CN1389271A - Knitted medical internal metal rack and its making process - Google Patents

Abstract

The knitted medical inner stent of the present invention is made of nickel-titanium shape memory alloy wire, which has good medical properties and biocompatibility, and at the same time it also has superelasticity, light weight, strong corrosion resistance, and good fatigue resistance, compression resistance and tensile resistance. It is completely suitable for the human body, and the special design of the small-diameter knitting machine with straight and tapered needle cylinders can adapt to the nickel-titanium shape memory alloy wire with high hardness, high rigidity, poor bending performance, small elongation, and inner bracket diameter. Small features, can be put into production in batches, using double-needle knitting technology, so that the woven inner bracket has a uniform coil structure. It can be deformed to a maximum extent, and is convenient for implantation operation in the operation process. The product of the present invention is suitable for medical requirements both in material and structure, and its prospect is very optimistic.

Description

Knitted medical metal inner stent and manufacturing method thereof

The invention relates to a medical metal inner stent, in particular discloses a knitted medical metal inner stent, which belongs to the category of medical instruments.

Medical metal stent is one of the more advanced medical devices in the world. Its research history abroad is not long, and its domestic production is limited to manual and small batch production. In medicine, many diseases or operations cause certain luminal stenosis and obstruction, which affect health, and in severe cases, aggravate the disease and even endanger life. For this reason, people have used various instruments or air bags to expand or support the affected area, but the work is more complicated and may produce other complications. Using rubber or silicone tubes as airbag stents or supports is prone to aging, deformation, large tissue reactions, and inaccurate results. Commonly used stainless steel stents, titanium alloy stents, and polyurethane stents have disadvantages such as complex operation and insufficient fixation to varying degrees due to the limitations of the materials themselves. None of them can exist in the human body for a long time, which limits the development of surgical techniques to a certain extent. Nitinol stents not only have good tissue compatibility, but also have unique shape memory properties. Using this feature to place the stent into the body is easy to operate and easy to grasp. The stent is especially suitable for elderly and frail patients who are not suitable for open surgery. According to reports, at present, nickel-titanium alloy stents can be used to treat urethral obstruction, esophagus, biliary tract, and tracheal stenosis caused by benign prostatic hyperplasia. As a new palliative treatment, it has received good clinical results. Figure 1 shows the working principle of the nickel-titanium shape memory alloy stent. Taking the cardiovascular mesh braided stent as an example, the stent is first made into a certain shape according to the needs (Fig. 1(a)). Figure 1(b) shows the stenosis of blood vessels caused by various diseases such as tumors in the human body. Figure 1(C) shows the low temperature of the stent into a small shape that is easy to place in the body. Figure 1(d) shows the placement of the stent into the human body through a guide tube. After being heated by body temperature, the implanted stent can automatically restore its original shape and give moderate support and expansion force, support the inner lumen and combine with it to keep the blood vessels open and slow down the stenosis. Figure 1(e) shows the application results of partial vessel repair.

The prior art stents are divided into stainless steel stents, titanium alloy stents, nickel-titanium alloy stents, and tantalum wire stents according to the raw materials. The tissue structure is divided into spiral stent tubes and hand-woven mesh stent tubes. The spiral inner stent tubes are simple to make, cheap, firm in positioning, and easy to insert and take out. However, the inner surface of the stent is not homogeneous with human tissue, so it should not covered by. The hand-woven mesh stent tube has good homogeneity, good recovery performance, simple insertion process, less material, and stable structure, but this kind of stent is limited to hand-made, and the length of the stent required in the operation can only be customized, not according to the needs Cut at will.

The purpose of the present invention is to disclose a kind of knitted medical inner bracket and its manufacturing method. The inner bracket structure is a knitting weft flat needle structure bracket, which is woven on a small-diameter circular knitting machine. It has the advantages of hand-woven mesh brackets, It has good homogeneity and simple structure, and it can be disassembled when the corresponding tap is pulled, so it is very convenient to take out the bracket from the human body. , it and the helical inner stent can be cut at will as required.

