A DOUBLING MACHINE FOR FABRICS.

Abstract

 Described herein is a doubling machine (1) for fabrics, comprising at least one contrast element (9) and one motor-driven driving device (6) for moving a strip of fabric (3), which is folded by a folding member (10), said doubling machine (1) further comprising a member for aligning the selvedges (11), controlled by a signal generated by a set of sensors (18), designed to detect the position of the selvedges (11), said folding member (10) being set at a level lower than said contrast element (9) and having an at least partially convex surface of envelope, on which the fabric (3) rests.

Description

[0001] The present invention relates to a doubling machine for fabrics according to the preamble of the main claim.

[0002] According to the state of the art, fabrics, produced in long strips, and before undergoing certain finishing operations, such as, for example, dyeing, washing, and fulling, are doubled, i.e., folded along a line on the longitudinal axis of the strip of fabric, and their lateral ends are aligned. Next, the lateral ends are sewn, in such a way that the strip of fabric will form a long tube, which, in the processes cited above, swells up creating an air cushion, which prevents any squeezing and consequent permanent folds, in order to protect the face of the product, which remains on the inside of the tube. The sewing made is a simple basting, and the fabric thus protected, folded and sewn is lapped and then stored.

[0003] Various types of doubling and sewing machines designed to provide such a basting of the fabric are known in the art.

[0004] Many years ago machines were used in which the strip of fabric moved horizontally suspended at the lateral ends by gripping elements such as inclined rollers, whilst the central part of the fabric was brought downwards by gravity. Such inclined rollers, the degree of closing of which was controlled by photo-electric cells that detected the alignment of the fabric, had the task of moving horizontally or drawing upwards separately each of the lateral ends of the strip of fabric, referred to as selvedges, then mutually aligning them precisely prior to the sewing operation. In these machines, proper mechanical control could be achieved only at very low r.p.m. so that the movement of the fabric proved very slow, and these machines were abandoned on account of their low output.

[0005] In currently produced machines, a doubling assembly and a sewing assembly may be distinguished. The doubling assembly performs the operation of doubling of the fabric by means of a folding element of a triangular shape. Various embodiments of this doubling assembly are possible. In one of the most common, the fabric slides down along an inclined surface, which, at its end, has a triangular shape. As the fabric arrives at the edges of the triangle, it changes direction of movement, folding over the sides of the triangle. The fabric is kept stretched by purposely provided tensioning elements, such as, for example, motor-driven rollers arranged in appropriate positions. There then exist alignment rollers which have the task of aligning precisely the lateral ends (selvedges) of the strip of fabric prior to sewing. Once the doubling operation has been performed with alignment of the selvedges, the sewing operation is carried out.

[0006] Current machines are quite complex on account of the fact that they envisage two or more distinct members to perform folding and precise alignment of the selvedges.

[0007] Furthermore, they can spoil the fabric, in particular elastic fabric, when it comes to rub against the vertex of the triangular folding element.

[0008] A rounding of the vertex of the triangle does not allow the tensioning rollers to function properly, and the fabric forms folds which cannot be eliminated subsequently.

[0009] An object of the present invention is consequently to provide a machine for doubling a strip of fabric, comprising folding and alignment of the selvedges, which will enable the aforementioned drawbacks to be overcome.

[0010] In particular, an object of the present invention is to provide a machine that is sufficiently fast and at the same time mechanically simple and hence less costly, in so far as it is made up of a smaller number of parts and is able to perform doubling of the fabric with just one member.

[0011] A further object is to reduce the risk of spoiling the fabric during the doubling operation.

[0012] The above objects are achieved by a machine the inventive characteristics of which are highlighted in the claims.

[0013] For a better understanding of the invention, there now follows a detailed description, provided merely by way of example, of a preferred embodiment shown in the annexed drawings, in which:

• Figure 1 is a side view of an embodiment of the doubling machine according to the invention; and
• Figure 2 shows a front view of said machine.

[0014] With reference to the figures, it may be noted that the doubling machine 1, in said first embodiment , has a frame 2 fixed to which are various members designed to pick up the fabric 3, fold it and align the selvedges, to prepare it for the subsequent sewing operation. Proceeding along the path followed by the fabric, it may be noted that fixed to the frame 2 comprises are two return idlers 4 and 5, a driving device 6, in turn comprising a driving roller 7 and a first motor 8, and a contrast element 9, which has the function of distending the fabric 3 and causing it to drop onto a folding member 10, formed by a cage having an ogival shape with the vertex facing upwards, rotatably mounted about its substantially vertical axis. In Figure 1, the fabric is illustrated so as to appear transparent, in order to show the folding member 10, which otherwise would be hidden within the two flaps of the fabric 3. Only the selvedges 11 of the fabric 3 and the line along which the fabric folds are represented in Figure 1.

