JPH0584691A - Industrial robot device for vacuum chamber - Google Patents

Abstract

PURPOSE:To realize miniaturization of an industrial robot for performing work in a vacuum chamber and further to prevent contamination of the vacuum chamber according to increase of a pressure difference by holding the pressure difference between the inside/outside of the industrial robot to a predetermined value, so that a small air-tight seal of low pressure resistance can be applied. CONSTITUTION:An industrial robot R set up in a vacuum chamber C has a plurality of shaftings, and each shafting is mutually ventilatably connected and sealed with an air-tight seal mounted on each rotary shaft. A gas feeder 31 for supplying cooling gas and a robot vacuum device 32 for discharging the cooling gas are connected to the industrial robot R, and a chamber vacuum device 40 for discharging gas in the chamber C is connected to the vacuum chamber C. Further, an industrial robot device provides a differential pressure holding means 35 for holding a differential pressure between an internal pressure of the industrial robot R and a pressure in the vacuum chamber C to a predetermined differential pressure and an interruption controlling means M for closing operating valves 33, 34 of the gas feeder 31 when the differential pressure exceeds an upper limit value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial robot apparatus for a vacuum chamber equipped with an industrial robot installed in the vacuum chamber to carry out work.

[0002]

2. Description of the Related Art Generally, an automatic device for performing work in a state where the whole device is installed in a vacuum chamber is disclosed in
It is disclosed and disclosed in Japanese Laid-Open Patent Application No. 2-158757 and Japanese Utility Model Laid-Open No. 1-153638. This kind of automatic device
Since the work weight that can be handled is limited and the operating range is narrow, the application target is limited to light work and only simple work can be performed. On the other hand, in the manufacturing process of, for example, a magnetic disk or a liquid crystal panel display, it is required to be able to handle and process a work in a vacuum chamber more freely and efficiently even with a light work, with high work accuracy. Are being made, and in order to meet these demands,
The introduction of industrial robots is under consideration.

[0003]

Therefore, it is conceivable to install an industrial robot in the vacuum chamber. In that case, heat generated by a motor or the like incorporated inside is removed and a lubricant is used. Evaporation becomes a problem. In a vacuum environment, heat is mainly dissipated by radiation, so the generated heat cannot be sufficiently removed into the atmosphere, and ordinary lubricating oil and grease evaporate immediately.
Because it will be dissipated. By the way, if the heat radiation is insufficient, serious failures such as coil burnout and malfunction due to local temperature rise are likely to occur.

On the other hand, in order to solve the above-mentioned problems, a cooling gas such as air is introduced into the inside of the industrial robot, and the cooling gas is brought into contact with the heating element in the same manner as in a normal environment, and its conduction action and It is possible to dissipate heat by convection. In such a case, an airtight seal is provided for each axis system of the industrial robot to prevent the cooling gas from flowing into the vacuum chamber. Technically, it is simple to use a vacuum seal with high pressure resistance as the airtight seal.

However, the vacuum seal has a larger frictional resistance than the airtight seal used under normal pressure, and the seal structure itself is complicated, so that the size of the robot itself becomes large. It is sufficient if the airtight seal used under normal pressure can be applied as it is,
Since the pressure resistance is low, the seal easily breaks.

The present invention has been made in view of the above problems, and an object thereof is to control a pressure difference between the inside and the outside of an industrial robot to a predetermined state so as to provide a compact, low-friction airtight seal with low pressure resistance. It is possible to apply it and realize miniaturization of the industrial robot that works in the vacuum chamber, and when the above pressure difference exceeds the upper limit, by controlling to close the operation valve of the air supply device, It is to prevent the hermetic seal from being broken and a large amount of cooling gas flowing into the vacuum chamber to contaminate the inside of the vacuum chamber.

