KR20210115264A - Dust penetration prevention device of machine tool ball screw - Google Patents

Abstract

The present invention relates to a ball screw apparatus comprising a screw unit and a nut unit. The outside of the screw unit is shielded by telescopic bellows covers. An air inlet and an air outlet are installed on the both bellows covers on both sides. An air passage communicating with the inside of the bellows covers on both sides is installed in the nut unit. A first additional suction port and a second additional suction port for selectively supplying compressed air are installed inside the bellows covers on both sides. Each of the air inlet and the first additional suction port and the second additional suction port is connected to a pneumatic pump. First and second solenoid valves for selectively supplying and discharging the compressed air are installed on a pipe to shield the screw unit and keep a pressure inside the bellows covers on both sides constant. Therefore, foreign substances such as dust from a processing area are prevented from penetrating into the ball screw apparatus.

Description

Dust penetration prevention device of machine tool ball screw

The present invention relates to a ball screw protection device that prevents foreign substances, such as machining chips, dust, and cutting oil, from penetrating into a thread part of a machine tool ball screw device.

Most CNC machine tools use a ball screw device to drive the feed system. 1 is a cross-sectional view showing an example of a bolt-type apparatus of a machine tool as a prior art. As shown in FIG. 1, the conventional ball screw device includes a long-axis screw part 20 connected to a servomotor 10, and a nut containing a plurality of balls inserted in a helical form and in rolling contact with the screw part 20. It consists of a part (40).

In the ball screw device configured as described above, the feed system 12 is mounted on one side of the body of the nut unit 40 , and the nut unit 40 rotates the screw unit 20 as the servo motor 10 rotates the screw unit 20 . The feed system 12 is moved on the axis of

However, although the ball screw device is usually installed inside the feed system 12, a part of the machining chips or cutting oil scattered from the machining area of the machine tool may penetrate into the screw part 20 or the nut part 40 of the ball screw device. have. In particular, when the processed material generates powder-type processed chips such as graphite, and the powder penetrates into the screw part 20 or the nut part 40, wear of the ball screw device may be accelerated.

In Patent Document 1 (Republic of Korea Utility Model Publication No. 1988-0011786), which is introduced as a prior art, the outer diameter of the threaded part 20 is covered with a tube to prevent machining chips or cutting oil from being deposited on the threaded part 20 of the ball screw device. The wrapping structure is presented.

However, since this structure is not a completely sealed structure, it is not a solution for dust-type processed chips.

KR 19880011786 U

An object of the present invention is to overcome the problems of the prior art as described above, and an object of the present invention is to provide a protection device for a ball screw device in which cutting oil as well as dust-type machining chips do not penetrate into the ball screw device.

Another object of the present invention is to improve the wear resistance of a ball screw device from processing chips such as dust.

In order to achieve the object of the present invention as described above, the device for preventing dust penetration of a machine tool ball screw of the present invention includes a threaded portion supported by bearings at both ends, and is arranged to be reciprocally movable in the longitudinal direction of the threaded portion on the threaded portion. In the ball screw device having a nut portion on which a bearing ball is disposed,

A bellows cover installed so as to be connected to both side surfaces of the bearing and the nut at both ends for rotating the screw to the outside in the circumferential direction of the screw, and to shield the screw from the outside and form a space for maintaining airtightness;

An air inlet and an air outlet installed in communication with the inside of the both sides of the bellows cover,

an air passage installed in the nut part so that the air inside both bellows covers can communicate with each other;

A first additional suction port and a second additional suction port for selectively supplying compressed air to the inside of the both bellows covers,

A pneumatic pump for supplying compressed air through a pipe to each of the air inlet, the first additional inlet, and the second additional inlet;

A second installed on the pipe connected to the first additional suction port and the second additional suction port and having a switching position for selectively connecting the compressed air supplied from the pneumatic pump to the connecting pipe of the first additional suction port or the second additional suction port It consists of a solenoid valve.

In addition, the air intakes are installed to communicate with the inside of the bellows cover from the bearing bodies at both ends supporting the screw portion.

In addition, in another embodiment, the air inlet is installed to communicate with the inside of the bellows cover from both sides of the nut portion, respectively.

In addition, the air outlet is respectively installed in the bellows cover adjacent to the bearing body at both ends supporting the screw portion.

In addition, the first additional suction port and the second additional suction port are respectively installed on one side of the nut portion so as to be connected to the inside of the bellows cover from the nut portion.

