JP2021130111A - Nozzle, drier, and method of manufacturing can body - Google Patents

Abstract

To provide a nozzle capable of improving straightness of gas to be discharged, a drier, and a method of manufacturing a can body.SOLUTION: A nozzle 11 has slit-like discharge openings 15 provided at the tips of a pair of nozzle walls 12 and 14 arranged in the state of facing each other at a predetermined interval. A plurality of protrusions 20 protruding toward the mutual nozzle walls 12 and 14 are provided on the tip sides of the nozzle walls 12 and 14.SELECTED DRAWING: Figure 2

Description

The present invention relates to a nozzle, a drying device, and a method for manufacturing a can body.

The inside bake oven (hereinafter referred to as IBO) that dries the bottomed tubular can body is a tunnel type oven that transports a certain amount of the can body together with a resin or stainless steel conveyor net and heat-treats it. .. For example, as in the case of IBO100 shown in FIG. 16, the type in which heating is divided into three regions (106, 108, 110) is the mainstream. The can body 104 coated with the thermosetting resin paint on the inner surface of the can by the inside spray machine in the previous step is conveyed to the IBO 100 with the upper opening facing upward (hereinafter referred to as normal placement).

In the IBO 100, the can body 104 placed upright on the conveyor net 102 forms a staggered pattern in a plan view, and passes through each region of the pre-tropical 106, the temperature rising zone 108, the holding zone 110, and the cooling zone 114. In the pre-tropical 106, water and solvent are evaporated at about 100 ° C. In the temperate zone 108, the can body 104 is brought to a predetermined temperature. In the holding band 110, the resin is crosslinked to make the molecular structure dense, and a coating film satisfying the required performance is formed. For example, it is necessary to secure 190 ° C. × 60 sec in order to form a coating film satisfying the required performance. It is cooled from the holding zone 110 through the air seal 112 in the cooling zone 114 from a can temperature of 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 upright 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 with the vertical direction of the can body 104. The slit nozzle 117 has a slit-shaped discharge port whose longitudinal direction is the direction orthogonal to the transport direction of the can body 104, that is, the width direction of the conveyor net 102. A plurality of discharge ports have a predetermined width (for example, 3 to 7 mm) and are arranged at regular intervals (for example, 75 to 90 mm, etc.) in the transport direction. 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). When the can body 104 is dried as described above, in the area where the slit nozzle 117 is deployed, a convection jet that blows the gas discharged from the slit nozzle 117 into the can is also deployed, and the slit nozzle 117 is deployed. Natural convection heat transfer is used in areas where it is not.

Although not shown, the IBO 100 takes in outside air as a gas and circulates hot air heated by a burner by a circulation fan by a hot air circulation type. The hot air is blown out from the upper blowing nozzle 118 and passes through the punching plate 120 immediately after the blowing nozzle 118 and the punching plate 122 immediately before the slit nozzle 117 in order to disperse and equalize the pressure in each region. .. In this way, hot air having a uniform flow velocity is blown out from the slit nozzle 117.

As the slit nozzle, Patent Document 1 discloses a vortex generator in which a pair of corrugated sheets are arranged apart from each other so that their peaks and valleys are orthogonal to each other. According to the above Patent Document 1, when the air in the turbulent state generated by the vortex generator reaches the can body, it disturbs the flow of the air flow around the can body and efficiently dries the moisture adhering to the surface of the can body. can do.

Japanese Unexamined Patent Publication No. 3-95385

However, although it is known that a gas having high straightness can be obtained by generating the vortex of Patent Document 1, a complicated mechanism is required to actually generate the vortex, and the space is limited. Therefore, it is difficult to generate a large number of eddy currents.

A first object of the present invention is to provide a nozzle and a drying device capable of improving the straightness of the discharged gas.

A second object of the present invention is to provide a method for producing a can body, which can further improve the quality of the coating film formed on the inner surface of the can body.

The nozzle according to the present invention is provided with a slit-shaped discharge port at the tip of a pair of nozzle walls arranged so as to face each other at a predetermined interval, and protrudes toward the tip of the nozzle wall toward each other. It is characterized by having a plurality of protrusions.

In the nozzle according to the present invention, the Reynolds number of the gas discharged from the discharge port is 1000 to 10000, and the ratio of the area of the protrusions to the area of the gap between the protrusions is 1: 3 to 2: 1. Is preferable.

