U.S. patent application number 14/101685 was filed with the patent office on 2014-07-31 for wire electrical discharge machined rupture disk and method.
This patent application is currently assigned to Oklahoma Safety Equipment Company, Inc.. The applicant listed for this patent is Oklahoma Safety Equipment Company, Inc.. Invention is credited to Alan Wilson.
Application Number | 20140209182 14/101685 |
Document ID | / |
Family ID | 50240212 |
Filed Date | 2014-07-31 |
United States Patent
Application |
20140209182 |
Kind Code |
A1 |
Wilson; Alan |
July 31, 2014 |
WIRE ELECTRICAL DISCHARGE MACHINED RUPTURE DISK AND METHOD
Abstract
The present invention provides an improved method of
manufacturing a rupture disk and specifically of forming a score on
a rupture disk. The method of the present invention includes the
rotating of a rupture disk blank relative to an electrical
discharge machining or "EDM" cutting wire and the simultaneous
moving of the EDM cutting wire toward the axis of the disk while
maintaining the wire in a selected position such as generally
parallel to the disk peripheral skirt or flange. The rotation of
the disk and the movement of the EDM wire can be precisely
controlled with the motion system of a commercially available EDM
machine. With the present invention, a precise score is cut a
partial distance through the disk thickness and preferably on the
convex side of the dome, near the transition from the dome to the
flange and in a generally "c" shaped pattern. The formed score
creates a pattern of weakness so that the disk will open in either
of the forward or reverse buckling direction. Score patterns other
than the "c" shaped pattern could be cut.
Inventors: |
Wilson; Alan; (Coweta,
OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Oklahoma Safety Equipment Company, Inc. |
Broken Arrow |
OK |
US |
|
|
Assignee: |
Oklahoma Safety Equipment Company,
Inc.
Broken Arrow
OK
|
Family ID: |
50240212 |
Appl. No.: |
14/101685 |
Filed: |
December 10, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11956047 |
Dec 13, 2007 |
8671550 |
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14101685 |
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60870000 |
Dec 14, 2006 |
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Current U.S.
Class: |
137/15.18 |
Current CPC
Class: |
Y10T 137/0491 20150401;
B23H 7/02 20130101; F16K 17/40 20130101; Y10T 29/49995 20150115;
B23H 9/00 20130101; B23H 7/26 20130101; F16K 17/16 20130101 |
Class at
Publication: |
137/15.18 |
International
Class: |
F16K 17/40 20060101
F16K017/40 |
Claims
1. A method of constructing a rupture disk, comprising the steps
of: a) providing a disk blank having a peripheral flange and a
concave convex portion that is surrounded by the peripheral flange;
b) rotating the disk blank upon a turntable wherein the turntable
engages the concave convex portion of the disk blank; c) during the
rotating of step "b", scoring the surface of the concave convex
portion with a wire of a wire electrical discharging machine, said
wire having a wire cross section and an outer surface with a shape;
and d) wherein the score includes a shaped part, at least part of
the shaped part having the shape of the outer surface of the wire,
the shaped part having a transverse cross section that is larger
than the cross section of the wire.
2. The method of claim 1 wherein the wire is between about 0.004
and 0.0012 inches in diameter.
3. The method of claim 1 wherein the wire is about 0.0010 inches in
diameter.
4. The method of claim 1 wherein in steps "c" and "d" the wire is
spaced away from the peripheral flange.
5. The method of claim 1 wherein the score formed in step "c" has a
transverse cross section that is different in shape than the
transverse cross section of the score.
6. The method of claim 1 wherein the score formed in step "c" has
at least three surfaces that are of different curvatures in
transverse cross section.
7. The method of claim 6 wherein the surfaces include at least one
generally flat surface.
8. The method of claim 6, wherein the surfaces include two flat
surfaces of different lengths.
9. The method of claim 1 wherein the disk blank has a thickness of
between 0.003 and 0.125 inches.
10. The method of claim 1 wherein the disk blank has a thickness of
between about 0.003 and 0.375 inches.
11. The method of claim 1 wherein the distance between the wire and
the peripheral flange is between about 0.020 and 2.0 inches.
12. The method of claim 1 wherein a convex surface of the disk
blank is scored in step "c".
13. The method of claim 1 wherein the disk blank has a central axis
and wherein the score in step "c" extends less than 360 degrees
around the disk blank central axis.
