Forming device for coated metal sheet and forming method thereof

Abstract

To provide a forming device for a coated metal sheet configured to manufacture, by roll forming, a formed product excellent in corrosion resistance and design.SOLUTION: A forming device for a coated metal sheet comprises: a pair of rollers which is configured for roll-forming a coated metal sheet; and a heating device which is disposed in front of the pair of rollers in a feeding direction of the coated metal sheet, and configured for heating the coated metal sheet formed by the pair of rollers.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a forming apparatus and a forming method for a coated metal sheet. [Background technology]

[0002] Lighting reflectors used in general straight-tube lighting equipment have a uniform cross-sectional shape, and are therefore manufactured by rolling and bending a long metal plate. The manufacturing method is, for example, the roll forming method shown in Patent Document 1. As for metal plate materials having a coating, painted metal plates manufactured by steel manufacturers are particularly called pre-coated metals (hereinafter referred to as PCM), and are often used as lighting reflectors. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-244320 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional roll forming described in Patent Document 1, when a coated metal sheet having a coating film is bent, the coating film may not be able to follow the bending deformation, resulting in cracks. When cracks occur in the coating film, corrosion is likely to progress from the cracked area, reducing corrosion resistance and also reducing aesthetic design. The present disclosure has been made to solve such problems, and has an object to provide a coated metal sheet forming apparatus that produces formed products having excellent corrosion resistance and design properties by roll forming. [Means for solving the problem]

[0005] The coated metal sheet forming apparatus of the present disclosure comprises a pair of rollers for roll-forming a coated metal sheet, and a heating device arranged in front of the pair of rollers in the feed direction of the coated metal sheet, for heating the coated metal sheet formed by the pair of rollers. Effect of the Invention

[0006] According to the present disclosure, since a heating device for heating the coated metal sheet is disposed before the pair of rollers, it is possible to prevent cracks in the coating film of the coated metal sheet being roll-formed, and therefore it is possible to manufacture a molded product with excellent corrosion resistance and design. [Brief description of the drawings]

[0007] [Figure 1] 1 is a perspective view showing an example of a product formed by the forming apparatus for a coated metal sheet according to the first embodiment; [Diagram 2] 1 is a schematic diagram showing a side view of a molding device for a coated metal sheet according to a first embodiment. [Diagram 3] 1 is a schematic diagram showing a coated metal sheet forming apparatus according to a first embodiment, viewed from above. [Figure 4] 1 is a schematic cross-sectional view showing a formed state of a coated metal sheet according to a first embodiment. FIG. [Diagram 5] FIG. 4 is a diagram showing temperature characteristics of paint of a coating film of the coated metal plate according to the first embodiment. [Figure 6] 1 is a schematic diagram showing an overall configuration of a method for forming a coated metal sheet according to a first embodiment. FIG. [Figure 7] FIG. 2 is a flow diagram showing a method for forming a coated metal sheet according to the first embodiment. [Figure 8A] 11 is a schematic diagram showing a side view of a partial configuration of a molding device for a coated metal sheet according to a second embodiment. FIG. [Figure 8B] 11 is a schematic diagram showing a partial configuration of a molding device for a coated metal sheet according to a second embodiment, as viewed from above. FIG. [Figure 9A] 11 is a schematic diagram showing a side view of a partial configuration of a molding device for a coated metal sheet according to a third embodiment. FIG. [Figure 9B]11 is a schematic diagram showing a partial configuration of a molding device for a coated metal sheet according to a third embodiment, as viewed from the feeding direction of the coated metal sheet. FIG. [Figure 10] FIG. 11 is a flow diagram showing a method for forming a coated metal sheet according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Embodiment 1 In the first embodiment of the present disclosure, a molded product manufactured using the present disclosure will be described taking as an example a reflector 1 for a lighting device shown in Fig. 1. The reflector 1 for a lighting device shown in Fig. 1 is often used in a straight tube type lighting device for widely illuminating the entire room in a relatively large facility such as an office, school, or store.

[0009] In a straight-tube lighting device, the reflector 1 of the lighting device has a role of accommodating a fluorescent lamp and enabling installation on a ceiling, as well as a role of concentrating light in a desired direction and spreading light, and has a fixed cross-sectional shape as shown in FIG. 1. In addition, the end faces are hemmed to prevent the worker from injuring his / her hands during installation. Here, the reflector 1 of a lighting device that is trapezoidal when viewed from the short side, so-called "inverted Mt. Fuji type", is illustrated as an example, but the present disclosure is not limited to this type and can also be applied to a straight-tube lighting device reflector with a fixed cross-sectional shape, such as a so-called "shaded type" that has a shading in the shape of a V when viewed from the short side. In the following explanation, a molded product of a painted metal plate is described as a general applicable product.

