Method for manufacturing foamed molded products

Abstract

To provide a method for manufacturing a foamed molded body for easily obtaining a foamed molded body in which a part of an embedded member is exposed from a foamed body.SOLUTION: A method for manufacturing a foam molded body according to the present invention is for obtaining a foam molded body formed by exposing a part of an embedded member from a foam body by using a mold 1. An embedded member 12 is arranged in a cavity S1 of the mold 1, a foaming raw material is foamed in the cavity S1, and a gas is jetted toward a part 12a of the embedded member 12. A gas jetting pressure is a pressure that is equivalent to a foaming pressure of the foaming raw material, and the gas jetting is started at a point in time when the foaming raw material starts to react and is continued, at the latest, until a rise time of the foaming raw material is passed.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] As a conventional foamed molded body, for example, there is known a foamed molded body in which a frame material for fixing to a seat frame of a vehicle protrudes from a foam (see, for example, Patent Document 1). When such a foamed molded body is not provided with any countermeasures, flash occurs around the frame material to be protruded from the foam during mold molding using a mold. Therefore, in the conventional method for manufacturing a foamed molded body, for example, as in the manufacturing method described in Patent Document 1, a detachable clearance member (nest) such as a rotating mold is provided in the cavity of the mold, and a clearance is formed in advance around the frame material to be protruded from the foam before supplying the foaming raw material.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above conventional manufacturing method, since a clearance member is arranged inside the molding die (mold), manual work by an operator is required, and the number of working hours also increases. Further, when a clearance member is arranged in the molding die, if the foaming raw material flows between the molding die and the clearance member, there is a concern that the foam may be formed in a shape different from the target. In addition, when a rotating mold is used as the clearance member as described in Patent Document 1, the foam enters and adheres to the rotation mechanism of the rotating mold, so that regular maintenance is required.

[0005] The object of the present invention is to provide a method for manufacturing a foamed molded body that allows for easy production of a foamed molded body in which a portion of the embedded member is exposed from the foam. [Means for solving the problem]

[0006] The present invention relates to a method for manufacturing a foamed molded body, which is a method for manufacturing a foamed molded body in which a part of the embedded member is exposed from the foam by using a mold, The method for manufacturing a foamed molded article according to the present invention includes a foaming raw material step, in which an embedded member is placed in a cavity formed inside the mold such that a portion of the embedded member is positioned higher than the lower surface of the cavity, and a foaming raw material is foamed within the cavity; and a gas injection step, in which gas is injected into the cavity toward the portion of the embedded member, wherein the gas injection pressure is equal to the foaming pressure of the foaming raw material, and the gas injection is started when the foaming raw material begins to react and continues at the latest until the rise time of the foaming raw material has elapsed.

[0007] In the method for manufacturing a foamed molded body according to the present invention, the gas injection time is adjusted according to the height between the part of the embedded member and the lower surface of the cavity. When manufacturing two or more foamed molded bodies with different exposed dimensions of the embedded member, it is preferable to make the gas injection time longer for the one with the greater height compared to the one with the less height. In this case, foamed molded bodies with different exposed dimensions of the embedded member can be easily obtained. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for manufacturing a foamed molded body in which a portion of an embedded member is exposed from the foam, and to easily obtain a foamed molded body. [Brief explanation of the drawing]

[0009] [Figure 1]This is a schematic cross-sectional view showing an example of a mold system usable in a method for manufacturing a foamed molded article, according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing a foamed molded body that can be molded using the molding system shown in Figure 1. [Figure 3] This is a cross-sectional view showing an enlarged portion of the mold shown in Figure 1, in order to explain a method for manufacturing a foamed molded article according to one embodiment of the present invention. [Figure 4] This is a cross-sectional view showing an enlarged portion of the mold corresponding to a part of the mold shown in Figure 1, in order to explain a comparative example of a method for manufacturing a foamed molded article, for comparison with a method for manufacturing a foamed molded article according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] The following describes a method for manufacturing a foamed molded article according to one embodiment of the present invention, with reference to the drawings.

