A TWISTING MACHINE PARTICULARLY FOR TWISTED THREADS

Abstract: A twisting machine (1), which yields a twisted thread at an unusually constant twist value, comprises within a main frame (2) first and second yarn paths (9,10) converging toward a gathering point (11) of respective yarns from a first reel (3) carried on the main frame (2) and a second reel (4) carried on a spindle (13), a twisted thread path (12) extending from the gathering point (11) to a take-up reel (7) driven rotatively by a roller (49), a flyer (19) journalled in the main frame (2) at the gathering point (11), and a capstan (48) placed along the twisted thread path (12), and a positive mechanical drive (50) for interconnecting rotatively the flyer (19), capstan (48), and roller (49) directly with the spindle (13).

Description: This invention relates to a twisting machine according to the preamble of the main Claim (see FR-A-1 153 547). Twisting machines of the kind outlined above are well known and have been widely used for plying together two yarns into a twisted thread at the yarn gathering point, which thread is then wound around a suitable take-up reel as it is being formed at the gathering point. With currently available twisting machines, the resulting thread lay tends to be more or less uneven, in that it may develop fluctuations in the amount of twist, due to slippage on the spindle, and hence to changes in the spindle-to-capstan speed ratio. The problem that underlies this invention is to provide a twisting machine of the type specified above, which has such constructional and operational characteristics as to overcome the noted drawback which affects the prior art. This problem is solved by a twisting machine according to the characterizing clause of the main Claim. Further features and the advantages of a twisting machine according to this invention will be more clearly understood from the following detailed description of a preferred embodiment thereof, to be taken by way of illustration and not of limitation with reference to the accompanying drawings, where: Figure 1 is a schematical view of a twisting machine according to the invention; Figure 2 is an enlarged scale, part-sectional view of a detail of the twisting machine of Figure 1; and Figure 3 is a sectional view taken through the machine detail in Figure 2 along the line III-III. With reference to the drawing views, the numeral 1 designates generally a twisting machine according to the invention. The twisting machine 1 comprises, mounted to a main frame 2, a first reel 3 and a second reel 4 loaded with respective yarns 5 and 6 to be plied together, and a take-up reel 7 for taking up a twisted thread 8. Respectively indicated at 9 and 10 are first and second yarn paths extending from the first reel 3 and the second reel 4, respectively, for the yarns 5 and 6, which paths are arranged to converge toward a yarn gathering point, indicated at 11. The reference numeral 12 denotes a thread path extending from the yarn gathering point 11 to the take-up reel 7 for the twisted thread 8. The first reel 3 is carried on the main frame 2, and the yarn 5 is paid off it. The second reel 4 is supported on a spindle 13 having a vertical axis X-X, carrying a reel holder bowl 14, and being journalled in the main frame 2. The reel 4 is retained inside the bowl 14 by conventional magnetic means. The spindle 13 is driven rotatively from an electric motor 18 via a drive belt 15 stretched between two pulleys 16 and 17. The twisting machine 1 comprises, located at the gathering point 11, a mechanism 19 journalled in the main frame 2 and referred to as the flyer. The mechanism or flyer 19 comprises a shaft 20 with an axis X-X, which has a first portion 21 provided with mutually set-apart bearings 22 and 23, whereby it is journalled to the main frame 2, and a second portion 24 jutting out toward the second reel 4. The first portion 21 is made tubular by the provision of a coaxial bore 25 therein which opens with its bottom end into a throughgoing hole 26 formed across the shaft 20 between the first and second portions. Provided at said bottom end is a yarn eye leader 27 at which the gathering point 11 substantially locates. Provided at the bottom end of the second portion 24 is a yarn eye leader 28. Keyed to the portion 24 of the shaft 20 in spaced-apart relationship are two disk plates, respectively an upper one 29 and a lower one 30. Provided in the upper disk plate 29 are two yarn eye leaders 31 and 32. Likewise, two yarn eye leaders 33 and 34 are provided in the lower disk plate 30. Supported rotatably on the portion 24 of the shaft 20 of the mechanism 19 is a pin shaft 35 having an axis Y-Y perpendicular to the axis X-X. In particular, the pin shaft 35 carries two bearings 36 and 37 in mutually spaced-apart relationship whereby it is supported rotatably within a bush 38 fitted into a throughgoing hole 39 formed across the second portion 24 at a location between the disk plates 29 and 30. To the opposing ends of the pin shaft 35 there are