Transcript DALSA_SMontgomery.ppt

IPD Technical Conference
February 19th 2008
Industry:
Automotive – Circuit Board Mounting Screw
Application:
Screw with Silicon Rubber Collar Assembly
Inspection
Presented by: Scott Montgomery / DALSA - IPD
Assembly and Measurement Inspection
Metal Screw with Green Silicon Rubber Collar
Silicon Rubber
Collar
Thread
Automotive part – used to bolt mini circuit board to center console inside a Jeep
Wrangler. Silicon collar used to keep water from penetrating. i.e. four-wheeling
Inspection Requirements
 Measure Silicon Rubber Collar Rib Diameter:
 12.05 mm + / - 0.13 mm
 Check Silicon Collar for Following Surface Flaws (or defects):
 Yellow Pigment Stains
 Foreign Material, i.e. fibers, thread, etc.
 Gas Pockets in the silicon mold
 Flash and Short Shots
 Missing, Rotated, Misplaced or Reversed Collars
 Check for Following Thread Defects:
 Foreign or Extra Material in Shoulder
 Missing Threads
Critical Measure: Rib Diameter
Rib Diameter
+ / - 0.13 mm
Surface Flaws in Collar
Gas Pockets
Foreign Material
Yellow Pigment Stains
Flash
Short Shots
Misplaced and Reversed Collar
Head Diameter Smaller
Collar Properly Placed
Head Diameter Larger
Misplaced Collar
(pushed downward)
Reversed Collar
Thread Defects
Foreign Material in Shoulder
Missing Threads
Vision System Overview
 Vision System : VA-41 w/ Sherlock
 2 Cameras, TM2 640 H x 480 V
 Camera 1: Lighting and Optics:
 TML 56676 Telecentric Lens
 24v. White LED Pad Light, size 75mm x 75mm
 Aluminum Polished Block
 Camera 2: Lighting and Optics
 Fujinon 35 mm Lens w / 5mm ext. ring
 24v. White LED Ring Ling ( 45 deg. angled LEDs )
 Initial trigger pulse sent from PLC, then custom DALSA IPD
I/O trigger module – generates a trigger pulse train
 User Interface – Visual Basic front end
Camera 1: Collar and Thread Inspection
Front Pad Light
( white LED )
Aluminum Block
( simulates a backlight )
Camera 2:
Insertion Inspection
(misplaced collars)
Ring Light
( 45 deg., white LED )
Machine Overview
 Screws and green silicon collars are “bowl fed” independently
to pick-and-place grippers
 Screws are dropped into a pocket on an indexing rotary table
 As the table indexes, a gripper inserts a silicon collar over the
screw head
 At the next station, a motorized drive engages, lifts, and
presents the screw assembly to the vision system –
CAMERA (1)
 The completed assembly is spun 360 degrees to perform 100%
surface flaw and thread inspection, and rib diameter
measurement
 The vision system snaps a picture every 18 deg. of rotation – 20
triggers total for one completed revolution
Machine Overview (continued)
 The table indexes the assembly to the next station to
check for proper collar insertion – CAMERA 2
 The vision system outputs a separate “PASS” signal at
each inspection station to the PLC
 If the assembly failed either inspection, a pick-and-place
gripper will discard the part at the next indexed station
 Otherwise, the part moves to the final station and is
placed onto a conveyor that drops the completed
assembly into a shipping carton
 Once the desired lot quantity is reached the carton is
sealed and ready for delivery.
Application Challenges
 Achieving Full 360 degree, 100% Surface Inspection
 Using a pulse train of input triggers from DALSA IPD trigger
module ‘matched’ to the desired speed of rotation – 1 sec.
 Finding a “One Light Fits All” Solution
 Green collar absorbs standard ‘RED’ LED wavelength of light
 Motion blur and minimal background contrast
 Lighting on a cylindrical surface produces centerline hotspot
 Detecting Subtle Surface Flaws and True Flash Defects
 Discriminating between real defects and acceptable surface
imperfections – TEXTURE TOOL
 Discriminating between true flash and acceptable flash
 Keeping Within Rib Diameter Tolerances
 Minimizing drive wobble and slippage
 Detecting drive slippage
 Minimizing perspective distortion
Capturing a Full 360 degree Field of View
(using a pulse train of input triggers)
20 Trigger Pulses **
1 Trigger Pulse
PLC
Begins
Inspection Cycle
DALSA IPD
Custom
I/O Module
1
2
3
20
VA-41
Begin to Capture
and Process Images
** Input triggers are fed to the trigger input on VA-41 I/O breakout board
( PIN 2 )
Finding a “One Light Fits All” Solution
Front Pad Light
( white LED )
Aluminum Block
( simulates a backlight )
Lighting Challenges
( creating a well-contrasted background with diffuse foreground )
Center line hotspots
( skunk stripe )
Green silicon
rubber absorbs most
LED light
Polished aluminum block reflects light, providing a bright background
White LED Pad Lighting
Suits All Inspections Requirements
Flash
Surface Inspection
Edge Profiling
TEXTURE TOOL
( Detecting Subtle Surface Flaws )
Gas Pockets
TEXTURE tool is effective for measuring texture based on edge density where
the edge sensitivity can be ‘tuned’ to discriminate between true defects and
natural surface variations - TOTAL EDGE COUNT is primary measure
Other Surface Flaws
Foreign Material
True Flash vs. Acceptable Flash
Acceptable Flash
True Flash
Tracking Independent Reference Points
Flash Tools
( tracks laterally )
Left side Reference Point
Right side Reference Point
Minimizing Drive Wobble
( critical for rib diameter measurements )
Tracking Spin Motion
Measuring Rib Diameter
Detecting Drive Slippage
Tracking thread motion to detect drive slippage
Minimizing Perspective Distortion
Conventional Lens
Telecentric Lens
Conventional vs. Telecentric Lens
Perspective Distortion
Flat - No Distortion
Conventional Lens
Telecentric Lens
User Interface
Summary
 Overall cycle time per part : 2.0 seconds
 Inspection time – 800 msec.
 Shuttling part in and out – 1.2 seconds
 Machine runs at less than 1.0% percent scrap rate
 Produces about 40,000+ parts per week
 Customer Quote :
“ Thanks to IPD, now I can sleep at night “
O.K. Guys, It’s a Wrap ! ! !
Tom
“ the builder ”
“ Dr. V.B. ”
“Vision Guy”