I. tool path planning
1. Die thickness: under the large load that the machine tool can bear, large cutter, large feed and fast feed should be selected. In the case of the same tool, the feed is inversely proportional to the feed. Under normal circumstances, the load of the machine tool is not a problem. The principle of tool selection is mainly based on whether the two-dimensional angle and three-dimensional arc of the product are too small. After selecting a knife, determine the length of the knife. The principle is that the tool length is greater than the machining depth. For large workpieces, the interference of chuck shall be considered.
2. Mold smooth knife: the purpose of the smooth knife is to meet the processing requirements of the workpiece surface finish, and to leave appropriate margin. Similarly, smooth knives should be as large as possible, and the time should be as fast as possible, because fine knives take longer, and appropriate feeds and feeds should be used. In the same feed, the greater the cross feed, the faster the speed. The feed rate of curved surface is related to the finish after machining. The feed size is related to the surface shape of the surface. Keep small allowance, large tool, fast speed and proper feed without damaging the surface.
2、 Mold closing method:
1. Vise clamping: the clamping height shall not be less than 10 mm, and the clamping height and processing height must be specified when processing workpieces. The machining height should be about 5mm higher than the plane of the vise to ensure the firmness without damaging the vise. This kind of clamping belongs to general clamping. The clamping height is also related to the size of the workpiece. The larger the workpiece, the higher the clamping height.
2. Splint clamping: the splint is coded on the workbench, and the workpiece is locked on the splint with screws. This kind of clamping method is suitable for the workpieces with insufficient clamping height and large machining force, and generally suitable for the large and medium workpieces with good effect.
3. Code iron clamping: when the workpiece is large, the clamping height is not enough, and it is not allowed to lock the screw at the bottom, the code iron clamping shall be used. This kind of clamping requires secondary clamping, first code four corners, process other parts, then code four corners, process four corners. During the second clamping, do not let the workpiece loose, first code and then loosen. You can also code two sides first and process the other two sides.
4. Clamping of cutter: the diameter is more than 10 mm, and the clamping length is not less than 30 mm; the diameter is less than 10 mm, and the clamping length is not less than 20 mm. The clamping of the cutter shall be firm, and it shall be strictly prevented from hitting the cutter and directly inserting the workpiece.
3、 Selection of processing technology:
1. Surface trenching: range selection and face selection
Tool path processing area: the selected surface within the selected range is the termination surface, and all places that the tool can go down from the high point to the low point are the principle. The selected face shall be full face as far as possible, and the boundary shall only be the area to be processed. No face extends less than half of the cutter diameter, because other faces have enough margin, so it is automatically protected; extend as far as possible, because there is less than one R gong at the lower limit.、
Selection of cutter: if the cutter can't enter the helix or oblique line, or the machining area can't enter the cutter, the area shall be sealed and left for the second opening.
Before the smooth knife, it is necessary to make all the areas that have not been cut thick, especially small angles, including two-dimensional angle, three-dimensional angle and sealed area, or the knife will be broken. Secondary roughening: it is generally used to select the range of three-dimensional trenching, flat bottomed cutter, and the one that can use plane trenching and profile cutter path. Without damaging other surfaces, the center of the tool is to the selected height. When the groove shape is strip shape, and it is impossible to screw down the tool, the oblique line is used to feed the tool. Generally, the filter is opened, especially when the curved surface is rough, and the feed plane cannot be low, so as to avoid hitting the tool, and the safety height cannot be low.
Back off: generally, relative back off is not used. Absolute back off is used. If there is no island, relative back off is used.
2. Plane slotting: milling all kinds of plane, concave and flat groove. When milling part of the open plane, it is necessary to determine the boundary. In principle, it can feed (more than one knife diameter), the opening part is more than half of the knife diameter, and the periphery is closed.
3. Profile: when the selected plane is suitable for profile layering, the profile layering tool lifting (plane profile) is used. When the tool lifting point and the lower tool point are one point, the z-plane tool lifting is not necessary, and the relative height is not needed as much as possible; the direction of correction is generally right correction (along the tool).
4. Setting of tool path for mechanical correction: the correction number is 21, and the computer correction is changed to mechanical correction. The feed is vertical feed, and the area where the knife cannot pass is increased by R without margin.
5. Contour of equal height: it is suitable for the closed face. If the open face is four circles, it is required to seal the item face. If it is within four circles or not, it is required to select the range and height (certain arc feed is required to be rough). It is used for the case of rough cutting: the processing distance in any plane is less than one cutter diameter, if it is larger than one cutter diameter, it is required to use a larger cutter or two contour of equal height.
6. Curved streamline: with good uniformity and dry brittleness, it is suitable for smooth knife to replace contour in many cases.
7. Radial knife path: suitable for the case with large hole in the middle (less use). Note: the spring knife is not sharp, and the knife is too long. When the workpiece is too deep, it should not go up or down around; the surfaces on both sides of the sharp angle in the workpiece should be divided into two knife paths, which should not go over, and the edge of the smooth knife should be extended (use arc to advance or retreat the knife).