How to optimize the processing technology of precision carving machine for knife die?

The core of optimizing the processing technology of the precision carving machine of the knife mold is to build a standardized process system from five dimensions, namely, path planning, parameter matching, tool tooling, process control and post-processing optimization, around three major goals, and the specific measures are as follows:

Optimize machining path to reduce invalid cutting and deformation.

Hierarchical and regional machining: according to the different characteristics of the die, such as slot sticking, hollowing out and outer contour, the machining areas are divided and the principle of "coarse before fine, external before internal, shallow before deep" is followed. During rough machining, most of the allowance is quickly removed (0.1~0.2mm allowance is reserved for finishing), and the finishing adopts small cutting depth and high rotating speed to improve the surface quality; Deep groove machining is divided into multi-layer cutting (the depth of each layer is less than or equal to 1 mm), so as to reduce the stress on the tool and avoid edge collapse or deformation of the substrate.

Optimization of corners and sharp corners: the sharp corners in CAD drawings are changed into transition arcs of R0.2~R0.5mm to avoid the vibration and edge collapse caused by frequent tool reversal at sharp corners; When machining corners, reduce the feed speed (down to 50%~70% of the normal speed) to ensure accurate corner contour.

Reserved connecting bridge and support: when machining the hollowed-out knife die, a small connecting bridge (width 0.5~1mm) is reserved between the hollowed-out area and the base material to prevent the hollowed-out parts from falling off and hitting the machine tool during machining; After the whole machining is completed, the connecting bridge is removed manually to avoid machining deformation.

Reduce the number of tool lifting: optimize the tool path through CAM software and adopt the combined mode of "ring cutting+parallel milling" to avoid frequent tool lifting and cutting, reduce non-cutting time and improve machining efficiency.

Accurately match the machining parameters and realize the "material-tool-parameter" collaboration.

Adjust parameters according to substrate

Rubber board/density board (carton die): Double-edged spiral milling cutter is selected, the spindle speed is 12,000 ~ 18,000 r/min, the feed speed is 3~5m/min, the cutting depth is 0.5~1mm, and air cooling is used to remove chips, so as to avoid the deformation of the substrate caused by cooling liquid.

Aluminum plate/thin steel plate (gift box die): Choose cemented carbide coated cutter or diamond cutter, with spindle speed of 18,000 ~ 24,000 r/min, feed speed of 1~2m/min, cutting depth of 0.3~0.5mm, and high-pressure cooling oil to prevent aluminium scrap from sticking the cutter and blocking the slot.

Indentation groove processing: the parameters are slightly lower than that of cutter groove processing, so as to reduce the feed speed, ensure the smooth groove wall and avoid loosening of the indentation line after embedding.

Adjust the parameters according to the machining stage: rough machining pursues efficiency and adopts "high speed, large feed and moderate cutting depth"; Precision machining pursues precision, and adopts "higher rotation speed, small feed and small cutting depth" to reduce the influence of tool wear on precision.

Upgrade tools and fixtures, and lay a solid foundation for process optimization.

Tool selection and management: give priority to the use of special die processing tools, double-edged spiral milling cutter for rubber sheet processing (good chip removal) and single-edged milling cutter for metal processing (reducing tool sticking); Establish a tool life ledger, and sharpen or replace the finishing tool in time after machining 50~100 pieces of die to avoid edge collapse and size deviation caused by tool passivation.

Optimization of fixture: vacuum adsorption fixture is used for rubber/MDF to increase the adsorption area and ensure that the substrate is flat and warpage-free; The metal substrate adopts multi-point pressure plate fixture, and the stress points are evenly distributed to avoid the deformation of the substrate caused by excessive local stress; For large-size knife dies, an auxiliary support table is installed to reduce the vibration during machining.

Tool compensation calibration: before machining, the length and radius of the tool are automatically measured with the probe of the machine tool to generate compensation parameters; During the machining process, the tool wear is sampled every 2 hours, and the compensation value is adjusted in time to ensure the stable machining accuracy.

Strengthen process control and realize dynamic precision guarantee.

On-line detection and real-time compensation: By using the probe detection function of the engraving machine, the key dimensions of the tool die (such as slot width and outline size) are detected in real time during machining. If deviation is found, the system automatically adjusts the machining parameters or tool compensation value to form a "machining-detection-compensation" closed loop.

Environment and equipment control: keep the processing environment at constant temperature (20 2℃) and constant humidity (40%~60%) to avoid thermal deformation of the substrate or machine tool caused by temperature and humidity changes; Before machining, let the machine run for 15 minutes without load, so that the spindle and guide rail can reach a thermal balance state; Regularly clean the debris on the guide rail and lead screw, and add special lubricating oil to ensure the movement accuracy of the machine tool.

Quality traceability and process iteration: record the processing parameters and test data of each batch of knife dies, analyze the reasons and optimize the process parameters in view of the problems such as edge collapse and size deviation, form a standardized process library, and directly call the mature parameters for subsequent similar knife dies.

Optimize the post-treatment process to improve the quality and life of the finished product of the knife die.

Deburring and cleaning: after the tool die is processed, use sandpaper or deburring machine to clean the burrs on the card slot and edge to avoid scratching the packaging materials during die cutting; Cleaning agent should be used to remove the oil stain and aluminium scrap on the surface of metal die to prevent corrosion.

Stress release and moisture-proof treatment: the rubber sheet is placed in a constant temperature and humidity environment for 24 hours after being processed, so as to release the processing stress and avoid later deformation; Spray moisture-proof paint on the surface of the knife die used in humid environment to prolong its service life.

Tool bar assembly and adaptation: accurately select the tool bar according to the size of the slot, ensure that the tool bar is vertically embedded and the cutting edge is flush during assembly, and improve the accuracy and stability of die cutting.