Improved automatic machine for stitching of various articles, in particular leather articles

Abstract: The machine comprises a longitudinal guide (1) which forms, at both sides, two working surfaces (P1, P2) onto which articles (4,5) are arranged when the upper edges (4a,5a) of which are joined by means of stitches (40) by the combined action of a needle (7), provided with a thread (8), and a rotary hook (10) connected with a spool of stitching thread; this needle (7) is coaxial with a related shaft (11) that moves it with oscillatory and translatory longitudinal to-and-fro motion. The machine is provided with two vertical presser feet (25, 26), inner and outer, moved vertically in an independent manner in time relation with the motion of the needle, so that to make wrinkles (70) on an edge (4a) of the said edges, in alternate position with respect to the said stitches (40).

Description: The present invention relates to the technical sector concerning the stitching of leather articles and the like. There are known various types of automatic machines for stitching leathers, e.g. shoe upper and patch. Such machines include generally a base body provided in front part with a protruding head, in which the means supporting the needle and the relative movement organs are housed. The needle is operated vertically in direction of an underlying horizontal arm on which the leathers to be stitched are placed; the head contains also the members for the horizontal motion of the needle, in the direction parallel to the arm. The cited machines are provided also with feeding means designed to cause, at every stitch, the advancement of the two edges of the leathers to be stitched, superimposed one on the other. These machines have one working surface, and this fact reduces their working capability, because- of the need of superimposing the edges to be stitched. To resolve this problem there has been proposed a machine designed to stitch the edges arranged in any way with respect to each other, illustrated in the US Patent No. 4,848,252 in the name of the Applicant. Such a universal machine comprises one longitudinal guide that forms laterally inclined flat surfaces, converging at the top; such surfaces form respectively first and second work surfaces on which the leathers to be stitched are made to advance. Over the guide there is placed longitudinally a shaft designed to be operated in oscillating motion. A needle extending in an arc and provided with a thread, is mounted tangentially on the free end of an arm keyed on this shaft, and is made to oscillate alternatively between lowered and raised positions so as to pierce the edges of the leathers. A rotary hook device, connected to a spool of stitching thread, is adapted to work in cooperation with the needle to make the stitching. The machine cited above can perform the stitching of the edges no matter of the orientation and shape of them. However, for this machine it is not possible to perform certain kind of ornamental stitching that are currently requested in this productive field, such as the wrinkling of the stitching edge. The object of the present invention is to propose an automatic machine for sewing articles made of leather, this machine being able to stitch the edges no matter of how they are arranged or shaped and also to perform the wrinkling of at least one edge of the stitching. A further object of this invention is to propose an automatic machine for sewing leather articles that is made in accordance with a technical solution simple, safe in its working and reliable, and versatile in use. The above mentioned objects are achieved in accordance with the content of the claims. The machine made in accordance with the invention can automatically perform the wrinkling of one of two edges that are joined to each other by a stitching; this operation has traditionally been performed only manually. The wrinkles obtained are identical to each other, equispaced or even centered with respect to the stitches, if desired. The aesthetical effect is very pleasant, while the wrinkling operation is performed in a simple way within the normal stitching cycle and without changing any operative time or function of the same cycle. In particular, the machine maintains the advantages of a versatile use already described in the said US patent No. 4,848,252. The features of the invention are set out in the following with a specific reference to the accompanying drawings, in which: Fig. 1 is a side schematic view of the subject machine; Fig. 2 is the sectional view II-II of Fig. 1; Figs. 3,4,5 and 6 show schematic perspective views of subsequent phases of a stitching cycle. With reference to the above cited figures, reference numeral 1 indicates a longitudinal guide secured to the frame of the machine (not shown). The guide 1 includes a lower portion 2, delimited at both sides by sloping flat surfaces 2a,2b that converge at the top, and an upper portion 3, shaped like a vertical fin disposed on the middle longitudinal plane. The sloping surfaces 2a,2b form, along with the opposed