Technical Field

The present invention relates to the technical sector concerning sewing vamps to soles of shoes for realising footwear.

Background Art

The prior art comprises machines which realise a sewing of an open vamp onto a moulded sole made of a synthetic material, for example polyurethane. These machines are obtained by opportunely tooling a machine for sewing with a curved needle, in which the needle is borne at the free end of an arm, keyed radially on a longitudinally-arranged shaft in the head of the machine itself.

The shaft is designed to be activated with an alternating oscillating motion, such as to move the needle between two extreme positions, along a curved trajectory which is concentric of the radius of curvature of the needle.

The machine is provided with suitable guide and support means destined to define the correct vertical positioning of the sole during sewing.

In the outward oscillation the needle passes first through the lower edge of the vamp, and then the sole, and exits laterally of the latter, then entering a rotary-hook device, commonly known as a crotchet, which is designed to cooperate with the needle in order to form the stitch.

In suitable phase-relation with the outward oscillation of the needle, a holding member is activated such as to press the sole in the opposite direction to the needle advancement and thus oppose the thrust of the needle.

With the needle engaged in the vamp and the sole the longitudinal shaft is axially translated in synchrony with the crochet by an amount which is equal to predefined stitching step, thus determining the advancement of the material to be sewn.

The return oscillation of the needle is then commanded, which determines the disengagement of the needle from the material and enables an opposite translation to be performed, of a same extension, of the shaft-needle-crochet group, in order to bring the group back into the initial position.

In setting-up the above-described machine, the head is arranged inclined with respect to the vertical, such that the portion of the circular trajectory described by the needle at the sewing zone is appropriated orientated such as to facilitate the entry of the needle into the vamp and the exit thereof from the sole.

The shoe obtained, known in the footwear sector as IDEAL, exhibits two externally-visible stitch lines, one along the lower edge of the vamp and the other on the side of the sole.

Also known are shoes, entirely for females, known as BALLERINA (ballerina pumps), which are constituted by an open vamp of small dimensions, joined to a thin sole often without a heel and preferably made of leather.

In the best realisations of these shoes, the sole is prepared with a small step in the relative perimeter edge, and with an incision being made that starting from the upper surface of the sole penetrates obliquely into the thickness thereof, in the direction of the perimeter edge, and extends along a closed- ring trajectory which follows, at a more-or-less constant distance, the plan profile of the sole.

The vamp is turned through and the external side of the lower surface is glued at the position of the step.

The joint is then stabilised with a stitching that goes from the internal end of the incision up to the step, and involves the pre-glued lower edge of the vamp. Once the sewing operating has been concluded, the vamp is newly turned through and the stitching is invisible both externally and internally of the shoe.

The stitching described above is realised either manually or using machines constructed expressly for this operation; in the first case the drawbacks are related to the slowness of execution and the need for specialised operatives, while in the second case a considerable investment is required in a machine totally lacking in versatility, which can risk lying idle for long or short periods according to market demand.

The curved-needle machine, with the tooling described for IDEAL shoes is not suitable for realising the stitching in BALLERINA shoes.

Summary of the Invention

The aim of the present invention is therefore to provide a machine for sewing a vamp to a shoe sole which exploits the intrinsic characteristics of curved- needle machines and is equipped such as to enable sewing BALLERINA type shoes.

A further aim of the invention consists in providing a machine which performs the stitching starting from a semi-finished workpiece (vamp + sole) in exactly the same way as known systems.

A still further aim of the invention is to provide a machine which is able to sew a slim sole to a vamp, where the sole is either leather or synthetic, in order to obtain shoes that are different to BALLERINA models.

A further aim of the invention relates to the desire to provide a machine in which the specific tooling for sewing BALEERINA shoes can be rapidly demounted so that the machine can be temporarily adapted to other operations.

Brief description of the Drawings.

The characteristics of the invention will more fully emerge from the following description, of a preferred embodiment of the sewing machine of the invention, in accordance with what is set out in the claims and with the aid of the accompanying figures of the drawings, in which:

figure 1 is an exploded perspective view of a vamp and a sole of a shoe of the BALLERINA type;

figure 2 is a large-scale illustration of a partial section of the sole along plane H-Il of figure 1 ;

figure 3 is a partial front view of the machine in a non-operative mode;

figure 4 is a similar view to that of figure 3, with the machine in a first operating stage on a shoe; figure 5 is a large-scale view from the entry side of the needle, illustrating the stitching organs in the first operating stage of figure 4;

figure 6 is a frontal view, partially sectioned, of the stitching zone, with the organs in the first stage of figures 4 and 5;

figure 7 is a similar view to that of figure 5, with the organs in a second operating stage;

figure 8 is a front view, partially sectioned of the sewing zone, with the organs in the second stage illustrated in figure 7;

figure 9 is a similar view to that of figures 5 and 7, with the organs in a third operating stage;

figure 10 is a view from the exit side of the needle, relating to the stage illustrated in figure 9;

figure 11 is a partial section of the sole and the vamp after stitching;

figure 12 is a perspective view of a BALLERINA shoe when completed.