The present invention is achieved in this way; a knitted medical metal inner stent, which is an inner stent tube composed of nickel-titanium shape memory alloy wire, is characterized in that the shape of the inner stent composed of nickel-titanium shape memory alloy wire is cylindrical, and the inner stent The structure is knitted weft flat stitch structure. Knitted medical metal inner stent, nickel-titanium shape memory alloy wire knitting weft plain needle structure uniformity inner stent structure, coil settlement arc section (1) and needle knitting arc section (2) are similar in shape and length, and can be used at low temperature Maximum deformation can be achieved. Knitted medical metal inner stent, nickel-titanium shape memory alloy wire knitted weft flat needle metal inner stent can have a diameter of 3mm to 28mm. Knitted medical metal inner stent, nickel-titanium shape memory alloy wire with a nickel content of 54-56%. The manufacturing method of the knitted medical metal inner stent adopts weaving on a special knitting machine, and the braided nickel-titanium shape memory alloy inner stent also goes through the stages of unwinding, lapping, closing, stripping, bending, and forming. It is: A.) adopting the method of increasing the pulling force and adding oil on the needle from time to time makes the phenomenon of needle latch backlash less likely to occur when the loop is withdrawn; B.) due to the high rigidity of the nickel-titanium alloy wire, it is not easy to deform, resulting in old The coil cannot be taken off normally. Select a latch needle with a high tongue height, which is beneficial to increase the size of the coil and facilitate the transfer between coils during knitting. Guarantee the smooth de-looping of the alloy wire; the manufacturing method of the knitted medical metal inner stent adopts the double-needle knitting technology, that is, two adjacent needles knit a large coil at the same time, so that the needle-knitting arc section and the subsidence arc section of the inner stent obtained are The length is close, and the amount of coil transfer and deformation in the low temperature state is large. The manufacturing method of knitted medical metal inner stent needs to normalize the alloy wire before weaving and anneal after weaving. Normalizing the alloy wire is to heat the alloy wire to a certain temperature, then cool it in the air and anneal it. The treatment is to heat the alloy wire above the critical temperature, and then cool it in the air after a period of heat preservation. cool down. A kind of special equipment for knitting medical metal inner stent products and manufacturing methods. The special equipment is a specially designed knitting machine. When the diameter of the inner bracket is less than 5mm, use a tapered syringe; when the diameter of the metal inner bracket is more than 5mm, use a straight or tapered syringe.

The present invention is further described below with accompanying drawing.

Accompanying drawing 1 is the working principle of the nickel-titanium memory alloy stent.

Accompanying drawing 2 is the product structure schematic diagram of the present invention.

Embodiment: The present invention is described in detail according to accompanying drawing. (1) Selection of raw materials

Type 316L and 317L stainless steels are widely used metallic biomaterials. However, in recent years, researchers at home and abroad are working hard to study the performance of nickel-titanium shape memory alloys and make such internal stents. The shape memory effect of nickel-titanium shape memory alloys is mainly used to greatly increase the compression ratio of the internal stents, thereby making the operation easier. For convenience, it can even be placed through an endoscope to treat diseases such as common bile duct stenosis, vascular stenosis, and urethral stenosis caused by prostatic hypertrophy, eliminating the need for open surgery and greatly reducing the pain of patients. The application prospect is very attractive.

