WO2001076843A1

WO2001076843A1 - Molding device for manufacturing midsole and insole of shoes

Info

Publication number: WO2001076843A1
Application number: PCT/KR2001/000193
Authority: WO
Inventors: Woo Won Lee
Original assignee: Woo Won Lee
Priority date: 2000-03-31
Filing date: 2001-02-09
Publication date: 2001-10-18
Also published as: AU3612301A; KR200195276Y1

Abstract

A mold assembly for shaping midsoles and insoles is disclosed. The mold assembly includes: outer mold sections constituting casings of the upper and the lower mold parts and having recesses at their inner surfaces; inner mold sections attached to the recessed surface of the outer mold sections and having at their inner surfaces a protrusion and a recess of a desired shape; and heating and cooling medium passages formed at the outer mold sections and communicated to the heating and cooling medium cavities to allaw external heating or cooling medium to be supplied to and withdrawn from the heating and cooling medium cavities, Therefore, the present invention affords considerable shortening of production time, improved productivity, energy saving and safe process conditions.

Description

MOLDING DEVICE FOR MANUFACTURING MIDSOLE AND INSOLE OF SHOES

Technical Field

The present invention relates a mold assembly for shaping midsoles and insoles of shoes, in general, and more particularly to a mold assembly for shaping midsoles and insoles of a shoe which is capable of simplifying its mold manufacturing process by improving a structure of its mold, thereby reducing cost required for manufacturing its mold, and is further capable of shortening time required for manufacturing midsoles and insoles by sequentially carrying out heating operation and cooling operation with the same mold, thereby improving productivity and reducing manufacturing cost.

Background Art

In recent times, ^'many types of shoes having various designs are manufactured according to improvement of standard of living and various desires of customers. Special shoes having various functions are also commercially manufactured. It will be appreciated that many such types of shoes are much alike in terms of their structures. That is, commonly used shoes comprise a bottom piece, an upper attached to an edge of the bottom piece, and an insole disposed on the bottom piece and within the upper. The bottom piece comprises an outsole constituting a bottom surface of the bottom piece, and a midsole.

The insole is made from a thin and stiff sheet material, and disposed beneath a shoe bed in case of an athletic shoe. The insole is manufactured in such a way that a sheet material is inserted in a recess of a mold having a shape similar to a shape of a foot, and it is compressed by a pressing machine to have a curvature similar to a foot. Such a process for shaping an insole is analogous to a process for shaping a midsole as will be described later, and a structure of a mold used therefor is also analogous to that of a mold for midsole.

As described above, various types of shoes can be manufactured depending to choices of a structure and material of a shoe sole and an upper. For example, in case of being used as jogging shoes, material constituting a shoe sole and an upper must have shock absorption ability and must be made of light material. In case of being used as shoe requiring abrasion resistance and slip resistance, an outsole attached to a bottom of a shoe must be made of rubber material. In this way, a style, function and price of shoes are determined according to choices of structures, shapes and material of a midsole and an outsole of shoe.

Such a shoe sole is manufactured in such a way that an outsole is made separately from a midsole and then attached to a bottom surface of the midsole. Alternatively, a shoe sole may be composed of only a midsole. The choice of process of shaping a shoe sole is determined according to material constituting a shoe sole. Material constituting a shoe sole and process for shaping a shoe sole from the material will be briefly described as follows.

An outsole is mostly made of rubber material so as to achieve its main function, i.e., slip resistance, abrasion resistance, improvement in its friction force on the ground. In process for manufacturing such an outsole, a rubber sheet, which is cut into a predetermined shape, is forcibly inserted into a recess of a mold. At this point, since the recess of the mold is formed with an outsole shaping surface on which a predetermined shape is carved, the produced outsole is formed at its bottom surface with the predetermined shape by being compressed by a certain pressure at high temperature after the insertion of the rubber sheet into the recess of the mold. Though a midsole can be commonly made of one of various materials, it is chiefly made from synthetic resin sheet consisting of foamed EVA compound. A process for manufacturing a midsole consisting of the EVA compound, which is also referred to as an EVA midsole, will be now described with reference to the accompanying drawings.