Description of Preferred Embodiments of the Invention.

With reference to the figures of the drawings, M denotes the sewing machine of the invention in its entirety.

The machine M, in known ways, comprises a head 1 in which the movement organs for activating the sewing organs are housed.

A longitudinal shaft (not illustrated in detail) enters among the movement organs, which shaft projects frontally from the head 1 and bears keyed thereto a radial arm 3, at a free end of which a needle 4 is fixed and develops in an arc of circumference, a centre of which coincides with the axis of the shaft 2 (see in particular figure 4).

The longitudinal shaft 2 is destined to be activated alternatingly oscillatingly, such as to move the needle 4 between two end positions, respectively a retracted position R and an advanced position A, along a curved trajectory concentric with the radius of curvature of the needle 4 and arranged on a vertical plane.

In the outward run, between the retracted position R and the advanced position A, the needle 4 is destined to encounter and pass beyond the material to be stitched, supported and positioned by special organs, as will be described in more detail herein below.

When the needle 4 is in the advanced position A, the point thereof is internal of a rotating-hook 5 device, known as a crotchet, with which it cooperates to realise the sewing stitches with two knotted threads.

When the operator releases the start pedal of the machine M, a known device intervenes to cause the automatic halting thereof, with the needle 4 in the retracted position R.

A holding member 6 is arranged in the space between the material to be sewn and the crotchet 5, which holding member 6 is mobile on a parallel plane to the oscillation plane of the needle 4, which pushes the material in an opposite direction to the advancement of the needle 4, such as to bear the thrust and facilitate penetration thereof.

The longitudinal shaft 2 is axially translatable with alternating motion in runs of predetermined entity, in synchrony with the crotchet 5 and in suitable phase relation with the oscillation of the needle 4 and with the movement of the holding member 6, such as to impress on the needle 4 a perpendicular motion with respect to the oscillation plane thereof, representing a predetermined stitching step.

In a preferred embodiment, a known device 40 for protecting the needle is associated to the needle 4; this needle-protecting device 40 is constituted by an oscillating lever 41 which is concentric to the radial arm 3 and subject to the action of a spring 42.

The oscillating lever 41 is shaped at a free end thereof such as to partially envelop the beam of the needle 4 and when the needle is in the retracted position thereof R the action of the spring 42 maintains the lever 41 at the zone of the point of the needle 4.

The lever 41 is destined to oppose any anomalous flexion solicitations which might occur on the needle 4 during the phase in which it passes through the material; for this purpose it follows the needle in the outward run thereof towards the advanced position A, up to when the impact with the material takes place, which halts the run of the lever 41 while the needle 4 penetrates the material.

The machine M of the invention is equipped with the following organs:

a spreader foot 10, provided at a lower end of a bearing element 11 having a substantially vertical development, solidly constrained to the head of the machine M such that the spreader foot 10 is located on a vertical plane that is parallel to the oscillation plane of the needle 4, in an intermediate position between the retracted position R and the advanced position A thereof; the spreader foot 10 exhibiting, in the side thereof facing the needle 4, a gully 10A which partially envelops the beam of the needle 4 during the outward run of the needle 4 towards the advanced position A;

an abutting foot 12 fixed inferiorly to the bearing element 11 , such as to be in an opposite position to the spreader foot 10;

a supporting stud 13, having a substantially vertical axis, arranged below the spreader foot 10 and the abutting foot 12, in a practically central position thereto;

a shaped arm 14, a top of which bears the support stud 13, the shaped arm

14 freely oscillating with respect to a relative base, according to an axis that coincides with the axis of the support stud 13.

The support stud 13 is associated to means for height-adjustment, for example a screw mechanism, not illustrated in detail.

In a preferred embodiment, the support stud 13 is born idle on the axis thereof and exhibits at least a portion 13A of the relative upper element which is obliquely cut, for reasons that will more fully emerge herein below.

The machine M, thus equipped, is destined to sew a vamp T to a sole F of a shoe 20 of the BALLERINA type, described in the preamble hereto (figure

12).

In some machines M destined for sewing particular models and/or formats of shoes 20, the axis of the support stud 13 (and the arm 14), differently from what is illustrated above, can be inclined towards the spreader foot 10 byan angle of about 15° with respect to the vertical. Similarly to the prior art, the sole F is relatively thin (about 6mm), preferably made of leather, and, in the illustrated example is without a heel.