[0011] Figure 1 schematically shows a molding system 100 that can be used in a method for manufacturing a foamed molded article, according to one embodiment of the present invention. As shown in Figure 1, the molding system 100 includes a mold 1.

[0012] The present disclosure is a method for manufacturing a foamed molded body, which uses the mold 1 shown in Figure 1 to obtain a foamed molded body in which a portion of the embedded member is exposed from the foam.

[0013] Figure 2 schematically shows a foamed molded body 10 that can be molded using the molding system 100. As shown in Figure 2, the foamed molded body 10 has a portion 12a of the embedded member 12 exposed from the foam 11.

[0014] Examples of foamed molded articles 10 obtained by the manufacturing method of foamed molded articles according to this disclosure include vehicle seat pads. In this disclosure, the foamed molded article 10 is a back pad used in automobiles. However, the foamed molded article 10 is not limited to automobile back pads. For example, the foamed molded article 10 can be a seat pad for automobile seats. Furthermore, the foamed molded article 10 is not limited to automobile seats and can be applied to vehicles other than automobiles. Moreover, the foamed molded article 10 can be applied to seat pads for vehicles other than automobiles.

[0015] In this disclosure, the front surface F11a of the foam 11 is the backrest surface that the occupant's back rests against. In this disclosure, the rear surface F11b of the foam 11 is the mounting surface that is attached to the seat frame of the vehicle.

[0016] The foam 11 is formed by foaming a foaming raw material. Examples of the foaming raw material include polyurethane. In this disclosure, the foam 11 is formed from polyurethane foam. Examples of polyurethane foam include rigid polyurethane foam, semi-rigid polyurethane foam, and flexible polyurethane foam.

[0017] An embedded member 12 is embedded in the foam 11. In this disclosure, the embedded member 12 is a frame member that forms the basic structure of the foamed molded body 10. In this disclosure, a portion 12a of the embedded member 12 protrudes rearward from the rear surface F11b1 of the upper part 11a of the foam 11. In this disclosure, the embedded member 12 is formed of a material having higher strength than the foam 11, for example, metal or resin (for example, engineering plastic).

[0018] In the method for manufacturing a foam molded body of the present disclosure, mold molding is used, in which the foam raw material M is foamed in the cavity S1 of the mold 1 in FIG. 1 to mold the foam body 11. In the present disclosure, the mold molding is a molding method for obtaining a foam molded body 10 in which a buried member 12 is arranged in a cavity S1 formed inside the mold 1 by using the mold 1, and a part 12a of the buried member 12 is exposed from the foam body 11 by foaming the foam raw material M in the cavity S1. Specifically, the method for manufacturing a foam molded body of the present disclosure includes at least the following two steps.

[0019] (Foaming process of foam raw material) The foaming process of the foam raw material corresponds to the first step of the method for manufacturing a foam molded body of the present disclosure. In the foaming process of the foam raw material, the buried member 12 is arranged in the cavity S1 formed inside the mold 1 so that a part 12a of the buried member 12 is at a position higher than the lower surface FL of the cavity S1, and the foam raw material M is foamed in this cavity S1.

[0020] In the present disclosure, the mold 1 includes an upper mold 2 and a lower mold 3. The upper mold 2 and the lower mold 3 can be separated by being spaced apart from each other in the vertical direction. Also, the upper mold 2 and the lower mold 3 can be combined by approaching each other in the vertical direction. In the present disclosure, the cavity S1 is formed between the upper mold 2 and the lower mold 3 by combining the upper mold 2 and the lower mold 3.

[0021] In the present disclosure, on the lower surface of the upper mold 2, as shown in FIG. 1, for example, by using existing means, the embedded member 12 can be removably attached to a predetermined position. Thereby, the embedded member 12 can be disposed at a predetermined position within the cavity S1 as shown in FIG. 1 by combining the upper mold 2 and the lower mold 3. That is, in the present disclosure, the embedded member 12 can be accommodated within the cavity S1 as an insert for mold molding. In the present disclosure, as shown in FIG. 1, when the upper mold 2 and the lower mold 3 are combined and clamped, the embedded member 12 is disposed within the cavity S1 such that a part 12a thereof is at a position higher than the lower mold surface (FL) of the lower mold 3.

