JP2001328133A - Method and apparatus for in-mold foam molding of thermoplastic synthetic resin, and in-mold foamed molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for the in-mold foam molding of a thermoplastic synthetic resin, capable of enhancing the quality of a molded article having a molded portion comprising raw material beads different in characteristics, and an in-mold foamed molded article. SOLUTION: A molding space 13 is demarcated into a plurality of demarcated molding spaces 13A and 13B by partition members 33 and 34 and at least the adjacent demarcated molding spaces 13A and 13B are individually filled with the raw material beads different in characteristics in such as state that the inner pressures of the raw material beads are set corresponding to the characteristics thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for in-mold foam molding of a thermoplastic synthetic resin suitable for forming a molded part comprising raw material beads having different characteristics in one molded article, and an in-mold foam molded article. About.

[0002]

2. Description of the Related Art An in-mold foam molding apparatus for producing a molded article using raw material beads made of a thermoplastic synthetic resin is disclosed in, for example, U.S. Pat. No. 5,164,257. Providing a partition member that can be retracted and retracted in the molding space, partitioning the molding space into a plurality of partition molding spaces by this partition member, and individually connecting fillers that supply raw material beads to each partition molding space, In the state where the inside of the molding space is partitioned by the partition member,
In the adjacent section forming space, for example, raw material beads having different expansion ratios are filled, and after filling, the partition member is retracted, and then steam is supplied into the forming space. An in-mold foam molding technique configured to obtain the following is described.

[0003] In a molded article formed by this in-mold foam molding technique, it is possible to produce a molded article having different mechanical properties depending on the portion, for example, by changing the raw material beads to be used depending on the portion of the molded product. It has the advantage of improving the performance and quality of molded articles, and is being used as a core material for automobile bumpers and as a cushioning material for packing home appliances, furniture and the like.

[0004] On the other hand, raw material beads made of polyolefin resin such as polyethylene resin or polypropylene resin generally have lower foaming power than raw material beads made of polystyrene resin. It does not swell sufficiently, and the adhesion between beads may decrease,
The quality of the molded product is reduced, for example, a large groove is formed between the beads and the appearance is reduced. For this reason, as a technique for filling raw material beads made of a polyolefin-based resin, a filling technique in which an inorganic gas of 0.03 to 0.2 MPa is preliminarily injected into the raw material beads to increase the foaming power has been widely adopted.

[0005]

By the way, in the molding apparatus described in the above-mentioned U.S. Patent, when a molded product is produced by filling raw material beads having different expansion ratios into adjacent partitioned molding spaces, heat fusion of the raw material beads is performed. Occasionally, there is a difference in the foaming pressure between different types of raw material beads, and the boundary surface of the different type of raw material beads is entirely displaced or the boundary surface is curved, and the desired quality cannot be obtained. there were. In addition, since such a displacement or deformation of the boundary surface also changes due to classification of the raw material beads during pneumatic transportation, fluctuations in external temperature conditions between each molding shot, and the like, it is extremely difficult to appropriately adjust them. Was thought to be.

As another problem, in the molding apparatus described in the above-mentioned US Patent Publication, it is necessary to provide an actuator for extending and retracting the partition member. Therefore, as the number of partitions in the molding space increases, the partition member is correspondingly increased. If the control system is not controlled so that the pressure difference does not occur in the filling pressure in the adjacent partitioned molding space, there is a concern that the partition member may be deformed unless the drive system becomes complicated and the manufacturing cost of the molding device increases. That the flow of the filling air is obstructed by the partitioning member and the filling property of the raw material beads is reduced, and the molding is performed because the insertion hole is formed in the mold and the partitioning member is attached to the insertion hole so as to be able to come and go freely. Burrs are formed along the insertion holes on the surface of the product, and there are problems such as deterioration in appearance.

The applicant of the present invention pays attention to the fact that the problem in the molding apparatus described in the above-mentioned US Patent is caused by arranging the plate-shaped partition member to be movable, and uses the comb-shaped partition member as a mold. Are being developed, and a molding device configured to partition the inside of the molding space into a plurality of divided molding spaces by this partition member is being developed. However, also in this molding apparatus, when the raw material beads having different expansion ratios are filled because the raw material beads are heated and fused while the partition member is left in the molding space, the difference in the foaming pressure of the raw material beads is obtained. As a result, the boundary surface is deformed, and the comb teeth are deformed together with the boundary surface, so that there is a problem that it is difficult to release the molded product or the quality of the molded product is deteriorated. In addition, if a large-diameter comb tooth is used to prevent deformation of the comb teeth, a large bottomed hole or through-hole is formed in the molded product, and the appearance or strength of the molded product is reduced. Therefore, there has been a demand for a technique for preventing a differential pressure from being generated in the foaming pressure of the raw material beads during heat fusion.

It is an object of the present invention to provide a method and apparatus for in-mold foam molding of a thermoplastic synthetic resin and an in-mold foam molded article capable of improving the quality of a molded article having a molded portion composed of raw material beads having different characteristics. It is.

[0009]

According to the first aspect of the present invention, there is provided a method for in-mold foam molding of a thermoplastic synthetic resin. When the raw material beads are individually filled into each compartment forming space so that the raw material beads having different characteristics are filled in the space, the internal pressure of the raw material beads is set according to the characteristics, and each compartment forming space is filled. The inside is filled with raw material beads.

In this molding apparatus, in a state where the molding space is divided into a plurality of divided molding spaces by the partition member, the adjacent divided molding spaces can be filled with the raw material beads having different characteristics. By appropriately setting the position, size, and characteristics of the raw material beads to be filled, the performance and quality of the molded product can be improved. For example, for parts where the strength is important, the strength and rigidity of the molded product are increased by using raw material beads having a low expansion ratio, and for other parts, the weight of the molded product is reduced by using raw material beads having a high expansion ratio, It is possible to improve the strength of the molded product and reduce the weight at the same time.

Further, since the internal pressure of the raw material beads is set in accordance with the characteristics, it is possible to appropriately adjust the foaming pressure at the time of heat fusion for each of the raw material beads having different characteristics. Specifically, the raw material beads are filled in each section forming space in a state where the internal pressure of the raw material beads is set according to the characteristics so that the foaming pressure during the heat fusion of the raw material beads is substantially uniform. By doing so, when using a plate-like member as the partition member, it is possible to prevent displacement or deformation of the boundary surface of the raw material beads having different characteristics, and when using a comb tooth as the partition member, deformation of the comb teeth is prevented. It is possible to improve the mold releasability of the molded product from the comb teeth and to use a small-diameter comb tooth, and to reduce the diameter of the through-hole or bottomed hole formed in the molded product by the comb teeth. By setting it small, the strength and appearance of the molded product can be improved.

The filling of the raw material beads into each of the molding spaces can be performed by a known filling method such as cracking filling, pressure filling, compression filling, etc. In order to minimize as much as possible, it is preferable to compress and fill the raw material beads under substantially the same compression conditions.