The shape memory effect means that after special treatment, the memory alloy specimen with a certain shape will be obviously deformed at a low temperature (martensitic phase). After the specimen is heated to a certain temperature (phase transition temperature), the specimen can be It restores its original shape (austenite phase) and produces a large restoring force during the shape restoration process, so it has a wide range of applications in the field of engineering technology. According to reports, there are more than 20 kinds of alloys with shape memory effect, but the most promising development and application in the medical field is the nickel-titanium shape memory alloy with nickel content between 54-56%. Nickel-titanium shape memory alloy has the characteristics of shape memory effect, superelasticity, fatigue resistance, wear resistance, corrosion resistance and good biocompatibility. It is regarded as a new type of medical biofunctional material and has been widely used in clinical medicine. Wide range of applications. In recent decades, Japan, the United States, Germany, etc. have done a lot of basic research on shape memory alloys, and countries such as Europe and the United States have held many international conferences, and there are also many reports on medical clinical applications. my country's basic research on shape memory alloys began in 1979. Although it started relatively late, it can be said to be in an international leading position in clinical applications. The application of nickel-titanium shape memory alloys has gradually expanded from orthodontics, orthodontics, and surgical orthodontics to various internal stents for the treatment of diseases such as urethra, esophagus, bile duct, trachea, blood vessels, and rectal stenosis. Through a large number of investigations and studies, this subject selects nickel-titanium shape memory alloy as the material of knitted medical metal inner stent. It has the following characteristics: 1. The performance of nickel-titanium alloy related to medicine

Melting point: 1240-1310℃ Specific gravity: 6.45g/cm ³

Recovery temperature: 30-45°C, it can be determined according to special purposes

Tensile strength: σ _b = 1078-1300Mpa Elongation: δ = 20-40%

Fatigue point: 558Mpa Shear strength: 725-921Mpa

Elastic modulus (at 40°C) 22000Mpa Hyperelastic strain: >7%

Heating plastic strain: ≥8% Heating recovery stress: 400Mpa

Phase transition temperature: M _S ＝223K——343K

Young's modulus varies with temperature, as shown in Table 1.

Table 1 Relationship between Young's modulus and temperature temperature(℃) -10 0 twenty two 37 45 100 Young's modulus E(Gpa) 58.9 58.9 61.1 63.7 64.2 71.5 2. Histocompatibility and corrosion resistance (1) Toxicity

Pure metals are known to be potentially toxic to humans. Arranged by toxicity: mercury, cadmium, lead, chromium, antimony, osmium, zinc, manganese, silver, nickel, gold, tin, bismuth, copper, iron, palladium, vanadium, germanium, cobalt, and the toxicity of nickel metal is in the middle. Therefore, Chinese and foreign researchers take a cautious attitude towards the stability of nickel ions in nickel-titanium alloys, and study the toxicity and biocompatibility of nickel-titanium alloys from different angles. The results of the study show that nickel ions are stable in Nitinol. The histocompatibility of the alloy is better than medical stainless steel, similar to cobalt chromium alloy, and even better than cobalt chromium alloy in some aspects. In 1990, the U.S. Food and Drug Commission (FDA) approved Mitek's nickel-titanium bone rivets to enter the market. Nanjing Medical University and Southeast University have analyzed and tested nickel-titanium shape memory effect intravascular stents, and concluded that the alloy stent has good biocompatibility and has no obvious toxic and side effects. (2) Corrosion resistance

Nickel-titanium shape memory alloy has excellent corrosion resistance. The corrosion rates in seven media including artificial saliva, artificial sweat, Hand's physiological fluid, 1% Nacl aqueous solution and 0.05% hydrochloric acid are all less than 6.8×10 ^-5 mm/year, and the chemical resistance is extremely strong, far exceeding Normal limit dissolution rate. This corrosion resistance allows nickel-titanium alloys to exist in the human body for a long time. (3) Histocompatibility

After more than 20 years of painstaking research, Chinese and foreign researchers have found that nickel-titanium alloy meets the requirements of transplantation. Its tissue compatibility is unmatched by medical stainless steel, carbon fiber, and cobalt-chromium alloy. 3. Memory effect

Nickel-titanium shape memory alloy is a thermoplastic martensitic state transformation. By changing the specific gravity of nickel and using different heat treatments, one-way, two-way or multi-way shape memory effects can be obtained. The alloy will generate considerable force during the recovery process and can do different degrees of mechanical work. For example: 1mm ² nickel-titanium nails can generate 85kg of force during the recovery process. 4. Hyperelasticity

