JP2000033644A - Lamination blow molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide laminated moldings which are free from weld loss or the like and have a presentable outlook by pressing a parison to the surface of a mold from inside the parison to set the parison and a skin sheet to the specified shape and laminating the skin sheet and the parison together in one piece. SOLUTION: A mold 8 is clamped and after the completion of clamping the mold, a compressed air is injected into the piston head side of a cylinder 60 for moving a blow pin 61 forward/backward and further the below pin 61 is made to advance to the parison P side. Thus the blow pin 61 is made to penetrate the parison P so that the below pin 61 is set protruding through the interior 50 of the parison P. Further, a compressed air is blown into the interior 50 of the parison disposed in the mold 8 through the blow pin 61 and the parison P is expanded by blowing to set the parison P and a skin sheet S to the specified shape along a mold cavity. At the same time, the parison P and the skin sheet S are fused together in one piece and this monolithic piece is cooled inside the mold 8 to be unloaded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lamination blow molding method for molding a molded product in which a skin sheet is laminated on a parison surface, and has a good appearance without melting and wrinkling of the skin sheet. The present invention relates to a lamination blow molding method capable of obtaining a molded product.

[0002]

2. Description of the Related Art The tip of a hollow parison, which is cylindrically injected and extruded from between a die head and a mandrel, is sandwiched by a parison pinch and fused to form a bag. Compressed air, which is a pressurized fluid, is put in and hangs below the die while slightly inflating, and is put between a pair of molds arranged below the die. Then, a skin sheet is arranged between the mold cavity and the parison, the mold is clamped, and after the mold clamping is completed, air pressurized to a high pressure is injected through an injection needle (sometimes called a blow pin). Then, the parison is formed into a predetermined shape along the mold cavity by blowing into the parison placed in the mold, and the skin sheet is pressed against the mold by the parison and aligned with the mold cavity. The parison and the skin sheet are fused and integrated. The bonded blow-molded product thus formed is cooled in a mold, and after cooling is completed, the compressed air in the parison is discharged, and then the mold is opened and taken out.

[0003]

However, in the above-described conventional lamination blow molding method, the parison immediately after being injected from the die and having a desired size has a very high surface temperature, and the parison has a very high surface temperature. When the above-described mold clamping and shaping are performed in a high state, the skin sheet is extremely heated by the heat of the parison, so that the skin sheet is melted by the heat and impairs the appearance (the erosion and damage). Or a hole may be formed.

In addition, it is necessary to spread the skin sheet with a parison at the time of shaping, and to fuse the skin sheet with the parison while the skin sheet is appropriately stretched. Before being stretched moderately,
Immediately fused with the parison, as a result, the skin sheet was wrinkled, and air was caught between the skin sheet and the parison and swelled, resulting in poor appearance.

[0005] Therefore, before the skin sheet and the parison are bonded and integrated in the mold, there is no problem that occurs because the parison surface temperature is too high, and the parison and the skin sheet are fused well. It is necessary to cool the parison until it reaches a proper surface temperature (sometimes referred to as a proper temperature). In the conventional lamination blow molding, the parison is allowed to cool in the atmosphere and is cooled. When the surface temperature of the parison is lowered by cooling in the air, it takes time for the cooling, and the parison has problems such as drawdown.

In addition, depending on the shape of the die, the temperature distribution of the injected parison may vary from the beginning, and a portion of the parison having a variation in the temperature distribution where the surface temperature is high becomes an appropriate temperature. If it is allowed to cool down in the air until it cools, the temperature of the relatively low temperature part will be too low and often deviate from the appropriate temperature,
In the portion where the temperature was lower than the appropriate temperature, problems such as poor fusion between the skin sheet and the parison occurred.

Even if a parison having a uniform temperature without variation in temperature distribution is ejected from the die, it takes a little time to eject a parison of a desired size from the die. The lower part of the parison, which is a part (also referred to as an injection start part), and the upper part of the parison, which is a part that is last injected from the die (sometimes referred to as an injection end part),
Since the elapsed time after injection from the die is different and the cooling time in the atmosphere is different, there is a temperature difference between the lower part of the parison which is the injection start part and the upper part of the parison which is the injection end part, and the parison , The parison surface temperature tends to gradually decrease from the upper part toward the lower part of the parison. Therefore, if the upper part of the parison is cooled in the atmosphere until the upper part reaches the appropriate temperature, the temperature of the lower part of the parison becomes too low, deviates from the appropriate temperature, and the portion lower than the appropriate temperature has problems such as poor fusion. Had occurred.

