JPS6364711A - Injection molding machine - Google Patents

Abstract

PURPOSE:To prevent deterioration in impact strength ascribable to premolding by enabling supply of a material to a kneader exclusively, continuously and intermittently, by providing a material supply equipment with a kneader and a feeder for supply of a kneaded thin from the kneader into a barrel. CONSTITUTION:A material supply equipment 80 is provided with a feeder 81 and kneader 82 provided on a material inlet 28 of a barrel 22 in a communicating state with each other. The feeder 81 is of a biaxial screw type and is provided with screws 81b, 81c which are driven in the opposite directions with each other within a casting 81. The kneader 82 is provided with an agitating screw 82a and motor 82b turning and driving the agitating screw 82a. Therefore, the title injection molding machine can feed raw materials such as one or more resin ingredients or curing agent ingredients or glass fibers into the kneader 82 and the mixture are fed into the barrel 22 through the feeder 81 after they have been kneaded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an injection molding machine, and particularly to BMC (Bulk
Molding Compound etc.
The present invention relates to an injection molding machine suitably used for molding materials containing fibers.

[Prior art] Molding materials made by mixing glass fiber with synthetic resins such as unsaturated polyester have various compositions and compositions depending on the application and molding method.
There are properties.

The mechanical properties of a molded product have a strong correlation with the condition of the glass fibers in the molded product; the longer the fiber length and the less bent the better.
Mechanical strength is improved.

The length of glass fiber in a molded product is not only related to the length of the raw glass fiber, but also to the molding method, and it is important to use a molding method that minimizes breakage as much as possible. It is necessary to improve mechanical properties.
.

Plunger type molding machines have less breakage and bending of glass fibers than screw type molding machines. However, despite these advantages, plunger type molding machines are rarely employed in practice. This is due to the following structural drawbacks. Figure 6.7 shows the general structure of the plunger type.

FIG. 6 is a schematic diagram of a conventional plunger-type injection molding machine. The molding machine 1 includes a stuffer 3 and a barrel 4 connected by an elbow 2. A plunger 6 of the supply cylinder 5 is fitted so as to be able to reciprocate. Further, a plunger 8 of an injection cylinder 7 is fitted into the inner hole of the barrel 4, and a material supply port 9 from the stuffer 3 is opened at an intermediate portion of the inner hole near the nozzle 1o. 11 is a check valve for preventing material backflow. With this configuration, when the material 12 is introduced into the stuffer 3 and the plunger 6 of the supply cylinder 5 is advanced, the material 12 is supplied into the barrel 4 from the material supply port 9 through the elbow 2. and check valve 1
1 restricts backflow. Then, by advancing the plunger 8 of the injection cylinder 7, the material 12 in the barrel 4 is
can be injected into the mold from the nozzle 10.

Further, FIG. 7 is a schematic configuration diagram showing another example of a conventional plunger type injection molding machine, and the same reference numerals as those in FIG. 6 have the same structure, so a description thereof will be omitted. This example differs from the example shown in FIG. 6 in that the material supply port 9A from the stuffer 3 opens at the end of the barrel 4A on the side opposite to the nozzle 10 and that there is no check valve 11. . As in the example shown in FIG. 6, the material 12 is supplied into the barrel 4A by advancing the plunger 6, and injection is performed by advancing the plunger 8.

However, in the conventional molding apparatus shown in FIG. 6, the material supply port 9 is provided closer to the nozzle 1o, so when the material 12 is metered and fed from there, back pressure is applied by the injection cylinder 7. However, on the other hand, the material 12 that enters the inner hole of the barrel 4 from the material supply port 9 first faces the plunger 8, and the material 12 that enters later faces the nozzle 10.
The material 12 that entered first during injection
Since the material 12 comes out later, there is a disadvantage that the material 12 tends to remain. Furthermore, since the seal portion of the plunger 8 passes through the material supply port 9 during injection, the seal portion is likely to be damaged.

Furthermore, in the case shown in FIG. 7, the material supply port 9A is provided closer to the plunger 8, and the material 12 is supplied by retracting the plunger 8 for each shot, so the material 12 that entered first is However, since no back pressure is applied, the metering of the supplied material 12 becomes unstable and air is easily drawn in.

As a means to solve these drawbacks, the present applicant has proposed patent application No.
We proposed a rotating plunger type injection molding machine as shown in the figure.