[0022] Also, in the present disclosure, the foaming raw material M is foamed within the cavity S1 where the embedded member 12 is disposed. The foaming raw material M can be introduced onto the lower surface FL of the cavity S1 by separating the upper mold 2 from the lower mold 3. As a specific example, before combining the upper mold 2 and the lower mold 3, unfoamed liquid foaming raw material M is injected onto the lower mold surface (the lower surface FL of the cavity S1) of the lower mold 3. After injecting the foaming raw material M into the lower mold 3, the upper mold 2 is combined with the lower mold 3. That is, in the present disclosure, the clamping of the upper mold 2 and the lower mold 3 is performed after supplying the foaming raw material M to the lower mold 3.

[0023] (Gas injection process) The gas injection process corresponds to the second process of the method for manufacturing a foamed molded body of the present disclosure. In the gas injection process, gas G is injected toward a part 12a of the embedded member 12 within the cavity S1.

[0024] In the present disclosure, the gas G is supplied into the mold 1 through the gas supply unit 4. In the present disclosure, the mold 1 includes a clearance forming portion 5. The gas supply unit 4 is connected to the clearance forming portion 5.

[0025] In FIG. 3, a part of the mold 1 is shown enlarged.

[0026] The clearance forming section 5 forms a clearance space S2 to prevent the foaming material M from adhering to a part 12a of the embedded member 12. The clearance space S2 is connected to the cavity S1 that forms the outer shape of the foam 11 and is a space filled with gas G supplied through the gas supply section 4.

[0027] The clearance forming section 5 is formed to surround a portion 12a of the buried member 12. In this disclosure, the clearance forming section 5 is formed on the upper mold 2. In this disclosure, the gas supply section 4 is positioned so that its supply port 4a faces the tip 12a1 of the portion 12a of the buried member 12. As a result, in this disclosure, the gas G is filled into the clearance space S2 from the tip 12a1 of the portion 12a of the buried member 12 along the extending direction of the portion 12a of the buried member 12. In this case, it is possible to efficiently prevent the foaming material M from adhering to the portion 12a of the buried member 12.

[0028] In this disclosure, the supply of gas G begins when the foaming raw material M starts to react (foam). Specifically, the supply of gas G can be started when the upper mold 2 and the lower mold 3 are clamped together, which is considered the time when the foaming raw material M starts to react. Alternatively, the supply of gas G can be started after a predetermined time has elapsed from the time the upper mold 2 and the lower mold 3 are clamped together, which is considered the time when the foaming raw material M starts to react. Here, the predetermined time can be set considering the time it is predicted that the foaming raw material M will start to foam in the cavity S1.

[0029] Referring to Figure 1, in this disclosure, gas G is supplied from a gas supply source 6. In this disclosure, the gas supply source 6 is an air tank. That is, in this disclosure, gas G is the air filled in the air tank. However, gas G is not limited to air. Gas G may be a gas that does not easily cause a chemical reaction with the foaming raw material M, such as nitrogen gas.

[0030] The injection pressure P of gas G is equivalent to the foaming pressure Pf of the foaming raw material M.

[0031] Here, "pressure equivalent to the foaming pressure Pf of the foaming material M" includes both the pressure identical to the foaming pressure Pf of the foaming material M and the pressure that is permissible as the foaming pressure Pf of the foaming material M. The foaming pressure Pf of the foaming material M depends on the type of foaming material M.

[0032] Here, the allowable pressure Pf for the foaming material M is the foaming pressure Pf ± allowable pressure ΔP (≠Pf). That is, P can be expressed mathematically as follows:

[0033] [Mathematics 1] Pf - ΔP ≤ P ≤ Pf + ΔP

[0034] In this disclosure, the foaming pressure Pf of the foaming raw material M is the foaming pressure Pf1 (MPa) of polyurethane. Also in this disclosure, the allowable pressure range ΔP is 0.03 (MPa).