In the nozzle according to the present invention, the Reynolds number of the gas discharged from the discharge port is preferably 1000 to 4000.

In the nozzle according to the present invention, the protrusions preferably have a quadrangular shape when viewed from the discharge direction.

In the nozzle according to the present invention, the protrusions preferably have a triangular shape when viewed from the discharge direction.

The drying device according to the present invention is a drying device including a plurality of regions having different drying temperatures and a transport unit for transporting a can body formed in a bottomed cylinder shape into the plurality of regions. Each of the regions is characterized by having the nozzle.

In the drying apparatus according to the present invention, it is preferable that at least one of the shape of the protrusion and the ratio of the area of the protrusion to the area of the gap between the protrusions is different in the plurality of regions.

In the drying apparatus according to the present invention, the plurality of regions are provided with a pre-tropical zone, a temperate zone, and a holding zone in order from the upstream along the transport direction, and the protrusions in the pre-tropical zone are viewed from the discharge direction. It is quadrangular, the ratio of the area of the protrusions to the area of the gap between the protrusions is 1: 2, and the protrusions in the temperate zone and the holding zone are triangular when viewed from the discharge direction. The ratio of the area of the protrusions to the area of the gap between the protrusions is preferably 1: 3.

In the drying apparatus according to the present invention, the width and length of the discharge port are preferably shorter than the radius of the can body.

In the method for producing a can body according to the present invention, a bottomed tubular can body having a coating film of a thermosetting resin paint formed on the inner surface is conveyed to a plurality of regions having different drying temperatures, and the can body is brought to the inner surface. A step of baking the coating film is provided, and the step of baking the coating film includes a slit-shaped discharge port at the tip of a pair of nozzle walls arranged to face each other at a predetermined interval, and a tip of the pair of nozzle walls. It is characterized in that gas is discharged from a nozzle having a plurality of protrusions protruding toward the nozzle wall of each other on the side.

According to the present invention, hot air having improved straightness can be discharged from a nozzle. The hot air discharged from the nozzle travels straight in one direction and can easily enter the inside of the can body. Therefore, the drying device can efficiently dry the inside of the can body. Since the inside of the can body can be efficiently dried, the quality of the coating film formed on the inner surface of the can body can be further improved according to the method for producing the can body according to the present invention.

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 in the drying apparatus of this embodiment. 3A is a plan view of the nozzle, FIG. 3A is a diagram showing a nozzle of the first example, FIG. 3B is a diagram showing a nozzle of the second example, and FIG. 3C is a diagram showing a nozzle of the third example. It is a perspective view provided for the explanation of the operation of the nozzle. 5A is a diagram showing a modified example (1), and FIG. 5B is a diagram showing a modified example (2). It is a figure which provides the explanation of the experimental data. It is a graph which shows the result of having measured the velocity distribution in Re number 1000. It is a visualization image of the gas passing through the nozzle at Re number 1000, FIG. 8A is the xy plane of the comparative example, FIG. 8B is the xy plane of the nozzle of the third example, and FIG. 8C is the xy plane of the comparative example. The z-plane and FIG. 8D are visualized images of the x-z plane of the third example. It is a graph which shows the result of having measured the velocity distribution in Re number 2000. It is a graph which shows the result of having measured the velocity distribution in Re number 3000. It is a visualization image of the gas passing through the nozzle of the first example in Re number 3000, FIG. 11A is a visualization image of the xy plane, and FIG. 11B is a visualization image of the xy plane. It is a graph which shows the result of having measured the velocity distribution in Reynolds number 10000. It is a visualization image of the gas passing through the nozzle of the first example in Re number 10000, FIG. 13A is a visualization image of the xy plane, and FIG. 13B is a visualization image of the xy plane. It is a graph which shows the result of having measured the velocity distribution of the nozzle of the modification (2) in Re number 2000. It is a visualization image of the gas passing through the nozzle in Re number 2000, FIG. 15A is the xy plane of the comparative example, FIG. 15B is the xy plane of the nozzle of the modified example (2), and FIG. 15C is the comparative example. The xx plane and FIG. 15D are visualization images of the xx plane of the nozzle of the modified example (2). 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. The drying apparatus of this embodiment is used in the painting process in the method for manufacturing a can body. The outline of the manufacturing method of the can body will be described below. The can manufactured in the can body manufacturing method is, for example, formed by molding an aluminum plate of 0.20 mm to 0.50 mm, and is a two-piece can or bottle in which the contents such as beverages are filled and sealed. It is used for the can body of a can. In the present embodiment, a can body used for the two-piece can will be described as an example.

