KR100714062B1 - Robot grip exchange apparatus - Google Patents

Abstract

The present invention has a structure in which the life is ensured by preventing the malfunction and the wear compensation according to the long-term use by the automatic caution according to the clamping of the robot mounting upper body and the tool mounting lower body according to the long-term use, the cumulative tolerance of the assembly and processing is compensated Provides a grip exchange device for robots that can reduce manufacturing costs by minimizing malfunctions and defective products and simplifying structures.

An upper body for horizontally shifting clamping and unclamping of the grip jaw of the 120 degree intervals coupled to the plunger that moves up and down in connection with the raising and lowering motion of the piston to achieve the above object, and the catch caught by the grip jaw The hook is composed of a lower body assembled, the hook rod is formed on the lower surface of the head inclined or formed into a spherical surface of the spherical sheet formed on the upper, lower surface contacting the spherical sheet, the hook of the grip When the piece clamps the lower spherical surface of the spherical spacer, the upper spherical surface is in contact with the seat surface and the moving tolerances between the grip jaws are always compensated in the vertical direction by the angular displacement regardless of the wear tolerance of the member. It is characterized in that the horizontal maintenance of the tool (various industrial jig, welding gun) to be attached.

 Robot, Plunger, Wedge Piece, Grips, Slide Piece, Spherical Spacer, Seat Surface, Compensation

Description

Grip changer for robots {ROBOT GRIP EXCHANGE APPARATUS}

1 is an exploded perspective view of a preferred embodiment according to the present invention.

2 is an exploded perspective view of a component member according to the present invention;

Figure 3 is an exploded perspective view of the piston and the plunger and grip jaw according to the present invention.

Figure 4 is an exploded cross-sectional view of the upper body for robot attachment according to the present invention.

5 is an exploded cross-sectional view of a tool attachment lower body according to the present invention.

Figure 6 is a cross-sectional view before assembly of the upper body and the lower body in accordance with the present invention.

Figure 7 is an assembled cross-sectional view after the coupling of the upper body and the lower body in accordance with the present invention.

Figure 8 is an enlarged view of the excerpt of the plunger and grip jaw and the engaging rod according to the present invention.

Figure 9 is a bottom view of the upper body for attaching the robot according to the present invention, showing the relationship between the grip jaw and the sensor.

10 to 12 are excerpts showing the operation relationship according to the clamping between the grip jaw of the upper body and the engaging rod of the lower body,

10 is a normal clamping operation,

11 is a clamping operation according to any malfunction of the grip jaw,

12 is a clamping operation according to the wear of the locking rod and the spherical spacer.

13 and 14 is another embodiment of the upper body for attaching a robot according to the present invention,

13 is a state in which the locking rod and the clamping state of the lower body is released,

14 is a state diagram clamped with the engaging rod of the lower body.

** Explanation of symbols for main parts of drawings **

100: upper body 110: upper body

120: cylinder chamber 130: slide guide groove

140: cover 150: piston

160: compression spring 170: plunger

172: Wedge 180: Grip

181: L type hook piece 182: slide piece

200: lower body 210: lower body

220: center shaft hole 230: interference prevention groove

240: locking rod 250: head

251: sheet surface 260: spherical spacer

261: center correction ball 270: spring ring

The present invention relates to a grip exchange device for a robot, and more particularly, to prevent malfunctions and to compensate for wear caused by long-term use by automatic attention due to the clamping of the robot-attached upper body and the tool-attached lower body according to long-term use. The present invention relates to a grip exchange apparatus for a robot capable of reducing manufacturing costs by minimizing malfunctions and defective products and simplifying the structure to compensate for the accumulated tolerances of assembly and processing.

In general, a variety of grip grip device techniques for robots related to the technology of the present invention have been disclosed.

The prior art has a structure of a robot attachment upper body assembled to a robot, and a tool attachment lower body clamped by gripping on the upper body, and a grip method of upper and lower bodies is known as a core technology.

A representative example of such a conventional grip change device is the ball type.

The ball type has a structure in which the lower part for attaching the tool is attached and detached using the master chuck and the intermittent ball provided in the upper part for attaching the robot.

However, this type of ball is difficult to maintain precise fastening force because the clamping operation of the upper body and the lower body is gripped by the point contact with the spherical surface of the intermittent ball, and the intermittent state is interrupted by the wear and external force distorted by long-term use. There was a disadvantage that the dismantling could not be done if the intermittent ball does not fall out for release.

