JP2019194518A - Dryer - Google Patents

Abstract

To provide a dryer capable of efficiently drying the inside of a can body.SOLUTION: The dryer comprising a transportation section 102 that transports a can body 104 formed to have a cylindrical shape with a bottom plate attached thereto, and a nozzle 11 comprising a slit-shaped ejection port 15 that ejects gas in the direction of an upper opening 105 of the can body 104, is characterized in that the longitudinal direction of the ejection port 15 is parallel to the transportation direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drying apparatus, and more particularly to an apparatus applied to an apparatus for drying a bottomed cylindrical can.

  An inside baking oven (hereinafter referred to as IBO) for drying a bottomed cylindrical can body is a tunnel type oven that heats a can body by conveying a certain amount of the can body together with a resin or stainless steel conveyor net. . For example, as in the case of IBO 100 shown in FIG. 14, a type in which heating is performed in three regions (106, 108, 110) is the mainstream. The can body 104 whose inner surface is coated with the thermosetting resin coating by the inside spray machine in the previous process is conveyed to the IBO 100 in a state where the upper opening is directed upward (hereinafter referred to as “placement”).

  In the IBO 100, the cans 104 placed on the conveyor net 102 form a zigzag pattern in plan view, and pass through each region of the pre-tropical zone 106, the heating zone 108, the holding zone 110, and the cooling zone 114. In the pre-tropical zone 106, water and solvent are evaporated at about 100 ° C. In the temperature rising zone 108, the can body 104 is made to reach a predetermined temperature. In the holding band 110, the resin is crosslinked to make the molecular structure dense, and a coating film that satisfies the required performance is formed. In order to form a coating film that satisfies the required performance, it is necessary to ensure, for example, 190 ° C. × 60 sec. From the holding band 110, the air seal 112 is passed through, and the cooling band 114 cools the can from a temperature around 200 ° C., and is conveyed to the next step.

  In each region of the IBO 100, a nozzle body 116 is provided at a predetermined position above the can body 104 placed on the conveyor net 102. The nozzle body 116 includes a slit nozzle 117 that discharges a gas for drying the can body 104 in parallel to the longitudinal direction of the can body 104. The slit nozzle 117 has a slit-like discharge port whose longitudinal direction is the direction orthogonal to the conveying direction of the can body 104, that is, the width direction of the conveyor net 102. The discharge ports have a predetermined width (for example, 3 to 7 mm), and a plurality of discharge ports are arranged in the transport direction at regular intervals (for example, 75 to 90 mm). The gas discharged from the slit nozzle 117 has a Reynolds number (hereinafter, “Re number”) of about 2000 (12 to 16 m / s at the discharge port). As described above, when the can body 104 is dried, in the area where the slit nozzle 117 is provided, a collision jet that blows the gas discharged from the slit nozzle 117 into the can, and the slit nozzle 117 is provided. Natural convection heat transfer is used in areas that are not.

  Although not shown in the figure, the IBO 100 circulates hot air heated by a burner by sucking outside air as a gas by a hot air circulation system. The hot air is blown out from the upper blow nozzle 118 and is distributed and equalized over the entire area by sequentially passing through the punching plate 120 immediately after the blow nozzle 118 and the punching plate 122 immediately before the slit nozzle 117. . In this way, hot air with a uniform flow velocity blows out from the slit nozzle 117.

  As the slit nozzle, Patent Document 1 discloses a eddy current generating device in which a pair of corrugated plates are arranged so as to be spaced apart from each other so that their crests and troughs are orthogonal to each other. According to Patent Document 1, when air in a turbulent state generated by a vortex generator reaches a can body, the flow of air around the can body is disturbed, and moisture attached to the surface of the can body is efficiently dried. can do.

