JPH03143452A - Shaping of tube - Google Patents

Abstract

PURPOSE:To shape stably an accurate shape by mass treatment by shaping the title tube at a shaping temp. using a shape memory alloy wire, performing a shape treatment by combining processes restricting at least two relative positions, cooling it at a shaping temp. or lower and pulling the shape memory alloy wire out. CONSTITUTION:An SMA wire 1 is inserted in an inner cavity of a medical tube catheter 2 and it is kept in a heating bath held at a shaping temp. As soon as it reaches a shaping temp., it is deformed in a pre-memorized shape and therefore, the tube catheter is deformed in a required shape in accordance with a deformed shape of the SMA wire 1. Then, while the SMA wire is inserted, the tube catheter is cooled and kept at a temp. lower than the shaping temp. and thereafter, the SMA wire is pulled out. In addition, while it is cooled to ordinary temp., as a tool preventing a required shape from returning to an original shape, a linear part of the tube catheter 2 is clamped and fixed with a clip 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shaping method that can stably provide large quantities of tubes with complex shapes.

[Prior Art] Conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 59-73937, a rubber hose is vulcanized and molded using a shape memory alloy, and then cooled to shape the shape memory alloy into a linear shape. A method of manufacturing a curved rubber hose is known in which the shape memory alloy is removed after returning the hose.

On the other hand, a method for imparting a desired shape to medical tubes, catheters, etc. is to use a metal wire, such as stainless steel, that has been previously processed into the desired shape, insert the wire into the tube, catheter, etc., and After heat treatment at
The common method was to cool and shape.

Another method of shaping is to insert a core wire such as stainless steel wire into a mold with a smooth surface that has been processed into the desired shape (female mold or male mold consisting of a metal mold, wooden mold, or plastic flyer mold). There are known forming methods such as winding a tube/catheter or inserting the tube/catheter as it is into the mold.

Furthermore, another method is to use a jig with various smooth-surfaced pins and place the tube in the appropriate position.
Another method was to wrap the catheter around a pin and use the lateral curvature of the pin to shape the catheter into the desired shape.

[Problems to be solved by the invention] However, all of these conventional shaping techniques lack accuracy, are unable to form delicate shapes, are too time-consuming, and are expensive. It had drawbacks such as being too thick.

That is, the above method for forming a rubber hose has the disadvantage that when a large number of hoses are formed, the shape memory alloy becomes stale and cannot be formed into an accurate shape.

This drawback is a negative property of the shape memory alloy itself, and this tendency is noticeable in two-way shape memory alloys, and the shape of both the high temperature side and the low temperature side cannot be set accurately. was considered to be particularly impractical in fields where delicate and complex shapes are required.

In addition, forming technology that utilizes stainless steel or other metal wires that have been previously formed into a desired shape can obtain a good shape if the number of repeated uses is extremely small, but as the number of times the wire is used increases, the stainless steel or other metal When the wire is pulled out of the tube/catheter, the shape of the metal wire is distorted, and as a result, the desired shape cannot be obtained. Furthermore, once the shape of the metal wire is lost, it takes a lot of effort to delicately repair it. Furthermore, if the material of the metal wire is a hard wire that is less deformed, there is a drawback that the above-mentioned repair becomes even more difficult.

In addition, the method of forming using a metal mold, wooden mold, or plastic mold processed into the desired shape requires a large and bulky forming mold compared to the case of forming using a metal wire. However, it is not possible to form delicate and complicated shapes, and the manufacturing cost is high.

Furthermore, in the method of shaping using jigs with various pins, the shape often changes depending on the skill level of the worker, and the number of workers must be limited. Even for the workers, shaping was a major constraint in that it required a considerable amount of time and effort.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a method that can stably shape a material into an accurate shape even when a large amount of material is formed.

Particularly precise, such as medical tubes and catheters.
In addition, anyone can easily shape objects that require delicate and complex shapes, especially shapes such as tips, regardless of the skill level of the operator, the shaping time is quick, and the number of times of repeated use is The object is to provide a shaping method that can be used at least 50 to 100 times with good reproducibility.

[Means for Solving the Problems] The present invention employs the following means to achieve the above object.

That is, the tube shaping method of the present invention includes a step of shaping using a shape memory alloy wire (hereinafter simply referred to as SMA wire) that develops a shape memorized in advance at the temperature for shaping the thermoformable tube. After shaping the SM A wire by combining the steps of constraining the relative positions of at least two points, cooling the SM A wire to a temperature lower than the shaping temperature, and then drawing out the SM A wire. This is a characteristic feature.