The sole F is prepared by realising a step 21 in the relative perimeter edge 22 and creating a slit 23 which, starting from the upper surface 24 of the sole F, penetrates obliquely into the thickness thereof, in the direction of the perimeter edge 22, and extends along a closed-ring trajectory which follows the plan profile of the sole F at a practically-constant distance (figures 1 and 2).

With respect to the normal configuration illustrated in figure 1 , the vamp T is turned (figure 2) and the outside side 25A of the lower edge 25 thereof is glued to the step 21 (figures 6, 8).

The above-described operating stages realise a semi-finished workpiece S which can be subjected to the action of the machine M for stabilising, by stitching, the union between the vamp T and the sole F as is more specifically described herein below.

The semi-finished workpiece is inserted by suitably orientating the shaped arm 14 and is arranged such that the lower surface 26 of the sole F (i.e. the surface which when the shoe is finished is destined to contact the ground) rests on the support stud 13, which is orientated and height-regulated for the purpose, such as to define an abutment at a predetermined height.

The semi-finished workpiece S is then translated and rotated horizontally, aiding the manoeuvre with suitable displacements of the shaped arm 14, up to bringing the spreader foot 10 to partly insert in the slit 23 such as to distance the adjacent lips L1 , L2 in the zone of the slit 23 which is destined to constitute the start of the stitching (figures 4, 5 and 6) as well as bringing the abutting foot 12 to laterally abut the lower edge 25 of the vamp T and the adjacent perimeter edge 22 of the sole F.

The action of the spreader foot 10 is facilitated by specially inclining the semifinished workpiece S, thanks to the inclined cut of the portion 13A of the support column 13, which can be orientated in the most favourable position (figures 4, 6). At this point it is possible to start the machine, by means of the pedal, in order to initiate the stitching:

the needle 4 inserts between the opened lips L1 , L2 of the slit 23 (figure 7) to pass, in order through sole F and the lower edge 25 of the vamp T, exiting in a median position with respect to the height of the step 21 ; in this movement it is aided by the action of the holding member 6 (figure 8);

the needle 4 proceeds towards the first advanced position A which brings it internally of the crotchet 5 (figures 9, 10) and, in phase relation, the synchronous axial translation of the shaft-needle-crotchet group starts to advance the material to be stitched by one sewing step (arrow X in figure 9); at the end of the translation, the needle 4 is made to oscillate towards the retracted position R to disengage from the material, the operation being facilitated by the presence of the spreader foot 10, which functions as an abutment;

an opposite axial translation is impressed on the shaft-needle-crochet group, which returns it to the initial position, ready for a new sewing stitch.

The operator manually accompanies the semi-finished piece S for the whole ring-trajectory of the slit 23, displacing the shaped arm 14 into the position which is most appropriate each time.

Once the stitching C is completed, and the semifinished workpiece S extracted, the vamp T is newly turned to return it to its normal configuration, defining the shoe 20 (figure 11 , 12).

The stitching C is invisible from the outside of the shoe 20, as it is hidden by the folding-over of the vamp T, and also from the inside, as it is covered by the lips L1 , L2 of the slit 23, newly neared to one another (see figures 11 and 12 once more).

In a constructional variant of the machine, not illustrated, an actuator, for example a pneumatic actuator, is combined with the means for height- regulating the support stud 13, which can sharply lower the stud 13 by a predetermined amount in order to enable stitching in the zone of the heel should the sole F exhibit a small heel block. In the above examples, reference has been made to leather soles, but obviously the described machine is also able to perform sewing operations on a moulded sole made of a synthetic material, as long as it has similar shape and dimensions.

The special characteristics of the machine of the invention clearly emerge from the above description, which fully attains the set aims, firstly in order to easily obtain a special stitching, which is a distinguishing sign of a prestige shoe, without using either specialist operators or specific machinery.

With reference to BALLERINA shoes, special mention must be made of the fact that the machine is designed to perform the stitching starting from a semifinished workpiece (vamp + sole) prepared exactly in the same way to what is required in the prior art, totally respecting, therefore, the shoe-making traditions and the final quality of the product obtained.

Obviously the machine can also be used, with the described tooling, for footwear not precisely describable as BALLERINA shoes, as long as the footwear is similar in terms of construction type.

A further advantageous aspect of the machine is that the operating organs which constitute the tooling for BALLERINA type shoes 8or the like) can be quickly demounted and replaced with others, to temporarily convert the machine for other work operations.

This versatility gives a further advantage, which consists in being able to market, with perfectly affordable costs, a transformation kit which enables a client already in possession of a curved-needle machine to convert it for the work operations that have been mentioned herein.

It is understood however that all of the above is given by way of non-limiting example, and therefore any eventual modifications to details thereof, for example in the form of the operating organs, which might become necessary for technical and/or functional reasons, are considered to fall within the ambit of protection defined by the following claims.