DESCRIPTION OF THE PRIOR ART It is known that during certain working steps, a layer of glue is applied to the lower face of the upper and the upper face of the sole.

The glue is then activated at a predetermined temperatures in order to allow gluing of the lower portion of the upper to the upper portion of the sole.

It is also known that the upper, after being assembled from different parts, is fitted onto a last and the sole is positioned over the lower portion of the upper, so as to define the sole position with respect to the upper.

In order to glue the sole to the upper, the so obtained last-upper-sole group is positioned in a kind of press of known type.

The inside of the lower part of the press features means for supporting and positioning the last-upper-sole group, while the upper part of the press is equipped with an elastic diaphragm, so as to define an air-tight chamber inside the same upper part.

The diaphragm matches perfectly with the shape of the sole lower surface.

The air-tight chamber is connected with a source of vacuum.

When the two parts of the press are set to match with each other, the air-tight chamber results in a pressure condition.

Consequently, the elastic diaphragm presses uniformly the sole.

The above described system has some drawbacks.

In order to make the sole adhere perfectly to the lower portion of the upper, it is necessary to press the sole very strongly and to maintain such pressure until the sole is glued to the upper.

The pressure action eliminates the air present between the upper and the sole, after the sole has been positioned on the lower surface of the upper.

The disadvantage of this working technique derives from the fact that, in spite of a very strong pressure applied to the sole, the air present between the latter and the upper, is not eliminated completely and consequently, the gluing of the sole is not homogeneous on the whole surface thereof, which negatively affects the quality of the finished product: the repeated use of the shoe can cause the detachment of the sole from the upper.

Another disadvantage results from the fact that the gluing of the sole to the upper requires a lot of time, which leads to the productivity loss.

SUMMARY OF THE INVENTION The object of the present invention is to propose a method which overweighs the reported disadvantages, more precisely a method, which allows a uniform gluing of a sole to a shoe upper.

Another object of the present invention is to propose a method which allows a reduction of the time necessary to glue a shoe sole to a shoe upper.

A further object of the present invention is to propose a method, which does not require highly specialized personnel to be carried out.

A still further object of the present invention is to propose an apparatus which carries out the above method.

The above mentioned objects are obtained by the present invention, as understood from the claims, by a method for gluing a shoe sole to a shoe upper, which method provides for use of an apparatus formed by two parts, namely a lower part and an upper part, moving vertically with respect to each other and assuming two positions: a rest or open position, in which said upper part is far from said lower part, and a working position, in which the two parts are perfectly matching and hermetically closed by sealing means, with said lower part being equipped with means for supporting and positioning a last-upper assembly obtained by fitting an upper onto a corresponding last, and with said upper part being equipped with an elastic diaphragm, which defines an air- tight chamber inside said upper part, said method including previous re-activation of glue present on the lower surface of said upper and on the upper surface of the sole, and being characterized in that it includes: - positioning of the last-upper assembly in said lower part, supported by said means; - positioning of the sole in a seat obtained in the lower part of said elastic diaphragm, centered with respect to said group situated below and with the

surface of the sole provided with the glue turned toward the assembly; moving of said lower part and upper part to the working position, so as to close said lower and upper parts hermetically; activating means to create a vacuum at least inside a cavity, delimited by the lower part by the disposition of said lower part and upper part in the working position, in order to increase the porosity of the materials forming the sole and the upper, so as to facilitate a substantial elimination of air and other elements of the glue which make the latter work as rapidly as possible, thus defining a first gluing between said sole and said upper; activating means, which create a pressure at least equal to the atmospheric pressure inside said air- tight chamber, with said elastic diaphragm pushing against the lower surface of the sole, in order to perform a homogeneous pressure to the upper part of the lower surface of the sole, in order to glue the sole with the upper; elimination of the vacuum; moving said lower part and upper part to the rest position; removing of the last-upper assembly from the lower part.

The above mentioned method is carried out by an apparatus for gluing a shoe sole to a shoe upper formed by two parts, namely a lower part and an upper part, moving vertically with respect to each other and assuming two positions: a rest or open position, in which said upper

part is far from said lower part, and a working position, in which the two parts are perfectly matching and hermetically closed by sealing means, with said lower part being equipped with means for supporting and positioning a last-upper assembly, obtained by fitting an upper onto a corresponding last, after having re- activated the glue present on the lower end of said upper, and with said upper part being equipped with an elastic diaphragm for defining an air-tight chamber inside said upper part, said apparatus being characterized in that it includes a seat, made in the lower part of said elastic diaphragm and centered with respect to said assembly situated below, said seat being aimed at receiving and keeping a sole corresponding to the upper fitted onto said last, with the lower surface of said sole provided with the previously re-activated glue turned toward the assembly situated below; and in that it includes a source of vacuum for creating a vacuum inside at least a cavity, defined by the lower part due to the disposition of said lower part and upper part in the working position, in order to increase the porosity of the materials forming the sole and the upper, so as to facilitate a substantial elimination of air and other elements of the glue which make the latter work as rapidly as possible; means, activated in step relation with the deactivation of the connection of said vacuum source with at least said cavity delimited by said lower part, said means being aimed at connecting the air-tight chamber with an environment having pressure at least equal to the atmospheric pressure.

