EUROPEAN COMMISSION SEVENTH FRAMEWORK PROGRAMME THEME SME Research for benefits of SME Association

Transcription

1 EUROPEAN COMMISSION SEVENTH FRAMEWORK PROGRAMME THEME SME Research for benefits of SME Association GA No Classification of retreated truck tyres in order to comply with future environmental performance and safety requirements Deliverable No. Deliverable Title Dissemination level Written By RETYRE D2.3/D3.3 Cold retreaded tyres for rolling resistance, noise emission and wet grip measurements Public Anna Molinari (KCL), Michael Schwämmlein (BRV) & WP2 partners Revised Jan 2014 Checked by David Gallegos (IDIADA), WP leader Approved by Ruud Spuijbroek (KCL) Technical Coordinator Issue date /9

2 Executive summary This document reports on the procedure followed to prepare the Cold retreaded tyre or Pre Cure The same procedure for the preparation of the cold retreaded tyres has been followed both for WP2 (focused on the determination of the influence of the retreading process on the tyres performances) and WP3 (focused on the determination of the influence of the applied tread on the tyre performances). Due to the public nature of the document, no confidential information over the matrix of the selected tyres has been included in this report (those information can be found in D2.1 and D3.1). For the reasons mentioned above the two deliverables D2.3 and D3.3 have been combined in one document. 2/9

3 Content 1 Introduction Methods and results... Fout! Bladwijzer niet gedefinieerd. 2.1 Procedure applied: Preparation of HOT and COLD retreaded tyresfout! Bladwijzer niet gedefinieerd. 3 Risk Register Conclusion... Fout! Bladwijzer niet gedefinieerd. 5 Acknowledgment /9

4 1 Introduction A tyre consists of several parts and layers (see figure below). Parts that are particularly relevant for the retreading process are: the casing (carcass), the undertread, the tread and the shoulder. Fig.1: Tyre structure 4/9

5 2 Preparation of COLD retreaded tyres The following retreading parameters will be investigated for the COLD retreading process: buffing radius and thickness of undertread, etc. The selected tread type will be kept constant. Selected European retreaders (relevant involvement of end-users) will prepare mould-cured (hot) retreaded tyres according to the standard procedure defined in Task 2.1 Casings have been collected and selected (following the procedure reported in the following section) by Banden Plan Europa (BPE, partner 6), the retreading process has been performed by another partner in the project: R.I.G. (Partner 9) with the collaboration and support by Kraiburg (Partner 14). 2.1 Retreading processes Used truck tyres are purchased from transport companies by vendors and sent to the retreading company. At the retreading companies, the retreading starts with a quality inspection of the used tyre. Once the casing has been approved for the retreading process the original tread is removed. After this step the buffed casing is re-examined for any further damage which needs to be addressed before the retreading process takes place. New tread rubber is then applied to the buffed "casing" using special bonding rubber to vulcanize tread and casing together (cushion gum), sometimes a rubber solution is also (pre-)applied to tread and casing. Two different manufacturing processes exist for retreading: Pre-cure retreading (cold) and Mould-cure retreading (hot). Below is described the Pre-Cure (or Cold ) retreading process. Fig.2: Casing inspection Fig.3: Buffed casing 5/9

6 Pre-cure Retreading Process or Cold Retreading 1 Pre-cure retreading involves vulcanization without a mould at a temperature of between 95 C and 120 C. The tyre is assembled using a pre-vulcanized tread (= new tread) and a non-vulcanized bonding gum layer. The final bond between the casing, the bonding gum and the pre-cured tread is created by heat and pressure in an autoclave. Pre-cure tread retreading or cold retreading is the replacement of the worn tread areas with pre-vulcanized treads containing the tread design already vulcanised. Fig. 4 Application new tread Fig. 5 Pressurized chamber All steps of the retreading process are performed according to quality standards provided by ECE Regulation No 109. The Regulation also provides specifications and performance requirements tyres need to comply with. 1 Pictures courtesy of Bandag and BPE/Kargro Group ( 6/9

7 3 Cold retreaded tyres prepared for testing WP2 of the ReTyre project is dealing with the major process parameters in a retreading operation. Besides the process types (hot and precure/cold process) the geometrical parameters like undertread thickness and buffing radius have been analysed. The parameter range has been determined through the theoretically allowed range descripted in the ECE - R 109 as well as the real minimum and maximum values to be found and possible in the workshop. The undertread thickness, with a theoretically allowed range from 3-13 mm, is for example not really represented in "real life" due to the fact, that normally there is always a remaining rubber layer left on the casing (above the breaker/belt package) for adhesion reasons ( 1-4 mm thick). Also the new applied material, no matter whether a mould-cure or pre-cure method is used will always have a certain rubber layer below the deepest tread groove for stability reasons (e.g. precure treads, 3-5 mm). Taking this into consideration the realistic range does not start with 3 mm but with 5 to 7mm. A comparable limitation is given for the buffing radius. The new tyre has a certain radius out of the tyre construction given by the radius of the new tyre mould. A retreader is trying to select a buffing radius in relation to this "preset" from the new tyre, the tread width and the desired or needed undertread. Also here there are "natural" limits given by the original tyre shape and the position of the belt package below the tread which need to stay embedded in rubber during the retreading process. That means that if for example a too small buffing radius would be selected the belt edges would be hit by the buffing knives (causing the casing to be scrapped) and the undertread width would have a high value in the centre of tread, descending to the shoulders. In reverse a too large radius would have the opposite effect: The buffing knives would hit the breaker in the tread centre and the undertread thickness would increase towards the shoulders. WP3 of the project is dealing with the tread applied during the retreading process. To investigate the influence of the different compositions different tread compounds ranging from 100% natural rubber to 100% synthetic rubber have been selected. Also in this case, as for WP2, the most common compounds have been taken into consideration. 7/9

8 4 Risk Register Risk No. What is the risk Level of risk Failures whilst manufacturing retreads. 3 (low) 2.3 Difficult in test planning due to the ongoing delay in few tests 2.2 Availability of testing equipment, due to the enormous increase of demand caused by the implementation of the new tyre label. 3 (low) 2 (medium) Solutions to overcome the risk During the purchase this particular potential liability was discussed. Following that discussion we increased the number of casings with #1. During our discussion with Research Performers the issue was discussed in depth. They assured us of our preferred position. 2 Risk level: 1 = high risk, 2 = medium risk, 3 = Low risk 8/9

9 5 Acknowledgment This project is co-funded by the 7th FP (Seventh Framework Programme) of the EC - European Commission DG Research Disclaimer The FP7 project has been made possible by a financial contribution by the European Commission under Framework Programme 7. The Publication as provided reflects only the author s view. Every effort has been made to ensure complete and accurate information concerning this document. However, the author(s) and members of the consortium cannot be held legally responsible for any mistake in printing or faulty instructions. The authors and consortium members retrieve the right not to be responsible for the topicality, correctness, completeness or quality of the information provided. Liability claims regarding damage caused by the use of any information provided, including any kind of information that is incomplete or incorrect, will therefore be rejected. The information contained on this website is based on author s experience and on information received from the project partners. 9/9