WO2003053664A1

WO2003053664A1 - Mold for producing shoe-sole

Info

Publication number: WO2003053664A1
Application number: PCT/KR2002/002333
Authority: WO
Inventors: Songjo Lim
Original assignee: Songjo Lim
Priority date: 2001-12-11
Filing date: 2002-12-11
Publication date: 2003-07-03
Also published as: AU2002366771A1; KR20030003202A

Abstract

Disclosed is a mold for producing a shoe-sole having an outsole made of a rubber material and a midsole made of ethylene vinyl acetate, integratedly molded in a single aluminium mold by use of an elastic intermediate plate part. This mold includes a mold part made of aluminium and including an upper mold, a middle mold introduced with a midsole material, and a lower mold having an outsole forming cavity with a bottom surface of a waved pattern, a cutter part formed along an outside edge of the outsole forming cavity, and a surplus outsole-collecting groove formed along the cutter part; and an intermediate plate part, including an outer cover made of aluminium, a cutter part protector positioned in the outer cover and made of a material having lower hardness than the outer cover, and an elastic resin part positioned below the cutter part protector.

Description

MOLD FOR PRODUCING SHOE-SOLE

Technical Field

The present invention relates to molds for producing shoe-soles, and more specifically, to a mold for producing a shoe-sole comprising an midsole and an outsole integrated together, characterized in that the outsole made of a rubber material and the midsole made of ethylene vinyl acetate are molded in a single aluminum mold by use of an intermediate plate part made of an elastic material.

Background Art

As well known to those skilled in the art, with improvements in living conditions, variously designed shoes have been produced as demands of users have changed. In addition, diverse shoes suitable for special purposes have been prepared. However, structures of most shoes are substantially the same.

Referring to Fig. 1, there is shown a shoe 1 comprising a shoe-sole having two parts 2 and 3, and a leather upper 4 attached to an upper portion of the shoe-sole 2 and 3. The shoe-sole 2 and 3 includes an outsole 3 forming a bottom piece of the shoe-sole, and a midsole 2 forming a middle layer of the shoe-sole. The outsole 3 is made of a rubber material for traction and wear resistance, and the midsole 2 is made of an urethane or ethylene vinyl acetate as a foam-type material, in consideration of impact absorption.

Each of the midsole and the outsole is prepared through a separate process by use of separate molds, and the prepared midsole is adhered to the outsole to produce the shoe-sole. Hereinafter, a description will be given of a shoe-sole material and a production process of the shoe-sole

The outsole 3 is mainly made of rubber, for improvement of traction, wear resistance and impact absorption force upon coming into contact with earth's surface For this, an outsole mold for use in preparation of the outsole made of rubber should be highly pressure resistant Thus, the outsole mold is typically made of iron

Further, the midsole 2 comprises various materials In general, the material of the midsole 2 is classified into two types, that is, a liquid phase of foamable urethane resin and ethylene vinyl acetate (hereinafter, simply abbreviated to E V A ) In the shoe industry, the above abbreviated term is readily used

The midsole made of E V A is obtained by compressing, heating and cooling the E V A via presses As shown in FIG 2, a sheet midsole material 10, referred to as phylon, is prepared by cutting a raw sheet of resin material formed of a foamable E V A , or a semi- processed state of foamed midsole material 10, referred to as a preform, is prepared The midsole material 10 is introduced into a midsole forming cavity 22 of a midsole mold 20 made of aluminum, after which the mold 20 is positioned between upper and lower press bodies 30 The midsole material 10 is molded at high temperature and under high pressure applied as downward movement of the upper press body 30 In a state of heat being blocked, while the whole mold is cooled by cooling water delivered through inner passages of the presses 30, the molded midsole material 10 is cooled, thereby obtaining the midsole As for the midsole made of E V A , a solid phase of the midsole material 10 is introduced into the mold 20, subjected to high temperature and high pressure, and then cooled Thus, the mold 20 should be made of a material capable of withstanding high pressure and exhibiting rapid heat transfer for heating and cooling The mold 20 is preferably made of aluminum in view of castability, processability, and its lightweight and hard properties As mentioned above, since the midsole and the outsole differ in preparation methods and molds thereof, they are separately formed and adhered together by means of an adhesive, to produce the shoe-sole Such conventional techniques suffer from much time and effort, and high individual unit cost In order to solve the problems, extensive efforts to prepare the outsole and the midsole using a single mold have been attempted

In this regard, an aluminum mold is used for preparation of the midsole The outsole is separately formed, after which the outsole is positioned on a lower aluminum mold An adhesive is coated on an upper surface of the outsole, on which a middle mold is positioned The midsole material is introduced into the middle mold, and is molded and adhered to the outsole at the same time

