PERFECTED DEVICE FOR THE INFEED OF LEATHER FLAPS IN A SEWING MACHINE FOR THE SEWING OF THE SAME

Abstract: The device for the infeed of flaps of leather in a machine for sewing the same, consists of two feed plates moved in a cyclic phase, inside holes 11, 12 made in a plate 10, in order to effect the partial protrusion of the plates 13, 14 from the holes 11, 12 and their engagement with the corresponding surfaces of the flaps 1, 2, resting on the plate 10 and below stopping means 20, the infeed of the flaps 1, 2, the disengagement of the feed plates 13, 14 from the flaps 1, 2 and the return to the original position of the feed plates 13, 14. The first plate is integral with a supporting element 9 and the second plate 14 is linked to the element 9, with the possibility of sliding axially. The sewing of said flaps 1,2 along a curved trajectory is performed because of the progressive slowing down of the mobile plate 14 occurring during the infeed movement of the plates 13, 14 and as a consequence of a counteraction to the infeed of the flap 1, whereas the return to the original position of the plate 14, is the result of the reaction of elastic means 18, during the movement of the plates 13, 14 to their starting position.

Description: The difficulties and problems involved in sewing flaps of leather together along curved trajectories are well known. In particular the shoes commonly known as "moccasins" generally consist of an upper, open or closed at the bottom, a superior part, called vamp, which is designed to close the top of the upper, and other elements, well known to the technicians in the sector, which have the function of completing the shoe. The vamp is in fact fixed to the upper by sewing, carried out using well known machines. The aforementioned machines for the infeed of leather flaps to be sewn together, are fitted with devices which generally consist of a pair of feed plates, moving, according to the leather infeed direction, with a periodic to and fro motion, and, in an appropriate phase relationship, raised and lowered. The feed plates, integral with a single supporting body, hold the leather from below against the foot, or other known means, above, thus determining contemporary and intermittent infeed of the upper and the vamp. It is known, however, that the flat path of the edges of the upper and the vamp which must be united is curved. There is obviously a difference in the trajectories which must be followed by the edges of the upper and the vamp in the working area; in other words the trajectory of the seam to be made is also curved. This difference, in particular the trajectory of the upper is greater than that of the vamp trajectory, is magnified by the fact that the feed plates are very close to one another. The feed plates pulling the upper and the vamp along successive tracts of the same length, tend to cause a straight infeed of the two leather flaps. As a consequence the operator must intervene manually, slowing down the infeed of the vamp, to correct the sewing trajectory, with all the obvious problems that this involves. Devices have been created which, fitted to these machines, automatically produce a curved seam. The known devices, in fact, have two separate infeed plates which move autonomously, so that the infeed plate corresponding to the vamp has a shorter travel than that of the other feed plate. However the complicated construction which characterizes the aforementioned devices penalizes them reflecting negatively on production and maintenance costs. From the DE-C-714 616 a device is known for carrying out circular path sewing, such as for button-holes or the like, that includes two feed plates, one fixed to a supporting element, and the other slidably borne by the same element. The feed plate supporting element is alternately moved in a forward and in a backward direction so as to feed the material to be sewn. The device is mounted in the feed plate supporting element, and consists of a rocker which is pushed by the fixed plate when the supporting element advances, and in turn pushes on the sliding feed plate which is consequently made to go back. In this way the material being sewn is made to rotate while advancing. A spring acts onto the sliding feed plate so as to push this plate to its original position when the supporting element moves in the backward direction. The device particularly carries out circular sewing with a very small diameter, since when the feed plate supporting element advances a certain space, together with the feed plate fixed thereto, the sliding feed plate is made to go back the same space because it is pushed by the rocker. As a consequence the center of the circular path of the sewing is located between the two feed plates, and the radius of the circular sewing cannot be varied, because the forward displacement of the fixed plate is exactly equal to the backward displacement of the sliding plate. The purpose of the present invention is that of creating a device which, while it facilitates the sewing of