Method for producing medical hollow needle

Abstract

To provide a method for producing a medical hollow needle that allows the efficient passage of blood or other liquids.SOLUTION: A medical hollow needle 10 has an inner lumen 12 penetrating it in the direction of the needle axis. An inner circumferential surface 16 of a needle tube 14 constituting the circumferential wall of the inner lumen 12 has a tapered surface 30 with a diameter becoming smaller toward a needle tip 18 formed by deep drawing. The arithmetic mean roughness Ra of the inner circumferential surface 16 in the direction of the needle axis is set as Ra≤1.0 μm.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a medical hollow needle used, for example, in artificial dialysis. [Background technology]

[0002] Conventionally, medical hollow needles used for injections, infusions, etc. have been manufactured by rolling a medical metal plate into a cylindrical shape and performing a multi-stage drawing process. However, in this case, if the diameter of the hollow needle becomes small, it is not possible to insert an inner die into the inner circumference of the hollow needle, and the subsequent drawing process is performed without the inner die. In this case, wrinkles may occur on the inner circumference of the hollow needle, making the surface roughness of the inner circumference rough, which may hinder the smooth flow of liquid. On the other hand, there is also a technology for manufacturing hollow needles by rolling a very thin medical metal plate into a cylindrical shape and joining the ends (for example, JP 2003-200218 A (Patent Document 1)). In this case, since there is no need to perform a multi-stage drawing process, it is possible to prevent situations such as wrinkles on the inner circumference. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-200218 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a medical hollow needle is formed by rolling a plate material into a cylindrical shape, a joint portion is formed at the edge of the plate material in a part of the circumference of the medical hollow needle, and the surface roughness of the inner peripheral surface of the medical hollow needle becomes rough at the joint portion, which may cause resistance to the flow of liquid. In particular, in the case of a medical hollow needle through which liquid such as blood flows, the joint portion is welded to ensure liquid-tightness, so it is sometimes difficult to give the joint portion a smooth inner peripheral surface shape.

[0005] Furthermore, when a hollow needle is obtained by a multiple-stage drawing process, as mentioned above, wrinkles may occur on the inner surface, making the surface roughness of the inner surface rough, which may hinder the smooth flow of liquid.

[0006] An object of the present invention is to provide a novel method for manufacturing a medical hollow needle that allows liquids such as blood to flow efficiently. [Means for solving the problem]

[0007] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely illustrative and may be combined with one another as appropriate, and the multiple components described in each embodiment may be recognized and used independently as far as possible, and may also be combined with any of the components described in another embodiment as appropriate. As a result, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0008] The first aspect is a medical hollow needle having an inner cavity penetrating in the needle axial direction, in which the inner surface of the needle tube has a tapered surface that becomes smaller in diameter toward the needle tip formed by deep drawing, and the arithmetic mean roughness Ra of the inner surface in the needle axial direction is Ra≦1.0 μm.

[0009] In a medical hollow needle constructed according to this embodiment, the needle tube that constitutes the peripheral wall of the inner cavity is formed by deep drawing, so that the irregularities that constitute the surface roughness on the inner surface of the needle tube are reduced and pressure loss can be reduced, ensuring a large flow rate of fluid flowing through the inner cavity and, for example, reducing damage to blood cells when blood flows through the lumen.

[0010] In addition, the inner peripheral surface of the needle tube of the medical hollow needle has a tapered surface, but this tapered surface is formed by deep drawing, and the change in the inner diameter can be suppressed to a level that does not affect the flow of liquid in the lumen. Because the tapered surface becomes smaller toward the tip, the flow rate is stabilized, especially when liquid flows through the lumen toward the tip (needle tip side).

[0011] The arithmetic mean roughness Ra of the inner surface of the needle tube in the needle axis direction is 1.0 μm or less. The inner surface of the needle tube, which is the inner wall surface of the inner cavity, is a smooth surface with little unevenness. As a result, the flow of liquid in the inner cavity is less likely to become turbulent due to the surface roughness of the inner surface, which effectively stabilizes the flow rate and reduces damage to blood cells.

[0012] In a second aspect, in the medical hollow needle described in the first aspect, the inner diameter of the tip portion of the needle tube, which is on the needle tip side, is smaller than the inner diameter of the base portion opposite the needle tip, and the tip and base portions are connected by a stepped portion whose diameter becomes smaller toward the needle tip side, and the angle of inclination of the inner surface of the needle tube relative to the needle axis at the stepped portion is larger than the angle of inclination of the inner surface of the tip and base portions relative to the needle axis, and the tapered surface is formed by the inner surfaces of the tip and base portions.

