U.S. patent application number 10/542686 was filed with the patent office on 2007-01-11 for molding method by forging and molding method for case.
Invention is credited to Takashi Araki, Shinji Kouno, Takashi Miura, Youichi Tabei, Shoichi Yanaoka.
Application Number | 20070006628 10/542686 |
Document ID | / |
Family ID | 35149824 |
Filed Date | 2007-01-11 |
United States Patent
Application |
20070006628 |
Kind Code |
A1 |
Tabei; Youichi ; et
al. |
January 11, 2007 |
Molding method by forging and molding method for case
Abstract
A material member blanked from metal sheet is subjected to
upsetting to form an annular peripheral portion that is thinner
than the center part of the material inside the annular portion,
and the thicker inside portion is formed into a concavity. The
first intermediate product thus formed is drawn to form a
cup-shaped case with an internal boss and/or an external boss, and
an outside flange. The intermediate product can also be used to
make gears and the like.
Inventors: |
Tabei; Youichi; (Saitama,
JP) ; Araki; Takashi; (Saitama, JP) ; Kouno;
Shinji; (Saitama, JP) ; Yanaoka; Shoichi;
(Gumma, JP) ; Miura; Takashi; (Gumma, JP) |
Correspondence
Address: |
KENYON & KENYON LLP
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
35149824 |
Appl. No.: |
10/542686 |
Filed: |
April 16, 2004 |
PCT Filed: |
April 16, 2004 |
PCT NO: |
PCT/JP04/05443 |
371 Date: |
September 5, 2006 |
Current U.S.
Class: |
72/348 |
Current CPC
Class: |
B21K 1/30 20130101; B21K
1/76 20130101; B21K 21/00 20130101; B21K 1/28 20130101; B21K 21/02
20130101; B21J 5/06 20130101 |
Class at
Publication: |
072/348 |
International
Class: |
B21D 22/00 20060101
B21D022/00 |
Claims
1. A method of forming by forging material, characterized in that
the method comprises: a first step of preparing sheet material, and
a second step in which a thickness of a circumferential portion of
the material is made thinner than a thickness of a center portion
of the material.
2. A method as claimed in claim 1, wherein the first step is a step
of blanking sheet metal.
3. A method as claimed in claim 1, wherein the second step is a
step of simultaneously stamping-forming a concavity in the center
portion of the material.
4. A method as claimed in claim 1 or 3, wherein the second step is
carried out by upsetting.
5. A method of forming a case, characterized in that the method
comprises: a first step of preparing sheet material, and a second
step in which a thickness of a circumferential portion of the
material is made thinner than a thickness of a center portion of
the material.
6. A method as claimed in claim 5, wherein the first step is a step
of blanking sheet metal.
7. A method as claimed in claim 5, wherein the second step is a
step of simultaneously stamping-forming a concavity in the center
portion of the material.
8. A method as claimed in claim 5, wherein the second step is a
step of forming by forging.
9. A method as claimed in claim 5, wherein the second step is
carried out by upsetting.
10. A method as claimed in claim 5, further comprising a third step
in which an intermediate product obtained by the second step is
forward drawn to simultaneously form the peripheral wall and bottom
of the case.
11. A method as claimed in claim 10, wherein, if a is a thickness
of the peripheral wall and b is a thickness of the bottom,
a<b.
12. A method as claimed in claim 5, wherein an intermediate product
obtained by the second step is forward drawn to form a case
peripheral wall, and then to form an internal boss.
13. A method as claimed in claim 5, wherein an intermediate product
obtained by the second step is forward drawn to simultaneously form
the case peripheral wall and the internal boss.
14. A method as claimed in claim 5, wherein an intermediate product
obtained by the second step is annealed before being subjected to a
subsequent step.
15. A method as claimed in claim 7, wherein the second step is a
step of forming by forging.
16. A method as claimed in claim 7, wherein the second step is
carried out by upsetting.