In addition, when the operation time of the intermittent ball is delayed, there is a possibility that the lower body may fall off, resulting in the loss of the jig.

Moreover, it is disclosed by the type using a cam.

This type of cam is guaranteed to be reliable in operation, but has a disadvantage in that the manufacturing cost is expensive due to the complicated components for operating the cam.

The present invention was developed to effectively solve the disadvantages of the conventional grip exchange device for robots,

The present invention provides a grip exchange apparatus for a robot in which a reliability of the device is ensured because there is no malfunction due to the reliability of the fastening of the upper body and the lower body.

The present invention is to provide a robot-type grip exchange device that guarantees the service life as well as the reliability can be provided by providing a horizontal maintenance of the lower body by automatically compensating the fastening tolerance of the upper body and the lower body according to the long-term use. .

SUMMARY OF THE INVENTION The present invention provides a robotic grip exchange apparatus capable of compensating a cumulative tolerance due to assembly and processing tolerances of a simple structure and a component, thereby minimizing a defect rate of a device and reducing manufacturing costs.

Robotic grip exchange device of the present invention for achieving the above object,

An upper body for horizontally moving the clamping and unclamping of the grip jaw of a 120 degree interval coupled to the lifting and lowering plunger in connection with the raising and lowering motion of the piston provided in the upper body,

Consists of a lower body consisting of a lower body assembled with a catch rod that is caught on the grip jaw,

The hooking rod forms a sheet surface formed inclined or spherical on the lower surface of the head, and contacts the spherical sheet and assembles a spherical spacer formed on the upper and lower portions of the spherical surface smaller than the inclined angle or diameter of the spherical surface. When the hook piece of the plate moves horizontally and clamps the lower surface of the spherical spacer,

Even when the upper spherical surface is in contact with the seat surface of the head, the axial center of the lower body of the lower body can always be compensated vertically by the angular displacement even with the tolerance of the moving distance between the grip jaws or the wear of the seat surface or the spherical spacer due to prolonged use. It is characterized by providing horizontal maintenance of tools (various industrial jigs, welding guns) to be attached.

In addition, the plunger is protruded and spaced apart from the sheet plate and the intermittent plate is provided with a sheet surface formed inclined or spherical in the lower portion, and the spherical spacer is formed between the sheet plate and the intermittent plate is spherical, Consists of a crank lever axially coupled to the upper body in the state in which both the cam projection is coupled between the intermittent groove and the spherical spacer and the intermittent plate processed on the slide piece of the grip jaw,

Provides horizontal movement of the grip jaw in connection with the lifting and lowering motion of the plunger, wherein the horizontal movement tolerance of each grip jaw is assembled to the lower body by angularly displacing the upper surface of the spherical spacer in contact with the seat surface. It is characterized by providing the horizontal maintenance of tools (various industrial jigs, welding guns) to be attached by always correcting the axis of the catch rod vertically.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration of the present invention.

As shown in FIG. 1, the grip exchange device for a robot of the present invention includes a robot attachment upper part fastened and assembled to a robot as in the prior art, and a tool attachment lower body fastened and assembled to a tool such as various industrial jigs and welding guns. It consists of a removable structure by clamping and unclamping mutually between upper and lower bodies.

2 to 7, the upper body 100 has a cylinder guide 120 through which the plunger hole 121 penetrates in a vertical direction and a slide guide groove 130 radially at a 120 degree interval in a horizontal direction on the bottom surface thereof. The processed upper body 110,

A cover 140 fastened to the upper body to seal an upper portion of the cylinder chamber 120;

A piston 150 for elevating operation in the cylinder chamber 120;

Compression springs 160 are arranged at intervals of 120 degrees between the piston and the upper body 110,

A plunger 170 inserted into the plunger hole 121 and having a wedge piece 172 radially at a 120-degree interval at a lower portion of the plunger shaft 171 assembled with the piston 150;

A slide piece 182 is formed on the upper portion of the L-shaped hook piece 181 to engage with the respective wedge pieces 172, and the slide piece is assembled to the slide guide groove 130 of the upper body 110, Consists of the grip jaw 180 is arranged at 120-degree intervals to move horizontally for clamping and clamping release in connection with the lifting and lowering operation of the wedge piece 172,

