber 161 via an air pipe 164, and the lock member 160 is operated during normal operation of the machine tool by air of a predetermined pressure supplied from the second air tank 166 to the pressure chamber 161. Is spaced from the piston rod 152a. When the air pressure in the pressure chamber 161 falls below a preset value due to power shutoff or the like, the lock member 160 moves to the piston rod 152a side and engages to lock the piston rod 152a. Regulate lifting. Such locking of the piston rod 152a by the pressure chamber 161 and the lock member 160 is known, for example, from Japanese Patent Application Laid-Open No. 2003-336605.

  An electromagnetic valve 163 is provided in the middle of the air pipe 164. The solenoid valve 163 communicates the air tank 156 and the pressure chamber 161 during normal operation of the machine tool (hereinafter, this state is referred to as “closed”), and the pressure of the air in the pressure chamber 161 is the same as that of the air tank 156. To keep it. When the power is shut off, the solenoid valve 163 is switched to release the air in the pressure chamber 161 to the atmosphere (hereinafter, this state is referred to as “open”), and the pressure of the air in the pressure chamber 161 is increased. Set to atmospheric pressure. As a result, the lock member 160 engages and locks with the piston rod 152a to restrict the elevation of the piston rod 152a.

The operation of the machine tool of the present invention configured as described above will be described with reference to the flowchart of FIG.
When the machine tool is operating in a normal state, air of a predetermined pressure is supplied to the pressure chamber 161 from the second air tank 166, and the lock member 160 is separated from the piston rod 152a. Further, in this state, when the ram 7 is raised by driving the linear motor 10 (step S1), the piston 152 is raised accordingly, and the air in the second chamber 151b is exhausted into the outside air (step S3).

  As the piston 152 rises, the pressure tends to drop by the amount of increase in the internal volume of the first chamber 151a (step S2), but the air tank 156 passes through the quick exhaust valve 155 to the first chamber 151a to compensate for the pressure drop. Since air is supplied (step S4), the air pressure in the first chamber 151a is always kept the same as the air pressure in the air tank 156.

On the other hand, when the ram 7 is lowered by driving the linear motor 10 (step S11), the piston 152 is lowered accordingly, and air is taken into the second chamber 151b from the outside air (step S13).
Further, as the piston 152 moves down, the pressure tends to increase by the amount that the internal volume of the first chamber 151a has decreased (step S12), but the air corresponding to the pressure increase in the first chamber 151a is used as the exhaust port of the quick exhaust valve 155. In this case, the air pressure in the first chamber 151a is kept the same as the air pressure in the air tank 156.

When the air pressure in the first chamber 151a becomes equal to the air pressure in the air tank 156, whether the air pressure in the first chamber 151a or the air pressure in the air tank 156 is within a preset specified range. Is determined by the NC device based on the detection result of a pressure gauge (not shown) (step S5).
If the air pressure is outside the specified range, an alarm is generated (step S6), the electromagnetic valve 153 is switched to open to shut off the supply of air to the first chamber 151a, and the electromagnetic The valve 163 is opened to release the air in the pressure chamber 161 to the atmosphere, and the piston rod 152a is locked by the lock member 160 to stop the operation of the machine tool (steps S7 and S8).
When the air pressure is within the specified range, the closed state of the electromagnetic valve 153 is maintained (step S10) on the assumption that the power supply is not shut off (step S9). Thereafter, each time the ram 7 is moved up and down, the operations in steps S1 to S10 are repeated.

[Second Embodiment]
Next, a second embodiment of the safety device of the present invention will be described with reference to FIG.
In this embodiment, as shown in the figure, an air tank that supplies air of a predetermined pressure to the pressure chamber 161 of the lock mechanism 16 and an air tank that supplies air of a predetermined pressure to the first chamber 151a are used as a common air tank 156.
In addition, the solenoid valve is located closer to the air tank 156 than the confluence of the air pipe 154 for supplying air from the air tank 156 to the first chamber 151 a and the air pipe 164 for supplying air from the air tank 156 to the pressure chamber 161. 163 is arranged.

In this embodiment, during normal operation of the machine tool, air is supplied to both the pressure chamber 161 and the first chamber 151a, and the piston rod 152a is unlocked by the lock member 160 to achieve a weight balance with the ram. The piston rod 152a is lifted and lowered.
When the power is shut off, the solenoid valve 163 is switched to the open state, the air in the pressure chamber 161 and the first chamber 151a is released to the atmosphere, the piston rod 152a is locked by the lock member 160, and the piston rod 152a Elevation is restricted.

[Third embodiment]
FIG. 6 is a block diagram illustrating a third embodiment of the safety device of the present invention.
In this embodiment, a constant pressure of air can be supplied to the second chamber 151b via the air pipe 154, and a constant pressure of air is supplied from the air tank 156 to the first chamber 151a via the air pipe 154 '. It can be supplied. A quick exhaust valve 155 is provided in the middle of the air pipe 154, and a quick exhaust valve 155 'having the same configuration as the quick exhaust valve 155 is provided in the middle of the air pipe 154'. Also in this embodiment, the quick exhaust valve 155 'acts as a pressure equalization maintaining means.