Japanese Patent Laid-Open No. 3-95385

  However, the slit nozzle of Patent Document 1 is configured such that the collision jet from the slit nozzle is intermittently blown into the can because the longitudinal direction of the discharge port is arranged in a direction orthogonal to the transport direction. Yes. When the interval between the slit nozzles is larger than the outer diameter of the can, since there is an area (time) in which only natural convection heat is transferred, the drying efficiency is lower than that of a system in which a collision jet always flows. In addition, when the gap between the slit nozzles is smaller than the outer diameter of the can, it is estimated that there are areas where two impinging jets flow, making the flow in the can unstable, increasing energy consumption, and increasing initial equipment costs. The

  An object of this invention is to provide the drying apparatus which can dry the inside of a can body efficiently.

  The drying apparatus according to the present invention includes a transport unit that transports a can body formed in a bottomed cylindrical shape, and a nozzle having a slit-shaped discharge port that discharges gas toward the upper opening of the can body, The longitudinal direction of the discharge port is parallel to the transport direction.

  In the drying apparatus according to the present invention, the discharge port is disposed at a position shifted from the center of the can body in the width direction of the transport unit.

  In the drying apparatus according to the present invention, when the distance between the center of the discharge port in the width direction and the center of the can body is D and the radius of the can body is r, the discharge port is (r / 3) ≦ It is preferable to arrange in the range of D <r.

  In the drying apparatus according to the present invention, it is preferable that a suction port for sucking the gas is provided on the side opposite to the side where the discharge port is disposed across the center of the can body.

  In the drying apparatus according to the present invention, it is preferable that the transport unit has an alignment mechanism for aligning the can bodies in a line in the transport direction.

  In the drying apparatus according to the present invention, the nozzle includes a pair of nozzle walls arranged to face each other at a predetermined interval, and the discharge port at the tip of the nozzle wall, and the nozzle wall is disposed at the tip of the nozzle wall. It is preferable to have a plurality of protrusions protruding toward the nozzle wall.

  According to the present invention, since the longitudinal direction of the discharge port is arranged in parallel with the transport direction, the upper opening of the can body is continuously exposed to hot air, so that the inside of the can body can be efficiently dried. Can do.

It is a schematic diagram which shows the whole structure of the drying apparatus of this embodiment. It is a perspective view of the nozzle used for the drying apparatus of this embodiment. It is a top view of the said nozzle. It is sectional drawing with which it uses for description of an effect | action of the said nozzle. It is a perspective view which shows the modification of the said nozzle. It is a perspective view which shows the structure of an experimental apparatus typically. It is the elements on larger scale of an experimental apparatus. FIG. 8A is a visualized image obtained by photographing the gas that has passed through the nozzle of the embodiment, FIG. 8A is a nozzle near the left side of the can body, FIG. 8B is a nozzle near the center left of the can body, FIG. FIG. 8D is a visualized image when the nozzle is on the right side of the can body. FIG. 9A is a plan view showing positions of the can body and the nozzle corresponding to each figure of FIG. 8, FIG. 9A is a position where the nozzle is D = r on the left side surface of the can body, and FIG. = (R / 3), FIG. 9C is a plan view of the position where D = r on the right side of the can body, and FIG. . It is a graph which shows the temperature change of a can body in case the position of a nozzle is D = 0. It is a graph which shows the temperature change of a can body in case the position of a nozzle is D = (4r / 5). It is a contour diagram of temperature and speed. It is a graph which shows the relationship between the position of a nozzle, and the temperature difference of a can. It is a schematic diagram which shows the whole structure of the conventional drying apparatus.

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

  A drying apparatus 1 according to this embodiment will be described with reference to FIG. The drying apparatus 1 that dries the bottomed cylindrical can body 104 is a tunnel type oven in which a certain amount of the can body 104 is collectively conveyed by a conveyor net 102 made of resin or stainless steel and heat-treated. The drying apparatus 1 is divided into three regions and heated. The can body 104 whose inner surface is coated with the thermosetting resin paint by the inside spray machine in the previous step is conveyed to the drying apparatus 1 in a state in which the upper opening 105 is faced up.

