Method for removably fastening insoles to corresponding lasts by a strip of adhesive tape, and device that carries out the method

The present invention relates to methods for fastening insoles to corresponding lasts and devices that carry out the methods.

The shoes are obtained by joining more parts, more precisely at least one upper, one insole and a corresponding bottom part (or sole).

A so-called "assembled" shoe is obtained by preparing an open upper, fastening an insole to the bottom surface, or sole, of a corresponding last, putting the upper on the last, fastening the edge of the upper to the insole and finally, fastening the bottom to the upper.

Suitable fastening means (e.g. nails or claws) are used for fastening the insole to the sole of a last.

Afterwards, a layer of glue is applied to the edge of the insole, the upper is put on the last, the edge of the upper is folded and is kept pressed, according to known techniques, against the insole, so as to join one to the other.

When the upper is joined to the insole, the so obtained upper-insole assembly is withdrawn from the last. During the withdrawing the fastening means must remain fastened to the sole of the last.

In some cases, a fastening element (nail or claw) can remain fastened to the insole after the shoe is completed, thus causing undesired disturbs to the shoe's user.

This disadvantage results in clients' complaints to the producer, which causes economic penalties to the firms producing the upper-insole assembly.

In other cases, the insole is fastened to the last by at least one strip of adhesive tape 15 (see Figure 6).

When the insole is correctly positioned with respect to the last sole, the strip of adhesive tape 15 adheres to the sides F of the fore portion a of the last 200 and to the lower fore portion "Ai" (or tip) of the insole 100, as shown in Figure 6 (insole and last for production of shoes for children).

In case a shoe for adults is needed, the insole 100 is fastened to the last 200 with two corresponding strips of adhesive tape 1a, 1b, respectively; a first strip of adhesive tape 1a, as already described, fastens the fore portion of the last to the insole, a second strip of the adhesive tape 1b is fastened to the sides F of the rear portion "Pi" of the last and to the lower rear portion Pt (or heel) of the insole 100, as shown in Figure 7.

The above technical solution avoids the problem of fastening means, which can remain attached to the insole during withdrawing of the upper-insole assembly.

In fact, after the insole has been fastened to the last, an upper is fastened, according to known techniques, to the insole, so as to obtain an upper-insole assembly.

Afterwards, the so obtained upper-insole assembly is withdrawn from the last and, during the withdrawal, the sharp corner Y of the insole 100 cuts the strip of adhesive tape in the region of the portion touching the above sharp corner.

Consequently, a part of the adhesive strip remains attached to the lower part of the insole, while the other parts, i.e. the ones attached to the sides F of the last, remain attached thereto.

A known device allows to apply the strip of adhesive tape to the lower part of an insole, so as to fasten it to the relative last.

The above device includes two stations, each of which includes pliers, first and second, respectively.

In the beginning, the first pliers of the first station hook the free end of the adhesive tape, translate to the second station bringing said adhesive tape along with them.

The second pliers of the second station, in step relation with the translation of the first pliers, follow an alternative path, so as to be positioned in the first station and catch the adhesive tape fastening it in the first station; in this way the length of the adhesive tape to be applied, is determined.

Contemporaneously, the operator fixes the last, with its sole turned upward, to a column, then locates the insole on the sole of the last and then places the last with the insole below the adhesive tape, so that the last touches the latter.

After the insole and the adhesive tape have been made touch each other, a main pad, situated over the adhesive tape, is positioned, with a pressure, on the upper part of the strip of adhesive tape, so as to make it adhere to the insole.

Afterwards, a blade cuts the adhesive tape in the region of the first station, so as to define the strip of adhesive tape to be fastened, and, in step relation, the pliers of the second station open thus releasing the adhesive tape.

Two additional pads, situated beside the main pad, act along the inclined directions, convergent downwards, so as to tuck in and fasten the edges of the strip of adhesive tape along the sides of the last.

Then, the operator withdraws the insole-last-strip assembly from the column.

One of the disadvantages of fastening the insole to the last by a strip of adhesive tape, if it is performed manually, derives from the fact that the fastening quality depends of the operator's ability and can be negatively influenced by the latter's tiredness.

