JPS61123508A - Injection molding machine - Google Patents

Abstract

PURPOSE:To make the amount of a material stagnation less, and to perform injection smoothly, by providing a backflow preventive mechanism to a shaft core section of a plunger for an injection cylinder, and mounting a material supply appratus to a side opening section in the plunger circumferential surface of the material passage. CONSTITUTION:The shaft core section of a plunger 30 for an injection cylinder is provided with a material passage 30c having a backflow preventive mechanism 36 adjacent to the discharge port on the nozzle side, and a material apparatus 33 is mounted to a material supply port 30d. While the properties of a plunger type injection molding machine are secured, the material supplied form the material supply apparatus can be injected in the order of the supply.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a plunger type injection molding machine suitable for molding materials such as bulk materials containing glass fibers.

[Conventional technology]

Injection molding machines are roughly divided into screw type and plunger type depending on the plasticization structure of the resin within the cylinder. Of these, the plunger type is made by mixing thermosetting resin, especially unsaturated polyester resin, with glass fiber, etc. Suitable for molding with materials.

That is, among these types of molding materials, those used in injection molding machines are generally made of BMC (Bulk Mou1d).
The mechanical properties of molded products made from this material are highly correlated with the state of the glass fibers in the molded product, and the fibers are long and bendable. Since the mechanical strength is the same as above when there is less, from this point of view the plunger type is used because the glass fibers are less likely to break and bend compared to the screw type.

The 31st problem is that within the general structure of the conventional one-lunger injection molding machine, the molding machine 1 has a stuffer 3 and a barrel 4 connected by an elbow 2, and the stuffer 3 has an inner hole. In this case, the granger 6 of the supply cylinder 5 is fitted so as to be able to reciprocate. Further, a granger 8 of the injection cylinder T is fitted into the inner hole of the barrel 4, and a stuffer 3 is fitted into the inner hole of the barrel 4.
The material supply port 9 is opened in the middle of the inner hole near the nozzle 10. 11 is a check pulp for preventing material backflow. With this configuration, when the material 12t is charged into the stuffer 3 and the plunger 6t of the supply cylinder 5 is advanced, the material 12 is supplied through the elbow 2 and into the barrel 4 from the material supply port 9. The check pulp 11 restricts backflow. Therefore, by moving the plunger 8t of the injection cylinder 7 forward, the O inside the barrel 4 is
The material 12t can be injected from the nozzle 10 into a sleeve metal chamber (not shown) and into the metal filler.

The fourth factor is a schematic configuration diagram showing another example of a conventional plunger-type injection molding machine, and those with the same reference numerals as in FIG. 3 have the same structure, so a description thereof will be omitted. In this example, the material supply port 11 from the stuffer 3
The difference from the example shown in FIG. 3 is that A is opened at the opposite end of the nozzle 10a of the barrel 4A. The material 12 is supplied into the barrel 4A by the advancement of the granger 6,
The fact that injection is performed by advancing the plunger 8 is the same as in the example shown in FIG.

[Problem that the invention seeks to solve]

However, in the conventional molding apparatus shown in FIG. 3, the material supply port 11 is provided close to the nozzle 10, so when the material 12 is metered and fed from there, the back pressure is applied by the injection cylinder 7. : It has the advantage of easy and stable metering, but on the other hand, the material 12 that enters the inner hole of the barrel 4 from the material supply port 11 first faces the plunger 8 side, and the material that enters later. 12 is nozzle 1
Friend material 1 will go to the 0 side and will enter first during injection.
Since the material 12 comes out later, there is a disadvantage that the material 12 tends to remain. In addition, the tight seal portion where the seal portion of the plunger 8 passes through the material supply port 9 during injection is likely to be damaged.

Furthermore, in the one shown in FIG. 4, the material supply port 11A
is provided near the glass/jar 8, and the material 12 is supplied by retracting the plunger 8t for each shot.The material 12 that enters first comes out first, but back pressure is applied. The measurement of the feed material 12 becomes unstable because the
Another drawback is that it tends to trap air.

