A METHOD AND APPARATUS FOR PRODUCING FLEXIBLE TUBES OF ANY LENGTH

Abstract: A method and apparatus for producing flexible tubes of any length from several superposed strips (12) of rubber and/or rubber reinforced with textile and/or metal fibres. The apparatus comprises a wrapping machine (1) and a vulcanizer (2) arranged in series on a common axis along which a core (3) can move, the strips (12) constituting the various sections of tube being deposited on the core and subsequently vulcanized.

Description: A method and apparatus for producing flexible tubes of any length The present invention relates to a method for producing flexible tubes of any length from several superposed strips of rubber and/or of rubber reinforced by textile and/or metal fibres, and in some cases by a reinforcement applied in a spiral, and to apparatus for performing it, comprising: a wrapping machine for depositing the strips around an elongate cylindrical core, the wrapping machine including a trolley which moves on rails; and a vulcanizer for receiving the core covered with the strips to produce the finished tube. Methods and related apparatus for producing sections of flexible tubing of limited length are known and provide for the use of wrapping machines and vύlcanizers which are independent of each other. In these methods, a cylindrical core is rotated about its own axis whilst a wrapping machine moves parallel thereto and winds strips of rubber and/or fibre-reinforced rubber around the core. The covered core is then inserted in a vulcanizer separate from the wrapping machine and the finished tube is then vulcanised. Obviously, it is not possible to use apparatus longer than a given limit, since it would not be very easy to use, excessive stresses would be created due to the rotating masses, and operations such as the removal of the vulcanized tube from the core would be very difficult. Nevertheless, according to the prior art, it is possible to obtain tubes of the desired length by joining several individual sections together, for example, by means of flanges. However, such tubes do not have the same mechanical characte istics at the joints as in the continuous portions. The object of the present invention is to provide a method which enables continuous flexible tubes of any length to be produced, and apparatus for carrying it out. The subject of the present invention is constituted by a method of producing the flexible tubes described above, characterised in that it comprises the steps of: fitting an unvulcanized end of a previously-wrapped first section of tube onto a first end portion of an elongate cylindrical core; covering the rest of the core with a plurality of superposed strips of rubber so as to form a second section of tube as an extension of the first section; inserting the core into a vulcanizer, an end portion of the second section opposite that adjacent the first section being left outside the vulcanizer; carrying out the vulcanization so as also to join the two sections; separating at least part of the core from the portion of tube constituted by the two sections; and repeating the above operations until the tube has reached the desired length, using as the first section of tube at any time the entire portion of tube produced up to that time. A further subject of the present invention is apparatus of the type indicated above, characterised in that: the wrapping machine and the vulcanizer are arranged in series and define a common axis along which the core can move; the trolley has a through-hole for the passage of the core in correspondence with the common axis, and has at least one head which rotates about the axis and carries at least one reel bearing the strips of rubber to be deposited; the vulcanizer has holes in its ends, in correspondence with the common axis, and has means therein for sealing against the core covered by the strips deposited by the trolley; and in that it includes propulsion means for moving the core from the vulcanizer to the wrapping machine and vice versa along their common axis, and means for supporting the moving core. Advantages and characteristics of the present invention will become clear from the detailed description which follows with reference to the appended drawings, provided by way of non-limiting example, in which: Figure 1 shows a diagram of apparatus for carrying out a method according to the invention. Figures 2a, 2b and 2c show a method for superposing the various strips of rubber constituting a section of tube on a core, Figure 3 is a diagrammatic front view of the trolley of the apparatus of Figure 1 with parts removed, Figure 4 is a side view of the trolley of Figure 3, Figure 5 is a section of the vulcanizer taken on the line V-V of Figure 1, Figure 6 is a section of the vulcanizer at another stage of operation, taken on the line V-V of Figure 1, Figure 7 is a section of a detail of the vulcanizer of Figure 1 taken on the line VII-VII of Figure 5, Figure 8 is a section of a detail of the core of Figure 1. Figure 9 is a perspective view of one of the pantographs of Figure 1, Figures 10a to lOi show schematically some stages of another method according to the invention, Figures 11a to Hi show another method for joining sections of tube according to the invention. An apparatus for producing flexible tubes of any length from several