U.S. patent application number 10/541506 was filed with the patent office on 2006-06-15 for lubricants suitable for hydroforming and other metal manipulating applications.
Invention is credited to Frank K. Botz, Paul B. Kutzko.
Application Number | 20060128573 10/541506 |
Document ID | / |
Family ID | 32711122 |
Filed Date | 2006-06-15 |
United States Patent
Application |
20060128573 |
Kind Code |
A1 |
Botz; Frank K. ; et
al. |
June 15, 2006 |
Lubricants suitable for hydroforming and other metal manipulating
applications
Abstract
The present invention discloses a hydroforming process for metal
parts that uses liquid-film and solid-film lubricants. The
lubricants used in the invention are particularly useful for
die-side lubrication. The process includes a step in which a
ductile metal part is over-coated with either the liquid-film or
solid-film lubricant. The liquid lubricants preferably include an
oil and a optionally a surfactant. The solid lubricants preferably
include a hard wax and optionally a surfactant.
Inventors: |
Botz; Frank K.; (Canton,
MI) ; Kutzko; Paul B.; (Livonia, MI) |
Correspondence
Address: |
HENKEL CORPORATION
THE TRIAD, SUITE 200
2200 RENAISSANCE BLVD.
GULPH MILLS
PA
19406
US
|
Family ID: |
32711122 |
Appl. No.: |
10/541506 |
Filed: |
December 30, 2003 |
PCT Filed: |
December 30, 2003 |
PCT NO: |
PCT/US03/41577 |
371 Date: |
January 17, 2006 |
Current U.S.
Class: |
508/517 |
Current CPC
Class: |
C10M 2205/18 20130101;
C10M 2215/042 20130101; C10M 2207/021 20130101; C10N 2050/01
20200501; C10M 2205/17 20130101; C10M 2209/104 20130101; C10M
169/041 20130101; C10M 2207/126 20130101; C10M 2207/404 20130101;
C10M 2207/40 20130101; C10M 2207/125 20130101; C10M 2205/163
20130101; C10N 2040/241 20200501; C10M 2201/062 20130101; C10M
2209/107 20130101; C10M 2205/16 20130101; C10M 2207/2815 20130101;
C10M 2207/402 20130101; C10M 2209/109 20130101; C10N 2050/02
20130101; C10M 2205/123 20130101; C10M 2207/284 20130101; C10N
2040/24 20130101; C10M 2207/2845 20130101; C10M 2209/108 20130101;
C10M 2209/12 20130101; C10M 2207/243 20130101; C10M 2211/04
20130101; B21D 26/033 20130101; C10M 2207/0215 20130101; C10M
2207/401 20130101; C10M 173/00 20130101; C10M 2201/02 20130101;
C10M 2207/141 20130101; C10M 2205/173 20130101; B21D 26/057
20130101; C10N 2060/04 20130101; C10M 2205/183 20130101; C10M
2205/14 20130101; C10M 2207/4045 20130101; C10N 2030/06 20130101;
C10M 2207/129 20130101; C10M 2207/281 20130101; B21D 26/035
20130101; C10M 169/04 20130101; C10M 2205/143 20130101; C10M
2209/10 20130101; C10M 2203/1065 20130101; C10M 2219/044 20130101;
C10M 2207/141 20130101; C10N 2010/02 20130101; C10M 2209/104
20130101; C10M 2209/108 20130101; C10M 2209/104 20130101; C10M
2209/105 20130101; C10M 2209/104 20130101; C10M 2209/109 20130101;
C10M 2207/141 20130101; C10N 2010/02 20130101 |
Class at
Publication: |
508/517 |
International
Class: |
C10M 173/02 20060101
C10M173/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 9, 2003 |
US |
10/339,523 |
Claims
1. A process for hydroforming a tube of ductile solid material, the
process comprising: (I) providing a pressure-side fluid and an
openable die having an interior surface of a shape to which it is
desired to have the hydroformed part of the outer surface of the
tube of ductile solid material conform after the tube has been
hydroformed; (II) forming over the outer surface of the tube of
ductile solid material a coating of a die-side lubricant selected
from the group consisting of: 1. a liquid lubricant comprising an
oil and a surfactant; 2. a solid lubricant comprising a wax wherein
the stress value within the solid die-side lubricant 0.75 sec after
the compressive stress began to be imposed is at least 500 kPa; the
stress value within the solid die-side lubricant 100 sec. after the
compressive stress began to be imposed is at least 300 kPa; and the
residual stress within the solid die-side lubricant 100 sec after
the compressive stress began to be imposed is at least 75 percent
of the maximum stress induced within the solid lubricant at any
time up to 100 sec after the stress began to be imposed; and 3.
mixtures thereof. (III) emplacing the coated ductile tube within at
least a part of said openable die and closing the die, so that a
portion of the outer surface of the ductile tube that is desired to
be hydroformed is within the closed openable die; (IV) filling the
interior of the tube of ductile solid with a volume of said
pressure-side fluid, so that said pressure-side fluid exerts
essentially equal pressure on all parts of the internal surface of
the tube of ductile solid with which the pressure-side fluid is in
physical contact; and (V) applying to said volume of pressure-side
fluid filling said interior of the ductile tube, while the ductile
tube remains emplaced within the closed openable die as recited in
operation (III) above, a sufficient pressure to cause at least a
portion of the outer surface of the coated ductile tube to conform
to the inner surface of the closed openable die.
2-7. (canceled)
8. The process of claim 1, wherein the oil is selected from the
group consisting of vegetable oils, blown vegetable oils, polymers
of vegetable oils, animal oils, and blown animal oils, and mixtures
thereof.
