CA2094644C - Method and apparatus for injection moulding rubber soles having at least two layers - Google Patents
Method and apparatus for injection moulding rubber soles having at least two layers Download PDFInfo
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- CA2094644C CA2094644C CA002094644A CA2094644A CA2094644C CA 2094644 C CA2094644 C CA 2094644C CA 002094644 A CA002094644 A CA 002094644A CA 2094644 A CA2094644 A CA 2094644A CA 2094644 C CA2094644 C CA 2094644C
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- mould
- rubber
- mould part
- layer
- mould cavity
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D35/00—Producing footwear
- B29D35/06—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising
- B29D35/08—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts
- B29D35/081—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts by injection moulding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/02—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles
- B29C44/08—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles for articles of definite length, i.e. discrete articles using several expanding or moulding steps
- B29C44/083—Increasing the size of the cavity after a first part has foamed, e.g. substituting one mould part with another
- B29C44/086—Increasing the size of the cavity after a first part has foamed, e.g. substituting one mould part with another and feeding more material into the enlarged cavity
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D35/00—Producing footwear
- B29D35/06—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising
- B29D35/061—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising by injection moulding
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D35/00—Producing footwear
- B29D35/06—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising
- B29D35/08—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts
- B29D35/081—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts by injection moulding
- B29D35/082—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts by injection moulding injecting first the outer sole part
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D35/00—Producing footwear
- B29D35/06—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising
- B29D35/08—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts
- B29D35/085—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts by compression moulding, vulcanising or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D35/00—Producing footwear
- B29D35/06—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising
- B29D35/08—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts
- B29D35/085—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts by compression moulding, vulcanising or the like
- B29D35/087—Producing footwear having soles or heels formed and joined on to preformed uppers using a moulding technique, e.g. by injection moulding, pressing and vulcanising having multilayered parts by compression moulding, vulcanising or the like forming first the outer sole part
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Footwear And Its Accessory, Manufacturing Method And Apparatuses (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
Process for injection moulding rubber or rubber-mixture soles having at least two layers and connecting them to one another and if required to a shoe upper. First the rubber mixture for the bottom sole layer is injected into an enlarged mould cavity and the latter is made smaller to match the volume of the bottom sole layer; once the rubber mixture has partially solidified the upper delimitation means for the bottom sole layer is removed and is replaced by a last. The rubber mixture for the inner sole layer is infected into the thus created mould cavity. By displacing the bottom sole layer upwards, the mould cavity is made smaller to match the size of the inner sole layer; after partial solidification of the rubber mixture the lower delimitation means of the inner sole layer is lowered by a certain distance and the inner sole is allowed to expand in controlled manner with the mould cavity enlarged. The apparatus according to the invention (Fig. 6) provides an intermediate piece (1) which is arranged between lateral mould parts (16a) and the bottom die (2) and can traverse both horizontally and vertically.
Description
PROCESS AND APPARATUS FOR INJECTION MOULDING RUBBER SOLES
HAVING AT LEAST TWO LAYERS
The invention relates to a process for injection moulding rubber soles having at least two layers, and to an apparatus for carrying out the process.
Because of the different reaction behaviour of rubber and thermoplastic plastics materials, there is a fundamental difference in type of procedure when injection moulding these materials, as there is in the results obtained.
Thus, when using rubber it was hitherto only possible to produce a simple solid rubber sole. It was usually used as bottom soles, in particular because of its high abrasion resistance.
It is also known to provide a two-layer sole construction comprising a bottom sole and an inner sole of rubber. The second sole or inner sole increases the cushioning comfort of the shoe.
DE-AS 2 241 493 discloses a process for producing multi-layer soles, in particular made of polyurethane or rubber, the material for forming the individual layers being injected successively into a mould whereof the mould cavity is larger on receiving the material than the volume of the respective sole layer and which, once an injection procedure is complete, is made smaller by displacing the bottom die to the volume corresponding to the sole layer, while moulding the sole layer. Once the material has partially solidified, the upper delimitation means for the bottom sole layer is removed and is replaced by an upper delimitation means for the inner sole layer - the last. Then, the material for the inner sole layer is injected into the thus created mould cavity and the latter is finally made smaller by displacing the bottom sole layer to the upper delimitation means of the inner sole layer to match the size of the inner sole layer. However, the inner sole has no pores which increase cushioning.