(Function) The thermoformable tube in the present invention is a normal hollow tube made of natural rubber, synthetic rubber, plastic, etc.
It refers to something that can be deformed and is not limited by length, thickness, wall thickness, etc., but the present invention is particularly suitable for shaping complex and delicate shapes such as medical tubes and catheters. .

The gold used in the SMA wire according to the present invention is as follows:
For example, a Ni-Ti alloy, a Cu-based SMA such as Cu-Al5Cu-Zn, or the like can be used.

The SMA wire made of such a metal may exhibit a pre-memorized shape at the forming temperature of the heat-formable tube; for example, a unidirectional SMA wire is sufficient; It may be a two-way SMA wire that also has a substantially linear memory at a temperature lower than the shaping temperature, preferably at room temperature. That is, the superiority or inferiority of a one-way SMA wire or a two-way SMA wire can be determined based on criteria such as which one is easier to obtain industrially, which one is cheaper, and which one is more advantageous in terms of the number of times of repeated use.

On the other hand, in the case of the unidirectional SMA wire, when it is shaped into a desired shape at the shaping temperature and then cooled to a temperature lower than the shaping temperature, for example, room temperature, the shape of the unidirectional SMA wire is usually
The SMA wire is slightly deformed back in the direction in which the memory strain is alleviated. The amount of return deformation at this time tends to increase as the amount of distortion of the original desired shape increases.

This amount of return deformation becomes a major hindrance when performing a large-scale shaping process, and as the number of shaping operations increases, accurate shaping cannot be expected.

The present invention uses a deformation suppressing jig to curve and restrain the SMA wire so that the return deformation assists the deformation in the deformation direction of the maximum deformation part during thermal shaping.
This was completed after discovering that it could suppress the return deformation.

In other words, when using an SMA wire with the maximum amount of deformation that curves to the right, the shaped shape will be a right-curved shape, so the S
After attaching the MA wire to the thermoformable tube, in advance, bend it to the right [
Return deformation can be controlled by restraining it in the form of tj. This constraint constrains the curvature of the SMA line, but does not necessarily fix the movement of the SMA line;
The constraint point may be freely slid in accordance with the deformation of the MA line into the memorized shape.

As such a restraining means, a jig with a simple structure such as an appropriate hook or clip can be used, but of course S
A desired jig can be used depending on the deformed shape of the MA wire.

Such a jig may be used, for example, by attaching a non-shape-memory metal wire (ordinary metal wire) to the tip of an SMA wire and hooking the metal wire as described above, or by making it into a slidable shape. It can be transformed and made.

The tube shaping method of the present invention is particularly suitable for medical tubes and
It is extremely suitable for things that require complex and delicate shapes, such as catheters.

As the SMA wire for forming such tubes and catheters, unidirectional SMA wire has a weak force for holding the shape at a temperature lower than the temperature at which the memorized shape is formed (forming temperature), and therefore it is not sufficient to use a simple jig. This is preferable because it can prevent return deformation.

'' As described above, the present invention includes a step of forming a heat-formable tube using an SMA wire that develops a pre-memorized shape at the forming temperature, and Shaping is performed by combining processes that restrict the position.
After passing through the step of restraining the SMA wire, it is preferable to pass through the step of shaping at the shaping temperature in order to appropriately prevent return deformation.

Here, the relative positions of the two points refer to appropriate positions sandwiching the shaped portion, and do not refer to particularly restricted positions.

[Operations] The method for manufacturing the medical tube/catheter of the present invention will be explained with reference to Examples.

Figure 1 shows the state (longitudinal cross section) at room temperature when using a unidirectional SMA wire ↓.The SMA wire 1 is stretched by hand into a substantially straight line, and then the SMA wire 1 is used for medical purposes. Insert into the lumen of the tube/catheter 2.

FIG. 2 shows the state in which the SMA wire-containing tube/catheter is maintained at its shaping temperature in a heating tank (chamber) (not shown), and the SMA wire 1 is As soon as the shaping temperature is reached, the tube/catheter is immediately deformed into a pre-memorized shape, and therefore the tube/catheter is also deformed into a desired shape corresponding to the deformed shape on the SMA line.