[0015] The contrast element 9 can comprise a roller mounted so that it can rotate or, as in the example that is illustrated and is clearly visible in Figure 2, a fixed bar preferably arched upwards to enable a better alignment of the strip of fabric 3, prior to the folding operation.

[0016] In this first embodiment, a second motor 12 is present, hereinafter referred to as alignment motor, which is designed to rotate the folding member 10 about its vertical axis.

[0017] The selvedges 11 of the fabric 3 are gripped by two sets of tensioning rollers 13 and 14, each one of which is designed to grip one of the two selvedges 11 and to pull it backwards to the right, as viewed in Figure 1.

[0018] The action of the sets of tensioning rollers 13 and 14 has mainly the function of unrolling and flattening out, the selvedges 11 of certain fabrics that tend to roll up.

[0019] A further object of such sets of tensioning rollers 13 and 14 is to cause the fabric 3 to exert a sufficient pressure against the folding member 10 in such a way that, by rotating the folding member 10, the fabric 3 will follow it in its movement and the selvedges 11 may, in this way, be aligned.

[0020] Said pressure of the fabric 3 on the folding member 10 can however be generated, in a sufficient way, just by the weight of the fabric, which, by being withheld by the contrast element 9, as it drops comes to rest upon the folding member 10, which is set in a lower and more advanced position (further to the left as viewed in Figure 1) with respect to the contrast element 9.

[0021] The sets of tensioning rollers 13 and 14 are actuated respectively by a third motor 15 and by a fourth motor 16.

[0022] The folding member 10 is supported by a supporting arm 21 and is positioned on one of its ends. The other end of the supporting arm 21 is fixed to the frame 2 of the machine in such a way that the supporting arm 21 can slide horizontally, actuated by a fifth motor 17, for example with a worm-screw mechanism.

[0023] Said worm-screw mechanism enables the supporting arm 21 to be positioned by the fifth motor 17 and remain in position irrespective of whether the fabric 3 exerts a pressure thereon, tending to displace it to the right (as viewed in Figure 1).

[0024] The folding member 10, as viewed in Figure 1, must be positioned on the bottom left with respect to the contrast element 9. This enables the fabric 3 to drop by gravity, rest on the folding member 10, fold over it, and, once again by gravity, press sufficiently against the folding member 10 so as to follow the movements thereof even in the case where the sets of tensioning rollers 13 and 14 were not present or were not to exert their action by pulling the fabric 3 to the right (as viewed in Figure 1), but exclusively unrolling the selvedges 11.

[0025] A set of sensors 18, comprising, for instance, two pairs of photo-electric cells slightly staggered with respect to one another, detects precisely the position of each of the selvedges 11 after they have been unrolled by the sets of tensioning rollers 13 and 14.

[0026] The position of each of the selvedges 11 of the strip of fabric 3 is detected by a pair of slightly staggered photo-electric cells. In the correct position of alignment, each selvedge 11 must cover one of the photo-electric cells of the pair and leave the other uncovered.

[0027] When the selvedges 11 are not well aligned, both of the photo-electric cells of one pair are covered by the fabric, whereas those of the other pair are uncovered.

[0028] In this case, the set of sensors 18 sends a signal to the alignment motor 12 in such a way that it will cause rotation of the folding member 10 until the selvedges 11 are aligned.

[0029] Operation of the set of sensors 18, designed to detect proper alignment of the selvedges 11 and to issue a command signal to a member for alignment of the selvedges is in itself already known and commonly used by other doubling machines.

[0030] The set of sensors 18 is also able to govern the fifth motor 17, which moves the supporting arm 21.

[0031] This can occur for example in the case where the strip of fabric is too narrow and all the photo-electric cells of the set of sensors 18 are uncovered. In this case, the set of sensors 18 issues a signal for displacing the supporting arm 21 to the right (as viewed in Figure 1) and bringing back the selvedges 11 into the correct position.

[0032] Clearly, in the opposite case, i.e., when the strip of fabric 3 is too wide, all of the photo-electric cells of the set of sensors 18 are covered, and the set of sensors 18 thus issues a command signal to the fifth motor 17 for displacing the supporting arm 21 to the left (as viewed in Figure 1) and bringing back the selvedges 11 into the correct position.

