JP5410139B2 - Method for manufacturing a luggage box for vehicles - Google Patents

Description

  The present invention relates to a method for manufacturing a luggage box for a vehicle, which is molded from a thermoplastic foamed resin sheet.

  A luggage box is a box that is installed on the cargo floor of an automobile and stores luggage, tools, etc., but the luggage compartment floor of the automobile is provided with a spare tire storage section, and the luggage box is a spare tire storage section. Placed on top.

  Since this luggage box is required to be shock-absorbing and lightweight in the luggage compartment at the rear of the vehicle body, foamed resin injection molded products have been widely used. In the case of products, the required strength cannot be obtained unless the wall thickness is considerably increased. Therefore, the conventional luggage box of this type is limited in pursuing further light weight while maintaining the required strength. was there.

  Patent Document 1 (Japanese Patent Laid-Open No. 10-29466), Patent Document 2 (Japanese Patent Laid-Open No. 2001-213239) and Patent Document 3 (WO 2006-11332) describe a luggage box made of an injection molded product of foamed resin and its A manufacturing method is disclosed.

JP-A-10-29466 JP 2001-213239 A WO2006-11332 publication

  The present invention forms a luggage box storage chamber and a partition wall in the storage chamber with a thermoplastic foam resin sheet made of a thermoplastic resin composition having an MFR (melt flow rate) of 8.0 to 0.1 g / 10 min. By forming a luggage box using a mold having a convex cavity for forming a convex rib and a flange protruding around the opening, the luggage box is thin and lightweight, and has the required strength. The present invention provides a method for manufacturing a luggage box for a vehicle capable of obtaining a luggage box.

The method for manufacturing a luggage bag for vehicles according to the present invention is a method for manufacturing a luggage box for vehicles molded from a thermoplastic foamed resin sheet, and the thermoplastic foamed resin sheet has an MFR at 230 ° C. of 8.0 to 0.00. A pair of split molds, which are made of a thermoplastic resin composition of 1 g / 10 min and mold a luggage box, have a luggage box storage chamber in one mold, convex ribs and openings that form partition walls in the storage chamber It has a convex cavity for molding a flange projecting to the periphery, and the thermoplastic foamed resin sheet disposed between the pair of split molds and the one convex cavity are closed and vacuum is formed from the surface of the convex cavity. With the thermoplastic foam resin sheet sucked and adsorbed in the convex cavity, the storage chamber with the upper surface opened, the flange projecting around the opening, and this A luggage box having a concave rib integrally forming a partition wall having a flat portion having the same height as that of the flange is formed.

  In the present invention, a pair of split dies having a compression molding portion that forms a stable support surface between the vehicle body and the periphery of the luggage box is used, and the spare tire stored in the spare tire storage chamber on the bottom surface of the luggage box. A pair of split molds having a flat portion that forms a stable support surface between them, and the luggage box has a foaming ratio of 2.0 to 30 times and a wall thickness of the bottom wall of 2.0 to It is preferable that it is 50 mm.

  According to the method for manufacturing a luggage bag for a vehicle according to the present invention, the storage box of the luggage box, the storage, and the storage by the thermoplastic foamed resin sheet made of a thermoplastic resin composition having an MFR of 8.0 to 0.1 g / 10 min. The luggage box is molded using a mold that has a convex rib that forms a partition wall in the room and a convex cavity that molds a flange that protrudes around the opening, so that it is thin and lightweight. A luggage box having the required strength can be obtained.

It is sectional drawing which shows an example of the shaping | molding apparatus which enforces the manufacturing method of the luggage box for vehicles which concerns on this invention, Comprising: The process which has arrange | positioned the thermoplastic foamed resin sheet in a pair of division mold is shown. It is a fragmentary sectional view which shows the process of closing between the mold cavity corresponding to the thermoplastic foam resin sheet arrange | positioned in a pair of division | segmentation metal mold | die in the shaping | molding apparatus of FIG. FIG. 3 is a partial cross-sectional view showing a step of forming a thermoplastic foamed resin sheet by vacuum suction into a convex cavity of a corresponding mold from the embodiment shown in FIG. 2 in the molding apparatus of FIG. 1. FIG. 4 is a partial cross-sectional view showing a process of opening a mold and taking out a molded product from the embodiment of FIG. 3 in the molding apparatus of FIG. 1. It is a perspective view of the luggage box for vehicles shape | molded in the shaping | molding apparatus of FIG. It is AA sectional drawing of FIG. It is a perspective view which shows the luggage compartment floor of the motor vehicle which installs the luggage box for vehicles which concerns on this invention.

