Abstract:
An inspection station for a workpiece including a conveyor, a mechanism for rotating the workpiece, and a probe. The conveyor includes a fixture for locating the workpiece and the conveyor is configured to translate the workpiece in a linear manner. A mechanism, such as a belt, engages the workpiece thereby rotating the workpiece within the fixture. The probe is configured to indicate if the workpiece conforms to quality criteria. To facilitate inspection while the conveyor translates the workpiece, the probe is attached to a stage where the stage is configured to move the probe synchronously with the workpiece over an inspection region.

Description:
FIELD OF THE INVENTION  
       [0001]     This invention relates to a device for inspecting components and particularly to one using a probe that translates synchronously with the component over an inspection region.  
       BACKGROUND OF THE INVENTION  
       [0002]     Presently, there is an ever increasing demand to obtain high quality products which has resulted in a significant increase in the use of 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, fasteners used in the automobile industry and elsewhere often must be individually inspected to determine if they meet product specifications.  
         [0003]     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, plating etc. It is not uncommon for one or more of the processes to produce a crack in the part or other defect. The occurrence of such defects is often not adequately monitored through random part selection or other quality assurance processes which do not provide 100% inspection. The inspection system of this invention is also highly adaptable for evaluating various components.  
         [0004]     A variety of non-contact inspection systems are known using a variety of inspection techniques. For example, eddy current inspection systems examine the electromagnetic field transmitted through a part as a means of characterizing cracks in the part. Various systems based on a video image of a part are also known. In addition, laser gauging systems are used for obtaining specific dimensional measurements.  
         [0005]     Although known inspection systems are generally useful, they have certain limitations. Many of the presently available non-contact gauging systems require complex data processing approaches which impose expensive hardware requirements and can limit the speed with which evaluations can be accomplished. Further, many inspection stations either require multiple sensors to inspect the full circumference of the part or include a station where the part is stopped and indexed into special tooling that manipulates the part to present the entire circumference to a sensor for inspection. Preferably, evaluation of a component can be conducted in a rapid enough fashion that the parts can be directly sorted into qualified or disqualified part streams. Many of these prior art systems also tend not to be easily adapted to various part configurations. Moreover, many prior art systems, although performing adequately in a laboratory setting, are not sufficiently rugged for a production environment where temperature variations, dust, dirt, cutting fluids, etc. are encountered.  
         [0006]     In view of the above, it is apparent that there exists a need for an improved inspection system for workpieces.  
       SUMMARY  
       [0007]     In satisfying the above need, as well as overcoming the enumerated drawbacks and other limitations of the related art, the present invention provides an improved inspection system for workpieces.  
         [0008]     In accordance with the present invention, an embodiment of an improved inspection system is provided which enables rapid inspection to be conducted permitting parts to be immediately sorted in terms of being in conformance or out of conformance with quality specifications. The parts move from a hopper by gravity or other means along a track to a conveyor. The conveyor has an array of fixtures for locating the parts on the conveyor. Further, a belt extends along the conveyor and engages the parts causing them to rotate within the fixture. One or more probes are used to inspect the parts as they are translated and rotated along the conveyor.  
         [0009]     In one aspect of the present invention, the probe is an eddy current sensor that generates a magnetic field to sense cracks in the part. In another aspect of the present invention, the probe inspects the formation of a recess in the part. The probe includes a tool that engages the recess and the depth of translation into the recess is measured to determine if the recess is properly formed. In addition, the system includes a stage where the probe is attached to the stage and the stage is configured to translate synchronously with the part as the part is translated by the conveyor. The stage includes a mechanism to engage the conveyor thereby translating the probe in alignment with the part and allowing inspection of the part by the probe. Preferably, the mechanism of the stage engages the conveyor for at least one full rotation of the part to facilitate inspection.  
         [0010]     Further objects, features and advantages of this invention will become readily apparent to persons skilled in the art after a review of the following description, with reference to the drawings and claims that are appended to and form a part of this specification. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is an isometric view of an inspection system in accordance with the present invention;  
         [0012]      FIG. 2  is an isometric view showing an inspection station in accordance with the present invention;  
         [0013]      FIG. 3  is a top view of the conveyor and inspection station in accordance with the present invention;  
         [0014]      FIG. 4  is an isometric view of an inspection assembly in accordance with the present invention; and  
         [0015]      FIG. 5  is another isometric view of an inspection assembly in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]     Referring now to  FIG. 1 , a system embodying the principles of the present invention is illustrated therein and designated at  10 . As its primary components, the system  10  includes an inspection station  12  that uses a linear conveyor  14  to translate parts while a belt drive  16  rotates the parts relative to the conveyor  14 .  
