EP0095261A1

EP0095261A1 - Method and apparatus for linearly uniting workpieces

Info

Publication number: EP0095261A1
Application number: EP83302476A
Authority: EP
Inventors: Edward Roy Williams; Peter Ashton
Original assignee: READSON Ltd
Current assignee: READSON Ltd
Priority date: 1982-05-05
Filing date: 1983-05-03
Publication date: 1983-11-30
Also published as: JPS5943107A

Abstract

A method of preparing a piece of flexible sheet material (2) for a sewing or like joining operation along a curved edge (2') comprises distorting the material (2") with said edge (2') free in such a way that the edge (2') is straightened in readiness for the joining operation. Apparatus for carrying out the method comprises a former (6) on which the material (2) can be located with the curved edge (2') overlapping one side of the former. Displacing means (32) displace the material (2") with respect to the former so as to straighten the curved edge (2').

Description

This invention relates to sewing or like joining operations such as heat or pressure welding whereby a piece of flexible sheet material is joined to itself and/or to another piece of such material in the curse of making a wide variety of different articles, e.g. bulk container bags and textile products including items of apparel.
It is known for the manufacture of such articles to be automated to some extent. For example, a garment hem may be formed by introducing a fabric edge into a sewing machine through a hemming folder. Likewise, when forming a seam between two fabric edges, appropriate folders may be used to bring the edges into correct overlapping relationship prior to sewing. However, such mechanical assistance has hitherto only been practicable if the edges in question are straight. The manipulation of curved edges, and particularly the seaming of curved and straight edges, has presented a serious obstacle to full automation of production of all but the most simple articles.
It is an object of the present invention to obviate or mitigate the aforesaid disadvantage.
According to a first aspect of the present invention thre is provided a method of preparing a piece of flexible sheet material for a sewing or like joining operation along a curved edge threof, comprising distorting the material with said edge free in such a way that the edge is straightened in readiness for the joining operation.
According to a second aspect of the present invention there is provided apparatus for preparing a piece offlexible sheet material for a sewing or like joining operation along a curved edge thereof, comprising a former on which the material can be located with the curved edge overlapping, and displacing means adapted to displace the material with respect to the former so as to straighten the curved edge.
The invention will now be further described by way of example only, with reference to the accompanying drawings, in which:-

Fig. 1 is a diagram showing two pieces of flexible sheet material which it is intended to sew together along their facing edges;
Fig. 2 shows the two pieces after sewing and parting;
Fig. 3 is a plan view of apparatus for automatically making the product of Fig. 2 from the pieces of material shown in Fig. 1;
Fig. 4 is a corresponding end elevation of the apparatus of Fig. 3 with the details identified by arrows shown to an enlarged scale;
Fig. 5 is a side view of the pleating station of the apparatus;
Fig. 6 is a further view of the pleating station with the details indicated by the arrows shown to an enlarged scale;
Fig. 7 is a perspective view of the sewing station of the apparatus with inset showing further details, and
Figs. 8 and 9 are alternative designs of former and pleating mechanism.

