JP3310601B2 - Die mechanism for extrusion molding with variable cross-sectional shape - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical drain tube for draining unnecessary body fluids accumulated at a treatment site in a body after treatment to outside the body, mainly in a surgical treatment.
The present invention relates to a die mechanism of an extruder.

[0002]

2. Description of the Related Art There are many medical tubing products in which the shape of the lumen changes in several stages in one tube product. For example, in the case of a drain tube for treating wounds, it is necessary to provide a cavity with a rib on the indwelling part side of the body in order to improve drainage efficiency and prevent kink, but on the outside of the body, connectors such as a drainage bottle are required. For convenience of connecting to
It is necessary to use a tube having a perfect circular shape and a relatively thick wall. The medical tube to be molded according to the present invention comprises 1
This is a tube in which different functions are required stepwise in the longitudinal direction of the book tube.

[0003] In the prior art, for example, when manufacturing a tube having a lumen with a thin rib and a rounded lumen,
A method has been adopted in which a tube having a lumen with a thin rib and a tube having a perfect circular shape are separately formed, and then the two tubes are bonded via a separately formed component such as a connector. However, in this method, not only the number of parts is increased but also the automation of the process is difficult, so that the assembly process must be performed manually, and it is impossible to reduce the cost of the product mainly in terms of man-hours. In addition, the inevitable step of the connector on the outer periphery of the tube often causes inconvenience when used as a medical tube.

As a means for solving this problem, a variable die shape mechanism using a crosshead mechanism has been developed, and an extrusion die mechanism for continuously changing the shape of the lumen has been put to practical use. In many cases, a plurality of components are required, the driving unit has a complicated mechanism, and the layout of the manufacturing line may have to be changed, and the cost is high.

[0005]

SUMMARY OF THE INVENTION The present invention has been made as a result of various studies in order to solve such problems of the conventional tube molding. In the extrusion molding, the shape of the lumen in the longitudinal direction of the tube is changed. It is an object of the present invention to provide a die mechanism for variable-section extrusion molding, which can easily be changed continuously at regular intervals, simplifies the process, and has a low equipment cost.

[0006]

That is, according to the present invention, a land portion of an in-die (a molded product lumen shape determining portion) has a multi-stage structure having a plurality of different cross-sectional shapes, and the in-die is moved back and forth in a resin flow direction. A cross-sectional shape variable extrusion molding die mechanism characterized in that the shape of the bore of the molded product is changed by causing the die to change.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of a die mechanism for extrusion molding with a variable cross section according to the present invention, and FIG. 1 is a schematic view of a die mechanism for extrusion molding with a cross section having a rib shape and a perfect circular shape. It is. FIG. 2 shows a movable in-die (1) of the mechanism.
FIG. FIG. 3 is a diagram showing the positional relationship of the movable in-die (1) of the mechanism during tube molding and a sectional view of the molded product.
(A) is the positional relationship during molding at the front part (7) of the in-die,
(B) is a cross-sectional shape of the molded article at that time. (C) shows the positional relationship at the time of molding at the rear part (8) of the in-die, and (d) shows the cross-sectional shape of the molded product at that time. FIG. 4 shows an embodiment of a molded article that can be molded by the mechanism of the present invention and the shape of the movable in-die.

[0008] The die mechanism for variable section extrusion molding of the present invention comprises:
As shown in FIG. 1, by moving an in-die fixed in normal tube extrusion back and forth in the resin flow direction in the resin flow path, the inner cavity of the tube is formed in the continuous extrusion. This makes it possible to change the cross-sectional shape.

The movable part is only the movable in-die (1),
Out die (2) is basically fixed. The actuator (3) for moving the movable in-die (1) may be one that moves backward and forward, for example, one air cylinder. The position where the actuator (3) is installed is basically located rearward on the same axis as the movable in-die (1), and a crosshead can be most easily incorporated. In addition, since the movable portion is a mechanism that receives little resistance from the resin, the driving force of the small actuator (3) is sufficient. In the case of a molding layout other than the crosshead, for example, a normal horizontal take-up type molding layout, It is also possible to embed a small actuator (3) in the resin flow path, and it is possible to easily cope with any extruder.