curved seams, is also simple and economical to produce, and does not involve complicated and costly maintenance operations. The constructive and operative simplicity of the device which is the subject of the present invention is very clear; this simplicity is also accompanied by a functionality and effectiveness which permits highly satisfactory results to be obtained. Moreover the proposed device does not require the maintenance operations of the same frequency, length and complexity as those required for the known devices, which involve an autonomous movement of the feed plates. It is therefore more than obvious the advantages which follow, as regards the production costs, reliability and the subsequent maintenance costs. The above purposes and advantages are obtained through the device described in the Claims and disclosed in the following description. The characteristics of the invention not apparent from the above are in fact described below, with reference to the attached drawings, in which: Fig. 1a and 1b illustrate an upper and a vamp respectively before and after the sewing of the same; Fig. 2 illustrates in perspective and diagrammatically the device which is the subject of the present invention; Fig. 3a and 3b illustrate the device which is the subject of the present invention, seen from above, in two working positions; Fig. 4a and 4b provide side views of the device along the cross-sections I-I and II-II in fig. 3a and 3b; Fig. 5 shows a detail of the device seen from along the cross-section III-III fig. 4b. Fig. 1a illustrates an upper 1 and the relative vamp 2 which represent the two flaps of leather to be sewn together. Upper and vamp are used here only to provide an example, since the technical solution which is the subject of this invention can be used anywhere that there is the need to sew together flaps of leather along a curved trajectory. As can be seen in the figure, the flat path of the edges 3 and 4 of the upper 1 and the vamp 2, which must be sewn together, is curved. The respective trajectories followed by the feed plates, indicated with 5 on the upper and 6 on the vamp (fig. 1) are clearly different, and more precisely the first is longer than the second. Fig.2 illustrates a plate 10, within which the feed plates indicated with 13 and 14 must operate, moving inside the corresponding holes 11 and 12 in the same plate 10. The fixed feed plate 13 is integral with a supporting element 9 irremovably fixed, by known means not illustrated here, to driving means, which are also not shown here since they are well known to the technicians in this sector. The other feed plate 14, mobile with respect to element 9, is in fact linked to the latter by means of a coupling which permits relative axial sliding between the mobile feed plate 14 and the element 9. As can be seen in particular in fig.4a, 4b and 5, a cylinder 16 is fixed by means of a baffle 15 to the mobile feed plate 14, so that the cylinder is parallel with the feed plate 14 and below the same; in the example illustrated here feed plate, baffle and cylinder form a single body. The cylinder is, in turn, fitted inside a corresponding cylindrical housing 25, in the element 9, and parallel to the direction of horizontal movement of the feed plates. The closed bottom of the housing 25 has a through hole 19, through which passes the leg of a screw 17, which screws into the corresponding head of the cylinder 16. Between the bottom of the housing 25 and the internal head of the cylinder 16 there is a spring 18, which pushes the cylinder 16, and, hence, the feed plate 14 integral with it, until the head of the screw 17, external to the bottom of the housing, rests against the external border of the hole 19. Between the two feed plates 13 and 14, there are stop means 20 fixed to the plate 10, of the known type, designed to prevent the raising of the upper and the vamp when the feed plates rise. In the example illustrated in fig. 2 the parts 20 consist of a blade 21 irremovably fixed to the plate 10, by means of a screw 22, which is integral with a "T" element 23 under the wings of which the edges of the upper and the vamp to be sewn together are inserted. Once the edges of the upper 1 are inserted under the "T" element 23, and the upper is placed over the fixed infeed plate 13, and those of the vamp 2, with the latter placed over the mobile infeed plate 14, the machine is started up and the support element 9 is cyclically moved, as indicated by the arrows and closed ring in fig. 2, first in an upwards direction S, which brings the teeth of the infeed plate against the lower face of the upper and the vamp, then in a second forward direction A, pulling the same upper and vamp forwards, then again in a downwards direction B, releasing the upper and the vamp from the infeed plate, and finally in a backwards direction R returning the feed plates to the starting point. At the same time, and with a suitable phase relationship, the needle 24 moving cyclically downwards and upwards effects the seam between the