Device for controlling the position of a tubular fabric during cutting

Abstract

 Device for centring a tubular fabric on the cutting tool, adapted for a cutting machine of the type implementing motor barrels which rotate on their axis and are controlled by photoelectric cells positioned along the advance path of the fabric and located inside the tube formed by the fabric, being in contact with it and associated to a motor fan adapted to blow air inside said tube in order to stretch and widen it; it consists of a single barrel (20) the side wall of which (23) is provided, along its whole circumference with through slots (25), adapted to put the outer surface in communication with means that suck air towards the inner part of the barrel (20).

Description

[0001] The present invention refers to a control device for controlling the position of a tubular fabric while it is cut.

[0002] It is known that a tubular fabric presents rope-like form and it needs to be first untwisted and then widened transversally so that it is possible to cut it longitudinally along the so-called missing weft, that is a line defined by a missing weft in the fabric. In order to obtain good precision in cutting, centring devices are used which make the tubular fabric rotate, after it has been widened by an air flow passing inside it, so that it always presents the missing weft to the cutting tool. It is an important condition that the cut be made quickly and precisely and that the fabric be stretched and kept all the time in the correct position, that is "centred" in relation to the cutting device which generally consists of a rotating disk blade the cutting edge of which defines a vertical centring plane.

[0003] It is known a centring device including also two positioning barrels which rotate on their vertical axis, being separated the one from the other and adapted to act directly on the fabric from its inner part in order to make it rotate transversally in the feeding direction so that the missing weft is kept in correspondence with the cutting device.

[0004] However, this system presents a few drawbacks. In fact, even if the respective position of the two barrels can be adjusted, so that it may be adapted to different types of loop and/or to different sizes, it may happen that the friction between the loop and the rotating barrel is not enough to make the barrel itself guide the loop into rotation in order to take the missing weft back to the position in which it is in correspondence with the cutting device. This is also due to the air which is blown inside the loop and sometimes causes the loop to be too "light" on the surface of the barrels.

[0005] It is an object of the present invention to provide a guiding device which allows to avoid the aforementioned drawback.

[0006] It is another object of the present invention to reduce as far as possible the component parts of the positioning device without compromising its effectiveness, in order to lower the overall production costs.

[0007] These and further objects are achieved by means of a device to position tubular fabrics implemented on a cutting machine presenting the characteristics disclosed in claim 1.

[0008] Further characteristics and advantages will become more clear in the following description which refers to the accompanying drawings provided as non-restrictive example, in which

Figure 1 is a side elevational view of a machine for cutting tubular fabric provided with a first preferred embodiment of the positioning device according to the invention;

figure 2 is a side elevational view of a machine for cutting tubular fabric provided with a second preferred embodiment of the positioning device according to the invention;

figure 3 is a magnified view of a part of the positioning device of figure 1.

[0009] With reference to the figures, in figure 1 the reference number 2 indicates en equipment continually performing a series of operations, such as cutting, on a tubular fabric 8 which advances through it. It is part of this equipment an untwisting device 10 of a known type, which makes the fabric arriving in rope-like form, for example after dyeing, rotate in both senses, as to the advancing direction, so that it presents no torsion and can be widened, by means of blowing air inside it, cut longitudinally and then stretched.

[0010] The air is blown countercurrent by means of a motor fan 12 and a conduit 14. The fabric that is thus inflated is dragged towards the cutting tool 15, which, in this case, consists of a disk 16 which rotates on a vertical plane, in order to cut the fabric longitudinally along the missing weft.

[0011] In the area immediately above the cutting unit 15, a positioning device, overall indicated by reference number 17, is located in a way that allows it to be positioned inside the tubular fabric while in use.

[0012] The centring device is controlled by an optical reader 19 which is always detecting the position of the missing weft and which acts immediately when the tubular fabric needs to be centred again.

[0013] According to the present invention, the positioning device 17 includes a fixed support part 19, supporting a barrel 20 which rotates on its axis by means of an electric motor 22 that is placed inside it. The side wall 23 of the barrel 20 is provided on its whole circumference with through slots 25, of preferably rectangular profile, which allow the communication between the outer surface of the barrel and the open end 26 of a fixed air suction vent 27 located inside the barrel next to the motor 22. The end 26 will advantageously open in correspondence with the plane defined by the cutting tool 15. The vent 27 is connected, by means of a conduit 30, to the sucking point of the motor fan 12 so that a sucking air current is created on the surface of the barrel, which current retains the loop fabric 8 against the wall 23 of the barrel 20. The possible interposition of a conduit of the Venturi type could increase the effect of suction.

[0014] This makes it possible for the fabric to be better caught on the barrel so that it may be also better transported during its rotation for the missing weft to be positioned on the vertical of the cutting tool below. The intensity of the sucking power may be also adjusted by means of adequate mobile bulkheads (not shown), located on the vent 27 or on the conduit 30 next to the motor fan 12. Such adjustment could become necessary to adapt the sucking force to the type of fabric. By means of the air adjustment it is possible to vary the friction between the fabric and the barrel as well as the transportation so that a minimun longitudinal stretching of the fabric is obtained.

[0015] In a second preferred embodiment, shown in figure 2, the positioning device consists, besides the barrel 20, of a second barrel 220, rotating on its axis and supported by a pair of rods 33 engaged by their extremities to the conduit 14 and to the support 35 of the barrel itself, so that it is possible to change its position in relationship to the first barrel 20. The barrel 220 can be motorised and is useful to rotate the fabric as well as to act as counter-guide in order to avoid uncontrolled side-sliding of the fabric. In case the machine is used to cut light fabric and/or tubes which are not excessively wide, said barrel 220, can also be substituted by a simple horizontal guide.

[0016] The present invention is not restricted to the embodiments described and shown above, which are to be considered as examples of the embodiment of the centring device, which can be modified in its form and location of parts as well as constructive and functional details. The invention is intended to cover all the variants which are within its scope, as defined in the following claims.

Claims

1. Device for centring a tubular fabric on the cutting tool, adapted for a cutting machine of the type implementing motor barrels which rotate on their axis and are controlled by photoelectric cells positioned along the advance path of the fabric and located inside the tube formed by the fabric, being in contact with it and associated to a motor fan adapted to blow air inside said tube in order to stretch and widen it, characterised in that it consists of a single barrel (20) the side wall of which (23) is provided, along its whole circumference with through slots (25), adapted to put the outer surface in communication with means that suck air towards the inner part of the barrel (20).

2. Device as claimed in claim 1, characterised in that the means that suck the air consists of a vent (27) connected by a conduit (30) to the sucking point of said motor vent (12).

3. Device as claimed in claim 2, characterised in that the opening (26) of the vent (27) faces the plane defined by the cutting tool (15).

4. Device according to claim in the previous claims, characterised in that the opening of the vent (27) is connected, by means of a conduit (30), the flow of which can be adjusted, to the sucking point of said motor fan (12).

5. Device as claimed in claim 1 characterised in that the slots (25) present a rectangular profile.

6. Device as claimed in claim 1 characterised in that the barrel (20) is coupled to a second revolving barrel (220) the position of which can be adjusted by means of articulated arms (33).

7. Device as claimed in claim 6 characterised in that said second barrel (220) is motorised.

8. Device as claimed in claim 1 characterised in that a horizontal guide is associated with the second barrel (20), in an adjustable position.

Drawing