Manufacturing method for molded products

Abstract

The present invention provides a method for manufacturing molded articles that can improve the shapeability of resin sheets. [Solution] According to the present disclosure, a method for manufacturing a molded article is provided, comprising a hanging step, a shaping start step, a welding step, and a forming step, wherein in the hanging step, the first and second resin sheet forming apparatuses each hang down the first and second resin sheets; in the shaping start step, the shaping of the first resin sheet onto the first mold is started with the slide portion protruding from the first mold toward the second mold; in the welding step, 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 step, a first wall portion and inner rib made of the first resin sheet and a second wall portion made of the second resin sheet are formed by blowing air between the first and second resin sheets with the slide portion stored in the first mold.

Description

Technical Field

[0006] , , ,

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

Background Art

[0002] Regarding the manufacturing technology of a molded body including inner ribs, a method for manufacturing a resin laminate described in Patent Document 1 is known. In this method, a sealed space is formed between a thermoplastic resin sheet and the cavity of a mold, and a slide core is protruded while sucking the sealed space. In this state, the resin sheet is shaped into the mold to protrude a part of the resin sheet, and a part of the protruded resin sheet is welded to another thermoplastic resin sheet to form inner ribs.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above method, the slide core extends in a direction orthogonal to the hanging direction of the resin sheet. When the resin sheet is shaped into the mold with the slide core protruded, it is assumed that the resin sheet is shaped above and below the slide core. However, due to the action of gravity, the resin sheet may sag, and it may be difficult to shape the resin sheet below the slide core. Such a problem becomes particularly prominent when the resin sheet is thick.

[0005] The present disclosure has been made in view of such circumstances, and provides a method for manufacturing a molded body capable of improving the formability of a resin sheet.

Means for Solving the Problems

[0006] According to the present disclosure, the following inventions are provided. [1] A method for manufacturing a molded body using a molding apparatus, wherein the molded body includes a first wall portion, a second wall portion spaced apart from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion, the molding apparatus comprises a first resin sheet forming apparatus, a second resin sheet forming apparatus, and a mold unit, each of the first and second resin sheet forming apparatuses hanging down the first and second resin sheets, respectively, the mold unit includes first and second molds configured to open and close in an opening and closing direction, the first mold includes a slide portion that can move back and forth relative to the second mold, the longitudinal direction of the slide portion is at an angle of 0 to 30 degrees with respect to the hanging direction, and the method comprises a hanging step, a shaping start step, a welding step, and a forming step. A method comprising, the hanging step, in which the first and second resin sheet forming apparatuses each hang down the first and second resin sheets; the shaping start step, with the slide portion protruding from the first mold toward the second mold, the shaping of the first resin sheet toward the first mold is started; the welding step, by closing the first and second molds, the first resin sheet located at the tip of the slide portion is welded to the second resin sheet; and the forming step, with the slide portion stored in the first mold, air is blown between the first and second resin sheets to form the first wall portion and the inner rib made of the first resin sheet, and the second wall portion made of the second resin sheet. A method according to [2][1], wherein the thickness of the first and second resin sheets is 3.0 mm or more. A method according to [3] [1] or [2], wherein the sliding portion includes sides extending in both the direction in which the sliding 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 sides. A method according to any one of [4][1] to [3], wherein the slide portion includes a side surface that extends in both the direction in which the slide portion extends and the opening and closing direction, and further comprises a storage step, wherein in the storage step, the slide portion is stored in the first mold after the welding step, and in the storage step, the slide portion is stored before the first resin sheet comes into contact with the side surface. A method according to [5][4], wherein the time from closing the first and second molds in the welding step to starting to store the slide portion in the storage step is 1.0 second or more and 1.5 seconds or less. [6] A method for manufacturing a molded body using a molding apparatus, wherein the molded body includes a first wall portion, a second wall portion spaced apart from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion, the molding apparatus comprises a first resin sheet forming apparatus, a second resin sheet forming apparatus, and a mold unit, each of the first and second resin sheet forming apparatuses hanging down the first and second resin sheets, respectively, the mold unit includes first and second molds configured to open and close in an opening and closing direction, the first mold includes a slide portion that can move forward and backward relative to the second mold, the slide portion has length in the longitudinal direction and width in a width direction intersecting the longitudinal direction, the slide portion includes a pair of sides facing each other in the width direction when viewed from the opening and closing direction, and the method comprises a hanging step, a shaping start step, a welding step, and a forming step. A method comprising, the hanging step, in which the first and second resin sheet forming apparatuses each hang down the first and second resin sheets; the shaping start step, with the slide portion protruding from the first mold toward the second mold, the shaping of the first resin sheet toward the first mold is started; the welding step, by closing the first and second molds, the first resin sheet located at the tip of the slide portion is welded 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, with the slide portion stored in the first mold, air is blown between the first and second resin sheets to form the first wall portion and the inner rib made of the first resin sheet, and the second wall portion made of the second resin sheet. [7] A method for manufacturing a molded body using a molding apparatus, wherein the molded body includes a first wall portion, a second wall portion disposed at a distance from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion, the molding apparatus comprises a first resin sheet forming apparatus, a second resin sheet forming apparatus, and a mold unit, each of the first and second resin sheet forming apparatuses hanging down the first and second resin sheets, respectively, the mold unit includes first and second molds configured to open and close in an opening and closing direction, the first mold includes a slide portion that can move forward and backward relative to the second mold, the slide portion has length in the longitudinal direction and width in a width direction intersecting the longitudinal direction, the slide portion includes a pair of sides facing each other in the width direction when viewed from the opening and closing direction, and the method comprises a hanging step, a shaping start step, a welding step, a storage step, and a forming step. A method comprising: in the hanging step, the first and second resin sheet forming apparatuses each hang down the first and second resin sheets; in the shaping start step, with the slide portion protruding from the first mold toward the second mold, the shaping of the first resin sheet toward the first mold is started; in the welding step, 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; in the storage step, after the welding step, before the first resin sheet comes into contact with the side surface, the slide portion is stored in the first mold; and in the forming step, with the slide portion stored in the first mold, air is blown between the first and second resin sheets to form the first wall portion and the inner rib made of the first resin sheet, and the second wall portion made of the second resin sheet. [Effects of the Invention]