DE-OS 40 22 778 discloses a process for injection moulding rubber soles in which the unvulcanized raw rubber composition is injected by way of two injection units successively or at the same time into two mould cavities which are arranged one above the other and which are separated from one another and heated by an intermediate piece, and the unvulcanized raw rubber composition is at least pre-vulcanized there, the temperature of the intermediate piece being chosen such that premature vulcanization therein is prevented. The intermediate piece can be pushed in between the mould cavities. In the intermediate piece are the temperature-controllable channels which guide the raw rubber composition, which for its part can be introduced by way of nozzles. The intermediate piece can traverse exclusively horizontally.
The state of the art does not teach injection moulding of a two-layer rubber sole directly onto an upper, the intermediate sole being of rubber. This is up to now only known using thermoplastic plastics materials. Attempts using rubber mixtures have shown that the expansion behaviour of the rubber mixture on foaming was uncontrolled and unpredictable. The inner sole injected with the rubber mixture "bagged", and the dimensional accuracy and profiling were correspondingly poor. These soles were only suitable for attachment by adhesion and had to be subjected to subsequent work.
In contrast, although foamed plastics soles can be produced to a certain extent, the plastics material has certain disadvantages. It is synthetic and has need of the chemical industry for its production. However, chemical industrial plants pollute the environment.
Moreover, there are a considerable number of countries with no or only little chemical industry. These have to import plastics at some expense. If these are also countries with a weak currency, then it is quite possible that there is no money available for plastics materials.
There are also countries with bans on import. For example, PVC soles cannot be imported to Russia, since they cannot withstand the extremely low temperatures and break.
It has further proved disadvantageous in the processing of plastics that the mould parts used have to be removed from the injection mould by separating agents after each injection procedure, which represents an additional environment-polluting measure.
The object of the invention is to produce, in a process or an apparatus for injection moulding a rubber sole having at least two layers, at least one of the two soles as a foamed rubber sole, without the use of complicated technical devices.
In accordance with the invention, there is provided a process for injection moulding of rubber or rubber mixture into two-layer soles and connecting the two layers to one another, in which:
a) the rubber mixture for a midsole layer and an outsole layer is injected simultaneously into corresponding mould cavities, b) the mould cavities, separable from one another by a movable adapter, are subsequently closed by a bottom mould part which is moved upwards from below, c) the rubber material is then moulded in form and pattern till a predefined reaction temperature has been reached, d) following this operation an expansion space for the midsole layer is formed by enlarging the corresponding mould cavity downwards for which purpose the movable adapter is lowered along with the bottom mould part, e) after that, when the foamed midsole layer has sufficiently stabilized, the movable adapter and the bottom mould part are lowered till the movable adapter can be withdrawn from the apparatus, f) finally, by raising the bottom mould part, the outsole layer and the midsole layer are put into contact with one another and allowed to vulcanize completely.
As a result of the process according to the invention, the possibility that on opening the mould an uncontrolled expansion of the propellant in the rubber mixture takes place, resulting in a sole shape which cannot be predicted, is prevented. The combination of selected rubber mixture, maintaining the conventional pressing time, subsequent slow and limited opening of the mould cavity enables the expansion procedure to be controlled and monitored. The inner sole foams evenly and its shape and thickness are predictable.
During the pressing time, the portion of the rubber composition which bears directly against the warming mould parts vulcanizes more quickly, so that a shiny layer is formed. This does not apply to the portion of the rubber composition which bears against the bottom sole, since this has an insulating effect; there, vulcanization is delayed. If the mould cavity is made slowly larger after the pressing time, then the rubber composition can expand into the free space. 'The previously formed lateral shiny layer acts as a type of guide rail and prevents expansion into the lateral free space which opens.
The sole thickness is determined by the size of the lowered distance. The sole can be produced in various thicknesses as required without expense.
HAVING AT LEAST TWO LAYERS
The invention relates to a process for injection moulding rubber soles having at least two layers, and to an apparatus for carrying out the process.
Because of the different reaction behaviour of rubber and thermoplastic plastics materials, there is a fundamental difference in type of procedure when injection moulding these materials, as there is in the results obtained.
Thus, when using rubber it was hitherto only possible to produce a simple solid rubber sole. It was usually used as bottom soles, in particular because of its high abrasion resistance.