In addition, in another embodiment, the first additional suction port and the second additional suction port may be installed so as to be connected to the inside of the bellows cover from the bearing body at both ends.

In addition, a first solenoid valve for opening and closing the flow of air supplied from the pneumatic pump is installed on the pipe connected to the air intake port of the both bellows covers.

In addition, a regulator for maintaining the reduced pressure of the air supplied to the first solenoid valve at a constant pressure is installed in the upstream pipe of the first solenoid valve.

In addition, in another embodiment, the first solenoid valve is a valve that is switched in the direction of opening the pipe only when the machine tool starts to operate and the nut part moves.

In addition, in another embodiment, when the first solenoid valve supplies compressed air to one of the air intake ports, the air intake port on the opposite side has a selective switching position connected to a vent hole for discharging the compressed air inside the bellows cover to the outside. one valve.

In addition, the second solenoid valve is switched before the inside of the bellows cover becomes a high pressure state or a negative pressure state of a predetermined pressure or more, and additionally supplies high-pressure air to the inside of the bellows cover in a negative pressure state, and the high-pressure bellows The high-pressure air inside the cover is a valve having a switching position to discharge to the outside through a vent hole.

In addition, in another embodiment, the second solenoid valve is a valve that is switched according to a predetermined speed value of the servomotor driving the screw portion.

In addition, in another embodiment, the second solenoid valve is a valve characterized in that the compressed air of a higher pressure than the compressed air supplied to the respective air intakes passes.

The present invention has an effect of preventing foreign substances such as dust, chips, and cutting oil from entering the ball screw device during processing.

In addition, by preventing foreign substances from entering the inside of the ball screw device, the wear resistance of the ball screw device is improved to extend the life of the ball screw device, and furthermore, the precision of the feed system is maintained, ultimately improving the precision of the workpiece. .

1 is a cross-sectional view showing an example of a bolt-type apparatus of a machine tool as a prior art.
2 is a cross-sectional view of a ball screw device according to an embodiment of the present invention.
3 is a pneumatic circuit diagram of a ball screw device according to an embodiment of the present invention.
4 is a pneumatic circuit diagram of a ball screw device as another embodiment of the present invention.

Hereinafter, a preferred embodiment of the main shaft fixing device according to the present invention will be described with reference to the accompanying drawings.

2 is a cross-sectional view of a ball screw device according to an embodiment of the present invention.

As shown in FIG. 2, the ball screw device of the present invention includes a screw portion 20 supported by a bearing 11 at both ends, and a nut portion 40 in which a bearing ball is helically disposed on the screw portion 20. ) is arranged to be reciprocally movable in the longitudinal direction of the screw portion 20 .

It is respectively connected to both sides of the bearing 11 and the nut part 40 for rotating and supporting the threaded part 20 outward in the circumferential direction of the threaded part 20 and expands and contracts, and shields the threaded part 20 from the outside and seals the airtightness. The bellows cover 30 is installed to form a holding space.

That is, the bellows cover 30 is divided into two sides based on the nut portion 40 moving on the screw portion 20 and is installed so as to be stretchable, and at one side of the bellows cover 30 on both sides, air intakes 31, respectively. and an air outlet 32 are installed.

The air intake 31 is installed to communicate with the inside of the bellows cover 30 from both bearings 11 and the body in order to easily fix the pipe 53 for supplying air. In addition, the air outlet 32 is installed at an arbitrary position of both the bellows covers 30 so that the air is discharged at a certain position.

As another embodiment, the air intake 31 may be installed to communicate with the inside of the bellows cover 30 from both sides of the nut part 40, respectively. In addition, the air outlet 32 may also be installed in the bellows cover 30 in contact with the nut part 40, respectively. In this way, when the air intake 31 is installed in the nut part 40, the air pipe 53 is installed so that the air pipe 53 does not interfere with the moving nut part 40 by flexibly installing it.

On the other hand, the nut part 40 is provided with an air passage 41 so that the air inside both the bellows covers 30 can communicate with each other.

In addition, a first additional suction port 42 and a second additional suction port 43 for supplying compressed air to both bellows covers 30 are installed in the nut unit 40 , respectively.

Also, in another embodiment, the first additional suction port 42 and the second additional suction port 43 may be installed to be connected to the inside of the bellows cover 30 from the bearing 11 body at both ends.