facings of the fin 3, a first working surface P1 and a second working surface P2. The leathers 4,5 to be stitched are fed on the working surfaces, in step and according to a preset direction N, by means of members that are not shown (for instance, by means of the members shown in the US patent 4,848252). A first shaft 11 is located over the guide 1 and oriented horizontally. This shaft 11 is made to move axially, with to-and-fro strokes that can be varied, in synchrony with the advancement of the leather 4,5, as shown, for example, in the already cited US patent. Particularly, the movement in accordance with the direction N is performed in synchrony with the advancement of the leathers 4,5. An arm 6 is keyed onto the said shaft, and a block 6a for locking a needle 7 is tangentially secured to the free end of the arm. The needle extends in an arc (concentric to the shaft 11) and is provided with a thread 8. The needle 7 is moved with oscillatory motion from a raised position S (Fig.1), that is located aside of the first working surface P1, to a lowered position A (Figs. 4 and 5). This oscillatory motion takes place in synchrony with the advancement of the leathers (see again the US patent No. 4,848,252). The needle 7 is designed to pass through, while oscillating, a hole 9 made transversely in the guide 1, in the region where the fin 3 joins the lower portion 2. Aside of the second working surface P2 there is located a conventional rotary hook device 10 (indicated in general insofar it is not new), called "crochet", connected with a spool of stitching thread 10a. The crochet 10 is adapted for cooperating with the needle 7 so as to make the stitching. A wrinkling device, globally indicated as 12, is linked to the shaft 11 that moves the needle, in accordance with the invention. This device includes a case 13 open at the top and supported by a second longitudinal shaft 14 that is made to move axially (in a known manner) in synchrony with the longitudinal motion of the shaft 11. The seat 13a of the case 13 has a parallelepipedal shape so as to form a vertical guide for two slides 15,16 located side by side in the same seat. These slides have respective vertical slots 15a,16a of a certain height, into which there is freely inserted the portion 14a of the shaft 14 that crosses the seat 13a. The bottom of the case 13 has two vertical through holes for receiving and guiding respective stems 17,18. Two presser feet 25,26, inner and outer with respect to the first working surface P1 that is under them, are secured to the lover ends of the stems 17,18. The inner presser foot 25 has a flat shape and extends vertically; the lower head 25a of the inner presser foot can have various shapes, in accordance with the kind of leather 4 and with the kind of wrinkling that is requested (as it will be better explained in the following). The outer presser foot 26 is preferably shaped like a truncated cone having the diameter enlarging from the bottom to the top. The presser feet 25,26 operate side by side, and since the inner presser foot projects towards the stem 18, via a small arm 25b, the same stem 18 features a vertical groove 27 in its outer surface adapted to freely receive the outer vertical side 25c of the inner presser foot 25 (Fig. 2) A pin 17a,18a is secured to each stem 17,18 and crosses a respective slot 30 made in the longitudinal wall of the case 13. Springs 19 are hooked with an end to each pin while the remaining end is fixed to a bar 20 that is made integral with a protrusion 21a. The protrusion 21a projecs from a plate 21 that is secured to the wall of the case 13 from which the pins 17a,18a protrude (Fig. 1). The action of the springs 19 is enough to keep the upper end of the respective stems 17,18 constantly in abutment on the respective overhanging slides 15,16. Furthermore the springs keep the upper end of the slides abutting on respective cams 22,23 that are keyed on a third longitudinal shaft 24. This shaft 24 is made to rotate, in a known manner, so as to complete a turn for each full oscillation of the needle 7 (to-and-fro strokes). The shaft 24 is also made to move longitudinally and in synchrony with the axial motion of the shaft 14, according to a known way. From what above, it follows that the presser feet 25,26 are moved vertically, in time relation with each other but in an independent way, between end positions, i.e. raised positions K1,H1 and lowered positions K2,H2 respectively. A description of the machine way of working will follow. The leathers 4,5, as specified, are placed on the respective working surfaces P1,P2. Particularly, the stitching of the upper edges 4a,5a of these leathers is accomplished with these edges properly folded as shown in the drawings. The Fig. 3 shows the position of the members of the machine being the subject of this invention, at the beginning of a single stitching cycle, that is with the needle 7 at the raised position S while both the presser feet 25,26 idle at the raised idle position H1,K1. Reference numeral 40 indicates the stitches previously made while