Another disadvantage results from the time needed to perform the above fastening, more precisely, the time necessary to find the right position of the insole 100 with respect to the last 200, the time needed for cutting the strip of adhesive tape off the relative bobbin and the time the operator needs to apply the strip to the lower part of the insole, so as to fasten it to the last.

The cited disadvantages of fastening the insole to the last using the described device, derive from the fact that the constructive features of the latter complicate and slow down the positioning of the last under the adhesive tape and the control of the movement of the first and second pliers necessary to catch and pull the adhesive tape.

There are other devices which operate like the previous device, i.e. positioning the strip horizontally from right to the left, or vice-versa; this does not allow to apply the strip to the last, because the operator holds by hands the assembly by its extremities, i.e. heel and tip.

The object of the present invention is to propose a new and original method for removably fastening an insole to a corresponding last by a strip of adhesive tape.

Another object of the present invention is to propose a device for fastening insoles to relative lasts by a strip of adhesive tape, which avoids the above described disadvantages, and in particular facilitates the operator during the positioning of the sole on the last, and simplifies as well as speeds up the fastening of the insole to the last by the strip of adhesive tape.

A further object of the present invention is to propose a device, whose structure allows to cut the adhesive tape in a predetermined point, so as to define the right length of the adhesive strip and assure the best fastening of the insole to the last.

A still another object of the present invention is to propose a device, for using which the operator can keep hands on the last during the application of the strip thereto.

The above mentioned objects are obtained in accordance with claims.

The characteristic features of the present invention will be pointed out in the following description of a preferred, but not only embodiment, with reference to the enclosed tables of drawings, in which:

• Figure 1 is a lateral view of the device proposed by the invention for fastening insoles to relative lasts;
• Figures 1a, 1b are enlarged views of the particular K of Figure 1, showing two working positions of pliers hooking an adhesive tape;
• Figure 2 is the same view as Figure 1, with the bottom dead center of the adhesive catching pliers;
• Figure 3 is a section view taken along line III-III of Figure 2, with some parts removed in order to point out others,
• Figure 4 is an enlarged view of a portion of the device shown in Figure 1, pointing out the position of the adhesive tape, of the insole and of the last during a working step;
• Figure 4a is an enlarged view of the particular W of Figure 4;
• Figure 5 is a view of a working step following what is shown in Figure 4;
• Figures 6, 7 illustrate details mentioned in the introductory statements;
• Figure 8 is the same view of Figure 2, pointing out some constructive variants;
• Figures 9a, 9b show the particular Z of Figure 8 in two working conditions.

With reference to the above figures, the reference numeral 10 indicates the device for removable fastening of insoles to corresponding lasts by a strip of adhesive tape.

A metallic framework, indicated with T, includes a base B, an upright M fastened to the base B, two transversal arms 30a, 30b, situated one beside the other (I cannot see it in the figure) and fastened to the upper head of the upright M, and a vertical support S fastened to the head of the upright M and aimed at carrying a bobbin 11 of adhesive tape 1.

A cutting member 3 is placed between the two arms 30a, 30b and includes a blade 32 and a counter-blade 33, which are operated by two pneumatic jacks 320, 330, respectively.

When in rest position, the blade 32 and the counter-blade 33 define a through hole 9, whose function will be explained later.

A transmission roller V is fastened over the blade 32, in the region of the through hole 9.

The transmission roller V is aimed at guiding the adhesive tape 1, unwinding from the bobbin 11 through the hole 9, and at defining the "stop point" for the adhesive tape in the region of the transmission roller V.

The upright M carries, fastened thereto, a pad 50 and a working group 6, situated below the pad 50.

The pad 50 and the working group 6 define a working station 5.

The pad 50, having a transversal axis, is carried by a shaft 52, which slides freely through a sleeve 53 featuring an anti-rotation stake 54, which engages freely with a slot 55 made in the sleeve 53.

First and second sensor means 57a, 57b are fastened to the free end of the shaft 52.

The pad 50 can withdraw axially against the action of elastic means 56; a predetermined withdrawal of the pad 50 is detected by first sensor means 57a, while a predetermined withdrawal, bigger than the first one, of the pad 50 is detected by second sensor means 57b.

