JP2018179357A - Molded article and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a formed part which can suppress the deformation of an opening.SOLUTION: A formed part 5 includes a cylindrical base part 6, and an opening 4b provided in the base part, and is formed with a rib 8 which reinforces a rim of the opening in a position adjacent to the opening for suppressing the deformation of the opening.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a molded article and a method of manufacturing the same.

  For example, in an air conditioner such as a car, a tubular air conditioning duct for ventilating air is used.

  As a method of manufacturing a duct for air conditioning, there is widely known a blow molding method in which a molten resin is clamped with a split mold and air is blown into the inside to expand it (see Patent Document 1).

JP, 2012-207837, A

  When forming an opening in a molded body in blow molding, a portion called a disposable bag is usually formed by providing a closed part at one end of the cylindrical part, and the open part is formed by cutting off the closed part. . Usually, residual stress is present in the cylindrical portion constituting the disposable bag, and in the state where the closed portion is provided, the balance of the residual stress is maintained and the shape of the disposable bag is maintained. For this reason, when the closed portion is cut off, the balance of the residual stress may be lost and the opening may be deformed to be narrowed. When the opening is deformed, there is a problem such as a failure in joining with other members.

  This invention is made in view of such a situation, and provides the molded article which can suppress a deformation | transformation of an opening part.

  According to the present invention, there is provided a molded article comprising a cylindrical base and an opening provided in the base, wherein a rib is provided at a position adjacent to the opening.

  The molded article of the present invention is provided with a rib at a position adjacent to the periphery of the opening, and the rib reinforces the periphery so that deformation of the opening is suppressed.

Hereinafter, various embodiments of the present invention will be illustrated. The embodiments shown below can be combined with one another.
Preferably, the rib is provided between the parting line of the molded article and the opening.
Preferably, assuming that the distance between the parting line of the molded product and the opening is L1 and the length of the side wall of the rib is L2, L2 / L1 is 0.5 or more.
Preferably, side walls of the ribs are provided to connect to the parting line.
Preferably, the rib is provided so as to increase in depth with distance from the opening.
Preferably, assuming that the depth at the deepest part of the rib is D and the thickness of the bottom wall of the rib is T, D / T is 2 or more.
Preferably, the molded article includes a beam rib provided along the periphery of the opening, and the beam rib is provided between the parting line of the molded article and the opening.
Preferably, the rib is provided to connect to the beam rib.
Preferably, a plurality of the ribs are provided to be connected to the beam rib.
Preferably, the beam rib is constituted by a groove-like recess provided along the peripheral edge.
Preferably, the rib is provided in the groove-like recess.
Preferably, the peripheral edge of the opening includes a pair of long sides facing each other and a pair of short sides provided to connect the pair of long sides.
Preferably, the rib is provided at the center of the long side.
Preferably, the molded article is a foam molded article.
According to another aspect of the present invention, there is provided a molded body forming step and a cutting step, in the molded body forming step, a molded body is formed by molding a molten resin, and the molded body has a cylindrical base and A cylindrical portion provided to stand up from the base, and a rib at a position adjacent to the cylindrical portion, wherein the cylindrical portion is provided with a closed portion at one end, and in the cutting step, the cylindrical portion is There is provided a method of manufacturing a molded article, wherein the closed portion is cut off to form an opening by cutting.

An example of the molding machine 1 which can be utilized with the manufacturing method of one Embodiment of this invention is shown. It is a perspective view which shows the molded object 10 for manufacturing the molded article 5 of 1st Embodiment of this invention. The molded article 5 obtained by removing obstruction | occlusion part 3a, 4a from the molded object 10 of FIG. 2 is shown. It is a cross-sectional perspective view which passes along the center of the rib 9 of the molded article 5 of FIG. It is sectional drawing to which the cross-sectional vicinity in the cross-sectional perspective view of FIG. 4 was expanded. It is a perspective view which shows the molded object 10 for manufacturing the molded article 5 of 2nd Embodiment of this invention. The molded article 5 obtained by removing obstruction | occlusion part 3a, 4a from the molded object 10 of FIG. 6 is shown. It is a cross-sectional perspective view which passes along the center of the molded article 5 of FIG. It is sectional drawing to which the cross-sectional vicinity in the cross-sectional perspective view of FIG. 4 was expanded.

