EP0664354A1

EP0664354A1 - Method for positioning the edges of two cloths to be joined by stitching in a sewing machine and device for performing this method

Info

Publication number: EP0664354A1
Application number: EP95100119A
Authority: EP
Inventors: Roberto Resta
Original assignee: Resta SRL
Current assignee: Resta SRL
Priority date: 1994-01-10
Filing date: 1995-01-05
Publication date: 1995-07-26
Also published as: ITBO940003A1; ITBO940003A0; IT1273211B

Abstract

A method for positioning the edges of two cloths (1,10) to be joined by means of a stitching line in a sewing machine, characterized in that, during a first step, a longitudinal enlarged portion (9) that is continuous over the entire length to be joined of the edges is formed along each edge; in that, during a second step, the enlarged portions (9) are guided through respective guiding channels that guide them so that when the enlarged portions (9) exit from the channels they are parallel and adjacent; and in that, during a third step, when they exit from the channels, the edges are joined to each other by means of stitching lines that run along the longitudinal enlarged portions.

Description

The present invention relates to a method for positioning the edges of two cloths to be joined by stitching in a sewing machine and to a device for performing this method.
In the hereinafter description, the term "cloth" refers to any type of flexible surface constituted by one or more layers of fabric or the like combined with one or more layers of soft material such as wool or sponge rubber.
The invention is particularly but not exclusively aimed at producing the covering of innerspring mattresses.
It is known that the coverings of innerspring mattresses are constituted by an upper and a lower cloths which are rectangular and are mutually connected by a perimetric band. The band is coupled to the cloths by stitching with the aid of a so-called hemming machine which stitches together the adjacent edges of the band and of the cloths.
Current hemming machines, however, do not allow to automate the stitching step since there are no devices that guide the edges under the sewing head. The edges are currently positioned manually by expert workers while stitching advances, therefore entailing a greater use of labor.
A principal aim therefore of the present invention is to provide a new method that allows to position the edges to be joined without resorting to manual interventions and thus to fully automate the stitching cycle.
This aim is achieved by a method for positioning the edges of two cloths to be joined by means of a stitching line in a sewing machine, characterized in that, during a first step, a longitudinal enlarged portion that is continuous along the entire length to be joined of said edges is formed along each edge; in that, during a second step, said enlarged portions are guided through respective guiding channels that guide them so that said enlarged portions are parallel and adjacent when they exit from said channels; and in that, during a third step, when they exit from said channels, said edges are mutually joined by means of stitching lines that run along said longitudinal enlarged portions.
Within the scope of this aim, an object of the present invention is a device for performing the above method. The characteristics of said device are defined in claims 4 to 8.
Further features of the present invention will become apparent from the following detailed description of a preferred but not exclusive embodiment thereof, given only by way of non-limitative example in the accompanying drawings, wherein:

figure 1 is a perspective view of the region where two cloths are mutually joined;
figure 2 is a perspective view of a portion of cloth in which a profiled element is associated with the edge and forms a rib;
figure 3 is a view of a further embodiment in the formation of the rib along the edge;
figure 4 is a plan view of the device for positioning the edges of the cloths to be joined;
figure 5 is a sectional view, taken along the plane V-V of figure 4;
figure 6 is a sectional view, taken along the plane VI-VI of figure 4;
figure 7 is a perspective view of a detail of the device.