  In the drying apparatus 1, a temperature rising zone 108, a holding zone 110, and a cooling zone 114 are sequentially provided from the upstream side along the transport direction. And the pretropical zone 106 is provided ahead of the temperature rising zone 108 as needed. The cans 104 placed on the conveyor net 102 as a transport unit are arranged in a lattice shape in a plan view and pass through each region of the pre-tropical zone 106, the heating zone 108, the holding zone 110, and the cooling zone 114. In the pre-tropical zone 106, water and solvent are evaporated at 100 ° C. or lower. In the temperature rising zone 108, the can body 104 is made to reach a predetermined temperature. In the holding band 110, the resin is crosslinked to make the molecular structure dense, and a coating film that satisfies the required performance is formed. In order to form a coating film that satisfies the required performance, it is necessary to ensure, for example, 190 ° C. × 60 sec. From the holding band 110, the air seal 112 is passed through, and the cooling band 114 cools the can from a temperature around 200 ° C., and is conveyed to the next step.

  In each region of the drying apparatus 1, a nozzle body 10 </ b> A is provided at a predetermined position above the can body 104 placed on the conveyor net 102. The nozzle body 10 </ b> A includes a nozzle (described later) that discharges gas parallel to the longitudinal direction of the can body 104. In this specification, the term “parallel” is not limited to the state of being completely parallel, but includes the state of being slightly inclined from the state of being completely parallel.

  Although not shown in the drawings, the drying apparatus 1 draws outside air as a gas for drying the can body 104 and circulates hot air heated by a burner at about 100 ° C. to 255 ° C. with a circulation fan. The hot air is blown out from the upper blowing nozzle 118, and sequentially passes through the punching plate 120 immediately after the blowing nozzle 118 and the punching plate 122 immediately before the nozzle 11, so that the hot air is dispersed and equalized over the entire region. In this way, hot air with a uniform flow velocity blows out from the nozzle. Note that the basic configuration of the drying device 1 is not limited to the example shown in FIG. 1, and can be applied to other forms using a so-called impinging jet.

  As shown in FIG. 2, the nozzle body 10 </ b> A is provided with a nozzle 11. In the case of FIG. 2, one nozzle 11 is illustrated, but in reality, a plurality of nozzles 11 are provided at predetermined intervals in the width direction of the conveyor net 102. The nozzle 11 includes a pair of nozzle walls 12 and 14 disposed to face each other with a predetermined interval (for example, 3 to 7 mm). In FIG. 2, the conveyance direction is the x direction, the width direction of the conveyor net 102 as the conveyance unit is the y direction, and the direction perpendicular to the conveyor net surface is the z direction.

  The nozzle 11 has a flow path for guiding the hot air that has passed through the punching plate 122 (FIG. 1) in one direction. The flow path has a flat shape formed between the nozzle walls 12 and 14. One direction is a hot air discharge direction. In the case of FIG. 2, the one direction is an arrow direction (z direction) in the figure, and is a direction parallel to the central axis of the bottomed cylindrical can body 104 placed with the upper opening 105 facing upward. The length in one direction of the nozzle 11 can be selected as appropriate.

  In the case of this embodiment, the nozzle walls 12 and 14 are formed by a pair of flat plates arranged at a predetermined interval. The nozzle walls 12 and 14 are integrated with the top plate 13 at the base end. In the nozzle body 10A, the nozzle 11 is formed with the top plate 13 interposed therebetween. The base end of the nozzle 11 is an inlet of hot air that has passed through the punching plate 122.

  The can bodies 104 are transported in a state of being aligned in a line in the transport direction. The drying apparatus 1 preferably has an alignment mechanism (not shown) that aligns the cans 104 in a line in the transport direction on the upstream side of the conveyor net 102. By having the alignment mechanism, the cans 104 conveyed in a staggered manner in a plan view from the process upstream of the drying device 1 can be aligned in a row.

