JPH06159325A - Straightly progressing type flexible actuator - Google Patents

Abstract

PURPOSE:To provide a straightly progressing type flexible actuator suitable for a semiconductor manufacturing facility, wherein the position is not deviated by creep deformation of a tube, and the possibility of the tube damaging accident is eliminated. CONSTITUTION:In a straightly progressing type flexible actuator, one end of a tube actuator 5 formed by winding a ring-like reinforced fiber around a flexible tube is fixed to a fixing holder 6, and the other end is fixed to a tube cap 7. The fixing holder 6 and the tube cap 7 are axially slid to each other, and there is a part provided with a non-circular cross section on a sliding part 8. Touching parts 9, 10, 11, 12 are provided on the fixing holder 6 and the tube cap 7 to regulate the upper and lower limits of the sliding range. Thereby, the position is not deviated owing to creep deformation, the possibility of the tube damaging accident can be eliminated, the straight progressing is certain, moreover no impact may be applied to any object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator capable of flexible movement, and more particularly to a rectilinear flexible actuator capable of rectilinear movement and having improved positional accuracy at an output end.

[0002]

2. Description of the Related Art In a semiconductor manufacturing process, when a mechanical shock is applied to a wafer, an internal defect may occur and the electrical characteristics thereof may be affected. Further, the particles inevitably generated by such a mechanical impact may be larger than the fine circuit element to be formed on the wafer, which hinders necessary fine circuit processing. For these reasons, mechanical shock should be eliminated as much as possible in semiconductor manufacturing. However, conventionally, a mechanical movement element in an actuator such as a motor or a piston mechanism is generally made to have a rigid structure, and due to such rigidity, it is possible to have a micron-order movement and positioning accuracy. If such a rigid motion element hits another member or the like while performing a predetermined motion, a mechanical shock will be generated. Hereinafter, this is called a hard movement. Therefore, when such a hard movement is used for wafer transfer in the semiconductor manufacturing process, it is necessary to suppress the occurrence of mechanical shock by performing extremely close position control and speed control.

On the other hand, as seen in the current robot drive, the actuator used under the general control by the microprocessor utilizing the developed visual and tactile sensors does not necessarily have a rigid structure and has a high processing accuracy. Not only those having Rather, it is expected that the use of a flexible actuator capable of flexible movement under such integrated control will lead to the development of artificial fingers that can replace human fingers. Therefore, it is considered that such an actuator having a flexible movement can realize an impact-free transfer mechanism applicable to a semiconductor manufacturing process under much simpler control than an actuator having a hard movement.

Therefore, some proposals have been made as flexible actuators to be applied to such applications, most of them are combinations of members having different flexibility, or a combination of a flexible tube and a non-stretchable reinforcing fiber. Thus, various deformations such as bending and twisting are realized. For example, the inside of a rubber tube is divided into three chambers in the circumferential direction to form an assembly of three pressure chambers that are long in the axial direction, and by applying different pressures to the respective pressure chambers, bending, axial extension, and axial rotation can be achieved. It is known that various flexible deformations such as twisting are possible. (Suzumori, The Japan Society of Mechanical Engineers, Volume C (Head 1-10), 2547-2552)

Alternatively, there is one in which a reinforcing fiber (circumferential reinforcing fiber) is densely wound around a rubber tube and another reinforcing fiber (axial reinforcing fiber) is joined along the axial direction. When the circumferential reinforcing fiber is pressed into the rubber tube, the circumferential reinforcing fiber has an action of preventing the diameter of the rubber winding from expanding and expanding the rubber winding only in the axial direction. And since expansion in the axial direction is also prevented at the location where the axial reinforcing fibers are joined, when this actuator is pressurized,
The part where there is no axial reinforcing fiber expands, and the axial reinforcing fiber side is curved inward as a whole. (Tanaka, Mechanical Design 36, 8 (1992-7), 32-39) When these flexible actuators are applied to a wafer transfer device of a semiconductor manufacturing apparatus, there is no fear of internal defects or particles due to mechanical shock. It is expected that an excellent wafer transfer mechanism will be realized.

