JPH0538749A - Heat insulating mold for blow molding - Google Patents

Abstract

PURPOSE:To provide a heat insulating mold for blow molding, the temperature of which can be controlled uniformly irrespective of the shape of a cavity and with which molding cycle can be improved. CONSTITUTION:By the constitution containing porous sintered metal layers 16 along the cavity 12 of a mold 14, any heat insulating layer suitable for shape, even complicated, is produced by utilizing the high formability of sintered material. Otherwise, by providing resin layer on the surface of the cavity 12, double- layered heat insulating layer is formed, resulting in realizing the mold structure having high heat insulating function. Further, through heat exchanging medium passages formed by utilizing the pores 18 within the sintered metal, refrigerant produced with a cooling device is circulated within the sintered metal layer 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat insulating mold for blow molding, and more particularly to a heat insulating mold suitable for improving a product molding cycle.

[0002]

2. Description of the Related Art The blow molding method involves injecting a parison from a die, preblowing the parison formed into a bag by a parison pinch to inflate it slightly, and then closing the left and right molds by a mold clamping device. There is. At the same time as or immediately before the mold is closed, the gas in the cavity is released, and a high pressure is blown into the parison to bring it into close contact with the cavity so that the mold is cooled and molded. After molding, the mold is opened, the product is taken out, and one molding cycle is completed.

By the way, the parison is formed into a predetermined shape by closely contacting with the mold cavity.
During the cycle, the mold is set to a temperature lower than the parison temperature in order to cool and mold the parison in close contact with the cavity, and this temperature is usually kept constant. For this reason, it is general to cast a copper pipe or a spiral pipe inside the mold, and let the heat exchange medium flow through this pipe to control the temperature.

[0004]

However, in the conventional mold, the heat exchange medium passage is formed inside by the copper pipe, but in the case of a large and smooth cavity shape, the cooling property can be maintained to some extent, If the shape of the cavity becomes complicated, the pipe cannot be placed at a constant depth position along the cavity surface, and uniform cooling cannot be achieved. Also, of course, copper pipes,
There is a problem in that the size and number of spiral tubes are limited, and uniform temperature control of the mold cannot be performed.

The present invention focuses on the above-mentioned conventional problems, and enables uniform temperature control of the mold regardless of the shape of the cavity, and blow molding which can improve the molding cycle. It is intended to provide a heat insulating mold for use.

[0006]

In order to achieve the above object, in a blow molding heat insulating mold according to the present invention, first, a porous sintered metal layer is arranged along a mold cavity surface, This is formed by cast-in-molding with a die main material.

In this case, the surface layer portion of the sintered alloy layer is coated with a resin layer to form a cavity surface portion, and the cavity surface portion is formed by casting around with the mold main material, or the porous sintered metal is used. It is also possible to connect a cooling / heating medium supply means to the layer so that the cooling / heating medium can flow through the porous sintered metal layer to allow heat exchange.

In this case, the porous sintered metal layer is formed in advance along the shape of the cavity, and this is casted with, for example, an aluminum alloy as the main material of the mold to form a predetermined mold shape. .. The porous sintered alloy layer may have a relatively large grain size so that pores through which the fluid can pass are formed in the layer. In order to allow the cooling and heating medium to flow through the sintered metal layer having through-holes, the mold is provided with a port communicating with the included sintered metal layer, and this port is connected to a heat exchanger. It is desirable to circulate the refrigerant. Further, an epoxy resin, a silicone resin, a polyimide resin, or the like can be used for the resin layer.

[0009]

According to the above structure, the heat transfer area of the porous alloy layer is several times as large as that of the conventional copper pipe or spiral pipe, and the heat transfer efficiency can be improved. Further, since the sintered metal layer functions as a pore layer, it becomes a heat insulating layer, and it is possible to prevent the heat from the parison from being conducted to the mold body. Further, the temperature control effect is high by passing the cooling / heating medium through the sintered metal layer, and the sintered metal layer is arranged along the cavity surface, so that the entire parison is uniformly cooled. Therefore, uniform cooling can be achieved.

Since the temperature of the die can be raised by the heat of the parison by self-heating and the temperature can be lowered by cooling with the refrigerant, the molding cycle can be shortened while simplifying the temperature control equipment. You can do it.

Further, a resin coating is applied to the surface layer of the sintered alloy layer to form a cavity surface, so that the heat insulating layer can be doubled to improve the heat insulating efficiency. In this case, since the resin layer is impregnated into the sintered alloy in the shape of a wedge, the cooling area is improved, and thus the releasability of the molded product is improved.

