JPH0530896Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mixing head for reaction injection molding, and in particular, discharges or stops a reactive liquid such as urethane or epoxy by moving a piston rod in a mixing chamber. This invention relates to novel improvements to enable independent performance.

[Prior Art] Generally speaking, in reaction injection molding in which a plurality of chemically active liquids are injected into a mold under high pressure and high speed to react and harden, the mixing head body is used to perform collisional mixing and mixing of the liquids. It has the function of pushing out the mixed liquid inside the mixing chamber.

As a typical configuration of such a conventional mixing head, although no literature is disclosed, the generally used configuration shown in FIGS. 11 and 12 can be mentioned.

11 and 12 is the mixing head body 1, which has a plurality of inlet passages 2 and 2' and outlet passages 3 and 3' axially connected to each other. A mixing chamber 4 is provided at different positions and is formed at the axial center of the mixing head main body 1.

The mixing chamber 4, each of the inlet passages 2 and 2' and the outlet passages 3 and 3' are communicated via inlet nozzles 2a and 2a' and outlet nozzles 3a and 3a', and the mixing chamber 4
A piston rod 5 having a plurality of circulation grooves 5a and 5a' is provided therein so as to be freely movable in the axial direction.

A conventional mixing head for reaction injection molding is constructed as described above, and its operation will be explained below.

The two types of reactive liquids are mixed by the energy of the flow of the liquid entering from the respective inlet passages 2 and 2' of the mixing head body 1 and being discharged from the respective inlet nozzles 2a and 2a' formed toward the center. They collide within the mixing chamber 4 and are instantaneously mixed.

Further, the discharge of these liquids from the respective inlet nozzles 2a and 2a' or their stopping operations are performed by moving the piston rod 5 provided inside the mixing head main body 1 in the axial direction, as shown in FIG. , the tip 5 of the piston rod 5
When the liquid a reaches the end face 1a of the mixing head body 1, each inlet nozzle 2a and 2a' is closed by the outer peripheral surface of the piston rod 5, and the discharge of liquid into the mixing chamber 4 is stopped.

The liquid whose flow path to the mixing chamber 4 has been cut off is guided to the outlet paths 3 and 3' via the circulation grooves 5a and 5a', and returns to the tank (not shown).

Therefore, in the situation of FIG. 11, in which each inlet nozzle 2a and 2a' is not blocked, liquid is injected into the mold (not shown) through the mixing chamber 4.

Also, the piston rod 5 is shown in FIGS. 11 to 12.
When moving to the state shown in the figure, the mixed liquid remaining in the mixing chamber 4 is injected into the mold by the volume of movement. This injection operation is similar to the pressure holding process in injection molding, in which the liquid in the mold undergoes a curing reaction under pressure, and the well-mixed liquid close to the product area is replenished into the product area. fulfills its function.

[Problems to be solved by the invention] Since the conventional mixing head for reaction injection molding was constructed as described above, it had the following problems.

In other words, immediately after the inlet nozzle is blocked by the piston rod and the discharge of liquid into the mixing chamber is stopped, the mixing and blending ratio of the liquid in the mixing chamber is poor, so the movement of the piston rod does not stop the liquid. In a conventional mixing head, which requires simultaneous mixing, this mixed and poorly mixed liquid would enter the product section of the mold, causing defects in the molded product.

The present invention was developed to solve the above-mentioned problems, and in particular, it is possible to discharge or stop reactive liquids such as urethane and epoxy independently of the movement of the piston rod within the mixing chamber. It is an object of the present invention to provide a mixing head for reaction injection molding that can be used in reaction injection molding.

[Means for Solving the Problems] The mixing head for reaction injection molding according to the present invention collides and mixes two or more reactive liquids in the mixing chamber of the mixing head body under high pressure and high speed. A cylindrical liner rotatably provided between the mixing head main body and the piston rod; This configuration includes a nozzle provided in the radial direction of the liner, and an inlet provided in the mixing head body and capable of communicating with the nozzle.

[Function] In the mixing head for reaction injection molding according to the present invention, a liner having a nozzle is rotatably provided between the mixing head main body and the piston rod, so that the reactive liquid can be discharged into the mixing chamber or stopped. This can be separated from the function of the piston rod, which pushes out the liquid remaining in the mixing chamber toward the mold and cleans the inside of the mixing chamber.