With reference to figure 2, the reference numeral 1 designates a generic cloth which in order to set the conceptual framework is assumed to be meant to form the covering of mattresses. The cloth 1 thus has a rectangular shape and is constituted by an outer fabric 2 and by an inner fabric 3 between which a layer 4 of spongy elastic material, for example sponge rubber, is placed. The fabrics 2 and 3 and the layer 4 are mutually joined by quilting lines 5 having any pattern.
A profiled element 6 made of flexible material, for example plastics, is fixed to the perimetric edge of the cloth 1.
The cross-section of the profiled element 6 is composed of a flat wing 7, on which the edge of the cloth 1 is fixed by means of a stitching line 8, and of a rib 9 that protrudes from one face of the wing 7, forming a longitudinal tubular enlarged portion.
During the execution of the covering of the mattress, two cloths 1 are arranged above and below a metal cage that forms the elastic frame of the mattress, and their perimetric edges are mutually connected by a band that perimetrically surrounds the cage.
Figure 1 illustrates the region where an upper cloth 1 and the perimetric band 10 of the covering of the mattress join; said perimetric band is assumed to be constituted substantially like the cloth 1, that is to say, to be composed of a single- or multilayer cloth having, along its parallel edges, respective profiled elements 11 which are identical to the profiled elements 6 of the cloth 1.
During the mutual coupling step, the band 10 is arranged at right angles to the cloths 1, as shown in figure 1, so that the wings 7 of the profiled elements 6 and 11 are in contact on the plane that bisects the right angle delimited by the cloth 1 and by the band 10.
A tape 12 is then applied on the profiled elements thus arranged by means of a hemming machine 13 (see figures 5 and 6) and covers the joint.
The hemming machine 13 is preferably tilted by 45^o with respect to the cloths 1, so that the stitching needle 14 can pass at right angles through the wings 7 and join them, covering them with the tape 12, along the stitching line 15 (figure 1).
A fundamental prerogative of the present invention is the provision of a device that allows to guide the edges to be joined of the cloths 1 and of the band 10, so as to avoid on one hand the need to resort to specialized personnel capable of performing this operation manually and, on the other hand, allow to automate the mutual assembly of the cloths and of the band.
Said device (see figures 4 and 6) comprises a sort of clamp 16 which is located upstream of the hemming machine and is composed of a stationary plate 17, which is fixed in any manner to the supporting framework of the hemming machine 13 at right angles to the needle 14 and thus at 45^o with respect to a horizontal working surface.
Two levers 18 and 19 are articulated on the opposite faces of the flat plate 17; each lever is composed of two arms 20, 21 and 22, 23. The articulation points are constituted by pivots 24, 25 which are supported by lobes 26, 27 that protrude from the plate 17 with which they are rigidly associated.
The arms of each pair delimit an obtuse angle between them. A spring 28 furthermore acts between the pair of arms 21 and 23 and keeps them spaced apart, so that the other two arms 20 and 22, which constitute the jaws of the clamp 16, rest on the opposite faces of the plate 17.
Respective recesses 29 and 30 are formed at the ends of the arms 20 and 22 on the side directed towards the plate 17; when the arms 20 and 22 rest on the plate 17, they form channels whose cross-section is complementary to the cross-section of the profiled elements 6 and 11, so as to allow to position and guide the cloths and the band during stitching, as will become apparent hereinafter. Accordingly, each channel comprises a rounded portion for the passage of the ribs 9 of the profiled elements 6 and 11 and a flattened portion through which the wing 7 slides together with the edge of the cloth fixed thereto.
Conveniently, as shown in figure 4, the clamp 16 is orientated at 45^o with respect to the edges of the cloth and of the band 10 so that it is possible to act on the levers 18 and 19 without being hindered by other parts of the device. Accordingly, the channels 29 and 30 pass obliquely through the arms 20 and 22 of the clamp to be aligned with the profiled elements 6 and 11.
As mentioned above, the clamp 16 is arranged upstream of the hemming machine 13. The axis of the needle 14 is designated by the same reference numeral in figure 4. The letter A designates the direction of the movement of the product during stitching, and conveniently the channels 29 and 30 form a guide in the direction A to facilitate the entry of the profiled elements 6 and 11 therein.
A block 31 is arranged between the needle 14 and the clamp 16 and keeps the edges of the cloth 1 and of the band 10 in position while the tape 12 is applied to them.
Said block 31 (see figure 7) is constituted by a body which is fixed to a stationary bracket 32 and has, at right angles to the direction A, a semicircular slit 33 that ends with a 45^o chamfer 34 arranged on a plane that is parallel to the plane of the clamp 16.
A cavity 35 is formed on the side of the block 31 that lies opposite to the side where the tape 12 enters; said cavity is shaped like a letter U that is open towards the edge of the product. The cavity 35 is narrower than the slit 33, so that two ribs 36 and 37 form at the chamfer 34, allowing to overturn and bend the tape 12 in a U-like shape in the direction A above the profiled elements 6 and 11 of the cloth 1 and of the band 10.
The operation of the described device is as follows.
In a first step, the profiled elements 6 and 11 are applied along the edges of the cloths 1 and of the band 10 that must be joined. The edges are then aligned on the opposite faces of the plate 17 and, while the clamp 16 is kept open, are arranged at the channels 29 and 30. By closing the clamp, the profiled elements 6 and 11 engage in the channels 29 and 30, which keep them exactly mutually opposite as they advance below the stitching needle 14.
It should be noted that the edges of the cloth 1 and of the band 10 are guided and positioned automatically, without corrective actions on the part of the personnel.
Furthermore, the exact match between the profiled element 6 of the cloth 1 and the profiled element 11 of the band 10 allows to apply the tape 12 automatically so as to cover the joint.
Numerous modifications and variations are possible in the practical execution of the invention, and all are within the scope of the inventive concept.
In particular, the formation of a longitudinal enlarged portion along the edges of the cloth and of the band can be provided as shown in figure 3, by wrapping the edge of the cloth around a simple longitudinal element 38 which can be constituted by a profiled element having a circular cross-section or a cord or the like.
Furthermore, the edge of the cloth can be fixed to the profiled element by hot-welding or glueing.
Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