[0013] In a medical hollow needle constructed according to this embodiment, the inner diameter of the tip portion is smaller than the inner diameter of the base portion, so that a large flow rate can be ensured in the inner cavity, for example, when liquid flows through the inner cavity from the base end side to the tip side (needle tip side).

[0014] The provision of a step connecting the tip and base ends allows for a large degree of freedom in setting the difference in inner diameter between the tip and base ends. In addition, the step becomes smaller in diameter toward the tip, making it difficult for the flow to be blocked by the step, realizing a smooth flow.

[0015] In a third aspect, in the medical hollow needle described in the first aspect, the inner surface of the needle tube is a tapered surface having a substantially constant angle of inclination relative to the needle axis over the entire length in the needle axis direction.

[0016] In a medical hollow needle constructed according to this embodiment, the inner surface of the needle tube is a tapered surface having a substantially constant inclination angle over the entire length of the needle axial direction, thereby more effectively stabilizing the flow rate and avoiding damage to blood cells.

[0017] In a fourth aspect, in the medical hollow needle described in any one of the first to third aspects, there is a molding mark on the inner surface of the needle tube which extends in the needle axial direction in a micrograph.

[0018] In the medical hollow needle according to this embodiment, in which molded marks extending in the needle axial direction are present on the inner circumferential surface in a micrograph, the surface roughness is suppressed by the molded inner circumferential surface of the needle tube, and the tips of the convex portions of the uneven surface roughness on the inner circumferential surface appear as if they had been crushed by a molding die such as a punch. Therefore, it is easy to achieve the effects of the present invention as described above by suppressing the arithmetic mean roughness Ra of the inner circumferential surface in the needle axial direction to Ra≦1.0 μm or less.

[0019] In a fifth aspect, in the medical hollow needle according to any one of the first to fourth aspects, the needle tube does not have a joint portion in the circumferential direction.

[0020] According to a medical hollow needle constructed in accordance with this embodiment, the needle tube has no joints in the circumferential direction, so it is possible to prevent the surface roughness of the inner surface from becoming locally large at the joints.

[0021] In a sixth aspect, in the medical hollow needle according to any one of the first to fifth aspects, the inclination angle of the tapered surface relative to the needle axis is greater than 0 degrees and equal to or less than 5 degrees.

[0022] In a medical hollow needle constructed according to this embodiment, the inclination angle of the tapered surface relative to the needle axis is greater than 0 degrees and not greater than 5 degrees, thereby ensuring the punching taper of the deep drawing inner die (punch) while setting a small rate of change of the inner diameter dimension in the needle axial direction, thereby suppressing the effect of the tapered surface on the flow of liquid in the inner cavity.

[0023] A seventh aspect is a method for manufacturing a medical hollow needle described in any one of the first to sixth aspects, comprising a press processing step of forming a bottomed tube by deep drawing a metal plate in multiple stages, and a needle tip forming step of cutting the tube at the bottom side of the deep drawing to form the needle tip.

[0024] According to the method for manufacturing a medical hollow needle according to this embodiment, a bottomed tube is formed by deep drawing a metal blank in multiple stages, thereby obtaining a needle tube with no joints in the circumferential direction. In addition, a tapered surface that expands toward the base end is set on the inner peripheral surface of the tube, which prevents the punch (inner die) that forms the inner peripheral surface of the tube from becoming stuck in the lumen of the tube. In addition, since the punch is inserted into the inner circumference of the tube and deep drawing is performed, the irregularities that constitute the surface roughness of the inner peripheral surface are reduced, and the sharp shape of the tip of the protrusion is smoothed out, thereby reducing the surface roughness of the inner peripheral surface.

[0025] In addition, the needle tip can be easily formed by cutting the bottom side of the bottomed tube obtained by deep drawing. It is also possible to form the lumen of the needle tube penetrating in the needle axial direction by cutting off the bottom part of the tube when forming the needle tip. Effect of the Invention

