WO2015170532A1

WO2015170532A1 - Curved tube section and production method for curved tube section

Info

Publication number: WO2015170532A1
Application number: PCT/JP2015/060349
Authority: WO
Inventors: 英哉北川; 猛日高
Original assignee: オリンパス株式会社
Priority date: 2014-05-08
Filing date: 2015-04-01
Publication date: 2015-11-12
Also published as: JP2015213580A

Abstract

Provided is a curved tube section (10) in which shape memory processing is used to form a wire guide section (30) in a pipe member (20) that is formed from a NiTi alloy. The wire guide section (30) is formed by shape memory processing so that in a neutral plane (20c) in the thickness direction of the pipe member (20), the circumferential length in a cross section of the neutral plane (20c) after shape memory processing does not change substantially with respect to the circumferential length in the cross section of the neutral plane (20c) prior to shape memory processing.

Description

Bent tube part and method of manufacturing the bent tube part

The present invention relates to a bending tube portion and a manufacturing method of the bending tube portion.

For example, in Patent Document 1, the wire guide portion is formed by pressing into a cylindrical node ring of a curved portion. As the material of such a node ring, for example, stainless steel or steel that can be easily plastically processed is used.

On the other hand, a superelastic pipe member such as a NiTi alloy may be used as the curved pipe portion. In this case, the plastic processing as described above is used for the pipe member in a cold state, and even if an attempt is made to form the wire guide portion by plastic processing, the pipe member is formed before the wire guide portion is formed due to the superelastic characteristics. It will return to its original shape. For this reason, it becomes difficult to form a wire guide portion by plastic working on a superelastic pipe member. Therefore, when the wire guide portion is formed on the superelastic pipe member, it is necessary to perform shape memory processing as disclosed in Patent Document 2, for example, on the superelastic pipe member. In this case, under a predetermined environment, the pipe member is pressurized by a die having a cut and bent shape transfer portion that forms the wire guide portion, and the cut and bent shape of the cut and bent shape transfer portion is transferred to the pipe member. A wire guide portion is formed on the pipe member. At the time of transfer, the cut and bent shape transfer portion is pressed against a part of the circumferential surface of the arcuate pipe member, so that a part thereof is deformed into a U shape. This deformed portion functions as a wire guide portion.

JP-A-9-122786 Japanese Patent Publication No. 6-65741

When a part of the peripheral surface is deformed and elongation is added to the deformed portion, the maximum value of strain tends to exceed the superelastic limit of about 8%. As a result, the inner peripheral side of the wire guide portion in the vicinity of the deepest portion of the U-shaped wire guide portion is broken and broken.

The present invention has been made in view of these circumstances, and when a superelastic pipe member is used as a curved pipe portion, the wire guide portion can be damaged by applying an appropriate shape memory process to the pipe member. It is an object of the present invention to provide a bending tube portion that can be prevented and a method for manufacturing the bending tube portion.

According to one aspect of the bending pipe portion of the present invention, a wire guide portion is formed by a shape memory process on a pipe member formed of a NiTi alloy, and the intermediate surface after the shape memory process is formed on a neutral surface in the thickness direction of the pipe member. The wire guide portion is formed by the shape memory process so that the peripheral length in the cross section of the vertical plane does not substantially change with respect to the peripheral length in the cross section of the neutral plane before the shape memory process.

In one aspect of the method for manufacturing a curved pipe portion of the present invention, a pipe member formed of a NiTi alloy is constrained to a mold, and the cut shape is cut by the cut shape transfer portion disposed in the mold. The pipe member is heated and cooled while being transferred from the outer peripheral surface side to the pipe member, and the shape of the pipe member is memorized, thereby forming the wire guide portion into the pipe member, and the thickness direction of the pipe member In the neutral surface, the wire guide portion is shaped so that the circumference in the cross section of the neutral surface after the shape memory process does not substantially change with respect to the circumference in the cross section of the neutral surface before the shape memory process. Molded by memory processing.

According to the present invention, when a superelastic pipe member is used as a bending pipe part, the bending pipe part and the bending pipe part can be prevented from being damaged by applying an appropriate shape memory process to the pipe member. A manufacturing method can be provided.