T indicates the path that the needle runs. In time relation with the lowering of the needle, and before that this latter pierces the edges 4a,5a, the outer presser foot 26 is moved to the related operative lowered position K2, while the inner presser foot 25 remains at the position H1 (see Fig.4); the lowering of the presser foot 26 is not hindered by the other presser foot due to the groove 27 made in the stem 18, thas is, the outer side 25c of the presser foot 25 freely runs in this groove. In this way the thread portion 8a located between the lastly made stitch 40 and the hole 60 made by the needle 7 while piercing the edges 4a,5a, rests against the outer presser foot 26 and therefore it remains aside of the region Z of the leather 5 that is delimited by the last stitch 40, downstream of the needle, and by the hole 60, upstream of the stitch 40. Before and during the edges piercing there are no vertical stresses on them, so that the mutual positioning of the same edges is not changed. The needle 7, after having pierced the edges 4a,5a reaches its end lowered position A (see Fig.4) in which it is located in the operative zone of the "crochet" 10; this latter, while oscillating, hooks the loop formed by the thread 8 carried by the needle 7. When the operating members described above are at the position shown in Fig.4, the leathers 4,5 are fed in synchrony, like shown, for example, in the already mentioned US patent No. 4,848,252. This advancement (in the direction N) is accomplished in synchrony with the longitudinal movement of the needle 7 and of the wrinkling device 12, in the same direction. At the end of this movement, while the outer presser foot 26 is still resting at the operative position K2, the inner presser foot is lowered until it reaches its operative position H2 (see Fig.5). This fact causes the head 25a of the inner presser foot 25 to wrinkle the region Z; this operation is not hindered by the portion 8a of the thread 8, because it is still kept aside by the outer presser foot 26, while the vertical downward stress provoked by the inner presser foot 25 and acting on the edge 4a, do not lead to any movement for the edges 5a,4a in the region of the hole 60, because of the fixing action of the needle 7. The beginning of the needle raising causes a loop to be formed in the thread 8, this loop being hooked by the "crochet" as already mentioned. While the needle is raising the thread 8 is kept under tension, and therefore also the portion 8a is under tension. At this moment, the outer presser foot 26 is raised, so that the portion 8a is released from it, and is temporarily held by the inner presser foot 25, this latter being still at the operative position H2 (Fig.6). Lastly, also the inner presser foot is raised so that the portion 8a is released from this latter. The portion 8a is under tension and then it pushes on the outer surface of the region Z. In this way the wrinkle 70 is kept due to the thread portion 8a that is strongly pressed on the region Z of the leather 4. The stitch 40 is such that a possible decrease of the tension in the portion 8a is not possible. Therefore the stitching 100 is obtained with an edge 4a provided with wrinkles 70 alternated with stitches 40. At this moment the needle 7 and the wrinkling device 12 are made to move longitudinally in the direction opposite to the direction N, so that the operating conditions shown in Fig.3 are restored. The shape of the wrinkles made along the edge 4a depends on the profile of the lower head 25a of the inner presser foot 25.

Claims: Improved automatic machine for sewing various articles, particularly articles made of leather, this machine being of the type comprising: a longitudinal guide (1), that forms two sloping flat surfaces (2a,2b) converging at the top, these surfaces forming first and second working surfaces (P1,P2) respectively; a first shaft (11) oriented longitudinally and rotatably supported over said guide (1), this first shaft being made to reciprocate axially and to move with to-and-fro movement in time relation with its reciprocating motion; an arm (6) keyed onto said first shaft (11); a needle (7) extending in an arc and provided with a thread (8), this needle being tangentially secured to the free end of said arm (6) and situated, as a consequence of the reciprocating motion of the first shaft, at a raised position (S), located aside of said first working surface (P1), and at a lowered position (A) in which it passes through a transverse hole (9) made in the said guide (1) while piercing the upper edges (4a,5a) of articles (4,5) placed on top of the said working surfaces (P1,P2); a rotary hook device (10), associated with a stitching thread spool (10a), this device being located aside of the second working surface (P2) and adapted for cooperating with the said needle to make the stitches (40); means moved longitudinally with a to-and-fro motion in time relation with with the oscillatory motion of said needle and designed to feed said articles (4,5) resting on top of the related working surfaces (P1,P2), in