TWI495607B - Handling device - Google Patents

Description

Handling device

The present invention relates to a conveying device that transports a substrate such as thin glass and transports it.

In the manufacture of a flat panel display such as a liquid crystal display, in order to transport a substrate such as thin glass without damage, it is a transport device that transports the substrate by floating it. Such a conveying device usually includes a belt conveyor or a roller conveyor for discharging a compressed air floating device and having a driving force in contact with the floating substrate.

The surface of the dust and the adhesion of the dust on the glass substrate will have a significant impact on the quality of the display. One of the main causes of dust adhesion and surface scratches is that the glass substrate is in contact with a conveying device or the like. On the other hand, the glass substrate has flexibility because it has a thickness of, for example, 0.7 mm or less, and it is important to convey the substrate in a flat manner in order to prevent contact during transportation. In recent years, thinner glass has been demanded, and it has become increasingly difficult to carry it flat.

Patent Document 1 discloses a technique including a conveying device of a belt conveyor. According to this technique, the belt body is provided with protrusions arranged at equal intervals by making the protrusions It is conveyed by contact with the floating glass substrate.

Patent Document 2 discloses a technique including a conveying device of a roller conveyor. According to Patent Document 2, the technical problem recognized is that "the central portion of the passage of the glass substrate floats upward and hangs down to make the bending become remarkable." In order to solve this problem, the bending of the glass substrate is suppressed by adjusting the air supply amount of the air stage unit located at the center in the width direction.

[Patent Document 1] Japanese Patent Application No. 2008-066661

[Patent Document 2] Japanese Patent Application No. 2008-260591

The above technique maintains the glass substrate substantially flat. However, in the conveyance direction, there is still a technical problem with respect to local bending of the front end bending or the like. That is, when the glass substrate is moved from one roller to the next, or when moving from one carrier to the next, since the member supporting the front end is not provided, the front end is bent downward due to its own weight. . There is a problem that the front end easily collides with the roller or the conveying device.

The present invention has been developed in view of the above problems. In contrast to the above-mentioned technical knowledge, the inventors of the present invention completed the present invention by simply supporting both ends in the width direction of the glass substrate and slightly bending the central portion of the glass substrate to suppress the bending of the tip end.

According to an aspect of the invention, the gas is used to float the object to the first The transport device for transporting in one direction includes a floating portion, a transport portion, a cover, and a suction portion, and the floating portion applies a positive pressure to the object by ejecting the gas to float the object; and the transport portion has a belt body And at least one of the plurality of rollers is configured to be driven in the first direction in contact with the object, and the belt is an endless belt extending in the first direction, and has a protrusion for contacting the object a plurality of protrusions, the plurality of rollers being rotatable in the first direction and arranged along the first direction; the cover covering the transport portion or extending adjacent to the transport device in parallel, allowing only the plurality of The upper end of each of the protrusions or the upper end of the plurality of rollers protrudes, and has a surface parallel to the lower surface of the object; the suction portion applies a negative pressure to the inside of the outer cover to bring the object into contact with the conveying portion.

The front end of the substrate can be prevented from being bent, and the substrate can be prevented from colliding with the conveying device or the like.

100‧‧‧Transportation device

120,120B‧‧·Transportation Department

2c, 126, 226, 326, 426‧‧ ‧ outer cover

128,728‧‧‧Attraction

114‧‧‧Protrusion

116‧‧‧Upper

118‧‧‧Support table

314‧‧‧Roller

X‧‧‧Transportation direction

W‧‧‧Workpiece

G, G’‧‧‧ gas

Fig. 1 is a perspective view showing a part of a conveying device according to an embodiment of the present invention.

The second (a) to (c) drawings are three sides of the conveying device of the present embodiment.

The third (a) and (b) drawings are cross-sectional views of the conveying portion and the suction portion of the present embodiment.

4(a) to 4(d) are cross-sectional views of the conveying portion and the suction portion of the other embodiment.

The fifth (a) to (c) are cross-sectional views of the suction portion and the conveying portion of still another embodiment.

Fig. 6(a)(b) is a perspective view showing a part of the conveying device of the other embodiment.

Fig. 7(a)(b) is a perspective view showing the substrate of the state in which the front end is bent by bending the vicinity of the center.

Several illustrative embodiments of the invention are described below with reference to the drawings.

