JP2000021949A - Structure for noncontact floating transfer of work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transfer a tabular work of simple structure in the right direction in positively clean condition, without providing a transfer guide or a special external force imparting mechanism. SOLUTION: A floating transfer plate is constructed so as to float a work W, such as a LCD glass substrate with blow air to transfer the work W and comprises a box 1, a sloped nozzle 2, and guide portion 3. A spacing c between both ends of the work W and the guide portions 3 is set at, for example, about the same as the amount of floating over a transfer surface 12a of the work. When the leaning of the work W changes the distance to the right and left guides, the pressure under the work changes to tilt the work W. This allows a force which centers the work W to be generated, which prevents the work W from coming into contact with the guide portions, thus transferring the work W in clean conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for floating and transporting a flat work by floating a flat work with gas to be blown out, and more particularly to a technique for maintaining a path of a transferred work.

[0002]

2. Description of the Related Art Various apparatuses have been conventionally known as apparatuses for blowing and blowing air from a transfer surface to float and transfer a flat work such as a wafer or a liquid crystal substrate. With such an apparatus, it is difficult to transport the work in the direction of the intended course without meandering. For this reason, in a conventional ordinary floating conveyance device, a mechanical guide such as a roller is provided to guide a work.
However, in this case, the workpiece cannot be transported in a completely clean state without contact.

On the other hand, there is also known an apparatus for moving a work straight without using a mechanical guide such as a roller in the floating conveyance of the work. For example, a porous ceramic plate is placed on an air chamber, air is uniformly blown out from the porosity of the ceramic through a large number of perforations, and a workpiece made of a thin plate-shaped powder compact is floated and supported without agitation, There has been proposed an apparatus capable of aligned conveyance (see Japanese Utility Model Laid-Open No. 3-82222 and the drawings). However, with this device, even if the work can be uniformly supported and hardly shaken in the traveling direction, there is no aligning action, so when the work transfer direction is biased for some reason, this cannot be corrected. Can not.

In addition, two rows of air outlets are provided on the transfer surface, and air is blown outward and obliquely upward from these, thereby floating a work such as a wafer-like semiconductor substrate and moving the work in the horizontal direction. An apparatus has been proposed in which a work is floated and conveyed while performing a centering action by a force and a negative pressure generated between the centers of two rows (Japanese Patent Laid-Open No. Hei 2 (1994)).
-89721). However, since the negative pressure only gives a force to attract the work to the transfer surface, there is not much alignment effect when the balance of the lateral force on both sides is lost, and with this device, if the work moves straightly, Not necessarily.

Further, an electrode is arranged on the transfer surface, air is blown out from a number of holes opened in the electrode, and while the wafer is being floated by the air, a current is applied to the electrode to automatically align the wafer by electric force. (See Japanese Patent Laid-Open No. 2-70617). However, in such a device, it is expected that the structure and operation become complicated due to the addition of an extra external force applying body, and that the meandering width at the time of conveyance becomes large because the aligning force is weak relative to the vertical force. Is done.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art, and enables a flat plate-like work to be reliably formed with a simple structure without providing a contact type guide or a special external force applying mechanism. It is an object of the present invention to provide a structure for floating and transporting a workpiece that can be transported in a clean state.

[0007]

In order to solve the above-mentioned problems, the present invention solves the above problem by blowing a gas from a plurality of holes formed in a transfer surface into a flat work having both sides parallel to the transfer direction. In a structure for floating and transporting a workpiece, which is lifted and transported while passing through a surface, the workpiece is disposed so as to have a predetermined interval between the two side surfaces and an interval for providing a passage resistance to a gas passing through the two side surfaces. It is characterized in that it has a guide member to be operated.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a sectional shape of a floating transport plate to which the present invention is applied. The floating transport plate, which is a workpiece floating transport structure, is configured to levitate and transport a workpiece W such as an LCD glass substrate, which is a flat workpiece, with air that is blown out,
The apparatus includes a box-shaped body 1, an inclined nozzle 2 as a nozzle section for transporting a work, and a guide section 3 as a guide member.