[0007] In the method for manufacturing a molded article according to this disclosure, the longitudinal direction of the slide portion is at an angle of 0 to 30 degrees with respect to the downward direction. This makes the resin sheet less likely to sag compared to the case where the longitudinal direction of the slide portion intersects the downward direction at an angle greater than 30 degrees. Therefore, the shapeability of the resin sheet can be improved. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic perspective view of the molded body 10. [Figure 2] This is a schematic diagram of a molding apparatus 1 according to one embodiment. [Figure 3] Figure 1 is a schematic cross-sectional view of the mold unit 4. [Figure 4] Figure 4A is a schematic front view of the mold 4a shown in Figure 3, and Figure 4B is a cross-sectional view taken along line BB in Figure 4A. [Figure 5] This is a schematic diagram showing one step in the manufacturing method of the molded article 10 according to the embodiment of this disclosure. [Figure 6] This is a schematic diagram showing the process after the process shown in Figure 5. The viewpoint in Figure 6 is the same as the viewpoint in Figure 4B. The same applies to Figures 7 to 9. [Figure 7] This is a schematic diagram showing the process after the process shown in Figure 6. [Figure 8] This is a schematic diagram showing the process after the process shown in Figure 7. [Figure 9] This is a schematic diagram showing the process after the process shown in Figure 8. [Modes for carrying out the invention]

[0009] Embodiments of this disclosure will be described below with reference to the drawings. The various features shown in the embodiments below can be combined with each other. Furthermore, each feature constitutes an independent invention. In addition, any elements in the embodiments below that are not defined in the claims are optional and can be omitted. Any number of zeros (e.g., one or two) may be added to the end of the numerical values ​​disclosed in the following description. For example, one or two zeros may be added after "1.4" to make it "1.40" or "1.400".

