Method and device for determining stable cutting parameters for precise mold milling

Abstract

The invention discloses a stable cutting parameter determination method and device for precise mold milling, and relates to the technical field of milling machines.The method comprises the steps that an unequal-pitch end mill is divided into a limited number of cutting infinitesimals in the axial direction; calculating the instantaneous cutting thickness of each cutting infinitesimal; based on the instantaneous cutting thickness of each cutting infinitesimal, the dynamic cutting force of the unequal-pitch end mill is calculated; the dynamic cutting force comprises side edge cutting force and bottom edge cutting force; based on the dynamic cutting force, establishing a dynamic control equation of a milling system of the end mill with unequal tooth pitches; solving the dynamic control equation of the unequal pitch end mill milling system by adopting a time domain improved semi-discrete method to obtain a milling stability limit diagram; and determining stable cutting parameters based on the milling stability limit diagram. According to the method, the influence of the cutting force of the end mill bottom edge is considered, and the stable cutting parameters capable of improving the machining precision and the machining efficiency can be obtained according to the solved milling stability limit diagram.

Description

Technical Field

[0001] The present application relates to the technical field of milling, and in particular, to a method and device for determining stable cutting parameters for precision die milling. Background Art

[0002] The die manufacturing industry is an important part of modern industry. In fields such as automobiles, ships, aerospace, and medical treatment, a large number of precision components need to be manufactured through dies, so higher requirements are put forward for the machining accuracy of dies. Milling is the main process for die machining. However, the regenerative chatter that easily occurs during milling has become a major problem restricting the machining accuracy and efficiency of dies. In addition, problems such as the reduction of tool life caused by chatter and the impact on the life and health of workers cannot be ignored. Solving the milling chatter problem is a challenge faced by every die factory.

[0003] Since the end of the 20th century, systematic methods for predicting milling stability limits have been formed, but there is still much room for improvement in prediction accuracy. Existing methods for predicting milling stability limits usually select relatively simplified cutting force models and ignore the influence of the cutting of the bottom edge of the tool during the actual milling process. This simplification is unacceptable in die milling with high machining accuracy requirements, especially when the radial immersion rate is large, the influence of the bottom edge cutting is more obvious. Therefore, there is an urgent need for a method for determining stable cutting parameters considering the bottom edge cutting to provide a reliable theoretical basis for the selection of stable cutting parameters for precision die milling. Summary of the Invention

[0004] The purpose of the present application is to provide a method and device for determining stable cutting parameters for precision die milling, which consider the influence of the cutting force of the bottom edge of the end mill. According to the solved milling stability limit diagram, stable cutting parameters that can improve machining accuracy and efficiency can be obtained.

[0005] To achieve the above object, the present application provides the following solutions:

[0006] In a first aspect, the present application provides a method for determining stable cutting parameters for precision die milling, and the method for determining stable cutting parameters for precision die milling includes:

[0007] Divide the unequal pitch end mill axially into a finite number of cutting micro-elements.

[0008] Calculate the instantaneous cutting thickness of each cutting micro-element.

[0009] Based on the instantaneous cutting thickness of each cutting micro-element, calculate the dynamic cutting force of the unequal pitch end mill; the dynamic cutting force includes: side edge cutting force and bottom edge cutting force.

[0010] Based on the dynamic cutting force, establish the dynamic control equation of the milling system for the variable pitch end mill.

[0011] Solve the dynamic control equation of the milling system for the variable pitch end mill by using the improved semi-discrete method in the time domain to obtain the milling stability limit diagram.

[0012] Determine the stable cutting parameters based on the milling stability limit diagram.

[0013] In a second aspect, the present application provides a device for determining stable cutting parameters for precision die milling. The device for determining stable cutting parameters for precision die milling includes:

[0014] A dividing unit for axially dividing the variable pitch end mill into a finite number of cutting micro-elements.

[0015] An instantaneous cutting thickness calculation unit for calculating the instantaneous cutting thickness of each cutting micro-element.

[0016] A dynamic cutting force calculation unit for calculating the dynamic cutting force of the variable pitch end mill based on the instantaneous cutting thickness of each cutting micro-element; the dynamic cutting force includes: side cutting edge force and bottom cutting edge force.

