JPH04365582A - Industrial robot equipment for vacuum chamber - Google Patents

Abstract

PURPOSE:To reduce the size of an industrial robot which is suitable for a small seal, such as an airtight seal used under an atmospheric pressure, having lower pressure resistance and effects work in a vacuum chamber by controlling a pressure difference between the inside and the outside of the industrial robot to a given state. CONSTITUTION:An industrial robot R installed in a vacuum chamber C and effecting a work has a plurality of shaft systems and the shaft systems are interconnected through a rotary shaft. The shaft systems are intercommunicated in a ventilatable manner, and sealed with an airtight seal for an atmospheric pressure mounted on each rotary shaft. An air feed device 31 to feed cooling gas and a vacuum device 32 for a root to discharge cooling gas are respectively connected to the industrial robot R, and a vacuum device 40 for chamber to discharge gas in the vacuum chamber C is connected to the vacuum chamber C. Further, a differential pressure holding means V to hold a differential pressure between the internal pressure of the industrial robot R and a pressure in the vacuum chamber C at a preset given value is provided.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an industrial robot device for a vacuum chamber, which is equipped with an industrial robot that is installed in a vacuum chamber and performs work.

0002

2. Description of the Related Art Generally, automatic equipment that performs work with the entire equipment installed inside a vacuum chamber, for example,
It is disclosed in Japanese Unexamined Patent Publication No. 2-158757, Japanese Utility Model Application Publication No. 1-153638, and the like. This kind of automatic equipment is
There is a limit to the weight of the workpiece that can be handled, and the range of motion is narrow, so it can only be applied to light work and can only perform simple tasks. On the other hand, in the manufacturing process of magnetic disks, for example, there is a growing need to be able to handle and process workpieces in a vacuum chamber more freely, efficiently, and with high precision even when handling heavy workpieces. In order to meet these demands, the introduction of industrial robots is being considered.

0003

[Problems to be Solved by the Invention] Therefore, it is conceivable to install an industrial robot inside a vacuum chamber, but in that case, it would be necessary to remove the heat generated from the internal motor, etc., and to remove the lubricant. Evaporation becomes a problem. In a vacuum environment, heat is dissipated primarily by radiation, so the generated heat cannot be removed sufficiently, and ordinary lubricating oils and greases quickly evaporate and dissipate. Incidentally, if heat dissipation is insufficient, serious failures such as burnout of the coil or malfunction due to localized temperature rise are likely to occur.

On the other hand, in order to solve the above problems, a cooling gas such as air is introduced into the interior of an industrial robot, and the cooling gas is brought into contact with a heating element in the same way as in a normal environment.
It is thought that heat is radiated by the conduction effect and the convection effect. In such a case, an airtight seal is provided for each axis system of the industrial robot to prevent cooling gas from leaking into the vacuum chamber. Technically, it is simple to use a vacuum seal with high pressure resistance as the airtight seal.

[0005] However, a vacuum seal has greater frictional resistance than an airtight seal used under normal pressure, and the seal structure itself is complicated, resulting in an increase in the size of the robot itself. It would be good if the airtight seal used under normal pressure could be applied as is.
Seal breakage occurs easily due to low pressure resistance.

[0006] The present invention was made in view of the above, and by controlling the pressure difference between the inside and outside of an industrial robot to a predetermined state, it is possible to apply a small, low-friction airtight seal with low pressure resistance. The objective is to realize the miniaturization of industrial robots that perform work inside vacuum chambers.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the means taken by the present invention is that an industrial robot that is installed in a vacuum chamber and performs work has a plurality of axis systems, each of which has a plurality of axes. The shaft systems are composed of articulated robots connected via rotating shafts, each of the shaft systems is in communication with each other in a freely ventilated manner, and is sealed with a normal pressure airtight seal attached to each rotating shaft; The industrial robot is connected to an air supply device that supplies cooling gas and a robot vacuum device that exhausts the cooling gas, and the vacuum chamber has a chamber vacuum device that exhausts the gas in the vacuum chamber. It is required that a differential pressure holding means is provided to maintain the differential pressure between the internal pressure of the industrial robot and the pressure in the vacuum chamber at a predetermined differential pressure set in advance.