[0010] [1. Molded body 10] Using FIG. 1, the molded body 10 manufactured by the molding apparatus 1 will be described. The molded body 10 is a component used for furniture such as a bed, for example. The molded body 10 has a length in the longitudinal direction E1 and a thickness in the thickness direction E2 that intersects (for example, is orthogonal to) the longitudinal direction E1. Further, the molded body 10 has a width in the width direction E3 that intersects (for example, is orthogonal to) both the longitudinal direction E1 and the thickness direction E2. The molded body 10 includes wall portions 10a, 10b (first wall portion, second wall portion) and an inner rib 10c.

[0011] In FIG. 1, a boundary line is shown between the wall portions 10a, 10b, but in actuality, the wall portions 10a, 10b may be welded to each other and the boundary may not be distinguishable from the outside. The same applies to the boundary line shown on the inner rib 10c.

[0012] The wall portions 10a, 10b are arranged at intervals from each other. The wall portions 10a, 10b overlap each other in the thickness direction E2. Each of both ends in the longitudinal direction E1 of the wall portion 10a is welded to each of both ends in the longitudinal direction E1 of the wall portion 10b.

[0013] The thickness of the wall portions 10a, 10b is, for example, 1 mm to 10 mm, preferably 3 mm to 6 mm. Specifically, the thickness of the wall portions 10a, 10b 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, 10.0 mm, and may be within the range between any two of the values exemplified here.

[0014] The inner rib 10c has a function of improving 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, 10b to each other. The inner rib 10c extends in the thickness direction E2. In the present embodiment, the molded body 10 includes a plurality (for example, three) of inner ribs 10c. The plurality of inner ribs 10c are arranged side by side at intervals in the longitudinal direction E1.

[0015] The thickness of the inner rib 10c (the length in the longitudinal direction E1) is greater than the thicknesses 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. Specifically, the thickness of the inner rib 10c is, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 mm, and may be within the range between any two of the values exemplified herein.

[0016] The protruding height of the inner rib 10c (the length in the thickness direction E2) is, for example, 5 mm to 30 mm, and preferably 10 mm to 25 mm (15 mm in this embodiment). Specifically, the protruding height of the inner rib 10c is, 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, 30 mm, and may be within the range between any two of the values exemplified herein.

[0017] For example, when the molded body 10 needs to support a person's weight, a certain level of strength is required for the molded body 10. Therefore, it is desirable that the wall portions 10a and 10b and the inner rib 10c constituting the molded body 10 be formed of a sheet-like and thick resin member.

[0018] [2. Forming device 1] The forming device 1 according to an embodiment will be described with reference to FIGS. 2 to 4. The forming device 1 manufactures the molded body 10. The forming device 1 manufactures the molded body 10, for example, by blow molding a resin sheet 5 (described later). As shown in FIG. 2, the forming device 1 includes a pair of resin sheet forming devices 2 (a first resin sheet forming device and a second resin sheet forming device), 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 devices 2, suffixes A and B are attached as symbols 2A and 2B. 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 lowers the resin sheet 5 in a downward direction D1. The resin sheet forming apparatus 2 lowers the molten resin sheet 5. The downward 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 may be in the form of pellets. The raw material resin R is 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 pushes the raw resin R fed from the hopper 2a into the accumulator 2c. The extruder 2b includes a cylinder 2b1. The cylinder 2b1 heats the raw resin R fed from the hopper 2a to form molten resin R1. The cylinder 2b1 includes a screw (not shown) located inside it. The screw kneads the molten resin R1 while conveying it toward the tip of the cylinder 2b1.

[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 molten resin R1 stored in the cylinder 2c1 to the T-die 2d.

[0023] The T-die 2d causes the molten resin R1 supplied from the accumulator 2c to hang down. The T-die 2d includes a slit (not shown) inside it. The T-die 2d forms a resin sheet 5 by pushing the molten resin R1 out through the slit and causing it to hang down.

[0024] The length of the resin sheet 5 (length in the downward 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, 4000 mm, and may be within the range of any two of the values ​​exemplified here.

[0025] The width of the resin sheet 5 (the length of 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 is, for example, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000 mm, and may be within the range of any two of the values ​​exemplified here.