Therefore, in order to obtain a good product in the conventional lamination blow molding method, it is necessary to select a skin sheet and a parison, and to form a wide range of appropriate temperatures. By selecting a material that is resistant to heat, increasing the thickness of the skin sheet, and examining and selecting a combination of materials for the skin sheet and parison, the skin sheet and parison can be melted at a relatively low temperature. And so on. But,
Increasing the thickness of the skin sheet impairs the shapeability at the time of molding the skin sheet, causing wrinkles, etc., and selecting the material of the skin sheet or parison as described above This was a factor that narrowed the choice of materials for seats and parisons.

In particular, in recent years, products have been diversified, and in many cases, there is a demand for a laminated molded product using a skin sheet having a thickness smaller than that of a conventional skin sheet or a skin sheet made of a material that is more vulnerable to heat than the conventional skin sheet. However, if such a skin sheet is molded by a conventional lamination blow molding method, problems such as erosion and opening of a hole occur, so that a good molded product cannot be obtained.

Furthermore, recently, a skin sheet having a foamed resin layer or a skin sheet having a brushed layer of resin has been used in order to form a high-quality soft and tactile bonded blow molded product. However, in the conventional bonding blow molding method, when molding is performed using a skin sheet having a foamed resin layer, the foamed resin is subjected to pressure in a state where the foamed resin is heated to a high temperature. Becomes, the layer of the foamed resin is melted, there is a problem that the soft feeling is lost by being crushed, and also when molding using a skin sheet having a brushed resin on the surface, For the same reason, the brushed resin is subjected to pressure in a heated state, and the raised brush of the resin may cause significant hair falling and impair the feel and appearance of the product. It occurs.

The present invention has been made in view of the above problems, and in particular, a skin sheet having a thickness smaller than that of a conventional skin sheet, a skin sheet made of a material that is weaker to heat than a conventional skin sheet, and a layer of a foamed resin. The present invention relates to a lamination blow molding method capable of obtaining a lamination molded product having good appearance without erosion or the like by using a skin sheet having the same or a skin sheet having a layer of raised resin.

[0012]

In order to solve the above-mentioned problems, a cooling medium is blown between a pair of left and right dies through a spray nozzle to a hollow parison hanging from a die, and the surface of the parison is blown. After cooling to the appropriate temperature and interposing a skin sheet between the parison and the mold at the appropriate temperature,
The parison and the skin sheet are shaped into a predetermined shape by closing the mold, successively blowing a high-pressure pressurized fluid into the parison, pressurizing and expanding the inside of the parison, and pressing the parison from the inside to the mold surface. The skin sheet and the parison were integrally laminated and molded.

In a second aspect of the invention, which is mainly based on the first aspect, the surface temperature of the hollow parison ejected from the die is measured by a temperature detector, and the temperature measured by the temperature detector is determined in advance. A cooling medium is sprayed on the parison through a spray nozzle until the temperature reaches a set temperature.

[0014] In a third aspect of the invention, which is mainly based on the second aspect, a plurality of surface temperature detectors arranged in the longitudinal direction of the parison are provided to measure the surface temperature of the parison in the longitudinal direction. Then, a cooling medium is sprayed from different spray nozzles to cool the parison so that the surface of the parison has a substantially uniform temperature in the vertical direction until the respective surface temperature measuring units of the parison reach a preset temperature. That is the configuration.

Further, the first invention or the second invention,
Alternatively, in the fourth invention mainly based on the third invention, a high-pressure pressurized fluid is blown into the parison through a blow pin to have a high pressure, so that the parison and the skin sheet are formed into a predetermined shape. After shaping, a heating medium is passed through a heating temperature control tube disposed in the mold, and the surface of the skin sheet is heated to the softening point temperature by the mold cavity surface heated to a desired temperature. By transferring a cooling medium through a cooling temperature control tube disposed in the mold and cooling the mold cavity surface to cool and solidify the surface of the skin sheet, it is possible to transfer the mold cavity surface to the surface of the skin sheet. The configuration was adopted.

[0016]

1 to 6 show an embodiment according to the present invention.
It will be described based on. FIG. 1 is a longitudinal sectional view of a lamination blow molding machine according to an embodiment of the present invention. FIG. 2 is an external view of the cooling medium spraying device according to the embodiment of the present invention. FIG. 3 is a layout diagram showing a positional relationship between a cooling medium spraying device and a mold. FIG. 4 is a conceptual diagram of the behavior of the cooling medium when the cooling medium is sprayed. FIG. 5 is a control flow sheet of the cooling medium spraying device. FIG. 6 is a conceptual diagram illustrating the inside of a mold during molding.

As shown in FIG. 1, the die 2 used in the embodiment of the present invention uses a molten resin supplied to the resin supply port 2a from the injection device 4 through an annular passage between the die head 2b and the mandrel 3. , And is extruded from the lowermost annular passage 7 and extruded to form a hollow parison P. Further, the width of the annular passage 7 can be controlled by moving the core 3a up and down by a paricon cylinder 6 provided at the upper part of the die 2 via a paricon rod 6a.

