Five high-speed milling processing requirements for CAM systems
High-speed machining has special processing requirements different from traditional machining. Therefore, the CNC automatic programming system CAM system applied at high speed must meet the corresponding special requirements.
(l) The CAM system should have a high computational programming speed. Very high feed rates and depths of cut are used in high-speed machining. Therefore, it takes a long time to calculate the NC program. It is very important that the CAM calculation speed is fast and convenient. In addition, the fast programming speed allows the operator to compare multiple machining strategy strategies to take the best possible solution and edit and optimize the tool path for optimum machining efficiency.
(2) The important feature of high-speed machining is the ability to machine complex molds with smaller diameter tools. The system automatically prompts the minimum clamp length and automatically performs tool interference checks, which is very important for high speed machining.
(3) The feed rate optimization processing function, in order to ensure the maximum cutting efficiency and ensure the safety of machining during high-speed cutting, the feed rate should be optimized automatically by the CAM system according to the processing instantaneous margin. .
(4) A rich processing strategy that meets the requirements of high-speed machining. Compared with the traditional method, high-build machining has special requirements for the machining process. Therefore, the CAM system is required to meet these specific process requirements. ☆ The tool path should be avoided. A sudden change in the direction of the knife to avoid damage to the tool or equipment due to partial overcutting. ☆ Full automatic overcutting resistance and automatic toolholder interference inspection. The processing is processed at a cutting speed that is nearly 10 times higher than conventional machining. The occurrence of overcutting, the consequences are unimaginable, the CAM system must have full automatic anti-overcut processing capability, the traditional curved CAM system is the concept of local processing, it is very prone to overcutting, generally relying on people to choose to intervene It is difficult to ensure the safety of over-cut protection. The new generation CAM system should have full automatic over-cut protection function to ensure its safety.
☆ The tool path should be kept stable and avoid sudden acceleration or deceleration. It is better to use the oblique lower knife or the return arc lower knife in the transition between the lower knife or the line to avoid the vertical lower knife directly approaching the workpiece material. Connection, avoiding straight line support. Residual machining or root cleaning is an important means to improve machining efficiency. Generally, multiple machining or series of tools should be used to divide the machining from large to small, until the required size is chased, and the knife is avoided. One-time machining is completed. The tool path editing function is also important. It can be trimmed to reduce the empty knife and improve efficiency.
According to the above high-speed milling processing characteristics, Dongfeng Motor Co., Ltd. commercial vehicle forging factory is equipped with De lcam's 3D NC software for high-speed milling (the shape module is Power Shape processing module for PowerMiII), which has strong surface modeling function. The machining performance is very powerful, and it supports almost all the machining methods known at present. The tool path editing ability is its strongest place, and the tool path can be arbitrarily deleted without overcutting the workpiece. In particular, it can fully support high-speed milling. (HSM) machining provides a powerful tool for high-speed milling but for main programming.
High-speed milling programming technology
High-speed milling and forging is a brand-new technology. Only by fully grasping the corresponding programming technology can we give full play to the benefits. The following is an example of machining a connecting rod final forging die. Let us describe the high-speed milling program with PowerMill. Process and technical parameters used. The two sets of the mold were completed in just 3 hours.
l Roughing programming roughing adopts layer cutting plus offset method, using tool MICRO 100, its model is XCI010003-82 ( ¢ 10 R3 round end milling cutter), spindle rotation speed is 500OOr/m, feed rate is 2500mm/ Min, tolerance 0.05. Machining allowance. The radial direction is o 2 , the axial direction is 0.1, the lower cutting step is 0.35, the row spacing is 2.6, and the feeding mode is oblique selection. The following are some precautions in roughing (1) Forging by commercial vehicle of Dongfeng Motor Co., Ltd. The high-speed milling introduced by the factory has the function of reversing deceleration. When machining, the machining infeed is spiral, the machine will reduce the feed, affect the machining efficiency, adopt the oblique feed method and effectively control the length of the diagonal line, which can increase the feed. Speed, because it is an end mill, the feed angle should not be greater than 5. Otherwise, the impact on the tool is large and it is easy to hit the knife.
