U.S. patent application number 10/874756 was filed with the patent office on 2005-02-03 for method of making a metallic thin wire and a medical tool into which the metallic thin wire is incorporated.
This patent application is currently assigned to ASAHI INTECC CO., LTD.. Invention is credited to Kato, Tomihisa, Miyata, Kenji.
Application Number | 20050022572 10/874756 |
Document ID | / |
Family ID | 33411088 |
Filed Date | 2005-02-03 |
United States Patent
Application |
20050022572 |
Kind Code |
A1 |
Kato, Tomihisa ; et
al. |
February 3, 2005 |
Method of making a metallic thin wire and a medical tool into which
the metallic thin wire is incorporated
Abstract
In a method of making a metallic thin wire (1), one single
metallic thin wire (2) is prepared to have a predetermined length
with a middle portion of the one single metallic thin wire (2) as a
fixed portion. Front and rear half portions of the one single
metallic thin wire (2) are twisted with the front and rear portions
being symmetrically located at both sides of the fixed portion,
while at the same time, applying a tensile weight (W) to the front
and rear half portions in the lengthwise direction. The one single
metallic thin wire (2) is processed with a heat treatment to remove
a residual stress from the one single metallic thin wire (2).
Otherwise, the front and rear portions of the one single metallic
thin wire (2) is primarily and secondarily twisted alternately
under the tensile weight (W) applied in the lengthwise direction.
This provides the metallic thin wire (1) with a high
rotation-following capability and high torque transmissibility,
thus enabling artisans to usefully apply the metallic thin wire (1)
to a main wire component (25) of a medical tool and equipment.
Inventors: |
Kato, Tomihisa; (Aichi-ken,
JP) ; Miyata, Kenji; (Aichi-ken, JP) |
Correspondence
Address: |
MORGAN LEWIS & BOCKIUS LLP
1111 PENNSYLVANIA AVENUE NW
WASHINGTON
DC
20004
US
|
Assignee: |
ASAHI INTECC CO., LTD.
|
Family ID: |
33411088 |
Appl. No.: |
10/874756 |
Filed: |
June 24, 2004 |
Current U.S.
Class: |
72/299 |
Current CPC
Class: |
C21D 7/10 20130101; A61M
2025/09191 20130101; C21D 8/065 20130101; A61M 2025/09108 20130101;
B21F 99/00 20130101; B21C 37/045 20130101; A61M 25/09 20130101;
Y10T 29/5187 20150115; A61M 25/0133 20130101; C21D 1/30 20130101;
B21F 7/00 20130101; Y10T 29/5121 20150115 |
Class at
Publication: |
072/299 |
International
Class: |
B21D 011/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2003 |
JP |
2003-181956 |
Claims
What is claimed is:
1. A method of making a metallic thin wire comprising steps of:
preparing one single metallic thin wire having a predetermined
length with a middle portion of said one single metallic thin wire
as a fixed portion; twisting front and rear half portions of said
one single metallic thin wire, while at the same time, applying a
tensile weight to said front and rear half portions, said front and
rear half portions being symmetrically located at both sides of
said fixed portion; and processing said one single metallic thin
wire with a heat treatment to remove a residual stress from said
one single metallic thin wire.
2. A method of making a metallic thin wire comprising steps of:
preparing one single metallic thin wire having a predetermined
length with one end of said one single metallic thin wire as a
fixed portion; primarily twisting said one single metallic thin
wire in one direction, and then secondarily twisting said one
single metallic thin wire opposite to the direction in which said
one single metallic thin wire is primarily twisted, while at the
same time, applying a tensile weight to said one single metallic
thin wire in the lengthwise direction; and processing said one
single metallic thin wire with a heat treatment to remove a
residual stress from said one single metallic thin wire.
3. The method of making a metallic thin wire according to claim 2,
wherein said primarily twisting step is an excessive enough to
induce slip lines on an outer surface of said one single metallic
thin wire.