  1 to 4, 1 is a T die, and 2 and 3 are a pair of split molds, and a thermoplastic foam resin sheet in a molten state is extruded from the T die 1 to be between the pair of split molds 2 and 3. Hang down. In the pair of split molds 2 and 3, one mold is indicated as 2 and the other mold is indicated as 3. The T-die 1 includes a resin supply device (not shown) including an accumulator, a plunger, an extruder, a thermoplastic foamed resin supply hopper, and the like. 4 and 4 are a pair of rollers. One mold 2 of the pair of split molds 2 and 3 has a convex cavity 5. The convex cavity 5 has a luggage box storage chamber, a convex rib forming a partition wall in the storage chamber, and a molding portion for molding a flange projecting around the opening. Reference numeral 6 denotes a storage chamber molding portion. Is a convex rib forming part forming a partition wall, and 8 is a flange forming part. The convex cavity 5 is provided with a number of suction vents 9, and 10 is a vacuum chamber. The other mold 3 is provided with a slide mold 11 on the outer periphery thereof, and the cavity 12 is provided with compression molding portions 13 and 13. The compression molding portions 13 and 13 are for forming a stable support surface between the spare tire stored in the spare tire storage chamber on the bottom surface of the luggage box, which will be described later. The other mold 3 is provided with a pressure fluid introduction hole 14 for introducing a pressure fluid into the mold.

  The vehicle luggage box 15 shown in FIGS. 5 and 6 is formed according to the embodiment shown in FIGS. That is, the molten thermoplastic foam resin sheet 16 for molding the vehicle luggage box 15 is pushed out from the T-die 1 and fed out by the pair of rollers 4, 4 and suspended between the pair of divided molds 2, 3. (FIG. 1). Next, the slide mold 11 of the other mold 3 is moved forward to support the hanging thermoplastic foam resin sheet 16 (FIG. 2), and then the mold 2 is moved forward to heat the convex cavity 5. The space between the plastic foam resin sheet 16 is closed, and the vacuum is sucked into the convex cavity 5 in one mold 2 to be along the convex cavity 5, and the other mold 3 is advanced to make a pair of split molds 2. , 3 is closed and a pressure fluid is introduced into the other mold 3 to mold the thermoplastic foam resin sheet 16 into a shape that is surely aligned with the convex cavity 5 (FIG. 3). And in this process, while forming the stable support surfaces 20 and 20 between the spare tires stored in the spare tire storage chamber on the bottom surface of the luggage box by the compression molding portions 13 and 13, the pair of split molds 2 and 3 A plurality of stable support surfaces 17 between the vehicle body are formed around the luggage box by the compression molding portions by the pinch-off portions 18 and 19. Thereafter, the pair of split molds 2 and 3 are opened to take out the formed luggage bix (FIG. 4).

  The thermoplastic foamed resin sheet 16 suspended between the pair of split molds 2 and 3 has a sheet thickness, an extrusion speed, and an extrusion direction in order to prevent occurrence of thickness variation due to drawdown, neck-in, or the like. It is necessary to adjust the thickness distribution separately. That is, the thermoplastic foamed resin sheet 16 is melted and kneaded with a thermoplastic resin added with a foaming agent by an extruder, and then temporarily stored in the accumulator chamber of the accumulator. Supplied. The thermoplastic foam resin sheet 16 extruded from the T-die 1 is sandwiched between a pair of rollers 4 and 4 and disposed between a pair of split molds 2 and 3. At this time, the thickness and thickness distribution of the thermoplastic foam resin sheet 16 are adjusted.