Further, regulators 156a and 156a 'as pressure adjusting means are provided in the air pipe 154 connected to the first chamber 151a and the air pipe 154' connected to the second chamber 151b, and the air in the first chamber 151a is supplied. The thrust of the piston 152 generated by the difference between the pressure and the pressure of the air in the second chamber 151 b can be adjusted to an appropriate size according to the weight balance of the ram 7.
The lock mechanism 16 in this embodiment is the same as the lock mechanism 16 in the first embodiment.

  In this embodiment, the quick exhaust valve 155, the air tank 156 and the regulator 156a constitute a first pressure holding means for keeping the air pressure in the first chamber 151a constant, and the quick exhaust valve 155 ', the air tank 156' and the regulator 156a ′ constitutes a second pressure holding means for keeping the air pressure in the second chamber 151b constant. Also in this embodiment, the air pressure difference between the first chamber 151 a and the second chamber 151 b is determined by the force necessary for the weight balance with the ram 7 and the area of the piston 152.

  The safety device of this embodiment is particularly advantageous when the fluid supplied to the first chamber 151a and the second chamber 151b is a fluid having high compressibility and expandability such as air. For example, when the weight of the elevating member suddenly changes due to the removal of the tool, the fluid in the first chamber 151 a expands and the fluid in the second chamber 151 b is compressed, so that the ram 7 is lifted together with the piston 152. Therefore, by setting the air pressure in the first chamber 151a and the second chamber 151b to be high in advance, the air expansion amount in the first chamber 151a and the air compression amount in the second chamber 151b are reduced, When the tool is removed, the amount of movement of the ram 7 can be reduced.

Although preferred embodiments of the present invention have been described, the present invention is not limited to the above-described embodiments.
For example, in the above description, the ram and the main shaft have been described as examples of the elevating member, but the present invention can also be applied to other elevating members such as a tool post.
In the above description, a fluid pressure cylinder such as an air cylinder is disposed below a lifting member such as a ram. However, a fluid pressure cylinder may be disposed above the lifting member. When the fluid pressure cylinder is disposed above the lifting member, the lifting member and the piston rod of the fluid pressure cylinder are connected so that the piston rod moves in conjunction with the lifting operation of the lifting member.

  Further, in the above description, air has been described as an example of the working medium (fluid) of the safety device 15, but other gases other than air may be used as a working medium, and liquid is not limited to gas. It is also possible. Further, different fluids may be used in the first chamber and the second chamber. For example, a liquid is supplied to one chamber (for example, the first chamber), and a gas is supplied to the other chamber (second chamber). Also good.

  In the present invention, a fluid recovery means for recovering the fluid discharged from the quick exhaust valve (pressure equality maintaining means) may be provided. Then, by returning the collected fluid to the fluid supply unit, the fluid can be reused. The fluid recovery means can be constituted by, for example, a pipe connected to the discharge port of the pressure uniformity maintaining means and the fluid supply unit, and a pump provided in the middle of the pipe.

  Furthermore, in the above description, the switching valve 163 is switched when the power is shut off to release the air in the pressure chamber 161 to the atmosphere, so that the piston rod 152a is locked by the lock member 160. Also, another low-pressure air tank is prepared, and the switching valve 163 is switched when the power is shut off so that the pressure chamber 161 communicates with the low-pressure air tank so that the piston rod 152a is locked by the lock member 160. May be.

Furthermore, in the other embodiments described above, the air tank on the first chamber 151a side and the air tank on the second chamber 151b side are the same, but the air tank on the first chamber 151a side and the air tank on the second chamber 151b side are It is good also as another thing (a 1st fluid supply part and a 3rd fluid supply part).
Moreover, although the fluid supply part which supplies the fluid of a fixed pressure to a 1st chamber or a 2nd chamber was demonstrated as a tank which stores fluids, such as air, at a fixed pressure, supplying a fluid of a fixed pressure If it is possible, a pump or the like may be used.

  The present invention can be applied to all types of machine tools for raising and lowering lifting members such as a tool post and a spindle, for example, lathes, drilling machines, milling machines, grinding machines, electric discharge machines, etc. The present invention is not limited to the one that raises and lowers the member, but can be applied to all machine tools in which the raising and lowering member may drop due to power interruption.

It is a figure showing an example of a machine tool provided with a safety device concerning one embodiment of the present invention. 1 is a block diagram illustrating a configuration according to a first embodiment of a safety device. FIG. It is a figure explaining the principle of the quick exhaust valve in this embodiment. It is a flowchart explaining the effect | action of the safety device concerning this embodiment. It is a block diagram concerning the 2nd embodiment of the safety device of the present invention, and explaining the composition. It is a block diagram explaining the structure concerning 3rd embodiment of the safety device of this invention. It is the schematic of the machine tool concerning the prior art example of this invention and described in patent document 1. FIG.

