GB1585996A - Moulds for producing rubber thermoplastics and like articles in particular shoe soles and shoe soles therefrom obtained - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO MOULDS FOR PRODUCING RUBBER, THERMOPLASTICS AND LIKE ARTICLES, IN PARTICULAR SHOE SOLES AND SHOE SOLES THEREFROM OBTAINED (71) We, ILGA INDUSTRIA LOM BARDA GOMMA AFFINI S.r.l., a company organised and existing under the laws of Italy, of 9 Via Madonna degli Angeli, Vigevano, Pavia, Italy, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following . statement: The present invention relates to a mould for producing moulded articles of flexible material such as rubber and thermoplastics materials. The moulded articles more particularly but not exclusively are shoe soles.

The present invention seeks to provide a mould which facilitates more easy removal of articles made of a resilient material, e.g.

rubber, thermoplastics or the like, from the mould.

It is well known for shoe soles, especially those for use in sports such as athletics, sporting, gymnastics, often have a non-skid pattern in their ground contacting surface which surface may also have sharp projections.

When moulding such soles particular difficulties are then encountered during the removal of moulded soles from the moulding means. The difficulties are because non-skid patterns usually show undercuts or are otherwise so shaped as to increase the difficulty in removal of the sole from the mould.

According to the present invention there is provided a mould for producing a moulded article of flexible material having a surface carrying a series of longitudinally extending rollers of part-circular section which rollers extend from and are integral with a common base sheet. the mould comprising a first bottom die having a plurality of roller forming cavities each defined by lands in the die contoured to obtain an undercut-free cross section for the major part of each roller, said first die co-operating with a second upper die one of which has bridges extending across longitudinally opposite ends of each cavity, said bridges having a width and a thickness sufficient to form an intervening space between each roller end and its base sheet, said intervening space permitting the rollers to be flexible in the region of the bridges and facilitating release of the roller ends from the respective cavities during the article removal from the mould. Preferably, each mould cavity of the first bottom die comprises a main portion having a semicylindrical bottom surface from which vertical side walls extend upwardly to define the lands, this main portion being wholly open upwardly, and a shorter portion at each end of the main portion having a circular cross-section partly defined in the mould by the bridges.

In the preferred embodiment, the flexible material is a material such as rubber or a thermoplastics material. In an embodiment the article is a shoe sole with a ground contacting surface having a non-skid pattern.

The present invention also provides an article moulded from a mould as defined in the two preceding paragraphs wherein the article is moulded by hot pressing a material such as rubber or thermoplastics material, wherein the article has a base sheet carrying a non-skid pattern comprising a plurality of parallel and adjacent part cylindrical rollers, which at both longitudinal ends of the rollers are separated from said base sheet.

An embodiment of the invention will now be described by way of example only, with reference to the accompanying drawings, in which: Figure 1 shows an underneath plan view of a part of a mould of a first embodiment; Figure 2 is a cross-section of said mould, along the line X-X; Figure 3 is a perspective view of a part of a mould according to the invention; Figure 4 is an enlarged cross-section of said mould, taken on a plane perpendicular to that of Figure 2; Figure 5 shows, as a not restrictive example, a section of a mould according to the invention, similar to that of Figure 2, with a moulding cavity partly filled with the material to be moulded; Figure 6 shows, likewise as not restrictive example, a cross-section similar to that of Figure 4 with some moulding cavities partly filled with the material to be moulded, and Figure 7 is a perspective view of a part of an article as moulded by the mould according to the invention.

Referring now to Figures 1 and 2 of the drawings, it will be seen that a mould A, which is particularly suitable for hot pressing on steam presses, comprises a bottdm die B and a top die C which is secured to a piston rod 10.

Such mould may be used for the production of sundry articles having a surface with a non-skid pattern formed by a series of parallel cylindrical rollers. In particular the mould is designed for making soles for sports shoes having a non-skid pattern.

The body of metal bottom die B is formed with a plurality of parallel and adjacent cavities D, each extending along the longitudinal direction L of the same die B. The cavities D are contoured for moulding a surface with parallel and adjacent cylindrical rollers F of a rubber or plastics article G (Figure 7).

