"Condensing device of a textile sliver in a spinning machine"

[0001] The present invention, relates to a condensing device of a textile sliver in a spinning machine.

[0002] Numerous embodiments of condensing devices for spinning machines exist.

[0003] The embodiments exploiting a current of aspirated air which acts on the fibres bringing them closer together, thereby condensing the sliver, are particularly widespread.

[0004] Such solutions are particularly appreciated, in that they permit the contemporary condensing of the sliver and the removal of dust from it, with a significant improvement in the quality of the yarn obtained in the spinning machine.

[0005] However, most of such solutions provide components which can only be applied to dedicated machines and do not thereby permit retrofitting on existing machines.

[0006] Other known solutions envisage laborious dismantling operations for the performance of extraordinary maintenance activities and frequent ordinary maintenance operations for the replacement of moving parts subject to wear; moreover they generally need a dedicated channel for the current of aspirated air on account of the large quantities of air needed for proper functioning.

[0007] In addition, some solutions exist which perform mechanical condensing, that is to say they substantially channel the sliver of fibre into a f nnel-shaped duct, so as to draw the fibres closer together, thereby condensing the sliver.

[0008] Such solutions do not however permit removal of the dust from the sliver.

[0009] The purpose of the present invention is to make a condensing device of a textile sliver in a spinning machine which overcomes the drawbacks mentioned in relation to the prior art.

[0010] Such purpose is achieved by a condensing device made according to claim 1 below.

[0011] The characteristics and advantages of the condensing device according to the present invention will be evident from the description below, made by way of a non-limiting example, according to the attached figures, wherein:

[0012] - figure 1 shows a view of the drawing zone of a spinning machine, fitted with a condensing device according to the present invention;

[0013] - figure 2 shows an isometric view of the drawing zone in figure 1;

[0014] - figure 3 shows one embodiment of the condensing device according to a rear view, that is observing the condensing device from the side of the drawing cylinder to which it is applied;

[0015] - figure 4 shows a further embodiment of the condensing device according to a rear view that is observing the condensing device from the side of the drawing cylinder to which it is applied;

[0016] - figure 5 shows a cross-section view of an aspiration unit, according to the section plane V-V in figure 1.

[0017] A spinning machine on a spinning line comprises a plurality of spinning points, each spinning point comprises a spindle for the formation of a reel of yarn.

[0018] Each spinning point further comprises a drawing device 1, which a roving Wl goes into and a drawn sliver comes out of, and a condensing device 2, from which a condensed sliver W3 emerges, generally destined to be twisted and wound to form the reel.

[0019] According to a preferred embodiment, the drawing device 1 comprises, in an opposite direction to that of advancement of the sliver, a first pair of cylinders, formed by the first drawing cylinder 4a and the first pressure cylinder 4b, which surmounts the first drawing cylinder and is in contact under pressure with it, to draw the sliver in transit.

[0020] The drawing device 1 further comprises, a second pair of cylinders, upstream of the first pair of cylinders, formed of the second drawing cylinder 6a and the second pressure cylinder 6b, and a third pair of cylinders, upstream of the second pair of cylinders, formed of the third drawing cylinder 8a and the third pressure cylinder 8b.

[0021] The pairs of cylinders have different rotation speeds, so as to achieve drawing of the sliver moving forward; in general, the rotation speed of the second pair of cylinders is greater than that of the third pair and the rotation speed of the first pair is greater than that of the second pair.

[0022] The ratios of the rotation speeds define the drawing ratios; in general, the drawing ratio between the second and third pair is much less than the drawing ratio between the first and second pair: this means that the sliver is drawn lightly between the second and third pair and drawn strongly between the second and third pair of cylinders .

[0023] Preferably, the drawing device 1 comprises a drawing cage 10 between the third pair of cylinders and the first pair of cylinders which the second pair of cylinders is part of.

[0024] The cage 10 comprises an inversion abutment 12, downstream of the second pressure cylinder 6b, distanced from it, and an upper belt 14, wound around the second cylinder 6b, by which it is dragged in movement, and around the inversion abutment 12, thereby forming a closed circuit.

[0025] The cage 10 further comprises a fixed lower guide 16, positioned downstream of the second drawing cylinder 6a, distanced from it, having a main portion 18 which extends mainly in the direction of advancement of the sliver terminating next to the abutment 12, and a lower belt 20, wound around the second drawing cylinder 6a, by which it is dragged in movement, and around the main portion 18, so as to form a closed circuit.