4. The method of making a metallic thin wire according to claim 2,
wherein total turning times of said secondarily twisting step is
more than 0.15 times inclusive of that of said primarily twisting
step, but less than 1.5 times inclusive of that of said primarily
twisting step.
5. The method of making a metallic thin wire according to claim 1,
wherein said one single metallic thin wire is divided into a
plurality of zones in the lengthwise direction, each of which is
twisted in different numbers of turns.
6. The method of making a metallic thin wire according to claim 1,
wherein said one single metallic thin wire is divided in the
lengthwise direction into a plurality of zones in the lengthwise
direction, each of which is processed with said heat treatment in
varied degrees.
7. The method of making a metallic thin wire according to claim 2,
wherein said primarily twisting step and said secondarily twisting
step are combined to form a unitary set, and said unitary set is
repeatedly applied to said one single metallic thin wire in a
plurality of times.
8. The method of making a metallic thin wire according to claim 1,
wherein an outer surface of said one single metallic thin wire is
treated with an electrolytic polishing procedure after processed
with said heat treatment.
9. A medical tool which incorporates said metallic thin wire
produced by the method according to any of claims 1-8.
10. The medical tool according to claim 9, wherein said metallic
thin wire is made of an austenitic stainless steel.
11. The medical tool according to claim 10, wherein said metallic
thin wire is applied to at least one member selected from the group
consisting of a main wire component, a shaft, a stylus, a
pull-wire, a stent and a needle.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The invention relates to a method of making a metallic thin
wire in the form of a flexible wire configuration used as a main
wire component of a medical tool such as a catheter, a catheter
guide wire, an endscope treating instrument or the like, and
particularly concerns to a medical tool produced by the method of
making the metallic thin wire.
[0003] 2. Description of Prior Art
[0004] In a catheter and a catheter guide wire which introduces a
leading distal end into a diseased area through a sinuous vascular
system, the leading distal end of the catheter or the catheter
guide wire is inserted into the blood vessel or the somatic cavity
by a "push-pull and turn" manipulation at a hand access portion
located outside a subject patient upon treating the diseased area.
In an endscope treating instrument which is inserted through a
somatic cavity to reach the diseased area, a leading end of the
endscope treating instrument is manipulated in the same manner as
mentioned above.
[0005] In order to achieve a smooth manipulation when inserting the
leading distal end into the somatic cavity and the blood vessel, it
is required for these medical devices to have multi-mechanical
properties. The multi-mechanical properties include a high
flexibility, a good straightness and restitutivity in an
unrestricted free state against bending deformation. The medical
devices of this type are required at its leading distal end portion
to have a high flexibility, while at the same time, required at its
rear portion to have an appropriate rigidity as a functionally
gradient property. It is also indispensable for the leading distal
end to have a high maneuverability in which the leading distal end
properly responds to the hand operation which is to be done outside
the subject patient.
[0006] The following publications disclose a flexible linear wire
used as a main component of the medical devices with an aim to
achieving the above indispensable multi-mechanical properties.
[0007] In the references of Laid-open Japanese Patent Application
No. 7-148267 and Domestic Publication No. 2000-512691 (referred in
turn to as "first and second reference" hereinafter), the first
reference shows a method of making a metallic thin wire in which a
metallic wire is mechanically rolled straight through a correction
roller, and then thermally treated to remove a residual stress so
as to produce a medical guide wire superior in linearity and
straightness.
[0008] The second reference also shows a method of making a
metallic thin wire in which a thin wire is made of a shape-memory
alloy, and twisted under a tensile force applied to the thin wire,
and then thermally treated to remove a residual stress so as to
produce a catheter guide wire.
[0009] The medical guide wire produced by the first reference is
superior in a lengthwisely directed straightness. It is, however,
poor in torsional characteristics. This leads to a shortage of the
torque transmissibility and rotational maneuverability so as to
reduce the steerability.