14. The method of claim 1 wherein in steps "b" and "c" rotation of
the turntable is controlled by the wire electrical discharge
machine.
15. The method of claim 1 wherein in step "c" movement of the wire
is controlled by the wire electrical discharge machine.
16. A method of constructing a rupture disk, comprising the steps
of: a) providing a disk blank having a central axis, a peripheral
flange and a concave convex portion that is surrounded by the
peripheral flange; b) rotating the disk blank and a cutting wire
relative to each other; c) during said rotating, scoring the
surface of the concave convex portion with the wire to form a
scored recess, wherein the wire is an electrical discharging
machine wire that contacts the disk concave convex portion while
scoring said surface, said wire having a diameter; d) wherein the
wire is advanced toward the disk central axis as the score is
formed in steps "b" and "c"; e) wherein the wire is spaced away
from the peripheral flange in step "d"; and f) the scored recess
having a maximum width that is greater than the wire diameter.
17. The method of claim 16 wherein the wire is between about 0.004
and 0.0012 inches in diameter.
18. The method of claim 16 wherein the wire is about 0.0010 inches
in diameter.
19. The method of claim 16 wherein in steps "c" and "d" the wire is
positioned generally parallel to a plane defined by the peripheral
flange.
20. The method of claim 16 wherein the score formed in steps "c"
and "d" has a cross section that is asymmetrical in transverse
cross section.
21. The method of claim 16 wherein the score formed in steps "c"
and "d" has surfaces that are of different curvatures in transverse
cross section.
22. The method of claim 16 wherein the score formed in steps "c"
and "d" has a generally flat surface.
23. The method of claim 16 wherein the wire is positioned in step
"c" to cut only partially through the disk blank.
24. The method of claim 16 wherein the disk blank has a thickness
of between 0.003 and 0.125 inches.
25. The method of claim 16 wherein the disk blank has a thickness
of between about 0.003 and 0.375 inches.
26. The method of claim 16 wherein the distance between the wire
and the peripheral flange is between about 0.020 and 2.0
inches.
27. The method of claim 16 wherein a convex surface of the disk
blank is scored in steps "c" and "d".
28. The method of claim 16 wherein the score in steps "c" and "d"
extends less than 360 degrees around the disk blank central
axis.
29. The method of claim 16 wherein in steps "b" and "c" the disk
blank is supported upon a tool and wherein rotation of the tool is
controlled by the wire electrical discharge machine.
30. The method of claim 16 wherein in step "c" movement of the wire
is controlled by the wire electrical discharge machine.
31. The method of claim 16 wherein the disk blank is supported by a
tool and wherein the tool engages the disk concave convex
portion.
32. The method of claim 16 wherein the disk blank is supported by a
tool and wherein the tool engages the disk peripheral flange.
33. The method of claim 1, further comprising the step of forming
an asymmetrical transverse cross section score on the disk
blank.
34. The method of claim 16, further comprising the step of forming
an asymmetrical transverse cross section score on the disk
blank.
35. The method of claim 16, further comprising the step of
supporting the disk blank on a tool.
36. The method of claim 35, further comprising the step of engaging
the tool to the disk peripheral flange.
37. The method of claim 35, further comprising the step of engaging
the tool to the disk concave convex portion.
38. The method of claim 35, further comprising the step of engaging
the tool to both the disk peripheral flange and the disk concave
convex portion.
39. A method of constructing a rupture disk, comprising the steps
of: a) providing a disk blank having a peripheral flange and a
concave convex portion having concave and convex surfaces and
surrounded by the peripheral flange; b) rotating the disk blank
upon a turntable, wherein the turntable contacts the concave
surface of the disk concave convex portion; c) during the rotating
of step "b", scoring the surface of the concave convex portion with
a wire of a wire electrical discharging machine, said wire having
an outer surface with a shaped surface; and d) wherein the score
includes a curved part that has the same curvature as the curvature
of at least a part of the outer surface of the wire.
40. A method of constructing a rupture disk, comprising the steps
of: a) providing a disk blank having a peripheral flange and a
concave convex portion that is surrounded by the peripheral flange,
said concave convex portion having concave and convex surfaces and
a central axis; b) rotating the disk blank upon a turntable and
about said central axis, wherein the turntable contacts the disk
concave surface; c) during the rotating of step "b", scoring the
convex surface with a wire of a wire electrical discharging
machine; d) wherein the wire has a circular cross section and the
score has a cross section that is formed by the wire in step "c"
and which score has a first part that corresponds in shape to the
cross section of the wire and a second part generated by movement
of the wire toward the disk central axis.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This is a continuation of U.S. patent application Ser. No.