FIG. 1A is a perspective view of a bending tube portion according to first and second embodiments of the present invention. FIG. 1B is a cross-sectional view of the pipe member according to the first and second embodiments. FIG. 2A is a diagram illustrating a state of a neutral surface in the first embodiment. FIG. 2B is a diagram illustrating dimensions of the pipe member in the base state according to the first embodiment. FIG. 2C is a diagram illustrating dimensions of each position in the initial state and the improved state of the first embodiment. FIG. 2D is a diagram illustrating the circumference of the neutral surface and the rate of change in each state of the first embodiment. FIG. 3A is a diagram illustrating a state of a neutral surface in the second embodiment. FIG. 3B is a diagram illustrating dimensions of the pipe member in the base state according to the second embodiment. FIG. 3C is a diagram illustrating dimensions of each position in the initial state and the improved state according to the second embodiment. FIG. 3D is a diagram illustrating the circumference of the neutral surface and the rate of change in each state of the second embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First Embodiment]
The first embodiment will be described with reference to FIGS. 1A, 1B, 2A, 2B, 2C, and 2D. Note that in some drawings, illustration of some members is omitted for clarity of illustration.

The bending tube portion 10 as shown in FIG. 1A is disposed, for example, in an insertion portion of an endoscope. The curved tube portion 10 of the present embodiment is not configured by connecting cylindrical annular members so as to be rotatable. As shown in FIG. 1A, a pipe member 20 having a notch portion 11 is used for the bending tube portion 10 of the present embodiment. The pipe member 20 has, for example, a cylindrical shape. The notch portion 11 is disposed in order for the bending tube portion 10 (pipe member 20) to bend. The notch 11 is formed in the pipe member 20 in advance before the shape memory process described later is performed on the pipe member 20.

As shown in FIG. 1B, the bent tube portion 10 of the present embodiment is configured by forming a wire guide portion 30 on a cylindrical pipe member 20 formed of a NiTi alloy by a shape memory process. The wire guide unit 30 guides an operation wire (not shown) for bending the bending tube unit 10. In other words, the wire guide portion 30 functions as a wire receiving portion that holds the operation wire. The wire guide portion 30 is a bent indented portion that is recessed from the outer peripheral surface 20 b side of the pipe member 20 toward the inner peripheral surface 20 a side of the pipe member 20, and is a part of the pipe member 20. . Such a wire guide part 30 has a U-shape, for example. It is sufficient that at least one wire guide portion 30 is disposed in the circumferential direction of the pipe member 20. When the bending tube portion 10 is bent in two directions such as the up and down direction, usually two wire guide portions 30 are provided. When the bending tube portion 10 bends in four directions such as up, down, left, and right directions, usually four wire guide portions 30 are provided. In these cases, the wire guide portions 30 are arranged apart from each other in the circumferential direction of the bending tube portion 10. Also in the direction of the central axis of the bending tube portion 10, the wire guide portions 30 are disposed apart from each other.

In forming the wire guide portion 30, the pipe member 20 is sandwiched by a mold (not shown) with the notch 11 in advance, and is restrained by the mold. The mold includes a not-shown cut shape transfer portion that functions as, for example, a convex punch that forms the wire guide portion 30. In a state where the pipe member 20 is constrained by the mold, the cut and bent shape of the cut and bent shape transfer portion is transferred to the pipe member 20 from the outer peripheral surface 20b side to the inner peripheral surface 20a side. The wire guide part 30 is shape | molded by the pipe member 20 by being cooled and shape-memorizing the pipe member 20 in a heating and cooling process. At the time of transfer, a part of the peripheral surface of the arc-shaped pipe member 20 is deformed into, for example, a U shape in the cross section of the pipe member 20 because the cut-shaped transfer portion is pressed. This deformed portion functions as a wire guide portion 30 having two first bent portions 31 and one second bent portion 33 as shown in FIG. 1B.

