Method for applying glue to a surface of pieces of footwear and device that carries out this method

A method for applying glue to the upper surface of soles for footwear includes the steps of transferring a sole to a first station with the upper surface turned upward, picking up the outline of the sole, transferring the sole from the first station to a second station, keeping the sole orientation unvaried and applying a jet of glue directed to the upper surface of the sole along a path that can be adjusted and that follows the border of the sole. In a different embodiment, glue is also applied to the surface of the upper that is intended for attaching of the sole.

BACKGROUND OF THE INVENTION 
The present invention relates to manufacturing of footwear, in particular 
footwear in which glue, sometimes integrated with suitable seams, is used 
in order to fix the sole to the upper. 
DESCRIPTION OF THE PRIOR ART 
At present, the glue is applied to the upper manually (a procedure that is 
obsolete because of the high cost of manpower) or automatically, that does 
not cause particular problems, since the part of upper to which glue is to 
be applied, is quite regular, without indentations or recesses. 
As far as sole is concerned, in some manufacturing processes, glue is not 
applied to the surface to be attached to the upper. 
In other manufacturing processes, glue is manually applied to this surface, 
more precisely, along a closed loop path close to the border of the sole, 
so as to match the corresponding portion of the upper. 
This way of proceeding has been often used up till now, in spite of high 
expense due to manpower cost, and health risk for the operators due to 
previous treatment of the surface to be glued with a halogenated 
substance. 
Some manufacturers have tried to automatically apply glue to the sole, 
using a brush that touches the upper surface of the sole; the relative 
motion between the sole and the brush makes this latter follow a closed 
loop path. 
It is known that the upper surface of the sole features lightening recesses 
and/or stiffening ridges. 
It is also known that it is difficult to grip, clamp, and handle the sole 
because of its flexibility and particular shape; e.g. sucking cups cannot 
be used due to the sole irregularities, and possible mechanical gripping 
and clamping means would bend the sole changing its space position. 
Consequently, the means used to apply the glue (i.e. the brush) touches one 
or more of the lightening recesses, or strikes one or more of the 
stiffening ridges; in both cases drops of glue can remain in the recess or 
on the ridge, thus causing all the problems well known to the field 
experts. 
As it has already been mentioned, the surface of the sole on which the glue 
is to be applied, is previously treated with a halogenated substance. 
This is performed by a suitable apparatus, at the outlet of which the soles 
are stored or directed, by known means, to a room, where the glue is 
applied in the previously described way. 
This procedure needs long processing time and special operative rooms, and 
consequently the production cost of the footwear is negatively affected. 
SUMMARY OF THE INVENTION 
The object of the present invention is to propose a method for applying 
glue along a path with adjustable trajectory, that extends in a closed 
loop on the upper surface of the sole, close to the border thereof, the 
whole procedure being carried out without any contact between the sole and 
the means used for applying the glue. 
Another object of the invention is to propose a method according to which 
the above mentioned operation is performed correctly no matter of the 
orientation of the sole. 
Yet another object of the invention is to propose a method that fulfils all 
the aforementioned objects and furthermore, allows to apply the glue to 
the sole while this is freely resting on a suitable support. 
A further object of the invention is to propose an apparatus to carry out 
the proposed method. 
Yet a further object of the invention is to propose an apparatus that 
applies glue also to the upper for the intended sole. 
The above mentioned objects are obtained in accordance with the contents of 
the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to the above Figures, reference numeral 1 indicates a first 
conveyor including a series of wires 2 set side by side and trained around 
respective rollers, namely a fore roller 3 and a rear roller 4, so as to 
form a closed loop. 
The rollers 3, 4, one of which is driven in a known way by means which are 
not illustrated, feature suitable raceways, not shown in detail, aimed at 
receiving the wires. 
Between the raceways of the rear roller 4 there are made grooves 5 (FIGS. 
2a, 2b) aimed at receiving respective prongs 6 of a comb-like 
lift-conveyor 7 located in a lowered position. 
There is also a second conveyor 9, similar to the conveyor 1. The rear 
roller 8 of the second conveyor and the roller 4 of the first one, are 
coaxial. 
Also the second conveyor 9 includes wires 10 (which are transparent for the 
reasons explained hereinafter) and a fore roller 11; grooves made in the 
said rear roller 8 are indicated with 12. 
The lift-conveyor 7 is moved by known means, not illustrated, between 
adjacent stations 50, 100, 150, with the intermediate station 100 centred 
with respect to the rear roller 4 and the rear roller 8. 