  The tip of the nozzle 11 is provided with a discharge port 15 serving as an outlet for hot air that discharges hot air toward the upper opening 105 of the can body 104. The discharge port 15 has a slit-shaped opening. The nozzles 11 are arranged such that the longitudinal direction of the discharge ports 15 is parallel to the transport direction (x direction), that is, parallel to the longitudinal direction of the conveyor net 102. The length of the discharge port 15 in the width direction is shorter than the radius of the can body 104. The flow path connecting the inlet of the nozzle 11 and the discharge port 15 has a flat shape when viewed from one direction. The opening area of the flow path is preferably constant until just before the discharge port 15. In the case of FIG. 2, the flow path and the discharge port 15 are rectangular when viewed from one direction. The hot air discharged from the nozzle 11 has a predetermined Re number, for example, about 2000 (12 to 16 m / s at the discharge port). As described above, in the drying of the can, a so-called collision jet flow in which hot air discharged from the nozzle 11 is blown into the can body 104 is employed.

  As shown in FIG. 3, the discharge port 15 is preferably arranged at a position shifted from the center of the can body 104 in the width direction of the conveyor net 102. The center of the can body 104 refers to the center of the circular can body 104 when viewed from the central axis direction. The position of the discharge port 15 does not include the center of the can body 104, and can be selected within a range up to the intersection of the straight line in the y direction passing through the center of the can body 104 and the body of the can body. In the case of FIG. 3, the discharge port 15 is disposed at a position shifted from the center of the can body 104 to the left side in the width direction (y direction) of the conveyor net 102.

  When the distance between the center of the discharge port 15 in the width direction and the center of the can body 104 is D and the radius of the can body 104 is r, the discharge port 15 is in the width direction (y direction) of the conveyor net 102. Therefore, it is preferable to arrange in the range of (r / 3) ≦ D ≦ (2r / 3). By disposing the discharge port 15 within the above range, most of the hot air discharged from the discharge port 15 is sent into the can body 104, and along the inner surface of the body portion of the can body 104 by the Coanda effect described later. It is possible to go straight and easily enter the inside of the can body 104.

  In addition, although FIG. 3 demonstrated the case where the discharge port 15 was arrange | positioned in the position shifted | deviated from the center of the can 104 to the width direction (y direction) left side of the conveyor net 102, the width direction (y direction) right side was demonstrated. Of course, it may be shifted.

  The discharge ports 15 are preferably arranged in the range of (r / 3) ≦ D <r. By disposing the discharge port 15 in the range of (r / 3) ≦ D <r, the hot air that has entered the can body 104 advances more reliably along the inner surface of the body portion by the Coanda effect described later. Therefore, the entire can body 104 can be heated more uniformly. The discharge port 15 is more preferably arranged in the range of (3r / 5) ≦ D <r.

  The drying apparatus 1 may provide the suction port 21 on the opposite side of the discharge port 15 with the center of the can body 104 interposed therebetween. Although not shown, the suction port 21 is connected to a circulation fan through a pipe. As with the discharge port 15, the suction port 21 has a slit-like opening and is arranged so that its longitudinal direction is parallel to the longitudinal direction of the conveyor net 102. The distance between the suction port 21 and the center of the can body 104 may be the same as or different from the above D, and can be selected as appropriate.

  Next, the operation and effect of the drying apparatus 1 will be described. In the drying apparatus 1, the can body 104 is transported in a state where the conveyor net 102 is aligned in a line in the transport direction. The cans 104 are arranged in a plurality of rows in the width direction of the conveyor net 102 and are arranged in a lattice shape as a whole. Hot air is discharged toward the upper opening 105 of the can body 104 from the discharge port 15 arranged at a predetermined upper position. Since the longitudinal direction of the discharge port 15 is arranged in parallel with the transport direction, the upper opening 105 of the can body 104 is continuously exposed to hot air, so that the inside of the can body can be efficiently dried.

  As shown in FIG. 4, the hot air discharged from the discharge port 15 is disposed at a position shifted in the width direction (y direction) from the center of the can body 104, so It goes straight along the inner surface of the part and can easily enter the inside of the can body 104. Part of the hot air that has entered the inside of the can body 104 becomes a horizontal vortex centering on a direction parallel to the longitudinal direction of the discharge port 15, and the remaining portion is moved to the center of the can body 104, while the remaining portion is caused by the Coanda effect. Along the inner surface, it reaches the bottom of the can body. The hot air that has reached the bottom of the can body rises along the inner surface of the opposite body portion.