As raw material beads, expansion ratio, base resin composition, crystallization structure, particle size, particle shape, particle weight,
Raw material beads differing in one or two or more characteristics of the cell diameter and color in the particle can be employed. Since these properties affect the foaming pressure of the raw material beads other than the color,
It is suitable for applying the present invention to adjust the foaming pressure.
Basically, under the same heating conditions, as the expansion ratio increases, the expansion pressure tends to increase, and the crystallized structure tends to decrease the expansion pressure as the degree of crystallinity increases. As the foaming pressure increases, the foaming pressure tends to increase.As the particle shape increases, the foaming pressure tends to decrease as the surface area per unit weight increases, and as the particle weight increases, the foaming pressure tends to increase. As the diameter increases, the foaming pressure tends to increase. Also, the base resin is
Due to the different compositions, for example, the melting point and MI (melt index) show different values. In general, under the same heating conditions, the foaming pressure tends to decrease as the melting point increases, and the foaming pressure increases as the MI increases. In the present invention, the internal pressure of the raw material beads is adjusted according to these characteristics.

Also, in actual raw material beads, adjusting one property often changes the other property.
Although it is difficult to make a qualitative judgment because it is difficult to configure only the two characteristics to be different, basically, raw material beads with different expansion ratios are used as raw material beads, and raw material beads with low expansion ratio are used. It is preferable to set the internal pressure higher than the internal pressure of the raw material beads having a high expansion ratio, because the above-described operation can be obtained. However, even when raw material beads having different expansion ratios are used as raw material beads, when other characteristics are different, the internal pressure of the raw material beads having a low expansion ratio is set to be equal to or less than the internal pressure of the raw material beads having a high expansion ratio. Then, the foaming pressure may be adjusted.

The filling of the raw material beads into the plurality of compartment forming spaces may be performed simultaneously or with a time difference. In addition, the thing consisting of a comb tooth was used as a partition member,
Moreover, when the interval between the comb teeth is set to an interval at which at least one kind of raw material beads can pass through, the raw material beads that cannot pass through are filled, and then the raw material beads that can pass through are filled.

Further, when at least one kind of raw material beads is temperature-controlled and filled into each of the molding spaces, the variation in the expansion ratio of the molded product between molding shots is reduced, and the variation in the weight of the molded product is reduced. It is preferable because it is possible. In addition, since the degree of compression of the raw material beads during compression filling can be adjusted by adjusting the temperature, foaming can be achieved by adjusting the internal pressure and temperature of the raw material beads by setting the temperature control temperature according to the characteristics of the raw material beads. Pressure and the like can be largely controlled.

It is preferable to compress the raw material beads into the molding spaces in the respective compartments while controlling the temperature to the same temperature, because the variation in the expansion ratio of the molded product between molding shots can be reduced and the variation in the weight of the molded product can be reduced. . Moreover, although the control width of the foaming pressure is reduced, the control is performed only by adjusting the internal pressure of the raw material beads, so that the control system can be significantly simplified.

An apparatus for in-mold foam molding of a thermoplastic synthetic resin according to the present invention comprises a mold having a partition member for dividing a molding space into a plurality of compartment molding spaces, and a raw material having different characteristics at least in adjacent compartment molding spaces. So that the beads are filled,
A filling means for individually filling the raw material beads into each of the compartment forming spaces, wherein the filling means is provided with an internal pressure adjusting means for adjusting the internal pressure of at least one kind of the raw material beads.

In this in-mold foam molding apparatus, since the internal pressure of at least one type of raw material beads can be adjusted by the internal pressure adjusting means, the raw material beads can be filled with the internal pressure adjusted appropriately, and the in-mold foam forming apparatus can be used. As in the case of the molding method, it is possible to appropriately adjust the foaming pressure at the time of heat fusion for each raw material bead having different characteristics.

As a partition member, a partition member having a plurality of comb teeth extending in a cantilever manner in a mold opening / closing direction at an interval where at least one of the raw material beads to be filled in the adjacent section forming space cannot pass therethrough is fixed to a mold. Then, although a through-hole or a bottomed hole is formed at a position corresponding to the comb teeth in the molded product, since the partition member is fixedly provided in the core mold or the cavity mold, the following operation is performed. Is obtained.

(1) Since a drive system for driving the partition member is not required, the molding apparatus can be configured to be much simpler, and the manufacturing cost of the molding apparatus can be reduced. (2) By changing the mounting position of the partition member, it is possible to easily change the partition area of the molding space, and it is possible to easily cope with a design change of the molded product. (3) Since the raw material beads having different characteristics filled in the adjacent section forming spaces are sufficiently fused to each other through the gap between the comb teeth, molding is performed using the raw material beads having different characteristics in the molded product. It is possible to sufficiently secure the joining strength of the formed molded portion. (4) Since it is not necessary to provide an insertion hole through which the partition member is inserted in the mold, the raw material beads enter the insertion hole or enter between the insertion hole and the partition member to form burrs. Failures can be reliably prevented. In addition, it is possible to prevent a partial decrease in the mold strength due to the formation of the insertion hole, and it is possible to improve the precision of the molded product.

Further, by setting the foaming pressure at the time of heat fusing of the raw material beads in the adjacent section forming space to be substantially the same, deformation of the comb teeth is prevented, and the releasability of the molded article from the comb teeth is improved. It is possible to improve the strength and appearance of the molded product by setting the diameter of the through hole and the bottomed hole formed in the molded product by the comb teeth to be small, while improving the comb teeth. .

As the comb teeth, it is preferable to use a rod-shaped member having a diameter of 1 to 10 mm. In other words, in this molding apparatus, the through-hole or the bottomed hole is formed in the molded product by the comb teeth as described above. Will be formed, causing a decrease in the strength of the molded product,
If the appearance of the molded article is reduced, and if the diameter of the comb teeth is set to be smaller than 1 mm, the strength of the comb teeth cannot be sufficiently secured, and the comb teeth may be damaged or deformed.

The interval between adjacent comb teeth is preferably set to 30 to 90% of the diameter of the raw material beads that cannot pass through. If the interval between adjacent comb teeth is too narrow, the adhesion between the raw material beads in the adjacent forming space with the comb teeth interposed therebetween cannot be sufficiently ensured, and the strength at the boundary portion decreases. In addition, since the raw material beads made of polyolefin resin are softer than the raw material beads made of polystyrene resin, if the interval between adjacent comb teeth is too wide, the raw material beads pass between the comb teeth of the partition member to form adjacent partitions. The problem of moving to space occurs.

Further, it is preferable that the comb teeth are made of a material which can be elastically deformed. In other words, in order to prevent the comb teeth from being deformed by receiving a filling pressure, a foaming pressure, or the like, it is preferable to set the cross-sectional area to be large to increase the strength and rigidity.
With such a configuration, a large through hole or a bottomed hole is formed in the molded product, which causes a decrease in the appearance and strength of the molded product. Therefore, the comb teeth are made of an elastically deformable material so that the comb teeth can be restored to the original shape even if the comb teeth are slightly deformed by the filling pressure or the foaming pressure. It is preferable that the cross-sectional area of the comb teeth is set as small as possible while preventing mold failure, so that a reduction in appearance and strength of the molded product can be suppressed.

The in-mold foam molded product according to the present invention has a plurality of molded portions molded using raw material beads having different characteristics, and the mold of the mold is provided at predetermined intervals along the boundary surface of each molded portion. A plurality of through holes or bottomed holes extending substantially straight in the opening and closing direction are formed. Such a molded article can be manufactured by the above-described in-mold foam molding apparatus having comb teeth, but since the through hole or the bottomed hole is substantially straight, the molded article from the comb teeth is formed. Since the releasability is good and the boundary surface of each molded part is not deformed, the dimensional accuracy is excellent, the weight variation is small, and the quality that can sufficiently secure the strength of the boundary surface is obtained. In addition, the boundary surface of each molded part may be configured as a flat surface, or may be configured as a triangular wave, a rectangular wave, a sine wave, or the like.

