Electric Control Cloth End Cutter Round knife cutting machine, Hand-held cloth cutting machine, Electric scissors Zhejiang Lejiang Machine Co., Ltd. , https://www.cnlejiang.com
Comprehensive Analysis of Tool Geometry Angle
In the study of tool geometry, one of the first things to understand is the basic angles. These include the orthogonal rake angle, the cutting plane inclination angle, the principal cutting edge angle, and the auxiliary cutting edge angle. Many students find it challenging to grasp these concepts during their initial learning phase. The main issue often lies in not fully understanding the concept of coordinate planes and measurement planes. Simply memorizing definitions without a clear visual or conceptual framework can lead to confusion.
To truly understand these angles, it's essential to recognize that the tool is placed within a specific measurement system. For example, the orthogonal plane measurement system includes the base plane, the cutting plane, and the orthogonal plane. Understanding each of these planes is crucial. The base plane, for instance, is defined as the plane perpendicular to the assumed direction of the main cutting motion at a selected point on the cutting edge. This means two key points must be clear:
1) The base plane is located at a selected point on the cutting edge.
2) It is perpendicular to the assumed main direction of motion.
The assumption here is that the workpiece is centered, and the main movement is downward. In this case, the base plane becomes a horizontal plane passing through the selected point on the cutting edge. The cutting plane is a vertical plane passing through the same point and is perpendicular to the base plane. The orthogonal plane, in turn, is a plane that is perpendicular to both the base and cutting planes. These three planes intersect in space and form the basis for measuring tool angles.
Once you understand the relationship between these planes, the basic angles become much clearer. For example, in the orthogonal plane, the angle between the rake face and the base plane is called the rake angle, while the angle between the flank face and the cutting plane is known as the relief angle. Therefore, mastering the auxiliary planes is a prerequisite for understanding the basic angles.
Next, we move to derived angles, such as the wedge angle and the cutting edge angle. The sum of the rake angle, relief angle, and wedge angle is always 90 degrees. As the rake and relief angles change, the wedge angle adjusts accordingly. Similarly, the sum of the principal cutting edge angle, the auxiliary cutting edge angle, and the nose angle equals 180 degrees. The nose angle changes based on the primary and secondary cutting edge angles. These relationships are important, but each angle also has its own function. For example, when turning threads, the accuracy of the tool angle directly affects the thread profile. Additionally, the size of the wedge angle influences the strength of the cutting edge.
Then there are conversion angles, which vary depending on the measurement plane used. The rake and relief angles can be measured in different planes, such as the orthogonal plane, normal plane, depth plane, and feed plane. Each of these planes provides a unique perspective on the tool’s geometry. For example, when turning an external surface, the relief angle is typically analyzed in the orthogonal plane, whereas for drilling, it’s examined in the end section. Understanding how these angles relate across different planes is essential, especially when working with complex tools like gears or threads.
Another important aspect is the difference between static (nominal) angles and working angles. While the nominal angles are fixed, the working angles change depending on the machining conditions. For instance, when turning an external surface, the working rake angle is the nominal rake angle plus the feed angle (μ), and the working relief angle is the nominal relief angle minus μ. This variation occurs because the actual cutting motion involves both the cutting speed and the feed movement, which alters the orientation of the base and cutting planes.
Finally, there are special features such as the transition edge, wiper edge, and negative rake chamfer. The transition edge is a short portion of the main cutting edge that helps reduce the load on the main blade and improve tool strength. The wiper edge, a type of secondary edge, is used to reduce surface roughness and improve finish quality. The negative rake chamfer is a small cut on the main edge that increases durability by providing additional support.
In summary, when selecting and using cutting tools, it's important to consider all the geometric angles together, rather than in isolation. A comprehensive understanding of how these angles interact and influence each other allows for better tool performance, improved efficiency, and higher-quality results. By analyzing tool geometry thoroughly, we can maximize the potential of each tool and meet the demands of modern manufacturing.