  Since the drying apparatus 1 according to the present embodiment can easily allow hot air to enter the inside of the can body 104, the inner surface of the can body 104 can be efficiently dried. By disposing the discharge port 15 in the range of (r / 3) ≦ D ≦ (2r / 3), the hot air discharged from the discharge port 15 can be more easily and easily entered into the can body 104. .

  The drying apparatus 1 can heat the entire can body 104 more uniformly by disposing the discharge ports 15 in the range of (r / 3) ≦ D <r. By disposing the discharge port 15 in the range of (3r / 5) ≦ D <r, the temperature difference in the can body 104 can be further reduced.

  The can body 104 is transported under a discharge port 15 whose longitudinal direction is parallel to the transport direction, with the can bodies 104 aligned in a line in the transport direction. Since the flow rate of the hot air entering the can body 104 is constant, the drying apparatus 1 can be efficiently dried because the can body 104 is continuously exposed to the hot air.

  By disposing the nozzle 11 as described above, hot air can be continuously supplied from the upper opening 105 of the can body 104 to the inside of the can body, and the supplied hot air is efficiently distributed along the inner surface of the can body. Reach the bottom. Therefore, since the can 104 is heated by the hot air which contacted, the can 104 is dried efficiently. In particular, when the can 104 is made of aluminum, the heat transfer coefficient is high, so that the can 104 is dried more efficiently.

  In the case of the conventional drying apparatus 100, since the longitudinal direction of the discharge port is arranged to be parallel to the width direction of the conveyor net, the change in the flow rate of hot air entering the can body is large, and the upper opening of the can body is Since the exposure to hot air is intermittent, it is not efficient. In an area where there is no discharge port, basically only heat transfer by natural convection is in a so-called steamed state. The cans on the actual conveyor net are transported in a dense state arranged in a staggered pattern rather than a lattice pattern. Therefore, the can group arranged in a staggered pattern has a larger fluid resistance than the can group arranged in a lattice pattern. It is considered that the flow velocity of hot air discharged from the discharge port rapidly decelerates in the vicinity of the upper opening of the can body, and the hot air is likely to flow to a portion where there is no can group. In order to forcibly supply the hot air between the inner surface of the can body or between the can bodies, it is necessary to increase the flow velocity while preventing the can body from falling over, which is not realistic. By not supplying hot air between the inner surface of the can body or between the can body and the can body, it is difficult to efficiently heat the can body, and the temperature difference between the upper portion and the lower portion of the can body increases. As a result, the can body is in a state where suppression of uneven baking of the paint on the inner surface and residual solvent is not sufficient. Therefore, conventionally, it has been necessary to increase the drying time by reducing the conveying speed or lengthening the equipment.

  On the other hand, in the case of the present embodiment, the cans 104 and the cans 104 are widened by arranging the cans 104 in a lattice pattern at the entrance of the drying device 1. Hot air discharged from the discharge port 15 whose longitudinal direction is arranged parallel to the transport direction flows into the gap between the can body 104 and the can body 104 and into the can body 104. Since the gap between the can body 104 and the can body 104 is wide, hot air can easily flow into the gap. The effect of forced convection heat transfer from the outer surface of the can body 104 is contributed by the hot air.

  The hot air flowing into the can body 104 is likely to have a Coanda effect in the can body 104 because the discharge port 15 is arranged at a position shifted in the width direction (y direction) from the center of the can body 104. The hot air becomes a so-called wall surface jet due to the Coanda effect. Since the wall surface jet is less diffused than the free jet, the flow velocity is less likely to decrease, and the center velocity of the jet is maintained. Therefore, the wall surface jet in the can body 104 reaches the bottom of the can and forms a flow that blows up to the top of the can. In the baking process of the paint on the inner surface of the can body 104, evaporation and volatilization of water and solvent are accompanied with a crosslinking reaction of the paint. The wall jet prevents the solvent from staying in the can body 104 and efficiently moves the mass. The wall surface jet that has reached the bottom of the can blows up to the top of the can including the solvent, so that the mass transfer can be further promoted by collecting the jet.

