JPS6039783B2 - Method for manufacturing underwoven fabric tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of needled nonwoven tubes.

More particularly, the present invention relates to the continuous production of nonwoven tubes with low weight per unit wall area and minimal diameter. Various attempts have been made in the past to produce tubular woven fabrics with structural properties suitable for industrial applications such as industrial furnaces and water removal, and for surgical applications such as vascular prosthesis. Early attempts used woven or knitted fabrics placed as sleeves around disparate structures or as tubular extensions between the end portions of ducts or fittings.

However, an important, sometimes critical, factor in the success of a tube in the above fields is the permeability of the woven tube. Moreover, of particular importance in many of these fields is the uniformity of the desired permeability over the entire length and area of the tube. Where the permeability changes, there is a corresponding change in flow rate, resulting in a loss of uniformity of operation.

Where the tube changes its structural properties during use and the permeability changes, the structure becomes correspondingly weaker in areas of greater permeability.

The weakening of the structure can then cause expansion or even failure of the tube wall. Previous attempts to improve the permeability of such tubes and to control their uniformity during tube manufacture include frayed fibers, beads, etc.

The inclusion of fabrics, such as a web or flocked web, and the tufting of the outer portion or surface of the web.
ng) and loop attachment.

However, more recent and better attempts have used unwoven or unwoven webs of strand material, commonly referred to as felted webs.

These felted material tubes have many advantages over woven or knitted material sleeves. A particularly useful and superior tube of needled nonwoven fabric is disclosed in the inventor's U.S. Patent Application No. 3, filed Aug. 8, 1973.
No. 86552' is disclosed.

Although these nonwoven tubes are required and have significant effectiveness in industrial applications such as filter media and roller sleeves, the most demanding requirements that these tubes must meet are in the field of surgery. In this field,
Human life directly depends on some quality of the tube. It is therefore appropriate to detail these strict conditions and their reasons.

It will be obvious to those skilled in the art that a tube that fully satisfies these surgical conditions will be equally effective in other industrial fields. When used as a vascular prosthesis, the precise permeability of the tube and its uniformity are absolutely necessary.

In this case, the transmittance conditions seem contradictory at first glance.

This is because the function of the tubular prosthesis is to substitute for diseased or damaged vascular sections and thus to act as a conduit for blood between healthy or undamaged vascular sections. Therefore, in this case it follows that the tube must be substantially impermeable to blood and its components. However, in order to achieve sufficient healing of the suture points and tissue development along the prosthesis, the tube wall structure must be made permeable to allow radial displacement of the cytoplasm and the tissue to be radially It is necessary to be able to transfer into the tube, enveloping the tubular prosthesis and forming a "living" blood vessel that is structurally supported by this prosthesis.

A successful solution to this apparent conflict is to pre-coagulate the permeable tube by sufficiently closing the wall gaps before installation so that the tube is impermeable during installation. -clotting) step to form a permeable tube that is initially made impermeable.
Finally, the coagulated substance is returned to its original state, and the cytoplasm enters the cell through the gap in the tube wall, and the coagulated substance is absorbed. However, the presence of pre-coagulated material makes the prosthetic odor potentially highly thrombogenic.

It is therefore essential that the structure of the tube adheres and retains all of the coagulated material in order to avoid release of the prosthesis and concomitant thrombus formation downstream of the prosthesis. This condition of creating an optimal surface for the attachment of coagulated substances also favors the successive progression of new tissue into and through the tube wall.

Therefore, the porosity and surface properties, along with precise control of permeability, are important for effective use of the tube.
However, the desired permeability must necessarily be uniform over the entire length of the tube and around its circumference.

If the permeability is below a preselected level, such a large variation from uniformity will prevent the passage of the desired components. Where areas of high permeability are present, excess components are transferred and the associated structural differences or deterioration causes weak sections of the tube wall to swell and bulge, resulting in ectatic arterial carcinoma. Or even destroy it. The nonwoven tubes of my above-identified U.S. Pat. It satisfies several conditions.