In each extreme station 50, 150, the lift-conveyor is moved between a 
lowered position A.sub.1, in which the prongs 6 enter the grooves 5, 12 of 
the rollers 4, 8, and a raised position A.sub.2 that is kept while passing 
through and dwelling in the intermediate station 100. 
A device 13 for treating the soles with halogenated substance, is situated 
in the intermediate station 100, over the lift-conveyor 7. 
A transparent supporting plate 16a is situated at the top of a box-like 
element 16 that is positioned under the end of the upper run 9a of the 
conveyor 9. 
A light source, that is not shown, is placed inside the box-like element 
16, and the light beam coming from the plate 16a is not weakened or 
troubled by the overlying wires 10, which are made, as already mentioned, 
of material transparent to the light radiation emitted by the source. 
A video camera 17, connected with a monitor 18, is situated over the 
box-like element 16 and the upper run 9a of the conveyor 9. Signals issued 
by the camera 17 are sent to a processing unit that works according to a 
programme and that is interlocked with a control panel 19 (FIG. 1). 
The camera 17, the box-like element 16 and the portion of the upper run 9a 
situated therebetween, form a pick up station S.sub.1, or first station. 
Right after the second conveyor 9, there is a third conveyor 20, also 
including wires as the other ones, and the rear roller of the third 
conveyor is also the fore roller 11 of the conveyor 9. 
Over the upper run 20a of the conveyor 20, there is a spray gun 25 designed 
to eject a jet 26 of a suitable glue 27 (FIG. 5). 
The gun 25 is carried by a longitudinal bar 28, that is moved transversally 
by known means, not shown, controlled by the processing unit. 
The spray gun is moved along the bar by other known means, not shown, also 
controlled by the same processing unit, which furthermore activates and 
deactivates the spray gun. 
Consequently, the nozzle 25a of the gun 25 is brought in a horizontal plane 
along a linear path of any kind, in particular in a closed loop. 
The upper run 20a of the conveyor 20 and the room occupied by the gun 25, 
form a second station S.sub.2, or glue applying station. 
Between the above mentioned stations, there is a shutter 29, that moves 
vertically (FIG. 3) between a raised position, in which the soles pass 
freely from the first to the second station, and a lowered position, in 
which the first station is protected against possible glue spreading from 
the second station. 
The operation of the above described apparatus will be explained in detail 
in the following, with particular reference to the means that carry out 
the proposed method. 
The soles 30 are placed, in any orientation, on the first conveyor 1 with 
the upper surface 31, that is the surfaces that is intended for attaching 
to the sole, turned upward. 
In the extreme station 50, the lift-conveyor 7 is in the lowered position 
A.sub.1. When a sensor 32 detects a sole 30 that has reached a position 
thereunder, the conveyor 1 is stopped and the lift-conveyor 7 is activated 
(see FIGS. 2a, 2b). 
The lift-conveyor raises (in the direction F) from the lowered position 
A.sub.1 to the raised position A.sub.2, with the sole 30 carried by the 
prongs 6 (FIG. 2). 
At this moment, the lift-conveyor 7, while keeping in the raised position, 
translates (in the direction B) toward the other extreme station 150, 
passing through the station 100, where the upper surface 31 of the sole 30 
undergoes a treatment by a jet H of known halogenated substances (FIG. 
2b). 
In the extreme station 150, the lift-conveyor is lowered until the prongs 6 
are inserted in the grooves 12 of the roller 8, thus allowing the second 
conveyor 9 to bring the sole 30, already treated with halogenated 
substances, toward the first station S.sub.1. 
Obviously, the lift-conveyor 7 is raised, translated and lowered in order 
to take over a subsequent sole from the conveyor 1. 
The upper run 9a of the second conveyor 9 is long enough so as to allow the 
solvents, used during the treatment with the halogenated substances, to 
evaporate completely, before reaching the station S.sub.1. 
When the sole 30 is in the station S.sub.1, the conveyor 9 is stopped, thus 
permitting to perfectly pick up the outline 30a of the sole 30 by means of 
the camera 17. Also the orientation of the sole 30 with respect to the 
horizontal plane defined by the upper run 9a of the conveyor 9 is 
detected. The image picked up is shown on the monitor 18. 
The electric signals obtained by the image picked up are transmitted to the 
processing unit. 
The two conveyors 9, 20 are operated after the raising of the shutter 29, 
and the sole 30 is transferred to the second station S.sub.2, in which it 
remains for a predetermined time. 
