Method for manufacturing molded products and apparatus for manufacturing molded products

Abstract

The present invention provides a method for manufacturing molded products and an apparatus for manufacturing molded products that enables uniform heating of the surface of a sheet material. [Solution] The system includes a heating step of heating a sheet material 31 containing a thermoplastic resin, and a molding step performed after the heating step of shaping the sheet material 31 into a predetermined shape. In the heating step, multiple regions A1 on the surface of the sheet material 31 are heated by multiple heaters 60, and the output of each of the multiple heaters 60 is controlled based on the temperature of each of the multiple regions A1 measured by multiple temperature sensors 61.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a method for manufacturing a molded product and an apparatus for manufacturing a molded product.

Background Art

[0002] Conventionally, as a method for manufacturing a molded product, the method described in Patent Document 1 below is known. In this Patent Document 1, as a method for manufacturing a molded product, after a sheet material (skin material) containing a thermoplastic resin is softened by heating with a heater (heating unit), a method of molding and attaching the sheet material to the surface of a base material using a vacuum molding apparatus is described.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above patent document, the surface of the sheet material is heated by a heater disposed opposite to the surface of the sheet material. In such a configuration, in the central region of the surface of the sheet material, heat is transferred from the peripheral region, so that it tends to become high temperature. In other words, in the outer region of the surface of the sheet material, it tends to become low temperature. Thus, if there is a portion where the temperature is low in the sheet material, there is a concern that the flexibility of that portion will be lower than that of the surrounding area, and the moldability will be deteriorated.

[0005] The technology disclosed in this specification has been completed based on the above circumstances, and an object thereof is to provide a method for manufacturing a molded product and an apparatus for manufacturing a molded product capable of uniformly heating the surface of a sheet material.

Means for Solving the Problems

[0006] As a means to solve the above problems, the method for manufacturing a molded article disclosed herein comprises a heating step of heating a sheet material containing a thermoplastic resin, and a molding step performed after the heating step of molding the sheet material into a predetermined shape, wherein in the heating step, a plurality of regions on the surface of the sheet material are heated by a plurality of heaters, and the output of each of the plurality of heaters is controlled based on the temperature of the plurality of regions measured by a plurality of temperature sensors.

[0007] In the heating process, heating the sheet material containing thermoplastic resin softens the sheet material, making it possible to mold the sheet material into a predetermined shape in the molding process. In the heating process, multiple temperature sensors measure the temperature of multiple areas on the surface of the sheet material, and the output of multiple heaters is controlled based on these temperatures. This allows multiple areas to be heated to the same temperature, ensuring uniform heating of the sheet material surface. If there are areas on the sheet material with low temperatures, the flexibility of those areas will be lower than the surrounding areas, potentially leading to reduced moldability in the molding process. By uniformly heating the surface of the sheet material, the sheet material can be molded more reliably in the molding process.

[0008] Furthermore, in the molding process, the sheet material can be molded to conform to the surface shape of the substrate by vacuum forming, and the sheet material can be attached to the surface of the substrate via an adhesive. When attaching the sheet material to the surface of the substrate via an adhesive, if there are areas on the sheet material that are at a low temperature, the temperature of the adhesive will not rise easily, which may result in a decrease in the adhesive strength of those areas compared to the surrounding areas. By uniformly heating the surface of the sheet material in the heating process, the sheet material can be attached to the substrate more reliably in the molding process.

[0009] Furthermore, as a means to solve the above problems, the method for manufacturing a molded article disclosed herein comprises a plurality of heaters for heating a plurality of regions on the surface of a sheet material containing a thermoplastic resin, a plurality of temperature sensors for measuring the temperature of the plurality of regions, a molding apparatus for molding the sheet material into a predetermined shape, and a control unit, wherein the control unit controls the output of each of the plurality of heaters based on the temperature of the plurality of regions measured by the plurality of temperature sensors.