However, tube manufacturing requires layer winding, especially since tube winding equipment places tension on the tube.
Full synchronization of the tube winding speed and the tube winding speed is required.

These manufacturing problems are even more acute when producing the relatively small tubes now required for vascular prostheses. Conventional equipment includes a unit for winding and needling a nonwoven web on a mandrel, said mandrel forming a pick trough that causes the formed tube to move continuously parallel to the axis of the mandrel. grooves are provided in the length direction.

This prior art device is therefore limited to a relatively large diameter of approximately 4 mm for the extraction device, the actual size of which is determined by the size of the slide rollers and the length of their pins. A further limitation of the unit is the strength of the finished Chufu walls. There is that strength. Its strength should be at least about 4 skins. This is 350 to 4
It weighs 00 grams. These dimensions and weights are
cannot be reduced by the use of conventional evacuation mechanisms.
Therefore, conventional hand grenades, such as those described above, which extract and eject the tube, are expensive and have problems in operation and flexibility of the device. As stated above, conventional methods and apparatus for forming nonwoven tubes are completely unsatisfactory in all respects.

A first object of the present invention is to provide an improved system for manufacturing needled nonwoven tubes.

A second object of the present invention is to provide an improved system for manufacturing nonwoven tubes that are wound in overlapping layers and needled at various angles.

A third object of the invention is to provide a nonwoven tube that is wrapped in overlapping layers on a mandrel, needled at various angles, and pressed against the mandrel by external pressure rolls. A fourth object of the present invention is to provide a nonwoven tube that is formed by needling and rotating on a mandrel with an external drive roll.

A fifth object of the invention is to provide a nonwoven tube that is needled and formed on a mandrel, the nonwoven tube being fed from the mandrel by mutual rotation between a helical surface and the tube. It is to be.

A sixth object of the present invention is to form a material on a mandrel by needling at various angles while being pressed against the mandrel and being rotated by a rotating pressure roll.
and to provide a nonwoven tube that is delivered from a mandrel by rotation against a helical surface on the mandrel. A seventh object of the present invention is to provide a needled nonwoven tube that is formed on a mandrel, radially compressed, and then delivered from the mandrel. Broadly speaking, preferred embodiments of the invention include:
A tapered mandrel having a plurality of needle holes in its large diameter portion, a reciprocating rod having a plurality of needles aligned with each of the needle holes, and applying pressure to the tube to be formed. and at least one drive roll for rolling and needling the tube.

Preferably, the mandrel has a helical surface in a portion that is pressed by a drive roll downstream of the needle hole. According to the present invention, it is possible to continuously produce a high-quality nonwoven fabric tube having a diameter of 4 or 5 sides or less, a weight of 4 mm per unit wall area, and a high quality nonwoven fabric tube.

This can be accomplished without the need for special nonwoven preparation equipment by simply feeding a narrow strip of thin nonwoven material directly into the winding device. Therefore, the distortion and longitudinal orientation of the fibers typical of the prior art can be avoided, and the desired nonwoven tube with many fibers interconnected can be obtained, while the cost of the tube extraction equipment is lower. . Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in the accompanying drawings, the tube forming apparatus according to the invention comprises a conveyor, a nip roller 2, a stretching and transferring station including a first roll 3 and a second roll 4, and a tube forming apparatus for needling and tube-forming a pressed web. It consists of equipment including a conveyor 5 for feeding to a forming unit 6.

The web fed onto the conveyor may be a generally accepted commercially available web, or may optionally be precarded. The web is
Typically, it is constructed from fibers that are felted in a manner that extends generally parallel to and generally along the length of the fiber. The material of the web may be textile fibers, metal fibers, mineral fibers or filaments or mixtures thereof.

These fibers or filaments must be very thin and flexible. The tube forming unit 6 comprises a stationary mandrel 7 having a plurality of needle holes 8 for receiving reciprocating needles 9 of a needling head 10.
This mandrel 7 is tapered conically towards the discharge end away from the needling castle and is provided with a helical portion 11 . This helical portion is preferably formed with serrated threads 12 which then each taper outwardly towards the apex 13 of the downstream green.