In FIG. 8, a cylindrical barrel 22 has a nozzle 21 at its tip and a relatively low temperature temperature control device at its outer periphery.
is arranged so that the nozzle 21 can face the material injection port of the mold.

Inside the barrel 22, a plunger 24, which has an outer diameter smaller than the inner diameter of the barrel 22 and has a backflow prevention mechanism consisting of a check ring 23, a ball, etc. near the tip, is provided so as to be movable forward and backward and rotatable. A material passage 70 is formed between the inner peripheral surface of the barrel 22 and the outer peripheral surface of the plunger 24.
is formed. Material inlet section 2 on the rear side of the barrel 22
8 is provided with, for example, a stuffer type material supply device having a stuffer plunger 3° in a stuffer 27 having a material population 31 as shown in the figure.

In an injection molding machine having such a configuration, when the stuffer plunger 30 for material supply is advanced while the plunger 24 located at the front within the barrel 22 of the injection cylinder is rotated, the material is supplied while being measured. The material is supplied to the tip inside the barrel of the injection cylinder via the port 28', the material passage 7o, and the backflow prevention mechanism 23. Metering ends when the desired amount of BMC etc. is accumulated in front of the barrel 22, and then when the plunger 24 is moved forward, the material is injected from the nozzle 21, but in this case, the material that entered the material passage 7o first is Get out. Furthermore, the rotation of the plunger 24 makes the material flow extremely smooth and uniform. Although this plunger type injection molding machine does not have a part corresponding to a screw type flight, it has a characteristic that its metering capacity increases in proportion to the number of rotations.

[Problems to be Solved by the Invention] According to the above-mentioned structure proposed in Japanese Patent Application No. Sho-79197 and No. IO-168898, a molded product having excellent performance with less damage to glass fibers can be obtained. However,
It was recognized that this type has the following improvement issues.

That is, as shown in FIG.
The 7 types use a method of pushing in with a plunger.

According to such a structure, it is necessary to prepare the materials in advance at a separate location, preform them into a size that is easy to handle, transport them, and then feed them into the molding machine. Therefore, it undergoes unnecessary deformation during preforming.

Furthermore, as the molded product and the molding machine become larger, the size of the blocks fed into the molding machine each time increases, and eventually it becomes virtually impossible to handle the product in block form.

[Means for Solving the Problems] The present invention provides an injection molding machine in which a plunger is inserted into the barrel and a material supply device is connected to the rear side of the barrel, and the material supply device is a kneader and a material supply device from the kneader. A feeder for feeding the kneaded material into the barrel was adopted.

[Function] By adopting the above structure, the raw materials can be separated individually and continuously, such as glass fiber and resin component, resin component and curing agent component, A resin component and B resin component (or even glass fiber), etc. It becomes possible to supply the material to the kneader intermittently or intermittently, and it is possible to prevent the impact strength from decreasing due to preforming.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is an overall sectional view showing the configuration of an injection molding machine according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view of the same essential parts, and FIG.
FIG. 3 is a sectional view taken along line III-III in FIG.

In FIG. 1.2, a cylindrical barrel 22 having a nozzle 21 at its tip and a relatively low-temperature heater at its outer periphery is connected to a material injection port of a fixed mold 61 attached to a fixed platen 60. It is arranged so that the nozzle 21 is exposed. 62 is a column, 63 is a column nut, 64 is a machine base on the mold clamping device side, 65 is a machine base on the injection device side, 66 is a block provided slidably in the axial direction on the machine base 65; On top, a barrel 22 is fixed to the front, and a motor holding member 6 is fixed to the rear.
7 is slidably attached.

68 is a cylinder for moving the block 66B fixed to the fixed plate 60; 69 is a piston rod;
The tip of the nozzle 21 is fixed to the center of the outer surface of the block 66, and the operation of the cylinder 68 causes the nozzle 21 to come into contact with the fixed mold 61 or to be retracted to the illustrated state.

Inside the barrel 22, a plunger 24, which has an outer diameter smaller than the inner diameter of the barrel 22 and has a backflow prevention mechanism consisting of a check ring 23, a ball, etc. near the tip, is provided so as to be movable forward and backward as well as rotatable. . A material passage 70 is formed between the inner peripheral surface of the barrel 22 and the outer peripheral surface of the plunger 24.
has been established.

A shaft of a rotation driving device such as a hydraulic motor 35 fixed to the motor holding member 67 is connected to the rear of the plunger 24 via a bearing portion 71 within the motor holding member 67 .