Below the die 2, a pair of left and right dies 8 is provided.
a and 8b are provided so that opening and closing are possible. As shown in FIG. 6, a through hole is formed from the outer wall of the mold 8b to the inside of the mold cavity, and a blow pin 61 having an open end is inserted. In the vicinity of the rear end of the blow pin 61, there is provided a high-pressure air blowing hole 62 for introducing compressed air as a pressurized fluid into the parison interior 50. When compressed air is introduced from the blowing hole 62, the blow pin 61 is blown.
Compressed air is blown out from the opening at the end of the nozzle. The rear end of the blow pin 61 is attached to one end of a rod 60b which is engaged with the blow pin forward / backward moving cylinder 60 and is fixed to a piston 60a capable of fully moving backward.

A skin sheet S whose both ends are supported by a pair of upper and lower rolls R is disposed between the mold 8a and the parison P. In addition, it is a matter of course that the back surface side of the skin sheet S is arranged so as to face the parison P hung down from the die 2 so that the back surface of the skin sheet S is fused with the parison P during molding.

The cooling medium spraying device 10 includes the spraying nozzle 1
1, a temperature detector 12 (in this embodiment, a radiation thermometer), a support frame 13, a guide 15, a movable cylinder 20, a support board 25, and the like. As shown in FIG. 2, the support frame 13 is composed of a vertically long support body V and a horizontally long support body H, which are assembled in a lattice, and the plurality of temperature detectors 12 (4 in this embodiment). A plurality of bases) are mounted near the center of the support H, and a plurality of the bases are arranged in a row in the vertical direction so as to extend in the vicinity of the center of the support frame 13 and are separated in the vertical direction of the parison P. In addition, a plurality of spray nozzles 11 (in this embodiment, 1
2) are arranged.

At this time, since the temperature detector 12 and the spray nozzle 11 are mounted on the support H via a mounting spacer having a spherical seat (not shown), the temperature detector 12 and the spray nozzle 11 are provided. The direction of the spray nozzle 11 can be freely changed as needed. In this embodiment, a mounting spacer having a spherical seat is used in order to make the direction of the sensor freely. However, the mounting spacer may be directly mounted on the support H without mounting the spacer.

Here, the support member V has the rod 20a of the movable cylinder 20 fixed at its tip via a mounting seat 16 and one end of a guide rod 15a at its mounting seat 16b. Further, a movable cylinder 20 and a guide bush 15b in which a guide rod 15a is slidably inserted are fixedly provided on the support board 25. The movable cylinder 20 is operated to move the tip of the rod 20a back and forth with respect to the support board 25. Accordingly, the support body V can be moved back and forth with respect to the support board 25 while sliding with the guide rod 15a as a guide, and the support frame 13 can be moved back and forth with respect to the support board 25.

Then, as shown in FIG. 3A, when the support frame 13 of the cooling medium spraying device 10 is advanced so as to be separated from the support board 25, the support frame 13 moves between the parison P and the skin sheet S. When the support frame 13 is retracted so as to approach the support board 25 as shown in FIG. 3B, the support frame 13 is positioned outside the mold clamping device. The support board 25 is fixed to a machine base (not shown).

Next, referring to FIG.
Will be described. In FIG. 5, a supply source of a cooling medium (compressed air in the present embodiment) not shown is connected to a stop valve 35,
The stop valve 35 and a plurality of electromagnetic switching valves 32 are connected. When the stop valve 35 is opened, the compressed air (also referred to as cooling gas) supplied through the stop valve 35 is supplied to the electromagnetic switching valve 32. Can be reached. Also, since the electromagnetic switching valve 32 is normally closed, the cooling gas that has reached the electromagnetic switching valve 32 is cut off by cutting off the flow path there, and does not flow out before the electromagnetic switching valve 32. The variable throttle valve 31 is connected to the end of the valve 32, and the spray nozzle 11 is connected to the variable throttle valve 31. When the electromagnetic switching valve 32 is excited and opened, the cooling gas is supplied to the electromagnetic switching valve. 32
, And the passed cooling gas can be blown to the outside from the spray nozzle 11 through the variable throttle valve 31.

The controller 100 includes a temperature detector 12
And the electromagnetic switching valve 32 are connected, the surface temperature measured by the temperature detector 12 can be sent to the controller 100 as a measurement signal, and the electromagnetic switching valve 32 can be freely excited by the switching signal from the controller 100. It is configured to be able to switch. In the controller 100, the set temperature and
The surface temperature measured by the temperature detector 12 can be compared. When the surface temperature measured by the temperature detector 12 is high, the electromagnetic switching valve 32 is switched so that the cooling gas can be sent from the spray nozzle 11. It is configured.

