Non-contact inline and offline measurement and inspection systems for rubber strip and tyres

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In rubber processing and tyre production, non-contact inline and offline measurement and inspection systems can provide significant benefits in process monitoring and quality control, says Glenn Wedgbrow, Business Development Manager at Micro-Epsilon UK.

 

Many rubber processing and tyre manufacturing companies seek to use inline inspection and measurement equipment to provide continuous monitoring of the process to ensure quality at every stage. Micro-Epsilon is a measurement specialist in this field and offers a range of non-contact, inline and offline measurement and inspection systems for process monitoring and quality control. These include specific measurement systems for rubber processing applications, including systems for measuring strip thickness, length, width and profile of rubber strip and sheet. Specific systems have also been developed for the measurement of tyres for passenger, truck and commercial vehicles, including systems for measuring the thickness profile of tyres, tyre treads, sidewalls and inner tube linings, as well as systems for measuring other critical dimensions of tyres and for colour coding or marking of tyre treads.

These innovative, robust, complete turnkey measurement systems offer distinct technical advantages in terms of measurement accuracy, thermal stability and reliability, backed up by installation, servicing, maintenance and technical support.

These technical advantages include fully automatic calibration. The systems periodically re-measure against a known reference and have integrated measurement sensors in the framework and mechanical parts, which measure the thermal expansion of the system. The software then compensates accordingly.

Micro-Epsilon’s range of measurement systems for rubber strip and tyres comprises the following:

Inline & offline profile measurement of strip thickness

Offline and inline profilomter systems measuring rubber
Micro-Epsilon offers a range of non-contact, inline and offline measurement and inspection systems for measuring strip thickness, length, width and profile of rubber strip and sheet.

Part of Micro-Epsilon’s thicknessCONTROL family, the RTP 8302 is a C-frame system that measures the thickness profile of rubber strip and sheet. C-frame systems are modular in their design, offering flexibility and high performance. They can be installed in tyre production lines, extruders, roller heads, calendar lines and inspection rooms, providing reliable, high precision measurement results that creates a basis for controlling the production process and product quality.

C-frame systems measure differentially. An application-specific (confocal, capacitive or laser triangulation) displacement sensor is integrated in the upper and lower arms of the C-frame. The thickness of the target material is derived from the distance between the two sensors and the resulting signals. By combining highly efficient signal processing algorithms and visualisation software, the system is able to achieve accuracies in the sub-micrometre range.

The C-frame can be used as a traversing thickness measurement system on linear axes in order to ensure full width measurements of the target profile. The control and analysis software is developed in-house by Micro-Epsilon specifically to match the needs of the rubber processing and tyre manufacturing industries, providing all the required functions in order to continuously record and evaluate production quality. This includes graphical user interfaces and the ability to store multiple product libraries. Also, the software supports and displays Statistical Process Control (SPC) parameters and other ‘Process Capability’ analysis and reporting methods such as Six Sigma ĈPK and ĈPM. Various fieldbus interfaces are available, which enable integration to the customer’s production control systems.

Fully automatic calibration ensures that measurements are not affected by temperature, enabling the system to be installed as a fixed, inline measurement system in harsh production environments, without the need for calibration or manual adjustments. All sensor technologies used are non-contact, wear-free and do not use isotopes or X-rays. The C-frame system provides long-term measurement reliability at an affordable price. C-frame systems can be used to measure strip widths up to 1m and strip thickness from <1mm up to 18mm. Accuracies are from +/- 5µm.

Measurement systems for tyres

Before a tyre set is delivered by the manufacturer, the tyres undergo a complex test procedure. Various parameters are tested, from tread width to tyre geometry. Only when these tests have been completed and successfully passed can the tyre make its way onto the road. The audit has enabled the error rate to be continuously reduced in recent years. This also reduces the risk of accidents and makes cars much safer. Various inspection, monitoring and control technologies are required to make the test procedures possible. Micro-Epsilon offers a wide range of different measurement technology solutions for tyre production.