The heating tank (chamber) is a steam atmosphere of 100'C or more than 100°C, a wet atmosphere such as a hot water tank of more than 90°C, or a dry atmosphere such as electric heating, and the material of the tube/catheter used is used. The temperature and heating method are selected accordingly.

Next, with the SMA wire still inserted, the tube/catheter is cooled and maintained at a temperature lower than the forming temperature, preferably room temperature, and then the SMA wire is pulled out to form the desired shape into the tube/catheter. It is possible to shape the shape of.

Heating at the above-mentioned shaping temperature, holding time, heating, cooling after holding, and holding time depend on the material of the tube/catheter used (
(for example, nylon, polyethylene, PVC, PU, silicone rubber, etc.), and should be determined experimentally. Usually, 0.5 minutes/line to 7-8 minutes/line is sufficient for both.

Figure 4 shows a jig, etc. that prevents the desired shaping shape from returning to its original shape when it is cooled to room temperature as described above, when a unidirectional SMA wire is used. The straight portion of the catheter 2 is grasped and fixed. In addition, a stainless steel wire whose tip 5 has a circular shape by welding or caulking with another protection tube tip is connected to one tip of the I-direction SMA wire 1, and the circular tip 5 is fixed by 4. It is fitted into a pin and fixed to prevent the return deformation. In addition, the mechanism that prevents this return deformation is the fourth
In addition to diagrams, you can make some simple things. One way is to extend the stainless steel wire 5 and apply appropriate bending processing to make a hook and hang it on the tube/catheter near the position 3, as shown in Figure 4. There is no need to provide another fixed location.

(Illustrated in Figure 5) [Effects of the Invention] Since SMA wires that have been memorized into the desired shape are used, first of all, an experienced worker is required to shape the tips of medical tubes and catheters. No need for it and anyone can do it easily. In particular, when it comes to complex two-dimensional or three-dimensional shapes, it takes even a skilled worker several minutes to more than 10 minutes per piece, but it has nothing to do with whether the shape is simple or complex. The imprinting process can be completed within a certain short period of time.

Therefore, in the case of the above-mentioned complicated shaped shapes, productivity has been extremely low until now, but by adopting the manufacturing method of the present invention, productivity not only improves significantly, but also improves productivity over time. Sex never declines. In other words, a significant reduction in shaping processing costs can be expected.

Next, the SMA wire can be used repeatedly, and
It should be able to withstand repetitions of 1000 times or more. Therefore, even if the SMA wire is purchased and used, its depreciation will not be a large burden.

[Brief explanation of the drawing]

Figure 1 is a partial cross-sectional view in the longitudinal direction of a shape memory alloy wire (described as a one-way shape memory alloy wire) inserted into a medical tube/catheter at room temperature. Figure 2 is a partial cross-sectional view in the longitudinal direction (the shape memory alloy wire is not shown in cross-section) showing the condition when the medical tube/catheter is heated to its forming temperature from the state shown in Figure 1. be. FIG. 3 shows a cross section taken along the line AA' in FIG. Figure 4.5 shows a medical tube/catheter in which a one-way shape memory alloy wire is used, and the medical tube/catheter into which the shape memory alloy wire is inserted is heated to its shaping temperature, held, and then cooled to room temperature. , is a diagram showing a fixing jig for preventing the above-mentioned return deformation. 1... Shape memory alloy wire 2... Medical tube/catheter 3... Tube/catheter gripping jig 4 such as a clip
... Fixing pin 5 ... Stainless steel wire 6 ... Protection tube tip

Claims (5)

[Claims] (1) Shaping using a shape memory alloy wire that develops a shape memorized in advance at the temperature at which the thermoformable tube is shaped, and restraining the relative positions of at least two points of the shape memory alloy wire. A method for shaping a tube, which comprises shaping the wire by combining steps, cooling the tube to a temperature lower than the shaping temperature, and then drawing the shape memory alloy wire. (2) The method for shaping a tube according to claim (1), wherein the step of shaping includes a step of inserting a shape memory alloy wire into the tube. (3) The method for shaping a tube according to claim (1), wherein the shape memory alloy wire has a non-shape memory metal wire portion at the tip of the shape memory portion. (4) The method for forming a tube according to claim (3), wherein the non-shape memory metal wire has a fixing mechanism at its tip. (5) The method for shaping a tube according to claim (1), wherein the tube is a medical tube/catheter.