[0017] A dynamic control equation establishment unit for establishing the dynamic control equation of the milling system for the variable pitch end mill based on the dynamic cutting force.

[0018] A solving unit for solving the dynamic control equation of the milling system for the variable pitch end mill by using the improved semi-discrete method in the time domain to obtain the milling stability limit diagram.

[0019] A stable cutting parameter determination unit for determining stable cutting parameters based on the milling stability limit diagram.

[0020] In a third aspect, the present application provides a computer device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor, where the processor executes the computer program to implement the method for determining stable cutting parameters for precision die milling described in any one of the above.

[0021] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, it implements the method for determining stable cutting parameters for precision die milling described in any one of the above.

[0022] In a fifth aspect, the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the method for determining stable cutting parameters for precision die milling described in any one of the above.

[0023] According to the specific embodiments provided by the present application, the following technical effects are disclosed in the present application:

[0024] The present application provides a method and device for determining stable cutting parameters for precision die milling. The method includes: dividing an unequal pitch end mill axially into a finite number of cutting micro-elements; calculating the instantaneous cutting thickness of each cutting micro-element; calculating the dynamic cutting force of the unequal pitch end mill based on the instantaneous cutting thickness of each cutting micro-element; the dynamic cutting force includes: side cutting force and bottom cutting force; establishing a dynamic control equation for the unequal pitch end mill milling system based on the dynamic cutting force; solving the dynamic control equation for the unequal pitch end mill milling system by using the time-domain improved semi-discrete method to obtain a milling stability limit diagram; and determining stable cutting parameters based on the milling stability limit diagram. Compared with the prior art, the present application incorporates the contribution of the bottom cutting force of the unequal pitch end mill into the model consideration range, improves the prediction accuracy of the milling stability limit, and based on this, stable cutting parameters with higher machining accuracy and machining efficiency can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 It is an application environment diagram of a method for determining stable cutting parameters for precision die milling in an embodiment of the present application.

[0027] Figure 2 It is a schematic flow diagram of a method for determining stable cutting parameters for precision die milling provided in an embodiment of the present application.

[0028] Figure 3 It is a schematic diagram of the axial micro-element division of an end mill provided in an embodiment of the present application.

[0029] Figure 4 It is a schematic diagram of the geometric structure and angular relationship of an end mill provided in an embodiment of the present application.

[0030] Figure 5 It is a schematic diagram of the side cutting force and bottom cutting force of an end mill provided in an embodiment of the present application.

[0031] Figure 6 It is a schematic diagram of a milling dynamics model provided in an embodiment of the present application.

[0032] Figure 7The milling stability limit diagram considering bottom-edge cutting provided by an embodiment of the present application.

[0033] Figure 8 The schematic diagram of the functional modules of a stable cutting parameter determination device for precision die milling provided by an embodiment of the present application.

[0034] Figure 9 The schematic structural diagram of a computer device provided by an embodiment of the present application. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. 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 of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0036] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners.

[0037] The stable cutting parameter determination method for precision die milling provided by the embodiments of the present application can be applied to, for example Figure 1In the application environment shown. Among them, the terminal 102 communicates with the server 104 through the network. The data storage system can store the data that the server 104 needs to process. The data storage system can be set separately, integrated on the server 104, placed on the cloud or other servers. The terminal 102 can send the unequal pitch end mill model to the server 104. After the server 104 receives the unequal pitch end mill model, for the unequal pitch end mill model, the server 104 divides the unequal pitch end mill along the axial direction into a finite number of cutting micro-elements; calculates the instantaneous cutting thickness of each cutting micro-element; based on the instantaneous cutting thickness of each cutting micro-element, calculates the dynamic cutting force of the unequal pitch end mill; the dynamic cutting force includes: side cutting force and bottom cutting force; based on the dynamic cutting force, establishes the dynamic control equation of the unequal pitch end mill milling system; uses the improved semi-discrete method in the time domain to solve the dynamic control equation of the unequal pitch end mill milling system, and obtains the milling stability limit diagram; determines the stable cutting parameters based on the milling stability limit diagram. The server 104 can feedback the obtained stable cutting parameters to the terminal 102. In addition, in some embodiments, the method for determining the stable cutting parameters for precision die milling can also be implemented separately by the server 104 or the terminal 102. For example, the terminal 102 can directly determine the stable cutting parameters for the unequal pitch end mill model, or the server 104 can obtain the unequal pitch end mill model from the data storage system and determine the cutting parameters for the unequal pitch end mill model.

