JPH0318163Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention involves colliding and mixing multiple liquid plastic raw materials (hereinafter referred to as liquid raw materials) at high pressure, and feeding this into a mold for reaction. This invention relates to a mixing head of a reaction injection molding machine for molding plastic products.

``Prior Art and Its Problems'' As a conventional mixing head of this type, for example, one having the configuration shown in FIG. 6 is known. This mixing head includes a mixing chamber 2 having a discharge port 1, and injection nozzles 3, 3 for injecting liquid raw materials a and b into this mixing chamber 2.
and a spool 4 that controls the start and stop of liquid material injection from the injection nozzles 3, 3. The spool 4 slides tightly within the mixing chamber 2, and in this type of mixing head, the liquid raw material remaining within the mixing chamber 2 is removed by the spool 4.

For this reason, with this mixing head, accidents such as the spool 4 becoming inoperable due to the adhesion force based on the liquid raw material that has entered between the wall surface of the mixing chamber 2 and the spool 4, and Accidents of damage to the spool 4 are likely to occur, and in order to prevent these accidents, the spool 4 and the mixing chamber 2 must be made short. As a result, this mixing head had the problem of not being able to mix the liquid raw materials sufficiently.

To address these problems, mixing heads shown in FIGS. 7-9 have been proposed.

These mixing heads are designed to facilitate mixing of liquid raw materials by forming the mixing chamber 2 in a curved manner.

However, for such a mixing head,
Since the two spools 4 and 5 are operated to remove the liquid raw materials remaining in the bent mixing chamber 4, accidents such as the spools 4 and 5 colliding or being pinched easily occur, and the mixing head The problem was that the configuration of the head became complicated and the head became large and expensive.

``Means for Solving the Problems'' Therefore, the mixing head of this invention is equipped with an air injection unit that injects compressed gas into the mixing chamber, and uses the compressed air injected from the unit to discharge the liquid raw materials remaining in the mixing chamber. This is an attempt to solve the above-mentioned problems.

"Operation" The liquid raw material remaining in the mixing chamber is discharged from the discharge port by air jetted from the air jetting unit.

Embodiment FIGS. 1 and 2 are diagrams showing an embodiment of the mixing head of this invention. In these figures, reference numeral 10 denotes a mixing chamber formed at the bottom of a spool hole C provided in the main body B of the mixing head H. The lower part of this mixing chamber 10 is connected in a straight line to an extension mixing chamber 10b formed inside by a pipe 10a detachably attached to the main body B of the mixing head H, and the lower end thereof is connected in a straight line. It serves as a discharge port 11 for injecting liquid raw material into a mold (not shown). In addition, injection nozzles 12, 12 for injecting liquid raw materials into the mixing chamber 10 are connected to and provided in the main body B above the mixing chamber 10. Above the injection nozzles 12, 12, circulation channels 13, 13 are further provided in the main body B, communicating with the spool hole C.

A spool 14 is inserted into the spool hole C in the upper part of the mixing chamber 10 to which the injection nozzles 12, 12 and the circulation channels 13, 13 are connected, so as to be freely slidable in the axial direction. This spool 14 constitutes a control valve A that controls whether to stop or start the injection of raw materials from the injection nozzles 12, 12 into the mixing chamber 10, and the mixing chamber 10 is controlled by a hydraulic cylinder (not shown) or the like.
It is possible to move forward and backward between the lower end (advance position) and a position retracted above the injection nozzles 12, 12 (retreat position). Circulating grooves 15, 15 are formed on the outer periphery of this spool 14. and the first
As shown in the figure, when the spool 14 is in the retracted position, the injection nozzles 12, 12 are opened toward the mixing chamber 10. Also, as shown in Figure 2,
When the spool 14 is in the forward position, the injection nozzle 12 and the circulation flow path 13 are communicated through the circulation groove 15, and each liquid raw material is circulated through each flow path to the raw material tank without being mixed. This control valve A controls the start and stop of injection of liquid raw materials into the mixing chamber 10 in the manner described above. At this time, the unmixed liquid raw materials interposed in the circulation grooves 15, 15 also act as lubricating fluid between the spool 14 and the spool hole C, so in the mixing head of this example, the forward and backward movement of the spool 14 is is carried out smoothly and easily.

