Forging die high-speed milling and DELCAM programming technology
I. Introduction
Dongfeng Motor Co., Ltd. Commercial Vehicle Forging Factory is a large-scale specialized manufacturer of plated parts and die forgings. It has more than 40 pieces of die forging and forging units from 20MN to 120MN, with an annual output of 100,000 tons of forgings, and has With an annual output of more than 5,000 sets of various types of die forging die production workshop, CNC milling machine 3, Mikron a high-speed milling, there are a large number of electrical processing and machining equipment.
With the rapid development of modern economy, the market has put forward higher and higher requirements for the quality, price, and delivery time of new product forgings. As the key tool for the production of new product forgings, the forging die has become a key factor in the success or failure of new product development due to its quality, price and delivery time. The traditional forging die processing method has been difficult to meet the market demand. Dongfeng Motor Co., Ltd.'s commercial vehicle forging plant forging die manufacturing system has been under great pressure in recent years. The production workshop is basically equipped with holidays. Key equipment 3 classes Production, but it is still difficult for some new products to meet their quality and delivery requirements.
Forging die manufacturing urgently requires a high-quality, high-efficiency machining method to improve the quality of the die, shorten the manufacturing cycle, and reduce manufacturing costs. The advent of high-speed machining technology has solved some of the difficulties faced by forging die manufacturing. Therefore, high-speed machining technology has been rapidly developed in the forging die manufacturing industry. Dongfeng Motor Co., Ltd.'s commercial vehicle forging plant has introduced a Swiss Mkron high-speed machining center (VCP1000Duro) to achieve remarkable results in the machining of precision and complex forging dies such as crankshafts and rammings.
Second, the comparison of two processes
At present, Dongfeng Motor Co., Ltd.'s commercial vehicle forging plant forging die processing process is generally: forging die shape machining → circular milling or copy milling roughing groove → heat treatment → grinding ground plane → EDM or digital power Rough spark, finishing groove → fitter polished groove → surface hardening. This kind of processing method has low efficiency, low quality, and long production cycle.
High-speed milling forging die process is: forging die shape machining → heat treatment → grinding datum plane -. high-speed milling groove type → surface hardening treatment. It can be seen that high-speed machining plated forging die process eliminates the need for rough machining, EDM coarse. Finishing. Fitter grinding and other 4 processes.
High-speed milling can also save electrode materials, the wood used in the model, and the man-hours and costs of making electrodes and models.
In addition, during high-speed finishing, small radii can be machined with small-diameter milling cutters for fine manufacturing, saving a lot of rest, grinding, and polishing time.
Third, the characteristics of high-speed milling
l High efficiency
High-speed milling is a machining method that is different from traditional machining. Compared with high-speed cutting, it has a high feed rate for high-speed cutting and a small amount of cutting. However, the amount of material removed per unit of time is 3-6 times larger than that of ordinary cutting. , is 5-10 times that of electrical machining, and high-speed milling can simplify the processing process and shorten the mold manufacturing cycle. It can shorten the average manufacturing cycle of forging die by half or more.
2. High precision
Because of the high cutting speed, low cutting depth, high feed rate, stable operation, and low vibration, 95% or more of the cutting heat is taken away by the chips during high-speed cutting. Therefore, the workpiece deformation is small and high machining can be achieved. Accuracy and surface finish, high-speed milling can solve the problem that Dongfeng Motor Co., Ltd.'s commercial vehicle forging plant has no precision mold processing methods, and improve the quality of mold manufacturing.
3. Low manufacturing cost
Can save a lot of graphite, wood and a large number of electrode manufacturing and wood mold manufacturing hours, although high-speed milling consumes some tools, but with a consumption of fine series only graphite electrode 1/2.
Fourth, benefit analysis
Take a crankshaft forging die as an example. The current total process of the traditional forging die machining process is 22 tracks, and the total time is 256 hours, in which the groove processing time is 179 hours (copy milling 40 hours, EDM 94 hours, fitter polishing 45 hour). The total number of processes for high-speed milling crankshaft forging dies was 17 and the total time was 120 hours, of which the processing time was only 44 hours. Compared with the traditional forging die machining process, the total mastering time can be reduced by 1/2, the machining time of the groove can be shortened by 3/4, and the machining accuracy can also be improved. After inspection, the error is within 0.1 mm and the surface roughness is For Ra 0.4, the molds do not have to be polished or even polished by fitters. In addition, it can save a lot of graphite, wood, economic benefits are very significant.
Five high-speed milling strategy for CAM system requirements
High-speed machining has special processing requirements that are different from traditional machining. Therefore, the CAM system used in the high-speed CNC automatic programming system must be able to meet the corresponding special requirements.
(l) The CAM system should have a very high speed of calculation and programming. In high-speed machining, very small feeds and depths are used. 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 various machining process strategies in order to take the best process plan and to edit and optimize the tool path for optimum machining efficiency.
