Design method of indexable milling cutter for machining large-modulus gear

Abstract

The invention relates to the technical field of complex forming of gear machining, and discloses a design method of an indexable milling cutter for machining a large-modulus gear, which comprises the following steps of: dispersing a theoretical edge shape line into a linear edge of a plurality of indexable blade combinations for replacement by using a linear edge shape approximate fitting design to form a fitting edge shape line; the fitting blade shape line is imported into three-dimensional software to determine the blade body blade space position, the blade position is determined in a tool nose point positioning mode, the blade shape lap joint error is controlled, the cutting angle of each blade is determined to conduct blade position correction, and the blade cutting edge and the lap joint blade shape line are made to be consistent; determining the distribution number and the spatial position of the blades on the cutter body and the positions and the sizes of the blade grooves and the chip flutes, checking the interference condition of the blade grooves and the chip flutes, and completing milling cutter modeling; and deviation optimization fitting and lap joint design of the lap joint edge-shaped line of the model and the theoretical edge-shaped line are detected. Discrete milling cutter profile modeling is adopted, a cutter tooth profile curve is calculated according to a theory, and a cutting edge is formed through lap joint of a universal blade, so that efficient design of the indexable gear milling cutter is achieved.

Description

Technical Field

[0001] The present invention relates to the field of complex forming technology for gear machining, and in particular to a method for designing an indexable milling cutter for machining large-module gears, which can provide technical support for low-cost, high-efficiency and high-precision machining of large-module gears of wind turbines, mining machinery, heavy machinery, etc. Background Art

[0002] With the continuous development of wind power technology, the demand for large wind power gears will continue to increase. This type of large modulus gear is characterized by large structural dimensions, complex profile curves, and the processed gear groove shape needs to meet specific requirements. It is difficult to meet production requirements using traditional gear processing methods. Existing large modulus gears processed by forming milling cutters are mainly divided into two categories. The first category is a disc milling cutter with carbide teeth with traditional back-shoveling characteristics. After the teeth are worn, they need to be reground before they can continue to be used. The machine tool accuracy and the material requirements of the teeth are high, and it is difficult to achieve the purpose of efficient tooth milling. Therefore, it is not widely used; the other category is an indexable gear milling cutter, whose blade line approaches the theoretical profile of the gear through discrete overlap of the blade. It can be used multiple times by changing the angle of the coated blade without regrinding, and the gear can be processed by a CNC gear milling machine, which is more efficient and convenient, and is more and more widely used.

[0003] At present, there are many challenges in the overlap method of indexable blades and the design method of tool profile curve in the processing of large modulus gears for wind power. For example: the existing fine processing indexable gear milling cutter generally designs corresponding special specific blades according to the parameters of the processed gear, so as to more accurately process the profile of the gear. Generally, no blade overlap is required, so the IT9 level of accuracy can be achieved in one processing, but high-precision assembly is required to meet the profile design requirements of the milling blade, and the cost of special blades is relatively high. The existing method of eliminating the processing errors of different gears by clamping different blades requires multiple blades to overlap to form the processing profile, which may lead to larger processing errors and it is difficult to eliminate the overlap marks between the blades, which in turn affects the processing quality of the gear. The existing method directly opens a suitable blade slot on the cutter body. When designing in 3D software, it is necessary to establish multiple reference planes, axes and points. It is quite cumbersome to determine the specific moving distance and rotation angle of these reference values, resulting in low efficiency in the design of the blade slot. Summary of the invention

[0004] The present invention aims to provide a method for designing an indexable gear milling cutter for machining large-module gears. The method adopts discrete milling cutter profile modeling, calculates the tool tooth profile curve according to theory, and uses multiple general conventional straight-edge blades to discretely overlap to form a cutting edge during the rough machining or semi-finishing process of the gear. This realizes the efficient design of the indexable gear milling cutter, reduces the machining cost, and improves the machining accuracy. This lays the foundation for the design of the indexable gear milling cutter and realizes the fitting machining of large-module gears such as wind power and mining machinery.

[0005] The basic solution provided by the present invention is: a method for designing an indexable milling cutter for machining large-module gears, the method comprising:

[0006] S1. According to the final tooth profile curve, tooth root machining allowance and tooth side machining allowance of the processed gear, the initial tooth groove profile curve after rough machining or semi-finishing machining is determined as the theoretical blade profile line; then, according to the blade profile error control requirements, the theoretical blade profile line is discretized into a plurality of linear blades composed of indexable inserts by linear blade profile approximation fitting design;

[0007] S2. Determine the basic parameters of the cutter body, wherein the basic parameters include diameter and thickness; import the fitting blade shape line of the linear blade into the 3D design software to determine the spatial position of the cutter body and the blade, determine the blade position by the tool tip point positioning method, and control the overlap error of the blade shape, and at the same time determine the cutting angle of each blade and correct the blade position so that the cutting edge of the blade is consistent with the overlap blade shape line;

[0008] S3, determine the number and spatial position of the blades on the cutter body, then determine the distribution position and shape size of the blade slots and chip slots, and check whether there is interference between the blade slots and chip slots, and complete the overall geometric modeling of the indexable gear milling cutter;

[0009] S4. For the designed indexable gear milling cutter model, detect its overlapping blade line, and analyze the deviation between the detected overlapping blade line and the fitting blade line to optimize the design process in S1-S3.