However, the above method is disadvantageous in terms of requiring an additional mold to form the outsole, and low productivity ensues, due to use of the produced outsole upon preparation of the midsole As well, when the midsole is molded, air is not sufficiently exhausted to the outside due to the outsole positioned below a lower surface of the midsole, and thus pores are formed at an adhered portion of the lower surface of the midsole and the upper surface of the outsole, resulting in poor adhesion

Alternatively, an aluminum mold for preparation of the midsole and an intermediate plate made of aluminum may be used That is, a non-vulcanized rubber sheet for preparation of the outsole is positioned on the lower aluminum mold, on which the intermediate plate made of aluminum is placed The non-vulcanized rubber sheet is vulcanized under pressure and heat by the presses, thereby preparing the outsole Then, the aluminum intermediate plate is removed, and an adhesive is coated on the upper surface of the prepared outsole, on which the middle mold is positioned The midsole material is introduced into the middle mold, and compressed, heated and cooled by movement of the upper press body, to form the midsole. Simultaneously, the outsole is adhered to the lower surface of the midsole. Thus, the shoe-sole is attained.

The above method is advantageous in terms of high productivity due to the simultaneous preparing and adhering processes of the midsole and the outsole in one mold, but has the following drawbacks.

When the outsole is prepared in the aluminum mold by use of the aluminum intermediate plate, the uneven bottom surface formed with a waved pattern of the lower mold is easily damaged under pressure. This is because 150 kgf/cm³ of pressure is applied in the state of the non-vulcanized rubber sheet being introduced. Such pressure is applied to the non-vulcanized rubber sheet placed on the lower mold and the waved pattern of the lower mold through the aluminum intermediate plate. In other words, the pressure is applied to fine wave pattern of the lower mold formed by low pressure-accurate cast method and having low hardness, through the aluminum intermediate plate, resulting in breaking the wave pattern. At present, a generally used aluminum intermediate plate functions only as a blocking sheet, without a function of distributing pressure. Thus, upon making the outsole, the fine waved pattern of the lower mold formed by low pressure-accurate cast method is essentially damaged, resulting in frequent exchange of the lower mold and the production of inferior goods. In addition, a surplus end of the outsole should be trimmed after the outsole is formed. The surplus end of the outsole is present along the edge of the adhered side surface of the midsole and the outsole. Thus, such a surplus end of the outsole is removed by use of an additional hot wire. As such, mistakes of operators or trimming work of curved surface results in damaged midsole made of a foamable resin material having low heat resistance due to heat by the hot wire, causing inferior goods. Specifically, the non-vulcanized rubber sheet is placed on the outsole forming cavity of the lower mold, on which the intermediate plate is disposed. Then, compressing and heating processes are performed by means of the presses. By heat and pressure, the rubber sheet is drawn along the uneven bottom surface of the outsole forming cavity, forming the outsole. As such, a portion of the outsole, having a broader surface area than the lower surface of the midsole, remains as the surplus outsole. The outsole having such a surplus end is formed and adhered to the midsole, after which the surplus end of the outsole is removed. That is, the midsole and the outsole are separately made and adhered together, and then the surplus end of the outsole is removed by use of the hot wire, in addition to the adhered portion of the lower surface of the midsole and the upper surface of the outsole.

When such a trimming process is performed, inferior goods may be generated, thus reducing productivity. Further, an additional finishing process is further required.

Disclosure of the Invention

Therefore, it is an object of the present invention to provide a mold for producing shoe-soles which is repeatedly usable for a long period of time, by preventing a waved pattern of a lower mold of the mold from breaking by use of an elastic intermediate plate part functioning to uniformly distribute pressure applied to the lower mold. It is another object of the present invention to provide a mold for producing shoe- soles, which is advantageous in terms of simultaneous molding and adhering processes of a midsole and an outsole, while an additional trimming process of cutting a surplus end of the outsole upon formation of the outsole is not required.

To achieve the above objects, according to a primary embodiment of the present invention, there is provided a mold for producing a shoe-sole comprising an outsole made of a rubber material for use in forming a bottom piece of the shoe-sole and a midsole made of ethylene vinyl acetate for use in forming a middle layer of the shoe-sole integrated together, comprising a mold part made of aluminum and including an upper mold, a middle mold introduced with a midsole material, and a lower mold having an outsole forming cavity with a bottom surface of a waved pattern, a cutter part formed along an outside edge of the outsole forming cavity, and a surplus outsole-collecting groove formed along the cutter part while being spaced apart from the cutter part by a predetermined gap; and an intermediate plate part including an outer cover made of aluminum, a cutter part protector positioned in the outer cover and made of a material having lower hardness than that of the outer cover, and an elastic resin part positioned below the cutter part protector and made of an elastic material.