As a specific example of the in-mold foam molded product, a core material of an automobile bumper can be considered. Thus, the core material of the automobile bumper needs to efficiently absorb the impact at the time of a frontal collision (frontal collision) of an automobile, the impact at the time of an offset collision, and the impact at the time of an oblique frontal collision (oblique impact). In addition, in order to reduce the weight of the vehicle body, it is necessary to make the core material as light as possible. In the core material of an automotive bumper as an in-mold foam molded product according to the present invention, the vicinity of a portion that is susceptible to local impact stress acting on the core material at the time of various frontal collisions of an automobile is formed from raw material beads having a low expansion ratio. The low-foaming section is composed of high-foaming sections made of raw material beads having a higher expansion ratio than the low-foaming section, so that the core material is reduced in weight as much as possible during offset collisions and oblique collisions. Even at times, it becomes possible to effectively absorb impact energy.

[0028]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment,
This is a case where the present invention is applied to a core material of an automobile bumper as an in-mold foam molded article, an in-mold foam molding apparatus and an in-mold foam molding method for molding the same.

First, the core material of an automotive bumper as an in-mold foam molded product will be described. As shown in FIG. 1 and FIG. 2, the core material 1 has a front shock absorbing portion 2 having both ends gently curved rearward, and a side shock extending rearward from both ends of the front shock absorbing portion 2. And an absorbing section 3. In the lower half of the corner 4 extending from the front impact absorbing portion 2 to the side impact absorbing portion 3, a low foaming portion 5 made of raw material beads having a low expansion ratio is formed, and the other portions are smaller than the low foaming portion 5. It comprises a high foaming section 6 made of raw material beads having a high foaming ratio.

That is, the central portion of the front impact absorbing portion 2 is for absorbing the impact energy at the time of a frontal collision. However, since the pressure receiving area of the impact energy can be set large, the soft and lightweight high foaming ratio is obtained. The shock absorbers are made of raw material beads, and both ends of the front shock absorber 2 and the side shock absorbers 3 are for absorbing the impact energy at the time of offset collision or oblique impact. Since it is difficult to set large, it is heavier than the other parts, but by providing the low foaming part 5 made of hard raw material beads having a low expansion ratio, while ensuring sufficient collision safety performance in various frontal collisions, It is configured so that the weight of the core material 1 can be reduced as much as possible. Note that the length and height of the low foaming portion 5 can be set to any size as long as the impact energy acting on the core material 1 can be sufficiently absorbed. Further, in this embodiment, the low foaming portion 5 is formed only in the lower half of the corner portion 4 of the core material 1, but the entire corner portion 4 may be made of raw material beads having a low foaming rate.
Further, the external shape and size of the core material 1 can be arbitrarily set according to the vehicle to which the core material 1 is applied.

As shown in FIGS. 1 and 2, the low-foaming portion 5 and the high-foaming portion 6 are defined at a position of a substantially U-shaped boundary surface L in front view, and the boundary surface L extends rearward from the front surface. A plurality of bottomed holes 7 and a plurality of bottomed holes 8 extending forward from the rear surface are formed alternately at regular intervals. These bottomed holes 7, 8
Is formed by molding the core material 1 by an in-mold foam molding apparatus 10 described later, but may be formed by a through hole penetrating the core material 1 in the front-rear direction. However, the boundary surface L does not necessarily need to be formed in a U-shape in a front view, and the core material can be sectioned along an L-shape, a straight line, or a curved boundary in a front view. Also, the boundary surface L
The bottomed holes 7 and 8 may be arranged such that each of the holes has a triangular wave shape, a rectangular wave shape, a sawtooth wave shape, or a sine wave shape.

In the core 1, as described above, a plurality of bottomed holes 7, 8 penetrating the core 1 in the front-rear direction at regular intervals along the boundary surface L are formed. Unlike the case where the partition member is used, no burr is formed on the surface of the core material 1 along the boundary surface L, so that the core material 1 can be removed without performing a step for removing the burr. It is possible to accurately fix it to the mounting surface of the front beam of the automobile as it is. In addition, even when the cover member is provided on the core member 1, it is possible to reliably prevent a gap from being formed between the core member 1 and the cover member.

In this embodiment, the core material 1 of the automobile bumper has been described. However, any molded product having a molded portion made of raw material beads having different characteristics can be used for the in-mold foam molded product other than the core material. However, the present invention can be similarly applied. Also,
Depending on the molded article, raw material beads having characteristics other than the expansion ratio, such as base resin composition, crystallized structure, particle size, particle shape, particle weight, etc.
A molded article may be formed using raw material beads having one or more characteristics of cell diameter and color in the particle.

As the material of the raw material beads, a material having physical properties corresponding to the use conditions of the molded article to be manufactured is selected. However, a polystyrene synthetic resin material, a polyethylene resin material, a polypropylene resin material, or the like is used. Polyolefin-based synthetic resin materials, copolymers of these synthetic resin materials, and the like can be employed. The expansion ratio of the raw material beads depends on the raw material of the raw material beads, but is preferably in the range of 3 to 150 times. Specifically, in the case of raw material beads made of a polystyrene-based synthetic resin material, it is 3 to 100 times, preferably 3 to 100 times.
In the case of 80-fold raw material beads made of a polyolefin-based synthetic resin material, those having 3 to 90 times, preferably 3 to 60 times can be suitably used. The particle size is 1 to 10 mm,
Preferably, those having a range of 2.0 to 8 mm can be suitably used.

Specific examples of the polyolefin resin material include ethylene propylene random polypropylene resin,
Ethylene propylene block polypropylene resin, homopolypropylene ethylene propylene butene random terpolymer, linear low density polyethylene (LLDPE),
Crosslinked low-density polyethylene (crosslinked LDPE) and the like can be suitably used.

When the cell diameter of the raw material beads made of such a polyolefin resin material is less than 100 μm, there is a problem that the surface elongation is poor at the time of molding, the sink is easy, and the appearance of the proper surface appearance is inferior. If it exceeds, the cell diameter tends to be non-uniform, and the cell diameter is large, so that the surface texture is rough and the proper surface appearance is inferior.Therefore, within the range of 100 to 900 μm, more preferably 150 to 700 μm, Particularly preferably 170 to 55
It will be set to 0 μm.

The DSC 2'nd peak ratio is 8% to 60%
It is preferable to set The DSC 2'nd peak ratio is defined as the two DSCs formed on the low-temperature side and the high-temperature side, which are formed due to the crystal melting point of the base resin when the base resin is heated.
(Differential scanning calorimetry) is the ratio of the area of the peak on the high temperature side to the total area of the peaks. When the DSC 2'nd peak ratio is less than 8%, the heating condition width during molding is narrow, and Easy to shrink and sink. On the other hand, if it exceeds 60%, it is necessary to greatly increase the heating conditions, it is necessary to increase the size of the molding machine, and it becomes negative from the viewpoint of energy saving, so it is 8 to 60%, more preferably 10 to 50%. %, Particularly preferably 15 to 40%.