[0010] By heating a sheet material containing thermoplastic resin with multiple heaters, the sheet material can be softened, allowing it to be molded into a predetermined shape by a molding device. The control unit controls the output of each of the multiple heaters based on the temperature of multiple regions measured by multiple temperature sensors. This allows multiple regions to be heated to the same temperature, ensuring uniform heating of the sheet material's surface. If there are areas of the sheet material with lower temperatures, the flexibility of those areas will decrease compared to the surrounding areas, potentially leading to reduced moldability. Uniform heating of the sheet material's surface allows for more reliable molding. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a method for manufacturing a molded article and an apparatus for manufacturing a molded article that can uniformly heat the surface of a sheet material. [Brief explanation of the drawing]

[0012] [Figure 1] Cross-sectional view showing the heating device (corresponding to the view cut along line II in Figure 2) [Figure 2] A view of the upper heating unit from above. [Figure 3] Cross-sectional view of the molding apparatus (mold open state) [Figure 4] Cross-sectional view of a molding apparatus (mold closed state) [Figure 5] A graph showing an example of heater control. [Modes for carrying out the invention]

[0013] One embodiment of the present invention will be described with reference to Figures 1 to 5. In this embodiment, a manufacturing apparatus 40 for vehicle interior materials 10 is exemplified as a manufacturing apparatus for molded products. The vehicle interior material 10 is, for example, a vehicle interior material such as a door trim, and as shown in Figure 4, comprises a base material 20 which is a plate-shaped member made of synthetic resin, and a surface material 30 which is attached to the surface of the base material 20. The surface material 30 is manufactured by molding a sheet material 31 containing a thermoplastic resin into a predetermined shape. As the thermoplastic resin contained in the sheet material 31, for example, TPO resin (thermoplastic olefin resin) can be exemplified, but is not limited to this.

[0014] The manufacturing apparatus 40 includes a heating device 50 for heating the sheet material 31, and a molding device 70 for shaping the sheet material 31 into a predetermined shape to form the surface material 30. As shown in Figure 1, the heating device 50 includes a pair of heating units 51, 51 arranged to cover both the upper and lower surfaces of the sheet material 31, a net 53 placed between the sheet material 31 and the lower heating unit 51, a control unit 54 for controlling the operation of each component of the heating device 50, and a holding unit 55 for holding the peripheral edge of the sheet material 31. The heating unit 51 includes a plurality of heaters 60 for heating a plurality of regions A1 on the surface of the sheet material 31, a plurality of temperature sensors 61 for measuring the temperature of the plurality of regions A1, and a fixing plate 62 to which the heaters 60 and temperature sensors 61 are fixed.

[0015] As shown in Figure 2, the multiple heaters 60 are arranged in a matrix. In the plan view shown in Figure 2, the temperature sensor 61 is positioned in the center of the four heaters 60 arranged in a 2x2 grid. In other words, the temperature sensor 61 is capable of measuring the temperature of region A1 on the surface (top or bottom) of the sheet material 31 that faces the four heaters 60 arranged in a 2x2 grid. The control unit 54 is electrically connected to each temperature sensor 61 and each heater 60. The control unit 54 controls the operation of the heaters 60 (four heaters 60 arranged in a 2x2 grid) that heat region A1 based on the temperature of region A1 measured by the temperature sensor 61, and this control is performed for all regions A1.

[0016] In Figure 2, the sheet material 31 (see dashed line in Figure 2) is rectangular in shape, and the upper (or lower) surface of the sheet material 31 is divided into 12 regions A1 arranged in 4 rows and 3 columns, with each region A1 being heated by four heaters 60. Of the multiple heaters 60, the group of heaters 60 located on the outermost periphery is used when heating a sheet material (not shown) that is larger than the sheet material 31 shown in Figure 2.

[0017] The heater 60 is positioned opposite the surface of the sheet material 31 at a distance from it. For example, the heater 60 can be configured to emit infrared rays or blow hot air toward the surface of the sheet material 31. The temperature sensor 61 is, for example, a radiation thermometer, which is capable of measuring the temperature of region A1 without contact.

[0018] The net 53 catches the sheet material 31 when it falls, thereby preventing the sheet material 31 from coming into contact with the lower heater 60. Because the net 53 is in place, the distance between the heater 60 in the lower heating unit 51 and the sheet material 31 is greater than the distance between the heater 60 in the upper heating unit 51 and the sheet material 31.

