Quality appraisal of roadheader

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tunnel boring machine is an efficient construction equipment used in tunnel engineering, coal mining and other fields. It realizes integrated operations of rock crushing, tunnel excavation and support by integrating cutting, shipping, supporting and other functions. Its application scenarios include railway and highway tunnel construction (such as processing hard rock formations in mountain crossing projects), coal mine roadway development (coping with high-hardness coal seam mining), urban subway construction (taking into account efficiency and environmental protection requirements), and water conservancy projects. It is the core equipment for dealing with complex geological conditions in infrastructure construction.

Zhongke Testing is a product quality appraisal service organization registered with the court. It can provide quality appraisal services for tunnel boring machines. It has a professional appraisal team and advanced instruments and equipment to provide fair and accurate appraisal results for tunnel boring machine quality appraisal.

With the scale of projects and the complexity of technology, tunnel boring machine quality disputes occur frequently. The focus of judicial disputes is:

1, disputes over performance indicators: such as whether the rock breaking efficiency reaches the standard, and the life of the main bearing is insufficient;

2, materials And process defects: the material of the pick is degraded and the welding process is not up to standard, resulting in structural cracks;

3. Control system failure: misjudgment of the coal and rock identification algorithm and the lack of automatic correction function cause tunnel over-excavation;

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

0In such cases, quality appraisal needs to be combined with failure analysis, working condition simulation and standard compliance verification to provide technical support for the court to determine liability for breach of contract and promote industry standardization and intellectual property protection.

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tunnel boring machine quality appraisal technical methods include:

1, material performance testing

using a spectrometer to detect pick material and verify the heat treatment process; detect internal defects in the frame welds through ultrasonic flaw detection, and evaluate surface cracks using magnetic particle testing (MT).

2, geometric accuracy verification

The laser interferometer measures the positioning accuracy of the cutting head (±0.05mm) and the straightness of the guide rail (≤0.02mm/m); the three-coordinate measurement of the cutterhead tooth seat spacing verifies the consistency with the design drawings (such as deviation ≤±0.1mm).

03, dynamic performance test

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2 The force sensor collects the load curve during the cutting process to verify the rated power and rock breaking efficiency; the acceleration sensor analyzes the vibration amplitude, and the modal analysis determines the resonance frequency.

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44. Control system evaluation

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6The servo motor encoder detects the displacement accuracy of the cutting arm and verifies the position loop gain parameters; calls the PLC program and analyzes the logic of the coal and rock identification algorithm.

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85, failure mode analysis

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0 Scanning electron microscope (SEM) was used to observe the fracture morphology of the main bearing, and energy dispersive spectrometer (EDS) was used to detect the migration of wear elements; the cutterhead stress distribution was analyzed based on finite element simulation, and the structural design was optimized.

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The applicant, a tunnel engineering company, and the respondent, an equipment manufacturing company, signed the "EBZ200 Type Boring Machine Procurement Contract", agreeing to purchase 2 pieces of equipment for tunnel excavation in coal mines. After being put into operation, the cutting head broke frequently, and the monthly footage was only 180 meters (300 meters as agreed in the contract). The misjudgment rate of the coal and rock identification system exceeded 10%, resulting in over-excavation of the tunnel. The engineering company believed that the equipment had design defects and demanded compensation for losses. The equipment company argued that the problem stemmed from improper operation, and both parties went to court.

Identification analysis results:

The quality analysis expert group discussed and comprehensively analyzed the relevant information of the "header", contract technical agreement, on-site investigation case materials and other data, and made the following quality analysis opinions:

The pick material of the roadheader involved in the case is 42CrMo, with a hardness of only HRC45 (standard ≥HRC60), insufficient wear resistance; micro-cracks appeared in the heat-affected zone of the cutterhead welding, and post-weld heat treatment was not performed to eliminate stress; the cutting head rotation speed and the advancement speed were unreasonably matched, resulting in local stress concentration (simulation showed that the maximum stress reached 750MPa, far exceeding the material limit); the coal and rock identification sensor layout position deviated from the optimal area, and the signal acquisition error reached ±15%.

The equipment company failed to provide equipment that met the material and precision requirements according to the contract, which was the main reason for the equipment problems.

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Tunnel boring machine quality appraisal report should include the following content:

1. Appraisal purpose and basis.

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.).

05. Identification conclusion.

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26. Signature and seal of the appraiser, and official seal of the appraisal institution.

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