A foamed resin sheet is prepared as an EVA midsole. The foamed sheet is cut into a predetermined shape, which is a little larger than that of a desired final midsole. The ^" cut foamed sheet is forcibly inserted into a recess of a lower mold part, which is light and excellent in thermal conduction, as shown in Fig. 1. Fig._ 1 is a perspective view of mold for EVA midsole with an upper mold part being opened. As shown in the drawing, the mold for EVA midsole comprises an upper mold part 1 and a lower mold part 3. The upper mold part 3 is provided with a shaping recess 5 for receiving the cut foamed sheet. The upper mold part 1 is provided at its lower surface with a protrusion 7 for pressing the foamed sheet inserted in the lower mold part 3, and is hingedly connected to the lower mold part 3. Therefore, when the mold assembly 10 is required to be opened, the opening of the mold assembly 10 is easily performed by opening only the upper mold part 1. After the foamed sheet is inserted into the shaping recess 5 of the lower mold part 3, the upper mold part 1 is closed and the mold assembly 10 is subjected to high pressure and high temperature. For applying high pressure and high temperature to the mold assembly 10, the mold assembly 10 is fed into a hot pressing machine as shown in Fig. 2.

The hot pressing machine shown in Fig. 2 contains four heater plates 11 so that four mold assemblies 10 are subjected to high pressure and high temperature all at once. Fig. 2 is a front view showing four mold assemblies 10 fed between the heater plates 11. Referring to Fig. 2, the hot pressing machine is provided at its lowermost portion with a cylinder rod 13. Guide bars 15 are mounted above the cylinder rod 13, and four heater plates 11 are supported on the guide bars 15 and are spaced at certain intervals. Therefore, -spaces for receiving the mold assemblies 10 are provided between the four heater plates 11.

Upon operating the hot pressing machine in which the mold assemblies 10 having the foamed sheets therein are fed between the heater plates 11, the mold assemblies 10 are pressed by rsising of the cylinder rod 13 as shown in Fig. 3. Fig. 3 is a front view showing the hot pressing machine in which the molds 13 are pressed by the hot pressing machine. Referring to Fig. 3, the cylinder rod 13 of the hot pressing machine is extended upwardly to raise the heater plates 11 so as to press the mold assemblies 10. By compression of the mold assemblies 10, the mold assemblies 10 come into close contact with the heater plates 11, and are heated by heat generated from the heater plates 11. When high pressure and high temperature are applied to the mold assemblies 10, the foamed midsole sheets in the mold assemblies 10 are further expanded by high temperature and thus are closely filled in the shaping recesses of the mold assemblies 10. Therefore, the foamed midsole sheets are molded into shapes corresponding* to shapes of the shaping recesses of the mold assemblies 10. After the condition shown in Fig. 3 is maintained for 8 - 12 minutes such that the mold assemblies 10 are sufficiently subjected to the high pressure and the high temperature, the mold assemblies 10 are subjected to cooling operation. The cooling operation of the molds are carried out using a cool pressing machine (not shown) which has a structure similar to the hot pressing machine shown in Fig. 2 and is provided with cooling plates in place of the heater plates 11. After the mold assemblies 10 are transferred to the cooling pressing machine, the mold assemblies 10 come into close contact with the cooling plates by activation of the cooling pressing machine, thereby causing the mold assemblies 10 to-be quickly cooled. The cooling operation of the mold assemblies 10 is maintained for 8 - 12 minutes to achieve complete cooling. Thereafter, the mold assemblies 10 are taken out of the cooling pressing machine. Then, the upper mold parts 1 of the mold assemblies 10 are opened and the shaped midsoles are removed from the shaping recess 5 of the lower mold parts 3. After such a process, the manufacture of the EVA midsole is completed. The EVA midsole manufactured by the above-mentioned process is excellent in terms of light weight and elasticity, and has no risk of discoloration as compared with midsole made of some another material. However, the above-mentioned process for manufacturing a midsole has disadvantages in that its productivity is poor, and manufacturing process of the mold assembly 10 is difficult and expensive.

