U.S. patent application number 10/678665 was filed with the patent office on 2004-04-08 for method of producing a workpiece having at least one bearing eye.
This patent application is currently assigned to Miba Gleitlager GmbH. Invention is credited to Rumpf, Thomas, Schneiderbauer, E., Spiessberger, Helmut.
Application Number | 20040064948 10/678665 |
Document ID | / |
Family ID | 31999990 |
Filed Date | 2004-04-08 |
United States Patent
Application |
20040064948 |
Kind Code |
A1 |
Rumpf, Thomas ; et
al. |
April 8, 2004 |
Method of producing a workpiece having at least one bearing eye
Abstract
A method of producing a workpiece having at least one bearing
eye is described, the bearing eye being coated with an
anti-friction coating made of an alloy of a harder alloy component
and a softer alloy component. In order to achieve an advantageous
load capacity, it is suggested that the bearing eye be processed
for a precise fit to a circular cylinder before the anti-friction
coating is applied to the processed bearing eye surface in a
thickness corresponding to the final dimensions, the proportion of
the softer alloy component in the deposited alloy being increased
with increasing coating thickness.
Inventors: |
Rumpf, Thomas; (Gmunden,
AT) ; Schneiderbauer, E.; (Taufkirchen, AT) ;
Spiessberger, Helmut; (Pinsdorf, AT) |
Correspondence
Address: |
Kurt Kelman
COLLARD & ROE, P.C.
1077 Northern Boulevard
Roslyn
NY
11576
US
|
Assignee: |
Miba Gleitlager GmbH
|
Family ID: |
31999990 |
Appl. No.: |
10/678665 |
Filed: |
October 3, 2003 |
Current U.S.
Class: |
29/898.12 |
Current CPC
Class: |
C23C 2/02 20130101; C25D
7/10 20130101; F16C 9/04 20130101; F16C 33/12 20130101; C23C 30/00
20130101; Y10T 29/49705 20150115 |
Class at
Publication: |
029/898.12 |
International
Class: |
B21K 001/76 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 4, 2002 |
AT |
A 1506/2002 |
Claims
1. A method of producing a workpiece having at least one bearing
eye, the bearing eye being coated with an anti-friction coating
made of an alloy of a harder alloy component and a softer alloy
component, characterized in that the bearing eye is processed for a
precise fit to a circular cylinder before the anti-friction coating
is applied to the processed bearing eye surface in a thickness
corresponding to the final dimensions, the proportion of the softer
alloy component in the deposited alloy being increased with
increasing coating thickness.
2. The method according to claim 1, characterized in that the
anti-friction coating is galvanically deposited on the processed
bearing eye surface and, during the galvanic depositing procedure,
the strength of the electrical field used for the depositing
procedure is varied as a function of the desired increase of the
proportion of the softer alloy component.
3. The method according to claim 1 or 2, characterized in that, for
a workpiece having a divided bearing eye, the bearing eye surface
is processed for a precise fit after the assembly of the divided
bearing eye and then galvanically coated with the anti-friction
coating, before the anti-friction coating is divided in accordance
with the division of the bearing eye by a fracture separation.
Description
1. FIELD OF THE INVENTION
[0001] The present invention relates to a method of producing a
workpiece having at least one bearing eye, the bearing eye being
coated with an anti-friction coating made of an alloy of a harder
alloy component and a softer alloy component.
2. DESCRIPTION OF THE PRIOR ART
[0002] Friction bearings subjected to high dynamic loads, for
connecting rods of internal combustion engines, for example, are
generally made of bearing shells which are received by a divided
bearing seat of the workpiece. In order to avoid the disadvantages
in regard to the overall size and therefore the weight, as well as
the production cost, connected with providing separate bearing
shells, it has already been suggested that the bearing eye provided
in the workpiece be coated directly with an anti-friction material
(European Patent Application 0 635 104 B1). For this purpose, the
workpiece may be coated with the anti-friction coating through a
thermal spray method, before the anti-friction coating applied to
the bearing eye surface is divided together with the workpiece or,
if the workpiece is already divided, is itself divided
corresponding to the workpiece by a fracture separation. As an
additional advantage of this direct coating of the bearing eye, it
was emphasized that the bearing eye surface to be coated must no
longer be reprocessed for a precise fit, because imprecisions are
compensated for by applying the anti-friction coating and it is
therefore no longer necessary to appropriately process the
anti-friction coating itself precisely. However, the compensation
of imprecisions of the bearing eye requires sufficiently thick
anti-friction coatings, which thermal spray methods are
particularly suitable for applying. Such thermal spray methods have
the disadvantage, however, that the adhesion between the
anti-friction coating sprayed on and the bearing eye surface is
hardly sufficient for high load requirements without something
further. In addition, due to the compensation of imprecisions,
after the anti-friction coating has been processed for a precise
fit, a non-uniform thickness of the anti-friction coating, whose
distribution is unpredictable, must be expected, which, due to the
fatigue strength, which is reduced with the thickness of the
anti-friction coating, may lead to a localized overload of the
anti-friction coating, for example, if anti-friction coating zones,
whose position may not be influenced, occur in a high load bearing
region.
