**METHOD OF DEVELOPMENT OF A THREE-DIMENSIONAL MODEL OF A FORM OF FOOTWEAR**

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**A43D1/02**

**A43D3/02**CLAIMS 1 . Method of development of a three-dimensional model (1 ) of a form of footwear comprising the following steps: a) generating at least one three-dimensional model (1 ) of a form of footwear, to which model is associated at least a given length, b) modification of the given length, c) modification of the said three-dimensional model (1 ) on the basis of the modificed length, characterized in that the step c) includes a step c1 ) relating to the identification of at least one geometric figure that approximates at least in part the profile of said model (1 ), and a step c2) relating to the modification of the dimensions of said geometric figure on the basis of said modified length. 2. Method according to claim 1 , wherein to the said model (1 ) of a three-dimensional form of the footwear is associated another dimension corresponding to the instep of the form, a step c3) being provided relating to the modification of the instep, being the modification of the instep unambiguously deduced based on default values and on the basis of length change value. 3. Method according to claim 1 , wherein said geometric figure is constituted by a line (1 1 ) that approximates at least in part the profile of the said model (1 ) of the form of the footwear, being the development of said model (1 ) made at least along the direction of said line (1 1 ). 4. Method according to claim 1 , wherein the step a) provides a substep a1 ) relating to the identification of one or more sections (12) of the model, arranged on mutually parallel planes. 5. Method according to claim 4, wherein said line (1 1 ) is constituted by the union of the centers of gravity of said sections (12). 6. Method according to claim 4, wherein the said line (1 1 ) is constituted by the union of the midpoints of the segments identified by the intersection between each section (12) and the longitudinal vertical plane of the said model (1 ). 7. Method according to one or more of the preceeding claims, wherein said line (1 1 ) aproximates at least in part the walk of the lower part of the model (1 ) of the form, corresponding to the part placed in proximity of the shoe sole (13). 8. Method according to claim 1 , wherein said model (1 ) of the form is divided into at least two parts, of which a front part closer to the tip of the footwear, and a rear part, closest to the heel of the footwear, approximating said geometric figure the profile of the front part or of the rear part. 9. Method according to claim 1 , wherein said three-dimensional model (1 ) is divided into three parts (101 , 102, 103), of which a front part (101 ), a central part (102) and a rear part (103), being each part inserted inside of a geometric solid (1 1 1 , 1 12, 1 13), providing the step c) the change of at least one dimension of at least a geometric solid (1 1 1 , 1 12, 1 13) on the basis of the change of the length. 10. Method according to claim 1 , wherein the step a) provides for the scanning of at least one foot, said scanning providing the acquisition of one or more of the following parameters: - distance from the most forward point to the most rear point of the foot, - distance between the inner tarsus of the foot and the outer tarsus, - instep, - distance of the heel from the outside tarsus and from the inside tarsus, - instep. 1 1 . Method of developing of a three-dimensional model of a shape of footwear comprising a step a) of generation of at least one three- dimensional model of a form of footwear, characterized in that the step a) provides for the scanning of at least one foot, said scanning providing the acquisition of one or more of the following parameters: - distance from the most forward point to the most rear point of the foot, - distance between the inner tarsus of the foot and the outer tarsus, - instep, - distance of the heel from the outside tarsus and from the inside tarsus, - instep, being provided a step d) relating to the modification of one or more of said parameters. 12. Method according to claim 1 1 , wherein the modification of one of said parameters provides for the modification of the remaining parameters in accordance with prearranged and predetermined values. 13. Method according to claim 1 1 , wherein are provided one or more of the features of claims from 1 to 10. |

DESCRIPTION

The present invention relates to a method of developing a three- dimensional model of a shoe last, comprising the steps of:

a) generating at least one three-dimensional model of a shoe last, at least one given length being associated with such model,

b) changing said given length,

c) changing the three-dimensional model based on said changed length.

The invention particularly relates to the field of shoe-making based on a three-dimensional model.

The three-dimensional model is used for making a last upon which fabrics and materials are processed to manufacture the finished shoe.