[0033] In the specific case, the doubling machine 1 further comprises a horizontal roller 19 (Figure 1), which is driven by a sixth motor 20 and is designed to receive the fabric 3 thus doubled, i.e., folded and with the selvedges aligned, and to deviate it in the horizontal direction so that it is ready for the subsequent sewing operation, which can thus be carried out by a horizontal sewing machine (not represented in the figures), which is simpler and less costly than a vertical sewing machine.

[0034] With reference to Figure 2, it may be noted that the sets of tensioning rollers 13 and 14 each comprise four rollers, the surfaces of which are screw-shaped so as to grip the fabric 3 and pull it backwards (towards the right in Figure 1).

[0035] The fabric 3 is made to pass between said tensioning rollers, which perform also the task of unrolling and flattening out the selvedges, which, in particular for certain fabrics, tend to roll up.

[0036] Depending on whether or not said tensioning rollers will have to carry out a more or less strong action, the fabric can pass twice or once between the rollers.

[0037] The top roller can be appropriately oriented by causing it to rotate about a vertical axis.

[0038] Also this adjustment can be made in order to regulate the strength of the action of the tensioning rollers.

[0039] When the doubling machine is set in operation, the fabric 3, introduced therein, is picked up thanks to the force applied by the driving device 6.

[0040] The fabric 3 moves, along to the direction indicated by the arrow, passing over the return idlers 4 and 5, then under the driving roller 7, and next above the contrast element 9, where it then slides downwards dropping on the folding member 10 that is approximately on the centre line of the strip of fabric 3.

[0041] The fabric 3 tends to drop by gravity along the vertical axis of the contrast element 9.

[0042] The presence of the folding member 10 set on the centre line of the strip of fabric 3 causes only the selvedges 11 to drop approximately along the vertical axis of the contrast element 9, whilst the central part of the strip of fabric 3 rests on the folding member 10, thus forming the desired fold.

[0043] The alignment motor 12, driven by the set of sensors 18, acts on the folding member 10 causing it to rotate about its vertical axis by the amount necessary for the selvedges 11 to be properly aligned and ready to be set on top of one another precisely at the moment of passage over the surface of the horizontal laying roller 19.

[0044] The sets of tensioning rollers 13 and 14 grip the selvedges 11, unrolling them, in the case where they are rolled up.

[0045] After the fabric 3 has passed under the horizontal roller 19, it is brought into the horizontal position, ready for the operation of sewing of the selvedges 11 correctly set on top of one another.

[0046] With reference to Figure 2, it may be noted that, after the operation of doubling and sewing, the fabric 3 is finally brought, through passages over further rollers visible in Figure 2, to the oscillating arm 24, which neatly arranges the fabric 3 in an appropriate container 25.

[0047] The supporting arm 21, actuated by the fifth motor 17, can position the folding member 10 in a more advanced or else more retracted position.

[0048] The optimal position of the folding member 10 depends upon the width of the strip of fabric 3, since the selvedges 11 have to reach the tensioning rollers 13 and 14 so as to be gripped thereby.

[0049] A narrower strip of fabric 3 requires a more retracted position of the tensioning member 10 (i.e., shifted towards the right as viewed in Figure 1), whereas a wider strip of fabric 3 requires a more advanced position of the tensioning member 10 (i.e., shifted towards the left as viewed in Figure 1).

[0050] Even more important is that the folding member 10 be set in a position such that the selvedges 11 reach the area in which their position can be read by the set of sensors 18.

[0051] An excessively advanced or excessively retracted position of the supporting arm 21 could prevent proper operation of the machine.

[0052] Of course, the mutual position of the folding member 10 and the set of sensors 18, and of the folding member 10 and the sets of tensioning rollers 13, 14 is important. Thus one could be moved and the others be kept stationary, as in the embodiment illustrated herein, or vice versa.

[0053] In the case of a fabric the selvedges of which do not tend to roll up, the sets of tensioning rollers could be absent.

[0054] In this case, of particular importance is the fact that the set of sensors 18 controls continuously the fifth motor 17, which moves the supporting arm 21, to prevent that a local narrowing of the strip of fabric 3 uncovers both pairs of photo-electric cells, thus preventing operation of the machine.

[0055] In the event that this happens, a command is issued to the fifth motor 17 to move the supporting arm 21 into a more retracted position (to the right, as viewed in Figure 1).

[0056] Instead, in the case where both pairs of photo-electric cells of the set of sensor 18 are covered by the fabric 3, a command is issued to the fifth motor 17 so that this will displace the supporting arm 21 into a more advanced position (to the left, as viewed in Figure 1).