When the closed cell ratio is less than 65%, even if the heating pressure at the time of molding is increased and the beads are fused together, the shrinkage and sink marks of the molded body are liable to increase.
Since it becomes difficult to obtain a molded product of the target quality, it is 65% or more, more preferably 75% or more, and particularly preferably 85%.
The above is set.

Next, an in-mold foam molding apparatus 10 for molding the core material 1 will be described. As shown in FIG. 3, the in-mold foam molding apparatus 10 includes a core mold 11 and a cavity mold 12 as a pair of dies arranged opposite to each other, and a core mold 1.
1 and the cavity 12 formed by the cavity mold 12
Two sets of partitioning means 30 for partitioning into one partition forming space 13A and one partition forming space 13B;
A, 13B, two sets of filling means 14A, 14A for filling raw material beads having different characteristics in air flow, respectively.
14B.

The core mold 11 and the cavity mold 12 are attached to a housing 15 having a frame-shaped frame and a back plate, respectively. A pair of a first chamber 16 and a second Chamber 17
Are respectively formed, and the core mold 11 and the cavity mold 12 are formed.
Are formed with a large number of air holes 18 communicating the chambers 16 and 17 with the molding space 13. The vent 18
Is actually 0.5 m as illustrated in FIGS. 4 and 5.
Round hole 19a of about mφ and slit 1 of about 0.5 mm width
A core vent 19 formed of a cylindrical body having a lid with an outer diameter of 7 to 12 mm through which a plurality of 9b are passed, and formed by fitting into a core vent attachment hole 20 formed in the dies 11 and 12; 0.5mmφ directly formed on, 12
The core vent hole 21 is formed.

First chamber 16 and second chamber 1
7 is connected to a supply pipe SP for supplying a working fluid such as steam or compressed air, and a discharge pipe EP connected to a decompression means and a drain pipe, respectively.
Control valves (not shown) are provided in the middle of the supply pipe SP and the discharge pipe EP, respectively.
It is configured to be able to control the supply and discharge of the utility fluid to and from the engine.

The filling means 14A and 14B have basically the same configuration except that raw material beads having different characteristics are filled. Each of the filling means 14A and 14B has a bead temperature for controlling the temperature of the raw material beads to a set temperature. It has a regulating tank 22, a raw material tank 23 for storing temperature-controlled raw material beads, and a filling device 24 for filling raw material beads supplied from the raw material tank 23 into the molding space 13.

An intake pipe IP is connected to the raw material tank 23, and an intake valve V1 is interposed in the middle of the intake pipe IP. The internal pressure of the raw material tank 23 is adjusted by controlling the intake valve V1. Further, a shutter 25 is attached to the raw material tank 23, and the raw material beads are supplied from the shutter 25 to the filling pipe FP.
Through to the filler 24. The inside of the raw material tank 23 is pressurized above the internal pressure of the chambers 16 and 17, and the raw material beads stored in the raw material tank 23 are filled in the forming space 13 by riding the flow of air from the raw material tank 23 to the forming space 13. It is configured to:

The raw material tank 23 is provided with a temperature control means 26 for controlling the temperature of the raw material beads, and a temperature sensor 26a for measuring the ambient temperature in the raw material tank 23 is provided.
Based on the signal from the temperature sensor 26a, the temperature control means 26
And the temperature of the raw material beads immediately before filling is adjusted to the set temperature. As the temperature control means 26, the temperature of the cooling water is controlled at 30 to 50 ° C. in the molding factory, so that it is preferable in terms of equipment economy to perform the temperature control using the cooling water.

The bead temperature control tank 22 is provided with a heating means 27 for heating the raw material beads, and a temperature sensor 27a for measuring the temperature in the bead temperature control tank 22 is provided. Heating means 2 based on
The temperature of the raw material beads is adjusted to a set temperature by controlling the heating temperature by the control unit 7. In order to more precisely adjust the temperature of the raw material beads, it is preferable to provide a plurality of temperature sensors 27a and use the average temperature as the temperature of the raw material beads.

As the heating means 27, a heating means having an arbitrary structure can be adopted, but it is preferable in terms of equipment economy to provide a heating means using heating steam used at the time of molding. Also,
It is also possible to adopt an electric heater or the like as the heating means,
A heating unit using heating steam and a heating unit such as an electric heater may be used in combination. Further, as a heating means, for example, a hot air blower may be used to control the temperature while stirring the beads so that the ambient temperature in the bead temperature control tank 22 becomes uniform.

It is preferable that the bead temperature regulating tank 22 has a heat insulating structure in which the inner wall or the outer wall is formed of a heat insulating material in order to enhance the heat retention. In addition, the transportation of the raw material beads from the bead temperature control tank 22 to the raw material tank 23 is performed by opening / closing a valve V on the way.
2 is carried out by pneumatic transportation via a transportation pipe TP provided with the heating pipe 2. In order to prevent a temperature change of the raw material beads during transportation, the transportation pipe TP is kept warm and the temperature of the air for transportation is also set in advance. Adjustment is also preferable.

The heating temperature of the raw material beads can be set to any temperature between the normal temperature and the melting point. However, considering the deterioration of the beads in a high temperature range, the temperature control in summer in a low temperature range, and the energy saving in winter, 30 ° C. The temperature is preferably set to 30 ° C. to 50 ° C. in consideration of the control accuracy of the compression filling pressure in the low compression pressure range or the high compression pressure range of the molding machine and the bead compression characteristics. Further, in order to stabilize the mechanical strength and weight of the molded product, the temperature of the raw material beads is preferably adjusted within a range of a set temperature ± 5 ° C. In this embodiment, the molding apparatus is configured on the assumption that the temperature of the raw material beads is controlled. However, when the temperature of the raw material beads is not controlled, the bead temperature control tank 22 can be omitted.

As the raw material beads to be supplied to the bead temperature adjusting tank 22, those having an internal pressure adjusted according to the characteristics of the raw material beads in order to appropriately set the foaming pressure at the time of heat fusion are used. Specifically, raw material beads having different characteristics are individually charged into a sedimentation tank (not shown), and while heating the interior of the sedimentation tank to a constant temperature, an inorganic gas atmosphere having a set pressure according to the characteristics of the raw material beads is used. The raw material beads are held therein for several hours, and an inorganic gas is injected into the raw material beads. For example, when using raw material beads made of a polypropylene-based resin, 0.1 to 0.6 M
The inorganic gas is press-fitted into the raw material beads 5 while being kept in an inorganic gas atmosphere of Pa for about 1 to 30 hours. However, the pressure is indicated by a gauge pressure, and will be handled similarly in the following description.

Next, the partitioning means 30 will be described. As shown in FIG. 3 and FIG.
And two partition forming spaces 13A for forming the low-foaming part 5 through two sets of partitioning means 30 provided corresponding to
One section forming space 13B for forming the high foaming portion 6
Fillers 24 are respectively connected to the partition forming spaces 13A and 13B, so that the adjacent partition forming spaces 13A and 13B can be filled with raw material beads having different characteristics. In the present embodiment, the molding space 13 is divided into three in order to mold the core material 1 of the automobile bumper. However, the division shape, the number of divisions, and the division position of the molding space 13 depend on the molded product to be manufactured. It can be set arbitrarily. In addition, the raw material beads having different expansion ratios were filled in the adjacent molding spaces 13A and 13B. However, depending on the use of the molded product, the base resin composition, the crystallized structure, the particle size,
It is also possible to fill raw material beads having one or more characteristics different in particle shape, particle weight, intracellular cell diameter, and color.