[Means for solving problems]

In order to solve all of these problems, the present invention provides a material passage in the axial center of the first runner for the injection cylinder with a backflow prevention rock near the discharge port on the nozzle side. A material supply device was attached to the material supply port, which is the opening on the J side.

[Effect]

When the plunger of the material supply cylinder is advanced, the material is metered and supplied into the barrel of the injection cylinder through the material supply port, material passage, backflow prevention mechanism, and at this time, back pressure is applied by the separate pressure of the material supply cylinder. It will be done. When the plunger of the injection cylinder is advanced after metering, material is injected from the nozzle, and in this case, the material that enters the material passage first comes out first.

〔Example〕

FIG. 1 is a schematic vertical sectional view of an embodiment of an injection molding machine according to the present invention. In the figure, a flanged cylindrical barrel 22 having a nozzle 21 at its tip is arranged with the nozzle 21 facing the mold injection port 23, and is fixed to the four corners of the flanged portion with nuts 24. A fixed platen 26 is fixed to the other end of the tie bar 25 with a nut 27. On the fixed plate 26,
A cylinder body 29 of the injection cylinder 28 is fixed concentrically with the barrel 22 9, and a piston 3 of a plunger 30 having a flange 30 a f in the center is attached to the cylinder body 29 .
0b is fitted so that it can move forward and backward. This plunger 3
0 is slidably fitted with the tie bar 25 through holes at the four corners of the collar 30a, and the barrel 22 is fitted onto the shaft portion 30b.
It is slidably fitted into the inner hole 22a of. and,
The shaft portion 30b is configured to move forward and backward within the inner hole 22a to feed pressure oil to the head end side and the rod end side of the injection cylinder 28, respectively.

A material passage 30c with an open end toward the nozzle 21 is provided at the shaft core of the shaft part 30b of the plunger 30, and the other end of the material passage 30c is connected to the shaft part 30b.
A material supply port 30d is opened in the cylindrical surface of the tube.

Reference numeral 31 denotes a stuffer attached to the material supply port 30d, which is formed into a cylindrical shape with a material input port 31af, into which a plunger 32 is fitted so as to be freely retractable. Also, 33 is a supply cylinder provided in parallel with the stuffer 31, and its piston rod 34
The connection plate 35 is connected between the stuffer 31 and the plunger 32.
By moving the piston rod 34t to the head end side using hydraulic pressure, the plunger 32 moves forward and supplies the material introduced from the material input 031a to the inner hole of the stuffer 31 to the material passage 30c. It is composed of On the other hand, the shaft portion 30bK of the plunger 3G has a ball check pulp 36 as a backflow prevention mechanism.
It is provided near the open end of the material passage 30c. This ball check pulp 36 includes a ball 37t formed at the open end of the material passage 30c and seated on a plate-shaped valve seat, and is configured to prevent material from flowing backward from the barrel 2211 to the plunger 3G111. has been done.

Molding operation noise by the injection molding machine configured as above,
The explanation will be given by taking as an example the molding of bulk BMCK mixed with glass fibers. After the mold is clamped with a metal (not shown), pressure oil is fed into the head end side of the supply cylinder 33 to form the piston rod 34 and plunger 32 as shown in the figure. is raised until the head of the granger 32 is past the material input port 31a.Then, 8MC resin as a material is supplied into the stuffer 31 from the material input port 31a, and pressure is applied to the rod end side of the supply cylinder 33. When oil is supplied, the piston rod 34 and plunger 32 move down together to compress the resin.Although not shown, the stuffer 3
1 is equipped with an electric heater and a high-temperature heating device to heat the resin inside. The resin compressed by the descent of the plunger 32 is transferred from the material supply port 30d to the material passage 30c.
The ball 3γ of the ball check valve 36 is fully pressed, and the ball 3γ is fed into the inner hole 22a of the barrel 22. When the inside of the inner hole 22a is pressurized by pushing the resin,
Since the backflow of the resin is restricted by the ball 37, the plunger 30 is retracted. At this time, the injection cylinder 28
If a constant or controlled back pressure is applied to the plunger 30 by supplying pressure oil to the head end side of the plunger 30, the plunger 3
Since the 0 retracted position is restricted, resin is measured at this retracted position and the supply of resin from the stuffer 31 is stopped. When metering is completed, oil is sent to the head end side of the injection cylinder 28 to advance the plunger 30, and the resin in the barrel 22 is injected from the nozzle 21 through the injection port 23 into the mold.

