Geometrical instruments – Gauge – Bearing or bearing part
Reexamination Certificate
1999-12-22
2001-10-09
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Gauge
Bearing or bearing part
C033S549000, C403S122000, C384S206000
Reexamination Certificate
active
06298570
ABSTRACT:
FIELD OF THE INVENTION
The present invention generally relates to an inspection gage. More particularly, the present invention relates to a gage assembly that is suitable for inspecting compliant or conformal bearings or bearing sets used in vehicular ball and socket joints, non-articulating joints and similar industrial applications. The present invention also includes a method for inspecting compliant or conformal bearings.
BACKGROUND OF THE INVENTION
Traditional methods for dimensionally inspecting injection or compression molded compliant or conformal bearings or bearing sets for use in ball joints can be complex, time-consuming, and inefficient. In particular, after parts are removed from the molds, the parts tend to deform slightly as they cool. With respect to compliant bearings, the deformation is self-correcting upon installation, because the bearing is designed to be “compliant” and to properly “conform” to the surfaces on which it is installed due to the force of installation.
Nevertheless, short of direct installation, it is difficult to know whether a particular bearing is acceptable for use. Current methods for inspecting conformal or compliant bearings generally involve extensive manual measurement of bearing dimensions. However, since the bearing typically deforms as it cools, the actual shape of the uninstalled bearing will be significantly different than the shape the bearing takes after installation. As a result, various complex methodologies have been developed to reconcile pre-installed bearing dimensional measurements, i.e. including bearing deformation, with performance of the bearing after installation. However, as bearing material becomes more compliant and as designs change, it is often impossible to know whether the actual bearing inspection measurements accurately reflect bearing performance after installation. Finally, qualification of large production lots typically requires testing of up to ten percent of all bearings produced. In practice, since the testing requires extensive manual measurements of various dimensions, production lot testing adds a significant amount of time and expense to production of the bearings.
A need therefore exists in industry for an inspection gauge that may be formed in a simple and versatile manner to provide reliable, efficient and cost-effective inspection of molded components. There further exists a need for a gage that is capable of simulating the intended environment for the molded component being inspected, thereby allowing a random sampling to statistically qualify all bearings or bearing sets within a predetermined quantity for use without requiring inspection of every bearing or bearing set.
SUMMARY OF THE INVENTION
The invention is directed to both a gage device and a test system for statistically qualifying compliant or semi-rigid molded bearings and bearing sets to predetermined material conditions prior to assembly (i.e. at beginning of life conditions). The invention includes a gage body, a flanged plug, adapters to set maximum and minimum of material conditions, bearings or bearing sets, studs to set maximum and minimum material conditions, and a test fixture. A bearing or bearing set is assembled to a lower portion of a stud, where the stud is chosen to provide a first material condition. The bearing/stud assembly is then received within at least one adapter chosen to provide a second predetermined material condition. The adapter, including the bearing and stud, is received within a gage body, and a flanged plug is threaded into the gage body. By tightening or loosening the plug, the plug may exert a known force both radially and axially on the bearing set between the adapter and the stud. If the plug flange is not able to seat against the gage body within predetermined torque values, then the bearing set is determined to be defective for failing to install compatibly within the cage. If desired, a test fixture is attached to the upper portion of the stud and the stud is rotated through a predetermined torque cycle and through a predetermined load cycle. The test fixture is used to cyclically load the assembly and to measure axial end motion of the assembly against minimum end motion allowed by applicable specifications. Therefore, during the axial loading cycle, at least one measuring device records the axial end motion or “play” within the assembly. The recorded axial motion must comply with pre determined minimum end motion requirements for the bearing or bearing set at the predetermined load cycle; otherwise the bearing or bearing set falls the conformal (functional) test.
A method of statistically qualifying conformal or compliant bearings is also disclosed whereby accepted statistical methods are applied to a production lot for acceptance testing. In particular, a predetermined number of bearing, or bearing sets within a production lot may be tested to ensure that an entire production lot is acceptable for use. In this way, functional acceptability of a given number of samples drawn from a production lot is proven to satisfy pre-determined maximum and minimum material conditions.
The bearing gage assembly of the present invention does not provide dimensional testing per se, but rather provides a PASS/FAIL test methodology for qualifying conformal or compliant bearing production. The device simulates the assembly of ball joints to determine whether molded conformal bearings or bearing sets are acceptable from a beginning of life perspective. Additional features allow the required crease flow through the bearings to be checked under varying load conditions. Moreover, the gage assembly of the present invention may serve as a check on any dimensional adjustments made in the production process, thereby insuring proper “fit” of any modified bearing or bearing set. The gage of the present invention may also substitute statistical qualifying for traditional time-consuming manual inspection regimes. In this way, functional acceptability of a given number of samples drawn from a production lot is proven to satisfy pre-determined maximum and minimum material conditions.
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Fleniken Greg
Lucienne Frank
Maughan Garth
Morrison Lani
Dana Corporation
Fernandez Maria
Gutierrez Diego
Rader & Fishman & Grauer, PLLC
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