Preferably, the cutter part protector is made of copper, zinc, lead, or aluminum having low hardness. In addition, the elastic resin part comprises a silicone resin, and further comprises metal powders.

In addition, according to a second embodiment of the present invention, there is provided a mold for producing a shoe-sole comprising an outsole made of a rubber material for use in forming a bottom piece of the shoe-sole and a midsole made of ethylene vinyl acetate for use in forming a middle layer of the shoe-sole integrated together, comprising a mold part made of aluminum and including an upper mold, a middle mold introduced with a midsole material, and a lower mold having an outsole forming cavity with a bottom surface of a waved pattern, a cutter part formed along an outside edge of the outsole forming cavity, and a surplus outsole-collecting groove formed along the cutter part while being spaced apart from the cutter part by a predetermined gap; an intermediate plate mold including an outer cover made of aluminum, and an elastic resin part made of an elastic material and formed to perforate a middle portion of the outer cover; and a sheet part having an empty chamber at a portion corresponding to the outsole forming cavity and positioned between the intermediate plate mold and the lower mold

Preferably, the lower mold of the mold part is higher in hardness than that of the outer cover of the intermediate plate mold Also, the elastic resin part comprises a silicone resin, and further comprises metal powders Further, the lower mold of the mold part further comprises an air passage formed at one side of the lower mold to communicate the inside of the lower mold with the outside thereof

Thereby, the outsole and the midsole can be integratedly formed by use of a single aluminum mold having an elastic resin part, a cutter part protector having low hardness and a lower mold having high hardness, while the mold is prevented from breaking

Brief Description of the Drawings

The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which

FIG 1 is a perspective view illustrating a shoe,

FIG 2 is a sectional view illustrating a conventional mold for preparing a midsole,

FIG 3 is a view illustrating a lower mold of a mold according to a primary embodiment of the present invention,

FIG 4 is a view illustrating an intermediate plate part of the mold according to the primary embodiment,

FIG 5 is a view illustrating a process of preparing the intermediate plate part, FIG 6 is a view illustrating a process of preparing an outsole by use of the mold according to the primary embodiment;

FIG. 7 is a view illustrating a process of producing a shoe-sole by use of the mold according to the primary embodiment;

FIG. 8 is a sectional view illustrating an intermediate plate part and a lower mold of a mold according to a second embodiment of the present invention; and

FIG. 9 is a view illustrating a process of producing the shoe-sole by use of the mold according to the second embodiment.

Best Mode for Carrying Out the Invention

Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components.

A mold for producing a shoe-sole of the present invention comprises a mold part including an upper mold, a middle mold and a lower mold, and an intermediate plate part.

As for the mold part, the upper mold and the middle mold are the same as conventional molds.

FIG. 3 illustrates the lower mold of a mold according to a primary embodiment of the present invention. As shown in FIG. 3, the lower mold 100 includes an outsole forming cavity 110 having a waved pattern at a bottom surface thereof, for formation of a bottom surface pattern of a shoe. An outside edge of the outsole forming cavity 110 is sharpened to form a cutter part 112. Such a cutter part 112 functions to cut a surplus end remaining along an edge of a formed outsole, resulting in trimming the outsole. That is, the outsole is formed by use of a non- vulcanized rubber, and then it is adhered to a midsole at the same time as the midsole is formed. As such, the surplus end of the formed outsole is cut by the cutter part 112. Thereby, only the outsole obtained by the outsole forming cavity 110 is adhered to a lower surface of the midsole. Thus, an additional trimming process of the outsole is not required. Accordingly, since a post-treatment process using a hot wire as in conventional techniques to trim the outsole is not performed, the number of production processes and the generation rate of inferior goods are decreased. Further, a groove 120 for collecting the surplus end of the outsole cut by the cutter part 112 is formed along the cutter part 112 while being spaced apart from the cutter part 112 by a predetermined gap. Thereby, the outsole may be easily prepared.

Referring to FIGs. 4 and 5, there is shown an intermediate plate part 200 of the mold according to the primary embodiment of the present invention, having the same function as a conventional intermediate plate. Typically, an intermediate plate, which is made of aluminum, functions as a cover of the lower mold on which an outsole material comprising the non-vulcanized rubber is placed. However, when the outsole is formed by means of such a conventional aluminum intermediate plate, pressure is directly applied to the aluminum intermediate plate while an upper press body is moved downwards, by which the waved pattern of the outsole forming cavity 110 of the lower mold 100 is easily broken. Thus, in the present invention, the intermediate plate part 200 having further improved functions is used. The inventive plate part 200 functions as the cover as in conventional cases, and additionally acts to evenly distribute the pressure generated by the downward movement of the upper press body, finally to decrease pressure applied to the waved pattern of the outsole forming cavity 110.