[0007]

In order to achieve the above object, the means taken by the present invention is that an industrial robot installed in a vacuum chamber for performing work has a plurality of shaft systems, each of which has a plurality of shaft systems. The shaft system is composed of an articulated robot connected via a rotary shaft, the shaft systems are communicably connected to each other, and sealed by an airtight seal for normal pressure mounted on each rotary shaft, An air supply device for supplying cooling gas and a robot vacuum device for exhausting cooling gas are connected to the industrial robot via at least operation valves such as electromagnetic valves and pneumatic valves, and the vacuum chamber is connected to the vacuum chamber. A chamber vacuum device for evacuating the gas in the vacuum chamber is connected, and the differential pressure between the internal pressure of the industrial robot and the internal pressure of the vacuum chamber is maintained at a preset predetermined differential pressure. Differential pressure protection Means a requirement that is provided.

The predetermined differential pressure is, for example, 0.1 to 0.2.
Set to the range of atm. This is for the following reason. First, with respect to the lower limit of 0.1 atm, the heat radiating action by the cooling gas becomes insufficient in a pressure state below this, and the heat-generating component falls into an overheated state. On the other hand, the upper limit value is determined by the pressure resistance performance of the airtight seal to be applied. For example,
When using an airtight seal designed with a pressure resistance of 0.2 atm, if the differential pressure exceeds 0.2 atm, the seal may break and the industrial robot itself may be damaged, making it difficult to seal the shaft. Because.

Here, the low pressure-proof airtight seal means a normal-type airtight seal used for shaft sealing under normal pressure,
It shall include oil seals and magnetic fluid seals.

In order to maintain the differential pressure in a predetermined state, the opening of the control valve is controlled by the differential pressure holding means from the internal pressure of the industrial robot and the pressure in the vacuum chamber,
It is realized by controlling the exhaust speed of the gas in each space.

Further, in order to prevent the industrial robot and the airtight seal from being damaged due to an abnormal rise in the differential pressure, and at the same time, to prevent a large amount of gas from flowing into the vacuum chamber to contaminate the vacuum environment, Is a fixed upper limit value, for example 0.2
When a state of exceeding atm occurs, the shutoff control means instantaneously closes the operation valve to shut off the internal space of the robot from the atmosphere side.

[0012]

With the above construction, in the present invention, in the operating state, the cooling gas such as air or helium is fed to the inside of the industrial robot by the air feeding device, and this cooling gas causes the heat-generating component. Have taken away the heat. The cooling gas that has completed the heat exchange is recovered by the robot vacuum device. At this time, the differential pressure between the inside and outside of the industrial robot is maintained, for example, at 0.1 to 0.2 atm. Therefore, even though the airtight seal for low pressure resistance is used, each rotary shaft should be sealed.
It can be surely performed like an airtight seal for high pressure. As described above, in the seal mode using the low pressure resistant airtight seal, the frictional resistance of the rotating shaft can be reduced and the seal structure can be downsized as compared with the high pressure resistant airtight seal.
Constructing the industrial robot with an articulated robot in which each axis system is connected via a rotary shaft also helps to simplify the seal structure at the connection portion of each axis system. This is because all the objects to be sealed are the rotating shafts, and thus the shaft can be sealed with a small airtight seal such as an oil seal or a magnetic fluid seal.

When the pressure difference between the pressure inside the industrial robot and the pressure inside the vacuum chamber exceeds a certain upper limit,
Since the shutoff control means controls to close the operation valve, the cooling gas in the industrial robot does not flow into the vacuum chamber.

[0014]

Therefore, according to the present invention, the industrial robot is configured as a multi-joint robot in which each axis system is connected via the rotary shaft, and the cooling gas is introduced into the inside of the industrial robot to generate heat such as a motor. With respect to the cooling, the differential pressure inside and outside the industrial robot is maintained in a predetermined state so that the pressure load acting on the airtight seal of each rotary shaft can be relaxed. Therefore, each rotary shaft can be reliably sealed with a low pressure resistant airtight seal as well as a high pressure resistant airtight seal, compared to the case of using a high pressure resistant airtight seal. Further, it is possible to reduce the frictional resistance that the rotary shaft receives, and at the same time, it is possible to reduce the size of the seal structure, and to reduce the size of the industrial robot used in the vacuum chamber as a whole.