Therefore, the operation of discharging and stopping the liquid into the mixing chamber can be performed only by rotating one liner, and since the operation of this liner is only a rotational movement, it can be performed instantly, easily and smoothly. The liquid can be discharged or stopped at the same time without any time lag.

Therefore, the piston rod can be moved freely regardless of the stoppage of liquid discharge, and after the liquid discharge into the mixing chamber has stopped, t
After seconds the piston rod can be moved independently. Therefore, molded products subjected to reaction injection molding using the mixing head according to the present invention are free from voids, sink marks, warpage, etc., and products with good appearance can be obtained.

[Embodiments] Hereinafter, preferred embodiments of the mixing head for reaction injection molding according to the present invention will be described in detail with reference to the drawings.

Note that the same reference numerals are used to describe the same or equivalent parts as in the conventional example.

1 to 10 are for showing a mixing head for reaction injection molding according to the present invention. First, a first embodiment shown in FIGS. 1 to 8 will be described.

In the mixing head main body designated by reference numeral 1 in the figure, a pair of inlet passages 2 and 2' are arranged opposite to each other for injecting two types of liquids supplied from the outside. ', outlet passages 3 and 3' are formed via bypass pipes 11 and 11' having on-off valves 10 and 10', and inside each of the inlet passages 2 and 2', the mixing An injection port 2 communicating with a liner receiving hole 13 formed in the center of the head body 1
A and 2A' are formed.

Inside the liner receiving hole 13, the overall shape is approximately cylindrical, and the injection ports 2A and 2 are provided.
Nozzles 2a and 2 formed to correspond to A'
A liner 14 having a diameter a' is rotatably provided, and a hole 14A formed in the center of the liner 14 in the axial direction and the mixing head main body 1
The mixing chamber 4 formed in the center of the mixing chamber 4 is formed continuously and concentrically.

Inside the hole 14A and the mixing chamber 4, there is a frame 1 attached to the mixing head main body 1.
A piston rod 5 is slidably provided in a cylinder 17 attached via a piston 6, and the cylinder 17 has a first hydraulic port 18 and a second hydraulic port for sliding the piston rod 5. 19 is formed.

Therefore, the piston rod 5 is configured to be able to slide by selectively supplying pressure oil from each of these hydraulic ports 18 and 19.

At the rear end of the liner 14, a pair of arms 14a and 14b extend vertically as shown in FIG. 3, and as shown in FIGS. It is attached to the rear end of the mixing head body 1 by four restraining bodies 20 attached to the mixing head body 1.

A first hydraulic cylinder 21 consisting of a pair of hydraulic cylinders 21a and 21b is provided at an upper position at the rear end of the mixing head 1, and a first piston rod is movably provided between each of these hydraulic cylinders 21a and 21b. A pair of flanges 23 are provided on the first piston rod 22 at intervals, and a notch 14 of the arm 14a is provided on the first piston rod 22 between the flanges 23.
aA is engaged.

A second hydraulic cylinder 24 consisting of a pair of hydraulic cylinders 24a and 24b is provided at a lower position at the rear end of the mixing head 1, and a second piston rod is movably provided between each of these hydraulic cylinders 24a and 24b. A pair of flanges 26 are provided on the second piston rod 25 at a distance from each other, and a notch 14 of the arm 14b is provided on the second piston rod 25 between the flanges 26.
bA is engaged.

Therefore, by selectively operating each of the hydraulic cylinders 21a, 21b and 24a, 24b, each arm 14a and 14b is rotated by each collar 23 and 26, as shown in FIG. The liner 14 can be rotated through a predetermined angle.

In the case of the second embodiment shown in FIGS. 9 and 10, a fixing groove 30 is provided in the liner receiving hole 13 of the mixing head main body 1 instead of the above-mentioned on-off valves 10 and 10' and bypasses 11 and 11'. and 30', and rotary grooves 31 and 31' are formed on the outer periphery of the liner 14, and these rotary grooves 31 and 31' communicate with the inlets 2A and 2A' and the outlet passages 3 and 3'. ing. Further, one end of the fixed grooves 30 and 30' communicates with the outlet passages 3 and 3' and partially overlaps with the rotating grooves 31 and 31', and the end thereof is connected to the inlets 2A and 2A'. are configured so that they do not communicate.

