JP3645781B2 - Dies for variable section extrusion - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a mechanism of an extrusion die for a medical drain tube for draining (extracting) body fluid that exudes to a treatment site in a body after surgery, mainly in surgical treatment.
[0002]
[Prior art]
In medical tubes, there are many products in which the shape of the lumen changes in several stages in one tube product. For example, a drain tube for wound treatment satisfies a function required by changing a cross section of a portion of the tube in the longitudinal direction. In order to satisfy the required functions, first, the part that is placed in the body and sucks the body fluid of the treatment part is attached with ribs so that the drainage is easy to suck and does not kink even if it is compressed by the organ. The cavity is as large as possible.
[0003]
On the other hand, a thread is wrapped around the tube so that the tube does not come off and the skin is fixed to the skin so that the tube does not kink with the wrapped thread and ribs are provided in the lumen so that the drainage is not boring. In order to provide airtightness, the suture fixing part and the part connected to connectors such as a drainage bottle have a round shape with no ribs in the lumen, and a relatively thick part that is difficult to kink. I need it.
[0004]
In the prior art, for example, to produce a drainage tube as shown in FIG. 4, the tube 1 (13) to be placed in the body is formed, and a new tube 2 (14) is attached to the outside of the rear end and bonded, In addition, the connector (15) having a round lumen without a rib at the rear end is required to be bonded after being molded separately, and in some cases, when the tube is taken out from the body, it breaks from the bonded portion. Sometimes, clots were clogged because blood clots were likely to adhere to the steps of the joints. In addition, the molding and bonding are required several times, which increases the cost.
[0005]
On the other hand, in order to solve the above problem, the technique disclosed in Japanese Patent Application No. 09-289340 is applied to extrude a tube whose cross-sectional area changes stepwise as shown in FIG. There is a technique of integrally molding by moving back and forth in the direction of the resin flow path in the resin flow path (7), but with this mechanism alone, the opening area of the resin outlet portion at the die tip changes, so the screw moves at a constant speed. In the case of rotation, the resin pressure applied to the variable section die is periodically changed. Although the extrusion speed of the extruded resin changes, the take-up speed is constant, so the tube is stretched in the pre-vulcanization furnace, and the outer diameter is reduced at the small cross-sectional area, and the cross-sectional area is reduced. The outer diameter is thicker at the larger area. Further, when the tube is slackened and passed through a pre-vulcanizing furnace, the discharge amount of extrusion cannot catch up with a large cross-sectional area, and the outer diameter becomes small.
[0006]
As a result, a difference in outer diameter occurs in one tube and the dimensions are not stable. Therefore, if the outer diameter of the portion to be placed in the body is large, the patient will be painful or the resistance will increase when the tube is pulled out of the body. The tube was sometimes broken by being pulled with a force stronger than the breaking strength of the material. Moreover, when the outer diameter of the part to be placed in the body is small, the body fluid may leak due to the difference in outer diameter from the part that goes outside.
[0007]
[Problems to be solved by the invention]
The present invention has been made as a result of various studies to solve such problems of the conventional tube forming. In the conventional extrusion forming, the shape of the lumen is continuously formed at regular intervals in the longitudinal direction of the tube. It is an object of the present invention to provide a die for variable section extrusion molding in which it is easy to control the change in outer diameter when forming a changed tube and to make the outer diameter constant.
[0008]
[Means for Solving the Problems]
That is, according to the present invention, in the tube extrusion die in which the outer diameter of the tube is constant and the resin cross-sectional area continuously changes at constant intervals, the resin cross-section area changes between the out die and the in-die. A variable section extrusion die having an opening / closing mechanism for releasing resin to the outside in the middle of a flow path.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic view showing an embodiment of a die mechanism for variable section extrusion molding according to the present invention, and FIG. 1 is provided with a variable section extrusion die according to an embodiment of the present invention. FIG. 2 is a diagram showing the structure of an overflow cock according to an embodiment.
[0010]
As shown in FIG. 1, the die mechanism for variable section extrusion molding according to the present invention synchronizes with the movement of the in-die (2) and opens and closes the resin overflow cock (1) to open and close the resin in the resin flow path (7). It is possible to reduce the pressure change.
[0011]
The resin overflow cock is installed in the middle of the resin flow path. A mechanism like a needle valve (8) as shown in FIG. 2 is used to rotate the valve with a motor (9) or the like to change the opening area. However, there is no particular limitation as long as it is a structure that controls the amount of resin released according to the cross-sectional area and does not retain the resin in the valve portion.
[0012]
The amount of resin escaped is determined by how much the amount of resin discharged from the die tip changes when the cross-section is variable, but when a state where resin does not escape occurs, it solidifies in that part and the opening and closing function works well Therefore, it is preferable that the resin always flows from the resin escape hole, and it is preferable that the minimum amount is determined so that an amount slightly larger than the change in the cross-sectional area can be released.
[0013]
Even if controlled by such a resin escape mechanism, the resin pressure in the extrusion die fluctuates, and although the extrusion speed of the resin exiting the die changes slightly, the take-up speed is always constant, so the tube The outer diameter changes due to stretching or slackening. In order to improve this, the tube detects the slack from the out die (3) to the take-up machine, and changes the take-up speed so that the slack does not change, and the operation of the in-die and overflow cock (1) The outer diameter difference is further improved by controlling the take-up speed in synchronization with the.
[0014]
The die for variable cross-section extrusion of the present invention can be used with either a thermoplastic resin or a thermosetting resin, but the overflow cock (1) and the sliding portion of the indie (2) whose cross-section is variable can easily retain the resin. In the case of a thermoplastic resin, the staying resin may be burned and extruded as a foreign substance, so that the thermosetting resin is easier to mold, but is not particularly limited as long as it is a resin that is difficult to burn.
[0015]
【The invention's effect】
As described above, when the drainage tube made of silicone resin was extruded using the die for variable section extrusion molding of the present invention, molding with a constant outer diameter and stable dimensions became possible. This eliminates the need to perform bonding and molding a plurality of times, so that it is possible to provide a low-cost drainage tube while maintaining the current function.
[Brief description of the drawings]
FIG. 1 is a cutaway sectional view showing the internal structure of a variable section extrusion die according to an embodiment of the present invention.
FIG. 2 shows an internal structure of an overflow cock of a variable section extrusion die according to an embodiment of the present invention. It is a cutaway sectional view.
FIG. 3 is a cross-sectional view of a tube formed by a conventional variable-section extrusion die.
FIG. 4 is a cross-sectional view of a conventional drainage tube.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Overflow cock 2 Indie 3 Out die 4 Actuator 5 Die 6 Extruder 7 Resin flow path 8 Needle valve 9 Motor 10 Section shape 1
11 Cross-sectional shape 2
12 Cross-sectional shape 3
13 Tube 1
14 Tube 2
15 Connector

Claims (1)

In the tube extrusion die where the outer diameter of the tube is constant and the resin cross-sectional area continuously changes at regular intervals, the cross-sectional area between the out die and the in-die changes in the middle of the resin flow path. A die for variable section extrusion molding, characterized by having an opening and closing mechanism for releasing resin to the outside.

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