The conveying device according to the embodiment of the present invention is suitable for conveying a thin object such as a glass substrate in, for example, a clean room. In the case of a glass substrate, it is not only about a thickness of about 0.7 mm, but also an extremely thin one having a thickness of about 0.1 to 0.3 mm.

Referring to Fig. 1, a conveying device 100 according to an embodiment of the present invention includes a floating portion 116 that floats a workpiece W (object), and a conveying portion 120 that drives the workpiece W in a direction X (first direction). The floating portion 116 is provided with an opening 116a for ejecting a gas, and the ejected gas applies a positive pressure to the workpiece W to float the workpiece W. The conveyance unit 120 has a plurality of projections 114 that are driven in the direction X by a motor or the like, and conveys the workpiece W by bringing the projections 114 into contact with the workpiece W. The detailed description of the transport unit 120 will be followed by providing the suction unit 128 to attract the gas around the protrusion 114. The workpiece W is in contact with the protrusion 114. The workpiece W may be supported and transported only by the transport unit 120 without using the floating portion 116.

Refer to Figure 2 for a more detailed explanation. Fig. 2(a) is a plan view showing a conveying device provided with a cover, and Figs. 2(b) and 2(c) are a front view and a side view of the conveying device in a state in which the cover is removed.

Both the belt body 112 and the upper floating portion 116 are supported by a support base 118 which is disposed on the floor or grille of the clean room through the support feet 118a. The floating portion 116 is arranged on the support table 118, for example, a plurality of floating portions 116 are arranged in the direction X, and a plurality of floating portions 116 are also arranged in a direction (width direction) orthogonal to the direction X. The number of arrays can be freely selected, and thus the configuration of the device can be arbitrarily changed corresponding to the size of the object. The transport unit 120 is usually disposed at both ends in the width direction of the plurality of floating portions 116, but other arrangements are also possible.

The upper floating portion 116 has a box shape as a whole, and its upper surface is substantially flat. The upper surface has an opening 116a that opens upward, and the opening 116a penetrates the upper surface to communicate with the inner space. The opening 116a is formed into a circular slit, for example, in the first and second drawings, and various shapes such as a rectangular shape, a plurality of slits, or a plurality of small holes may be employed. Further, the opening 116a can penetrate vertically upward, and can also be inclined with respect to the upper surface. Alternatively, a part or the entire upper portion of the floating portion 116 may be a gas-permeable mesh body or a porous body.

A gas supply device is provided outside the opening 116a, and a gas G such as air or nitrogen gas is supplied and ejected from the opening 116a. The gas supply device is a pump or a compressor that pressurizes the gas G to be supplied to the floating portion 116.

A gas supply device can be connected to an upper floating portion 116, and A plurality of floating portions 116 are coupled to a single gas supply device. Further, a chamber in which a certain amount of compressed gas can be stored may be interposed between the gas supply device and the floating portion 116.

The gas G ejected from the opening 116a generates a pressurizing space P between the workpiece W and the floating portion 116, thereby applying a positive pressure to the workpiece W to impart a buoyancy. At this time, in addition to the force generated by the ejected gas G colliding with the workpiece W, the static pressure generated during the process in which the collided gas G is dispersed toward the periphery also becomes a source of buoyancy. Therefore, a large buoyancy can be obtained with a slight pressing force, and the energy efficiency is excellent.

The belt body 112 is substantially an endless belt that is wound between two or more runners 110, and the entire conveying portion 120 is a belt conveyor. Each of the runners 110 is supported by a frame 102. As described above, the conveyance unit 120 is disposed at both ends in the width direction of the plurality of floating portions 116, and the belt body 112 extends in the direction X.

The main shaft 110a is coupled to the reel 110, and the main shaft 110a is pivotally supported by the support hole 102a of the frame 102, whereby the reel 110 can be rotated around it. The main shaft 110a is coupled to the gear 110b to be integrally rotatable. In the case of bonding, for example, a combination of a key and a key groove which are fitted to each other can be employed, and a structure in which the fitting is integrated instead of the fitting can be employed.

The conveying device 100 further has a driving device 110c such as an electric motor. The driving device 110c has a gear 110d that meshes with the gear 110b. The driving of the driving device 110c causes the rotating wheel 110 to rotate, and the belt 112 is rotated around the rotating wheel 110. Alternatively, the drive unit can also directly drive the wheel or further provide a suitable gear and pinion device.