The mixing head for reaction injection molding according to the present invention is constructed as described above, and its operation will be explained below.

First, the reactive liquids a and b are separately supplied to the inlet passages 2 and 2' of the mixing head body 1 at high pressure and high speed through high-pressure liquid supply sections (not shown).

In addition, each of the above-mentioned reaction solutions a and b shall be hereinafter abbreviated as "liquid".

These liquids a and b enter each inlet passage 2 and 2', each inlet 2A and 2A' and liner 14.
The mixture passes through the nozzles 2a and 2a', and is impingement-mixed in the mixing chamber 4 in the mixing head body 1, and then introduced into a mold (not shown).

In the above case, the on-off valves 10 and 10' provided on the flow paths of the bypasses 11 and 11' in the mixing head body 1 are in the closed state, and the liquids a and b that have entered the mixing head body 1 are in a closed state. The entire amount is sent into the mixing chamber 4.

After the product part, gate part, etc. (not shown) in the mold are filled with the mixture of liquids a and b, each hydraulic cylinder 21a, 21b and 24 in FIG.
a, 24b are operated, and as the piston rods 22 and 25 move, the arms 14a and 14b of the liner 14 are rotated to a predetermined angle via the flanges 23 and 26, as shown in FIG.

At this time, the flow path state of liquids a and b changes as shown in FIG. 4 to FIG. 7, and each injection port 2A and 2
A' and each nozzle 2a and 2a' become out of communication, and almost simultaneously with this operation, bypasses 11 and 11' in the mixing head main body 1 shown in FIG.
Open the on-off valves 10 and 10' installed in
Liquids a and b supplied from each inlet channel 2 and 2' flow via bypasses 11 and 11', respectively, to respective outlet channels 3 and 3', and a tank (not shown)
Return to

Thereafter, the piston rod 5 shown in FIG. 8 pushes the liquid in the mixing chamber 4 to the outside of the mixing head body 1 in the direction of the arrow, but the movement of the piston rod 5 is caused by the rotation of the liner 14 and This is performed after a predetermined time t seconds has elapsed from the opening of each on-off valve 10 and 10'. That is, when the discharge of liquids a and b from each nozzle 2a and 2a' of the liner 14 shown in FIG. 7 has stopped, the liquid in the mixing chamber 4 shown in FIG. 8 is due to poor mixing or blending ratio. For this reason, it is necessary to increase the viscosity of this part to a certain extent so as not to supply it to the product part in the mold. For this purpose, the movement time of the piston rod 5 is set to be delayed by t seconds depending on the reactivity of each liquid a and b.

The aforementioned delay time t seconds may be 1 second or less in the case of a highly reactive liquid, and may be 3 seconds or more in the case of a slow reaction.

The movement of the piston rod 5 can be adjusted at any speed in terms of stroke, and can also be stopped in the middle of the stroke. This movement of the piston rod 5 is a function of the pressure holding process in injection molding, that is, the liquid in the mold is hardened under pressure, and the well-mixed liquid close to the product area is replenished into the product area. It also has the function of It also has the function of cleaning the inside of the mixing chamber 4.

After the piston rod 5 moves to the end face of the mixing head main body 1, the liquid injected into the mold hardens after a certain period of time, and after hardening, the mold is opened and the product part is taken out, and each part of the mold is cleaned. I do. After cleaning the mold, the mold is closed again in preparation for the next molding.

In addition, in the embodiment shown in FIGS. 1 to 8 described above, each bypass 11 and 11' and each on-off valve 10
and 10' have been described, the means for guiding the liquid to the outlet paths 3 and 3' is not limited to this, and for example, as shown in FIGS. 9 and 10. As shown in FIG. ' can flow into the respective outlet passages 3 and 3'.

The aforementioned rotating grooves 31 and 31' are offset in the circumferential direction from the positions of the nozzles 2a and 2a' of the liner 14, as shown in FIG. 30' is
Each inlet passage 2 and 2' and each inlet 2A and 2
A' and the respective outlet passages 3 and 3' in substantially the same position in the circumferential direction.