(2) The important feature of high-speed machining is that it is able to use smaller diameter tools to produce complex molds. The system can automatically prompt the shortest knife length and automatically perform tool interference check, which is very important for high-speed machining.
(3) The feedrate optimization processing function, in order to ensure the maximum cutting efficiency, and ensure the safety of the processing during high-speed cutting, the CAM system should automatically optimize the feedrate according to the size of the machining instantaneous margin. .
(4) Abundant machining strategies that meet the requirements of high-speed machining. Compared with the traditional methods, high-grade machining has special requirements for the cutting method of the machining process. Therefore, the CAM system is required to meet these specific process requirements.
☆A sudden change in the direction of the tool in the tool path should be avoided to avoid damage to the tool or equipment due to partial over-cutting.
☆Full automatic anti-over-cutting capability and automatic toolholder interference check, consultation processing is performed at cutting speeds up to 10 times higher than traditional machining. Once over-cutting occurs, the consequences are unbearable. CAM system must have full automatic anti-cutting processing The ability of the traditional curved CAM system to be a local processing concept is extremely prone to over-cutting. It is generally based on the way people are choosing to intervene. It is difficult to ensure the safety of over-cut protection. A new generation of CAM systems should be developed. With full automatic anti-cutting function, it can truly guarantee its safety.
☆ The tool trajectory should be kept steady to avoid abrupt acceleration or deceleration. It is better to use the oblique knife or arc back knife in the transition between the lower knife or the row to avoid the vertical knife directly approaching the workpiece material. Connecting, avoiding straight line aids. Residual or root removal processing is an important means to improve processing efficiency, generally should be used for multiple processing or use a series of tools from major to minor processing, until the pursuit of the required size, to avoid using a knife Once machining is completed, the tool path editing function is also very important, and trimming can be used to reduce the number of empty tools and improve efficiency.
According to the above characteristics of high-speed milling Dongfeng Motor Co., Ltd. commercial vehicle forging plant for high-speed milling specially equipped with De lcam's 3D NC software (styling module for the Power Shape processing module for PowerMiII), the software in addition to the surface modeling function is strong The processing performance is very strong, and it supports almost all the currently known machining methods. The tool path editing capability is its strongest place, and the tool path can be arbitrarily deleted without over-cutting the workpiece. In particular, it can fully support high-speed milling. (HSM) processing provides us with a powerful tool for high-speed milling and main programming.
Six. High-speed milling programming technology
High-speed milling forging lock is a brand new technology, only in a comprehensive grasp of the appropriate programming techniques, in order to give full play to their due benefits. The following is to process a connecting rod end forging die as an example, tell us about using PowerMill to compile high-speed milling program The process and the technical parameters used. This set of two molds was completed in only 3 hours.
l rough programming
Rough cutting adopts lamination and offset method, uses tool MICRO 100, its model is XCI010003-82( ¢ 10 R3 radius end mill), spindle rotation speed is 500OOr/m, feed rate is 2500mm/min, tolerance is 0.05 Processing allowance. Radial is o 2 , axial is 0.1, downcut is 0.35, spacing is 2.6, and the feed is oblique. The following are some precautions in roughing
(1) The high-speed milling machine imported from Dongfeng Motor Co., Ltd. for commercial vehicle forging factory has its own reversing deceleration function. When the programming feed is programmed, the machine tool feeds the tool in a spiral manner. The machine tool will decelerate the feed and influence the processing efficiency. It uses slash feed. Ways and effective control of the length of the slash 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, given bad, too much high lifting knife. In particular, rough connection reasonable connection parameters can greatly reduce the unnecessary lifting knife to improve processing efficiency. In terms of the body: the rapid traverse height in the table is not absolute and the relative fast forward is selected. The traverse distance should be minimized and the feed height should be selected when the incline feed is short. The connection should be selected on the obscure surface. The long link should be selected. Choose to pass through, safe altitude should choose to pass.
(3) According to the characteristics of high-speed milling of Dongfeng Motor Co., Ltd.'s commercial vehicle forging plant, the rounding and arc welding functions in rough machining should be removed, which can reduce the number of repetitive tool paths and improve efficiency.
(4) Machining allowance is larger than uranium in radial direction. It is mainly to take into account that when the knife is cut, if the tool is broken, the radial direction is easier to tie than the axial direction.
(5) The roughing must be done with a round-end end mill (nose-nosed knife), which can both mirror plane and sharp side, and it has extremely high linear velocity when rotating, and the cutting efficiency is the highest. Compared to his side edge, the peaceknife is not easy to collapse. Compared to a ball nose knife, the row spacing can be several times larger and the processing efficiency is much higher.
(6) When processing retreading dies, it is necessary to define suitable blanks. Otherwise, due to uneven machining allowances, it is easy to hit the knife and increase the manufacturing cost.