[0010] The catheter guide wire produced by the second reference
specifies the shape-memory alloy, and only one metallic thin wire
is prepared each time the method is used upon producing the
catheter guide wire. This makes the catheter guide wire costly and
disadvantageous especially when brought to the mass production. In
addition, the metallic thin wire is twisted only in one direction,
and thus making the torsional characteristics uneven in the
lengthwise direction. Because the metallic thin wire is twisted
only in one direction, and not twisted further in the reverse
direction, the metallic thin wire becomes to lack the torque
transmissibility and rotation-following capability to reduce the
steerability when applied to the medical guide wire, and maneuvered
to swivel the guide wire in the right and left directions upon
inserting the guide wire into the vascular vessel.
[0011] Therefore, it is an object of the invention to overcome the
above drawbacks so as to provide a method of making a metallic thin
wire and a medical tool which are capable of improving a
rotation-following capability and torque transmissiblity so as to
enhance a steerability.
SUMMARY OF THE INVENTION
[0012] According to the present invention, there is provided a
method of making a metallic thin wire which is twisted in one
direction under a tensile weight applied in the lengthwise
direction, or primarily and secondarily twisted alternately in one
direction and the opposite direction under the tensile weight
applied in the lengthwise direction. This induces a uniform
torsional rigidity in the right and left directions through an
entire length of the one single metallic thin wire.
[0013] According to other aspect of the present invention, one
single metallic thin wire is prepared to have a predetermined
length or a bifold extension of the predetermined length. A middle
portion of the one single metallic thin wire is fixedly supported
at a fixed portion. Front and rear half portions of the one single
metallic thin wire is twisted (in one direction) with the front and
rear half portions symmetrically located at both sides of the fixed
portion. At the time of twising the front and rear half portions, a
tensile weight is concurrently applied to the front and rear half
portions. This produces two metallic thin wires simultaneously in a
dual-way fashion to maintain the product quality uniform while
improving the productivity.
[0014] According to other aspect of the present invention, the one
single metallic thin wire which is primarily twisted is further
twisted secondarily. At the time of primarily twisting the one
single metallic thin wire, the one single metallic thin wire is
excessively twisted nearly to induce slip lines (Luder's lines) on
an outer surface of the one single metallic thin wire. Total
turning times of the secondarily twisting step is more than 0.15
times of that of the primarily twisting step, but less than 1.5
times of that of the primarily twisting step. It is preferable that
the primarily twisting numbers of times is 0.2 times as great as
that of the secondarily twisting numbers of times.
[0015] The one single metallic thin wire is divided into a
plurality of zones in the lengthwise direction, each of which is
twisted in different number of turns, or processed with the heat
treatment in varied degrees so as to enhance the performance when
the one single metallic thin wire is applied to a medical tool or
equipment. From the same viewpoint, an outer surface of the one
single metallic thin wire is treated with an electrolytic polishing
procedure. Alternatively, the one single metallic thin wire is made
of an austenitic stainless steel.
[0016] The metallic thin wire thus produced is applied to a main
wire element, a shaft, a stylus, a pull-wire, a stent and a needle
in the medical tools such as, for example, a catheter, a balloon
catheter and a medical endscope.
[0017] From the viewpoint of an operation and advantages of the
present invention, the one single metallic thin wire is twisted in
one direction or primarily and secondarily twisted alternately
under the lengthwise tensile weight. This reduces a torsional
elasticity to impart the one single metallic thin wire with an
enhanced torsional rigidity. When the one single metallic thin wire
is primarily and secondarily twisted alternately, the uniform
torsional rigidity develops in the right and left directions
through an entire length of the one single metallic thin wire.
[0018] By primarily twisting the one single metallic thin wire
excessively beyond the yield point, a slipping stress prevails
through the entire length to induce wavy slip lines (Luder's lines)
on the weak portion of the one single metallic thin wire so as to
equalize the torsional characteristics through the entire length of
the one single metallic thin wire. By secondarily twisting the one
single metallic thin wire after primarily twisted, the excessive
amount of the twisted turns is retrieved to a certain degree, and
then the one single metallic thin wire is processed with the heat
treatment to remove the residual stress. This imparts the metallic
thin wire with a highly improved linearity and straightness.