An air jetting unit 16 is provided at the base of the pipe 10a, which is located slightly closer to the discharge port 11 than the forward end of the spool 4. This air injection unit 16 injects compressed gas into the extended mixing chamber 10b to discharge the raw material remaining in the extended mixing chamber 10b. The air blowing unit 16 in this example is fixed to a pipe 10a forming the lower part of the mixing chamber 10 (extended mixing chamber 10b),
An air pipe 16 communicating with the extended mixing chamber 10b
an air conduit 16b that is connected to the intermediate portion of the air pipe 16a and supplies compressed air into the air pipe 16a; The air injection control spool 16c includes an air injection control spool 16c that opens and closes an opening to the air injection control spool 16c, and a drive cylinder 16d that is supported by an air pipe 16a and drives the air injection control spool 16c. The air injection control spool 16c of the air injection unit 16 is configured such that its tip forms a part of the peripheral surface of the mixing chamber 10 when it is advanced. In addition, the drive cylinder 16d includes
Air cylinders and hydraulic cylinders are used. The air blowing unit 16 is controlled by a limit switch, a timer, etc. (not shown). The air conduit 16b of the air injection unit 16 has a solenoid valve that opens and closes the conduit 16b as necessary to prevent air from leaking between the air pipe 16a and the air injection control spool 16c. etc. will be established.

Next, the operation of this mixing nozzle will be explained.

First, when supplying mixed raw materials to a mold (not shown), as shown in FIG.
4 is moved backward to open the injection nozzles 12, 12. The liquid raw materials injected from the injection nozzles 12, 12 are collided and mixed in the mixing chamber 10, and then further mixed in the extended mixing chamber 10b until the liquid materials reach the discharge port 1.
Injected into the mold from step 1.

When a predetermined amount of injection is completed, the spool 14 is advanced to open the injection nozzle 1, as shown in FIG.
2 and 12 are closed, and the injection of liquid raw material is stopped. Then, the air injection control spool 16c of the air injection unit 16 is retracted after a delay of about 1 to 2 seconds due to the liquid raw material injection stop signal or the action of a timer. When the air injection control spool 16c retreats, the air pipe 16
The inside of the chamber a is communicated with the air conduit 16b, and compressed air is injected from the air pipe 16a into the extended mixing chamber 10b for a predetermined period of time set by a timer. This injected compressed air flows at high speed within the extended mixing chamber 10b toward the discharge port 11, and blows away the liquid raw material remaining on the wall surface of the extended mixing chamber 10b. As a result, the liquid raw material remaining in the extended mixing chamber 10b is removed.

In the mixing head of the present invention, since the liquid raw material remaining in the mixing chamber (extended mixing chamber 10b) can be removed by compressed air, the entire mixing chamber (mixing chamber 10b) can be removed by compressed air.
0 and the extended mixing chamber 10b) with the spool 14, and since the spool 14 can only be cleaned up to the mixing chamber 10, the extended mixing chamber 10b can be used to promote mixing without considering strength or operability. Can be formed long enough.
Therefore, according to the present invention, the mixing chamber 10 can be made longer without increasing the cleaning length of the spool 14, so that the liquid raw materials can be mixed sufficiently.

In addition, in the mixing head of this embodiment, the portion (pipe 10
a) is formed to be detachable from the main body B of the mixing head H, so even if an accident occurs where the mixing chamber (extended mixing chamber 10b) is clogged due to incomplete removal of residual liquid by compressed air, the pipe 10a This has the advantage that post-accident treatment is easy and recovery can be done in a short time.

In addition, in the mixing head of this embodiment, if the pipe 10a is removed, the mixing chamber 10 can be moved to the spool 1.
4 is the only part from which residual liquid is removed, so there is an advantage that it can also be used as a mixing head for supplying raw materials to the closed mold.

3 and 4 show other embodiments, and the above embodiment is different from the mixing chamber (extended mixing chamber 10b).
The only difference is the shape.

In the mixing head of FIG. 3, the pipe 1 forming the extended mixing chamber 10b' forming the lower part of the mixing chamber 10
A meandering line at 0a is used. Further, annular convex portions 17 for partially constricting the mixing chamber 10 are provided at a plurality of locations on the inner surface thereof.

In the mixing head of this example, the mixing of the liquid raw materials is promoted while passing through the meandering extended mixing chamber 10b', and the mixing of the liquid raw materials is further promoted in the narrowed portions of the convex portions 17. , it has the advantage of being able to mix liquid raw materials sufficiently.

