WO1998004399A1

WO1998004399A1 - Integral tube

Info

Publication number: WO1998004399A1
Application number: PCT/GB1997/001298
Authority: WO
Inventors: Nigel Edwin Wrigley; Norman James Stancliffe
Original assignee: Netlon Ltd
Current assignee: Netlon Ltd
Priority date: 1996-07-30
Filing date: 1997-05-12
Publication date: 1998-02-05
Anticipated expiration: 1999-01-30
Also published as: GB9615934D0; AU2782997A; GB2315702A; GB9709643D0

Abstract

In order to make an integral plastics material tube which has a wide range of diameter change and is suitable for the use for protecting or collating cables, a bi-planar diamond net tube (1) is extruded and the angle between one set of strands (2) and the other set of strands (3) is changed to cause the portions of the strands (2, 3) at their interconnections to rotate with respect to each other and cause the plastics material at the interconnections to be molecularly oriented into oriented joints that allow the angles between the sets of strands (2, 3) to be readily changed.

Description

Integral Tube

Background

Extruded, polymeric diamond integral net tubes manufactured using the process of GB 836 555. GB 928 954. or other extruded net processes, and also woven, braided tubes, are used as protective sleeves for a wide range of components and applications, because of their ability to be expanded and contracted over a range of diameters Similar rubes can be used for collation, to hold a number of components together The components can be for instance electric cables or tubes or hoses The "protection^"" may be to protect the components inside the sleeve or to protect external components, materials or persons from the components inside the sleeve

The extruded, integral tubes can be manufactured on relatively simple machinery, but are limited in the range of diameters over which a single tube can be applied, typically 2.5.1 or less.

The woven braided tubes can have a wide range of diameter change, with greater flexibility, but need complex, small diameter, circular weaving machines for their manufacture

It is desirable to combine the ease of manufacture of the extruded net tubes with the wide range of applications of the woven braided tubes.

A "swivel joint" was used in a N^'etlon Limited hat moulding net in the 1960's to provide ease of moulding hat forms and heat-setting to shape, so that the strands could swivel easily during moulding, but then retain shape after heat-setting. After yielding in one direction during the moulding operation, the jomt was then heat-set at its new angle The Invention

The present invention provides methods as set forth in Claims 1 or 3, integral tubes as set forth in Claims 4, 5 or 7, and the tube in use, positioned around one or more components to protect and or collate the component(s).

The invention provides rotational integral hinges as swivel joints beuveen the strands of one set and the strands of the other set. WTien initially changing the angle, the material that is oriented may originate in the strand, and it is possible that both the for instance infinitesimally thin layers forming the original interconnection between the strands and the adjacent material from the strands orient to form a joint in the finished product. The mechanism will depend on the form of the interconnection between the strands in the as-cast material.

In general, there is a very small intersection area between the strands, and the molecular orientation of the joints causes the joints to act like pivots so that the angle between the sets of strands can be readily changed. When the tube is expanded to pull it over one or more components, the strands do not flex or bend significantly at the joints, their stiffness being sufficient to apply sufficient torque to the joints to cause the joints to swivel; in other words, the tube on expansion yields by rotation at ώe joints more than by significant bending of the strands. In this way, the inner and outer strands act like two helical springs: they can be expanded until their turns are in contact almost along the whole of their lengths, and their resilience can provide some clamping as the strands tend to return to their as-cast configuration.

In general terms, the as-cast material (for instance the material after extrusion and passing over the sizing mandrel, if used) should exhibit some bi-planarity, but it is not required that there should be no or substantially no overlap between the inner and outer -, -^*> strands as it may be possible to make the product even if there is a large overlap of strand cross-sections. Furthermore, the product can be made from as-cast materials which are beyond bi-planar, for instance by extruding the inner strands into spiral grooves in a rotating sizing mandrel which are deeper than the inner strands, so that the sizing mandrel causes the outer strands to be pulled away somewhat from the inner strands; in any case, some separation can be obtained with normal extrusion techniques, eg a separation of not less than about 1 :30, or of not more than about 1 : 10, preferably about 1 :20, as a ratio of the thickness of the tube wall.

