JP2520126B2 - Method for forming the tip of the indwelling needle - Google Patents

Description

The present invention relates to a method for forming the tip of an indwelling needle outer needle. More specifically, it is composed of an inner needle consisting of a stainless steel cannula and a hub, and an outer needle consisting of a thermoplastic resin cannula and a hub, and is placed inside a vein to secure an infusion port for infusion therapy or blood transfusion treatment. The present invention relates to a method for forming a distal end portion of an indwelling needle outer needle that is indwelled in a vein of an indwelling needle for indwelling and using an outer needle or inserting a catheter through the indwelling outer needle.

<Prior Art> An indwelling needle is generally composed of an outer needle having a cannula made of a thermoplastic resin and an inner needle made of a stainless steel cannula and a hub. The outer needle has a hub and has no hub. There are things. The present invention provides a method suitable for forming a tip portion of an indwelling needle outer needle having a hub.
A method of injection molding the whole (JP-A-53-1984, JP-A-59-90564, JP-A-60-220070, and JP-A-6-62).
No. 0-241451), a method of grinding the tip (Japanese Patent Publication No. 52)
-37310, Japanese Patent Publication No. 53-43756, Japanese Patent Publication No. 54-30
231), and a method of cutting the tip after heating and stretching the tube (JP-B-49-5433, JP-A-53-153062, JP-A-57-2935, JP-B-61-24024). )
Etc. are known. The conventional technique will be briefly described below.

First, regarding the method of injection molding the whole, the invention of JP-A-53-1984 discloses that the mandrel of the metal mold is inserted into the catheter molding cavity provided in the female mold, and the tip of this mandrel is inserted. It is characterized in that it is held and fixed by a holding body and the resin is press-fitted into the void portion, and is intended for mass production.
The invention of JP-A-59-90564 is directed to an injection molding die,
Through the ring gate directly connected to the needle base, inject the melt-processable fluorine-containing resin heated above the melting point,
It is characterized in that the taper portion and the tube needle portion are made to flow in this order and then cooled and solidified below the melting point, and the purpose is to simplify the process. Further, the invention of JP-A-60-22070 discloses that the inner die of an indwelling needle is coaxially inserted into a synthetic resin extruded in a molten state, and the resin is molded by this inner die.
This molding resin is characterized in that it is cut at a predetermined position to enable continuous and efficient production.
The invention of -241451 gazette is characterized by heating the indwelling needle tip part molding die, injection molding the molten synthetic resin, and then cooling and solidifying it, thereby reducing the wall thickness as much as possible and improving the production efficiency. It is intended.

For the method of grinding the tip, refer to Japanese Examined Patent Publication No. 52-37310.
The invention of JP-B No. 53-43756 is characterized by polishing with a plastic tube and a material of the same quality as that of the tube, and is intended to prevent rising. The outer needle having an inner diameter smaller than the outer diameter is heated and softened, and the opening jig is inserted into the outer needle being heated and softened, and the outer needle is cooled while the opening jig is inserted in the outer needle. The feature is that after the cooling, the opening jig is extracted, and after the extraction, the tip of the outer needle is sharpened, and the adhesion between the outer needle and the inner needle is improved. In addition, Japanese Examined Japanese Patent Publication Sho 54-30231
In the invention of Japanese Patent Publication, after inserting the inner needle into the outer needle, the appropriate portion of the outer needle is softened by heating, and the outer needle is wrung until the inner circumference of the outer needle is in close contact with the outer circumference of the inner needle, and then the inner needle is not pulled out. The outer needle is cut at an appropriate position in this state, and the cut surface is sharpened.The purpose is to prevent the outer needle from curling up and the poor adhesion between the outer needle and the inner needle. To do.

Next, regarding the method of cutting the tip after heating and stretching the tube, the invention of Japanese Patent Publication No. 495433 is fitted with a synthetic resin pipe on a core member having the same diameter as the metal cannula, and in that state. The invention is disclosed in Japanese Patent Application Laid-Open No. 53-153062, which is characterized in that heat is applied while appropriately rotating to heat the synthetic resin pipe appropriately, and that the adhesion with a metal cannula is improved. The present invention is characterized in that a raw material tube is fitted to a guide member, and the central portion of the raw material tube is heated and softened in an annular shape and stretched, so that the raw material tube is stretched to a uniform wall thickness.