The diameter of this thread gradually increases towards the center or middle of the helix, and from there it decreases again towards the discharge end. The spiral of the spiral portion is coaxial with the mandrel and tube axes. In a preferred embodiment, a cylindrical portion is connected downstream of the helical portion. On either side of the stationary mandrel is a pair of rollers 14 and 14', which are connected to a pivotably supported yoke 1.
5 and 15' are located substantially at each diametrical end of the mandrel.

The yokes 15 and 15' also include compression springs 16 and 16' and lever arms 17 and 1 to swing inwardly to force the rollers 14 and 14' inwardly toward the mandrel.
7'. roller 14,
14' is parallel to the tapered mandrel surface and is covered with rubber or other suitable material to provide driving friction against the tube "T" at predetermined locations on the mandrel. preferable.

The amount of pressure that the rolls exert on the tube can be adjusted by means of threaded handles 18, 18'. The rollers are driven by suitable variable speed drive means (not shown) via universal joints 19 and 19'. The embroidery head 10 is driven by conventional means. This head is connected to a stripper or foot member 20 which is bent to conform to the contour of the material in the needling area to prevent the needled material from being lifted up when the needle is withdrawn. The needles are barbed with the wide part of the barb facing the point of penetration to capture the fibers and pull them inwardly through the lower layers of the wound web (Mndings). . The needling procedure may be the same as that disclosed in the inventor's aforementioned US Patent Application No. 3,865,52'.

As seen in FIG. 1, the needles 9 are parallel to each other. Thus, needles located directly above the bag center of the mandrel 7 intersect the surface of the mandrel at a right angle, whereas needles located outward from the center of the axis intersect the surface of the mandrel at an angle greater than perpendicular. The crossing angle gradually increases as the needle moves away from the axis. Thus, the chewable product is needled by multiple needles at various different angles. The above conveyors 1, 5 and rolls 2, 3, 4,
are preferably all driven by a variable speed drive to provide the tube forming unit with a precise feed rate of the sliver or curve.

To stabilize this critical feed factor and initiate the desired lateral reorientation of the fibers, nip the web at a line speed slightly above the belt conveyor speed. The web is drawn in a thin form on the surface of the roll 3 by rotating the roll 3 at a circumferential speed considerably faster than the linear velocity passing through this nip roll, and then On a roll 4 rotating at a much lower circumferential speed, a partially jumbled web of fibers is collected with partially laterally reoriented fibers. This initial fiber redirection is further increased if rolls 3 and 4 are provided with a traction surface, such as a metal carded fabric. A stripping comb 21 is also arranged near the conveyor 5 for stripping the slide or web from the roll 4. The speed of conveyor 5 is matched to feed the web to drive roll 14 at the desired rate. Next, the operation of this device will be explained. In operation, a suitably prepared extremely thin sliver or web material is fed into roll 14, wound around it onto a mandrel, and subsequently needled at various angles to form a tube of nonwoven fabric. Form. Each needle penetration drives the fibers from the outer layer into the lower layer at an angle, and the wound web is secured and intertwined to form a continuous tube. The continuous tube thus produced is driven around a stationary mandrel by drive rolls 14 and 14', and due to the presence of the helical portion 11 against which it is pressed, it continuously feeds itself out,
or forced lateral displacement from a stationary mandrel.

This self-feeding effect is further enhanced by the contractility of the tube when it is so needled.

This shrinkage acts to prevent the tube from being removed, so it is necessary to apply tensile stress to remove the tube, but when the tube is sent out, the shrinkage and
The mandrel's taper and helical expansion work together.
In direct contrast to longitudinal stretching to remove the tube, tubes formed in accordance with the present invention are radially compressed over the helix and thus extruded from the mandrel without longitudinal distortion. The actual taper of the mandrel will depend on the type of fiber and its shrinkability during needling, but
．． The taper may be about 50 to 20.