In the mixing head of FIG.
Pipe 10 that is branched into 18 and then rejoined
formed by a″.

In the mixing head of this example, channels 18, 1
Since the liquid raw materials are again collided and mixed at the confluence section 8, there is an advantage that the liquid raw materials can be sufficiently mixed.

The mixing head shown in FIG. 5 is different from the above embodiments in the structure of the air blowing unit 16.

In the mixing head H' of this example, the air jetting unit 16 has an air jetting passage 16f provided along the central axis of the spool 14a, and a mixing head for supplying compressed air to the air jetting passage 16f. The air supply passage 16g is formed in the main body B' of the head H'. Air jet passage 16
One end of f is formed to have a small diameter, and the spool 14
It is opened at the center of the lower end surface of a. Further, the other end of the air jet passage 16f is formed with a large diameter,
It is opened in the circumferential surface of the spool 14a. The lower end surface of the spool 14a is formed in a tapered shape that gradually expands downward and outward. Furthermore, a guide member 16h that guides the injected compressed air radially outward is attached below the opening at one end of the air ejection passage 16f. Above air supply path 16g
When the spool 14a comes to the forward position, it communicates with the other end opening of the air jet passage 16f, and the spool 1
When the spool 14a is in the retracted position, the spool 14a
It is provided so as to open at a position where it is closed by the circumferential surface of.

According to this mixing head H', when the spool 14a is advanced to close the injection nozzles 12, 12 after the injection of a predetermined amount of liquid raw material is finished, the air injection passage 16f and the air supply passage 16g are simultaneously communicated with each other. , compressed air is injected into the mixing chamber 10. The injected compressed air is guided to the circumferential surface of the mixing chamber 10 by the guide member 16h, and removes residual liquid raw material adhering to the circumferential surface of the extended mixing chamber 10b inside the pipe 10a forming the lower part of the mixing chamber 10. It is blown toward the discharge port 11.

Even with this mixing head, the same effects as in the first embodiment can be obtained.

In addition, in the above embodiment, the air blowing unit 1
Although compressed air is ejected from 6, gases other than air may be used as necessary.

Further, in the above embodiment, the mixing head is provided with removably attached pipes 10a to 10a having extension mixing chambers 10b to 10b extending the mixing chamber 10. , H′.

Further, the mixing head of the present invention has pipes 10a to 10a extending the mixing chamber 2 to a ready-made mixing head as shown in the prior art in FIGS. 6 to 9.
is detachably attached to the pipes 10a to 1.
Of course, it can also be constructed by providing an air jet unit 16 at 0a.

``Effect of the invention'' As explained above, the mixing head of the reaction injection molding machine of the invention injects compressed gas from the air injection unit into the mixing chamber to discharge the raw materials remaining in the mixing chamber. There is no need to spool off residual liquid material over the entire length of the mixing chamber. Therefore, according to the mixing head of the present invention, since the spool can be formed short, there is no possibility of damage to the spool. Further, since it is not necessary to use two spools to promote mixing as in the conventional device, collision accidents of spools can be eliminated and the structure of the head can be simplified.

Moreover, in the mixing head of the present invention, the liquid raw materials remaining in the mixing chamber are removed by compressed gas, so the length of the mixing chamber can be extended or the mixing chamber can be arbitrarily bent to mix the liquid raw materials. It becomes possible to promote Therefore, according to the present invention, it is possible to provide a mixing head that is small in size and capable of highly mixing liquid raw materials.

[Brief explanation of the drawing]

Figures 1 and 2 are views showing essential parts of an embodiment of the mixing head of the present invention, in which Figure 1 is a sectional view showing the spool in a retracted state, and Figure 2 is a cross-sectional view showing the spool in a retracted state. 3 to 5 are sectional views showing main parts of other embodiments of the mixing head of the present invention, and Figs. 6 to 9 show main parts of a conventional mixing head, respectively. FIG. 10... Mixing chamber, 11... Discharge port, 12... Injection nozzle, 16... Air injection unit, A...
control valve.

Claims (1)

[Scope of utility model registration request] A mixing chamber having a discharge port, an injection nozzle that injects liquid raw material into this mixing chamber, a control valve that controls starting and stopping of raw material injection from this injection nozzle, and a stop of raw material injection from the injection nozzle to the mixing chamber. After being
A mixing head for a reaction injection molding machine comprising an air injection unit that injects compressed gas into a mixing chamber to discharge raw materials remaining in the mixing chamber.