         [0017]     The parts are provided from a hopper  18  along a track  20 . The parts translate along the track  20  due to gravity, vibration, or other means reaching the inspection station  12 . Parts  24  are located in the inspection station  12  by an array of fixtures  26  forming part of the conveyor  14 , as shown in  FIG. 2 . The belt drive  16  moves at a speed different than the speed of the conveyor  14 . For example, the belt drive  16  may move in the same direction as the conveyor  14  but at a slightly faster speed. Alternatively, the belt drive  16  may move slower than the conveyor  14  or even in the opposite direction. Another embodiment may include a stationary pad that frictionally engages the parts  24 .  
         [0018]     Referring again to  FIG. 2 , the belt drive  16  frictionally engages the parts  24  located on the conveyor  14 . The frictional engagement causes the parts  24  to rotate as they are translated linearly by the conveyor  14  in the fixtures  26 . To facilitate rotation of the parts  24 , the fixtures  26  include rollers  28  that provide positive mechanical location of the parts  24  parallel to the direction of conveyor translation while allowing rotation.  
         [0019]     Further, the parts  24  have a head with a diameter that is larger than the diameter of the body of the parts  24 . The fixtures  26  have a surface that locates the parts  24  in a direction perpendicular to the direction of conveyor translation. In the embodiment shown, the fixtures  26  are positioned at an angle relative to gravity such that the head of the parts  24  will self locate against a surface of the fixture  26  due to gravity thereby locating the parts  24  in a direction perpendicular to the direction of conveyor translation. A guide such as a rail may also be used to positively locate the parts  24  in a direction perpendicular to the direction of conveyor translation. The parts  24  fall off the end of the conveyor  14  into a chute  22  that sorts conforming from non-conforming parts.  
         [0020]     Now referring to  FIG. 3 , a first and second inspection assembly  40 ,  42  are illustrated in accordance with the present invention. The first inspection assembly  40  includes a stage  44  and a probe  45 . The first inspection assembly  40  is configured to inspect a recess in the part as the conveyor  14  translates the part  24  through an inspection region  41 . The conveyor  14  includes a belt  30  that rotates around a first pulley  32  and a second pulley  34 . Although a belt  30  is shown, a chain or other conveyor may be readily used. Attached to the belt  30  is an array of fixtures for holding parts. Fixture  36  is aligned with the first inspection assembly  40  at the start of the inspection region  41  while fixture  38  is aligned with the second inspection assembly  42  at the start of inspection region  43 .  
         [0021]     The stage  44  of the first inspection assembly  40  is configured to engage the conveyor  14  such that the stage  44  moves synchronously and in alignment with fixture  36  allowing inspection of the part as the fixture  36  translates through inspection region  41 . The probe  45  includes a tool  52  configured to engage a recess in the part. The tool  52  may be readily changed and adapted for different parts. For example, the tool  52  may take the form of a torx head, a hex head, or any other commonly used tool for driving a fastener.  
         [0022]     A slide cylinder  46  is attached to the tool  52  through a spindle assembly  48 . The tool  52 , spindle assembly  48 , and slide cylinder  46  are attached to the stage  44  through a slide  50 . The slide  50  allows motion perpendicular to the travel of the conveyor  14  and slide  44 . Therefore, the slide  50  enables the tool  52  to be advanced toward the part while the tool  52 , spindle assembly  48 , and slide cylinder  46  are being translated synchronously and in alignment with the part and fixture  36 .  
         [0023]     The slide cylinder  46  is configured to advance the tool  52  causing it to engage the recess in the part as the part translates through the inspection region  41 . Further, slide cylinder  46  retracts the tool  52  from the part when the part exists the inspection region  41  allowing the stage  44  to translate back to the start of the inspection region  41  to inspect the next part. Alternatively, the tool  52  may be advanced using a cam mechanism configured to translate the tool  52  toward the part based on the linear movement of the slide  44 .  
         [0024]     The translation of the tool  52  into the recess of the part corresponds to the translation of an indicator  57  that is attached to the tool  52  or spindle assembly  48 . Accordingly, translation of the indicator  57  is measured by a sensor  58 . The sensor  58  may be a simple switch, such as a photo switch to indicate whether or not the tool has translated an acceptable distance. Alternatively, the sensor  58  may be configured to measure the amount of translation of the indicator  57 , such as a linear transducer. To axially align the tool  52  with the part, an angle adjustment plate  54  is provided to adjust the rotation of the spindle assembly  48  and tool  52 . Similarly, a vertical adjustment plate  56  is provided to translate the tool  52  relative to the stage  44 .  