The lower body 200 has the central axis hole 220 penetrated in the center and the wedge piece 172 of the plunger 170 and the grip jaw 180 so that there is no interference of operation of the upper surface 120 degrees in the center A lower body 210 provided with an interference preventing groove 230 through which the shaft hole 220 is horizontally processed;

A locking rod 240 fastened and assembled to the central shaft hole and having a head 250 machined on a bottom surface of the seat surface 251 inclined upward toward the shaft rod 241;

Correction shaft hole 261 larger than the diameter of the shaft rod 241 of the engaging rod is coupled to the upper and lower parts so as to be in contact with the seat surface 251 and the L-shaped hook piece 181 of each grip jaw 180 A spherical spacer 260 having upper and lower spherical surfaces 262 and 263 facing each other;

It is composed of a spring ring 270 coupled to the shaft rod 241 of the engaging rod 240 to block the separation of the lower portion of the spherical spacer 260.

As shown in FIG. 6, the cylinder chamber 120 of the upper body 110 has an inlet port 122 and an outlet port 123 connected to an air supply source 300 such as a compressor penetrating through one side thereof.

The upper portion of the cylinder chamber 120 is formed in the cover 140 is fastened with a plurality of fastening screws in the upper body 110 is assembled to the step portion 141 accommodated in the inner peripheral surface of the cylinder chamber 120 ( Confidentiality is maintained by C).

The plunger 170 is assembled with the piston 150 and the fastening screw, and the piston 150 has airtight rings A and B assembled on the outer circumferential surface for airtightness of the upper side and the lower side of the cylinder chamber 120. There is,

An airtight ring (D) is assembled in the plunger hole 121 of the upper body 110 for lower airtightness of the cylinder chamber 120 to maintain airtightness between the plungers 170 and at the same time smoothly lift the plunger 170. A guide bush 111 made of copper (Cu) for holding the guide of the operation is assembled.

At this time, the upper body 110 and the cover 140, the bolt assembly hole 112 and the bolt passing hole 142 is matched through a plurality of, the upper body 110, the cover 140 is assembled using them. The robot is fastened and assembled with the fastening bolt (R).

The compression spring 160 is preferably composed of a square spring having a rigidity than the circular.

The compression spring 160 is between the seating groove 115 of the 120-degree intervals processed on the upper surface of the upper body 110 and the seating groove 155 processed at 120-degree intervals on the lower surface of the piston 150. Installed reliably at

The compression spring 160 may maintain the clamping force of the grip jaw 180 by always raising the piston 150 when the air supply of the inlet port 122 is cut off from the power source or the air supply source 300.

As shown in FIG. 3, the plunger 170 protrudes from the lower portion of the plunger shaft 171 in the radially arranged wedge piece 172.

The wedge piece 172 has both sides are uneven protrusions 172a and the uneven protrusions are inclined narrowly from the upper side to the lower side toward the axial center of the plunger shaft 171 to extend a predetermined distance, and the slide piece of the grip jaw 180. 182 is coupled to the wedge piece 172 is formed with an uneven inclined groove 182a extending a predetermined distance from the top to the bottom to guide the movement.

The grip jaw 180 is formed with an L-shaped hook piece 181 integrated with the slice piece 182, the upper surface of the hook piece is inclined downwardly inclined toward the axis of the plunger shaft 171 181a is formed, and the lower spherical surface 263 of the spherical spacer 260 is brought into contact with each other.

And the lower surface of the wedge piece 172 of the plunger 170 is to prevent the infiltration of dust or foreign matter as much as possible by the cover plate 190 is assembled with a fastening screw in a circular groove processed in the bottom surface of the upper body (110). have.

At this time, the slide guide groove 130 of the upper body 110 is formed as a T-shaped step groove and the grip jaw 180 is also formed by the hook piece 181 and the slide piece 182 in cross-section T-shaped bottom It is configured to prevent the departure.

On the other hand, the upper body 110 is a pair of positioning pins 116 is assembled, is fixed by a setting screw screwed on one side, the lower body 210 is set by the positioning pins 116 Positioning groove 216 is configured, the rigid guide bush 217 is assembled to the positioning groove.

The positioning pin 116 is set to the correct position when the upper body 100 is lowered and coupled to the lower body 200.