The can body is manufactured by undergoing a punching and cutting step, a DI step, a trimming step, a cleaning step, a printing step, a painting step, a necking step, and a franging step.

In the punching step and the cupping step (cupping step), a thin plate made of an aluminum alloy material is punched by a cupping press and drawn (cupping) to form a relatively large diameter and shallow cup-shaped body.

In the DI process (squeezing and ironing process), the cup-shaped body is subjected to DI processing (re-squeezing and ironing processing) by a DI processing device to form a bottomed tubular can body having a can body and a can bottom. By this DI processing, the can bottom of the can body is formed into the shape of the can bottom of the final can body.

In the trimming step, the open end of the can body is trimmed. The open end of the can body formed by the DI processing apparatus has ears formed and the height is non-uniform. By cutting and trimming the opening end portion, the height of the peripheral wall along the can axis direction at the opening end portion is evenly aligned over the entire circumference.

In the cleaning step, the can body is washed, lubricating oil and the like are removed, and then surface treatment is performed to dry the can body.

In the printing process, outer surface printing and outer surface painting are performed. External printing is applied to the can body using printing ink. Then, the outer surface is painted immediately after the outer surface is printed.

In the painting process, a coating film is formed on the inner surface of the can body and the bottom of the can body. For example, a thermosetting resin paint (for example, an epoxy-based paint) is used to form a coating film on the inner surface, and the can body on which the coating film is formed is heat-dried by the drying apparatus according to the present embodiment to form the coating film. Burn on the inside.

In the necking step, a necking die (diameter reduction die) is used to form a neck portion having a smooth inclined shape at the opening end portion by a necking process. Specifically, a necking die (necking die and guide block) is fitted inside and outside the can body, and the diameter becomes smaller toward the opening end between the necking die and the guide block. The neck part is molded by performing diameter processing. Further, by this diameter reduction processing, a cylindrical flange planned portion is formed above the neck portion.

In the flanging step, the planned flange portion is flanged to form an annular flange portion that protrudes radially outward from the upper end of the neck portion and extends along the circumferential direction.

In this way, the can body is manufactured and transported to a post-process of the flanging process. In this post-process, the inside of the can body is filled with contents such as beverages, the can lid is wrapped around the flange portion, and the can body is sealed.

The drying apparatus 1 according to the present embodiment will be described with reference to FIG. The drying device 1 for drying the bottomed tubular can body 104 is a tunnel type oven in which a fixed amount of the can body 104 is conveyed together by a conveyor net 102 made of resin or stainless steel and heat-treated. The drying device 1 is divided into three regions and heated. The can body 104 coated with the thermosetting resin paint on the inner surface of the can by the inside spray machine in the previous step is conveyed to the drying device 1 in a vertically placed state with the upper opening 105 facing upward.

The drying device 1 is provided with a temperature rising zone 108, a holding zone 110, and a cooling zone 114 in this order from the upstream along the transport direction. Then, if necessary, a pre-tropical 106 is provided in front of the temperate zone 108. The can bodies 104 placed upright on the conveyor net 102 as a transport unit are arranged in a grid pattern in a plan view, and pass through each region of the pre-tropical 106, the temperature rising zone 108, the holding zone 110, and the cooling zone 114. In the pre-tropical 106, water and solvent are evaporated at about 100 ° C. In the temperate zone 108, the can body 104 is brought to a predetermined temperature. In the holding band 110, the resin is crosslinked to make the molecular structure dense, and a coating film satisfying the required performance is formed. For example, it is necessary to secure 190 ° C. × 60 sec in order to form a coating film satisfying the required performance. It is cooled from the holding zone 110 through the air seal 112 in the cooling zone 114 from a can temperature of around 200 ° C., and is conveyed to the next step.

