Apparatus for joining automatically the beginning and the end of a hem in a circular textile material

Abstract: Characterized by the initial phase in which the material is fed on to an entry roller (1) which receives the cloth from a flat guide (4,5), the said roller being inclined at the moment of the initial introduction of the material followed by the material being fed and guided with the principal roller being horizontal, this being followed by the pre-folding and final folding of the edge of the material prior to the stitching of the hem until the already sewn section of the hem reaches the entry of the guide unit, at which moment the said unit is displaced in parallel for the realignment of the hem stitching zone, following which the guide is separated.

Description: SPECIFICATION Many forms of so called circular cloths or textile materials require a hem on the full periphery of the cloth and various machines have been developed to provide this continuous hem which can then contain within its interior an elastic band, with the final stage of ending the hem being a manual operation. Circular cloths requiring such a closed form include fitted bed linen, table cloths and others where the cloth has to cover the object in question with its periphery adapted so that it encloses the the said object laterally. The final shape of the cloth, though denominated as circular need not be of that shape but could equally be square, rectangular or any other shape. From DE-A-38 31 034 a Sewing machine, especially designed for sewing circular cloth in particular three fold hem of the leg of trousers, is known. DE-A-26 32 541 and US 3,890,911 disclose further sewing machines provided with hemming means for circular cloth. However, none of the currently known machines ensure a detection of misalignment and subsequently operating alignment means. The apparatus, object of this patent has therefore as object the improvement of the machines currently known and employed for this purpose but providing a fully automatic operation to form the hem completely including the final stage of joining up the beginning of the hem with the end, the operation currently carried out by hand and as a further object the providing of detection of misalignment and alignment means ensuring a correct position of the edge of the cloth. This present invention patent facilitates therefore the fully automatic forming of the hem in a circular cloth and the detection and alignment of the cloth with an apparatus as described in claim 1. The apparatus according to the invention designed to carry out the automatical joining of beginning and end of a hem consists fundamentally of a first guide device, a second device for the first folding and final fold prior to stitching, the two devices being synchronized together with the various sections of the machine in which they are located and which correspond partly to currently known technical means of producing the work indicated herein. As an essential feature the guide unit in this present patent has a vertical guide zone consisting of flat plates emprisoning the cloth a guide roller successively and a system of pressure actuated rollers, adjustable at will, to provide the cloth alignment, the position being detected by a system of photo-electric cells, the whole assembly being carried on an arm which is mounted at entry and exit on a shaft which is parallel to the roller so as to provide for the two different positions of the assembly for guiding and feeding. The device for first and second folding, in this invention, comprises an arrangement which has as its characteristic a provision for detecting the previously made hem, causing the machine to stop and ejecting the cloth. For a better understanding of this specification explanatory drawings are provided showing by way of an example the process and the associated apparatus, objects of this present patent. Figure 1 is a perspective view of the guide and feed unit for the cloth according to this invention. Figure 2 is a perspective view of the same unit as in figure 1 shown from what is approximately the front part of the feed roller. Figures 3 and 4 show respectively the unit for the first and second fold operation which is a part of the apparatus, object of this patent. Figure 5 shows a variant of the component for the initial folding. As may be seen in figure 1 the guide and feed unit comprises a main roller -1- made up of two sections -2- and -3- one of which is fixed and the other mobile, this roller receiving the cloth which comes from a guide formed by the plates -4- and -5-, the first of which is fixed while the second can swing on a vertical hinge located on the edge opposite that seen in the figure, these two parts -4- and -5-providing guidance of the cloth which then passes to the roller -1-. Photo-electric cells, picking up the position of the cloth edge, the orifice -6- show-the position of one of them, cause the alignment of the material. When the cloth is misaligned the alignment roller -7- acts on the section -2- of the feed roller and the roller -8- acts against the plate -5-, both these rollers being set at a particular angle and coming into operation intermittently to realign the edge of the cloth until it arrives at its correct position. So as to allow the roller -1- to take up a horizontal working position and a position which is slightly inclined downwards for the entry and the ejection of the cloth the said rotating roller is mounted on a horizontal shaft capable of being acted on by a lower piston and cylinder assembly -9- which can cause an angular movement of roller -1- between the said horizontal and slightly inclined positions. At the same time a forward movement along an axis parallel to roller -1- of the guide and feed unit is required allowing the cloth to be fed for its normal stitching position along almost the entirety of the hem and then fed in another position corresponding to the final stage of joining the beginning and the end of the hem where it is necessary that the alignment of the stitching changes in relation to the stitching head so as to take into account precisely the presence of the already existing hem. To this effect the arm -10- which carries the guide and feed assembly can move vertically and laterally and thus assume the two required alignment positions. In conjunction with the roller -1-, a micro-switch -11-, figure 2, with a mobile arm -12- can operate and detect the entry of the already existing section of hem, signalling to a programmer which can cause the above mentioned changes of alignment which can then allow the operation of joining the beginning and the end of the hem to take place. The guide and feed unit operates in conjunction with the first and second fold unit shown in figures 3 and 4 in which may be seen the first fold device -13- and the final fold device -14- of the double articulation type. On entry the cloth undergoes its first fold by means of the open ring -15- or by means of a semi-envelopping pre-folding device -21- with a lateral wing -22-, figure 5, then passing to the final folding device -14- which is hinged to a mobile member -16- which in turn can girate on an axis -17-. This mobile member -16- is held by two magnets, one being the main magnet -18- and the other the secondary one, -19- with the magnetic strength of magnet -19- being less than that of the magnet -18-, the latter providing the effective retention of the member -16- in its closed position, corresponding to figure 4, that being the position of the normal stitching of the hem. On arrival of the already stitched hem extremity which has to be joined to the other extremity of the hem, the guide device -14- moves outwards as shown in figure 3, operating the micro-switch -20- and thus causing the machine to stop and the cloth to be ejected, this be transmitting a signal to the programmer, causing the plate 5 to swing on its axis to open, and the machine to stop and the roller -1- to descend and allow the ejection of the cloth. The above arrangements render possible the objects of this present patent which provides for a first phase in which the cloth is guided towards the pre-fold and folding unit then at the moment when the already hemmed extremity reaches the guide unit the assembly takes up a second position of alignment of the stitching in relation to the stitching head, then proceeding, once the already made section of hem reaches the prefold and folding device, to actuate the micro - switch which stops the machine, causes the outward swing of the guide roller and opening of the guide plate causing in turn the ejection of the cloth. The above means as indicated permit the machine to operate automatically in joining the beginning to the end of the hem in the so-called circular cloths of textile material. The interior of the hem may have within it a cord or elastic as the case may be. Anything not modifying altering or changing the essence of the described process is a variable for purposes of this invention patent.