The working group 6 includes two vertical guides 61 (only one of which is shown with broken line), between which a vertical plate 62 slides.

The vertical plate 62 supports a transversal arm 63, which carries, cantilevered thereto, a substantially vertical extending body 60, seen in Figure 3.

The level of the body 60 is adjustable by an actuator 64, e.g. mechanical (Figures 1, 2), manual or controlled by motor means of known type.

The upper part of the body 60 carries a bar 65, perpendicular to the transversal arm 63, and includes an actuator 66 (e.g. pneumatic), which operates a vertical stem 67 moving freely through the bar 65.

A bracket 68, fastened to the vertical stem 67, is guided vertically, and simultaneously, prevented from rotating, by a pair of vertical guiding shafts 69, which freely pass through the through holes 690 made in the bar 65.

The bracket 68 features two through holes 680, through which wings 71 of an U-like frame 70 pass.

The base 72 of the U-like frame 70 is situated under the bracket 68.

The upper ends of the wings 71 carry, idling, a first lower roller R1, which is maintained in its extreme raised position, in absence of any external force, by first elastic means E1, winding about the portion of the wings 71 included between the bracket 68 and the first lower roller R1.

The extreme raised position of the first lower roller R1 is defined the base 72 of the frame striking against the bracket 68.

The first lower roller R1 faces a second upper roller R2, which is fastened to the above mentioned arms 30a, 30b and which moves vertically against the action of second elastic means E2.

The device 10 includes also pliers 4 (Figures 1, 2) situated before the pad 50 and the working group 6.

The pliers 4 include two jaws 4a, 4b, to which two actuators 42a, 42b are fastened.

The actuators 42a, 42b operate the pliers opening and closing.

The other end of the actuators 42a, 42b is fastened to a block 43 carried by a vertical shaft 45 operated by an actuator 44, e.g. pneumatic jack; the vertical shaft 45 passes freely through a through hole 76a made in a transversal bar 76 fastened to the body 60.

The vertical movement of the block 43 makes the pliers 4 reach two limit positions, one defined by the top dead center (TDC), in which the pliers catch, in the withdrawing station 2, the end 90 of the adhesive tape near, more precisely over the through hole 9, and the other defined by the bottom dead center (BDC, in which the lower part of the block 43 goes in abutment against the transversal bar 76 of the body 60.

The abutment defines the length of the adhesive tape 1.

In order to describe the operation of the device 10, a condition should be considered, in which the working group 6 is positioned to define a corresponding level of the body 60. During the adjustment, a distance "d" (Figure 2) between the first lower roller R1 and the second upper roller R2 is defined, so as to define a space corresponding to the size of the insole to be fastened to the last.

Afterwards, the actuator 44 moves vertically the pliers 4 until the latter reaches the top dead center (Figure 1a).

During the above mentioned movement, the actuators 42a, 42b of the pliers 4 keep open the jaws 4a, 4b of the pliers 4.

The pliers 4 pass through the hole 9 and catch the end 90 of the adhesive tape 1 by closing the jaws (Figure 1b).

After having caught the end of the adhesive tape 1, the pliers 4 move vertically downward, pulling the adhesive tape therewith, until the bottom dead center defined by the abutment between the lower part of the block 43 and transversal bar 76 (Figure 2).

In this condition, the operator puts the insole 100 on the last 200 and holding and stabilizing the last with his hands, he places the bottom surface of the insole in alignment with the adhesive tape 1.

Afterwards, the last-insole assembly is brought to touch the portion of the adhesive tape 1, in front of the pad 50, and a slight pressure allows the adhesive tape 1 to adhere to the insole, thus making the pad 50 withdraw.

Therefore, the pad 50 passes from a rest position, in which the elastic means 56 are in non-working condition and the stake 54 is situated near the stop of the slot 55, Figure 4, to a position of maximum withdrawal, in which the elastic means 56 are in working condition and the stake 54 is in the position of maximum withdrawal with respect to the slot 55, Figure 5.

In the position of maximum withdrawal, the tail portion of the shaft 52 of the pad 50 is detected first by the first sensor means 57a, which control the opening of the pliers 4, as well as operate the cutting means 32, 34, so as to cut the adhesive tape 1 and define the strip 15 of adhesive tape, as shown in Figure 4a.