[0057] This may occur, for example, in the case where the strip of fabric has become locally narrower, and this consequently causes both pairs of photo-electric cells of the set of sensors 18 to be simultaneously uncovered. In this case, the set of sensors 18 issues a command to the fifth motor 17 so that this will displace the supporting arm 21 to the right (as viewed in Figure 1), to bring the selvedges 11 back again into the correct position.

[0058] The folding member 10 can of course have a shape other than the ogival one, but it is in any case preferable for it to have a rounded surface of envelope at least at the sides and hence non to have sharp edges at the sides, which could damage the fabric.

[0059] It is preferable to think in terms of surface of envelope as regards the folding member 10, in so far as it could, for instance, be made as a cage with slats that are plane but arranged in such a way as to form a curved surface of envelope.

[0060] Furthermore, a cage structure renders the folding member light, and the individual bars are more suited for gripping the fabric and drawing it without damaging it.

[0061] In the case where the folding member is rotatably mounted so that it can rotate about a vertical axis, it is not strictly necessary for the axis to be perfectly vertical, but it is sufficient for said axis to be substantially vertical.

[0062] The folding member could have a convex surface of envelope with a single curvature; for instance, it could be a cylinder rotatably mounted so that it can turn about its own axis.

[0063] Preferably, said surface of envelope has a double curvature, precisely to prevent the fabric 3, as it drops from above and is withheld backwards by the contrast element 9, from touching non-curved and sharp parts at the edge of the surface of the folding member.

[0064] For example, the folding member 10 may have a surface of envelope shaped like a paraboloid, with the vertex upwards (the ogival shape already described), or else shaped like an ellipsoid, or more simply spherical.

[0065] An advantageous characteristic of the invention is that the sets of the tensioning rollers 13 and 14 mainly have the purpose of unrolling the selvedges 11, whereas, in particular when the fabric 3 is in itself quite heavy, their contribution in tensioning the fabric can prove unnecessary.

[0066] This enables, in the case of a fabric that does not present the problem of having the selvedges rolled up, provision of a machine that operates perfectly even without the presence of the sets of tensioning rollers 13 and 14.

[0067] Alignment of the selvedges is performed by what as a whole can be referred to as member for alignment of the selvedges. As has been seen, in the first embodiment of the invention, said member comprises the folding member 10, which can rotate about its own vertical axis, and the alignment motor 12, which actuates the folding member 10.

[0068] A second embodiment of the doubling machine can be obtained by eliminating the alignment motor 12 and rendering the folding member 10 idle about its vertical axis.

[0069] In this case, the action of alignment of the selvedges 11 is performed by the sets of tensioning rollers 13 and 14 appropriately actuated on the basis of the signal coming from the set of sensors 18.

[0070] In this second embodiment, the member for alignment of the selvedges hence comprises the sets of tensioning rollers 13 and 14 and the motors 15 and 16 designed to actuate them.

[0071] In this second embodiment, it is also possible for the folding member 10 to be fixed and hence not be able to rotate about a vertical axis.

[0072] In fact, in this second embodiment, the rotation about the vertical axis of the folding member 10 has only the purpose of reducing the friction in the movement of alignment of the selvedges 11. The reduction of said friction can also be obtained by providing a sufficiently smooth surface of the folding member 10.

[0073] In the case of a fixed folding member 10, its shape can even not be axisymmetrical.

[0074] It is sufficient for the surface of envelope of the folding member 10 on which the fabric 3 rests to be convex so as to favour folding and not damage the fabric. For example, said surface could be cylindrical with a vertical axis, having as directrix a semicircle and with its convexity facing the fabric 3.

[0075] Also in this case, a surface of envelope with double curvature is however preferable, at least in the part on which the fabric 3 rests, to prevent the fabric from coming into contact with sharp parts at the edge of the resting surface of the folding member.

[0076] For operation of this second embodiment, if, for example, the selvedge that passes through a first set of tensioning rollers 13 is more advanced than the other, a command is issued to the third motor 15, which actuates the set of tensioning rollers 13, for accelerating compared to the fourth motor 16, which controls the set of tensioning rollers 14, until the selvedges 11 are perfectly aligned.

[0077] Consequently, by adjusting differently the speeds of the tensioning rollers 13 and 14, it is possible to align the selvedges 11.

[0078] In a third embodiment, the member for aligning the selvedges comprises a centring member, in itself already known to the art, which centres the strip of fabric 3 prior to its arrival on the contrast element 9 and its descent onto the folding member 10, in such a way that after folding the selvedges 11 are already aligned.

[0079] Said centring members can comprise, for example, a roller made up of staves with a set of photo-electric cells, which detect the position of the fabric 3 distended thereon and bring about orientation of the staves to align the fabric in a pre-defined position, central with respect to the folding member.