In each region of the drying device 1, nozzle bodies 10 are provided at predetermined positions above the can body 104 placed upright on the conveyor net 102. The nozzle body 10 includes a nozzle 11 that discharges gas in parallel with the vertical direction of the can body 104. As used herein, the term "parallel" is not limited to a state of being perfectly parallel, but includes a state of being slightly tilted from a state of being perfectly parallel.

Although not shown, the drying device 1 takes in outside air as a gas for drying the can body 104, and circulates hot air heated to about 100 ° C. to 255 ° C. by a circulation fan. The hot air is blown out from the upper blowing nozzle 118 and passes through the punching plate 120 immediately after the blowing nozzle 118 and the punching plate 122 immediately before the nozzle 11 in order to disperse and equalize the pressure over the entire region. In this way, hot air having a uniform flow velocity is blown out from the nozzle 11. 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 collision jet.

As shown in FIG. 2, the nozzle body 10 is provided with nozzles 11 at predetermined intervals. The nozzle 11 includes a pair of nozzle walls 12, 14 arranged so as to face each other with a predetermined interval (for example, 3 to 7 mm). In FIG. 2, the transport direction is the x direction, the width direction of the conveyor net 102 as the transport unit is the y direction, and the direction perpendicular to the surface of the conveyor net is the z direction.

The nozzle 11 has a flow path that guides hot air that has passed through the punching plate 122 (FIG. 1) in one direction. The flow path has a slit shape formed between the nozzle walls 12 and 14. One direction is the discharge direction of hot air. In the case of FIG. 2, one direction is the arrow direction (z direction) in the figure, which is a direction parallel to the central axis of the vertically placed bottomed cylindrical can body 104. The length of the nozzle 11 in one direction can be appropriately selected.

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

The tip of the nozzle 11 is provided with a discharge port 15 which is an outlet for hot air, which 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 in a direction orthogonal to the transport direction in the longitudinal direction of the discharge port 15, that is, parallel to the width direction of the conveyor net 102. 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 immediately before the discharge port 15. In the case of FIG. 2, the flow path and the discharge port 15 have a rectangular shape when viewed from one direction. The dry gas discharged from the nozzle 11 has a predetermined Re number, for example, about 2000 (12 to 16 m / sec at the discharge port). As described above, in drying the can, a so-called collision jet is adopted in which the hot air discharged from the nozzle 11 is blown into the can body 104.

The tip side of the nozzle walls 12 and 14, in the case of FIG. 2, the tips 16 and 18 have a plurality of protrusions 20 protruding toward the nozzle walls 12 and 14 of each other. The protrusions 20 are comb-shaped and are formed in plurality along the longitudinal direction of the discharge port 15. The protrusion 20 shown in FIG. 2 has a quadrangular shape when viewed from one direction. A recess 22 is formed between the protrusions 20. The recess 22 has a quadrangular shape like the protrusion 20.

In the case of FIG. 2, the protrusion 20 and the recess 22 formed on the nozzle wall 12 are formed at the same positions as the protrusion 20 and the recess 22 formed on the nozzle wall 14, but the present invention is not limited to this. For example, the protrusion 20 and the recess 22 formed on the nozzle wall 12 may be displaced in the longitudinal direction of the discharge port 15 with respect to the protrusion 20 and the recess 22 formed on the nozzle wall 14, and are formed on the nozzle wall 12. The recess 22 of the nozzle wall 14 may be formed at a position corresponding to the protrusion 20.

The protrusion 20 formed on the nozzle wall 12 is formed at a right angle to the nozzle wall 12, but the present invention is not limited to this, and the protrusion 20 may be tilted to the outlet side with respect to the discharge port 15. You may have fallen to the entrance side.

The size and spacing of the protrusions 20 can be selected according to the Reynolds number of hot air (hereinafter referred to as the Re number). When the Re number is 1000 to 10000, the ratio of the area of the protrusion 20 to the area of the gap (recess 22) between the protrusions 20 is preferably in the range of 1: 3 to 2: 1. When the Re number is 1000 to 10000 and the ratio of the area of the protrusion 20 to the area of the gap (recess 22) between the protrusions 20 is within the above range, the straightness of the hot air passing through the discharge port 15 is improved. can do.

When the Re number of hot air is 1000 to 4000, since the flow velocity of hot air is low, there is no risk of overthrowing the can body 104, which is more preferable.