The invention of JP-A-57-29365 discloses that the preformed tube is fitted to a molded core rod having the same outer diameter as the outer diameter of the injection cannula, and the both are coaxially rotated while the preformed tube is being rotated. While locally heating the positions corresponding to both the cut ends of the preform, the other end of the preformed tube is stretched in the axial direction, and then the stretched heating part is cooled to be cut into a predetermined length. The purpose of the invention is to provide an indwelling needle that is smooth without steps and has good adhesion to an injection cannula.
A cored bar is inserted into a plastic tube, and while the tube is being rotated, the central part of the tube is heated and drawn to form a second taper part having a relatively small angle with respect to the axis of the tube in the heated part. 2 A heated round bar is pressed around the minimum diameter portion of the tapered portion to form a curved groove around the tube, and then the tube is cut in the curved groove to form the first tapered portion. Characteristic,
It is intended to provide an indwelling needle having a sharp tip shape and a constant quality.

<Problems to be Solved by the Invention> However, the method of injection-molding the whole is long in molding time, it is difficult to manufacture a thin indwelling needle outer needle, the tip is easily scratched, and the alignment is difficult to automate. Except when using a hot runner mold, the post-processing takes time and labor, the mold is expensive, the fitting strength of the inner needle and the outer needle varies when the thickness of the inner needle varies. There are drawbacks such as material loss and uneconomical.

In addition, the method of grinding the tip has a drawback that static electricity is generated by grinding and dust adheres to the tip of the cannula,
The method in which the tube is heated and stretched and then the tip is cut has the drawbacks that the tip size of the cannula varies greatly and the heating time is long.

The present invention has been completed as a result of intensive studies in view of the above problems, and there is little variation in the shape of the cannula tip,
An object of the present invention is to provide a method for manufacturing an indwelling needle outer needle in which the processing time is significantly shortened.

<Means for Solving Problems> That is, the present invention provides (a) an indwelling needle outer needle having a tip portion and a tube made of a thermoplastic resin, the tip of which is not formed, and a tube of the outer needle. Then, a cored bar having an outer diameter smaller than the inner diameter of the tube is inserted to a position retracted from the tip of the tube by a predetermined length. (A) While holding the core metal so that it does not move inside the tube, heat the tube in which the core metal is inserted to a predetermined temperature that has a hole diameter larger than the core metal outer diameter and smaller than the tube outer diameter. The tube is inserted into the formed mold until the tube is supported, and then the cored bar is pushed to a predetermined position of the mold. (C)
After heating the tube for a predetermined time to soften it, the core metal is further pushed in while holding the needle base of the outer needle, and the tip of the core metal is projected by several mm from the cavity of the mold. (D) Pull out the tube in which the core metal is inserted from the mold.
(E) After cooling, pull out the core metal from the tube. (F) Cut the tip of the tube at a predetermined position. The present invention relates to a method for forming a tip portion of an indwelling needle outer needle, comprising:

<Example> Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a view showing the relationship between an indwelling needle outer needle according to the present invention and a core metal and a mold, and FIGS. 2 and 3 are steps (a) of the tip forming method of the indwelling needle outer needle according to the present invention, respectively. It is a figure for demonstrating and a process (c).

As shown in FIGS. 1 to 3, the tip portion of the indwelling needle outer needle according to the present invention is not formed by forming the tip portion composed of the needle base (2) and the thermoplastic resin tube (3). The indwelling needle outer needle (1) is provided with a cored bar (4) to be inserted into the tube (3) of the outer needle (1) and a heater block (6). This is done by using the mold (5).

