Method for producing molded body

Abstract

Provided is a method for producing a molded body, with which it is possible to improve shapability of a resin sheet.　The present disclosure provides a method for producing a molded body, the method comprising: a hanging step, a shaping start step, a welding step, and a formation step. In the hanging step, first and second resin sheet formation devices hang first and second resin sheets, respectively. In the shaping start step, shaping of the first resin sheet to a first mold is started in a state where a slide part protrudes from the first mold toward a second mold. In the welding step, the first resin sheet positioned at the tip of the slide part is welded to the second resin sheet by closing the first and second molds. In the formation step, a first wall part and an inner rib constituted by the first resin sheet and a second wall part constituted by the second resin sheet are formed by blowing air between the first and second resin sheets in a state where the slide part is housed in the first mold.

Description

Manufacturing method of molded body

[0001] The present disclosure relates to a method for producing a molded body.

[0002] Regarding the manufacturing technology of a molded product including an inner rib, a method for manufacturing a resin laminate plate is known, as described in Patent Document 1. In this method, an enclosed space is formed between a thermoplastic resin sheet and a mold cavity, and a slide core is protruded while suction is applied to the enclosed space. In this state, the resin sheet is shaped in the mold to protrude a portion of the resin sheet, and the protruding portion of the resin sheet is welded to another thermoplastic resin sheet to form the inner rib.

[0003] JP 2011-255531 Public Relations

[0004] In the above method, the slide core extends in a direction perpendicular to the hanging direction of the resin sheet. It is said that when the resin sheet is shaped in a mold with the slide core protruding, the resin sheet is shaped above and below the slide core. However, the resin sheet may sag due to the action of gravity, making it difficult to shape the resin sheet below the slide core. This problem is particularly noticeable when the resin sheet is thick.

[0005] The present disclosure has been made in view of the above circumstances, and provides a method for producing a molded body that can improve the shapeability of a resin sheet.

[0006] According to the present disclosure, the following inventions are provided: [1] A method for manufacturing a molded body using a molding device, the molded body including a first wall portion, a second wall portion disposed at an interval from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion to each other, the molding device including a first resin sheet forming device, a second resin sheet forming device, and a mold unit, the first and second resin sheet forming devices respectively suspending first and second resin sheets in a suspending direction, the mold unit including first and second molds configured to be openable and closable in an opening and closing direction, the first mold including a slide portion that can advance and retreat relative to the second mold, the longitudinal direction of the slide portion forming an angle of 0 to 30 degrees with respect to the suspending direction, the method including a suspending step, a shaping start step, a welding step, and a forming step. [2] The method according to [1], wherein in the drooping step, the first and second resin sheet forming devices droop the first and second resin sheets, respectively; in the shaping start step, shaping of the first resin sheet into the first mold is started with the slide part protruding from the first mold toward the second mold; in the welding step, the first and second molds are closed to weld the first resin sheet located at the tip of the slide part to the second resin sheet; and in the forming step, air is blown between the first and second resin sheets with the slide part stored in the first mold, thereby forming the first wall part and the inner rib made of the first resin sheet and the second wall part made of the second resin sheet. [3] A method according to [1] or [2], wherein the slide portion includes a side surface extending in both the direction in which the slide portion extends and the opening and closing direction, and in the welding process, the first and second molds are closed before the first resin sheet comes into contact with the side surface.[4] The method according to any one of [1] to [3], wherein the sliding portion includes side surfaces extending in both the extending direction of the sliding portion and the opening / closing direction, and further comprises a storing step, wherein the storing step stores the sliding portion in the first mold after the welding step, and the storing step stores the sliding portion before the first resin sheet comes into contact with the side surfaces. [5] The method according to [4], wherein the time from closing the first and second molds in the welding step to starting to store the sliding portion in the storing step is 1.0 second or more and 1.5 seconds or less.[6] A method for manufacturing a molded body using a molding device, wherein the molded body includes a first wall portion, a second wall portion arranged at an interval from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion to each other, the molding device includes a first resin sheet forming device, a second resin sheet forming device, and a mold unit, each of the first and second resin sheet forming devices hangs a first and second resin sheet, respectively, in a hanging direction, the mold unit includes first and second molds configured to be openable and closable in an opening and closing direction, the first mold includes a slide portion that can advance and retreat with respect to the second mold, the slide portion has a length in a longitudinal direction and a width in a width direction intersecting the longitudinal direction, and the slide portion includes a pair of side surfaces that face each other in the width direction when viewed from the opening and closing direction, and the method includes a hanging process, a shaping start process, a welding process, and a forming process. and in the forming step, the first and second resin sheet forming devices respectively suspend the first and second resin sheets; in the shaping start step, shaping of the first resin sheet into the first mold is started with the slide portion protruding from the first mold toward the second mold; in the welding step, the first and second molds are closed to weld the first resin sheet located at the tip end of the slide portion to the second resin sheet; in the welding step, the first and second molds are closed before the first resin sheet comes into contact with the side surface; and in the forming step, air is blown in between the first and second resin sheets with the slide portion stored in the first mold, thereby forming the first wall portion and the inner rib formed by the first resin sheet and the second wall portion formed by the second resin sheet.[7] A method for manufacturing a molded body using a molding device, wherein the molded body includes a first wall portion, a second wall portion arranged at an interval from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion to each other, the molding device includes a first resin sheet forming device, a second resin sheet forming device, and a mold unit, each of the first and second resin sheet forming devices hangs a first and second resin sheet, respectively, in a hanging direction, the mold unit includes first and second molds configured to be openable and closable in an opening and closing direction, the first mold includes a slide portion that can advance and retreat relative to the second mold, the slide portion has a length in the longitudinal direction and a width in a width direction intersecting the longitudinal direction, and the slide portion includes a pair of side surfaces facing each other in the width direction when viewed from the opening and closing direction, the method includes a hanging process, a shaping start process, a welding process, a storing process, and a forming process, a suspending step in which the first and second resin sheet forming devices suspend the first and second resin sheets, respectively; a shaping start step in which the shaping of the first resin sheet into the first mold is started with the slide portion protruding from the first mold toward the second mold; a welding step in which the first resin sheet located at the tip of the slide portion is welded to the second resin sheet by closing the first and second molds; a storing step in which the slide portion is stored in the first mold after the welding step and before the first resin sheet contacts the side surface; and a forming step in which air is blown in between the first and second resin sheets with the slide portion stored in the first mold, thereby forming the first wall portion and the inner rib formed by the first resin sheet and the second wall portion formed by the second resin sheet.