The nozzle discharge port 15A shown in FIG. 3A is an example (first example) in which the ratio of the area of the protrusion 20A to the area of the recess 22A between the protrusions 20A is 1: 3. The nozzle discharge port 15B shown in FIG. 3B is an example (second example) in which the ratio of the area of the protrusion 20B to the area of the recess 22B between the protrusions 20B is 1: 1. The nozzle discharge port 15C shown in FIG. 3C is an example (third example) in which the ratio of the area of the protrusion 20C to the area of the recess 22C between the protrusions 20C is 2: 1. The width and length L of the discharge port 15 is shorter than the radius of the can body 104.

The flow velocity of the hot air discharged from the discharge port 15 gradually decreases. The length of the region where the flow velocity of the discharge port is maintained is called the potential core length XP. In the range of Re number of 1000 to 2000, the discharge ports 15A and 15B of the nozzles of the first and second examples have a longer potential core length XP than that of the third example. In the range of Re number of 3000 to 10000, the discharge port 15A of the nozzle of the first example has a potential core length XP longer than that of the second and third examples.

As shown in FIG. 4, the hot air that has passed through the nozzle 11 as described above passes through the recess 22 between the protrusions 20 to form a vertical vortex having an axis in one direction, thereby increasing the straightness. .. The drying device 1 provided with the nozzle 11 can discharge hot air having improved straightness from the discharge port 15. The hot air discharged from the discharge port 15 has a curtain shape extending in the width direction of the conveyor net 102. The hot air travels straight in one direction and easily enters the inside of the can body 104 conveyed on the conveyor net 102. Therefore, the drying device 1 can efficiently dry the inner surface of the can body 104. That is, the drying device 1 can suppress energy consumption.

Since the conventional nozzle body 116 (FIG. 16) does not have a protrusion, it becomes a lateral vortex centered on a direction parallel to the longitudinal direction of the discharge port, and hot air tends to spread in the lateral direction of the discharge port.

When the Re number is 1000 to 10000, by appropriately selecting the area of the protrusion 20 with respect to the area of the recess 22, it is possible to more efficiently generate a vertical vortex in the hot air and improve the straightness of the hot air. The Re number can vary depending on the temperature of the hot air discharged. Therefore, in the drying device 1 having a plurality of regions having different drying temperatures, it is effective to appropriately select the area of the protrusion 20 with respect to the area of the recess 22 for each region in order to efficiently dry the inner surface of the can body 104. Is.

When the Re number is larger in the range of 1000 to 3000, it is preferable that the area of the protrusion 20 with respect to the area of the recess 22 is smaller because the flow velocity decreases slowly. On the other hand, when the Re number is smaller in the above range, it is preferable that the area of the protrusion 20 is larger than the area of the recess 22 because the flow velocity decreases slowly.

When the Re number is 1000 or more, the amount of hot air is large and the drying efficiency is good, and when it is 10,000 or less, the flow velocity is preferable from the viewpoint of preventing the can body 104 from tipping over.

In the case of the above embodiment, the case where the protrusion 20 has a quadrangular shape has been described, but the present invention is not limited to this, and as shown in FIG. 5, it may have a triangular shape. When the ratio of the area of the triangular protrusion to the area of the recess is in the range of 1: 1 to 1: 3, it is preferable because better straightness of hot air can be obtained as compared with a conventional nozzle having no protrusion. The nozzle discharge port 30A shown in FIG. 5A is a 1: 1 example (modification example (1)). The recess 26A of the discharge port 30A has the same triangular shape as the protrusion 24A. The nozzle discharge port 30B shown in FIG. 5B is an example (modification example (2)) in which the above ratio is 1: 3. The recess 26B of the discharge port 30B has a trapezoidal shape. Even when the protrusions are triangular, the nozzle can generate a vertical vortex in the hot air passing through the gaps between the protrusions, so that the same effect as that of the above embodiment can be obtained.

In the case of the above embodiment, the case where the nozzle 11 is arranged in the longitudinal direction of the discharge port 15 in parallel with the width direction of the conveyor net 102 has been described, but the present invention is not limited to this. The nozzle 11 may be arranged at a position where the longitudinal direction of the discharge port 15 is parallel to the transport direction, that is, parallel to the longitudinal direction of the conveyor net 102, and is deviated from the center of the can body 104 in the width direction of the conveyor net 102. By arranging 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 can be efficiently supplied along the can body surface. Reach the bottom. Therefore, the can body 104 is efficiently dried because the whole body is heated by the hot air in contact with the can body 104. In particular, when the can body 104 is made of aluminum, the heat transfer coefficient is high, so that the can body 104 is dried more efficiently.

