US20150298189A1

US20150298189A1 - Extrusion die using shock-absorbing pad and method for manufacturing extrusion

Info

Publication number: US20150298189A1
Application number: US14/405,784
Authority: US
Inventors: Sang Mok Lee; Geun An Lee; Hoon Jae PARK; Eung Zu Kim; Sung Joo LIM; Deog Jae YOON; Jong Sup Lee; Ki Ho JUNG; Yong Bae Kim; Yong Shin LEE; Sang Hun Yoon
Original assignee: Korea Institute of Industrial Technology KITECH
Current assignee: Korea Institute of Industrial Technology KITECH
Priority date: 2012-06-13
Filing date: 2013-06-13
Publication date: 2015-10-22
Also published as: KR20130139589A; WO2013187716A1

Abstract

An extrusion die using a shock-absorbing pad and a method for manufacturing an extrusion. A shock-absorbing pad is inserted between a material to be processed and a die such that the shock-absorbing pad is deformed during extrusion to form an optimal die half angle, thereby efficiently extruding the material to be processed. The extrusion die for extruding the material to be processed includes a container for accommodating a material to be processed, a die which is mounted on the front of the container, and which has, in the center thereof, a die hole that is a path through which the material to be processed is extruded, a shock-absorbing pad inserted between the material to be processed and the die, and a ram for pressing the material to be processed.

Description

TECHNICAL FIELD

The present invention relates, in general, to an extrusion mold using a buffer pad and a method of fabricating an extruded product and, more particularly, to an extrusion mold for efficiently extruding a material to be machined by disposing a buffer pad between the material to be machined and a die, such that the buffer pad is deformed during extrusion to form an optimum semi-die angle, and a method of fabricating an extruded product.

BACKGROUND ART

In general, the term extrusion refers to a process of loading a material to be machined within a container and subsequently applying a high pressure onto the material to be machined using a ram engaged with a piston disposed within a hydraulic cylinder, such that the material is pushed out through a die hole formed in the front portion of the container, thereby reducing the cross-section of the material to be machined. This extrusion process can mold a variety of products by extrusion, such as pipes, section materials and fine wires, while improving mechanical characteristics of the extruded products. In addition, an extrusion molding method for molding not only a single material, such as copper (Cu) or aluminum (Al), but also a heterogeneous material, such as copper clad aluminum (CCA), has been developed and commercialized.
FIG. 1( a) is a cross-sectional view illustrating a flat-faced die, and FIG. 1( b) is a cross-sectional view illustrating a conical-faced die. Referring to FIG. 1( a) and FIG. 1( b), in a flat-faced die 120, an inner wall surface 121 is perpendicular to a horizontal axis X, i.e. the direction in which a material to be machined is extruded, and a semi-die angle is 90°. On the other hand, in a conical-faced die 120, an inner wall surface 123 decreases in width along a horizontal axis X, i.e. the direction in which a material to be machined is extruded, and a semi-die angle is α°. Here, a can have a variety of values.
FIG. 2( a) is a schematic cross-sectional view of an extrusion mold 130 illustrating the state of a heterogeneous material loaded into a container 110 before being extruded through the flat-faced die, and FIG. 2( b) is a schematic cross-sectional view illustrating the state of the heterogeneous material after being extruded through the flat-faced die 120. Referring to FIG. 2( a) and FIG. 2( b), a heterogeneous material 220 includes a core 220 and a covering material 210 cladding the core 200. The heterogeneous material 220 is loaded into the container 110 and is extruded through a die hole 125 pressed under a high pressure from a ram 100. If a difference in deformation resistance due to the difference in yield strength between the core 200 and the covering material 210 is greater than the bonding force (or frictional force) of laminate interfaces, the core 200 and the covering material 210 are separated from each other, such that only the core 200 is extruded during the extrusion, which is problematic.
FIG. 3( a) is a schematic cross-sectional view of an extrusion mold illustrating the state of a heterogeneous material loaded into a container before being extruded through the conical-faced die, and FIG. 3( b) is a schematic cross-sectional view illustrating the state of the heterogeneous material after being extruded through the conical-faced die. Referring to FIG. 3( a) and FIG. 3( b), during the extrusion of the heterogeneous material, the covering material 210 is deformed by coming into contact with the conical inner wall surface before the core 200, and is subsequently separated from the core 200, such that only the covering material 210 is extruded, which is problematic.
Accordingly, both types of dies share the problem that the core and the covering material are separated from each other.

DISCLOSURE

Technical Problem

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 an extrusion mold for efficiently extruding a material to be machined by disposing a buffer pad between the material to be machined and a die, such that the buffer pad is deformed during extrusion to form an optimum semi-die angle, and a method of fabricating an extruded product.

Technical Solution

In order to accomplish the above object(s), the present invention provides an extrusion mold for extruding a material to be machined. The extrusion mold includes a container accommodating a material to be machined; a die disposed on a front portion of the container, the die having a die hole as a passage through which the material to be machined is extruded; a buffer pad disposed between the material to be machined and the die; and a ram pressing the material to be machined.
The material to be machined may include a core and a covering material cladding the core. The buffer pad may be formed of a material having a yield strength lower than a yield strength of a material of which the core or the covering material is formed.
Also provided is a molding device for fabricating an extruded product by extruding a material to be machined. The molding device has the above-described extrusion mold disposed therein.
Also provided is a method of fabricating a product by extruding a material to be machined. The method includes the following steps of: disposing a buffer pad between a material to be machined and a die; extruding the material to be machined through a die hole by applying a pressure to the material to be machined; and withdrawing a product extruded through the die hole.
The material to be machined may include a core and a covering material cladding the core. The buffer pad may be formed of a material having a yield strength lower than a yield strength of a material of which the core or the covering material is formed.

Advantageous Effects

According to the present invention as set forth above, it is possible to realize all of the objects of the present invention.
Specifically, the buffer pad additionally provides deformation resistance to a covering material while being deformed. It is therefore possible to prevent the covering material from being separated from a core and ensure that the core and the covering material are uniformly extruded through the die hole with a constant cross-section ratio, thereby preventing a defect in an extruded product.
In addition, the buffer pad fills a conical dead metal zone while being deformed, thereby forming an optimum half-die angle. This can consequently minimize an extrusion load required for the extrusion of a heterogeneous material. Furthermore, the buffer pad functions as a lubricant that reduces friction between the die and the covering material, thereby improving the quality and machinability of an extruded product.
In particular, it is possible to efficiently extrude a heterogeneous material using a flat-faced die of the related art without having to fabricate a conical die or disposing the conical die in the container, thereby reducing costs and improving the convenience of operation.

DESCRIPTION OF DRAWINGS

FIG. 1( a) is a cross-sectional view illustrating a flat-faced die, and FIG. 1( b) is a cross-sectional view illustrating a conical-faced die;

FIG. 2( a) is a schematic cross-sectional view of an extrusion mold illustrating the state of a heterogeneous material loaded into a container before being extruded through the flat-faced die, and FIG. 2( b) is a schematic cross-sectional view illustrating the state of the heterogeneous material after being extruded through the flat-faced die;

FIG. 3( a) is a schematic cross-sectional view of an extrusion mold illustrating the state of a heterogeneous material loaded into a container before being extruded through the conical-faced die, and FIG. 3( b) is a schematic cross-sectional view illustrating the state of the heterogeneous material after being extruded through the conical-faced die;

FIG. 4( a) is a schematic cross-sectional view of an extrusion mold according to an exemplary embodiment of the present invention illustrating the state in which a buffer pad is disposed between a heterogeneous material and a die, and FIG. 4( b) is a schematic cross-sectional view illustrating the flowing state of the heterogeneous material after being extruded;

FIG. 5( a) is a schematic cross-sectional view illustrating a device for indirectly extruding a heterogeneous material, and FIG. 5( b) is a schematic cross-sectional view illustrating a device for hydrostatically extruding a heterogeneous material; and

FIG. 6 is a process flowchart illustrating an extrusion method using a buffer pad according to an exemplary embodiment of the present invention.


<Description of the Reference Numerals in the Drawings>

100: ram

110: container

120: die

200: core

	210: covering material	220: heterogeneous material
	230: buffer pad

BEST MODE

Reference should now be made to the features and exemplary embodiments of the present invention in conjunction with the drawings.
FIG. 4( a) is a schematic cross-sectional view of an extrusion mold according to an exemplary embodiment of the present invention illustrating the state in which a buffer pad is disposed between a heterogeneous material and a die, and FIG. 4( b) is a schematic cross-sectional view illustrating the flowing state of the heterogeneous material after being extruded. Referring to FIG. 4( a) and FIG. 4( b), an extrusion mold 130 according to the present invention includes a container 110, a die 120, a buffer pad 230 and a ram 100.
In the following, the same reference numerals will be used to refer to the same or like parts, and repeated descriptions of the same or like parts will be omitted.
Specifically, the container 110 is open at the front and the rear, and is configured such that it can accommodate a heterogeneous material 220 to be machined and the buffer pad 230. In general, the heterogeneous material 220 includes a core 200 and a covering material 210 cladding the core. In this case, the core may be formed of aluminum (Al) or an alloy thereof, and the covering material may be formed of copper (Cu) or an alloy thereof. However, the present invention is not limited thereto and other materials may be applied. These materials are also embraced within the scope of the present invention.
The die 120 has an inner wall surface 121 perpendicular to the direction in which the heterogeneous material flows. The die 120 has a die hole at the center, through which the heterogeneous material is extruded, and a land section 122 on the inner circumference of the die hole. The land section 122 is configured to improve the straightness of an extruded product.
The buffer pad 230 is disposed between the die 120 and the heterogeneous material 220. The buffer pad 230 fills a conical dead metal zone to form an optimum half-die angle while being deformed to minimize extrusion energy during the extrusion in which the material is pressed with the ram 100. Consequently, it is possible to minimize an extrusion load required to extrude the heterogeneous material. In addition, the buffer pad 230 provides additional deformation resistance to the covering material while forming an optimum half-die angle through deformation. This can consequently prevent the core 200 and the covering material 210 from being separated from each other. In this case, it is preferable that the buffer pad 230 is formed of a material having a yield strength lower than that of a material of which the core 200 or the covering material 210 is formed.
The ram 100 is engaged with a piston (not shown) of a hydraulic cylinder (not shown) that is actuated by hydraulic pressure. The ram 100 presses the heterogeneous material 220 under high pressure while moving forwards in close contact with the inner surface of the container 110, thereby pushing the heterogeneous material through the die hole. While the material to be machined is illustrated as being pressed by direct extrusion according to an embodiment of the present invention, the present invention is not limited thereto. The scope of the present invention includes an indirect extrusion method of extruding a material to be machined in the opposite direction to the direction in which the die 120 engaged with the ram 100 moves (see FIG. 5( a)) and a hydrostatic extrusion method of extruding a material to be machined 220 by making the pressure of a fluid 240 surrounding the material 220 to be identical to a critical pressure (see FIG. 5( b)).
FIG. 6 is a process flowchart illustrating an extrusion method using a buffer pad according to an exemplary embodiment of the present invention. Referring to FIG. 6, the extrusion method using a buffer pad includes a buffer pad inserting step S100, an extrusion step S200 and a product withdrawal step S300.
Specifically, the buffer pad inserting step S100 includes loading a heterogeneous material into a container, disposing the buffer pad in close contact with the front portion of the heterogeneous material, and subsequently coupling the die with the front portion of the container. The extrusion step S200 includes extruding the heterogeneous material through the die hole by applying a pressure to the heterogeneous material by direct/indirect extrusion or hydrostatic extrusion. The product withdrawal step S300 includes withdrawing a product that has been extruded through the die hole from the extrusion mold 130.
Although the exemplary embodiments of the present invention have been described 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 present invention as disclosed in the accompanying claims.

Claims

1. An extrusion mold for extruding a material to be machined, comprising:

a container accommodating a material to be machined;

a die disposed on a front portion of the container, the die having a die hole as a passage through which the material to be machined is extruded;

a buffer pad disposed between the material to be machined and the die; and

a ram pressing the material to be machined.

2. The extrusion mold according to claim 1, wherein

the material to be machined comprises a core and a covering material cladding the core, and

the buffer pad is formed of a material having a yield strength lower than a yield strength of a material of which the core or the covering material is formed.

3. A molding device for fabricating an extruded product by extruding a material to be machined, the molding device comprising the extrusion mold as claimed in claim 1.

4. A method of fabricating a product by extruding a material to be machined, the method comprising:

disposing a buffer pad between a material to be machined and a die;

extruding the material to be machined through a die hole by applying a pressure to the material to be machined; and

withdrawing a product extruded through the die hole.

5. The method according to claim 4, wherein