superposed strips 12 (Figure 2) of rubber and/or fibre-reinforced rubber comprises (Figure 1) a wrapping machine 1, a vulcanizer 2, a core 3 which moves between these two pieces of equipment, and a reel 4 for collecting the finished tube 5. The wrapping machine 1 includes a trolley 6 which moves on rails 7 and carries on each of its two faces 8 a head 9 which, by virtue of a motor 20 (Figures 3 and 4), rotates about a hole 21 through the trolley for the passage of the core 3. Each head 9 carries an arm 10 with a regulator 24 for adjusting its angle of inclination to the core 3, and the arm supports a reel 11 on which the strips 12 to be deposited around the core 3 are wound in succession. A motor 22 enables a bush 23 to rotate independently around each head 9 and, by means of the arm 25, the bush is able to carry a reel, not shown, from which a bandage can unwind to surround the already-deposited strips and compact them. The trolley 6 can move in two directions by virtue of a motor 26 which drives a pinion 27 that engages a rack 28 carried by the rails 7. There are two belts 28 within the trolley 6 for supporting the core 3, and these are driven by the motor 26 through a kinematic mechanism 31, so that their velocity is equal to and opposite that of the trolley 6, thus preventing slippage between the core 3 and the belt 28. Idle rollers 29 are arranged in succession above the core 3. The rollers 29 and the belts 28 together prevent the misalignment of the core 3 relative to the hole 21 as a result of the radial forces exerted by the strips- 12 during the deposition stage which will be described below. The trolley 6 also houses a clamp 30 which can be clamped onto a reduced-diameter portion of -the core 3 to make it fast with the trolley 6 and enable it to be propelled thereby. The elongate cylindrical core 6 is hollow (Figure 8) and within it are a small tube 40 for the passage of cooling air and a small tube 41 which communicates with the outer surface of the core 3 by means of holes 42 through which air can pass to separate the vulcanized tube 5 from the core 3. Moreover, in correspondence with its end opposite that which faces the vulcanizer, the core has a reduced-diameter portion, not visible in the drawings. This portion can be engaged by the clamp 30 carried by the trolley 6 during the movement stages, and by a fixed clamp 14 located at one end of the rails 7 when the core is stationary, to prevent it from rotating about its own axis. When the core 3 is in correspondence with the wrapping machine 1 (as shown in Figure 1), it is supported by support means 54 mounted on pantographs 15 located in a trench 16 formed beneath the path of the trolley 6, the means 54 being movable between a withdrawn position in which they do not interfere with the movement of the trolley 6 and an extended position for supporting the core 3. Each pantograph 15 is driven by a motor 50 which lowers it in correspondence with the approach of the trolley 6. Each pantograph 15 (Figure 9) carries the support means 54 for the core 3, which include supports 51 and a roller 52 which is rotatable about an axis perpendicular to the core and movable in a plane perpendicular thereto. The supports 51 support the core 3, covered by the strips 12, when it is stationary, without damaging the still-raw rubber of the strips 12 by virtue of the large surface area of contact which they provide. The rollers 52 are raised when the core 3 starts to move, supporting it and rotating about their own axes without harmful mutual slippage. The vulcanizer 3 is arranged in series with the wrapping machine 1 and defines therewith a common axis 17 along which the core 3 can move, as will be described below. The vulcanizer 2 (Figure 7) has holes in both its ends 66, in correspondence with the common axis 17, and sealing means constituted by inflatable toroidal sleeves 60 are provided near the ends. Once inflated through a tube 62, these can come into contact with a circumferential surface of the outermost of the strips 12 covering the core 2, ensuring the sealing of the vulcanizer 2. In the event of the breakage of a sleeve 60, most of the vapour can be discharged through an aperture 63 formed in a safety chamber 64, since a rigid rubber sealing ring 65 ensures a separate, though obviously not perfect, seal in correspondence with the holes in the ends 66 of the vulcanizer 2. Means 67 for supporting the core 3 are located within the vulcanizer 2 (Figures 5 and 6). Each of these comprises a roller 68, which is rotatable about an axis 69 perpendicular to the core 3, and a support 70 which is movable in a plane perpendicular to the core 3. The supports 70 support the core 3, covered by the strips 12, when it is stationary, without damaging the rubber of the strip 12, which at certain stages is still raw, by virtue of the large surface area of contact they afford. When the core 3 starts to move, however, the supports 70 are lowered under the action of oleodynamic cylinders 71 and the core 3 is supported by the rollers 68 which rotate on their own axes without harmful mutual slippage. Supports 19 for the vulcanized tube 5, which is collected on a reel 4, are located at the outlet of the vulcanizer (Figure 1), at the opposite end from the wrapping machine 1. Upstream of the reel is a constriction device 18 which can close the vulcanized tube 5 