Nickel-titanium shape memory alloy can be interpreted as "flexibility in rigidity and rigidity in flexibility" and "combination of rigidity and softness". Under the same conditions, the residual deformation of nickel-titanium alloy is 1/10 of that of medical stainless steel, and the bending moment is 3/8 of that of stainless steel. 5. Other properties

Nitinol has a smaller specific gravity than stainless steel, and its modulus of elasticity is comparable to that of bone after proper heat treatment. These characteristics show that nickel-titanium alloys are essentially different from medical stainless steels. In general, Nitinol is dynamic and variable, and its mechanical properties are continuous, dynamic and elastic. (2) Special equipment - knitting machine design

Medical metal stents should be flexible in the human body and have a certain anti-compression effect in blood vessels, trachea and esophagus. The yarns in the weft-knitted fabric are arranged in coils, and the transfer between coils can occur, which has high elastic deformation and meets the requirements of medical metal stents.

The weaving principle of medical metal stents is the same as that of ordinary knitted fabrics, but it has its own characteristics:

A. The diameter of the syringe is small, ranging from 5mm to 30mm.

B. The syringe can be straight, but in order to meet the requirements of small diameter, the tapered syringe is better.

C. The range of wires that can be woven is 0.1-0.3mm, and the needle groove is usually larger than the ordinary needle groove.

D. Because the needle barrel is very small, only one loop forming system is used.

In order to meet different needs, the medical metal inner stent knitting machine should be a series of knitting machine systems. According to the test, the caliber of the inner bracket ranges from 3mm to 28mm, and the corresponding syringe caliber varies from 5mm-30mm. 1. Knitting needles

The latch needle is one of the main loop forming parts on the knitting machine. Its motion laws and mechanical characteristics will directly affect the knitting process performance and work efficiency of the knitting machine. Compared with ordinary knitting machines, the knitting machine for weaving medical metal inner stents requires the latch needles to have the following special properties in addition to the general performance: ● The height of the tongue should be as high as possible. The possibility is large, which is conducive to breaking off and forming circles, and there are also

Facilitate transfer between coils. ● The stroke of the latch needle is as small as possible, which is beneficial to reduce the height of the triangle. ● Because the metal wire coil puts a lot of pressure on the latch needle in the process of stripping, it is easy to damage the needle latch. therefore,

The hardness requirement of the latch needle is higher than that of the general latch needle.

In addition, in order to improve the wear resistance of the latch needle, steel with high chromium content should be selected;

The elasticity of the latch needle; through special processing technology to improve the smoothness of the hook, latch and needle bar. 2. Syringe

The needle cylinder is also one of the main parts of the weft knitting machine. According to its structure, it can be divided into two types: integrated type and steel sheet type. At present, steel-inlaid needle cylinders are commonly used on knitting machines, but due to the small-caliber characteristics of medical metal inner frame knitting machines, we choose integrated needle cylinders.

When designing and testing, we found that there are still several problems in weaving small-diameter metal inner stents:

(1) Since the caliber of the inner bracket is too small, the diameter of the syringe is required to be also small. But on the straight barrel, the triangular

Reasonable design and rational arrangement of the number of needles limit the reduction of the diameter of the syringe.

(2) When knitting on a straight needle cylinder knitting machine, due to the large pulling force on the tube blank, the knitting is soft

Metal wires with poor performance have less retractability, so there are certain difficulties in retreating and stripping.

(3) When designing the cam, in order to reduce the collision force between the cam and the knitting needle, it is necessary to reduce the starting angle and the pressure of the needle.

Angle, but the small circumference of small bore straight barrels limits this requirement.

For small-bore inner stents, we consider tapered barrels. Its advantages and disadvantages are as follows:

(1) The use of tapered needle cylinder is beneficial to reduce the braiding diameter of the inner stent tube.

(2) Compared with the straight needle cylinder, the tapered needle cylinder is easier to withdraw and take off the circle.