In the present embodiment, in the cross section of the pipe member 20 shown in FIG. 1B, the first bent portion 31 protrudes from the center of the pipe member 20 toward the outside of the pipe member 20 in the radial direction of the pipe member 20. It is a part to be done. In the cross section of the pipe member 20, the second bent portion 33 is a portion protruding from the outside of the pipe member 20 toward the center of the pipe member 20 in the radial direction of the pipe member 20. Note that one of the first bent portion 31 and the second bent portion 33 may be formed, and the other may be formed. The diameter of the first bent portion 31 and the diameter of the second bent portion 33 are smaller than the diameter of the pipe member 20. In the cross section of the pipe member 20, the first bent portion 31 functions as a convex portion and the second bent portion 33 functions as a concave portion when viewed from the center of the pipe member 20. In the cross section and the circumferential direction of the pipe member 20, the first bent portion 31, the second bent portion 33, and the first bent portion 31 are arranged in this order. That is, the second bent portion 33 is sandwiched between the first bent portions 31. The second bent portion 33 has one end connected to one first bent portion 31 and the other end connected to the other first bent portion 31.

Next, design requirements for the shape memory process will be described with reference to FIGS. 2A, 2B, 2C, and 2D.
First, as shown in FIGS. 1A and 2B, the dimensions of the cylindrical pipe member 20 in the base state before the shape memory processing are defined in advance as follows, for example.
Inner diameter D = 2.451 mm
Thickness T = 0.114mm
The inner diameter D and the wall thickness T are shown in FIG. 1B. In this case, the radius IR on the inner peripheral surface 20a and the radius OR on the outer peripheral surface 20b are calculated based on the inner diameter D and the wall thickness T as follows.
IR = D / 2 = 2.451 / 2 = ≈1.226 mm
OR = IR + T = 1.226 + 0.114 = ≈1.340 mm
Here, in the cross section of the pipe member 20, an intermediate surface between the inner peripheral surface 20a and the outer peripheral surface 20b in the thickness direction of the pipe member 20 is defined as a neutral surface 20c. In addition, the neutral surface 20c should just be located in the thickness direction of the pipe member 20 between the inner peripheral surface 20a and the outer peripheral surface 20b.

In this case, since the radius MR at the neutral surface 20c is an average of the radius IR and the radius OR,
MR = (IR + OR) / 2
= (1.226 + 1.340) /2=≈1.283 mm.

Next, the design requirements for the initial shape memory processing will be described with reference to FIGS.
Here, the shape of the pipe member 20 in the base state is formed by the shape memory process, and the wire guide portion 30 having the first bent portion 31 and the second bent portion 33 is formed.

The setting result of the radius IR1 on the inner peripheral surface 20a of the first bent portion 31 is as follows.
IR1 = 0.254mm
In this case, based on the radius IR1 and the wall thickness T, the radius OR1 on the outer peripheral surface 20b of the first bent portion 31 is calculated as follows.
OR1 = IR1 + T = 0.254 + 0.114 = ≈0.368 mm
In this case, the radius MR1 at the neutral surface 20c of the first bent portion 31 is an average of the radius IR1 and the radius OR1,
MR1 = (IR1 + OR1) / 2
= (0.254 + 0.368) /2=≈0.311 mm.

The setting result of the radius OR2 on the outer peripheral surface 20b of the second bent portion 33 is as follows.
OR2 = 0.381mm
Unlike the first bending portion 31, OR2 indicates the outer peripheral side of the pipe member 20.
In this case, based on the radius OR2 and the wall thickness T, the radius IR2 on the inner peripheral surface 20a of the second bent portion 33 is calculated as follows.
IR2 = OR2 + T = 0.382 + 0.114 = ≈0.495 mm
IR2 indicates the inner peripheral side of the pipe member 20, unlike the first bent portion 31.
In this case, since the radius MR2 at the neutral surface 20c of the second bent portion 33 is an average of the radius OR2 and the radius IR2,
MR2 = (OR2 + IR2) / 2
= (0.381 + 0.495) /2=≈0.438 mm

The wire guide portion 30 having the radius and the thickness and having the first bent portion 31 and the second bent portion 33 is formed, and the state of the pipe member 20 after the shape memory processing is referred to as an initial state.

In this initial state, the strain increased by experiment, and in detail, the maximum value of the strain exceeded 8%, which is the limit of superelasticity, and the wire guide portion 30 was broken. For example, when the wire guide portion 30 is formed, the outer side of each bent portion extends and the inner side of each bent portion shrinks. For example, the peripheral length of the neutral surface 20c increases. One reason may be that it has stopped.