In particular, by providing a resin layer on the cavity surface, the heat insulating layer can be made into two layers, and a mold structure having a high heat insulating function can be obtained. By forming the heat exchange medium passage by utilizing the pores inside the sintered metal, it is possible to effectively perform the mold temperature control, and thus to obtain a mold with high temperature controllability.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a blow molding heat insulating mold according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a block diagram of a heat insulating mold 10 for blow molding according to an embodiment. This mold 10 is a pair of left and right molds 1.
0R and 10L, a cavity 12 (12R, 12L) is formed on the mold matching surface, a parison injected from a die (not shown) is sandwiched, and air is blown into the parison to form the mold. A hollow container that matches the closed cavity is formed.

The mold body 14 in such a mold 10
Although (14R, 14L) is formed as a cast product of an aluminum material, in the embodiment, each mold body 14R,
The porous sintered alloy layer 16 is formed inside 14L along the surfaces of the cavities 12R and 12L. The porous sintered metal layer 16 is formed so as to be substantially similar to the cavity 12 so as to surround the cavity 12 from the surroundings when the mold 10 is fitted to the mold 10. The sintered metal layer previously formed by the powder metallurgy method. Each of the molds 10R and 10L is cast by surrounding 16 with an aluminum material as a mold main material. At this time,
As shown in FIG. 1 (2), molten aluminum is impregnated from the surface of the sintered metal layer 16 at the boundary between the mold body 14 made of aluminum as a base material and the sintered metal layer 16, whereby the composite material A region (A in the figure) is formed.

Here, the porous sintered metal layer 16 has sufficient heat resistance for resin molding, and powder metal having a relatively large grain size may be formed by an ordinary sintering method. A large number of pores 18 are formed inside by using a copper-based sintered metal powder. A fluid passage is formed in the sintered metal layer 16 by these pores 18 mutually.
In this embodiment, a coolant is supplied to the fluid passage formed in the sintered metal layer 16 to cool the surface temperature of the mold 10, especially the cavity 12, to a temperature required for resin hardening. Therefore, a coolant supply port 20 and a coolant discharge port 22 are formed in the bottom plate and the top plate of each mold body 14R, 14L,
This is opened in the sintered metal layer 16. Further, a cooling device 24 is installed outside the mold 10, and the refrigerant generated between the device 24 and the mold 10 is pressure-fed and supplied to the refrigerant supply port 20 so that the refrigerant flows inside the sintered metal layer 16. A coolant pipe 26 is provided for returning the coolant discharged from the coolant discharge port 22 after cooling the mold 10 by flowing the coolant. In this case, since the refrigerant to be used has a large resistance to the vent holes of the sintered metal layer 16, a gas refrigerant may be used. Of course, it is also possible to flow the cooling liquid.

The porous sintered metal layer 1 thus constructed
Blow molding work using the mold 10 containing 6 is performed as follows. After the parison is ejected from a die (not shown), the molds are matched with each other by the mold clamping device. Simultaneously with this mold matching, while blowing air into the parison, a cooling medium is supplied from the cooling device 24 to flow the cooling medium into the sintered metal layer 16 for molding. As a result, since the parison initially adheres to the cavity 12, the cavity 12 surface portion of the mold 10 is heated, but since the sintered metal layer 16 is interposed in the middle, this functions as a heat insulating layer, and the sintered metal The mold body 14 on the back side of the layer 16 is prevented from being heated. Then, the refrigerant generated by the cooling device 24 is supplied into the sintered metal layer 16, which flows through the flow passage formed by the internal pores 18 of the sintered metal layer 16, and the cavity 12 as a whole from the outer surface side. Cool. Due to this cooling action, the cavity 12
The parison that is in close contact with is molded into a cavity shape.

According to the above embodiment, the porous sintered metal layer 1
Since 6 is composed of a sintered body of powder metal, its heat transfer area is about 1.5 to 2 times larger than that of conventional cooling copper pipes and spiral pipes due to its porous structure, so heat transfer efficiency is improved. Can be significantly improved. Moreover, since the sintered metal layer 16 is cast around the cavity 16 by the die main material, it functions as a heat insulating layer and a heat exchanger, and controls the temperature rise of the die 10 as a whole. The temperature can be made uniform.