Hence, the intermediate plate part 200 of the present invention is characterized by having no deterioration by heat transfened to form the outsole, elastically changing a shape thereof under external pressure, and having rapid heat transfer. Thus, as shown in FIGs. 4 and 5, the intermediate plate part 200 comprises an outer cover 210, a cutter part protector 220, and an elastic resin part 230. The outer cover 210 is made of an aluminum material, to have heat conductivity and withstand pressure by downward movement of the upper press body. That is, the outer cover 210 of the intermediate plate part 200 should be high in heat conductivity for good heat transfer to the lower mold 100, and should be sufficiently pressure resistant, upon downward movement of the upper press body. For this, the outer cover is formed of aluminum, and comprises a plurality of gate holes 212 and an internal empty chamber 214.

In such an empty chamber 214, the cutter part protector 220 is positioned, made of a material having hardness lower than that of aluminum. The material constituting the cutter part protector 220 is exemplified by hard synthetic resins, copper or lead, having lower hardness than that of aluminum. Further, the cutter part protector 220 may be formed of aluminum, provided that having hardness lower than that of the outer cover 210 made of aluminum. In other words, the outer cover 210 has 60-80 db of hardness, while the cutter part protector 220 has 40 db or less of hardness. The reason why hardness of the protector 220 must be lower than that of the outer cover 210 is that the cutter part 112 of the outsole forming cavity 110 is prevented from breaking. Upon repeated movement of the upper press body, since a surface of the cutter part protector 220 having lower hardness than that of the cutter part 112 comes into contact with the cutter part 112, the cutter part 112 is prevented from breakage. Further, such a cutter part protector 220 has a plurality of gate holes 222 at positions corresponding to the gate holes 212 of the outer cover 210.

Further, the elastic resin part 230, which is made of a heat resistant resin having elasticity, is provided below the cutter part protector 220. Upon formation of the outsole, the elastic resin part 230 functions to compress the non-vulcanized rubber sheet while coming into surface contact with the non-vulcanized rubber sheet. Such an elastic resin part 230 has elasticity to prevent breakage of the waved pattern of the outsole forming cavity 110, with no deterioration by heat transferred to form the outsole. The elastic resin part 230 is preferably formed of a silicone resin, or similar materials. The silicone resin is advantageous in terms of high heat resistance up to 250°C after being cured, and various hardness according to preparation methods. Therefore, the above silicone resin has no heat deterioration at 140- 160°C, and can be maintained in its original shape under 60 kgf/cm³ of pressure applied from the upper press body, thereby obtaining an outsole with a certain shape. In addition, this resin exhibits elasticity under pressure higher than 60 kgf/cm³ and acts to evenly distribute the pressure, consequently removing excessive pressure applied to the waved pattern of the outsole forming cavity 110. Meanwhile, the silicone resin has no heat transfer property, and thus should be mixed with metal powders, such as copper or aluminum, for good heat transfer. Of the above-mentioned metals, the copper powders are very high in heat conductivity, through which the heat is transferred to the outsole.

FIG. 5 illustrates a preparation process of the intermediate plate part 200 of the mold according to the primary embodiment of the present invention. As shown in FIG. 5, the outsole forming cavity 110 of the lower mold 100 is charged with a gypsum core (a) at a predetermined thickness, preferably an outsole thickness. Then, a copper plate as the cutter part protector 220 and an aluminum plate as the outer cover 210 are positioned on the lower mold 100. A silicone liquid is poured into the outsole forming cavity 110 through a plurality of the gate holes 212 and 222 of the outer cover 210 and the cutter part protector 220, to form the elastic resin part 230 having a predetermined shape. When the silicone liquid is completely cured, the intermediate plate part 200 comprising the outer cover 210, the cutter part protector 220 and the elastic resin part 230 is obtained. On the other hand, the cured gypsum core (a) is removed from the outsole forming cavity 110 of the lower mold 100 after the intermediate plate part 200 is obtained. The reason why such a gypsum core (a) is used is that the elastic resin part 230 is maintained in predetermined size and shape. That is, if the silicone liquid is injected in the state of not using the gypsum core (a), the elastic resin part 230 having an equal volume to the outsole forming cavity 1 12 is obtained. In such a case, while the non-vulcanized rubber sheet is vulcanized under the pressure, the pressure applied to the non-vulcanized rubber is too high, resulting in breaking the waved pattern of the outsole forming cavity 112. Thus, the gypsum core (a) is previously formed in the outsole forming cavity 112, whereby the silicone resin part has an outline shape of the outsole, provided that it has a volume exclusive of the volume of the charged gypsum core (a). Consequently, upon performing a drawing process of the non-vulcanized rubber sheet by the upper press body, the waved pattern of the outsole forming cavity 112 is prevented from breakage.