[0007] In the manufacturing method of the molded body of the present disclosure, the angle of the longitudinal direction of the slide portion with respect to the hanging direction is 0 to 30 degrees. This makes it less likely for the resin sheet to sag than when the longitudinal direction of the slide portion intersects with the hanging direction at an angle greater than 30 degrees. Therefore, the formability of the resin sheet can be improved.

[0008] FIG. 6 is a schematic perspective view of a molded body 10. FIG. 6 is a schematic diagram of a molding apparatus 1 according to one embodiment. FIG. 6 is a schematic cross-sectional view of the mold unit 4 shown in FIG. 1. FIG. 4A is a schematic front view of the mold 4a shown in FIG. 3, and FIG. 4B is a cross-sectional view taken along line B-B in FIG. 4A. FIG. 6 is a schematic diagram showing one step of a method for manufacturing a molded body 10 according to an embodiment of the present disclosure. FIG. 6 is a schematic diagram showing a step subsequent to the step shown in FIG. 5. The viewpoint in FIG. 6 is the same as the viewpoint in FIG. 4B. The same is true for FIGS. 7 to 9. FIG. 6 is a schematic diagram showing a step subsequent to the step shown in FIG. 6. FIG. 7 is a schematic diagram showing a step subsequent to the step shown in FIG. 8.

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an invention independently. Furthermore, elements in the following embodiments that are not defined in the claims are optional elements and can be omitted. Any number of "0"s (e.g., one or two) may be added to the end of numerical values ​​disclosed in the following description. For example, one or two "0"s may be added after "1.4" to make it "1.40" or "1.400."

[0010] [1. Molded Body 10] A molded body 10 manufactured by a molding apparatus 1 will be described using Figure 1. The molded body 10 is a component used in furniture such as a bed. The molded body 10 has a length in a longitudinal direction E1 and a thickness in a thickness direction E2 that intersects (e.g., is perpendicular to) the longitudinal direction E1. The molded body 10 also has a width in a width direction E3 that intersects (e.g., is perpendicular to) both the longitudinal direction E1 and the thickness direction E2. The molded body 10 includes walls 10a and 10b (first wall and second wall) and an inner rib 10c.

[0011] 1, a boundary line is shown between the walls 10a and 10b, but in reality, the walls 10a and 10b are welded together, and the boundary line may not be discernible from the outside. The same applies to the boundary line shown on the inner rib 10c.

[0012] The walls 10a and 10b are spaced apart from each other and overlap each other in the thickness direction E2. Both ends of the wall 10a in the longitudinal direction E1 are welded to both ends of the wall 10b in the longitudinal direction E1.

[0013] The thickness of the walls 10a, 10b is, for example, 1 mm to 10 mm, preferably 3 mm to 6 mm, and specifically, for example, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0 mm, or may be within a range between any two of the values ​​exemplified here.

[0014] The inner rib 10c functions to improve the strength of the molded body 10 in the thickness direction E2. The inner rib 10c is a portion that connects the wall portions 10a and 10b to each other. The inner rib 10c extends in the thickness direction E2. In this embodiment, the molded body 10 includes multiple (e.g., three) inner ribs 10c. The multiple inner ribs 10c are arranged at intervals in the longitudinal direction E1.

[0015] The thickness of the inner rib 10c (length in the longitudinal direction E1) is greater than the thickness of the wall portions 10a and 10b. The thickness of the inner rib 10c is, for example, twice the thickness of the wall portion 10a. The thickness of the inner rib 10c is, for example, 2 mm to 20 mm, and preferably 6 mm to 12 mm. Specific examples of the thickness of the inner rib 10c include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20 mm, and may be within a range between any two of the values ​​exemplified here.

[0016] The protruding height of the inner rib 10c (length in the thickness direction E2) is, for example, 5 mm to 30 mm, preferably 10 mm to 25 mm (15 mm in this embodiment). Specifically, the protruding height of the inner rib 10c may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 mm, or may be within a range between any two of the values ​​exemplified here.