[0019] When the one single metallic thin wire is processed with the
heat treatment while excessively twisted only in one direction, the
one single metallic thin wire is likely to torsionally and wavily
deform due to the reaction force developed from excessively
twisting the one single metallic thin wire.
[0020] When the one single metallic thin wire is processed with the
heat treatment while not excessively twisted in one direction, the
one single metallic thin wire is likely to become bendable,
although the heat treatment decreases the torsional and wavy
deformation which the one single metallic thin wire is subjected
to.
[0021] In general, the one single metallic thin wire has a tendency
to develop the torsional and wavy deformation due to an uneveness
between one portion in which an elastic reaction develops against
the torsional direction and other portion in which a plastic
deformation starts to appear when the one single metallic thin wire
is twisted with one end of the thin wire as a fixed portion.
[0022] In the present invention, the one single metallic thin wire
is primarily and secondarily twisted alternately in mutually
opposed directions. This makes the resultant numbers of twisting
turns uniform with a high torsional rigidity due to a total sum of
the twisting turns in the right and left directions when taking the
primarily and secondarily twising numbers plus and minus
respectively.
[0023] The one single metallic thin wire is primarily and
secondarily twisted alternately under the tensile weight applied to
the one single metallic thin wire, and then processed with the heat
treatment to remove the residual stress.
[0024] This produces the metallic thin wire highly superior in the
rotation-following capability (torsional rigidity and torque
transmissibility) in both the right and left directions while
securing a high flexibility and linearity in the one single
metallic thin wire.
[0025] In the medical tool and equipment into which the metallic
thin wire is incorporated as the main wire component, the main wire
component is highly superior in the rotation-following capability
(torsional rigidity and torque transmissibility) so as to enhance
the performance depending on its usage.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] A preferred form of the present invention is illustrated in
the accompanying drawings in which:
[0027] FIG. 1 is an explanatory view of one single metallic thin
wire attached to a twisting device to explain a method of twisting
the one single metallic thin wire according to a first embodiment
of the invention;
[0028] FIG. 2 is a latitudinal cross sectional view taken along the
line II-II of FIG. 1;
[0029] FIG. 3 is an explanatory view showing how the one single
metallic thin wire is twisted;
[0030] FIG. 4 is an explanatory view showing how an outer surface
of the one single metallic thin wire changes as the one single
metallic thin wire is twisted;
[0031] FIG. 5 is an explanatory view showing how one single
metallic thin wire is twisted into a metallic thin wire according
to a second embodiment of the invention;
[0032] FIG. 6 is an explanatory view of a twisting device on which
the one single metallic thin wire is mounted to be twisted;
[0033] FIG. 7 is a perspective view showing how an intermediary
clamp device works in the twisting device;
[0034] FIG. 8 is a graphical representation characteristic of the
metallic thin wire;
[0035] FIG. 9 is an explanatory view showing how one single
metallic thin wire is twisted into a metallic thin wire according
to a third embodiment of the invention;
[0036] FIG. 10 is an explanatory view of the one single metallic
thin wire mounted on the twisting device to explain the method of
twisting the one single metallic thin wire;
[0037] FIG. 11 is a graphical representation characteristic of the
metallic thin wire;
[0038] FIG. 12 is an explanatory view showing how a metallic thin
wire is manufactured according to a fourth embodiment of the
invention;
[0039] FIG. 13 is a plan view of a medical guide wire into which
the metallic thin wire is incorporated as a main wire component
according to a fifth embodiment of the invention but partly cross
sectioned;
[0040] FIG. 14 is a longitudinal cross sectional view of a medical
guide wire into which the metallic thin wire is incorporated as a
main wire component according to a sixth embodiment of the
invention; and
[0041] FIG. 15 is a plan view of a balloon catheter into which the
metallic thin wire is incorporated as a main wire component
according to a seventh embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0042] In the following description of the depicted embodiments,
the same reference numerals are used for features of the same type.