[0008] The predetermined differential pressure, for example, 0.1 to 0.2a
Set in the range of tm. This is due to the following reasons. First, regarding the lower limit of 0.1 atm, this is because if the pressure is lower than this, the heat dissipation effect of the cooling gas will be insufficient and the heat generating components will fall into an overheated state. On the other hand, the upper limit value is determined by the pressure resistance of the airtight seal to be applied. For example, when using an airtight seal designed to withstand a pressure of 0.2 atm, if the differential pressure exceeds 0.2 atm, the seal will break and the industrial robot itself may be damaged, causing the shaft to be sealed. This is because it becomes difficult.

[0009] Here, the airtight seal for low pressure resistance refers to a normal type of airtight seal used for shaft sealing under normal pressure.
This includes oil seals, magnetic fluid seals, etc.

[0010] In order to maintain the differential pressure at a predetermined state, the industrial robot is equipped with a leak valve that releases the cooling gas inside the industrial robot into the vacuum chamber, and the leak valve is opened and closed according to the differential pressure state. It is possible to take the form of

[0011] Furthermore, in order to prevent damage to the industrial robot and the airtight seal due to an abnormal increase in differential pressure, an opening is provided in the external wall of the industrial robot to communicate the space inside the industrial robot with the inside of the vacuum chamber. A safety measure can be taken in which the opening is hermetically closed with a rupture disc that ruptures when the differential pressure exceeds a predetermined value, for example, 0.2 atm.

0012

[Operation] With the above configuration, in the present invention, in the operating state, a cooling gas such as air or helium is fed into the interior of the industrial robot by the air supply device, and this cooling gas generates heat generated by the heat generating parts. It takes away the heat. After the heat exchange, the cooling gas is recovered by a robot vacuum device. At this time, the differential pressure between the inside and outside of the industrial robot is maintained at, for example, 0.1 to 0.2 atm. This can be done reliably in the same way as a pressure-tight airtight seal. As described above, in the seal form using the airtight seal for low pressure resistance, the frictional resistance of the rotating shaft can be reduced compared to the airtight seal for high pressure resistance, and the seal structure can be simplified. Configuring the industrial robot as an articulated robot in which each axis system is connected via a rotating shaft also helps to simplify the seal structure at the connection part of each axis system. This is because all the objects to be sealed are rotating shafts, so shaft sealing can be performed with a small airtight seal such as an oil seal or a magnetic fluid seal.

[0013]

Therefore, according to the present invention, an industrial robot is constructed as an articulated robot in which each axis system is connected via a rotating shaft, and cooling gas is introduced into the robot to cool heat-generating parts such as motors. In order to cool the industrial robot, the differential pressure between the inside and outside of the industrial robot is maintained at a predetermined level, so that the pressure load acting on the airtight seals of each rotating shaft can be alleviated. Therefore, it is possible to seal each rotating shaft with a low pressure hermetic seal as reliably as a high pressure hermetic seal, and compared to using a high pressure hermetic seal. In addition, the frictional resistance exerted on the rotating shaft can be reduced, and the seal structure can also be made smaller, making it possible to downsize the industrial robot used inside the vacuum chamber as a whole.

[0014]

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

As shown in FIGS. 1 to 5, the vacuum chamber industrial robot device is constructed by housing an industrial robot R in a vacuum chamber C, and FIG. 2 shows the external appearance of the industrial robot R. It shows. The industrial robot R is an articulated robot having first to sixth axis systems 1 to 6, each of which is connected via a rotating shaft, and each axis system 1 to 6 is Each can be rotated as shown by the arrows. Note that the sixth axis system 6 is a robot hand that captures the workpiece. Among the rotating shafts connecting each shaft system 1 to 6, the first to fourth
The rotating shafts of the shaft systems 1 to 4 are each sealed with an airtight seal 8A having an oil seal 7 as a sealing element, as shown in FIGS. 3 and 4, and the rotating shafts of the remaining shaft systems 5 and 6 are As shown in FIG. 5, they are each 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 reduction gear 11, and the second shaft system 2 is rotatably supported by the first shaft system 1 through a cross roller bearing 10 and a harmonic reduction gear 11. 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 power from a motor (not shown) via a transmission gear 14, reduces its rotational speed, and outputs the reduced speed. The decelerated power is transmitted to the rotating shaft 12A via the cylindrical passive body 15. The first shaft system 1 and the second shaft system 2 are communicated with each other via a passage 16 that runs longitudinally through the deceleration shaft 11a. Other shaft systems are also connected in the same way.

