JPS60212316A - Screw type injector - Google Patents

Abstract

PURPOSE:To enable a precise control of injection with a smaller size of a screw and cylinder by providing a plunger slidably at a nozzle section of the cylinder to make the cylinder and the screw movable forward to and backward from the mold while the screw is set at the home position for the cylinder. CONSTITUTION:A cylinder 12 and a driving source 18 of a screw 13 are fixed on the same base 19 and the screw 13 is rotated at the home position within the cylinder 12. A plunger 14 having an injection hole 15 inside is provided slidably in a nozzle section 12a at the tip of the cylinder 12 and the tip of the plunger 14 is fastened on a mold 17. Then, the base 19 is moved forward to or backward from the mold 17 on a slide surface 21 with a fluid cylinder mechanism 20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a screw type injection device used for injection molding of synthetic resin molded products.

Conventionally, a wide variety of synthetic resin molded products have been molded from various thermoplastic and thermosetting resins, and many of these molded products are manufactured using a so-called in-line screw injection device. In this in-line screw type injection device, as shown in Fig. 1, molding materials such as resin pellets and colorants 1
A is heated and melted in cylinder 2, and then screwed into bladed screw 3.
The molding material 1a is kneaded and pumped by rotating the screw 3, and the pressure inside the cylinder 2 is increased by stopping the rotation of the screw 3 and moving the screw 3 forward. lb of molten material is injected into the cylinder. The screw 31 and cylinder 2 are installed on a base 7 that is slid by the shift cylinder 6, and the screw 3 is driven by an injection cylinder 8 that is also installed on the base 7. Then, when the screw 3 is rotated again, the screw 3 is pushed back backward by the reaction force of the molten material ib accumulating at the tip of the screw 3, and the amount of retreat is regulated by the limit switch 9. ,
The next injection amount is determined by stopping the rotation of the screw 3 at a fixed position.

When manufacturing minute molded products, it is desirable to reduce the size of the screw 3 according to the molded product, but it is difficult to downsize the screw 3 due to mechanical constraints, and the injection amount The drawback is that precise control cannot be performed, resulting in a high incidence of defective products. Therefore, molten material 1 in Venus 5
By increasing the amount of the molten material 1b remaining in the spool and launch which serve as passages for introducing the molten material 1b, the distribution of the molten material 1b within the mold 5 must be adjusted, and the yield of the molten material 1b can be reduced. There is a problem that the cooling time is extremely poor and the cooling time is long.

In order to solve these problems, the present applicant has already published Japanese Patent Application No. 174270/1983 regarding a screw type injection device that enables accurate and precise control of the injection amount when manufacturing minute molded products, for example. I have applied. it is,
A cylinder equipped with a nozzle and a hopper, a screw that rotates at a fixed position in the cylinder to force-feed the molding material, a screw that has a through hole along its axis, and a screw that can move forward and backward within the through hole of the screw. It is equipped with a plunger. However, this improved injection device also has two (II) for injection and shift, similar to the conventional one shown in FIG.
A cylinder mechanism is required.

The purpose of the present invention is to simplify the overall structure by allowing one cylinder mechanism to share the two cylinder mechanisms used in conventional injection devices, one for injection and one for shifting.
The purpose of this is to provide a small, lightweight, and highly accurate screw-type injection device that significantly reduces manufacturing and operating costs and can mold minute molded products with high precision. An injection device that has a cylinder that heats and melts the cylinder, and a screw that rotates at a fixed position within the cylinder and pressurizes the molding material to the nozzle side of the cylinder. A plunger having an injection hole in the direction is slidably fitted into the cylinder between the curves, and a drive mechanism for driving the plunger in the axial direction is connected to a base to which the electric motor for driving the cylinder and the screw is fixed. It is characterized by:

The present invention will be explained in detail below based on the embodiments shown in FIG. 2 and below.

In FIG. 2, 10 is a hopper that supplies the molding material 11, and 12 is a cylinder that melts the molding material. is built-in and can be rotated freely.

In this case, the screw 13 is rotated at a fixed position relative to the cylinder 12, and the volume of the space surrounded by the cylinder 12, the screw blades 13a, and the screw body 13b gradually decreases toward the tip of the screw 13.

A plunger 14 is inserted into the nozzle portion 12a of the cylinder 12 so as to be slidable with respect to the cylinder 12, and from an injection hole 15 bored in the axial direction of the plunger 14, a molten material $411b is melted by the heating device 16. is injected into the metal m17. The drive motor 18 that rotates the screw 13 and the cylinder 1
2 is constructed on a common base 19, and the sliding surface 2! is moved in the axial direction of the cylinder 12 by a single cylinder mechanism 20 consisting of a hydraulic or pneumatic cylinder. A base 19 is slid onto the top. Moreover, 22 and 23 are power transmission gears of the drive electric motor 18. Although not shown in the drawings, other peripheral devices such as control devices such as the heating device 16, drive motor 18 or cylinder mechanism 20, and limit switches for detecting the amount of movement of the base 19 are of course arranged. It is.