It is also known to provide a two-layer sole construction comprising a bottom sole and an inner sole of rubber. The second sole or inner sole increases the cushioning comfort of the shoe.
DE-AS 2 241 493 discloses a process for producing multi-layer soles, in particular made of polyurethane or rubber, the material for forming the individual layers being injected successively into a mould whereof the mould cavity is larger on receiving the material than the volume of the respective sole layer and which, once an injection procedure is complete, is made smaller by displacing the bottom die to the volume corresponding to the sole layer, while moulding the sole layer. Once the material has partially solidified, the upper delimitation means for the bottom sole layer is removed and is replaced by an upper delimitation means for the inner sole layer - the last. Then, the material for the inner sole layer is injected into the thus created mould cavity and the latter is finally made smaller by displacing the bottom sole layer to the upper delimitation means of the inner sole layer to match the size of the inner sole layer. However, the inner sole has no pores which increase cushioning.
DE-OS 40 22 778 discloses a process for injection moulding rubber soles in which the unvulcanized raw rubber composition is injected by way of two injection units successively or at the same time into two mould cavities which are arranged one above the other and which are separated from one another and heated by an intermediate piece, and the unvulcanized raw rubber composition is at least pre-vulcanized there, the temperature of the intermediate piece being chosen such that premature vulcanization therein is prevented. The intermediate piece can be pushed in between the mould cavities. In the intermediate piece are the temperature-controllable channels which guide the raw rubber composition, which for its part can be introduced by way of nozzles. The intermediate piece can traverse exclusively horizontally.
The state of the art does not teach injection moulding of a two-layer rubber sole directly onto an upper, the intermediate sole being of rubber. This is up to now only known using thermoplastic plastics materials. Attempts using rubber mixtures have shown that the expansion behaviour of the rubber mixture on foaming was uncontrolled and unpredictable. The inner sole injected with the rubber mixture "bagged", and the dimensional accuracy and profiling were correspondingly poor. These soles were only suitable for attachment by adhesion and had to be subjected to subsequent work.
In contrast, although foamed plastics soles can be produced to a certain extent, the plastics material has certain disadvantages. It is synthetic and has need of the chemical industry for its production. However, chemical industrial plants pollute the environment.
Moreover, there are a considerable number of countries with no or only little chemical industry. These have to import plastics at some expense. If these are also countries with a weak currency, then it is quite possible that there is no money available for plastics materials.
There are also countries with bans on import. For example, PVC soles cannot be imported to Russia, since they cannot withstand the extremely low temperatures and break.
It has further proved disadvantageous in the processing of plastics that the mould parts used have to be removed from the injection mould by separating agents after each injection procedure, which represents an additional environment-polluting measure.
The object of the invention is to produce, in a process or an apparatus for injection moulding a rubber sole having at least two layers, at least one of the two soles as a foamed rubber sole, without the use of complicated technical devices.
In accordance with the invention, there is provided a process for injection moulding of rubber or rubber mixture into two-layer soles and connecting the two layers to one another, in which:
a) the rubber mixture for a midsole layer and an outsole layer is injected simultaneously into corresponding mould cavities, b) the mould cavities, separable from one another by a movable adapter, are subsequently closed by a bottom mould part which is moved upwards from below, c) the rubber material is then moulded in form and pattern till a predefined reaction temperature has been reached, d) following this operation an expansion space for the midsole layer is formed by enlarging the corresponding mould cavity downwards for which purpose the movable adapter is lowered along with the bottom mould part, e) after that, when the foamed midsole layer has sufficiently stabilized, the movable adapter and the bottom mould part are lowered till the movable adapter can be withdrawn from the apparatus, f) finally, by raising the bottom mould part, the outsole layer and the midsole layer are put into contact with one another and allowed to vulcanize completely.
As a result of the process according to the invention, the possibility that on opening the mould an uncontrolled expansion of the propellant in the rubber mixture takes place, resulting in a sole shape which cannot be predicted, is prevented. The combination of selected rubber mixture, maintaining the conventional pressing time, subsequent slow and limited opening of the mould cavity enables the expansion procedure to be controlled and monitored. The inner sole foams evenly and its shape and thickness are predictable.