(2) The tool path connection parameters are very important, and the feeding is not good. The lifting knife is too large and high. Especially the roughing processing reasonable connection parameters can greatly reduce the unnecessary lifting of the knife and improve the processing efficiency. Body: The fast-forward height in the table is not absolute and the relative fast-forward is used. The cutting distance should be reduced as much as possible and the infeed height should be short when connecting obliquely. The connection should be chosen on the secluded surface. If you choose to pass, the safe altitude should be chosen to pass.
(3) According to the characteristics of high-speed milling of commercial vehicle forging factory of Dongfeng Motor Co., Ltd., the rounding and light arc connection functions in roughing should be removed, which can reduce the repeated cutting path and improve efficiency.
(4) The machining allowance is radially larger than the uranium direction, mainly considering that if the cutter breaks when the tool is taken, the radial direction is easier to tie the knife than the axial direction.
(5) It is necessary to use the rounded end milling cutter (bovine nose knife) for roughing. It can be both mirror plane and sharp side. It has extremely high linear velocity when rotating and has the highest cutting efficiency. Compared with his side blade, the flat bottom knife is not easy to collapse. Compared with a ball head knife, the line spacing can be several times larger and the processing efficiency is much higher.
(6) When processing retreading molds, it is necessary to define suitable blanks. Otherwise, due to uneven machining allowance, it is easy to cut the knife and increase the manufacturing cost. (7) The roughing method is easy to select once, and it is not easy to use the residual roughing method. Instead of high-level machining in semi-finishing, the machining speed can be increased by more than one time. It should be noted that the diameter of the latter tool is greater than or equal to 1/2 of the diameter of the previous tool, otherwise the residual amount will be left. Affect the cutting of a tool.
2. Semi-finishing and finishing programming (1) Semi-finishing adopts contour processing method. Using tool MICRO 100, its model is XC91010-5 (6-ball headed cutter), spindle rotation speed is 15000r/min, feed The rate is 3000mm/mln, the tolerance is 0.03, the machining allowance is 0.08, the lower cutting step is 0.2, and the feeding mode is vertical arc feeding.
(2) Finishing adopts the combination of contour machining and parallel machining, and sometimes the best contour method can be used. The tool FRAISA is U5283 (4-ball headed cutter), and the spindle rotation speed is 19500r/min. 0.01. Machining allowance 0, lower cutting step 0.1 infeed mode is vertical arc infeed.
(3) After root cleaning, the radius of the connecting rod rod is only 1.2mm. It is necessary to use the R1 tool for root cleaning. The method is to first find the boundary that the R2 tool can't work, and then use the three-dimensional offset to process the boundary. Surface, using the tool FRAISA, model M5782-140 (2-ball headed knife), other processing parameters are the same as finishing. Here are a few notes on semi-finishing and finishing:
(1) The vertical arc feed can reduce the length of the lower cutter path. At the same time, the lower cutting path and the cutting edge are connected to be tangent, which has less impact on the tool and can effectively protect the tool.
(2) The parameter selection during tool processing should be provided strictly according to the manufacturer's hungry data, so as to maximize the protection of the tool.
(3) The root can not be directly used by the clean root program provided by Powermill. Because the local machining allowance is too large, it is easy to use a knife. It is necessary to first find the residual boundary and enlarge it by 2mm, and then use the three-dimensional offset to process the outer lining. Not only the surface quality can be greatly improved, but also it is not easy to use a knife. The reason why the large knife is used for machining, the knives are used to finish the mold without the use of a knives, and the main reason is to improve the processing efficiency.
(4) In most cases, a combination of equal processing and parallel methods should be used. Because the optimal contour is automatically divided into two parts: steep and shoal (flat) by 30, the steep part is processed with high precision, and the shoal part is processed by three-dimensional offset. The joints after processing have joints and the quality of the edge is not high. . The combination of higher processing and parallel processing can control the boundary between the steep and the shoal to make a certain overlap, the continuous part after processing has no joints, the surface quality is high, and the parallel processing of the shoal surface is used. The marks and finish are better than the three-dimensional offset mode. When calculating the tool path, the parallel machining method is much faster than the three-dimensional offset mode. At the same time, in order to improve the processing efficiency, we can change the steep and shoal boundary angle to 20, which can reduce the certain cutting time.
(5) The toolholder collision inspection is very important. When the programming is completed, it must be checked to avoid damaging the machine tool spindle. At the same time, the minimum length of the tool during machining can be calculated, and the length of the tool can be clamped as much as possible.
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