In the case of the above embodiment, the case where the tips 16 and 18 of the nozzle walls 12 and 14 have a plurality of protrusions 20 has been described, but the present invention is not limited to this. The protrusion 20 may be formed at a position deviated toward the inlet of the discharge port 15 within a range that does not significantly reduce the straightness of hot air due to pressure loss.

The result of actually verifying the straightness of the hot air in the nozzle body 10 according to the above embodiment will be described below. First, the first example (FIG. 3A, rectangular tab A, H: 2 mm, W: 0.75 mm, D: 2.25 mm), the second example (FIG. 3B, rectangular tab B, H: 2 mm, W: 1.5 mm). , D: 3.0 mm), the third example (Fig. 3C, rectangular tab C, H: 2 mm, W: 3.0 mm, D: 4.5 mm), and the modified example (2) (Fig. 5B, triangular tab B). , H: 2 mm, W: 2 mm, D: 4 mm) nozzles were prepared. The length of the discharge port in the longitudinal direction was set to 300 mm. As a comparative example, a slit nozzle (without tabs) having no protrusion was prepared. Let the height H of the protrusions, the width W of the protrusions, and the arrangement pitch of the protrusions be D. The length of the discharge port in the lateral direction (nozzle height) in the comparative example was used as the reference nozzle height (equivalent nozzle height He), and the nozzle height was adjusted so that the flow rate was constant in each example. .. In this embodiment, the equivalent nozzle height He is set to 5 mm. A predetermined Re number of gas was supplied from the blowing nozzle to the inlet of the nozzle via the punching plate. The working fluid was room temperature air. The Re number of the working fluid was adjusted by changing the flow velocity of the fluid in the range of 3 to 30 m / s.

The velocity distribution of the discharged gas was measured by the particle image velocimetry method. Specifically, a CCD camera was used to photograph the flow of air discharged from the nozzles in the xy plane and the xx plane shown in FIG. An oil mist (average particle size 1 μm, specific gravity s≈1.05) was used as a tracer, and an Nd: YAG laser (maximum output 200 mJ) was used as a light source. The results are shown in FIGS. 7 to 15.

7 and 8 are the results when the Re number is 1000. In FIG. 7, the horizontal axis is the ratio of the distance x from the discharge port to the equivalent nozzle height He (x / He), and the vertical axis is the ratio wind speed when the flow velocity at the discharge port is U0 and the flow velocity at x / He is uc. (Uc / U0) is shown. The potential core length XP is set to a region where 95% of the flow velocity of the discharge port is maintained in this embodiment. The potential core length XP of the nozzles of the first example and the second example was the longest, about 10. It was confirmed that the nozzles of the first to third examples all had less decrease in flow velocity than the nozzles of the comparative example, and the third example (rectangular tab C) had the least decrease in flow velocity. From the visualized image shown in FIG. 8, in the third example (rectangular tab C), since a striped pattern is seen even at a point where x / He is 15, a vertical vortex is generated instead of a horizontal vortex, and the straightness is not good. It was confirmed that it was improving. This result is consistent with the flow velocity result in FIG. On the other hand, in the comparative example (without tabs), a large lateral vortex is generated at a point where x / He is 15, and it is considered that the generation of the lateral vortex is the cause of the decrease in the flow velocity.

FIG. 9 shows the result when the Re number is 2000. The horizontal axis and the vertical axis of FIG. 9 are the same as those of FIG. 7. The potential core length XP of the nozzles of the first example and the second example was the longest, about 11. On the other hand, the potential core length XP of the comparative example was about 8. It was confirmed that the nozzles of the first to third examples all had less decrease in flow velocity than the nozzles of the comparative example, and the first and second examples (rectangular tabs A and B) had less decrease in flow velocity. .. In the comparative example (without tabs), even when the Re number was 2000, the decrease in the flow velocity was large as compared with the first to third examples.