[0026] According to the present invention, it is possible to provide a medical hollow needle that allows efficient flow of liquid such as blood. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a plan view showing a medical hollow needle according to a first embodiment of the present invention; [Diagram 2] Cross-sectional view of Fig. 1 along line II-II [Diagram 3] FIG. 3 is an enlarged cross-sectional view of the medical hollow needle of FIG. 1, which corresponds to the cross section taken along the line III-III of FIG. 2. [Figure 4] A diagram explaining the manufacturing process of the medical hollow needle shown in FIG. [Diagram 5] Micrograph of the inner surface of the medical hollow needle shown in Figure 1 [Figure 6] Microscopic image of the inner surface of a conventional medical hollow needle [Figure 7] Graph of the center average roughness of the inner surface of the medical hollow needle shown in Figure 5 [Figure 8] Graph of the center average roughness of the inner surface of the medical hollow needle shown in Figure 6 [Figure 9] FIG. 1 is a longitudinal sectional view showing a medical hollow needle according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] 1 to 3 show a medical hollow needle 10 as a first embodiment of the present invention. The medical hollow needle 10 has an inner cavity 12 that penetrates in the axial direction, and is composed of a cylindrical needle tube 14 that forms the peripheral wall of the inner cavity 12. In the following explanation, the distal end side generally refers to the left side in FIG. 1, which is the side of a needle tip 18 described below, and the proximal end side generally refers to the right side in FIG. 1, which is the opposite side to the needle tip 18. Furthermore, the up-down direction generally refers to the up-down direction in FIG. 2.

[0030] The needle tube 14 has a small-diameter cylindrical shape overall, and does not have a joint in the circumferential direction, as shown in Fig. 3. That is, the needle tube 14 is not formed by rolling a sheet material into a cylindrical shape, and does not have a joint formed by both ends in the circumferential direction when rolling a sheet material into a cylindrical shape. Therefore, the needle tube 14 has a substantially uniform inner circumferential surface 16 over the entire circumference. Note that the needle tube 14 without a joint in the circumferential direction can be obtained, for example, by a multi-stage press process (deep drawing process) as described later.

[0031] As shown in Figs. 1 and 2, the needle tube 14 has a sharp needle tip 18 at one end in the needle axis direction (the length direction, i.e., the left-right direction in Fig. 1). The needle tip 18 is provided, for example, by cutting the end of the needle tube 14 into a shape inclined with respect to the needle axis α to form a blade surface 20. The blade surface 20 of this embodiment has different inclination angles with respect to the needle axis α at the tip side and the base end side, and the inclination angle is larger at the tip side. The inclination angle of the blade surface 20 with respect to the needle axis α is, for example, 15 degrees or more and 30 degrees or less at the tip side, and 10 degrees or more and 20 degrees or less at the base end side. However, the specific shape of the blade surface 20 is not limited, and may be, for example, constituted by a single plane, may be constituted by three or more planes, or may be constituted by one or more curved surfaces.

[0032] A through hole 22 is formed at the tip of the needle tube 14, penetrating in a direction perpendicular to the needle axis α. This ensures an efficient flow rate of liquid such as blood flowing into or out of the lumen 12 when, for example, the medical hollow needle 10 is inserted into a blood vessel. In this embodiment, the through hole 22 is elliptical with the needle axis direction as the longitudinal direction, and the opening area is ensured in a space-efficient manner, but the shape is not limited thereto. Furthermore, the through hole 22 is not essential and can be omitted.

[0033] The needle tube 14 is formed so that the wall thickness becomes smaller toward the tip. The needle tube 14 is also provided with a step portion 24 in the middle of the length direction, and the tip portion 26 located on the needle tip 18 side of the step portion 24 has a smaller diameter than the base portion 28 located on the opposite side of the needle tip 18 from the step portion 24. The step portion 24 is a fixing portion to a needle hub or the like (not shown), and is fixed to the needle hub or the like by adhesive, for example. The step portion 24 has a larger outer diameter than the tip portion 26, so that a large bonding area can be obtained. The difference in inner diameter between the tip portion 26 and the base portion 28 is desirably 0.6 mm or less. For example, the tip portion 26 has an inner diameter dimension (1.45 mm) equivalent to 16G, and the base portion 28 has an inner diameter dimension (1.90 mm) equivalent to 14G. The large inner diameter of the base portion 28 ensures a large flow rate of the lumen 12. The difference in outer diameter between the tip portion 26 and the base portion 28 is preferably 0.6 mm or less. For example, the tip portion 26 has an outer diameter (1.65 mm) equivalent to 16G, and the base portion 28 has an outer diameter (2.10 mm) equivalent to 14G. The small outer diameter of the tip portion 26 can reduce pain during puncture. The length of the tip portion 26 in the needle axis direction is appropriately set according to the puncture depth for each application of the needle, and it is desirable that the step portion 24 is at least long enough not to hit the patient's skin during puncture. In this embodiment, the length of the tip portion 26 in the needle axis direction is larger than the length of the base portion 28 in the needle axis direction, and is preferably 1.5 times or more. Considering that a blood vessel will be punctured, the length dimension in the needle axial direction of tip portion 26 is preferably 25 mm or more, and considering that base end portion 28 or stepped portion 24 will be the fixed portion to a needle hub (not shown), the length dimension in the needle axial direction from the tip of tip portion 26 to the base end of base end portion 28 (total length of medical hollow needle 10) is preferably 30 mm or more. Note that in this embodiment, stepped portion 24, which is part of medical hollow needle 10, is the fixed portion to the needle hub, but for example, a separate member can be joined to the base end side of the medical hollow needle according to the present invention and the separate member can be the fixed portion to the needle hub.In this case, since the medical hollow needle does not include a fixed part with the needle hub, the total length of the medical hollow needle may be less than 30 mm. The method of forming the separate member described above is not limited, and may be formed by, for example, deep drawing, or by rolling a plate material into a cylindrical shape and then thinning it by drawing.