Explanation of symbols

1 bed 2 table 3 column 4 saddle 5a, 5b guide 6 guide 7 ram 8 spindle head 9 spindle 10 linear motor 15 safety device 151 air cylinder 151a first chamber 151b second chamber 152 piston 152a piston rod 154 air piping 155 quick exhaust valve 156 Air tank 157 Silencer 16 Lock mechanism 160 Lock member 161 Pressure chamber 163 Solenoid valve 164 Air piping 166 Second air tank

Claims (10)

A safety device that is provided in a machine tool provided with a lifting member that is lifted and lowered by a motor or other driving means, and that prevents the lifting member from falling when a power interruption occurs,
A fluid pressure cylinder that is provided above or below the elevating member and in which a piston rod that is movable back and forth moves in conjunction with the elevating operation of the elevating member;
A piston which is provided inside the fluid pressure cylinder and moves forward and backward in the fluid pressure cylinder together with the piston rod;
A first chamber and a second chamber provided inside the fluid pressure cylinder and partitioned by the piston;
The first chamber is provided between a first fluid supply unit that supplies a fluid having a constant pressure to the first chamber and the first chamber, and the pressure of the first chamber is equal to the pressure of the fluid of the first fluid supply unit. First pressure holding means comprising pressure equality maintaining means for maintaining the pressure;
A lock member that is provided in the middle of the forward / backward movement path of the piston rod, engages with the piston rod when power interruption occurs, and is supplied from the second fluid supply unit. A pressure chamber that is filled with a fluid of a predetermined pressure and the lock member is separated from the piston rod by the fluid of the predetermined pressure, and the pressure of the fluid in the pressure chamber is reduced when the power is shut off and the lock is performed. A locking mechanism having a pressure reducing part that locks the piston rod by a member;
Second pressure holding means for holding the pressure of the fluid in the second chamber at a constant pressure different from the pressure of the fluid in the first chamber;
A safety device for a machine tool, wherein the piston thrust generated by the difference between the fluid pressure in the first chamber and the fluid pressure in the second chamber is sized according to the weight balance of the elevating member. . The pressure reducing unit communicates the pressure chamber with the second fluid supply unit during normal operation of the machine tool to separate the lock member from the piston rod. The safety device for a machine tool according to claim 1, wherein the safety valve is a switching valve that is opened and decompressed. The pressure of the fluid supplied from the first fluid supply unit is adjusted by pressure adjusting means, and the thrust of the piston of the fluid pressure cylinder is set to a magnitude corresponding to the weight balance of the lifting member. Item 3. A machine tool safety device according to Item 1 or 2. The safety device for a machine tool according to any one of claims 1 to 3, wherein the second pressure holding means is a communication portion that allows the second chamber to communicate with outside air. The second pressure holding means is provided between the third fluid supply section for supplying a fluid having a constant pressure to the second chamber and the second chamber, and the pressure of the second chamber is set to the third fluid. The safety device for a machine tool according to any one of claims 1 to 3, further comprising pressure equality maintaining means for maintaining a pressure equal to the pressure of the fluid in the supply unit. The first fluid supply unit that supplies fluid to the first chamber and the third fluid supply unit that supplies fluid to the second chamber are the same fluid supply unit, and supply to the first chamber by pressure adjusting means. 6. The safety device for a machine tool according to claim 5, wherein the pressure of the fluid is different from the pressure of the fluid supplied to the second chamber. The fluid recovery means for recovering the fluid discharged from the discharge port when the fluid supplied to the first chamber and / or the second chamber is a liquid is provided. The machine tool safety device described in 1. The first fluid supply unit and the second fluid supply unit or the first fluid supply unit, the second fluid supply unit, and the third fluid supply unit are a common fluid supply unit. The switching valve is provided closer to the fluid supply unit than a confluence of air pipes for supplying air to the chamber and the pressure chamber or the first chamber, the second chamber, and the pressure chamber. The machine tool safety device according to any one of claims 2 to 7. The equal pressure maintaining means communicates an inlet connected to the fluid supply unit, an outlet connected to the first chamber or the second chamber, a fluid outlet, and the inlet and the outlet. A first passage that is connected to the second passage, a second passage that connects the outlet and the discharge port in communication, and a valve body that selectively switches between the first passage and the second passage,
When the pressure of the fluid on the outlet side becomes higher than the pressure of the fluid on the inlet side, the valve body closes the first passage and opens the second passage, and fluid flows from the outlet to the discharge port. When the pressure of the fluid on the outlet side is lower than the pressure of the fluid on the inlet side, the valve body closes the second passage and opens the first passage, and the outlet from the inlet So that fluid flows through
Maintaining the thrust of the piston at a constant magnitude according to the weight balance of the elevating member;
The machine tool safety device according to any one of claims 1 to 8, wherein: A machine tool comprising an elevating member that elevates and lowers by a motor or other driving means, comprising the safety device according to any one of claims 1 to 9.

Images