[0038] Among them, the terminal 102 can be, but is not limited to, various desktop computers, laptop computers, smart phones and tablet computers. The server 104 can be implemented by an independent server or a server cluster composed of multiple servers, and can also be a cloud server.

[0039] In an exemplary embodiment, as Figure 2 shown, a method for determining stable cutting parameters for precision die milling is provided. This method is executed by a computer device, and can be specifically executed alone by a computer device such as a terminal or a server, or jointly executed by a terminal and a server. In the embodiments of the present application, taking this method applied to Figure 1 the server 104 in it as an example for illustration, it includes the following steps S1 to step S7.

[0040] Among them:

[0041] S1: Divide the unequal pitch end mill along the axial direction into a finite number of cutting micro-elements.

[0042] S2: Calculate the instantaneous cutting thickness of each cutting micro-element.

[0043] S3: Calculate the dynamic cutting force of the variable pitch end mill based on the instantaneous cutting thickness of each cutting element. The dynamic cutting force includes: side cutting force and bottom cutting force.

[0044] S4: Establish the dynamic control equation of the milling system of the variable pitch end mill based on the dynamic cutting force.

[0045] S5: Solve the dynamic control equation of the milling system of the variable pitch end mill by using the improved semi-discrete method in the time domain to obtain the milling stability limit diagram.

[0046] S6: Determine the stable cutting parameters based on the milling stability limit diagram.

[0047] Implementing the above steps S1 to S6, first, the variable pitch end mill is axially decomposed into a finite number of cutting elements, calculate the instantaneous cutting thickness corresponding to the cutting element at each axial height, then calculate the dynamic cutting forces of the side cutting edge and the bottom cutting edge of the variable pitch end mill respectively, establish the dynamic control equation of the milling system of the variable pitch end mill considering the bottom cutting force, and improve the semi-discrete method to adapt to the solution of the multi-time-delay system. Determine the stable milling parameters for precision molds based on the solved milling stability limit diagram. This application incorporates the contribution of the bottom cutting force of the variable pitch end mill into the model consideration range, improves the prediction accuracy of the milling stability limit, and based on this, stable cutting parameters with higher machining accuracy and machining efficiency can be obtained.

[0048] As an alternative implementation, as Figure 3 shown, in step S1, the variable pitch end mill is axially divided into a finite number of cutting elements, the number of elements is S, and the axial height of a single cutting element is dz. Their mathematical relationship with the axial cutting depth a p is:

[0049] a p = Sdz (1);

[0050] Refer to Figure 4 to calculate the instantaneous azimuth angle of the jth tooth at the axial height z:

[0051]

[0052] where, φ j (t,z) is the instantaneous azimuth angle corresponding to the jth tooth at the axial height z at time t; φ p.i is the pitch between the (j - 1)th tooth and the jth tooth; β is the helix angle of the tool; R is the tool radius; Ω is the spindle rotation angular velocity; z is the axial height.

[0053] As an alternative implementation, in step S2, the instantaneous cutting thickness of each cutting element is calculated. The instantaneous cutting thickness consists of two parts, namely the static cutting thickness generated by the feed and the dynamic cutting thickness caused by the regeneration effect. The calculation formula for the instantaneous cutting thickness of each cutting element is:

[0054] h j (t,z) = g(φ j )[f z sinφ j + Δxsinφ j + Δycosφ j (3);

[0055] Among them, h j (t,z) is the instantaneous cutting thickness of each cutting element; f z is the feed per tooth of the tool (mm / tooth); φ j is the instantaneous azimuth angle corresponding to the j-th tooth at the axial height z at time t; Δx = x(t) - x(t - τ j ), which is the vibration displacement difference of the tool in the x direction at time t; Δy = y(t) - y(t - τ j ), which is the vibration displacement difference of the tool in the y direction at time t, τ j is the regeneration time lag corresponding to the (j - 1)-th tooth and the j-th tooth; g(φ j ) is a step function used to judge the cutting state of the tool, and the expression is as follows:

[0056]

[0057] Among them, φ s is the cutting-in angle of the tooth; φ e is the cutting-out angle of the tooth; for the down milling condition, φ s = arccos(2a D - 1), φ e = π; for the up milling condition, φ s = 0, φ e = arccos(1 - 2a D ); the radial immersion ratio a D = a p / 2R.

