JPH0442092Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an after-mixer for mixing raw materials provided in a mold used in reaction injection molding.

(Prior technology) Reaction injection molding (hereinafter referred to as RIM molding) involves stirring and mixing RIM molding raw materials such as polyisocyanate and polyol or lactam and caprolactam and casting them into the cavity of a mold, and then reacting and curing them at high speed to form a molded product. This technology is widely used for molding automotive exterior products such as bumpers, furniture, building materials, and other fields.

By the way, the performance of the molded product in the RIM molding described above is greatly affected by the stirring and mixing state of the RIM molding raw materials, and if the stirring is insufficient, minute pores may occur on the surface of the molded product, the strength may decrease, etc. Alternatively, when foamable raw materials are used, defects such as non-uniformity of cells and generation of flow patterns occur.

In RIM molding, stirring of the RIM raw materials is mainly carried out in a casting machine attached to the mold, but in reality, stirring by only this casting machine often does not sufficiently mix the raw materials.

Therefore, in general, a complex-shaped flow path called an after-mixer is formed between the casting hole and the cavity of the RIM mold, and the flow path inside the after-mixer is
Mixing and agitation of the RIM raw materials is assisted by colliding the RIM raw materials with each other.

Various shapes of this after-mixer have been proposed depending on the molded product (Special Public Interest Publication in 1988).
52776, etc.) However, basically, as shown in Fig. 2, there are several pairs of inflow ports 1 that communicate with the injection hole of the mold and a pair of branch inflow channels 2 that branch from this inflow port 1. A configuration is often adopted in which an inlet passage 3 is provided, and an outflow passage 4 is configured to communicate with the several pairs of inlet passages 3 and have one end connected to the mold cavity. According to the above, the after mixer having the above configuration shows the most excellent stirring effect.

(Problems to be solved by the invention) The conventional after-mixer has sufficient stirring effect for practical purposes, but there are still problems to be solved in terms of mold release properties of molded products. have

That is, the conventional after mixer divides the raw material injected from the inlet passage 1 into two streams by the branched inlet passage 2, and jets them out against each other through the mixing passage 3, causing the raw materials to collide with each other. It is.

Therefore, the mixing passage 3 is designed to have a small cross-sectional area for the purpose of increasing the flow rate of the raw material passing through this portion and causing strong collisions to improve the stirring efficiency.

However, in the structure of the conventional after-mixer, the raw material passing through the mixing passage remains in the same state as the raw material discharged from the casting machine, and the stirring state is completely insufficient.

On the other hand, when the RIM raw material is reacted and cured under insufficiently stirred conditions, it becomes weaker in strength and more adhesive than those under normal stirred conditions.

Furthermore, as described above, the inlet passage 3 is narrower than other parts.

Therefore, when the after-mixer portion is removed from the mold, the mixing passage 3 portion is often cut. This uncut intrusion path 3 must be scraped out with a spatula, stick, etc., but this work is extremely difficult because the part concerned is highly sticky.

Therefore, in 1986, the inventor proposed a method to discharge this after-mixer part without difficulty.
In No. 145056, we proposed a new technology. Although these proposals improve the old technology and have considerable effects, it is still difficult to say that the after-mixer portion can be demolded completely without difficulty.

Therefore, the present invention focused on the drawbacks of the conventional technology and created a mold that is easy to demold and has an excellent stirring effect.
We propose an after mixer for RIM molding.

(Means for Solving the Problems) The features of the present invention for achieving the above-mentioned objects include: an inlet portion communicating with the casting hole of the mold;
Several pairs of inflow passages were provided opposite to the pair of branched inflows branching from the inflow part, and an outflow passage was configured to communicate with the several pairs of inflow passages and to have one end connected to the mold cavity. The after-mixer for reaction injection molding has an inlet passage consisting of one or several curved passages between the injection hole of the mold and the inflow part.

In other words, the after mixer for RIM molding of the present invention is provided with a curved introduction part at the front stage of the after mixer of the conventional technology, and when raw materials are injected in RIM molding, some mixing of the raw materials is performed by the introduction part. .