During the pressing time, the portion of the rubber composition which bears directly against the warming mould parts vulcanizes more quickly, so that a shiny layer is formed. This does not apply to the portion of the rubber composition which bears against the bottom sole, since this has an insulating effect; there, vulcanization is delayed. If the mould cavity is made slowly larger after the pressing time, then the rubber composition can expand into the free space. 'The previously formed lateral shiny layer acts as a type of guide rail and prevents expansion into the lateral free space which opens.
The sole thickness is determined by the size of the lowered distance. The sole can be produced in various thicknesses as required without expense.
In accordance with a further advantageous embodiment of the invention, pororubber is used as the rubber mixture for the inner sole layer. Pororubber is a particular rubber mixture with a propellant additive, so that on warming the rubber can foam, and as a result of gas release pores are created and a sole with high level of cushioning is created.
According to a further aspect of the invention, there is provided an apparatus for use in the process described above with reference to the drawings, the apparatus including a list, a lateral mould part, a bottom mould part and a movable adapter which are shiftable relatively to one another, the movable adapter being accommodated between the lateral mould part and the list - which can be placed on that lateral mould part - and the bottom mould part, and being shiftable both vertically and horizontally. Using this apparatus, it is possible to injection mould the inner sole on the bottom sole at the same time. The movable adapter (intermediate piece) can be moved horizontally and vertically, so that an enlarged mould cavity for expanding the inner sole can be provided together with the lateral mould part.
The bottom mould part and the intermediate piece can thereby traverse vertically together. As a result of this movement, the mould cavities are closed. The common traversing of intermediate piece and bottom die furthermore makes it possible for the mould cavity for the inner sole to be opened independently of the mould cavity of the bottom sole.
The lower mould surface of the intermediate piece may be heated only to a temperature of approximately 120°C. In the apparatus according to the invention, the bottom sole and the inner sole are injection moulded at the same time. For this reason, there is on the base of the mould cavity of the inner sole no insulating bottom sole as in the application of the process according to the invention using the conventional injection moulding apparatus. The vulcanization of the rubber mixture on the side facing the bottom sole, which begins later, results in a favourable behaviour as regards the formation of the shiny layer, however. In order to achieve a similar behaviour in the apparatus according to the invention, the base of the mould cavity of the inner sole is brought to a temperature which corresponds approximately to that of the mould cavity base with the insulating bottom sole lying on it.
There may be arranged in the intermediate piece and in the lateral mould part injection channels for supplying rubber mixture. A lateral mould part with injection channel is a known mould part of conventional injection moulding apparatus. The apparatus according to the invention thus enables known and conventional mould parts to be used as they are and thus greatly reduces the costs of~adapting a conventional injection mould to the apparatus according to the invention in order to be able to exploit the advantages of the invention.
After producing the bottom sole and the foamed inner sole, the intermediate piece is withdrawn from the mould and the two soles are brought together in order to complete vulcanization. This is effected by the horizontal movability of the intermediate piece.
In summary, it is found that the process according to the invention enables a foamed rubber inner sole to be produced and at the same time enables the use of a conventional injection moulding apparatus. A foamed rubber inner sole having a previously predictable shape, sole thickness and degree of cushioning can be produced and foamed onto a bottom sole. The process does not require any great expense for apparatus, but makes use of the conventional moulds for injection moulding apparatus.
The apparatus according to the invention for carrying out the process enables the inner sole and the bottom sole to be injection moulded at the same time. Here too, mould parts which are to a very large extent commercially available are used, such as lasts, lateral _' mould part and bottom die, and only the intermediate piece - a part which is formed simply as regards the apparatus used - has to be produced specially for the apparatus.
The use of an environment-friendly and renewable raw material rubber as the material for $ producing a foamed inner sole is thus successful. Countries without industry but in which rubber is the only available - or acquirable - raw material for producing soles do not need any expensive importation of plastics. Transportation and scarce currency can be saved. As a natural material, rubber is quite harmless. Rubber is not subject to any import restrictions because of disadvantageous side effects. Thus, for example, rubber soles can be exported to Russia, since rubber is temperature-resistant.
An embodiment of the invention is illustrated in the drawings and described below in more detail. In the drawings:
Figure 1 shows a longitudinal section through the heel part of an apparatus according to the invention in the injection position, and Figure 2 shows the apparatus according to the invention, in accordance with Figure 1, in the pressing position, and Figure 3 shows the apparatus according to the invention, in accordance with Figure 1, during the controlled expansion of the inner soles, and Figure 4 shows the apparatus according to the invention, in accordance with Figure l, with the intermediate piece withdrawn, and Figure 5 shows the apparatus according to the invention, in accordance with Figure 1, during final vulcanization of the inner sole with the bottom sole, and _g_ Figure 6 shows an overall view of the apparatus accarding to Figure 1.