The belt body 112 has a plurality of protrusions 114 that protrude outward. A plurality of protrusions 114 are arranged along the direction X. The protrusions 114 may be formed integrally with the belt body 112 or may be formed separately to be engaged with the belt body. The protrusions 114 are formed to be slightly higher than the floating height of the workpiece W as will be described later. The shape may be a cylinder, a rectangular parallelepiped, a cone or any other shape. Further, the front end thereof may be formed to be flat or formed in a spherical shape or a conical shape in order to reduce the contact area with the workpiece W. In addition, the front end can also have a lowered inclination toward the upper floating portion 116. This aspect will be explained later.

Referring to Figure 3(a), the strip 112 and the projections 114 are preferably covered by a cover 126. An opening 126c is provided at the upper end of the outer cover 126, and the projection 114 has only its upper end projecting upward from the opening 126c. As can be understood from Fig. 1, the opening 126c is a slit extending in the direction X, and the projection 114 can be moved in the direction X in a state where the upper end thereof protrudes. It is preferable that the outer cover 126 not only covers the upper side of the belt body 112 (the path that moves in the direction X) but also the lower side (the return path that moves in the direction opposite to the direction X).

The conveyance unit 120 includes a suction portion 128 inside the outer cover 126 or a suction portion 128 that communicates with the inside of the outer cover 126. The suction unit 128 is an air suction means such as a fan, a blower, or a pump, and the inside of the outer cover 126 is a negative pressure. The inner passage opening 126c of the outer cover 126 communicates with the space around the upper end of the projection 114, and sucks the gas G' in the space to cause the negative pressure NP to act on the workpiece W. The gas G' may be the same as the aforementioned gas G or may be other gases.

The upper end of the outer cover 126 may be formed to be tapered toward the upper end as shown in Fig. 3(b), and preferably has a flat upper end as shown in Fig. 3(a). The surface 126a, more preferably the surface 126a is substantially parallel to the lower surface of the workpiece W. In order to ensure parallelism, it is also possible to add a separately formed member at the upper end.

By making the surface 126a of the outer cover 126 substantially parallel to the lower surface of the workpiece W, as shown in Fig. 3(a), a pair of flow paths f can be secured therebetween, and the gas G' is directed toward the opening through the flow paths f. 126c attraction. The flow path f is a narrow flow path surrounded by both sides, and the pair of flow paths f are substantially symmetrical with respect to the opening 126c and the protrusion 114. By flowing the gas G' from the wide space into the narrow flow path f, the flow rate of the gas G' becomes large and the pressure is lowered based on the Bernoulli principle, whereby the negative pressure NP is generated. The flow path f has a substantially constant width throughout the entire flow, and the negative pressure NP is substantially constant throughout the flow path f.

The effects produced by the above structure can be more clearly understood by comparison between the third (a) and third (b) drawings. The graph below the 3(a) and (b) graphs shows the magnitude of the negative pressure NP (vertical axis) at different positions D (horizontal axis). For the sake of understanding, the vertical axis is absolute (the negative sign of the negative number) Become a positive sign). As shown in Fig. 3(b), the upper end 2a of the outer cover 2c is tapered toward the front end. When the belt body 1 and the suction portion 3 are covered, the negative pressure is concentrated near the center of the opening 2b, with the center negative pressure being removed. Sharply smaller. The negative pressure NP is large near the center of the opening 2b (dashed line a), but the negative pressure NP is remarkably small near the shoulders of the cover 2c (dotted line b, c) away from the center of the opening 2b. On the other hand, as shown in Fig. 3(a), when the upper end has a surface 126a substantially parallel to the lower surface of the workpiece W, a substantially constant negative pressure NP is generated throughout the entire pair of flow paths f, so that it is near the center of the opening ( Dotted line a) near the ends of face 126a (dashed line b, c) will A certain negative pressure NP is generated. That is, the range in which the end portion of the workpiece W is kept flat becomes large. Further, the attraction force acting on the workpiece W is the integral value of the negative pressure NP, and generation of the negative pressure NP over a wide range can cause a greater attractive force. Therefore, even if the output of the attraction portion 128 is small, a large attraction force can be obtained, and excellent energy efficiency is obtained.