(3) When the tapered needle cylinder is used, the triangle design can be more convenient and feasible.

The angle can be enlarged appropriately. Because the diameter of the tapered syringe is relatively large at the height of the triangular area, the unfolded surface is relatively wide.

It is therefore not as restricted as a straight barrel. The triangle expansion radius of the tapered needle barrel is large, so that the triangle of the needle and the pressing

The angle of the needle triangle can be reduced during design, which reduces the impact of the triangle on the knitting needle.

(4) The processing of the tapered needle cylinder is complicated and difficult to process. The parameter design and calculation of the needle cylinder and the triangle are relatively

It's also more complicated.

After repeated trials and comparisons, we finally selected:

(1) The diameter of the medical metal inner stent is less than 5mm, and a tapered syringe is used.

(2) The diameter of the medical metal inner stent is more than 5mm, and a straight or tapered syringe is used.

When designing a tapered syringe, the taper of the syringe should be reasonable. Simultaneously, because the caliber of the syringe is small, there will be a phenomenon of unstable transmission during the transmission. Therefore, weaving is carried out in the way that the needle cylinder is fixed and the cam seat rotates. 3. Triangle

Since the barrel is tapered, the triangle is also tapered. For the convenience of installation, the outer surface of the triangle is cylindrical, and the inner surface of the triangle is conical. Considering that the expansion surface of the small-caliber tapered needle barrel is not very large, we use an integrated needle starting cam and needle pressing auxiliary cam. In order to prevent the triangle from rubbing against the needle cylinder when it rotates, the horizontal gap between the needle cylinder and the inner surface of the triangle is Δ=0.3mm. The syringe is fixed on the frame, the cam is fixed on the triangular seat, and the triangular seat is driven by a 76-tooth tooth plate to rotate. The pressing triangle can be adjusted longitudinally to adjust the length of the stitch. For the convenience of needle loading and needle replacement, a gap is made on the needle pressing triangle. 4. Yarn guide

On the small-diameter metal inner bracket knitting machine, the yarn guide has two functions: one is to lay yarn, and the other is to prevent needle latch backwash. Since the needle cylinder is tapered, the knitting needles are also arranged in a tapered shape, so the yarn guide is also tapered. Its taper is the same as the barrel. The thickness of the yarn guide is 2mm. The width of the yarn guide is designed as follows: when the knitting needle rises and retreats, and the coil retreats to the latch spoon, the yarn guide enters the working position to prevent the needle latch from backlashing and missing needles; , the yarn guide exits the working position. The central angle of the yarn guide surrounding the needle cylinder is within 75°, and the maximum enclosing angle is 120°. 5. Yarn feeding, pulling and transmission mechanism

(1) Yarn feeding mechanism: adopt passive yarn feeding method. Install a tension compensation device on the creel.

(2) Pulling mechanism: Considering that the metal wire is hard and smooth, after weaving into a circle, the pulling mechanism of the wire support

 It is difficult to roll and roll. When rolling, it can neither be crushed to change the shape of the bracket, nor can it be used

 It slips and affects the normal coiling, causing the wire support to relax, so that it cannot be knitted normally.

Weave. Therefore, the current test adopts negative pulling method, heavy hammer pulling.

(3) Transmission mechanism: engine with speed controller → bevel gear → 76-tooth large chainring → triangular seat →

triangle. (3) Weaving method 1. The process of weaving into loops

Like all knitted fabrics, the weaving of the nickel-titanium shape memory alloy inner stent with a plain stitch structure also goes through the stages of unlooping, lapping, closing, stripping, bending, and looping. 2. Coil shape