In the present embodiment, the box-shaped body 1 has a thin sheet metal structure, and has an upper surface serving as a transport surface 12a formed with a plurality of holes 11 through which air is blown out. A plate 12 is provided. The box-shaped body 1 has a keel-shaped rib 13 which is a reinforcing plate for reinforcing the upper plate 12 so that the inner plate is subjected to a weak internal pressure when air is introduced and deformation of the upper plate 12 is limited at that time. The inside of the box 1 is an air chamber 1a. The reinforcing plate is preferably a rib-shaped plate as shown in the figure in order to reduce the weight as much as possible and allow air to flow therethrough, as compared with a plate stretched over the entire surface so as to partition the box-shaped body 1.

The inclined nozzle 2 is shaped so as to be inclined by an angle θ in the Y direction, which is the transfer direction, so that the work W can be transferred. In this example, an air supply communication pipe 2 for supplying air of a different system from the air for floating to the inclined nozzle 2
1 is connected and generates a vertical work supporting component fv and a Y-direction workpiece transporting component fy by a force f ₀ due to the dynamic pressure of the air blown out from it. In addition, this nozzle may be a movable nozzle that can change the direction between when the workpiece floats and conveys and when the workpiece only floats. Further, such a floating conveyance nozzle may be provided not only at the center position in the X direction but also at other positions. Further, all the nozzles can be variable nozzles capable of floating conveyance.

The guide portion 3 has a predetermined distance c between both ends Wa and Wb in the X direction which is the width direction of the work W and parallel to the Y direction on the conveying surface 12a of the upper plate 12. It is arranged to have. The distance c is set so as to provide a passage resistance to the air passing through both side surfaces, that is, to increase a floating force for floating the work from the transfer surface 12a by the air resistance. Will be about the same. Accordingly, the work can be guided in a non-contact state when the work is levitated and conveyed from the conveying surface as described later. Such a guide part 3
May be configured so that the position can be adjusted in the X direction by an appropriate mechanism using a linear guide, an adjusting screw, or the like so as to adjust the floating force and the centering force and to cope with a work having several widths. In FIG. 1, the above h and c are shown large, but the actual dimensions when the glass substrate or the like is floated and conveyed are usually several mm or less.

The ribs 13 are arranged at appropriate pitches in the transport direction so as to maintain the flatness of the transport surface 12a as shown in the plane state of the floating transport plate portion in FIG.
Are provided. The box-shaped body 1 and the upper plate 12 have sufficient strength by being reinforced by the ribs 13 as described above. Therefore, for example, even when a large glass substrate of about 1 m square is levitated and conveyed, its thickness is 0.8 to
A thin stainless steel plate of about 1.2 mm can be used. As a result, the floating transport plate can be manufactured lightly and inexpensively.

The ribs 13 are manufactured with high precision by laser processing or sheet metal processing. Therefore, in this example, the upper plate 1
Since 2 is a flat plate, it is cut linearly, and its end face has a sufficient straightness. By joining the upper plate 12 to this, the flatness can be obtained. That is, for a large workpiece, it is not easy to obtain the flatness of the plate by machining, but the flatness of sufficient accuracy can be easily obtained by sheet metal working using a rib plate. Also, since the work can be levitated by a slight air pressure as described later, even if a sheet metal structure is adopted, no special covering or sealing is required. Therefore, the manufacturing process is also simple.

FIG. 2 shows an example of the configuration of a work floating transport device using the floating transport plate of FIG. The work floating transfer device of this example is a device capable of heat-treating the work, and is provided with a temperature changing means for changing the temperature of the supplied gas, a purifying means for purifying the gas, and a circulating means for circulating at least a part of the gas. As a supply system, there is provided a floating blowing section 4 and a floating / transporting blowing section 5, and air is supplied from the gas supply system to the floating transport plate, so that the workpiece is raised and transported and heat-treated.