[0026] The thickness of the resin sheet 5 (length D2 in the opening / closing direction, 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, 10.0 mm, and may be within the range of 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 in order to construct the wall portions 10a, 10b and inner rib 10c constituting the molded body 10 from a thick resin member. However, if, for example, the slide portion extends in the orthogonal direction D3, as will be described later, when the resin sheet 5 is shaped onto the slide portion, the resin sheet 5 may sag due to the action of gravity, making it difficult to shape the resin sheet 5 on the lower side of 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 this 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 positioned between the resin sheet forming apparatus 2 and the mold unit 4. The roller unit 3 includes rollers 3a and 3b. The rollers 3a and 3b rotate in opposite directions while sandwiching the resin sheet 5, feeding the resin sheet 5 downwards to the roller unit 3. The gap between the rollers 3a and 3b may be configured to be variable. In this case, the resin sheet 5 can be sandwiched between the rollers 3a and 3b by positioning the resin sheet 5 between the rollers 3a and 3b with the gap widened, and then narrowing the gap. Roller 3a may be a fixed roller with a fixed position, while roller 3b may be a movable roller with a variable distance from roller 3a.

[0029] [2-3. Mold Unit 4] As shown in Figure 3, the mold unit 4 includes molds 4a and 4b (first mold and second mold) and mold frames 4c and 4d (first mold and second mold). Molds 4a and 4b are configured to be openable and closable in the opening / closing direction D2. The opening / closing direction D2 is, for example, a direction that intersects (e.g., perpendicular to) the downward direction D1.

[0030] The mold 4a includes a shaping surface 4a1 for shaping the resin sheet 5, and a pinch-off surface 4a2 configured to surround the shaping surface 4a1. The pinch-off surface 4a2 is located on the mold 4b side of the shaping surface 4a1.

[0031] The mold 4a includes a sliding portion 4a3. The sliding portion 4a3 is movable forward and backward relative to the mold 4b. Specifically, the sliding portion 4a3 can protrude from the mold 4a toward the mold 4b. The sliding portion 4a3 can be housed in the mold 4a in a direction away from the mold 4b. The sliding portion 4a3 may include a coating layer that is slippery against the resin sheet 5. An example of the material for the coating layer is fluororesin. Details of the sliding portion 4a3 will be described later.

[0032] The mold 4b includes a shaping surface 4b1 for shaping the resin sheet 5, and a pinch-off surface 4b2 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 is in contact with the pinch-off surface 4a2. When the molds 4a and 4b are closed, a molding region for molding the molded body 10 is formed between the shaping surfaces 4a1 and 4b1.

[0034] The mold 4c is positioned around the mold 4a. The mold 4c includes an adsorption surface 4c1 capable of adsorbing the resin sheet 5A. The adsorption surface 4c1 advances toward the resin sheet 5A and then adsorbs the resin sheet 5A. After adsorbing the resin sheet 5A, the mold 4c retracts relative to the mold 4a (i.e., the mold 4c retracts and / or the mold 4a advances). This configures the mold 4c to press the resin sheet 5A against the mold 4a.

[0035] The mold 4d is positioned around the mold 4b. The mold 4d includes an adsorption surface 4d1 capable of adsorbing the resin sheet 5B. The mold 4d advances toward the resin sheet 5B and then adsorbs the resin sheet 5B. After adsorbing the resin sheet 5B, the adsorption surface 4d1 retracts relative to the mold 4b (i.e., the mold 4d retracts and / or the mold 4b advances). This configures the mold 4d to press the resin sheet 5B against the mold 4b.

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

[0037] As shown in Figure 4A, the mold 4a is rectangular in plan view. The shape of the mold 4a can be selected according to the shape of the molded body 10 to be manufactured and is not particularly limited. The mold 4a includes a plurality (e.g., three) of sliding parts 4a3. The plurality of sliding parts 4a3 are arranged in an orthogonal direction D3. The orthogonal direction D3 is, for example, a direction perpendicular to both the downward direction D1 and the opening / closing direction D2. In this embodiment, the plurality of sliding parts 4a3 can be projected 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 downward direction D1. The length A1 (length in the longitudinal direction) of the sliding portion 4a3 is, for example, 3 cm to 30 cm, preferably 5 cm to 15 cm (10 cm in this embodiment). Specifically, the length A1 is, 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, 30 cm, and may be within the range of any two of the values ​​exemplified here.