Below, a description will be given of a process of producing the shoe-sole by use of the mold part and the intermediate plate part of the mold according to the primary embodiment of the present invention.

FIG. 6 illustrates a preparation process of the outsole. As shown in FIG. 6, the lower mold 100 is positioned between the upper press body 300 and the lower press body 300 while being fixed to the lower press body 300. In the state of the lower mold 100 being heated, the non-vulcanized rubber sheet (p) is placed on the bottom surface of the outsole forming cavity 110 to cover the cutter part 112 of the outsole forming cavity 1 10, on which the intermediate plate part 200 is placed. By downward movement of the upper press body 300, pressure and high temperature are applied to the intermediate plate part 200 and the lower mold 100, to produce the outsole (p'). As such, the lower mold 100 may be simultaneously subjected to pressure and heat or the lower mold 100 may be preheated and then subjected to pressure. According to compressing and heating processes by the upper and lower press bodies 300, the non- vulcanized rubber sheet (p) comes into close contact with the waved pattern of the outsole forming cavity 110 while being vulcanized, forming the outsole (p'). Meanwhile, an outside edge of the outsole forming cavity 110 is sharpened to form the cutter part 112. Thus, the non-vulcanized rubber sheet (p) positioned on the cutter part 112 is subjected to pressure of the intermediate plate part 200, and a surplus end of the formed outsole (p') is cut by the cutter part 1 12 to trim the outsole (p') and then collected into the groove 120. The non- vulcanized rubber sheet (p) is drawn along the uneven bottom surface of the outsole forming cavity 110 while being vulcanized to form the outsole (p'). Simultaneously, the surplus end of the outsole (p') is cut, whereby an additional trimming process is unnecessary.

Upon the downward movement of the upper press body 300, the outer cover 210 acts to withstand such pressure. That is, the outer cover 210 is made of aluminum having high hardness, and an end thereof is positioned above the lower press body 300, thereby withstanding the whole pressure. The cutter part 112 of the outsole forming cavity 110 is subjected to pressure by a cutter part protector 220 made of a soft material. The cutter part 112 has hardness higher than that of the cutter part protector 220, and thus is not damaged by pressure of the protector 220. The non- vulcanized rubber sheet (p) is subjected to pressure through an elastic resin part 230, and drawn along the uneven bottom surface of the outsole forming cavity 110. Hence, upon the downward movement of the upper press body 300, the elastic resin part 230 functions to transfer pressure and heat to the non- vulcanized rubber sheet (p), which is then elastically subjected to pressure and vulcanized. Moreover, since the elastic resin part 230 is formed to have a volume exclusive of a volume of the outsole (p') in the outsole forming cavity 110, the waved pattern of the outsole forming cavity 110 is prevented from breaking. The elastic resin part 230 of the intermediate plate part 200 is made of elastic silicone resin and evenly distributes the pressure applied from the upper press body 300. Upon the downward movement of the upper press body 300, the non-vulcanized rubber sheet (p) is drawn along the uneven bottom surface of the heated outsole forming cavity 110 while being vulcanized The elastic resin part 230 is elastically expanded and contracted under the pressure by the upper press body 300, and thus acts to decrease pressure directly applied to the waved pattern on the lower mold 100 Thereby, the above waved pattern can be prevented from breaking due to excessive pressure As for heat transfer required to form the outsole, heat is transferred from the lower press body 300 to the non- vulcanized rubber sheet (p) placed on the outsole forming cavity 110 through a lower surface of the lower aluminum mold 100 On the other hand, heat by the upper press body 300 is transferred to the non-vulcanized rubber sheet (p) through the outer cover 210 and the cutter part protector 220 of the intermediate plate part 200 When the elastic resin part 230 is mixed with metal powders, heat may be transferred to the non- vulcanized rubber sheet (p) through such an elastic resin part 230

After the outsole (p') is formed, the upper press body 300 is moved upwards The intermediate plate part 200 is removed, along with the surplus end of the non-vulcanized rubber sheet (p) cut by the cutter part 112 of the outsole forming cavity 110 and collected into the groove 120 Thus, only the vulcanized outsole (p') remains in the outsole forming cavity