A great variety of shoes are apparently available on the market, differing in terms of type, i.e. men's, women's, children's, sports shoes, etc. and in terms of size.

Consumer also have more and more stringent demands, requiring shoes with a better fit on their feet.

The provision of accurate lasts, to obtain shoes that can be adapted to the various types and consumers is a key issue.

Namely, market requirements can be only addressed by providing a development method that allows easy, quick and automatic manufacture of lasts from a master model, without incurring last deformations or requiring manual adjustments to maintain the last profile unchanged.

In industrial processes, for apparent time and costs requirements, lasts cannot be manually formed by a craftsman, and devices are provided that use a master last and develop such last by increasing or reducing its length according to the shoe that has to be made. Prior art methods use tables of increasing or decreasing development factors, to change, for instance, the length of the last in view of obtaining the desired shoe.

According to a first arrangement of prior art methods, lasts are developed using a tool path; a digitized tool path is developed, instead of the actual surface, with a technique that is similar to the use of a pantograph in hydraulic machinery.

An evolution of such method is the controlled tool path, i.e. a method that does not use an open-loop technique to develop the tool path, by approximation of the profile of the model to be developed to a right triangle that contains it, but operates iteratively until the preset length is achieved. This is still based on the tool path and not the actual surface.

As an alternative to these methods, more recent machine tools use a method that accounts for the actual surface of the last, with the tool path being calculated by the CAM residing in the machine during processing, based on tool geometry and on blade consumption.

In prior art methods, the three-dimensional model of the last generally has sections that move toward and away from each other in accordion-like fashion to achieve the target length.

Irrespective of the technique that is selected, prior art methods are dependent on the processing axis, i.e. the last turning axis.

Therefore, prior art methods are limited to a linear development along an axis, which may cause last deformations, especially in models having particularly complex shapes, such as heeled shapes, or in intensive developments requiring considerable length increases or decreases.

Therefore, there is a yet unfulfilled need in the art for a control system for a shoe last development model that can obviate the above discussed drawbacks.

The present invention fulfills the above purposes by providing a method as described above, in which the step of c) changing the length includes a step of c1 ) identifying at least one geometric figure that can at least partially approximate the profile of said model. A step is also provided of c2) changing the dimensions of the geometric figure based on the changed length.

It will be appreciated from the following description that any geometric figure may be selected, with the basic requirement that it will approximate the profile of the model.

Due to this requirement, the length of the model may be increased or decreased without causing distortions or deformations of the last.

The development of the three-dimensional model following the change of length causes a change of the geometric figure that can be lengthened or shortened, without involving a change of the model shape, but only of its dimensions.

In a preferred embodiment, a further dimension is associated with the three-dimensional model of a shoe last, i.e. the instep of the last.

Therefore, a step is provided of c3) changing the instep, the instep change being uniquely determined according to preset values and according to the length change value.

The instep is defined as the perimeter of the area identified by the intersection between the last and a vertical plane passing through the tarsi.

Here, model development is not only based on length but also on the instep.

The model development instep is preferably calculated on the bases of length change multiplied by default values.

Typically, length and instep increments in European countries are defined by numbers, 6.66 mm and 4.5 mm respectively.

A length-to-instep ratio may be calculated from these increments, i.e. a number that can be used to determine the instep from the length or vice versa, which is 6.66/4.5.

Advantageously this ratio can be shown in tables, which may change by sex, age or ethnic origin.

Therefore, it will be appreciated below that the method of the present invention can provide a location-based development, i.e. with developments differing not only according to the parts of the foot, but also according to the origin of the consumer.

Here, a fixed ratio may be provided, which can change the instep profile with the same development: therefore, for example, the instep may increase in height and decrease in width, while keeping the ratio constant, to obtain the desired instep.

Advantageously, the geometric figure consists of a line that at least partially approximates the profile of the shoe last model.

Here, the three-dimensional model is developed at least in the direction of such line.

It will be appreciated from the description of a few exemplary embodiments that the steps of the method of the present invention may be carried out through the help of a software platform, which can display the model that is being generated in combination with the line or the geometric figures that approximate its profile.

The development of the last will correspond to an increase or a decrease of the line length, based on an increase or a decrease of the last size respectively.