When using nickel-titanium alloy wire braided medical inner stent, it is required that the underfill coefficient of the inner stent is large, so as to facilitate the maximum coil transfer and deformation at low temperature. Since the diameter of the latch needle used by the knitting machine cannot be very thick, the distance between the two needles is relatively large, and then the inner support weaved, from the perspective of the coil shape, the settlement arc section of the coil is large, and the arc section of the needle knitting small, as shown in Figure 2. After many experiments, we finally adopted the double-needle knitting technique, that is, two adjacent needles knit a large coil at the same time, so that the length of the needle knitting arc section and the settlement arc section of the obtained inner stent are close, as shown in Figure 4 . The stent has a large amount of coil transfer and deformation in a low temperature state, and the effect is good. 3. Normalizing treatment before braiding and annealing treatment after braiding

(1) Normalizing treatment

The alloy wire is normalized, that is, the alloy wire is heated to a certain temperature, and then cooled in the air. place

The purpose of the treatment is to change the structure of the metal and improve the mechanical properties. After processing, most

In some cases, the alloy can bend the yarn into a loop normally. But sometimes there will be continuous broken wires during the weaving process

Phenomenon, product quality is not stable enough.

(2) Annealing treatment

Anneal the alloy wire, that is, heat the alloy wire above the critical temperature, and keep it warm for a period of time

Then, cool in air. This method can refine the coarse grains after forging and casting,

In order to improve its strength, plasticity and toughness, eliminate the uneven cooling and deformation during forging and casting.

internal stress caused by uneven shape, and at the same time eliminate castings and forgings due to excessive cooling during the cooling process

The resulting imbalance in the tissue reduces its stiffness. The annealing process we adopt is: in the metallographic

Heat to 460°C in an oven, hold for 45 minutes and cool in air. (4) Performance of knitted medical metal stents

The performance of the knitted medical metal stent braided with nickel-titanium alloy wire is as follows:

The phase transition temperature of the product woven by nickel-titanium memory alloy is 31°C. It can become small and soft in ice water at 0-4°C, which is convenient for medical operations, and it can return to its original state at human body temperature (about 37°C). The designed shape, and correspondingly generate restoring force, play the role of expansion, support and drainage. Because nickel-titanium alloy has specific shape memory function, excellent superelasticity, excellent wear resistance and corrosion resistance, and excellent biocompatibility, the medical inner stent made of it has good bending performance and can adapt to The natural curvature of the cavity. After insertion, it will be covered by new epithelium and become an integral part of the cavity. It has no toxic and side effects, and can be used as a long-term luminal stent to treat luminal stenosis.

Compared with medical metal internal stents produced by other methods, this product can be mechanized on a large scale and has the following advantages:

● There are no burrs on the surface of the inner stent, which is not easy to cause infection during medical use.

● The uniformity of the internal stent structure is good, so that the restoring force in all directions is uniform, which can make it expand evenly

Zhang is in the human body pipeline.

● The organizational structure of the inner stent allows the stent to be cut into any desired length and placed in the human body. the bracket

It can be placed in the body for a long time, even if it fails, it can be conveniently operated by simple operation or dismantled into wires

It can be easily removed with minimal damage to the inner cavity. This is of great significance in clinical application

righteous.

Beneficial effect of the present invention is summarized as:

1. The knitted medical stent is made of nickel-titanium shape memory alloy wire, its medical performance and biocompatibility

Good performance, at the same time it also has superelasticity, light weight, strong corrosion resistance and anti-fatigue, compression, anti-

It has good pulling performance and other characteristics, and is completely suitable for the human body.

2. Knitted medical stents woven with nickel-titanium shape memory alloy wires can become tiny,

Easy to place shape. Placed in the body, relying on body temperature or external heating, it will return to its original state by itself, supporting

Support the pipeline in the human body and combine it closely to ensure its smooth flow. The structure of the stent has good uniformity, and the expansion

When the recovery force in all directions is uniform, it can be fully applied to the expansion of the human body pipeline. This product can

 Cut to any length as needed. At the same time, it can be easily disassembled and taken from the human body after being used by the human body.

Out, reduce the patient's pain in multiple operations.

3. The special design of small-diameter knitting machine with straight cylinder and tapered cylinder can adapt to nickel-titanium shape memory alloy

The wire has the characteristics of high hardness, high rigidity, poor bending performance, small elongation, and small diameter of the inner bracket.