In the; embodiment shown, an intermediate piece 1 which can traverse is arranged between upper mould parts comprising lateral mould parts 16a and last 15a with the S upper 14a drawn on and a lower mould part, the bottom die 2.
The intermediate piece 1 contains an injection channel 32 from which channels 33, 34 lead downward. The lower part of the intermediate piece 1 is constructed as a displacer and is indicated by the reference numeral 3. The channels 33, 34 open into a mould cavity 5. The underside of the displacer ~ forms the mould cavity 5 by means of its upper mould surface 9 and its horizontal part piece 30a and the upper side of the bottom die 2, comprising a lower mould surface 8 with horizontal part piece 31a. The contour of the bottom die is designed as a shell-shaped bottom die for producing a bottom sole 13a with peripheral edge. The mould cavity 5 substantially corresponds to the mould cavity 23 from Figures 1 and 2. The mould suri:ace 9 correspondingly has a contour 20a.
The upper mould surface of the intermediate piece 1 is composed from a horizontal part piece 26 and a mould surface 6, having a contour, for moulding an inner sole underside.
The upper mould surface of the intermediate piece 1 forms the mould cavity 4 by means of the underside of the upper 14a and parts of the lateral mould part 16a, in particular a horizontal lateral mould piece 21a which merges into a lateral mould undercut 27a and a sealing lip 29a which acts in sealing manner on the upper 14a.
The intermediate piece 1 is displaceable vertically between the lateral mould parts 16a.
Depending on its position with respect to the lateral mould part 16a. it can traverse laterally out of the mould. The bottom die 2 can only traverse vertically.
The; individual mould parts are heated to 170°C' during injection moulding.
The process proceeds as follows: the bottom sole 13a and the inner sole 12a are produced at the same time (Figs. 1 and 2). To this end, rubber composition is injected by way of an injection cylinder into the injection channel 32 and into the channels 33 and 34 and into the mould cavity 5. At the same. time, pororubber is injected by way of an injection cylinder into the channel 24a and into the mould cavity. The material is distributed evenly in the mould by injection. After injection, the bottom die 2 is raised;
this closes the mould cavity 5 and the intermediate piece 1 now also traverses upwards, seated on the bottom die 2. The movement is complete when the mould cavity 4 is also closed and the injected rubber material is pressed into the mould and impression. The excc;ss material is during this pressed into the separation plane.
During the pressing time, the temperature of the rubber mixtures in the heated mould parts is increased. When the reaction temperature is reached, vulcanization begins (Fig.
2). After the predetermined pressing time, the intermediate piece 1 is lowered together with the bottom die 2 so that the mould cavity 4 is enlarged downwards and an expansion space for the poro composition is created. During this, the mould cavity 5 remains closed (Fig;. 3). In this position, heating is continued until the crosslinking reaction and the propellant development are more or less complete. Once the poro material is dimensionally stable, the lateral parts 16a can be moved apart. The intermediate piece 1 and the bottom die 2 are lowered together. Once the common lowering movement of intermediate piece l and bottom die 2 is complete, the bottom die 2 continues to be lowered separately and the mould cavity 5 is opened. The intermediate piece 1 is withdrawn from the mould.
Thc; bottom die 2 is raised with the bottom sole 13a, and the bottom sole 13a and the inner sole 12a are brought into contact and their vulcanization together can now be connpleted.
According to a further aspect of the invention, there is provided an apparatus for use in the process described above with reference to the drawings, the apparatus including a list, a lateral mould part, a bottom mould part and a movable adapter which are shiftable relatively to one another, the movable adapter being accommodated between the lateral mould part and the list - which can be placed on that lateral mould part - and the bottom mould part, and being shiftable both vertically and horizontally. Using this apparatus, it is possible to injection mould the inner sole on the bottom sole at the same time. The movable adapter (intermediate piece) can be moved horizontally and vertically, so that an enlarged mould cavity for expanding the inner sole can be provided together with the lateral mould part.