[0010] Next, a coated metal sheet forming apparatus for manufacturing the reflector 1 of the above-mentioned lighting equipment will be described with reference to Figs. 2 and 3. Fig. 2 is a schematic diagram showing a side view of the coated metal sheet forming apparatus 2 according to the first embodiment. Fig. 3 is a schematic diagram showing the coated metal sheet forming apparatus 2 according to the first embodiment as viewed from above. In Fig. 2, the roller support column at the front has been removed for ease of viewing, and in Fig. 3, the top plate 5 has been removed. In both Figs. 2 and 3, the coated metal sheet 3 that is the material to be formed is shown by diagonal hatching, and the heating device 4 is shown by vertical hatching.

[0011] The forming device 2 for the painted metal sheet 3 in this embodiment is composed of at least one roller pair 7 consisting of an upper roller 8 and a lower roller 9 for roll-forming the painted metal sheet 3, and a heating device 4 arranged in front of the roller pair 7 in the feed direction, and the painted metal sheet 3, which is made of a coating film and a metal plate material, is sandwiched between the roller pair 7 and fed out, thereby bending the painted metal sheet 3 by roll forming. The coated metal sheet 3 is made of a coating and a metal plate material as described above, and is processed by the forming device 2 according to this embodiment. The coated metal sheet 3 is made of a material that will become the reflector 1 of a lighting device, such as PCM. The material and dimensions of the coated metal sheet 3, such as length, width, and plate thickness, are not particularly limited, and an appropriate material and dimensions can be set according to the reflector 1 of a desired lighting device. Although an example in which the roller pairs 7 are arranged facing each other vertically has been shown, the arrangement direction can be selected, such as left and right, or diagonally.

[0012] The heating device 4 is for heating the coating film of the coated metal sheet 3 before bending, and is disposed before the pair of rollers 7 as viewed in the traveling direction F of the coated metal sheet 3 as described above. Preferably, the heating device 4 is disposed in accordance with the position where the coated metal sheet 3 passes through the forming portion so as to locally heat only the bending portion that becomes the forming portion of the coated metal sheet 3. In this embodiment, the heating device 4 uses, for example, a line-type halogen lamp heater, and is disposed in the vicinity of the coated metal sheet 3 that is to be formed by hanging it by a hanging device 6 from the top plate 5 of the forming device 2 for the coated metal sheet 3 as shown in Figures 2 and 3 to heat the coating film.

[0013] In the manufacture of the reflector 1 of the inverted Fuji-shaped lighting equipment, first, the end surface is hemmed, and then other bending processes are performed. In Figures 2 and 3, the hemming is performed by four pairs of rollers 7 through which the coated metal sheet 3 passes first, and the remaining four pairs perform other bending processes. Since the hemming is performed on both end surfaces of the coated metal sheet 3 that is the material to be formed, the heating devices 4 disposed in front of the four pairs of rollers 7 through which the coated metal sheet 3 passes first are disposed so as to be located directly above both end surfaces of the coated metal sheet 3 to be formed. On the other hand, since bending other than the hemming is performed at a position inside the end surface, the heating devices 4 disposed in front of the remaining four pairs of rollers 7 are disposed in a position inside the end surface to locally heat the bent portion of the coated metal sheet 3.

[0014] The set temperature of the heating device 4 is set to an appropriate temperature according to the type of resin of the coating film used in the coated metal sheet 3, as described later. The forming device 2 uses an infrared thermometer (not shown) to sense the temperature of the coating film surface in a non-contact manner and controls the output of the heating device 4 so that the bent portion of the coated metal sheet 3 is heated to a desired temperature. By heating the coated metal sheet 3, which is the material to be formed, before bending, it is possible to perform bending after improving the flexibility of the coating film. In addition, by locally heating only the bent portion, it is possible to prevent the occurrence of scratches on the coating film due to a decrease in hardness other than the bent portion. In this embodiment, a line-type halogen lamp heater is used as the heating device 4, but this is not limited thereto, and a high-frequency heating device or the like may also be used.

