Optics: measuring and testing – Dimension – Thickness
Reexamination Certificate
2001-03-05
2004-06-29
Smith, Zandra V. (Department: 2877)
Optics: measuring and testing
Dimension
Thickness
C250S559270
Reexamination Certificate
active
06757069
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
(Not Applicable)
BACKGROUND OF THE INVENTION
The present invention generally relates to a system and a method for measuring a workpiece thickness, and more particularly to an improved system and method for measuring a workpiece thickness via an adjustable laser triangulation system that is operative to emit at least one laser beam in generally perpendicular relation to angularly oriented sides of the workpiece.
The concept of measuring workpiece thicknesses in commercial and military applications is well known. More specifically, the measuring of workpiece thicknesses may have wide variety of applications in the aerospace industry, substantially extending to all forms of structural and manufacturing related operations. For instance, a workpiece thickness measurement is frequently a required engineering specification in designing and manufacturing parts related to the field, namely, in construction and assembly of structures such as aircrafts or other forms of vehicles. Simply put, the workpiece thickness measurement is often a necessary product and design information. Thus, defining workpiece thickness measurements has become a vital and integral process in the aerospace industry, as well as other related industries.
In many industries, and in the aerospace industry in particular, the workpiece thickness measurement is usually obtained by a hands-on method. Such contention is generally true in obtaining thickness measurements for workpieces such as composite laminate skins. For example, when measuring thicknesses of composite laminate skins, many aerospace industries use traditional contact inspection methods.
As is generally known, the traditional contact inspection methods require the utilization of a plurality of tools (e.g., Micrometer, Vernier Caliper, Magna Mike). Moreover, an above average skill level personnel is oftentimes needed to operate such tools in order to measure the thicknesses of composite laminate skins. In other words, a certain level of personnel expertise may be demanded when determining thicknesses of composite laminate skins via the traditional contact inspection methods. Therefore, a significant cost associated with training the personnel may be unavoidable, as well as the time expended therewith.
However, even when the traditional contact inspection methods are applied correctly, such methods are marred by unfavorable limitations. For instance, the speed and accuracy of measuring the thicknesses of composite laminate skins are frequently compromised, as manual interaction plays a considerable role and is often inevitable. Furthermore, the tools utilized in the traditional contact inspection methods, such as the Micrometer and the Vernier Caliper, may generally be restricted to measuring static workpieces. As a result, such methods have posed to be moderately ineffective and inconvenient in the aerospace industry.
Many industries, not necessarily related to the aerospace industry, have begun using laser triangulation systems to measure thicknesses of desired workpieces. More specifically, the laser triangulation system may comprise two opposing laser heads, wherein a specific workpiece may be positioned therebetween. Thereafter, a laser beam may be radiated from each respective opposing laser heads on the surfaces of the workpiece. In addition, the opposing laser heads may further receive the laser beams which are reflected from the surfaces of the workpiece. The laser triangulation system may convert the laser beams into a computable signal for conveyance to a measurement device (i.e., a computer). Thus, the measurement device may then manifest the computable signal into a workpiece thickness measurement.
However, the laser triangulation systems have their disadvantages. In particular, it is imperative that the laser beams radiated from the laser heads be perpendicular to the surfaces of the workpiece. If they are not perpendicular to the workpiece surfaces, then the precision and accuracy of the thickness measurements may be substantially reduced. Moreover, both of the laser beams should be aimed at a common axis of the workpiece such that the precision and accuracy of the thickness measurements remain intact.
Continuing the above paragraph, the general preference to have the laser beams in perpendicular relation to the workpiece surfaces, while the laser beams are aimed at the common axis thereof, may be for the purposes of procuring the appropriate angles and depth. More specifically, acquiring the proper degrees of separation between the radiated laser beams and the reflected laser beams may be essential in the overall calculation of the workpiece thickness. Additionally, it may further be important that the laser beams share the common axis of the workpiece so that a measurement can be made as to the particular thickness of that axis.
The laser triangulation systems have generally been used to measure thicknesses of flat surfaced workpieces in the industries that they are most utilized in. Because of the flatness of the workpiece surfaces, a perpendicular relationship therewith may easily be achieved by the radiated laser beams. Moreover, the common axis of the workpiece may further be shared by the laser beams thereby. However, in certain industries, such as the aerospace industry in particular, the workpieces often do not possess flat surfaces. The aerospace industry usually involves construction and assembly of complex structures due to the inherent nature of its business. The workpieces involved in the aerospace industry may define sophisticated configurations and angular orientations. Application of the laser triangulation methods as described above may be difficult, and sometimes impractical. In order to obtain the desired perpendicular relationship and the common axis between the laser beams and the workpiece, the workpiece may need to be conformed to the laser triangulation system. Such tempering of the workpiece may result in incorrect measurement of its thickness.
Thus, there has long been a need in the industry, and in the aerospace industry in particular, for a uniform system and method of measuring workpiece thicknesses in a more efficient and accurate manner without involving highly skilled personnel. In particular, there is a need to apply such system and method to measure thicknesses of workpieces that define sophisticated configurations and angular orientations.
The present invention addresses the above-described deficiencies by introducing a system and a method to the aerospace industry in particular to avoid the traditional contact inspection methods when measuring workpiece thicknesses by utilizing a laser non-contact thickness measurement system. More specifically, the laser non-contact thickness measurement system is designed to conform to a plurality of workpiece configurations and angular orientations so as to facilitate the emission of laser beams in generally perpendicular relation thereto. In this respect, not only does the present invention mitigate the problems posed by the traditional contact inspection methods used in the aerospace industry, but it also corresponds to various workpiece configurations and angular orientations as well.
BRIEF SUMMARY OF THE INVENTION
In accordance with a preferred embodiment of the present invention, there is provided a system and a method for measuring a thickness of a workpiece having first and second sides, wherein the second side may define a reference plane. The first side has a first angular orientation with respect to the reference plane. The reference plane may further define a target axis which extends perpendicular from a second side target point of the second side disposed in the reference plane through a first side target point of the first side.
A first laser triangulation emitter/sensor may be sized and configured to emit a first laser beam at the first side target point. More specifically, the first laser triangulation emitter/sensor may comprise a first laser diode for the purpose of emitting the first laser beam at the first si
Northrop Grumman Corporation
Smith Zandra V.
Stetina Brunda Garred & Brucker
Stock, Jr. Gordon J.
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