GB2219063A - Method and apparatus for manufacture of an umbilical - Google Patents

Abstract

A method of and apparatus 10 for manufacture of an umbilical comprising a plurality of cables or conduits 13 utilises guide means 24 axially spaced apart in the longitudinal direction of the apparatus 10 and each comprising a guide plate 26 rotatable in an oscillating manner about a central axis extending substantially parallel with the longitudinal direction of the apparatus 10. Each guide means 24 has a plurality of guide positions 27a, 27b etc spaced radially from the central axis of rotation so that a cable or conduit 13 extending through the guide positions e.g. 27a of the two guide means 24 is maintained spaced from the central axis. The guide plates 26 of the guide means 24 are rotatable in an oscillating manner in unison with one another and one rotatable relative to the other, with the guide plate 26 of a second guide means 24 being constrained to rotate only through an angle range of less than +/-180 DEG more than the angle range of the guide plate 26 of the first guide means 24. Means e.g. a tapering head 19 is provided for securing and holding the resulting assembly of conductors 13 in a reversing lay orientation thereby to result in an umbilical of flexible construction. <IMAGE>

Description

METHOD AND APPARATUS FOR FORMING A FLEXIBLE MULTI-CONDUCTOR LINE This invention relates to a method of and apparatus for forming a plurality of conductors into a flexible multi-conductor line, and in particular, although not exclusively, to a multi-conductor line in the form of an umbilical in which a plurality of conductors, such as conductors for transmission of hydraulic fluid or fluid pressure and which plurality may include electrical conductors, are contained within a protective sheath.

One known method for the formation of a flexible multi-conductor line from a plurality of conduits entails winding the conduits about a central core member, which may itself be a conduit, in a manner in which successive sections of the length of each conduit extend around the central core alternately in clockwise and anti-clockwise directions. This technique sometimes is referred to as an SZ stranding or twisting technique; in this specification conductors positioned by an SZ technique are referred to as having a "reversing lay orientation". The use of a reversing lay orientation avoids the need necessarily to support large conduit supply spools on a rotating frame such as would be necessary if the conduits were to be spiralled continuously about a central core.

One technique for construction of an umbilical having a reversing lay orientation of conduits is described in the Patent specification of GB 2038988B (Multiflex); that specification also refers to a number of other prior known techniques. GB 2038988B apparently is directed particularly to a feature by which an attempt is made to avoid introducing twist and thus torsional stress into a conduit as it is being wound about a core member; it is alleged that the avoidance or reduction of such torsional stresses in the conduits enhances the durability and useful life of the resulting multi-conduit line.

Whilst the technique described in GB 2038988B may be effective for reducing or avoiding the introduction of torsional stress in each conduit during its laying about a central core, the technique requires that the conduits arranged around the central core all intermittently frictionally engage the core member at a position upstream of that at which the conduits and core member enter a closing block for securing together by taping means.

It is believed that the aforementioned intermittent frictional engagement can be undesirable and that there is a risk of components of the multi-conduit line becoming tangled at the point of frictional engagement. It is further considered that the risk of entanglement may arise especially in constructions in which a strip of filler material or other non-conduit member, provided for example to space two neighbouring conduits, is included in the laying operation to form the multi-conduit line.

The present invention seeks to provide an improved method of and apparatus for forming a multi-conductor line in which conductors are arranged in a reversing lay orientation and in which the above-referred requirement for intermittent frictional engagement between a plurality of conductors and a core member, (and the need necessarily to provide a core member) is eliminated.

In accordance with one of its aspects the present invention provides apparatus for constructing a multiconductor line from a plurality of conductors as the conductors are drawn in a generally longitudinal direction through the apparatus from pay-out reels comprising: first and second guide means axially spaced apart as considered in said longitudinal direction and each guide means being rotatable in an oscillating manner about a central axis extending substantially parallel with the longitudinal direction of the apparatus; each said guide means comprising a plurality of conduit guide positions spaced radially from said central axis of rotation whereby a conductor extending through guide positions of the two guide means may be maintained spaced from said central axis;; drive means for causing each guide means to rotate in an oscillating manner about a datum position and for the guide means to rotate one relative to the other, said drive means being operable to cause said guide means to rotate directionally in unison and for the second guide means to rotate only through an angle range of less than + 1800 more than the angle range of the first guide means, and securing means for securing and holding the resulting assembly of conductors in a reversing lay orientation as herein defined.

Each guide means may have a central guide position aligned with said central axis.