[0015] Here, the effect of improving the flexibility of the coating film of the coated metal sheet 3 by heating will be described with reference to Figs. 4 and 5. When the base material 31 having the coating film 32 of the coated metal sheet 3 is bent, the coating film 32 deforms to follow the deformation of the base material 31 as shown in Fig. 4, but when it cannot follow the deformation, it breaks and cracks. At this time, the coating film 32 deforms more as the bending angle becomes larger, and cracks are most likely to occur when the coating film 32 is bent 180 degrees as in hemming bending. If cracks occur in the coating film 32, the design quality is reduced, and the base material 31 is directly exposed to corrosive factors, which makes corrosion more likely to progress. Therefore, when bending the base material 31 having the coating film 32, cracks in the coating film 32 must be avoided as much as possible.

[0016] The polymer coating film 32 has a glass transition temperature Tg, at which it has the property of suddenly softening. As an example, Fig. 5 shows the results of measuring the elastic modulus E and loss tangent tan δ with respect to temperature change for a polyester coating film. The elastic modulus E here refers to the storage elastic modulus. The loss tangent tan δ is an index of viscoelasticity obtained by dividing the viscous contribution of the coating film by the elastic contribution, and the larger this is, the stronger the viscous nature is. The elastic modulus E starts to decrease at a temperature 15 to 20 degrees lower than the glass transition temperature Tg, drops sharply near the glass transition temperature Tg, and then when the temperature is 15 to 20 degrees higher than the glass transition temperature Tg, the decrease becomes gradual at temperatures above that. The decrease in the elastic modulus E near the glass transition temperature Tg and the peak of the loss tangent tan δ, i.e., the softening property, are utilized to obtain the effect of improving the flexibility of the coating film 32. Note that the glass transition temperature Tg is a temperature that differs depending on the paint.

[0017] The heating device 4, which is a component of the forming apparatus 2 for the coated metal sheet 3 according to this embodiment, aims to obtain the above-mentioned effects. Therefore, the forming apparatus 2 controls the temperature of the heating device 4 so that the coating film 32 of the coated metal sheet 3, which is the material to be formed, is heated from a temperature 15 to 20 degrees lower than the glass transition temperature Tg to a temperature 15 to 20 degrees higher than the glass transition temperature Tg.

[0018] As shown in Fig. 2 and Fig. 3, the roller pair 7 is composed of an upper roller 8 and a lower roller 9, and the coated metal sheet 3 to be formed is sandwiched between the upper roller 8 and the lower roller 9 and fed out, thereby bending the sheet along the shape of the gap between the upper roller 8 and the lower roller 9. Preferably, the roller pairs 7 are arranged in a line in multiple pairs in order to gradually perform the bending process rather than bending the sheet at a large angle all at once. In this case, the heating device 4 is also arranged in front of each of the roller pairs 7. By alternately arranging the heating devices 4 and the roller pairs 7 in multiple stages, the forming device 2 can continuously perform bending while maintaining the effect of improving flexibility, even when the heat of the coated metal sheet 3 to be formed is absorbed by the roller pairs 7, by heating the sheet again before the next bending process.

[0019] In the manufacturing process using the forming device 2 for the painted metal sheet 3 of this embodiment, the painted metal sheet 3 brought in by the conveyor 10 is first heated locally at the bent portion to be formed as described above, and then sent to the first pair of rollers 7, and then heated again by the next heating device 4 and transported sequentially to the next pair of rollers 7, thereby finally producing the reflector 1 for the lighting equipment.

[0020] In this way, the heating device 4 for heating the coated metal sheet 3 to be formed is disposed before the pair of rollers 7, so that it is possible to prevent cracks in the coating film of the coated metal sheet 3 being roll-formed. This makes it possible to manufacture a formed product with excellent corrosion resistance and design. Furthermore, by positioning the heating device 4 in accordance with the passing position of the bent portion that will become the shaping portion of the painted metal sheet 3 being shaped by the roller pair 7, it is possible to locally heat only the bent portion that will become the shaping portion of the painted metal sheet 3 that is the material to be shaped, thereby preventing the occurrence of scratches due to a decrease in hardness of the coating other than the bent portion.

[0021] In addition, by arranging the roller pairs 7 at multiple positions where the painted metal sheet 3 is formed in stages, the bending process in the roll forming process is carried out in stages, thereby preventing cracks that would occur if the sheet were bent all at once. In addition, the temperature of the heating device 4 is set so that the temperature of the painted metal sheet 3 during molding is 15 to 20 degrees above or below the glass transition temperature Tg of the paint of the coating film 32. As a result, the flexibility of the coating film 32 is improved by heating, which prevents the occurrence of scratches during molding of the painted metal sheet 3.