As described above, in the injection molding of MC resin, the resin is introduced from the material input port 31a, and then the resin flows from inside the stuffer 31 to the material passage 30c, the backflow prevention mechanism 36L, and the inner hole 22.
a'r: and is injected from the nozzle 21. During this time, the resin is extruded without being kneaded as in the case of a screw type, so there are few breakages or bends of the long glass fibers.

Another of the present invention in the second case! l! This is a sectional view of a backflow prevention mechanism showing an embodiment. In this embodiment, the backflow prevention mechanism has a check ring 38 instead of the ball 37 in the previous embodiment.
It is made up of. That is, the material passage 30c of the plunger 30 is inserted into the inner hole 22a of the barrel 22 at will, and the material passage 30c of the plunger 30 is branched into a plurality of parts at the tip and opened at a tapered end surface 30e.
extends like a rod from the tapered end surface 30e of C toward the nozzle 21, and has a conical cap 30f at the threaded end.
are screwed together. Check ring 38 is plunger 3
It is fitted into the rod-shaped portion 30g between the tapered end surface 30e of 0 and the shaft 3Qf so as to be movable in the axial direction,
It has a tapered surface 38a continuous to the cap 30f, a dish-shaped portion 38b opening toward the tapered end surface 30e, and a solid communication hole 38c. The plunger 30 and the check ring 38 are respectively formed with closing surfaces 30h and 38d that face each other.
When the pressure in the barrel inner hole 229111 is high, the closing surfaces 30h and 38d are closed to prevent the resin from flowing back. By doing this, it is possible to prevent backflow of the material when measuring the material as in the previous embodiment. It can be prevented.

In this embodiment, it goes without saying that the side tone molding machine for molding 8MC resin by the injection molding machine according to the present invention can also be used for molding various other resins.

〔Effect of the invention〕

=9 As is clear from the above description, according to the present invention, in a plunger type injection molding machine, a material passage provided with a backflow prevention mechanism near the discharge port on the nozzle side is provided in the axial center of the plunger for the injection cylinder. By attaching the material supply device to the material supply port that is located at the opening on the peripheral surface of the glass/jar in this material passage, it is possible to reduce the chance of cutting or bending of fibers when molding resin containing glass fibers, etc. Not only can it maintain the characteristics of a plunger type injection molding machine, but the material supplied from the material supply device f1t is injected in the order of supply without being switched back and forth, so there is less material retention and injection is faster. In addition to being extremely smooth, it is possible to apply back pressure while regulating the backflow of material during material measurement, making material measurement extremely stable and reducing air entrapment in the barrel. Since the material does not pass through the material supply port when moving the plunger back and forth, the seal part of the plunger will not be damaged◇

[Brief explanation of drawings]

Figures 1 and 2 show an injection molding machine according to the present invention! ! !
FIG. 1 is a schematic vertical cross-sectional view thereof, FIG. 2 is a cross-sectional view of a reversal prevention and mechanism showing another feature of the present invention, and FIGS. 3 and 4 are respectively a conventional plunger. A schematic vertical cross-sectional view of a mold injection molding machine. 21φ...nozzle, 22...φ barrel, 22a ・
...Inner hole, 28, excellent...Injection cylinder, 30...
Plunger, 30c...Material passage, 30d.
...Material supply port, 31...Stuffer, 36...
...ball check pulp, 37-fist ball 33
＊ ＊ Abbreviated check ring. Patent Appearance Ube Industries Co., Ltd.

Claims (1)

[Claims] A material passage having a material supply port opening toward the peripheral surface of the plunger and a discharge port opening toward the nozzle side is provided in the axial center of the injection cylinder plunger, and a material supply device is attached to the material supply port, and An injection molding machine characterized in that a backflow prevention mechanism is provided near the discharge port of the plunger.