9. The process of claim 1, wherein the oil is selected from the
group consisting of blown canola oil, blown fish oil, canola oil,
blown rapeseed oil, naphthenic oil, and mixtures thereof.
10. The process of claim 1, wherein the surfactant is a non-ionic
surfactant.
11. The process of claim 10, wherein the surfactant is selected
from the group consisting of vegetable oil ethoxylates, ethoxylates
of alkyl alcohols, ethoxylates of acetylenic diols, block
copolymers of ethylene and propylene oxides, ethoxylates of alkyl
carboxylates, alkyl polyglycosides, and mixtures thereof.
12. (canceled)
13. The process of claim 10, wherein the surfactant is present in
an amount of about 1.0% to 5% of the total weight of the liquid
film composition.
14. (canceled)
15. The process of claim 1, wherein the wax is selected from the
group consisting of carnauba wax, candelilla wax, montan wax,
microcrystalline waxes, solid alcohols, solid esters, and oxidized
petroleum waxes.
16. The process of claim 1, wherein the wax is a primary alcohol
having at least 18 carbon atoms per molecule.
17. The process of claim 1, wherein the wax is an ester of a
primary alcohol having at least 18 carbon atoms per molecule with
an organic acid.
18. The process of claim 1, wherein the organic acid is an
unbranched monoacid, having at least 18 carbon atoms per
molecule.
19. The process of claim 1, wherein the solid lubricant further
comprises a surfactant.
20. The process of claim 19, wherein the surfactant is a non-ionic
surfactant.
21. The process of claim 19, wherein the surfactant is selected
from the group consisting of vegetable oil ethoxylates, ethoxylates
of alkyl alcohols, ethoxylates of acetylenic diols, block
copolymers of ethylene and propylene oxides, ethoxylates of alkyl
carboxylates, alkyl polyglycosides, and mixtures thereof.
22. The process of claim 19, wherein the surfactant is present in
an amount of about 0.05% to 10% of the total weight of the dry film
composition.
23. The process of claim 19, wherein the surfactant is present in
an amount of about 1.0% to 5% of the total weight of the dry film
composition.
24. (canceled)
25. The process of claim 1, wherein the solid lubricant further
comprises a wetting agent.
26. The process of claim 25 wherein the wetting agent is selected
from the group consisting of nonionic fluorosurfactants, anionic
fluorosurfactants, ethoxylated tetramethyldecynediols, acetylenic
glycol-based surfactants, dialkylsulfosuccinates, and mixtures
thereof.
27. (canceled)
28. The process of claim 25 wherein the wetting agent is present in
an amount of 0.01% to 1.0% of the weight of the dry film
composition.
29. The process of claim 25 wherein the wetting agent is present in
an amount of 0.1% to 0.5% of the weight of the dry film
composition.
30. A liquid film lubricant comprising: an oil; and a surfactant,
wherein the liquid film lubricant has the characteristic that the
coefficient of friction is reduced when the liquid film lubricant
is wetted as compared to the coefficient of friction of the liquid
film lubricant is unwetted.
31-37. (canceled)
38. A solid film lubricant comprising: a wax; and a surfactant,
wherein the solid film lubricant has the characteristic that the
coefficient of friction is reduced when the solid film lubricant is
wetted as compared to the coefficient of friction of the solid film
lubricant is unwetted.
39-41. (canceled)
42. The solid film lubricant of claim 38, wherein the organic acid
is an unbranched monoacid, having at least 18 carbon atoms per
molecule.
43-44. (canceled)
45. The solid film lubricant of claim 38, wherein the surfactant is
present in an amount of about 0.05% to 10% of the total weight of
the dry film composition.
46. (canceled)
47. (canceled)
48. The solid film lubricant of claim 38 further comprising a
wetting agent.
49. The solid film lubricant of claim 48 wherein the wetting agent
is selected from the group consisting of nonionic
fluorosurfactants, anionic fluorosurfactants, ethoxylated
tetramethyldecynediols, dialkylsulfosuccinates, and mixtures
thereof.
50. (canceled)
51. The solid film lubricant of claim 48 wherein the wetting agent
is present in an amount of 0.01% to 1.0% of the weight of the dry
film composition.
52. The solid film lubricant of claim 48 wherein the wetting agent
is present in an amount of 0.1% to 0.5% of the weight of the dry
film composition.
53. A solid film lubricant comprising: a wax; and a wetting agent,
wherein the solid film lubricant has the characteristic that the
coefficient of friction is reduced when the solid film lubricant is
wetted as compared to the coefficient of friction of the solid film
lubricant is unwetted.
54. (canceled)
55. (canceled)
56. The solid film lubricant of claim 53, wherein the wax is an
ester of a primary alcohol having at least 18 carbon atoms per
molecule with an organic acid.
57. (canceled)
58. (canceled)
59. (canceled)
60. (canceled)
61. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S.
application Ser. No. 09/957,911 filed Sep. 21, 2001 which, in turn,
claims the benefit of U.S. Provisional Application Ser. No.
60/234,833, filed Sep. 22, 2000.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to lubricants used in metal forming
processes and, in particular, to lubricants used in hydroforming
processes.
[0004] 2. Background Art
[0005] Processes in which metal parts are manipulated or formed
typically require lubricants to reduce equipment wear. These
processes include such operations as bending, swaging,
roll-tapping, drawing, and hydroforming. Hydroforming is a
particularly important process in which a relatively complex metal
part is fabricated.
