1. Processing technology planning
Before machining the high-precision hole system of the hydraulic valve body, the processing technology needs to be carefully planned. First, the structure and hole system distribution of the valve body should be deeply analyzed to determine the reasonable processing sequence. Generally, the reference hole is machined first, and the position accuracy of other holes is guaranteed based on this. For example, for a valve body with mutually perpendicular hole systems, the main reference hole in one direction can be machined first, and then the holes in the perpendicular direction can be machined based on it. At the same time, the appropriate cutting tool and cutting parameters should be selected according to the hole accuracy requirements and material properties. For high-precision small holes, carbide drills can be used, and higher speeds and smaller feed rates can be used to reduce the impact of cutting forces on hole accuracy; for large holes, boring tools may be required to ensure the cylindricity and surface roughness of the holes.
2. Tool and fixture selection
The selection of tools is directly related to the hole system processing accuracy. Special tools should be selected for different hole diameters and processing requirements. For example, twist drills, reamer drills, and reamers with high-precision grinding and coatings should be used. For deep hole processing, internal cooling drills can be used to effectively cool and remove chips to prevent scratches on the hole wall and reduced precision due to chip accumulation. The tooling fixture is even more critical, and a special fixture needs to be designed to ensure that the valve body is accurately positioned and firmly clamped during processing. For example, the positioning method of one side and two pins can effectively limit the six degrees of freedom of the valve body and ensure the relative position accuracy of each hole during processing. And the rigidity of the fixture should be good to avoid deformation due to force during processing, which affects the processing accuracy of the hole system.
3. Processing equipment and cutting parameter optimization
High-precision hole system processing requires extremely high accuracy and stability of the equipment. Usually, a machining center or CNC boring and milling machine with high rigidity, high-precision spindle and positioning system is selected. The spindle runout of the equipment should be controlled within a very small range, such as not exceeding 0.005mm, to ensure the stability of the tool during rotation. In terms of cutting parameter optimization, the optimal parameters are determined by combining experiments and empirical data. For example, the selection of cutting speed should take into account the tool material, valve body material and hole accuracy requirements. Generally speaking, for carbide tool processing of medium carbon steel valve body, the cutting speed can be between 80-150m/min, the feed rate is between 0.05-0.15mm/r, and the cutting depth is determined according to the hole size and allowance, but it is necessary to ensure that the cutting force is stable during the processing to avoid vibration that affects the surface quality and accuracy of the hole.
4. Quality inspection and error compensation
Real-time quality inspection should be carried out during the processing, and an online measurement system can be used or spot checks can be carried out after key processes. The diameter, cylindricity, position and other parameters of the hole are detected by high-precision measuring equipment such as a three-coordinate measuring machine. Once an error is found, it is necessary to analyze and compensate it in time. For small dimensional errors, it can be corrected by adjusting the radial compensation amount of the tool; for position errors, it may be necessary to readjust the fixture or optimize the processing technology. For example, if the position of the hole is deviated, the positioning element of the fixture can be checked for wear or looseness, and repaired or replaced in time, and then reprocessed to ensure that the accuracy of the final hole system meets the design requirements of the hydraulic valve body and ensure the stable and reliable operation of the hydraulic system.