[0034] The length of the stepped portion 24 in the needle axial direction is shorter than the length in the same direction of the tip portion 26 and the base portion 28. Note that the needle tube 14 may have a substantially constant tapered shape over the entire length from the tip to the base end, thereby eliminating the stepped portion 24.

[0035] The step-like portion 24 is tapered so that the diameter gradually decreases toward the needle tip 18 side, and the small-diameter tip portion 26 and the large-diameter base portion 28 are continuous via the step-like portion 24. The tip portion 26 and the base portion 28 are tapered so that the diameter gradually decreases toward the needle tip 18 side. The inner peripheral surface 16 of the needle tube 14 has a tapered surface 30 composed of the inner peripheral surfaces of the tip portion 26 and the base portion 28. The tapered surface 30 is formed by deep drawing, and is set as a punch taper of the inner mold when the needle tube 14 is formed by deep drawing, for example. The tapered surface 30 has a relative inclination angle θ with respect to the needle axis α that is greater than 0 degrees and less than 5 degrees, preferably less than 1 degree, and more preferably less than 0.7 degrees. The smaller the taper angle θ, the less the patient's skin is pushed open during puncture, and the less pain caused by puncture. The inclination angle θ of the tapered surface 30 may be set to an angle outside the above angle range, for example, an angle larger than 5 degrees. In this embodiment, the inclination angle of the inner peripheral surface of the stepped portion 24 with respect to the needle axis α is larger than the inclination angle θ of the tapered surface 30, for example, 15 degrees or more and 60 degrees or less, but may be set to an angle outside the angle range, for example, 15 degrees or less, taking into consideration ease of manufacture and the degree of turbulence. Note that FIG. 2 shows a partially enlarged view of a part of the needle tube 14, and in the enlarged view, a virtual line parallel to the needle axis α is shown by a dashed line to show the inclination angle θ of the tapered surface 30 constituting the inner peripheral surface 16 of the needle tube 14 with respect to the needle axis α, but in the enlarged view, the inclination angle θ of the tapered surface 30 with respect to the needle axis α is exaggerated and shown large for ease of viewing.

[0036] The inner peripheral surface 16 of the needle tube 14 has an arithmetic mean roughness Ra in the needle axis direction of 1.0 μm or less (Ra≦1.0 μm). More preferably, the arithmetic mean roughness Ra in the needle axis direction of the inner peripheral surface 16 is 0.7 μm or less (Ra≦0.7 μm), and the closer to 0, the more preferable. In short, the inner peripheral surface 16 of the needle tube 14 is a smooth surface with small irregularities. The outer peripheral surface of the needle tube 14 has an arithmetic mean roughness Ra in the needle axis direction of 1.0 μm or less (Ra≦1.0 μm), and more preferably, 0.7 μm or less (Ra≦0.7 μm). As is generally known, the arithmetic mean roughness Ra is calculated by taking the average value of the irregularities constituting the surface roughness as a reference line and calculating the average value of the distance of the irregularities from the reference line.

[0037] The medical hollow needle 10 having such a structure can be obtained by a manufacturing method including each step shown in Fig. 4. In Fig. 4, each step constituting the manufacturing method of the medical hollow needle 10 is shown in order from the top in the figure, and the manufacturing method of the medical hollow needle 10 includes (a) a blank plate preparation step, (b) a first press working step, (c) a second press working step, (d) a third press working step, (e) a fourth press working step, (f) a fifth press working step, (g) a flange cutting step, and (h) a needle tip forming step. Note that Fig. 4 is a diagram for explaining each step of the manufacturing method, and for example, the shapes and dimensions of the metal blank plate 14a, the first to sixth molded products 14b to 14g, and the needle tube 14 are not strictly accurate.