In this embodiment, since the skin sheet S is stuck to only one side of the parison P, the cooling medium spraying device 10 is arranged so as to be interposed between the parison P and the mold 8a. Although only one side of P is cooled, when the skin sheets S are stuck on both sides of the parison P, the cooling medium spraying device 10 is connected to the parison P and the mold 8.
It is necessary to cool the parison P from both sides by arranging it between b.

Further, even when the skin sheet S is stuck on only one side of the parison P, the cooling medium spraying device 10
If only one side of the parison P is cooled by this, the temperature distribution of the parison P varies, causing a problem such as deformation of the parison P.
0 must be arranged between the parison P and the mold 8b, and the whole must be uniformly cooled from both sides.

In this embodiment, the relief valve 36 and the silencer 37 are connected as shown in FIG. 5 in order to ensure the safety of the apparatus.

In this embodiment, compressed air is used as the cooling medium, but nitrogen gas or the like may be used.
Further, if the cooling medium or the cooling medium whose temperature is lower than the normal temperature is used in the present invention by using a cooler or adiabatic expansion of gas, the parison P can be cooled more effectively.

In this embodiment, compressed air is used as the pressurized fluid blown into the parison P. However, other pressurized fluids such as compressed nitrogen and high-pressure steam may be used.

The operation of the embodiment of the present invention performed using the lamination blow molding apparatus 1 configured as described above will be described. The molten resin (polypropylene in this embodiment) supplied to the resin supply port 2a by the injection device 4 is injected from the lowermost annular passage 7 through the annular passage between the die head 2b and the mandrel 3. An extruded hollow parison P is formed. Dice head 2
The distal end of the hollow parison P injected from the above is sandwiched and fused by a parison pinch (not shown) to form a bag. Compressed air is introduced into the bag-shaped parison P, and while the bag is slightly inflated, the die is A more desired length is hung, and a hollow parison P hung from the die 2 is inserted between a pair of left and right molds 8a and 8b. At this time, mold 8
a and a parison P, by a pair of upper and lower rolls R,
A skin sheet S supported so as to apply an appropriate tension is provided.

The skin sheet S used in the embodiment of the present invention is a thin sheet of a synthetic resin (in this embodiment, polypropylene), and the thickness of the synthetic resin sheet is as follows.
It was 0.05 to 0.1 mm.

Further, at this time, the support frame 13 of the cooling medium spraying device 10 is advanced so as to be separated from the support plate 25,
The support frame 13 is positioned so as to be interposed between the parison P and the skin sheet S. Then, the plurality of temperature detectors 12 arranged in the vertical direction of the parison P are used to measure the surface temperature in the vertical direction of the parison P at a plurality of points from the upper part to the lower part of the parison P (in the embodiment of the present invention, 4 points) Measure and the measured surface temperature is used as a measurement signal by the controller 100.
Send to The controller 100 compares a preset temperature (sometimes referred to as a set temperature) with the measured surface temperature. If the measured surface temperature is high, the temperature detector 1
The electromagnetic switching valves 32 of the spray nozzles 11 (three spray nozzles 11 arranged on the same support H as the temperature detector 12 in this embodiment) capable of spraying the cooling gas near the temperature measurement unit 2 are switched. The cooling gas is blown from the spray nozzle 11 toward the parison P to cool the parison P, and when the set temperature and the measured surface temperature become the same, the electromagnetic switching valve 32 is switched to stop blowing the cooling gas. .

After the blowing of the cooling gas is completed, the support frame 13 is retracted so as to approach the support board 25, and is taken out of the mold clamping device.

Next, the mold is clamped, and after the mold clamping is completed, compressed air is injected into the piston head side of the blow pin forward / backward moving cylinder 60, and the blow pin 61 is advanced to the parison P side, and the parison P is penetrated. To make it protrude into the parison inside 50 of the parison P. Then, compressed air (6 kg / cm ² in this embodiment) is blown into the parison inside 50 placed in the mold through the blow pin 61 to expand the parison P under pressure, so that the parison P and the skin sheet S are expanded. And into a predetermined shape along the mold cavity,
The parison P and the skin sheet S are fused together to form a mold 8
Cool and take out.

The above-mentioned set temperature is determined by the skin sheet S after molding.
In consideration of the state of the surface sheet, if a problem occurs due to a high surface temperature of the parison P such as erosion or perforation of the skin sheet S, it is necessary to lower the set temperature. Parison P such as poor fusion between S and parison P or improper transfer of mold surface to skin sheet S
If a problem occurs due to the low surface temperature of the device, it is necessary to increase the set temperature. Also, Parison P
If the above-mentioned problem caused by the high or low surface temperature occurs locally, the direction of the spray nozzle 11 is changed to change the spray direction, or the variable throttle valve 31 is used.
The flow rate of the cooling gas hitting the damaged portion is adjusted by adjusting the opening of the cooling gas.