[0017] For example, when the molded body 10 needs to support the weight of a person, a certain level of strength is required for the molded body 10. For this reason, it is desirable that the walls 10a, 10b and inner rib 10c constituting the molded body 10 are made of a sheet-like, thick resin member.

[0018] [2. Molding Apparatus 1] A molding apparatus 1 according to one embodiment will be described using Figures 2 to 4. The molding apparatus 1 manufactures a molded body 10. The molding apparatus 1 manufactures the molded body 10, for example, by blow molding a resin sheet 5 (described later). As shown in Figure 2, the molding apparatus 1 includes a pair of resin sheet forming apparatuses 2 (a first resin sheet forming apparatus and a second resin sheet forming apparatus), a pair of roller units 3, and a mold unit 4. Hereinafter, when it is necessary to distinguish between the pair of resin sheet forming apparatuses 2, the suffixes A and B are added, such as 2A and 2B, to the reference numerals. The same applies to the roller unit 3 and the resin sheet 5.

[0019] [2-1. Resin sheet forming apparatus 2] The resin sheet forming apparatus 2 hangs the resin sheet 5 in a hanging direction D1. The resin sheet forming apparatus 2 hangs the resin sheet 5 in a molten state. The hanging direction D1 is, for example, the vertical direction (the direction in which gravity acts). The resin sheet forming apparatus 2 is configured to extrude the resin sheet 5. The resin sheet forming apparatus 2 includes, for example, a hopper 2a, an extruder 2b, an accumulator 2c, and a T-die 2d.

[0020] The hopper 2a feeds the raw material resin R into the extruder 2b. The form of the raw material resin R is not particularly limited, but for example, it is in the form of pellets. The raw material resin R is, for example, a thermoplastic resin such as polyolefin. Examples of polyolefins include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, ethylene-propylene copolymer, and mixtures thereof.

[0021] The extruder 2b extrudes the raw material resin R fed from the hopper 2a into the accumulator 2c. The extruder 2b includes a cylinder 2b1. The cylinder 2b1 heats the raw material resin R fed from the hopper 2a to form a molten resin R1. The cylinder 2b1 includes a screw (not shown) disposed therein. The screw conveys the molten resin R1 toward the tip of the cylinder 2b1 while kneading it.

[0022] The accumulator 2c stores the molten resin R1 extruded from the extruder 2b. The accumulator 2c sends the stored molten resin R1 to the T-die 2d. The accumulator 2c includes a cylinder 2c1 and a piston 2c2 that is slidable inside the cylinder 2c1. The cylinder 2c1 stores the molten resin R1 extruded from the extruder 2b. The piston 2c2 slides toward the T-die 2d, thereby sending a predetermined amount of the molten resin R1 stored in the cylinder 2c1 to the T-die 2d.

[0023] The T-die 2d allows the molten resin R1 sent from the accumulator 2c to drip down. The T-die 2d includes a slit (not shown) formed therein. The T-die 2d extrudes the molten resin R1 through the slit and allows it to drip down, thereby forming a resin sheet 5.

[0024] The length of the resin sheet 5 (length in the hanging direction D1) is, for example, 1000 mm to 4000 mm, preferably, for example, 2000 mm to 3000 mm. Specifically, the length of the resin sheet 5 is, for example, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800, 3000, 3200, 3400, 3600, 3800, or 4000 mm, and may be within a range between any two of the values ​​exemplified here.

[0025] The width of the resin sheet 5 (the length in the orthogonal direction D3 described later) is, for example, 500 mm to 2000 mm, preferably 800 mm to 1500 mm. Specifically, the width of the resin sheet 5 may be, for example, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, or 2000 mm, or may be within a range between any two of the values ​​exemplified here.

[0026] The thickness of the resin sheet 5 (the length in the opening / closing direction D2, which will be described later) is, for example, 1 mm to 10 mm, preferably 3 mm to 6 mm. Specifically, the thickness of the resin sheet 5 is, for example, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, or 10.0 mm, and may be within a range between any two of the values ​​exemplified here.

[0027] In this embodiment, the thickness of the resin sheet 5 is set to 3.0 mm or more so that the wall portions 10a, 10b and the inner rib 10c constituting the molded body 10 are made of thick resin members. Here, for example, if the slide portion extends in the orthogonal direction D3, when the resin sheet 5 is shaped into the slide portion as described below, the resin sheet 5 may sag due to the action of gravity, making it difficult for the resin sheet 5 to shape below the slide portion. This problem is particularly pronounced when the resin sheet 5 is thick (for example, when the thickness of the resin sheet 5 is 3.0 mm or more), as in this embodiment. Therefore, the technical significance of applying the present disclosure is particularly pronounced when the thickness of the resin sheet 5 is 3.0 mm or more.

[0028] [2-2. Roller unit 3] The roller unit 3 is disposed between the resin sheet forming device 2 and the mold unit 4. The roller unit 3 includes rollers 3a and 3b. The rollers 3a and 3b rotate in opposite directions with the resin sheet 5 sandwiched between them to feed the resin sheet 5 downward from the roller unit 3. The roller unit 3 may be configured so that the gap between the rollers 3a and 3b is variable. In this case, the resin sheet 5 can be sandwiched between the rollers 3a and 3b by placing the resin sheet 5 between the rollers 3a and 3b with the gap widened and then narrowing the gap. The roller 3a may be a fixed roller whose position is fixed, and the roller 3b may be a movable roller whose distance from the roller 3a is variable.