  Hereinafter, embodiments of the present invention will be described. The various features shown in the embodiments described below can be combined with one another. In addition, the invention is established independently for each feature.

1. Configuration of Molding Machine 1 First, with reference to FIG. 1, a molding machine 1 that can be used to carry out a method of manufacturing a molded article according to an embodiment of the present invention will be described. The molding machine 1 includes a resin supply device 2, a head 18, and a split mold 19. The resin supply device 2 includes a hopper 12, an extruder 13, an injector 16, and an accumulator 17. The extruder 13 and the accumulator 17 are connected via a connecting pipe 25. The accumulator 17 and the head 18 are connected via a connecting pipe 27.
Each component will be described in detail below.

Hopper 12, extruder 13
The hopper 12 is used to introduce the raw material resin 11 into the cylinder 13 a of the extruder 13. The form of the raw material resin 11 is not particularly limited, but is usually in the form of pellets. The raw material resin 11 is, for example, a thermoplastic resin such as polyolefin, and examples of the polyolefin include low density polyethylene, linear low density polyethylene, high density polyethylene, polypropylene, ethylene-propylene copolymer, and a mixture thereof. The raw material resin 11 is introduced into the cylinder 13a from the hopper 12 and then melted by being heated in the cylinder 13a to become a molten resin. Further, it is conveyed toward the tip of the cylinder 13a by the rotation of a screw disposed in the cylinder 13a. The screw is disposed in the cylinder 13a and is conveyed while kneading the molten resin by its rotation. A gear device is provided at the proximal end of the screw, and the screw device is rotationally driven by the gear device. The number of screws disposed in the cylinder 13a may be one or two or more.

<Injector 16>
The cylinder 13a is provided with an injector 16 for injecting a foaming agent into the cylinder 13a. In the case where the raw material resin 11 is not foamed, the injector 16 can be omitted. The blowing agent injected from the injector 16 includes physical blowing agents, chemical blowing agents, and mixtures thereof, with physical blowing agents being preferred. As physical blowing agents, inorganic physical blowing agents such as air, carbon dioxide gas, nitrogen gas, water and the like, organic physical blowing agents such as butane, pentane, hexane, dichloromethane, dichloroethane and the like, and their supercritical fluids are used. be able to. As a supercritical fluid, it is preferable to use carbon dioxide, nitrogen, etc., and if it is nitrogen, its critical temperature is -149.1 ° C, its critical pressure is 3.4 MPa or more, and if it is carbon dioxide, its critical temperature is 31 ° C, its critical pressure It is obtained by setting it as 7.4 MPa or more. Examples of the chemical blowing agent include those which generate carbon dioxide gas by the chemical reaction of an acid (eg, citric acid or a salt thereof) and a base (eg, sodium bicarbonate). The chemical blowing agent may be fed from the hopper 12 instead of the injector 16.

<Accumulator 17, Head 18>
The molten resin 11 a to which the foaming agent is added or not added is extruded from the resin extrusion port of the cylinder 13 a and injected into the accumulator 17 through the connecting pipe 25. The accumulator 17 includes a cylinder 17a and a piston 17b slidable therein, and the molten resin 11a can be stored in the cylinder 17a. Then, after the molten resin 11a is stored in the cylinder 17a by a predetermined amount, the piston 17b is moved to push down the molten resin 11a from the die slit provided in the head 18 through the connecting pipe 27 and to hang down the parison 23 Form. The shape of the parison 23 is not particularly limited, and may be cylindrical or sheet-like.

