JP3089329B2 - Industrial robot equipment for vacuum chamber - Google Patents

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 having an industrial robot installed in a vacuum chamber for performing operations.

[0002]

2. Description of the Related Art Generally, an automatic apparatus for performing a work in a state where the entire apparatus is installed in a vacuum chamber is disclosed in
It is disclosed and known in Japanese Patent Application Laid-Open No. 2-158775 and Japanese Utility Model Application Laid-Open No. 1-153638. This kind of automatic device
The application target is limited to light work, such as a limited work weight that can be handled and the operating range is narrow, 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, there is a demand that the handling and processing of a workpiece in a vacuum chamber can be performed more freely and efficiently even with a non-lightweight workpiece with high working accuracy. And to meet these demands,
The introduction of industrial robots is under consideration.

[0003]

Therefore, it is conceivable to install an industrial robot in a vacuum chamber. In this case, it is necessary to remove heat generated from a motor or the like incorporated in the vacuum chamber or remove lubricant. Evaporation becomes a problem. In a vacuum environment, heat is mainly radiated by radiation, so that the generated heat cannot be sufficiently removed as in the atmosphere, and normal lubricating oils and greases evaporate and dissipate immediately. It is. By the way, if the heat radiation is insufficient, serious failures such as burnout of the coils and malfunctions 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 an industrial robot, and the cooling gas is brought into contact with the heating element in the same manner as in a normal environment. It is conceivable that heat is dissipated by convection. In such a case, an airtight seal is provided for each shaft 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 hermetic seal.

However, a vacuum seal has a higher frictional resistance than an airtight seal used under normal pressure, and the seal structure itself is complicated, so that the robot itself becomes larger. It is sufficient if the hermetic seal used under normal pressure can be applied as it is,
Seal breakdown easily occurs due to low pressure resistance.

[0006] The present invention has been made in view of the above points, and enables the application of a small, low-friction hermetic seal with low pressure resistance by controlling the pressure difference between the inside and outside of an industrial robot to a predetermined state. Another object of the present invention is to reduce the size of an industrial robot that operates in a vacuum chamber.

[0007]

In order to achieve the above-mentioned object, a means taken by the present invention is that an industrial robot which is installed in a vacuum chamber and performs work has a plurality of axis systems, and The shaft system is composed of an articulated robot connected via a rotating shaft, each of the shaft systems is communicated with each other in a freely permeable manner, and sealed with an airtight seal for normal pressure mounted on each rotating shaft, Industrial robots have a vacuum chamber inside the robot.
Air supply that supplies cooling gas at a pressure higher than the pressure in the chamber
A device, connected with the robot vacuum apparatus for evacuating the cooling gas supplied into the robot, the said vacuum chamber, the chamber for a vacuum apparatus for evacuating the gas in the vacuum chamber is connected, Discharge side arrangement of the above air supply device
The tube, the internal pressure of the industrial robot vacuum chamber
And the differential pressure between the two becomes
Is maintained at a specified differential pressure set according to the pressure resistance of the
As described above, it is required that a differential pressure control valve for adjusting the supply pressure from the air supply device be provided.

[0008] 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, when the pressure is lower than 0.1 atm, the heat radiation effect by the cooling gas becomes insufficient, and the heat-generating component falls into an overheated state. On the other hand, the upper limit is determined by the pressure resistance of the hermetic seal to be applied. For example,
When a hermetic seal designed with a pressure resistance of 0.2 atm is used, if the differential pressure exceeds 0.2 atm, seal breakage may occur and the industrial robot itself may be damaged, making it difficult to seal the shaft. Because.

Here, the hermetic seal for low withstand pressure means an ordinary hermetic seal used for shaft sealing under normal pressure.
An oil seal, a magnetic fluid seal, and the like are included.

The differential pressure control valve controls the opening degree of the valve based on the differential pressure between the internal pressure of the industrial robot and the pressure in the vacuum chamber, and controls the pressure of the cooling gas supplied from the air supply device, that is, the inflow speed. Has been realized.

[0011]

With the above arrangement, in the present invention, in the operating state, the air is supplied to the inside of the industrial robot by the air supply device .
A cooling gas such as air or helium having a pressure higher than the pressure in the vacuum chamber is supplied into the bot, and the cooling gas removes heat generated in the heat-generating components. After the heat exchange, the cooling gas is recovered by the robot vacuum device. At this time, the internal pressure of the industrial robot
And the differential pressure between the two, for example,
A place corresponding to the pressure resistance of the hermetic seal, such as 0.1 to 0.2 atm
Since the pressure difference is maintained at a constant value , the rotation shafts can be reliably sealed in the same manner as the high pressure-resistant hermetic seal despite the use of the low pressure-resistant hermetic seal. As described above, in the sealing mode using the low-pressure-resistant hermetic seal, the frictional resistance of the rotating shaft can be reduced as compared with the high-pressure-resistant hermetic seal.
Moreover, the size of the seal structure can be reduced. Industrial robots,
The configuration of an articulated robot in which each axis system is connected via a rotation axis also contributes to simplifying a seal structure at a connection portion of each axis system. This is because the entirety of the object to be sealed is the rotating shaft, so that the shaft can be sealed with a small hermetic seal such as an oil seal or a magnetic fluid seal.