[0029] 3, the mold unit 4 includes molds 4a and 4b (first and second molds) and mold forms 4c and 4d (first and second mold forms). The molds 4a and 4b are configured to be openable and closable in an opening / closing direction D2. The opening / closing direction D2 is, for example, a direction intersecting (for example, perpendicular to) the hanging direction D1.

[0030] The mold 4a includes a shaping surface 4a1 that shapes the resin sheet 5, and a pinch-off surface 4a2 that is configured to surround the shaping surface 4a1. The pinch-off surface 4a2 is located closer to the mold 4b than the shaping surface 4a1.

[0031] The mold 4a includes a slide portion 4a3. The slide portion 4a3 is movable forward and backward relative to the mold 4b. Specifically, the slide portion 4a3 is capable of protruding from the mold 4a toward the mold 4b. The slide portion 4a3 is capable of being retracted into the mold 4a in a direction away from the mold 4b. The slide portion 4a3 may include a coating layer that is easily slidable relative to the resin sheet 5. An example of a material for the coating layer is a fluororesin. The slide portion 4a3 will be described in detail below.

[0032] The mold 4b includes a shaping surface 4b1 that shapes the resin sheet 5, and a pinch-off surface 4b2 that is configured to surround the shaping surface 4b1. The pinch-off surface 4b2 is located closer to the mold 4a than the shaping surface 4b1.

[0033] When the molds 4a and 4b are closed, the pinch-off surface 4b2 contacts the pinch-off surface 4a2. When the molds 4a and 4b are closed, a molding area for molding the molded body 10 is formed between the shaping surfaces 4a1 and 4b1.

[0034] The mold 4c is arranged around the metal mold 4a. The mold 4c includes an adsorption surface 4c1 that can adsorb the resin sheet 5A. The adsorption surface 4c1 moves forward toward the resin sheet 5A and then adsorbs the resin sheet 5A. After adsorbing the resin sheet 5A, the mold 4c moves backward relative to the metal mold 4a (i.e., the mold 4c moves backward and / or the metal mold 4a moves forward). In this way, the mold 4c is configured to press the resin sheet 5A against the metal mold 4a.

[0035] The formwork 4d is arranged around the metal mold 4b. The formwork 4d includes an adsorption surface 4d1 that can adsorb the resin sheet 5B. The formwork 4d moves forward toward the resin sheet 5B and then adsorbs the resin sheet 5B. The adsorption surface 4d1 moves backward relative to the metal mold 4b after adsorbing the resin sheet 5B (i.e., the formwork 4d moves backward and / or the metal mold 4b moves forward). In this way, the formwork 4d is configured to press the resin sheet 5B against the metal mold 4b.

[0036] The mold 4a will be described in more detail using Fig. 4. The viewpoint in Fig. 4 is different from that in Fig. 3. Fig. 4A is a view of the mold 4a as seen along the opening / closing direction D2, and Fig. 4B is a cross-sectional view of the mold 4a in a cross section perpendicular to the hanging direction D1.

[0037] As shown in FIG. 4A , the mold 4a has a rectangular shape in a plan view. The shape of the mold 4a is not particularly limited and may be selected depending on the shape of the molded body 10 to be manufactured. The mold 4a includes a plurality of (e.g., three) slide portions 4a3. The plurality of slide portions 4a3 are arranged in the orthogonal direction D3. The orthogonal direction D3 is, for example, a direction orthogonal to both the hanging direction D1 and the opening / closing direction D2. In this embodiment, the plurality of slide portions 4a3 can be protruded and retracted independently of each other.

[0038] The sliding portion 4a3 is located inside the pinch-off surface 4a2 in a plan view. The sliding portion 4a3 has a length in the longitudinal direction. In this embodiment, the longitudinal direction coincides with the hanging direction D1. The length A1 (length in the longitudinal direction) of the sliding portion 4a3 is, for example, 3 cm to 30 cm, and preferably 5 cm to 15 cm (10 cm in this embodiment). Specifically, the length A1 may be, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 cm, and may be within a range between any two of the values ​​exemplified here.

[0039] Note that the sliding portion 4a3 does not need to extend strictly in the vertical direction D1. The longitudinal direction of the sliding portion 4a3 forms an angle with respect to the vertical direction D1 of 0 to 30 degrees, preferably 0 to 10 degrees (0 degree in this embodiment). Specific examples of the angle include 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, and 30 degrees, and may be within a range between any two of the values ​​exemplified here.

[0040] The slide portion 4a3 has a width in a width direction intersecting (e.g., perpendicular to) the longitudinal direction. In this embodiment, the width direction coincides with the perpendicular direction D3. The thickness A2 (length in the width direction) of the slide portion 4a3 is, for example, 2.0 mm to 12.0 mm, preferably 3.0 mm to 7.0 mm (5 mm in this embodiment). Specifically, the thickness A2 may be, for example, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, or 12.0 mm, or may be within a range between any two of the values ​​exemplified here. The thickness A2 may be selected depending on the thickness of the inner rib 10c to be formed.