Among the actuators of this type, one in which the output end shows a linear motion is a cylindrical tube 14 and a tube in which a number of ring-shaped reinforcing fibers 15 are densely wound around the tube 14, as shown in FIG. Actuator 5 is conceivable. When the tube actuator 5 is pressurized, it tries to deform so that the internal volume increases, but since the ring-shaped reinforcing fiber 15 restricts the expansion of the tube 14 in the radial direction, It can only extend in the axial direction. Therefore, the tube actuator 5
When one end is fixed and the other end is used as the output end, the output end moves in a straight line along the tube axial direction to be expanded by being pressurized.

[0007]

However, in a flexible actuator using this type of rubber tube, when it is continuously used, the elastic deformation of the rubber is repeated, so that the time during which the rubber is in the stretched state is increased. Due to the accumulation, creep deformation inevitably occurs in the rubber. When this occurs, the position of the actuator output end shifts from that before the occurrence, so that the required position accuracy cannot be obtained. Further, in the above-mentioned tube actuator 5, there is nothing that restricts the rotational movement around the axis at the output end, and therefore, due to factors such as uneven material of the tube 14 and uneven bonding density of the reinforcing fibers 15, etc. Depending on the load applied, a rotation component around the axis may be included in the movement of the output end. If there is such an unintended rotation component, the tube actuator 5 will apply a stress to the object, which may affect the characteristics and the fine structure of the object.

On the contrary, a rotational component may be added to the tube actuator 5 due to the load from the object, and if it is extreme, a breakage accident of the tube 14 may occur. Needless to say, if such an accident occurs, it is dangerous and may cause generation of particles which are not preferable in semiconductor manufacturing. Further, although the tube actuator 5 is of a straight type, the output end is not supported at all,
Curvature is inevitable depending on the weight of the object. In particular, when the object is extended under pressure, the bending moment due to the weight of the object becomes large, so that the object is easily bent. Therefore, unless the object is very light, it does not actually go straight. Further, if over-pressurized, the tube 14 may be damaged and suddenly scattered. Similar to the rotation component of the tube 14, such an accident is dangerous and causes particles.

The present invention has been made in order to solve the above-mentioned problems, and the position accuracy does not decrease due to the creep of the tube even if it is repeatedly used, and the rotation is ensured regardless of the weight of the object. An object of the present invention is to provide a variable shape actuator suitable for the semiconductor manufacturing field, which moves linearly without any component, and eliminates the risk of tube breakage accidents due to rotational components and overpressurization.

[0010]

To achieve the above object, a rectilinear flexible actuator of the present invention is a flexible actuator having a flexible tube and a ring-shaped reinforcing fiber wound around the tube. An actuator, comprising a fixed holder that fixes and holds one end of the tube, and a tube cap that is held at the other end of the tube, wherein the fixed holder and the tube cap are axially mutually reciprocated. A sliding portion that slides, and a first abutting portion and a second abutting portion that come into contact with each other to regulate the axial sliding range are formed.
Further, the straight-moving type flexible actuator of the present invention is configured as described above, wherein the shortest length of the tube within the sliding range regulated by the contact portion is longer than the free length of the tube. Further, the straight-moving type flexible actuator of the present invention has the above-mentioned structure, wherein a part of the sliding portion has a non-circular cross-sectional shape.

[0011]

In the straight type flexible actuator of the present invention having the above structure, when air pressure is applied to the inside of the tube, the tube tries to expand, but the reinforcing fiber wound around the tube moves in the circumferential direction of the tube. As it restricts expansion, the tube only extends axially. Releasing the applied air pressure causes the tube to contract axially.

