Novel tool cutting edge characterization method

Abstract

The invention provides a novel tool cutting edge characterization method, and relates to the field of tool modeling characterization. Comprising the step of accurately obtaining the position of a separation point through program calculation based on an ALE grid method. And the upper and lower optimal fitting circles are transformed, so that the positions of the separation points of the two different positions are obtained. According to the method, more meticulous parameterization expression can be carried out on the tool through the transformation of the positions of the separation points, the structure and cutting edge characteristics of the tool are represented more visually and conveniently, and the position of a tool nose of the tool is strengthened in the reverse modeling process of the tool. The method can solve the problem of insufficient characterization of tool morphology and cutting edge characteristics in an existing method, and improves the modeling efficiency and accuracy of the tool.

Description

Technical field:

[0001] The invention relates to the mesoscopic geometrical characteristics of a tool edge, and in particular to a method for characterizing the morphology of a tool edge and a method for modeling a tool edge. Technical background:

[0002] Cutting is one of the important processes in the manufacturing industry and is widely used in the processing of various materials. As a key tool in cutting, the cutting edge morphology of the tool directly affects the processing quality and efficiency. Therefore, accurate characterization of the cutting edge morphology of the tool is an important prerequisite for improving the level of cutting.

[0003] During the cutting process, the tool edge will be affected by factors such as material friction, impact and heat, resulting in edge wear and failure. By characterizing the tool edge morphology, the wear of the tool can be understood in time, so that corresponding measures can be taken to reduce tool wear and failure and increase tool life.

[0004] With the continuous development of cutting theory and technology, the requirements for tool edge morphology are getting higher and higher. The traditional tool edge morphology characterization method can no longer meet the needs of modern cutting processing. Therefore, it is necessary to study new tool edge morphology characterization methods to adapt to the development of cutting theory and technology. Summary of the invention:

[0005] The present invention provides a method for characterizing the cutting edge morphology of a tool, which can solve the technical problem of inaccurate and incomplete expression of the cutting edge morphology in the existing methods.

[0006] The present invention provides a method for characterizing the cutting edge morphology of a tool, the method comprising:

[0007] The three-dimensional contour of the tool is extracted using the edge contour recognition instrument to obtain the three-dimensional model of the tool. The cutting edges of different segments of the three-dimensional model of the tool are extracted using software to obtain the two-dimensional cross-sectional graphics of each segmented tool. The perspective is transformed by rotating and translating the two-dimensional cross-section of the tool to correct it and eliminate the influence of the helix angle.

[0008] The two-dimensional cross-sectional image of the tool is projected onto the plane coordinate system to obtain a two-dimensional point cloud image of the tool cross-sectional profile, and then the optimal contour of the cutting edge is obtained through fitting algorithm.

[0009] From the obtained two-dimensional tool model, a material to be processed is selected for milling simulation and a milling finite element model is established. In the milling simulation, the ALE meshing technology is used to calculate the relative sliding speed of the material to be processed by the program, and the position with the largest velocity vector difference on the tool surface is marked as the actual separation point S of the tool. At this time, the distance between the separation point S and the coordinate origin P is r'.

[0010] The vertical distance h from the separation point S to the back tool surface is the first parameter, which is expressed as the thickness of the plowing zone, and the actual plowing zone thickness is h*cos(α), where α is the back angle of the tool.

[0011] Draw a best-fit circle for the arc from the separation point S upward to the front cutting edge position, which is tangent to the front cutting edge of the tool. Note that the radius of the best-fit circle is R1 and the center position is O1'.

[0012] Make a best-fit circle tangent to the tool back face for the arc from the separation point S downward to the back face position, and record the radius of the best-fit circle as R2 and the center position as O2'. R1 and R2 are the second and third parameters of the tool edge characterization, which will directly affect the shear effect and plowing effect of the tool during milling.

[0013] It is known that the separation point S is a point at a distance h from the back cutting edge. In order to describe the sharpness of the cutting edge, the position of the separation point is transformed, and the separation point can move on a parallel straight line at a distance h from the back cutting edge.

[0014] Due to the uncertainty of the positions of the upper and lower best fitting circles, constraints are added to the upper and lower arcs so that they are tangent to each other while the radii R1 and R2 remain unchanged. When the two arcs are at the tangent position, the centers O1 and O2 of the upper and lower arcs are recorded.

[0015] r represents the distance from the separation point S to the coordinate origin P after transformation, and Δr is the difference between r and r'. This parameter can affect the sharpness of the tool edge, or be used to strengthen the separation point position S during reverse modeling. Δr is the fourth parameter representing the edge morphology.

[0016] Milling experiments were conducted under specific working conditions and analyzed to study the influence of the cutting edge shape on the machined surface. The changes of cutting edge shape parameters and the surface roughness of titanium alloy workpieces with machining time are shown in Figure 2. Figure 3 shown.

[0018] It can be observed that the change in the shape of the tool edge presents clear two-stage characteristics. In the initial stage of machining, due to the characteristics of the initial shape of the edge, the wear distribution at the edge is uneven, and this uneven wear causes the shape of the edge to change dramatically. This drastic change directly affects the stability of the machining process, which in turn causes the surface roughness of the machined workpiece to drop significantly in a short period of time. However, as the machining process continues, when the edge wears to a certain extent, the edge shape parameters gradually converge to a certain threshold. This shows that the tool wear has entered a relatively stable stage. At this stage, although the wear continues, the change in the edge shape tends to be gentle, and the surface roughness of the machined workpiece gradually stabilizes at Ra3.6μm.

[0019] By studying the influence of the interaction of the cutting edge shape on the machined surface, when h is equal to 3.5μm, the machined surface roughness first decreases and then increases with the increase of Δr and R2, reaching the minimum value in the middle range, and the machined surface roughness also reaches the maximum value when both reach the maximum value. When Δr is 6μm, the machined surface roughness first decreases and then increases with the increase of h. When h is small, the machined surface roughness first decreases and then increases with the increase of R2. When h is large, the machined surface roughness increases with the increase of R2.

[0020] When R2 is 6.5 μm, the roughness of the machined surface increases with the increase of h and Δr.

[0021] Compared with the prior art, this method brings the following technical effects:

[0023] A method for characterizing the cutting edge morphology of a tool of the present invention accurately locates the position of the separation point by forward solving the position of the separation point. After determining the radius and center position of the upper and lower best fitting circles, the sharpness of the cutting edge of the tool is characterized by the transformation of the position of the separation point. This method can more accurately characterize the cutting edge morphology of the tool with four simple parameters and accurately parametrically express the sharpness of the tool. It can also be used in the reverse modeling process of the tool, improving the efficiency and accuracy of the tool modeling. Description of the drawings:

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0025] Figure 1 Schematic diagram of a new cutting edge characterization method considering working conditions

[0026] Figure 2 This is a flow chart of the method for characterizing the cutting edge morphology of a tool in the present invention. Figure 3 This is the curve of surface roughness changing with processing time. Figure 4 The interaction diagram of cutting edge parameters on machined surface roughness Specific implementation method:

[0028] The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0029] The three-dimensional model of the cutting edge of a certain cutting tool is identified by a cutting edge identification instrument, and the two-dimensional morphology of the cutting tool is extracted by a three-dimensional modeling software. The two-dimensional morphology of the cutting tool can be used as the cutting edge morphology map of the cutting tool. R1, R2, h and Δr are used to characterize the obtained cutting edge morphology of the cutting tool.

[0030] The first step is to identify S as the distance from the separation point to the back face. The identification method is based on the ALE meshing method. The program calculates and accurately identifies the relative maximum sliding speed point of the material when the material is processed at the cutting edge of the tool. The maximum sliding speed point is the separation point, and its distance from the back face is the parameter h.

[0031] The second step is to determine the radii of the upper and lower fitting circles. The arc contours from the separation point to the front and rear tool faces are fitted using the fitting point fitting method. The two cutting edge morphology parameters obtained by fitting are the radii R1 and R2 of the fitting circles.

[0032] The third step is to strengthen the position of the tool separation point. The positions of the upper and lower fitting circles in the second step are transformed so that the position of the intersection point is changed while the distance between the intersection point S and the back tool surface remains unchanged until the two fitting circles are tangent. The difference in distance from the separation point to the origin of the coordinate system before and after strengthening is Δr.

[0033] The four parameters obtained can be used to parametrically characterize the morphology of the current tool edge. In the process of tool modeling, these four parameters can also be used to reverse model the tool morphology.

Claims

1. A new cutting edge characterization method, characterized in that: The coordinate system x and y axes are established. The angle between the front cutting face of the tool and the y axis of the coordinate system is γ, and the angle between the back cutting face of the tool and the x axis of the coordinate system is α. The intersection point P of the front and rear cutting faces of the tool is the coordinate origin. ALE meshing technology is used in milling simulation. The relative sliding speed of the material being processed is calculated by the program. The position with the largest velocity vector difference on the tool surface is marked as the actual separation point S of the tool. The vertical distance h from the separation point S to the back cutting face is the first parameter. The best fitting circle is made tangent to the front and back cutting faces of the tool for the arc from the separation point S upward and downward to the front and back cutting faces. The radius of the upper and lower best fitting circles is recorded as R1 and R2, and the center position is O1' and O2'. The position of the separation point is transformed so that the separation point can move on a parallel straight line at a distance h from the back cutting face. At the tangent position of the upper and lower best fitting circles, the two arcs are recorded at the tangent position as the center of the upper and lower arcs O1 and O2. r represents the distance from the separation point S to the coordinate origin P after transformation, and Δr is the difference between r and r'. This parameter can affect the sharpness of the tool edge, or be used to strengthen the separation point position S during reverse modeling. Δr is the fourth parameter representing the edge morphology.

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