  By arranging the cans 104 in a lattice pattern, the number of cans 104 transported per hour can be reduced as compared with the prior art. However, the drying apparatus 1 of the present embodiment can perform processing without reducing the transport quantity per hour by increasing the transport speed of the conveyor net by an amount corresponding to the improvement in the heat transfer rate and the mass transfer efficiency. As mentioned above, this embodiment can improve the quality of the coating film of the can body 104 and realize energy saving by improving the heat transfer rate and the mass transfer efficiency.

  In the case of the above embodiment, the flow path and the discharge port 15 have been described with respect to the case where the shape viewed from one direction is a rectangular shape, but the present invention is not limited to this. The nozzle body 10B shown in FIG. The nozzle 23 has a plurality of protrusions 31 protruding toward the nozzle walls 12 and 14 at the tip ends of the nozzle walls 12 and 14, in the case of FIG. 5, at the tips 27 and 28. The protrusion 31 has a comb shape, and a plurality of protrusions 31 are formed along the longitudinal direction of the discharge port 25. The protrusion 31 shown in FIG. 5 has a square shape when viewed from one direction. A recess 32 is formed between the protrusions 31. The recess 32 has a quadrangular shape like the protrusion 31.

  The hot air that has passed through the nozzle 23 as described above passes through the concave portion 32 between the protrusions 31 to form a vertical vortex having a unidirectional axis, thereby increasing straightness. Since the discharge port 25 according to this modification is arranged such that the longitudinal direction of the discharge port 25 is parallel to the transport direction, hot air can be continuously supplied to the upper opening 105 of the can body 104. It can be dried efficiently.

  By disposing the discharge port 25 at a position shifted in the width direction (y direction) from the center of the can body 104, the same effect as in the above embodiment can be obtained. Moreover, since the drying apparatus 1 provided with the nozzle 23 can discharge hot air with improved straightness from the discharge port 25 because the nozzle 23 has the protrusion 31, the interior of the can body 104 can be more efficiently discharged. Can be dried. By providing the nozzle 31 with the protrusion 31 and forcibly generating a vertical vortex, a large-scale vortex array of a free jet can be suppressed. The hot air that has passed through the nozzle 23 can extend the region (velocity potential core) in which the flow velocity of the discharge port is maintained compared to the hot air that has passed through the nozzle without protrusions, and has the same effect as increasing the Reynolds number. can get. The protrusion 31 is not limited to a quadrangular shape, and may be a triangular shape.

  In the case of FIG. 5, the protrusion 31 and the recess 32 formed on the nozzle wall 12 are formed at the same position as the protrusion 31 and the recess 32 formed on the nozzle wall 14, but the present invention is not limited to this. For example, the protrusion 31 and the recess 32 formed on the nozzle wall 12 may be displaced in the longitudinal direction of the protrusion 31 and the recess 32 formed on the nozzle wall 14 and the discharge port 15, and formed on the nozzle wall 12. A recess 32 may be formed in the nozzle wall 14 at a position corresponding to the protrusion 31.

  In the case of FIG. 5, the case where a plurality of protrusions 31 are provided at the tips 27 and 28 of the nozzle walls 12 and 14 has been described, but the present invention is not limited to this. The protrusion 31 may be formed at a position shifted in the inlet direction of the discharge port 25 within a range in which the straightness of the hot air due to pressure loss is not significantly reduced.

  In the case of the above embodiment, the drying apparatus 1 has been described as having an alignment mechanism (not shown) that aligns the can bodies 104 in a line in the transport direction on the upstream side of the conveyor net 102, but the present invention is not limited thereto. Absent. The alignment mechanism may be provided on the upstream side of the drying device 1 separately from the drying device 1.