Specifically, first, the extrusion speed is set individually by the accumulator and the T die 1. The extrusion capability of the extruder connected to the accumulator can be appropriately selected depending on the size of the vehicle luggage box 15, but is preferably 50 kg / hour or more from the viewpoint of shortening the molding cycle. Further, from the viewpoint of preventing the occurrence of drawdown, the extrusion process of the thermoplastic foam resin sheet 16 from the T-die 1 needs to be completed within 40 seconds, more preferably within 30 seconds. For this reason, the thermoplastic foamed resin stored in the accumulator of the accumulator is extruded from the opening of the slit of the T-die 1 at 50 kg / hour or more, preferably 60 kg / hour or more per 1 cm ² . At this time, the influence of the drawdown can be minimized by changing the slit gaps of the T-die 1 together with the extrusion of the thermoplastic foam resin sheet 16. That is, the thickness of the thermoplastic foamed resin sheet 16 is increased by gradually widening the slit gap from the start of extrusion against the thickness of the thermoplastic foamed resin sheet 16 that is stretched and thinned by its own weight due to the drawdown phenomenon. It is possible to adjust the thickness to a uniform thickness from the upper side to the lower side of the thermoplastic foamed resin sheet 16 by extruding it thicker upward. Further, the extrusion speed of the thermoplastic foam resin sheet 16 from the T die 1 is changed by changing the rotational speed of the pair of rollers 4 and 4 with respect to the extrusion speed of the thermoplastic foam resin sheet 16 extruded from the T die 1. The thickness of the sheet can be adjusted to be thin by stretching the thermoplastic foam resin sheet 16 between the T die 1 and the pair of rollers 4 and 4.

  The thermoplastic foamed resin respectively supplied to the T-die 1 is extruded as a sheet from the slit through a resin flow path from a manifold of the T-die main body (not shown). The main body of the T die 1 is formed by superimposing one die and the other die, and one die lip and the other die lip are opposed to each other with a slit gap at a tip portion of the main body of the T die 1. It is set by the slit clearance adjusting device. Although the thickness of the thermoplastic foamed resin sheet 16 extruded by a slit clearance is determined, specifically, it is extruded from the T die 1 as a thermoplastic foamed resin sheet 16 having a thickness of 0.6 to 6.0 mm. The accumulator can be a side accumulator system or a ring accumulator system.

  The slit gap is adjusted for uniformity in the width direction of the sheet by a known slit gap adjusting device. Further, the thickness of the sheet in the extrusion direction is adjusted by changing the other die lip from the start to the end of the extrusion of the thermoplastic foam resin sheet 16 that is intermittently extruded by a slit gap driving device (not shown). As the slit gap adjusting device, there are a thermal expansion type and a mechanical type, and it is preferable to use a device having both functions. A plurality of slit gap adjusting devices are arranged at equal intervals along the width direction of the slit, and the thickness of the thermoplastic foam resin sheet 16 in the width direction is reduced by narrowing or widening the slit gap by each slit gap adjusting device. Be uniform.

  The slit clearance adjusting device has a die bolt provided so as to be able to advance and retreat toward one die lip, and an adjustment shaft is disposed at the tip of the die bolt via a pressure transmission unit. An engagement piece is coupled to the adjustment shaft by a fastening bolt, and the engagement piece is connected to one die lip. When the die bolt is moved forward, the adjustment shaft is pushed out in the distal direction through the pressure transmission portion, and one die lip is pressed. As a result, the die lip is deformed at the portion of the concave groove, and the slit gap is narrowed. To widen the slit gap, the die bolt is moved backward. Furthermore, the slit gap can be adjusted with high accuracy by using a thermal expansion type adjusting means in accordance with the mechanical adjusting means. Specifically, one die lip is pressed by heating the adjustment shaft by an electric heater (not shown) to cause thermal expansion, thereby narrowing the slit gap. In order to widen the slit gap, the electric heater is stopped, and the adjusting shaft is cooled and contracted by a cooling means (not shown).