[0038] First, in a blank preparation step shown in Fig. 4(a), a blank metal plate 14a is prepared. The blank metal plate 14a is made of a medical metallic material such as medical stainless steel, and has a generally flat plate shape.

[0039] Next, a pressing process is carried out in which the prepared metal plate 14a is pressed using a punch 32, which is an inner die, and a die 34, which is an outer die. The pressing process is carried out stepwise over a number of times, and in this embodiment, five pressing processes, 1st to 5th, are carried out. The punches used in the first to fifth pressing processes are given the respective reference numerals 32b to 32f, and the dies used in the first to fifth pressing processes are given the respective reference numerals 34b to 34f. In addition, from the first pressing process carried out first to the fifth pressing process carried out last, the outer diameters of the punches 32b to 32f, which determine the inner diameters of the first to fifth molded products 14b to 14f, and the inner diameters of the dies 34b to 34f, which determine the outer diameters of the first to fifth molded products 14b to 14f, are gradually reduced.

[0040] Specifically, in the first press process (first press process in FIG. 4(b)), a flat metal blank 14a is deep-drawn with a punch 32b and a die 34b to obtain a first tubular product 14b with a large diameter and a small depth. The bottom 35 of the first product 14b is substantially disk-shaped, and the outer periphery is smoothly connected to the peripheral wall to form a curved cross-sectional shape. Furthermore, in the second press process in FIG. 4(c), a punch 32c and a die 34c are used to obtain a second product 14c with a smaller diameter and a larger depth than the first product 14b, and in the third press process in FIG. 4(d), a punch 32d and a die 34d are used to obtain a third product 14d with a smaller diameter and a larger depth than the second product 14c. Furthermore, in the fourth press process in Fig. 4(e), a punch 32e and a die 34e are used to obtain a fourth molded product 14e having a smaller diameter and a larger depth than the third molded product 14d, and in the final press process (the fifth press process in Fig. 4(f)), a punch 32f and a die 34f are used to obtain a fifth molded product 14f having a smaller diameter and a larger depth than the fourth molded product 14e. In this way, by gradually reducing the inner and outer diameters of the needle tube 14 and gradually increasing the length in the needle axial direction through the first to fifth press processes, it is possible to obtain the fifth molded product 14f as a tube that can be used as a medical hollow needle 10.

[0041] The fifth molded product 14f obtained at the completion of the fifth press working step has a generally bottomed tubular shape with the tip closed by a deep drawn bottom 35, and is integrally provided with a flange-like portion 36 expanding toward the base end on the base end side. In this embodiment, the step portion 24 is formed in the fifth press working step, which is a molding step of the fifth molded product 14f.

[0042] The first to fifth molded products 14b to 14f obtained in each press processing step have a tapered shape in which the peripheral wall portions expand in diameter toward the base end opening, and in particular, the inner peripheral surface, including the tapered surface 30, is an inclined surface that expands in diameter toward the base end opening over the entire surface, so that the punches 32b to 32f can be easily pulled out from the first to fifth molded products 14b to 14f toward the base end after molding.

[0043] 4(g), the flange-like portion 36 of the fifth molded product 14f is cut off to obtain a sixth molded product 14g as a pipe. The sixth molded product 14g from which the flange-like portion 36 has been cut off has a smaller maximum outer diameter than the fifth molded product 14f having the flange-like portion 36, so that the space required for transportation and storage can be reduced.

[0044] Next, in the needle tip forming step of Fig. 4(h), the sixth molded product 14g from which the flange-shaped portion 36 has been removed has its tip portion having a bottom 35 cut obliquely to form a needle tube 14 (medical hollow needle 10) having a blade surface 20 and needle tip 18 at its tip. Through the manufacturing steps as described above, the medical hollow needle 10 according to this embodiment can be manufactured. Note that in this embodiment, after completion of the needle tip forming step, a through hole 22 is formed in the tip portion of the needle tube 14. Also, the formation of the needle tip 18 by cutting the tip portion and the cutting of the flange-shaped portion 36 can be performed as a single step.

[0045] In this way, by forming the needle tube 14 by deep drawing the plate material (metal plate 14a) into a cylindrical shape through multiple stages, it is possible to obtain the needle tube 14 having a substantially uniform peripheral wall with no joints in the circumferential direction. Therefore, the surface roughness of the inner peripheral surface 16 of the needle tube 14, which is the peripheral wall surface of the lumen 12, does not become locally large at the joints.