In particular, in the embodiment, the temperature of the mold 10 is raised by self-heating by the heat of the resin (parison), and the temperature is lowered by causing the refrigerant to flow through the sintered metal layer 16, so that the heat exchange equipment is installed. In addition to being simplified, the effect of significantly improving the product molding cycle due to the high cooling effect can be obtained.

Next, a blow molding die according to the second embodiment will be described with reference to FIG. Mold 30 of the second embodiment
Molds the mold body 32 with an aluminum alloy material, and the cavity 34 is formed by the resin layer 36, and the porous sintered metal layer 38 is arranged in the inner layer of the resin cavity 34. At the time of molding 32, it is made to be cast-molded. Therefore, as shown in FIG. 2B, the cross section including the cavity 34 portion is from the cavity 34 side to the resin layer 36 and the sintered metal layer 3
8. The mold body 32 is made of an aluminum alloy layer. That is, epoxy resin, silicone resin,
Alternatively, a composite material impregnated or coated with a resin such as a polyimide resin is formed, and the cavity 34 is formed on the outer surface of the resin layer 36. Then, this composite material is cast around an aluminum alloy material to form a predetermined die 30. As a result, in the boundary layers B and C on the front and back surfaces of the sintered metal layer 38, a composite material of resin and sintered metal (B portion) and a composite material of aluminum alloy and sintered metal (C) are generated.

The blow-molding heat insulating mold 30 thus formed is used in the same manner as in the above-mentioned embodiment. In this mold 30, the resin layer 36 and the sintered alloy layer 38 are provided on the cavity 34 side. Two heat insulating layers are formed by the inner pores 40. The molding temperature is usually about 140 ° C., and the heat resistant temperature of the resin layer 36 is 166 to 260 with epoxy.
C., 316.degree. C. for silicon, and 260.degree. C. for polyimide, so that it is possible to have sufficient heat insulating properties. Further, since the pores 40 in a sintered metal act as a heat insulating function, a mold 30 having a high heat insulating function is provided. It will be. Further, by impregnating the sintered metal layer 38 with the resin layer 36 on the side of the cavity 34, the resin is impregnated into the internal pores 40 in a wedge shape, which has the advantage that the peelability of the molded product can be improved. Be done.

Next, FIG. 3 shows a mold 50 according to the third embodiment.
FIG. This mold 50 has an expansion moderating layer 52 having a coefficient of thermal expansion on the back surface side of the sintered metal layer 38 of the second embodiment and having a coefficient of thermal expansion located between the sintered alloy layer 38 and the mold body 32.
To provide a so-called gradient alloy mold. The relaxing layer 52 may be made of a copper alloy or the like, and the relaxing layer 52 may be provided on the sintered metal layer 38 by thermal spraying or casting. As a result, thermal deformation of the mold 50 during molding is suppressed, the deformation of the mold 50 can be made uniform, and the forming accuracy can be improved. In the figure, region D is a composite material layer of sintered metal and copper alloy,
E is a composite material layer of a copper alloy and an aluminum alloy.

In the above embodiment, the mold body 1
It is also possible to arbitrarily control the temperature distribution inside the mold by using a combination structure in which copper pipes and the like are built into the inside of 4, 32.

[0024]

As described above, according to the present invention,
By incorporating a porous sintered metal layer along the cavity of the mold, the high heat moldability of the sintered metal can be used to provide any heat insulation suitable for even complex cavity shapes. By forming a layer, it is possible to make the temperature distribution of the mold uniform, improve the cooling performance, and since it is possible to make the mold only have a cooling function, it is possible to shorten the molding cycle, The effect of improving the molding workability is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a blow molding die according to a first embodiment and an enlarged cross-sectional view of a main part.

FIG. 2 is a sectional view of a blow molding die according to a second embodiment and an enlarged sectional view of a main part.

FIG. 3 is an enlarged cross-sectional view of a main part of the mold according to the third embodiment.

[Explanation of symbols]

 10, 30, 50 Blow molding die 12 (12R, 12L) Cavity 14 (14R, 14L) Mold body 16, 38 Sintered metal layer 18 Pore 20 Refrigerant supply port 22 Refrigerant discharge port 24 Cooling device 26 Refrigerant pipe 36 Resin layer 52 Expansion and relaxation layer

Claims (1)

[Claims] 1. A heat insulating mold for blow molding, wherein a porous sintered metal layer is arranged along the surface of a mold cavity, and this is cast-molded by a mold main material.