Further, an injection cylinder 72 and a piston rod 73 are attached between the barrel 22 and the lower side of the motor holding member 67.

A convex portion 25 in contact with the inner circumferential surface of the barrel 22 is provided at the center of the plunger 24. In addition, the convex portion 2 of the plunger 24
A screw 29 for discharging leakage material was provided on the rear side of 5. This screw 29 connects the outer peripheral surface of the convex portion 25 and the barrel 2.
This is for smoothly discharging leak material flowing backward from the clearance part between the inner peripheral surfaces of the barrel 22 to the rear of the barrel 22, and is provided in a thread direction opposite to the rotational direction of the plunger 24. .

Reference numeral 80 denotes a material supply device, which includes a feeder 81 and a kneader 82 connected to the material inlet 28 of the barrel 22. In this embodiment, the feeder 81 is of a two-shaft screw type, and is provided with screws 81b and 81c that are driven in mutually opposite directions within a Keirin'j 81a. 81d is a motor for driving the screws 81b and C.

In this embodiment, the kneader 82 includes a stirring screw 82a and a motor 82b for rotationally driving the stirring screw 82a, and a raw material inlet 82d is provided at the upper part of a cylindrical casing 82c.

Therefore, raw materials such as one or more resin components, curing agent components, or glass fibers can be supplied into the kneader 82, kneaded, and then supplied from the feeder 81 into the barrel 22. ″Damage of glass fiber at feeder
By appropriately selecting the shape of the feeder, this can be almost completely prevented.

In the apparatus shown in FIG. 1, a material such as BMC is charged into the stuffer 27 with the plunger 24 positioned at the forward limit and rotating at 25 to 150 rpm, and the feeder 81 is activated. let The material is then sent forward through the outer periphery of the plunger 24, passes through the check ring 23, and is sequentially collected in the barrel 22 in front of the plunger 24. Of course, in this metering process, the plunger 24 gradually retreats.

At this time, back pressure can be applied to the material by controlling the hydraulic pressure in the rod end side chamber of the injection cylinder 72 connected to the rear of the plunger 24. Note that back pressure can also be applied to the material by friction between the outer peripheral surface of the convex portion 25 of the retreating plunger 24 and the inner peripheral surface of the barrel 22.

The rotation of the plunger 24 homogenizes the resin material around the plunger 24 and prevents short circuits in the flow path of the material. Also, due to the suppressing action of the stuffer plunger 30 and the rotating action of the plunger 24, the material is
The material is pushed in such a way that it goes around the material passage 70 on the lower side of the plunger 24 without passing through only the material 1 passage 70 on the upper side of the plunger 24, and the material also flows from the lower side of the plunger 24 to the upper side, or Since the material is fed while going around from the upper side to the lower side, it is smoothly fed all around the entire circumference of the barrel 22 without staying in the barrel 22 even in areas where the material flows or the material is difficult to flow.

In the above embodiment, a screw feeder 81 is used, but in the present invention, a vane-type feeder 83 shown in FIG. 4 or a roots-type feeder 84 shown in FIG. Various feeders capable of generating a supply pressure of about 100 kg/crn' can be employed.

[Effects] As is clear from the above embodiments, the injection molding machine of the present invention allows raw materials to be supplied to the kneader continuously or intermittently. This eliminates the need for preforming.Also, since the material is not handled in block form, material feeding becomes easier, especially in the case of large machines.

[Brief explanation of the drawing]

Fig. 1 is an overall sectional view of the embodiment device, Fig. 2 is a partial sectional view thereof, Fig. 3 is a sectional view taken along the line III--III in Fig. 2, and Fig.
Figures 6 and 7 are cross-sectional views of different feeders.
8 and 8 are cross-sectional views showing the prior art. 22...Barrel, 23...Tickle ring, 24...Plunger, 27...Stuffer,
30... Stuffer plunger, 70... Material passage, 81... Feeder, 82
... Needa.

Claims (1)

[Claims] (1) A barrel that has an injection port at the tip and a material inlet at the rear side, and a barrel that is inserted into the barrel and has a diameter that forms a material passage between the circumferential surface and the inner circumferential surface of the barrel. a plunger having a rear end connected to a drive device and reciprocated within the barrel; a material supply device connected to a material inlet of the barrel; and a plunger provided in a material flow path within the barrel. An injection molding machine comprising: a material backflow prevention mechanism; and wherein the material supply device includes a kneader and a feeder that supplies a kneaded material from the kneader to the material inlet.