DESCRIPTION OF THE PRIOR ART There are machines for stitching shoe uppers and soles, obtained by a machine for stitching edges of leather articles, adapted by providing them with suitable tools.

An example of this machine is the one disclosed in the US Patent No. 4.848.252 of the same Applicant.

This machine includes a longitudinal guide defining two flat inclined planes, mutually convergent upwards and defining respective working surfaces, on which the pieces of leather to be stitched move.

An arm is keyed onto a shaft situated over the guide and oriented parallel thereto. At its free end, the arm carries an arc like curved needle.

The shaft is operated to oscillate about its longitudinal axis, so as to move the needle between a raised and a lowered position in which it passes through the edges of the leather pieces.

The needle co-operates with a rotary hook, commonly-known as"crochet", to which a bobbin of stitching thread is joined.

This machine allows to stitch the edges of two articles of leather, e. g. shoe upper and toe cap.

However, the machine cannot stitch the sole to the upper, if it is of open type, i. e. forms a strip to be joined to the sole along an edge.

As pointed out before, this operative limitation has been overcome by providing the machine with suitable tools derived from the machine of the above mentioned US Patent.

The international publication No. W097/05316 also owned by the Applicant, discloses a method and a related machine for stitching a sole to a upper of open type.

Basically this machine is. formed by a head, supporting the needle and hook operating means, and a pivoting arm.

A longitudinal guide supporting the articles to stitch, is situated on the end of this pivoting arm.

The head is suitably inclined with respect to a vertical plane, so that a portion of the circular path covered by the needle in the region of the stitching area has a direction such to make easy for the needle to enter the upper and go out of the sole.

The pivoting arm is equipped with motorized means, pedal operated, which allow to place this arm in suitable positions, during the shoe stitching, so as not to hinder the shoe movements.

Moreover, the pivoting arm include a device for maintaining unchanged the space attitude fo the-guide independently from the positions assumed by the arm.

The Applicant has conceived another machine, disclosed by the European Patent Application No. EP 96941797.1, which overcomes the drawbacks of the previously described machine.

This last machine maintains the inclined head, according to the technique already used in the previous machine, whereas it eliminates the arm, that is replaced with a stationary guide fastened to the head and extending downward.

The lower end of the guide features a flange which supports the internal edge of the sole during the stitching.

The last machine is more compact, simpler and thus cheaper to produce with respect to the first one, therefore it has been more appreciated commercially, despite its operative limitation resulting from its structure.

In fact, shoe stitching cannot be finished by completing the close loop in the start point. This would prevent the flange, which during the stitching is situated inside the shoe, from coming out therefrom thus remaining trapped therein and making it impossible to withdraw the shoe from the guide.

To avoid this inconvenience, the stitching is interrupted before the last stitch, so that the shoe can be withdrawn, and subsequently, stitching is finished manually by the operator.

It is to be pointed out that the above described operative limitation must be considered under both technical and commercial point of views and in a context in which the only alternative was manual work or much more complex and laborious processes and apparatuses.

Therefore, this limitation has not been detrimental to commercial success.

SUMMARY OF THE INVENTION The object of the present invention is to propose a machine which allows stitching an open upper to a relative sole, in a complete and definitive way, without subsequent final operations and/or without interrupting the stitching before it is actually finished.

Another object of the present invention is to propose a machine, whose conformation, with small adaptations, allows to perform particular stitching, like the one in which the upper edge overlaps a corresponding sole part.

The above mentioned objects are obtained, in accordance with the content of the claims, by a machine for sewing a shoe upper to a related sole, the machine including: a longitudinal guide formed at a lower free end of a bracket arranged substantially vertical, said guide forming an upper stop for respective edges of a shoe upper and a related sole, which are advanced along the same guide; a curved needle having an arc-like shape, said needle being moved to oscillate on a plane crosswise to the guide between a start position, beside said guide and a maximum rotation position, in which the needle passes first through said edge of the upper and then through the edge of the sole, the needle being also reciprocated parallel to said guide according to strokes of predetermined pitch; a rotary hook, with a bobbin of stitching thread associated thereto, the rotary hook being situated beside the guide on the side opposite to the side where the needle enters said shoe upper, said rotary hook co- operating with the needle, so as to make the stitches;

a pivoting arm pivoted to a relative support close to and beside said guide; a wheel carried idle by a free end of said pivoting arm and situated below said guide, said wheel having such arrangement as to rotate about a horizontal axis crosswise to the guide, and coincident with the pivot axis of said arm, so that the wheel forms a lower stop and support for the internal surface of the sole edge.