More than two axially spaced guide means may be provided, successive guide means being arranged to be rotatable relative to and directionally in unison with one another and with the downstream of the two guide means of each pair of successive guide means being arranged for rotation only through an angle range of less than + 1800 more than the rotation of the other, upstream guide means.

Said first, upstream guide means also may be arranged for rotation only through an angle range of less than + 1800, in this case the movement being that relative to said datum position. This is not, however, an essential requirement; if no conductor or other component extends centrally through the machine the first guide means may be arranged for oscillatory rotation through an angle range of + 1800 or more relative to the datum position.On the other hand, in order to facilitate a compact installation of payout reels and any guides leading conductors to the first guide means, it is appropriate to ensure that the first guide means is arranged for rotation only through an angle range of less than + 1800 relative to the datum position, typically that being a position which is stationary as considered relative to machine support structure provided for mounting the drive means and guide means.

The maximum permissible amplitude of relative rotation of successive guide means, and also the rotational range of the first guide means about the datum position to avoid contact between a member extending along the central axis and a conductor spaced radially therefrom will depend on geometrical considerations. In general, if a conductor extends between two guide means at a position close to the central axis (or at only a small angle particularly in the case of a conductor entering the first guide means) and if a central member has a cross-sectional dimension which is significant in comparison with the spacing between the conductor and central member, the angle range of relative rotation will need to be restrained to much less than + 1800, typically less than + 1350.

To attain a useful degree of rotational movement but without requiring an unduly space consuming apparatus the invention provides that the angle of relative rotation of successive guide means is + 900 and that the rotation of the first guide means about the datum position correspondingly is + 900. Thus, the first, upstream guide means will rotate in an oscillating manner between two positions 1800 apart, the second, downstream guide means will rotate between two angular positions which are 360 apart, and if a third guide means is provided, that will rotate through a total angular range of 5400.

Preferably each guide means is provided with a similar array of guide positions whereby, when the first guide means is aligned say with the datum position and the second guide means is similarly aligned a conductor extending through guide positions of the two guide means and radially spaced from the central axis of the apparatus will extend parallel with that central axis.

Each guide means may be in the form of a guide plate rotatably supported in a guide housing. The plate may be formed with openings for the passage of conductors therethrough. In a preferred embodiment the guide plate is formed from a sheet of low friction material such as nylon 66 having holes drilled therein to allow the direct movement of conductors therethrough without the need to provide relatively expensive swivel or like bearing arrangements in each guide opening.

The drive means may comprise a common drive shaft for simultaneous transmission of oscillatory rotational movement from a power source to each of two or more guide plates; to attain the required rotation of one guide means plate relative to the other different ratio gear trains may be provided at the respective guide means.

It is preferred that the drive means provide a non-constant, preferably a sinusoidal variation of, rotational speed of the guide means, the speed preferably being a maximum at a position (which typically may be at the datum position) mid-way between the extremes of rotational movement about the datum position.

The apparatus of the invention may include stationary guide means for selectively directing conductors to the first rotatable guide mean. The apparatus also may comprise support means for supporting a plurality of pay-out reels; in general it is envisaged that those pay-out reels should be rotatably supported for rotation about respective axes which are fixed relative to the datum position and support structure for the apparatus.

In accordance with another of its aspects the present invention provides a method for constructing a multi-conductor line from a plurality of conductors as the conductors are drawn in a generally longitudinal direction from pay-out reels comprising the steps of: providing first and second guide means axially spaced apart as considered in said longitudinal direction, each guide means being of a kind comprising a plurality of guide positions spaced radially from a central axis of rotation whereby a conductor extending through guide positions of the two guide means is maintained spaced from said central axis; feeding conductors from the pay-out reels, through respective guide positions in the first and second pay-out reels, passing the conductors through a securing means and bringing them into association with means for drawing the conductors through the apparatus;; operating said drawing means to simultaneously draw a plurality of conductors through the apparatus whilst simultaneously causing the two guide means to oscillate in unison about a datum position with the guide means rotating one relative to the other, and causing the second guide means to rotate through an angle range of less than + 1800 more than the angle range of rotation of the first guide means.

From the foregoing it will be appreciated that in this specification the reference to a + angle range of a specified angle means rotation from a reference position through that specified angle in both clockwise and anti-clockwise directions. That reference position may be the aforementioned datum position. Thus an angle range of movement of + 900 means, as considered in the case of a movement starting from the datum position, a rotation through + (say clockwise) 900 followed by a negative (say anti-clockwise) rotation through 1800 and then a + (clockwise) rotation through 900 back to the datum position.

The method of the invention may comprise the step of providing securing means to helically wind tape about the resulting bundle of reversing lay orientation conduits so as to preserve that lay orientation during subsequent processing or use of the bundle of conduits.

