Research On Toolpath Planning For Mould Cavity With Islands Machining

Die industry is one of the important basic industries in the national economy. Die CAM technology has played an important role in the die industry and it is a key technology of Mold Manufacturing. Tool path planning for Die Pocket Machining is an important part of die CAM technology.At present, there are many softwares used for the design of the die. The file format of these softwares for the mold designing is also different. In order to set up a neutral mechanism which does not rely on some specific system, the International Organization for Standardization (ISO) developed a set of standards, which is called the STEP standards. A convenient, brief, mature way to achieve the STEP standards is by the neutral document, the vast majority of the existing mold designing softwares can export STEP neutral document. So this paper uses the STEP neutral documents as an interface of the software of die design. Firstly paper introduces the concept of the STEP and shows how important the STEP neutral document is in the CAM technology, and then describes the detail of the format of the STEP neutral document. On the basis of this, the paper programs programs to deal with the STEP neutral document, which is the postpositive processor of the STEP.As the STEP neutral document is processed, the mold accessory is divided into several blocks. Then tool paths can be generated and planned on these blocks. In this moment, it is need to interpolate the cutting contact points into curves and some surface need to be re-generated. Next, this paper briefly presents the B-spline surfaces and its counting and anti-counting algorithm which will be used. In the GAGD(Computer Aided Geometric Design), it is one of the mainstream that the curves and surfaces are expressed by functions which have B-spline-based functions. The reason is that B-spline-based function has unified, common and effective standard algorithm, a strong supporting technologies. In addition, its counting and anti-counting algorithms are mature and stable.Tool path planning is the core of this paper. First it discusses the existing tool path planning methods, and compares the advantages and disadvantages of each method. After ascertaining a cutter and the way for tool path, it uses the revised method based on the same residue height to generate the tool path. Currently research on die pocket with convex hulls or pits or isolated islands is few. So this paper refers to some study for this type of mold, and raises concept of affecting area, finally realizes the high speed machining for the accessory with islands by rationally programming the tool path in the affecting area.The example shows that this method can finely bypass the island. The tool path is slippery, and it can also improve the efficiency.