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Mould type of numerical control process computer assist the cutter choose and studyForewordNumerical control include cutter production and cutter of orbit choose two key problems process ,. The first problem has been got and studied extensivly and deeply over the past 20 years, a lot of algorithms developed have already got application in commercial CAD/ CAM system. Most CAM systems can produce the cutter orbit automatically after users input relevant parameters at present. Comparatively speaking , it is still not ripe to regard quality , efficiency as the research of choosing the problem of cutter of optimizing the goal correctly, do not have commercial CAM system that can offer the preferred decision support tool of cutter at present, therefore it is difficult to realize the integrating automatically and organically of CAD/ CAM. The cutter is chosen to usually include cutter type and cutter size. Generally speaking , suitable for one processing cutter of target for much kind , one cutter can finish different processing tasks, so it is easier to only consider meeting the cutter that basically processes the requirement and choose, especially to geometirc characteristics of model such as the hole , trough ,etc. But in fact, it is common for cutter to choose and sure optimization goal interrelate, for instance most heavy to cut efficiency , process time , minimum process cost , longest service life ,etc. at least, so the cutter is chosen it is a complicated optimization question. Such as mould type one of parts, because the geometirc form is complicated (usually include curved surface of freedom and island), influence geometry that cutter choose it restrains from to be can explicit to say among CAD model, need to design the corresponding algorithm to draw, therefore choose the cutter specification suitable and cutter association , it is not easy things by improving efficiency and quality processed in numerical control.Mould type generally with preparation method that numerical control mill, usually including rough machining, half finish machining , precise process of processing etc. The principle of rough machining is to spare no effort to remove the surplus metal with high efficiency, therefore hope to choose the larger cutter, but the cutter is oversized, may cause the increase of the crude volume ; Half finish machining of tasks to remove rough machining leave over step that get off mainly; Finish machining mainly guarantees size of the part and surface quality. Consider , go on , select exist , sure by computer difficult automatically totally up till now, therefore assist the cutter to choose in the computer that we developed (Computer Aided Tool Selection , CATS) among the system, base on , provide one aid decision tool for user, rough machining , half finish machining , precise to process etc., the real policy-making power is still left to users, in order to give full play to the advantages of computer and people.1 Basic structure of the system CATS system is CAD model, output for cutter type , cutter specification , mill depth of sharpening , enter the giving amount , rotational speed of main shaft (cut the pace ) and process six parameters such as time (such as Fig. 1), including choosing the aid decision tool in cutter type, rough machining cutter choose aid decision tool, half finish machining cutter choose aid decision tool and finish machining cutter choose aid decision tool ,etc.Given the rough machining in Xingqiang processing of the important position (usually rely time 510 times), rough machining, the system automatically optimize portfolio with cutlery functions to enhance overall processing efficiency. In addition to the decision-making tools, the system also has a detailed look cutlery norms, based on the type and size cutlery recommended processing parameters and assess the function of processing time, the last generation of the overall results of choice cutlery statements (figure 2). All the data and knowledge systems cutlery done by the background database support.2 Key technologies and algorithms2.1Cutlery type choiceAccording to Assistant Xingqiang digital processing practice, Xingqiang Xi state general processing cutlery into milling cutter, milling cutter radius milling cutter and the first three balls. D based cutlery diameter, radius radius r when r=0 for milling cutter, 0RCutlery can be divided into the overall style and embed films ceremony. For inlay film style, the key is to select the materials razor blades, razor blades materials choice depends on three elements : the processing of working materials, machine tools and cutlery jig stability of the state structures. Processing system will be translated into material steel, stainless steel, cast iron, nonferrous metals, materials and hard to cut materials six groups. Machine tool jig stability into good, better and less than three levels. Cutlery investigation into the short and long cantilever structures two, the system automatically reasoning on the basis of the specific circumstances of razor blades materials, decision-making knowledge from Walter cutlery manual system by the users first choice cutlery type in the world. To embed film style cutlery, a rules-based automated reasoning suitable razor blades materials. For example, if the final processing of materials for the steel, machine tool jig for good stability, cutlery cantilever structures for short, razor blades materials for WAP25.Rough machining cutlery portfolio optimizationXingqiang rough machining the aim is to maximize the removal of excess metal normally used milling cutter, take-cutting approach. Thus, 3D mould Xingqiang the rough machining process, is actually a series of 2.5D components Xingqiang processing. Cutlery optimization is to find a group of cutlery portfolio, allowing for maximum efficiency removal of most metals. Cutlery portfolio optimized basic methods as follows :A. To do some long step into knife in the direction of a group of vertical and horizontal search Xingqiang another entity to form a search layer.B. Derive closed to the contours.C. Calculated between Central and outside the island or islands and the distance between the key that affect cutlery choice geometric constraints algorithm flow As shown in figure 3D. According to the principle of the merger (adjacent to the critical distance will be smaller than the difference between the threshold) to search layer merger, graphic processing and identifying viable cutlery sets, a processing layer.E. Determine the use of each processing layer cutlery, cutlery Xingqiang processing portfolio. F. According cutlery recommended processing parameters (cutting speed, depth and into Xianxiao to speed), the calculation of material removal. G. According to the actual removal of the volume processing layer, the processing time for each processing layer. H. Xingqiang calculating the total processing time and residual volume.I. The overall portfolio of the Group cutlery processing efficiency assessment. J . Repeat ai until derive optimal mix of cutlery. If time is the goal, called for the entire processing time t Xingqiang shortest portfolio to optimize cutlery.2.2 Semi-finished cutlery choiceThe main purpose is to remove semi-finished rough machining residual contours of the new warrants. To completely remove height, depth must be greater than Xianxiao parts of each level to the surface distance x. Its algorithm steps are as follows :Step 1:entity models from parts of two adjacent to the cross section of the surface contours and the corresponding length;Step 2: The average length of contours;Step 3:calculate its width;Step 4 : calculating height floor to the surface of parts to the law distance x;Step 5 : steps 1 repeat steps 4, each level of decision Xianxiao depth;Step 6 : calculate cutlery diameter D, by or under cutlery experience D=x/0.6 manual recommended;steps7 : choose Xianxiao x depth than the smallest cutlery.2.3 fine cutlery choiceFine cutlery choice is the basic principle : cutlery parts surface radius smaller than the smallest size R curve radius r, the general admission R= (0.80.9) r. Its algorithm steps are as follows :Step 1 : from the smallest curve radius calculation model parts entities; Step 2 : From cutlery database search radius of less than a cutlery calculated radius of the curve all cutlery; Step 3 : select the best cutlery meet the above requirements; Step 4 : If all cutlery than the smallest curve radius, the smallest chosen as a recommended cutlery.3 summary and discussionMould type of craft of processing plan , need high technology and experience very usually, prepare NC time of data nearly and process time to be large. So person who produce of craft of processing plan and NC process demand of the order right away seem further more urgent automatically.This text system research mould type of craft cutter plan , choose problem, put forward mould of rough machining , half finish machining , finish machining principle and method that cutter chooses, the realization algorithm with corresponding structure , and has carried on the realization of preliminary programming under the environment of UG/OPEN API, have developed CATS prototype system. In cutter type and on the foundation that the specification is fixed, system also can recommend parameter of processing according to cutter manual (cut pace , mill , sharpen depth , enter person who give ,etc.), evaluate corresponding processing time. Final purpose its to realize integration of CAD/CAM really , produce through aftertreatment numerical control process the order.Need to point out , should improve the mould type totality of and process efficiency, need it from the rough machining , half finish machining , consideration on the whole of finish machining , make up and optimize many targets, this will be work that we want to carry on next .
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