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a side view of apparatus in accordance with one embodiment of the present invention; Figure 2 is an end view of one of the guide means of Figure 1; Figure 3 is an end view of the fixed guide means of Figure 1; Figure 4 shows the lay of a conduit of an umbilical manufactured in accordance with the present invention; Figure 5 shows a modified form of the apparatus of Figure 1, and Figure 6 shows the lay of a conduit positioned in accordance with another embodiment of the method of the invention and the lay of a conduit of a prior art multi conduit.

Apparatus 10 for constructing an umbilical of electrical and hydraulic conductors by a method in accordance with the present invention is shown in Figure 1.

The apparatus comprises a creel frame 11 having, say, seven fixed spindles (not all shown) each for rotatably supporting a pay-out spool 12 which carries a required length of an electrical conductor or an hydraulic conduit type conductor 13.

Downstream of the creel frame there is provided an entry guide 14 (see also Figure 3) comprising four rotatable rollers 15 which define a rectangular opening 16 through which the conductors 13 from the seven spools 12 all extend. The entry guide 14 is supported by and movable longitudinally along part of the length of a machine support frame 17.

The entry guide 14 is positioned in the region of one end of the machine support frame. The other end region 18 of the machine support frame supports a consolidating die 32 also movable longitudinally along part of the length of the machine frame and a taping head 19. The taping head 19 has two support arms 20 each of which ca rries a reel 21 of tape 22,

such as a tape of Mylart, the reels being arranged such that in operation of the taping head the tapes serve to secure into a bundle those conductors passing through the taping head and which have been consolidated by the die 32. The tapes are arranged to be wound spirally in an overlapping configuration.

Downstream of the taping head 19 a caterpillar draw machine 23 of conventional kind is provided to draw the taped assembly of conductors through the apparatus.

Between the entry frame 14 and taping machine 19 the machine support frame 17 supports three conductor guide means 24. Each guide means (see also Figure 2) comprises a guide frame 25 in which a circular guide plate 26 is rotatably supported for controlled rotation. The guide plate is formed from a sheet of low friction material and is provided with seven guide positions 27 each for direct contact by and guidance of a respective conductor 13. One guide position 27a is a central opening aligned with the central axis of the machine and about which the guide plate is rotatable. The other guide positions 27b are uniformly disposed about and spaced from said central axis.

The outer periphery of each guide plate is formed with a ring gear 28 to facilitate controlled rotation of the guide plate by a drive shaft 29 (see Figure 1) which simultaneously transmits drive to each guide means from a drive unit 31 attached to the machine frame.

Each guide frame 24 carries a gear train 30 of two gears arranged to transmit drive from the shaft 29 to the ring gear 28 of the guide plate 26. The gear ratios are selected such that the guide plate 26 nearest the entry guide 14 rotates between positions which lie + 900 relative to a midway datum position fixed relative to the machine frame. That is, that plate is rotatable alternately through 1800 clockwise and 1800 anti-clockwise. The intermediate guide plate is rotatable between angular positions which lie + 900 greater than the positions between which the upstream guide plate is rotatable. Likewise the downstream guide plate, being that nearest the taping head 19, is rotatable between angular positions + 900 greater than the positions between which the intermediate guide plate is rotatable.Accordingly the intermediate guide plate is rotatable in an oscillatory manner to alternately undertake excursions of 3600 clockwise and 3600 anti-clockwise, and the downstream guide plate is rotatable alternately to undertake excursions of 5400 clockwise and 5400 anticlockwise.

Two of the guide means 24, the upstream and intermediate guide means are longitudinally movable relative to the machine frame 17; the downstream guide means is fixed to the machine frame. To facilitate longitudinal movement of the upstream and intermediate guide means the drive shaft 29 is formed with splines for engagement with the gears 30 of the upstream and intermediate guide means 24.

The drive means 31 comprises an electrical motor and a gearbox unit arranged to cause alternating clockwise and anti-clockwise rotation of the drive shaft 29 through a controlled angular range. The drive means is of a kind which incorporates a suitable D.C.

motor control to result in a sinusoidal variation of the speed of the drive shaft.

In use of the apparatus conductors are drawn from the pay-out reels 12 to extend through the entry guide 14 and respective holes 27a,27b in the three guide plates 26, then through the taping machine into engagement with the caterpillar draw unit 23. The conductors initially are uniformly fed through the three guide plates, with the three guide plates having their openings in alignment, such that one conductor extends centrally along the central axis of the machine and is surrounded by six uniformly spaced conductors which each extend between the upstream and downstream guide plates in a direction parallel with said central axis.