3 is a pneumatic circuit diagram of a ball screw device according to an embodiment of the present invention. As shown in FIG. 3 , each of the air inlet 31 , the first additional inlet 42 and the second additional inlet 43 is connected through a pneumatic pump 50 and a pipe 53 for supplying compressed air. .

A first solenoid valve 51 for opening and closing the flow of air supplied from the pneumatic pump 50 is installed on the pipe 53 connected to the air intake 31 of both bellows covers 30, and the first solenoid valve ( The outlet of 51 is connected to the air intake 31 of both bellows covers 30 through the branched pipe 53, respectively.

On the other hand, a regulator 54 for maintaining a constant pressure of the air supplied to the first solenoid valve 51 is installed in the upstream pipe 53 of the first solenoid valve 51 .

On the other hand, on the pipe 53 connected to the first additional suction port 42 and the second additional suction port 43, the compressed air supplied from the pneumatic pump 50 is supplied to the first additional suction port 42 or the second additional suction port 43 ) to install a second solenoid valve having a switching position to be selectively connected to the connecting pipe 53.

Hereinafter, the operation of the dust penetration prevention device of the machine tool ball screw of the present invention configured as described above will be described.

When the machine tool starts to operate, the first solenoid valve 51 is switched in the direction in which the pipe 53 is opened, and the supplied air pressure is reduced to a predetermined pressure through the regulator 54 and supplied to both sides of the air of the bellows cover 30 . It is supplied into the bellows cover 30 through the suction port 31 . As such, when the compressed air is supplied to the inside of the bellows cover 30 on both sides, the compressed air is discharged to the outside through the air outlet 32 after filling the inside of the bellows cover 30 on both sides. In this state, since pneumatic pressure of a certain pressure is supplied and discharged inside both bellows covers 30, foreign substances such as chips or dust in the processing area cannot penetrate.

On the other hand, when the servomotor 10 rotates and the screw part 20 directly connected thereto rotates, the nut part 40 moves to either side according to the rotation of the screw part 20, and the bellows cover 30 in the moving direction ), even if the internal air is discharged to the outside through the air outlet 32, the volume is rapidly reduced compared to the amount of discharged air, and since compressed air is continuously supplied through the air inlet 31, the internal pressure increases.

On the other hand, the inside of the bellows cover 30 on the opposite side is continuously supplied with compressed air through the air intake 31, but as its volume increases faster than the air supply amount, the internal pressure is lowered to become a negative pressure state.

When the pressure imbalance occurs inside both the sealed bellows covers 30 as described above, the compressed air inside the bellows cover 30 with the higher pressure flows through the air passage 41 formed in the nut part 40, the pressure Move to the inside of the lower bellows cover (30).

However, the pressure imbalance inside the bellows cover 30 as described above, when the movement of the nut part 40 is faster, despite the flow of air through the air passage 41 formed in the nut part 40, one side is in a high pressure state and the negative pressure on the other side may be severe.

As such, the high pressure state or the negative pressure state is not resolved due to the limit of the diameter of the air inlet 31, the air outlet 32 and the air passage 41 and the amount of supplied or discharged air depending on the moving speed of the nut unit 40. may not be

If the high pressure and negative pressure inside the bellows cover 30 are not resolved, the high pressure side bellows cover 30 may be damaged due to the pressure, and the negative pressure side bellows cover 30 has an air outlet ( 32), processing dust may be sucked into the interior. In addition, the high-pressure state and the negative-pressure state inside the bellows cover 30 may act as a load on the servomotor 10 that moves the nut part 40 , thereby causing a side effect of slowing the moving speed of the feed system 12 . .

However, before the inside of the bellows cover 30 becomes a high pressure state or a negative pressure state of a predetermined pressure or more, the second solenoid valve 52 is switched, and the second solenoid valve is inside the bellows cover 30 in a negative pressure state. By supplying additional high-pressure air through (52), the negative pressure state is eliminated, and the high-pressure air inside the bellows cover (30) in a high-pressure state is discharged through the air outlet (32) and the vent hole (55) of the second solenoid valve (52). ) is discharged to the outside.

In this way, by resolving the high pressure and negative pressure inside the bellows cover 30 according to the operation of the 2 solenoid valve, it prevents dust from being sucked into the bellows cover 30 due to the negative pressure, and also the transfer system 12 ), the load due to the bellows cover 30 does not occur in the servomotor 10 that moves.