Moreover, when the differential pressure exceeds the upper limit value due to, for example, a failure of the control valve, the operating valve is closed,
Since a large amount of cooling gas does not flow into the industrial robot and therefore does not flow into the vacuum chamber, pollution of the environment inside the vacuum chamber is effectively prevented.

[0016]

Embodiments of the present invention will now be described in detail with reference to the drawings.

As shown in FIGS. 1 to 5, an industrial robot apparatus for a vacuum chamber is constructed by housing an industrial robot R in a vacuum chamber C, and FIG. 2 shows the appearance of the industrial robot R. Shows. The industrial robot R is a multi-joint robot having first to sixth axis systems 1 to 6, and each axis system 1 to 6 is connected via a rotation axis. Each can be rotated as shown by the arrow.
The sixth axis system 6 is a robot hand that captures a work. Of the rotating shafts that connect the shaft systems 1 to 6, the first to the fourth
As shown in FIGS. 3 and 4, the rotary shafts of the shaft systems 1 to 4 are respectively sealed with an airtight seal 8A having an oil seal 7 as a sealing element, and the remaining rotary shafts of the shaft systems 5 and 6 are As shown in FIG. 5, each is sealed with an airtight seal 8B made of a magnetic fluid seal.

In FIG. 3, the second shaft system 2 is rotatably supported by the first shaft system 1 via a cross roller bearing 10 and a harmonic speed reducer 11, and has a rotating shaft 12A and a first shaft 12A. The space between the shaft system 1 and the case end wall 13 is sealed by an airtight seal 8A. The harmonic speed reducer 11 inherits the power of the motor (not shown) via the transmission gear 14, decelerates the number of revolutions, and outputs the decelerated speed. The decelerated power is transmitted to the rotating shaft 12A via the passive body 15 having a cylindrical structure. The first shaft system 1 and the second shaft system 2 are communicated with each other via a passage 16 which extends vertically through the reduction shaft 11a. The other shaft systems are similarly connected.

In FIG. 4, the airtight seal 8A is composed of two oil seals 7, 7 press-fitted into the case end wall 13 and a vacuum grease 17 filled between the two seals 7, 7 The lip portion 7a of the oil seal 7 is located on the external space side, and the oil seal 7 on the inner side is the lip portion 7a.
With a being located on the inner space side of the case end wall 13,
Wear each. The outer oil seal 7 is retained and supported by a ring 18 fixed to the case end wall 13. 1
9 is a seal spring.

In FIG. 5, the sixth shaft system 6 is rotatably supported by the fifth shaft system 5 via a cross roller bearing 21 and a harmonic speed reducer 22, and its rotary shaft 12B and the fifth shaft system 6 are supported. The space between the system 5 and the case end wall 23 is sealed by an airtight seal 8B. Harmonic reducer 22
Is the drive shaft 2 which is adjusted in the same manner as the drive mechanism described above.
The power after deceleration is output to the rotary shaft 12B via the passive body 25 that also serves as the inner race of the cross roller bearing 21. In this case as well, the two shaft systems 5 and 6 are communicatively connected to each other through a communication pipe 26 that vertically extends through the harmonic speed reducer 22 and the drive shaft 24. The above connection mechanism is also adopted between the fourth shaft system 4 and the fifth shaft system 5.

As described above, the airtight seal 8B provided at the above connecting portion is a magnetic fluid seal. The holding plates 28, 28 made of a ferromagnetic material are fixed to both sides of the ring-shaped magnet 27, and the holding plates 28, 28 and the rotating shaft 12 are fixed.
The magnetic fluid 29 is interposed between the magnetic fluid 29 and B. The magnetic fluid seal is used because the seal structure can be downsized and the load on the drive system can be reduced as compared with the case where an oil seal is used as a sealing element. In the first to fourth shaft systems 1 to 4, there is a sufficient margin for the motor output, so such consideration is unnecessary.