[0006] There are two types of hydroforming processes. One is used
to form parts from sheet metal and the other is used to form parts
from metal tubes. Many tube hydroforming applications are currently
utilized by the automotive industry.
[0007] In a tube hydroforming process, a workpiece tube is placed
in a tool cavity. The geometry of the die cavity corresponds to the
external geometry of the produced part. The tool cavity is closed
by the ram movement of a press. At the same time, the tube ends are
loaded by two punches moving along the tube axis, and an aqueous
fluid is pumped into the tube. As the internal pressure of this
pressure-side aqueous fluid is increased, the tube expands until
the expanding tube wall contacts the inner surface of the die, and
the part is formed.
[0008] There are three types of lubricants involved in the tube
hydroforming process: a bending lubricant, the pressure-side
aqueous fluid mentioned above, and a die-side lubricant that is
used between the workpiece tube and the die. The bending lubricant
is used on the inside of the tube to bend the tube into a desired
shape just prior to mounting the tube in the hydroforming tool
cavity. The pressure-side fluid is the aqueous hydraulic fluid used
to transmit the pressure to the inside of the tube. Although little
lubricity is required of the pressure-side fluid, other properties,
such as corrosion protection, high pressure stability, and the
ability to reject the bending and die-side lubricants, are
important to the performance. The die-side lubricant is the primary
forming fluid in high-pressure hydroforming. It provides the
lubricity between the workpiece and the die.
[0009] The demands on the die-side lubricant vary widely. Some
light duty applications require little of the die-side lubricant.
In the case of lower pressure applications, the pressure-side fluid
may also be used simultaneously to transmit pressure inside the
tube and to provide die-side lubrication. As the complexity of the
application increases, the importance of the die-side lubricant
increases. Furthermore, the die-side lubricants' compatibility with
the pressure-side lubricant and the removal of the die-side
lubricant from the newly formed part are important
considerations.
SUMMARY OF THE INVENTION
[0010] The present invention discloses a liquid film die-side
hydroforming lubricant that comprises an oil and a surfactant. The
liquid film die-side lubricant is typically already a liquid when
applied to the workpiece tube. Preferably, the liquid film die-side
lubricant has lubrication properties that are not substantially
damaged by contact with the pressure-side fluid which usually
contains water. Furthermore, the liquid film die-side lubricant
preferably has high viscosity.
[0011] In accordance with another aspect of the present invention,
a solid film die-side hydroforming lubricant is disclosed. The
solid film die-side lubricant comprises a wax such that the stress
value within the die-side lubricant is at least 540 kPa at 0.75 sec
after a compressive stress is imposed. Preferably, the solid film
die-side lubricant is a liquid when applied to the workpiece tube.
The applied liquid then either dries or cures into a solid
lubricating film. The solid film die-side lubricant has lubrication
properties that are not substantially damaged by contact with the
pressure-side fluid, which usually contains water. Furthermore, the
liquid film die-side lubricant preferably has high viscosity. When
the die-side lubricant of the present embodiment is a solid at the
time of emplacement, the die-side lubricant preferably has high
hardness and optionally a high elasticity. The solid film lubricant
also optionally includes a wetting agent to improve the ability of
the composition to wet metallic surfaces.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] Reference will now be made in detail to presently preferred
compositions or embodiments and methods of the invention, which
constitute the best modes of practicing the invention presently
known to the inventor.
[0013] For purposes of the present invention, the resistance of a
lubricant to damage to its lubrication properties by pressure-side
fluid is most conveniently measured by measuring the coefficient of
friction of two metal surfaces, lubricated with the die-side
lubricant to be measured, in a sliding friction test at a pressure
from 65 to 400 bars and in a twist compression test at a pressure
from 675 to 2500 bars. A die-side lubricant to be tested is first
placed on one surface of a substrate of the same type of metal as
is to be hydroformed in the same manner as if the substrate were to
be hydroformed, but the substrate in this instance has a shape
suitable for the intended method of measurement of coefficient of
friction. After the coefficient of friction has been measured, the
die-side lubricant layer is sprinkled or otherwise gently wet with
the intended pressure-side fluid for hydroforming or a surrogate
for this pressure-side fluid, plain deionized or tap water often
being an effective surrogate. A volume of the pressure-side fluid
or surrogate therefor that is not more than about twice the volume
of the wetted die-side lubricant film itself should be used, and no
substantial mechanical force such as would result from high
pressure spraying should be used. After a minute or two of contact
between the lubricant layer and the pressure-side fluid or
surrogate therefor, any remaining aqueous liquid is allowed to
drain away under the influence of natural gravity, and the
coefficient of friction of the substrate bearing the thus-drained
die-side lubricant film is again measured. The die-side lubricant
has sufficient pressure-side fluid-resistance for the purposes of
this invention when the coefficient of friction measured with the
thus wetted and drained die-side lubricant film does not exceed the
coefficient of friction measured under the same conditions with the
originally emplaced and unwetted die-side lubricant film by an
amount that is preferably more than about 50 percent of the value
of the coefficient of friction for the originally emplaced and
unwetted die-side lubricant film, more preferably more than about
30 percent of the value of the coefficient of friction for the
originally emplaced and unwetted die-side lubricant film, and most
preferably more than about 1.0 percent of the value of the
coefficient of friction for the originally emplaced and unwetted
die-side lubricant film. In particularly favorable instances, the
coefficient of friction is reduced by contact with the
pressure-side fluid or surrogate therefor. All of the measurements
involved in this determination of the pressure-side fluid
resistance of a lubricant should be made at the intended
temperature of the hydroforming process itself, or, if the latter
is unknown, at a normal ambient human comfort temperature (between
18 and 23.degree. C.).