Therefore, as shown in FIG. 2D, the length of the circumference of the neutral surface 20c in the base state and the initial state will be compared. Here, as an example of the circumference, a comparison is made based on a circumference of 1/4 circle. Furthermore, the circumferential length CL of the neutral surface 20c in the arc-shaped portion that maintains the shape of the base state without being formed, the circumferential length CL1 of the neutral surface 20c in the first bending portion 31, and the second bending portion 33. The total value CT, which is the sum of the circumferential length CL2 of the neutral surface 20c, is calculated, and CL and CT are compared.
That is, CT = CL + CL1 + CL2.

In the base state, the first bent portion 31 and the second bent portion 33 are not formed.
CL1 = CL2 = 0.
Therefore, CT = CL in the base state.

In the base state, since the first bent portion 31 and the second bent portion 33 are not formed, CL has a ¼ arc shape and theoretically has the following circumference.
CL = 2.015mm
As described above, since CL1 = CL2 = 0,
CT = CL + CL1 + CL2 = CL = 2.015 mm.

In contrast to the above, in the initial state, CL = 1.213 mm, CL1 = 0.462 mm, and CL2 = 0.377 mm are the theoretical perimeters.

Therefore, CT = CL + CL1 + CL2
= 1.213 + 0.462 + 0.377
= ≈2.053 mm

In the total value CT, the change rate of the initial state with respect to the base state is calculated as follows.
Rate of change = Total value CT in the initial state / Total value CT in the base state
= 2.053 / 2.015
= ≒ 101.89%
That is, when the circumference of the neutral surface 20c in the initial state extends 1.89% with respect to the circumference of the neutral surface 20c in the base state, the maximum value of the strain exceeds the superelastic limit of about 8%. It becomes easy and the wire guide part 30 has a high possibility of breaking.

2A, FIG. 2B, FIG. 2C, and FIG. 2D, the maximum value of the strain is prevented from exceeding about 8%, which is the limit of superelasticity, and the wire guide portion 30 is prevented from cracking. Next, the design requirements for the shape memory processing improved from the above will be described.
Here, the radius IR1 on the inner peripheral surface 20a of the first bent portion 31 is improved as follows. This state of the pipe member 20 is referred to as an improved state. In the present embodiment, the first bent portion 31 has different dimensions in the initial state and the improved state, but the second bent portion 33 has the same size in the initial state and the improved state. For this reason, the depth dimension of the 2nd bending part 33 is the same even if it is an improved state and an initial state. In the connection part of the 1st bending part 31 and the 2nd bending part 33, the 1st bending part 31 and the 2nd bending part 33 are mutually connected in the shape of a curve so that S shape may be formed. ing. Therefore, no linear portion exists between the first bent portion 31 and the second bent portion 33.

IR1 = 0.381mm
For this purpose, OR1, MR1, IR2, and MR2 are calculated as follows.
OR1 = IR1 + T = 0.382 + 0.114 = ≈0.495 mm
MR1 = (IR1 + OR1) / 2 = (0.381 + 0.495) /2=≈0.438 mm
Since the improved state of the second bent portion 33 is the same as the initial state, the following is the same as described above.
OR2 = 0.381mm
IR2 = OR2 + T = 0.382 + 0.114 = ≈0.495 mm
MR2 = (OR2 + IR2) / 2 = (0.381 + 0.495) /2=≈0.438 mm

In the improved state, CL = 1.050 mm, CL1 = 0.644 mm, and CL2 = 0.315 mm are theoretical circumferences.

Therefore, CT = CL + CL1 + CL2
= 1.050 + 0.644 + 0.315
= ≈2.009 mm.

In the total value CT, the change rate of the improved state with respect to the base state is calculated as follows.
Rate of change = Total value CT in improved state / Total value CT in base state
= 2.009 / 2.015
= 99.73%
That is, the circumferential length of the neutral surface 20c in the improved state is reduced by 0.27% with respect to the circumferential length of the neutral surface 20c in the base state. As a result, the maximum strain value is prevented from exceeding about 8%, which is the limit of superelasticity, and cracking of the wire guide portion 30 is prevented.