Here, the plunger 14 is designed to prevent it from accidentally escaping from the cylinder 12, and the injection amount and plunger diameter are changed depending on the molded product. Preferably, FIG. 3 shows a practical example of attachment to facilitate attachment and detachment, and the attachment tube 24 is screwed onto the tip of the cylinder 12.
Slideably fit the plunger 14 into the mounting tube 2.
4 from the cylinder 12, the plunger 14 can be replaced.

At this point, set the inner diameter of the tip 24a of the mounting tube 24,
The inner diameter of the rear end portion 24b is smaller than that of the plunger 14.
A large diameter part 14a provided at the rear end for preventing removal is attached to the rear end 2.
4b, the plunger 14 will not escape unless the mounting tube 24 is removed.This is only an example of how to install the plunger 14.
4 can be attached and detached freely, and can be attached in such a way that it will not come out accidentally during attachment, so various attachment methods are possible in addition to the embodiment shown in FIG.

In the configuration shown in FIG. 2, necessary molding materials 11a such as resin pellets, fillers, reinforcing agents, colorants, etc. are supplied from a hopper '10 into a cylinder 12 heated to a predetermined temperature by a heating device 16. When the molding material 11a is forced forward by the screw 13 rotating at the
As it advances toward the tip, it becomes a single masonry, becomes mixed by rotation, and is further melted and plasticized by the shearing and heating action of the screw 13 and heating device 16, becoming a molten material 11b and entering the injection hole 15 of the plunger 14. Get into it.

Here, the rotation of the screw 13 is stopped, and the plunger 14
When the base 19 is advanced by the cylinder mechanism 20 with the gold M17 set at the tip of the cylinder, the plunger 14 is pushed into the cylinder 12, and the molten material 11b is poured into the mold 17 under appropriate pressure. Injected into the cavity.

After the molten material 11b fills the cavity and is cooled and solidified, when the screw 13 is rotated again, the molten material 1
1b is fed into the tip of the screw 13 and accumulated, and the reaction force causes the cylinder 12 to retreat together with the base 19.

Therefore, by setting this retreat amount to a predetermined value using a control means such as a limit switch, the primary injection amount can be quantified by stopping the rotation of the screw 13. The amount of one injection of the molten material 11b is determined by the diameter of the injection hole 15 of the plunger 14 and the forward stroke of the cylinder 12, so by changing these minutely, the injection amount can be finely adjusted. .

As mentioned above, the screw type injection device according to the present invention not only ensures excellent injection speed and injection pressure, which are the advantages of the conventional in-line screw type injection device, but also
There is no need for reciprocating movement of the screw relative to the cylinder, and the injection amount can be determined with extreme precision by the plunger. Also,
The spool and runner inside the mold can be made smaller, which improves the yield of molten material and shortens the cooling time inside the mold, making it ideal for molded products and minute molded products that require particularly high precision. is particularly advantageous. In particular, in the case of the present invention, since the two cylinder mechanisms for injection and shift that were conventionally required can be shared by a single cylinder mechanism 20, the overall structure is simplified and the entire device can be compared to the conventional one. It can be made significantly smaller and lighter than the previous model, with significant benefits such as significantly lower manufacturing and operating costs.

Moreover, by removing the plunger portion and making it easy to replace it, it is possible to freely and easily change the plunger diameter, the injection amount, the color of the molded resin, etc. Further, even if the molten resin material leaks from the gap between the plunger and the nozzle portion, the operation of the plunger will not be hindered, and the leaked material can be easily removed.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional screw type injection device, Figure 2
The figures below show an embodiment of the screw type injection device according to the present invention, FIG. 2 is a sectional view thereof, and FIG. 3 is an enlarged sectional view showing an example of how a plunger is attached. 10 is a hopper, lla is a molding material, llb is a melting material, 12 is a cylinder, 13 is a screw, 14 is a plunger, 15 is an injection hole, 18 is a driving electric motor, 19 is a base,
20 is a cylinder mechanism, and 24 is a mounting tube.

Claims (1)

[Scope of Claims] 1. An injection device comprising a cylinder that heats and melts a molding material, and a screw that rotates at a predetermined position within the cylinder and pumps the molding material to the nozzle side of the cylinder, wherein the cylinder A plunger having an injection hole in the axial direction is slidably fitted into the cylinder between the nozzle part and the mold,
A screw-type injection device characterized in that a drive mechanism for driving the plunger in the axial direction is connected to a base to which a driving motor for the cylinder and screw is fixed. 2. The screw type injection device according to claim 1, wherein the plunger is fitted into a mounting tube that is threaded onto the nozzle portion of the cylinder.