In the present invention, unlike the case where the parison P is cooled by being allowed to cool in the air, the parison P is rapidly cooled by spraying a cooling medium thereon. Since the parison P and the skin sheet S are in contact with each other in a state where the temperature is low, the parison P and the skin sheet S do not immediately fuse with each other, and the parison P pushes and spreads the skin sheet S, and the skin sheet S is appropriately stretched by the parison P. . Then, after the skin sheet S is appropriately stretched by the parison P, the surface temperature of the parison P rises again, albeit slightly, due to the latent heat of the entire parison P, and the surface temperature of the parison P rises. Thus, the skin sheet S and the parison P are fused, so that good fusion can be performed. Therefore, as described above, the wrinkles of the skin sheet S caused by being immediately fused to the parison P before the skin sheet S is appropriately stretched, and the air between the skin sheet S and the parison P are bitten. And the problem of poor fusion does not occur.

It should be noted that even if the surface temperature of the parison P slightly rises again due to the latent heat of the parison P, the skin sheet S
Is spread by the parison P, and the surface temperature of the parison P rises again in a state where the skin sheet S and the mold 8a are in close contact with each other, so that the heat transmitted from the parison P to the skin sheet S immediately S is transmitted to the mold 8a, and a sharp rise in the temperature of the skin sheet S can be avoided.

In general, a difference in surface temperature occurs between the injection start portion and the injection end portion of the parison P having different elapsed times from the injection from the die 2, and the parison P gradually increases from the injection end portion to the injection start portion. Although the surface temperature tends to decrease, in the present invention, a plurality of the temperature detectors 12 are arranged in the longitudinal direction of the parison P and are spaced from each other in the vertical direction of the parison P to the injection end portion which is the upper part of the parison. The surface temperature in the vertical direction of the parison P is measured until the temperature of each of the plurality of temperature detectors 12 is increased. Since the temperature measurement unit cools down to the set temperature, from the top to the bottom of the parison, the parison P is cooled so that the surface of the parison P has a substantially uniform temperature in the vertical direction, There is almost no variation in the degree distribution.
As described above, if the lamination blow molding is performed using the parison P having a uniform surface temperature at an appropriate temperature,
It is possible to prevent erosion and the like occurring in the skin sheet S, and does not cause a problem such as poor fusion between the skin sheet S and the parison P.

The parison P is made of polypropylene, and the skin sheet S has a thickness of 0.05 to 0.1.
In the case of the embodiment of the present invention using a polypropylene sheet of mm, the parison temperature of the polypropylene before cooling was 200 ° C., whereas the appropriate temperature of the parison surface used in the lamination blow molding method was 170 ° C. ~ 1
80 ° C. is preferable, and the set temperature is 170 ° C. to 180 ° C.
By doing so, a bonded molded article having a good appearance could be obtained.

Similarly, the parison P is made of polypropylene, and the skin sheet S has a thickness of 0.1 mm.
The appropriate temperature of the parison surface when using a polypropylene sheet of 02 to 0.05 mm is preferably 160 to 170 ° C, and the set temperature is 160 to 170 ° C,
Further, when polypropylene is used as the material of the parison P and a polypropylene sheet having a thickness of 0.1 to 1 mm is used as the skin sheet S, the appropriate temperature of the parison surface is preferably 180 ° C to 200 ° C, and the set temperature is 1
80 ° C to 200 ° C.

Similarly, the material of the parison P is AB
S (acrylonitrile butadiene styrene polymer)
, And as the skin sheet S, the thickness is 0.02 to 0.
When using a 05mm ABS sheet, AB before cooling
Although the parison temperature of S is 220 ° C., the appropriate temperature of the parison surface is preferably 160 ° C. to 170 ° C., the set temperature is 160 ° C. to 170 ° C., ABS is used as the material of the parison P, and the skin sheet S As the thickness is 0.0
When a 5-0.1 mm ABS sheet is used, the appropriate temperature of the parison surface is preferably 170 ° C. to 180 ° C., the set temperature is 170 ° C. to 180 ° C., and ABS is used as the material of the parison P. When an ABS sheet having a thickness of 0.1 to 1 mm was used as the skin sheet S, the appropriate temperature of the parison surface was preferably 180 ° C to 200 ° C, and the set temperature was 180 ° C to 200 ° C.

Also, in this embodiment, when the set temperature and the measured surface temperature become the same, the electromagnetic switching valve 32
Was used to stop the spraying of the cooling gas, but the difference between the set temperature and the measured surface temperature was calculated to determine the cooling gas ejection time, and the spraying was performed using a timer or the like. A method may be used in which the cooling gas is sprayed only during the time, and after the spraying time has elapsed, the blowing of the cooling gas is stopped to cool the parison P to an appropriate temperature.