Referring to FIGS. 1 through 4, a method of making a metallic thin
wire 1 according to a first embodiment of the invention is
described. The metallic thin wire 1 is used to a main wire
component of a medicl guide wire 20, 20A and a balloon catheter 21
as shown in FIGS. 13 through 15. As a raw material of the metallic
thin wire 1, one single metallic thin wire 2 (referred merely to as
"thin wire 2" hereinafter) is drawn and severed to have a
predetermined length and diameter as shown in FIG. 1. By way of
illustration, the thin wire 2 is made of an austenitic stainless
steel, and attached to a twisting device 10 to be twisted and
processed with a heat treatment to remove a residual stress as
described hereinafter.
[0043] The thin wire 2 has a predetermined length (e.g.,
1,000-1,500 mm), one end of which is firmly clamped by a rotary
chuck 11. The other end of the thin wire 2 is clamped by a slidable
chuck 12 which is provided slidably in the lengthwise direction.
The slidable chuck 12 has a tensile weight W which hangs down a
static load 13 to apply a tensile weight W to the thin wire 2 in
its stretchy direction. This brings the thin wire 2 straight to the
stretch between the rotary chuck 11 and the slidable chuck 12 with
the tensile weight W as a torsion-resistant load. Across the rotary
chuck 11 and the slidable chuck 12, an electrically conductive line
18 is connected to be energized by a current generator 17. With the
energization of the current generator 17, the electric current
flows through the thin wire 2 to thermally treat the thin wire 2 by
its electric resistance.
[0044] With the thin wire 2 thermally treatable under the tensile
weight W, the thin wire 2 is primarily twisted around its axis in
the direction as shown at an arrow M in FIG. 2. Then, the thin wire
2 is secondarily twisted in the direction to return the way which
the thin wire 2 is primarily twisted. As shown at an arrow N in
FIG. 2, the secondarily twisted direction is opposite to the
direction in which the thin wire 2 is primarily twisted.
Concurrently with the secondarily twisting the thin wire 2 or after
the secondarily twisting the thin wire 2, the thin wire 2 is
processed with the heat treatment due to the electric resistance to
remove the residual stress from the thin wire 2. This process
produces the metallic thin wire 1 highly superior in the
rotation-following capability and linearity as shown in FIG. 3.
[0045] After the end of the heat treatment, the metallic thin wire
1 is treated at its outer surface with an electrolytic polishing
procedure to be consecutively produced as the main wire component
25 of the medical guide wire 20 for the purpose of mass
production.
[0046] By way of example, an outer diameter of the main wire
component 25 measures 0.342 mm, the primarily twisting numbers of
times is 125-185, the secondarily twisting numbers of times is
18-280, the electric current employed herein is for 3-5 minutes at
2.0-2.3 ampere, and the tensile weight W measures 4-6 kg as the
torsion-resistant load.
[0047] The primarily twisted thin wire 2 progressively decreases
its twisted numbers of times from one side 3 of the rotary chuck 11
to other side 4 of the slidable chuck 12 as shown at an initial
metamorphous stage 2A in FIG. 3. At the time of secondarily
twisting the thin wire 2 with the primarily twisted condition
maintained, the secondarily twisted thin wire 2 influences its own
twisted numbers of times to successively increase from one side 3
of the rotary chuck 11 to other side 4 of the slidable chuck 12 as
shown at a subsequent metamorphous stage 2B in FIG. 3.
[0048] Based on the composite metamorphosis of the thin wire 2
primarily and secondarily twisted and a total sum of the primarily
and secondarily twisted numbers of times, the thin wire 2 comes to
be equally twisted substantially through the entire length of the
thin wire 2. By primarily and secondarily twisting the thin wire 2
alternately, a torsional rigidity is induced on the thin wire 2
equally in its lengthwise direction to impart the thin wire 2 with
a uniform rotation-following capability and linearity substantially
through the entire length of the thin wire 2. Wavy curves depicted
on the metallic thin wire 1, the thin wire 2 and the main wire
component 25 in FIG. 3 are for the purpose of clarifying
unrecognizable marks on each wire element.
