JPH09254074A - Drop prevention mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the drop of a Z shaft by giving self-weight and force of equivalence of a workpiece and a structure which handles the workpiece from the outside and balancing self-weight of the workpiece in a conveyance device and a conveyance driving part by producing fluid pressure such as air pressure. SOLUTION: An output shaft 3b of a cylinder 3 is connected with a Z shaft drive part 7, and pressure 10 of supply air is adjusted by a regulator 8 to generate force which is balanced with the weight of the driving part 7. Consequently, a motor 6 which gives extremely small output can be adopted because the driving part 7 enters a gravity free condition in principle. Moreover, the regulator 8 of which is provided with a relief port 11 is adopted so that air immediately exhausted from the relief part 11 when secondary pressure 10 exceeds the set pressure and pressure inside the cylinder 3a is kept at the set pressure. Moreover, a workpiece and the drive part do not drop, even if driving force is lost due to the breakage and failure of a driving means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fall prevention mechanism for an industrial device having a vertical axis that works against gravity.

[0002]

2. Description of the Related Art Conventionally, in a transfer device having a vertical shaft that works against gravity, when a transmission mechanism that transmits power from a power source is damaged, the vertical shaft drive unit falls and the object to be transferred is damaged. There was a risk of

In order to avoid such a danger, in a conventional conveyor having a vertical axis, a method of balancing a weight equivalent to a symmetrical object to be conveyed by a pulley or the like is adopted.
As the weight of the object increases, it is necessary to make the weight larger and heavier. Therefore, it is necessary to increase the size of the transportation device itself. Further, in the conventional conveying device having a vertical axis, a drive source such as a motor is selected to match the maximum weight of the object to be conveyed, so that it is necessary to increase the power source as the maximum weight increases.

[0004]

In industrial equipment related to semiconductor manufacturing, liquid crystal panel manufacturing, etc., a wafer or glass plate as a work, a mask or reticle as a master,
Alternatively, a robot for positioning and transporting a cassette for storing these works and reticles at a predetermined position is provided. This transfer robot is usually composed of a plurality of drive shafts, and a vertically driven shaft, a so-called Z-axis, is formed therein.

The present invention has been made in view of the problems in the above-mentioned conventional example, and the first object of the present invention is to provide a work,
Also, the Z-axis is prevented from falling by applying a force equivalent to the own weight of the structure for handling the work from the outside. A second object of the present invention is to reduce the power source that drives the Z axis by applying an equivalent force to the Z axis, for example, to bring the load of the motor close to no load. A third object of the present invention is to detect the load applied to the power source when the weight of the work is not constant and change, and automatically change the load applied from the outside to finally generate a force equivalent to the work. That is.

[0006]

In order to achieve the above object, the fall prevention mechanism of the present invention is characterized in that the weight of the work and the transport drive section in the transport apparatus are balanced by generating fluid pressure such as pneumatic pressure. And In order to generate the fluid pressure, for example, when the weight of the work is constant, a piston and a cylinder are attached between a predetermined fixed part and a driving part of the transfer means, and a constant air pressure (pneumatic pressure) is applied to the cylinder. ) Supply. When the weight of the work is not constant, the load of the work is detected and the air pressure equivalent to the detected load is supplied to the cylinder.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In one embodiment of the present invention, a pneumatic cylinder is used to connect its output shaft, that is, a rod, to a Z drive unit. A force equivalent to the weight of the work and the Z drive unit is obtained by adjusting the pressure of the air supplied to the cylinder. As a result, the weight of the Z drive unit balances with the force from the cylinder, resulting in a weightless state.

The load on the Z-axis is detected by detecting the input supplied to the power source of the Z-axis, for example, the motor, and the air pressure to the cylinder is applied so that a force equivalent to this load is applied to the cylinder. By equipping with a regulator that automatically adjusts, a weightless state is achieved by balancing with a changing load.

[0009]

As described above, the Z axis can be prevented from falling by applying a force equivalent to the own weight of the work and the structure for handling the work from the outside. Further, by applying an equivalent force to the Z axis, the power source for driving the Z axis, for example, the load of the motor can be brought into a state close to no load and the power source can be reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows a Z-axis of a carrier device for constant load according to an embodiment of the present invention. In the figure, 1 is a work such as a wafer or plate, 2 is a ball screw, 2a is a screw of the ball screw 2, 2b is a nut of the ball screw 2, 3 is a cylinder, 3a is a cylinder portion of the cylinder 3, 3
b is a rod portion of the cylinder 3, 4 is a timing pulley, 5
Is a timing belt, 6 is a motor, 7 is a vertical axis drive unit,
8 is a regulator, 9 is a primary pressure, 10 is a secondary pressure, 1
Reference numeral 1 is a relief port, and 12 is a Z-axis guide.