As shown in FIG. 1, the industrial robot R described above is installed on the floor of a vacuum chamber C. Inside the industrial robot R, a large number of heat-generating components such as motors are housed. In order to cool these heat generating parts,
An air supply device 31 (including a simple gas cylinder) for supplying a cooling gas is provided, and a robot vacuum device 32 for forcibly exhausting the cooling gas is also provided. Both of these devices 31, 3
2 is connected to the inside of the industrial robot R through operation valves 33 and 34 which are normally kept fully open and abnormally kept fully closed, but the air supply device 31 is connected to the first axis system 1 for the robot. The vacuum device 32 is connected to the sixth shaft system 6. This is because the cooling gas is evenly circulated inside the industrial robot R. In addition to the above, an opening / closing valve 37 and a filter 38 are provided in a state of communicating with the internal space of the first shaft system 1, and the internal pressure can be monitored by a pressure gauge 39. The vacuum chamber C is evacuated by a dedicated chamber vacuum device 40. The chamber vacuum device 40 is connected to the inside of the vacuum chamber C, and its internal pressure is measured by the pressure gauge 4
Monitored by 2.

On the discharge side of the air supply device 31,
The electric function that functions as the differential pressure holding means in the present invention
An air regulator 35 is interposed, and the electro-pneumatic regulator 35 converts an electric signal into a pressure signal according to a linear input / output characteristic as shown in FIG.
The electro-pneumatic regulator 35 and both operation valves 33, 34
Is connected to the controller M, and is controlled by the controller M as follows.

That is, when the pressure signals from the pressure gauges 39 and 42 are received, the difference ΔS between the pressure difference between the pressure gauges 39 and 42 and the target pressure difference (eg 0.15 atm) is calculated. Then, when this deviation ΔS is “0”, the reference point (Vo in FIG. 6) of the input electric signal is determined so as to output the optimum supply pressure (Po in FIG. 6) obtained by the experiment, and the deviation ΔS is When it is a positive value, an electric signal equal to or lower than Vo is output, and when the deviation ΔS is a negative value, Vo is output.
The above electric signal is output from the controller M to the electropneumatic regulator 35 as a differential pressure signal. In accordance with this differential pressure signal, the electro-pneumatic regulator 35 supplies a pressure according to the characteristics shown in FIG. Due to the supply pressure adjusting action of the electro-pneumatic regulator, the differential pressure between the inside of the industrial robot R and the inside of the vacuum chamber C is held at a predetermined value set in advance,
For example, it is maintained in the range of 0.1 to 0.2 atm. That is, the differential pressure inside and outside of this industrial robot R is set to 0.1 atm.
When the cooling gas is smaller than a certain degree, the cooling gas in the industrial robot R becomes lean, and when the cooling gas becomes lean, the heat radiation amount of the heat-generating component is reduced, and gradually falls into an overheated state.
It is set to avoid this. Further, if the differential pressure is larger than about 0.2 atm, the industrial robot R itself may be damaged due to the possibility of seal breakage. Therefore, in the atmospheric pressure type hermetic seals 8A, 8B, etc., the shaft portion cannot be sealed. It will be difficult.

The structure of the differential pressure holding means is the same as the above-mentioned electric
The air regulator 35 is not limited to the air regulator 35. For example, a control valve may be provided on the discharge side or the suction side of the air supply device 31 to control the opening thereof to keep the differential pressure constant, or A leak valve for discharging the cooling gas inside the industrial robot into the vacuum chamber C may be provided, and the leak valve may be opened when the differential pressure exceeds a certain value.

Further, the controller M receives signals from both the pressure gauges 39 and 42, and the differential pressure between the inside of the industrial robot R and the inside of the vacuum chamber C reaches an upper limit value (for example, 0.2 atm).
) When the pressure rises above the above, the control valves 33 and 34 are controlled so as to be closed, and the controller M functions as the shutoff control means in the present invention.