keyed respective pulleys 40 and 41 which are identical of each other. By virtue of their keyed fit on the pin shaft, the two pulleys 40 and 41 can be rotated jointly. The first yarn path 9 travelled by the yarn 5 from the reel 3 to the gathering point 11 has a section 42 through the spindle 13 and then forms, with a section 43 thereof, a bag or balloon (the term "balloon" being meant herein to define the revolution figure generated by the yarn and detectable by the eye, and rendering the more frequently used French term of "ballon") which extends from the spindle 13 to the eye 33, and past the eye 33 into a section 44 extending from the eye 33 to the eye 31 and given at least one turn around the pulley 40, to then go through the eye 31 and converge toward the yarn gathering point 11 as far as the eye 27. The second yarn path 10 travelled by the yarn 6 from the reel 4 to the gathering point 11, has a section 45 which extends from the reel 4 to the eye 28, and runs then through and past the eye 34 into a section 46 extending from the eye 34 to the eye 32, it being given at least one turn around the pulley 41 and run through the eye 32 to also converge toward the yarn gathering point 11 at the eye 27. The path 12 travelled by the twisted thread 8 extends from the yarn gathering point 11 to the take-up reel 7 and has a section 47 extending through the first portion 21 of the shaft 20, goes through a positive feed 48, referred to as the capstan, and finally reaches the take-up reel 7. As for the take-up reel 7, this is driven rotatively by a roller 49 journalled in the main frame 2, with the reel arranged to bear on the periphery of the roller 49. The twisting machine according to this invention includes a mechanical drive 50 which interconnects for joint rotation in a direct and positive manner the flyer 19, capstan 48, and take-up reel drive roller 49 with the spindle 13. More specifically, the drive 50 comprises a vertical shaft 51 journalled in the main frame 2, to which three cogged pulleys 52, 53, and 54, defining lower, middle, and upper pulleys, respectively, are keyed. The lower pulley 52 is positioned level with the spindle 13 and connected by a cogged belt 55 to a cogged pulley 56 keyed to the spindle 13. The middle pulley 53 is positioned level with the flyer 19 and connected by a cogged belt 57 to a cogged pulley 58 which is mounted for idle rotation on the top end of the first portion 21 of the shaft 20 for the flyer 19. A clutch 59 associated with the flyer 19 at an intermediate location to the pulley 58 and the remaining portion 21 of the shaft 20, is provided for making rotatively unitary the pulley 58 with the shaft 20, and hence, the flyer with the drive. It is arranged to be declutched when the flyer 19 is to be disengaged from the drive 50. The clutch 59 is of the centrifugal variety, it being disengaged on the centrifugal force attaining, as a result of a predetermined critical angular velocity having been reached, a predetermined suitable magnitude. More specifically, the clutch 59 includes a case 60, fast with the pulley 58, wherein two eccentric masses 60 and 61 are pivoted which are subjected to the centrifugal force against the bias of a restoring spring 63 embodied by a snap ring encircling said masses. A dog 64 is provided on the mass 61 and adapted to engage in a notch 65 formed in the portion 21 of the shaft 20 to make the pulley 54 and shaft 20 rotatively unitary. The upper pulley 54 is positioned level with the capstan 48 and connected by a cogged belt 66 to a cogged pulley 67 associated with the capstan for driving it. The drive 50 further includes a pulley 68 which is associated with the capstan and connected rotatively to the pulley 67 by a transmission, e.g. a bevel gear transmission, said pulley 68 being, in turn, connected via a cogged belt 69 to a cogged pulley 70 keyed to the roller 49. The twisting machine 1 just described may be coupled, on a common main frame, to another twisting machine 71, quite similar to the former but being a mirror image thereof. Also, the two twisting machines, 1 and 71, could be laid beside quite similar pairs of twisting machines, to provide a cluster including up to several tens pairs all mounted on a common main frame, wherein each twisting machine forms an operatively independent unit. The operation of the twisting machine 1 will be next described by making reference to starting, steady-state, and halting phases thereof. At the start-up, the motor 18 will reach its rated rpm almost instantaneously, and the spindle 13 move, within a certain time period when the belt 15 slips, from standstill to steady-state rpm. The same applies to the flyer 19, capstan 48, and roller 49, which are all held rotatively rigid with the spindle by means of the drive 50. As for the flyer 19, this is driven rotatively by the drive 50 until its speed rises from zero to the aforesaid predetermined angular velocity critical value at which the centrifugal force reaches a value whereby the clutch 59 is disengaged. From