The floating air blower 4 is provided with a blower 41, an outside air inlet 42, an intermediate duct 43, an air blow opening 44, and a temperature changing means, which are provided in a machine room 7 which is partitioned and disposed in a casing 6. Heater 45, high-performance filter 46 as air purifying means, return duct portion 4 as circulating means
7 and an intake port 48. A certain amount of flow rate and wind pressure are required for the air for floating blowing supplied to the large number of air blowing holes 11. Therefore, the blower 41
For example, a turbo fan, a sirocco fan or the like having an appropriate type and size may be used.

The floating / conveying air blowing section 5 includes a compressed air introduction pipe 51a through which compressed air is sent from a compressed air source (not shown).
The suction filter 52, the electromagnetic valve 53, the air supply pipe 51b, the air supply communication pipe 21, the inclined nozzle 2, and the like shown in FIG. In this embodiment, an outside air heater 54 as the temperature changing unit and a clean filter 55 as the purifying unit are provided. When compressed air is used for the floating / transporting portion 5 in this manner, the amount of air and the pressure can be easily increased and decreased, and there is an advantage that the adjustment of the transport speed of the work is facilitated. However, the air source may be the same as that of the floating blower 4 so that the speed can be adjusted by a nozzle having a variable diameter and a variable inclination angle.

The above-described work floating device is used as follows. Blower 4 when lifting the work
Drive 1 At this time, if it is necessary to heat the work, the heater 45 is turned on. The air blown out from the blower 41 is distributed by the intermediate duct 43, passes through the high-performance filter 46, and enters the air chamber 1 a in the box-shaped body 1 of the floating transfer plate from the blow opening 44. The inside is partitioned by ribs 13 so that air flows in the traveling direction in a well-balanced manner. At this time, if a pressure difference occurs between the respective rib sections, air is conducted through the holes of the ribs 13 to equalize the pressure.

The blower 41 has an air volume of 0.3 to 0.5 Nm ³ / mi if the work is a glass substrate of about 1 m square.
n. And a static pressure of about 10 to 30 mmAq. This air blows out from under the work through the air supply hole 11 to generate a total pressure consisting of the dynamic pressure of the air blown out to the lower surface of the work and the static pressure of the air filled therein. To surface. For example, the pressure receiving area of the work is 1m
² , if the total pressure generated is 10 mmAq, a force of 10 kgf which is three times or more of its own weight acts on the work, so that the work can be lifted.

FIG. 3 shows the relationship between the gravitational force G acting on the work W and the levitation force F. As shown in (a), the work W is floated while passing air from both sides Wa and Wb.
When the conveying surface 12a and the distance between the workpiece W is small h _1, since the balloon air hardly flows out, the pressure P ₁ which occurs between them becomes high. As a result, the weight G of the work W
Increases work upward force F ₁ by the pressure P ₁ than the workpiece W is increased. Needless to say, the air can pass through the front and rear ends of the work W.

In this case, the distance c between both ends of the work W and the guide portion 3 is set so as to give a resistance to passage of air, thereby increasing the pressure below the work and increasing the floating force of the work. That is, the air that escapes from both ends in the X direction of the air blown under the work W is the guide portion 3.
In this case, the air flows upward from the space c while turning 90 °, so that by appropriately setting the space c, the air flowing out has a bend and resistance based on the orifice effect. As a result, the pressure P ₁ of the work under They become larger than is sufficiently wide spacing c, it has increased floating force of the work accordingly. If the distance c is sufficiently large, no resistance occurs due to the bending of the air or the orifice effect in this portion, and therefore the work floating force does not increase.

[0021] spacing beneath the workpiece W rises and increases from h ₁ to h, air is likely to flow out from the four sides of the bottom of the workpiece, as shown (b), the pressure is lower than P ₁ P
Becomes, the force by which the balance between its own weight G of the workpiece becomes F ₁ is smaller than F, the work W is stable in a state of being floated. Even in this state, the predetermined interval c is set, so that the pressure P and the levitation force F are increased, and the work is easily levitated.