(7) The roughing method is easy to use only once, and it is not easy to use the residual roughing method and directly replace it with the advanced processing method in semi-finishing, which can increase the processing speed more than twice. It should be noted that the diameter of the last tool is greater than Or equal to 1/2 of the diameter of the previous tool, otherwise it will leave a residual amount, affecting the cutting of the next tool.
2. Semi-finishing and finishing programming
(1) The semi-finishing process adopts the contour processing method. The tool MICRO 100 is used, the model is XC91010-5 (6-ball headed knife), the number of spindle rotations is 15000r/min, the feed rate is 3000mm/mln, the tolerance is 0.03, processing The margin is 0.08, the lower cutting step is 0.2, and the feed method is vertical arc infeed.
(2) The combination of equal-height processing and parallel processing is used for the finish machining, and sometimes the best contour method can be used. The model FRAISA is U5283 (4-ball headed knife), the number of spindle revolutions is 19500 r/min, and the tolerance is 0.01. Machining allowance 0, down-cut 0.1 The infeed method is a vertical arc infeed.
(3) For clear root processing, the fillet radius of the connecting rod part is only 1.2mm. The R1 tool is used for root removal processing. The method is to first find the boundary that the R2 tool cannot process, and then use the three-dimensional offset processing boundary. Surfaces, using the tool FRAISA, model M5782-140 (2-ball headed knife), other processing parameters are the same as for finishing. The following are some notes on semi-finishing and finishing:
(1) Using a vertical arc infeed reduces the length of the lower cutter path. At the same time, the lower cutting tool and the cutting tool are tangentially connected when they are connected, which has less impact on the tool and can also effectively protect the tool.
(2) When selecting parameters for tool processing, hungry data should be strictly provided by the manufacturer so as to maximize the protection of the tool.
(3) Qing Gen cannot directly use the root removal procedures provided by Powermill. Because the local machining allowance is too large, it is easy to hit the knife. To find the residual boundary first, and to enlarge it by 2mm, and then use the three-dimensional offset to process outwards and inwards, not only the surface quality can be greatly improved, but also it is not easy to hit the knife. The reason why the use of large knives for processing, knives and roots to finish the mold, rather than a knife to complete the processing, mainly from the point of view can improve the processing efficiency.
(4) In most cases, the combination of contour processing and parallel methods should be adopted. Because the optimal height is 30, the surface is automatically divided into two parts, steep and shallow (flat), and steep parts are processed at a higher level. The shoal parts are offset by three-dimensional processing. After processing, the connecting part has joint marks, and the quality of the edges is not high. . With the combination of advanced machining and parallel machining, the borders of the steep and shallow sections can be controlled to have a certain degree of coincidence, the continuous part after processing is free of marks, the surface quality is high, and the surface of the shoal is used to process the knife. The marks and finishes are better than the three-dimensional offset method. When calculating the tool path, the parallel processing method is much faster than the three-dimensional offset method. At the same time, in order to increase the processing efficiency, we can change the steepness and shallows demarcation angle to 20, which can reduce the certain cutting time.
(5) The collision detection of the tool bar is very important. When the programming is completed, it must be checked to avoid hitting the machine tool spindle. At the same time, the shortest length of the tool during machining can be calculated, and the length of the tool during machining can be as much as possible.
Seven. Other measures to improve high-speed milling programming
In high-speed milling programming, there are many measures that can increase speed and reduce programming errors.
1. Create a user menu
Some functions that are not on the menu are inconvenient to use. You need to type a large number of English letters. This requires you to create a user menu for your convenience. The specific method: First in my computer → advanced → environment variables will be changed to HOME; c;\DelcamHome, then create a sub-directory Pm il1 2 and finally generate a User_menu file. The user menu can be generated after processing, for example, a tool library creation menu can be added, etc.
2. Generate a tool library
All the existing tools of the Dongfeng Motor Co., Ltd. commercial vehicle forging factory are input into the tool magazine. When the tool is used in the machining, it can be called directly in the tool magazine, which not only saves the creation of tool time, but also reduces errors. Specific methods: Right-click in the blank area of ​​the processing directory tree, pop up the user menu to select the tool library generation menu, enter the specifications and parameters of each tool,
3. Make a great life today
In the preparation of the processing program, many environmental variables, such as cutting out the connection, fast-forwarding height table, output machine type in the post-processing file, etc., each time through the manual surface, wasting a lot of time. We can determine A macro command automatically initializes the environment parameters. As long as the NC software is started, the environment variables needed by the user can be automatically added and saved. It can save a lot of time. It is worth noting that the macro command file should be named PmlocaLmac and be placed in the default state record of the software. The macro command can be executed automatically.
Eight conclusions
High-speed milling is a new technology newly developed in the mold manufacturing industry following CNC milling and precision CNC EDM. It features high efficiency, high precision, and low manufacturing cost, making mold manufacturing high-grade, fast, and easy. Reliable, high-speed milling is the only way for the development of forging die manufacturing, it will certainly bring a huge change to the mold manufacturing industry.
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