Advantageously, the three-dimensional model so obtained has one or more sections arranged on mutually parallel planes.

The sections are like the ones provided in prior art methods and models, except that, in this case, they may be used to locate the line that approximates the last profile.

Different types of lines are provided, requiring different method steps, as described below.

According to a first embodiment, the line is formed by joining of the centers of gravity of the sections.

Thus, in addition to avoiding model deformations, the development of the lasts maintains the parallelism between the planes of the different sections.

According to an improvement, the line is formed by joining of the midponts of the segments identified by the intersection between each section and the longitudinal vertical plane of the model. Based on this feature, the development better conforms with the contour of the last, especially in the rear portion of the model.

According to a further embodiment, the line at least partially approximate the contour of the lower portion of the last model, which corresponds to the portion located proximate to the shoe sole.

In this configuration, the development of the last is enhanced at the most critical portion, which represents the actual footprint of the foot, and disregards the last crest, which is mainly used for shoe construction and processing purposes.

Once again, line in the two variants as described above, the sections are spaced apart during development by conforming with the curvature of the profile, and the position of the last on the turning axis will have no effect thereupon.

According to one embodiment of the method of the present invention, the last model may be divided into at least two parts, i.e. a front part that is closer to the toe end, and a rear part, closer o the heel end of the shoe.

Furthermore, the geometric figure may approximate the profile of the front part or the rear part.

With this feature, different development factors may be used for different regions of the last.

Furthermore, different development methods may be used in combination: for example, a prior art development may be used for the rear part and a last profile-conforming development may be used for the front part or vice versa.

In addition to a line, another geometric figure may be used for development, which accounts on more dimensions of the last, in addition to length, while the last is being developed.

For this reason, according to a preferred variant of the method of the present invention, the three-dimensional model is divided into three parts, i.e. a front part, a central part and a rear part, such that each part fits within a solid geometric figure. The step of c) changing the three-dimensional model based on the changed length, includes changing at least one dimension of the solid geometric figure.

It will be understood that this configuration allows development to be independent of the digitization axis: the last is developed irrespective of the position it had while the model was being generated.

Furthermore, development is also independent of the turning axis: the last is developed irrespective of the position it had during processing.

Like in the previously described cases, this development method limits deformations, even in lasts with high heels or other elements that pose development challenges.

A further advantageous aspect is that, developments may not only differ in the three axial directions, but also in different parts of the last.

For example, this configuration allows enhanced development of the rear and central parts, that contain the foot, as compared with the toe end of the last, which mainly identifies the style.

Also, as mentioned above, the use of solids allows the instep to be more developed in width than in height, for improved adaptation of the instep to the population target.

It shall be noted in the explanation of the exemplary embodiments that the development method of the present invention can maintain the last profile more efficiently, even with uncommon development factors, such profile being unchanged irrespective of how the last is positioned or processed.

According to a further embodiment, in the development method of the present invention the three-dimensional model of a shoe last is obtained by scanning at least one foot.

Particularly, during scanning, certain parameters may be acquired, including:

- the distance from the foremost point to the rearmost point of the foot,

- the distance between the inner surface and the outer surface of the tarsus of the foot, - the instep,

- the distance of the heel from the outer surface and the inner surface of the tarsus,

- the instep girth.

It will be appreciated that the acquisition of these parameters is useful for the development to provide lasts that more accurately conform with the foot and can easily fit various consumers.

For this reason the present invention also relates to a further method of development of a three-dimensional model of a shoe last comprising a step of generating at least one three-dimensional model of a shoe last.

Particularly, this step includes scanning at least one foot, which scanning includes acquiring one or more of the following parameters:

- the distance from the foremost point to the rearmost point of the foot,

- the distance between the inner surface and the outer surface of the tarsus of the foot,

- the instep,

- the distance of the heel from the outer surface and the inner surface of the tarsus,

- the instep girth.

A step o also provided of d) changing one or more of such parameters.

Therefore, the above described method will provide a last model, one dimension whereof is isolated and changed, by increments or decrements, until the desired last is achieved.

