JPS6169406A - Reactive injection molding method and device thereof - Google Patents

Abstract

PURPOSE:To speedily mold resin exterior trim part, resin structural part or the like at low cost by a method wherein rubber mold, simple mold, ceramic mold or the like is employed. CONSTITUTION:In order to perform the vacuum casting, firstly, a vacuum chamber and a mold, which is placed in the vacuum chamber and heated up to the reaction temperature for vacuum casting, are provided at the lower part of an injection section. Secondly, the chamber is evacuated to 5X10<-1>Torr or less before injection. Thirdly, after the predetermined amount of material is injected, the chamber is gradually brought back to the atmospheric pressure. Concretely, agitating blades and gear pumps P1 and P2 are respectively provided to a main material liquid tank A and an assistant liquid tank B for agitation and circulation. Though the deterioration of the material may slightly develop by the circulation of the mate rial, the residual bubbles in the piping are eliminated by said circulation. Because the tanks are evacuated, while the material stands in the tanks, bubbles in the material escape from the material. In addition, valves V1 and V2 are closed during the circulation of the material. When the injection of the material is intended, the valves V1 and V2 are open to pour the liquids in the tanks A and B in a mixing part M and, after that, a valve V5 is open so as to discard the small amount of the liquid in the mixing part M in order to remove epsilon- caprolactam. Finally, the valve V5 is closed and a valve V4 is open for injecting the predeter mined amount I1 of the material into the mold in the vacuum chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a vacuum casting method and apparatus using reactive injection molding, and by using a rubber mold, simple mold, ceramic mold, etc. .

It is used to quickly and inexpensively mold resin mechanical parts, etc.
As an alternative to conventional vacuum casting, a wide variety of small quantities can be produced.2.
This is used as a production method.

The structure of the conventional example and its problems The conventional method had three problems in terms of materials, construction method, and equipment, and the structure of the present invention did not have the structure. Most of the materials used in conventional vacuum casting are urethane-based materials.
There are vacuum casting materials such as H&Niya and Japan On, but the heat resistance (heat distortion temperature is 1s, under 5KLi/Cn) is 100%.
'C or higher and impact resistance (with eyenote) 10
There was no material that could replace the ABS resin material, which has a value of 9.alpha./an or higher.

Without this, conventional vacuum cast products had the disadvantage that they could only be used for prototypes and not for commercial products. Also, conventional urethane materials are 60'
Although the curing reaction temperature was low, an after-cure of 30 minutes to 2.5 hours was required at a temperature of 60'C or higher. This means that the number of times the mold is used is controlled, and metal molds cannot be used, making them unsuitable for high-mix, low-volume production.
It was difficult to produce more than one piece.

Furthermore, in terms of equipment, conventional urethane reactive injection molding machines cannot be heated, making it impossible to inject nylon materials with excellent material properties. In addition, many of the nylon reactive injection molding machines found in literature use collision mixing, which has the difficulty of entraining air, and in order to obtain precision molded products, a unique precision casting machine was required. . In addition, while using the self-made casting machine, the inventors found that the ease of maintenance of the mixing section was critical to the life of the casting machine, and that the maintenance of the main liquid, auxiliary liquid, and cleaning liquid was difficult. They also discovered a problem in which temperature differences affect physical properties during casting.

Purpose of the Invention The purpose of the present invention is to provide a reactive injection molding method for producing precise resin molded products with few air bubbles using a nylon-based main liquid and an auxiliary liquid, which are reactive materials having physical properties that can replace ABS resin materials. The purpose is to provide such equipment.

Structure of the Invention In reactive injection molding where at least two or more liquids are mixed and reacted to form a predetermined shape, the storage tank for each liquid, the cleaning liquid tank, the pump, the mixing part, and the piping can all be heated to a predetermined temperature. each tank is located in an oil tank with at least
The height is longer than the diameter of the cylinder, and it is installed vertically, and the mixing section is located at least half the height of the center of the tank.When repairing the mixing section, you only need to drain about half of the oil from the oil tank, and it can be stored. This is a reactive injection molding machine that can be repaired without lowering the temperature of the material in the tank, and requires low injection pressure. In order to reduce the amount of oil, it is better to have a structure as narrow as possible in the width direction.The pump may be one selected from gear pumps and cylinder pumps (lance cylinder pumps).

The main agent liquid and the auxiliary agent liquid used in the reaction are circulated by a pump, except during injection, from the tank, through the piping, through the pump, through the piping, through the valve, and back into the tank. The main and auxiliary liquids are injected into the mixer section by closing the valve that has passed through the pump and opening the valve of the mixing section installed between the pump and the valve.After the predetermined amount has been injected, the valve is closed and the main agent liquid is injected into the mixer section. After circulating the auxiliary agent liquid, the valve at the tip of the injection part of the mixing part is closed, and the cleaning liquid valve is opened to inject the cleaning liquid into the mixing part to perform the injection cycle. A vacuum chamber and a mold heated to the reaction temperature for vacuum casting are installed in the vacuum chamber, and the chamber is vacuumed to a vacuum of 5 x 10-' Torr or less before injection, and then a predetermined amount of the reaction liquid is injected. , is a reactive injection molding method in which vacuum casting is performed by gradually returning the chamber to atmospheric pressure. Note that the valve and mixing can also be a mixing head using an impingement mixing method. However, in that case, it is possible to replace the vacuum chamber with a mold clamp machine.