 Weaving a knitted inner stent that meets the requirements of medical operations.

4. The double-needle knitting technology can make the woven inner bracket have a uniform coil structure, and the coils can settle

The shape of the arc and needle-knitting arc sections is similar, and the deformation and transfer of the inner stent coil are large, which is beneficial to the inner

The maximum deformation of the stent at low temperature is convenient for implantation during medical surgery.

5. The weaving parameters in the weaving process of knitted medical metal inner stent have direct influence on inner stent diameter and coil shape.

Indirect influence. In general, when the alloy wire is thin and soft, under the premise that it can be weaved normally, it can be used

 With a small pulling tension and yarn feeding tension, the inner support is soft and the coil uniformity is good. But when alloy wire

When the diameter is thick, the pulling tension can be increased to improve its weaving performance.

In a word, the product of the present invention is suitable for medical requirements no matter its structure or material, and its prospect is very promising.

optimism.

Claims (8)

1, a kind of knitted medical internal metal rack, it is the inner support pipe that the niti-shaped memorial alloy silk is formed, and it is characterized in that the inner support shape that the niti-shaped memorial alloy silk is formed is a cylindrical shape, the inner support structure is knitting latitude plain construction.

2, knitted medical internal metal rack according to claim 1, it is characterized in that described niti-shaped memorial alloy silk knit latitude plain construction inner support even structure degree is good, coil sinker loop portion section (1) and needle loop portion section (2) plesiomorphism, length is close.

3, knitted medical internal metal rack according to claim 1 and 2 is characterized in that the flat pin internal metal rack of described niti-shaped memorial alloy silk knit latitude bore can be at 3mm～28mm.

4, knitted medical internal metal rack according to claim 3 is characterized in that used niti-shaped memorial alloy silk nickel content is 54～56%.

5, a kind of manufacture method of claim 1～4 knitted medical internal metal rack, employing weaves on the knitting machine of special use, braiding niti-shaped memorial alloy inner support also will through moving back circle, fill up yarn, remain silent, knocking over, kinking, these stages of lopping, it is characterized in that: take the crosspointer knitting skill, be that adjacent two pieces of pins weave a big coil simultaneously, make its needle loop portion section of inner support and the sinker loop portion segment length of gained approaching, coil transfer and deflection under low temperature state are big.

6, the manufacture method of knitted medical internal metal rack according to claim 5, needing it is characterized in that preceding normalized treatment of involutory spun gold braiding and the annealing in process after the braiding, it promptly is that the alloy silk is heated to uniform temperature that involutory spun gold carries out normalized treatment, in air, cool off then, annealing in process promptly is that the alloy silk is heated to more than the critical temperature, through in air, cooling off again after the insulation after a while, annealing treating process is: the alloy silk is heated to 460 ℃ in the metallographic stove, insulation is 45 minutes in stove, cools off in air then.

7, the manufacture method of knitted medical internal metal rack according to claim 5 is characterized in that: A) adopt to strengthen traction force and frequently on pin the method for oiling agent make to move back and be not prone to needle latch backwash phenomenon when enclosing; B) because of the rigidity of nitinol alloy wire big, not yielding, caused the normally knocking over of old coil, choose tongue and go up high higher latch needles again, increase coil when helping weaving and be convenient to transfer between the coil, help knocking over, pretreatment guaranteed the smooth knocking over of alloy silk to reduce its rigidity before the alloy silk was woven;

8, the special equipment of a kind of knitted medical internal metal rack product and manufacture method, it is characterized in that special equipment is custom-designed knitting machine, syringe bore scope is at 5mm～30mm, the preferential taper syringe that adopts, adopt one tunnel cam system, when weaving the medical internal metal rack bore when 5mm is following, adopt the taper syringe; The internal metal rack bore adopts straight shape syringe or taper syringe when 5mm is above.

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