As shown in FIG. 5, the central shaft hole 220 of the lower body 210 has a bolt accommodation hole 218 penetrated at a lower portion thereof, so that the engaging rod 240 is screwed at the upper portion thereof, and in the bolt accommodation hole 218. It is tightened again by fixing bolts to be assembled.

In addition, the lower body 210 is passed through a plurality of bolt assembly holes 219 for assembling with the tool (T).

As shown in FIG. 8, the engaging rod 240 has an angle θ of an inclined seat surface 251 processed on the head 250 to receive upper and lower spherical surfaces 262 and 263 of the spherical spacer. It is formed in size.

At this time, the inclination angle of the seat surface 251 of the head 250 of the locking rod 240 is preferably formed in the range of 100 degrees to 170 degrees.

In addition, the seat surface 251 processed on the head 250 of the engaging rod 240 is formed as a spherical surface, the spherical diameter (D1) of the seat surface was formed larger than the spherical diameter (D2) of the spherical spacer 260. .

1 and 6, the lower portion of the upper body 110 and the upper portion of the lower body 210 face each other so that the connector holes 195 and 295 are formed through one side so that the male connector 196 and The female connector 296 is assembled and connected to the connection adapters 197 and 297 respectively assembled on one side, and the respective connection adapters 197 and 297 are electrically connected to the robot R and the tool T, respectively.

And, as shown in Figure 9, the upper body 210 is the sensor assembly hole 198 is processed 120 degrees intervals and the withdrawal hole 199 penetrates through the connector hole 195 therein, the sensor assembly hole ( 198, a contact sensor S1 or a non-contact sensor S2 is assembled and electrically connected to the male connector 196 through the extraction hole 199.

That is, when the upper body 100 is lowered and coupled to the lower body 200 as shown in FIG. 7 while the upper body 100 and the lower body 200 are separated as shown in FIG. 6, the sensor S1 or S2. The sensing of the coupling state of the upper body 110 and the lower body 210 is delivered to the male connector 196 to check the bot (R) and proceed to the next operation.

In addition, the male connector 196 and the female connector 296 are connected to each other to transmit a signal of the tool T of various jigs or welding guns assembled to the lower body 210 of the lower body 200 to the robot R. To operate under the control of the robot R.

The core technology of the present invention is the wear and angle of the sliding portion of the piston 150, the wear of the piston 150, the wedge piece 172 of the plunger 170 and the slide piece 182 of the grip jaw 180 with each other for a long time use. Spherical spacer coupled to the engaging rod 240 of the lower body 200 clamped to the grip jaw 180 of the upper body 100 even in the process of processing or cumulative tolerance of the component member, irregular wear or wear due to long-term use ( 260 is automatically angularly displaced by the spherical contact with the seat surface 251 of the head 250 of the locking rod 240, the locking rod 240 is a tool attached to the axial center is always maintained in the vertical direction ( Keeping the level of T) prevents the malfunction of the tool (T) and ensures its life.

That is, the upper body 100 is lowered by the robot R and lowered and coupled to the lower body 200 attached to the tool T.

At this time, the cylinder chamber 120 of the upper body 210 by lowering the piston 150 by the supply of the compressed air from the air supply source 300 through the inlet port 122, the grip jaw radially assembled at 120 degree intervals ( The upper body 110 and the lower body 210 are in close contact with each other while being lowered in an open state in the opposite direction of the axial direction to be accommodated in the interference preventing groove 230 of the lower body 210.

When the coupling state of the lower body 210 is confirmed by the sensor S1 or S2 of the upper body 110, the compressed air is supplied to the outlet port 123 by the air supply source 300 to the cylinder chamber 120. The piston 150 is raised and the plunger 170 is raised in association.

As such, the rise of the plunger 170 is narrowed by horizontally moving the radially assembled grip jaw 180 at an interval of 120 degrees in the axial direction, and clamps the catching rod 240 assembled to the lower body 210.

If the power supply is interrupted or the air supply is stopped due to an external factor, the piston 150 is lifted by the compression spring 160 so that the clamping state is continued and the clamping of the lower body 200 is fixed to the tool T. Breakage is prevented.