[0046] The inner peripheral surface 16 of the needle tube 14 stretched by the first to fifth press working steps has an arithmetic mean roughness Ra in the needle axis direction of 1.0 μm or less (Ra≦1.0 μm), more preferably 0.7 μm or less (Ra≦0.7 μm), which is smaller than the surface roughness of a conventional needle tube made by rolling a plate material and reducing its diameter by pultrusion. Therefore, the flow resistance of liquid such as blood flowing through the lumen 12 is suppressed, and a stable and efficient flow rate can be obtained, while damage to blood cells can be reduced.

[0047] Moreover, the tips of the protrusions constituting the uneven surface roughness on the inner peripheral surface 16 of the needle tube 14 are flattened by contact with the punch 32 during multiple press processes, making the tips of the protrusions flat and reducing their sharpness. As a result, when liquid flows through the lumen 12 of the needle tube 14, resistance due to the fine unevenness on the inner peripheral surface 16 is reduced, and the liquid can flow efficiently.

[0048] The needle tube 14 formed by deep drawing has a tapered surface 30 inclined in a direction in which the inner peripheral surface 16 expands toward the base end so that the punches 32b-32f can be easily pulled out from the inner peripheral surfaces of the first to fifth molded products 14b-14f in the press working process. The inclination angle (taper angle) θ of the tapered surface 30 with respect to the needle axis α is set to be small, 5 degrees or less (preferably 1 degree or less, more preferably 0.7 degrees or less), so that the influence on the flow of liquid through the lumen 12 is substantially avoided.

[0049] In this embodiment, a stepped portion 24 is provided midway along the length of the needle tube 14, and the inner diameter of a tip portion 26 located on the tip side of the stepped portion 24 is made smaller than the inner diameter of a base portion 28 located on the base side. This ensures a large flow rate, for example, when a liquid flows from the base end side to the tip side of the medical hollow needle 10. Moreover, by making the tip portion 26, which is the part that is inserted into the patient, smaller in diameter than the base portion 28 in the medical hollow needle 10, pain during insertion can also be reduced.

[0050] The needle gauge G, which indicates the thickness of the medical hollow needle 10, is set, for example, by the average value of the thickness (outer diameter and inner diameter) of the tip portion 26, which is the part that is inserted into the patient. The base end portion 28 may be exposed to the outside, or may be inserted, for example, into a needle hub or a syringe cylinder (not shown), or may be a part that is fixed to a needle hub or the like. Preferably, the tip portion 26 is the part that is exposed from the needle hub, syringe, adhesive for fixing thereto, etc., and the axial length of the tip portion 26 is the effective length of the medical hollow needle 10.

[0051] Since the tip portion 26 and the base portion 28, which have different inner diameters, are connected via the stepped portion 24, the inner diameters of the tip portion 26 and the base portion 28 can be set with a large degree of freedom. Therefore, for example, it is possible to make the tip portion 26, which is inserted into the patient, sufficiently small in diameter to suppress pain when the needle is inserted, while making the base portion 28 sufficiently large in diameter to ensure the flow rate of liquid in the lumen 12. Moreover, the stepped portion 24 is tapered so that the diameter becomes smaller toward the tip, and a sudden change in the cross section at the stepped portion 24 is prevented, thereby reducing adverse effects on the flow of liquid flowing through the lumen 12.

[0052] The medical hollow needle 10 is preferably used, for example, in the blood return port or blood removal port of an artificial dialysis circuit, or the administration port which is the patient end of an infusion circuit. In particular, the medical hollow needle 10 is preferably applied to the puncture portion of an artificial dialysis circuit or a blood transfusion circuit through which blood flows. Specifically, for example, the medical hollow needle 10 can be preferably used as a needle for artificial dialysis. This allows smooth liquid flow, making it difficult for damage to blood cells or entrapment of air bubbles to occur during artificial dialysis or infusion (including blood transfusion), and allows for minimally invasive dialysis or infusion.

[0053] The micrographs shown in Figs. 5 and 6 also confirm that the inner peripheral surface 16 of the medical hollow needle 10 according to the present invention is a smooth surface with a smaller surface roughness than the inner peripheral surface of a conventional medical hollow needle. Fig. 5 is a micrograph of the inner peripheral surface 16 of the medical hollow needle 10 according to the present invention, and Fig. 6 is a micrograph of the inner peripheral surface of a conventional medical hollow needle. In Figs. 5 and 6, the up-down direction in the figures is the needle axial direction, and the left-right direction in the figures is the circumferential direction. The conventional medical hollow needle shown in Fig. 6 was formed by a conventional manufacturing method in which a flat plate material is rolled into a cylindrical shape, both ends that are butted together in the circumferential direction are joined by welding, and then the needle is thinned to a predetermined thickness by a multiple-stage drawing process. The micrographs in Figs. 5 and 6 were taken using an OLS4100 laser microscope manufactured by Olympus Corporation, with an objective lens of 20x and an observation magnification of 432x.