[0035] The injection of gas G begins when the foaming raw material M starts reacting and continues until the rise time TR of the foaming raw material M has elapsed at the latest.

[0036] Here, the injection of gas G begins at the point when the foaming raw material M starts reacting, as described above. The rise time TR is the time from when the foaming raw material M starts foaming until it reaches its maximum height (i.e., until the foaming of the foaming raw material M stops). The rise time TR depends on the type of foaming raw material M.

[0037] In this disclosure, the injection of gas G is initiated when the liquid, unfoamed polyurethane begins to foam and continues at the latest until the rise time TR1 of the polyurethane has elapsed.

[0038] According to the method for manufacturing a foamed molded article of this disclosure, by supplying gas G to the clearance space S2 of the mold 1 in accordance with the reaction of the foaming raw material M, the growth of the foaming raw material M in the clearance space S2 can be suppressed. As a result, as shown in Figure 3, the foaming raw material M can be attached to most of the embedded member 12, while preventing the foaming raw material M from attaching to a part 12a of the embedded member 12.

[0039] Figure 4 shows an enlarged view of a portion of the mold 1M of the comparative example, corresponding to a part of the mold 1 shown in Figure 1, for comparison with a method for manufacturing a foamed molded article according to one embodiment of the present invention.

[0040] In this comparative example, a clearance member C1 is required to fill the clearance space S2 during mold molding. Therefore, as shown in Figure 4, the clearance member C1 is placed in the clearance space S2 to prevent the foaming material M from adhering to a portion 12a of the embedded member 12. However, in this comparative example, the clearance member C1 must be removed from a portion 12a of the embedded member 12 or from the clearance space S2 after mold molding.

[0041] In contrast, according to the method for manufacturing a foamed molded body of the present disclosure, a foamed molded body 10 can be easily obtained in which a part 12a of the embedded member 12 is exposed from the foam 11.

[0042] For example, according to the method for manufacturing a foamed molded body of this disclosure, the adhesion of the foaming material M to a part 12a of the embedded member 12 can be prevented simply by injecting gas G. In this case, it is not necessary to place the clearance member C1 inside the mold 1, as in the comparative example in Figure 3. Therefore, the manual work performed by the worker in the comparative example in Figure 3 is eliminated, and the number of work hours can be reduced. Furthermore, according to the method for manufacturing a foamed molded body of this disclosure, it is not necessary to place the clearance member C1 inside the mold 1, as in the comparative example in Figure 3, so the foaming material M does not flow between the mold 1 and the clearance member C1. Therefore, according to the method for manufacturing a foamed molded body of this disclosure, the foam 11 can be formed into the shape targeted during the design phase. In addition, according to the method for manufacturing a foamed molded body of this disclosure, it is not necessary to make the clearance member C1 a rotating type, as described in Patent Document 1. Therefore, according to the method for manufacturing a foamed molded body of this disclosure, the foaming material M does not enter or adhere to the rotating mechanism of the rotating type, so periodic maintenance is not required.

[0043] In this disclosure, the gas injection time (duration of gas injection) T of the embedded member 12 is adjusted according to the height H between a part 12a of the embedded member 12 and the lower surface FL of the cavity S1. In this disclosure, when manufacturing two or more foamed molded bodies 10 with different exposed dimensions L of the embedded member 12, it is preferable to make the gas injection time T of the body with a higher height H longer than that of the body with a lower height H. In this case, foamed molded bodies with different exposed dimensions of the embedded member 12 can be easily obtained.

[0044] Specific examples include the following:

[0045] Referring to Figure 2, in this disclosure, as shown in Figure 2, a portion 12a of the embedded member 12 of the foamed molded body 10 protrudes (is exposed) by an exposure dimension L from the rear surface F11b1 of the upper part 11a of the foamed body 11.