110 The removed intermediate plate part 200 is stored in an additional chamber to maintain the temperature of the plate part 200 at a predetermined level This is because the intermediate plate part 200 is again used in the state of heat being maintained to improve heat transfer efficiency, thereby easily bringing the non-vulcanized rubber sheet (p) into contact with the waved pattern of the outsole forming cavity 110 and easily cutting the surplus end of the formed outsole

Thereafter, the middle mold is positioned on the above-mentioned lower mold and is introduced with a midsole material, on which the upper mold is assembled By use of the upper and lower press bodies, pressure and heat are transfened to the mold of the present invention, thereby simultaneously molding the midsole material and adhering the molded midsole to the outsole, thus obtaining a shoe-sole. Below, the molding process of the midsole and the adhering process of the midsole and the outsole are described.

FIG. 7 illustrates a preparation process of the shoe-sole by use of the mold according to the primary embodiment of the present invention. As shown in FIG. 7, a midsole material (q) is introduced into a middle mold 130. As such, a molded midsole (q') is adhered to the outsole (p') formed in the lower mold 100, by means of various methods. For example, an adhesive may be simply coated on the upper surface of the outsole (p'), after which the midsole material (q) may be introduced into the middle mold 130. Alternatively, an adhering medium may be additionally used at desired positions. That is, a transparent sheet, preferably, a transparent film sheet made of E.V.A. as the same material to the midsole (q'), may be coated with an adhesive at a lower surface thereof, and then may be positioned on the upper surface of the outsole (p'). When the transparent film sheet made of E.V.A. material is used, adhesion may be further increased. Since the transparent film sheet made of E.V.A. is formed of the same material as the midsole material (q), adhesion between the film sheet and the molded midsole (q') is further increased. As well, the transparent sheet is melted by heat applied upon preparation of the midsole, and vulcanized with coming into close contact with an upper surface of the non-vulcanized rubber sheet, resulting in high adhesion strength between the lower surface of the midsole and the upper surface of the outsole.

In case the transparent film sheet made of E.V.A. is used as the adhering medium, it may be integrated with the outsole material upon forming the outsole (p'). That is, when the non-vulcanized rubber (p) is cut to a sheet shape, the transparent film sheet is positioned on the non-vulcanized rubber sheet (p) and cut together. After the non-vulcanized rubber (p) provided with the transparent film sheet is positioned on the lower mold 100, it is vulcanized by heat applied upon preparation of the outsole, to form the outsole (p'). Simultaneously, the transparent sheet is melted and adhered to the upper surface of the vulcanized outsole (p'). Then, the middle mold 130 is mounted, into which the midsole material (q) is introduced. Upon the downward movement of the upper press body, while the introduced midsole material (q) is drawn along the upper surface of the outsole (p'), the transparent sheet as a thermoplastic resin is again melted by the heat applied for molding the midsole and adhered to a lower surface of the midsole (q'), thereby adhering the midsole to the outsole.

The adhering process is performed by coating the adhesive on the outsole or by using the adhering medium such as the transparent film sheet. The midsole material (q) is introduced into the middle mold 130, on which the upper mold 150, which is fixed to the upper press body 300, is positioned. While the upper press body 300 is downwardly moved, the mold of the present invention is subjected to pressure. In such a case, heat required for molding the midsole is transferred to the upper mold 150 and the middle mold 130. The molding process of the midsole by compression and heating is known, so a detailed description therefore is omitted.

Meanwhile, the outsole (p') is formed, and only the midsole material (q) may be used, without use of an additional adhesive, to produce the midsole. If so, because the same mold is used, the outsole and the midsole having respective accurate dimensions can be produced. Conventionally, a midsole mold and an outsole mold have been separately prepared and used. Thus, conventional techniques for preparing midsoles and outsoles suffer from different elasticity properties of the outsole mold made of iron and the midsole mold made of aluminum, and difficult production of the shoe-sole having accurate dimensions due to dimension calculation errors by producers. However, in the present invention, the midsole as well as the outsole are produced only in the one mold made of aluminum, thus avoiding dimensional inferiority.