by squeezing its outer surfaces. A method of producing flexible tubes with the use of the apparatus described above will now be described. The core 3 (Figure 1) is located in the wrapping machine 1, being secured by the clamp 14 outside the vulcanizer 2, and a raw end 81 of a first section 5 of already-vulcanized tube which extends through the vulcanized tube which extends through the vulcanizer 2 and is wound around the reel 4 is fitted onto its end portion 80 (Figure 2). The trolley 6 then moves in two directions along the rails 7 and, with its rotary heads 9, deposits the various strips 12 around the core 3 with their ends directly superposed on respective, corresponding stepped strips of the end 81 of the first section 5, forming a second section 82 which extends the first section 5. In order to prevent any damage to the strips 12 by the members of the trolley 6, it is convenient for them to be deposited by the head 9 which, at that moment, is situated at the rear with respect to the direction of movement of the trolley 6. Finally, by means of a further pass of the trolley 6, a bandage carried by the reel which rotates with the bush 23 is unwound to bind the assembled section of tube 82 in order to compact it and assist its subsequent vulcanization. The trolley 6 then clamps the core 3 with the clamp 30 and pushes it into the vulcanizer 2, the end portion 83 of the section 82 opposite that adjacent the first section 5 being left outside. During this stage, as during all subsequent stages of movement, the reel 4 winds up or unwinds a length of vulcanized tube 5 which corresponds to the distance of movement of the trolley 6, the rollers 68, 52 supporting the core 3 by virtue of a relative upward movement with respect to the supports 51, 70 and the pantographs 15 being lowered when the trolley 6 approaches them and raised again once it has passed over them. The vulcanization, and also the joining of the two sections 5, 82, is then carried out, during which the sleeves 60 are inflated and come into contact with the outer surfaces of the sections of tube 82 and 5 to ensure the vapour-tight sealing of the vulcanizer 2. Upon completion of this operation, the trolley 6 returns the core 3 covered by the vulcanized tube 5 to its initial position in the wrapping machine 1, wherein the bandage is removed from the tube 5 by means of the reel carried by the rotary bush 23 of the moving trolley 6. The core 3 is then re-inserted ' in the vulcanizer 2 and the vulcanized tube 5 is separated by blowing air into the small tube 41 in the core 3 (Figure . 8)- and constricting the tube 5 by means of the device 18. The air works its way between the outer surface of the core 3 and the inner surface of the tube 5 to separate them, and also acts on the base of the end portion- of the core 3 which is thrust out of the vulcanizer 2 towards the wrapping machine 1. This thrust is adjusted so that the core is positioned in the wrapping machine 1 again, as at the start of the cycle, with the raw end 83 of the second section, which remained outside the vulcanizer 2, fitted over its end portion 80. This series of steps can then be repeated cyclically until the tube 5 has reached the required length, using as the first section of tube at any time the entire portion of tube produced up to that time. Flexible tubes of any length, having constant mechanical characteristics throughout their length, can thus be produced. Naturally, in order to avoid the dead times of the individual pieces of equipment resulting from the use of apparatus and a method of the type just described, a different installation arrangement may be considered. For example, a single trolley may be used to serve two sets of apparatus of the type described, depositing the strips on the core of one whilst vulcanization is effected in the other. In a variant of the method of the invention, the various strips 12 of rubber may be deposited on a core 3 (Figures 10a to lOg) by a conventional wrapping machine, not illustrated, with a rotary core and a reel-carrying trolley which moves parallel to and beside it to form a second section 82 of tube. A raw end 81 of a first already-vulcanized tube section 5 (Figure lOh) is then fitted onto an end portion 80 of the core which is left free. The two sections 5, 82 are thus a short distance apart, with their respective stepped layers 12 facing each other. Connecting strips 85 with characteristics substantially similar to each of the pairs of strips of the two sections 5, 82 are then applied manually (Figures 11a to Hi) between each pair. If necessary, bandaging may be carried out for the purposes of compaction after the deposition of each connecting strip 85, with subsequent unbandaging before the deposition of the next connecting strip 85. The core 3 thus covered is then inserted (Figure lOi) into a vulcanizer 2 provided with sealing means as described above, the end 83 of the second section 82 opposite the end 84 adjacent the first section 5 being left outside. After vulcanization, the core 3 is separated completely from the vulcanized tube 5 by pneumatic means similar to those described above. In this case, the cycle of steps can also be repeated cyclically until the tube has reached the required length, using as the first section 5 of the tube at any time, the entire portion of tube produced up to that time.