[0039] Note that the sliding portion 4a3 does not need to extend strictly in the downward direction D1. The longitudinal direction of the sliding portion 4a3 has an angle of 0 to 30 degrees with respect to the downward direction D1, preferably 0 to 10 degrees (0 degrees in this embodiment). Specifically, this angle is, for example, 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, 30 degrees, and may be within the range of any two of the values ​​exemplified here.

[0040] The sliding portion 4a3 has a width in the width direction that intersects (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 sliding 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 is, 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, 12.0 mm, and may be within the range of any two of the values ​​exemplified here. The thickness A2 should be selected according to 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, preferably 0.02 to 0.14 (0.05 in this embodiment). Specifically, the value of A2 / A1 is, for example, 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, 0.40, and may be within the range of 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 (for example, the orthogonal direction D3) when viewed from the opening / closing direction D2. As shown in Figure 4B, when the slide portion 4a3 is housed in the mold 4a, the tip surface 4a32 is flush with the forming surface 4a1.

[0043] The slide portion 4a3 is housed in the housing portion 4a4 of the mold 4a when it is retracted relative to the mold 4b (see Figure 3). The slide portion 4a3 is slidable within the housing portion 4a4 in the opening / closing direction D2. The protrusion height A3 of the slide portion 4a3 is shorter than the distance from the forming surface 4a1 to the forming surface 4b1 (see Figure 3) when the molds 4a and 4b are closed. The protrusion height A3 refers to the distance from the forming surface 4a1 to the tip surface 4a32 when the slide portion 4a3 is in its furthest forward position 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 is, 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, 30 mm, and may be within the range of 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, preferably 0.1 to 0.5 (0.2 in this embodiment). Specifically, the value of A3 / A1 is, for example, 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, 1.00, and may be within the range of any two of the values ​​exemplified here.

[0046] [3. Method for manufacturing the molded body 10] Next, the manufacturing method for the molded body 10 using the molding apparatus 1 will be explained with reference to Figures 5 to 9. This manufacturing method comprises a hanging step, a pressing step, a shaping initiation step, a welding step, a storage step, and a forming step. The details of each step will be explained below.

[0047] [3-1. Drooping process] In the hanging process, as shown in Figure 2, the resin sheet forming apparatuses 2A and 2B each hang down the resin sheets 5A and 5B. Specifically, the resin sheet forming apparatus 2A pushes the resin sheet 5A toward the roller unit 3A. After passing through the roller unit 3A, the resin sheet 5A hangs down between the molds 4a and 4b, at a position adjacent to mold 4a.

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

[0049] [3-2. Pressing process] In the pressing process, molds 4c and 4d press the resin sheets 5A and 5B, respectively, against the molds 4a and 4b. Specifically, as shown in Figure 5, first, mold 4c moves forward 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 and 4d1 each adsorb the resin sheets 5A and 5B, the sliding portion 4a3 protrudes toward the mold 4b. Specifically, as the sliding portion 4a3 slides within the housing portion 4a4, the tip surface 4a32 approaches the resin sheet 5A. When the sliding portion 4a3 is protruding, the tip surface 4a32 is separated from the resin sheet 5A. From among the multiple sliding portions 4a3, the sliding portion 4a3 to be protruded may be selected according to the position and number of inner ribs 10c to be formed. However, the suction surfaces 4c1 and 4d1 may each adsorb the resin sheets 5A and 5B after the sliding portion 4a3 has protruded toward the mold 4b.