In this case, since the upper plate 12 is made of a thin plate, the air blowing direction is blown at right angles to the conveying surface 12a without being affected by the sectional shape of the hole. Accordingly, there is no variation in the direction in which the air is blown out by the holes, and no horizontal component is generated in the dynamic pressure component of the blown air. As a result, the work W is levitated and supported in a well-balanced manner without receiving a conveying force in any direction. According to such a floating support, the work does not come into contact with the transport mechanism or the like, so that its cleanness is maintained.

[0023] The air that floats and supports the work in this manner is:
As shown in FIG. 2, the air flows on the conveying surface 12 a, is sent out from the periphery of the work to the return duct 47 at the upper portion thereof, passes through the upper space of the casing 6, and is sucked into the blower 41 again from the air inlet 48. When the work entrance / exit portion to the space on the transport surface 12a is open without being closed by a shutter or the like, a part of the air leaks to the outside. At that time, the insufficient air during circulation is supplied from the outside air inlet 42. Since at least most of the air is circulated and used in this device, the heater output is reduced and energy is saved. In addition, the cleanliness of the air is increased by repeatedly passing through the high-performance filter, and the work has a high level of cleanliness. Is achieved. Further, a large amount of air can be easily supplied by such air circulation.

In the apparatus shown in FIG. 2, while the workpieces are taken in and out one by one on the transfer surface 12a, two workpieces are floated and supported, and heated by the air for floating to be heat-treated.
When the heat treatment of the work on the front end side is completed, the solenoid valve 53 is opened, and the suction filter 5 is sequentially moved from the compressed air introduction pipe 51a.
2, solenoid valve 53, outside air heater 54, clean filter 5
5. Compressed air is blown from the inclined nozzle 2 through the air supply communication pipe 21 and the like, and a propulsive force is given to the work.

FIG. 4 shows a state in which the work is conveyed by applying a propulsive force to the work. (A) shows a planar state when the workpiece W is centered and transported. At this time, the distance between both ends of the work and the guide portion 3 is c, and the work W moves straight under the transport force T in this state.

(B) shows a state at the moment when the work W is slightly shifted to the right in the figure by δ _{1 for} some reason.
At this time, the left and right intervals are c + δ ₁ and c−
δ becomes _1, along with this resistance of the air is changed by substantially -δP and + [delta] P respectively flowing out of this part, each pressure of the work under almost P-[delta] P and P + [delta] P in the left and right
And lose balance. That is, as described above, since the interval c is set so as to increase the pressure below the work by the passage resistance and increase the floating force of the work, the change in the interval c immediately increases the pressure under the work as described above. Acts to change.

In this case, if the interval c changes, the speed of the air flowing out of this portion changes correspondingly.
Assuming that a certain amount of air passes, the δP corresponding to the passage resistance is proportional to the square of the velocity. Therefore, if the interval c changes, δP changes in inverse proportion to the square of the interval c.
That is, as the work approaches the guide portion, the air passage resistance rapidly increases. In this state, it is difficult for air to come out from the right side, and more air comes out from the left side.

(C) shows the state immediately after the state of (b). That is, when the pressure on the right side increases and the pressure on the left side decreases under the work, the work W is slightly inclined, and the distance between the work W and the transfer surface 12a at the left and right ends becomes h-δ ₂ and h + δ ₂ , respectively. Become. As a result, the levitation force F acting on the workpiece W at right angles is inclined, and the horizontal component force Fx
Occurs. Also, when the left side where the distance c is wide is lowered, the outflow resistance of the air in that part is increased, and the pressure that has been lowered rises toward the recovery, and the right side where the distance c is narrow is raised, so that the part of the part is raised. As the resistance to the outflow of air decreases, the pressure that has risen falls, and recovery begins. Then, the work W is centered by the horizontal component force Fx, the pressure under the work becomes the same pressure P as a whole, and the posture of the work becomes horizontal. in this case,
As the work approaches the guide portion, the horizontal component force Fx, which is the centering force, increases. Further, the air blown out from the narrowed guide portion 3 and the side surface Wb of the work W serves as an air cushion that suppresses the contact between the two. By such an operation, the work is conveyed at a substantially constant flying height without contacting the guide portion, while the bias and inclination are reliably corrected.

