How to ensure the machining accuracy when the precision carving machine processes the fiber bottom die?

In order to ensure the precision of the fiber bottom die processed by the carving machine, it is necessary to control the five core links: material fixation, cutting tools and parameters, path planning, process control and precision detection. The specific measures are as follows:

Ensure that the material clamping is stable and smooth, and eliminate the benchmark error.

Fiber bottom die (carbon fiber, glass fiber, etc.) is brittle and easy to delaminate. When clamping, vacuum sucker (suitable for flat plate) is preferred, and the material is adsorbed by uniform negative pressure to avoid material deformation caused by local pressure of rigid fixture; If the material size is small, it should be fixed with rubber battens and bolts, and the battens should cover the edge of the material to prevent warping and displacement during processing.

Before clamping, the dust and impurities on the workbench and the bottom of the material must be cleaned to ensure that the material is completely attached to the workbench; If the material itself is slightly warped, a thin heat-conducting silica gel sheet can be placed at the bottom, and it can be leveled by the pressure of vacuum adsorption.

Taking the flat edge of the material as the machining benchmark, the edge finder is used for calibration in advance to reduce the benchmark positioning deviation.

Match special tools with precise parameters to reduce cutting deformation.

Tool selection is the core: diamond coated carbide milling cutter (sharp cutting edge and strong wear resistance) is preferred to avoid machining dimension deviation caused by wear of high speed steel tool; For fiber materials, double-edged or triple-edged flat-bottomed knives are selected, and the cutting edge angle is suggested to be 30-45, so as to reduce the pulling of fibers during cutting and reduce the risk of edge collapse and surface fuzzing.

Cutting parameters need to be accurately adapted:

Spindle speed: 18,000-24,000 r/min (high speed can reduce the contact time between tool and material and reduce fiber tearing);

Feed speed: 800-1200mm/min (too fast feed will easily lead to material deformation and out-of-tolerance size, while too slow feed will aggravate tool wear);

Cutting depth: The single cutting depth should be controlled at 0.2-0.5mm, and layered milling should be adopted (especially when processing deep grooves or thick materials) to avoid excessive single cutting load leading to tool deflection.

Optimize machining path planning to avoid cutting stress and deformation.

Follow the principle of * * "rough before fine, inside before outside": 80%-90% of the allowance is removed in the rough carving stage, and 0.1-0.2mm** of the fine carving allowance is reserved; In the carving stage, small feed and high rotation speed are adopted to ensure dimensional accuracy and surface smoothness.

The forward milling method is preferred for contour machining: the cutting direction of the cutter is consistent with the feeding direction of the material, and the cutting force is stable, which can reduce the edge collapse of the fiber material and the deviation of the cutter, and improve the dimensional accuracy by 0.02-0.05mm compared with the reverse milling.

Avoid continuous machining of narrow grooves or sharp corners: set an arc transition path at the sharp corners to prevent the tool from staying at the sharp corners and causing local overheating and carbonization; When machining a large area plane, reciprocating layered milling is adopted, and spaced heat dissipation paths are set to avoid material deformation due to continuous cutting.

Strengthen the control of machining process and reduce external interference.

Continuous cooling and dust removal: use a high-pressure air gun (0.3-0.5MPa pressure) to continuously purge the cutting area, and clean up the fiber dust in time to prevent the dust from adhering to the surface of the tool or material and affecting the cutting accuracy; If the machining accuracy is extremely high (within ±0.01mm), it can be matched with micro atomized cutting fluid (special water-soluble cutting fluid) to reduce the tool temperature and avoid dimensional deviation caused by thermal expansion of the tool.

Keep the equipment running stably: before machining, check the radial runout of the main shaft of the engraving machine (the runout should be ≤0.005mm) and calibrate the accuracy of the guide rail regularly; Close the protective door of the equipment during machining to avoid external vibration and airflow interfering with the spindle operation.

Avoid continuous processing for a long time: every 30-40 minutes of processing, pause for 5-10 minutes to let the tool and materials dissipate heat to prevent thermal deformation from affecting accuracy.

Accurate detection and post-processing, control the final accuracy.

In the process of machining, set up sampling inspection: after the rough carving is completed, use calipers and micrometers to detect the key dimensions, and adjust the fine carving parameters in time if there is any deviation; In the carving stage, online measurement is adopted (some high-precision carving machines have their own measuring heads) to compensate the size error in real time.

The finished product inspection needs to be comprehensive: the flatness, aperture, outline size and other key indicators should be detected with a two-dimensional image measuring instrument, and the tolerance should be controlled within the drawing requirements (the common precision of fiber bottom die requires 0.02-0.05 mm); If there are slight burrs on the surface, use fine sandpaper with 1000 mesh or more to gently polish along the fiber direction to avoid damaging the dimensional accuracy.

Post-treatment deformation prevention: the processed fiber bottom die should be placed on a flat tooling plate to avoid stacking and extrusion and prevent deformation during storage.