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

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

[0053] In the forming initiation process, air is drawn in from the space S1 between the resin sheet 5A and the forming surface 4a1 through suction holes (not shown) provided in the forming surface 4a1. As a result, the resin sheet 5A begins to approach the forming surface 4a1. Similarly, in the mold 4b, air is drawn in from the space between the resin sheet 5B and the forming surface 4b1 through suction holes provided in the forming 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 formed on the forming surface 4b1 before the resin sheet 5A is formed on the forming surface 4a1.

[0054] The suction holes provided on the shaping surface 4a1 may be located at 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 on the shaping surface 4a1, it is not necessary to draw air through these 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, potentially forming wrinkles 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 wrinkle formation in the wall portion 10a can be reduced, improving the aesthetic appearance of the molded body 10.

[0055] At the start of the molding process of the resin sheet 5A onto 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. Since the resin sheet 5A is not in contact with the side surface 4a31, the decrease in the temperature of the resin sheet 5A is suppressed.

[0056] [3-4. Welding process] In the welding process, as shown in Figure 7, the resin sheet 5A located at the tip of the slide portion 4a3 is welded to the resin sheet 5B by closing the molds 4a and 4b. Even during the welding process, the shaping of the resin sheet 5A onto the mold 4a continues, so the resin sheet 5A remains in close proximity to the shaped 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 and 4b are closed, the resin sheets 5A and 5B are welded to each other at the pinch-off surfaces 4a2 and 4b2. As a result, a thin-walled portion is formed at the pinch-off surfaces 4a2 and 4b2 that is thinner than the resin sheets 5A and 5B. In addition, both ends of the molded body 10 in the longitudinal direction E1 are formed on the inside of the thin-walled portion. Furthermore, the resin sheets 5A and 5B are welded to each other at the tip surface 4a32 of the slide portion 4a3. A burr B is formed on the outside of the molds 4a and 4b. The burr B is removed in a later process.

[0058] [3-5. Storage Process] In the storage process, as shown in Figure 8, the slide portion 4a3 is stored in the mold 4a after the welding process. Specifically, the slide portion 4a3 slides within the housing portion 4a4, causing it to retract relative to the mold 4b. As a result, the tip surface 4a32 separates from the resin sheet 5A while a portion of the resin sheet 5A remains welded to the resin sheet 5B. In the storage process, the slide portion 4a3 is stored before the resin sheet 5A comes into contact with the side surface 4a31.

[0059] The time from closing the molds 4a and 4b in the welding process until the start of storing the slide portion 4a3 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. Specifically, the start time may be, for example, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, or 1.50 seconds, and may be within the range of any two of the values ​​exemplified here.

[0060] If the start time is less than 1.0 second, the welding of the resin sheets 5A and 5B at the tip surface 4a32 of the slide portion 4a3 may be insufficient. In this case, a defect may occur in the inner rib 10c. Specifically, the welded portion 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 together with the slide portion 4a3 and towards the resin sheet 5A. In this case, the resin sheets 5A and 5B will be close to each other, making it difficult to secure the thickness of the molded body 10. In this embodiment, since the start time is 1.0 second or more and 1.5 seconds or less, a sufficient thickness of the molded body 10 can be secured while reducing the possibility of a defect occurring in the inner rib 10c.

[0061] [3-6. Forming process] In the forming process, as shown in Figure 9, the wall portions 10a, 10b and inner ribs 10c are formed by blowing air between the resin sheets 5A and 5B while the slide portion 4a3 is housed in the mold 4a. For example, a blowing needle may be inserted into at least one of the resin sheets 5A and 5B, and air may be blown between the resin sheets 5A and 5B through the blowing needle. The method of blowing air is not particularly limited.

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

[0063] Next, after opening the molds 4a and 4b, the burrs B are removed. The method for removing the burrs B is not particularly limited, but for example, the burrs B may be cut using a cutter or the like. After these steps, the manufacturing of the molded body 10 is completed.

[0064] [4. Effects and Benefits] In the above embodiment, the longitudinal direction of the slide portion 4a3 has an angle of 0 to 30 degrees (0 degrees in the above embodiment) with respect to the downward direction D1. This makes the resin sheet 5 less likely to sag compared to the case where the longitudinal direction of the slide portion 4a3 intersects the downward direction D1 at an angle greater than 30 degrees. Therefore, the shapeability of the resin sheet 5 can be improved.