The sections of extruded strands vary somewhat along the lengths of the strands and only approximate to geometrical shapes. However, the strands preferably are of generally rectangular shape, taller than they are wide (though they may be considerably canted over), with a height to width ratio eg not less than about 1.3: 1 or 1.4: 1 and eg not greater than about 1.8: 1 or 2: 1. The strand sections could alternatively be of a special profile, eg as in GB 1 210 354.

The temperature at which the oriented joints are formed can be any temperature at which the plastics material is sufficiently solid for the joints to be mechanically swivelled; the relationship of the joint-pivoting modulus to the strand-bending modulus is not very temperature dependent, and the lower limit is determined by the particular products and polymer. With a suitable plastics material, the temperature could be room temperature and die orientation could be effected immediately before or during braiding or collating. Once the oriented swivel joint is formed, it is preferably not subsequently heat set, ie it is preferably not heated above a temperature at which it de-orients (heat setting an oriented plastics material requires constraining the plastics material to prevent any shrink back, heating to a temperature significantly above the orientation temperature, and cooling). Nonetheless, the rube could be heat set if desired, for instance in its fully-extended configuration.

The plastics material can be any suitable molecularly orientable material, preferred materials being polyamides, polyesters and polyolefms. Alώough said angle need be changed in only one direction, it is preferably changed in one direction relative to ώe as-extruded configuration and is ώen changed in ώe opposite direction. The amount by which ώe angle need be changed will vary according to ώe plastics material, ώe temperature and ώe rate of change. However in general, ώe angle change is preferably greater ώan about 15°, about 20°, about 30°, about 40°, or about 50°; ώe angle change is ώe total angle through which ώe angle is changed, as measured from one extreme position to ώe opposite extreme position (one of which extreme positions would be ώe starting position if ώe angle is changed in one direction only).

Preferably, the net formed by ώe sets of strands is a diamond net in which each set of strands makes approximately the same (but opposite) angle with ώe machine direction_. However, diis is not essential, and ώe angles can be different or one set of strands can extend in ώe longitudinal direction.

Preferred Embodiments

The invention will be further described, by way of example, with reference to ώe accompanying drawings, in which:

Figure 1 is a plan view of an as-cast tube for forming a braided tube in accordance with ώe invention;

Figure 2 is a plan view of ώe tube of Figure 1 extended to its maximum length;

Figure 3 is a plan view of ώe rube of Figure 1 compressed to its minimum length;

Figure 4 is a schematic isometric view of a typical interconnection beuveen two strands in an as-cast tube;

Figure 5 is a schematic elevation of ώe interconnection of Figure 4;

Figure 6 is an elevation showing the oriented joint after swivelling ώe interconnection of Figure 4; Figure 7 is a partly schematic plan view of a typical interconnection between two strands in a second as-cast tube,

Figures 8 and 9 are vertical sections along ώe planes VIII-VIII and IX-IX in Figure 7, Figure 10 is an isometπc view of ώe interconnection of Figure 7 but taken from a photograph of an actual interconnection,

Figures 1 1 and 12 coπespond to Figures 8 and 9, but show ώe oπented jomt after swivelling the interconnection,

Figure 13 is an isometπc view of the oπented jomt of Figures 1 1 and 12 but taken from a photograph of an actual joint,

Figure 14 is a schematic elev ation of a fust production machine. Figure 15 is a schematic elevation, showing a vaπation of Figure 14, Figure 16 is a schematic elevation of another production mactune. and Figures 17 and 18 illustrate Uvo uses of ώe braided tube of ώe invention

Figures 1 to 3

Figures 1 to 3 illustrate the invention as applied to a tubular diamond form integral net An integral diamond net tube 1 as cast by ώe extrusion process is shown in Figure 1 It consists of two sets of strands running in opposite helical directions, outer strands 2 and inner strands 3 If, at each crossing pomt of the inner and outer strands 2, 3, there is formed between the strands 2. 3 an integral rotational lunge jomt, ώe tube shown in Figure 1 can be readily expanded in length to ώe form shown in Figure 2. at which point its turns are in contact and it has its minimum diameter, or contracted in length to ώe form shown in Figure 3. at which point its turns are again in contact and it has its maximum diameter