The normal Z-axis moves at high speed, high precision positioning,
The ball screw 2 and the Z-axis guide 12 are often used together in order to efficiently transmit the output of the motor. Also, Z
The motor 6 and the ball screw 2 are connected to the timing pulley 4 and the timing belt 5 in order to reduce the space required for the shaft.
In most cases, they are connected with each other. However, because the ball screw 2 has good transmission efficiency, when the output of the motor is stopped, the weight of the drive unit 7 is transmitted to the nut 2b of the ball screw, the screw 2a of the ball screw is rotated, and the drive unit 7 tries to fall. . To prevent this, the motor 6 is usually of a type having a built-in brake.

In the present embodiment, the output shaft 3b of the cylinder 3 is connected to the Z-axis drive unit 7 and the supply air pressure 10 is adjusted by the regulator 8 to generate a force balanced with the weight of the drive unit 7. As a result, the drive unit 7 is in principle in a weightless state, so that a type in which the output of the motor 6 is extremely small can be adopted.

A regulator 8 is provided to adjust the pressure to the cylinder 3a. When the drive unit 7 descends, the secondary pressure 10 of the regulator 8 is reduced because the air in the cylinder 3a descends while being compressed. The set pressure is exceeded.

Therefore, as the regulator 8, a type with a relief port 11 is adopted, and when the secondary pressure 10 exceeds the set pressure, air is promptly discharged from the relief port 11 and the pressure inside the cylinder 3a becomes the set pressure. It is possible to maintain.

As described above, according to this embodiment, Z
Since a force equivalent to the weight of the shaft driving unit is supplied from the cylinder, it is possible to use an extremely small motor.
Further, when the transmission parts such as the timing belt and the ball screw are broken, or even when the motor shaft is broken, the work does not drop and is stopped on the spot, so that the work is not damaged.

(Second Embodiment) FIG. 2 is a schematic view showing the Z-axis of a transfer device for a variable load according to another embodiment of the present invention. In the figure, 21 is a workpiece such as a wafer cassette or a plate cassette, 22 is a motor driver, 23 is a servo valve driver, and 24 is a servo valve.

Each Z axis of a semiconductor or liquid crystal panel manufacturing apparatus is
Since the work is a wafer, a glass plate, a mask, etc., and the weight loaded by each Z axis is substantially constant, the supply pressure to the cylinder 3a is regulated by the regulator 8 as shown in the first embodiment. If it is set in advance, the subsequent adjustment is unnecessary.

However, the weight of the work may be uncertain within a certain range. For example, a cassette for storing wafers and glass plates usually stores a plurality of sheets.
In the case of a sheet or an empty cassette, the weight naturally differs. If the air pressure is adjusted to the weight when all the sheets are stored, the weight of the drive unit and the cylinder output will not be balanced when the empty cassette is transported.

Therefore, in the present embodiment, the servo valve 2 capable of detecting the electric power supplied to the motor 6 by the motor driver 22 and automatically controlling the set pressure from the outside.
4 is controlled by the servo valve driver 23 so that a force equivalent to the load is always obtained even if the load changes.

According to the present embodiment, even for a load that fluctuates within a certain range, it has a means for detecting this and a means for adjusting the pressure. Therefore, the same effect as that of the first embodiment is obtained. Can be achieved.

[0021]

According to the present invention, since a force equivalent to the weight of the work and the driving portion is supplied by the fluid pressure, it is possible to employ an extremely small driving means such as a motor. Further, even if the driving force is lost due to the damage or failure of the driving means, the work and the driving unit do not drop and stop on the spot, so that the work is not damaged.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a Z-axis of a constant load carrying device according to a first embodiment of the present invention.

FIG. 2 is a schematic view showing the Z-axis of a transport device with varying loads according to a second embodiment of the present invention.

[Explanation of symbols]

1: Workpiece, 2: Ball screw, 2a: Ball screw, 2b: Ball screw nut, 3: Cylinder, 3
a: cylinder part of cylinder, 3b: rod part of cylinder, 4: timing pulley, 5: timing belt,
6: motor, 7: vertical axis drive unit, 8: regulator,
9: 1 primary pressure, 10: secondary pressure, 11: relief port, 12: Z-axis guide, 21: wafer, plate cassette, 22: motor driver, 23: servo valve driver, 24: servo. valve.

Claims (3)

[Claims] 1. Attached to a means for conveying a work,
Fall prevention which prevents drop of the drive unit of the work and the transfer unit when a force for driving the drive unit is lost by generating a fluid pressure balanced with the own weight of the drive unit of the work and the transfer unit mechanism. 2. The weight of the workpiece is constant, and the means for generating the fluid pressure supplies a cylinder means having a piston and a cylinder attached to the drive part and the fixed part of the transfer means, and supplies this constant air pressure. The fall prevention mechanism according to claim 1, characterized by comprising means. 3. The weight of the work is not constant, and the means for generating the fluid pressure is a cylinder means in which a piston and a cylinder are attached to a driving portion and a fixed portion of the conveying means, and a means for detecting a load on the work. And a means for supplying an air pressure equivalent to the detected load to the cylinder means.