[0019] As shown in FIG. 3, the molding device 70 includes an upper mold 71 and a lower mold 81. The upper mold 71 and the lower mold 81 are configured to be able to close and open the mold by approaching and separating from each other by a driving device (for example, an electric motor, an air cylinder, a hydraulic cylinder, etc.) not shown in the figure. The upper mold 71 has a molding surface 72 having a concave shape, and the molding surface 72 is arranged in a downward-facing manner. The lower mold 81 has a molding surface 82 having a convex shape, and the molding surface 82 faces upward and is arranged below the upper mold 71 so as to face the molding surface 72 of the upper mold 71.

[0020] A plurality of suction holes 73 penetrating in the vertical direction are provided in the upper mold 71. A plurality of suction holes 83 penetrating in the vertical direction are provided in the lower mold 81. The base material 20 is provided with a plurality of through holes 21 penetrating in the thickness direction (front and back directions of the base material). The suction holes 73 and 83 are each connected to a vacuum suction device not shown in the figure. Thereby, the sheet material 31 can be closely adhered to the molding surface 72 without a gap by the negative pressure applied from the suction hole 73, and the skin material 30 can be closely adhered to the surface of the base material 20 without a gap through the through hole 21 by the negative pressure applied from the suction hole 83.

[0021] Next, a manufacturing method of the vehicle interior material 10 using the manufacturing device 40 will be described. The manufacturing method of the vehicle interior material 10 according to the present embodiment includes a heating step of heating the sheet material 31 by the heating device 50, and a molding step that is executed after the heating step and molds the sheet material 31 into a predetermined shape by the molding device 70.

[0022] (Heating step) In the heating process, as shown in Figure 1, multiple regions A1 on both the front and back surfaces of the sheet material 31 are heated by multiple heaters 60. The control unit 54 controls the output of each of the multiple heaters 60 based on the temperatures of the multiple regions A1 measured by multiple temperature sensors 61. Specifically, the control unit 54 acquires the temperature of each region A1 measured by the temperature sensors 61 at predetermined intervals (e.g., 1 second), and controls the output of each heater 60 that heats each region A1 so that the temperature reaches the target temperature T1 set for each region A1. For example, PID control can be used as the control method for the heaters 60.

[0023] Figure 5 shows an example of heater 60 control during the heating process. In Figure 5, the horizontal axis represents the time (S) since the start of the heating process, the left vertical axis represents the temperature (°C), and the right vertical axis represents the heater output (%). The upper surface temperature T2 in Figure 5 is the temperature of the upper surface region A1 of the sheet material 31 as measured by the temperature sensor 61, and the lower surface temperature T3 is the temperature of the lower surface region A1 of the sheet material 31 as measured by the temperature sensor 61. The upper heater output P1 in Figure 5 is the output of the heater 60 that heats the upper surface region A1 of the sheet material 31, and the lower heater output P2 in Figure 5 is the output of the heater 60 that heats the lower surface region A1 of the sheet material 31. In this embodiment, one region A1 is heated by four heaters 60, but the output of the four heaters 60 is set to the same value. As shown in Figure 5, the control unit 54 controls the output of each heater 60 so that the temperatures of the upper and lower surfaces of the sheet material 31 measured by the temperature sensor 61 in region A1 (upper surface temperature T2 and lower surface temperature T3 in Figure 5) reach a predetermined target temperature T1.

[0024] The target temperature T1 is set to approximately the same value as the ambient temperature of the sheet material 31 (air temperature T4 in Figure 5) at the start of the heating process. Thereafter, it rises proportionally with the passage of time, reaching a predetermined value (180°C in Figure 5) after a predetermined time (60 seconds in Figure 5), and is set to maintain that predetermined value. In the example shown in Figure 5, at the start of the heating process, the surface temperature of the sheet material 31 is higher than the target temperature T1. Therefore, immediately after the start of the heating process, the output of the heater 60 is 0%, and when the target temperature T1 becomes higher than the surface temperature of the sheet material 31, the output of the heater 60 is increased to heat the surface of the sheet material 31. Subsequently, the output of the heater 60 is increased or decreased to control the top surface temperature T2 and bottom surface temperature T3 so that they follow the target temperature T1.

