Quality appraisal of high-speed twist-free rolling mill

high-speed twist-free rolling machine uses high-speed rotating rollers and twist-free rolling technology to achieve high-precision rolling of metal materials with the help of precise roll gap adjustment and tension control. It is widely used in manufacturing fields such as steel, nonferrous metals, and precision pipes. In the steel industry, it can be used to produce high-strength rebar; in the automotive manufacturing field, it can roll high-precision gear blanks; in the aerospace field, it can be used for the forming and processing of titanium alloy thin-walled pipes. Compared with traditional rolling mills, high-speed twist-free rolling mills have significant features such as high production efficiency, high-precision control, and low energy consumption. They are key equipment in the modern metal processing industry.

Zhongke Testing is a product quality appraisal service organization registered with the court. It can provide quality appraisal services for high-speed twist-free rolling mills. It has a professional appraisal team and advanced instruments and equipment to provide fair and accurate appraisal results for the quality appraisal of high-speed twist-free rolling mills.

As the metal processing industry continues to improve its product accuracy requirements, quality dispute cases for high-speed twist-free rolling mills are also increasing. The focus of judicial disputes mainly focuses on the following aspects:

1. Disputes over performance indicators: whether the actual rolling speed can meet the contract stipulations and whether the dimensional tolerances meet the standards;

2. Material and process defects: the wear resistance of the roll material is insufficient. Jia. Improper control of the heat treatment process caused the roller surface to peel off;

3. Control system failure: the tension control accuracy exceeded the error range and the automatic roll gap adjustment function failed;

4. Contract performance issues: the delivered equipment did not match the technical agreement.

High-speed twist-free rolling mill quality appraisal mainly adopts the following technical methods:

1. Appearance inspection: Check whether there are defects in the appearance of the product, such as scratches, dents, cracks, etc.

2. Dimensional measurement: Use measuring instruments, such as micrometers, three-dimensional coordinate measuring machines, etc., to accurately measure product dimensions to determine whether they meet the design requirements.

3. Mechanical property test: Conduct mechanical property tests such as tensile strength and yield strength to evaluate whether the product strength meets the standard requirements.

4. Metallographic analysis: observe the product structure through a microscope and analyze whether there are defects or process problems.

The applicant, a steel company, and the respondent, a rolling mill manufacturing company, signed a "High-Speed Twist-Free Rolling Mill Purchase Contract", which stipulated in the contract the purchase of two HNT-800 rolling mills for the production of rebar. After the equipment was put into production, the dimensional tolerance of the rebar reached ±0.2mm, far exceeding the ±0.1mm specified in the contract, resulting in a 25% drop in product qualification rate. The steel company believed that the rolling mill had quality defects and required the manufacturing company to compensate for the losses. The manufacturing company argued that it was caused by fluctuations in raw materials, and the two parties went to court.

Identification analysis results:

The quality analysis expert group discussed and comprehensively analyzed the relevant information of the "high-speed twist-free rolling mill", contract technical agreements, on-site inspection case materials and other data, and made the following quality analysis opinions:

The roll material of the high-speed twist-free rolling mill involved is 9Cr2Mo steel, but the Cr content is only 1.8% (contract requirement ≥2.0%), the hardness is only HRC52 (standard requirement HRC55 - 60), and the wear resistance is insufficient. The roll gap adjustment system was not calibrated regularly, and the positioning error reached ±0.03mm (the standard should be ≤±0.01mm). The dynamic balance correction of the roll did not meet the standard requirements, and the residual imbalance was 15g·cm (the standard should be ≤5g·cm), resulting in increased vibration during the rolling process.

The rolling mill manufacturing company failed to provide roll materials that met the requirements in accordance with the contract, and the process parameter control was not up to standard, which constituted a fundamental breach of contract.

High-speed twist-free rolling mill quality appraisal report should include the following content:

1. The purpose and basis of the appraisal.

2. Model, specification, manufacturer and other information of the equipment being identified.

3. Identification method.

4. Identification results (including whether there are quality problems, causes of problems, etc.).