[0041] The value obtained by dividing the thickness A2 by the length A1 (i.e., the value of A2 / A1) is, for example, 0.006 to 0.40, and preferably 0.02 to 0.14 (0.05 in this embodiment).Specific examples of the value of A2 / A1 include 0.006, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, and 0.40, and may be within a range between any two of the values ​​exemplified here.

[0042] The slide portion 4a3 includes a pair of side surfaces 4a31 and a tip surface 4a32 connecting the pair of side surfaces 4a31. The pair of side surfaces 4a31 face each other in the width direction (e.g., the orthogonal direction D3) when viewed from the opening / closing direction D2. As shown in Fig. 4B, when the slide portion 4a3 is housed in the mold 4a, the tip surface 4a32 is flush with the shaping surface 4a1.

[0043] The slide portion 4a3 is stored in the storage portion 4a4 of the mold 4a when it is retracted relative to the mold 4b (see FIG. 3). The slide portion 4a3 is slidable within the storage portion 4a4 in the opening / closing direction D2. The protruding height A3 of the slide portion 4a3 is shorter than the distance from the shaping surface 4a1 to the shaping surface 4b1 (see FIG. 3) when the molds 4a and 4b are closed. The protruding height A3 refers to the distance from the shaping surface 4a1 to the tip surface 4a32 when the slide portion 4a3 is moved most forward relative to the mold 4b.

[0044] The protrusion height A3 is, for example, 5 mm to 30 mm, preferably 10 mm to 25 mm (20 mm in this embodiment). Specifically, the protrusion height A3 may be, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 mm, and may be within a range between any two of the values ​​exemplified here.

[0045] The value obtained by dividing the protrusion height A3 by the length A1 (i.e., the value of A3 / A1) is, for example, 0.016 to 1.00, and preferably 0.1 to 0.5 (0.2 in this embodiment).Specific examples of the value of A3 / A1 are 0.016, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, and 1.00, and may be within a range between any two of the values ​​exemplified here.

[0046] 5 to 9, a method for manufacturing the molded body 10 using the molding device 1 will be described. This manufacturing method includes a drooping process, a pressing process, a shaping start process, a welding process, a storing process, and a forming process. Each process will be described in detail below.

[0047] 2, in the hanging process, resin sheets 5A and 5B are hung down from resin sheet forming apparatuses 2A and 2B, respectively. Specifically, resin sheet forming apparatus 2A extrudes resin sheet 5A toward roller unit 3A. After passing through roller unit 3A, resin sheet 5A is hung down between molds 4a and 4b at a position adjacent to mold 4a.

[0048] Similarly, the resin sheet forming device 2B also extrudes the resin sheet 5B toward the roller unit 3B. The resin sheet 5B that has passed through the roller unit 3B hangs down at a position adjacent to the mold 4b between the resin sheet 5A and the mold 4b.

[0049] [3-2. Pressing Process] In the pressing process, the resin sheets 5A and 5B are pressed against the molds 4a and 4b by the molds 4c and 4d, respectively. Specifically, as shown in FIG. 5, the mold 4c first advances toward the resin sheet 5A, and the suction surface 4c1 comes into contact with the resin sheet 5A. Next, the suction surface 4c1 adsorbs the resin sheet 5A. Similarly, the suction surface 4d1 adsorbs the resin sheet 5B.

[0050] In this embodiment, after the suction surfaces 4c1, 4d1 adsorb the resin sheets 5A, 5B, respectively, the slide portion 4a3 protrudes toward the mold 4b. Specifically, as the slide portion 4a3 slides within the accommodation portion 4a4, the tip surface 4a32 approaches the resin sheet 5A. When the slide portion 4a3 protrudes, the tip surface 4a32 is separated from the resin sheet 5A. Of the multiple slide portions 4a3, the slide portion 4a3 to protrude may be selected depending on the position and number of inner ribs 10c to be formed. However, the suction surfaces 4c1, 4d1 may adsorb the resin sheets 5A, 5B, respectively, after the slide portion 4a3 protrudes toward the mold 4b.

[0051] Next, the formwork 4c retreats relative to the metal mold 4b, pressing the resin sheet 5A against the metal mold 4a. As a result, the resin sheet 5A comes into contact with the formwork 4c, the pinch-off surface 4a2, and the tip surface 4a32. In this state, the resin sheet 5A is spaced apart from the shaping surface 4a1. Similarly, the formwork 4d presses the resin sheet 5B against the metal mold 4b. As a result, the resin sheet 5B comes into contact with the formwork 4d and the pinch-off surface 4b2. In this state, the resin sheet 5B is spaced apart from the shaping surface 4b1.

[0052] [3-3. Shaping Start Process] In the shaping start process, as shown in Figure 6, shaping of the resin sheet 5A into the mold 4a is started with the slide portion 4a3 protruding from the mold 4a toward the mold 4b. In this embodiment, shaping of the resin sheet 5A is started, and shaping of the resin sheet 5B into the mold 4b is started at the same time. Note that the perspectives of Figures 6 to 9 are different from the perspective in Figure 5. Figures 6 to 9 are cross-sectional views of the mold unit 4 in a cross section perpendicular to the hanging direction D1. In other words, the perspectives in Figures 6 to 9 are the same as the perspective in Figure 4B.