In this embodiment, the bottom die B of mould A is in the form of a parallelepipedon block which has a length L and which is defined by sides 12 and 14 parallel to the longitudinal direction L and 16 and 18 orthogonal to the direction L. Each cavity D in which a cylindrical roller F of article G is moulded, may be regarded as subdivided into three portions, namely a main or greater portion 20. and two end or smaller portions 22 and 24.

The cross-section of each portion 20 in the moulding cavity D is shown in Figures 4 and 6. Portion 20 seen in section has a semicylindrical bottom 26 from which vertical sides 28 and 30 extend. such sides acting as reliefs.

Accordingly, each cavity D is wholly open upwardly in its portion 20.

The cross-section of end portions 22 and 24, respectively, of each moulding cavity D is circular as shown in longitudinal section in Figure 2 and as shown in transverse section in Figures 3 and 4. The closed circular section is defined by the presence of cross bridges 32 and 34 extending across the opposite ends of cavities D. Each of the bridges 32, 34 has a width and a thickness determined by the requirement to conveniently define both ends of each cylindrical roller F as formed in the mould A.

Actually, each moulding cavity D, when viewed from above, appears as wholly open up to the convergence with the bridges 32 and 34 whilst, when viewed orthogonally to that direction i.e., along direction L each cavity D is seen to be a right cylindrical tube.

As previously stated, the structure of each moulding cavity D, and thus the structure of bottom die B, is such as to make easy and practically immediate the removal of rubber or plastics article such as moulded in the mould B and provided with a non-skid pattern formed by a plurality of rollers F.

When the article G is to be hot-pressed, the raw material, in its solid state, is placed in the bottom die B, which is then covered by the top die C, whereupon the whole mould is heated. Heating continues to obtain melting of the material to be moulded such that this material achieves a fluid state. This fluid material then will fill all mould cavities i.e. the plurality of moulding cavities D as well as the upper cavity H, which is defined by the spacing left between the lower side 11 of top die C, and the upper side 13 of bottom die B.

After a suitable cooling time, the solidified material forms the article G, having a non-skid pattern defined by a plurality of adjacent parallel part cylindrical rollers which extend from and are integral with a flat sheet M (Figure 7).

Each roller F (Figure 6) is shaped such that the main portion thereof, corresponding to the portion 20 of the related cavity D, has a cross-section which is semicircular at its bottom and is then defined by two rectilinear portions 15, 17, corresponding to the vertical sides 28, 30. Both end portions 19 21 of each roller F. corresponding to related end portions 22, 24 of each cavity D have a circular cross-section. These are formed with the assistance of the die bridges 32,34 which also define an intervening space 23 between the corresponding edge of said sheet M and the roller ends 22.24.

As previously stated, the unique structure of bottom die B and thus of articles G as formed in side die, is such as to allow for an easy and immediate removal of article G from the die.

In order to carrv out this removal. once the upper die C is lifted and the article G uncovered a pull is exerted thereon in the direction of arrow Y. The lands or walls 28, 30 between different cavities D ensure the planarity of surfaces 15, 17 of rollers F (without any undercut). Also in consequence of the presence of intervening spaces 23 as defined by the bridges 32, 34 all along the sides 16, 18 of mould B the resistance encountered when the article is removed from the mould is minimized. The removal of the sheet M in the vicinity of ends 19, 21 is made easy by the resilience of the material forming said article G. This is because the resilience allows ends 19, 21 to deflect and to release from the inner edges 25, 27 of each cavity D. This allows each roller F to be readily removed from its die cavity D.

The presence of intervening spaces 23, which extends all along the surfaces 16, 18 and which is formed by bridges 32, 34 results in a proper cylindrical form of the roller ends. The remaining roller portion, corresponding to the portion 20 of cavity D has a shape which differs from cylindrical. Instead, this portion has a connecting zone with the sheet M (Figures 5 and 7). Nevertheless, the outward appearance of the article displays a plurality of parallel and adjacent cylindrical rollers F.

Instead of a hot pressing process, an injection moulding of the material, for example, rubber, or thermoplastics material is possible.