[0049] More particularly, during primarily twisting the thin wire
2, a torsional surface appears on the thin wire 2 as shown at stage
one 2C in FIG. 4. At the end of the primarily twisting (excessive
twist) the thin wire 2, a swollen surface appears on the thin wire
2 with a torsional pitch maintained substantially uniform as shown
at stage two 2D in FIG. 4. At the end of the secondarily twisting
the thin wire 2, the swollen surface disappears from the thin wire
2 with the torsional pitch somewhat larger than that of the stage
two 2D as shown at stage three 2E in FIG. 4. The non-swollen
surface runs in a spiral fashion with the lead angle as 4-5
degrees. In this instance, the stage three 2E is in the condition
in which the primarily twisted numbers of times is approximately
20% of the secondarily twisted numbers of times.
[0050] FIGS. 5 through 8 show a second embodiment of the invention
in which the thin wire 2 is divided into a plurality of zones X, Y
and Z in the lengthwise direction. The zones X, Y and Z in turn
have different twisted numbers of times after the thin wire 2 is
primarily and secondarily twisted depending on the zones X, Y and
Z. When the thin wire 2 is used to the medical guide wire 20, 20A
and the balloon catheter 21 as shown in FIGS. 13 through 15, the
zone X has the largest numbers of twisted times to position near a
hand access section 27 with the smallest numbers of twisted times
given to the zone Z. The zone Y, which positions between the zone X
and the zone Z, has a middle numbers of twisted times between the
largest and smallest numbers of twisted times. In this way, the
thin wire 2 are wrought out to have the different numbers of
twisted times discretely depending on the zones X, Y and Z.
[0051] In the second embodiment of the invention, an intermediary
clamp device 14 is slidably placed between the rotary chuck 11 and
the slidable chuck 12 in the twisting device 10 as shown in FIG. 7.
The clamp device 14 has a pair of movable clamp pieces 15 to clamp
the thin wire 2 at an appropriate position. The clamp device 14 is
placed at boundaries between the zones X, Y and Z to clamp the
boundaries in turn with a predetermined time lag at the time when
primarily and secondarily twisting the thin wire 2. This enables
artisans to produce the zones X, Y and Z of different numbers of
twisted times.
[0052] The thin wire 2 thus provided has a mechanical property in
which a bending characteristics differs hard and soft depending on
the zones X, Y and Z as shown in FIG. 8. When the thin wire 2 is
applied as a flexible line wire to the medical guide wire 20, 20A
and the balloon catheter 21 (medical tools), the thin wire 2
progressively changes its bending rigidity R1 along the lengthwise
direction L so as to produce the high quality metallic thin wire 1
whose rigidity and flexibility gradually changes to represent a
functionally gradient characteristics.
[0053] Namely, the most rigid portion of the medical tools is where
the hand access section 27 positions to be grasped and maneuvered
outside the subject patient. The most flexible portion of the
medical tools is a leading head portion which is to be inserted
into the blood vessel and somatic body.
[0054] FIGS. 9 through 11 show a third embodiment of the invention
in which the thin wire 2 is divided into a plurality of zones X, Y
and Z in the lengthwise direction. The zones X, Y and Z have
heating devices 16A, 16B and 16C in turn to be heated in different
degrees depending on the zones X, Y and Z after the thin wire 2 is
primarily and secondarily twisted into the metallic thin wire 1.
The residual stress is removed from the thin wire 2 in varied
degrees depending on the zones X, Y and Z. For this reason, the
thin wire 2 has a tensile strength and bending rigidity R2
gradually changing in the lengthwised direction L as shown in FIG.
11. This enables the metallic thin wire 1 to work as a high quality
main wire component for the medical guide wire 20, 20A and the
balloon catheter 21. In this instance, any of the metallic thin
wire 2 can be used which represents the first and second
embodiments of the invention.
[0055] FIG. 12 shows a fourth embodiment of the invention in which
a dual rotary chuck 11A is provided in the twisting device 10. An
extension of the thin wire 2 is a bifold of the predetermined
length. A middle section of the thin wire 2 is firmly clamped by
the dual rotary chuck 11A. Both ends of the thin wire 2 is clamped
by a slidable chuck 12A which hangs down the tensile weight W.