         [0025]     To allow inspection while the conveyor  14  is translating the part through the inspection region  41 , the slide  44  mechanically engages the conveyor  14  allowing the stage to synchronously translate in alignment with the part and fixture  36  through the inspection region  41 . To facilitate engagement, a notch  60  is provided in the fixture  36 . A dog  62  attached to the stage  44  is biased into engagement with the notch  60  as the fixture  36  approaches the inspection region  41 . Further, to signal the beginning of the inspection region  41 , a position flag  74  is configured to trigger photo switch  80  that signals a controller that the fixture  36  is at the beginning of the inspection region  41 . The signal also indicates that sensor  58  may be monitored to determine whether the tool  52  has translated into the recess of the part an acceptable distance. Similarly, a second flag  76  triggers photo switch  78  when the fixture  36  translates to the end of the inspection region  41  signaling the controller that the end of the inspection region has been reached.  
         [0026]     In addition, a pawl  66  is provided with a cam surface  68  that is configured to engage a release surface  70 . As the stage  44  translates through the end of the inspection region  41 , the cam surface  68  engages the release surface  70  rotating the pawl  66  about pivot  64 . As the pawl  66  rotates, the dog  62  is withdrawn from the notch  60  of the fixture  36 . As the slide  44  disengages the conveyor  14 , a biasing member  72 , such as a spring, translates the slide  44  to the beginning of the inspection region  41  where the next part may be inspected. In addition, a shock absorber  76  may be provided to reduce wear on the slide  44  and the probe  45 .  
         [0027]     Now referring to the second inspection assembly  42 , slide  84  engages the track  14  to align probe  108  with the part and fixture  38  as fixture  38  travels through the inspection region  43 , as shown in  FIG. 4 . The probe  108  may be an eddy current sensor configured to generate a magnetic field to detect cracks in the part, for example cracks in the head of a fastener. Preferably, the part interacts with the belt  16  such that the part rotates at least one full circumference through the inspection region  43 . As the part is rotated so that the cracked surface of the part is exposed to the probe  108 , the magnetic field is disturbed allowing the crack to be detected. The probe  108  is mounted on a stage  84 . The stage  84  is configured to engage the conveyor  14  such that the stage moves synchronously and in alignment with fixture  38  allowing inspection of the part as fixture  38  translates through inspection region  43 .  
         [0028]     Referring again to  FIG. 3 , the slide mechanically engages the conveyor  14  allowing the stage to synchronously translate in alignment with fixture  38 . To facilitate engagement, a notch  86  is provided in the fixture  38 . A dog  88  attached to the stage  84  is biased into engagement with the notch  86  as the fixture  38  approaches the inspection region  43 . Further, to signal the beginning of the inspection region  43 , a position flag  100  is configured to trigger photo switch  104  that signals a controller that the fixture  38  is at the beginning of the inspection region  43  and that probe  108  may be monitored to determine whether a crack is present in the part. Similarly, a second flag  102  triggers photo switch  106  when the fixture  38  translates to the end of the inspection region  43  signaling the controller that the end of the inspection region has been reached. An isometric view of the stage  84  and flags  100 ,  102  is provided in  FIG. 5 .  
         [0029]     In addition, a pawl  82  is provided with a cam surface  94  that is configured to engage a release surface  96 . As the stage  84  translates through the end of the inspection region  43 , the cam surface  94  engages the release surface  96  rotating the pawl  92  about pivot  90 . As the pawl  92  rotates the dog  88  is withdrawn from the notch  86  of the fixture  38 . As the slide  84  disengages the conveyor  14  a biasing member  98 , such as a spring, translates the slide  84  to the beginning of the inspection region  43  where the next part may be inspected.  
         [0030]     Further, it is also envisioned that multiple probes may be attached to the same slide. For example, the probe  108  of the second inspection assembly may be attached to slide  44  along with probe  45 . Accordingly, probe  45  and probe  108  would operate on two parts located in adjacent fixtures.  
         [0031]     As a person skilled in the art will readily appreciate, the above description is meant as an illustration of implementation of the principles this invention. This description is not intended to limit the scope or application of this invention in that the invention is susceptible to modification, variation and change, without departing from the spirit of this invention, as defined in the following claims.