[0022] Next, a method for forming a coated metal sheet 3 using the forming apparatus 2 for the coated metal sheet 3 described above will be described with reference to Figures 6 and 7. The method for forming a coated metal sheet 3 according to this embodiment includes a press process in which a press machine cuts and processes a long coated metal sheet 3, and a roll forming process in which the forming apparatus 2 rolls the processed coated metal sheet 3, and in the roll forming process, a heating device 4 heats the coated metal sheet 3 at least either before or during roll forming.

[0023] In this embodiment, a case where a long coil material 12 of PCM is used as the coated metal sheet 3 will be described. As shown in FIG. 6, the coil material 12 unwound from the uncoiler 11 is smoothed and flattened by a leveler 13, and then conveyed to a press machine 14. In the pressing process, the coil material 12 is cut into a desired shape by the press machine 14, punched, and then sent to a forming device 2 as the coated metal sheet 3 to be formed. The forming device 2 for the coated metal sheet 3 performs roll forming of the coated metal sheet 3 as described in this embodiment. In the roll forming process, the coated metal sheet is locally heated at the bending portion by a heating device 4, and then sent to a pair of rollers 7. The coated metal sheet 3 is repeatedly heated and bent, and then processed into a desired shape, and finally a reflector 1 for a lighting device is manufactured.

[0024] The above-mentioned forming method of the painted metal sheet 3 can be illustrated in a flow diagram as shown in Figure 7. That is, the metal sheet PCM that has been painted in step S1 is pressed in a pressing process in step S2, and the processed product is roll-formed in step S3 to produce the product, the reflector 1 of the lighting equipment. In this embodiment, a long coil material 12 of PCM is used as the painted metal sheet 3, but this is not limited to this, and other pre-coated products, such as metal sheet material painted in a factory, may also be used.

[0025] Embodiment 2 The forming apparatus 2 for a coated metal sheet 3 according to the second embodiment is provided with a roller heating device 15 for heating the pair of rollers 7 performing roll forming, in addition to the heating device 4 for heating the coated metal sheet 3. As shown in Fig. 8A and Fig. 8B, a roller heating device 15 is provided for heating the vicinity of the portion where bending is performed on either the upper roller 8 or the lower roller 9, or on both. Fig. 8B is a schematic diagram seen from above with the top plate 5 of Fig. 8A removed. Note that parts corresponding to the components of the first embodiment are denoted by the same reference numerals, and detailed explanations will be omitted.

[0026] The second embodiment will be described with reference to Figures 8A and 8B. Each of the roller pairs 7 is provided with roller heaters 15 using hot air generators at positions directly above and below where the coated metal sheet 3 is bent, and the upper roller 8 and the lower roller 9 are heated by blowing hot air onto them. This allows the heat of the coated metal sheet 3 heated by the heater 4 just before the roller pair 7 to be absorbed by the roller pair 7, preventing a decrease in the temperature of the coated metal sheet 3 and a decrease in the effect of improving flexibility due to heating.

[0027] Embodiment 3 In the first embodiment, the bent portion that will become the shaping portion of the coated metal sheet 3 is locally heated by the heating device 4, but in the third embodiment, a configuration is provided in which a cooling device is used to cool the portion other than the bent portion that will become the shaping portion. Figures 9A and 9B show schematic diagrams of the partial configuration. Figure 9B is a schematic diagram of the partial configuration of Figure 9A as seen from the feed direction of the coated metal sheet 3. Note that parts corresponding to the components of the first embodiment are indicated by the same reference numerals, and detailed explanations will be omitted. The third embodiment will be described with reference to Figures 9A and 9B. A cooling device 16 using a cold air generator is attached to each of the roller pairs 7 at a position directly above or below a portion that does not contact the bent portion that will become the forming portion of the coated metal sheet 3, and cold air is blown onto other portions of the coated metal sheet 3 except for the forming portion, thereby cooling the coated metal sheet 3 except for the bent portion. This improves local heating and makes it possible to more effectively prevent scratches on the design surface.

[0028] Embodiment 4 The forming method of the coated metal sheet 3 according to the fourth embodiment is a method different from that shown in Fig. 7, and as shown in the flow diagram of Fig. 10, a metal sheet is first processed in step S11, which is a pressing process, and the pressed metal sheet is painted in step S12. After the painted coated metal sheet 3 is produced, a roll forming process is carried out by the forming device 2 in step S13.