In FIG. 4, the airtight seal 8A consists of two oil seals 7, 7 press-fitted into the case end wall 13, and vacuum grease 17 filled between these two seals 7, 7. The lip portion 7a of the oil seal 7 is located on the outside space side, and the inner oil seal 7 has the lip portion 7a located on the outside space side.
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 to prevent it from coming off. 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 reduction gear 22, and the sixth shaft system 6 is rotatably supported by the fifth shaft system 5 through 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
In this case, the adjusted power is transmitted to the drive shaft 2 in the same way as the above-mentioned drive mechanism.
4, and outputs the decelerated power to the rotating shaft 12B via the passive body 25, which also serves as the inner race of the cross roller bearing 21. Here again, both shaft systems 5 and 6 are communicated with each other in a ventilated manner via a communication pipe 26 that passes longitudinally through the harmonic reduction gear 22 and the drive shaft 24. The above connection mechanism is also adopted between the fourth axis system 4 and the fifth axis system 5.

As mentioned above, the airtight seal 8B provided at the connection portion is composed of a magnetic fluid seal. This is achieved by fixing holding plates 28, 28 made of ferromagnetic material on both sides of a ring-shaped magnet 27, and fixing the holding plates 28, 28 and the rotating shaft 12.
A magnetic fluid 29 is interposed between it and B. The reason why a magnetic fluid seal is used is that the seal structure can be made smaller and the load on the drive system can be reduced compared to when an oil seal is used as a sealing element. In the first to fourth axis systems 1 to 4, there is sufficient margin in the motor output, so such considerations are unnecessary.

As shown in FIG. 1, the above-mentioned industrial robot R is installed on the floor inside a vacuum chamber C. A large number of heat-generating parts such as motors are housed inside the industrial robot R. In order to cool these heat generating parts,
An air supply device 31 (including a simple gas cylinder) for supplying cooling gas is provided, and a robot vacuum device 32 for forcibly exhausting the cooling gas is also provided. Both these devices 31, 3
2 is connected to the inside of the industrial robot R via control valves 33 and 34, the air supply device 31 is connected to the first shaft system 1, and the robot vacuum device 32 is connected to the sixth shaft system 6. This is to circulate the cooling gas evenly inside the industrial robot R. In addition to the above, a leak valve 35, a filter 36, an on-off valve 37, and a filter 38 are provided in communication with the internal space of the first shaft system 1, and a pressure gauge 39 is provided to monitor the internal pressure. Further, the vacuum chamber C is evacuated by a chamber vacuum device 40 dedicated for this purpose. This chamber vacuum device 40 is connected to the inside of the vacuum chamber C via a control valve 41. 42 is a pressure gauge.

[0021] The control valve 34 and the leak valve 3
5, the filter 36, the on-off valve 37, and the filter 38 constitute a differential pressure holding means V.
maintains the differential pressure between the inside of the industrial robot R and the inside of the vacuum chamber C at a predetermined value, for example, 0.1.
It is maintained within the range of ~0.2 atm. When the pressure difference between the inside and outside of this industrial robot R is made smaller than about 0.1 atm, the cooling gas inside the industrial robot R becomes diluted, and when this cooling gas becomes diluted, the amount of heat dissipated from the heat generating parts decreases, and gradually This setting is necessary to avoid overheating. Furthermore, if the differential pressure is made larger than about 0.2 atm, there is a risk of seal failure and damage to the industrial robot R itself, making it difficult to seal the shaft with normal pressure type airtight seals 8A, 8B, etc. It is from.