17. A method of forming a cup-shaped case having an internal boss,
characterized in that the method comprises: a step of preparing
sheet material, a step of making a thickness of a circumferential
portion of the material thinner than a thickness of a center
portion of the material and simultaneously stamping-forming a
concavity in the center portion of the material, and a method of
forward drawing an intermediate product obtained by the
stamping-forming to form a cup-shaped case having a bottom that is
thicker than a peripheral wall.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of forming by
forging and a case forming method.
BACKGROUND ART
[0002] Various types of machine parts and the like are often
manufactured by forging for cost reasons. In such cases, it often
happens that the intermediate product requires the formation of an
overlay on the plate core material. This is the case in, for
example, the manufacture of parts such as sprockets, gears,
pulleys, cams, links and fixing brackets.
[0003] Also, cup-shaped cases with a boss provided on the inside
are widely employed in various fields. For example, the case of the
electromagnetically controlled valve of an injection apparatus used
to supply fuel to the cylinders in an internal combustion engine is
a cup-shaped member with an integrally formed inside boss for
affixing the electromagnetic coil and the magnetic core. Cup-shaped
cases such as these having an inside boss are also usually formed
by forging, for cost reasons, and in the intermediate product form
require the formation of overlays on the plate core material.
[0004] In the prior art the method of fabrication used in cases
such as these in which material is to be shaped by forging and the
intermediate product requires the formation of an overlay on plate
core material, has been to press-form cylindrical material obtained
by cutting low-carbon round steel bar.
[0005] Japanese Unexamined Patent Application publication No.
2000-94088 discloses a method of forming a cup with an inside boss
in which the material is obtained by spheroidizing annealing a
forged slab and subjecting the material to shot bonderizing
treatment. Because the method includes the step of cutting round
steel bar, it endeavors to reduce the cutting cost by using round
bar having a relatively small diameter, and gives the material a
thick configuration suitable for forming a cup having an internal
boss by forging the cut sections of round bar. To eliminate such
tasks, there is also known a method of forming a case having an
internal boss by preparing and forging a flat steel slab.
[0006] However, in the case of the above method in which the
intermediate product is formed by stamping cylindrical material
obtained by cutting low-carbon round steel bar, there are problems
such as a high cutting cost, making the end product costly.
[0007] Also, when a cup-shaped case is formed with an internal boss
by the forging of sheet material, the cup is stamping-formed by the
forward drawing of relatively thin sheet material, so there tends
to be a lack of bulk which can make it difficult to ensure that the
bottom is thick enough to form the internal boss by forming the
bottom of the cup thicker than the peripheral wall.
[0008] An object of the invention is to provide a method of forming
by forging and a case forming method capable of overcoming the
aforesaid problems of the prior art.
[0009] An object of the invention is to provide a method of forming
for manufacturing a high-quality case by blanking of sheet
material.
[0010] Another object of the invention is to provide a case forming
method capable of manufacturing high-quality cases at low cost.
DISCLOSURE OF THE INVENTION
[0011] A characterizing feature of the invention is that the method
of forming by forging material comprises a first step of preparing
sheet material, and a second step in which a thickness of a
circumferential portion of the material is made thinner than a
thickness of a center portion of the material.
[0012] Another characterizing feature of the invention is that the
case forming method comprises a first step of preparing the sheet
material, and a second step in which a thickness of a
circumferential portion of the material is formed to be thinner
than a thickness of a center portion of the material.
[0013] Another characterizing feature of the invention is that the
method of forming a cup-shaped case having an internal boss
comprises a step of preparing sheet material, a step of forming a
circumferential portion of the material to be thinner than a
thickness of a center portion of the material while simultaneously
time stamping-forming the thicker center portion into a concave
shape, and a step of using forward drawing to stamping-form the
intermediate product formed by the above stamping-forming into a
cup-shaped member having a bottom that is thicker than the
peripheral wall.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a diagram for illustrating the process of forming
a case with an internal boss in accordance with the invention.