[0014] In one embodiment of the present invention, a liquid film
die-side hydroforming lubricant is disclosed. The liquid film
die-side lubricant is typically already a liquid when applied to
the workpiece tube. The liquid film die-side lubricant has
lubrication properties that are not substantially damaged by
contact with the pressure-side fluid as defined above. Furthermore,
the liquid film die-side hydroforming lubricant includes an oil
that has a kinematic viscosity measured at 40.degree. C., that is
at least, with increasing preference in the order given, 2.5, 5.0,
7.5, 10.0, 12.5, 15.0. 17.5, or 20 stokes. Suitable commercially
available oils include vegetable oils, blown (alternatively called
"oxidized") vegetable oils, polymers of vegetable oils, animal
oils, and blown animal oils along with typical petroleum oils.
Specific examples include blown canola oil, blown fish oil, canola
oil, blown rapeseed oil, and naphthenic oil.
[0015] The liquid film die-side hydroforming lubricant ("liquid
film composition") of the present invention optionally further
include a surfactant. The surfactant improves the cleaning
properties of the lubricant, i.e., the ease of removing residual
lubricant. Although any surfactant may be utilized, preferably
non-ionic surfactants are used. The surfactant also preferably
improves the lubricity of the liquid film when wetted. Though not
restricting the improvement of lubricity to any particular
mechanism, the surfactant appears to form an emulsified layer when
wetted that enhances lubricity. However, the amount of surfactant
is not so much that the liquid film is deteriorated during
emulsification. The surfactant is preferably present in an amount
of 0.1% to 10% of the total weight of the liquid film composition,
more preferably in an amount of 1.0% to 5% of the total weight of
the liquid film composition, and most preferably in an amount of
about 2.5% of the total weight of the liquid film composition.
Preferred surfactants include vegetable oil ethoxylates,
ethoxylates of alkyl alcohols, ethoxylates of acetylenic diols,
block copolymers of ethylene and propylene oxides, ethoxylates of
alkyl carboxylates such as typical fatty acids, alkyl
polyglycosides, and mixtures thereof. Examples include but are not
limited to Chemal DA-6, Chemal DA-9, Chemal LA-4, Chemax CO-5,
Chemax CO-16, Chemax CO-25, Chemax CO-30, Chemax CO-36, Chemax
CO-40, Chemax CO-80, and Chemax CO-200/50 commercially available
from Chemax, Inc. located in Greenville, S.C. Suitable surfactants
also include but are not limited to Surfynol 440 commercially
available from Air Products, TOMAH E-14-5 (poly (5) oxyethylene
isodecyloxypropylamine) and TOMAH E-14-2 commercially available
from Tomah Products Inc. located in Milton, Wis.; NINOL 11CM (a
modified coconut diethanolamide surfactant sold by Stepan, Inc.)
TRITON X-100 (octylphenol ethylene oxide condensate; Octoxynol-9)
commercially available from Union Carbide; and APG 325 CS (decyl
polyglucoside) commercially available from Cognis Corporation
located in Cincinnati, Ohio. Other suitable non-ionic surfactants
include block surfactants containing polyoxypropylene hydrophobe(s)
and polyoxyethylene hydrophile(s). In order to properly function,
the surfactant must be soluble or dispersible in the lubricant. The
blocks may be homopolymeric or copolymeric, for example copolymers
derived from oxyalkylating with mixtures of ethylene oxide and
propylene oxide. Such surfactants are available from numerous
sources, including the Pluronic.RTM., Tetronic.RTM., and
Pluronic.RTM. R polyether surfactants from BASF Corporation.
[0016] In another embodiment of the present invention, a solid film
die-side hydroforming lubricant ("solid film composition") is
disclosed. Typically, the solid film lubricant will be applied to a
surface as a liquid which is subsequently dried and cured. The
resultant solid lubricant of the present invention preferably has a
hardness as measured at 23-26.degree. C. by the American Society
for Testing and Materials ("ASTM") Procedure Number D-5 that is not
more than, with increasing preference in the order given, 50, 40,
30, 20, 15, 13, 11, 9, 7, 5, or 3. The solid film lubricant of the
present invention includes solid lubricants that are characterized
by one or more of the following properties when subjected to a
compressive stress within the range from 1.50 to 2.00 percent over
a time interval of 0.20 to 0.30 seconds at 23-26.degree. C.: [0017]
the stress value within the solid die-side lubricant 0.75 sec after
the compressive stress began to be imposed is at least, with
increasing preference in the order given, 500, 510, 520, 530, 540,
550, 560, 570, or 580 kiloPascals (this unit of stress being
hereinafter usually abbreviated as "kPa"); [0018] the stress value
within the solid die-side lubricant 100 sec. after the compressive
stress began to be imposed is at least, with increasing preference
in the order given, 300, 350, 400, 450, 500, 510, 520, 530, 540, or
550 kPa; and [0019] the residual stress within the solid die-side
lubricant 100 sec after the compressive stress began to be imposed
is at least, with increasing preference in the order given, 75, 80,
82, 84, 86, 88, or 90 percent of the maximum stress induced within
the solid lubricant at any time up to 100 sec after the stress
began to be imposed. A method of measuring these stress values is
described by T H. Sheilhammer, T. R. Rumsey, and J. M. Krochia in
"Viscoelastic Properties of Edible Lipids," JOURNAL OF FOOD
ENGINEERING 33 (1997), pages 305-320. This paper is hereby
incorporated herein by reference to the extent that it is not
inconsistent with any explicit statement herein. Preferred solid
film lubricants include carnauba wax; candelilia wax; montan wax;
microcrystalline waxes; solid alcohols, particularly primary
alcohols having at least 18 carbon atoms per molecule; solid
esters, particularly esters of primary alcohols having at least 18
carbon atoms per molecule with organic acids, especially unbranched
monoacids, having at least 18 carbon atoms per molecule; and
oxidized petroleum waxes.