10 and 11 are the results when the Re number is 3000. The horizontal axis and the vertical axis of FIG. 10 are the same as those of FIG. 7. The potential core length XP of the nozzle of the first example was the longest, about 10. It was confirmed that the nozzles of the first to third examples all had less decrease in flow velocity than the nozzles of the comparative example, and the first example (rectangular tab A) had the least decrease in flow velocity. From the visualized image shown in FIG. 11, it was confirmed that in the first example (rectangular tab A), no lateral vortex was generated even at the point where x / He was 10, and the straightness was improved. This result is consistent with the flow velocity result in FIG.

12 and 13 are the results when the Reynolds number is 10000. The horizontal axis and the vertical axis of FIG. 12 are the same as those of FIG. 7. The potential core length XP of the nozzle of the first example was the longest, about 7. On the other hand, the potential core length XP of the comparative example was about 3. From FIG. 12, it was confirmed that the nozzles of the first to third examples were superior to the nozzles of the comparative example in terms of flow velocity, and among them, the decrease in flow velocity of the first example (rectangular tab A) was small. .. From the visualization image shown in FIG. 13, it was confirmed that in the first example (rectangular tab A), no lateral vortex was generated even at the point where x / He was 4. This result is consistent with the flow velocity result in FIG.

14 and 15 are the results of the modified example (2) (triangle tab B) in the case of the Re number 2000. The horizontal axis and the vertical axis of FIG. 14 are the same as those of FIG. 7. The potential core length XP of the nozzle of the modified example (2) was about 11. On the other hand, the potential core length XP of the comparative example was about 8. It was confirmed that the nozzle of the modified example (2) had less decrease in the flow velocity than the nozzle of the comparative example. From the visualized image shown in FIG. 15, it was confirmed that in the modified example (2), no lateral vortex was generated even at the point where x / He was 11, and the straightness was improved. This result is consistent with the flow velocity result in FIG. On the other hand, in the comparative example (without tabs), a lateral vortex had already occurred at the point where x / He was 5.

As a result of the above verification, when the protrusion is square, the potential core length XP is the longest in the range of Re number 1000 to 10,000, that is, the ratio of the area of the recess 22A between the protrusions 20A. Was confirmed to be a 1: 2 outlet. It was also found that when the protrusions are triangular, a longer potential core length XP can be obtained at Reynolds 2000.

From the above, it was found that the straightness of the gas discharged from the discharge port can be improved by using the nozzle according to the present invention. Therefore, the drying device using the nozzle can easily deliver hot air to the inside of the can body, so that the can body can be dried more efficiently.

Specifically, in the case of the Re number 2000 (temperate zone 108 and holding zone 110), the nozzle of the modified example (2), that is, a triangular shape when viewed from the discharge direction, has the area of the protrusion 24A and the area of the recess 26B. It is preferable to use a nozzle having a discharge port 30B (FIG. 5B) having a ratio of 1: 3. In the case of Re number 3000 (pretropical 106), the nozzle of the first example, that is, the discharge port 15A which is square when viewed from the discharge direction and the ratio of the area of the protrusion 20A to the area of the recess 22A is 1: 2 (FIG. It is preferable to use a nozzle having 3A). As described above, by appropriately selecting the shape of the protrusion and the ratio of the area of the protrusion to the area of the recess according to the Re number, a drying device for drying the can body more efficiently can be obtained.

1 Drying device 10 Nozzle body 11 Nozzle 12, 14 Nozzle wall 15 Discharge port 20 Protrusion 22 Recess (gap)
100 drying device

The present invention relates to nozzles and drying equipment.

The present invention is directed to purpose thereof is to provide a nozzle and a drying apparatus capable of improving the linearity of the gas discharge.

Nozzle according to the present invention, an inlet of gas provided with a pair of nozzle walls which are arranged opposite formed by parallel flat plates to each other with a predetermined distance, the proximal end of the nozzle wall, said nozzle wall a slit-shaped discharge port provided at the tip of, formed between the pair of the nozzle wall, and a flow passage connecting the entering-port and the discharge port, the discharge port, another of said nozzle a plurality of projections projecting toward the wall, have a plurality of recesses formed between the said protrusions, ejecting the gases passing through a more guided the recess in the flow path from the discharge port, It is characterized in that it enters the inside of a can body formed in a bottomed tubular shape.