BRIEF DESCRIPTION OF DRAWINGS The characteristics of the invention have been pointed out in the following, with a particular reference to the enclosed drawings, in which: -Figure 1 is a perspective view of the front part of the machine, where the stitching means are located; -Figure 2 is the same perspective view of Figure 1 and shows the position of a member of the machine in which the upper can be set in or removed; -Figures 3a, 3b are perspective views of a detail of the stitching area, seen at different angles; -Figure 4 is a front view of the stitching area with the machine prepared for a first stitching type; -Figure 5 is a perspective view of a shoe stitched by the present machine by the means illustrated in Figure 4; -Figure 6 is the same front view of Figure 4, of the machine prepared for a second stitching type;

Figure *7 is a perspective view of a part of a shoe stitched by the present machine by the means illustrated in Figure 6.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the above mentioned figures, numeral 1 indicates a head of a stitching machine, supporting operating means for driving stitching means thereof.

The head 1 is carried, in known way, by a base block which has such shape that the head is suitably inclined with respect to the vertical.

The head 1 supports, in known way, a longitudinal shaft 4 equipped with a radial arm 5.

A curved needle 6, that has an arc-like shape, is concentric with respect to the shaft 4. The curved needle 6 is fastened to the free end of the radial arm 5 (See also US-A-4,848,252).

The head 1 is so inclined that the part of the circular path covered by the needle 6 in the region of the stitching area, has a suitable direction so as to make easy for the needle to enter and go out at desired levels.

The needle 6 is cyclically moved from a start position, beside a longitudinal guide 7, and a maximum rotation active position, in which the needle pierces, during stitching, first the edge 9a of a upper 9, and then the corresponding edge 8a of a sole 8, engaged by the guide 7.

In particular, the upper 9 is of open type and is to be joined to the related sole 8, suitably shaped, in the region of its lower edge 9a.

The shaft 4 of the needle 6 is also reciprocated axially, according to strokes of prefixed amplitude, in suitable time relation with the needle 6 oscillation, as explained in the following.

The needle 6 co-operates with a rotary hook 10, commonly known as"crochet", to which a bobbin of stitching thread is joined.

The crochet 10 is situated beside the longitudinal guide 7, on the side opposite to the side where the needle 6 enters the shoe upper, and translates, in its turn, in synchrony with the shaft 4 of the needle 6.

As shown in the above mentioned document WO-A-9705316, a foot 20, indicated with broken line in Figures 4 and 6, is situated on the same side as the crochet 10.

The foot 20 moves crosswise to the guide 7, in suitable time relation with the needle 6 oscillation, so as to hold the sole 8 during the needle piercing.

The needle 6 passes through a slot 21 made in the foot 20.

A leather pressing element 52, situated on the side, where the needle enters the shoe upper, moves crosswise to the guide 7, in suitable time relation with the-needle 6 oscillation, so as to hold down the upper 9, after each stitch, when the needle 6 withdraws.

A wrinkling group 53 is situated on the side where the needle 7 enters the shoe upper, and is operated upon suitable command, so as to reciprocate in a direction

longitudinal to the guide 7 and crosswise thereto, in suitable time relation with the needle 6 oscillation.

The wrinkling group 53 carries a head 54, acting on the upper 9, so as to increase its advancement steps with respect to the sole 8, thus wrinkling the edge 9a of the upper, e. g. during the shoe toe stitching.

The longitudinal guide 7 is formed at a lower free end of a bracket 12, arranged substantially vertical and fastened to the machine head 1. The bracket 12. Also, the guide 7 has the task of guiding the edges 9a, 8a of the upper 9 and sole 8, during stitching.

According to a first embodiment, shown in detail in Figure 4, the guide 7 defines two working planes 7a, 7b, substantially vertical and facing opposite directions.

The guide has a recess, made in known way and therefore not shown, that is open toward the head 1, so as to allow the needle pass therethrough.

Respective prongs 14,15, independently adjustable in height, co-operate with the above mentioned working planes 7a, 7b.

This way, the guide 7 forms an upper stop for the edges 9a, 8a of the upper 9 and sole 8, which allows to adjust their mutual position for stitching and to direct correctly these edges 9a, 8a to the point where the needle 6 passes.

The just described guide 7 allows to obtain a shoe like the one illustrated in Figure 5.