[0058] As an alternative implementation, in step S3, based on the instantaneous cutting thickness of each cutting element, refer to Figure 5 , calculate the dynamic cutting force of the unequal pitch end mill. The axial force has little influence on the tool vibration, and only the tangential force and the radial force are considered. The total cutting force includes two parts, the side cutting edge force and the bottom cutting edge force. The calculation formula for the dynamic cutting force is:

[0059] F = F F + F B (5);

[0060] Wherein, F is the total dynamic cutting force; F F is the side cutting edge force; F B is the bottom cutting edge force. Calculate the side cutting edge force and the bottom cutting edge force respectively and then perform linear superposition to obtain the total cutting force.

[0061] Calculate the side cutting edge force. The side cutting edge force corresponding to the cutting microelement at the axial height z at time t is:

[0062]

[0063] Wherein, dF F,tj (t, z) is the tangential side cutting edge force corresponding to the cutting microelement; dF F,rj (t, z) is the radial side cutting edge force corresponding to the cutting microelement; K tc,F is the tangential side cutting edge force coefficient; K rc,F is the radial side cutting edge force coefficient; h j (t, z) is the instantaneous cutting thickness of each cutting microelement; dz is the axial height of a single cutting microelement.

[0064] Convert the tangential side cutting edge force corresponding to the cutting microelement and the radial side cutting edge force corresponding to the cutting microelement to the x and y directions:

[0065]

[0066] Wherein, dF F,xj (t, z) is the equivalent cutting force of the side cutting edge force corresponding to the cutting microelement in the x direction; dF F,yj (t, z) is the equivalent cutting force of the side cutting edge force corresponding to the cutting microelement in the y direction; φ j (t, z) is the instantaneous azimuth angle corresponding to the jth tooth at the axial height z at time t.

[0067] Furthermore, superpose the side cutting edge forces of each cutting microelement to obtain the total side cutting edge force:

[0068]

[0069] Wherein, F F is the side cutting edge force; F F,x is the equivalent component force of the total side cutting edge force in the x direction; F F,y is the equivalent component force of the total side cutting edge force in the y direction; N is the number of teeth; S is the number of cutting microelements; K tc,F is the tangential side cutting edge force coefficient; a xx,Fis the first factor of the periodically varying direction of the side cutting edge force; a xy,F is the second factor of the periodically varying direction of the side cutting edge force; a yx,F is the third factor of the periodically varying direction of the side cutting edge force; a yy,F is the fourth factor of the periodically varying direction of the side cutting edge force; Δx is the vibration displacement difference of the tool in the x direction at time t; Δy is the vibration displacement difference of the tool in the y direction at time t.

[0070] In the factor matrix of the periodically varying direction of the side cutting edge force, the expressions of each element are:

[0071]

[0072] where, K r,F = K rc,F / K tc,F .

[0073] Calculate the bottom cutting edge force. The bottom cutting edge force corresponding to the j-th tooth is related to the instantaneous cutting width and is expressed as:

[0074]

[0075] where, F B,tj (t) is the tangential bottom cutting edge force; F B,rj (t) is the radial bottom cutting edge force; K tc,B is the tangential bottom cutting edge force coefficient; K rc,B is the radial bottom cutting edge force coefficient; w(t) is the width of the part of the bottom cutting edge participating in cutting, and its value is approximately equal to the instantaneous cutting thickness of the first cutting microelement at the end of the tool.

[0076] Convert the tangential bottom cutting edge force corresponding to the cutting microelement and the radial bottom cutting edge force corresponding to the cutting microelement to the x and y directions:

[0077]

[0078] where, F B,xj (t) is the equivalent cutting force of the tangential bottom cutting edge force corresponding to the cutting microelement in the x direction; F B,yj (t) is the equivalent cutting force of the tangential bottom cutting edge force corresponding to the cutting microelement in the y direction; φ j (t,z) is the instantaneous azimuth angle corresponding to the j-th tooth at the axial height z at time t.