[0065] At the time when the resin sheet 5A is formed in 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 comes into contact with the side surface 4a31, the temperature of the resin sheet 5A will decrease, 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 comes into contact with the side surface 4a31, and the slide portion 4a3 is then stored in the mold 4a. This shortens the time that the resin sheet 5A is in contact with the side surface 4a31, or prevents the resin sheet 5A from coming into contact with the side surface 4a31, thereby suppressing the decrease in the temperature of the resin sheet 5A. Therefore, the possibility of slit formation can be reduced.

[0066] In the above embodiment, the method for manufacturing 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, by the mold frames 4c and 4d, before the shaping start step. Since the shaping of the resin sheet 5 is started after the resin sheet 5 is pressed against the molds 4a and 4b, the shaping properties of the resin sheet 5 can be further improved.

[0067] In the above embodiment, the mold 4a includes a plurality of sliding portions 4a3. Therefore, a molded body 10 including a plurality of inner ribs 10c can be manufactured. When the molded body 10 includes a plurality of inner ribs 10c, the strength of the molded body 10 can be improved.

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

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

[0070] In the above embodiment, an example was described in which the mold 4a includes multiple slide portions 4a3, but the mold 4a may include only one slide portion 4a3. The number of slide portions 4a3 can be selected according to 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 Molded body 10 was manufactured using the manufacturing method described above. As the raw material resin R, a resin was used which was a mixture of polypropylene (VB170A (manufactured by Sun Allomer Co., Ltd.)) and high-density polyethylene (BM1052 (manufactured by Seibic Co., Ltd.)) in a ratio of 70:30. Other manufacturing conditions are as shown in Table 1. [Table 1]

[0072] 2. Example 2 Except for setting the start time to 1.25 seconds, the molded body 10 was manufactured in the same manner as in Example 1.

[0073] 3. Example 3 Except for setting the start time to 1.5 seconds, the molded body 10 was manufactured in the same manner as in Example 1.

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

[0075] Furthermore, each of the molded bodies 10 according to Examples 1 to 3 was cut along cross-sections extending in both the longitudinal direction E1 and the thickness direction E2, and the condition of the inner ribs 10c was observed. The test results are shown in Table 3. [Table 3]

[0076] The above evaluation tests 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 set to 16.5 cm or more, ensuring a sufficient thickness for the molded body 10. It was also confirmed that the condition of the inner ribs 10c can be kept in good condition. In particular, it was confirmed that the condition of the inner ribs 10c can be kept in good condition when the start time is 12.5 seconds. [Explanation of Symbols]

[0077] 1: Molding equipment 2: Resin sheet forming apparatus 2A: Resin sheet forming apparatus (First resin sheet forming apparatus) 2B: Resin sheet forming apparatus (Second resin sheet forming apparatus) 2a: Hoppa 2b: Extruder 2b1: Cylinder 2c: Accumulator 2c1: Cylinder 2c2: Piston 2d: T-die 3: Roller Unit 3A: Roller Unit 3B: Roller Unit 3a: Laura 3b: Laura 4: Mold Unit 4a: Mold (First mold) 4a1: Shaping surface 4a2: Pinch-off face 4a3: Slide section 4a31: Side view 4a32:Tip surface 4a4: Containment section 4b: Mold (Second mold) 4b1: Shaping surface 4b2: Pinch-off face 4c: Formwork (First formwork) 4c1: Adsorption surface 4d: Formwork (Second formwork) 4d1: Adsorption surface 5: Resin sheet 5A: Resin sheet (first resin sheet) 5B: Resin sheet (second resin sheet) 10: Molded body 10a: Wall section (first wall section) 10b: Wall part (second wall part) 10c: Inner rib A1: Length A2: Thickness A3: Protrusion height B: Bali D1: Drooping 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 apparatus, The molded body includes a first wall portion, a second wall portion disposed at a distance from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion. The molding apparatus comprises a first resin sheet forming apparatus, a second resin sheet forming apparatus, and a mold unit. Each of the first and second resin sheet forming apparatuses suspends each of the first and second resin sheets in a downward direction, The mold unit includes first and second molds configured to open and close in the opening and closing direction. The first mold includes a sliding portion that can move forward and backward relative to the second mold, The longitudinal direction of the sliding portion has an angle of 0 to 30 degrees with respect to the downward direction. The above method comprises a hanging step, a shaping initiation step, a welding step, and a forming step. In the hanging process, each of the first and second resin sheet forming apparatuses hangs down the first and second resin sheets. In the molding initiation step, with the slide portion protruding from the first mold toward the second mold, the molding of the first resin sheet toward the first mold is started. 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. The forming step involves blowing air between the first and second resin sheets while the slide portion is housed in the first mold, thereby forming the first wall portion and the inner rib made of the first resin sheet, and the second wall portion made of the second resin sheet.