In this embodiment, a method is used in which the surface temperature of the parison P is measured, and cooling is performed by blowing a cooling gas so that the set temperature and the measured surface temperature become the same. If the surface temperature of the parison P is high due to a high surface temperature such as erosion or perforation of the skin sheet S in consideration of the state of the skin sheet S after molding without considering the surface temperature, , The time for spraying the cooling medium is lengthened, and poor fusion between the skin sheet S and the parison P,
If a problem occurs due to a low surface temperature of the parison P such as a transfer failure of the mold surface to the skin sheet S, the parison P is cooled to an appropriate temperature by a method such as shortening the spraying time. Such a method may be used.

When the above-mentioned problem caused by the high surface temperature of the parison P occurs locally, cooling gas is blown only to the damaged portion while checking the condition of the skin sheet S after molding. In addition, the cooling gas may be blown for a time until the damaged portion is no longer damaged.

Further, in the skin sheet S which is particularly easily melted and hardly fused, the above-mentioned problems caused by the high or low surface temperature of the parison P occur simultaneously in the same portion of the parison P. If the temperature is not solved even if the set temperature is changed, for example, in the case where the mold surface is not transferred to the eroded portion of the skin sheet S despite the erosion of the skin sheet S, Skin sheet S
The parison P is cooled with a cooling gas until the temperature reaches the lower set temperature in the above-described process, and the skin sheet S is cooled. After shaping into a predetermined shape along the mold cavity, before cooling in the mold 8, a heating medium is passed through a heating temperature control tube arranged in the mold 8 a to make the mold cavity face. By raising the temperature to a desired temperature, the skin sheet S is heated to a softening temperature of the resin constituting the skin sheet S, and then a cooling medium is passed through a cooling temperature control tube provided in the mold 8a to form a mold cavity. A parison that cools the surface to cool and solidify the surface of the skin sheet so that the mold cavity surface is transferred to the surface of the skin sheet by cooling, and the mold surface is not transferred to the skin sheet S. Low surface temperature of P It is possible to prevent many of the problems arise because.

As a method for heating and cooling the mold,
A method for controlling the temperature of a molding die as disclosed in JP-A-6-328452 is known. Also in this embodiment, a heating medium (heating oil in this embodiment) is passed through the die. A plurality of heating temperature control tubes capable of flowing through the mold and a plurality of cooling temperature control tubes through which a cooling medium (in this embodiment, cooling water) can flow are disposed in the mold 8a. When heating the mold 8a, a heating medium is passed through the heating temperature control tube to heat the mold, and when cooling the mold, the heating temperature control tube is The supply of the heating medium was stopped, and the mold was cooled by flowing the cooling medium through the cooling temperature control tube.

Further, even when the skin sheet S is heated to the softening temperature of the resin constituting the skin sheet S by the above-described heating method, the entire surface of the skin sheet S is heated in a state where the cavity surface of the mold 8a is in close contact with the skin sheet S. The parison P and the skin sheet S are heated in a state where the parison P and the skin sheet S are in close contact with each other and are almost integrated with each other, so that the heat transmitted from the mold 8a to the skin sheet S is difficult. However, the skin sheet S is immediately transmitted to the parison P from the skin sheet S, and a sharp rise in temperature of the skin sheet S is avoided, so that problems such as erosion and the like hardly occur.

In this embodiment, the skin sheet S
Is formed into a predetermined shape along the mold cavity, and then the mold 8 is heated to a desired temperature, but before the skin sheet S is formed into a predetermined shape along the mold cavity. Therefore, the mold 8 may be heated in advance to a desired temperature.

In the embodiment of the present invention, polypropylene and ABS are used as the material of the skin sheet S, but polystyrene, polyvinyl chloride or the like may be used.
Further, in the embodiment of the present invention, polypropylene and ABS are used as the material of the parison P, but polyethylene or the like may be used. In addition, since the parison P and the back surface of the skin sheet S need to be fused at the time of molding, when the materials of the skin sheet S and the parison P are combined, the fusion property between the material of the skin sheet S and the material of the parison P is high. Need to be. Further, when the material of the skin sheet S and the material of the parison P do not have a fusion property, the back surface of the skin sheet S is bonded to the back surface of the skin sheet S by fusion or bonding. Must be processed.

In the embodiment of the present invention, the skin sheet S has a single layer structure, but may have a multilayer structure. In such a case, at least one of the multilayer structures is made of a material which is vulnerable to heat. What is necessary is just to be composed of polypropylene, ABS, polyethylene, polyurethane, etc.
The material other than the layer of the heat-sensitive material constituting the skin sheet S is not particularly limited, but the back surface of the skin sheet S that is fused with the parison P at the time of molding is a material that is fusible with the parison P, The back surface of the skin sheet S needs to be treated so that the back surface of the skin sheet S and the parison P can be integrated by fusion or bonding.