[0079] Furthermore, sum up the cutting forces of each bottom cutting edge to obtain the total bottom cutting edge force. For the unity of the mathematical expression form, a double summation is still introduced:

[0080]

[0081] Among them, F B is the cutting force of the bottom edge; F B,x is the equivalent component force of the total bottom-edge cutting force in the x direction; F B,y is the equivalent component force of the total bottom-edge cutting force in the y direction; N is the number of teeth of the cutter; S is the number of cutting micro-elements; K tc,B is the tangential bottom-edge cutting force coefficient; a xx,B is the first factor of the periodically varying bottom-edge cutting force direction; a xy,B is the second factor of the periodically varying bottom-edge cutting force direction; a yx,B is the third factor of the periodically varying bottom-edge cutting force direction; a yy,B is the fourth factor of the periodically varying bottom-edge cutting force direction; Δx is the vibration displacement difference of the tool in the x direction at time t; Δy is the vibration displacement difference of the tool in the y direction at time t; G(k) is a judgment function used to illustrate that the bottom-edge cutting force is included in the calculation of the first micro-element at the tool tip;

[0082] In the periodically varying bottom-edge cutting force direction factor matrix, the expressions of each element are:

[0083]

[0084] Among them, K r,B = K rc,B / K tc,B ; when the value of k in Equation (12) is not 1, K r,B = 0; which means that the bottom-edge cutting force only exists when calculating the cutting force of the first cutting micro-element at the tool tip, that is, when k = 1 in the formula, k is an accumulation coefficient and has no practical meaning.

[0085] As an optional implementation manner, as Figure 6 shown, in step S4, a dynamic control equation for the milling machining system of an unequal-pitch end mill is established, and the expression of the dynamic control equation for the milling machining system of the unequal-pitch end mill is:

[0086]

[0087] In Equation (14):

[0088]

[0089] Among them, M is the modal mass matrix of the system; C is the modal damping matrix of the system; K is the modal stiffness matrix of the system; q(t) is the modal coordinate; m x is the modal mass of the tool-spindle system in the x direction; m y is the modal mass of the tool-spindle system in the y direction; c x is the modal damping of the tool-spindle system in the x direction; cy is the modal damping of the tool - spindle system in the y - direction; k x is the modal stiffness of the tool - spindle system in the x - direction; k y The modal stiffness of the tool - spindle system in the y - direction; x(t) is the displacement of the tool in the x - direction; y(t) is the displacement of the tool in the y - direction; N is the number of teeth of the cutter; S is the number of cutting micro - elements; K tc,F is the tangential side - cutting force coefficient; a xx,F is the first factor of the periodically - varying side - cutting force direction; a xy,F is the second factor of the periodically - varying side - cutting force direction; a yx,F is the third factor of the periodically - varying side - cutting force direction; a yy,F is the fourth factor of the periodically - varying side - cutting force direction; K tc,B is the tangential bottom - cutting force coefficient; a xx,B is the first factor of the periodically - varying bottom - cutting force direction; a xy,B is the second factor of the periodically - varying bottom - cutting force direction; a yx,B is the third factor of the periodically - varying bottom - cutting force direction; a yy,B is the fourth factor of the periodically - varying bottom - cutting force direction; Δx is the vibration displacement difference of the tool in the x - direction at time t; Δy is the vibration displacement difference of the tool in the y - direction at time t.

[0090] As an alternative implementation, in step S5, the time - domain improved semi - discrete method is used to solve the dynamic control equation of the unequal - pitch end - milling cutter milling system, and the milling stability limit diagram is obtained, which specifically includes:

[0091] S51: In equation (14), select the state factor Separate the current - time dynamic behavior from the time - delay dynamic behavior, then equation (14) can be rewritten in the following state - space equation form:

[0092]

[0093] In equation (16):

[0094]

[0095] S52: Discretize the spindle period T into a finite number of time micro - elements, the number of micro - elements is n, and the length of the time micro - element is Δt; the time - delay τ between the (j - 1) - th tooth and the j - th tooth j The corresponding number of time micro - elements is m j , and their relationship is as follows:

[0096]

[0097] Within an extremely small time interval [t i , t i+1 , Equation (16) can be approximately expressed as:

[0098]

[0099] In Equation (19):

[0100]

[0101] In Equation (20), denotes w j,1 and w j,2 respectively denote the weight coefficients of {u(t i -τ j )} with respect to the two interval endpoints of the delay interval .