2. The method according to claim 1, A method 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, The sliding portion includes sides that extend in both the direction in which the sliding portion extends and the opening and closing direction. In the welding process, the first and second molds are closed before the first resin sheet comes into contact with the side surface.

4. A method according to claim 1 or claim 2, The sliding portion includes sides that extend in both the direction in which the sliding portion extends and the opening and closing direction. With an additional storage process, In the storage step, after the welding step, the slide portion is stored in the first mold. In the storage step, the sliding portion is stored before the first resin sheet comes into contact with the side surface.

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

6. A method for manufacturing a molded body using a molding apparatus, The molded body includes a first wall portion, a second wall portion disposed at a distance from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion. The molding apparatus comprises a first resin sheet forming apparatus, a second resin sheet forming apparatus, and a mold unit. Each of the first and second resin sheet forming apparatuses suspends each of the first and second resin sheets in a downward direction, The mold unit includes first and second molds configured to open and close in the opening and closing direction. The first mold includes a sliding portion that can move forward and backward relative to the second mold, The sliding portion has length in the longitudinal direction and width in the width direction intersecting the longitudinal direction, The sliding portion includes a pair of sides facing each other in the width direction when viewed from the opening and closing direction, and the method comprises a hanging step, a shaping start step, a welding step, and a forming step. In the hanging process, each of the first and second resin sheet forming apparatuses hangs down the first and second resin sheets. In the molding initiation step, with the slide portion protruding from the first mold toward the second mold, the molding of the first resin sheet toward the first mold is started. 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. In the welding process, the first and second molds are closed before the first resin sheet comes into contact with the side surface. The forming step involves blowing air between the first and second resin sheets while the slide portion is housed in the first mold, thereby forming the first wall portion and the inner rib made of the first resin sheet, and the second wall portion made of the second resin sheet.

7. A method for manufacturing a molded body using a molding apparatus, The molded body includes a first wall portion, a second wall portion disposed at a distance from the first wall portion, and an inner rib connecting the first wall portion and the second wall portion. The molding apparatus comprises a first resin sheet forming apparatus, a second resin sheet forming apparatus, and a mold unit. Each of the first and second resin sheet forming apparatuses suspends each of the first and second resin sheets in a downward direction, The mold unit includes first and second molds configured to open and close in the opening and closing direction. The first mold includes a sliding portion that can move forward and backward relative to the second mold, The sliding portion has length in the longitudinal direction and width in the width direction intersecting the longitudinal direction, The sliding portion includes a pair of sides that face each other in the width direction when viewed from the opening and closing direction, The above method comprises a hanging step, a shaping initiation step, a welding step, a storage step, and a forming step. In the hanging process, each of the first and second resin sheet forming apparatuses hangs down the first and second resin sheets. In the molding initiation step, with the slide portion protruding from the first mold toward the second mold, the molding of the first resin sheet toward the first mold is started. 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. In the storage step, after the welding step, before the first resin sheet comes into contact with the side surface, the slide portion is stored in the first mold. The forming step involves blowing air between the first and second resin sheets while the slide portion is housed in the first mold, thereby forming the first wall portion and the inner rib made of the first resin sheet, and the second wall portion made of the second resin sheet.

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