JPH018335Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a mixing head installed in a reaction injection molding apparatus.

Conventionally, reaction injection has a mixing head body equipped with a mixing chamber and a plurality of injection nozzles opening into the mixing chamber, and injection molding is performed by injecting separate stock solutions from each injection nozzle into the mixing chamber at high pressure. Molding devices are known. By the way, in this type of reaction injection molding equipment, improvements have been made in the past in terms of the strength of the mixing head body, which is related to the lifespan of the mixing head body, or in terms of the shape of the injection nozzle, which controls the shape of the jet flow in the mixing chamber when mixing raw solutions. Various improvements have been made, and although performance has been improved in these areas, the following problems have arisen in aspects different from those mentioned above.

The stock solution used in reaction injection molding is usually stored in a stock solution tank, and is sent to the mixing head main body and injected into the mixing chamber from an injection nozzle as needed. Normally, the stock solution is kept at a predetermined temperature in the stock solution tank to facilitate the reaction in the mixing chamber, but when the stock solution leaves the stock solution tank and reaches the mixing head, heat is generated in the mixing head itself. As a result, the temperature of the stock solution decreases, causing an imbalance in the temperature of the stock solution during mixing, which may impede the reaction.

In addition, injection molding in which a material that is solid at room temperature is melted in a stock solution tank (for example, nylon RIM)
When molding) is performed using a conventional mixing head, the above phenomenon occurs, and the stock solution often solidifies in the mixing head before injection, making injection difficult.Each time it solidifies, it is necessary to disassemble and clean the mixing head. There was a practical problem.

In this invention, injection nozzles are provided in each of the plurality of stock solution inflow holes opening into a mixing chamber formed in the injection cylinder, an outflow hole is provided next to each of the stock solution inflow holes, and an injection nozzle is provided in the injection cylinder. In the retreating state from the mixing chamber toward the outflow hole, the injection nozzle is connected to the mixing chamber and the connection between the stock solution inflow hole and the outflow hole is cut off, and in the forward state into the mixing chamber, the injection nozzle is connected to the outer peripheral surface. In a mixing head of a reaction injection molding machine, a spool is inserted movably in the axial direction, which communicates with the outflow hole through the formed groove and disconnects the injection nozzle from the mixing chamber. The above-mentioned problems of the conventional technology have been solved by providing a flow path through which a heat medium flows in the flow direction of the raw solution flowing into the outlet hole, along the raw solution outlet hole, the injection cylinder, and the outlet hole. It is an object of the present invention to provide a mixing head for a reaction injection molding apparatus, which allows various injection molding operations to be carried out smoothly by adjusting the temperature of the stock solution within the mixing head within a predetermined range.

This invention will be explained below with reference to the drawings.

Figures 1 and 2 show an embodiment of this invention, and the reaction injection molding apparatus A consists of a cylindrical mixing head body (hereinafter referred to as the head body) 1, and a head body 1 provided with a cylindrical mixing head body (hereinafter referred to as the head body). It mainly consists of a spool 4 that slides within the injection cylinder 3 and a hydraulic mechanism 5 that moves the spool 4. The head main body 1 includes stock solution inflow holes 6, 6 that open into the injection cylinder 3 facing each other with the injection cylinder 3 in between, and openings of each of these inflow holes 6, 6 on the injection cylinder 3 side. injection nozzle 7 fixed to
7, and well-known circulating stock solution outflow holes 8, 8 which are opened into the injection cylinder 3 on the side of the hydraulic mechanism 5 from the stock solution inflow holes 6, 6 are provided, respectively.

In addition, by pulling the spool 4 from the injection nozzle 7 toward the hydraulic mechanism 5 side by the hydraulic mechanism 5, a mixing chamber S is formed in the injection cylinder 3, and the hydraulic pressure of the injection cylinder 3 is The opening on the side opposite to the mechanism 5 side is used as the injection port 3a. Further, a groove 9 is provided on the outer circumference of the spool 4, which communicates the inflow hole 6 and the outflow hole 8 when the spool 4 is extended to the injection port 3a.
is provided.

The head body 1 has one end attached to the outer periphery of the head body 1 between the inlet hole 6 and the outlet hole 8 closer to the inlet hole 6, and the other end attached to the head body 1 closer to the hydraulic mechanism 5 than the outlet hole 8. The head body 1 has openings on the outer periphery of the main body 1, and the central part is close to the injection cylinder 3.
Heat medium flow paths D, D formed by bypassing the outflow hole 8 are provided inside. Although not shown in the drawing, the circulation passage D is connected to a circulation passage, a circulation pump, and a temperature controller, and the heating medium whose temperature is controlled by the temperature controller is passed through the circulation passage to the circulation passage D. The flow path D and the heat medium constitute a temperature control means F.

Next, the operation of this device configured as described above will be explained.

