Patent GB-788094-A (GB)
Title: Improvements relating to machines for covering a continuous length of tubing with two or more layers of threads helically wound around the tubing
IPC: B29D23/00
Filed: 1956-09-18
Abstract: 788,094. Tube-making machines. PIRELLI SOC. PER AZIONI. Sept. 18, 1956 [Oct. 13, 1955], No. 28543/56. Class 99(2). A machine for covering a continuous length of tubing 89 in the uncured or unset condition and particularly of natural or synthetic rubber, with at least two layers of thread wound helically around the tubing, comprises stationary tubular supports 2 equal in number to the number of layers of thread to be applied to the tubing and upstanding from a stationary framework 1, and a rotor associated with and mounted concentrically on each support, each rotor carrying in fixed relation thereto a number of thread spools 12. There is means associated with each support for feeding the tubing upwardly through and along a path coincident with the axis of the support, means associated with each support and located at the upper end thereof for guiding the tubing past a point in the said path at which the threads are wound onto the tubing, and for guiding the threads from the respective spools to that point, and means for applying a tractional force lengthwise of the tubing and beyond the point in the path of the tubing at which the last layer of threads is wound on to the tubing. Construction. As shown in Figs. 1 and 6, each rotor comprises an annular ring 7 connected by spokes to a central hub 6 and is mounted through the intermediary of ball-bearings on the respective support 2 which carries a stationary interchangeable guide 8 of conical shape, the hub 6 being extended upwardly to carry a guide 9 also of conical shape and provided with a series of grooves corresponding in number to the number of spools 12 mounted on the respective rotor ; the spools are disposed in two batches at different levels around the axis of rotation of the rotor, those of the upper batch being in angularly staggered relation to those of the lower batch, and each rotor carries two concentric rings 13, 14 provided with threadguiding bushes. Mounted on a horizontal shaft 17 is a feed pulley 18, the shaft driving through bevel gears 20, 21 a shaft 19 at right angles thereto and carrying a guide pulley 22. A vertical and stationary hollow column 23 supports a hollow arm 24 housing a rotatable shaft 32 which carries a traction drum 26 ; a second guide pulley 25, the axis of which is at right angles to that of the drum, is mounted on a shaft 35 driven through bevel gears 33, 34 from the shaft 32, and an arm 27, Fig. 5, carries a series of rotatable rollers 28 the axes of which are disposed obliquely with respect of the axis of rotation of the drum 26. Within the column 23 is a shaft 29 which drives through bevel gears 30, 31 the shaft 32 and which is driven through bevel gears 37, 38, the gear 38 being mounted on a shaft 39 driven by a spur gear 40, meshing with a gear 41 fast with the shaft 17. Driving mechanism. The machine is driven by a motor 52, Fig. 9, coupled by belts 54 to a pulley 53 on a shaft 55 carrying gears 56, 57, the gear 56 meshing with a gear 58 connected with and driving in a clockwise direction the lefthand rotor 7, Fig. 1, and the gear 57 driving in an anti-clockwise direction and through gears 59, 60 the right-hand rotor ; gear 57 also drives, through gears 61 .... 74 and a gear 36, the shaft 29, the gear 36 being mounted on the shaft, and consequently the pulleys 18, 22 and 25 and the drum 26. The ratio between the speed of feed of the tubing through the machine and the rotational speed of the rotors is varied by changing the gears 68, 69 and 71, 72. Brakes. To brake the rotation of the rotors 7 each of the latter is provided with a dished member 80, Fig. 9, against which are pressed a pair of pivoted shoes 78 incorporating a hydraulically operated piston-cylinder device. Thread spools. The mounting of each spool comprises a plate 42, Figs. 7 and 8, rigidly attached to the inner periphery of the ring 7 of the spool carriers and formed with a circular recess 43 equal in diameter to that of a flange 44 having a frusto conical surface 51 and projecting from the core of the spool ; the plate is also formed with two parallel channels 45 in which slides a plate 46 urged upwardly by a spring 47 and against a stop 48. The plate 46 is provided with an aperture 49 the upper part of the latter being semicircular and the lower part being defined by two V-shaped surfaces connected at the bottom thereof by a frusto-conical surface 50 corresponding to the surface 51 of the flange 44. To mount the spool, the plate 46 is depressed until the recess 43 is uncovered by the aperture 49 and the flange 44 is introduced into the recess whereupon the plate is allowed to rise under the thrust of the spring, so that the surfaces 50, 51 engage and the flange is forced axially into the bottom of the recess. The thread is wound helically on to the rigid conical core of a spool in such a manner that the helices of thread never exceed the larger diameter of the core, and is unwound from the spools by the " off-top " system. Operation. The tubing is delivered from the die of a tubing machine to a rotatable pan and unwound from the latter by an unwinding device and guided around the pulley 18 from which the tubing rises vertically through the left-hand support 2, Fig. 1, at which stage the first layer of threads is applied, and then passes around the pulley 25 to descend to and pass around the pulley 22. The tubing rises again from the latter pulley and, prior to passing through the support 2 of the right-hand winding unit which applies the second layer of threads, a strip 90 of rubber is applied over the first layer of threads. Having received the requisite number of layers of threads, the tubing then passes around the traction drum 26 and rollers 28 and is collected in a second pan.