[0046] In the method for manufacturing a foamed molded body according to this disclosure, the exposed dimension L changes according to the gas injection time T. When manufacturing two foamed molded bodies 10 with different exposed dimensions L using the method for manufacturing a foamed molded body according to this disclosure, the gas injection time T is made longer when manufacturing the foamed molded body 10 with a longer exposed dimension L than when manufacturing the foamed molded body 10 with a shorter exposed dimension L. In this case, the growth of the foaming raw material M during foaming is taken into account in the gas injection time T. As a result, foamed molded bodies with different exposed dimensions of the embedded member 12 can be easily obtained by using the same molding system 100, that is, the same manufacturing method.

[0047] Here, as shown in Figure 1, height H is the height from the bottom surface FL1 of the cavity S1, which is directly below a portion 12a of the embedded member 12. In this disclosure, height H is the height from the bottom surface FL1 of the cavity S1 to the tip 12a1 of a portion 12a of the embedded member 12.

[0048] As shown in Figure 1, in this disclosure, the molding system 100 includes a pressure regulator 7 and an on / off valve 8 in addition to the gas supply source 6.

[0049] In this disclosure, the injection pressure P of the gas G can be adjusted, for example, by a pressure regulator 7 located downstream of the gas supply source 6. In this case, the gas G can be injected into the clearance space S2 at the pressure adjusted by the pressure regulator 7. In this disclosure, an on-off valve 8 is located between the pressure regulator 7 and the gas supply unit 4. In this case, the injection and cessation of the injection of gas G can be controlled by opening and closing the on-off valve 8. The on-off valve 8 can be operated manually or automatically.

[0050] The above describes exemplary embodiments of the present invention, and various modifications can be made without departing from the scope of the claims. For example, in this disclosure, a portion 12a of the buried member 12 is configured to extend in the vertical direction, but the direction in which a portion 12a of the buried member 12 faces is not limited to the vertical direction. Furthermore, the buried member 12 is not limited to a frame member. That is, the external shape of the buried member 12 can be changed to various external shapes, along with the external shape of the foam body 11. [Explanation of symbols]

[0051] 1: Molding mold, 2: Upper mold, 3: Lower mold, 4: Gas supply unit, 5: Clearance shape unit, 6: Gas supply source, 7: Pressure regulator, 8: On / off valve, 10: Foamed molded body, 11: Foam, 12: Embedded member, 12a: Part of embedded member, 100: Molding system, G: Gas, H: Height between part of embedded member and the bottom surface of the cavity, M: Foaming material, S1: Cavity, FL: Bottom surface of the cavity, FL1: Directly below the cavity, S2: Clearance space, P: Gas injection pressure, Pf: Foaming pressure of foaming material, Pf1: Foaming pressure of polyurethane, ΔP: Allowable pressure range, T: Gas injection time, TR: Foam rise time, TR1: Polyurethane rise time

Claims

1. A method for manufacturing a foamed molded body, which involves using a mold to obtain a foamed molded body in which a portion of the embedded member is exposed from the foam, A foaming raw material step is performed, in which the embedded member is placed in a cavity formed inside the mold such that the entire embedded member is positioned higher than the lower surface of the cavity, and the foaming raw material is foamed within the cavity. The process includes a gas injection step of injecting gas into a clearance-forming portion formed in the mold so as to surround a portion of the embedded member, in order to form a clearance space in the cavity so as to prevent foaming material from adhering to a portion of the embedded member, The injection pressure of the gas is equivalent to the foaming pressure of the foaming raw material. A method for manufacturing a foamed molded article, wherein the injection of the gas is started when the foaming raw material begins to react and is continued at the latest until the rise time of the foaming raw material has elapsed.

2. The method for manufacturing a foamed molded body according to claim 1, wherein the gas injection time is adjusted according to the height between the part of the embedded member and the lower surface of the cavity, and when manufacturing two or more foamed molded bodies in which the exposed dimensions of the embedded member differ, the gas injection time is made longer for the one with the higher height than for the one with the lower height.

Images