Let’s take a look at the knowledge points that we need to know about the cutting edge inclination in CNC machining. What needs to be paid attention to in cutting machining with respect to the inclination of the cutting edge.
1. Control the direction of chip flow. When λs=0°[see Figure 7-14 (a)], the cutting edge of the tool is perpendicular to the composite movement direction, which is also called right-angle cutting. Chips flow out on the rake face similar to the normal direction of the cutting edge; suitable for chip breaking of brittle materials. It is necessary to prevent the chips from wrapping around the tool or tool holder near the cutting area, which will affect the normal progress of subsequent cutting.
When λs≠0°, that is, the cutting edge of the tool is not perpendicular to the direction of the combined cutting motion, it is also called bevel cutting; it is suitable for continuous discharge of chips in a spring shape when cutting tough materials.
When λs is a negative value, see Figure [7-14(b), the chips flow to the machined surface, and even scratch the machined surface, but the strength of the cutter head is better, and it is often used for rough machining.
When λs is a positive value, see Figure [7-14 (c)], the chips flow to the surface to be machined, but the strength of the cutter head is poor, which is suitable for finishing.
2. Affect the strength and impact resistance of the tool tip. As shown in Figure 7-15, when λs is negative, the tool tip is the lowest point on the cutting edge. When the cutting edge cuts the workpiece, the first contact point with the workpiece leaves the tip and falls on or in front of the cutting edge, which not only protects the tip from impact, but also enhances the strength of the tip. When λs=0° or a positive value, the tool tip may first contact the workpiece and be impacted. Therefore, many large rake angle tools are often used with negative edge inclination.
3. Negative blade inclination can protect the tip of the knife. As shown in Figure 7-16, the negative edge angle cuts the workpiece with the discontinuous surface. Figure 7-16 (a) shows the situation of turning the workpiece when λs is zero. The tool is lost and the cutting edge touches the workpiece at the same time, and the tool tip is not protected. Figure 7-16 (b) shows that when λs is a positive value, the fragile tool tip is first impacted by the workpiece, and it is easily broken and loses cutting ability, let alone the protection of the tool tip. Figure 7-16 (c) shows the situation of turning the workpiece when λs is a negative value. The tool nose is the lowest point on the main cutting edge. When cutting the discontinuous surface, the first contact with the workpiece is the point on the cutting edge far away from the cutting edge. , And it is a part with better strength. Unlike the positive edge angle tool, the first contact is the tip of the tool, which prevents the tip of the tool from being damaged by the first blow of the impact force. This is the negative edge angle in turning. The important role played by a special surface.
The negative edge inclination can make the cutting process smooth. When turning intermittent surfaces, the negative edge inclination can not only protect the tool tip, but also make the cutting process smooth. When turning with a turning tool with zero edge inclination, the entire cutting edge cuts the workpiece at the same time and cuts out the workpiece at the same time. When cutting in, the cutting edge of the tool receives the maximum impact force at the same time, and the impact force disappears quickly when cutting out, so that the tool When cutting in and cutting out, it will receive the greatest impact, which can easily cause vibration and make the cutting process unstable.
When using a negative edge angle turning tool to cut intermittent surfaces, the blade gradually cuts the workpiece, and then gradually cuts the workpiece, so that the cutting force on the tool gradually increases, after reaching the maximum, it gradually decreases, and finally disappears to zero, so that the cutting The process proceeded smoothly and without vibration.
4. Other influences. The size of λs affects the length of the cutting edge to participate in the work and the smoothness of cutting, changes the direction of the main cutting force, and affects the sharpness of the cutting edge.