In the nozzle according to the present invention, the Reynolds number of the gas flowing through the flow path is preferably 1000 to 10000, and the ratio of the area of the protrusion to the area of the recess is preferably 1: 3 to 2: 1. ..

In the nozzle according to the present invention, the Reynolds number of the gas flowing through the flow path is preferably 1000 to 4000.

Drying apparatus according to the present invention includes a plurality of regions drying temperature varies, the A drying apparatus comprising a conveying unit for conveying the cup-shape formed the can body into the plurality of regions, said plurality Each of the regions of is characterized by having the nozzle.

In the drying apparatus according to the present invention, it is preferable that at least one of the shape of the protrusion and the ratio of the area of the protrusion to the area of the recess is different in the plurality of regions.

In the drying apparatus according to the present invention, the plurality of regions are provided with a pre-tropical zone, a temperate zone, and a holding zone in order from the upstream along the transport direction, and the protrusions in the pre-tropical zone are viewed from the discharge direction. It is square and the ratio of the area of the protrusion to the area of the recess is 1: 2. The protrusions in the temperate zone and the holding zone are triangular when viewed from the discharge direction, and the protrusions. The ratio of the area of the recess to the area of the recess is preferably 1: 3.

In the drying apparatus according to the present invention, the width and length of the discharge port are preferably 3 to 7 mm. stomach. It is preferable that the transport unit transports the can body in a vertically placed state.

According to the present invention, hot air having improved straightness can be discharged from a nozzle. The hot air discharged from the nozzle travels straight in one direction and can easily enter the inside of the can body. Therefore, the drying device can efficiently dry the inside of the can body .

The present invention relates to a nozzle , a drying device , and a method for manufacturing a can body.

An object of the present invention is to provide a nozzle, a drying device, and a method for manufacturing a can body, which can improve the straightness of the discharged gas.

Claims (10)

A slit-shaped discharge port is provided at the tip of a pair of nozzle walls arranged so as to face each other at a predetermined interval, and a plurality of protrusions protruding toward each other's nozzle walls are provided on the tip side of the nozzle wall. Nozzle featuring. The claim is characterized in that the Reynolds number of the gas discharged from the discharge port is 1000 to 10000, and the ratio of the area of the protrusions to the area of the gap between the protrusions is 1: 3 to 2: 1. Item 1. The nozzle according to item 1. The nozzle according to claim 1 or 2, wherein the Reynolds number of the gas discharged from the discharge port is 1000 to 4000. The nozzle according to any one of claims 1 to 3, wherein the protrusion has a quadrangular shape when viewed from the discharge direction. The nozzle according to any one of claims 1 to 3, wherein the protrusion has a triangular shape when viewed from the discharge direction. Multiple areas with different drying temperatures and
A drying device including a transport unit for transporting a can body formed in a bottomed cylinder shape into the plurality of regions.
Each of the plurality of regions
A drying device having the nozzle according to any one of claims 1 to 5. The drying apparatus according to claim 6, wherein at least one of the shape of the protrusion and the ratio of the area of the protrusion to the area of the gap between the protrusions is different in the plurality of regions. In the plurality of regions, a pre-tropical zone, a temperate zone, and a holding zone are provided in order from the upstream along the transport direction.
The protrusions in the pretropical zone are square when viewed from the discharge direction, and the ratio of the area of the protrusions to the area of the gap between the protrusions is 1: 2.
The claims in the temperate zone and the holding zone are triangular when viewed from the discharge direction, and the ratio of the area of the protrusions to the area of the gap between the protrusions is 1: 3. Item 6. The drying apparatus according to item 6. The drying apparatus according to any one of claims 6 to 8, wherein the width and length of the discharge port are shorter than the radius of the can body. A can body provided with a step of transporting a bottomed tubular can body having a coating film of a thermosetting resin coating formed on the inner surface into a plurality of regions having different drying temperatures and baking the coating film on the inner surface. It ’s a manufacturing method,
In the step of baking the coating film, a slit-shaped discharge port is directed to the tip of a pair of nozzle walls arranged so as to face each other at a predetermined interval, and the nozzle walls are directed to each other on the tip side of the pair of nozzle walls. A method for manufacturing a can body, which comprises discharging gas from a nozzle having a plurality of protruding protrusions.

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