SUMMARY OF THE INVENTION
[0003] The present invention is therefore based on the object of
implementing a method of producing a workpiece having at least one
bearing eye of the type initially described in such a way that,
with a comparatively low production cost, a high dynamic bearing
load capacity may be ensured without impairing the service
life.
[0004] This object is achieved according to the present invention
in that the bearing eye is processed for a precise fit to a
circular cylinder before the anti-friction coating is applied to
the processed bearing eye surface in a thickness corresponding to
the final dimensions, the proportion of the softer alloy component
in the deposited alloy being increased with increasing coating
thickness.
[0005] Since, as a consequence of these measures, a precisely fit,
circular cylindrical bearing eye surface may be assumed, the final
dimension of the running surface formed by the anti-friction
coating may be ensured using a thin-layered application of the
anti-friction coating without reprocessing of the anti-friction
coating, with the advantage that the anti-friction coating has a
constructively predetermined thickness gradient, which represents
an essential requirement for a high service life of friction
bearings subjected to high dynamic loads, particularly since
comparatively thin anti-friction coatings having a thickness of,
for example, 20 to 40 .mu.m are possible within narrow tolerance
ranges, if no compensation of imprecisions via the anti-friction
coating thickness is required. A further requirement for a high
dynamic load capacity of such a friction bearing may be seen in the
load capacity of the anti-friction coating itself, taking into
consideration the running-in conditions, which require a
comparatively soft running coating. In order to be able to meet
these partially contradictory requirements, the anti-friction
coating, which is typically made of an alloy of harder and softer
alloy components, is deposited on the bearing eye surface in such a
way that with increasing coating thickness, the proportion of the
softer alloy component in the deposited alloy is increased, so that
the hardness of the anti-friction coating increases from the
running surface toward the bearing eye surface. This means that in
spite of good running-in conditions, a sufficient support effect to
meet high dynamic loads of the friction bearing may also be applied
via the anti-friction coating.
[0006] Such anti-friction coatings may be applied physically in
vacuum with the necessary precision due to the restricted coating
thickness. The coating outlay may be simplified in relation to this
application method by a galvanic deposition of the anti-friction
coating on the bearing eye surface, however. The strength of the
electrical field used for the depositing procedure merely has to be
changed during the galvanic deposition procedure as a function of
the desired increase of the proportion of the softer alloy
component. This means, for example, for an anti-friction coating
based on a copper-lead alloy, that the current density must be
increased during the depositing procedure from an initial 3
A/dm.sup.2 to 10 A/dm.sup.2, in order to elevate the proportion of
lead in the deposited coating using the higher current density. The
hardness gradient over the thickness of the anti-friction coating
thus achieved may be controlled in accordance with the particular
requirements via the current density.
[0007] During coating of a workpiece having a divided bearing eye,
the bearing eye surface is processed for a precise fit after
assembly of the divided bearing eye and then galvanically coated
with the anti-friction coating, before the anti-friction coating is
divided in accordance with the division of the bearing eye through
a fracture separation. Since, after the assembly of the divided
bearing eye, the processing of the bearing eye for a precise fit is
performed in order to provide the requirements for a tailored
coating which ensures the final dimensions without reprocessing, it
must merely be ensured, after the thin-layered application of the
anti-friction coating, that the anti-friction coating applied is
divided corresponding to the division of the bearing eye, which is
advantageously performed through a fracture separation. The
comparatively low coating thickness and the good adhesion of the
galvanically deposited anti-friction coating on the bearing eye
surface represent advantageous conditions for a fracture separation
without problems.
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