Advantageously, standard ratios of one quantity to another may be provided , even in tables that provide variations based on the countries of origin, such that a change of one parameter will automatically change the other parameters.

Therefore, according to the method of the present invention the change of one of said parameters may cause the change of the remaining parameters according to preset and predetermined values. It shall be further noted that the above described development method may include all the features that have been set forth hereinbefore.

These and other features and advantages of the present invention will appear more clearly from the following description of a few embodiments, illustrated in the annexed drawings, in which:

Figs. 1 a to 1 d show different embodiments of the development method of the present invention;

Fig. 2 shows the comparison of the development method of the present invention and the classical prior art methods, in extreme development parameter conditions, to highlight that the model is less prone to deformation in the method of the present invention.

Figs. 3A to 3h show different views of the parameters acquired by the method of the present invention to generate a three-dimensional model of a shoe last.

It shall be noted that the figures annexed to the present application depict certain embodiments of the development method of the present invention, to provide an improved understanding of its advantages and characteristics.

Therefore, these embodiments shall be intended by way of illustration only and without limitation of the inventive concept of the present invention, which consists in providing a method of developing a three-dimensional model of a shoe last for making shoes that can be adapted in an increasingly efficient and customized manner to the feet of different consumers to afford automatic development of lasts without generating deformations.

Furthermore, as mentioned above, the steps of the method of the present invention may be preferably carried out using special software that can use a virtual last model to make changes to the dimensions of such last.

Thus, the figures annexed to the present patent applications relate to vired of such software that highlight the steps of the development method of the present invention. Particularly referring to Figures 1 a to 1 e, the method of developing a three-dimensional model of a shoe last comprises the steps of:

a) generating at least one three-dimensional model of a shoe last, at least one given length being associated with such model,

b) changing said given length,

c) changing the three-dimensional model 1 based on the changed length.

Particularly, the step of changing the three-dimensional model 1 includes a step of c1 ) identifying at least one geometric figure that can at least partially approximate the profile of the model 1 , and a step of c2) changing the dimensions of the geometric figure based on the changed length.

Particularly referring to Figures 1 a to 1 c, the geometric figure consists of a line 1 1 that at least partially approximates the profile of the shoe last model 1.

The three-dimensional model 1 is developed at least in the direction of such line 1 1.

Based on what is shown in Figures 1 a to 1 c, once the change has been set on the length, the model 1 is not developed in the direction of axis A or in the direction indicated by axis B, but is developed in the direction of line 1 1 , of which length is changed, whereby the model 1 is developed without deformations caused by shortening or lengthening.

Obviously, based on the length increase or decrease, corresponding values are provided for shortening o lengthening the line 1 1 .

According to a preferred embodiment, a further dimension is associated with the three-dimensional model 1 , corresponding to the instep of the last.

In this case, the method of the present invention includes a step of c3) changing the instep.

Particularly the instep change is uniquely determined according to preset values and according to the length change value. Particularly, the instep change is obtained by multiplying the length change by said preset values that can be provided in a table and divided according to the nationality, age or sex of users.

Particularly referring to the above figures, the model 1 as shown in Figures 1 a to 1 c is obtained by defining one or more sections 12 arranged on parallel planes, which are moved toward/away from each other for development of the model 1 .

As is known in the art, these sections may not be evenly arranged, but will be preferably at a shorter distance in the points of the model 1 that require a higher resolution.

The line 1 1 may be formed according to various criteria, as shown in Figures 1 a to 1 c.

According to the variant embodiment as shown in Figure 1 a, the line 1 1 is formed by joining of the centers of gravity of the sections 12.

As shown in Figure 1 a, the development axis is not a linear axis, and an axis may be supposed that extends through the center of gravity of the surface sections 12.

According to the embodiment as shown in Figure 1 b, the line 1 1 is formed by joining of the midponts of the segments identified by the intersection between each section 12 and the longitudinal vertical plane of the model 1 .

Assuming a longitudinal vertical plane that cuts the model 1 into halves, such plane is perpendicular to the sections 12 and the intersection of such plane with the various sections 12 identifies a segment for each section.

The midpoins of each segment are calculated and the line that joins all the points is the development line 1 1 .