At this time, since both ends of the tube are held by the fixed holder and the tube cap which slide with each other, the tube does not bend due to the weight of the object, and the straightness is guaranteed. Also, since the fixed holder and the tube cap have contact points and the sliding range is regulated, the minimum length of the tube determined by the lower limit of the sliding range must be longer than the free length of the tube. This will eliminate the effects of the initial creep of the tube. Further, the upper limit of the sliding range can prevent the tube from being damaged due to overpressurization. Furthermore, since the cross-sectional shape of the sliding part between the fixed holder and the tube cap is non-circular, the motion of the tube cap due to the expansion and contraction of the tube does not add a rotational component around the axis, resulting in unnecessary stress on the object. The tube will not be damaged and accidental damage to the tube will be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the rectilinear flexible actuator of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the overall structure of a rectilinear flexible actuator 1 of this embodiment. First, the overall structure of the rectilinear flexible actuator 1 will be described, then the tube actuator 5, which is one of the components thereof, will be described, and then the overall operation of the rectilinear flexible actuator 1 will be described. Main parts of the actuator 1 as the present invention will be described.

The overall structure of the straight-moving type flexible actuator 1 shown in FIG. 1 is such that one end of a tube actuator 5 is airtightly fixed to a fixed holder 6 and the other end is airtightly fixed to a tube cap 7. Here, the fixed holder 6
The tube cap 7 and the tube cap 7 can slide in the sliding portion 8 in the axial direction (left and right direction in the drawing). Furthermore, the fixed holder 6 is formed with abutting portions 9 and 10 that come into contact with the tube cap 7, and the tube cap 7 has
Contact portions 11 and 12 that contact the fixed holder 6 are formed.

Next, the tube actuator 5, which is one of the constituent elements of the straight-moving type flexible actuator 1 having the above-mentioned overall structure, will be described with reference to FIG. The tube actuator 5 is formed by tightly winding a ring-shaped reinforcing fiber 15 that does not expand and contract around a flexible tube 14. When the tube actuator 5 is pressurized, the whole of the tube actuator 5 tries to expand, but since the expansion in the radial direction is restricted by the reinforcing fiber 15, it expands only in the axial direction. When the pressure is released, it returns to the original even if it contracts in the axial direction. Here, the material of the tube 14 may be any material such as rubber such as NBR rubber or plastic having appropriate flexibility and elasticity, and the reinforcing fiber 15 may be any material.
Longitudinal elastic modulus (Young's modulus) of carbon fiber, thin metal wire, silk thread, etc.
Any material may be used as long as it is sufficiently larger than the tube material and hard to yield. And these are usually joined by some kind of adhesive, but as the adhesive, the same quality as the tube 14 and the reinforcing fiber 15 are used.
It is good to choose one that is familiar with.

Next, the overall operation of the rectilinear flexible actuator 1 having the above structure will be described. First, Fig. 1
(A) shows a state where the contact portion 9 of the fixed holder 6 and the contact portion 11 of the tube cap 7 are in contact with each other, that is, a contracted state. When the pressure chamber 13 is pressurized, the space inside the tube 17 is also pressurized through the hole 16, so that the tube actuator 5 extends in the axial direction as described above, and the abutting portion 10 of the fixed holder 6 and the tube cap 7 are extended. The abutting portion 12 comes into contact with each other, and the stretched state shown in FIG. At this time,
Since the hole 18 is also formed in the contact portion 12 of the tube cap 7, the space 19 between the contact portion 12 and the contact portion 10 is formed.
The pressure change in is moderated. If the pressure in the pressure chamber 13 is moderately adjusted, it can be brought to an intermediate state. Pressure chamber 13
When the pressure is released, the state returns to the contracted state shown in FIG.

As a result, the rectilinear flexible actuator 1
The tube cap 7, which is the output end of, moves linearly in the left-right direction in the drawing due to the pressure applied to the pressure chamber 13, and the movable range is between the contact portion 9 of the fixed holder 6 and the tube cap 7. The lower limit of the contact portion 11 is the contact portion 10 of the fixed holder 6 and the contact portion 12 of the tube cap 7.
The upper limit is fixed by. Further, since the movement of the tube cap 7 here is due to the air pressure and the flexible expansion and contraction of the tube, it is a so-called flexible movement that does not give a shock to the object.