The bottom mould part and the intermediate piece can thereby traverse vertically together. As a result of this movement, the mould cavities are closed. The common traversing of intermediate piece and bottom die furthermore makes it possible for the mould cavity for the inner sole to be opened independently of the mould cavity of the bottom sole.
The lower mould surface of the intermediate piece may be heated only to a temperature of approximately 120°C. In the apparatus according to the invention, the bottom sole and the inner sole are injection moulded at the same time. For this reason, there is on the base of the mould cavity of the inner sole no insulating bottom sole as in the application of the process according to the invention using the conventional injection moulding apparatus. The vulcanization of the rubber mixture on the side facing the bottom sole, which begins later, results in a favourable behaviour as regards the formation of the shiny layer, however. In order to achieve a similar behaviour in the apparatus according to the invention, the base of the mould cavity of the inner sole is brought to a temperature which corresponds approximately to that of the mould cavity base with the insulating bottom sole lying on it.
There may be arranged in the intermediate piece and in the lateral mould part injection channels for supplying rubber mixture. A lateral mould part with injection channel is a known mould part of conventional injection moulding apparatus. The apparatus according to the invention thus enables known and conventional mould parts to be used as they are and thus greatly reduces the costs of~adapting a conventional injection mould to the apparatus according to the invention in order to be able to exploit the advantages of the invention.
After producing the bottom sole and the foamed inner sole, the intermediate piece is withdrawn from the mould and the two soles are brought together in order to complete vulcanization. This is effected by the horizontal movability of the intermediate piece.
In summary, it is found that the process according to the invention enables a foamed rubber inner sole to be produced and at the same time enables the use of a conventional injection moulding apparatus. A foamed rubber inner sole having a previously predictable shape, sole thickness and degree of cushioning can be produced and foamed onto a bottom sole. The process does not require any great expense for apparatus, but makes use of the conventional moulds for injection moulding apparatus.
The apparatus according to the invention for carrying out the process enables the inner sole and the bottom sole to be injection moulded at the same time. Here too, mould parts which are to a very large extent commercially available are used, such as lasts, lateral _' mould part and bottom die, and only the intermediate piece - a part which is formed simply as regards the apparatus used - has to be produced specially for the apparatus.
The use of an environment-friendly and renewable raw material rubber as the material for $ producing a foamed inner sole is thus successful. Countries without industry but in which rubber is the only available - or acquirable - raw material for producing soles do not need any expensive importation of plastics. Transportation and scarce currency can be saved. As a natural material, rubber is quite harmless. Rubber is not subject to any import restrictions because of disadvantageous side effects. Thus, for example, rubber soles can be exported to Russia, since rubber is temperature-resistant.
An embodiment of the invention is illustrated in the drawings and described below in more detail. In the drawings:
Figure 1 shows a longitudinal section through the heel part of an apparatus according to the invention in the injection position, and Figure 2 shows the apparatus according to the invention, in accordance with Figure 1, in the pressing position, and Figure 3 shows the apparatus according to the invention, in accordance with Figure 1, during the controlled expansion of the inner soles, and Figure 4 shows the apparatus according to the invention, in accordance with Figure l, with the intermediate piece withdrawn, and Figure 5 shows the apparatus according to the invention, in accordance with Figure 1, during final vulcanization of the inner sole with the bottom sole, and _g_ Figure 6 shows an overall view of the apparatus accarding to Figure 1.
In the; embodiment shown, an intermediate piece 1 which can traverse is arranged between upper mould parts comprising lateral mould parts 16a and last 15a with the S upper 14a drawn on and a lower mould part, the bottom die 2.
The intermediate piece 1 contains an injection channel 32 from which channels 33, 34 lead downward. The lower part of the intermediate piece 1 is constructed as a displacer and is indicated by the reference numeral 3. The channels 33, 34 open into a mould cavity 5. The underside of the displacer ~ forms the mould cavity 5 by means of its upper mould surface 9 and its horizontal part piece 30a and the upper side of the bottom die 2, comprising a lower mould surface 8 with horizontal part piece 31a. The contour of the bottom die is designed as a shell-shaped bottom die for producing a bottom sole 13a with peripheral edge. The mould cavity 5 substantially corresponds to the mould cavity 23 from Figures 1 and 2. The mould suri:ace 9 correspondingly has a contour 20a.
The upper mould surface of the intermediate piece 1 is composed from a horizontal part piece 26 and a mould surface 6, having a contour, for moulding an inner sole underside.
