JPH0436900Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of an in-line screw of a screw type injection device used for injection molding of rubber or plastic.

[Conventional technology]

As an in-line screw type injection device, the one shown in FIG. 4 has been known.

In the figure, 101 is a heating cylinder, and 102 is an injection nozzle attached to the tip of the heating cylinder 101. A screw body 103 that rotates and reciprocates in the axial direction is inserted into the heating cylinder 101, and a conical screw head 105 in which a plurality of passage grooves 106 extending in the axial direction are formed at the tip of the body 103; A head metal fitting 104 having a neck portion 107, which is a small diameter portion formed at the rear of the screw head 105, is screwed 108.
A back flooring 109 is loosely fitted onto the outer periphery of the neck portion 107 and slides on the inner circumferential surface of the heating cylinder 101 with a minute clearance.

This back flooring 109 functions as a check valve. That is, as shown in FIG. 5, during the metering stroke in which the screw main body 103 and the head metal fitting 104 connected thereto move backward while rotating, the back flooring 109 moves against the screw head 10 in the outer circumferential space of the neck 107.
On the 5th side, the molten molding material is sent from the screw side space 110 to the nozzle side space 112 through the gap 111 between the neck 107 and the back flooring 109 and the passage groove 106, and then to the screw body 103 and the head. The metal fitting 104 is the nozzle 1
During the injection stroke that advances toward the 02 side, the back floor ring 109 is pushed backward as shown in FIG. The molten material comes into close contact with the tip surface 113 of the screw to prevent the molten material from flowing back into the screw side space 110.

[The problem that the idea attempts to solve]

However, in the conventional device described above, since the back flooring 109 has a simple ring shape, there are problems as listed below.

a Back flooring 10 to the outer periphery of the neck 107
9, it is necessary to manufacture the screw body 103 and the head fitting 104 separately.

b. If the threaded connection 108 between the screw body 103 and the head metal fitting 104 were to loosen, the metering (the amount of molten material injected) would become inaccurate.

c When replacing the back flooring 109 when it is worn out or when removing molten material stuck around the back flooring 109 and the head fitting 104 when changing the molding material, use the screw 10
This involves a troublesome work such as having to separate the screw body 103 and the head fitting 104 which are in the 8-state.

d In order to prevent the back flooring 109 from being damaged by the injection pressure applied to its inner circumferential wall, the hardness is improved or the wall thickness is increased. Sometimes galling with the inner peripheral surface of the heating cylinder 101 tends to occur, and if the wall thickness is increased, the transfer speed of the molten material passing through the gap 111 during the metering process is reduced.

e. If the back flooring 109 is damaged by the injection pressure, the resulting crushed powder and fragments will be mixed into the molten material.

[Means to solve the problem]

In order to solve the above-mentioned problems all at once, the in-line screw of the injection device according to the present invention has a back flooring loosely fitted around the outer periphery of the small diameter neck between the screw main body and the screw head protruding from the tip of the screw main body. It has a structure in which it is divided into a plurality of divided pieces in the direction.

[Effect]

In the above configuration, when assembling the back flooring to the outer periphery of the neck, the tip side of the screw main body is exposed from the heating cylinder, and the divided pieces separated from each other are combined in a ring shape from the outer periphery of the neck, and the screw main body and The entire screw head can be inserted into the heating cylinder, and there is no need to separate the screw main body and the screw head as in the past.
The neck and screw head can be integrated.

When in use after assembly, the directions of pressure, sliding resistance, etc. applied to each segment of the back flooring are the same, so the back flooring operates integrally like a single annular body.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

In the illustrated embodiment, 1 is a heating cylinder, 2
3 is an injection nozzle, 3 is a screw body, 4 is protruded from the tip of the screw body 3, and has a plurality of passage grooves 5 on the outer periphery.
A conical screw head 6 having a diameter is a small diameter neck between the screw head 4 and the former screw body 3, and the screw body 3, the screw head 4 and the neck 6 are integrally formed. Reference numeral 7 denotes a back flooring that is loosely fitted around the outer periphery of the front neck 6 and slides with a minute clearance on the inner circumferential surface of the heating cylinder 1, and is divided into two parts at a position of 180° in the circumferential direction, that is, into two arc-shaped parts. The ends of the pieces 7a and 7b are made to face each other to form an annular shape. As mentioned earlier, the screw body 3, screw head 4, and neck 6 are integrated, but this is due to the back flooring 7 attached to the outer periphery of the neck 6.
By dividing it in the circumferential direction, it became possible to integrate it as a result.

The first divided pieces 7a and 7b are manufactured separately in advance and their contact surfaces 8 and 8 are processed into serrated zigzag surfaces, etc., or they are cut by applying high frequency vibration to an endless annular body (vibration type). When obtaining the divided pieces 7a and 7b using the latter vibratory cutting method, a notch 9 having a V-shaped cross section as shown in FIG. If it is provided, cutting is easy.
Also, the divided pieces 7 obtained by this vibration cutting
Since a and 7b were originally one annular body, there is an advantage that the contact surfaces 8 are perfectly aligned.

In this embodiment, the back flooring 7 is divided into two parts, but it is optional to divide it into three or more parts.

[Effect of idea]

As explained above, the in-line screw of the present invention has a structure in which the back flooring, which is attached to the neck between the screw main body and the tip of the screw head, is divided, so that the following effects can be obtained.

a) Since the screw main body, neck and screw head can be integrated, manufacturing can be facilitated.

b By integrating the screw main body and the screw head, it is possible to prevent errors in measurement due to loosening of the head fittings, which is the case in the past.

c. Replacement of the back flooring when it wears out or maintenance when changing the molding material can be carried out without the need to separate the screw body and head fitting as in the past, improving work efficiency.

d Because the back flooring is divided, the form of stress due to injection pressure is different from that of a one-piece annular flooring, and it does not break, so there is no generation of fragments due to such breakage, and the purpose is to improve durability. There is no need to increase the thickness or hardness of the back flooring.

[Brief explanation of drawings]

Fig. 1 is a front sectional view of essential parts showing one embodiment of the present invention, Fig. 2 is a sectional view taken along line A-A in Fig. 1, Fig. 3 is a front view of back flooring, Figs. 4 and 5. is a front sectional view of a main part showing a conventional example. 1... Heating cylinder, 2... Injection nozzle, 3...
...Screw body, 4...Screw head, 5...
Passage groove, 6...Neck, 7...Back flooring, 7a, 7b...Divided piece, 8...Contact surface, 9...
...Notsuchi.

Claims (1)

[Scope of utility model registration request] A back flooring 7 loosely fitted around the outer periphery of the small diameter neck 6 between the screw main body 3 inserted into the heating cylinder 1 of the injection device and the screw head 4 protruding from the tip of the screw main body 3 is divided into a plurality of divided pieces in the circumferential direction. An in-line screw for an injection device, characterized in that it is divided into 7a and 7b.