[0025] Furthermore, the target temperature T1 is set to the same value for all regions A1 on the sheet material 31, for example. In this way, all regions A1 on the surface of the sheet material 31 can be heated to the same temperature in a predetermined time. In other words, the surface temperature of the sheet material 31 can be made uniform. Note that the target temperature T1 may be set to a different value for each region A1 on the sheet material 31. Also, although Figure 5 shows an example where the target temperature T1 is set to the same value on both sides of the sheet material 31, the target temperature T1 may be set to a different value for the top and bottom surfaces of the sheet material 31.

[0026] As described above, in this embodiment, the distance between the heater 60 in the lower heating unit 51 and the sheet material 31 is greater than the distance between the heater 60 in the upper heating unit 51 and the sheet material 31. Therefore, the output of the heater 60 in the lower heating unit 51 (lower heater output P2) is generally higher than the output of the heater 60 in the upper heating unit 51 (upper heater output P1).

[0027] (molding process) In the molding process, the sheet material 31 is formed by vacuum forming to conform to the surface shape of the base material 20, and the sheet material 31 is attached to the surface of the base material 20 via adhesive 22. Specifically, as shown in Figure 3, the sheet material 31 is pressed tightly against the molding surface 72 by negative pressure applied from the suction hole 73 of the upper mold 71. As a result, the sheet material 31 is molded to conform to the shape of the molding surface 72, becoming the surface material 30.

[0028] Subsequently, an adhesive 22 such as hot melt is applied to the surface of the base material 20 placed in the lower mold 81, and the upper mold 71 and lower mold 81 are closed as shown in Figure 4. As a result, the base material 20 and the surface material 30 are pressed together by the molding surface 72 of the upper mold 71 and the molding surface 82 of the lower mold 81. At the same time, the surface material 30 is vacuum-suctioned through the base material 20 by the suction holes 83 provided in the lower mold 81, and adheres tightly to the surface of the base material 20 to which the adhesive 22 has been applied. With the surface material 30 attached to the base material 20, the manufacturing of the vehicle interior material 10 is completed.

[0029] Next, the effects of this embodiment will be described. The manufacturing method of the vehicle interior material 10 of this embodiment comprises a heating step of heating a sheet material 31 containing a thermoplastic resin, and a molding step performed after the heating step of shaping the sheet material 31 into a predetermined shape. In the heating step, multiple regions A1 on the surface of the sheet material 31 are heated by multiple heaters 60, and the output of each of the multiple heaters 60 is controlled based on the temperature of each of the multiple regions A1 measured by multiple temperature sensors 61.

[0030] In the heating process, the sheet material 31 containing thermoplastic resin is heated, which softens the sheet material 31 and allows it to be molded into a predetermined shape in the molding process. In the heating process, multiple temperature sensors 61 measure the temperature of multiple regions A1 on the surface of the sheet material 31, and the output of multiple heaters 60 is controlled based on these temperatures. This allows multiple regions A1 to be heated to the same temperature, ensuring uniform heating of the surface of the sheet material 31. If there are areas on the sheet material 31 with low temperatures, the flexibility of those areas will decrease compared to the surrounding areas, potentially leading to reduced moldability in the molding process. By uniformly heating the surface of the sheet material 31, the sheet material 31 can be molded more reliably in the molding process.

[0031] Furthermore, in the molding process, the sheet material 31 is molded to conform to the surface shape of the base material 20 by vacuum forming, and the sheet material 31 is attached to the surface of the base material 20 via adhesive 22. When attaching the sheet material 31 to the surface of the base material 20 via adhesive 22, if there are areas on the sheet material 31 that are at a low temperature, the temperature of the adhesive 22 will not rise easily, and there is a concern that the adhesive strength in those areas will be lower than the surrounding areas. By uniformly heating the surface of the sheet material 31 in the heating process, the sheet material 31 can be attached to the base material 20 more reliably in the molding process.

[0032] Furthermore, in the heating process, as shown in Figure 5, the surface temperature of the sheet material 31 can be heated to a predetermined temperature in a predetermined time. In other words, the working time for the heating process can be kept the same regardless of fluctuations in the air temperature T4 (more specifically, the temperature inside the heating furnace in which the heating device 50 is installed). As a result, the sheet material 31 can be continuously supplied to the next process, the molding process, in the same amount of time, and the waiting time for workers in the molding process can be reduced.