That is, first, (a) prepare an indwelling needle outer needle (1) having a tip portion not formed as shown in FIG. 1, and insert a tube (3) with a core having an outer diameter smaller than the inner diameter of the tube (3). Insert the gold (4) from the tip of the tube (3) to a position retracted for a predetermined length. Next, (a) for example, in a state where the needle base (2) and the cored bar (4) are coaxially fixed so that the cored bar (4) does not move inside the tube (3), The inserted tube (3) is placed in a mold (5) which is heated to a predetermined temperature and has a hole diameter larger than the outer diameter of the cored bar (4) and smaller than the outer diameter of the tube (3). ) Until it becomes a supporting state, and then the cored bar (4) is pushed to a predetermined position of the mold (5) as shown in FIG. (C) After heating the tube (3) for a predetermined time to soften it, as shown in FIG.
While holding the needle base (2) of the outer needle (1), the cored bar (4) is further pushed in, and the tip of the cored bar (4) is projected from the cavity of the mold by several mm. Then, (d) the tube (3) having the cored bar (4) inserted therein is pulled out from the mold (5), and (e) the tube (3) is cooled and then the cored bar (4) inserted from the tube (3) is inserted. ) Is pulled out, and the tip of the (3) tube (3) is finally cut at a predetermined position.

Here, the mold (5) used for forming the tip of the indwelling needle outer needle (1) is preferably such that the cavity of the mold (5) is the first.
As shown in the figure, the tube insertion opening (7) having a diameter sufficiently larger than the outer diameter of the tube (3) is followed by a first hole having a larger diameter than the outer diameter of the tube (3) which is reduced in diameter with a relatively large taper. A tapered portion (8), a second tapered portion (9) that reduces the diameter with a gentle taper following the first tapered portion (8), and a tubular shape with the same diameter that follows the second tapered portion (9), The straight part (10) having a hole diameter smaller than the outer diameter of the tube (3) and larger than the outer diameter of the cored bar (4) is included, and the outer diameter (Dt) and the single wall thickness (Dt) of the tube (3) ( t), outer diameter (Dm) of cored bar (4), straight section (1
The hole diameter (Dc) of 0) is preferably the following (I) to (I)
It satisfies the formula II).

0.06 ≤ Dc-Dm ≤ 0.2 (I) 2t <Dt-Dm ≤ 3t ...... (II) t ≤ Dt-Dc ≤ 2t ...... (III) (However, the units of Dt, Dm, Dc and t are mm Next, the method for forming the tip of the indwelling needle outer needle according to the present invention will be described in more detail.

The tube (3) constituting the indwelling needle outer needle (1) is extruded using a thermoplastic resin such as polyethylene, polypropylene, tetrafluoroethylene, a fluorinated ethylene-propylene copolymer, an ethylene-tetrafluoroethylene copolymer or the like. It is molded, and its outer diameter and wall thickness are determined by the size of the indwelling needle and the material for forming the tube (3). The size of the cored bar (4) inserted into this tube (3) is also determined by the size of the indwelling needle, and the outer diameter of the cored bar (4) is the outer diameter of the stainless steel cannula that constitutes the indwelling needle inner needle. Slightly smaller. The insertion of the cored bar (4) into the tube (3) is automatically performed by using a dedicated machine (not shown), but the cored bar (4) generally has a tube ( It is inserted from the tip of 3) to a position retracted by 4 to 6 mm, preferably about 5 mm.

The mold (5) has a first taper portion (8), a second taper portion (9) and a straight portion (10) as shown in FIG.
The first taper portion (8) has a hole diameter larger than the outer diameter of the tube (3), and the tube insertion port (7) of the first taper portion (8) inserts the tube (3). It is formed with a diameter sufficiently larger than that of the tube (3) so that it can be easily performed. And the first taper part (8)
The taper is not particularly limited, but is generally formed at about 30 ° to 60 °.

The second taper portion (9) is a portion that determines the tip shape of the indwelling needle outer needle (1), is reduced in diameter with a small taper continuously with the first taper portion (8), and is continuous with the straight portion (10). To do. The hole diameter of the second tapered portion (9) is larger than the outer diameter of the tube (3) at the contact point with the first tapered portion (8),
Moreover, the contact point with the straight portion (10) is smaller than the outer diameter of the tube (3), and the taper is preferably 4
It is formed at ゜ ~ 15 ゜. If the taper is 15 ° or more, the piercing resistance of the formed indwelling needle outer needle will be large, and if this is pierced into a patient's vein, etc., it will cause pain to the patient. If it is less than °, the taper is too long, and therefore the contact portion between the inner needle and the outer needle of the indwelling needle becomes too long, and the fitting between the inner needle and the outer needle is too strong, making it difficult to operate. If the portion is made longer, the wall thickness naturally becomes smaller, and the indwelling needle outer needle may be rolled up during piercing, which is not preferable.