The upper mould surface of the intermediate piece 1 forms the mould cavity 4 by means of the underside of the upper 14a and parts of the lateral mould part 16a, in particular a horizontal lateral mould piece 21a which merges into a lateral mould undercut 27a and a sealing lip 29a which acts in sealing manner on the upper 14a.
The intermediate piece 1 is displaceable vertically between the lateral mould parts 16a.
Depending on its position with respect to the lateral mould part 16a. it can traverse laterally out of the mould. The bottom die 2 can only traverse vertically.
The; individual mould parts are heated to 170°C' during injection moulding.
The process proceeds as follows: the bottom sole 13a and the inner sole 12a are produced at the same time (Figs. 1 and 2). To this end, rubber composition is injected by way of an injection cylinder into the injection channel 32 and into the channels 33 and 34 and into the mould cavity 5. At the same. time, pororubber is injected by way of an injection cylinder into the channel 24a and into the mould cavity. The material is distributed evenly in the mould by injection. After injection, the bottom die 2 is raised;
this closes the mould cavity 5 and the intermediate piece 1 now also traverses upwards, seated on the bottom die 2. The movement is complete when the mould cavity 4 is also closed and the injected rubber material is pressed into the mould and impression. The excc;ss material is during this pressed into the separation plane.
During the pressing time, the temperature of the rubber mixtures in the heated mould parts is increased. When the reaction temperature is reached, vulcanization begins (Fig.
2). After the predetermined pressing time, the intermediate piece 1 is lowered together with the bottom die 2 so that the mould cavity 4 is enlarged downwards and an expansion space for the poro composition is created. During this, the mould cavity 5 remains closed (Fig;. 3). In this position, heating is continued until the crosslinking reaction and the propellant development are more or less complete. Once the poro material is dimensionally stable, the lateral parts 16a can be moved apart. The intermediate piece 1 and the bottom die 2 are lowered together. Once the common lowering movement of intermediate piece l and bottom die 2 is complete, the bottom die 2 continues to be lowered separately and the mould cavity 5 is opened. The intermediate piece 1 is withdrawn from the mould.
Thc; bottom die 2 is raised with the bottom sole 13a, and the bottom sole 13a and the inner sole 12a are brought into contact and their vulcanization together can now be connpleted.
Claims (8)
1. Process for injection moulding of rubber or rubber mixture into two-layersoles (12a, 13a) and connecting the two layers to one another, in which:
a) the rubber mixture for a midsole layer (12a) and an outsole layer (13a) is injected simultaneously into corresponding mould cavities (4, 5) of a mould apparatus;
b) the mould cavities (4, 5), separable from one another by a movable adapter (1), are subsequently closed by a bottom mould part (2) which is moved upwards from below;
c) the rubber material is then moulded in form and pattern till a predefined reaction temperature has been reached, d) following this operation, an expansion space for the midsole layer (12a) is formed by enlarging the corresponding mould cavity (4) downwards for which purpose the moveable adapter (1) is lowered along with the bottom mould part (2), e) after that, when the midsole layer (12a) has foamed and has sufficiently stabilized, the movable adapter (1) and the bottom mould part (2) are lowered till the movable adapter (1) can be withdrawn from the apparatus;
f) finally, by raising the bottom mould part (2), the outsole layer (13a) and the midsole layer (12a) are put into contact with one another and allowed to vulcanize completely.
a) the rubber mixture for a midsole layer (12a) and an outsole layer (13a) is injected simultaneously into corresponding mould cavities (4, 5) of a mould apparatus;
b) the mould cavities (4, 5), separable from one another by a movable adapter (1), are subsequently closed by a bottom mould part (2) which is moved upwards from below;
c) the rubber material is then moulded in form and pattern till a predefined reaction temperature has been reached, d) following this operation, an expansion space for the midsole layer (12a) is formed by enlarging the corresponding mould cavity (4) downwards for which purpose the moveable adapter (1) is lowered along with the bottom mould part (2), e) after that, when the midsole layer (12a) has foamed and has sufficiently stabilized, the movable adapter (1) and the bottom mould part (2) are lowered till the movable adapter (1) can be withdrawn from the apparatus;
f) finally, by raising the bottom mould part (2), the outsole layer (13a) and the midsole layer (12a) are put into contact with one another and allowed to vulcanize completely.