[0033] Furthermore, the manufacturing apparatus 40 for the vehicle interior material 10 of this embodiment includes a plurality of heaters 60 that heat a plurality of regions A1 on the surface of a sheet material 31 containing a thermoplastic resin, a plurality of temperature sensors 61 that measure the temperature of the plurality of regions A1, a molding apparatus 70 that molds the sheet material 31 into a predetermined shape, and a control unit 54. The control unit 54 controls the output of each of the plurality of heaters 60 based on the temperature of the plurality of regions A1 measured by the plurality of temperature sensors 61.

[0034] By heating the sheet material 31 containing thermoplastic resin with multiple heaters 60, the sheet material 31 can be softened, and the molding apparatus 70 can mold the sheet material 31 into a predetermined shape. The control unit 54 controls the output of each of the multiple heaters 60 based on the temperature of multiple regions A1 measured by multiple temperature sensors 61. This allows multiple regions A1 to be heated to the same temperature, and the surface of the sheet material 31 to be heated uniformly. If there are areas in the sheet material 31 that are at a low temperature, the flexibility of those areas will be lower than the surrounding areas, which may lead to a decrease in moldability. By uniformly heating the surface of the sheet material 31, the sheet material 31 can be molded more reliably.

[0035] Furthermore, if the sheet material 31 has a pattern (such as a textured surface), if the sheet material 31 is overheated during the heating process, it may become too soft, and there is a concern that the pattern may disappear when it is pressed by the upper die 71 and lower die 81 during the molding process. In this embodiment, it is possible to suppress the situation in which the surface temperature of the sheet material 31 becomes partially high, thereby suppressing the situation in which the surface pattern disappears partially. In this embodiment, it is possible to set the target temperature T1 to different values ​​for the upper and lower surfaces of the sheet material 31. In other words, it is possible to heat the upper surface (design surface) and the lower surface of the sheet material 31 at different temperatures. For this reason, for example, by setting the heating temperature of the upper surface of the sheet material 31 (target temperature T1 in Figure 5) lower than the heating temperature of the lower surface, it is possible to more reliably suppress the situation in which the pattern formed on the upper surface of the sheet material 31 disappears.

[0036] <Other Embodiments> The technologies disclosed herein are not limited to the embodiments described above in the description and drawings, but also include, for example, the following embodiments. (1) In the above embodiment, vehicle interior materials such as door trims were given as examples of vehicle interior materials, but the invention is not limited to these. For example, vehicle interior materials may be used in vehicles other than automobiles (airplanes, ships, etc.). (2) The arrangement of the heaters 60 is not limited to those exemplified in the above embodiment and can be changed as appropriate. In addition, although the above embodiment exemplified a configuration in which one region A1 is heated by four heaters 60, the number of heaters 60 used to heat region A1 can be changed as appropriate. [Explanation of Symbols]

[0037] 10...Interior materials for vehicles (molded products), 20...Base material, 22...Adhesive, 31...Sheet material, 40...Manufacturing equipment, 54...Control unit, 60...Heater, 61...Temperature sensor, 70...Molding equipment, A1...Area

Claims

1. A heating step for heating a sheet material containing thermoplastic resin, The process includes a molding step performed after the heating step, in which the sheet material is formed into a predetermined shape, In the heating process, multiple regions on the surface of the sheet material are heated by multiple heaters. A method for manufacturing a molded product, comprising controlling the output of each of the multiple heaters based on the temperatures of the multiple regions measured by the multiple temperature sensors.

2. The method for manufacturing a molded article according to claim 1, wherein in the molding step, the sheet material is molded into a shape that conforms to the surface shape of the base material by vacuum forming, and the sheet material is attached to the surface of the base material via an adhesive.

3. Multiple heaters that heat multiple regions on the surface of a sheet material containing a thermoplastic resin, Multiple temperature sensors for measuring the temperature of each of the aforementioned multiple regions, A molding apparatus for shaping the aforementioned sheet material into a predetermined shape, It comprises a control unit and, A molded product manufacturing apparatus, wherein the control unit controls the output of each of the multiple heaters based on the temperatures of the multiple regions measured by the multiple temperature sensors.

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