[0080] This third embodiment is suitable for fabrics the selvedges of which do not tend to roll up.

[0081] In this embodiment, the sensor 18 is set upstream of the folding element 10, and the presence of sets of tensioning rollers for unrolling the selvedges and possibly aligning them is not necessary.

[0082] Neither is it necessary for the folding member 10 to be mounted so that it can rotate, nor for it to be motor driven for aligning the selvedges, which are automatically aligned by the operation of centring of the fabric 3 carried out prior to folding.

[0083] The fact that the folding member 10 is free to rotate about its own vertical axis enables the sets of tensioning rollers 13 and 14 to act with a lower stress and to prevent the fabric 3 from rubbing against the surface of the folding member 10, hence running the risk of damaging it.

[0084] Of course, instead of acting selectively on the speeds of the sets of tensioning rollers 13 and 14, it is also possible to adjust their inclination, which enables variation of the grip on the fabric 3 and hence application on the selvedges of different forces designed to align them.

[0085] For example, with reference to Figure 2, the two tensioning rollers 22 and 23 can be oriented in an appropriate way by rotating them about a substantially vertical axis to obtain a greater or smaller grip according to the requirements.

[0086] In the example of embodiment described, this adjustment is possible, but is performed with the machine not running.

[0087] Without any great difficulty, it would be, however, possible to orient at least one of the two tensioning rollers 22 and 23 appropriately, causing it to rotate about a substantially vertical axis, in response to a signal coming from the set of sensors 18.

[0088] This would entail a different grip of the sets of tensioning rollers on the selvedges 11, enabling their alignment.

Claims

1. A doubling machine (1) for fabrics comprising at least one contrast element (9) and one motor-driven driving device (6) for moving a strip of fabric(3), which is folded by a folding member (10), said doubling machine (1) further comprising a member for aligning the selvedges (11), governed by a signal generated by a set of sensors (18), designed to detect the position of the selvedges (11), said doubling machine (1) being characterized in that said folding member (10) is set at a level lower than said contrast element (9) and has an at least partially convex surface of envelope, on which the fabric (3) rests.

2. Doubling machine (1) for fabrics according to Claim 1, characterized in that said folding member (10) has a surface of envelope with double curvature.

3. Doubling machine (1) for fabrics according to Claim 1, characterized in that said folding member (10) has an axisymmetrical shape about a substantially vertical axis.

4. Doubling machine (1) for fabrics according to Claim 3, characterized in that said folding member (10) is mounted in a rotatable way about a substantially vertical axis.

5. Doubling machine (1) for fabrics according to Claim 1, characterized in that said folding member (10) comprises a cage.

6. Doubling machine (1) for fabrics according to Claim 4, characterized in that said member for aligning the selvedges comprises an alignment motor (12), designed to cause the folding member (10) to rotate about its own substantially vertical axis.

7. Doubling machine (1) for fabrics according to Claim 1, characterized in that said folding member (10) is fixed and in that the member for aligning the selvedges comprises sets of tensioning rollers (13, 14) for tensioning the selvedges, and the motors (15, 16) designed for actuating them.

8. Doubling machine (1) for fabrics according to Claim 4, characterized in that said folding member (10) is idle with respect to its own axis and in that the member for aligning the selvedges comprises sets of tensioning rollers (13, 14) for tensioning the selvedges, and the motors (15, 16) designed for actuating them.

9. Doubling machine (1) for fabrics according to Claim 1, characterized in that said folding member (10) is supported by a supporting arm (21), which can slide horizontally.

10. Doubling machine (1) for fabrics according to Claim 9, characterized in that the position of said supporting arm (21) is adjusted according to a signal coming from the set of sensors (18).

11. Doubling machine (1) for fabrics according to Claim 1, characterized in that it comprises a horizontal laying roller (19), designed to cause the folded fabric (3) to slide in a horizontal direction with the selvedges aligned.

12. Doubling machine (1) according to Claim 7 or Claim 8, characterized in that said set of sensors (18) controls the orientation, obtained by means of a rotation about a substantially vertical axis, of at least one tensioning roller (22) comprised in the set of tensioning rollers (13).

13. Doubling machine (1) according to Claim 7 or Claim 8, characterized in that said set of sensors (18) selectively controls the speed of operation of the set of tensioning rollers (13, 14).

14. Doubling machine (1) for fabrics according to Claim 1, characterized in that said folding member (10) is fixed and in that the member for aligning the selvedges comprises a centring member for centring the strip of fabric set upstream of the folding member (10).

Drawing