[0053] In the shaping start process, air begins to be sucked from the space S1 between the resin sheet 5A and the shaping surface 4a1 through suction holes (not shown) provided in the shaping surface 4a1. As a result, the resin sheet 5A begins to approach the shaping surface 4a1. Similarly, in the mold 4b, air begins to be sucked from the space between the resin sheet 5B and the shaping surface 4b1 through suction holes provided in the shaping surface 4b1. The suction pressure in the mold 4b is greater than the suction pressure in the mold 4a. As a result, the resin sheet 5B is shaped onto the shaping surface 4b1 before the resin sheet 5A is shaped onto the shaping surface 4a1.

[0054] The suction holes provided in the shaping surface 4a1 may be located at a position that is a predetermined distance or more away from the base of the slide portion 4a3. Alternatively, even if suction holes located within a predetermined distance from the base of the slide portion 4a3 are provided in the shaping surface 4a1, air does not have to be sucked through the suction holes. If the suction holes are close to the base of the slide portion 4a3, for example, the resin sheet 5A located at the base of the slide portion 4a3 may be drawn into the suction holes, causing wrinkles to form in the wall portion 10a. If the suction holes are located at a predetermined distance or more away from the base of the slide portion 4a3, the possibility of wrinkles forming in the wall portion 10a can be reduced, and the aesthetic appearance of the molded body 10 can be improved.

[0055] When the resin sheet 5A starts to be shaped into the mold 4a, the resin sheet 5A is separated from the side surface 4a31 of the slide portion 4a3. At this point, for example, the temperature of the slide portion 4a3 is lower than the temperature of the resin sheet 5A. Because the resin sheet 5A is not in contact with the side surface 4a31, a decrease in the temperature of the resin sheet 5A is suppressed.

[0056] 7, in the welding process, the molds 4a and 4b are closed to weld the resin sheet 5A located at the tip of the slide portion 4a3 to the resin sheet 5B. Even during the welding process, the resin sheet 5A continues to be shaped into the mold 4a, so the resin sheet 5A continues to be close to the shaping surface 4a1 and the side surface 4a31. In the welding process, the molds 4a and 4b are closed before the resin sheet 5A comes into contact with the side surface 4a31.

[0057] When the molds 4a, 4b are closed, the resin sheets 5A, 5B are welded to each other at the pinch-off surfaces 4a2, 4b2. As a result, thin-walled portions that are thinner than the resin sheets 5A, 5B are formed at the pinch-off surfaces 4a2, 4b2. Furthermore, both ends of the molded body 10 in the longitudinal direction E1 are formed inside the thin-walled portions. Furthermore, the resin sheets 5A, 5B are welded to each other at the tip surface 4a32 of the slide portion 4a3. Burrs B are formed on the outside of the molds 4a, 4b. The burrs B are removed in a later process.

[0058] 8, in the storing step, the slide portion 4a3 is stored in the mold 4a after the welding step. Specifically, the slide portion 4a3 slides within the accommodation portion 4a4 and retreats relative to the mold 4b. As a result, the tip surface 4a32 moves away from the resin sheet 5A while a portion of the resin sheet 5A remains welded to the resin sheet 5B. In the storing step, the slide portion 4a3 is stored before the resin sheet 5A comes into contact with the side surface 4a31.

[0059] The time from when the molds 4a and 4b are closed in the welding process to when the sliding portion 4a3 starts to be stored in the storage process (hereinafter, sometimes referred to as the "start time") is 1.0 second or more and 1.5 seconds or less. Preferably, the start time is 1.2 seconds to 1.3 seconds. Specific examples of the start time include 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, and 1.50 seconds, and may be within a range between any two of the values ​​exemplified here.

[0060] If the start time is less than 1.0 second, the resin sheets 5A and 5B may not be sufficiently welded to the tip surface 4a32 of the slide portion 4a3. In this case, defects may occur in the inner rib 10c. Specifically, the welded portions of the resin sheets 5A and 5B may become narrower. On the other hand, if the start time is longer than 1.5 seconds, the resin sheets 5A and 5B may be excessively welded, and, for example, when the slide portion 4a3 is retracted, the resin sheet 5B may be pulled by the resin sheet 5A along with the slide portion 4a3. In this case, the resin sheets 5A and 5B may become close to each other, making it difficult to ensure the thickness of the molded body 10. In this embodiment, the start time is 1.0 second or more and 1.5 seconds or less, thereby reducing the possibility of defects occurring in the inner rib 10c and ensuring a sufficient thickness of the molded body 10.

[0061] 9, in the forming process, the walls 10a, 10b and the inner rib 10c are formed by blowing air between the resin sheets 5A, 5B while the slide portion 4a3 is housed in the mold 4a. For example, a blow needle may be inserted into at least one of the resin sheets 5A, 5B, and air may be blown between the resin sheets 5A, 5B through the blow needle. The method of blowing air is not particularly limited.