  The result of actually verifying the effectiveness of the arrangement of the discharge ports according to the above embodiment will be described below. First, an experimental apparatus 124 shown in FIG. 6 was prepared. In the experimental device 124, gas is discharged to the can body 104 through the upper blowing nozzle 118, the punching plate 120, and the nozzle body 10 </ b> A. The gas had a Reynolds number of 2000 and a flow velocity at the outlet 15 of 6 m / s. The can body 104 is held by a linear guide 34 so as to be movable in a direction perpendicular to the longitudinal direction of the discharge port 15. The moving speed of the can 104 was 2.40 cm / s.

  The flow of the discharged gas was photographed by particle image velocimetry. Specifically, the flow of the gas discharged from the nozzle 11 was photographed using the CCD camera 36. Oil mist (average particle diameter 1 μm, specific gravity s≈1.05) was used as a tracer. The light source 38 was an Nd: YAG laser (maximum output 200 mJ), and the laser sheet was irradiated from the position shown in FIG.

  As the can body 104 (FIG. 7), a bottomed cylindrical body made of a transparent resin and having an upper opening with a diameter of 66 mm and a height of 123 mm was used. The nozzle 11 had a length in one direction of 30 mm, a length in the width direction of the discharge port 15 of 5 mm, and a distance from the table on which the can body was placed to the top plate 13 to 190 mm. FIG. 8 shows a result of photographing the flow of the gas discharged from the nozzle 11 using the CCD camera 36. FIG. 9 is a plan view showing the positions of the can body 104 and the discharge port 15 corresponding to the respective drawings of FIG.

  In the lower right of each image, the elapsed time from the time when the left body of the can 104 and the discharge port coincide is shown. As shown in FIGS. 8A and 8D, in the vicinity of the can body portion, the gas discharged from the discharge port 15 goes straight in one direction and enters the inside of the can body along the inner surface of the can body portion by the Coanda effect. is doing.

  As shown in FIGS. 8B and 8C, the gas discharged from the discharge port 15 when the discharge port 15 is located at a distance D from the center of the can body 104 of 9 mm (FIG. 8B) and 7.8 mm (FIG. 8C). It was confirmed that it entered the inside of the can body while heading to the can body due to the Coanda effect. Moreover, as shown in FIGS. 9B and 9C, the overlap between the discharge port 15 and the upper opening 105 is large, and most of the gas discharged from the discharge port 15 can be sent into the can body, which can be said to be efficient.

  From the above results, when the discharge port 15 is at least at a position of (r / 3) ≦ D, the gas discharged from the discharge port 15 enters the inside of the can body from the upper opening 105 while going to the can body portion. In order to efficiently send the hot air discharged from the discharge port 15 into the inside of the can body, it is necessary to considerably increase the overlap between the discharge port 15 and the upper opening. Therefore, it is preferable that D ≦ (2r / 3). It can be said.

  The result of actually verifying the relationship between the arrangement of the discharge ports and the heating temperature of the can body according to the above embodiment will be described below. A heat gun (SURE plastic jet PJ-214A manufactured by Ishizaki Electric Mfg. Co., Ltd.) was used as the jet source. For a can body having a height of 135 mm and an inner diameter of about 50 mm, a nozzle was disposed at a position about 20 mm above the upper end of the can body. The nozzle used was a flat nozzle having a discharge port with an opening width of 3 mm and a length of about 50 mm. Hot air having a wind speed of about 15 m / s, a temperature of about 300 ° C., and a number of lay nozzles of about 1400 was discharged from the nozzle. While changing the distance D from the center of the can body to the center of the discharge port, the temperature is measured at a position 8 mm (bottom) from the bottom of the can body, a position 68 mm (middle) from the bottom, and a position 127 mm (top) from the bottom. did. The temperature was measured at points a, b, and c when the can body was viewed from the central axis direction. The point a is one intersection of a straight line passing through the center of the can body and orthogonal to the longitudinal direction of the nozzle and the body portion of the can body. The point c is the other intersection of the can body body part facing the point a across the center of the can body. The point b is one intersection of a straight line passing through the center of the can body and parallel to the longitudinal direction of the nozzle and the body portion of the can body.