11/956,047, filed Dec. 13, 2007, which is a non-provisional of U.S.
Provisional Patent Application Ser. No. 60/870,000, filed Dec. 14,
2006, each of which is incorporated herein by reference and
priority is hereby claimed.
[0002] Priority of U.S. Provisional Patent Application Ser. No.
60/870,000, filed Dec. 14, 2006, incorporated herein by reference,
is hereby claimed.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0003] Not applicable
REFERENCE TO A "MICROFICHE APPENDIX"
[0004] Not applicable
BACKGROUND OF THE INVENTION
[0005] 1. Field of the Invention
[0006] The present invention relates to the manufacturing of
rupture disks. More particularly, the present invention relates to
an improved method of manufacturing a rupture disk that has a
concave convex central disk portion surrounded by a planar
peripheral skirt, wherein the disk is rotated about a central disk
axis, and wherein a wire electric discharge machine forms a score
or cut that extends a partial distance through the outer surface of
the disk concave convex portion. The score predictably contributes
to disk failure when the rupture disk is subjected to a design
pressure value.
[0007] 2. General Background of the Invention
[0008] Rupture disks are used in a variety of chemical process and
manufacturing applications. The Oklahoma Safety Equipment
Corporation website (www.oseco.com) provides many rupture disk
products that are available to satisfy numerous applications.
[0009] In the past, rupture disks have been scored in hydraulic
presses using very precisely machined and hardened tooling and
hardened sine bars to control the score depth. Changes in the
profile of the disk or the geometry of the score necessitate the
design and manufacture of new score blades and anvils.
[0010] Scoring with hard tooling work hardens the disk material
often requiring a post score anneal or stress relief. Worn or
damaged tooling must be rebuilt and replaced. Hard materials are
especially prone to damaging score tooling. The need to heat treat
and harden tooling makes it difficult to manufacture in large sizes
as the heat treatment often distorts the tooling beyond acceptable
tolerances.
BRIEF SUMMARY OF THE INVENTION
[0011] The method of the present invention offers several
advantages over previous methods of manufacturing rupture disks
including previous methods of scoring rupture disks.
[0012] The new method of the present invention includes rotating a
rupture disk blank and electrical discharge machining cutting wire
relative to one another while moving the cutting wire toward the
axis of the disk and while maintaining the wire in a selected
position (e.g. parallel to the disk flange). The relative rotation
of the disk and wire and the movement of the wire toward the disk
can be precisely controlled by a motion system of an electrical
discharge machining apparatus or "EDM" machine. The objective is to
cut a precise "score" part way through the disk thickness. The
"score" can be on the convex side of the dome. The score can be
near the transition from the dome to the flange. The score extends
less than 360 degrees circumferentially in a generally "c" shaped
pattern. This score will create a pattern of weakness so the disk
will open in either the forward or the reverse buckling direction.
Patterns other than a "c" shaped pattern could be cut as well.
[0013] The score tool is electrical discharge machining or "EDM"
wire, which is constantly renewed. Changes in score depth or shape
can be achieved by machine programming. Standard EDM equipment with
a controlled rotary table could be used to cut or score multiple
disk sizes. Tooling to hold the disk in the rotary table would be
developed for each disk size, however the same tooling could be
used for all thicknesses and disk materials.
[0014] The present invention includes a method of constructing a
rupture disk. The method of the present invention includes
providing a disk blank having a peripheral flange and a concave
convex portion that is surrounded by the peripheral flange,
rotating the disk blank upon a turntable, scoring the surface of
the concave convex portion with a wire of a wire electrical
discharging machine, and wherein the wire is renewed as the score
is formed.
[0015] In one embodiment, the wire can be between about 0.004 and
0.0012 inches in diameter.
[0016] In one embodiment, the wire can be about 0.0010 inches in
diameter.
[0017] In one embodiment, the wire can be positioned generally
parallel to a plane defined by the peripheral skirt.
[0018] In one embodiment, the score formed can have a cross section
that is asymmetrical in transverse cross section.
[0019] In one embodiment, the score formed can have surfaces that
are of different curvatures in transverse cross section.
[0020] In one embodiment, the score formed can have a generally
flat surface.
[0021] In one embodiment, the wire can be positioned along a line
that forms an acute angle with the surface of the disk blank being
scored.