For this clamping operation, refer to the excerpt view showing the operation relationship according to the clamping of the grip jaw 180 of the upper body 100 and the locking rod 240 of the lower body 200 shown in FIGS. if,

The slide piece 182 of the grip jaw 180 coupled to the wedge piece 172 of the plunger 170 has a sliding structure of mutually inclined concave-convex coupling, so that it can be combined with the initial or precision machining. As such, normal clamping operation is achieved.

However, the sliding part of the uneven inclined groove 182a to which the uneven protrusion 172a of the wedge piece 172 and the slide piece 182 of the grip jaw 180 are combined for long-term use or accumulating processing errors and sliding parts. And when the wear of the other constituent members occurs as shown in Figure 11, any one of the grip jaw 180 as shown in Figure 11 error in the movement distance for clamping or wear of the locking rod 240 and the spherical spacer 260 as shown in FIG. Done.

At this time, the axial movement of each of the grip jaws 180 for clamping the engaging rods 240 is simultaneously in contact with the lower spherical surface 263 of the spherical spacer 260 on the upper inclined surface 181 of the L-shaped hook piece 181. The upper spherical surface 262 is in contact with the seat surface 251 provided on the head 250 of the locking bar 240, the angle bar in the moving distance tolerance of the L-shaped hook piece 181, the locking rod ( 240 is compensated for and clamped at all times to maintain the vertical axis.

Such an operation may be a spherical diameter D2 in which the spherical surface of the spherical spacer 260 is located within the inclination angle of the seat surface 251 or the size of the spherical diameter D1 when the sheet surface 251 is spherical. When the spherical spacer 260 is formed to be larger than the spherical diameter D2, the spherical spacer 250 may be freely angularly displaced to compensate for the cumulative tolerance and the machining tolerance.

13 and 14 is another embodiment of the upper body for attaching a robot according to the present invention,

The plunger 170 has a seat plate 174 and an intermittent plate 176 having a seat surface 175 formed to be inclined or spherical at a lower portion thereof, and are spaced at a predetermined interval, and the sheet plate 174 and the intermittent plate ( Spherical spacer 265 having an upper spherical surface 266 between the 176 is assembled,

The upper body 110 in a state in which both side cam protrusions 281 and 282 are coupled between the intermittent groove 185 and the spherical spacer 265 and the intermittent plate 176 processed on the slide piece 182 of the grip jaw 180. ) Is composed of a crank lever 280 axially coupled by a shaft pin (285).

At this time, the diameter of the upper spherical surface 266 of the spherical spacer 265 is formed smaller than the size of the inclination angle of the sheet surface 175 of the sheet plate 174 or the diameter of the spherical surface as in the preferred embodiment of the present invention.

And the lower surface 267 of the spherical spacer 265 is formed in a plane so that the cam projection 281 of the crank lever 280 is uniformly transmitted sliding force.

The operation of this embodiment is not significantly different from the operation of the preferred embodiment of the present invention.

However, it is characterized in that the horizontal movement of the grip jaw 180 disposed radially at 120 degree intervals is transmitted to the crank lever 280 that rotates about the shaft pin 285.

As described above, in the present invention, even if there is a cumulative tolerance or a machining tolerance caused by wear of a component member due to long-term use of the clamping operation of the lower body to which the tool is attached, the axis center of the lower body is always in the vertical direction automatically. Compensated construction increases tool usage and ensures reliable clamping and de-clamping to ensure device reliability.

And the simple structure and compensation of machining tolerances of the constituent members minimize the defect rate of the product and ensure a long service life.

Claims (15)