As shown in FIGS. 7 and 8, the partitioning means 30 includes comb teeth 31 arranged in parallel in the mold opening / closing direction.
And a support member 32 for supporting the comb teeth 31 in a cantilever manner, a set of three first partition members 33 fixed to the cavity mold 12 in a substantially U-shape, and a core mold 11 And a set of three second partition members 34 fixed in a substantially U-shape. However, as the partition members 33 and 34, those integrally formed in a substantially U-shape may be used. In addition, the comb teeth 31
Instead of the partitioning members 33 and 34 having a shape, a plate-like partitioning member that moves into and out of the molding space 13 by an actuator such as an air cylinder can be employed.

The interval T between the comb teeth 31 of the two partition members 33, 34
Are set at intervals at which raw material beads filling at least one of the partition forming spaces 13A and 13B cannot pass through. If the interval T between the comb teeth 31 is too small, the adhesion between the raw material beads filled in the adjacent section forming spaces 13A and 13B cannot be sufficiently secured, and the strength of the core material 1 is reduced, so that the core material 1 cannot pass through. Raw material beads diameter 3
It is preferably set to 0 to 90%, more preferably 50 to 80%.

The comb teeth 31A of the first partition member 33 and the comb teeth 31B of the second partition member 34 are arranged so as to be shifted by a half pitch, and the length of the comb teeth 31 of both partition members 33, 34 is
Both dies 11, 1 at positions where the comb teeth 31 are arranged
It is configured to be shorter than the distance between the two and the tips of the comb teeth 31A, 31B wrap in the mold opening / closing direction in a state where the molds 11, 12 are closed.

In this partitioning means 30, the first partitioning member 33
Of the comb teeth 31A and 31B of the second partition member 34, the length of the comb teeth 31A and 31B can be set as short as possible.
Can be prevented and the bending moment acting on the comb teeth 31A, 31B can be set small.
31B, it is possible to adopt a small-diameter one, and the bottomed hole 7 formed in the core 1 by the comb teeth 31A, 31B.
8 can be made as small as possible. Also, the comb teeth 31A, 31B
Since the length setting becomes rough, it is possible to easily respond to changes in the shape of the core material 1, etc., and to fill the raw material beads with a cracking gap between both molds like cracking filling In this case, by setting the lap amount of the comb teeth 31A and 31B of the two partition members 33 and 34 to be slightly larger than the cracking gap, the adjacent forming space 13 is formed.
A and 13B can be partitioned. In addition, the comb teeth 31
A and the comb teeth 31B are alternately arranged.
When the molds 1 and 12 are opened, it is possible to apply a pulling force to the comb teeth 31A and 31B in a well-balanced manner with respect to the core material 1, which is preferable in improving mold release properties.

The comb teeth 31 are formed of an elongated rod-shaped or pipe-shaped member, and may have any cross-sectional shape such as a circular shape, an elliptical shape, an elliptical shape, a polygonal shape such as a square or a hexagon. Can be adopted. The material of the comb teeth 31 is made of any material such as a metal material, a synthetic resin material, and ceramics as long as the material can withstand the filling pressure of the raw material beads and can withstand the heat during the heat fusion of the raw material beads. it can. In the case where the partitioning means 30 is used, FIGS.
As shown in FIG. 2, since the bottomed holes 7 and 8 are formed in the core 1 at positions corresponding to the comb teeth 31A and 31B, the diameter of the comb teeth 31 can be set as small as possible. Preferably, the diameter of the comb teeth 31 is set to, for example, 1 to 10 mm, preferably 1.5 to 5 mm. Further, it is preferable to use an elastically deformable metal material or synthetic resin material as the comb teeth 31. With this configuration, even if the comb teeth 31 are slightly deformed due to the filling pressure or the foaming pressure, the comb teeth 31 can be restored to the original shape. , Comb teeth 3
By setting the cross-sectional area of the core material 1 as small as possible, it is possible to suppress a reduction in the appearance and strength of the core material 1.

Although not shown, the in-mold foam molding apparatus 10 is provided with an ejector pin for releasing the core material 1 from the cavity mold 12, and is provided with the molds 11 and 12 including the partition members 33 and 34. With respect to the mold release resistance of the core material 1
By adjusting the configurations of 1A and 31B as follows, the mold release resistance of the cavity mold 12 side is set to be larger than that of the core mold 11 side, and the core material 1 is placed on the cavity mold 12 side having the ejector pins when the mold is opened. It is configured to be securely left.

The mold release resistance on the cavity mold 12 side is the core mold 1
The cavity mold 12 and the first mold are larger than the first mold.
Comb teeth 31A of the partition member 33 and comb teeth 3 of the second partition member 34
The total surface area, the number, the total length, the cross-sectional area, the cross-sectional shape, the surface properties, the draft angle, and the like with 1B are adjusted, or these adjustments are combined. However, since the mold is basically designed such that the core material 1 is left on the mold side having the ejector pins, the two comb teeth 31A, 3
If the release resistance of the core material 1 from the core mold 1B is set to be the same, the core material 1 is left on the cavity mold 12 side, and the release resistance from the comb teeth 31B on the core mold 11 side is reduced by the comb on the cavity mold 12 side. Even if it is set slightly larger than the release resistance from the teeth 31A,
The core material 1 is left on the cavity mold 12 side, but the mold release resistance from the comb teeth 31A on the cavity mold 12 side is changed so that the core material 1 is securely left on the cavity mold 12 side. It is preferable to adjust the configuration of the comb teeth 31A and 31B as described above so as to be greater than the release resistance from the 11-side comb teeth 31B. In addition, both comb teeth 31A, 3
If the difference between the mold release resistances from the mold teeth 1A and 1B is set too large, the work of releasing the core material 1 by the ejector pins may be hindered. It is preferable to set it to be large. Further, it is preferable that the release resistance from the comb teeth 31A and 31B be set so as to act uniformly on the core material 1.

As shown in FIG. 9, the partition member 34 of the core mold 11 is omitted and the tip of the core mold 11 is replaced with the partition member 33 of the cavity mold 12.
A partition member 42 having comb teeth 41 extended to
By providing the interval between the comb teeth 41 at a distance shorter than the diameter of at least one of the raw material beads, the molding space 1 is formed.
3 may be divided into a plurality. In this case, the left and right first partitioning members 42A are fixed to the cavity mold 12 as shown in FIG. Second partition member 42B
May be fixed to the core mold 11.

Also, instead of the partitioning means 30, as in the partitioning means 50 shown in FIG. 11, a columnar fixed partition is formed corresponding to the corners and ends of the boundary L between the low foaming part 5 and the high foaming part 6. Member 5
1 is provided integrally with the core mold 11 or the cavity mold 12, or a wall-shaped fixed partitioning member is provided at an intermediate portion of the boundary surface L between the low foaming section 5 and the high foaming section 6 as shown in FIG. 5
6 may be provided integrally with the core mold 11 or the cavity mold 12. In this case, as shown in FIG. 11, a through hole 57 and a groove 58 are formed in the core 1A by a fixed partition member 52, and as shown in FIG. 12, a fixed partition member 56 is formed in the core 1B. Although a long through hole 59 is formed, a thin portion of the core material, which is difficult to be divided by the comb teeth 31, can be partitioned by the fixed partition members 51 and 56. It is preferable to employ it.