In operation of the machine, the progressively increasing range of oscillatory movement of the conductors as they pass from the first upstream guide plate to the intermediate guide plate and then through the downstream guide plate results in them extending in a helical manner about the central conductor in the region of the taping head and in consequence there results a reversing lay orientation of six of the conductors about the central conductor as they enter the taping head. At the taping head the spirally wound tapes 22 draw the surrounding conductors onto the central conductor and maintain that bunched relationship and reversing lay orientation in the resulting product as it is drawn from the apparatus by the draw unit 23.

In use of the machine the positions of the entry guide 14, the upstream and intermediate guide means 24 and taping head 19 relative to the direction of the length of the machine are adjusted as necessary to ensure that until reaching the taping head the six conduits which pass through the guide holes 27b do not contact the central conduit at any position downstream of the entry guide 14.

It is not essential that each opening in the guide plate be used or be used for the passage of a conductor. One or more of the openings may be used for the guidance of a strip of filler material provided to occupy any significant space that would otherwise exist in the finished umbilical.

The umbilical constructed using the aforementioned apparatus may have a covering layer applied, for example an extruded sheath or a metallic armouring of braided wire applied by conventional techniques.

The reversing lay orientation of the conductors which have passed through the guide plate openings 27b is apparent from Figure 4 which shows the resulting lay of one conduit 13 of the resulting umbilical.

In a second embodiment of apparatus in accordance with the invention, illustrated with reference to Figure 5, the intermediate guide means is eliminated and use is made of a spaced pay-out spool arrangement which causes the conduits 13 to approach the upstream guide means at a substantial angle relative to the central axis. Other details of the apparatus correspond in essence with those of the first embodiment of the invention. The consequence of the large angle at which the conduits approach the upstream guide plate is that that plate may be oscillated between positions which lie in the order of + 160c relative to a datum position, i e the plate may be alternately rotated 3200 clockwise and 3200 anti-clockwise without risk of the conduits spaced from the central axis contacting a conduit at the central axis.Therefore, the downstream plate, which oscillates between positions + 2700 relative to the datum position oscillates between positions which lie + 1100 greater than the positions between which the upstream plate oscillates. Although there is a greater relative rotation of the two plates 26 in this embodiment of the invention, by sufficiently closely positioning the two plates avoidance of intermittent frictional contact between the surrounding conduits and the central conduit may readily be avoided at all times except if use is made of a central conductor the diameter of which is very significant in relation to the spacing of the openings 27b from the central opening 27a of each guide plate.

It is not essential that the downstream guide means be arranged to oscillate through an angle range of t 2700 relative to a datum (i e total alternating excursions of 5400 clockwise and 5400 anti-clockwise), though often this angle range and the resultant axial spacing of the node points at which the conduits change direction will be found to result in good flexibility of the resulting umbilical. Where a high flexibility feature is not required a lesser rotation of the guide means to result in a conduit lay of, say, 3600 angle range may be sufficient.

In Figure 6 curve A shows the lay of a conduit positioned using the above-described apparatus of Figures 1 to 3 but operated for oscillatory motion of the guide plates through a lesser angle range, and curve B shows the lay of a conduit positioned at the same pitch using the prior art apparatus of the above-referred GB 2038988B; in each case the apparatus is arranged to result in a 3600 angle range of the conduit. In the case of the prior art method the uniform rotational speed and sharp change in direction of rotation due to the use of a pair of alternately engageable clutches results in essentially sharp node points 60. These are considered undesirable for an umbilical intended to have a good fatigue life.

In contrast, by the use of a non-constant rotational speed and especially a lower rotational speed close to the occurrence of change of rotational direction, such as the sinusoidal speed variations of the apparatus of Figures 1 to 3 and 5 of the present invention, much smoother node points 61 are attained. These are considered beneficial to the fatigue life of the resulting umbilical.

Claims (22)

CLAIMS:

1. Apparatus for constructing a multi-conduit line from a plurality of conduits as the conduits are drawn in a generally longitudinal direction through the apparatus from pay-out reels comprising: first and second guide means axially spaced apart as considered in said longitudinal direction and each guide means being rotatable in an oscillating manner about a central axis extending substantially parallel with the longitudinal direction of the apparatus; each said guide means comprising a plurality of conduit guide positions spaced radially from said central axis of rotation whereby a conduit extending through guide positions of the two guide means may be maintained spaced from said central axis;; drive means for causing each guide means to rotate in an oscillating manner about a datum position and for the guide means to rotate one relative to the other, said drive means being operable to cause said guide means to rotate directionally in unison and for the second guide means to rotate only through an angle range of less than + 1800 more than the angle range of the first guide means, and securing means for securing and holding the resulting assembly of conduits in a reversing lay orientation as herein defined.

