STRAIGHTENING DEVICE EQUIPPED WITH A DEVICE FOR POSITIONING A FABRIC DETACHING CYLINDER FOR TEXTILE MACHINES

Abstract

 A straightening device is described for correcting the deformation of a conveyed fabric web (16), comprising a pinwheel (18) for the fabric (16), upstream of which, with respect to the advancement direction of the fabric (16), there is an hollow detachment cylinder (3), the straightening device also comprising a positioning device (1) of the detachment cylinder (3) comprising: the hollow detachment cylinder (3) equipped inside with at least one control cylinder (5) integral with it but rotating independently; control means (7, 9, 11, 13) designed to move along a rectilinear direction (A) and to move the detachment cylinder (3) into one of the plurality of its operating positions; and guide means (15) designed to guide, horizontally and parallel to the rotation axis of the pinwheel (18), the detachment cylinder (3) towards its operating position along a path that varies depending on the type of fabric (16) to straighten.

Description

[0001] The present invention relates to a straightening device of the pinwheel type for correcting the deformation of a conveyed web of material. This straightening device is equipped with a device for positioning a fabric detaching cylinder for textile machines.

[0002] During the mechanical production and processing of conveyed webs of material, deformations or distortions often occur. Such distortions in the web change the structure of the products made from them, such as woven fabrics or carpets, which in turn reduces the use value of the products and/or affects the further processing of the products.

[0003] A textile web consists in particular of threads crossed at right angles, which are produced during the weaving process in the loom or weaving machine. A distinction is made between longitudinal threads ("warp") and transverse threads ("weft"). The orthogonal textile structure of the warp and weft is deformed due to distortion that usually runs obliquely to the travelling direction of the fabric ("oblique deformation") or that runs in a curve to the travelling direction of the fabric ("curved deformation "). The originally orthogonal structure of warp and weft or their rows of stitches are thus modified obliquely or arched, i.e. there is an oblique and/or arched distortion.

[0004] To restore the originally orthogonal structure, the textile web is guided on mechanical straightening devices in which existing distortions are compensated by applying balancing forces to the moving textile web using cylinders arranged at an angle or in an arc with respect to the travelling direction of the textile web.

[0005] Such roller-based straightening devices are preferably used to eliminate mesh distortion.

[0006] Alternatively, so-called needle straightening arrangements are known in which the moving textile web is tensioned at the opposite edges of the web by means of at least two needle straightening wheels arranged oppositely transverse to the movement direction of the textile web. By rotating the straightening wheels around a rotation axis at a predetermined angle to the running direction of the textile web and with a predetermined transverse force, a transverse tension acting laterally outward is introduced into the textile web, causing widening of the web. The edges of the deformed textile web are therefore subjected to a defined straightening force towards the outside, i.e. in the direction of the textile web weft. This creates a force component that attempts to reshape the parallelogram structure into the originally orthogonal structure.

[0007] The inclination of the straightening wheels, starting from the tapping point, where there is a minimum spreading value, leads to an increase in the spreading value of the web up to a maximum spreading value and, beyond this, a decrease in spreading value of the web up to the unlock point. Since at least a slight strain of the sheet is introduced into the web of material by the straightening wheels themselves, the pin straightening arrangement is often followed by a pinwheel take-off roll arrangement.

[0008] However, when the textile web is withdrawn or released from the straightening wheels, problems occur. For example, the sheet distortion introduced by the needle straightening arrangement increases if the web is unblocked from the straightening wheels too late, while if the web is unblocked too early, the straightening forces are still so high that the web is almost torn by wheel straightening, causing distortion of the edges to the point of damaging the edges of the material. The moment at which the web is released or the selection of the release point from the straightening wheels depends in particular on the properties of the material, in particular on its elasticity and/or on the state of the web, in particular on the extent of the existing warp. The width of the web of material is also of particular importance during needling, which is usually smaller than the width of the web of material in the unloaded state due to the mechanical transport of the web of material. In conventional needle straightening arrangements, the needling of the web of material always occurs in the same way, regardless of the properties of the web of material, so that in some cases high residual distortions are introduced in the web of material, leading to increased mechanical stress in their subsequent correction.

[0009] The problems highlighted above have been resolved by a device as described in document EP-A1-2573254. Therein, a take-off cylinder has been developed, which is designed to be automatically moved to a series of operating positions tangential to the surface of two pinwheels, such movement occurring along an annulus in which the take-off cylinder is pivoted around a rotation axis of two pinwheels.

[0010] Document EP-A1-2573254 further describes a method for setting the detachment point of a needle straightening device having at least two needle straightening wheels for correcting the deformation of a conveyed web of material, in particular textile, in which the conveyed web of material is applied with opposite material edges at a point of attachment to the needle straightening wheels and is removed again at a point of fixation from the needle straightening wheels.

[0011] The problem with the solution of document EP-A1-2573254 is that it allows, through a complicated and imprecise solution, only a movement along a circular arc tangential to the pinwheels, without any operational flexibility depending on the type of fabric to be processed.

[0012] Documents DE-A1-10 2016 222143 and GB-A-143 347 describe a device for positioning a fabric detaching cylinder according to the preamble of Claim 1.