In the above embodiment, the plurality of comb teeth of the partition member are arranged on the same plane, and the boundary surface L between the low foaming portion 5 and the high foaming portion 6 by each partition member is formed as a flat surface. However, by arranging the comb teeth 31 so that the boundary surface has a wavy shape such as a rectangular wave, a triangular wave, or a sine wave, the contact area between adjacent raw material beads is increased, and the bonding strength between the two is improved. It is preferable because it is possible. In addition, although the case where the boundary surface L between the low foaming portion 5 and the high foaming portion 6 is substantially U-shaped in front view has been described, the present invention is applicable to other shapes such as L-shape, crank shape, and straight shape. The invention is equally applicable.

Further, instead of the in-mold foam molding apparatus 10, as shown in FIG. 13, an in-mold foam molding apparatus 60 in which the vent holes 18 are completely or almost completely omitted from the core mold 11 and the cavity mold 12 is employed. It is also possible. In this case, even when the core mold 11 and the cavity mold 12 are closed, the clearance 61 that opens into the molding space 13 is formed.
Is formed along the joint of the two dies 11 and 12, and a working fluid such as steam is supplied to the molding space 13 via the clearance 61 independently of the two chambers 16 and 17, or the molding is performed. Drain and the like are discharged from the space 13. In such a molding apparatus 60, it is possible to manufacture the core material 1 with a beautiful surface without any trace of the vent hole 18.
Since the strength of the molds 11, 12 due to the formation of the mold 8 can be prevented, the heat capacity of the molds 11, 12 can be set small by making the molds 11, 12 thin, and the heat efficiency of heating and cooling can be improved. That the accuracy of temperature control can be improved,
The processing cost for forming the air holes 18 can be greatly reduced, the manufacturing cost of the molds 11 and 12 can be reduced, and heating defects, mold release defects, and cooling defects due to clogging of the air holes 18 do not occur. Maintenance work such as replacement of the core vent 19 or periodic cleaning with high-pressure cleaning water is not required at all, and the cooling water used in the cooling step does not enter the molding space 13. From about 6 to 10% to about 0.5 to 2%,
The effect of eliminating the need for a drying step and greatly contributing to a reduction in cycle time is obtained.

Further, in this embodiment, the in-mold foam molding apparatuses 10 and 50 for producing the core material 1 of the automobile bumper as the in-mold foam molded product have been described, but molded products other than the core material 1 are produced. The present invention can be similarly applied to a molding apparatus that performs the above.

Next, an example of a method for molding the core material 1 using the foam molding apparatus 10 shown in FIG. 3 will be described. First, an inorganic gas is injected into the raw material beads in accordance with the characteristics so that the foaming pressure at the time of heat fusion of the raw material beads having different characteristics is substantially the same, and the raw material beads having the internal pressure of the raw material beads adjusted in advance are prepared. To manufacture. For example, when the low-foaming portion 5 is made of raw material beads made of a polypropylene resin having an expansion ratio of 5 times and the high-foaming portion 6 is made of raw material beads made of a polypropylene resin having an expansion ratio of 20 times, When the raw material beads are heated and fused by steam as shown in
Under low-expansion-ratio raw material beads, under heating at 30 ° C. in an inorganic gas atmosphere of 0.1 MPa so that the low-expansion-ratio raw material beads and the high-expansion-ratio raw material beads have substantially the same foaming pressure. The raw material beads having a high expansion ratio are maintained at a temperature of 30 ° C. for 10 hours under an atmosphere of an inorganic gas of 0.2 MPa to raise the internal pressure of the raw material beads having a low expansion ratio to 0.3. The pressure is set to 1 MPa, and the internal pressure of the raw beads having a high expansion ratio is set to 0.05 MPa.

In this example, raw beads having different expansion ratios were used as raw beads having different characteristics. However, the base resin composition, crystallization structure, particle size, particle shape, particle weight, particle cell diameter, Similarly, even when using one or two or more kinds of raw material beads having different characteristics, the internal pressure of the raw material beads is adjusted according to each characteristic, and the heat pressure between the raw material beads having different characteristics during heat fusion is similarly adjusted. The foaming pressure is adjusted so as to be substantially the same. Further, the internal pressure of the raw material beads was adjusted so that the foaming pressure at the time of heat fusion was substantially the same. However, depending on the molded product, the differential pressure of the foaming pressure between the raw material beads having different characteristics became a desired value. To
It is also possible to adjust the internal pressure of the raw material beads.

Further, the internal pressures of the two types of raw material beads having different expansion ratios were respectively adjusted. However, only the internal pressure of one type of raw material beads was adjusted so that the expansion pressure at the time of heat fusion was substantially the same. May be. However, since raw material beads made of polyolefin resin have weak foaming power as compared with polystyrene resin, the raw material beads are sufficiently expanded to improve the adhesion and appearance between beads. It is preferable to adjust the internal pressures.

Next, the raw material beads of which the internal pressure has been adjusted are supplied to the corresponding bead temperature control tank 22, and the temperature of the raw material beads in the bead temperature control tank 22 is measured while the heating means 27 controls the temperature of the raw material beads in the bead temperature control tank 22. Is heated and the temperature of the raw material beads is adjusted to a predetermined set temperature of 30 to 50 ° C., and then the raw material beads are supplied to the heated raw material tank 23. However, it is preferable to set the set temperature as low as possible because the higher the set temperature, the more the inorganic gas pressed into the raw material beads is released. As described above, by adjusting the temperature of the raw material beads, it is possible to suppress a change in the expansion ratio of the molded product between molding shots due to a variation in the outside air temperature or the like, and to mold a high-quality molded product. Also, by adjusting the temperature according to the characteristics of the raw material beads, the degree of compression of the raw material beads during compression filling can be adjusted, and thus the foaming pressure of the raw material beads during heat fusion can be adjusted, so that the internal pressure of the raw material beads, the temperature and Thus, it is also possible to control the foaming pressure largely. Note that this step is not necessarily required and may be omitted.

Next, the core mold 11 and the cavity mold 12 are filled with the raw material beads in the section forming spaces 13A and 13B.
And the molding space 13 is closed by the partition members 33 and 34.
The interior is partitioned into three partition forming spaces 13A and 13B. At this time, the tip of the comb tooth 31A on the cavity mold 12 side and the tip of the comb tooth 31B on the core mold 11 side overlap each other in the longitudinal direction, and the molding space 13 is divided into the partition molding spaces 13A, 13A.
B.

Next, from the filling device 24, the compartment forming space 13
A and 13B, 5 times the raw material beads and 2
The raw material beads having a volume of 0 times are supplied individually in a flow of air, and the molding space 13 is filled with the raw material beads. At this time, the raw material beads filled in the adjacent section forming spaces 13A and 13B come into contact with each other via the gap between the comb teeth 31. In addition, as a specific filling method of the raw material beads, a known filling method such as a cracking filling method, a pressure filling method, and a compression filling method can be adopted, but when adjusting the foaming pressure by controlling the temperature of the raw material beads. It is preferable to employ a compression filling method since the foaming pressure can be adjusted by controlling the temperature to expand the control range of the foaming pressure.