[0056] In this instance, the thin wire 2 symmetrically locates its
right (front) half portion and left (rear) half portion in a dual
fashion. Thereafter, the right and left half portions are primarily
and secondarily twisted in the same manner as done in the first
embodiment of the invention. With the use of the dual rotary chuck
11A, two metallic thin wires can be produced concurrently, thus
reducing the manufacturing cost with a high productivity. The two
metallic thin wires is produced under the same conditions, thus
contributing to equalizing the quality of the product.
[0057] FIG. 13 shows a fifth embodiment of the invention in which
the metallic thin wire 1 is used to the medical tool and equipment.
In this instance, the metallic thin wire 1 is made of the
austenitic stainless steel and produced by any of the method
described from the first embodiment to the fourth embodiment of the
invention. The metallic thin wire 1 thus produced is applied as the
main wire component 25 to the medical guide wire 20.
[0058] FIG. 14 shows a sixth embodiment of the invention in which
the metallic thin wire 1 is used to the medical tool. The metallic
thin wire 1, which is produced in the same manner as done in the
fifth embodiment of the invention, is applied as the main wire
component 25 to the medical guide wire 20A which is structurally
different from the previous medical guide wire 20. An entire
surface of the main wire component 25 is coated by a plastic film
such as, for example, a polyamide (Nylon 66) layer 28a which
contains a contrast medium (e.g., barium sulfate).
[0059] FIG. 15 shows a seventh embodiment of the invention in which
the metallic thin wire 1 is used to the medical tool and equipment.
In this instance, the metallic thin wire 1 is made of the
austenitic stainless steel and produced by any of the method
described from the first embodiment to the fourth embodiment of the
invention. The metallic thin wire 1 thus produced is applied as a
shaft 26 to the balloon catheter 21.
[0060] This results in the guide wire 20, 20A and the balloon
catheter 21 having a transmissible elongation made of the thin
metallic wire 1 to transmit a manipulation from the hand access
section 27 to the leading head portion 28. This enables the hand
access section 27 to transmit its push-pull and rotational movement
in quick response to the leading head portion 28 with a high
accuracy. This ensures a good maneuverability of the guide wire 20,
20A and the balloon catheter 21 so as to secure a quicker remedial
treatment against the diseased area.
[0061] When the metallic thin wire 1 is wrought out to have the
functionally gradient characteristics as done in the second and
third embodiments of the invention, and the metallic thin wire 1 is
applied to the main wire component 25 of the guide wire 20, 20A,
the functionally gradient characteristics makes the hand access
section 27 flexible while making the rigid leading head portion 28
rigid, thus significantly improving the mechanical property as
required for the guide wire 20, 20A.
[0062] In addition, the metallic thin wire 1 made of the austenitic
stainless steel as described from the fifth to seventh embodiments
of the invention has the following advantages as the guide wire 20,
20A.
[0063] When a martensitic stainless steel is used to the main wire
component 25 as shown in FIG. 13, it tends to harden with the heat
treatment so as to likely make a helical portion 30 and the main
wire component 25 partly stiffen in the neighborhood of the bulge
head portion 29 under the thermal influence produced at the time of
soldering the bulge head portion 29, thereby resultantly depriving
the leading head portion 28 of the favorable flexibility.
[0064] On the other hand, a ferritic stainless steel has the
property referred to as "475.degree. C. fragility" and having the
property called as "sigma fragility" occurred when heated to
approx. 600-800.degree. C. for an extended period of time.
Especially, the ferritic stainless steel makes the crystallized
particles grow to reveal "high temperature frailty" when heated to
950.degree. C. or more, thereby deteriorating the quality as the
medical guide wire due to the thermal influence brought by
thermally bonding the bulge head portion 29.