[0015] FIG. 2 is a diagram for illustrating the process of forming
a case with an internal boss in accordance with the invention.
[0016] FIG. 3 is a diagram for illustrating the process of forming
a case with an internal boss in accordance with the invention.
[0017] FIG. 4 is a diagram for illustrating the process of forming
a case with an internal boss in accordance with the invention.
[0018] FIG. 5 is a diagram for illustrating the process of forming
a case with an internal boss in accordance with the invention.
[0019] FIG. 6 is a diagram illustrating the forming process when
the first intermediate formed product shown in FIG. 2 is used to
manufacture a gear.
[0020] FIG. 7 is a diagram illustrating the forming process when
the first intermediate formed product shown in FIG. 2 is used to
manufacture a gear.
[0021] FIG. 8 is a diagram illustrating the forming process when
the first intermediate formed product shown in FIG. 2 is used to
manufacture a gear.
[0022] FIG. 9 is a diagram illustrating the forming process when
the first intermediate formed product shown in FIG. 2 is used to
manufacture a pulley.
[0023] FIG. 10 is a diagram illustrating the forming process when
the first intermediate formed product shown in FIG. 2 is used to
manufacture a pulley.
[0024] FIG. 11 is a diagram illustrating the forming process when
the first intermediate formed product shown in FIG. 2 is used to
manufacture a pulley.
BEST MODE OF CARRYING OUT THE INVENTION
[0025] Embodiments of the invention will now be explained in detail
with reference to the drawings.
[0026] FIGS. 1 to 5 are process ironings for explaining an
embodiment of method of the invention, applied to the manufacture
of the case of an electromagnetically controlled valve of a fuel
injection apparatus used to supply fuel to an internal combustion
engine.
[0027] First, the sheet member shown in FIG. 1 is prepared as
material 1. The material 1 can be obtained by, for example, by
blanking and stamping low-carbon steel sheet. Here, material 1 is a
disk-shaped member, but it does not have to be disk-shaped.
[0028] Next, upsetting is used to reduce the thickness of the
periphery compared to the thickness at the center portion while
forming a concavity in the thick center portion, forming the first
intermediate formed product 2 shaped as shown in FIG. 2. The
intermediate formed product 2 shown in FIG. 2 has a circumferential
thin annular portion 21, a thick portion 22 on the inside of the
thin annular portion 21 that is thicker than the thin annular
portion 21, and a concave portion 22A on the center portion of the
thick portion 22.
[0029] In subsequent process steps, the thick portion 22 is formed
into at least the case bottom and internal boss, so it is thickened
to allow for at least the amount of material for the internal boss
formed integrally with the bottom. Before being processed in the
next step, it is preferable for the first intermediate formed
product 2 to be annealed to prevent cracking occurring in the
subsequent process steps.
[0030] In the following drawing and ironing step, the first
intermediate formed product 2 is stamping-formed to form the thick
portion 22 into a bottom 32 and the thin annular portion 21 into a
peripheral wall 31 that extends integrally from the bottom 32,
thereby forming a second intermediate formed product 3 shaped as
shown in FIG. 3. Since the first intermediate formed product 2 has
the concave portion 22A in the center thereof, the second
intermediate formed product 3 of FIG. 3 can readily be obtained by
the drawing and ironing process. In order to form an external
flange around the edge of the peripheral wall of the case, drawing
and ironing are used to slightly thicken the outer edge 31A of the
peripheral wall 31, giving the wall 31 a skirt-like shape. The
thickness of the peripheral wall 31 is less than the thickness of
the bottom 32. If an external flange is not needed, it is not
necessary to thicken the outer edge 31A.
[0031] In the next forward/backward drawing to which the second
intermediate formed product 3 is subjected to form it into the
third intermediate formed product 4 shown in FIG. 4, internal boss
43 is formed on the inside of the bottom 42, external boss 44 is
formed on the outside of the bottom 42, and external flange 41A is
formed on the edge of the peripheral wall 41. Only forward drawing
is required in cases in which the external boss 44 is not
needed.