The hole diameter of the straight portion (10) is smaller than the outer diameter of the tube (3) and larger than the outer diameter of the cored bar (4).
The length of the straight part (10) is determined by the size of the indwelling needle.

Next, in the step (a), the tube (3) having the cored bar (4) inserted therein is placed in the step (a) until the tube (3) can be used by the mold (5) heated to a predetermined temperature in advance. The point is that the core metal (4) is pushed into a predetermined position of the mold (5), and then the tube (3) is inserted until it is supported by the mold, and then the tube (3) is further inserted. 3) and the cored bar (4) are not pushed at the same time, because the cored bar (4) further enters the mold (5), but the tube (3) into the mold (5). Entry is insufficient and therefore the tube (3)
This is because a bent portion occurs at the end and causes defective molding. It is preferable to push the cored bar (4) into the mold (5) until the tip of the cored bar (4) enters the straight part (10) by 0 to 2 mm. Insufficient penetration of the core metal (4)
This is because if the tip of the tube is located at the second taper portion, the heating portion of the tube (3) may be insufficient and molding failure may occur, and the core metal (4) may enter too much and the straight portion ( If it goes into 10) by more than 2 mm, the tip of the cored bar (4) may come out of the tube (3), and as a result, the next step (C) cannot be performed and molding defects will occur. It may happen.

The temperature of the mold (5) varies depending on the material for forming the tube (3), but it is set to a temperature slightly higher than the softening temperature of the resin. For example, when the material is polyethylene, the temperature is 95%.
~ 105 ° C, preferably 100 ± 1 ° C, in the case of polypropylene 105-115 ° C, preferably 110 ± 1 ° C, in the case of ethylene-tetrafluoroethylene copolymer 200-2
It is 20 ° C, preferably 210 ± 2 ° C.

Next, after heating the tube (3) inserted in the mold (5) in the step (c) for a predetermined time to soften it, the cored bar (4) is further pushed in, and the tip of the cored bar (4) is molded into the mold. Regarding the point of protruding a few mm from the cavity of (5), the heating time of the tube (3) depends on the material for forming the tube, and the temperature of the mold (5) is set to a predetermined temperature, for example, the tube. When the forming material of (3) is polyethylene, it is about 0.5 seconds, when it is polypropylene, it is about 0.5 seconds, and when it is ethylene-tetrafluoroethylene, it is about 0.7 seconds. Further, the protrusion length of the core metal (4) from the cavity (protrusion length from the straight portion (10) in FIG. 1) is preferably 2 to 4 mm. If the protrusion length is 2 mm or less, defective molding of the tip may occur, and the protrusion length
This is because the tube (3) may break if it exceeds 4 mm.

Next, the outer diameter (Dt) and single wall thickness (t) of the tube (3), the outer diameter (Dm) of the cored bar (4), and the hole diameter (D
Regarding the relationship of c), when the units of Dt, Dm, Dc, and t are millimeters, Dt, Dm, Dc, and t are 0.06 ≦ Dc−Dm ≦ 0.2 (I) 2t <Dt−Dm ≦ 3t (II) 0.5t ≦ Dt−Dc ≦ t (III) It is preferable to satisfy the relationship.

In the formula (I), when Dc-Dm is larger than 0.2, the piercing resistance of the indwelling needle outer needle is large, and when Dc-Dm is smaller than 0.06, the tube (3) is cut, or even if molding is possible, the piercing is performed. Sometimes the outer needle rolls up, which is a problem.

In the formula (II), when Dt-Dm is larger than 3t, the outer diameter of the tube (3) is excessively reduced, which tends to cause defective molding. Further, in order to avoid this defective molding, the heating time may be lengthened, but this is uneconomical. When Dt-Dm is 2t or less, the cored bar (4) does not slide smoothly in the tube (3), so that the non-molded part of the tube (3) extends and the tube (3) in the mold (5) The length of 3) goes wrong.

In the formula (III), when Dt-Dc is larger than 2t, the outer diameter and the wall thickness of the tube (3) are excessively reduced, which easily causes defective molding. Further, in order to avoid this defective molding, the heating time may be lengthened, but this is uneconomical.