Further, another embodiment of the bonding blow molding method according to the present invention (sometimes referred to as a second embodiment).
Used was a skin sheet S having a foamed resin. Second
The skin sheet S having a foamed resin used in the example has a two-layer structure, and a foamed resin (in the second example, a polypropylene sheet in the second example) is provided on the back side of the sheet. Used a layer of polypropylene). The thickness of the synthetic resin sheet used in the second embodiment is 0.5 to 1 mm, and the thickness of the foamed resin layer on the back side is 2 mm.

Originally, a porous material such as a foamed resin,
Since air bubbles (foaming) become a heat insulating layer and heat is hardly transmitted, it takes a long time for the heat of the parison P to be transferred and the foamed resin to be heated. However, the foamed resin is easily compressed by pressure, and in the compressed state, bubbles (foaming) are crushed and the heat insulating effect is weakened, so that the resin is heated in a relatively short time. Therefore, when the surface temperature of the parison P is high and the surface temperature of the parison P is non-uniform as in the conventional lamination blow molding method, the foamed resin is locally heated and the extremely high temperature portion is formed. Occurs, and
Since the foamed resin in an extremely high temperature receives high pressure, the foamed resin is melted or crushed.

According to the present invention, the foamed resin layer is made of parison P
Thus, it is possible to prevent the resin from being locally heated to an extremely high temperature, so that damage such as melting or crushing of the foamed resin can be prevented.

The skin sheet S containing the foamed resin
The thickness of the sheet used is preferably thin and preferably 0.5 to 1.5 mm in consideration of shapeability, but is not limited to this as long as shapeability is possible. In addition, since the foamed resin used for the skin sheet S has good extensibility and is relatively easy to shape, it is better to have a little thickness in order to give a soft touch to the product. It is preferable, but not limited to this, because it depends on the degree of demand for softness and the shapeability.

In the embodiment of the present invention, the skin sheet S having the foamed resin has a two-layer structure as described above, but may have a multilayer structure.
Polypropylene, polyethylene,
Polystyrene or the like may be used. Further, as the material of the parison P, polypropylene, polyethylene, ABS or the like may be used. The material other than the foamed resin layer constituting the skin sheet S is not particularly limited. However, since the back surface of the skin sheet S must be fused with the parison P during molding,
It is necessary that the material be capable of adhering to parison P.

Another embodiment of the bonding blow molding method according to the present invention (sometimes referred to as a third embodiment).
A raised layer of synthetic fibers (polyethylene terephthalate in the third embodiment) was formed on the front side of a synthetic resin (polypropylene in the third embodiment) sheet.
A skin sheet S having a layer structure was used. Also in the case where the raised hair is used, it is possible to prevent the falling of the hair caused by the strong raised pressure in the state where the raised resin is locally heated by the heat of the parison P.

The thickness of the sheet used for the brushed skin sheet S is preferably 0.5 to 1.5 mm, which is thin and good in view of shaping properties, but is not limited to this if shaping is possible. Absent. In addition, in this embodiment, polyethylene terephthalate is used as the material of the raised material used for the skin sheet S, and acrylic and nylon are generally used. However, it is not limited to this.

In a third embodiment of the present invention,
Although the skin sheet S having the raised hair has the two-layer structure as described above, the skin sheet S may have a multilayer structure. Further, the material other than the raised material constituting the skin sheet S is not particularly limited, but the back surface of the skin sheet S must be fused with the parison P at the time of molding. is necessary. Further, as the material of the parison P, polypropylene, polyethylene, ABS or the like may be used.

[0060]

As described above, according to the first aspect of the present invention,
According to the invention, the surface of the parison is cooled to an appropriate temperature by spraying a cooling medium to cool it, so that the skin sheet is extremely heated by the heat of the parison during shaping in a mold, Since the skin sheet can be prevented from being damaged by heat or a problem such as opening a hole, and the skin sheet and the parison can be fused well and integrated,
It is possible to obtain a good bonded blow-molded product having no erosion or the like. Further, according to the present invention, the skin sheet is pushed and spread by the parison, and the skin sheet can be fused with the parison in an appropriately stretched state, so that the air is bitten between the skin sheet and the parison. This can prevent appearance defects such as swelling and wrinkles caused by the above. Further, in the case of a parison having a variation in temperature distribution, if the high temperature portion of the parison surface is cooled in the atmosphere until the temperature reaches the appropriate temperature, the temperature of the relatively low temperature portion becomes too low, and the temperature of the parison becomes too low. However, according to the present invention, a good appearance can be obtained by, for example, spraying a cooling gas mainly on the high temperature portion of the parison while observing the condition of the skin sheet after molding. A laminated blow molded product can be obtained.