abovementioned edges. When the seam takes on a curved trajectory, i.e. when the upper and vamp paths must be differentiated, it is sufficient for the operator to exercise a slight contrast to the vamp 2 infeed to achieve a shorter path for the latter. That is naturally when the counteraction exercised by the stopping means 20 is not sufficient on its own to curve the seam. As illustrated in fig.3a and 3b, and in the corresponding fig.4a and 4b, when the element 9 makes the upward movement in the S direction and starts the forward movement in the A direction, the mobile feed plate 14 is moved forward until the screw 17 comes to rest against the external border of the hole 19, and in the position corresponding to the fixed feed plate 13 (fig.3a and 4a). During the forward movement in the A direction of element 9, the feed plate 14 is slowed down by the contrast exercised by the operator on the vamp (or, if sufficient, by the stopping means 20) and, able to slide longitudinally with respect to the element 9, remains progressively further back as compared to the fixed feed plate 13, until the spring 18 is completely compressed by the cylinder 17 against the bottom of the housing 25 blocking any further movement of the cylinder 17 (fig.3b and 4b). During the downwards movement in the B direction and the backwards movement in the R direction, the elastic reaction of the spring 18 takes the mobile feed plate 14 back to the original position. It is obvious that by adjusting the screw 17 it is possible to determine the initial position of the mobile feed plate 14 with respect to the element 9, and thus vary the difference in the travel with respect to the fixed infeed plate 13. In particular it is possible to fix the mobile feed plate 14, by completely screwing down the screw 17, to obtain an identical functioning as that of a machine with both feed plates fixed for straight-line seams. The maximum reverse position of the mobile feed plate 14 can also be determined by some counter device other than that consisting of a completely compressed spring. Finally the mobile feed plate 14 may be linked to element 9 by means of a system other than that described here, provided that it allows the relative longitudinal movements, as described above.

Claims: 1. Perfected device for the infeed of flaps of leather in a machine for sewing the same, the said device consisting of, among other things, two feed plates (13, 14) moved in a cyclic phase, inside the corresponding holes (11, 12) in a plate (10) forming a working surface, respectively in the directions upwards (S), forward (A), downwards (B) and backwards (R), to effect in order the partial protrusion of said feed plates (13, 14) from said holes (11, 12) and their engagement with the corresponding surfaces of said flaps (1, 2) to be sewn arranged resting on said plate (10) and below the stopping means (20), the infeed of said flaps (1, 2), the disengagement of said feed plates (13, 14) from said flaps (1, 2) and the return to the original position of said feed plates (13, 14); said feed plates, respectively fixed (13) and mobile (14), being the first one integral with a supporting element (9) and the second one (14) linked to the same supporting element (9) with the possibility of sliding axially with respect to the latter during the movement of said feed plates (13, 14) in the forward direction (A), said mobile feed plate further being subject to elastic means (18), so as to effect the return to its original position as a result of the reaction of said elastic means (18), during the movement of said feed plates (13, 14) in the downward (B) and backward (R) directions; said device being characterized in that said mobile feed plate (14) is linked to said supporting element (9) by means of a cylinder (16), integral and parallel to it, inserted in a complementary housing (25) in the said supporting element (9), the bottom of which has a through hole (19) through which the leg of a screw (17) passes and screws into the corresponding head of said cylinder (16), so that the said device is able to effect the sewing of said flaps (1, 2) along a curved trajectory by means of the progressive slowing down of the mobile feed plate (14), with respect to said element (9) and fixed feed plate (13) occurring during the movement in said forward direction (A) of the same feed plates (13, 14) and as a consequence of a counteraction to the infeed of the corresponding flap (1), 2. Device as in claim 1 characterized in that said elastic means (18) lying between the bottom of said housing (25) and said head of said cylinder (16). 3. Device as in claim 1 characterized in that said supporting element (9) is itself moved in said directions upwards (S), forwards (A), downwards (B) and backwards (R). 4. Device according to claim 1 characterized in that said cylinder (16) is fixed to said mobile feed plate (14) by means of a baffle (15).

Inventors: CIUCANI, MARIO
Applicants: CIUCANI, MARIO
Application year: 1989
Main classification: D05B27
IPC codes: D05B27