If Dt-Dc is smaller than t, the thickness of the tube (3) cannot be sufficiently reduced and the tip cannot be thinned.

<Example 1> Polypropylene (K-101 manufactured by Chisso Petrochemical Co., Ltd.)
1) The indwelling outer needle was manufactured by the method according to the present invention and the conventional heating and drawing method using the tube manufactured in 1), and the defective rate by size and the time required for one cycle of manufacturing were compared. The results shown in Tables and Table 2 were obtained.

However, as the heat drawing method, a cannula forming tube with a taper jig inserted is inserted into the heater block space (hole diameter 3 to 4 mm) to soften by heating, and then the upper portion of the tube is fixed with a fixture. The tube and the taper jig are lowered at the same time while being supported and fixed, and the tube is stretched (falling distance 10
(0 to 200 mm, descending speed 20 to 30 mm / sec) was adopted, and the defective rate was judged by the appearance and the length of the contact portion between the outer needle and the inner needle.
The standard of the close contact part is 7 ± 0.5m when the size is 12G to 20G.
In case of m and 22G, it is set to 4 ± 0.5 mm.

It can be seen that the defect rate is significantly reduced and the manufacturing cycle is significantly shortened as compared with the conventional heat stretching method.

<Effects of the Invention> As is apparent from what has been described above, the use of the method for forming the distal end portion of the indwelling needle outer needle according to the present invention makes it possible to reduce the variation in the shape of the cannula distal end and to significantly shorten the processing time. The indwelling needle outer needle having a sharp tip shape and good adhesion to the inner needle and stable quality can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between an indwelling needle outer needle according to the present invention and a core metal and a mold, and FIGS. 2 and 3 are steps (a) of a method for forming a distal end portion of the indwelling needle outer needle according to the present invention, respectively. It is an explanatory view of and a process (c). <Explanation of main symbols> 1: Indwelling needle outer needle, 2: Needle base 3: Tube, 4: Wire 5: Mold, 6: Heater block 8: 1st taper part, 9: 2nd taper part 10: Straight Department

Claims (3)

(57) [Claims] 1. (a) An indwelling needle outer needle having a tip portion not formed and comprising a needle base and a tube made of a thermoplastic resin is prepared,
A cored bar having an outer diameter smaller than the inner diameter of the tube is inserted into the tube of the outer needle up to a position retracted by a predetermined length from the tip of the tube. (B) While holding the core metal so that it does not move inside the tube, heat the tube in which the core metal is inserted to a predetermined temperature that has a hole diameter larger than the core metal outer diameter and smaller than the tube outer diameter. The tube is inserted into the formed mold until the tube is supported, and then the cored bar is pushed to a predetermined position of the mold. (C) After heating the tube for a predetermined time to soften it, the core metal is further pushed in while holding the needle base of the outer needle, and the tip of the core metal is projected by several mm from the cavity of the mold. (D) Pull out the tube in which the core metal is inserted from the mold. (E) After cooling, pull out the core metal from the tube. (F) Cut the tip of the tube in place. The method for forming a tip portion of an indwelling needle outer needle, comprising: 2. A first taper portion having a hole diameter larger than the outer diameter of the tube, wherein the cavity of the mold is followed by a tube insertion opening having a diameter sufficiently larger than the outer diameter of the tube, and the diameter is reduced with a relatively large taper. A second taper portion that follows the first taper portion and has a gradual taper, and a tubular shape having the same diameter that follows the second taper portion and is smaller than the outer diameter of the tube and larger than the outer diameter of the cored bar. Claim 1 characterized in that it includes a straight portion having a hole diameter.
Item 5. A method for forming a tip portion of an indwelling needle outer needle according to item. 3. The outer diameter (Dt) of the tube and the wall thickness (t), the outer diameter (Dm) of the core metal, and the hole diameter (Dc) of the straight portion of the mold are as follows (I) to (III). ) Formula: 0.06 ≤ Dc-Dm ≤ 0.2 (I) 2t <Dc-Dm ≤ 3t ...... (II) t ≤ Dt-Dc ≤ 2t ...... (III) (However, for Dt, Dm, Dc and t The unit is mm. The method for forming the tip of an indwelling needle outer needle according to claim 2, wherein the unit satisfies mm.