[0062] In the forming process, wall portion 10a and inner rib 10c are formed from resin sheet 5A, and wall portion 10b is formed from resin sheet 5B. Specifically, wall portion 10a is formed from the portion of resin sheet 5A that is shaped on shaping surface 4a1, and wall portion 10b is formed from the portion of resin sheet 5B that is shaped on shaping surface 4b1. Furthermore, inner rib 10c is formed by welding resin sheets 5A to each other in the portion where slide portion 4a3 was located.

[0063] Subsequently, the molds 4a and 4b are opened, and then the burrs B are removed. There is no particular limitation on the method for removing the burrs B, but for example, the burrs B may be cut off using a cutter or the like. Through the above steps, the production of the molded body 10 is completed.

[0064] [4. Effects] In the above embodiment, the angle between the longitudinal direction of the slide portion 4a3 and the hanging direction D1 is 0 to 30 degrees (0 degree in the above embodiment). This makes it less likely for the resin sheet 5 to sag compared to when the longitudinal direction of the slide portion 4a3 intersects with the hanging direction D1 at an angle greater than 30 degrees. This improves the formability of the resin sheet 5.

[0065] When the resin sheet 5A is shaped into the mold 4a, the temperature of the slide portion 4a3 may be lower than the temperature of the resin sheet 5A. In this case, when the resin sheet 5A contacts the side surface 4a31, the temperature of the resin sheet 5A drops, which may cause problems in the formation of the inner rib 10c. For example, a slit (sink mark) may occur in the wall portion 10a at the position where the inner rib 10c is formed. In the above embodiment, in the welding process, the molds 4a and 4b are closed before the resin sheet 5A contacts the side surface 4a31, and the slide portion 4a3 is stored in the mold 4a. This shortens the time the resin sheet 5A contacts the side surface 4a31, or prevents the resin sheet 5A from contacting the side surface 4a31, thereby suppressing a decrease in the temperature of the resin sheet 5A. This reduces the possibility of slit formation.

[0066] In the above embodiment, the manufacturing method of the molded body 10 includes a pressing step in which the resin sheets 5A and 5B are pressed against the molds 4a and 4b, respectively, using the molds 4c and 4d before the shaping start step. Since shaping of the resin sheet 5 starts after the resin sheet 5 is pressed against the molds 4a and 4b, the shaping ability of the resin sheet 5 can be further improved.

[0067] In the above embodiment, the mold 4a includes a plurality of slide portions 4a3. Therefore, it is possible to manufacture the molded body 10 including a plurality of inner ribs 10c. When the molded body 10 includes a plurality of inner ribs 10c, the strength of the molded body 10 can be improved.

[0068] [5. Modifications] In the above embodiment, an example has been described in which the mold unit 4 includes the mold forms 4c and 4d. However, the mold unit 4 does not have to include the mold forms 4c and 4d. In this case, the pressing step may be omitted.

[0069] In the above embodiment, an example in which the start time is 1.0 second or more and 1.5 seconds or less has been described, but the start time may be less than 1.0 second or longer than 1.5 seconds. In the above embodiment, an example in which the thickness of the resin sheet 5 is 3.0 mm or more has been described, but the thickness of the resin sheet 5 may be less than 3.0 mm.

[0070] In the above embodiment, the mold 4a includes multiple slide portions 4a3. However, the mold 4a may include only one slide portion 4a3. The number of slide portions 4a3 may be selected depending on the number of inner ribs 10c to be formed. For example, the number of slide portions 4a3 is equal to or greater than the number of inner ribs 10c.

[0071] [6. Evaluation Test] 1. Example 1 A molded body 10 was manufactured by the manufacturing method described above. As the raw material resin R, a resin obtained by mixing polypropylene (VB170A (manufactured by SunAllomer Co., Ltd.)) and high-density polyethylene (BM1052 (manufactured by Savic Co., Ltd.)) in a ratio of 70:30 was used. Other manufacturing conditions were as shown in Table 1.

[0072] 2. Example 2 A molded body 10 was produced in the same manner as in Example 1, except that the starting time was set to 1.25 seconds.

[0073] 3. Example 3 A molded body 10 was produced in the same manner as in Example 1, except that the starting time was set to 1.5 seconds.

[0074] The thickness of each of the molded bodies 10 according to Examples 1 to 3 was measured. The test results are shown in Table 2.

[0075] Furthermore, each of the molded articles 10 according to Examples 1 to 3 was cut along a cross section extending in both the longitudinal direction E1 and the thickness direction E2, and the state of the inner rib 10c was observed. The test results were as shown in Table 3.

[0076] The above evaluation test confirmed that by setting the start time to 1.0 second or more and 1.5 seconds or less, the thickness of the molded body 10 can be made 16.5 cm or more, ensuring a sufficient thickness of the molded body 10. It was also confirmed that the condition of the inner rib 10c can be made good. In particular, it was confirmed that the condition of the inner rib 10c can be made good when the start time is 12.5 seconds.

