1. File structure analysis Although the shapes of files are square, triangular and cylindrical, their main processing surface shapes are the same. In the length direction, various files have a certain arc and taper. Most people often ignore this point. They think that as long as the file is flat and the hand moves horizontally, the workpiece can be filed to meet the requirements. In fact, this is a misunderstanding.
Through the shape of the file, we can see that on the entire processing surface, the file has a horizontal plane on the shank, and there is an obvious curved arc at two-thirds. Observe the working surface of the file perpendicular to the horizontal plane. , You will find that the surface of the file is not straight. Theoretically speaking, even if your hands are moving horizontally, the movement of the knife surface of the file is not straight, and its movement trajectory is changing.
We know that the machining allowance of filing is generally not large, and manual filing mainly relies on physical strength as power, and this power is not constant, but changes with time and human physical strength. This is not good for filing work. .
2. Correct filing method Keep the horizontal movement as much as possible during filing. When pushing the rake face of the file forward on the workpiece, use a little force with the left hand and keep the balance with the right hand; to the back section, use the right hand while keeping the balance with the left hand. Then judge the effect of filing by observing the filing lines. For example, cross filing is used. From the view of the combination of textures, you can clearly know the processing conditions of the filing plane, which is convenient for adjusting the direction of the filing force and maintaining the processing surface. Consistency; Do the measurement at the same time, and make a record after each measurement, so that you can refer to the control and guide the processing.
If it is found that the texture of the file is uneven, or there is a size and shape error in the measurement, this phenomenon is mostly convex and collapsed corners in the processing surface, and the entire processing surface appears commonly known as "loach back". This is caused by incorrect techniques. Unsteady force with filing, or just failing to understand the shape and performance of the file. At this time, to eliminate the convexity and avoid the convexity of the file, the arc surface of the file mentioned earlier must be used.
Use the arc on the file to face the plane for processing. It is necessary to consciously and purposefully file and eliminate the convex surface of the processed part. At the same time, make multiple measurements and compare with squares, feelers, etc., until a qualified product is filed. Use the arc surface to be careful not to process the workpiece into a concave shape. At the same time, this method can be extended to the processing of round holes, square holes and keyways.
3. The selection of the thickness of the file and the selection of the reserved processing amount is also a more delicate issue, which is mainly determined according to the requirements of the workpiece on the surface roughness and accuracy. The general principles are: coarse grains for rough machining, medium and fine grains for semi-finish machining, and fine grains and gloss files for finishing.