Further, for example, the lower end of the outer cover 126 is provided with an opening to allow the gas G' to be exhausted from the opening to the outside. Preferably, the opening has an air cleaner 126f. Rotating bodies such as belt conveyors, fans or blowers often become the main source of dust in the clean room. By providing an air filter here, it is advantageous to maintain the cleanliness of the clean room.

Further, the opening can be connected to a gas supply means for supplying gas to the floating portion 116 to circulate the gas G. These constitute a loop. As far as the gas supply device is concerned, it is advantageous to save energy based on the energy efficiency of the inflow and outflow balance. In this case, one of the air suction means and the gas supply means may be omitted, and the other side may serve as means for sucking the gas and means for pressurizing the gas.

The shape of the cover can be variously deformed. For example, as shown in Fig. 4(a), the upper surface 226a of the outer cover 226 is inclined in accordance with the bending of the workpiece W. Specifically, the inclination of the lower portion of the end portion when the workpiece W is bent in the center in the width direction thereof is parallel. The opening 226c is provided on the inclined surface 226a. Not only is it advantageous to ensure the parallelism of the face 226a and the workpiece W, but also the workpiece W can be prevented from contacting the cover 226.

As shown in Fig. 4(b), the entire outer cover 126 may be tilted. Specifically, the outer cover 126 has an adjustment portion for adjusting the inclination thereof. 320. The adjustment unit 320 has a support body 320a that supports the outer cover 126, and a main shaft 320b that supports the support body 320a. The outer cover 126 is rotatable about the main shaft 320b to adjust its inclination. A driving means such as an electric motor can be coupled to the main shaft 320b. The bending of the workpiece W varies depending on the type, thickness, or conditions under which the floating portion 116 is driven. As long as the adjustment unit 320 is provided as shown in Fig. 4(b), the parallelism between the surface 126a and the workpiece W can be ensured in accordance with various bending.

As shown in Fig. 4(c), the face of the upper end of the outer cover 326 may further have an inclined surface 326f. The inclined surface 326f starts from the shoulder of the upper end surface and is inclined away from the workpiece W as it leaves the opening 326c. The inclined surface 326f may be a circular arc surface as shown in the figure, or may be a plane or a collection of planes whose angles gradually change. The gas G' first passes through the vicinity of the inclined surface 326f and then flows into the flow path f. At this time, the flow rate is gradually increased and the pressure is gradually decreased by passing the gas G' through the gradually narrowing flow path. That is, the pressure at the entrance of the flow path f does not cause the pressure to drastically change, and the gas G' does not easily turbulently flow. These are all beneficial to ensure the flatness of the W end of the workpiece. In addition, pressure loss is less likely to occur, and an energy efficiency based viewpoint is also advantageous.

As shown in Fig. 4(d), the upper surface of the outer cover 426 may have an outwardly extending flange portion 426a. The flange portion 426a is of course preferably substantially parallel to the lower surface of the workpiece W. In this way, the flow path f can be formed between the flange portion 426a and the lower surface of the workpiece W, and a uniform negative pressure NP can be generated in the range from the opening 426c to the flow path f. It is advantageous to expand the range in which the uniform negative pressure NP is generated, and to secure a wide opening 426c, so that the pressure loss becomes small, and it is also advantageous from the viewpoint of energy efficiency.

The parallelism between the upper end surface of the outer cover and the lower surface of the workpiece W is not necessarily critical, as shown in Figs. 5(a) and (b). In the example of Fig. 5(a), the surface 526a is inclined toward the center of the workpiece W, and the surface 526a and the lower surface of the workpiece W form an angle. In the example of Fig. 5(b), the face 626a is inclined with respect to the center in a bilaterally symmetrical manner, and the face 626a forms an angle with the lower face of the workpiece W. If the angle is, for example, about 10°, it is acceptable, and it is more preferably 5° or less in order to sufficiently obtain the effect described later.