<Divided mold 19>
The parison 23 is guided between the pair of split dies 19. By molding the parison 23 using the split mold 19, a molded body 10 as shown in FIG. 2 is obtained. The method of molding using the split mold 19 is not particularly limited, and may be blow molding in which air is blown into the cavity of the split mold 19 for molding, and the inside of the cavity from the inner surface of the cavity of the split mold 19 may be formed. It may be vacuum forming in which the parison 23 is formed by reducing the pressure, or a combination thereof. When the molten resin contains a foaming agent, the parison 23 becomes a foamed parison, and the molded body 10 becomes a foamed molded body.

  FIG. 2 shows a molding 10 for producing a duct for air conditioning. The molded body 10 has cylindrical parts 3 and 4 provided with the closed parts 3a and 4a at one end. The cylindrical portion 4 is provided to rise from the cylindrical base 6. The cylindrical portion 3 is provided at both ends of the base 6. Although the molded body 10 does not have a branched structure in FIG. 2, the number of cylindrical portions 3 may be three, four or more by branching the cylindrical portions 3.

2. Molded Article of First Embodiment and Method of Manufacturing the Same A molded article of a first embodiment of the present invention and a method of manufacturing the same will be described with reference to FIGS. 1 to 6. The method of the present embodiment comprises a formed body forming step and a cutting step. The details will be described below.

2.1 Molded Body Forming Step In this step, as shown in FIGS. 1 and 2, a molded body having cylindrical portions 3 and 4 provided with the closed portions 3a and 4a at one end by molding the molten resin 11a. Form 10 This process can be implemented using the above-mentioned molding machine 1. Although the effect of the present invention can be obtained when the molded body 10 is either a solid molded article or a foam molded article, when the molded article 10 is a foam molded article, the opening 3b by cutting off the closed portions 3a and 4a. Since the shape change of 4b and 4b is remarkable, when the molded body 10 is a foam-molded article, the technical significance of applying the present invention is particularly large. The expansion ratio of the foam-molded article is, for example, 1.5 to 5 times, preferably 2 to 4 times, and specifically, for example, 1.5, 2, 2.5, 3, 3.5, 4 , 4.5, and may be in the range between any two of the numerical values exemplified here. The thickness of the foam-molded article is, for example, 1 to 7 mm, preferably 1.5 to 5 mm, and specifically, for example, 1, 1.5, 2, 2.5, 3, 3.5, It is 4, 4.5, 5, 5.5, 6, 6.5, 7 mm, and may be in the range between any two of the numerical values exemplified here.

2.2 Excision Step In this step, as shown in FIGS. 2 to 3, the blocking portions 3 a and 4 a are excised by cutting the cylindrical portions 3 and 4 along a cutting line S indicated by a dashed dotted line. By this, as shown in FIGS. 3 to 5, the openings 3 b and 4 b are formed in the cylindrical portions 3 and 4, and the molded product 5 is obtained.

  By the way, residual stress is present in the molded body 10 formed by molding the molten resin 11a, and in the state where the closed portions 3a and 4a are provided, the residual stress of each part is balanced. When the blocking portions 3a and 4a are cut off, the balance of the residual stress is lost, and the openings 3b and 4b are deformed. Although both the openings 3b and 4b are deformed, generally, the larger the area of the openings 3b and 4b, the larger the change in the shape, so the shape change at the opening 4b is remarkable. So, in this embodiment, the deformation | transformation of the opening part 4b is suppressed by providing the ribs 8 and 9 in the position adjacent to the cylinder part 4 and the opening part 4b.

  The cylindrical portion 4 and the opening 4b are rectangular. Therefore, the side wall of the cylindrical portion 4 and the peripheral edge of the opening 4b include a pair of long sides 4c facing each other and a pair of short sides 4d provided to connect the pair of long sides 4c. The long side 4c and the short side 4d are connected at the corner 4e. The length of the long side portion 4c is, for example, 100 to 500 mm, and specifically, for example, 100, 150, 200, 250, 300, 350, 400, 450, 500 mm, any of the numerical values exemplified here It may be in the range between the two. The length of the short side 4d is, for example, 50 to 250 mm, and specifically, for example, 50, 100, 150, 200, 250 mm, and is within the range between any two of the numerical values exemplified here. May be The ratio of the length of the long side 4c to the length of the short side 4d is, for example, 1.5 to 5 times, and specifically, for example, 1.5, 2, 2.5, 3, 3.5 , 4, 4.5, 5 mm, and may be in the range between any two of the numerical values exemplified here. The radius of curvature of the corner 4 e is, for example, 1 to 30 mm, and specifically, for example, 1, 5, 10, 15, 20, 25, 30 mm, and the range between any two of the numerical values exemplified here It may be within. The cylindrical portion 4 is provided to rise from the base 6. The height of the cylindrical portion 4 is, for example, 10 to 50 mm, and specifically, for example, 10, 15, 20, 25, 30, 35, 40, 45, 50 mm, any one of the numerical values exemplified here It may be in the range between two.