WHAT WE CLAIM-IS: 1. A mould for producing a moulded article of flexible material having a surface carrying a series of longitudinally extending rollers of part-circular section which rollers extend from and are integral with a common base sheet, the mould comprising a first bottom die having a plurality of roller forming cavities each defined by lands in the die contoured to obtain an undercut-free cross-section for the major part of each roller, said first die co-operating with a second upper die one of which has bridges extending across longitudinally opposite ends of each cavity, said bridges having a width and a thickness sufficient to form an intervening space between each roller end and its base sheet, said intervening space permitting the rollers to be flexible in the region of the bridges and facilitating release of the roller ends from the respective cavities, during the article removal from the mould.

2. A mould as claimed in Claim 1, wherein each mould cavity of the first bottom die comprises a main portion having a semicylindrical bottom surface from which vertical side walls extend upwardly to define the lands, this main portion being wholly open upwardly and a shorter portion at each of the main portions having a circular cross-section partly defined in the mould by the bridges.

3. An article moulded from a mould as claimed in Claim 1. or Claim 2. wherein the article is moulded by hot pressing a material such as rubber or thermoplastics material, wherein the article has a base sheet carrying a non-skid pattern comprising a plurality of parallel and adjacent part cylindrical rollers which at both longitudinal ends of the rollers are separated from said base sheets.

4. A shoe sole formed from an article as claimed in Claim 3.

5. A mould for producing a moulded article of flexible material having a surface carrying a series of longitudinally extending rollers of part-circular section, which rollers extend from and are integral with a common base sheet, the mould being arranged, constructed and adapted to operate substantially as hereinbefore described.

6. A shoe sole manufactured from a mould according to Claim 5.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. from the mould is minimized. The removal of the sheet M in the vicinity of ends 19, 21 is made easy by the resilience of the material forming said article G. This is because the resilience allows ends 19, 21 to deflect and to release from the inner edges 25, 27 of each cavity D. This allows each roller F to be readily removed from its die cavity D. The presence of intervening spaces 23, which extends all along the surfaces 16, 18 and which is formed by bridges 32, 34 results in a proper cylindrical form of the roller ends. The remaining roller portion, corresponding to the portion 20 of cavity D has a shape which differs from cylindrical. Instead, this portion has a connecting zone with the sheet M (Figures 5 and 7). Nevertheless, the outward appearance of the article displays a plurality of parallel and adjacent cylindrical rollers F. Instead of a hot pressing process, an injection moulding of the material, for example, rubber, or thermoplastics material is possible. WHAT WE CLAIM-IS:

1. A mould for producing a moulded article of flexible material having a surface carrying a series of longitudinally extending rollers of part-circular section which rollers extend from and are integral with a common base sheet, the mould comprising a first bottom die having a plurality of roller forming cavities each defined by lands in the die contoured to obtain an undercut-free cross-section for the major part of each roller, said first die co-operating with a second upper die one of which has bridges extending across longitudinally opposite ends of each cavity, said bridges having a width and a thickness sufficient to form an intervening space between each roller end and its base sheet, said intervening space permitting the rollers to be flexible in the region of the bridges and facilitating release of the roller ends from the respective cavities, during the article removal from the mould.

2. A mould as claimed in Claim 1, wherein each mould cavity of the first bottom die comprises a main portion having a semicylindrical bottom surface from which vertical side walls extend upwardly to define the lands, this main portion being wholly open upwardly and a shorter portion at each of the main portions having a circular cross-section partly defined in the mould by the bridges.

3. An article moulded from a mould as claimed in Claim 1. or Claim 2. wherein the article is moulded by hot pressing a material such as rubber or thermoplastics material, wherein the article has a base sheet carrying a non-skid pattern comprising a plurality of parallel and adjacent part cylindrical rollers which at both longitudinal ends of the rollers are separated from said base sheets.

4. A shoe sole formed from an article as claimed in Claim 3.

5. A mould for producing a moulded article of flexible material having a surface carrying a series of longitudinally extending rollers of part-circular section, which rollers extend from and are integral with a common base sheet, the mould being arranged, constructed and adapted to operate substantially as hereinbefore described.

6. A shoe sole manufactured from a mould according to Claim 5.