It is to be pointed out that the sole remains in the same orientation, i.e. 
the orientation of the sole in the station S.sub.2 is the same as in the 
station S.sub.1. 
In the station S.sub.2 the gun 25 and the means provided to control it in 
two orthogonal directions, are activated, while the shutter 29 lowers in 
order to protect the station S.sub.1 from spreading of glue. 
The nozzle 25a of the gun is made to move, in a horizontal plane, along a 
closed loop path, that is calculated for each sole and that follows the 
outline 30a of that sole. 
It is to be pointed out, that the jet 26 is preferably centred with respect 
to the axis of the nozzle 25a, and this allows to direct precisely the jet 
close to the border of the sole so as to define a path P that usually is 
like a closed loop. 
The operation can be better understood with reference to FIG. 4, where a 
portion 40 of the glue strip 45 is illustrated, while the part not glued 
yet is indicated with 41 (sketched line). 
The distance X between the strip 45 and the outline 30a of the sole is 
calculated by a predetermined programme, but its length must prevent 
recesses 30b (FIG. 5) or stiffening ridges, made on the surface 31, from 
being touched by the jet 26; this distance can be kept constant or varied 
according to the sole shape. 
The path P is like a closed loop but it can also be open or criss-crossed. 
The above described method has many advantages, among which the following: 
the soles are simply placed, oriented in any way, on suitable supports, in 
particular the wires of conveyors 9, 20; 
glue is applied without any contact between the surface 31 of the sole and 
the glue ejecting means (i.e. gun 25); 
the strip 45 of glue applied to the surface 31 extends along an adjustable 
path that is kept at a distance X from the outline 30a of the sole, which 
distance can be programmed, calculated and varied. 
It is to be pointed out that the above mentioned advantages are obtained 
independently from the shape and structure of the sole, as well as from 
orientation of the sole in the first station S.sub.1. 
The characteristic of the proposed method requires a very simple device 200 
to be carried out, formed by the stations S.sub.1 and S.sub.2, first and 
second and by means connected with the latter. 
In fact, there are not means for clamping and/or gripping and/or 
positioning the sole, since it is supported on the wires 10 of the 
conveyor 9 (station S.sub.1) that cooperate, between the stations S.sub.1 
and S.sub.2, with the wires 22 of the conveyor 20, aimed at supporting the 
sole in the station S.sub.2. 
These conveyors 9, 20 cooperate, in the stations S.sub.1, S.sub.2, with the 
camera 17, with the associated box-like element 16, and with the gun 25 
controlled by means that drive it along two orthogonal directions, the 
whole being interlocked with the processing unit. 
With reference to the accompanying figures, the conveyor 9 is fed with the 
soles coming from a station where they have been treated with halogenated 
substances, (that is the central station 100). 
This should not be considered as a limitation, since the conveyor 9 can be 
supplied in any way, e.g. with soles coming from a special store. 
The particular combination of the device 200 with the stations 50, 100, 
150, and consequently with the means associated thereto, i.e. the 
lift-conveyor 7 and the conveyor 1, allows to provide a compact, versatile 
and functional apparatus that permits to treat the soles with halogenated 
substances and then, to apply glue thereto. 
A further advantage, besides the ones already mentioned, results from the 
fact that the conveyor 1 is fed with soles in any orientation, but with 
the upper surface turned upwards. 
The main advantage of the proposed method is that the glue is applied along 
a predetermined path P close to the outline 30a of the sole, without any 
contact between the gun and the surface 31. 
In a possible different embodiment of the present invention, instead of the 
conveyors 9, 20, there are trailer means equipped with means for gripping, 
and/or clamping and/or orientating the sole (such as clamps, suckers, 
box-like holders) aimed at positioning the sole in the stations S.sub.1, 
S.sub.2. 
If the soles are equal to one another, and held by trailing means that keep 
the same orientation for all the soles, the camera 17 is no longer 
necessary, since the outline and the orientation of the sole are 
previously stored considering a predetermined tolerance. 
The above description provides breaks in the movement of the sole form 
station S.sub.1 to station S.sub.2 ; it is obvious that such breaks may be 
avoided. 
According to a different embodiment of the invention, carried out by the 
device shown in FIGS. 6 and 7, glue is also applied to the bottom 61 of 
the upper 60, in the same time, using the same method. 
However, while the sole 30 is a flat piece that can be easily placed on a 
support plane, the upper 60 is made of soft material, and therefore it 
must be set on a last 63, so as to have it well taut and easy to be 
supported. 