Preferably, the helical portion is formed as a threadably replaceable mandrel component so that helices with different pitches may be used. The feeding speed of the tube can be determined by using different helical sections and drives.

can be changed by adjusting the speed of the controller,
This modifies the tube wall thickness for a given web intake speed. It should be noted that it is dynamically advantageous to feed the incoming web onto the surface of the drive roller 14.

As a result, by flattening or pressing the web between the drive roller 14 and the mandrel 7, the web is oriented and de-lofted (de-loH) prior to the needling step.
)do. This is preferably increased by positioning the final conveyor 5 almost tangentially to the rollers 14. In view of the foregoing, it is clear that the present invention provides a unique method and apparatus for manufacturing nonwoven tubes and a novel shape of tube that is radially compressed immediately after forming.

Radial compression of the tube wall not only creates a relatively thin wall, but also reduces the permeability of the wall structure, as can occur when a tube as described above is subjected to substantial longitudinal tension. It also has the strengthening effect (densify-1 increase eHect) of reducing its initial permeability without permanently changing or weakening the wall structure.

By continuously and uniformly feeding the tube as it is formed, uniform overlapping of turns and stitch locking are obtained.

This is extremely important in tubes with very thin walls and small diameters, and is also particularly advantageous in tubes of larger dimensions. Although other types and different thread profiles may be used, the serration profile disclosed herein has been found to provide particularly accurate and uniform tube delivery.

Tubes made in accordance with the present invention have advantages not only because they are non-woven tubes, but also as a result of the reliability achieved with very thin wall thicknesses and small diameter tubes for surgical applications such as vascular prostheses. It is particularly effective in medicine.
The tubes are manufactured in the range 4 to 30 millimeters, with wall thicknesses of the order of 0.5 millimeters. but,
It should be understood that the advantages of the invention also apply to tubes with a diameter greater than 3. Furthermore, although the utility of the present invention has been specifically described above in vascular prostheses, tubes according to the present invention may also be used in several industrial fields, including tanning and paper mills, and also as filter and water removal surfaces. be able to.

Various modifications can be made to the details of the invention described above without impairing the effects of the invention or departing from the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a simplified side view of a tube forming apparatus according to the present invention. 2 is a plan view of the apparatus of FIG. 1; FIG. FIG. 3 is an enlarged view of a portion of FIG. 2, but shows the tube molding unit with a portion omitted for clarity. 1 and 5... Conveyor, 2... Nip loaf, 3 and 4... First and second rolls, 6... Tube forming unit, 7... Stationary mandrel, 8. ...
... Needle hole, 9 ... Reciprocating needle, 10 ... Needling head, 11 ... Spiral part, 12.
...Screw thread, 14 and 14'...Drive roller, 15 and 15''...Yoke, 16 and 16'
・・・・・・Compression spring. FIG. IFIG. 2 FIG-wo

Claims (1)

Claims: 1. A stationary mandrel comprising a conical portion and a helical portion in sequence toward the discharge end; b. A stationary mandrel provided upstream of the discharge end of the mandrel for receiving a needle of a needling means. c) a rotating delivery means for rotating a series of overlapping turns of the web around the mandrel; and d for interconnecting the overlapping turns to form a tube. a needling means, and e the rotary feeding means comprises:
An apparatus for manufacturing a nonwoven tube, the apparatus comprising at least one drive roller positioned to engage a peripheral edge of the tube. 2. The manufacturing apparatus according to claim 1, wherein the diameter of the spiral portion increases in the feeding direction of the tube. 3. The manufacturing apparatus according to claim 2, wherein the diameter of the intermediate portion between both ends of the spiral portion is increased. 4. The apparatus of claim 1, wherein the helical portion includes threads that are triangular in profile and serrated, each of the threads tapering outwardly in a downstream direction. 5. The manufacturing apparatus of claim 1, wherein said drive roller is adjustably urged by a spring toward the surface of said mandrel. 6. Claim 5, wherein the drive roller is mounted on a yoke parallel to the adjacent surface of the mandrel and supported on at least one hinged lever arm.
Manufacturing equipment as described in section.