Next, after the raw material beads are heated by supplying steam to the molding space 13 through both the chambers 16 and 17 and the vent hole 18, the raw material beads are foamed by releasing the vapor pressure, and the raw material beads are removed. They are fused to each other with almost no gap. At this time, if air remains between the raw material beads, the adhesiveness between the raw material beads decreases, so that the operation of replacing the air in both chambers 16 and 17 and the molding space 13 with steam is performed in advance. In addition, the heating by the steam causes the raw material beads in the adjacent forming spaces 13A and 13B to fuse with each other via the gap between the comb teeth 31. In addition, since the internal pressure is set in accordance with the characteristics of the raw material beads as described above, both the forming space 13
The foaming pressure of the raw material beads in A and 13B becomes substantially the same, so that an excessive force is prevented from acting on the comb teeth 31, and a small diameter comb tooth 31 can be adopted. For this reason, the boundary surface L of the core material 1 does not shift or curve, and the bottomed holes 7, 8 and the through hole can be formed in a straight shape and with a small diameter. A good quality core material 1 can be formed.

Next, cooling water is sprayed toward the core mold 11 and the cavity mold 12 from a nozzle (not shown) to form the molding space 1.
After cooling the core 1 in the mold 3, the molds 11 and 12 are opened. As described above, the comb teeth 31 of the partition members 33 and 34 are opened.
By adjusting the configuration of A, 31B, the cavity mold 12
The mold release resistance on the side is set to be larger than the mold release resistance on the core mold 11 side, so that the core material 1 is left on the cavity mold 12 side with the molds 11 and 12 opened. In this manner, the molds 11 and 12 are opened to leave the core 1 on the cavity mold 12 side, and the core 1 is released from the cavity 12 using an ejector pin (not shown).

When the first raw material beads having a diameter that cannot pass between the comb teeth 31 and the second raw material beads that can pass through between the comb teeth 31 are used as the raw material beads, the raw material to the molding space 13 is used. When filling the beads, the first raw material beads are filled in the partition forming space 13B, and then the second raw material beads are filled in the partition forming space 13A. In this case,
Since a part of the first raw material beads moves into the section forming space 13A through the space between the comb teeth 31, the adhesion between the first raw material beads and the second raw material beads can be further improved.

When molding is performed using the in-mold foam molding apparatus 60, the core mold 11 having no vent hole 18 formed in a molding portion for molding a prominent portion of the outer surface of the core material 1 is formed.
In addition, since the cavity mold 12 is used, the filling air supplied into the molding space 13 together with the raw material beads at the time of filling the raw material beads is discharged out of the molding space 13 via the clearance 61. When the raw material beads are heated and fused by steam, the chambers 16, 1
7 and the steam is supplied into the molding space 13 via the clearance 61. In the present embodiment, the molding method for molding the core material 1 of the automobile bumper has been described. However, the present invention can be similarly applied to the case where an in-mold foam molded product other than the core material 1 is molded.

[0073]

According to the in-mold foam molding method of the present invention, the adjacent bead forming spaces can be filled with raw material beads having different characteristics. By properly setting the characteristics and the like, the performance and quality of the molded product can be improved. For example, for parts where the strength is important, the strength and rigidity of the molded product are increased by using raw material beads having a low expansion ratio, and for other parts, the weight of the molded product is reduced by using raw material beads having a high expansion ratio, It is possible to improve the strength of the molded product and reduce the weight at the same time.

Further, since the internal pressure of the raw material beads is set according to the characteristics, it is possible to appropriately adjust the foaming pressure at the time of heat fusion for each raw material bead having different characteristics. Specifically, the raw material beads are filled in each section forming space in a state where the internal pressure of the raw material beads is set according to the characteristics so that the foaming pressure during the heat fusion of the raw material beads is substantially uniform. By doing so, it is possible to prevent the displacement or deformation of the boundary surface of the raw material beads having different characteristics, and when using a comb tooth as a partition member, prevent the deformation of the comb tooth and release the molded article from the comb tooth. In addition to improving combability, it is possible to use small-diameter comb teeth, and the through-holes and bottomed holes formed in the molded article by the comb teeth are set to a small diameter to improve the strength and appearance of the molded article. Can be improved. Further, it is preferable to compress and fill the raw material beads under substantially the same compression condition, because dispersion of the packing density in each part in the molding space can be minimized.

By compressing and filling at least one kind of the raw material beads into each of the molding spaces in a state where the temperature is controlled, the variation in the expansion ratio of the molded product between molding shots is reduced.
This is preferable because the variation in weight of the molded article can be reduced. In addition, since the degree of compression of the raw material beads during compression filling can be adjusted by adjusting the temperature, the foaming pressure and the like can be largely controlled by adjusting the internal pressure of the raw material beads and the temperature.

It is preferable to compress and fill the raw material beads into the molding spaces in the respective compartments while controlling the temperature to the same temperature, because the variation in the expansion ratio of the molded product between molding shots can be reduced and the variation in the weight of the molded product can be reduced. . Moreover, although the control width of the foaming pressure is reduced, the control is performed only by adjusting the internal pressure of the raw material beads, so that the control system can be significantly simplified.

According to the thermoplastic synthetic resin in-mold foam molding apparatus of the present invention, the internal pressure of at least one kind of raw material beads can be adjusted by the internal pressure adjusting means, so that the raw material beads are filled with the internal pressure adjusted appropriately. As in the case of the in-mold foam molding method, it is possible to appropriately adjust the foaming pressure at the time of heat fusion for each raw material bead having different characteristics.

When a partition member having a plurality of comb teeth is fixed to a mold as a partition member, it is possible to reduce the manufacturing cost of the molding apparatus, to easily cope with a design change of the molded article, and to have different characteristics among the molded articles. It is possible to ensure sufficient bonding strength of the molded part molded with the raw material beads, and to reliably prevent the problem that burrs are formed at the boundary part,
In addition, it is possible to obtain effects such as the ability to prevent a partial decrease in the mold strength and to improve the precision of the molded product.

Further, by setting the foaming pressure at the time of heat fusing of the raw material beads in the adjacent section forming spaces to be substantially the same, deformation of the comb teeth is prevented, and the releasability of the molded article from the comb teeth is improved. It is possible to improve the strength and appearance of the molded product by setting the diameter of the through hole and the bottomed hole formed in the molded product by the comb teeth to be small, while improving the comb teeth. . When a rod-shaped member having a diameter of 1 to 10 mm is used as a comb tooth, a reduction in the strength and appearance of the molded product due to the formation of a bottomed hole or a through hole can be prevented as much as possible, and the strength of the comb tooth is sufficiently ensured. As a result, breakage and deformation of the comb teeth can be prevented.

When the interval between the adjacent comb teeth is set to 30 to 90% of the diameter of the raw material beads that cannot pass through, the adhesion between the raw material beads in the partition forming space adjacent to each other across the comb teeth is improved, and In addition to securing sufficient strength at the portion, even when soft material beads are used, it is possible to prevent a problem that the material beads move between the comb teeth of the partition member to the adjacent forming space. When the comb teeth are made of a material that can be elastically deformed, the cross-sectional area of the comb teeth is set as small as possible while preventing molding defects and mold release defects due to plastic deformation of the comb teeth, thereby reducing the appearance and strength of the molded product. Can be suppressed.

According to the in-mold foam molded article of the present invention, the through-hole or the bottomed hole has a substantially straight shape, so that the molded article can be easily released from the comb teeth, and the boundary between the molded parts can be improved. Since the surface is not deformed, the dimensional accuracy is excellent, the variation in weight is small, and the quality is high enough to sufficiently secure the strength of the boundary surface.