[0102] Given the initial value {u(t i )} = {u i}, the solution of Equation (19) can be expressed as:

[0103]

[0104] Substituting t = t i+1 and into Equation (21) gives:

[0105]

[0106] In Equation (22):

[0107]

[0108] Define V i .

[0109]

[0110] In Equation (24):

[0111]

[0112] By simultaneously solving Equation (22) and Equation (24), the discrete mapping form of adjacent time intervals can be constructed:

[0113] V i+1 = D i V i (26);

[0114] In Equation (26), the state transition matrix can be expressed as:

[0115]

[0116] In Equation (27), D i has a dimension of (2l max +4)×(2l max +4), and the positions of Q j,i,1 and Q j,i,2 in the matrix mainly depend on the variable l j determined by the time delay τ j , starting from the (2l j +1)-th column and the (2l j +3)-th column respectively.

[0117] By combining Equation (25) and Equation (26), within one main axis rotation period, the state transition matrix can be expressed as:

[0118] V k = ΦV0 = D k-1 D k-2 …D1V0 (28);

[0119] S53: Determine the stable state of the system according to Floquet theory, and the determination basis is as follows:

[0120]

[0121] In Equation (29), ζ is the maximum value of the characteristic roots of the state transition matrix Φ. Thus, the stable state of the milling system can be judged at each rotational speed and axial cutting depth, and the milling stability limit diagram can be drawn. See Figure 7 .

[0122] It should be noted that in the solution process of steps S51 - S53, the newly emerged parameters have no practical significance and are all combined expressions of known parameters in the transformation process.

[0123] See Figure 7 , where curve A considers the cutting situation of the bottom edge, curve B is the case of the conventional mechanical model. The lobe-shaped curve in the figure is the milling stability limit boundary. The area above the curve is the unstable region, the area below the curve is the stable region, and the points on the curve are the critical stable regions. In Figure 7 , compared with curve B obtained by the traditional algorithm, curve A obtained by the described algorithm has a larger stable region. Based on the milling stability limit diagram, the best rotational speed - cutting depth combination can be selected within the stable region to obtain stable cutting parameters with higher machining accuracy and machining efficiency.

[0124] The present application also provides an application scenario, which applies the above-mentioned method for determining stable cutting parameters for precision die milling. Specifically: The method for determining stable cutting parameters for precision die milling provided in this embodiment can be applied in a milling processing scenario. The milling processing scenario includes: a division step, an instantaneous cutting thickness calculation step, a dynamic cutting force calculation step, a kinetic control equation establishment step, a solution step, and a stable cutting parameter determination step; First, divide the unequal pitch end mill into a finite number of cutting micro-elements along the axial direction; calculate the instantaneous cutting thickness of each cutting micro-element; based on the instantaneous cutting thickness of each cutting micro-element, calculate the dynamic cutting force of the unequal pitch end mill; the dynamic cutting force includes: side cutting force and bottom cutting force; Secondly, based on the dynamic cutting force, establish a kinetic control equation for the unequal pitch end mill milling processing system; use the time-domain improved semi-discrete method to solve the kinetic control equation of the unequal pitch end mill milling processing system to obtain a milling stability limit diagram; Then, based on the milling stability limit diagram, the stable cutting parameters can be determined.

[0125] Based on the same inventive concept, the embodiment of the present application also provides a device for determining stable cutting parameters for precision die milling for implementing the above-mentioned method for determining stable cutting parameters for precision die milling. The solution provided by this device to solve the problem is similar to the solution recorded in the above method. Therefore, the specific limitations in one or more embodiments of the device for determining stable cutting parameters for precision die milling provided below can refer to the limitations on the method for determining stable cutting parameters for precision die milling in the above text, and will not be repeated here.