Figures 4 to 6

Figure 4 shows ώe strands 2, 3 connected at an interconnection 4 in ώe as-cast form The machine direction is indicated as MD, and θ is the strand angle. If ώe strands 2, 3 are rotated m the direction of the arrows A or B, ώe interconnection 4 is subjected to rotational shear. If ώe rotational shear yield moment of ώe intersection 4 is less than the bending yield moment for the strands 2, 3, forces applied in directions of arrows A or B will cause ώe intersection 4 to yield in rotational shear before the strands 2, 3 yield in bending. If ώe intersection 4 is yielded first in one direction then optionally in the other, ώe intersection becomes oriented into an integral rotational hinge joint 5 as shown in Figure 6, forming a tubular net or braided tube 6 in accordance wiώ ώe invention.

Figures 7 to 13

The same references used as in Figures 1 to 6. The strand 2 is of generally rectangular section and has a heightwidth ratio of about 1.6: 1 but is somewhat canted over; ώe strand 3 is of similar section wiώ a height: width ratio of about 1.5: 1 but is very canted over. In this canted situation, height is measured in directions h and width is measured in directions w. In this case, there was some tearing of ώe material in ώe area 7 (Figures 1 1 and 13) during ώe orientation of ώe hinge joint 5. After formation of ώe integral hinge joint 5. ώe strands 2 and 3 are substantially further apart. In ώe as-cast net 1 of Figures 7 to 10. ώe distance apart of ώe strands 2 and 3 was about 1/20 of ώe net thickness; in the braided tube 6 of Figures 1 1 to 13, the distance apart was about 1 '8 of the net thickness.

Figure 14

Suitable equipment for manufacturing braided tubes 6 according to this invention is illustrated in Figure 14. The equipment comprises a suitable diehead 8 for manufacturing an integral bi-planar diamond net in accordance wiώ GB 836 555 or GB 928 954. a sizing mandrel 9 over which ώe diamond net ( 1 ) is cast, and spray nozzles or water jets 10 to cool and solidify ώe diamond net ( 1 ). The sizing mandrel 9 is fastened to the diehead 8. Downstream of ώe sizing mandrel 9 an expanding mandrel 1 1 is fastened to ώe sizing mandrel 9 by a towing wire or rod 12. A caterpillar haul-off 13 pulls ώe diamond net ( 1 ) over ώe sizing mandrel 9 and along a smaller diameter portion of the expanding mandrel 1 1 and ώen pushes ώe diamond net on to a larger diameter portion of ώe expanding mandrel 1 1. This causes ώe joints in ώe diamond net to rotate in ώe direction necessary to move from ώe form of Figure 1 towards ώe form of Figure 3. The smaller diameter portion of ώe expanding mandrel 1 1 may be of a similar diameter to ώe sizing mandrel 9 or it may be significantly smaller than ώe sizing mandrel 9. In this latter case, ώe tension generated in ώe diamond net by ώe caterpillar haul-off 13 to pull ώe diamond net off ώe sizing mandrel 9 may cause rotation of the interconnections 4 in ώe diamond net 1 from ώe form of Figure 1 towards ώe form of Figure 2. The diamond net (6) is ώen pulled off the expanding mandrel 1 1 by equipment 14 which may be a haul-off nip or a wind-up mechanism. The tension generated to pull ώe net off the expanding mandrel 1 1 will cause rotation of the joints within ώe net 6 towards ώe form of Figure 2.

Figure 15

As an alternative to ώe "towed" expanding mandrel 1 1 shown in Figure 14. a free- floating expanding mandrel 15 as illustrated in Figure 15 may be employed. This free- floating mandrel 15 is trapped between haul-off rollers 16 and a stop mechanism 17 which is formed by a stationary guide or by stationary rollers.

The caterpillar haul-off 13 as shown in Figure 14 and ώe driven haul-off rollers 16 shown in Figure 15 are interchangeable.