The belt body 112 and the projections 114 do not have to be covered with a cover. In the example shown in Fig. 5(c), the belt body 112 and the projection 114 are provided outside the suction pipe 726, which is a member corresponding to the outer cover. Preferably, the belt body 112 and the projection 114 are located outside the suction tube 726 in the width direction of the conveying device. The upper end of the suction pipe 726 becomes an opening 726c that communicates with the inside. The opening 726c is a slit that extends in the direction X. Further, a flange portion 726a is provided continuously to the opening 726c. The flange portion 726a is of course preferably substantially parallel to the lower surface of the workpiece W. The flange portion 726a may be provided on both sides of the opening 726c, and the flange portion 726a may be provided only on one side as shown. A suction portion 728 is provided inside the suction pipe 726 or a suction portion 728 is provided in communication with the inside of the suction pipe 726. An opening for exhausting is provided in communication with the suction portion 728, and an air cleaner can be provided in the opening as in the above-described embodiment. Although the negative pressure of the projections 114 is not symmetrical, the other effects are the same as those of the embodiment described above.

According to any of the above embodiments, the suction portion transmits the negative pressure NP to the workpiece W through the opening, and the end portion of the workpiece W comes into contact with the projection. The end of the workpiece W travels with the protrusion in contact with the protrusion, thereby moving Shipped. The opening surrounds the projection, and a negative pressure NP is generated around the wide range, so that the end portion of the workpiece W can be kept flat over a wide range in the width direction. Furthermore, since the opening extends in the direction X, the end of the workpiece W can be kept flat over a wide range along the direction X.

Further, the conveying unit 120 may be configured to suck the gas G' instead of sucking the gas G' from the opening. The gap between the lower surface of the workpiece W and the upper end of the outer casing allows the gas G' to flow out at a considerable flow rate. At this time, if the gap becomes large, the flow velocity will change, and a negative pressure will be generated based on the Bernoulli principle. As long as the gap and the flow rate are in a specific relationship, a negative pressure sufficient to attract the workpiece W can be generated. That is, the conveyance unit 120 functions as a so-called Bernoulli chuck, and applies a negative pressure NP to the workpiece W.

The ends of the workpiece W are supported by a plurality of protrusions 114 arranged in a row, and move therewith, maintaining a flat shape like a ceiling supported by a beam and column. As the workpiece W shown in Figs. 3 and 4 is lowered toward the left, it is understood that the end portion of the workpiece W is flatly supported, and on the other hand, the vicinity of the center of the workpiece W is slightly bent by its own weight. That is, when viewed in the direction X, the workpiece W has a concave shape. Alternatively, a deformation means for bending the vicinity of the center of the workpiece W may be provided.

One of the deformation means is a gas supply device that produces a specific floating height. The pressurized gas supplied from the gas supply means can be adjusted by the pressing force so that the floating height on the floating portion 116 can be made lower than the height of the workpiece W on the projection 114. Alternatively, among the plurality of floating portions 116 arranged in the width direction, only the buoyancy above the center floating portion 116 may be reduced. Alternatively, it is suitable to be disposed in the gas supply device or the floating portion 116. The pressure drop means or the flow rate adjustment means can reduce the buoyancy near the center. The deformation of the workpiece W can be made into a concave shape by this deformation means. Alternatively, the workpiece W may have a convex shape by enhancing the buoyancy generated by the floating portion 116.

Another example of the deformation means is that the projection 114 is configured to bend the workpiece W. The workpiece W has an inherent floating height on the floating portion 116 depending on the weight of the workpiece W and the buoyancy force generated by the floating portion 116. The workpiece W is supported at a height that is not curved with respect to the projections 114. As long as the projections 114 are formed to support the workpiece W to a higher height, the workpiece W can be made concave.

In another example of the deformation means, each of the front ends of the projections 114 has a downward inclination toward the floating portion 116. By tilting the projections 114, the vicinity of the center of the workpiece W can be caused to bend downward.

The above embodiment can have various modifications. Hereinafter, in particular, several embodiments of the deformation will be described with respect to the conveyance unit and the suction unit.

It can also replace the belt conveyor, as shown in Figure 6(a). The conveyance unit 120B includes a plurality of rollers 314 arranged in the direction X instead of the belt body 112 including the plurality of protrusions 114. The plurality of rollers 314 are covered by a single outer cover 126, and the upper ends of the rollers 314 protrude upward from the opening 126c of the outer cover 126, respectively. Similarly to the above embodiment, the gas G' is sucked through the opening 126c, and the negative pressure NP is applied to the workpiece W. The end of the workpiece W is brought into contact with the roller 314 by the negative pressure NP, and the roller 314 is driven to carry the workpiece W in the direction X. The surface around the opening 126c is substantially parallel to the lower surface of the workpiece W, and a negative pressure NP is generated throughout the range, and The flatness of the end of the workpiece W is maintained over a wide range.

