Green Tire Uniformity Measurement Using High Speed Laser Profile Sensors

Only available on StudyMode
  • Download(s) : 746
  • Published : November 18, 2010
Open Document
Text Preview
Green Tire Uniformity Measurement using High Speed Laser Profile Sensors

Introduction

Tire Uniformity refers to the dynamic mechanical properties of pneumatic tires as strictly defined by a set of measurement standards and test conditions accepted by global tire and car makers. These measurement standards include the parameters of radial force variation, lateral force variation, conicity, plysteer, radial runout, lateral runout, and sidewall bulge. Tire makers worldwide employ tire uniformity measurement as a way to identify poorly performing tires so they are not sold to the marketplace. Both tire and vehicle manufacturers seek to improve tire uniformity in order to improve vehicle ride comfort.

Tire Uniformity Engineers are tasked with improving uniformity by reducing variation at many steps in tire production – raw materials, component preparation, tire assembly, and curing. Executive Managers are tasked with making investments to modernize equipment to achieve those improvements. As improvements in mixing, calendering, and extrusion are realized it is more often than not the tire building process that presents the best opportunities for uniformity improvement. Green tires with better geometrical uniformity produce cured tires with better uniformity. This results in lower cost of scrap, fewer production problems, reduced uniformity grind rates, and better overall tire quality. The primary tire building non-uniformities are caused by component placement (centering and snaking), splicing (butt splice, overlapping splice, and skived splice), turn-ups, and stitching. This paper presents examples of these non-uniformities at each stage of assembly using the high speed laser profile sensor-based Green Tire Uniformity (GTU) system from Bytewise Measurement Systems. The GTU sensor is used to scan any stage of tire building, and the GTU software applies various analysis tools to determine radial runout, tread

Green Tire Uniformity Measurement using High Speed Laser Profile Sensors

snaking, turn-up edge variation, splice uniformity, and other geometrical parameters that can adversely affect the cured-tire uniformity.

Measurement Technology

Bytewise Measurement Systems produces a very-high-speed laser profile triangulation sensor (VHSL) that utilizes a laser line source and a 2-dimensional Complimentary Metal-Oxide Semiconductor (CMOS) array. These sensors acquire profiles at frequencies up to 2000 Hz. There are over 1,000 VHSL sensors in service measuring cured tire sidewall bulges and depression. The GTU model VHSLE3 sensor has a width of 300mm at a distance of 475mm and a width of 400mm at 700mm. The sensor takes 1500 points across the width for a width resolution of approximately .25mm. Resolution in the radial axis is 0.1mm. Other sizes are available including a long-range sensor with a standoff distance exceeding 1000mm. Circumferential resolution is a function of the sensor frequency, drum rotation speed, and tire circumference.

CMOS Detector

Laser Line Source

Thickness Range

Width Range
Figure 1 – The Laser Profile Triangulation Sensor utilizes a laser line source and CMOS detector to digitize profile geometry while the drum rotates

Green Tire Uniformity Measurement using High Speed Laser Profile Sensors

At the start of each scan the sensor begins acquiring profiles at a user-defined frequency and stores them in a buffer. At the end of the scan the buffer is closed and the file is batch-processed to convert the raw data into a calibrated space-frame, or coordinate system. Processing threads run the metrology applications to extract the measurement parameters like radial and lateral runout, and render the data visualization.

The scan data is visualized in a color-mapped topographical image. The horizontal axis is expressed in degrees, from 0 to 360. The vertical axis is scan lines, from 1 to 1500. Scan lines are normalized to a 16 color map covering a user-defined range, for...
tracking img