Figure 1 c shows a further variant of the lone 1 1 , which in this case is obtained by at least partially approximating the contour of the lower portion of the last model 1 , which corresponds to the portion located proximate to the shoe sole 13.

In this case the development line 1 1 may be provided above or below the part that is level with the sole 13, provided that it approximates its contour to obtain a development that complies with the lower portion of the last, omitting the part that is closer to the crest plane 14.

Particularly referring to figures 1 a to 1 c, the line 1 1 may also only partially approximate the profile of the model 1 .

For this reason, according to a possible embodiment, the model 1 may be divided into two parts, a front part and a rear part and the line 1 1 may be arranged to follow the profile of the model 1 only for the front part or the rear part.

Figures 1 d and 1 e show a further embodiment of the development method of the present invention, in which the geometric figure that approximates the profile of the model 1 is not a line, but one or more solid geometric figures.

This will provide a three-dimensional development, in which the various solid figures may be developed in different directions.

Particularly referring to such figures, it can be noted that the three- dimensional model 1 is divided into three parts, i.e. a front part 101 , a central part 102 and a rear part 103.

Each part fits into a solid geometric figure, such that the length change will cause the change of at least one dimension of the solid geometric figure.

In the particular case of Figure 1 d, the solid geometric figures consist of parallelepipeds 1 1 1 , 1 12 and 1 13, which respectively encircle the front part 101 , the central part 102 and the rear part 103.

The three parallelepipeds, joined together, somewhat form a "deformation cage" whose development can provide the development of the model 1 .

The model 1 was inscribed in the deformation cage, which contains all its points and has such points associated therewith; by changing the geometry of the cage, the geometry of the model 1 is changed accordingly.

The deformation cage may be obtained using a new reference system, which is joined to the model 1 and is thus independent of the position in which the last is processed or digitized, i.e. the position at the time in which the model 1 is generated.

The reference system may be based, for example, on the crest plane 14; the crest plane 14 is firs identified, then a plane parallel to the crest plane 14 is identified and placed at half the height of the model 1 and a plane perpendicular to these two planes is finally identified.

This will provide the axes of the new reference system, which will locate the front sole, the central sole and the rear sole of the foot, to divide the model 1 into the three parts 101 , 102 and 103.

Particularly referring to the variant as shown in Figure 1 d, Figure 2 shows the comparison of the development method of the present invention and the classical prior art methods, in extreme development parameter conditions, to highlight that the model is less prone to deformation in the method of the present invention.

Particularly, starting from the master model, referenced 20 in

Figure 2, two different developments have been made; numerals 30 and

31 designate the lasts obtained with prior art development methods, and

40 and 41 designate the lasts obtained with the development method of the present invention.

It will be appreciated that the models 40 and 41 keep the shape of the master model 20 unchanged, especially the model 41 as compared with the model 31 .

As decribed above, length is just one of the dimensions upon which the development method of the present invention may be based.

Thus, according to the particular generation of the model 1 , all the dimensions available to the user may be changed to develop the model 1 in a variety of manners.

Various parameters may be used to obtain the generation of the model 1 , one part of which is shown in Figures 3a to 3h.

Particularly, the model 1 may be generated by scanning a foot and acquiring the following parameters:

- the instep, as shown in Figure 3a, which is indicated as the perimeter of the section of the plane that passes through the tarsi, - the distance from the foremost point to the rearmost point of the foot, as shown in Figures 3b and 3c, i.e. the projected length, the footprint of the foot on the ground,

- the distance of the heel from the outer surface and the inner surface of the tarsus, as shown in Figure 3d,

- the distance between the outer surface and the inner surface of the tarsus, indicated as the width of the sole of the foot, as shown in Figure 3e,

- the axial width of the sole of the foot, as shown in Figure 3f, - the axial length, as shown in Figure 3g,

- the instep girth, as shown in Figure 3h and referenced X6.

All these parameters may be available once the virtual model 1 has been generated and may be thus changed during development of the last.

Finally, tables may be advantageously provided that can relate all these parameters together, such that the change of one of these will automatically lead to the change of the remaining parameters.

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