When performing reaction injection molding, a heat medium is flowed into the flow path D in the direction shown by the arrow in the figure to raise the temperature of the head body 1 to the melting point of the stock solution used for molding, and then As shown, the spool 4 is pulled by the hydraulic mechanism 5 to form a mixing chamber S, and the stock solution is injected from the injection nozzles 7, 7. At this time, the stock solution enters the stock solution inflow hole 6 from the stock solution tank as is well known, but the stock solution does not solidify in the stock solution inflow hole 6 because the temperature of the head body 1 is at the melting point temperature of the stock solution. Furthermore, even if some solidified stock solution remains in the head body 1, the solidified stock solution can be reused by flowing a heat medium through the flow path D to raise the temperature of the head body 1 as described above. It can be melted and reaction injection molded. Therefore, even in reaction injection molding using not only a stock solution with a high melting point but also a material that is solid at room temperature, reaction injection molding can be carried out smoothly without unnecessarily solidifying the stock solution within the head body 1. Therefore, nylon RIM molding can be carried out freely. On the other hand, the temperature of the head body 1 may be appropriately adjusted to a temperature other than the melting point of the stock solution at which the stock solution does not solidify and is easily reacted.

As explained above, in this invention, injection nozzles are provided in each of the plurality of stock solution inflow holes opening into a mixing chamber formed in an injection cylinder, and an outflow hole is provided next to each of the stock solution inflow holes. , when the injection nozzle is retracted from the mixing chamber toward the outflow hole in the injection cylinder, the injection nozzle is connected to the mixing chamber and the communication between the stock solution inflow hole and the outflow hole is cut off, and when the injection nozzle is moved forward into the mixing chamber, the injection nozzle is connected to the mixing chamber. In a mixing head of a reaction injection molding apparatus, a spool is movably inserted in the axial direction, which connects the injection nozzle to the outflow hole through a groove formed on the outer circumferential surface and disconnects the injection nozzle from the mixing chamber. Since a flow path is provided to allow the mixture to flow, the temperature of the mixing head body is raised to the melting point of the stock solution to be injected, thereby preventing the stock solution from solidifying unnecessarily in the mixing head body. Therefore, it has excellent effects such as not only reaction injection molding that uses a stock solution with a high melting point, but also reaction injection molding (for example, nylon RIM molding) that uses a stock solution that has a low melting point and solidifies at room temperature can be performed freely. .

In addition, in this invention, the heat medium flow path is
The heating medium is provided along the raw solution inflow hole, the injection cylinder, and the outlet hole, and is configured to flow in the flow direction of the raw solution flowing from the raw solution inlet hole to the outlet hole through the groove, so that the most important injection The temperature of the stock solution at the nozzle portion can be controlled with high precision. In other words, when the heating medium is flowed in the opposite direction to the flow direction of the undiluted solution, there are cases in which the undiluted solution is flowing through the outflow hole in a circulating state and cases in which it is not (injected into the mixing chamber from the injection nozzle). In this case, there is a difference in the amount of heat of the heating medium at the injection nozzle part (in the case of the former circulation state, the raw liquid flowing through the outflow hole takes away the heat from the heating medium), so the temperature at the injection nozzle part changes, and temperature control However, in this design, the stock solution and the heating medium flow in the same direction and reach the injection nozzle, so this does not occur and the temperature of the stock solution injected from the injection nozzle is controlled. can be done accurately. Furthermore, since the heat medium flow path is provided along the injection cylinder, the groove portion of the spool will not be clogged with the stock solution during circulation of the stock solution.

[Brief explanation of the drawing]

The drawing shows one embodiment of this invention.
The figure is a schematic cross-sectional view showing the injection stopped state, and FIG. 2 is a schematic cross-sectional view showing the injection state. A... Reaction injection molding device, 1... Mixing head main body, 7... Injection nozzle, F... Temperature control means, S
...Mixing room.

Claims (1)

[Scope of utility model registration request] An injection nozzle 7 is provided in each of the plurality of stock solution inflow holes 6 to open into a mixing chamber S formed in the injection cylinder 3, and an outflow hole 8 is provided next to each of the stock solution inflow holes 6, and 3, when the injection nozzle 7 is retracted from the mixing chamber S toward the outflow hole 8 side, the injection nozzle 7 is connected to the mixing chamber S, and the communication between the stock solution inflow hole 6 and the outflow hole 8 is cut off, and the inside of the mixing chamber S is A spool 4 that connects the injection nozzle 7 to the outflow hole 8 through a groove 9 formed on the outer circumferential surface and disconnects the injection nozzle 7 from the mixing chamber S in the forward movement state is inserted so as to be freely movable in the axial direction. In the mixing head of the reaction injection molding apparatus, a flow path D through which a heating medium flows in the flow direction of the stock solution flowing from the stock solution inflow hole 6 to the outflow hole 8 through the groove 9 is connected to the stock solution inflow hole 6, the injection cylinder 3,
and a mixing head of a reaction injection molding apparatus, characterized in that it is provided along the outflow hole 8.