[0026] The two belts 14, 20 are in contact along a section aligned with the gap between the second pair of cylinders and the first pair of cylinders, and the sliver is dragged between them.

[0027] At the exit of the cage 10, the sliver enters the condensing device 2, which it comes out of as a condensed sliver W3.

[0028] The condensing device 2 comprises the first drawing cylinder 4a and the first pressure cylinder 4b, a suction mouth 30 looking onto the first drawing cylinder 4a, and an output cylinder 4c, downstream of the first pressure cylinder 4b, in contact under pressure with the first drawing cylinder 4a. [0029] Generally, the suction mouth 30 can be fitted to a general main cylinder; in other words, the suction mouth does not necessarily have to be fitted to a drawing device. For example, in one embodiment variation, the spinning machine comprises a drawing device and, downstream of this, a main cylinder, coupled to the pressure cylinder and to the output cylinder, which the suction mouth co-operates with.

[0030] The first pressure cylinder 4b co-operates peripherally with the first drawing cylinder 4a in an input contact zone and the output cylinder 4c co-operates peripherally with the first drawing cylinder 4a in an output contact zone, so that the sliver passes along the contact zones between these, passing along a contact section on the outer surface of the first drawing cylinder 4a.

[0031] The contact section on the first drawing cylinder 4a, defined between the contact zones of the first pressure cylinder 4b and the output cylinder 4c, has an angular breadth on the first drawing cylinder of 45° to 90°, preferably 60° to 75°, preferably equal to 68°.

[0032] The suction mouth 30 is connected, by a suction duct 60, to suction means suitable to form a current of aspirated air.

[0033] According to a preferred embodiment, the mouth 30 comprises a main body 32 provided with a main surface 34, looking onto the outer surface of the first drawing cylinder 4a, on which a suction zone extends provided with at least one suction aperture 36, in the form of a slit or hole, from which the air is aspirated by the suction means.

[0034] For example, the slits are an elongated shape, for example slotted; for example the holes are circular or elliptical.

[0035] Preferably, the main body has a central row of circular holes of a larger diameter which extends along the contact section of the sliver on the first pressure cylinder, with along either side, circular holes of a smaller diameter.

[0036] Preferably, the main surface 34 is arched, for example with a curvature such as to substantially trace the curvature of the outer surface of the first drawing cylinder, with which said mouth 30 co-operates. Preferably, said main surface 34 has the same curvature radius as the outer surface of the first drawing cylinder 4a.

[0037] According to a preferred embodiment, the mouth 30 further comprises a casing 38 in which the main body is housed.

[0038] According to one embodiment, the casing 38 comprises an upstream wall 40, placed upstream of the suction zone, terminating in an upstream terminal surface 42.

[0039] The upstream terminal surface 42 is preferably arched, such as .to trace the curvature of the outer surface of the first drawing cylinder 4a for example with an identical curvature radius.

[0040] Preferably, the main surface 34 and the upstream terminal surface 42 are the same distance from the outer surface of the first drawing cylinder 4a, that is to say they lie on the same cylindrical surface.

[0041] According to one embodiment, the upstream terminal surface 42 projects from the main body 32, so as to terminate looking onto the outer surface of the first drawing cylinder 4a, closer to said outer surface than the main surface 34 of the main body 32, which is therefore recessed.

[0042] Preferably, in addition, the casing 38 comprises a downstream wall 44, placed downstream of the suction zone, terminating in a downstream terminal surface 46.

[0043] The downstream terminal surface 46 is preferably arched, such as to trace the curvature of the outer surface of the first drawing cylinder 4a, for example with an identical curvature radius.

[0044] Preferably, the main surface 34 and the downstream terminal surface 46 are the same distance from the outer surface of the first drawing cylinder 4a, that is to say they lie on the same cylindrical surface.

[0045] According to a further embodiment, the downstream terminal surface 46 projects from the main body 32, so as to terminate looking onto the outer surface of the first drawing cylinder 4a, closer to said outer surface than the main surface 34 of the main body 32, which is therefore recessed.

[0046] Rearwards, that is to say from the side opposite the outer surface of the first drawing cylinder 4a in relation to the suction zone, the mouth 30 comprises a bottom wall 48, which connects the upstream wall 40 and the downstream wall 44.