[0065] However, since the austenitic stainless steel is less
subjected to the textural metamorphosis when heated, it is less
affected by the heat generated at the time of thermally bonding the
bulge head portion 29. The austenitic stainless steel further has a
relatively small thermal conductivity and a greater coefficient of
thermal expansion which is approx. 1.5-1.6 times as large as that
of the general stainless steel. This means that the thermal
expansion and the thermal stress produced on the main wire
component 25 by thermally bonding the bulge head portion 29 are
absorbed by a limited area of the main wire component 25 in the
neighborhood of the bulge head portion 29. This alleviates the
residual stress produced by thermally bonding the bulge portion 29,
and thereby maintaining the good linearity and favorable
flexibility even in the restricted portion of the main wire
component 25 near the bulge head portion 29.
[0066] The thin wire 2 contracts and stretches in the lengthwise
direction when primarily and secondarily twisted alternately and
then processed with the heat treatment. Due to the greater
coefficient of thermal expansion of the austenitic stainless steel,
a stroke appeared when the thin wire 2 contracts and stretches
becomes longer to work out the outer surface of the thin wire 2 to
help it form a closely packed structure.
[0067] While on the other hand, the martensitic stainless steel has
a quench hardening property by which a tensile strength is
reinforced, the austenitic stainless steel increases its strength
when drawn (work hardening) so as to be well-suited to the medical
guide wire 20, 20A. Since an electric resistance of the austenitic
stainless steel is approx. five times as great as that of the
carbon steel, and is approx. 1.6 times as great as that of the
martensitic stainless steel. This alleviates an intensity of the
electric current necessary to thermally bond the bulge head portion
29, whereby limiting the thermally bonding heat to a necessary
minimum so as to lessen a bending and torsional deformation under
the influence of the heat generated by thermally bonding the bulge
head portion 29.
[0068] With the thin wire 2 specified by the austenitic stainless
steel, the thin wire 2 is magnetized and mirror-finished at its
outer surface when drawn by a dice tool. This attracts ferric
particles to the outer surface of the thin wire 2 and collects
foreign matters on the thin wire 2 with the help of the Van del
Waals' force based on the intermolecular affinity. When the foreign
matters are collected, the passive rust corrosion and the crevice
corrosion would occur between the outer surface of the thin wire 2
and the foreign matters so as to likely reduce a
corrosion-resistant property.
[0069] On the contrary, with the outer surface of the thin wire 2
electrolytically polished, oxidized scales are removed from the
thin wire 2 to restore an original concentration of chromium
component of the thin wire 2 so as to resultantly improve the
corrosion-resistant property.
[0070] As apparent from the foregoing description, the subject
method of making a metallic thin wire enables the artisans to mass
produce one single metallic thin wire with a high
rotation-following capability and high linearity (straightness)
provided. The one single metallic thin wire has such good
properties as to be appropriately applicable to main constituents
of high quality medical tools. This effectively enhances the
quality and the performance of the medical tools depending on their
usage so as to improve remedial skills and an efficiency of the
medical treatment.
[0071] It is to be noted that the primarily and secondarily
twisting procedures are combined to form a unitary set, and the
unitary set is repeatedly applied to the one single metallic thin
wire in a plurality of times.
[0072] Only the primarily twisting procedure may be applied to the
one single metallic thin wire without the secondarily twisting
procedure.
[0073] Metallic object to be primarily and secondarily twisted is
not merely confined to the one single metallic thin wire but also a
wire-stranded hollow tube in which the secondarily twisting turns
is one time the primarily twisting turns or less than that. In this
instance, the wire-stranded hollow tube is primarily twisted in the
same direction in which the wire-stranded hollow tube was
stranded.
[0074] Not only the austenitic stainless steel but other metallic
material may be applied to the one single metallic thin wire. After
the end of the heat treatment, the electrolytic polishing procedure
may be omitted.
[0075] The metallic thin wire may be used to not only the guide
wire and balloon catheter but also an endscope treating tool,
flexible type endscope and the like. The metallic thin wire may be
used to an actuation thin wire which requires the superior
rotation-following capability even except for the medical tool.
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