  The thermoplastic foamed resin sheet 16 extruded from the T-die 1 is adjusted so that the thickness in the extrusion direction is uniform when it is suspended between the pair of split molds 2 and 3, that is, when the mold is clamped. Is preferred. In this case, the slit gap is gradually widened from the start of extrusion and is varied so as to become maximum at the end of extrusion. As a result, the thickness of the thermoplastic foam resin sheet 16 extruded from the T-die 1 gradually increases from the start of extrusion, but the thermoplastic foam resin sheet 16 extruded in a molten state is stretched by its own weight and from below to above. Since the thickness is gradually reduced, the thickness of the slit gap that is widened and the thickness that has been stretched by the draw-down phenomenon cancel each other, and the thermoplastic foam resin sheet 16 can be adjusted to a uniform thickness from above to below. it can.

  As the foaming agent used in the present invention, any of physical foaming agents, chemical foaming agents and mixtures thereof may be used. As physical foaming agents, inorganic physical foaming agents such as air, carbon dioxide, nitrogen gas, and water, and organic physical foaming agents such as butane, pentane, hexane, dichloromethane, dichloroethane, and their supercritical fluids are used. be able to. As the supercritical fluid, carbon dioxide, nitrogen or the like is preferably used. If nitrogen, the critical temperature is 149.1 ° C. and the critical pressure is 3.4 MPa or more. If carbon dioxide, the critical temperature is 31 ° C. and the critical pressure is 7 It is obtained by setting it to 4 MPa or more.

  As the polypropylene resin used for the blend resin constituting the vehicle luggage box 15 according to the present invention, polypropylene having a melt tension (abbreviated as MT) at 230 ° C. in the range of 30 to 350 mN is used. In particular, the polypropylene resin is preferably a propylene homopolymer having a long chain branched structure, and more preferably an ethylene-propylene block copolymer is added.

  The hydrogenated styrene-based thermoplastic elastomer blended with the resin is 5 to 40 wt%, preferably 15 with respect to the polypropylene-based resin in order to improve impact resistance and maintain rigidity as a luggage box. It is added in a range of ˜30 wt%. Specifically, a hydrogenated polymer such as a styrene-butadiene-styrene block copolymer, a styrene-isoprene-styrene block copolymer, or a styrene-butadiene random copolymer is used. Further, the hydrogenated styrene thermoplastic elastomer has a styrene content of less than 30 wt%, preferably less than 20 wt%, and an MFR at 230 ° C. of 8 g / 10 min or less is 0.1 g / 10 or more, preferably 5. 0 g / 10 min or less and 1.0 g / 10 min or more.

Moreover, as a polyolefin-type polymer blended with the said resin, a low density ethylene-alpha olefin is preferable and can be mix | blended in 1-20 wt%. An ethylene / α-olefin copolymer obtained by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms is used as the low-density ethylene-α olefin having a density of 0.91 g / cm ³ or less. Are preferred, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4-methyl-1-pentene, 4-methyl. -1-hexene and the like, preferably 1-butene, 1-hexene, and 1-octene are used. Moreover, said C3-C20 alpha olefin may be used independently and may use 2 or more types together. Content of the monomer unit based on ethylene in the ethylene / α-olefin copolymer is in the range of 50 to 99 wt% with respect to the ethylene / α-olefin copolymer. The content of the monomer unit based on the α-olefin is in the range of 1 to 50 wt% with respect to the ethylene / α-olefin copolymer. In particular, it is preferable to use a linear ultra-low density polyethylene polymerized using a metallocene catalyst, an ethylene elastomer, or a propylene elastomer.

  The thermoplastic foam resin sheet 16 suspended in the pair of split molds 2 and 3 prevents the occurrence of wall thickness variation due to drawdown, neck-in, etc. From the viewpoint of obtaining a duct having heat insulation properties, it is necessary to use a material having a high melt tension. Specifically, the MFR at 230 ° C. (measured at a test temperature of 230 ° C. and a test load of 2.16 kg according to JIS K-7210) is 5.0 g / 10 min or less, more preferably 1.5 to 3.0 g / 10 minutes. In general, from the viewpoint of extruding thinly from the slit of the T-die 1, MFR at 230 ° C. is larger than 3.0 g / 10 min in molding of a film or the like, specifically 5.0 to 10.0 g / 10 min. It is used. Further, MT is important for the thermoplastic foamed resin sheet 16 because foamability causes the drawdown to peel off and to prevent foam breakage. It is necessary that the composition is a resin composition having an MT of 2 to 8 cN (23 ° C.), preferably 3 to 6 cN (23 ° C.).