Inline weight inspection of running tread profiles for passenger and truck tyres

The dimensionCONTROL TMWI 8302.LC system is suitable for the inline weight inspection of continuous running rubber profiles (tread pattern or sidewalls) for passenger and truck tyres. Based on the force measurement principle, the inspection system uses two load cells that measure the deflection of the measurement conveyor. These sensor elements are attached to a massive construction, which ensures a long-term mechanical stability of the system. The measurement conveyor uses precise and balanced aluminium rollers with special surface treatment. This ensures a low deadweight, avoids influence of unbalance and eliminates material sticking. Data obtained from the load cells are processed in the implemented PLC cards which determine the measured weight mathematically. The software included offers a variety of measurement data processing, definition of design profiles, statistical analysis of measured profiles and diagnostic tools.

Tyre geometry inline inspection in TU machines

Tyre uniformity machine
Micro-Epsilon offers a range of non-contact, inline and offline measurement and inspection systems for measuring the thickness profile of tyres, tyre treads, sidewalls and inner tube linings.

Monitoring tyre geometry i.e. the measurement of radial or lateral unbalance, as well as side wall detection for bulges, constrictions, dents etc., is one of the most important inspections at the end of the production process. The TGI 8302.LLT system can be easily integrated while offering precise measuring results. The TGI 8302.LLT system uses three profile sensors which reliable detect bulges and constrictions as well as radial and axial unbalance. The sensors are integrated in a robust mechanics and applied in such a way that the total surface of the tyre can be detected within one rotation. Thereby, the tester visualises the tyre surface, hides the tyre lettering, enables filtering of data, performs a vibration check, inspects the tyre size and classifies the degree of a defect.

Non-contact inline profile measurement of inner liner material

During the production of inner liners, the thickness profile of inner liner material is measured immediately after the calender using the thicknessCONTROL TIP system. Accurate precision of the non-contact optical system ensures high quality and security of the product produced. Being equipped with optical sensors, systems of the TIP family are designed as O- and C-frames. Temperature fluctuations of the measuring mechanics are also detected using distance and temperature sensors and are therefore algorithmically compensated.

Non-contact inline profile measurement of tread strips

The profilometer of the thicknessCONTROL.TTP series accurately measures the thickness profile of tyre tread or side walls during the extrusion process and therefore enable efficient control during production, as well as fully documented quality control. TTP systems are equipped with optical sensors and have an application-specific operators’ front end which provides all necessary data regarding the organisation of the extrusion process of running surfaces and side walls.

Offline profile thickness measurement of tread strips and side wall material

The profilometer thicknessCONTROL TCP8301.T-Offline is used for sampling regarding the extrusion process of treads, side wall and inner liner material. The system offers high precision measurements and therefore enables efficient production as well as fully documented quality control. The system is equipped with optical sensors and has an application-specific operators’ front end which provides all necessary data regarding the organisation of the extrusion process of treads and side walls. The TCP8301.T-Offline is based on laser triangulation sensors and therefore ensures the measurement being independently from material constants. In order to ensure highest precision, the laser beams of the sensors are accurately adjusted during the production process using optoelectronic tools which have been specially developed. Offering easy operation, the system provides an in-situ calibration unit and ensures high precision.

Non-contact inline length measurement of tread strips

For tyre production, tread strips are cut from the extruded strip material. The TLS 8303.I optical testing system is applied in the extrusion line to measure the length of the strips immediately after the cutting machine in order to ensure a secure production process in high quality. At the TLS 8303.I, rubber strips for tyre production are inspected for their profile and length characteristics. Two cameras record the cutting edges of the strips. Deviations from the nominal cutting edge are detected by an intelligent composition proceedings. The cutting edges are compared to each other in order to evaluate the strip lengths. Therefore, the pictures are revalued using a stabiliser filter and different algorithms.

Inline inspection of colour codes on treads

The TCC 8303.I system marks the running surface which is output after the extruder, inspects the colour lines for their completeness and measures the width of the running strip. The integrated TCC 8303.I system was developed for the inspection of colour codes on running surfaces of tyres. The cartridges for the marking are inserted in a holder. A pneumatic height adjustment and servo-controlled horizontal positioning ensure a straight line and optimal position of the code lines. The colour code is immediately inspected by an image processing system.

For more information on measurement systems for rubber strip and tyres, please visit www.micro-epsilon.co.uk or call the Micro-Epsilon sales department on +44 (0)151 355 6070 or email info@~@micro-epsilon.co.uk

Further Information

Systems for Tyre and Rubber
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