In the above description, when the guide portion 3 is not provided, or when the distance between both ends of the work and the guide portion is freely widened without being set, the above-described centering action does not occur. That is, when the guide portion 3 is not provided, there is no force to correct the work when the work is biased in the horizontal state. Further, when the distance between the work and the guide portion is large, the centering action does not occur until the distance becomes narrow, so that the work is moved laterally (SWAY) or swung (YAW).
Cannot be effectively regulated at an early stage. As a result, when the work approaches the guide portion, the inertial force due to the movement is large, and the correction force is relatively small, so that the movement of the work cannot be sufficiently regulated, and the work hits the guide portion.

By setting the distance c to an appropriate value that influences the levitation force of the work and increases it, as in the present embodiment, the work is conveyed while being constantly centered, and the contact between the work and the guide is maintained. Prevention and a clean transport state can be ensured. According to such a floating transfer plate, the work can be centered only by the action of air necessary for the floating transfer of the work.
It is not necessary to apply a special external force to the work by another means.
Therefore, it is possible to make the device simple in structure, reliable in operation and inexpensive.

According to the experiments performed by the inventors, the amount of air was 0.3
7 m ³ / min. Under the condition that the static pressure of the air chamber 1a is 20 mmAq and a glass substrate having a width of 800 to 1000 mm is used, the guide portion 3 is brought into contact with and separated from the work on both sides on the transfer surface 12a. Sometimes, the work floated, and h at that time was also about 0.5 mm.
At this time, when the work was moved in the transport direction, the work advanced without contacting the guide portions on both sides.

Note that h increases when the amount of blown air increases, but if economical operation is performed with the amount of air reduced as much as possible, when the work is a large glass substrate, c and h are almost zero. It can be set to about 0.5 mm. However, when it is necessary to increase the amount of air for another purpose, or when it is necessary to increase the flying height in order to position the work or to improve the plane accuracy of the transfer surface, it is possible to do so. Needless to say.

When the first work is heat-treated and sent to another external floating transfer system, the second work which has been similarly lifted and transported is stopped by an unillustrated stopper or the like, and a new work is stopped. The work is carried in. This work is also stopped at a predetermined position by a similar stopper or the like. In this way, the workpieces are heat-treated one by one. Note that the stopper or the like only stops the work, and does not slide in contact with only a very small part of the work, so that the cleanness of the work is not impaired.

In such an air levitation apparatus, the transport speed can be changed as required. At that time, the transport speed can be adjusted by changing the flow rate and pressure of the propulsion air. In the deceleration and stop sections, the nozzle tilt angle is approached vertically or turned in the opposite direction, and an appropriate number of suction holes for partially inhaling the blown air are arranged in a different pitch arrangement from the air supply holes 11 to support the floating. A method of applying a suction force to the worked workpiece to perform a braking and stopping action, or the like can be appropriately adopted.

FIG. 5 shows a schematic configuration of a multi-stage heat treatment apparatus using the floating transfer plate shown in FIGS. 1 and 2 and a work floating transfer device provided with the plate. This apparatus includes an entrance elevator section 100, a heat treatment section 200, and an exit elevator section 3
00 and the like. The heat treatment section 200 is constituted by, for example, about 10 stages as the workpiece floating transfer devices 100-1 to 100-N shown in FIG. The entrance and exit elevator sections 100 and 300 are each one stage of the work levitation device 100.
Although not shown, it is configured to be able to move up and down and stop at a predetermined position by ordinary various lifting mechanisms such as a lifting guide and a lifting drive (not shown).