  FIG. 10 shows the result when the discharge port is arranged at a position where the distance D is 0 (center position of the can). In the graph, the horizontal axis represents time (s), the vertical axis represents temperature (° C.), and the curves represent changes in measured temperature at the bottom, middle, and top, respectively. The temperature at the bottom is the lowest at both the point a (= c) and the point b, and in particular, the temperature difference after 120 seconds from the start of the hot air discharge at the point a is 40.3 ° C. confirmed. FIG. 12 shows a contour diagram of temperature and speed 40 seconds after the start of hot air discharge. In the temperature contour diagram in the case where the distance D (nozzle position) is 0, it is shown that the top of the can body has the highest temperature, then the middle has the highest temperature, and the bottom has the lowest temperature. As can be seen from the velocity contour diagram, it can be seen that the velocity of the hot air discharged from the nozzle is rapidly decreasing at the middle of the can body. This result is consistent with the result of FIG. 10, and when the discharge port is at the center of the can body, the hot air discharged from the discharge port does not reach the bottom of the can body. The temperature difference is thought to increase.

  FIG. 11 shows the result when the discharge port is arranged at a position where the distance D is 4r / 5 (= 0.8r). In each graph, the horizontal axis represents time (s), the vertical axis represents temperature (° C.), and the curves represent changes in measured temperature at the bottom, middle, and top, respectively. At the point a closest to the discharge port, the top temperature is the highest, but at the point b, the temperature difference 120 seconds after the start of hot air discharge is as small as 3.5 ° C., and at the point c farthest from the discharge port, the middle And the bottom was hotter than the top temperature. As is apparent from the temperature contour diagram of FIG. 12, when the distance D is 4r / 5, it is shown that the temperature is high throughout the top, bottom, and middle. As can be seen in the velocity contour diagram, the hot air discharged from the discharge port enters the inside of the can body along the inner surface of the can body, folds back at the bottom, and along the inner surface of the can body on the opposite side. You can see that it is rising. This result is consistent with the result of FIG. 11, by arranging the discharge port at a position shifted from the center of the can body, the hot air discharged from the discharge port can reach the bottom of the can body, It is considered that the temperature difference between the bottom and the top becomes small.

  FIG. 13 shows the relationship between the distance D from the center of the can body to the can body and the temperature difference between the bottom, middle, and top at each point. From FIG. 13, it was confirmed that the temperature difference was the largest when the discharge port was arranged at the center of the can body (distance D = 0). It was shown that the temperature difference becomes smaller as the discharge port deviates from the center of the can body, and becomes the smallest when the distance D is 4r / 5 (= 0.8r).

DESCRIPTION OF SYMBOLS 1 Drying apparatus 10A, 10B Nozzle main body 11 Nozzle 12, 14 Nozzle wall 15 Discharge port 21 Suction port 23 Nozzle 25 Discharge port 31 Protrusion 100 Drying device

Claims (6)

A transport unit for transporting the can formed in a bottomed cylindrical shape;
A nozzle having a slit-like discharge port for discharging gas toward the upper opening of the can body,
A drying apparatus, wherein a longitudinal direction of the discharge port is parallel to a transport direction. The drying apparatus according to claim 1, wherein the discharge port is disposed at a position shifted from a center of the can body in a width direction of the transport unit. When the distance between the center of the discharge port in the width direction and the center of the can body is D and the radius of the can body is r, the discharge port is disposed within the range of (r / 3) ≦ D <r. The drying apparatus according to claim 1, wherein the drying apparatus is provided. The drying apparatus according to claim 2, wherein a suction port for sucking the gas is provided on a side opposite to the side where the discharge port is disposed across the center of the can body. The drying apparatus according to claim 1, wherein the transport unit includes an alignment mechanism that aligns the cans in a line in a transport direction. The nozzle includes a pair of nozzle walls arranged to face each other at a predetermined interval, and the discharge port at the tip of the nozzle wall, and protrudes toward the nozzle wall at the tip side of the nozzle wall. The drying apparatus according to claim 1, wherein the drying apparatus has a plurality of protrusions.

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