In such a conventional process for shaping a midsole, the mold assembly 10 is heated and cooled from its outside by using the heater plates 11 and the cooling plates. Each of the mold assemblies 10 is an aluminum mold having a size of width 25 cm x length 30 cm x height 60 - 80 mm. Since the mold assemblies 10 are subjected to heat from the external heater plates, heat loss of the molds is increased. Therefore, considerable time is required until heat from the heater plates reaches the foamed midsole sheet disposed in the center of the mold assemblies 10. In case of cooling of the mold assemblies 10, considerable time is also required because the molds are cooled by external cooling plates. Therefore, though varying according to type of products, the conventional process can produce at most 40 - 50 pairs of shoes per one mold in 24 hours. That is, the conventional process has poor productivity. Furthermore, since heating and cooling of the molds requires a long time period, energy consumption is also increased.

To prevent such reduction of productivity, the hot pressing machine or the cool pressing machine must be equipped with four mold assemblies 10, and must use them all at once. In this way, since the prior art process requires a plurality of mold assemblies 10, an extended time period and high production cost are required to prepare the molds. Furthermore, the prior art process for manufacturing midsoles has a disadvantage in that the hot and heavy molds ranging from 15kg to 20kg must be manually transferred from the hot pressing machine to the cool pressing machine.

As mentioned above, a hot pressing machine and a cool pressing machine are necessary to heat and quickly cool mold assemblies 10. Therefore, the mold assemblies 10 must be transferred from a work bench to a hot pressing machine, from the hpt pressing machine to a cool pressing machine, and from the cool pressing machine to the work bench as the process progresses. Due to such a troublesome process taking a lot of time and effort, a worker becomes easily tired, and a worker is exposed to safety hazards .

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a mold assembly for a midsole and an insole of a shoe which is capable of sequentially carrying out a heating operation and a cooling operation by improving a structure of its molds, thereby shortening a time required for shaping midsoles and insoles, and improving operational safety.

In order to accomplish the above object, the present invention provides a mold assembly including: an outer mold section constituting a casing of the upper mold part and functioning to be pressed by a pressing machine, the outer mold section of the upper mold part having a recess at its inner surface; an outer mold section constituting a casing of the lower mold part and functioning to be pressed by a pressing machine, the outer mold section of the lower mold part having a recess at its inner surface; an inner mold section attached to the inner surface of the outer mold section of the upper mold part to be fitted in the recess of the outer mold section of the upper mold part so as to define a heating and cooling medium cavity therebetween, and having at its inner surface a protrusion of desired shape; an inner mold section attached to the inner surface of the outer mold section of the lower mold part to be fitted in the recess of the outer mold section of the lower mold part so as to define a heating and cooling medium cavity therebetween, and having at its inner surface a recess of desired shape; _t and heating and cooling medium passages formed at the outer mold sections of the upper and the lower mold parts and communicated to the heating and cooling medium cavity of the upper and the lower mold part, such tehat external heating or cooling medium is supplied to and withdrawn from the heating and_, cooling medium cavities of the upper and the lower mold parts therethrough to heat or cool the inner mold sections.

The inner mold section of the lower mold part preferably includes a plurality of air vents formed at corner portions of the shaping recess thereof to discharge air existing therein during shaping operation therethrough, and air venting elements for collecting air discharged through the air vents and discharging the air to outside of the outer mold section of the lower mold part.

The heating and cooling medium cavities of the upper mold part and the lower mold part are preferably communicated with each other such that heating or cooling medium supplied to one of the cavities of the upper and the lower mold parts is supplied to the other of the cavities through the communicating portions .

Therefore, the mold assembly of the present invention has advantages in that it is capable of sequentially carrying out a heating operation and a cooling operation by improving a structure of its molds, thereby shortening a time required for shaping midsoles and insoles resulting in improvement of productivity, and improvement of operational safety.

Brief Description of the Drawings

Fig. 1 is a perspective view of a prior art mold assembly for shaping midsoles; Fig. 2 is a front view of a pressing machine in which the mold assembly of Fig. 1 is placed;

Fig. 3 is a front view of the pressing machine of Fig. 2, which is operated to press the mold assembly; Fig. 4 is a perspective view of a mold- assembly according to an embodiment of the invention;

Fig. 5 is a cross-sectional view showing the fabricated mold assembly of Fig. 4 and its partially enlarged cross- sectional view; Fig. 6 is an exploded perspective view of the mold assembly of Fig. 4;

Fig. 7 is a cross-sectional view showing another embodiment of a heating and cooling medium cavity of the invention; and Fig. 8 is a perspective view showing further another embodiment of a^' heating and cooling medium cavity of the invention.

Best Mode for Carrying Out the Invention

Reference now should be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. As shown in Figs. 4 and 5, a mold assembly for shaping a midsole and an insole of shoe according to the present invention comprises an upper mold part 40 and a lower mold part 50. The upper mold part 40 includes an outer mold section 31 constituting aη upper surface of the upper mold part 40, an inner mold section 33 constituting a shaping surface and having at its lower surface shoe-shaped protrusions 37, a heating and cooling medium receiving cavity 51* provided between the outer mold section 31 and the inner mold section 33, and heating and cooling medium passages 35 communicated to the heating and cooling medium receiving cavity 51' and intended to supply heating steam and cooling water to the heating and cooling medium receiving cavity 51' . The lower mold part 50 includes an inner mold section 43 constituting a shaping surface and having shaping recesses 47 to receive the shaping protrusions 37, an outer mold section 41 coupled to a lower surface of the inner mold section 43, a heating and cooling medium receiving cavities 51 provided between the inner mold section 43 and the outer mold section 41, and heating and cooling medium passages 45 communicated to the heating and cooling medium receiving cavity 51 and intended to supply heating steam and cooling water to the heating and cooling medium receiving cavity 51. The outer mold section 31 of the upper mold part 40 constitutes a casing of the upper mold part 40 and also serves as a pressing surface. The outer mold section 31 is made from a rectangular or an elliptical sheet of steel, aluminum or the like. The recess including the heating and cooling medium cavity of the upper mold part 31 is designed to have a size, which -^'is a little larger than the inner mold section 33, to allow the 'inner mold section to be fitted into the recess of the outer mold section 31 of the upper mold part 40. When the inner mold section 33 is attached to the outer mold section 31 of the upper mold part 40, the heating and cooling medium cavity 51 is defined between the outer mold section 31 and the inner mold section 33, thereby allowing heating and cooling mediums to be supplied thereto. The outer mold section 31 of the upper mold part 40 is preferably applied at its outer surface with resin material or heat insulating material so that heat or cold generated from the heating steam or the cooling water supplied to the heating and cooling medium cavity cannot be radiated from the outer surface of the outer mold section 31. The inner mold section 33 of the upper mold part 40 is disposed on a midsole sheet to press the midsole sheet and is provided at its lower surface with the foot-shaped shaping protrusions 37. The inner mold section 33 is intended to endure pressure of the heating steam or pressure of the pressing machine, and is attached to a center portion of the lower surface of the outer mold section 31. Packing material (not shown) is attached to contact portions between the outer mold section 31 and the inner mold section 33 so that the heating steam or the cooling water supplied through the heating and cooling medium passages 35 from an external source cannot leak through the contact portions. In the present embodiment, the upper mold part 40 is constructed to be divided the outer mold section 31 and the inner mold section 33. Hence/ when it is required to manufacture another model of midsole, the existing outer mold section 31 can be used as it is with only the inner mold section 33 being replaced. Therefore, even when a fresh mold must be manufactured, cost and time required to manufacture the outer mold section can be saved, thereby reducing its production cost and its manufacturing time. Since the lower mold part 50 is also constructed to be divided into the outer mold section 41 and the inner mold section 43, production cost for manufacturing the mold can be saved. The heating and cooling medium receiving cavity 51' of the upper mold part 40 is designed to serve as a flow channel as well as a cavity containing heating and cooling medium, and is. defined by the outer mold section 31 and the inner mold section 33 of the upper mold part 40.

The heating and cooling medium receiving cavity 51' is first supplied with heating steam to heat the inner mold section 33 to cause foamed midsole sheets disposed in the inner mold section 33 to be heated, -and then supplied with cooling water to cool the foamed midsole sheets. The heating steam and the cooling water are supplied to the heating and cooling medium cavity 51' through the heating and cooling medium passages 35. - The heating and cooling medium passages 35 pass through the outer mold section 31 of the upper mold part 40 from its side to the heating and cooling medium cavity 51' . At this point, two heating and cooling medium passages 35 are formed at the upper mold section 31 s©.as to supply the heating and cooling medium to the heating ahd cooling medium cavity 51' and draw the heating and cooling medium from the heating and cooling medium cavity 51' . That is, the heating steam and the cooling water flow into the heating and cooling medium cavity 51' through one of the two heating and cooling medium passages 35 and flow out from the heating and cooling medium cavity 51' through the other of the two heating and cooling medium passages 35. When the mold assembly according to the invention is turned to practical use, the midsole shaping process is preferably automated in such a way that the heating and cooling medium passages 35 are provided at their outside with valves actuated by means of an automatic timer such that the supply of the cooling water is automatically initiated to cool the foamed midsole sheet after the completion of the heating of the mold parts by the valves controlled by the timer. With such a construction, the mold assembly according to the invention enables foamed midsole sheets received therein to be heated and then cooled by means of only one mold assembly. Therefore, the invention has advantages in that it is possible to eliminate inconvenience accompanied by transmission of the mold, and thus to improve safety in operation and working efficiency. The outer mold section 41 of the lower mold part 50 constitutes a casing of the lower mold part 50, and functions to support the inner mold section 43 of the lower mold part 50. Between the outer mold section' 41 and the inner mold section 4-3^* is formed the heating and cooling medium receiving cavity 51. Fig. 6 is an exploded view showing the lower mold 50. Referring to the drawing, an upper surface of the outer mold section 41 is provided at its upper surface with a recess including the heating and cooling medium cavity, which is a little larger than a size of the inner mold section 43, so as to allow the inner mold section 43 to. be fitted. The outer mold section' 41 is also formed at its side with the heating and cooling medium passages 45. As is the case with the outer mold section 31 of the upper mold part, the outer mold section 41 of the lower mold part 50 is applied at its- outer surface with resin material or heat insulating material, so that heat and cold generated from the heating steam and the cooling water cannot be radiated from the outer surface of the outer mold section 41, thereby reducing energy loss. The outer mold section 41 of the lower mold part 50 is provided with a plurality of outer air vent grooves 41a,^' which are communicated to an air vent grooves 43b of the .inner mold section 43, so that air existing in the shaping recesses 47 can be discharged therethrough during the pressing operation, as shown in the enlarged cross-sectional view of Fig. 5. The inner mold section 43 of the lower mold part 50 is designed to receive midsole sheets to mold them into desired shapes. The inner mold section 43 has the shaping recesses 47, and is attached to an upper surface of the outer mold section 43. Packing material (not shown) is attached to contact portions between the outer mold section 41 and the inner mold section 43 of the lower mold part 50, so that heating steam and cooling water supplied from an external source cannot leak between the outer mold section 41 and the inner mold section 43 under the condition that both of the mold sections are coupled to each other. In addition, the inner mold section 43 is constructed to endure pressure of steam and pressure of the pressing machine during the shaping operation. The inner mold section 43 of the lower mold part 50 comprises the shaping recesses 47 and a plate 43d for supporting the shaping recesses 47, and is fitted in the outer mold 41. In the present embodiment of the invention, the inner mold section 43 is manufactured in such a way that recess walls defining the shaping recesses 47 are made to have a thickness of about 2 - 3 mm by an electroforming technique, and then the recess walls are welded to a metal plate having a desired thickness. That is, the recess walls and the plate are made separately and then they are welded to each other. The reason for manufacturing the inner mold section 43 in this manner is that considerable time is required to form the plate to a desired thickness and boundaries between the plate 43d and the recess walls 47 cannot be formed so favorably when the plate 43d and the