Above, the description of the whole of the rectilinear flexible actuator 1 is completed, and the description will be directed to the characteristic part of the present invention. First, the first characteristic part is shown in FIG.
The length of the tube actuator 5 in the contracted state shown in (a) (indicated by L _S in the drawing) is the free length of the tube actuator 5 (the length in a state where it is not assembled to the fixed holder 6 or the like, hereinafter L _f It is longer than that). Therefore, the tube actuator 5 is mechanically stretched in advance by the length of L _S -L _f (hereinafter referred to as pre-stretching) and assembled to the straight-moving flexible actuator 1. This is for preventing the positional displacement of the tube cap 7 due to creep deformation which is inevitable because the tube actuator 5 is made of the tube 14 made of rubber or the like.

Here, the creep deformation of the rubber material will be described. Generally, a polymer material creeps with time under a constant stress, and a stress relaxation phenomenon occurs when a constant displacement is applied and maintained. That is, in the case of the tube actuator 5, if the tube 14 is maintained in the stretched state, the free length of the tube 14 increases due to creep.

An example of this creep deformation behavior is shown in FIG. FIG. 6 is a graph showing the relationship between the application time t (logarithmic display) and the creep rate Δε when a constant stress of 12.6 kgf / cm ² is applied to NBR rubber. Here, the creep rate is an extension rate expressed on the basis of an extension rate by applying stress for 30 minutes, and is expressed by the following equation. Δε = ε−ε ₃₀ Here, ε is the elongation rate (%) at time t, and ε ₃₀ is 3
The elongation rate (%) after 0 minutes is shown. From FIG. 6, it can be seen that the creep increases almost linearly with the logarithm of time at the initial stage of stress application, but thereafter the slope becomes steep and the creep becomes rapid. It is considered that the higher the test temperature is, the more severe the stress is, and the rapid creep due to the deterioration of the rubber occurs when the stress is applied for a long time. Rubbers other than NBR rubber show the same tendency.

Focusing on the curve at the temperature of 50 ° C. in FIG. 6, the creep rate reaches about 10% at the application time of 1000 hours. Therefore, even if ε ₃₀ at 50 ° C is negligibly small, the elongation rate ε at 1000 hours is about 10%, and the initial free length of the tube 14 is 50 m.
If m, a deviation of 5 mm will occur. This deviation is large when the tube actuator 5 is used in, for example, a wafer transfer mechanism of a semiconductor manufacturing facility. Moreover, since the time on the horizontal axis of the graph in FIG. 6 is on a logarithmic scale, if this is expressed on an antilogarithmic scale, it is considered that most of the change in elongation rate is concentrated in the relatively early period of the application time. From the above,
In the conventional linear actuator used without giving the tube actuator 5 a preliminary extension, the tube 14 must be used in consideration of the creep deformation of the tube 14 immediately after the start of use.

Therefore, in the straight-moving type flexible actuator 1 of this embodiment, the tube actuator 5 is preliminarily extended and used to solve this difficulty. That is, when the tube actuator 5 is preliminarily stretched by 10% and incorporated into the straight-moving type flexible actuator 1,
If the contribution to the creep deformation due to the pre-expansion is neglected, the deviation due to the creep deformation is absorbed by the pre-expansion and does not pose a problem until 1000 hours when the elongation rate reaches 10%. Actually, the pre-stretching also contributes to the creep deformation to some extent, and it is considered that the influence of the creep deformation appears a little earlier than 1000 hours. If the extension rate due to creep deformation exceeds the amount of pre-elongation, the tube cap 7 will be displaced, so the tube actuator 5
Will be replaced with a new one.

The positional deviation due to the creep deformation is a problem even during pressurization, but this point is also taken into consideration in the linear flexible actuator 1 of this embodiment. That is, the contact portion 10 and the contact portion 12 which is a second feature portion of the present invention, since the established maximum length of the tube actuator 5 (in FIG. 1 L _l), creep deformation has occurred Even if pressure is applied later, the length of the tube actuator 5 does not exceed L ₁ . Due to these facts, the rectilinear flexible actuator 1 has excellent positional accuracy both when not pressurized and when pressurized. Further, due to the determination of the maximum length described above, in the straight advance type flexible actuator 1, the tube 14 does not burst even if over-pressurization occurs due to an erroneous operation or the like. Needless to say, if such a rupture accident occurs, it is dangerous, and further, it may lead to the generation of particles which are not preferable in semiconductor manufacturing. Therefore, it is significant to eliminate them.