[0032] In the next step, two dies are used to stamp the third
intermediate formed product 4 into the intended final shape to
obtain, as the final product, the case 5 having an internal boss
shown in FIG. 5. In the case 5 thus formed, the bottom 52 and
peripheral wall 51 are approximately the same thickness and the
internal boss 53 and external boss 54 on the bottom 52 are coaxial.
The internal boss 53 is provided in order to incorporate an
electromagnetic solenoid, and the external boss 54 is provided to
accommodate a bearing. An external flange 51A on the outside edge
of the peripheral wall 51 extends integrally at a right-angle to
the peripheral wall 51.
[0033] When a case with an internal boss is formed in accordance
with the steps of FIGS. 1 to 5, since it is possible to draw sheet
material to form an internal boss and/or an external boss in the
bottom, it is possible to readily manufacture a high-quality
product at a lower cost compared to the prior art in which a case
is formed with an internal boss from a cut section of round bar.
Moreover, in a modified version of the example shown in FIG. 5, it
is also possible to form just an internal boss. In particular,
using the same volume to form just an internal boss makes it
possible to form an internal boss that is higher than when both
internal and external bosses are formed.
[0034] While the above explanation has been made with reference to
one embodiment of the invention, the first intermediate formed
product 2 shown in FIG. 2 is a general-purpose member. The first
intermediate formed product 2 can be used as an intermediate
product in the manufacturing of, for example, sprockets, gears,
pulleys, cams, links and fixing brackets.
[0035] The steps of using the first intermediate formed product 2
of FIG. 2 to manufacture a gear will now be described with
reference to FIGS. 6 to 8. First, the first intermediate formed
product 2 is prepared and subjected to forward/backward drawing
forging steps whereby the thick center portion of the first
intermediate formed product 2 is formed into a boss 61 and the thin
portion is formed into a thin annular portion 62 having a uniform
thickness. Here, the boss 61 is cup-shaped, formed as a cylinder
with a bottom.
[0036] The intermediate formed product in FIG. 6 is stamped to
remove the bottom 61A of the boss 61, forming the cylindrical boss
63 shown in FIG. 7.
[0037] Then, the periphery of the thin annular portion 62 is
trimmed and blanked, forming a plurality of teeth 62A to thereby
obtain a gear 6 having a boss 63 (FIG. 8).
[0038] The steps of using the first intermediate formed product 2
of FIG. 2 to manufacture a pulley will now be described with
reference to FIGS. 9 to 11. First, the first intermediate formed
product 2 is prepared and stamped to increase the thickness of the
peripheral edge of the thin portion, thereby forming the outer ring
71 shown in FIG. 9.
[0039] After forming the outer ring 71, forward/backward drawing
forging steps are used whereby the thick center portion is formed
into a boss 72 and a thin annular portion 73 having a uniform
thickness is formed between the outer ring 71 and the boss 72 (FIG.
10). Here, the boss 72 is cup-shaped, formed as a cylinder with a
bottom, and the outer ring 71 is formed to have the required
dimensions for outer ring 74.
[0040] Then, the bottom 72A of the boss 72 is punched to remove it,
forming the cylindrical boss 75 shown in FIG. 11.
[0041] In accordance with the above steps, a pulley 7 is obtained
comprising the boss 75 and the outer ring 74 integrated by the thin
annular portion 73 of uniform thickness. For end product
application, a groove may be formed on the outer ring 74 by
machining or the like.
INDUSTRIAL APPLICABILITY
[0042] The method of forming by forging and a case forming method
according to the invention, as described in the foregoing, is
useful for the low-cost fabrication of parts such as sprockets,
gears, pulleys, cams and fixing brackets, and for the low-cost,
high-quality manufacture of cup-shaped cases with an internal
boss.
* * * * *