Then, the tail portion of the shaft 52 is detected by the second sensor means 57b, which control the actuator 66 and subsequently, the vertical stem 67 moves upward the bracket 68.

The vertical movement of the bracket 68, as shown in Figure 5, compresses the elastic means E1, joined to the U-like frame 70, thus changing the extreme position of the first lower roller R1.

As a consequence of the above movement, the first lower roller R1 and the second upper roller R2, co-operating functionally, fold in and compress the ends of the adhesive strip 15 in the region of the sides F of the last 200.

After having folded the strip of adhesive strip 15 on the sides F of the last 200, the operator does not press any more the last-insole-adhesive strip assembly against the pad 50, therefore, the pad 50 returns to the rest position due to the action of the elastic means 56.

Afterwards, the operator withdraws the last-insole-adhesive strip assembly from the device 10 and a photocell (not shown in the enclosed drawings), situated near the pad 50, does not detect the presence of the insole and consequently operates again the pliers 4, which pass from the bottom dead center back to the top dead center, so as to hook the end 90 of the adhesive tape near the through hole 9.

The device for removable fastening insoles to corresponding lasts by a strip of adhesive tape has many particularly advantages.

The presence of a working group 6, pliers 4, a pad 50 and cutting means (blade and counter-blade), allows to automate, although only partially, the steps in which the insole is fastened to the last.

Actually, the working group 6, by adjusting the distance between the first lower roller R1 and the second upper roller R2, defines the size of the insole, which must be fastened to the corresponding last.

Therefore, a standard position is defined for a series of insoles to be fastened, and the operator is facilitated in positioning the insole-last assembly, stabilized and kept by himself while the device is working.

The presence of pliers 4, which catch the adhesive tape 1 and pull it vertically downward, so as to define the length of the strip of adhesive tape necessary to fasten the insole to the last, is advantageous because the use of only one pair of pliers simplifies the device working and allows to speed up and synchronize the subsequent operations.

During the manual positioning of the insole-last assembly between the upper and lower rollers, the operator pushes the pad.

The pad not only facilitates the fastening of the adhesive tape on the last surface but also controls, by suitable sensor means, the opening of the pliers, the operation of the cutting means (blade and counter-blade), so as to cut the adhesive tape 1, and the vertical movement of the bracket 68, which results in folding and fastening of the ends of the adhesive tape on the sides F of the last 200.

Consequently, the operator must maintain manually the coupling between the insole and the last, while the device 10 prepares the adhesive tape, cuts it, so as to define the strip 15 and folds it on the last.

Consequently, the proposed method includes:

• vertical downward positioning of the adhesive tape;
• centering of the insole with respect to the last and
• maintaining the positioning of the last-insole assembly by the operator, who holds the ends of the assembly, i.e. tip and heel;
• pushing the assembly only with a movement of the operator's arms, transversely with respect to the adhesive tape, until the strip of adhesive tape can be folded on the sides of the last.

According to a proposed embodiment (Figure 8), an elastic band 600, situated in front of the pad 50 and of the lower and upper rollers R1, R2, is fastened in 600A to the machine structure and controlled by the action of elastic means 600B.

The elastic band 600 is aimed at improving the adherence of the adhesive strip 15 to the insole 100 and at co-operating with the lower and upper rollers R1, R2 to fold the ends 15A of the adhesive strip 15 on the sides F of the last, which optimizes the adherence of the latter to the ends 15A of the adhesive strip 15.

Instead of the first sensor means 57a there are detecting means 500, e.g. micro-switch usually deactivated (position ZD of Figure 9a).

The micro-switch is pushed, and therefore activated, by the last 200-insole 100 assembly (position ZA of Figure 9b), when the assembly is about to touch the adhesive tape 1; this provokes the opening of the pliers 4 and activating of the cutting means 32, 34, so as to define the strip 15 of adhesive tape.

It is understood that what above, has been described as a pure, not limitative example, therefore, possible variants of the invention remain within the protective scope of the present technical solution, as described above and claimed hereinafter.