When the upper is set on the last, the outline 60a of the bottom cannot be 
picked up by means of a light beam directed upwards and a camera, because 
the lateral curvature 64 of the last, necessary to fit the shape of the 
upper, would be detected in certain zones, instead of the bottom outline. 
In fact, only the fore part 60b and the rear part 60c of the upper bottom 
profile are correctly picked up. 
Furthermore, the upper 60 mounted on the last 63 is rather higher than the 
sole 30. 
All the problems have been solved by providing at least two cabinets 70, 71 
arranged side by side, in the first of which the outline 30a of the sole 
30 is picked up and then glue is applied thereto, while in the second 
cabinet 71 glue is applied to the upper bottom 61 on the basis of the 
outline picked up from the sole. 
Obviously, the sole and the upper must be coupled, that is the upper must 
be the one that is to be adhered to that sole. 
In the first cabinet 70 two soles are treated while in the second one two 
uppers 60 undergo operation. Each sole 30 of the first cabinet is coupled 
with a respective upper of the second cabinet. 
The soles are placed, either manually or automatically, in the first 
cabinet 70, on a supporting light-transparent surface 73. 
Each sole is positioned so as to be located under one of two video cameras 
117, which pick up the outlines of the respective soles as previously 
described. 
Two monitors 118 are connected to the cameras 117, respectively. 
Two light sources, not shown, are arranged inside two respective box-like 
elements 116 situated under the supporting surface 73, so as to emit a 
beam of light, upwardly directed, for each sole. 
When the outline 30a of the soles 30 is picked up, the spraying device 125 
of the soles cabinet 70 is activated so as to spray glue along the border 
of both the soles, in the way previously described. 
In the same time, the soles profile images are transferred to a processing 
unit 100, to be processed as described in the following. 
In the second cabinet 71, the two uppers 60 are arranged basically like the 
sole 30, but turned upside down. 
The uppers 60 are mounted on respective lasts 63 which are removably fixed 
to a transparent supporting surface 74, e.g. by means of press fit 
couplings 75. 
Consequently, the bottom profile of each upper results reversed, in the 
transverse dimension, with respect to the respective sole outline. Also in 
the second cabinet there are two video cameras 217, each one directed 
toward a respective upper. 
The supporting surface 74 of the second cabinet 71 is set out at a level 
lower that the level of the supporting surface 73 of the first cabinet 70 
for the soles. The difference in level can be adjusted to match the 
difference in height between the soles and the uppers mounted on the 
lasts. This differences in thus compensated. 
The cameras 217 of the second cabinet 71 pick up the outlines of the two 
uppers 60, with the help of two light sources 216 situated thereunder, and 
define the orientation assumed by each upper in the horizontal plane. 
Obviously, the uppers could be set out always in the same exact position, 
since the lasts are fixed to stationary points of the supporting plane, 
and accordingly the cameras could be omitted in the second cabinet, 
because the orientation of the uppers would be unvaried. 
In the example described herein, also two monitors 218 are provided and 
connected to the cameras 217 of the second cabinet 71, although they are 
not strictly necessary. 
The processing unit 100 reverses the electronic outline image of each sole 
30, with respect to the transverse dimension only, thus obtaining a 
specular image that corresponds to the actual outline of the respective 
upper 60. 
The same electronic outline image is rotated and translated in the 
horizontal plane to make the rear and fore parts of it to match the fore 
and rear parts 60a,60b of the respective upper image. 
All these operations are performed in a very short time by the electronic 
processing unit 100. 
Finally, the spray gun 225 of the second cabinet is activated and a jet of 
glue 127 is sprayed on the bottom 61 of each upper 60 along a path Q that 
follows the outline 60a. 
The path Q is not altered by a wrong image of the upper profile due to the 
shape of the last 63, because it is obtained from the reversed outline of 
the corresponding sole 30. 
In the example described herein, two soles 30 and two uppers 60 can be 
disposed in the cabinets 70,71, but it is obvious that smaller cabinets 
will allow to treat only one sole and one upper at a time, whereas bigger 
cabinets will allow to treat three or more soles and uppers at the same 
time. 
Moreover, in the described example, two cameras are used in each cabinet, 
but only one camera could be provided for each cabinet, when a suitable 
programme is installed in the electronic processing unit. 
Finally, there is only one spray gun in each cabinet, but in order to 
expedite the process, two or more spray guns could be mounted in each 
cabinet, each one driven by respective means, according to the number of 
sole and uppers being treated.