[0012]

Therefore, according to the present invention, the industrial robot is constituted as an articulated robot in which each axis system is connected via a rotating shaft, and a cooling gas is introduced into the inside of the industrial robot by an air supply device. In order to cool heat-generating components such as air conditioners, a differential pressure control valve is provided on the discharge side of
So that the internal pressure is higher than the pressure in the vacuum chamber
By maintaining the pressure difference between the two in a predetermined state, the pressure load acting on the hermetic seal of each rotating shaft can be reduced. For this reason, each rotating shaft can be reliably sealed with a low pressure-resistant hermetic seal in the same way as a high pressure-resistant hermetic seal is used, compared with the case of using a high pressure-resistant hermetic seal. In addition, the frictional resistance applied to the rotating shaft can be reduced, and at the same time, the seal structure can be downsized, so that the industrial robot used in the vacuum chamber can be downsized as a whole.

[0013]

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

As shown in FIGS. 1 to 5, the industrial robot apparatus for a vacuum chamber has an industrial robot R housed in a vacuum chamber C. FIG. Is shown. The industrial robot R is a multi-joint robot having first to sixth axis systems 1 to 6, each of which is connected via a rotation axis. Each can be rotated as indicated by the arrow.
The sixth axis system 6 is a robot hand that captures a workpiece. Of the rotating shafts connecting the respective shaft systems 1 to 6, first to fourth
The rotating shafts of the shaft systems 1 to 4 are sealed with airtight seals 8A using the oil seal 7 as a sealing element, as shown in FIGS. 3 and 4, and the rotating shafts of the remaining shaft systems 5, 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 on the first shaft system 1 via a cross roller bearing 10 and a harmonic reduction gear 11, and its rotating shaft 12A and first The space between the shaft system 1 and the case end wall 13 is sealed with an airtight seal 8A. The harmonic reducer 11 receives the power of a motor (not shown) via a transmission gear 14, reduces the number of revolutions, and outputs the reduced speed. The decelerated power is transmitted to the rotating shaft 12A via the passive member 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 that vertically passes through the reduction shaft 11a. Other shaft systems are connected similarly.

In FIG. 4, the hermetic seal 8A is composed of two oil seals 7, 7 pressed into the case end wall 13 and a vacuum grease 17 filled between the two seals 7, 7. The oil seal 7 has a lip 7a located on the side of the external space, and the inner oil seal 7 has a lip 7
a is located on the side of the internal space of the case end wall 13,
Attach each. The outer oil seal 7 is supported by a ring 18 fixed to the case end wall 13 so as not to come off. 1
9 is a seal spring.

In FIG. 5, the sixth shaft system 6 is rotatably supported on the fifth shaft system 5 via a cross roller bearing 21 and a harmonic reducer 22. The space between the system 5 and the case end wall 23 is sealed with an airtight seal 8B. Harmonic reducer 22
Transmits the power adjusted in the same manner as the above-described drive mechanism to the drive shaft 2.
4, and outputs the decelerated power to the rotary shaft 12B via the passive body 25 which also serves as the inner race of the cross roller bearing 21. Also in this case, the two shaft systems 5 and 6 are communicated with each other through a communication pipe 26 that vertically passes through the harmonic reduction gear 22 and the drive shaft 24. The above connection mechanism is also employed between the fourth shaft system 4 and the fifth shaft system 5.

As described above, the hermetic seal 8B provided at the connection portion is made of a magnetic fluid seal. In this case, holding plates 28, 28 made of ferromagnetic material are fixed to both sides of a ring-shaped magnet 27, and the holding plates 28, 28 and the rotating shaft 12 are fixed.
B and a magnetic fluid 29 interposed therebetween. The reason for using the magnetic fluid seal is that the size of the seal structure can be reduced and the load on the drive system can be reduced as compared with the case where the oil seal is used as the sealing element. Since the first to fourth shaft systems 1 to 4 have a sufficient margin for the motor output, such consideration is unnecessary.

As shown in FIG. 1, the above-mentioned industrial robot R is installed on a floor in a vacuum chamber C. A large number of heat-generating components such as motors are housed inside the industrial robot R. In order to cool these heating components,
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 provided. Both devices 31, 32
Is connected to the inside of the industrial robot R,
Is the first shaft system 1, and the robot vacuum device 32 is the sixth shaft system 6.
Connect to This is because the cooling gas is circulated evenly inside the industrial robot R.

In addition to the above, an on-off valve 37 and a filter 38 are provided in communication 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, and the internal pressure thereof is monitored by a pressure gauge 42.