[0126] In an exemplary embodiment, as Figure 8 shown, a device for determining stable cutting parameters for precision die milling is provided. The device for determining stable cutting parameters for precision die milling includes:

[0127] A division unit M1, configured to divide the unequal pitch end mill into a finite number of cutting micro-elements along the axial direction.

[0128] An instantaneous cutting thickness calculation unit M2, configured to calculate the instantaneous cutting thickness of each cutting micro-element.

[0129] A dynamic cutting force calculation unit M3, configured to calculate the dynamic cutting force of the unequal pitch end mill based on the instantaneous cutting thickness of each cutting micro-element; the dynamic cutting force includes: side cutting force and bottom cutting force.

[0130] A kinetic control equation establishment unit M4, configured to establish a kinetic control equation for the unequal pitch end mill milling processing system based on the dynamic cutting force.

[0131] A solution unit M5, which is used to solve the dynamic control equation of the unequal-pitch end milling cutter milling system by using the time-domain improved semi-discrete method to obtain a milling stability limit diagram.

[0132] A stable cutting parameter determination unit M6, which is used to determine stable cutting parameters based on the milling stability limit diagram.

[0133] In an exemplary embodiment, a computer device is provided. The computer device can be a server or a terminal, and its internal structure diagram can be as Figure 9 shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, abbreviated as I / O), and a communication interface. Among them, the processor, the memory, and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store unequal-pitch end milling cutter data. The input / output interface of the computer device is used to exchange information between the processor and external devices. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a method for determining stable cutting parameters for precision die milling.

[0134] Those skilled in the art can understand that Figure 9 the structure shown in

[0135] is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0136] In an exemplary embodiment, a computer-readable storage medium is also provided, storing a computer program, and when the computer program is executed by a processor, it implements the above-mentioned method embodiments.

[0137] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, it implements the above-mentioned method embodiments.

[0138] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use, and processing of relevant data need to comply with relevant regulations.

[0139] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, database, or other medium used in the various embodiments provided in this application can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0140] The databases involved in the various embodiments provided in this application can include at least one of relational databases and non-relational databases. Non-relational databases can include distributed databases based on blockchain, etc., and are not limited thereto. The processors involved in the various embodiments provided in this application can be general-purpose processors, central processors, graphics processors, digital signal processors, programmable logic devices, data processing logics based on quantum computing, etc., and are not limited thereto.

[0141] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0142] In this text, specific examples are used to elaborate on the principles and implementation manners of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application. At the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A method for determining stable cutting parameters for precision mold milling, characterized in that: The stable cutting parameter determination method for precision mold milling includes: Divide the unequal pitch end mill into a finite number of cutting micro-elements along the axial direction; Calculate the instantaneous cutting thickness of each cutting element; Based on the instantaneous cutting thickness of each cutting micro-element, the dynamic cutting force of the unequal pitch end mill is calculated; the dynamic cutting force includes: side cutting force and bottom cutting force; Based on the dynamic cutting force, a dynamic control equation of the milling system of the unequal pitch end mill is established; The time domain improved semi-discrete method is used to solve the dynamic control equation of the unequal pitch end mill milling system to obtain the milling stability limit diagram; Stable cutting parameters are determined based on the milling stability limit diagram.

2. The method for determining stable cutting parameters for precision mold milling according to claim 1, characterized in that: The calculation formula of the instantaneous cutting thickness of each cutting element is: h j (t,z)=g(φ j )[f z sinφ j +Δx sinφ j +Δy cosφ j ]; Among them, h j (t,z) is the instantaneous cutting thickness of each cutting element; g(φ j ) is a step function, which is used to judge the cutting state of the tool; f z is the feed rate per tooth of the tool; φ j is the instantaneous azimuth angle corresponding to the jth tooth at the axial height z at time t; Δx is the vibration displacement difference of the tool in the x direction at time t; Δy is the vibration displacement difference of the tool in the y direction at time t.

3. The method for determining stable cutting parameters for precision mold milling according to claim 1, characterized in that: The calculation formula of the dynamic cutting force is: F=F F +F B ; Where, F is the total dynamic cutting force; F F is the side cutting force; F B is the bottom cutting force.

4. The method for determining stable cutting parameters for precision mold milling according to claim 1, characterized in that: The calculation formula of the side cutting force is: Among them, F F is the side cutting force; F F,x is the equivalent component of the total side cutting force in the x direction; F F,y is the equivalent component of the total side cutting force in the y direction; N is the number of teeth; S is the number of cutting elements; K tc,F is the tangential side cutting force coefficient; a xx,F is the first factor of the periodically changing side cutting force direction; a xy,F is the second factor of the periodically changing side cutting force direction; a yx,F is the third factor of the periodically changing side cutting force direction; a yy,F is the fourth factor of the periodically changing side cutting force direction; Δx is the vibration displacement difference of the tool in the x direction at time t; Δy is the vibration displacement difference of the tool in the y direction at time t.

5. The method for determining stable cutting parameters for precision mold milling according to claim 1, characterized in that: The calculation formula of the bottom cutting force is: Among them, F B is the cutting force of the bottom edge; F B,x F is the equivalent component of the total cutting force at the bottom edge in the x direction; B,y is the equivalent component of the total cutting force on the bottom edge in the y direction; N is the number of teeth; S is the number of cutting elements; K tc,B is the tangential cutting force coefficient of the bottom edge; a xx,B is the first factor of the periodically changing cutting force direction of the bottom edge; a xy,B is the second factor of the periodically changing cutting force direction of the bottom edge; a yx,B is the third factor of the periodically changing cutting force direction of the bottom edge; a yy,B is the fourth factor of the periodically changing bottom cutting force direction; Δx is the vibration displacement difference of the tool in the x direction at time t; Δy is the vibration displacement difference of the tool in the y direction at time t; G(k) is the judgment function, which is used to illustrate that the bottom cutting force is included in the first infinitesimal calculation of the tool end; 6. The method for determining stable cutting parameters for precision mold milling according to claim 1, characterized in that: The expression of the dynamic control equation of the unequal pitch end mill milling system is: Where M is the modal mass matrix of the system; C is the modal damping matrix of the system; K is the modal stiffness matrix of the system; q(t) is the modal coordinate; N is the number of teeth; S is the number of cutting elements; K tc,F is the tangential side cutting force coefficient; a xx,F is the first factor of the periodically changing side cutting force direction; a xy,F is the second factor of the periodically changing side cutting force direction; a yx,F is the third factor of the periodically changing side cutting force direction; a yy,F K is the fourth factor of the periodically changing side cutting force direction; tc,B is the tangential cutting force coefficient of the bottom edge; a xx,B is the first factor of the periodically changing cutting force direction of the bottom edge; a xy,B is the second factor of the periodically changing cutting force direction of the bottom edge; a yx,B is the third factor of the periodically changing cutting force direction of the bottom edge; a yy,B is the fourth factor of the periodically changing bottom cutting force direction; Δx is the vibration displacement difference of the tool in the x direction at time t; Δy is the vibration displacement difference of the tool in the y direction at time t.

7. A stable cutting parameter determination device for precision mold milling, the stable cutting parameter determination device for precision mold milling is used to implement the stable cutting parameter determination method for precision mold milling according to any one of claims 1 to 6, characterized in that: The stable cutting parameter determination device for precision mold milling comprises: A division unit is used to divide the unequal pitch end mill into a finite number of cutting micro-elements along the axial direction; An instantaneous cutting thickness calculation unit is used to calculate the instantaneous cutting thickness of each cutting microelement; A dynamic cutting force calculation unit, used to calculate the dynamic cutting force of the unequal pitch end mill based on the instantaneous cutting thickness of each cutting micro-element; the dynamic cutting force includes: side cutting force and bottom cutting force; A dynamic control equation establishing unit, used for establishing a dynamic control equation of a milling processing system of an unequal pitch end mill based on the dynamic cutting force; A solving unit, used for solving the dynamic control equation of the unequal pitch end mill milling system by using a time domain improved semi-discrete method to obtain a milling stability limit diagram; The stable cutting parameter determination unit is used to determine the stable cutting parameter based on the milling stability limit diagram.

8. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the stable cutting parameter determination method for precision mold milling according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the stable cutting parameter determination method for precision mold milling described in any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the stable cutting parameter determination method for precision mold milling described in any one of claims 1 to 6 is implemented.

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