Therefore, the raw material passing through the mixing path is a little more agitated than in the conventional case, and the reaction hardened raw material in the mixing path has enough strength to withstand the tensile force during demolding, and is also less sticky. It becomes less.

Therefore, when an operator pulls on the part during demolding, the mixing path is not cut and the entire after mixer is easily demolded.

(Example) Specific examples of the present invention will be further described below.

FIG. 1 is a front view of a RIM mold equipped with an after-mixer for reaction injection molding in a specific embodiment of the present invention.

In the figure, numeral 10 indicates a RIM mold. and,
Reference numeral 11 indicates an after mixer 11 for RIM molding in an embodiment of the present invention. The after mixer in this embodiment has the same structure as the prior art, with an introduction section (circle 13) provided upstream of the main stirring section (circle 12). Here, the main stirring section 12 has the same configuration as the conventional after mixer as described above, and includes an inflow section 15 communicating with the casting hole 14 of the mold 10,
It is provided opposite to a pair of branch inflow passages 16 branching from this inflow part, and its cross-sectional area is the same as that of the previous branch inflow passage 1.
The molding die 10 has three pairs of inlet passages 17 smaller than 6, and each inlet passage 17 has an outflow passage 19 which is opened oppositely and one end of which is connected to the cavity 18 of the mold 10. The introduction section 13 connects the casting hole 14 of the mold and the injection section of the main stirring section 12, and is composed of two curved channels.

To explain the shape of the introduction part 13 of this embodiment, it is divided into two strips from the vicinity of the casting hole 14 of the mold 10, and one end of the channel 20 is extended toward the outer circumferential direction of the mold, and from the corner 21 It bends downward, further contracts toward the center of the mold 10, bends outward again at the center of the mold 10, and its tip bends three-dimensionally toward the front in the drawing, forming the main stirring part 12 at the center of the mold 10. It is connected to the inflow section 15 of. On the other hand, the other flow path 21 passes through the previous flow path 20 and the path of the reversed strip, and the main stirring section 1
It is connected to the inflow section 15 of No. 3.

The above-mentioned shape of the introduction part is preferable because it allows the curved flow path to be arranged three-dimensionally and many curved parts can be provided in a short distance, but the essence of the present invention is to stick to this. It is also possible to have curved portions arranged in a flat strip instead of a straight strip.

Also, the introduction path may be one-threaded, but two
It is particularly preferable that the length is more than 100 mm, since this has the effect of causing the raw materials to collide with each other at the gathering part of the introduction part.

(Effects) The RIM molding after-mixer of the present invention has an introduction path consisting of a curved flow path in the previous stage of the conventionally shaped after-mixer, so that the raw material passes through the introduction section, and the curved section allows the raw material to flow in the flow direction. The stirring of the raw materials progresses as the Ru.

Therefore, the after mixer for RIM molding of the present invention has the effect of facilitating demolding during reaction curing.

Moreover, as a supplementary effect, it also has the effect of promoting mixing and stirring of raw materials.

[Brief explanation of the drawing]

FIG. 1 is a front view of a RIM mold equipped with an after-mixer for reaction injection molding according to a specific embodiment of the present invention, and FIG. 2 is a front view of a conventional after-mixer for reaction injection molding. 13... Inlet path, 15... Inflow path, 16... Branch inflow path, 17... Mixing path, 18... Cavity, 19... Outflow path for practical use.

Claims (1)

[Scope of utility model registration request] An inflow part that communicates with the casting hole of the mold, several pairs of mixing passages provided opposite to a pair of branched inflow passages that branch from this inflow part, and an inflow passage that communicates with the several pairs of mixing passages and has one end connected to the injection passage. In an after-mixer for reaction injection molding, which is provided with an outflow path configured to lead to a mold cavity, an inlet path consisting of one or several curved flow paths is provided between the injection hole of the mold and the inflow part. An after mixer for reaction injection molding featuring the following.