  As shown in FIGS. 3 to 5, the base 6 is cylindrical. The base 6 includes a base wall 6a, side walls 6b and 6c, and an opposing wall 6d. The cylindrical portion 4 and the opening 4b are formed in the base wall 6a. Side walls 6b and 6c are substantially parallel. The opening 4b is provided between the side walls 6b and 6c. The opposing wall 6d faces the opening 4b. The side walls 6b and 6c are connected by the opposing wall 6d. As shown in FIG. 5, the angle α between the opening surface (surface formed by the periphery of the opening 4b) P and the side wall 6b is preferably 20 to 80 degrees, preferably 30 to 60 degrees, and 40 to 50 degrees. Is preferred. The smaller the angle is, the more easily the side wall 6b falls in the direction in which the opening 4b is narrowed. Therefore, the technical object of suppressing the deformation of the opening 4b is remarkable by providing the ribs 8 and 9.

  The rib 8 is a V-groove shaped rib, and is provided in a large number along the long side 4c on the side wall 6b side and the pair of short sides 4d. The rigidity of the peripheral edge of the opening 4 b is enhanced by the rib 8. On the side wall 6c side, a parting line PL is provided along the long side 4c at a position adjacent to the long side 4c, and a beam 28 is provided along the parting line PL to enhance the strength. There is.

  As shown in FIG. 3, the rib 9 is provided at the center of the long side 4 c on the side wall 6 b between the parting line PL and the opening 4 b. The opening 4b is most likely to be deformed near the center of the long side 4c, and the rib 9 suppresses the deformation of the long side 4c. As shown in FIGS. 4 to 5, the rib 9 is provided so as to extend from the parting line PL toward the opening 4 b. Since the thickness of the molded product 5 becomes thicker as it approaches the parting line PL, deformation of the opening 4b is suppressed by providing the rib 9 extending from the parting line PL toward the opening 4b.

  The rib 9 is in the form of a groove and includes a pair of side walls 9a, a bottom wall 9b, and an end wall 9c. The bottom wall 9 b is provided between the pair of side walls 9 a. The end wall 9c is connected to the side wall 9a and the bottom wall 9b. The end wall 9c is provided on the parting line PL. The end wall 9c has high strength because the parison 23 is formed by being compressed by the split mold 19 during molding.

  Assuming that the distance between the parting line PL and the opening 4b is L1 and the length of the side wall 9a is L2, L2 / L1 is preferably 0.5 or more, and L2 / L1 is, for example, 0.5 to 1 , Specifically, for example, 0.5, 0.6, 0.7, 0.8, 0.9, 0.95, 1 and within the range between any two of the numerical values exemplified here. It may be. In the present embodiment, the side wall 9a is connected to the parting line PL. By connecting the side wall 9a to the parting line PL, the deformation of the opening 4b is particularly suppressed.

  Assuming that the distance from the outer surface of the facing wall 6d to the opening surface P is H1 and the distance from the outer surface of the facing wall 6d to the parting line PL is H2, H2 / H1 is preferably 0.7 or less and 0.5 or less More preferable. In this case, since the opening 4b is separated from the parting line PL and the opening 4b is particularly easily deformed, the significance of suppressing the deformation of the opening 4b by providing the rib 9 is particularly remarkable. H2 / H1 is, for example, 0 to 0.7, and specifically, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 It may be in the range between any two of the numerical values exemplified here.