2. Apparatus for constructing a multi-conductor line from a plurality of conductors as the conductors are drawn in a generally longitudinal direction through the apparatus from pay-out reels comprising: first and second guide means axially spaced apart as considered in said longitudinal direction and each guide means being rotatable in an oscillating manner about a central axis extending substantially parallel with the longitudinal direction of the apparatus; each said guide means comprising a plurality of conductor guide positions spaced radially from said central axis of rotation whereby a conductor extending through guide positions of the two guide means may be maintained spaced from said central axis;; drive means for causing each guide means to rotate in an oscillating manner about a datum position and for the guide means to rotate one relative to the other, said drive means being operable to cause said guide means to rotate directionally in unison and for the second guide means to rotate only through an angle range of less than + 1800 more than the angle range of the first guide means, and securing means for securing and holding the resulting assembly of conductors in a reversing lay orientation as herein defined.

3. Apparatus according to claim 1 or claim 2 wherein each guide means has a central guide position aligned with said central axis.

4. Apparatus according to claim 1, claim 2 or claim 3 comprising more than two axially spaced guide means, successive guide means being arranged to be rotatable directionally in unison with one another and with the downstream of the two guide means of each pair of successive guide means being arranged for rotation only through an angle range of less than + 1800 more than the rotation of the other, upstream guide means.

5. Apparatus according to any one of the preceding claims wherein the guide means lying upstream of the or all other rotatable guide means is arranged for rotation only through an angle range of less than + 1800 relative to said datum position.

6. Apparatus according to any one of the preceding claims wherein the angle range of relative rotation of two rotatable guide means is less than + 1600.

7. Apparatus according to claim 6 wherein said angle range of relative rotation is less than + 1350.

8. Apparatus according to claim 7 wherein said angle range of relative rotation is substantially in the order of + 900.

9. Apparatus according to any one of the preceding claims wherein each guide means is provided with a substantially similar array of guide positions.

10. Apparatus according to any one of the preceding claims wherein said rotatable guide means comprises a rotatable plate.

11. Apparatus according to claim 10 wherein said plate is formed from low friction material.

12. Apparatus according to any one of the preceding claims wherein said drive means comprises a common drive shaft for simultaneous transmission of oscillatory rotational movement to each of two or more said rotational guide means.

13. Apparatus according to claim 12 wherein a rotatable guide means comprises a gear train for transmission of drive from the drive shaft to a rotatable guide component of the guide means.

14. Apparatus according to any one of -the preceding claims wherein the drive means is operable to provide a non-constant rotational speed to the guide means.

15. Apparatus according to claim 14 wherein the drive means provides a sinusoidal variation of speed.

16. Apparatus according to claim 14 or claim 15 wherein the rotational speed is a maximum mid-way between the extremes of rotational movement about the datum position.

17. Apparatus for constructing a multi-conductor line constructed and arranged substantially as herein before described with reference to Figures 1 to 3 and Figure 5 of the accompanying drawings.

18. A method for constructing a multi-conductor line from a plurality of conductors as the conductors are drawn in a generally longitudinal direction from pay-out reels comprising the steps of: providing first and second guide means axially spaced apart as considered in said longitudinal direction, each guide means being of a kind comprising a plurality of guide positions spaced radially from a central axis of rotation whereby a conductor extending through guide positions of the two guide means is maintained spaced from said central axis; feeding conductors from the pay-out reels, through respective guide positions in the first and second pay-out reels, passing the conductors through a securing means and bringing them into association with means for drawing the conductors through the apparatus;; operating said drawing means to simultaneously draw a plurality of conductors through the apparatus whilst simultaneously causing the two guide means to oscillate in unison about a datum position with the guide means rotating one relative to the other, and causing the second guide means to rotate through an angle range of less than t 1800 more than the angle range of rotation of the first guide means.

19. Method according to claim 18 and comprising provision of securing means to helically wind tape about the resulting bundle of reversing lay orientation conductors.

20. Method according to claim 19 wherein a pair of tapes are helically wound in an overlapping manner.

21. Method according to any one of claims 18 to 20 wherein the plurality of conductors comprises at least one conduit.

22. Method for constructing a multi-conduit line from a plurality of conduits substantially as hereinbefore described with reference to Figures 1 to 3 and 5 of the accompanying drawings.