Method for positioning the edges of two cloths (1, 10) to be joined by means of a stitching line in a sewing machine (13), characterized in that, during a first step, a longitudinal enlarged portion (9, 38) that is continuous over the entire length to be joined of said edges is formed along each edge; in that, during a second step, said enlarged portions (9, 38) are guided through respective guiding channels (29, 30) that guide them so that when said enlarged portions exit from said channels they are parallel and adjacent; and in that, during a third step, when they exit from said channels, said edges are joined to each other by means of stitching lines that run along said longitudinal enlarged portions.
Method according to claim 1, characterized in that said enlarged portion is constituted by a profiled element (6) which comprises a wing (7), on which the edge of the cloth is fixed by stitching (8), and a rib (9), which protrudes from one face of said wing (7).
Method according to claim 1, characterized in that said enlarged portion is formed by wrapping the edge of the cloth around a longitudinal element such as a profiled element (38) having a circular cross-section or a cord.
Method according to one of claims 1 to 3, characterized in that a joint covering tape (12) is applied while the positioned edges are being joined.
Device for performing the method according to one of claims 1 to 4, characterized in that it comprises a clamp element (16) which is located upstream of the hemming machine (13) and is composed of a stationary plate (17) on which two levers (18, 19) are articulated on opposite sides, said levers having respective arms (20, 22) which constitute the jaws of the clamp in which recesses are formed on the side directed towards said plate, said recesses forming channels (29, 30) when the jaws (20, 22) rest on the opposite faces of the plate (17), said channels having a cross-section that is substantially complementary to the cross-section of said longitudinal enlarged portions (9).
Device according to claim 5, characterized in that it comprises elastic means (28) for keeping said jaws (20, 22) in contact with said plate (17).
Device according to claim 5 or 6, characterized in that a block (31) is arranged between said clamp element (16) and the needle (14) of the sewing machine (13) and is provided with guiding and bending means (33-37) for applying a tape (12) to cover the joint region.
Device according to claim 7, characterized in that said block (31) has, at right angles to the direction (A) in which the cloth advances, a semicircular slit (33) which ends with a 45^o chamfer (34) at which it intersects a cavity (35) that is open towards the edges to be joined and forms two ribs (36, 37) which are suitable to overturn the tape (12) and bend it in a U-like shape over the edges to be joined.
Method for positioning the edges of two cloths to be joined by means of a stitching line in a sewing machine, and device for performing said method, according to what can be deduced from the description and from the drawings.