[0054] In the micrograph of Fig. 5, there is a molding mark extending in the needle axis direction on the inner peripheral surface 16 of the medical hollow needle 10. Such molding marks on the inner peripheral surface 16 are formed when the punches 32b-32f are inserted into or removed from the inner circumference of the first to fifth molded products 14b-14f in the needle axis direction in the press working process, and the convex parts constituting the surface roughness of each of the inner peripheral surfaces of the first to fifth molded products 14b-14f are crushed or scraped by the abutment of the punches 32b-32f. Therefore, the molding mark on the inner peripheral surface 16 of the needle tube 14 can be confirmed in the micrograph by the fact that the convex parts constituting the surface roughness of the inner peripheral surface 16 of the needle tube 14 are elongated and extend in the needle axis direction, and the tips of the convex parts are flat with a small degree of sharpness. On the other hand, in the micrograph of FIG. 6, which shows a needle tube pultrusion-molded without using an inner die (plug), no clear molding marks are observed, and the tips of the convex parts that constitute the surface roughness are sharp-pointed and have a spot-like shape (dot-like) without extending in the needle axial direction.

[0055] Comparing Figures 5 and 6, due to these differences in molding marks, in Figure 5 the tips of the convex parts protruding towards the inner circumference that constitute the surface roughness are planar, whereas in Figure 6 the tips of the convex parts are sharply shaped. Due to these differences in the shape of the inner circumference surface, it is believed that medical hollow needle 10 according to the present invention can achieve a smoother flow of liquid than conventional medical hollow needles.

[0056] In addition, when the micrographs in Figs. 5 and 6 were taken, the surface roughness of the inner circumferential surface was also measured using a laser, and the measurement results of the surface roughness (magnitude of unevenness) of the inner circumferential surface are shown in Figs. 7 and 8. Fig. 7 shows the measurement results of unevenness of the inner circumferential surface 16 of the medical hollow needle 10 according to the present invention, and Fig. 8 shows the measurement results of unevenness of the inner circumferential surface of a conventional medical hollow needle. The graphs in Figs. 7 and 8 show the line roughness in the needle axial direction, and in the graphs in Figs. 7 and 8, the horizontal axis is the position in the needle axial direction of the medical hollow needle, and the vertical axis is the height dimension from the reference position to the inner circumferential surface of the medical hollow needle. Therefore, in the graphs in Figs. 7 and 8, the smaller the fluctuation range in the vertical axis direction in the horizontal axis direction, the smaller the unevenness of the inner circumferential surface of the medical hollow needle is and the smoother it is.

[0057] Comparing Figures 7 and 8, the graph of measurement results shown in Figure 7 has a smaller fluctuation range in the vertical axis direction compared to the graph of measurement results shown in Figure 8, and therefore it was confirmed by actual measurement that inner circumferential surface 16 of medical hollow needle 10 according to the present invention is smoother and has fewer projections and recesses than the inner circumferential surface of a conventional medical hollow needle. It was confirmed that the needle tube shown in Figure 5 has approximately the same good surface roughness in the circumferential direction as in the needle axial direction.

[0058] 9 shows a medical hollow needle 40 as a second embodiment of the present invention. In the following description, the same members and parts as those in the first embodiment are denoted by the same reference numerals in the drawings, and description thereof will be omitted.

[0059] Compared to the medical hollow needle 10 of the first embodiment, the medical hollow needle 40 does not have a stepped portion 24, the entire inner circumferential surface 16 is a tapered surface 30, and the inclination angle θ of the inner circumferential surface 16 with respect to the needle axis α is approximately constant over the entire length in the needle axial direction. With the medical hollow needle 40 of this embodiment, there is no sudden change in the inner diameter dimension and the flow of liquid in the lumen 12 is more stable, so that the flow rate is further stabilized and damage to blood cells of the blood flowing through the lumen 12 can be further reduced.