That is, regardless of the moving speed of the nut part 40, the pressure inside the bellows cover 30 always maintains a constant pressure to the extent that it does not affect the load of the servomotor, thereby preventing the inflow of foreign substances such as dust due to negative pressure. .

On the other hand, whether the inside of the bellows cover 30 is in a high pressure state or a negative pressure state above a predetermined pressure is predetermined in the control unit based on the rotation command speed of the servo motor 10 rotating the screw part 20, and the command Control the 2 solenoid valve according to the set speed value.

On the other hand, the switching operation of the second solenoid valve 52 is driven according to the command of the control unit (not shown) according to the moving direction of the nut unit (40).

On the other hand, as another embodiment of the present invention, the first solenoid valve 51 is in a direction to close the pipe 53 if the servomotor 10 does not operate to move the feed system 12 even when the machine tool is operated The nut part 40 is moved by maintaining the switching state and switching to the direction of opening the pipe 53 only when the servo motor 10 is operated to move the feed system 12 after the machine tool is operated. When not, since high-pressure air is not supplied to the inside of the bellows cover 30 , the adverse effect of drying the lubricant applied to the screw part 20 and the nut part 40 by supplying high-pressure air unnecessarily can be prevented.

Meanwhile, as another embodiment, as shown in FIG. 4 , the first solenoid valve 51 installed on the pipe 53 connected to the air intake 31 of the bellows cover 30 is connected to the second solenoid valve 52 . When supplying compressed air to one of the air intakes 31 as shown, the air intake 31 on the opposite side is a selective switching position connected to the vent hole 55 for discharging the compressed air inside the bellows cover 30 to the outside. is composed of a valve having a The pipe 53 is connected to the air intake 31 on the side where the volume inside the bellows cover 30 increases to supply compressed air to the inside of the bellows cover 30, and vice versa, the volume inside the bellows cover 30 The pipe 53 of the decreasing side air intake 31 is connected to the vent hole 55 of the first solenoid valve 51 to discharge the compressed air inside the bellows cover 30 to the outside.

In this way, the compressed air inside the bellows cover 30 in a high pressure state on either side is supplied not only to the air passage 41 and the air outlet 32 of the nut part 40, but also to the vent hole of the first solenoid valve 51. By discharging through (55) to the outside, the high-pressure state inside the bellows cover 30 is more quickly resolved, and the damage of the bellows cover 30 or the load of the servomotor 10 driving the screw part 20 is reduced. can be further reduced.

On the other hand, when the air inside the bellows cover 30 in a high pressure state is discharged through the vent hole 55 of the air passage 41, the air outlet 32, and the first solenoid valve 51 as described above, the negative pressure Inside the bellows cover 30 on the opposite side where the condition can be induced, the first solenoid valve 51, as well as the second solenoid valve 52, high-pressure compressed air by switching the first additional suction port 42 or the second Since it is additionally supplied through the second additional suction port 43, it does not become a negative pressure state and maintains a constant pressure state.

As such, both bellows covers 30 inside maintain a constant pressure state, not in a pneumatic state or a negative pressure state, so that foreign substances such as chips or dust in the processing area do not penetrate, as well as a servomotor ( 10) does not generate any load.

On the other hand, in the above-described embodiments, the compressed air supplied to the first solenoid valve 51 is supplied with reduced pressure through the regulator 54 installed upstream of the first solenoid valve 51, whereas the second solenoid valve ( Since the compressed air supplied to 52 does not go through the pressure reducing regulator 54 , it is compressed air having a higher pressure than the air pressure that has passed through the first solenoid valve 51 .

Therefore, the high-pressure compressed air supplied to the first additional suction port 42 or the second additional suction port 43 through the second solenoid valve 52 is inside the bellows cover 30 even if the nut unit 40 is rapidly transferred. Always maintain a constant input without generating negative pressure

As described in the above embodiments, the present invention installs the bellows cover 30 that is blocked from the outside in the threaded portion 20 of the ball screw device, and maintains a constant pressure inside the bellows cover 30, so that during processing Prevents foreign substances such as chips, machining dust, and cutting oil from penetrating into the ball screw device. In addition, the servomotor 10 for driving the ball screw by preventing a high-pressure state or a negative-pressure state from occurring inside the bellows cover 30 according to the rapid movement of the nut part 40 for transferring the feed system 12 . It is also prevented from increasing the load of

As described above, the present invention improves the wear resistance of the ball screw device by preventing the intrusion of foreign substances into the ball screw device, and furthermore, maintains the precision of the ball screw device to ultimately improve the precision of the workpiece. .