[0020] The solid film die-side hydroforming lubricant of the
present invention optionally further includes a surfactant.
Although any surfactant may be utilized, preferably non-ionic
surfactants are used. The surfactant also preferably improves the
lubricity of the solid film when wetted. The surfactant is
preferably present in an amount of 0.05% to 10% of the total weight
of the solid film composition, more preferably in an amount of 0.1%
to 5% of the total weight of the solid film composition, and most
preferably in an amount of about 1% of the total weight of the
solid film composition. Preferred surfactants include vegetable oil
ethoxylates, ethoxylates of alkyl alcohols, ethoxylates of
acetylenic diols, block copolymers of ethylene and propylene
oxides, ethoxylates of alkyl carboxylates such as typical fatty
acids, alkyl polyglycosides, and mixtures thereof. Suitable
surfactants also include but are not limited to Surfynol 440
commercially available from Air Products, TOMAH E-14-5 (poly (5)
oxyethylene isodecyloxypropylamine) and TOMAH E-14-2 commercially
available from Tomah Products Inc. located in Milton, Wis.; NINOL
11CM (a modified coconut diethanolamide surfactant sold by Stepan,
Inc.) TRITON X-100 (octylphenol ethylene oxide condensate;
Octoxynol-9) commercially available from Union Carbide; and APG 325
CS (decyl polyglucoside) commercially available from Cognis
Corporation located in Cincinnati, Ohio. Other suitable non-ionic
surfactants include block surfactants containing polyoxypropylene
hydrophobe(s) and polyoxyethylene hydrophile(s). The blocks may be
homopolymeric or copolymeric, for example copolymers derived from
oxyalkylating with mixtures of ethylene oxide and propylene oxide.
Such surfactants are available from numerous sources, including the
Pluronic.RTM., Tetronic.RTM., and Pluronic.RTM. R polyether
surfactants from BASF Corporation.
[0021] The solid film die-side lubricant optionally comprises a
wetting agent. Utilization of such agents improves the ability of
the dry film composition (which is a liquid when applied) to wet
metals such as the various steel alloys (stainless steel, hot
rolled steel, and cold rolled steel), aluminum alloys, titanium,
and copper. It will be recognized by those skilled in the art, that
many wetting agents are surfactants and many surfactants are
wetting agents. Accordingly, a subset of the surfactants listed
above will also function as wetting agents. Suitable wetting agents
include, but are not limited to, nonionic fluorosurfactants,
anionic fluorosurfactants, ethoxylated tetramethyldecynediols,
acetylenic glycol-based surfactants, dialkylsulfosuccinates, and
mixtures thereof. Suitable ethoxylated tetramethyldecynediols
include members of the Surfynol 400 series such as Surfynol 440 and
420 commercially available from Air Products. An exemplary
acetylenic glycol-based surfactant is Dynol 604 commercially
available from Air Products. Suitable dialkylsulfosuccinates
include dioctylsulfosuccinates. The preferred wetting agent is a
fluorosurfactant which includes both nonionic fluorosurfactants and
an anionic fluorosurfactants. Most preferably the wetting agent is
a nonionic fluorosurfactant. Suitable nonionic fluorosurfactants
include fluoroaliphatic ethoxylates and related derivatives.
Specifically, Clariant Fluowet OTN and DuPont Zonyl FSN 100 are
nonionic surfactants that performed well. Fluowet OTN is a
proprietary fluoroaliphatic ethoxylate commercially available from
Clariant. Zonyl FSN 100 is a Telomer B monoether with polyethylene
glycol which is a 1:1 mixture of poly(oxy-1,2-ethandiyl),
.alpha.-hydro-.OMEGA.-hydroxy-ether with
.alpha.-fluoro-.OMEGA.-(2-hydroxyethyl)poly(difluoromethylene).
Suitable anionic fluorosurfactants include fluoroalkylsulfonates
and carboxylates with a range of counter ions that include
potassium, sodium, and amines. Preferably, the fluorosurfactant is
present in an amount of about 0.1% to 1.0% by weight of the dry
film composition. More preferably, the fluorosurfactant is present
in an amount of about 0.1% to 0.5% by weight of the dry film
composition.
[0022] The solid film die-side lubricant also optionally includes a
corrosion inhibitor and/or a defoamer. Suitable defoamers include
neo-decanoic acid. Suitable corrosion inhibitors include soaps or
salts of carboxylic acids or organo-sulfonates. Agents capable of
adjusting the pH of the lubricant may also be included, such as,
for example, amines (e.g., alkanolamines).
[0023] Regardless of whether the die-side lubricant is solid or
liquid at the time of emplacement or whether the die-side lubricant
has an aqueous-based liquid after being emplaced, the coefficient
of sliding friction between two metal surfaces with a layer between
them of a die-side lubricant to be used in a process according to
the invention preferably is not more than about 0.3 to 0.5, more
preferably is not more than about 0.1 to 0.3, and most preferably
is not more than about 0.04 to 0.1.
[0024] Furthermore, the die-side lubricant is preferably capable of
being readily cleaned from the hydroformed object after
hydroforming is complete, preferably with an aqueous-based cleaner.