Thus, in the neutral surface 20c of the pipe member 20, the circumferential length (hereinafter referred to as the circumferential length A) of the neutral surface 20c after the shape memory process is the transverse cross section of the neutral surface 20c before the shape memory process. The wire guide portion 30 is formed by shape memory processing so that it does not substantially change with respect to the circumferential length (hereinafter referred to as circumferential length B). The circumference in the cross section of the neutral surface 20c after the shape memory process indicates, for example, an improved state. The circumference in the cross section of the neutral surface 20c before the shape memory process indicates, for example, a base state. In this embodiment, in detail, the wire guide part 30 is shape | molded by a shape memory process so that the circumference A may shrink | contract minutely with respect to the circumference B. In the present embodiment, this suppresses the maximum strain value from exceeding about 8%, which is the limit of superelasticity, and prevents the wire guide portion 30 from cracking.

Thus, in this embodiment, when the wire guide part 30 is shape | molded by the shape memory process in the pipe member 20 formed with a NiTi alloy, as shown in an improved state, the neutral surface 20c in an arc-shaped part is shown. Is defined as 1.050 mm, the circumferential length CL1 of the neutral surface 20c in the first bending portion 31 is defined as 0.644 mm, and the circumferential length CL2 of the neutral surface 20c in the second bending portion 33. Is defined as 0.315 mm, the design requirements of the wire guide portion 30 are clear. Accordingly, in the present embodiment, the circumferential length A can be slightly reduced with respect to the circumferential length B, and the maximum strain value can be prevented from exceeding about 8%, which is the limit of superelasticity. Can be prevented from cracking. Therefore, in the present embodiment, when the superelastic pipe member 20 is used as the bending tube portion 10, the wire guide portion 30 can be prevented from being damaged by the shape memory processing of the design requirements described above.

In the present embodiment, the shape memory processing according to the design requirements described above can stabilize the quality of the bending tube portion 10 and eliminate waste in manufacturing. In this embodiment, the rate of change is 99.73%, but the rate of change may be slightly different as long as the rate of change is around 100%.

In the present embodiment, only the first bent portion 31 in the improved state is deformed with respect to the first bent portion 31 in the initial state. For this reason, in this embodiment, the dead space around the 1st bending part 31 in the inner surface of the bending pipe part 10 can be improved. In the present embodiment, the second bent portion 33 has the same dimensions in the initial state and the improved state. For this reason, the 2nd bending part 33 of the wire guide part 30 by which an operation wire is arrange | positioned can be designed easily as usual.

[Second Embodiment]
With reference to FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D, the design requirement of the shape memory process in 2nd Embodiment is demonstrated.
First, as shown in FIGS. 3A and 3B, the dimensions of the cylindrical pipe member 20 in the base state before the shape memory processing are defined in advance as follows, for example.
Inner diameter D = 3.01mm
Thickness T = 0.13mm
In this case, the radius IR and the radius OR are calculated as follows based on the inner diameter D and the wall thickness T.
IR = D / 2 = 3.01 / 2 = ≈1.505 mm
OR = IR + T = 1.505 + 0.13 = ≈1.635 mm
In this case, since the radius MR is an average of the radius IR and the radius OR,
MR = (IR + OR) / 2
= (1.505 + 1.635) /2=≈1.57 mm.
A state of the cylindrical pipe member 20 having the radius and the thickness and before the shape memory processing is referred to as a base state.

Next, the design requirements for the initial shape memory processing will be described with reference to FIGS. 3A, 3B, and 3C.
Here, the shape of the pipe member 20 in the base state is formed by the shape memory process, and the wire guide portion 30 having the first bent portion 31 and the second bent portion 33 is formed.

The setting result of the radius IR1 on the inner peripheral surface 20a of the first bent portion 31 is as follows.
IR1 = 0.2mm
In this case, based on the radius IR1 and the wall thickness T, the radius OR1 on the outer peripheral surface 20b of the first bent portion 31 is calculated as follows.
OR1 = IR1 + T = 0.2 + 0.13 = ≈0.33 mm
In this case, the radius MR1 at the neutral surface 20c of the first bent portion 31 is an average of the radius IR1 and the radius OR1,
MR1 = (IR1 + OR1) / 2
= (0.2 + 0.33) /2=≈0.265 mm

The setting result of the radius OR2 on the outer peripheral surface 20b of the second bent portion 33 is as follows.
OR2 = 0.25mm
Unlike the first bending portion 31, OR2 indicates the outer peripheral side of the pipe member 20.
In this case, based on the radius OR2 and the wall thickness T, the radius IR2 on the inner peripheral surface 20a of the second bent portion 33 is calculated as follows.
IR2 = OR2 + T = 0.25 + 0.13 = ≈0.38 mm
IR2 indicates the inner peripheral side of the pipe member 20, unlike the first bent portion 31.
In this case, since the radius MR2 at the neutral surface 20c of the second bent portion 33 is an average of the radius OR2 and the radius IR2,
MR2 = (OR2 + IR2) / 2
= (0.25 + 0.38) /2=≈0.315 mm

In the second bent portion 33 in the initial state, the depth d of the neutral surface 20c is 0.425 mm.