Claims: CLAIMS 1. A method of producing flexible tubes of any length from several superposed strips (12) of rubber and/or fibre-reinforced rubber, characterised in that it comprises the steps of: fitting an unvulcanized end (81) of a previously-wrapped first section (5) of tube onto an end portion (80) of an elongate cylindrical core (3); covering the rest of the core (3) with a plurality of superposed strips (12) of rubber so as to form a second section (82) of tube as an extension of the first section (5); inserting the core (3) into a vulcanizer (2), an end portion (83) of the second section (82) opposite the end (84) adjacent the first section (5) being left outside the vulcanizer; carrying out the vulcanization so as also to join the two sections (82, 5); separating at least part of the core (3) from the portion of tube constituted by the two sections (5, 82) , and repeating the above operations until the tube (5) has reached the desired length, using as the first section (5) of tube at any time the entire portion of tube produced up to that time. 2. A method according to Claim 1, characterised in that the adjacent ends (84, 81) of the two sections (5, 82) are juxtaposed on the core (3) and are situated a short distance apart with their respective stepped strips (12) facing each other, and a connecting strip (85) is applied between each pair of strips (12) of the two sections (5, 82), the connecting strips (85) having characteristics substantially the same as those of the strips (12) they connect. 3. A method according to Claim 2, characterised in that, after the application of each connecting strip (85), the said strip (85) and the ends of the strips (12) which it connects are bandaged in order to achieve compaction, and in that the bandage is removed before the application of the connecting strip (85) between the immediately overlying pair of strips (12). 4. A method according to Claim 1, characterised in that the adjacent ends (84, 81) of the two sections (5, 82) of tube are juxtaposed on the core (3), the ends of the individual strips (12) constituting the second section (82) being deposited directly on top of the end portions of the respective, corresponding stepped strips of the unvulcanized end (81) of the first section (5) which is left on the core (3) at the end of the preceding cycle of steps. 5. A method according to Claim 4, characterised in that it includes the steps of: bandaging the core (3) covered by the second section (82) and the unvulcanized end (81) of the first section (5) ; inserting the bandaged core (3) into a vulcanizer (2), the end portion (83) of the second section (82) opposite the end (84) adjacent the first section (5) being left outside the vulcanizer; vulcanizing the portion of tube inserted in the vulcanizer (2), so as also to join the two sections (5, 82); removing the core (3) carrying the vulcanized tube (5) from the vulcanizer (2); removing the bandage from the vulcanized tube (5); re-inserting the core (3) carrying the vulcanized tube (5) into the vulcanizer (2); separating the vulcanized tube (5) from the core (3) by blowing air into the core (3) so that the air passes through holes (42) formed in the surface of the core and works its way between the outer surface of the core and the inner surface of the tube to separate them; expelling the core (3) from the vulcanizer (2), the end portion (80) of the core (3) which is covered by the end (83) of the second section (82) opposite the end (84) adjacent the first section (5) being left and the vulcanized tube remaining inside the vulcanizer (2); and repeating the above steps until the tube has reached the desired length, using, as the first section (5) of tube at any time the entire portion of tube produced up to that time. 6. A method according to Claim 5, characterised in that the expulsion of the core (3) from the vulcanizer (2) takes place as a result of the thrusting action of the blown air on the base of the end portion (80) of the core (3), the tube (5) being constricted at a point downstream of the vulcanizer (2). 