[0029] A method for forming the coated metal sheet 3 according to the fourth embodiment will be described in detail. The steps are the same as those in FIG. 6 described in the first embodiment up to step S11, which is the pressing step. As in the case of using PCM, the metal coil material 12 is unwound by the uncoiler 11, and the coiling tendency is straightened by the leveler 13. Then, in the pressing step, the metal coil material 12 is cut into a desired shape by the press machine 14 and punched (step S11). In the fourth embodiment, the metal sheet 3 is then conveyed to a painting step, and is painted, including the end faces, to be processed into a metal sheet material having a coating (step S12). After that, the metal sheet 3 is formed by roll forming by the forming device 2 for the coated metal sheet 3 (step S13), and finally, the reflector 1 of the lighting equipment is manufactured.

[0030] That is, the method of forming a painted metal plate 3 relating to embodiment 4 includes a pressing process in which a press machine 14 cuts and processes a long metal plate, a painting process in which a painting device paints the processed metal plate, and a roll forming process in which a roll forming device rolls the metal plate painted in the painting process into a painted metal plate 3, and is characterized in that in the roll forming process, a heating device 4, 15 heats the painted metal plate 3 at least either before or during roll forming. According to the method for forming the coated metal sheet 3 according to the fourth embodiment, by applying coating after the pressing process, it is possible to improve the end surface corrosion resistance of the cut surface of the metal sheet by the press machine 14. In addition, it is possible to reduce the material cost compared to the case where PCM is used.

[0031] In the above-described first to fourth embodiments, a reflector for a lighting device has been taken as an example for explanation; however, the present disclosure is not limited to reflectors for lighting devices and can be generally applied to the molding of metal plate materials having a coating film.

[0032] Although various exemplary embodiments and examples are described in this disclosure, various features, aspects, and functions described in one or more embodiments are not limited to the application of a specific embodiment, but can be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are expected within the scope of the technology disclosed in this specification. For example, the modification, addition, or omission of at least one component, and the extraction and combination of at least one component with components of other embodiments are included. [Explanation of symbols]

[0033] 1 Lighting equipment reflector, 2 Molding device, 3 Painted metal plate, 31 Base material, 32 Coating film, 4 Heating device, 5 Top plate, 6 Lifting device, 7 Roller pair, 8 Upper roller, 9 Lower roller, 10 Conveyor, 11 Uncoiler, 12 Coil material, 13 Leveller, 14 Press machine, 15 Roller heating device, 16 Cooling device.

Claims

1. A pair of rollers for roll forming the coated metal sheet; a roller pair disposed in front of the roller pair in a feed direction of the coated metal sheet; a heating device for heating the coated metal sheet formed by the roller pair; A forming apparatus for a coated metal sheet comprising:

2. 2. The coated metal sheet forming apparatus according to claim 1, wherein the heating device is disposed in accordance with a position where the coated metal sheet formed by the pair of rollers passes through a forming portion of the coated metal sheet.

3. 3. The coated metal sheet forming apparatus according to claim 2, further comprising a roller heating device for heating one or both of the pair of rollers.

4. The coated metal plate forming apparatus according to claim 2, further comprising a cooling device for cooling other portions of the coated metal plate except for the forming portion of the coated metal plate heated by the heating device.

5. 5. The coated metal sheet forming apparatus according to claim 1, wherein the roller pairs are disposed at a plurality of positions where the coated metal sheet is formed in stages.

6. A pressing process in which a press machine cuts and processes long painted metal sheets; a roll forming step in which a forming device rolls the processed coated metal sheet; Including, The method for forming a coated metal sheet, wherein in the roll forming step, a heating device heats the coated metal sheet at least either before or during roll forming.

7. The method for forming a coated metal plate according to claim 6, characterized in that in the roll forming process, a heating device heats the formed portion of the coated metal plate before it is sent to a pair of rollers that form the coated metal plate, and the pair of rollers form the formed portion of the heated coated metal plate.

8. 8. The method for forming a coated metal sheet according to claim 7, wherein in the roll forming step, the coated metal sheet is heated during forming by a roller heating device provided on one or both of the rollers of the pair of rollers.

9. The method for forming a coated metal plate according to claim 7, characterized in that in the roll forming process, a cooling device cools other portions of the coated metal plate except for the formed portion of the coated metal plate that is heated by the heating device.

10. 10. The method for forming a coated metal sheet according to claim 7, wherein in the roll forming step, the coated metal sheet is formed in stages by the roller pairs respectively arranged at a plurality of positions.

11. A pressing process in which a press machine cuts and processes long metal plates; a coating process in which a coating device coats the processed metal plate; a roll forming process in which a forming device rolls the metal plate coated in the coating process into a coated metal plate; Including, The method for forming a coated metal sheet, wherein in the roll forming step, a heating device heats the coated metal sheet at least either before or during roll forming.

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