[0047] Axially, that is in the direction of the rotation axes of the cylinders, the upstream 40 and/or downstream wall 44 and/or bottom wall 48 extend for a longer section than the axial extension of the central body 32.

[0048] In other words, between the outer surface of the first drawing cylinder 4a, the bottom wall 48, the upstream wall 40 and the downstream wall 44 form a compartment which the main body 32 is housed in.

[0049] Said compartment has, in an axial direction, on both sides of the suction zone, a lateral access 80, 82 which forms a suction channel of the air in a direction orthogonal to the direction of advancement of the sliver being processed.

[0050] The lateral accesses enable the air aspirated from the suction zone to strike the fibres of the sliver being processed in a direction mainly incident, in particular mainly orthogonal to that of advancement of the sliver, thereby enhancing condensing.

[0051] For example, the lateral accesses have a smaller through section than the circumferential extension of the suction zone they open onto.

[0052] In general, "gap" between two cylinders in contact under pressure is defined as the region contained between the contact zone of the two cylinders and the tangent plane common to both cylinders.

[0053] Preferably, the suction zone has a circumferential extension such as to penetrate at least partially the gap between the first pressure cylinder 4b, and the first drawing cylinder 4a and/or the gap between the output cylinder and the first drawing cylinder 4a.

[0054] According to a preferred embodiment, the mouth 30 comprises an entrance duct 50, upstream of the suction zone, which the sliver passes through before reaching the slits 36.

[0055] For example, said entrance duct is funnel-shaped converging towards the suction zone and, preferably, is made through the upstream wall 40. [0056] In addition, according to a further embodiment, the mouth 30 comprises an exit duct 52, downstream of the suction zone, which the sliver passes through after passing over the slits 36.

[0057] For example, said exit duct is funnel-shaped converging away from the suction zone and, preferably, is made through the downstream wall 44.

[0058] For example, the entrance mouth of the exit duct 52 has a smaller axial extension than the exit opening of the entrance duct 50.

[0059] According to one embodiment, the suction zone extends on the main surface 34 of the main body 32, in a region included between the upstream wall 40 and the downstream wall 44, and in particular completely between the exit opening of the entrance duct 50 and the entrance mouth of the exit duct 52.

[0060] According to a further embodiment, the suction zone also extends in the entrance duct 50 and/or in the exit duct 52.

[0061] Preferably, two adjacent spinning points have a single suction unit 70, connected to a single suction duct 60, fitted with two separate suction mouths 30, each operating on a respective contact section of the first drawing cylinder 4a of the spinning point.

[0062] Preferably, the suction mouths of the suction unit are identical.

[0063] Innovatively, the condensing device according to the present invention is particularly efficient in its condensing action.

[0064] In particular, advantageously, the condensing device forms a suction compartment defined by walls so as to increment the suction action of the current of air and enhance the condensing and removal of dust from the sliver.

[0065] Advantageously, in addition, the condensing device is particularly simple from a structural point of view: in particular, it does not envisage rotating cylinders fitted with suction holes, requiring a complex airtight system and high production costs.

[0066] According to a further advantageous aspect, the condensing device can also be attached to existing machines, by mean of extremely limited modification operations .

[0067] According to a further advantageous aspect, the condensing device does not require a dedicated suction system in that it does not need higher flows of aspirated air than those normally present in a spinning machine.

[0068] For clarity of explanation the condensing device according to the present invention has been described above with reference to the drawing cylinder of a drawing device of the sliver; in general however the condensing device is applicable to any cylinder of the spinning machine, for example additional in relation to the cylinder of the drawing device, downstream of the drawing device .

[0069] According to an embodiment variation, in addition, the main surface of the main body of the suction mouth is flat.

[0070] According to a further embodiment variation, the main body is provided with identical slits and/or holes; according to yet a further embodiment variation, the main body is provided with slits of different shapes and dimensions and/or holes of different shapes■ and dimensions.

[0071] According to a further embodiment variation, the suction unit serves more than two spinning points.

[0072] According to yet a further embodiment variation, the suction unit is provided with suction mouths of differing shape and size to each other.

[0073] It is clear that a person skilled in the art may make variations to the condensing device according to the present invention so as to satisfy contingent requirements while remaining within the sphere of protection as defined by the following claims.