Therefore, the state before rotating the liner 14,
That is, even when the liquid is discharged into the mixing chamber 4, the positions of the nozzles 2a and 2a' and the rotation grooves 31 and 31' are shifted from each other, and the passages to the outlet passages 3 and 3' are blocked. Therefore, introduction of the liquid from each inlet 2A and 2A' into each outlet path 3 and 3' can be prevented.

Note that the liquid is transferred from each inlet path 2 and 2' to each outlet path 3.
and 3', the configuration of each bypass 11 and 11' and each on-off valve 10 and 10' in FIG. 1, and each fixed groove 30 and 3 in FIG.
0' and the configurations of the rotation grooves 31 and 31' are shown, but these configurations may be shared, or only one of them may be used. Moreover, structures other than these structures can also be used.

Furthermore, although the configuration shown in FIG. 3 has been described as a means for rotating the liner 14 by a predetermined angle, this rotation means is not limited to this, and includes, for example, a rack and pinion mechanism, a worm wheel mechanism, an electric motor, hydraulic pressure, and air pressure. In addition to the above cylinder, any means that satisfies this mechanism can be used to obtain the same effect.

Further, the means for attaching the liner 14 to the mixing head main body 1 is not limited to the suppressor 20 shown in FIG. 5, and other structures such as a leaf spring may also be used.

Furthermore, as shown in FIG. 4, the configuration has been described in which there are two locations for discharging the liquid into the mixing chamber 4, but the number can be increased depending on the type of liquid used. In this case, the number of flow paths from the inlet path to the outlet path can be increased according to the number of liquids.

Next, an actual example using the mixing head of the present invention will be described. Polyol was used as liquid a, and isocyanate was used as liquid b. The liquid temperature was 29℃ in both cases, and the injection pressure was 60 to 150Kg/ ^cm2.
The injection rate is 90g/sec for polyol,
The amount of isocyanate was 28 g/sec. Furthermore, the mold temperature was 65°C, and the curing time after liquid injection was 100 seconds. The time for injecting the liquid into the mixing chamber 4 and mixing it by collision was set to 6 seconds. After this time has elapsed, the liner 14 is rotated by a certain angle, and at the same time the on-off valves 10, 10' which have been closed are opened. The waiting time t from when the piston rod 5 starts moving is 0sec, 1sec, 2sec, 3sec. The molded product is a flat plate with a width of 22 cm, a length of 55 cm, and a thickness of 0.5 cm, and the gate of the mold is a fan gate. Under these molding conditions, reaction injection molding of polyol and isocyanate was performed, and the appearance of the molded products was compared. First, when the waiting time t=0 sec, voids, sink marks, and warpage occurred on the gate side and the peripheral area of the product part, and the surface surface was rough. This is due to a part of the liquid that was improperly mixed or blended into the product part in the mold. Next, when t=1 sec, the voids, sink marks, and warpage that had occurred in the product were reduced, but they were not completely eliminated, and the molded product was still defective. This is because the viscosity of the mixed liquid in the mixing chamber 4 is still low (several poise), and although it is less than when t = 0 sec, some of this mixed liquid has penetrated into the product part in the mold. It is. Then t=
In the case of 2 seconds, voids, sink marks, warpage, etc. that had occurred on the product part were almost completely eliminated, and the surface texture was also good. At this time, the viscosity of the mixed liquid in the mixing chamber 4 was several tens to several hundreds of poise, and when it was pushed out by the piston rod 5, it exhibited a plug-like flow. As a result, the mixed liquid remaining in the mixing chamber 4 entered the mold but did not reach the product section, and the product section was able to have a good appearance. Next, when t=3sec,
Although the product part was in good condition, the mold releasability after molding was completed was poor, and a part of the product part was damaged during mold release.
From the above molding results, it was found that the optimum waiting time t was 2 seconds. This waiting time t varies depending on the type of reactive liquid used in reaction injection molding.
In the case of a highly reactive liquid, t=1 sec or less, and in the case of a slow reaction, t may be 3 sec or more. In these molding operations, the liner 14 was operated only by rotating through a certain angle, so the operation was simple, instantaneous, and smooth. In this example, a molding example using polyol and isocyanate as reactive liquids a and b was shown, but other reactive liquids such as nylon, unsaturated polyester, epoxy,
The present invention is also effective in reaction injection molding of dicyclopentadiene and the like.