this time onwards, the mechanism 19 is rotated, up to its steady state rpm, rather than from the mechanical drive 50, from the balloon formed by the yarn 5 across its section 43. It should be noted that, with the clutch 59 in its disengaged condition, the flyer 19 is released angularly from the spindle 13, and that the balloon can take a slightly helical pattern in space, that is the required pattern for entraining the flyer 19. On the steady state condition being reached, and regardless of any residual slippage of the belt 15, the flyer 19, capstan 48, and roller 49 will be all timed together. In particular, the spindle 13 and flyer 19 will turn at exactly the same rpm. It should be noted that during steady-state operation, the yarns 5 and 6 will reach, on account of the at least one turn thereof around their respective pulleys 40 and 41, the same speed at their sections 44 and 46, thereby they get to the gathering point 11 at the same rate. Thus, the pin shaft 35 is effective to balance the tensions on the yarns 5 and 6 by transmitting a supplementary torque to the pulley around which is wound the yarn inherently more tensioned at the expense of the pulley having the least tensioned yarn wound around it. The twisting machine halting procedure is substantially the reverse of its starting procedure. In fact, after switching off the motor 15, the spindle 13, and hence the flyer 19, capstan 48, and drive roller 49 for the take-up reel 7 will all slow down gradually in timed relationship. On the flyer 19 speed again crossing the critical speed value, the clutch 59 is engaged, owing to the spring bias overcoming the centrifugal force, and the flyer 19 is re-engaged with the drive 50 and, therefore, again made rotatively unitary with the spindle 13, and continues to rotate, despite the gradual collapsing of the balloon, until it is brought to a full stop in timed relationship with the spindle. The main advantage of the twisting machine according to this invention resides in the constant value of the thread lay, attained irrespective of any fluctuations in the spindle speed by virtue of the timed rotary connection of all the twisting machine members to the spindle. A further advantage of the twisting machine according to the invention is that its operation is nearly fully automatic, since the various members derive their motions from the spindle. In particular, the inventive twisting machine ensures absolute uniformity of twist, even during the starting and halting phases. Where a number of twisting machines are provided on a common main frame, the added advantage is secured that the threads from all the twisting machines carry all the same amount of twist, irrespective of the speeds at which the individual motors are run. Another advantage of the twisting machine according to the invention is that the flyer carrying the yarn tension equalizing shaft is driven rotatively, while operating at steady-state speed, from the spindle itself via the balloon formed by the yarn. A not least advantage of the twisting machine according to the invention is that it yields a thread, from two yarns made to converge to a gathering point, which has quite faultless characteristics, that is, optimum appearance and a high toughness, on account of the rates at which both yarns are led to the gathering point being strictly identical.

Claims: A twisting machine (1) of a type which comprises, within a main frame (2), first and second yarn paths (9,10) converging toward a yarn gathering point (11) where the yarns are gathered as they are respectively supplied from a first pay-off reel (3) carried on the main frame (2) and a second pay-off reel (4) carried on a spindle (13) journalled in the main frame (2), a twisted thread path (12) extending from said yarn gathering point (11) to a take-up reel (7), a so-called flyer (19) journalled in the main frame (2) at the gathering point (11), and a so-called capstan feed (48) in the thread path (12) from the gathering point (11) to the pick-up reel (7), rotatvely coupled to the spindle (13), characterized in that it comprises a positive mechanical drive (50) for rotatively coupling the flyer (19) directly to the spindle (13). A twisting machine (1) according to Claim 1, characterized in that said positive mechanical drive (50) includes a clutch (59) associated with the flyer (19) and disengageable to release it from the drive (50) upon a predetermined critical velocity being exceeded. A twisting machine (1) according to Claim 2, characterized in that said clutch (59) is of the centrifugal type disengaged by centrifugal force on reaching said critical velocity. A twisting machine (1) according to Claim 3, characterized in that each yarn path (9,10) includes at least one section (44,46) passed around a respective one of two pulleys (40,41) keyed to a pin shaft (35) journalled to the flyer (19) for idle rotation.

Inventors: BIANCHI, FRANCO
Applicants: OFFICINE MECCANICHE RIVA S.R.L.
Application year: 1988
Main classification: D02G3
IPC codes: D02G3