Next, the function of preventing the rotation component of the tube cap 7, which is the third characteristic part of the present invention in the straight type flexible actuator 1, will be described. FIG. 7 shows a cross-sectional view of the straight advance type flexible actuator 1 taken along the line X-Y in FIG. The sliding portion 8 between the fixed holder 6 and the tube cap 7 shown in FIG. 7 has a rectangular shape, and the tube cap 7 cannot rotate about the axis with respect to the fixed holder 6.

As a result, even if the material of the tube 14 is uneven, no rotational component is added to the movement of the tube cap 7. Also, depending on the load of the object,
No rotational component is added to the movement of the tube cap 7. Therefore, unnecessary stress is applied to the object,
The tube 14 is not damaged by twisting. Here, the cross-sectional shape of the sliding portion 8 shown in FIG. 7 is not limited to a quadrangular shape, but may be another polygonal shape such as a triangular shape, or an elliptical shape such that the fixed holder 6 and the tube cap 7 do not rotate about the axis. Anything is fine.

The straight-moving type flexible actuator 1 having the above-mentioned characteristic portions further has the following characteristics. First, in the straight-moving type flexible actuator 1, since both ends of the tube actuator 5 are securely supported by the fixed holder 6 and the tube cap 7, the straight-moving motion is surely performed without being curved due to the weight of the object. You can

Since the tube actuator 5 is preliminarily stretched by the fixed holder 6 and the tube cap 7, the starting pressure at which the rectilinear flexible actuator 1 starts its operation is changed by changing the amount of the preliminary tension. Can be set. As shown in FIG. 8, if the fixed holder 6 is divided into a base portion 24 and a distal end portion 23 and is screwed, the position of the distal end portion 23 with respect to the base portion 24 is adjusted by a screw, so that the tube actuator 5 is fixed. The amount of pre-stretch can be changed without changing the free length. Alternatively, if the free length of the tube actuator 5 is changed, the fixed holder 6 and the tube cap 7 can be left as they are, and the amount of preliminary extension can be changed. However, it is necessary to manage the starting pressure with the creep deformation of the tube 14.

Further, as shown in FIG. 9, if the tube cap 7 is divided into a stopper portion 21 and a shaft portion 22 and screwed, the position of the stopper portion 21 with respect to the shaft portion 22 is adjusted by a screw. By doing so, it is possible to adjust the stroke amount as the straight-movable type flexible actuator 1. As is clear from the above description, the rectilinear type flexible actuator 1 of the present embodiment is
Since both ends of the tube actuator 5 are supported by the fixed holder 6 and the tube cap 7, the tube actuator 5 has various characteristics which the conventional linear actuator does not have.

Next, a wafer holder 25 to which the rectilinear flexible actuator 1 of this embodiment is applied will be described with reference to FIG. The wafer holder 25 has a center portion 27.
3 sets of straight-moving type flexible actuators 1 are arranged in a star shape via. In the wafer holder 25, pressure can be simultaneously supplied or released from the common pressure supply port 28 to the three sets of rectilinear flexible actuators 1.

In the wafer holder 25, a wafer chuck 29 is attached to the tube cap 7 of each rectilinear type flexible actuator 1 (see the side view of FIG. 11).
Therefore, the wafer 26 can be held or released by driving each of the rectilinear flexible actuators 1 from the common pressure supply port 28. That is, each tube cap 7 and the wafer chuck 29 are in the positions indicated by the solid lines when not pressurized,
The wafer 26 is held. When pressure is applied from the common pressure supply port 28, the tube cap 7a and the wafer chuck 29a shown by the broken line are brought into the state, and the wafer 26 is opened. In the wafer holder 25, since each of the rectilinear flexible actuators 1 has the feature of the present invention, the wafer 26 is not subjected to impact or unnecessary stress, and there is no risk of tube breakage accident.
In addition, the position accuracy of each rectilinear flexible actuator 1 is good.

