Visual Inspection of Self-Pierce Riveting Systems for the Automotive Industry

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Visual Inspection of Self-Pierce RivetingSystems
for the Automotive Industry
By Paul Johnson (p.johnson1_at_ljmu.ac.uk)
Supervisors Dr Francis Lilley, Professor David
Burton.
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Overview

• Self-Pierce Riveting
• Why SPR?
• SPR Problems
• Current Technology
• Technology Problems
• Project Objectives
• Project Status
• Conclusions Future Work
• A problem to solve (this means you!)

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Self-Pierce Riveting

• Mechanical joining process / aluminium
• Handheld, pedestal or automated
• High speed, single operation, no prep
• Fully pierce top materials partially pierce
  bottom material

Joint creation process.
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Self-Pierce Riveting
A cross section of a successful SPR joint. A
semi-tubular rivet joining three sheets of
aluminium.
Animated Joint creation process.
C-frame which accommodates the tooling.
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Self-Pierce Riveting

• Doidge Type 120 Riveting Machine
• impact riveting machine
• semi-tubular, tubular, bifurcated
• steel, brass, copper, aluminium and light alloy
• semi-tubular steel rivets
• 3.1mm diameter / 7.4mm length
• aluminium grade 1200 (BS14701987)

Doidge Type 120 Riveting Machine
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Why SPR?

• reduce emissions
• lighter vehicles
• smaller engines
• EU emissions regs
• directive 70/220/EEC
• category M1
• passenger vehicles
• 8 seat max

EU Emissions Directive 70/220/EEC.
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Why SPR?

• Traditional joining / steel body
• new light weight vehicles (ally)
• RSW is impractical for aluminium
• lower resistance than steel
• consumes more energy due to heat loss
• SPR is a viable solution
• lower power consumption
• creates an air/water tight joint
• high speed
• no insertion hole and material alignment
• pierce and fasten in one operation

Spot weld machine.
Sample spot weld.
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SPR Problems

• Poor joint access / dual access
• C-frame, die, punch
• Quality control of the joint
• Predominantly destructive (chiselling, pulling)
• Handheld ultrasonic probe
• Physical Teardown
• One car, 5000 joints, two men, 30 days
• Time, money, delayed quality control

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Current Technology

• Driven by
• increased automation
• dissimilar materials
• Decline of skilled/cheap labour force
• HENROB Ltd
• Industry leader for SPR systems
• BMW, Audi, Jaguar, Volvo, Chrysler, Mercedes,
  Freightliner and Hyundai.

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SLIDES REMOVED FOR CONFIDENTIALITY
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Project Status (Rivet Status)

• Applying camera to
• nose for rivet status
• bespoke software
• identifies light intensity
• requires calibration to ambient lighting
• pre-process

inspection point intensity values decision
Intensity profile of a missing rivet.
Intensity profile of a single rivet.
Intensity profile of a double rivet.
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Project Status (Mat. Depth)

• Applying camera and laser to
• identify material depth
• physical filters
• image processing
• identifies laser stripe
• thickness in mm and px
• pre-process
• requires joint calibration
• lens
• distance from material
• ambient lighting / threshold

A 6mm stack of sheet aluminium.
As above, with neutral density and red filters.
As above, with threshold and laser line
identification.
Screenshot of the process monitoring software.
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SLIDES REMOVED FOR CONFIDENTIALITY
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Thank You!