[0060] Although the embodiments of the present invention have been described above in detail, the present invention is not limited by the specific description. For example, in the first embodiment, an example was shown in which the inclination angle θ of the tapered surface 30 constituting the inner circumferential surface 16 of the medical hollow needle 10 was approximately constant except for the portion where the step-like portion 24 was formed, but the inclination angle θ of the tapered surface 30 may change stepwise or continuously. Specifically, for example, in the medical hollow needle 10 of the first embodiment, the inclination angle of the inner circumferential surface of the tip portion 26 and the inclination angle of the inner circumferential surface of the base end portion 28 can be made different from each other. In addition, the inclination angle θ of the inner circumferential surface 16 may change in the circumferential direction. When the inclination angle θ of the tapered surface 30 set on the inner circumferential surface 16 of the medical hollow needle 10 changes in the needle axial direction or the circumferential direction, it is desirable that the minimum inclination angle of the tapered surface 30 is greater than 0 degrees and the maximum inclination angle is 5 degrees or less (preferably 1 degree or less, more preferably 0.7 degrees or less).

[0061] In the medical hollow needle 10, the stepped portions 24 may be provided at two or more locations in the needle axial direction. In this case, the inner circumferential surface of the intermediate portion of the medical hollow needle 10 located between adjacent stepped portions 24, 24 in the needle axial direction is a tapered surface 30 similar to the tip portion 26 and the base portion 28, and is desirably a tapered shape with a larger diameter on the base side at the same inclination angle as the tip portion 26 and the base portion 28.

[0062] In the above embodiment, a manufacturing method for medical hollow needle 10 including first to fifth press working steps has been exemplified, but the number of press working steps is not limited to five, and may be four or less, or six or more. In particular, when manufacturing a thinner medical hollow needle 10, the number of press working steps may increase.

[0063] In the above embodiment, the needle tip 18 and blade surface 20 are formed and the inner cavity 12 is penetrated simultaneously by cutting the bottom 35 side of the sixth molded product 14g, which is a bottomed cylindrical product. However, for example, it is also possible to form a hole in the bottom 35 of the sixth molded product 14g with a punch to penetrate the inner cavity 12, and then perform cutting to form the needle tip 18 and the blade surface 20. [Explanation of symbols]

[0064] 10 Medical hollow needle (first embodiment) 12 lumen 14 Needle tube 14a Metal plate 14b 1st molded product 14c 2nd molded product 14d 3rd molded product 14e 4th molded product 14f 5th molded product (pipe) 14g 6th molded product (tube) 16 Inner surface 18 Needle tip 20 Blade surface 22 Through hole 24 Step part 26 Tip part 28 Proximal part 30 Tapered surface 32 Punch 34 Die 35 bottom 36 Flange-shaped part 40 Medical hollow needle (second embodiment) α Needle shaft θ Tilt angle

Claims

1. A method for manufacturing a medical hollow needle having an inner cavity penetrating in a needle axial direction, comprising the steps of: The inner peripheral surface of the needle tube has a tapered surface that becomes smaller in diameter toward the needle tip, which is formed by deep drawing, A method for manufacturing a medical hollow needle, wherein the arithmetic mean roughness Ra of the inner surface in the needle axial direction is Ra≦1.0 μm.

2. The needle tube has an inner diameter at a tip end portion on the needle tip side that is smaller than an inner diameter at a base end portion on the opposite side to the needle tip, and the tip end portion and the base end portion are connected by a stepped portion in which the diameter decreases toward the needle tip side.

2. The method for manufacturing a medical hollow needle according to claim 1, wherein the angle of inclination of the inner circumferential surface of the needle tube with respect to the needle axis at the stepped portion is larger than the angle of inclination of the inner circumferential surface of the tip portion and the base end portion with respect to the needle axis, and the tapered surface is formed by the inner circumferential surfaces of the tip portion and the base end portion.

3. The method for manufacturing a medical hollow needle according to claim 1 , wherein the inner peripheral surface of the needle tube is a tapered surface having a substantially constant inclination angle with respect to the needle axis over the entire length in the needle axis direction.

4. The method for manufacturing a medical hollow needle according to any one of claims 1 to 3, wherein a molding mark extending in the needle axial direction is present on the inner surface of the needle tube in a micrograph.

5. 5. The method for manufacturing a medical hollow needle according to claim 1, wherein the inclination angle of the tapered surface relative to the needle axis is greater than 0 degrees and less than 5 degrees.

6. a press working process in which a metal blank is subjected to multiple deep drawing steps to form a bottomed tube; a needle tip forming step of cutting the tube at the bottom side of the deep drawing process to form the needle tip; The method for manufacturing a medical hollow needle according to any one of claims 1 to 5, comprising:

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