According to a second embodiment, shown in detail in Figure 6, the guide 7 defines a rounded channel 70 with the concave part turned downwards.

The profile of the channel 70 allows to define a kind of a form, thanks to which it is possible to stitch the upper 9 to the sole 8 in such a way that the edge 9a of the upper 9 overlaps the edge 8a of the sole 8, partially wrapping it.

In this way, the needle 6 pierces twice the edge 9a of the upper 9, in the points where it enters and exits.

The esthetic effect of the just described stitching is seen in Figure 7, which shows a part of shoe obtained in accordance with this way.

This second way of stitching is particularly efficient for obtaining a shoe with high water tightness.

The longitudinal guide 7, in both described embodiments, co-operates with a wheel 17, situated therebelow and rotating about a horizontal axis crosswise to the guide 7.

The wheel 17 is carried idle on the top of an arm 13, that pivots freely with respect to a relative support 130 fastened to the head 1.

The pivot axis of the arm 13 coincides with rotation axis of the wheel 17, so that oscillation of the arm 13 does not change position of the wheel.

The support 130 features means 131 for maintaining the arm 13 in a raised working position L (see Figures 1,4 and 6).

In this situation, the wheel 17 is at a predetermined distance from the longitudinal guide 7 and acts as a stop and support for the internal surface of the edge 8a of the sole 8.

The means 131 are controlled to lower the arm 13 to a shoe set in and removal position K, in which the wheel 17 is far from the guide 7 (Figure 2).

In this position, it is possible to set in an upper 9 to be stitched as well as remove an upper already stitched to the relative sole, when the stitching is completed.

The means 131 are formed e. g. by a vertical shaft 132, to which the arm 13 is articulated, so as to move vertically and subjected to the action of elastic means, not shown, which maintain the above mentioned working position L.

Driving means 133, e. g. pneumatic powered, can be operated by a push button 134 to act on the shaft 132 so as to lower the arm 13 to the shoe set in and removal position K, in contrast to the above mentioned elastic means ; when the push button 134 is released, the driving means 133 bring the arm 13 back to the raised working position L.

The first operation of the stitching cycle, according to both ways, is mounting the upper 9, by lowering and raising the arm 13, as has already been said.

Therefore, the edges 9a, 8a of the upper 9 and the sole 8 are positioned along the guide 7 and then, moved manually to mate each other during the advancement. While doing so, they are stitched, with the sole 8 supported by the wheel 17, which rolls on the inner surface of its edge 8a.

The machine means drive the needle into oscillating motion, in known way, so that it passes first through the edge 9a of the upper and then through the edge 8a of the sole 8, until the needle reaches its maximum rotation position (Figures 4,6). I such position, the tip of the

curved needle is inside the crochet 10, where the stitching threads are reciprocally hitched.

At the same time, the needle 6 and the crochet 10 translate synchronously along the axis of the respective shafts, by a predetermined stitching pitch, thus making the upper 9 and the sole 8 advance.

Then, the needle 6 is extracted from the material to be stitched and brought back to its start position. The curved needle together with the crochet 10 move back by the same pitch as during the just completed stroke in the forward direction.

The foot 20 and the leather pressing element 52 work, in the previously explained way, during each stitch, performed according to the just described cycle.

During the stitching, the operator intervenes to activate the wrinkling group 53, which, by wrinkling the upper 9, compensates for its longer peripheral extension with respect to the sole 8 in the toe area, thus curving the sole.

The operator, during the stitching, suitably moves the arm 13, so that its position does not hinder the shoe upper 9 movements.

The stitching is completed along the whole length of the shoe and the last stitches are realized by passing over the initial stitches, so that the stitching path C becomes a close loop, and at the same time it is suitably fixed (Figures 5,7).

Afterwards, the arm 13 is lowered by pushing the button 134, and the so obtained shoe is extracted.

The work is completed by cutting the stitching threads, without any further operations.

Therefore, it appears that the objects mentioned in the introductory statements are fully obtained by a simple, reliable and extremely compact technical solution.

It is to, be specially pointed out that, due to the fact that complete and definitive stitching is obtained, the productivity increases and it is possible to avoid using specialized operators for manually completing the stitching process. This compensate for the additional cost, anyway low, resulting from the addition of the arm 13 and the means joined thereto.

It is understood that what above has been described as a mere, non limitative example, therefore possible constructive variants remain within the protective scope of the present technical solution, as described above and claimed in the following.