In this apparatus, as in the apparatus shown in FIG. 2, the two workpieces are heat-treated in the heat treatment section, and when the workpieces of each stage complete the heat treatment in sequence, the transfer devices of the entrance and exit elevator sections are moved to that position. It moves, and a work is taken in and out of these, and is exchanged with an external conveyance process. Also in this apparatus, each part of 100 to 300 is maintained in a state of high cleanliness. Further, as described above, since the floating transport plate has a sheet metal thin plate structure and is sufficiently lightweight, even with such a multi-stage apparatus, it is possible to satisfy the load limitation of the floor grating in a clean room or the like.

In the above description, the case where the floating transport plate and the workpiece floating transport device are mainly heat treatment devices has been described. However, various devices such as a preheating device, a cooling device, and a cooling device, and a production process of an LCD glass substrate, etc. It can be used as a connection device between various devices and various devices for cleanly transporting a planar work.

When the work is not transported, the work can be positioned easily by setting the work in a floating state. In this case, since there is no sliding between the work and the support pins at the time of positioning, problems such as rubbing of the liquid crystal surface are solved.
Therefore, the floating transport plate is effectively used as a work positioning device. In the above description, an example in which the work is transported cleanly in the air has been described.However, the present invention may be applied to various devices that levitate or transport the workpiece in an inert gas atmosphere such as nitrogen gas. it can.

[0039]

According to the present invention, a guide member is provided at a predetermined interval between both ends in the width direction of a work on a transfer surface where a plurality of holes from which gas is blown out are formed, and the work is lifted from the transfer surface at this interval. Since the interval is set so as to increase the levitation force of the work by providing a passage resistance to the gas to be made, the guide member prevents the work from meandering, avoids contact between the work and the guide member, and improves cleanliness during work transfer. be able to.

That is, since the interval between the guide members is set so as to increase the levitation force of the work by giving the passage resistance to the gas,
When the interval changes, the levitation force of the work is affected and increases or decreases.
Therefore, when the distance between both ends of the work changes due to the eccentricity of the work even if the work is slightly eccentric, the work floating force immediately increases on the side where the work space becomes narrower and decreases on the opposite side. As a result, the work is slightly inclined, the work lifting force, which is a force due to the pressure acting at right angles to the work surface, is inclined, and a horizontal component force is generated which causes the work to slide toward the wide side. Further, the pressure relationship under the work also changes with the inclination of the work, and the work tends to be balanced. And
Due to such a modified thrust and pressure change, the work is immediately centered and returned to the initial horizontal floating state.

As described above, since the centering action always operates from the stage where the eccentricity of the work is minute, the eccentric inertia force of the work does not increase, and the centering force increases further when the work approaches the guide member. Does not collide with or slide on the guide member. As a result, a clean transport state is ensured. According to such a levitation plate, the work is centered only by the action of air necessary for the levitation transfer of the work, so that it is not necessary to apply a special external force to the work by another means. Therefore, it is possible to make the device simple in structure, reliable in operation and inexpensive.

[Brief description of the drawings]

1A and 1B show a configuration example of a floating transport plate to which the present invention is applied, wherein FIG. 1A is a longitudinal sectional view showing the entire structure, and FIG. 1B is a partial sectional view taken along line AA of FIG.

FIG. 2 is a perspective view of a heat-treating work floating apparatus using the above-described floating transfer plate.

FIGS. 3A and 3B are explanatory views of a floating state of a work.

FIGS. 4A to 4C are explanatory diagrams of a centering operation of a work.

5A and 5B show a heat treatment apparatus in which the apparatus of FIG. 2 is configured in multiple stages, wherein FIG. 5A is a front view and FIG. 5B is a side view.

[Explanation of symbols]

 3 Guide part (guide member) 11 Air supply hole (plural holes) 12a Transport surface c Interval (predetermined interval) W Work Wa, Wb Both side surfaces X Work width direction

Claims (1)

[Claims] 1. A work floating and transporting structure for transporting a flat plate-shaped workpiece having both side surfaces parallel to the transport direction by blowing out gas from a plurality of holes formed in the transport surface and floating while passing through the both side surfaces. Wherein the guide member is provided so as to have a predetermined interval between the two side surfaces and an interval for providing a passage resistance to the gas passing through the two side surfaces, Structure.