[0022] In one embodiment, the disk blank can have a thickness of
between 0.003 and 0.125 inches.
[0023] In one embodiment, the disk blank can have a thickness of
between about 0.003 and 0.375 inches.
[0024] In one embodiment, the distance between the wire and the
peripheral flange can be between about 0.020 and 2.0 inches.
[0025] In one embodiment, a convex surface of the disk blank can be
scored.
[0026] In one embodiment, the disk blank has a central axis and
wherein the score can extend less than 360 degrees around the disk
blank central axis.
[0027] In one embodiment, rotation of the turntable can be
controlled by the wire electrical discharge machine.
[0028] In one embodiment, movement of the wire can be controlled by
the wire electrical discharge machine.
[0029] The present invention includes a method of constructing a
rupture disk. The method of the present invention includes
providing a disk blank having a central axis, a peripheral flange
and a concave convex portion that is surrounded by the peripheral
flange, rotating the disk blank and a cutting wire relative to each
other, scoring the surface of the concave convex portion with the
wire, wherein the wire is an electrical discharging machine wire,
and wherein the wire is advanced radially as the score is
formed.
[0030] In one embodiment, the wire can be positioned to cut only
partially through the disk blank.
[0031] In one embodiment, the disk blank can be supported upon a
tool and wherein rotation of the tool can be controlled by the wire
electrical discharge machine.
[0032] In one embodiment, movement of the wire can be controlled by
the wire electrical discharge machine.
[0033] In one embodiment, the disk blank can be supported by a tool
and wherein the tool engages the disk concave convex portion.
[0034] In one embodiment, the disk blank can be supported by a tool
and wherein the tool engages the disk peripheral flange.
[0035] In one embodiment, the present invention further comprises
the step of forming an asymmetrical transverse cross section score
on the disk blank.
[0036] In one embodiment, the present invention further comprises
the step of supporting the disk blank on a tool.
[0037] In one embodiment, the present invention further comprises
the step of engaging the tool to the disk peripheral flange.
[0038] In one embodiment, the present invention further comprises
the step of engaging the tool to the disk concave convex
portion.
[0039] In one embodiment, the present invention further comprises
the step of engaging the tool to both the disk peripheral flange
and the disk concave convex portion.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0040] For a further understanding of the nature, objects, and
advantages of the present invention, reference should be had to the
following detailed description, read in conjunction with the
following drawings, wherein like reference numerals denote like
elements and wherein:
[0041] FIG. 1 is a sectional view illustrating a preferred method
of the present invention;
[0042] FIG. 2 is an end view of the method and apparatus of the
present invention;
[0043] FIG. 3 is an enlarged partial sectional view of the method
of the present invention showing disk, score and EDM wire;
[0044] FIG. 4 is a sectional view of a preferred embodiment of the
apparatus of the present invention;
[0045] FIG. 5 is a plan view of a preferred embodiment of the
apparatus of the present invention; and
[0046] FIG. 6 is an enlarged fragmentary view of a preferred
embodiment of the apparatus of the present invention and showing
the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0047] FIGS. 1-6 show a preferred embodiment of the apparatus of
the present invention, designated generally by the numeral 10 in
FIGS. 1-2 and 4-5. The method of the present invention includes the
step of rotating a disk blank 11 (that is mounted upon a tool or
tool base 18) and a cutting wire 21 relative to one another.
Simultaneously, the cutting wire (preferably an electrical
discharge machining wire or "EDM" wire) 21 is moved toward the
central axis 27 of the disk blank 11. The method of the present
invention places the wire 21 in a selected position, such as for
example generally parallel to the disk blank peripheral skirt or
flange 12 as shown in FIGS. 3 and 5. A relative rotation of the
disk blank 11 and wire 21, coupled with movement of the EDM wire 21
toward the disk central axis 27 (see FIGS. 1, 5 and arrows 31 in
FIGS. 5, 6) can be precisely controlled by the motion control
system of a commercially available EDM apparatus. Such EDM
apparatus are commercially available from Mitsubishi and Fanuc, as
examples. With the method of the present invention, a precise score
22 can be cut a partial distance through the disk blank 11 and
preferably, through the concave convex dome portion 15 of the disk
blank 11. This cut or score 22 is preferably performed on the
convex surface 16 of the concave convex central disk or dome
portion 15. The precisely cut score 22 can be positioned near the
transition from the concave convex dome portion 15 to the flange or
skirt 12 and can be in a generally "c" shaped score pattern 28 (see
FIG. 5).