Thereafter, the upper press body is moved upwards and the produced shoe-sole is removed from the mold. Then, another non-vulcanized rubber sheet is positioned on the lower mold, on which the intermediate plate part having a predetermined temperature is placed, and the same processes as mentioned above are repeatedly performed, resulting in obtaining shoe-soles

FIG 8 illustrates an intermediate plate part and a lower mold of a mold according to a second embodiment of the present invention, having a structure thereof different from that of the primary embodiment

As shown in FIG 8, an intermediate plate part 200' comprises a separate intermediate plate mold 200' and a sheet part 230' As for the intermediate plate mold 200', the plate mold 200' comprises an outer cover 210' and an elastic resin part 220' Functions of the outer cover 210' and the elastic resin part 220' are the same as in the primary embodiment Although the elastic resin part 220' may be positioned below the outer cover 210' as in the primary embodiment, it may be formed to perforate a middle portion of the outer cover 210' as shown in FIG 8 In addition, a lower mold 100' is enhanced in strength so that the elastic resin part 220' of the intermediate plate mold 200' functions as a cutter part protector As described in the above primary embodiment, a cutter part protector functions to minimize effects of pressure or heat on the cutter part and the waved pattern of the lower mold, thereby preventing the cutter part and the waved pattern from breaking However, in the present embodiment, strength of the lower mold 100' itself is enhanced, and the above problem is solved According -to the present invention, it is preferred that the lower mold 100' has strength increased by 30% over that of a middle mold Such enhancement of strength is achieved by heat treatment following preparation of the lower mold 100' Therefore, in this embodiment, a heat treatment process of the lower mold 100' is performed one more, whereby strength of the lower mold 100' itself is enhanced Thus, the mold according to the second embodiment of the present invention does not additionally require a cutter part protector Further, the sheet part 230' is made of aluminum and has an empty chamber at a portion corresponding to an outsole forming cavity 110' formed on the lower mold 100' The sheet part 230' is variable in thickness, depending on the thickness of the formed outsole, with the aim of controlling thickness of the outsole and trimming the outsole As shown in FIG 8, the sheet part 230' is positioned on the lower mold 100' An inner edge of the sheet part 230' comes into contact with a cutter part 112' formed by sharpening the outside edge of the outsole forming cavity 110' of the lower mold 100' Upon a downward movement of an upper press body, the sheet part 230' comes into surface contact with the cutter part 112', thus easily cutting a surplus end of the outsole to trim the outsole. In addition, since the sheet part 230' functions to decrease pressure applied to the lower mold 100' from the upper press body according to increase of thickness thereof, thus controlling the thickness of the outsole Upon compression by the press, the sheet part 230' made of aluminum, which is positioned between the middle mold 200' and the lower mold 100', may withstand such pressure That is, as thickness of the sheet part 230' increases, the pressure applied to the non- vulcanized rubber sheet positioned on the outsole forming cavity

110' of the lower mold 100' is decreased Thus, the thickness of the outsole may be formed as thick as that of the sheet part 230' Such thickness control of the outsole provides various advantages

For instance, an outsole having two colors can be easily formed as shown in FIG 9 In order to produce a two-colored outsole, an outsole piece (a) having a specific color is previously prepared at a middle portion of an outsole forming cavity Preparation of the outsole piece (a) is the same as that of conventional outsoles, provided that a second cutter part 112a' is formed around the outsole piece (a) to cut a surplus outsole piece Then, a non- vulcanized rubber sheet (p) having another color is positioned on the lower mold 100', to form an outsole (p') As such, the outsole (p') is two-folded at a portion formed with the outsole piece (a), and thickness of the portion formed with the outsole piece (a) is two times to that of the other portions of the outsole forming cavity. In the absence of the sheet part 230', the outsole (p') is cut by the second cutter part 112a' of the outsole piece (a), generating inferior goods. However, in the presence of the sheet part 230', thickness of the outsole (p') is increased by that of the sheet part 230'. Thus, it is possible to form the outsole (p'), regardless of the second cutter part 112a' of the outsole piece (a). As well, in the case of specific purpose shoes, such as mountain-climbing boots, the outsole (p') may become thick because thickness of the outsole (p') is controlled by the sheet part 230'.

Furthermore, as shown in FIG. 8, the lower mold 100' is provided with an air passage 100a'. The air passage 100a' is formed at one side of the lower mold 100', one end of which is in communication with an opened inside of the mold 100', the other end of which is connected to a vacuum pump (not shown in this figure). By operation of the vacuum pump, air of a space defined on the mold 100' is exhausted to the outside and the space is under vacuum. In order to improve adhesion between the midsole and the outsole, the above air passage 100a' is used. The midsole on the middle mold and the outsole (p') on the lower mold 100' are not adhered well due to air present therebetween. That is, attributable to air remaining between the lower surface of the midsole and the upper surface of the outsole (p'), a plurality of pores are formed at an adhering portion, causing poor adhesion. Thus, the air passage 100a' is required to completely exhaust the remaining air so as to prevent poor adhesion.

Such an air passage 100a' which is not shown in the primary embodiment may be applied to the primary embodiment.