a preset direction (N) in synchrony with the motion of the said shaft (11) in the same direction; the said machine being characterised in that it comprises: a wrinkling device (12) moved longitudinally in synchrony with the axial translation of the said shaft (11); two presser feet (25,26), connected with said wrinkling device and moved independently from one each other, between two end positions, respectively raised idle position (H1,K1), and lowered operative position (H2,K2), these presser feet being inner and outer in respect of the upper edge of the underlying first working surface (P1); means connected to said wrinkling device for moving vertically said presser feet (25,26) in time relation with the oscillatory motion of the said needle, so that the outer presser foot (26) holds, when at the operative position (K2), the thread portion (8a) that is external with respect to the article (4) resting upon the first working surface (P1) and that is positioned between the lastly made stitch (40) of the stitching (100) and the hole (60) made by the neddle (7) while piercing the folded edges (4a,5a) of the articles (4,5), and so that the inner presser foot (25) makes, when at its operative position (H2), that is set after the operative position (K2) for the outer presser foot (26), a wrinkle (70) by means of the related lower head (25a), this wrinkle being arranged along the region (Z) of the upper edge (4a) of the said article (4) situated between the said last stitch (40) and the said hole (60), the raising of the outer presser foot (26), that occurs in time relation with the raising of the needle (7) and before the raising of the inner presser foot (25), provoking the said portion (8a) of the thread (8) to be released from the same outer presser foot (26), with this portion (8a) being subsequently temporarily held by the inner presser foot (25), from which it is lastly released because of the raising of this latter, so that this portion (8a) strongly presses the outer surface of the said region (Z) to fix the said wrinkle (70). Machine as in claim 1, characterised in that the said means for vertically moving the said presser feet (25,26) comprise, for each presser foot, a vertical stem (17,18) slidably guided by a case (13) born by a second longitudinal shaft (14) that is moved axially in synchrony with the axial motion of the said first shaft (11), with each stem (17,18) equipped, at their lower ends, with one of the said presser feet (25,26) and being subjected to the action of a respective cam (22,23) that acts axially on the related stem, while elastic means (19) are connected to said stems to contrast the action of said cams, these cams being keyed onto a third longitudinal shaft (24) that moves axially in synchrony with the axial motion of said first and second shafts (11,14). Machine as in claim 1, characterised in that said wrinkling device (12) includes a case (13) open at the top and while said means for vertically moving said presser feet (25,26) include, for each presser foot: a vertical stem (17,18) whose lower end is equipped with one of the said presser feet (25,26), this stem being guided slidibly by the bottom of said case (13), this latter being supported by a second longitudinal shaft (14) that is moved axially in synchrony with the axial motion of the said first shaft (11); a slide (15,16) inserted in the seat (13a) of said case, this slide having a vertical slot (15a,16a) for freely engaging the portion (14a) of the second shaft that crosses the said seat (13a), the said slide (15,16) being arranged between the upper end of the related stem (17,18) and a corresponding cam (22,23) that is keyed on a third longitudinal shaft (24) moved longitudinally in synchrony with the axial motion of the said first and second shafts (11,14); elastic means (19) acting on each stem (17,18) and contrasting the action of the said cams (22,23) on the related stem. Machine as in claim 2 or 3, characterised in that the inner presser foot (25) is shaped like a plate and extends vertically, this inner presser foot (25) being connected to the related stem (17) by a transverse little arm (25b), while the stem (16) connected to the outer presser foot (26) has a vertical groove (27) on its outer surface, this groove being adapted to receive freely the vertical outer side (25c) of the inner presser foot (25). Machine as in claim 2 or 3, characterised in that each stem (17,18) has a related pin (17a,18a) perpendicularly secured to it, this pin projecting out of said case (13) while passing through a slot (30) aligned with it and made in the wall of the case, with an end of said elastic means (19) hooked to the free end of said pin while the remaining end of said elastic means (19) is hooked to the same case. Machine as in claim 1, characterised in that the outer presser foot (26) is shaped like a truncated cone with diameter enlarging from the bottom to the top.

Inventors: CIUCANI MARIO, CIUCANI, MARIO
Applicants: CIUCANI MARIO, CIUCANI, MARIO
Application year: 1992
Main classification: D05B15
IPC codes: D05B15