According to the second aspect of the present invention, as a method of cooling the parison to an appropriate temperature, the surface temperature of the hollow parison ejected from the die is measured by a temperature detector, and the parison is measured by the temperature detector. By blowing the cooling medium to the parison through a spray nozzle until the measured temperature reaches a preset temperature, the parison surface can be cleaned even if the parison temperature changes for any reason during continuous molding. Since it is possible to always cool to a constant appropriate temperature, a stable operation can be performed, and a bonded blow-molded product having a stable appearance and a good appearance can always be obtained.

According to the third aspect of the present invention, there is usually a difference in the surface temperature between the upper part and the lower part of the parison, which are different in the elapsed time from the injection from the die, and the parison surface temperature tends to gradually decrease from the upper part to the lower part. However, by a plurality of temperature sensors arranged in the vertical direction of the parison,
Measure the parison longitudinal surface temperature from top to bottom,
Cooling media are sprayed from different spray nozzles to the vicinity of the respective measuring units of the plurality of temperature detectors to cool them to the set temperature, so that the temperature becomes substantially uniform in the vertical direction of the parison. Since the temperature is at an appropriate temperature without variation, it is possible to prevent melting and the like that occur in the skin sheet when the skin sheet and the parison are fused and integrated, and that the fusion between the skin sheet and the parison is poor. Thus, a bonded blow-molded article having a good appearance can be stably obtained without causing any problems such as the above.

According to the fourth aspect of the present invention, if the above-mentioned problems caused by the high or low surface temperature of the parison occur at the same time and the problem is not solved by changing the set temperature, for example, Even though the sheet is melted, in the case where the mold surface did not transfer to the skin sheet, the above set temperature was lowered and set lower until the occurrence of the melt damage of the skin sheet disappeared, as described above. In such a process, the parison is cooled with the cooling gas until the set temperature is set lower, and the skin sheet is shaped into a predetermined shape along the mold cavity, and then the mold is formed into the skin sheet. By heating to the softening temperature of the resin and then cooling, the mold surface can be transferred well to the skin sheet, and a bonded blow-molded article having a good appearance can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a lamination blow molding machine according to an embodiment of the present invention.

FIG. 2 is an external view of a cooling medium spraying device according to the embodiment of the present invention.

FIG. 3 is a layout diagram showing a positional relationship between a cooling medium spraying device and a mold.

FIG. 4 is a conceptual diagram of a cooling medium behavior when the cooling medium is sprayed.

FIG. 5 is a control flow sheet of the cooling medium spraying device.

FIG. 6 is a conceptual diagram illustrating the inside of a mold during molding.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lamination blow molding device 2 die 8 die 8a die 8b die 11 spray nozzle 12 temperature detector 10 cooling medium spray device 20 moving cylinder 13 support frame 15 guide 25 support plate 61 blow pin 62 high-pressure air blow hole 100 control Vessel P parison S skin sheet R roll H support V support

Claims (4)

[Claims] 1. A cooling medium is sprayed between a pair of left and right dies through a spray nozzle onto a hollow parison suspended from a die, and the surface of the parison is cooled to an appropriate temperature to reach the appropriate temperature. After the skin sheet is interposed between the parison and the mold, the mold is clamped. Subsequently, a high-pressure pressurized fluid is blown into the parison and the inside of the parison is pressurized and expanded, and pressed against the mold surface from the inside of the parison. In this manner, the parison and the skin sheet are shaped into a predetermined shape, and the skin sheet and the parison are integrally bonded and formed. 2. A surface temperature of a hollow parison injected from the die is measured by a temperature detector, and the temperature of the parison is measured through a spray nozzle until the temperature measured by the temperature detector reaches a preset temperature. 2. The method according to claim 1, wherein a cooling medium is sprayed. 3. A plurality of surface temperature detectors arranged in the longitudinal direction of the parison and spaced apart in the longitudinal direction to measure the surface temperature of the parison in the longitudinal direction, and the measuring units for the respective surface temperatures of the parison are set in advance. 3. The lamination blow molding according to claim 2, wherein the cooling medium is sprayed from different spraying nozzles until the temperature reaches a set temperature, so that the surface of the parison is cooled to a substantially uniform temperature in the longitudinal direction. Method. 4. The parison and the skin sheet are formed into a predetermined shape by blowing a high-pressure pressurized fluid into the parison through a blow pin to increase the pressure, and then disposed in a mold. The surface of the skin sheet is heated to the softening point temperature by the mold cavity surface heated to a desired temperature by flowing a heating medium through the heating temperature control tube, and then cooled to the cooling temperature control tube disposed in the mold. The mold cavity surface is transferred to the skin sheet surface by flowing a medium to cool the mold cavity surface to cool and solidify the surface of the skin sheet, wherein the mold cavity surface is transferred to the surface of the skin sheet. 4. The method of laminating blow molding according to claim 2 or claim 3.