BRIEF DESCRIPTION OF THE DRAWINGS

The characteristic features of the present invention will be pointed out in the following with reference to the enclosed drawings, in which: Figure 1 is a lateral schematic, partially sectional view of an apparatus for carrying out the method proposed by the present invention, as seen during the method initial steps; - Figures 2 and 3 show the same apparatus of Figure 1 during subsequent method steps; Figure 4 shows the apparatus at the end of the method working steps.

BEST MODES OF CARRYING OUT THE INVENTION With reference to the enclosed drawings, the reference numeral 1 indicates an apparatus, which carries out the proposed method for gluing a sole F to a shoe upper T of a shoe fitted onto a respective last R.

The reference letter M stands for the last R-upper T assembly.

The apparatus 1 is formed by two parts, a lower part 2 and an upper part 3.

The lower part 2 and the upper part 3 move vertically, one with respect to the other, between two positions: a rest or open position I, shown in Figures 1 and 4, in which the upper part 3 is away from the lower part 2; and a working position O, in which the two parts match perfectly and are hermetically closed by sealing means 32, e. g. connected to the upper part 3.

The inside of the lower part 2 is equipped with means 20 for positioning the last-upper assembly M, e. g. a pin

20a, on which the last R is fitted and locked, and a support 20b, carrying the neck of the upper T, previously fitted onto the last R, as shown in Figure 1.

A source of vacuum Sv, whose function will be explained later on, is connected to the lower part 2.

The upper part 3 is equipped with an elastic diaphragm 30, which defines an air-tight chamber P inside the upper part 3.

The lower part of the elastic diaphragm 30 forms a seat 33, which receives, and keeps, the sole F, which is thus kept centered with respect to the last-upper assembly M, situated below.

When the apparatus is in the working position O, the diaphragm 30 defines a cavity D in the apparatus lower part 2.

Also the upper part 3 can be connected to the source of vacuum Sv in the way specified below.

The method for gluing of a shoe sole to a shoe upper includes a plurality of preliminary operations, among which fitting the upper T onto a corresponding last R and re-activating, as mentioned in the introductory note, the glue present on the lower face of the upper and on the upper surface of the bottom F.

According to the proposed method, the last-upper assembly M is positioned inside the lower part 2, with the lower surface of the upper T turned upwards, supported by the means 20a, 20b which define its exact collocation.

Afterwards, the sole F is positioned in the seat 33 of the elastic diaphragm 30, so that the surface of the sole F provided with the glue is turned downwards (Figure 1).

In a subsequent step, the lower part 2 and the upper part 3 are operated to move from the rest position I to the working position O : as seen in Figure 2, the sole F and the upper T are still separated and the elastic diaphragm 30 is in rest configuration.

Afterwards, the source of vacuum Sv is operated to create a vacuum (high vacuum) inside the cavity D as well as inside the chamber P; in this way, the porosity of the materials forming the sole and the upper, increases, so as to facilitate a substantial elimination of air (moreover, there can be other gases and/or particles of water vapor and e. g. the elements of the glue which makes the latter work as rapidly as possible).

After a predetermined time of vacuum duration, the upper air-tight chamber P is set in communication with the outer environment by a valve 60 controlled by a timer 70, while the lower cavity D is kept under vacuum (Figure 3).

Therefore, a pressure difference is created, which results in the downwards deformation of the diaphragm 30, and consequently in the contact of the sole F against the upper T.

The thrust exerted by the diaphragm 30 causes the perfect gluing of the sole F to the upper T.

According to a variant of the method, compressed air is introduced into the upper air-tight chamber P, so as to increase the pressure difference with respect to the lower cavity D and, consequently, to increase the thrust of the diaphragm 30 on the sole F during the gluing action.

When the gluing step is completed, the atmospheric pressure is reinstated in both the cavity and the air-

tight chamber, and the apparatus 1 is brought back to the rest position I, in which the two parts, lower 2 and upper 3, are far from each other (Figure 4).

Thus, it is possible to remove the last-upper assembly M with the relative glued sole F and the apparatus 1 is ready for a new working cycle.

The above described method for gluing a shoe sole F to a shoe upper T and the apparatus used for carrying it out are advantageous.

Having defined a cavity D, inside which a vacuum environment is created only after having created a vacuum and having kept it for a predetermined time, allows to eliminate the air present between the sole and the upper: this allows a rapid, perfect and lasting gluing.

Moreover, it is advantageous because the time necessary for gluing of the two parts is reduced; the pressure difference between the cavity and the chamber eliminates the air present between the sole and the upper and makes more efficient the thrust of the diaphragm performed on the sole F in order to glue it to the upper T.