Referring now to Fig. 1, a first piece 1 of flexible sheet material, for example textile fabric has straight parallel edges and a second piece 2 of the same or different flexible sheet material is shaped with curved top and bottom edges of different length interconnected by convergent side edges. The object is to sew the straight edge of the piece 1 to the adjacent concavely curved edge of the other piece 2 and then part the piece 1 to provide a product as shown in Fig. 2 which can then be combined with other components to produce a finished article.
The apparatus for performing the sequence of operations necessary to achieve the object is illustrated in Figs. 3 to 7 and comprises a supply station 3 for holding a stack 4 of shaped fabric pieces 2, a pleating station 5 for pleating the shape of pieces 2 on respective formers 6, an oval track 7 for conveying the formers 6 to a sewing station 8, a feed path 9 for feeding the fabric piece 1 in continuous strip form to the sewing station 8 and parting means (not shown) for parting the fabric pieces 1 after the sewing operation.
The supply station 3 comprises a table 10 mounted on a fluid pressure operated piston and cylinder device 11. The table 10 supports a wire mesh basket 12 having the same shape in plan as the fabric pieces 2. The stack 4 of fabric pieces 2 is contained in the basket 12 directly below a pick-up head 13 which is of approximately the same shape and orientation as the fabric pieces in the basket 12. The pick-up head 13 has suction openings on its lower surface and is equipped with a flexible suction pipe 14. The head 13 is suspended from a carriage 13a which runs on rails 15 by means of wheels 16, 17. Fluid pressure operated piston cylinder devices 18, 19 are arranged to raise and lower the pick-up head 13.
The rails 15 for the pick-up head 13 extend into the region of the pleating station 5 beneath which is situated a former 6 as seen in Fig. 4. A total of 8 formers 6 run on the oval track 7 which has inner and outer track surfaces 20,21. Each former 6 is mounted on a respective carriage 22 which has a pair of castors 23, running on the outer track surface 21 and a pair of vertical rollers 24, 25 flanking a guide flange 26 on the inner track surface 20. Each former carriage 22 is connected by a linkage 27 to a conveyor chain 28 which runs around sprockets 29, 30 within the oval track 7. One of the sprockets 29,30 is connected to a drive motor (not shown).
Each former 6 has a central former rod 31 to each side of which are arranged three parallel former arms 32 which are spaced apart from each other and from the former rod 31 to provide an inner pair of spaces 33 between the former rod 31 and the adjacent former arm 32 to each side thereof, an outer pair of spaces 34 between each pair of outermost former arms 32, and an intermediate pair of spaces 35 between the second and third former arms 32 counting from each end of the former. Each former arm 32 is an elongate box section 37 with suction slots 36 in its upper surface which is covered by timber facing strips 38 having a polished rounded surface with apertures 39 registering with said slots 36. The box sections 37 are connected at their one end to a plenum chamber 40 and a capping plate 41 which serves to close these ends of the box sections 37. The former rod 31 and the former arms 32 are supported in cantilevered manner (as seen in Fig. 4) by means of a suction pipe 42 connected to the plenum chamber 40 and mounted on the carriage 22 by meanscf brackets 43, 44. The suction pipe 42 is equipped with an externally operable butterfly shut off valve 45. A suction manifold 46 interconnects the suction pipes 42 of all the formers 6 and has flexible sections to permit variable spacing between the formers during their travel around the oval track 7. A main suction pipe 47 is connected to the manifold 46 in the middle of the oval track 7.
At the pleating station 5 is arranged a pleating device having three pairs of pleating arms 48, 49, 50. Each pair of arms is interconnected by a central yoke 51, 52, 53 and a rear bridge member 54, 55, 56. The spacing between the pleating arms 48 corresponds to that between the inner pair of spaces 33 between the former rod 31 and the adjacent former arms 32. Similarly the spacings between the pleating arms 49, 50 corresponds to those between the outer pair of spaces 34 and the intermediate pair of spaces 35 defined by the former arms 32. Each pleating arm pair 48, 49, 50 is connected by its yoke 51, 52, 53 to a respective actuator 57, 58. 59 in the form of a fluid operated piston and cylinder device arranged to move the arm pairs vertically. Lateral displacement of the pleating arm pairs during such vertical movement is prevented by vertical guides 60. It will be noted from Fig. 4 that the pleating arms overlap the former 6 at both sides thereof.
The sewing station 8 is located opposite the pleating station 5 on the opposite side of the tracks 7. It comprises a sewing machine 61 mounted adjacent the track 7 and in line with the feed path 9. Immediately upstream of the machine 61 is a sewing guide 62 having a curved rear section 63 for folding the rear edge of the fabric strip 1 so as to enable the strip to pass under the sewing machine arm. The front of the guide 62 is shaped to double the opposite edge of the strip 1. A further guide 64 is arranged to lift the adjacent edge of the other fabric piece 2 under the front of the guide 62 so that by the time the two pieces of fabric reach the sewing machine they are held in the overlapping position indicated in the inset of Fig. 7 in readiness for seaming by a3ine of stitching 65. Further upstream of the sewing machine 61 on the feed path 9 and not illustrated in the drawings is an additional sewing machine for producing a hem in the rear edge of the fabric strip 1. Downstream of the sewing machine on the feed path 9 is a parting device (not shown) including a cutting element, which may be a heated wire, for parting the fabric strip 1.
