Quality appraisal of CNC boring and milling head

CNC boring and milling head is the core functional component of CNC machine tools. By integrating high-precision spindle, feed system and intelligent control module, it can realize multi-process processing such as boring, milling and drilling of metal materials. CNC boring and milling heads can be used in automotive mold manufacturing: processing precision components such as new energy vehicle battery casings and gearbox cases (such as the case of an automobile mold company that caused processing losses due to casting quality problems); aerospace and aviation fields: completing high-precision processing of complex curved surfaces such as spacecraft cabins and engine blades (such as the "zero-defect" manufacturing requirements for Shenzhou series products); high-end equipment manufacturing: processing deep-hole boring and surface milling of nuclear power pressure vessels and marine engineering equipment.

Compared with traditional mechanical boring heads, CNC boring and milling heads have become key equipment for upgrading modern manufacturing industries with their fully closed-loop control, multi-axis linkage and adaptive processing capabilities. Its technical level directly affects product accuracy, production efficiency and energy consumption, and is an important indicator of the country's high-end manufacturing competitiveness.

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

With the development of intelligent and sophisticated equipment, there has been a significant increase in CNC boring and milling head quality disputes. The judicial dispute focuses on:

1, performance index disputes: such as whether the radial runout of the spindle meets the standard, whether the cutting vibration amplitude exceeds the limit;

2, material and process defects: bearing material degradation, heat treatment process The main spindle is deformed due to substandard technology;

3. Control system failure: the feed axis positioning accuracy is too poor and the cutting parameter automatic compensation function is missing;

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

CNC boring and milling head quality appraisal technical methods include:

1, material performance testing

using a spectrometer to detect the spindle material and verify the heat treatment process; detecting internal defects in the weld through ultrasonic flaw detection, X-ray detection of box casting shrinkage holes and blisters; three-coordinate measurement of spindle taper hole coaxiality and ram guide straightness.

2, performance parameter test

The laser interferometer measures the radial runout and axial movement of the spindle, and the modal analysis determines the critical speed; the force sensor collects the dynamic load during the milling process and evaluates the rigidity of the transmission chain; the infrared thermal imager scans the spindle temperature rise curve to verify the effectiveness of the constant temperature cooling system.

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A precision manufacturing company of the applicant signed a "CNC Boring and Milling Head Procurement Contract" with an equipment supplier of the respondent, agreeing to purchase 5 high-precision boring and milling heads for the processing of new energy vehicle battery casings. After the equipment was put into production, the hole size of the processed shell was out of tolerance (±0.03mm), and the surface roughness Ra value reached 1.6μm (standard ≤0.8μm), resulting in customer returns. The manufacturing company believed that the equipment had a design defect and demanded compensation for damages. The supplier argued that the problem stemmed from improper operation, and the parties went to court.

Identification analysis results:

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

1, the spindle material of the CNC boring and milling head involved is 45 steel (contract requirements) 40Cr), the hardness is only HRC28 (standard ≥HRC45), resulting in deformation during cutting; the bearing roller surface peels off, and the material carbides are unevenly distributed (SEM-EDS testing shows insufficient Cr content).

2, the ram guide rail span of the CNC boring and milling head involved in the case is too short (design value 600mm, actual 550mm), the vibration amplitude during milling reaches 0.08mm (standard ≤ 0.05mm); the cooling system is not equipped with a temperature compensation module, and the spindle thermal elongation reaches 0.02mm/℃ (standard ≤0.01mm/℃).

CNC boring and milling head 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.).