[0013] Object of the present invention is solving the aforementioned prior art problems, by providing a straightening device equipped with a device for positioning a fabric detaching cylinder which allows an almost infinite range of operating positions of the weft straightening cylinder to be achieved, so as to be able to satisfy any type of fabric to be straightened, for example elastic fabrics for which the tangential position with respect to the pinwheels is not optimal for their straightening.

[0014] The above and other objects and advantages of the invention, as will appear from the following description, are achieved with a straightening device equipped with a device for positioning a fabric detaching cylinder for textile machines such as claimed in claim 1. Preferred embodiments and non-trivial variants of the present invention form the subject matter of the dependent claims.

[0015] It is understood that all attached claims form an integral part of this description.

[0016] The present invention will be better described by some preferred embodiments thereof, provided by way of example and not by way of limitation, with reference to the attached drawings, in which:

• Figure 1 is a schematic side view of the operational idea underlying the present invention;
• Figure 2 is a side view of the outline of the guide means of the present invention;
• Figure 3 is a side view of the guide means of Figure 2 with the control means of the present invention inserted:
• Figure 4 is a front view of the guide means and the control means in combination with the detachment cylinder of the present invention;
• Figure 5 is a top view of the solution in Figure 4; and
• Figure 6 is a detailed view of Figure 4 which better illustrates the operational couplings between guide means, control means and the cylinder for detaching the fabric from the wheels.

[0017] Referring to the Figures, a preferred embodiment of the present invention is illustrated and described.

[0018] Figure 1, in general terms, shows a schematic side view of a straightening device in a simplified representation, which has at least one pinwheel 18 of the fabric 16, upstream of which there is at least one detachment cylinder 3. Operation of these elements on the fabric 16 to widen and straighten it is known and will not be described in detail below.

[0019] Figure 1 also shows a plurality of positions of the detachment cylinder 3, positions created starting from the highest one, which is the closest to the surface of the pinwheels 18, to arrive at the lowest one, progressively moving away from this surface, along the direction A indicated by the arrows.

[0020] As illustrated in Figures 3, 4, 5 and 6, the straightening device is equipped with a positioning device 1 of the detachment cylinder 3 for textile machines of the present invention substantially comprising:

• at least one hollow detachment cylinder 3 equipped inside with at least one control cylinder 5 integral with it but rotating independently;
• control means 7, 9, 11, 13 designed to move along a rectilinear direction (A) and to move the detachment cylinder 3 to one of the plurality of its operating positions; and
• guiding means 15 designed to guide, horizontally and parallel to the rotation axis of the wheels, the detachment cylinder 3 towards its operating position along a path that varies depending on the type of fabric 16 to be straightened.

[0021] The guiding means 15 can be a slot inside which one end of the detachment cylinder 3 slides, the detachment cylinder 3 being placed downstream, with respect to the direction of advancement of the fabric 16, of pinwheels 18 of fabric 16.

[0022] The slot has an elongated shape such as to achieve a progressive distancing of the detachment cylinder 3 from the surface of the pinwheels 18.

[0023] The control means 7, 9, 11, 13 are made up of toothed wheels 7 integral with the bar inside the detachment cylinder controlled in rotation by racks 9 by contrast with two guide wheels 11, all controlled by a gearmotor 13.

[0024] As illustrated, the control cylinder 5 is integral with the detachment cylinder 3 via at least one bearing 20.

[0025] The device 1 of the invention thus allows the detachment cylinder 3 to be moved, by controlling the toothed wheels 7 and the racks 9, to one of its operating positions, upon reaching which the cylinder 3 itself is fixed and begins to work on the fabric coming out of cylinder 18.

Claims

1. Straightening device for correcting the deformation of a conveyed fabric web (16), said straightening device comprising at least one pinwheel (18) for the fabric (16), upstream of which, with respect to the advancement direction of the fabric (16), there is at least one hollow detachment cylinder (3), said straightening device also comprising a positioning device (1) of the detachment cylinder (3) comprising:

- said hollow detachment cylinder (3) equipped inside with at least one control cylinder (5) integral with it but rotating independently;

- control means (7, 9, 11, 13) designed to move along a rectilinear direction (A) and to move said detachment cylinder (3) into one of the plurality of its operating positions; and

- guiding means (15) designed to guide, horizontally and parallel to the rotation axis of the pinwheel (18), said detachment cylinder (3) towards its operating position along a path that varies depending on the type of fabric (16) to straighten;

characterized in that said control means (7, 9, 11, 13) are made up of toothed wheels (7) controlled in rotation by racks (9) by contrast with two guide wheels (11), all controlled by a gearmotor (13).

2. Straightening device according to claim 1, characterized in that said guide means (15) are a slot inside which one end of the detachment cylinder (3) slides, said detachment cylinder (3) being designed to be placed downstream, with respect to an advancement direction of the fabric (16), of the pinwheel (18) of the fabric (16), said slot being of an elongated shape such as to achieve a progressive removal of the detachment cylinder (3) from the surface of the pinwheel (18).

3. Straightening device according to claim 1 or 2, characterized in that the control cylinder (5) is integral with, but rotates independently of, the detachment cylinder (3) via at least one bearing (20).

Drawing