Preferably, the die-side lubricant is capable of being cleaned at a
temperature not higher than 55.degree. C., more preferably a
temperature not higher than 40.degree. C., and most preferably at a
temperature not higher than 28.degree. C. This preference is not
inconsistent with the need for pressure-side fluid resistance of
the die-side lubricant as described above. Typical aqueous based
cleaners are either more acidic or more alkaline than most aqueous
pressure-side fluids used in hydroforming. Furthermore, even if the
cleaners are neutral, they usually contain other cleaning-promoting
ingredients such as detersive surfactants that are not present in
typical pressure-side fluids for hydroforming.
[0025] The die-side lubricant is also preferably easy to separate
from the pressure-side fluid should the lubricant become
contaminated by the pressure-side fluid. Accordingly,
self-segregation of the die-side lubricant into a separate phase
that can be skimmed or drained off from a reservoir of
pressure-side fluid is highly desirable.
[0026] Finally, the lubricant is preferably easy to apply to the
surface to be lubricated, without producing any hazard such as
flammable, toxic, or noxious fumes, without requiring any equipment
more complicated than simple spray, immersion, and/or roll coating,
and without requiring any special drying equipment. For example, if
a die-side lubricant that is a solid when emplaced ready for use
can be applied from a latex and allowed to dry in the ambient air
without producing any fire hazard or unpleasant odor, there is a
substantial practical advantage and therefore a preference for it
over a solid die-side lubricant that must be melted to be applied
and then quickly cooled to avoid having the melted die-side
lubricant run off the substrate being hydroformed.
[0027] In another embodiment of the present invention, a process
for hydroforming a tube of a ductile solid material is provided.
The process comprises the following steps: [0028] (I) providing a
pressure-side fluid and an openable die having an interior surface
of a shape to which it is desired to have the hydroformed part of
the outer surface of the tube of ductile solid material conform
after the tube has been hydroformed; [0029] (II) forming over the
outer surface of the tube of ductile solid material a coating of a
die-side lubricant suitable for use in a process according to the
invention as described above, so as to form a coated ductile tube;
[0030] (III) emplacing the coated ductile tube within at least a
part of said openable die and closing the die, so that a portion of
the outer surface of the ductile tube that is desired to be
hydroformed is within the closed openable die; [0031] (IV) filling
the interior of the tube of ductile solid with a volume of said
pressure-side fluid, so that said pressure-side fluid exerts equal
pressure on all parts of the internal surface of the tube of
ductile solid with which the pressure-side fluid is in physical
contact; and [0032] (V) applying to said volume of pressure-side
fluid filling said interior of the ductile tube, while the ductile
tube remains emplaced within the closed openable die as recited in
operation (III) above, a sufficient pressure to cause at least a
portion of the outer surface of the coated ductile tube to conform
to the inner surface of the closed openable die.
[0033] Only a relatively thin layer of the die-side lubricant is
needed for satisfactory lubrication. More particularly, the average
thickness of the die-side lubricant layer formed before
hydroforming begins preferably is in the range 0.2 to 200 microns,
more preferable in the range 1.0 to 100 microns, and most
preferably about 15 microns. Uniformity of the die-side lubricant
is not critical. The films may even be discontinuous ball-like
lumps and aggregates evenly distributed over the surface of the
part.
[0034] Preferred lubricants for use according to the invention can
be readily removed from surfaces of metal ductile tubes, after
hydroforming is completed, by conventional alkaline cleaners.
[0035] Except for use of the characteristic lubricant for this
invention as described above, the process conditions for a
hydroforming process according to the invention are normally the
same as those already in use in the art. A process according to the
invention is particularly advantageous in "high pressure"
hydroforming, in which the hydraulic pressure in step (V) of the
process as described above is at least 340 bars and independently
is particularly advantageous in hydroforming cold rolled steel, but
is suitable for hydroforming any other ductile solid as well.
Hydroforming with these lubes is successful with hot-rolled steel,
cold-rolled steel, and aluminum, both 5000 and 6000 series
alloys.
[0036] The invention may be further appreciated by consideration of
the following examples and comparison examples. In all of the tests
below, the metal substrate was type ADKQ 95 hot-rolled steel, which
is one of the most commonly hydroformed substrates.
Test Methods
Cornerfill Test
[0037] The cornerfill test is designed to test the properties
required by a die-side hyroforming lubricant in the expansion zone
of a hydroforming process. In these tests, the exterior surface of
a welded cylindrical steel tube was coated with test die-side
lubricant and then mounted in a die with a square cross-section
that was within one millimeter of touching the exterior
cross-section of the cylindrical steel tube at the center of all
four walls of the square die, with no weld line at or near one of
these centers of the die walls. The lubricant-coated exterior of
the steel tube was then sprayed lightly with water before the die
was closed. The interior of the steel tube was then filled with a
volume of a water-based pressure side fluid, and the pressure in
the tube was then increased until the tube burst. Sensors detected
the pressure at various stages of expansion, the maximum pressure
before the tube burst, and the maximum expansion of the tube. The
burst tube was then removed from the die, and the tube burst
location was noted. Then the dimensions of the burst tube were
measured and the true thickness strain was calculated for seven
locations: the four corners and the centers of the three walls of
the square cross-section into which the tube had expanded that did
not include the original welded area. Three of the properties
measured in this type of test are generally considered relevant to
performance in actual hydroforming. A higher burst pressure is
better than a lower one; a low standard deviation of the true
thickness strain is better than a higher one; and a burst near the
center of the tube is better than a burst in any other part of the
tube.
Twist Compression Test
[0038] A twist compression test is designated to test the
properties required by a die-side hydroforming lubricant in
transition zones near the edges of expansion zones in hydroforming.