  The ribs 9 are provided so as to increase in depth as they move away from the opening 4 b. Assuming that the depth at the deepest portion of the rib 9 is D and the thickness of the bottom wall 9 b of the rib 9 is T, D / T is preferably 2 or more. D / T is, for example, 2 to 20, and specifically, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, any of the numerical values exemplified here. It may be in the range between or two. The larger the thickness T, the more easily the opening 4b is deformed. However, by increasing the depth D, the deformation suppressing effect is enhanced. Therefore, by setting the value of D / T in the above range, the thickness of the molded article 5 is obtained. Regardless of the thickness, deformation of the opening 4b can be effectively suppressed.

  As shown in FIG. 4, the parting line PL on the side wall 6c is provided along the long side 4c at a position adjacent to the long side 4c. A beam 28 projecting from the side wall 6c is provided on the parting line PL. The beam portion 28 is provided along the long side portion 4 c, and the beam portion 28 suppresses the deformation of the long side portion 4 c.

3. Molded Article of Second Embodiment and Method of Manufacturing the Same A molded article of a second embodiment of the present invention and a method of manufacturing the same will be described with reference to FIGS. This embodiment is similar to the first embodiment, and the difference in the shape of the rib is the main difference. The differences will be mainly described below.

3.1 Molded Body Forming Step In this step, as shown in FIGS. 1 and 6, as in the first embodiment, the molten resin 11a is molded to provide a cylinder having the closed portions 3a and 4a at one end. The molded body 10 having the parts 3 and 4 is formed.

2.2 Excision Step In this step, as shown in FIGS. 6 to 7, the blocking portions 3 a and 4 a are excised by cutting the cylindrical portions 3 and 4 along a cutting line S indicated by an alternate long and short dash line. By this, as shown in FIGS. 7-8, opening 3b, 4b is formed in cylinder parts 3 and 4, and molded article 5 is obtained. Although a force to deform the opening 4b is generated along with the removal of the closed portion 4a, in the present embodiment, the beam rib 31 and the rib 32 are provided at positions adjacent to the cylindrical portion 4 and the opening 4b. It is suppressing the deformation.

  The basic configuration of the base 6 is the same as that of the first embodiment, but in the present embodiment, as shown in FIGS. 8 to 9, the side wall 6b is configured by a standing wall 6b1 and an inclined wall 6b2. The standing wall 6b1 stands substantially perpendicularly to the opening surface P. The inclined wall 6b2 is inclined with respect to the standing wall 6b1. The angle β between the opening surface P and the inclined wall 6 b 2 is preferably 5 to 70 degrees, and more preferably 10 to 45 degrees. Specifically, the angle β is, for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70 degrees, and any one of the numerical values exemplified here It may be in the range between two.

  The beam rib 31 is provided between the parting line PL and the opening 4 b. The beam rib 31 is configured by a groove-like recess, and is provided along the long side 4c and the pair of short sides 4d on the side wall 6b. The rigidity of the periphery of the opening 4 b is enhanced by the beam rib 31. On the side wall 6c side, a parting line PL is provided along the long side 4c at a position adjacent to the long side 4c, and a beam 28 is provided along the parting line PL to enhance rigidity. There is.

  In the side wall 6b, the beam rib 31 is provided on the inclined wall 6b2. The beam rib 31 is formed such that a bottom wall 31a and a side wall 31b are formed on the inclined wall 6b1, as shown in FIGS. In the cross-sectional view of FIG. 9, the inclined wall 6b1, the bottom wall 31a, and the side wall 31b have a substantially triangular shape. The bottom wall 31 a is substantially parallel to the opening surface P. The angle between the bottom wall 31 a and the opening surface P is preferably 0 to ± 30 degrees. Specifically, this angle is, for example, -30, -20, -10, 0, 10, 20, 30 degrees, and may be in the range between any two of the numerical values exemplified here. The angle θ between the side wall 31 b and the opening surface P is preferably 60 to 120 degrees, and more preferably 75 to 105 degrees. Specifically, the angle θ is, for example, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, and 120 degrees, and between any two of the values exemplified here. It may be in the range of

  A plurality of ribs 32 are connected to the beam rib 31. The rib 32 is provided to extend from the beam rib 31 toward the opening 4 b. The rib 32 is provided to connect the bottom wall 31 a and the side wall 31 b of the beam rib 31. The rib 32 is provided in a groove-like recess that constitutes the beam rib 31. The rib 32 further enhances the rigidity of the peripheral edge of the opening 4b.