  As shown in FIGS. 5 and 6, the luggage box 15 according to the present invention includes a storage chamber 21 having an upper surface opened, 22 a flange projecting around the opening, and 23 a partition wall. The partition wall 23 is formed by a convex rib 24, and the convex rib 24 has a flat portion 25 having the same height as the flange 22. For this reason, the lid body 26 covered with the vehicle luggage box 15 is supported by the peripheral flange 22 and the flat portion 25 of the partition wall 23 located inside thereof, and maintains a stable posture, and the lid body 26 has luggage and the like. Deformation and the like are surely prevented even when a load of. Further, since the concave ribs 24 forming the partition wall 23 have a shape that is spaced downward, the overall rigidity and strength of the luggage box are thereby improved.

  In a state in which the vehicle luggage box 15 according to the present invention is installed on the luggage compartment floor 27 of the automobile, the flat portion 20 forming a stable support surface around the luggage box is supported in a stationary state on the vehicle body side 28, and the luggage Since the stable support surfaces 17 and 17 on the bottom surface of the box are supported by the spare tire 30 stored in the spare tire storage portion 29, there is no possibility that the luggage box will float or fluctuate due to vibration, shaking or impact of the vehicle body. The shock absorbing effect by the box can be expected. Since the flat portion 20 forming the stable support surface around the luggage box and the stable support surfaces 17 and 17 on the bottom surface of the luggage box are both formed by compression molding, the surface has high smoothness and stable support. It is excellent.

DESCRIPTION OF SYMBOLS 1 T die 2,3 A pair of division molds 4,4 A pair of rollers 5 Convex cavity 6 Storage chamber shaping | molding part 7 Convex rib shaping | molding part 8 Flange shaping | molding part 9 Suction ventilation path 10 Vacuum chamber 11 Slide mold 12 Cavity 13 , 13 Compression molding portion 14 Pressure fluid introduction hole 15 Luggage box for vehicle 16 Thermoplastic foam resin sheet 17 Plural stable support surfaces 18, 19 Pinch-off portions 20, 20 Stable support surfaces 21 Storage chamber 22 Flange 23 Partition wall 24 Convex rib 25 Flat part 26 Lid 27 Cargo floor 28 Car body side 29 Spare tire storage part 30 Spare tire

Claims (4)

A method for manufacturing a luggage box for a vehicle formed by a thermoplastic foam resin sheet,
The thermoplastic foamed resin sheet is composed of a thermoplastic resin composition having an MFR at 230 ° C. of 8.0 to 0.1 g / 10 min.
A pair of split molds for forming a luggage box has a convex cavity for molding a luggage box storage chamber, a convex rib forming a partition wall in the storage chamber, and a flange projecting around the opening. And
Close the space between the thermoplastic foam resin sheet disposed between the pair of split molds and the one convex cavity and vacuum suction from the convex cavity surface,
Luggage integrally including a storage chamber having an upper surface opened by a thermoplastic foam resin sheet adsorbed in the convex cavity, a flange projecting around the opening, and a concave rib forming a partition wall having a flat portion equal to the flange. A method for manufacturing a luggage box for a vehicle, characterized by forming a box.   2. The method for manufacturing a luggage box for a vehicle according to claim 1, wherein a pair of split molds having a compression molding portion for forming a stable support surface between the luggage box and the periphery of the luggage box is used.   3. A vehicle according to claim 1 or 2, wherein a pair of split molds having a compression molding part for forming a stable support surface between the spare tire housed in the spare tire housing part on the bottom surface of the luggage box is used. Luggage box manufacturing method.   4. The method of manufacturing a luggage box for a vehicle according to claim 1, wherein the luggage box has an expansion ratio of 2.0 to 30 times and a wall thickness of the bottom wall of 2.0 to 50 mm. .

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