2. Process according to claim l, characterized in that poro-rubber is used as rubber mixture for the midsole layer (12).
3. Process according to either of claims 1 or 2, further comprising connecting the two layers to a shoe upper (14).
4. Apparatus for application of the process according to any of claims 1 through 3, including a last (15a), a lateral mould part (16a), a bottom mould part (2) and a movable adapter (1) which are shiftable relative to one another, the movable adapter (1) being accommodated between the lateral mould part (16a) and the last (15a) - which can be placed on that lateral mould part - and the bottom mould part (2), and being shiftable both vertically and horizontally.
5. Apparatus according to claim 4, characterized in that the bottom mould part (2) can be shifted vertically.
6. Apparatus according to either of claims 4 or 5, characterized in that the moveable adapter (1) has a moulding face (6) on its bottom side forming a lower limiting face of the midsole.
7. Apparatus according to any one of claims 4 through 6, characterized in that the lateral mould part (15a) has a channel (24a) through which material is injected into the mould cavity (4), and that the movable adapter (1) has an injection channel (32) from which other channels (33, 34) lead to the mould cavity (5).
8. Apparatus according to claim 7, characterized in that a material injection channel leading to the mould cavity (5) is arranged in the bottom mould part (2).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE4214254A DE4214254C2 (en) | 1992-04-30 | 1992-04-30 | Method and device for injection molding two-layer rubber soles |
| DEP4214254.7 | 1992-04-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2094644A1 CA2094644A1 (en) | 1993-10-31 |
| CA2094644C true CA2094644C (en) | 2002-06-11 |
Family
ID=6457843
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002094644A Expired - Fee Related CA2094644C (en) | 1992-04-30 | 1993-04-22 | Method and apparatus for injection moulding rubber soles having at least two layers |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0575692B1 (en) |
| CA (1) | CA2094644C (en) |
| DE (1) | DE4214254C2 (en) |
| ES (1) | ES2087583T3 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT2407U1 (en) * | 1997-07-23 | 1998-10-27 | Gerhard Pliessnig | ORTHOPEDICAL SUPPORT, IN PARTICULAR ORTHOPEDICAL SHOE INSOLE |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1629399A1 (en) * | 1966-03-04 | 1971-02-04 | Funck Kg Dr Ing | Method and tool for the production of molded foam bodies with reinforced outer skin |
| CA926571A (en) * | 1969-10-03 | 1973-05-22 | H. Drag Edward | Method and apparatus for molding rubber |
| DE2241493C3 (en) * | 1972-08-23 | 1975-06-26 | Desma-Werke Gmbh, 2807 Uesen | Method and device for the production of multi-layer soles from materials of low viscosity, in particular polyurethane or rubber |
| GB1420948A (en) * | 1972-10-26 | 1976-01-14 | Ici Ltd | Injection moulding process |
| DE2650398A1 (en) * | 1976-11-03 | 1978-09-21 | Desma Werke Gmbh | METHOD AND DEVICE FOR CASTING OR INJECTION MOLDING IN PARTICULAR TWO-PIECE OR MULTI-PIECE SHOE SOLES |
| GB2076725A (en) * | 1980-05-23 | 1981-12-09 | Liu Chin Lien | Method of making laminated sole |
| GB2105252A (en) * | 1981-08-27 | 1983-03-23 | Geminder Rodney Ian Peter | Production of footwear with a two-coloured moulded sole |
| DE4022778A1 (en) * | 1990-07-18 | 1992-01-23 | Kloeckner Ferromatik Desma | Rubber sole injection moulding - uses distributor between moulds at temp. preventing premature vulcanisation |
-
1992
- 1992-04-30 DE DE4214254A patent/DE4214254C2/en not_active Expired - Fee Related
-
1993
- 1993-02-04 EP EP93101720A patent/EP0575692B1/en not_active Expired - Lifetime
- 1993-02-04 ES ES93101720T patent/ES2087583T3/en not_active Expired - Lifetime
- 1993-04-22 CA CA002094644A patent/CA2094644C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| ES2087583T3 (en) | 1996-07-16 |
| EP0575692B1 (en) | 1996-04-03 |
| EP0575692A1 (en) | 1993-12-29 |
| CA2094644A1 (en) | 1993-10-31 |
| DE4214254C2 (en) | 1995-04-06 |
| DE4214254A1 (en) | 1993-11-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |