Metal deforming – By extruding through orifice
Reexamination Certificate
2000-03-28
2003-05-06
Tolan, Ed (Department: 3725)
Metal deforming
By extruding through orifice
C072S271000, C072S467000, C076S004000, C076S107100, C076S107400, C703S001000
Reexamination Certificate
active
06557388
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 11-099170, filed Apr. 6, 1999, entitled “Method Of Producing Extrusion Die, Apparatus For Producing The Same, And Extrusion Die Produced By The Method”. The contents of that application are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of determining at least one dimension of an extrusion die, and an extrusion die produced based on the method.
2. Discussion of the Background
As is obvious from its schematic structure shown in
FIG. 1
, an extrusion press
10
used for extrusion generally is constructed by a container
11
, an extrusion die
12
fixed to one end of the container
11
, a stem
13
movably mounted on a pushing ram at the other end of the container
11
, and a bolster
16
for fixing the container
11
and the extrusion die
12
through a backer
14
and a die ring
15
. An extrusion method is, for example, a hot working method including placing a cylindrical aluminum billet in the container
11
interposed between the extrusion die
12
and the stem
13
and moving the stem
13
to extrude the billet into a product from the extrusion die
12
. Most billets used for extrusion are cylindrical but square billets may be used. When a material having excellent hot workability such as aluminum is extruded by the above method, even a product having a complicated shape may be obtained.
The extrusion die used for extrusion has a shape shown in
FIG. 2
as an example. The design values of the extrusion die mostly depend on the thickness of an extruded product and typical design factors include a bearing length and a flow guide shape. In this invention a flow guide shape or a chamber shape means absolute shape: that is because shape has the meanings of both size and shape.
The bearing is a part to give friction to an extrusion material for controlling a metal flow and formed at the outlet of the extrusion die. For example, in the case of a solid (product having no hollow portion) extrusion die shown in
FIG. 2
, the bearing is a portion where an extrusion material is extruded (in the figure, the inner wall of a die hole corresponding to the cross-section of a product). The purpose of forming the bearing is to form an extruded product having a desired shape. Stated more specifically, by changing the wall length of a bearing at each portion, a metal flow is controlled making use of friction at the time of extrusion to mold in an extruded product having a desired shape. That is, by changing the length of a part to give friction to a metal according to the shape of a product, a metal flow is controlled properly and a product of high quality which cannot be bent by metal flow or the like is extruded.
Generally speaking, when there is nonuniformity in the thickness of a product, the metal flow rate tends to be higher in a thick portion than in a thin portion at the time of extrusion. Therefore, the wall length of a bearing of a portion corresponding to the thick portion must be designed relatively larger than the wall length of a bearing of a portion corresponding to the thin portion. Thus, the determination of the wall length of the bearing is one of important factors that affect extrusion results in terms of the size and shape of an extrusion material.
A description is subsequently given of a general method of determining the wall length of a bearing.
Points (points along the die opening for calculating the wall length of a bearing) for calculating the wall length of a bearing on an opening (die hole shape) of a die are first determined. For example, when a product has a sectional shape as shown in
FIG. 3
, two different points (points A and B) on the reference line of the bottom portion of the section are selected. Thereafter, thicknesses at these calculation points are measured and the wall length of the bearing is calculated using the bearing wall length calculation equation of each designer. A die having the calculated bearing wall length is produced and extrusion is carried out using this die. Stated more specifically, based on the thickness of 40 mm at the point A and the thickness of 15 mm at the point B, the wall length of the bearing between points A and B is obtained.
Even when the measurement of the thickness of a product is carried out by each designer independently, in the case of a straight angular shape surrounded by parallel straight lines as shown in
FIG. 4
, since the shape is simple and a single design standard can be applied, differences among the concepts of designers and the methods of applying design standards are rarely occurred.
However, since extruded products are various in shape, there are differences in thickness measurement among designers with the result that dies which are designed differently may be obtained. For example, in the case of a product having a shape shown in
FIG. 5
, definition “a” and definition “b” are conceivable for the determination of thickness at point C in the figure and there is a difference in the measurement value of thickness according to differences in concept among designers and design standards such as thickness measurement method and the like.
Since the shape of the opening of an extrusion die is complicated and various, in the present situation in which a reference line is used to measure the thickness of an extrusion material as the basis of the design of a bearing or the measurement of thickness depends on the judgment of each designer, the step of making a bulky manual describing a huge number of product shape patterns and minute rules is required to reduce differences in thickness measurement method among designers.
When a die opening is shaped like an ameba having no symmetry at any portions, “thickness” itself cannot be defined, thereby making it impossible to design a bearing based on predetermined standards by a conventional bearing design method.
Meanwhile, CAD has been frequently used for the design of an extrusion die in recent years. Even when CAD is used, product thickness measurement methods are classified by the shape of a die opening and further complicated rules are incorporated into a CAD program, a huge number of program production steps and a huge number of maintenance steps are required to produce a program which covers all kinds of products having thousands of different shapes. Further, since thickness itself cannot be defined even by using CAD incorporating design standards based on conventional design techniques, the above opening having a completely unsymmetric shape cannot be incorporated into a CAD program, thereby making it impossible to automate the design of a die.
Moreover, since there is such a case as lack of some patterns or rules, a method of defining the measurement of the thickness of a product according to the shape of a product in an one-to-one correspondent manner is necessary even if any type of the product shape is given.
The following two typical methods have been used to define thickness.
The first method (1) is, as shown in
FIG. 6
, to draw inward a perpendicular or normal to an element (line segment or circular arc) belonging to a bearing wall length calculation point D (D
1
, D
2
, . . . ) on an opening from the calculation point D, obtain an intersection point E (E
1
, E
2
, . . . ) with an element on the opposite side, and define the distance between the intersection point E and the bearing wall length calculation point D as thickness.
The second method (2) is, as shown in
FIG. 7
, to provide a predetermined reference line on the under surface of extrusion for the shape of a product, draw inward a perpendicular to the reference line from a bearing wall length calculation point F (F
1
, F
2
, . . . ), obtain an intersection point G (G
1
, G
2
, . . . ) with an element on the opposite side and define the distance between the intersection point G and the bearing wall length calculation point F as thickness.
According to the above met
Itabashi Kazuhiro
Kakinoki Toshiyuki
Kato Kazumi
Mitsumaru Akira
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
The Furukawa Electric Co. Ltd.
Tolan Ed
LandOfFree
Method of determining dimension of extrusion die and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of determining dimension of extrusion die and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of determining dimension of extrusion die and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3089203