When the present invention is applied to a bumper for an automobile, a portion near a local impact stress acting on a core material at the time of various frontal collisions of an automobile is constituted by a low foaming portion made of raw material beads having a low expansion ratio. The other parts are composed of high foaming parts made of raw material beads having a higher expansion ratio than the low foaming parts, so that the impact energy can be reduced even at the time of offset collision or oblique collision while reducing the weight of the core material as much as possible. It becomes possible to absorb effectively.

[Brief description of the drawings]

FIG. 1 is a perspective view of a core material of an automobile bumper.

2A is a sectional view taken along line II-II of FIG. 1, and FIG. 2B is a sectional view taken along line bb of FIG.

FIG. 3 is a longitudinal sectional view of an in-mold foam molding apparatus.

FIG. 4 is a longitudinal sectional view of a mold near an air hole.

FIG. 5 is a front view of a core vent.

FIG. 6 is a sectional view taken along line VI-VI of FIG. 3;

FIG. 7 is a side view of the partition means.

FIG. 8 is a perspective view of a partitioning means.

FIG. 9 is a perspective view of a partitioning unit having another configuration.

FIG. 10 is a perspective view of a partitioning unit having another configuration.

FIG. 11A is a perspective view of a molded article having another configuration,
(B) is an explanatory view of a molding device for molding the molded article.

FIG. 12A is a perspective view of a molded product having another configuration,
(B) is an explanatory view of a molding device for molding the molded article.

FIG. 13 is a longitudinal sectional view of a molding apparatus having another configuration.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 core material 2 front shock absorbing portion 3 side shock absorbing portion 4 corner portion 5 low foaming portion 6 high foaming portion 7 bottomed hole 8 bottomed hole L boundary surface 10 in-mold foam molding device 11 core mold 12 cavity mold 13 Molding space 13A Compartment molding space 13B Compartment molding space 14A Filling means 14B Filling means 15 Housing 16 First chamber 17 Second chamber 18 Vent hole 19 Core vent 19b Slit 19a Round hole 20 Core vent mounting hole 21 Core vent hole 22 Bead temperature regulating tank 23 Raw material tank 24 Filler 25 Shutter 26 Temperature control means 26a Temperature sensor 27 Heating means 27a Temperature sensor EP Discharge pipe FP Fill pipe IP Intake pipe TP Transport pipe SP Supply pipe V1 Intake valve V2 Open / close valve 30 Partition means 31 Comb teeth 31A Comb teeth 31B Comb tooth 32 Support member 33 Partition member 34 Partition part REFERENCE SIGNS LIST 40 partitioning means 41 comb teeth 42 partitioning member 43 partitioning means 42A partitioning member 42B partitioning member 1A core material 1B core material 50 partitioning means 51 fixed partitioning member 52 fixed partitioning member 55 partitioning means 56 fixed partitioning member 57 through hole 58 groove portion 59 through hole 60 In-mold foam molding device 61 Clearance

Claims (17)

[Claims] 1. A molding member is divided into a plurality of compartment molding spaces by a partition member, and individual compartment molding spaces are individually filled so that at least adjacent compartment molding spaces are filled with raw material beads having different characteristics. At the time of filling the raw material beads in the state, with the internal pressure of the raw material beads set according to the characteristics,
A method for in-mold foam molding of a thermoplastic synthetic resin, characterized in that raw material beads are filled in each compartment molding space. 2. Filling the raw material beads into each compartment forming space in a state where the internal pressure of the raw material beads is set according to the characteristics so that the foaming pressure during the heat fusion of the raw material beads is substantially uniform. The method for in-mold foam molding of a thermoplastic synthetic resin according to claim 1. 3. The method according to claim 1, wherein the raw material beads are compressed and filled into each of the molding spaces under substantially the same compression conditions. 4. The raw material beads having one or more characteristics of one or more of expansion ratio, base resin composition, crystallization structure, particle size, particle shape, particle weight, cell diameter in particle, and color as the raw material beads. The method for in-mold foam molding of a thermoplastic synthetic resin according to any one of claims 1 to 3, wherein 5. The raw material beads having different expansion ratios are used as the raw material beads, and the internal pressure of the raw material beads having a low expansion ratio is set higher than the internal pressure of the raw material beads having a high expansion ratio. In-mold foam molding method of the thermoplastic synthetic resin described in the above item. 6. The raw material beads having different expansion ratios are used as the raw material beads, and the internal pressure of the raw material beads having a low expansion ratio is set to be equal to or less than the internal pressure of the raw material beads having a high expansion ratio. An in-mold foam molding method of the thermoplastic synthetic resin according to the above. 7. The method for in-mold foam molding of a thermoplastic synthetic resin according to claim 1, wherein the plurality of compartment molding spaces are filled with raw material beads at the same time. 8. The in-mold foam molding method for a thermoplastic synthetic resin according to claim 1, wherein the plurality of compartment molding spaces are filled with the raw material beads at a time difference. 9. The compression molding of at least one kind of the raw material beads into each of the compartment forming spaces in a state where the temperature is controlled.
9. An in-mold foam molding method for a thermoplastic synthetic resin according to any one of the above items 8. 10. The in-mold foam molding method for a thermoplastic synthetic resin according to any one of claims 1 to 9, wherein the raw material beads are compression-filled into each of the molding spaces under the same temperature. 11. A mold having a partition member for partitioning a molding space into a plurality of compartment molding spaces, and a mold for each of the compartment molding spaces such that at least the adjacent compartment molding spaces are filled with raw material beads having different characteristics. And a filling means for individually filling the raw material beads, wherein the filling means is provided with an internal pressure adjusting means for adjusting the internal pressure of at least one kind of the raw material beads. . 12. A partition member having a plurality of comb teeth extending in a cantilever manner in a mold opening and closing direction at an interval where at least one of raw material beads to be filled in an adjacent section forming space cannot pass therethrough. Claim 11 fixed to a mold
An in-mold foam molding apparatus for the thermoplastic synthetic resin according to the above. 13. The in-mold foam molding apparatus for thermoplastic synthetic resin according to claim 12, wherein a rod-like member having a diameter of 1 to 10 mm is used as said comb teeth. 14. The in-mold foam molding apparatus for thermoplastic synthetic resin according to claim 12, wherein an interval between adjacent comb teeth is set to 30 to 90% of a diameter of raw material beads which cannot pass through. 15. The in-mold foam molding apparatus for a thermoplastic synthetic resin according to claim 12, wherein the comb teeth are made of a material that can be elastically deformed. 16. A plurality of molding parts formed by using raw material beads having different characteristics, and a plurality of molding parts extending substantially straight in a mold opening / closing direction at predetermined intervals along boundaries of the molding parts. An in-mold foam molded product having a through hole or a bottomed hole. 17. The foamed molded product in a mold is a core material of an automobile bumper, and the core material has a foaming ratio in a vicinity of a portion which is susceptible to a local impact stress acting on the core material in various frontal collisions of an automobile. 17. The in-mold foam molded article according to claim 16, wherein the in-mold foam molded product is constituted by a low-foaming portion made of raw material beads having a low expansion ratio, and the other portion is constituted by a high-foaming portion made of raw material beads having a higher expansion ratio than the low-foaming portion.