Clamping of milling cutter
The milling cutters used in machining centers mostly adopt the spring clamp set clamping method, and are in a cantilever shape when in use. During the milling process, sometimes the milling cutter may gradually extend from the tool holder, so that it is complete? Lost, so that the workpiece is scrapped. The reason is generally due to the existence of the inner hole of the tool holder and the outer diameter of the milling tool holder Oil film, caused by insufficient clamping force. The milling cutters are usually coated with anti-rust oil. If a non-aqueous cutting oil is used for cutting, a mist of oil film will also be attached to the inner hole of the tool holder. When the oil film is stored on the handle and the tool holder, the tool holder is very It is difficult to firmly clamp the shank, and the milling cutter is loose and lost during processing. Therefore, before the milling cutter is clamped, the milling cutter shank and the inner hole of the cutter clamp should be cleaned with cleaning fluid, and then dried before clamping.
When the diameter of the milling cutter is large, even if the tool holder and the tool holder are very clean, a tool loss accident may occur. At this time, the tool holder with a flattening gap and the corresponding side locking method should be selected.
Another problem that may occur after the milling cutter is clamped is that the milling cutter is breaking at the port of the tool holder during processing. The reason is generally that the tool holder has been worn for a long time and the port portion of the tool holder has been worn into a tapered shape. Replace with a new tool holder.
Milling cutter vibration
Because there is a slight gap between the milling cutter and the tool holder, the cutter may vibrate during processing. Vibration will make the cutting edge of the milling cutter uneven in the amount of cutting, and the cutting expansion will increase than the original set value, affecting the machining accuracy and tool life. However, when the width of the groove processed is small, the tool can be purposely vibrated, and the required groove width can be obtained by increasing the cutting and expanding amount, but in this case, the maximum amplitude of the milling cutter should be below 0.02mm, otherwise Perform stable cutting. In normal machining, the smaller the vibration of the cutter, the better.
When tool vibration occurs, you should consider reducing the cutting speed and feed speed. If both have reduced by 40% and there is still a large vibration, you should consider reducing the amount of knife eating.
If resonance occurs during processing, the reason may be that the cutting speed is too high, the feed rate is just small, the tool is not enough, the clamping force of the workpiece is not enough, and the shape of the workpiece or the clamping method of the workpiece should be accepted. Measures such as adjusting the amount of cutting, adding the fragmentary rigidity of the tool, and increasing the feed speed.
End cutting of milling cutter
In the CNC milling process of the cavity of the mold and other workpieces, when the cut point is a concave part or a deep cavity, the extension of the milling cutter needs to be increased. If a long-edge milling cutter is used, due to the large deflection of the tool, it is easy to cause vibration and cause tool breakage. Therefore, in the machining process, if only the cutting edges with similar tool ends are required to participate in the cutting, it is best to choose a short-edge long-shank milling cutter with a longer total tool length. When using a large-diameter milling cutter to process a workpiece on a horizontal CNC machine tool, due to the large deformation caused by the weight of the tool, more attention should be paid to the title of superb end cutting. If you are using a long-edge milling cutter, you need to significantly reduce the cutting speed and feed speed.
Selection of cutting parameters
The choice of cutting speed mainly depends on the material of the workpiece to be processed; the choice of feed speed mainly depends on the material of the workpiece to be processed and the diameter of the milling cutter. The tool samples of some foreign tool manufacturers are accompanied by a table of tool cutting parameters for reference. However, the choice of cutting parameters is also affected by many factors such as machine tools, tool bits, the shape of the workpiece to be processed, and clamping methods. The cutting speed and feed speed should be adjusted according to the actual situation.
When the tool life is the priority factor, the cutting speed and feed speed can be appropriately reduced; when the chip removal from the edge is not good, the cutting speed can be increased appropriately.
Selection of cutting methods
Adopting down-milling is beneficial to defense blade cover and can improve tool life. But there are two points to focus on:
① If you accept ordinary machine tool processing, you should try to eliminate the gap of the feed mechanism;
② When the appearance of the workpiece is left with oxide film or other hardened layer composed of casting and forging process, it is advisable to adopt reverse milling.
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