[0022] Furthermore, if the internal pressure of the industrial robot R increases abnormally during operation, each of the airtight seals 8A, 8B will break, making it necessary to disassemble the surrounding structures for repair. In order to save such effort, an opening is provided in the external wall of the first shaft system to communicate the internal space with the vacuum chamber C, and this opening is hermetically closed with a rupture disc 43. The rupture disc 43 has a pressure difference between the inside and outside of the industrial robot R of 0.
When the pressure exceeds 2 atm, the partition wall ruptures and releases the internal pressure.

Next, the operating procedures of each of the above devices will be explained.

First, the control valves 34 and 41 are opened to start the respective vacuum devices 32 and 40, 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 between the inside and outside of 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 inside the vacuum chamber C drops to a predetermined state (10-3 Torr),
The on-off valve 37 is closed to shut off the interior space of the industrial robot R from the vacuum chamber C. In this state, the control valve 33 is opened to supply cooling gas made of inert gas such as helium or clean and dry air from the air supply device 31, and the cooling gas is transferred from the first shaft system 1 to the sixth shaft system 6. Let it flow. The robot vacuum device 32 continues to operate.

As the cooling gas is supplied, the internal pressure of the industrial robot R increases, but when the pressure difference between the inside and outside of the industrial robot R, that is, the differential pressure reaches 0.2 atm, the leak valve 35 is activated. A portion of the cooling gas is released into the vacuum chamber C to prevent the internal pressure from increasing further. The filter 36 removes foreign substances contained in the emitted gas to prevent the inside of the vacuum chamber C from being contaminated with foreign substances. The leak valve 35 may detect the pressure state inside and outside the industrial robot R using pressure gauges 39 and 42, and open or close the valve body based on the detection results.

For example, a difference occurs between the amount of gas supplied by the air supply device 31 and the amount of gas exhausted by the robot vacuum device 32, and the differential pressure between the inside and outside of the industrial robot R becomes 0.1 atm.
When the pressure drops to , the leak valve 35 closes the passage and waits for the differential pressure to recover. Thereafter, while repeating opening and closing of the leak valve 35, the differential pressure between the inside and outside of the industrial robot R is set to 0.1 to 0.2 at.
m range.

In the above embodiment, the leak valve 35 is simply a relief valve, but it may also be a valve that is forcibly opened and closed by differential pressure.

[Brief explanation of drawings]

FIG. 1 is a diagram explaining the principle of the invention.

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

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

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

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

[Explanation of symbols]

1 First axis system 2 Second axis system 3 3rd axis system 4 4th axis system 5 5th axis system 6 6th axis system 8A, 8B Airtight seal 12A, 12B Rotation axis 31 Air supply device 32 Vacuum equipment for robots 40 Vacuum equipment for chamber 43 Rupture disc R Industrial robot C Vacuum chamber V Differential pressure holding means

Claims (3)

[Claims] 1. An industrial robot device for a vacuum chamber, comprising an industrial robot installed in a vacuum chamber to perform work, wherein the industrial robot has a plurality of axis systems, each axis system being a rotation axis. The industrial robot is composed of articulated robots connected via An air supply device for supplying air and a robot vacuum device for exhausting the cooling gas are connected to each other, and a chamber vacuum device for exhausting the gas in the vacuum chamber is connected to the vacuum chamber, while the industrial robot 1. An industrial robot device for a vacuum chamber, characterized in that a differential pressure holding means is provided for maintaining a differential pressure between the internal pressure of the vacuum chamber and the pressure inside the vacuum chamber at a predetermined differential pressure set in advance. [Claim 2] The differential pressure holding means is equipped with a leak valve that releases cooling gas inside the industrial robot into the vacuum chamber, and is configured so that the leak valve is opened or closed depending on the differential pressure state. The industrial robot device for vacuum chamber according to claim 1, characterized in that: 3. The external wall of the industrial robot is provided with an opening that communicates the space inside the industrial robot with the inside of the vacuum chamber, and a rupture disc that ruptures when the differential pressure exceeds a predetermined pressure differential is provided. 3. The industrial robot device for a vacuum chamber according to claim 1, wherein the opening is hermetically closed.