Here, on the discharge side of the air supply device 31, an electro-pneumatic regulator 35 functioning as a differential pressure control valve is provided, and the electro-pneumatic regulator 35 converts an electric signal into a pressure signal. As shown in FIG. 6, the output signal always has a linearity proportional to the input signal. Then, the electro-pneumatic regulator 35
Is connected to the controller M, and is controlled by the controller M as follows.

That is, upon receiving the pressure signals from the pressure gauges 39 and 42, a deviation ΔS between the pressure difference between the two and the target pressure difference (for example, 0.15 atm) is calculated. When the 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 positive. When the value is, that is, when the pressure difference is larger than the target pressure, an electric signal equal to or less than Vo is output as a differential pressure signal from the controller M to the electro-pneumatic regulator 35 when the deviation ΔS is a negative value. According to this differential pressure signal, electro-pneumatic regulation
The pressure according to the characteristic shown in FIG. By adjusting the pressure of the electro-pneumatic regulator 35, the pressure difference between the inside of the industrial robot R and the inside of the vacuum chamber C is maintained at a predetermined value.
It is kept in the range of 2 atm. If the pressure difference between the inside and outside of the industrial robot R is made smaller than about 0.1 atm, the cooling gas inside the industrial robot R becomes thin. It will be overheated and set to avoid this. When the differential pressure is larger than about 0.2 atm,
This is because the seal may be broken and the industrial robot R itself may be damaged, and it is difficult to seal the shaft portion with the normal-pressure hermetic seals 8A and 8B.

If the internal pressure of the industrial robot R rises abnormally during operation, seal breakage occurs in each of the hermetic seals 8A and 8B, and it is necessary to disassemble the peripheral structure for repairing the seals. In order to save such troubles, an opening for communicating the internal space with the vacuum chamber C is provided in the outer wall of the first shaft system, and the opening is closed in an airtight manner by the rupturable plate 43. The rupture disk 43 has a pressure difference between the inside and outside of the industrial robot R of 0.
When it exceeds 2 atm, the partition breaks and releases internal pressure.

Next, the operation procedure of each device will be described.

First, each of the vacuum devices 32 and 40 is activated, and the inside of the vacuum chamber C and the inside of the industrial robot R are evacuated. At this time, in order to prevent a pressure difference from occurring inside and outside the industrial robot R, the on-off 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 on-off valve 37 is closed to shut off the internal space of the industrial robot R from the vacuum chamber C. In this state, the air supply device 31 is operated to supply a cooling gas such as helium or clean and dry air while adjusting the supply pressure as described above, and supply the cooling gas from the first shaft system 1 to the sixth shaft system. Flow to 6. The robot vacuum device 32 is continuously operated.

Therefore, the supply pressure from the air supply device 31 is adjusted so that the pressure difference between the inside of the robot R and the inside of the vacuum chamber C is maintained at a predetermined pressure. Within the range of 0.2 atm), the pressure load acting on the hermetic seal of each rotating shaft is reduced, and the size can be reduced by using the hermetic seal for low pressure.

[Brief description of the drawings]

FIG. 1 is a principle explanatory diagram showing the contents of the present invention.

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

FIG. 3 is a cross-sectional view of a connection portion between a first shaft system and a second shaft system.

FIG. 4 is a sectional view showing details of a seal structure in FIG. 3;

FIG. 5 is a sectional view of a connection portion between a fifth axis system and a sixth axis system.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st-axis system 2 2nd-axis system 3 3rd-axis system 4 4th-axis system 5 5th-axis system 6 6th-axis system 8A, 8B Hermetic seal 12A, 12B Rotary axis 31 Air supply device 32 Vacuum device for robot 35 Electro-pneumatic regulator (differential pressure control valve) 40 Chamber vacuum device R Industrial robot C Vacuum chamber M Controller

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-48491 (JP, A) JP-A-63-162187 (JP, A) JP-A-4-3655582 (JP, A) 170587 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B25J 21/00 B25J 19/00

Claims (1)

(57) [Claims] 1. An industrial robot apparatus for a vacuum chamber provided with an industrial robot installed in a vacuum chamber for performing an operation, wherein the industrial robot has a plurality of axis systems, and each axis system is a rotary axis. It consists of a multi-joint robot which is connected via the said axes system is communicated freely vent to each other, are sealed in an airtight seal mounted on the rotary shaft, the said industrial robot, in the robot Inside the vacuum chamber
Air supply device that supplies cooling gas at a pressure higher than
When the robot vacuum apparatus for evacuating the cooling gas supplied into the robot is connected to the aforementioned vacuum chamber, while the chamber for a vacuum apparatus for evacuating the gas in the vacuum chamber is connected, said feeding The internal pressure of the above industrial robot becomes higher than the pressure in the vacuum chamber,
The differential pressure is set in advance according to the pressure resistance of the hermetic seal.
An industrial robot apparatus for a vacuum chamber, comprising a differential pressure control valve for adjusting a supply pressure from the air supply device so as to be maintained at a predetermined differential pressure .