In particular, the present invention has an excellent effect in protecting the ball screw device in a precision machine tool where fine graphite dust adheres to the ball screw device during processing of the graphite material and accelerates the wear of the ball screw.

10 servo motor
11 bearing
12 feed system
20 thread
30 Bellows Cover
31 air intake
32 air outlet
40 nut part
41 air passage
42 1st additional suction port
43 Second additional inlet
50 pneumatic pump
51 1st solenoid valve
52 2nd solenoid valve
53 plumbing
54 regulator
55 vent hole

Claims (13)

A ball screw device having a screw portion supported by bearings at both ends, and a nut portion disposed on the screw portion to be reciprocally movable in the longitudinal direction of the screw portion and having a bearing ball helically disposed therein,
a bellows cover which is connected to both sides of the bearing and the nut at both ends for supporting the rotation of the threaded part in the circumferential direction of the threaded part, respectively, and is expanded and contracted, and is installed so as to form a space for shielding the threaded part from the outside and maintaining airtightness;
an air inlet and an air outlet installed in communication with the inside of the both sides of the bellows cover, respectively;
an air passage installed in the nut portion so that the air inside both bellows covers can communicate with each other;
a first additional suction port and a second additional suction port for selectively supplying compressed air to the inside of the both bellows covers;
a pneumatic pump for supplying compressed air through a pipe to each of the air inlet, the first additional inlet, and the second additional inlet;
A second installed on the pipe connected to the first additional suction port and the second additional suction port and having a switching position for selectively connecting the compressed air supplied from the pneumatic pump to the connecting pipe of the first additional suction port or the second additional suction port A device for preventing dust penetration of a machine tool ball screw including a solenoid valve. The device for preventing dust penetration of a machine tool ball screw according to claim 1, wherein the air inlet is installed to communicate with the inside of the bellows cover from the bearing bodies at both ends supporting the screw part. The device for preventing dust penetration of a machine tool ball screw according to claim 1, wherein the air inlet is installed to communicate with the inside of the bellows cover from both sides of the nut part. The device for preventing dust penetration of a machine tool ball screw according to claim 1, wherein the air outlet is installed in each of the bellows covers adjacent to the bearing bodies at both ends supporting the screw portion. The apparatus of claim 1, wherein the first additional suction port and the second additional suction port are respectively installed on one side of the nut part so as to be connected from the nut part to the inside of the bellows cover. The apparatus of claim 1, wherein the first additional suction port and the second additional suction port are installed so as to be connected from the bearing body at both ends to the inside of the bellows cover. The device for preventing dust penetration of a machine tool ball screw according to claim 1, wherein a first solenoid valve for opening and closing the flow of air supplied from the pneumatic pump is installed on the pipe connected to the air intake port of both bellows covers. . The apparatus of claim 7, wherein a regulator for maintaining the pressure of the air supplied to the first solenoid valve under reduced pressure at a constant pressure is installed in the upstream pipe of the first solenoid valve. [8] The device according to claim 7, wherein the first solenoid valve is switched in the direction of opening the pipe only when the machine tool starts to operate and the nut part moves. The method of claim 7, wherein when the first solenoid valve supplies compressed air to one of the air intake ports, the air intake port on the opposite side has a selective switching position connected to a vent hole for discharging the compressed air inside the bellows cover to the outside. A device for preventing dust penetration of a machine tool ball screw, characterized in that it is a single valve. According to claim 1, wherein the second solenoid valve is switched before the inside of the bellows cover becomes a high pressure state or a negative pressure state of a predetermined pressure or more, and additionally supplies high-pressure air to the inside of the bellows cover in a negative pressure state, A device for preventing dust penetration of a machine tool ball screw, characterized in that it has a switching position for discharging the high-pressure air inside the bellows cover to the outside through the vent hole. The apparatus of claim 1, wherein the second solenoid valve is switched according to a predetermined speed value of a servomotor driving the screw portion. According to claim 1, wherein the second solenoid valve is a machine tool ball screw dust penetration prevention device, characterized in that through the compressed air of a higher pressure than the compressed air supplied to the respective air intakes.

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