Thereafter, a producing process of a shoe-sole is simply described by use of the mold according to the second embodiment of the present invention. As shown in FIG. 9, a non-vulcanized rubber sheet (p) is positioned on the lower mold 100', on which the sheet part 230' and the intermediate plate mold 200' are placed. As such, strength of the lower mold 100' is higher than that of the outer cover 210' of the intermediate plate mold 200'.

The outsole (p') is formed in the same manner as in the primary embodiment, under pressure and heat by a downward movement of an upper press body 300. As such, the sheet part 230', which is subjected to pressure applied from the upper press body 300, acts to easily cut a surplus end of the outsole (p') while bringing a lower surface of the sheet part 230' into contact with the cutter part 112' formed along an outside edge of the lower mold 100'. In addition, the sheet part 230' which is variable in thickness, functions to control thickness of the outsole (p') and to produce the outsole (p') having various colors.

After the outsole (p') is formed, the sheet part 230' and the intermediate plate mold 200' are removed from the mold of the present invention. A middle mold 130 provided with a midsole material (q) is positioned on the lower mold 100' having the formed outsole (p'). Further, an upper mold 150 is placed on the middle mold 130, and the three molds are positioned between the upper and lower press bodies 300.

Immediately before the molds are compressed by a downward movement of the upper press body 300, a vacuum pump connected to the air passage 100a' which is formed through the lower mold 100' is operated. Operation of the vacuum pump results in exhausting the air remaining between an upper surface of the outsole (p') of the lower mold 100a and a lower surface of the midsole material (q) of the middle mold 130. Then, complete close contact between the midsole and the outsole is achieved by the movement of the upper press body 300. Thereafter, the midsole (q') is molded and adhered to the outsole (p') at the same time, through hot and cool heat transfer by the upper and lower press bodies 300. Industrial Applicability

As described above, the present invention provides a mold for producing a shoe- sole, characterized in that a midsole and an outsole are produced in a single aluminum mold, and the mold is prevented from breakage by means of an intermediate plate part made of an elastic material having high hardness and good heat conductivity.

Upon formation of the outsole, a surplus end of the outsole is removed, thus requiring no additional trimming process of the outsole. Thereby, the mold of the present invention is advantageous in terms of decrease in the production of inferior shoe-soles and a reduced number of production processes.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A mold for producing a shoe-sole comprising an outsole made of a rubber material for use in forming a bottom piece of the shoe-sole and a midsole made of ethylene vinyl acetate for use in forming a middle layer of the shoe-sole integrated together, comprising: a mold part made of aluminum and including an upper mold, a middle mold introduced with a midsole material, and a lower mold, having an outsole forming cavity with a bottom surface of a waved pattern, a cutter part formed along an outside edge of the outsole forming cavity, and a surplus outsole-collecting groove formed along the cutter part while being spaced apart from the cutter part by a predetermined gap; and an intermediate plate part, including an outer cover made of aluminum, a cutter part protector positioned in the outer cover and made of a material having lower hardness than that of the outer cover, and an elastic resin part positioned below the cutter part protector and made of an elastic material.

2. The mold as defined in claim 1, wherein the cutter part protector is made of copper, zinc, lead, or aluminum having low hardness.

3. The mold as defined in claim 1 or 2, wherein the elastic resin part comprises a silicone resin.

4. The mold as defined in claim 3, wherein the elastic resin part further comprises metal powders.

5. A mold for producing a shoe-sole comprising an outsole made of a rubber material for use in forming a bottom piece of the shoe-sole and a midsole made of ethylene vinyl acetate for use in forming a middle layer of the shoe-sole integrated together, comprising: a mold part made of aluminum and including an upper mold, a middle mold introduced with a midsole material, and a lower mold, having an outsole forming cavity with a bottom surface of a waved pattern, a cutter part formed along an outside edge of the outsole forming cavity, and a surplus outsole-collecting groove formed along the cutter part while being spaced apart from the cutter part by a predetermined gap; an intermediate plate mold, including an outer cover made of aluminum, and an elastic resin part made of an elastic material and formed to perforate a middle portion of the outer cover; and a sheet part having an empty chamber at a portion corresponding to the outsole forming cavity and positioned between the intermediate plate mold and the lower mold.

6. The mold as defined in claim 5, wherein the lower mold of the mold part is higher in hardness than that of the outer cover of the intermediate plate mold.

7. The mold as defined in claim 5 or 6, wherein the elastic resin part comprises a silicone resin.

8. The mold as defined in claim 7, wherein the elastic resin part further comprises metal powders.

9. The mold as defined in claim 1 or 5, wherein the lower mold of the mold part further comprises an air passage formed at one side of the lower mold to communicate the inside of the lower mold with the outside thereof.