[Effects of the invention] Since the mixing head for reaction injection molding according to the invention is constructed as described above, the following effects can be obtained.

In other words, the function of the piston rod is to separate the function of discharging or stopping the reactive liquid into the mixing chamber from the function of the piston rod, which pushes out the liquid remaining in the mixing chamber toward the mold and cleans the inside of the mixing chamber. An effective means is to use a liner between the main body and the piston rod that can switch between discharging and stopping the liquid.

Therefore, discharging and stopping the liquid into the mixing chamber can be performed only by rotating one liner. Since this liner operates only by rotational motion, it can be operated instantly, easily, and smoothly, and the liquid can be discharged and stopped at the same time without any time lag. As a result, the movement of the piston rod can be freely controlled, so that the piston rod can be independently moved t seconds after the discharge of liquid into the mixing chamber has stopped. As a result, molded products made by reaction injection molding using the mixing head of the present invention have almost no voids, sink marks, or warpage.
A product with good appearance can be obtained.

[Brief explanation of the drawing]

Figures 1 to 10 are for showing a mixing head for reaction injection molding according to the present invention.
Fig. 1 is a sectional view showing the overall configuration, Fig. 2 is a side view seen from direction A in Fig. 1, and Fig. 3 is a B--
4 is a sectional view taken along line C-C in FIG. 1, FIG. 5 is a sectional view taken along line D-D in FIG. 3, and FIG. 6 shows the liner in FIG. State diagram of the mixing head main body when rotated, No. 7
The figure is a cross-sectional view taken along line E-E in Figure 8, Figure 8 is a cross-sectional view of the mixing head body when the liner in Figure 3 is rotated by a predetermined angle, and Figure 9 is a cross-sectional view of the mixing head body when grooves are formed in the body and liner. Cross section of mixing head, 1st
0 is a sectional view taken along the line FF in FIG. 9, and FIGS. 11 and 12 are sectional views showing the conventional structure. 1 is the mixing head body, 2 and 2' are the inlet passages,
2a, 2a' are nozzles, 3, 3' are outlet passages, 4 is a mixing chamber, 5 is a piston rod, 10,
10' is an on-off valve, 14 is a liner, 30, 30' are fixed grooves, and 31, 31' are rotating grooves.

Claims (1)

[Claims for Utility Model Registration] (1) Two or more reactive liquids are collided and mixed in the mixing chamber 4 of the mixing head body 1 under high pressure and high speed, and then injected into the mold. In a mixing head for reaction injection molding in which the liquid in the mixing chamber 4 is pushed out and cleaned by a piston rod 5, a cylindrical liner is rotatably provided between the mixing head main body 1 and the piston rod 5. 14, nozzles 2a, 2a' provided in the radial direction of the liner 14, and inlet passages 2, 2' provided in the mixing head main body 1 and capable of communicating with the nozzles 2a, 2a'; By rotating 14, the inlet passage 2,
2' and the mixing chamber 4. (2) It has outlet passages 3, 3' provided in the mixing head main body 1 and connected to the inlet passages 2, 2' via on-off valves 10, 10';
2. A mixing head for reaction injection molding according to claim 1, wherein the on-off valves 10, 10' are opened when the connection between the mixing chamber 2' and the mixing chamber 4 is disconnected. (3) Outlet passages 3, 3' provided in the mixing head main body 1, fixing grooves 30, 30' formed in communication with the outlet passages 3, 3', and fixing grooves 30, 30' provided in the liner 14, It has grooves 30, 30' and rotating grooves 31, 31' formed so as to be able to communicate with the inlet passages 2, 2', and when the connection between the inlet passages 2, 2' and the mixing chamber 4 is disconnected. 2. The apparatus according to claim 1, wherein the inlet passages 2, 2' and the outlet passages 3, 3' are connected to each other via the fixed grooves 30, 30' and the rotating grooves 31, 31'. Mixing head for reaction injection molding.