The wire guide portion 30 having the radius, the thickness, and the depth and having the first bent portion 31 and the second bent portion 33 is formed, and the state of the pipe member 20 after the shape memory processing is changed to the initial state. Called.

Therefore, as shown in FIG. 3D, the circumferential length of the neutral surface 20c in the base state and the initial state will be compared. Here, as an example of the circumference, a comparison is made based on a circumference of 1/4 circle. Furthermore, the circumferential length CL of the neutral surface 20c in the arc-shaped portion that maintains the shape of the base state without being formed, the circumferential length CL1 of the neutral surface 20c in the first bending portion 31, and the second bending portion 33. The total value CT, which is the sum of the circumferential length CL2 of the neutral surface 20c, is calculated, and CL and CT are compared.

That is, CT = CL + CL1 + CL2.

In the base state, since the first bent portion 31 and the second bent portion 33 are not formed, CL has a ¼ arc shape and theoretically has the following circumference.
CL = 2.46615mm
As described above, since CL1 = CL2 = 0,
CT = CL + CL1 + CL2 = CL = 2.46615 mm.

On the other hand, in the initial state, CL = 1.82602 mm, CL1 = 0.400115 mm, and CL2 = 0.347175 mm are theoretical perimeters.

Therefore, CT = CL + CL1 + CL2
= 1.826002 + 0.400115 + 0.347175
= ≈2.57331 mm.

In the total value CT, the change rate of the initial state with respect to the base state is calculated as follows.
Rate of change = Total value CT in the initial state / Total value CT in the base state
= ≒ 104.35%
That is, when the neutral surface 20c in the initial state extends by 4.35% with respect to the neutral surface 20c in the base state, the maximum value of the distortion easily exceeds about 8%, which is the limit of superelasticity, and the wire guide portion. 30 is likely to break.

Therefore, referring to FIG. 3A, FIG. 3B, FIG. 3C, and FIG. 3D, it is possible to prevent the maximum value of strain from exceeding about 8%, which is the limit of superelasticity, and to prevent the wire guide portion 30 from cracking. Next, the design requirements for the shape memory processing improved from the above will be described.
Here, the sizes of the radius IR1 on the inner peripheral surface 20a of the first bent portion 31 and the radius OR2 on the outer peripheral surface 20b of the second bent portion 33 are improved as follows. This state of the pipe member 20 is referred to as an improved state. In the present embodiment, the first bent portion 31 has different dimensions in the initial state and the improved state, and the second bent portion 33 also has different dimensions in the initial state and the improved state. For this reason, in the improved 2nd bending part 33, the depth d of the neutral surface 20c is 0.4 mm, and is shallower than the initial state. In the connection part of the 1st bending part 31 and the 2nd bending part 33, the 1st bending part 31 and the 2nd bending part 33 are mutually connected in the shape of a curve so that S shape may be formed. ing. Therefore, no linear portion exists between the first bent portion 31 and the second bent portion 33.

IR1 = 0.45mm
OR2 = 0.45mm
For this purpose, OR1, MR1, IR2, and MR2 are calculated as follows.
OR1 = IR1 + T = 0.45 + 0.13 = ≈0.58 mm
MR1 = (IR1 + OR1) / 2 = (0.45 + 0.58) /2=≈0.515 mm
IR2 = OR2 + T = 0.45 + 0.13 = ≈0.58 mm
MR2 = (OR2 + IR2) / 2 = (0.45 + 0.58) /2=≈0.515 mm

In the improved state, CL = 1.46008 mm, CL1 = 0.694421 mm, and CL2 = 0.339404 mm are theoretical circumferences.

Therefore, CT = CL + CL1 + CL2
= 1.460008 + 0.669421 + 0.339404
= ≈2.46891 mm.