The movable in-die (1) is provided with portions having different cross sections as many as the cross-sectional shape of the lumen is desired to be changed, and as shown in FIG. A desired cross-sectional shape is provided at the rear part (8) of the in-die. When changing the cross-sectional shape, molding of a desired cross-sectional shape is performed by moving the movable in-die (1) in the resin flow direction.

As shown in FIG. 3 (a), when the die is formed in a sectional shape of the front part of the in-die (7), the front part of the in-die (7) is connected to the out-die land part. In (4), as shown in FIG. 3C, in the case of molding in the shape at the rear part of the in-die (8), the rear part of the in-die (8) is moved to the out-die land part (4). The cross-sectional shape of each molded product is as shown in FIGS. As shown in FIG. 3C, at the time of molding at the rear part of the in-die (8), the front part of the in-die (7) is out-die (2).
The front of the in-die (7)
It is desirable that the length be as short as possible in consideration of the formable land length.

In the case of a medical tube, since the tube diameter is in the range of 1 to 30 mm, the out-die land portion (4)
Is preferably 2 to 30 mm or less, and the length of the front part (7) of the in-die and the rear part (8) of the in-die are also preferably equal to the length of the land part (4) of the out-die. In the extrusion in the horizontal direction, there is a concern that the tip of the front part of the in-die (7) may come into contact with the inner cavity of the molded product. If there is a concern that the tip of the in-die front (7) may come into contact with the cavity of the molded product, the in-die front (7)
Can be reduced to about 70% of the length of the out-die land portion (4), which is useful. When extruding in the vertical direction with a crosshead, the number of steps can be changed. 2-3 stages are suitable.

The front part of the die (7) and the rear part of the die (8)
The cross-sectional shape of each is arbitrary and no problem,
In the mechanism according to the present invention, the shape of the front part of the in-die (7) is changed to the shape of the rear part of the in-die (8), and As long as it is completely included from the surface, any cross-sectional shape can be extruded with variable cross-sectional shape.

[0014]

As described above, the use of the die mechanism for variable cross-section extrusion molding according to the present invention makes it possible to easily change the shape of the lumen at regular intervals in the longitudinal direction of the tube in extrusion molding. Thus, the process can be simplified and the equipment cost can be reduced, which is extremely useful.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a die mechanism according to the present invention.

FIG. 2 is a view showing one embodiment of an in-die of a die mechanism according to the present invention.

3A and 3B are diagrams showing a positional relationship of an in-die at the time of molding of a die mechanism according to the present invention, wherein FIG. 3A shows a position of an in-die at the front of the in-die and FIG. Shows the cross-sectional shape. (C) shows the position of the in-die at the rear of the in-die during molding, and (d) shows the cross-sectional shape of the molded product at that time.

FIG. 4 shows a combination of tube cross-sectional shapes that can be formed by a die mechanism according to the present invention and an in-die shape thereof.

[Explanation of symbols]

 1. Movable in-die 2. Out die 3. Actuator 4. Out die land section 5. Indie holder 6. Die head 7. 7. Indai front 8. Indai rear Example 1 of tube shape due to front part of in-die Example 1 of tube shape by rear part of in-die 11 Movable in-die example 1 12. Tube shape example 2 due to front part of in-die 13 13. Tube shape example 2 due to rear part of in-die Movable in-die example 2 15. Tube shape example 3 due to front part of in-die 16 Tube shape example 3 due to rear part of in-die 17 Movable in-die example 3

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 47/00-47/96 A61M 25/00 A61M 27/00

Claims (3)

(57) [Claims] 1. A land portion of an in-die (a molded product lumen shape determining portion) has a multi-stage configuration having a plurality of different cross-sectional shapes,
A cross-sectional shape variable extrusion molding die mechanism characterized in that the shape of the inner cavity of a molded product is changed by moving the in-die forward and backward in the resin flow direction. 2. The variable cross-sectional shape according to claim 1, wherein in the in-die land portion having a two-stage configuration having different cross-sectional shapes, the cross-sectional shape on the rear end side of the in-die includes the cross-sectional shape on the front end side. Extrusion die mechanism. 3. The die mechanism for extrusion molding according to claim 1, wherein the molded product is a specially shaped tube used for medical applications.