[0077] 1: molding device, 2: resin sheet forming device, 2A: resin sheet forming device (first resin sheet forming device), 2B: resin sheet forming device (second resin sheet forming device), 2a: hopper, 2b: extruder, 2b1: cylinder, 2c: accumulator, 2c1: cylinder, 2c2: piston, 2d: T-die, 3: roller unit, 3A: roller unit, 3B: roller unit, 3a: roller, 3b: roller, 4: mold unit, 4a: mold (first mold), 4a1: shaping surface, 4a2: pinch-off surface, 4a3: slide portion, 4a31: side surface, 4a32: tip surface, 4a4: storage portion , 4b: mold (second mold), 4b1: shaping surface, 4b2: pinch-off surface, 4c: form (first form), 4c1: suction surface, 4d: form (second form), 4d1: suction surface, 5: resin sheet, 5A: resin sheet (first resin sheet), 5B: resin sheet (second resin sheet), 10: molded body, 10a: wall portion (first wall portion), 10b: wall portion (second wall portion), 10c: inner rib, A1: length, A2: thickness, A3: protrusion height, B: burr, D1: hanging direction, D2: opening / closing direction, D3: orthogonal direction, E1: longitudinal direction, E2: thickness direction, E3: width direction, R: raw material resin, R1: molten resin, S1: space

Claims

1. A method for manufacturing a molded body using a molding device, wherein the molded body includes a first wall portion, a second wall portion arranged at an interval from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion to each other, the molding device includes a first resin sheet forming device, a second resin sheet forming device, and a mold unit, each of the first and second resin sheet forming devices suspending the first and second resin sheets in a suspending direction, the mold unit including first and second molds configured to be openable and closable in an opening and closing direction, the first mold including a slide portion that can advance and retreat relative to the second mold, the longitudinal direction of the slide portion forming the first resin sheet at an angle of 0 to 30 degrees relative to the suspending direction, the method including a suspending step, a shaping start step, a welding step, and a forming step, wherein in the suspending step, each of the first and second resin sheet forming devices suspends the first and second resin sheets, In the shaping start process, shaping of the first resin sheet into the first mold is started with the slide portion protruding from the first mold toward the second mold; in the welding process, the first resin sheet located at the tip of the slide portion is welded to the second resin sheet by closing the first and second molds; and in the forming process, air is blown between the first and second resin sheets with the slide portion stored in the first mold, thereby forming the first wall portion and the inner rib formed by the first resin sheet and the second wall portion formed by the second resin sheet.

2. The method according to claim 1, wherein the thickness of the first and second resin sheets is 3.0 mm or more.

3. A method according to claim 1 or claim 2, wherein the slide portion includes side surfaces extending in both the direction in which the slide portion extends and the opening and closing direction, and in the welding step, the first and second molds are closed before the first resin sheet comes into contact with the side surfaces.

4. A method according to claim 1 or claim 2, wherein the slide portion includes side surfaces extending in both the direction in which the slide portion extends and the opening and closing direction, and further comprising a storing step, wherein the slide portion is stored in the first mold after the welding step, and wherein the slide portion is stored before the first resin sheet comes into contact with the side surfaces.

5. A method according to claim 4, wherein the time from closing the first and second molds in the welding step to starting to store the slide part in the storing step is 1.0 second or more and 1.5 seconds or less.

6. A method for manufacturing a molded body using a molding device, wherein the molded body includes a first wall portion, a second wall portion arranged at an interval from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion to each other, the molding device includes a first resin sheet forming device, a second resin sheet forming device, and a mold unit, each of the first and second resin sheet forming devices suspending the first and second resin sheets in a suspending direction, the mold unit including first and second molds configured to be openable and closable in an opening and closing direction, the first mold including a slide portion that can advance and retreat relative to the second mold, the slide portion having a length in the longitudinal direction and a width in a width direction intersecting the longitudinal direction, the slide portion including a pair of side surfaces opposing each other in the width direction when viewed from the opening and closing direction, the method including a suspending step, a shaping start step, a welding step, and a forming step, wherein in the suspending step, each of the first and second resin sheet forming devices suspends the first and second resin sheets, a welding step of welding the first resin sheet located at the tip of the slide portion to the second resin sheet by closing the first and second molds; a welding step of closing the first and second molds before the first resin sheet contacts the side surface; and a forming step of forming the first wall portion and the inner rib formed by the first resin sheet and the second wall portion formed by the second resin sheet by blowing air between the first and second resin sheets while the slide portion is stored in the first mold.

7. A method for manufacturing a molded body using a molding device, wherein the molded body includes a first wall portion, a second wall portion arranged at an interval from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion to each other, the molding device includes a first resin sheet forming device, a second resin sheet forming device, and a mold unit, each of the first and second resin sheet forming devices suspending the first and second resin sheets in a suspending direction, the mold unit including first and second molds configured to be openable and closable in an opening and closing direction, the first mold including a slide portion that can advance and retreat relative to the second mold, the slide portion having a length in the longitudinal direction and a width in a width direction intersecting the longitudinal direction, the slide portion including a pair of side surfaces opposing each other in the width direction when viewed from the opening and closing direction, the method including a suspending step, a shaping start step, a welding step, a storing step, and a forming step, wherein in the suspending step, each of the first and second resin sheet forming devices suspends the first and second resin sheets, a first wall portion and an inner rib formed from the first resin sheet and the second wall portion formed from the second resin sheet by blowing air between the first and second resin sheets after the welding step, the first wall portion and the inner rib formed from the first resin sheet are formed by blowing air between the first and second resin sheets with the slide portion stored in the first mold;

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