Figure 16

Figure 16 shows an arrangement in which ώe machine direction is vertical, and in which, in place of ώe expanding mandrel 1 1 or 15 of Figures 14 and 15. a smooth expanding ball 18 is used, trapped between haul-off rollers 16 and a stop mechanism 19 which may be a stationary ring. The net (1 ) is extruded into a water tank 20 and is turned around a roller 21 by ώe haul-off rollers 16. Example

A protective sleeve was formed as set out below. The equipment was as in Figure 16_.

Material: polyamide (Nylon)

Grade: high viscosity stabilized extrusion grade.

Die diameter: 31.75 mm.

Slot type: straight cut.

Slot widώ: 0.61 mm.

Slot depώ: 0.91 mm.

No. of outer slots: 17.

No. of inner slots: 17.

Strand (filament) cross-sectional shape: generally rectangular wiώ radiussed comers, as in Figures 8 and 9.

Outer strand maximum cross-section dimension: 0.83 mm.

Outer strand minimum cross-section dimension: 0.59 mm.

Inner strand maximum cross-section dimension: 1.00 mm.

Inner strand minimum cross-section dimension: 0.57 mm

Sizing mandrel diameter: 24.2 mm.

Expanding ball diameter: 40 mm

Running speed; 4 m/min.

Die rotation speed: 30 rpm.

Processing temperatures:

Die head 8 295°C

Water tank 20 10°C nominal

Mean diameter of as cast product on reaching expanding ball 18: 24 mm. θ on leaving sizing mandrel 9: 60°. θ on reaching expanding ball 18: 60°. θ on reaching maximum distortion over expanding ball 18: 120°. θ on reaching haul-off equipment 14: 60°. Product linear mass: 20 g<^*m. Product inner diameter (as cast): 20 mm. Maximum product inner diameter (flexed): 42 mm. Minimum product inner diameter (flexed): 4 mm. θ of product at maximum diameter: 165°.

Figures 17 and 18

A braided tube 6 of the invention is shown protecting a cable 22 in Figure 17 and collating three cables 23 in Figure 18.

The present invention has been described above purely by way of example, and modifications can be made within ώe spirit of ώe invention. The invention also consists in any individual features described or implicit herein or shown or implicit in ώe drawings or any combination of any such features or any generalisation of any such features or combination.

Claims

CLAIMS:

1. A method of making an integral tube, comprising: integrally extruding a plastics material tube formed of at least two sets of strands with ώe strands of one set at an angle to ώe strands of ώe oώer set, respective strands at an angle to each oώer being interconnected where ώe strands cross; and at a temperature below ώe melt temperature of ώe plastics material, changing ώe angle between one set of strands and ώe oώer set of strands, to cause ώe portions of ώe strands at ώe interconnections to rotate wiώ respect to each oώer and cause ώe plastics material m ώe interconnections of the strands to be molecularly oriented

2. The meώod of Claim 1. in which, at a temperature below the melt temperature of ώe plastics material, said angle is changed in one direction relative to ώe as-cast configuration and is ώen changed in ώe opposite direction relative to ώe as-cast configuration.

3. A meώod of making an integral tube, substantially as herein described wiώ reference to Figure 14 or Figure 15 or Figure 16 of ώe accompanying drawings or in the foregoing Example.

4 An integral tube made by the method of ώe preceding Claims

5 An integral plastics material tube comprising an outer set of strands in a helical configuration, an inner set of strands in a helical configuration wiώ ώe strands of ώe inner set at an angle to ώe strands of the outer set. respective strands of ώe outer and inner sets being interconnected where ώe strands cross by moleculariy-oπented joints which act like pivots to enable ώe angles between ώe portions of ώe strands at ώe joints to be changed, whereby ώe rube can be expanded in diameter by decreasmg ώe lengώ of ώe tube, passed over one or more components, and have its diameter reduced by increasing ώe lengώ of ώe tube to fit more closely on ώe component(s).

6. The tube of Claim 5, wherein ώe helix angles of the outer and inner sets of strands are in opposite directions.

7. An integral tube, substantially as herein described wiώ reference to Figures 4 to 6 or Figures 7 to 13 of ώe accompanying drawings or in ώe foregoing Example.

8. The tube of any of Claims 4 to 7, positioned around one or more components to protect and/or collate ώe components and/or protect oώer components, materials or persons from ώe components inside ώe tube.