It consists of a robot attachment upper part that is fastened and assembled to the robot, and a tool attachment lower part that is fastened and assembled to a tool such as various industrial jigs, welding guns, etc., and the robot is detachable by upper clamping and lowering of the lower parts. In the grip exchange device for A cylinder body communicating with the plunger hole penetrated in the vertical direction and an upper body in which the radially guided grooves are radially spaced 120 degrees apart on the bottom surface, a cover which is fastened to the upper body to seal the upper part of the cylinder chamber, and lifts from the cylinder chamber. An actuating piston, a compression spring disposed at intervals of 120 degrees between the piston and the upper body, a plunger having a wedge piece radially at intervals of 120 degrees on the lower part of the plunger shaft assembled with the piston, and lifting and lowering operation of the wedge piece. L-shaped hook pieces radially spaced 120 degrees apart, which are assembled in the slide guide groove of the upper body so as to be connected to each other in a horizontal direction, and at the same time, the slide pieces integrally engaged with the wedge pieces of the upper body integrally thereon. The upper body composed of grips The lower body having an interference preventing groove which is penetrated in the horizontal direction in the central axis hole 120 degrees radially on the upper surface so that the center shaft hole and the wedge piece of the plunger and each grip jaw penetrated in the center so that there is no interference A locking rod having a head which is fastened and assembled to the shaft and has an upwardly inclined seat surface toward the shaft, and a correction shaft hole larger than the shaft diameter of the locking rod penetrates and is coupled to the seat surface and the L-shaped hook of the grip jaw. Robotic grip, characterized in that consisting of a spherical spacer formed with upper and lower spherical surfaces (262, 263) in contact with one side, a spring ring coupled to the shaft rod of the engaging rod to block the lower departure of the spherical spacer. Exchange device. The method of claim 1, Each wedge piece of the plunger is an uneven protrusion on both sides and the uneven protrusion is inclined narrowly from the top to the bottom toward the axial center of the plunger shaft to extend a certain distance, and the slide piece of the grip jaw is engaged with the wedge piece to guide the movement. Robot-type grip exchange device, characterized in that consisting of the uneven inclined groove extending at a predetermined distance from the top to the bottom. The method of claim 1, L-shaped hook piece of the grip jaw is a robot-type grip exchange device, characterized in that the upper surface is formed to be inclined downward toward the center line to the lower surface of the spherical spacer in contact with the lower surface. The method of claim 1, The inclined angle of the inclined seat surface processed in the head of the engaging rod is a robot-type grip exchange device, characterized in that formed in the angle size to accommodate the spherical surface of the spherical spacer. The method of claim 4, wherein Robotic grip exchange device, characterized in that the inclination angle of the head seat surface of the engaging rod is formed in the range of 100 degrees to 170 degrees. The method according to claim 1 or 4, The seat surface processed in the head of the engaging rod is formed into a spherical surface, the spherical diameter of the seat surface robot-type grip exchange device, characterized in that formed larger than the spherical diameter of the spherical spacer. The method according to claim 1 or 3, The axial movement of each grip jaw for clamping the engaging rod is such that the lower spherical surface of the spherical spacer is in contact with the inclined surface of the L-shaped hook piece and the upper spherical surface is in contact with the head seat surface of the engaging rod, but the movement distance tolerance of each L-shaped hook piece B) a robot-type grip changer configured to compensate by clamping the locking rod to always maintain a vertical axis by angular displacement of the sliding part of the wedge piece of the plunger and the slide piece of the grip jaw. The method of claim 1, The plunger is protruded from the sheet plate and the intermittent plate is provided with a sheet surface formed inclined or spherical at the bottom spaced apart at regular intervals, and the spherical spacer formed with a spherical surface between the sheet plate and the intermittent plate is assembled, And a crank lever axially coupled to the upper body by an axial pin in a state in which both cam protrusions are coupled between the spherical spacer and the intermittent plate. The method of claim 8, The spherical spacer is a robot-type grip exchange device, characterized in that the lower surface is formed in a plane. The method of claim 8, And a spherical diameter of the spherical spacer is smaller than the inclination angle of the sheet surface of the sheet plate or the diameter of the spherical surface. The method of claim 1, Each said compression spring is a robot type grip exchange apparatus characterized by consisting of a square spring. The method of claim 1, The upper body is a pair of positioning pins are assembled, the lower body is composed of a positioning groove for setting the positioning pin, the positioning groove is characterized in that the rigid guide bush is assembled Robotic grip changer. The method of claim 1, The lower part of the upper body and the upper part of the lower body are opposed to each other so that the connector hole is formed through one side, the male connector and the female connector are assembled. Robot-type grip change device, characterized in that configured to be connected to the tool by a connection adapter. The method according to claim 1 or 13, The upper body is a sensor assembly hole is processed at intervals of 120 degrees and the extraction hole is penetrated into the connector hole therein, the sensor assembly hole is a contact sensor or a non-contact sensor is assembled and connected to the male connector through the extraction hole Robotic grip exchange device characterized in that. The method of claim 1, The plunger hole of the upper body is a robot-type grip exchange device, characterized in that the airtight ring and the guide bushing of the copper material is assembled to maintain the airtight between the plunger and the contact.

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