In the total value CT, the change rate of the improved state with respect to the base state is calculated as follows.
Rate of change = Total value CT in improved state / Total value CT in base state
= 2.46891 / 2.46615
= ≒ 100.11%
That is, the peripheral length of the neutral surface 20c in the improved state extends by approximately 0.11% with respect to the peripheral length of the neutral surface 20c in the base state. As a result, the maximum strain value is prevented from exceeding about 8%, which is the limit of superelasticity, and cracking of the wire guide portion 30 is prevented.

Thus, in the neutral surface 20c of the pipe member 20, the circumferential length (hereinafter referred to as the circumferential length A) of the neutral surface 20c after the shape memory process is the transverse cross section of the neutral surface 20c before the shape memory process. The wire guide portion 30 is formed by shape memory processing so that it does not substantially change with respect to the circumferential length (hereinafter referred to as circumferential length B). In the present embodiment, in detail, the wire guide portion 30 is formed by shape memory processing so that the circumferential length A hardly extends with respect to the circumferential length B in detail, and in detail, it extends extremely finely. In this case, in this embodiment, the wire guide part 30 is shape | molded by a shape memory process so that the change rate of the circumference A with respect to the circumference B may be about 100.11% or less. Thereby, it is suppressed that the maximum value of distortion exceeds about 8% which is the limit of superelasticity, and the crack of the wire guide part 30 is prevented.

Thus, in this embodiment, when the wire guide part 30 is shape | molded by the shape memory process in the pipe member 20 formed with a NiTi alloy, as shown in an improved state, the neutral surface 20c in an arc-shaped part is shown. Is defined as 1.46008 mm, the circumferential length CL1 of the neutral surface 20c in the first bent portion 31 is defined as 0.669421 mm, and the circumferential length CL2 of the neutral surface 20c in the second bent portion 33 is defined. Is defined as 0.339404 mm, the design requirements of the wire guide 30 are clear. Thereby, in this embodiment, the perimeter A can be extended very minutely with respect to the perimeter B, and the maximum value of the strain can be suppressed from exceeding about 8%, which is the limit of superelasticity. Can be prevented from cracking. Therefore, in the present embodiment, when the superelastic pipe member 20 is used as the bending tube portion 10, the wire guide portion 30 can be prevented from being damaged by the shape memory processing of the design requirements described above.

The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment.

Claims

A pipe member formed of a NiTi alloy is a curved tube part in which a wire guide part is formed by shape memory processing,
In the neutral surface in the thickness direction of the pipe member, so that the circumferential length in the cross section of the neutral surface after the shape memory treatment does not substantially change with respect to the circumferential length in the cross section of the neutral surface before the shape memory treatment, A curved tube portion in which the wire guide portion is formed by shape memory processing.
The wire guide portion is formed by shape memory processing so that the peripheral length of the neutral surface after the shape memory processing does not substantially extend with respect to the peripheral length of the neutral surface before the shape memory processing. The bending tube part as described in.
The wire guide portion is subjected to shape memory processing so that the rate of change of the circumference of the neutral surface after shape memory processing with respect to the circumference of the neutral surface before shape memory processing is approximately 100.11% or less. The bending pipe part according to claim 2 formed.
At least one wire guide portion is disposed in the circumferential direction of the pipe member,
The wire guide portion is sandwiched between two first bent portions, one end connected to one of the first bent portions, and connected to the other first bent portion. A second bend having the other end of the
The first bent portion is protruded outward from the center of the pipe member in the radial direction of the pipe member, and has a smaller diameter than the pipe member.
The bending pipe portion according to claim 3, wherein the second bending portion protrudes from the outside toward the center portion in the radial direction of the pipe member and has a smaller diameter than the pipe member.
The pipe member formed of the NiTi alloy is constrained to the mold, and the cut and bent shape is transferred from the outer peripheral surface side of the pipe member to the pipe member by the cut and bent shape transfer portion disposed in the mold. Heating and cooling a pipe member, and a shape of the pipe member is memorized, whereby a wire guide part is formed into the pipe member.
In the neutral surface in the thickness direction of the pipe member, so that the circumferential length in the cross section of the neutral surface after the shape memory treatment does not substantially change with respect to the circumferential length in the cross section of the neutral surface before the shape memory treatment, A method for manufacturing a bending tube part, wherein the wire guide part is formed by shape memory processing.