Claims: An apparatus for joining automatically the beginning and the end of a hem in a circular textile material comprising a guide and feed unit equipped with a main roller (1), characterized in that the main roller (1) is made up by a fixed section (2) and a mobile section (3) inclinable in relation to the horizontal and fitted in a supporting assembly coupled to an arm (9) being displaceable in a lateral and vertical sense thereby providing two distinct working positions of the unit, which unit has a flat entry guide (4, 5) comprised of a fixed plate (4) and a moveable plate (5) which can swing on a vertical hinge both together providing guidance for the cloth before being fed to the roller (1), the unit further being combined with detection systems coupled with an alignment roller (7) acting on section (2) of the roller (1) and an alignment roller (8) acting against plate (5) of the guide unit causing automatically realignment of the cloth edge when required. The apparatus according to claim 1, characterized by , further comprising a prefolding device (13) and a final folding device (14) folding the cloth prior to sewing the hem, wherein the prefolding unit (13) works in conjunction with a piston and cylinder assembly which can cause its displacement while the final fold device (14) is removable on the arrival of the already sewn hem section with simultaneous operation of a microswitch (20) initiating the final cycle of the process including stopping the machine and the inclination of roller (1). The apparatus according to claim 1, characterized in that alignment roller (7) is held on a support which is subject to a variable pressure from a piston and cylinder pneumatic device and having an inclination adjustable from another piston and cylinder device actuated from the positioning of a photo-electric cell which can detect the position of the edge of the cloth and cause its realignment if required. The apparatus according to claim 1, characterized in that there is also a system of photo-electric cells to locate the edge of the material as fed in with the roller (8) for realignment perpendicular to the plane of the guide plates, operating through an aperture (6) in the fixed plate (4) with the pressure of a hinged arming on which it is mounted. The apparatus according to claim 2 characterized in that the final fold unit (14) comprises a guide ring on the edge of the cloth articulated at one extremity on a bridge member, hinged in turn at the other extremity to a fixed part on the machine and arranged so that it is in opposition to a system of permanent retention magnets (18, 19) and which retain the final fold unit (14) in position until the moment of entry of the already sewn hem, it being capable of swinging the assembly on the two axes of articulation separating the final fold ring (15) from the trajectory of the hem for joining the beginning and end thereof automatically. The apparatus according to claim 5, characterized in that , one of the permanent magnets (18) of greater strength, retains the articulated assembly firmly during the final folding while the other of lesser strength (19) is designed to cause the return of the articulated assembly to its work position once the final stitching of the cloth has been carried out.

Inventors: CARRERAS FONTCUBERTA FRANCISCO, CARRERAS FONTCUBERTA, FRANCISCO
Applicants: CARRERAS FONTCUBERTA FRANCISCO, TEXPA-ARBTER MASCHINENBAUGESELLSCHAFT MBH CARRERAS FONTCUBERTA, FRANCISCO
Application year: 1991
Main classification: D05B33
IPC codes: D05B33