In these tests, an annular tool was rotated under pressure over a
flat plate of steel on which the test lubricant had been emplaced.
The pressure applied on the lubricated plate in one set of tests
was 10,000 psi and in another was 15,000 psi. These pressures are
typical of commercial hydroforming of hot rolled steel tubes. A
plot of the coefficient of friction as a function of time was
generated. The results are reported at 1, 2, and 3 revolutions. The
test was first conducted dry for each lubricant and then twice
after the lubricant had been sprayed lightly with water. Only the
average of the latter two of these measurements is reported below.
The tests were also performed on lubricants sprayed with Novacool
9034, a pressure-side fluid commercially available from Henkel
Corporation, Madison Heights, Mich. The lower the coefficient of
friction in these tests, the better performance the lubricant
usually gives in the transition zone.
Sliding Friction Test
[0039] The sliding friction test measures the properties of the
die-side lubricant that are important in the "end-feeding zone" of
a hydroforming process. In this end-feeding zone, the tube being
hydroformed does not substantially expand or contract its eternal
cross-section, although its walls may thin or thicken. Instead,
part of the tube moves laterally along the die to allow for
expansion in another part of the die. This end-feeding is very
important in the production of some part designs by hydroforming.
The procedure used for this type of test for which values are
reported here is described in American Society for Testing and
Materials ("ASTM") Procedure 4173-82, using a compressive pressure
between the sliding workpieces of 69 bars (1000 psi). (This is
officially an "obsolete" ASTM test method, but it is still useful
for measuring the coefficient of friction in sliding friction.) The
lower the coefficient of friction in sliding friction, the better
is the lubricant in the end-feeding zone.
Solid Film Lubricants
[0040] Examples 1-4 provides examples of the solid film lubricants
of the present invention.
EXAMPLE 1
[0041] TABLE-US-00001 Component Weight % carnuba wax aqueous 89.5%
emulsion, 22% solids, (Michelman Michem Lube 160) water 8.0%
monoethanolamine 0.5% sodium benzoate 2.0% Total 100%
[0042] The monoethanolamine reduces the staining by the wax by the
slightly acidic carnuba wax by raising the pH. Finally, the sodium
benzoate is a corrosion inhibitor. The carnuba wax is characterized
with a hardness of about 1 (ASTM-D-5), a particle size of about
0.15 microns, and a melting point of about 85.degree. C.
EXAMPLE 2
[0043] TABLE-US-00002 Component Weight % microcrystalline wax 99.0
emulsion, 42% solids, (Michelman Michem Lube 124) nonionic
surfactant, (Air 1.0 Products Surfynol 440) Total 100%
[0044] The microcrystalline wax is a mixture of two waxes of
hardness 5 and 13 using ASTM D-5 and with melting points centered
around 68 and 101 degrees C. Furthermore, the microcrystalline wax
has a particle size of about 0.18 microns.
EXAMPLE 3
[0045] TABLE-US-00003 Component Weight % Fischer-Tropsch wax 99.9
emulsion, 40% solids, (Michelman Emulsion 64540) nonionic
surfactant, (Air 0.1 Products Surfynol 420) Total 100%
[0046] The Fischer-Tropsch wax is characterized with a hardness of
about 1 (ASTM-D-5), a particle size of about 0.6 microns, and a
melting point of about 98.degree. C.
EXAMPLE 4
[0047] TABLE-US-00004 Component Weight % Fischer-Tropsch wax 92.5
emulsion, 40% solids, (Michelman Emulsion 98040M1) nonionic
surfactant, (Air 1.0 Products Surfynol 440) neodecanoic acid 4.0
KOH, 45% 2.5 Total 100.00
[0048] The neodecanoic acid functions as both a corrosion inhibitor
and defoamer. The Fischer-Tropsch wax is characterized as set forth
above for example 3.
[0049] The results of the twist compression measurements for the
lubricants in examples 1-3 are summarized in Tables 1 and 2.
TABLE-US-00005 TABLE 1 Twist Compression Results using 6061 T4
Aluminum at 10,000 psi Prewet initial COF @ COF @ COF @ Lube Fluid
COF 1 rev 2 rev 3 rev example 1 water 0.07 0.06 0.07 0.09 example 1
9034 0.01 0.03 0.03 0.04 example 2 water 0.01 0.03 0.06 0.08
example 2 9034 0.01 0.03 0.07 0.10
[0050] TABLE-US-00006 TABLE 2 Twist Compression Results using
Hot-Rolled Steel at 15,000 psi Prewet initial COF @ COF @ COF @
Lube Fluid COF 1 rev 2 rev 3 rev example 1 water 0.01 0.02 0.04
0.06 example 1 9034 0.04 0.04 0.05 0.05 example 2 water 0.01 0.03
0.03 0.04 example 2 9034 0.01 0.03 0.03 0.03 example 3 water 0.01
0.02 0.03 0.04 example 3 9034 0.01 0.02 0.03 0.04
[0051] The coefficient of friction (COF) was determined by the
sliding friction test for various wetted and unwetted waxes. The
results are summarized in Table 3. Surprisingly, the COF is reduced
when the waxes are wetted. TABLE-US-00007 TABLE 3 Coefficient of
friction for various waxes. Wax COF (Neat) COF (wetted) carnuba wax
0.30-0.20 0.20-0.10 montan wax 0.20-0.18 0.18-0.12 microcrystalline
wax 0.12-0.10 <0.10 Fischer-Tropsch wax -- <0.10
Liquid Film Lubricants
[0052] Examples 5-8 provide examples of the liquid film
compositions of the present invention.