In this reactive injection molding method, the reaction liquid is a nylon-based ionic polymer material dust, and the cleaning liquid is ε-caprolactam or a composition thereof. ε-caprolactam has a void of several tens of centimeters at around 90'C, and in order to increase its detergency, a composition prepared by melting a saturated hydrocarbon polymer is preferable.

-・“ Previously, vacuum casting #J) The mold is attached.Polymerization, Eve.7 It is a reactive injection molding method in which silicone rubber is a simple mold or ceramic mold placed at least on the surface that comes into contact with the reaction liquid. .Silicone rubber is suitable for molded products with undercuts, and ceramics are highly durable.

The reactive injection molding method and the apparatus thereof according to claim 4 provide a platform having at least an oil removal tank, a cleaning liquid waste tank, a vacuum pump, a trap thereof, and control units for valves, temperature, pressure, etc. and vacuum chamber/bar,
It consists of three parts: two or more tanks, one or more pumps, a mixing head part, a piping drive motor, gears, and a constant temperature oil tank part that houses everything except the drive valves (electric foundation valves, hydraulic valves, etc.). This is a reactive injection molding apparatus characterized by the following configuration.

DESCRIPTION OF THE EMBODIMENTS In the embodiment of the present invention, as shown in FIG. 1, the main liquid tank B and the auxiliary liquid tank B are provided with stirring blades.
It is circulated by gear pumps P1 and P2, respectively.

Although the material deteriorates to some extent due to circulation, there are no air bubbles remaining in the piping or inside, and by evacuating the tank, the air bubbles will escape while they remain. Also, during circulation, valves V and V
2 is closed. A check valve was used for v6. The liquid is not allowed to flow up to the gauge s Kq/ci. (It is variable from 20 to 9/Ca.) The tank and piping were all made of 5US316, and the gear pump was made by Takachiho Kikai. At the time of injection, valves V and V2 are opened to inject the liquid into the mixing section M, and valve V5 is opened to drain a small amount of liquid to remove ε-caprolactam. Thereafter, valve v5 is closed and valve v4 is opened to inject a predetermined amount. v4
and v5 can also be structured to serve as both. The mixing section M may be a static mixer, but in the actual 1M example, a power mixer was used. After the injection part, v4 r
Close vI y v2, open v3, and pour the molten ε-caprolactam into the valve V, pressed under a predetermined N2 pressure.
.

Open to inject liquid into the mixing section, and open valve v5 to drain liquid. However, process 2 also needs to be heated to 80'C, and the piping is installed in a constant temperature oil bath at 100'C. The nylon material used in the present invention is U (manufactured by Ube Industries).
It is B-X.

In addition, as shown in FIG. 2, the embodiment shown in FIG.
A constant temperature oil tank section 1 in which all reactive injection molding functions are installed, a vacuum chamber section 2, a role to be installed at the height of the operator 17, a valve 7 and tank 8 for draining oil from the constant temperature oil tank, and a waste liquid tank 11. and the vacuum chamber at 5 × 10-' Torr.
A vacuum pump 16 and a trap 16 that suck up to
It consists of a stand 21 having a control block, and the casting mold can be put in and taken out at the position shown at 19,
The vacuum chamber is suctioned to below 5×1Φ-' Torr by closing the valve 14 and opening the valve 13 and operating the vacuum pump. It is preferable that the injection part has a mechanism that moves up and down, but in this example, the nozzle was brought into close contact manually. After injection,
The valve 9 (Vs in FIG. 1) is opened to drain the liquid through the waste/liquid pipe 10. This injection cycle cannot be used permanently, and it is necessary to periodically replace the mixing section and valve section, but in order to make this process more efficient, the oil level in the constant temperature oil tank is adjusted to the mixing section. The oil is drained to an oil level 20 where no oil remains, and the pump section 22, valve section 23, and mixing section 24 can be repaired or replaced. The main agent liquid, auxiliary agent liquid, and cleaning liquid (ε-caprolactam) solidify at temperatures below 80'C, but with such a configuration, they can remain molten.
It is possible to replace it. Also, when left at night, the oil tank may cool down and the mixed liquid remaining in the mixing section may gel during the standing time, but this is also caused by lowering the oil level in this way, which cools down the mixing section rapidly. is also possible. In other words, the number of maintenance operations could be reduced. In addition, the power mixer section is always filled with the mixed liquid of the main agent liquid and the auxiliary agent liquid, and since the ε-caprolactam is injected into a vacuum without entraining air bubbles, the air bubbles in the mold are injected. There is little residue, there are few bubbles, and precise casting is possible.

Table 1 shows the stability of physical properties (molded product) and the number of maintenance times depending on the temperature control method. Oil tank control has an effect on both. Further, in this example, an addition polymerization type rubber mold was used, but by heating it to 150°C, the mold could be removed in 3 minutes. It has been found that condensation polymerization type molds cannot be used for molding due to the phenomenon of whitening of the surface. It was possible to mold the ceramic mold using the vacuum casting method, although there was a problem with the surface gloss. When casting in air, whitening still remains on the surface of nylon molding in a 6-ceramic mold, but casting in a vacuum or with N2
It is best to do it inside. Table 2 shows the differences in curability depending on the mold.

FIG. 3 shows a more detailed configuration diagram of the embodiment. Main liquid tank 26, auxiliary liquid tank 27, cleaning liquid tank 28, piping 29, gear pump 30, and its motor 33
, valve block 31, power mixer 32 and its motor 3
4 is everything except the motor, heater 38 and temperature sensor 4
It is provided in a constant temperature oil tank 25 whose temperature is controlled at zero. Further, the tank is provided with a stirring blade motor 35 and a thermocouple 36 at the raw material input port 39, and a lowest position detection liquid level gauge 37 is provided in the main liquid and auxiliary liquid tanks. The constant-temperature oil tank has a T-shape when viewed from above, has a vacuum chamber 42 at the bottom of the injection section, and is provided with a viewing window 41 so that the situation of liquid injection into the mold 43 can be observed.

The reason why the raw material input port is large and faces toward the rear is to make it easier to input all raw materials from the rear, and it is also slanted. A hopper can also be installed at this input port. The stirring blades of the tank are fixed at the top and bottom of the tank, and the motor is designed to be removed together with the lid.

It is believed that the removal of the lid will be made easier by installing the gear pump motor on the side of the T-shaped pump section.

(Hereinafter in the margin) Effects of the Invention In the present invention, as described above, by placing the tank, piping, mixing part, etc. in a constant temperature oil bath, the reaction uniformity of the mixed liquid is increased and stable polymerization is possible. Also, circulation,
Using the vacuum casting method, we were able to obtain vacuum-cast resin parts with few bubbles and good properties. In addition, it became possible to easily obtain exquisite items using rubber molds and ceramic molds. Furthermore, the nylon-based material UB-X as an alternative material for BS can be provided as equipment capable of stable molding, so it has great industrial value.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the configuration of tanks, piping, valves, mixing parts, etc., Fig. 2 is a schematic diagram showing the structure and characteristics of the actual flow side of the present invention, and Fig. 3 is an embodiment of the present invention. FIG. 3 is a front partial cross-sectional view of a constant temperature oil bath section and part of a vacuum chamber, and FIG. 3 is a plan view thereof. 1... Constant temperature oil tank section, 2... Vacuum chamber, 3 evenings, 11... Waste liquid tank, 16...
...Vacuum pump, 21...Base part. Name of agent Patent attorney Toshio Nakao and 1 other person Area Area

Claims (5)

[Claims] (1) The main agent liquid and the auxiliary agent liquid used for the reaction are circulated by a pump, except during injection, from the tank, through the piping, through the pump, through the piping, through the valve, and back into the tank. The main and auxiliary liquids are injected into the mixer section by closing the valve that has passed through the pump and opening the valve of the mixing section installed between the pump and the valve.After the predetermined amount has been injected, the valve is closed and the main agent liquid is injected into the mixer section. After circulating the auxiliary agent liquid, the valve at the tip of the injection part of the mixing part is closed, and the cleaning liquid valve is opened to inject the cleaning liquid into the mixing part to perform the injection cycle. A vacuum chamber and a mold heated to the reaction temperature for vacuum casting are installed in it, and the chamber is vacuumed to a vacuum of 5 x 10^-^1 Torr or less before injection, and then, after the predetermined amount is injected, the chamber is heated to a reaction temperature for vacuum casting. A reactive injection molding method that involves vacuum casting by gradually returning the material to atmospheric pressure. (2) The reactive injection molding method according to claim 1, wherein the reaction liquid is a nylon-based ionic polymer material, and the cleaning liquid is ε-caprolactam or a composition thereof. (3) The reactive injection molding method according to claim 1, wherein the mold for vacuum casting is a simple mold or a ceramic mold in which addition polymerization type silicone rubber is placed at least on the surface in contact with the reaction liquid. . (4) The storage tank for each liquid, the cleaning liquid tank, the pump, the mixing part, and the piping for reactive injection molding, in which at least two or more liquids are mixed and reacted to form a predetermined shape, can all be heated to a predetermined temperature. each tank is located in an oil tank with at least
It has a height longer than the diameter of the cylinder, is installed vertically, and the mixing section is located at least half the height of the center of the tank, so when repairing the mixing section, you only need to drain about half of the oil from the oil tank. Reactive injection molding equipment that allows repair without lowering the temperature of the material in the storage tank. (5) The reactive injection molding apparatus according to claim 4, which includes at least an oil removal tank, a cleaning liquid waste tank, a vacuum pump and its trap, and a control section for controlling valves, temperature, pressure, etc. A base and a vacuum chamber,
A reactive injection molding device comprising three parts: two or more tanks, one or more pumps, a mixing head part, and a constant temperature oil bath part in which all piping is housed.