Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
1998-11-04
2001-09-04
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S559240, C356S638000
Reexamination Certificate
active
06285034
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device for inspecting components and particularly to one using an array of light sources and photo-detection devices as a means of evaluating a fastener with a flanged or“washer-headed” configuration for conformance to spatial form criteria.
Presently, there is an ever increasing demand to obtain high quality products which has resulted in a significant increase in the use of non-contact inspection systems. In order for a complex machine to operate as designed, it is necessary that all of its sub-components comply with quality criteria. In some manufacturing settings, customers require 100% inspection of component parts. For example, flanged fasteners used in the automobile industry and elsewhere often must be individually inspected to determine if they meet spatial form criteria.
Numerous types of inspection systems are presently utilized. One type of system uses contact probes which touch a component at various points to determine if its dimension or profile meet certain criteria. However, contact devices have inherent limitations in that they are subject to wear and generally require that the component and the contact probe be accurately positioned during the evaluation process. Moreover, such devices are generally slow to operate and are limited in terms of the number of criteria and complexity of profiles which they can evaluate. A variety of non-contact systems are also known using a variety of techniques. For example, ultrasonic inspection systems examine reflected sound waves as a means of characterizing a component. Various systems based on photodetection utilizing single channel photodetectors are also known. In addition, laser gauging systems are used in which specific dimensional measurements can be obtained.
However, although non-contact inspection systems are known, there is a need in the art for a non-contact inspection system that can detect damage or defects for a hex headed flanged or“washer headed” bolt. If a hex-headed flange bolt is damaged across its corners and fails a minimum“across corners value” a wrench used to tighten the bolt will slip, leading to installed bolts lacking the required tightening torque. A hex-headed flanged bolt as it slides down a chute will be oriented in an unknown radial position because of it circular flange. A simple profile matching function cannot be used to detect damage to the hex-head as the bolts do not pass by the inspecting lasers in a known position. Non-contact gauging systems that exist today do not have the ability to examine damage to the corners of a hex-headed flange bolt in real time with a 100% part inspection. There is a need in the art for a noncontact gauging system for the inspection of hex headed flanged bolts.
SUMMARY OF THE INVENTION
In accordance with the present invention, an improved non-contact inspection system is provided which enables rapid inspection of hex headed flanged or“washer headed” bolts to be conducted permitting the bolts to immediately be sorted in terms of being in conformance or out of conformance with spatial form criteria. For example, for a hex headed flanged bolt, the“across corner values” can be evaluated and the conforming parts can be channeled to a bin separate from that of the nonconforming parts.
When producing fasteners, the process often begins with wire stock which is fed into a cold heading or screw type forming machine. The part is die-formed or cut in a machine into a shape that may include several diameters and possibly a threaded or knurled length. The formed part may require secondary operations such as thread rolling, heat treating, planing, stamping etc. It is not uncommon for one or more of the processes to fail to produce the desired geometry of part. Specifically, the hex head stamped onto the fastener may be distorted and twisted by the stamping process. The occurrence of such defects is often not adequately monitored through random part selection or other quality assurance processes which do not provide a 100% inspection.
In the present invention parts move by gravity or other means along a track through a test section. The part shape is determined through the use of an array of lasers or other light sources and photodetection devices such as CCD in line pixel arrays or single channel photodetectors, but is not limited to such approaches. The array of lasers is mounted in radial fashion about a track in which the parts slide down. As a part slides down the track it will occlude the light generated from the array of lasers . The photodetection devices will measure the occluded light and generate output signals to a signal processor. From these output signals the conformity of the hex head may be determined through the use of a novel method which does not require that the flanged hex bolt slide down the track in a fixed radial position.
Further objects, features, and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.
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Hanna James L.
Smith Donald R.
Brinks Hofer Gilson & Lione
Le Que T.
Luu Thanh X.
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