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The basic angles are: the rake angle in the orthogonal plane, the angle of inclination in the cutting plane, the main declination angle and the declination angle in the base plane. Many students feel difficult to grasp at the time of teaching. The key is to fail to pay attention to and appreciate the concept of coordinate plane and measurement plane. However, the definition of rote memorization is merely a mere memory on the surface.
In fact, it should first be clear that the tool is placed within a certain measurement system to determine the angle. For example, the orthogonal plane measurement system includes a base surface, a cutting plane, an orthogonal plane, and the like. For an understanding of a plane, for example, the base definition is: the selected point on the over-cutting edge is perpendicular to the plane of the presumed main direction of motion. There are two things you must understand when you understand:
1) The base surface is the selected point on the over-cutting edge;
2) perpendicular to the assumed main direction of motion.
The so-called assumption of the main direction of motion: It is assumed that the loading height is at the center of the workpiece. At this time, the direction of the main movement is vertically downward. The base defined at this time is a horizontal plane that passes through the selected point on the main blade. Similarly, the cutting plane is a vertical plane that passes through the selected point on the main blade and is perpendicular to the base surface. The orthogonal plane is a section that is perpendicular to the base plane and the cutting plane at the same time. The three auxiliary planes are two-by-two in space.
The orientation of the three auxiliary planes in the space and the mutual positional relationship must be clear. It is not difficult to understand the basic angle. For example, in the orthogonal plane: the angle between the rake face and the base face is the rake angle; the angle between the flank face and the cutting plane is the relief angle. Therefore, the prerequisite for learning the basic angle is to understand the auxiliary plane.
Second, derived perspective
Derivation angles are: knife angle, wedge angle. Because the sum of the rake angle, relief angle, and wedge angle equals 90°. The value of the wedge angle varies with the change of the rake angle and the relief angle, and because the sum of the main declination angle, the declination angle, and the tool nose angle is equal to 180 degrees. The value of the tool nose angle changes with the change of the primary and secondary declination angles. This is the correspondence between the angle values. However, whether the wedge angle or the corner angle has its own meaning and function. It is by no means optional. For example: when turning the thread, the accuracy of the tool angle directly affects the thread angle; as well as the tool angle, the size of the wedge has a great influence on the strength of the blade.
Third, the conversion angle
The rake angle or relief angle can be defined in different measuring planes. For example: In the orthogonal plane, normal plane, depth plane, feed plane has its corresponding rake and back angle.
The angles defined in the various measurement planes have their own meaning and function. This is because the machining characteristics of various tools are different and the angles need to be analyzed in different profiles. For example, when turning an outer circle, the size of the back angle of the turning tool is generally analyzed in the orthogonal plane. When drilling, the back angle of the twist drill needs to be analyzed in the end section.
The angle of the same name in each measurement plane has a certain degree of correlation with the value. Students must understand the similarities and differences. For example, the relationship between the orthogonal rake angle and the normal rake angle of the turning tool is as follows:
Γo = γn × cosλs ; When λs = 0°: γo = γn The forward angle of the method is the orthogonal rake angle.
On the other hand, when λs≠0°, γo≠γn affects the machining accuracy of the workpiece when gears and threads are machined.
Four working angles
The mark angle of the tool is a static angle and is uniquely determined. The dynamic angle, that is, the working angle, varies with different working conditions.
For example: When turning outside:
Working front angle = γ0 + μ
Working back angle = α0-μ
The change in μ value is now analyzed from the cutting motion alone.
Because the actual turning, there is a feed movement (especially when machining large pitch threads). At this time, the base plane and the cutting plane should be defined by the synthetic cutting motion. Become a working surface and work cutting plane. The working plane is defined as the plane through which the selected point of the cutting edge is perpendicular to the direction of the composite cutting speed. The definition of the working cutting plane is that the selected point through the cutting edge is tangent to the cutting edge and is perpendicular to the plane of the working base surface. The base and cutting planes are tilted by an angle of μ relative to the original angle.
In this way, when turning a large pitch thread, the cutting edge may not be able to cut into the workpiece due to a reduction in the angle of work.
V. Derivation angle
1, the transition edge declination
A short length of transition edge is ground on the main blade. That is, the double blade of the transition blade and the main blade is formed. The main blade becomes a fold line-like transitional blade for part of the cutting task. The declination angle of the transitional edge is generally half of the primary declination angle. The purpose is to reduce the burden on the main blade while increasing the strength of the cutting part of the cutter head. Therefore, the cutting amount can be increased and the durability of the tool can be increased.
2, repair knife declination
Between the primary and secondary blades, the wiper can also be worn. In fact, the wiper is the extreme form of the secondary blade. The function of the wiper is similar to that of the secondary blade, but because the wiper angle is generally 0°~3° and the length is 2 times the amount of the knife. Therefore, it can greatly reduce the roughness of the processing surface and improve the processing quality.
3, negative chamfer rake
Sharpen the negative chamfer on the main blade. The chamfer angle is generally -15° to -20°. The chamfer is on the main blade, but in the opposite direction of the rake angle and is of negative rake angle. The purpose is to increase the strength of the main blade and increase the durability of the tool. Should be considered together with the front corner.
When selecting and using tools, the geometrical angle of the tool does not analyze an angle in isolation. Instead, it needs to comprehensively consider the complementary and constraint relations of the relevant angles. Therefore, we need to make a comprehensive analysis of the tool geometry angle in order to maximize the potential of the tool. To achieve high-quality, high-yield, low-consumption production requirements.
Comprehensive Analysis of Tool Geometry Angle
First, understand the basic angle