In operation, the stack 4 of shaped fabric pieces 2 is lifted up to the pick-up head 13 which retains the uppermost fabric piece 2 on its lower surface by suction. The carriage 13a is then operated to carry the pick-up head 13 over the former 6 at the pleating station 5. The cylinders 18, 19 lower the pick-up head 13 onto the former 6 and suction is interrupted to deposit the fabric piece 2 onto the former 6 with its concave edge facing the outside of the track 7. The pick-up head 13 is then lifted and retracted to its starting position. The pleating device actuators 57, 58, 59 are now operated sequentially to lower the pleating arm pairs 48, 49, 50 through the spaces 33, 34, 35 of the former 6. As the pleating arms are lowered their free ends are arrested by the capping plate 41 and continued descent of the pleating arms causes them to assume an inclined position as shown in Fig. 5. As a result of this engagement of the pleating arms with the former 6 the fabric piece 2 which initially lay flat on the former 6 is pleated in the way best seen in Fig..7. It will be noted that each fold or pleat increases in depth in the direction away from the concave edge of the fabric piece 2. By carefully controBing the pleating operation, and in particular the depth and inclination of the pleats, it is possible to distort the free, concave edge of the fabric piece 2 into a rectilinear edge overlapping the former 6 in readiness for sewing to the straight edge 3 of the fabric strip 1. It will be appreciated that differently dimensioned fabric pieces may require different pleat dimensions and the actuators 57, 58, 59 therefore have adjustable strokes.
Suction is applied to the former 6 at the pleating station 5 by opening the butterfly valve 45 in its suction pipe 42. The valve 45 will remain open until the sewn fabric is removed downstream of the parting device beyond the sewing machine 61. The valve 45 is operated by suitable cams provided at appropriate podtions along the track 7. The pleating arms 48, 49, 50 are now raised and the conveyor chain 28 is indexed to bring the next former 6 into the pleating station 5, whereupon the sequence of operations described above is repeated.
The former 6 with the pleated fabric piece 2 held thereon by suction eventually reaches the sewing station 8. As the former 6 is advanced, the straightened concave edge of the fabric piece 2 is lifted into engagement with the sewing guide 62 by the guide 64. At the same time the fabric strip 1 is pulled through the sewing guide 62 so as to fold its edge 3 into a hem overlying the edge of the fabric piece 2 (Fig. 7). The sewing machine 61 then stitches along line 65 to form the seam shown in Fig. 2.
It will be appreciated from the above description that the loading and pleating operations take place while the conveyor chain is stationary whereas the fabric edge guiding and sewing operations are carried out during travel of the formers 6. Once the leading end of the strip 1 has been sewn to a shaped piece of fabric 2 the strip 1 will be automatically advance by a former 6 passing through the sewing station 8. On completion of the sewing operation the fabric strip 1 is parted and the seamed product as shown in Fig. 2 is removed.
Fig. 8 shows an alternative design of former which is made of sheet metal having a straight front edge and a series of ridges 101, 102, 103, 104 extending rearwardly therefrom and defining three troughs 105, 106, 107 of progressively increasing depth. In use, the curved edge of the fabric piece 2 overlaps the straight front edge of the former and the side portions of the piece 2 may be supported by a locating table (not shown) at opposite sidesof the former.
Three pleating arms 108, 109, 110 extend above and along the troughs of the former in the inoperative position. Each arm has a cantilever mounting at its rear end. The mounting comprises a fluid pressure operated cylinder 111, 112, 113 for vertically reciprocating an actuating rod to which the arm is pivoted. A bracket serves to keep the arm horizontal in the raised position of the actuating rod. When the rod is lowered it entrains the sheet material and draws it into the trough to form three pleats of increasing depth in the direction away from the front edge of the former. Preferably the central pleat is formed first followed by simultaneous formation of the two outside pleats.
The result of this pleating operation is to straighten the curved edge of the piece 2 into parallel overlapping relationship with the front edge of the former. The former may now be conveyed on a roller bed to a sewing machine in advance of which is a seam folder. At this point the straightened edge is brought into the desired overlapping relationship with the edge of the piece 1 and sewn.
It will be appreciated that the shape of the former of Fig. 8 is determined by the shape of the. piece of material which it has to pleat. In particular the relative dimensions of the front and side edges of the former and the number and inclination of the troughs are dictated by the degree of curvature of the edge 4. The greater this curvature the more material has to be pleated away in order to straighten the edge.
In contrast the first embodiment of former described with reference to Figs. 3 to 7 is a general-purpose former capable of handling a range of material pieces. Another general-purpose former is shown in Fig. 9. In this case the former has a frame with side panels 201, 202 interconnected at the front of the former by a bar 203, on which are pivoted a plurality of vertical plates 204 movable through respective linkages 205 by a bank of cylinders 206 or by mechanically adjustable levers on a shaft operated by one cylinder. Each plate 204 has an arcuate slot 209 for the passage of a locking bar 208. Friction pads (not shown) are provided between the plates 204 adjacent their bottom edges. When the locking bar 203 is released the operating mechanism is used to adjust.the plates 204 relative to each other so that their upper edges define the desired contour whereupon the locking bar 203 is locked again. Means (not shown), such as pleating bars, are also provided to bring the material into conformity with said contour thereby straightening the curved edge into parallel relationship with the pivot bar which it overlies.
The formers so far described are suitable for straightening concave or inward curves. Outward or convex curves can also be straightened by a similar technique but in this case the folds or pleats must be made in a direction generally parallel to the front edge of the former, i.e. transverse to the pleats in the embodiments described above.
The means described may be used to join a concave or convex curved edge of a convex, concave or straight edge. Where two curved edges are to be joined two formers, with their front edges in facing relationship. have to be advanced through the sewing station.
It will be appreciated that the curved edge may simply be folded and joined to itself in order to form a hem.
The sewing machine may be replaced by another form of joining machine depending on the material involved. For example, plastics material may be joined by a heat sealing operation.

Claims

1. A method of preparing a piece of flexible sheet material for a sewing or like joining operation along a curved edge thereof, comprising distorting the material with said edge free in such a way that the edge is straightened in readiness for the joining operation.

2. A method as claimed in claim 1, wherein the edge is inwardly curved and the material is distorted by making a plurality of parallel folds therein of increasing depth in the direction away from the edge.

3. A method as claimed in claim 1, wherein the edge is outwardly curved and the material is distorted by introducing one or more folds in a direction generally parallel to said edge.

4. Apparatus for preparing a piece of flexible sheet material for a sewing or like joining operation along a curved edge thereof, comprising a former on which the material can be located with the curved edge overlapping one side of the former and displacing means adapted to displace the material with respect to the former so as to straighen the curved edge.

5. Apparatus as claimed in claim 4, wherein the former comprises a plurality of spaced ridges extending in a direction away from said one side of the former and defining therebetween troughs of increasing depth in said direction.

6. Apparatus as claimed in claim 4, wherein the former comprises one or more ridges extending generally parallel to said one side of the former.

7. Apparatus as claimed in claim 4, wherein the former comprises a plurality of individually adjustable vertical plates whereof the top edges define ridges and troughs depending on the relative position of the plates.

8. Apparatus as claimed in claim 4, wherein the former comprises a plurality of arms with spaces therebetween through which the material can be drawn by the displacing means to form folds of increasing depth in said direction.

9. Apparatus as claimed in claim 8, wherein the former arms are hollow with upwardly directed suction openings for holding the material in position thereon, the arms being connected to a common suction chamber.

10. Apparatus as claimed in claim 8 or 9, wherein the displacing means comprises a plurality of pleating arms arranged to be lowered between the former arms and means on said former at said one side thereof for arresting the descent of the one ends of the pleating arms such that continued lowering causes thepleating arms to pivot into an inclined attitude which is adjustable by varying the extent to which the pleating arms are lowered.

11. A method of automatically performing a sewing or like joining operation along a curved edge of a piece of flexible sheet material, comprising positioning the material in a predetermined location, distorting the material by the method of any one of claims 1 to 3, and conveying the so distorted material to a joining (e.g. sewing) machine for manipulating and joining the straightened edge.

12. Apparatus for automatically performing a sewing or like joining operation along a curved edge of a piece of flexible sheet material, comprising means for positioning the material in a predetermined location with respect to preparing apparatus as claimed in any one of claims 4 to 10, and conveying means for conveying the preparing apparatus to a joining (e.g. sewing) machine for manipulating and joining the straightened edge.