recess walls 47 are integrally formed by the electroforming technique. In case that both components are integrally formed, since there is many post-treatment processes even after completion of the electroforming procedure, it is difficult to manufacture the inner mold section 43 and to attain an acceptable mold. As shown in the enlarged cross-sectional view of Fig. 5, each of the shaping recesses 47 of the inner mold section 43 of the lower mold part 50 is provided at its corner as viewed in its cross-section with a plurality of air vents 43a. The air vents 43a function to prevent poor shaping of a midsole by allowing air remaining in the corner portions to be vented outside during a shaping operation of a midsole. Each of the air vents 43a is designed to have a diameter of 0.5 - 1 mm so as to vent even trace quantities of air existing in the inner mold section 43 to the outside. The inner mold section 43 is provided at its outer surface with the air vents 43b communicating with the air vent grooves 43a. With the air vent grooves 43a, air flowed through the air vents 43a is discharged to the outside of the inner mold 43. The inner mold section 43 is provided at its air vent grooves 43b with air vent caps 43c formed separately. The air vent caps 43c function to prevent air flowing in the air vent grooves 43b from leaking into the heating and cooling medium cavity 51. Since the air vent grooves 43b are communicated to the outer air vent grooves 41a of the outer mold section 41 of the lower mold part 50, air flowing in the air vent grooves 43b is discharged to the outside of the outer mold section 41 through the outer air vent grooves 41a. The heating and cooling medium receiving cavity .51 defined between the outer mold section 41 and the inner mold section 43 of the lower mold part 50 functions to supply heating steam and cooling water to the inner mold section 43. That is, the heating and cooling medium receiving cavity 51 contains the heating steam or the cooling water supplied through the heating and cooling medium* passages 45 to heat or cool the inner mold section 43. The^' heating steam is supplied into the heating and cooling medium receiving cavity 51 through the heating and cooling medium passages 45 during a heating operation for heating midsole sheets in the inner mold section 43 while the cooling water is supplied therein during a cooling operation for quickly cooling midsole sheets in the inner mold section 43. As mentioned above, the mold assembly according to the present embodiment is constructed such that its upper mold part 40 and its lower mold part 50 have the heating and cooling medium receiving cavities 51' and 51, respectively, to allow the heating steam or the cooling water to be * circulated therethrough. The'refore, the mold assembly according to the invention is excellent in heat transfer coefficient as compared with the prior art mold assembly 10. That is, the upper and the lower mold parts 40 and 50 of the mold assembly according to the invention are designed to directly heat or cool the surface of the shaping recess 47, differently from the prior art mold assembly intended . to heat or cool the surface of the shaping recess from outside of the mold. Therefore, the mold assembly of the invention is capable of quick heating and cooling of midsole sheets because heat loss is reduced, thereby enabling time period required to heat or cool midsole sheets to be shortened to a large extent. In practice, heating period is considerably shortened to about 3 minutes and cooling period is also considerably shortened to about 4 minutes, as compared with the prior art wherein the heating and the cooling period are 8 - 12 minutes, respectively. Hence, production rate of midsole is improved by about* 250 - 300 %, and it is thus possible to manufacture 120 - 150 pairs of midsoles a day. The above embodiment has been illustrated and described to be constructed such that the upper and the lower mold parts 40 and 50 have the heating and cooling medium passages 35 and 45, respectively, to enable heating steam or cooling water to be supplied therethrough. Alternatively, the mold assembly according to the invention can be embodied in such a manner that the heating and cooling medium receiving cavity 51' of the upper mold part 40 is communicated to the heating and cooling medium cavity 51 of the lower mold part 50 such that heating steam or cooling water can be circulated through the heating and cooling medium cavities 51' and 51 of the upper and the lower mold parts 40 and 50, as shown in Fig. 7. Fig. 7 is a cross-sectional view showing the mold assembly in which a communicating hole 51a is formed at an upper surface of the outer mold section 41 of the lower mold part 50 to be communicated to the heating and cooling medium cavity 51 while a communicating hole 51' a is formed at lower surface of the outer mold section 31 of the upper mold part 40 to be communicated to the heating and cooling medium cavity 51' so that the heating and cooling medium cavities 51' and 51 of the upper and the lower mold parts 40 and 50 are communicated to each other.