The roller conveyor can be driven by the driving device shown in Fig. 6(b). A plurality of rollers 314 are arranged along the direction X, and are rotatably supported by the frame 302. Each of the main shafts of the roller 314 is coupled to the pulley 310b, and a driving device 310 such as an electric motor is also coupled to the pulley 310b. The pulleys 310b are coupled to each other by the belt body 310e, and all the rollers 314 are rotated in synchronization. The main shaft 310c of the driving device 310 preferably extends to the opposite side end, and rotates the opposite side pulley 310b. Thereby, the rollers 314 at both ends are rotated in synchronization. Alternatively, the drive unit may be configured by a spindle and a gear mechanism without using a belt body.

According to this aspect, both ends in the width direction of the workpiece W can be supported flat, and on the other hand, the vicinity of the center of the workpiece W can be slightly curved. In this way, the workpiece W is formed into a concave (or convex) shape, and the following effects are exhibited.

The effects that can be exhibited by the above embodiments will be described with reference to Fig. 7. Referring to Fig. 7(a), if the shape of the entire workpiece W is to be flat as in the prior art, when the front end of the workpiece W is not supported, the front end is bent downward as indicated by the arrow H due to its own weight. . This is the state, for example, when the workpiece W moves from one roller to the next, or from one carrier to the next. The workpiece W is easily bent against the roller or the conveying device because it is bent downward. On the other hand, according to the present embodiment, as shown in Fig. 7(b), both ends in the width direction of the workpiece W are flat along the conveyance direction X, but the vicinity of the center is slightly curved. Thus, the workpiece W becomes wavy in the width direction, so the workpiece is moved in the conveying direction X. W cannot be freely deformed, and the front end of the workpiece W is not bent downward even if it is not supported. Even when the workpiece W moves from one roller to the next, or when moving from one conveying device to the next, the front end of the workpiece W can be prevented from colliding with the roller or the conveying device.

Although the invention has been described by way of preferred embodiments, the invention is not limited to the embodiments described above. In view of the above disclosure, those skilled in the art can change the embodiments and practice the invention.

[Industry Utilization]

A conveying device capable of preventing the front end of the substrate from being bent is provided.

100‧‧‧Transportation device

114‧‧‧Protrusion

116‧‧‧Upper

116a‧‧‧ openings

120‧‧‧Transportation Department

X‧‧‧Transportation direction

W‧‧‧Workpiece

Claims (7)

A transport device that transports an object to the first direction by using a gas, and includes a floating portion, a transport portion, a cover, and a suction portion, and the floating portion applies a positive gas to the object Pressing to raise the object; the transporting portion includes one of a belt body and a plurality of rollers, and is configured to be driven in the first direction in contact with the object, and the belt body is endlessly extended in the first direction The strip body has a plurality of protrusions protruding in contact with the object, and the plurality of rollers are rotatable in the first direction and arranged along the first direction; the outer cover only allows the upper ends of the plurality of protrusions Or the upper ends of the plurality of rollers projecting to have a surface parallel to the lower surface of the object; the suction portion applies a negative pressure to the inside of the outer cover to bring the object into contact with the conveying portion; and the surface of the outer cover is opposite The inclination of the lower end portion of the object when the object is bent in the center in the width direction thereof is parallel. The conveying device according to claim 1, wherein the outer cover covers the conveying portion or extends parallel to the conveying device, and further has a slit extending in the first direction The aforementioned negative pressure acts on the object. The conveying device according to claim 1, wherein the surface of the outer cover is provided at one end thereof away from the object The slope of the direction of the slope. The conveying device according to claim 1, further comprising: an adjusting portion for adjusting the inclination of the outer cover. The conveying device according to the first aspect of the invention, wherein the floating portion or the conveying portion includes a deforming means configured to bend the object in a center in a width direction thereof. The conveying device according to claim 5, wherein the conveying unit includes the endless belt body, the deformation means is a gas supply device or the plurality of protrusions, and the gas supply device is configured to allow the floating device The portion generates a floating height lower than a height of the object on the plurality of protrusions, and the plurality of protrusions are formed to have a higher floating height than the object of the floating portion. The conveying device according to claim 1, wherein the suction portion is a fan, a blower or a pump provided in the outer cover.