EXAMPLE 5
[0053] TABLE-US-00008 Component Weight % blown canola oil, Z2 97.5
viscosity ethoxylated castor oil, 2.5 Chemax CO-5 Total 100.00
[0054] In view of the tackiness of blown canola oil, the
ethoxylated castor oil is water miscible and makes it easier to
wash the composition in example 5. The ethoxylated castor oil in
provided in such an amount that the washability of the formulation
improved but lubricity of the formulation is only minimally
degraded. Small amounts of the ethoxylated castor oil actually
improve lubricity. Example 5 has a burst pressure of about 10,510
psi; a twist compression coefficient of friction at 10,000 psi of
about 0.06; a twist compression coefficient of friction at 15,000
psi of about 0.05; and a sliding coefficient of about 0.065.
[0055] Tables 4 and 5 summarize the twist compression results for
the composition described by example 5. TABLE-US-00009 TABLE 4
Twist Compression Results using 6061 T4 Aluminum at 10,000 psi
Prewet initial COF @ COF @ COF @ Lube Fluid COF 1 rev 2 rev 3 rev
example 5 water 0.06 0.27 0.29 0.28 example 5 9034 0.10 0.24 0.32
0.35
[0056] TABLE-US-00010 TABLE 5 Twist Compression Results using
Hot-Rolled Steel at 15,000 psi Prewet initial COF @ COF @ COF @
Lube Fluid COF 1 rev 2 rev 3 rev example 5 water 0.08 0.07 0.09
0.14 example 5 9034 0.09 0.07 0.08 0.07
EXAMPLE 6
[0057] TABLE-US-00011 Component Weight % canola oil 97.5
ethoxylated castor oil, 2.5 Chemax CO-5 Total 100.00
EXAMPLE 7
[0058] TABLE-US-00012 Component Weight % blown herring oil, Z5 95.0
viscosity ethoxylated castor oil, 5.0 Chemax CO-5 Total 100.00
EXAMPLE 8
[0059] TABLE-US-00013 Component Weight % blown canola oil, Z2 47.5
viscosity naphthenic oil, 100 SUS 50.0 viscosity ethoxylated castor
oil, 2.5 Chemax CO-5 Total 100.00
[0060] Example 8 has a burst pressure of about 10,510 psi; a twist
compression coefficient of friction at 10,000 psi of about 0.06; a
twist compression coefficient of friction at 15,000 psi of about
0.05; and a sliding coefficient of about 0.065
[0061] The coefficient of friction (COF) was determined for
mixtures of blown canola oil and various surfactant. The COF was
measure both for neat (unwetted) and wetted mixtures. Table 6
summarizes the results. The coefficient of friction is surprisingly
reduced in each case when wetted. Chemal DA-6 is the surfactant
ethoxylated decyl alcohol with 6 moles of ethoxylation for each
mole of alcohol, Chemal DA-9 is the surfactant ethoxylated decyl
alcohol with 9 moles of ethoxylation for each mole of alcohol,
Chemal LA-4 is the surfactant ethoxylated lauryl alcohol with 4
moles of ethoxylation for each mole of alcohol, Chemax CO-5 is the
surfactant ethoxylated castor glyceride with 5 moles of
ethoxylation for each mole of castor glyceride; Chemax CO-16 is the
surfactant ethoxylated castor glyceride with 16 moles of
ethoxylation for each mole of castor glyceride; and Chemax CO-80 is
the surfactant ethoxylated castor glyceride with 80 moles of
ethoxylation for each mole of castor glyceride. TABLE-US-00014
TABLE 6 COF for neat and wetted mixtures of blown canola oil and
surfactant. Lubricant COF at 2350 psi % reduction in COF blown
canola oil + 2.5% 0.040 DA-6 blown canola oil + 2.5% 0.025 37.5
DA-6 blown canola oil + 2.5% 0.032 DA-9 blown canola oil + 2.5%
0.028 12.5 DA-9 blown canola oil + 2.5% 0.024 LA-4 blown canola oil
+ 2.5% 0.017 29 LA-4 blown canola oil + 2.5% 0.037 CO-5 blown
canola oil + 2.5% CO-5 0.021 43 blown canola oil + 2.5% CO- 0.035
16 blown canola oil + 2.5% CO- 0.022 37 16 blown canola oil + 2.5%
CO- 0.036 80 blown canola oil + 2.5% CO- 0.024 33 80
[0062] The COF was determined for neat (unwetted) and wetted
mixtures of blown canola oil and the surfactant Chemax CO-40. Table
7 summarizes the COF for varying amounts of Chemax CO-40 in blown
canola oil, Z2, viscosity. Chemax is an ethoxylated caster
glyceride with 40 moles of ethoxylation for each mole of caster
glyceride. Again, the wetted mixtures have lower COF than the neat
mixture. TABLE-US-00015 TABLE 7 COF for neat and wetted mixtures of
blown canola oil and Chemax CO-40. COF at % reduction COF at %
reduction Lubricant 2900 psi in COF 2900 psi in COF blown canola
0.015 -- -- -- oil + 2.5% CO-40 (neat) blown canola 0.012 20% -- --
oil + 2.5% CO-40 (wetted) blown canola -- -- 0.034 -- oil + 2.5%
CO-40 (neat) blown canola -- -- 0.023 32% oil + 2.5% CO-40 (wetted)
blown canola -- -- 0.042 -- oil + 5% CO-40 (neat) blown canola --
-- 0.039 7% oil + 5% CO-40 (wetted)
[0063] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *