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(11) | EP 1 138 816 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Stretcher for tubular knitwear |
| (57) A stretcher for tubular knitwear fabric, comprising: two stretcher arms (5, 6), the
drive wheels (7a, 7b), wheels (8) in contact with the contact wheels (7a, 7b) and
mounted on the arms (5, 6), a first magnet (21) that is fixed onto a fixed sustainment
mount [9) and a second magnet (22) on each arm (5, 6) in front of the first magnet,
the magnets being oriented in a repulsion relationship in contrast to the rotation
of the arm (5, 6), such that the vertical sustainment of the arm is thus a maintained. |
[0001] The object of the present invention is a stretcher for tubular knitwear fabric, to be applied in particular to calenders and other machines for the treatment of tubular fabric.
[0002] It is known that in the course of tubular knitwear fabric finishing stretchers are used to stretch and spread the tubular item in order to ease the finishing operations.
[0003] Thus in calendering, which is usually the last finishing operation, it is necessary to use a stretcher in order to achieve a uniform steaming and to adjust the width of the tubular item onto the desired value.
[0004] There are known, for example from patent PCT/IT99/00344 of the same proprietor as the present invention, stretchers for tubular fabrics with horizontal magnetic sustainment of the two stretcher arms along which the fabric slides by means of advancement wheels that are coupled to transmission belts.
[0005] There is also known the European patent application NO. 900,872 concerning a stretcher for tubular fabric that comprises two stretcher arms that are sustained in the vertical direction by magnets. In particular, each arm is provided with two bipolar magnets, and four magnet pairs are attached to the fixed parts of the stretcher that are adjacent to the arms. Thus a repulsion force is generated between the magnet pairs and the corresponding bipolar magnets. By means of this complicated system the arms are prevented from moving vertically.
[0006] The object of the present invention is a simple efficient device for the vertical magnetic sustainment of the arms of a tubular fabric stretcher.
[0007] The features, advantages and the solution of the above-mentioned technical problem will be evident from the detailed description hereinbelow of a preferred, non limiting embodiment of the subject stretcher, said embodiment being illustrated in a merely exemplary, non limiting way in the accompanying figure, in which:
Figure 1 shows a front view of the stretcher;
Figure 2 shows an enlarged fragmentary horizontal cross-sectional view of a stretcher through line II-II of Figure 1; and
Figure 3 shows an enlarged fragmentary horizontal cross-sectional view of the stretcher through line III-III of Figure 1.
[0008] Referring now to figure 1, the subject stretcher is comprised of stanchions 1 and 2 in which the various control and drive mechanisms are contained.
[0009] Said stanchions support the per se known steamer 3, through which the tubular fabric is caused to run after passing through the stretcher.
[0010] Said stretcher is comprised of the stretcher arms 5 and 6, which in turn are held on the hereinbelow described support devices.
[0011] Within stanchions 1 and 2, motor means hereinbelow described transmit the motion to the upper drive wheels 7a, and thus means not shown in the figure can determine the displacement in opposite directions of the stretcher arms 5 and 6, so as to possibly change the width of the tubular fabric.
[0012] The upper drive wheels 7a are coupled to the similar lower wheels 7b through means that are specified hereinbelow.
[0013] As can clearly be seen from figures 1 and 2, the stretcher arms 5 and 6 are provided with wheels or rings 8 that are suitably shaped and are arranged in front of the convex part the drive wheels 7a and 7b are provided with. The latter in turn exhibit the supports 9 that carry the inclined axis (12) wheel pairs 10 and 11. Said wheels 10 and 11 are spaced apart with their peripheral parts from the circumferential outlines 8' of rings 8, this being due to the magnetic attraction force, as will be described later on.
[0014] The transportation of the tubular fabric 4 is obtained by means of belts 13 that are wound around a set of idle pulleys 14 on arms 5 and 6 along the outlines of the drive wheels 7a and 7b and of the rings 8.
[0015] As can clearly be seen from figure 1, both of the inclined wheels 10 are motor-driven as they are coupled to one another by means of an elastic belt 15 that is wound on drive wheels 7a and 7b.
[0016] In a similar way, the inclined wheels 11 are motor driven as they are coupled by means of an elastic belt with the same drive wheels 7a and 7b.