In the above-mentioned embodiment of the invention, the heating and cooling medium cavities 51' and 51 are designed to be defined between the outer mold sections 31 and 41 and the inner mold sections 33 and 43, respectively. However, the heating and cooling medium cavities 51' and 51 can be also separately formed differently from the embodiment. For example, a heating and cooling medium cavity 61, which is separately formed, can be attached to a lower surface of the inner mold section 43 of the lower mold part 50, as shown in Fig. 8. Fig. 8 shows the inner mold section 43 beneath which a heating and cooling medium cavity 61 having a square cross section is attached, and the square pole-shaped heating and cooling medium cavity 61 is provided at its side with heating and cooling medium passages communicated thereto.

When the heating and cooling medium cavity 61 is constructed as shown in Fig. 8, the outer mold section is preferably formed with heating and cooling medium passages communicated to the heating and cooling medium passages of the inner mold section to allow external heating and cooling medium to be supplied to the heating and cooling medium cavity therethrough. Though the embodiment of the invention has been heretofore described in relation to only the mold assembly for shaping shoe midsoles, a detailed description of a mold assembly for shaping a shoe insole will be omitted because the mold assembly for insole is substantially the same as the above-mentioned mold assembly for midsole in their structure. In case of shaping of insole, only the inner mold sections for midsole shown in Fig. 4 may be replaced with inner mold sections for insole.

Industrial Applicability

As described above, the present invention provides a mold assembly for shaping midsoles and insoles which comprises an upper mold part and a lower mold part, each of the mold parts being composed of an inner mold section and an outer mold section, and having a heating and cooling medium cavity between the inner mold section and the outer mold section and heating and cooling medium passages communicated to the heating and cooling medium cavity, thereby allowing heating medium and cooling medium to come into close contact with the inner mold sections. Therefore, the mold assembly according to the invention has advantages in that heating period and cooling period are considerably shortened to about 3 - 4 minutes without energy loss in case of shaping of midsole and insole, as compared with the prior art, and thus production rate is improved by about 250 - 300 % .

Furthermore, since a heating operation and^' a cooling operation are carried out in one mold assembly, it is possible to eliminate inconvenience owing to transfer of a mold assembly and afford a safe working environment.

Since it is also possible to replace only the inner mold section, production cost of the mold assembly can be reduced even in case of model change of mold assembly. Therefore, the mold assembly according to the invention can be effectively applied in case of shaping of midsoles and insoles of shoes.

Claims

1. A mold assembly for shaping midsols and insoles, which is adapted to receive midsole material or insole material therein and to be subjected to high temperature and high pressure to shape them into a midsole or an insole, the mold assembly including: an outer mold section constituting a casing of the upper mold part and functioning to be pressed by a pressing machine, the outer mold section of the upper mold part having a recess at its inner surface; an outer mold section constituting a casing of the lower mold part and functioning to be pressed by a pressing machine, the outer mold section of the lower mold part having a recess at its inner surface; an inner mold section attached to the inner surface of the outer mold section of the upper mold part to be fitted in the recess of the outer mold section of the upper mold part so as to define a heating and cooling medium cavity therebetween, and having at its inner surface a protrusion of desired shape; an inner mold section attached to the inner surface of the outer mold section of the lower mold part to be fitted in the recess of the outer mold section of the lower mold part so as to define a heating and cooling medium cavity therebetween, and having at its inner surface a recess of desired shape; and heating and cooling medium passages formed at the outer mold sections of the upper and the lower mold parts and communicated to the heating and cooling medium cavity of the upper and the lower mold part, such that external heating or cooling medium is supplied to and withdrawn from the heating and cooling medium cavities of the upper and the lower mold parts therethrough to heat or cool the inner mold sections.

2. The mold assembly as set forth m claim 1, m which the inner mold section of the lower mold part includes a plurality of air vents formed at corner portions of shaping recess thereof to discharge air existing therein during shaping operation therethrough, and air venting elements for collecting air discharged through the air vents and discharging the air to outside of the outer mold section of the lower mold part.

3. The mold assembly as set forth in claim 1 or 2, m which the heating and cooling medium cavities of the upper mold part and the lower mold part are communicated with each other such that heating or cooling medium supplied to one of cavities of the upper and the lower mold parts is supplied to the other of the cavities through the communicating portions .