7. Apparatus for performing a method according to any one of Claims 1, 4, 5 and 6, comprising: a wrapping machine (1) for depositing the strips (12) around an elongate cylindrical core (3), including a trolley (6) which moves on rails (7), and a vulcanizer (2) for receiving the core (3) covered with the strips (12) to produce the finished tube (5), the apparatus being characteirsed in that: the wrapping machine (1) and the vulcanizer (2) are arranged in series and define a common axis (17) along which the core (3) can move; the trolley (6) has a through-hole (21) for the passage of the core (3) in correspondence with the common axis (17) and has at least one head (9) which rotates about the axis (17) and carries at least one reel (11) bearing the strips (12) to be deposited; the vulcanizer (2) has holes in its ends (66), in correspondence with the common axis (17), and has means therein for sealing against the core (3) covered by the strips (12) deposited by the wrapping machine (1); and in that it includes propulsion means for moving the core (3) from the vulcanizer (2) to the wrapping machine (1) and vice versa along their common axis (17), and means (54, 67) for supporting the moving core (3). 8. Apparatus according to Claim 7, characterised in that the propulsion means for the core (3) are constituted by the moving trolley (6) which carries a clamp (30) for engaging a reduced-diameter portion of the core (3) to make it fast with the trolley (6) . 9. Apparatus according to Claim 7, characterised in that the means (54, 67) for supporting the core (3) comprise a plurality of pairs constituted by at least one support (51, 70) and a roller (52, 68) rotatable about an axis perpendicular to the core (3) , the supports (51, 70) supporting the core (3) when it is stationary and the rollers (52, 68) supporting it during its movements, the supports (51, 70) and/or the rollers (52, 68) being provided with motor means which enable their movement in a plane perpendicular to the core (3), so that they can be raised and lowered relative to each other when the core (3) stops or starts moving, respectively. 10. Apparatus according to Claim 9, characterised in that each pair consisting of a support (51) and a roller (52) is supported in the wrapping machine (1) by a pantograph (15) which is located in a trench (16) formed beneath the rails (7) and can move between a withdrawn position in which it does not interfere with the movement of the trolley (6) and an extended position for supporting the core (3). 11. Apparatus according to Claim 6, characterised in that the means for sealing the vulcanizer (2) comprise a toroidal inflatable sleeve (60) which is arranged around the hole in each end (66) of the vulcanizer (2) and, once inflated, comes into contact with a circumferential surface of the outermost of the strips (12) covering the core (3) so as to ensure the sealing of the vulcanizer (2). 12. Apparatus according to Claim 7, characterised in that the trolley (6) includes at least one pair of controlled-velocity conveyor belts (28) for supporting the core (3) . 13. Apparatus according to Claim 12, characterised in that the conveyor belts are driven by the same motor (26) as causes the movement of the trolley (6). 14. A vulcanizer (2) for carrying out a method according to any one of Claims 1 to 6, characterised in that it has holes in its ends (66) and has sealing means therein. 15. A vulcanizer according to Claim 14, characterised in that the sealing means comprise an inflatable toroidal sleeve (60) which, once inflated, comes into contact with a circumferential surface of the outermost of the strips (12) covering the core (3) so as to ensure the sealing of the vulcanizer (2).

Inventors: ALBERTINI GUIDO, BARBIERI STEFANO, CIOFFI GIUSEPPE, ALBERTINI, GUIDO, BARBIERI, STEFANO, CIOFFI, GIUSEPPE
Applicants: UNIROYAL MANULI RUBBER SRL
Application year: 1989
Main classification: B29C53
IPC codes: B29C33, B29C35, B29C53, B29D23, B29K21, B29K105