[0017] Said motor drive has the advantage that the transportation of the fabric is markedly improved.
[0018] In particular, the supports 9 carry the fork shaped brackets 16 for the adjustment of the working angles of arms 5 and 6.
[0019] The wheels 10 and 11 are kept spaced apart from the rings 8 by means of magnets 17, 18 that respectively attract the arms 5 and 6 outwards as shown by arrows B. said rings 8 canied by arms 5 and 6 remain spaced apart from the inclined wheels 10 and 11, and are attracted against the drive wheels 7a and 7b by said magnets 17 and 18, and the fabric is advanced between the belts 13 and the drive wheels 7a and 7b.
[0020] It is moreover to be pointed out that the attraction force of magnets 17 and 18 can be adjusted, thereby assuring that rings 8 are spaced apart from the inclined wheels 10 and 11.
[0021] Said adjustment is obtained by means of a mechanism that takes the magnets 17 and 18 closer to a farther from arms 5 and 6 respectively. In fact magnets 17 and 18 are coupled to said mechanism that is provided with an adjustment hand grip 19, which is adapted to move closer or farther the magnets 17 and 18 to and from the supports 17' and 18' that are fixed to bars 5 and 6.
[0023] The apparatus is operated as follows: the tubular fabric 4, that usually consists of various tubular pieces that are sewn together, is introduced upwards, as can be seen from figures 1 and 2, between wheels 10 and 11 and ring 8 and between ring 8 and wheels 7a and 7b of each arm and is thus transported upwards as indicated by arrow A upon rotation of the drive wheels 7a and 7b that are coupled to rings 8 and to pulleys 14 that are mounted on the arms 5 and 6, said arms being kept in position and sustained by the attraction force of magnets 17 and 18.
[0024] When a larger width of the tubular fabric is desired to be obtained, the arms 5 and 6 are displayed relative to one another until they reach the maximum distance shown in the positions of figure 1.
[0025] In case of an emergency, where the magnets should be in such a position as not to attract the arms 5 and 6, the latter would nonetheless remain in position because the rings 8 would lean with their circumferential outlines 8' against the wheels 10 and 11. However, such a situation would be temporary and would become normal again upon a proper adjustment of the position of magnets 17 and 18 by means of handgrips 19.
[0026] According to the new feature of the present invention, that is shown especially in figure 3, the magnetic vertical sustainment device of the arms 5, 6 of the stretcher comprises a first magnet 21 on the fixed sustainment parts 9 of the stretcher and a second magnet 22 facing said magnet 21 on each arm. The centre of gravity 23 of the stretcher arm 5, 6 is spaced apart from the point of contact of the drive wheel 7a with the wheel 8, said point of contact consisting of the profiled circumferential end portion 8' embracing the outer part of drive wheel 7a with alignment between said wheels.
[0027] Accordingly, the force of each arm generates a moment relative to said point of contact such that, in order to prevent the stretchers arms from rotating downwards, the two magnets 21, 22, that are oriented in a repulsion relationship, create a reaction to the rotation of every arm and allow it to be sustained vertically.
1. A tubular fabric stretcher comprising: idle pulleys (14) for the advancement of the
fabric and at least one wheel (8) that is provided with a circumferential profile
(8') that embraces a drive wheel (7a) at a contact point, the pulleys (14] and the
wheels (8) being supported by the two stretcher arms (5, 6) and said drive wheel (7a)
being carried on a fixed sustainment mount (9) of the stretcher, characterized in that, in relation with every stretcher arm (5, 6), a first magnet (21) is attached on
the fixed sustainment mount (9) and a second magnet [22) is fixed in front of the
first magnet (21) at a point of the arm (5, 6), the two magnets (21, 22) being oriented
in a repulsion relationship such that the vertical sustainment of the stretcher arm
(5, 6) is maintained in contrast to the arm (5, 6) rotation moment relative to the
point of contact, said moment being generated by the weight force of the arm.
2. A stretcher according to claim 1, characterized in that the centre of gravity (23) of each stretcher arm [5, 6) is spaced apart from the
point of contact where the wheels (8) and (7a] are aligned.
3. A stretcher according to claim 2, characterized in that said centre of gravity (23) is between said point of contact and the magnet (22)
that is attached to arm [5, 6).