When the internal pressure of the industrial robot R abnormally rises above 0.2 atm. During operation, the airtight seals 8A and 8B are broken, and the surrounding structures are disassembled for repair. Need to do. In order to save such trouble, an opening that connects the internal space and the vacuum chamber C is provided on the outer wall of the first shaft system, and the opening is closed airtight by the rupture plate 43. The rupture plate 43 cannot prevent the increase of the internal / external differential pressure as a result of closing the operation valves 33, 34 when the internal / external differential pressure of the industrial robot R exceeds 0.2 atm, resulting in damage to the airtight seals 8A, 8B. Limit (eg 0.3 atm.)
When it exceeds, the partition is broken and the internal pressure is released.

Next, the operation procedure of each of the above devices will be described.

First, the operation valve 34 is opened to activate each of the vacuum devices 32 and 40 to evacuate the inside of the vacuum chamber C and the industrial robot R. At this time, the industrial robot R
In order to prevent a pressure difference between the inside and the outside, the open / close valve 37 is opened, and the internal space of the industrial robot R is communicated with the vacuum chamber C. When the pressure in the vacuum chamber C drops to a predetermined state (10 ⁻³ Torr), the opening / closing valve 37 is closed to shut off the internal space of the industrial robot R from the vacuum chamber C. In this state, the operation valve 33 is opened and the air supply device 31 is opened.
Is supplied with a cooling gas such as helium or clean and dry air, and the cooling gas is caused to flow from the first shaft system 1 to the sixth shaft system 6. The robot vacuum device 32 continues to operate.

By adjusting the supply pressure with the electro-pneumatic regulator 35, the pressure difference between the inside and outside of the industrial robot R is maintained within the range of 0.1 to 0.2 atm, and the heat radiation effect by the cooling gas is maintained. However, the pressure load that acts on the airtight seal of each rotating shaft is eased, which enables downsizing of the industrial robot.

At this time, for example, the electro-pneumatic regulator 35
When the differential pressure exceeds the upper limit value (0.2 atm) due to a failure of the differential pressure holding means such as, the controller M (shutdown control means) controls the operation valves 33 and 34 to be closed, and the industrial robot R It is designed so that a large amount of cooling gas does not flow into the interior. Therefore, the cooling gas does not flow into the vacuum chamber S, and the pollution of the environment inside the vacuum chamber C is effectively prevented.

[Brief description of drawings]

FIG. 1 is a principle explanatory view showing the content of the present invention.

FIG. 2 is a side view of an industrial robot.

FIG. 3 is a sectional view of a connecting portion between the first shaft system and the second shaft system.

FIG. 4 is a cross-sectional view showing details of the seal structure in FIG.

FIG. 5 is a cross-sectional view of a connecting portion between a fifth shaft system and a sixth shaft system.

FIG. 6 is an input / output characteristic diagram of an electro-pneumatic regulator.

[Explanation of symbols]

 1 1st shaft system 2 2nd shaft system 3 3rd shaft system 4 4th shaft system 5 5th shaft system 6 6th shaft system 8A, 8B Airtight seal 12A, 12B Rotating shaft 31 Air supply device 32 Robot vacuum device 33 , 34 Operation valve 35 Electro-pneumatic regulator (Differential pressure holding means) 40 Chamber vacuum device R Industrial robot C Vacuum chamber M Controller (cut-off control means)

Claims (1)

[Claims] 1. An industrial robot apparatus for a vacuum chamber, comprising an industrial robot installed in a vacuum chamber for performing work, wherein said industrial robot has a plurality of axis systems, each axis system being a rotary axis. It is composed of an articulated robot connected via the above, each axis system is communicated with each other in a freely ventilated manner, and is sealed by an airtight seal attached to each rotary axis. An air supply device for supplying and a robot vacuum device for exhausting the cooling gas are respectively connected through operation valves, and a chamber vacuum device for exhausting the gas in the vacuum chamber has a control valve in the vacuum chamber. On the other hand, the differential pressure holding means for holding the differential pressure between the internal pressure of the industrial robot and the pressure in the vacuum chamber at a preset predetermined differential pressure is provided, and the differential pressure is constant. of If it exceeds the limit value, the vacuum chamber for industrial robot, characterized in that cut-off control means for controlling so as to close the both operating valve is provided.