  Assuming that the distance from the outer surface of the facing wall 6d to the opening surface P is H1 and the distance from the outer surface of the facing wall 6d to the parting line PL is H2, H2 / H1 is preferably 0.7 or less and 0.5 or less More preferable. In this case, since the opening 4b is separated from the parting line PL and the opening 4b is particularly easily deformed, the significance of suppressing the deformation of the opening 4b by providing the rib 9 is particularly remarkable. H2 / H1 is, for example, 0 to 0.7, and specifically, for example, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 It may be in the range between any two of the numerical values exemplified here.

1: molding machine 2: resin supply device 3: cylindrical portion 3a: closed portion 3b: opening 4: cylindrical portion 4a: closed portion 4b: open portion 4c: long side 4d: short side 4e: corner 5: molded Article 6: Base 6a: Base wall 6b: Side wall 6b1: Standing wall 6b2: Inclined wall 6c: Side wall 6d: Opposite wall 8: Rib 9: Rib 9a: Side wall 9b: Bottom wall 9c: End wall 10: Molded body 11: Raw material resin 11a: molten resin 12: hopper 13: extruder 13a: cylinder 16: injector 17: accumulator 17a: cylinder 17b: piston 18: head 19: split mold 23: parison 25: connecting pipe 27: connecting pipe 28: beam Section 31: Beam rib 31a: Bottom wall 31b: Side wall 32: Rib P: Opening surface PL: Parting line S: Cutting line T: Thickness α: Angle β: Angle θ: Angle

Claims (15)

A molded article comprising a tubular base and an opening provided in the base,
A molded article, wherein a rib is provided at a position adjacent to the opening.   The molded article according to claim 1, wherein the rib is provided between the parting line of the molded article and the opening.   The molded article according to claim 2, wherein L2 / L1 is 0.5 or more, where L1 is the distance between the parting line of the molded article and the opening, and L2 is the length of the side wall of the rib. .   The molded article according to claim 2, wherein side walls of the rib are provided to be connected to the parting line.   The molded article according to any one of claims 2 to 4, wherein the rib is provided so as to increase in depth with distance from the opening.   The depth according to any one of claims 2 to 5, wherein D / T is 2 or more, where D is the depth at the deepest part of the rib and T is the thickness of the bottom wall of the rib. Molding. The molded article includes a beam rib provided along the periphery of the opening,
The molded article according to claim 1, wherein the beam rib is provided between the parting line of the molded article and the opening.   The molded article according to claim 7, wherein the rib is provided to connect to the beam rib.   The molded article according to claim 7 or 8, wherein a plurality of said ribs are provided to be connected to said beam rib.   The molded article according to any one of claims 7 to 9, wherein the beam rib is constituted by a groove-like recess provided along the peripheral edge.   The molded article according to claim 10, wherein the rib is provided in the groove-like recess.   The peripheral edge of the opening includes a pair of long sides facing each other, and a pair of short sides provided to connect the pair of long sides. Articles described in.   The molded article according to claim 12, wherein the rib is provided at the center of the long side.   The molded article according to any one of claims 1 to 13, wherein the molded article is a foam molded article. Equipped with a forming process and a cutting process,
In the molded body forming step, a molded body is formed by molding a molten resin,
The molded body includes a cylindrical base, a cylindrical portion provided to rise from the base, and a rib at a position adjacent to the cylindrical portion.
The cylindrical portion is provided with a closed portion at one end,
In the cutting step, the closed portion is cut off by cutting the cylindrical portion to form an opening.