[0048] In FIGS. 1-6, rupture disk apparatus 10 is formed from a
disk blank 11 that has a peripheral skirt or flange 12 and a
concave convex central dome portion 15. The peripheral skirt or
flange 12 has an upper surface 13 and a lower surface 14.
Peripheral skirt or flange 12 preferably forms a plane 29. Concave
convex dome portion 15 provides a convex surface 16 and a concave
surface 17. In a preferred embodiment, the concave convex dome
portion 15 is scored. A precise score transverse or radial cross
section 25 in FIG. 6 is cut partway through the disk blank
thickness as indicated by the arrow 26. The transverse or radial
cross section 25 includes a larger generally flat score surface 23
and a smaller generally flat or curved score surface 24. These
surfaces 23, 24 can form an angle of about 90 degrees. Surfaces 23,
24 are joined with a curved surface 30 that has about the same
curvature as the curvature of the outer surface of the EDM wire 21
(see FIG. 6).
[0049] The disk blank 11 is mounted upon a disk fixture, tool or
tool holder base 18. In FIG. 1, tool base 18 provides a disk
fixture part 20. As part of a preferred embodiment of the method of
the present invention, tool 18 supports disk blank 11. Disk fixture
part 20 of tool 18 engages peripheral flange 12, concave convex
disk portion 15 or both peripheral flange 12 and concave convex
disk portion 15. A vacuum applied to channel 19 can be used to hold
or engage disk blank 11 to fixture 20.
[0050] As part of the method of the present invention, an
electrical discharge machining wire 21 is moved toward the axis 27
of the disk blank 11 while maintaining the wire 21 in a selected
position such as parallel to the plane 29 of flange or skirt 12 of
the disk blank 11.
[0051] The tool base 18 and disk fixture 20 are rotated, the disk
blank 11 rotating with the disk fixture 20. The rotation of the
disk blank 11 and wire 21 relative to one another and the movement
of the wire 21 toward the disk blank 11 can be controlled by the
motion system of a commercially available EDM machine. Such
machines are commercially available from Mitsubishi or Fanuc. Such
EDM machines have been patented. Examples can be seen in U.S. Pat.
Nos. 7,013,195; 7,038,158; 6,875,943; 6,855,904; 6,621,033, each of
these patents being hereby incorporated herein by reference.
[0052] In FIG. 5, a score pattern 28 that is generally "c" shaped
is shown. It should be understood, however, that patterns other
than a "c" shaped pattern could be cut as well. Score 22 creates a
pattern of weakness so that the disk 10 will open in either the
forward or the reverse buckling direction at a selected design
pressure value.
[0053] The wire 21 is constantly renewed during machining of the
score 22. Changes in score 22 depth or in score shape or pattern 28
can be modified using programming associated with the commercially
available EDM machine. Commercially available EDM equipment can be
used with a controlled rotary table to cut multiple disk sizes.
Tooling to hold the disk blank 11 of a particular size on a rotary
table could be provided for different disk sizes. The same tooling
could be used for example for all thicknesses and disk
materials.
[0054] Disk fixture 20 supports rupture disk 10. Disk fixture 20
can support flange 12. Disk fixture 20 can support concave convex
central disk portion 15 (see connection 32 in FIG. 6). Disk fixture
20 can support rupture disk 10 at both flange 12 and concave convex
portion 15.
[0055] The following is a list of parts and materials suitable for
use in the present invention.
TABLE-US-00001 PARTS LIST Part Number Description 10 rupture disk
apparatus 11 disk blank 12 peripheral skirt or flange 13 upper
surface 14 lower surface 15 concave convex central disk or dome
portion 16 convex surface 17 concave surface 18 disk fixture, tool,
tool base or tool holder base 19 vacuum line channel 20 disk
fixture part 21 cutting wire or EDM wire 22 score 23 larger score
surface 24 smaller score surface 25 score transverse/radial cross
section 26 arrow 27 axis 28 score pattern 29 plane 30 curved
surface 31 arrow 32 connection
[0056] All measurements disclosed herein are at standard
temperature and pressure, at sea level on Earth, unless indicated
otherwise. All materials used or intended to be used in a human
being are biocompatible, unless indicated otherwise.
[0057] The foregoing embodiments are presented by way of example
only; the scope of the present invention is to be limited only by
the following claims.
* * * * *