Next, a modified example of the above-described rectilinear flexible actuator 1 will be described. The straight-moving type flexible actuator 2 shown in FIG. 2 is obtained by deforming the fixed holder 6 and the tube cap 7 in the straight-moving type flexible actuator 1.
The fixed holder 36 and the tube cap 37 are used. 2A shows a contracted state and FIG. 2B shows an extended state. The rectilinear flexible actuator 3 shown in FIG.
The tube actuator 5 is arranged inside. FIG. 3A shows a contracted state and FIG. 3B shows an extended state. The straight-moving type flexible actuator 4 shown in FIG. 4 is obtained by deforming the fixed holder 46 and the tube cap 47 in the straight-moving type flexible actuator 3 to form a fixed holder 56 and a tube cap 57. Figure 4
The contracted state is shown in (a) and the extended state is shown in FIG. 4 (b).

Of course, each of the rectilinear flexible actuators 2 to 4 has the same characteristics as the rectilinear flexible actuator 1. The embodiments described here do not limit the present invention at all, and needless to say, various modifications and improvements can be made without departing from the scope of the invention.

[0033]

As is apparent from the above description, in the straight-moving type flexible actuator of the present invention, the straight-moving telescopic tube actuator is held by the fixed holder and the tube cap that slide with each other without rotating component, and the sliding Since the upper and lower limits are mechanically limited, the positional accuracy as an actuator is good, and the output position does not change due to the effect of creep deformation of the tube. In addition, since the bending of the object due to load etc. and the over-expansion due to over-pressurization do not occur, there is no danger of tube damage accidents, and there is also no impact or unnecessary stress on the object. Absent. Therefore, it is possible to provide a rectilinear flexible actuator suitable for the semiconductor manufacturing field.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a rectilinear flexible actuator that is an embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a rectilinear flexible actuator that is an embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a rectilinear flexible actuator that is an embodiment of the present invention.

FIG. 4 is a diagram showing the configuration of a rectilinear flexible actuator that is an embodiment of the present invention.

5 is a diagram showing a configuration of a tube actuator which is a constituent element of the rectilinear flexible actuator shown in FIG.

FIG. 6 is a graph showing creep characteristics of NBR rubber.

FIG. 7 is an X-Y of the rectilinear type flexible actuator shown in FIG.
FIG.

FIG. 8 is a view showing a modified example of a fixed holder which is a constituent element of the rectilinear flexible actuator shown in FIG.

9 is a view showing a modified example of a tube cap which is a constituent element of the rectilinear flexible actuator shown in FIG.

FIG. 10 is a plan view of a wafer holder to which the rectilinear flexible actuator chute shown in FIG. 1 is applied.

11 is a side view of the wafer holder shown in FIG.

[Explanation of symbols]

 1, 2, 3, 4 Straight advance type flexible actuator 5 Tube actuator 6 Fixed holder 7 Tube cap 8 Sliding part 9, 10, 11, 12 Contact part 14 Tube 15 Reinforcing fiber

Claims (3)

[Claims] 1. A flexible actuator having a flexible tube and a ring-shaped reinforcing fiber wound around the tube, comprising: a fixed holder for fixing and holding one end of the tube; A tube cap held at the other end, wherein the fixed holder and the tube cap respectively have sliding portions that slide in the axial direction, and abutment against each other to regulate the axial sliding range. A linearly advancing type flexible actuator having a first contact portion and a second contact portion. 2. The rectilinear flexible actuator according to claim 1, wherein the shortest length of the tube within a sliding range regulated by the abutting portion is longer than the free length of the tube. 3. The rectilinear flexible actuator according to claim 1, wherein a cross-sectional shape of a part of the sliding portion is non-circular.