[0010] The present invention also provides an indexable milling cutter for processing large-module gears, the indexable gear milling cutter comprising and fasteners; the structure of at least the cutter body and the indexable blade of the indexable gear milling cutter is designed using the above-mentioned indexable milling cutter design method for processing large-module gears.

[0011] The working principle and advantages of the present invention are:

[0012] Compared with the existing technology, this scheme proposes a design method of constructing the blade line profile using a discrete model in the design process of an indexable milling cutter for processing large-module gears, which has many advantages over the existing overlap method. The existing overlap method is relatively complicated in blade selection and assembly, and blades need to be customized for different gear parameters, which is costly and has limited efficiency. The discrete model method uses universal conventional blades to approximate the gear contour curve through clever combination and positioning, which greatly simplifies the design and production process, reduces dependence on special blades, and effectively controls costs. In terms of precision control, it is difficult to accurately adjust the blade cutting angle with the traditional overlap method, and large errors are prone to occur, affecting the gear processing quality. The discrete model uses advanced three-dimensional design software to accurately calculate and optimize the blade position and cutting angle, so that the blade overlap line is highly consistent with the theoretical blade line, significantly improving the processing accuracy, and providing a more reliable solution for efficient and high-precision processing of large-module gears.

[0013] The present invention adopts a design method for discretely approximating the gear contour curve by overlapping universal conventional blades, which can reduce the cost of milling blades and improve processing efficiency. That is, in rough machining or semi-finishing of indexable gear milling cutters, multiple universal conventional straight blades are combined together by overlapping blades to approximate the tooth shape. This method greatly improves the efficiency of rough machining and semi-finishing of gears, reduces the cost of special customized blades, and has better versatility and good applicability.

[0014] The present invention controls the error of the blade overlap line through scanning and measurement and other related operations of three-dimensional design software, can eliminate the processing errors of different gears, and improve the processing accuracy. In the process, the cutting angle of the blade is gradually optimized so that the allowable error value between the boundary contour line obtained by scanning the axially overlapping blade cutting edges and the blade overlap line is controlled to be less than or equal to 0.1mm, the accuracy is significantly improved, and the existing problem of eliminating the processing errors of different gears by clamping different blades can be avoided.

[0015] The present invention determines the spatial distribution of the blade slot and the chip groove directly through the blade position by analyzing the mutual interference between the blade slot and the chip groove, as well as the relative position relationship between the blade and the blade slot and the chip groove. This method of spatial position distribution of the blade, blade slot and chip groove can achieve that each blade edge type accurately covers the entire tool body, eliminates interference effects and improves design efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic flow chart of a method for designing an indexable milling cutter for machining large-module gears provided by an embodiment of the present invention;

[0017] Figure 2 A schematic diagram of a theoretical final tooth profile curve of a processed gear provided by an embodiment of the present invention;

[0018] Figure 3 A schematic diagram of a theoretical final tooth profile curve and a fitting edge line of a gear after rough machining provided by an embodiment of the present invention;

[0019] Figure 4 A schematic diagram of blade overlaps on a cutter body provided by an embodiment of the present invention to form a blade-shaped overlap line;

[0020] Figure 5 A schematic diagram of a blade positioning method and a chip groove structure provided by an embodiment of the present invention;

[0021] Figure 6 Schematic diagram of the spatial position distribution of the blade, blade slot, and chip groove provided in an embodiment of the present invention Figure 1 ;

[0022] Figure 7 Schematic diagram of the spatial position distribution of the blade, blade slot, and chip groove provided in an embodiment of the present invention Figure 2 ;

[0023] Figure 8 A schematic diagram of the structure of the indexable gear milling cutter disc with a final design provided by an embodiment of the present invention;

[0024] Fig. 9 A schematic diagram of a preliminary position distribution design for a blade interference check according to an embodiment of the present invention;

[0025] Fig.10 A schematic diagram of the inner and outer deviations of the detected overlapping edge line of the milling cutter model provided by an embodiment of the present invention and the theoretical edge line of the blade;

[0026] The symbols in the drawings of the specification include: a cutter body 1, a blade 2, a chip groove 3, and a fastener 4. DETAILED DESCRIPTION

[0027] The following is a further detailed description through specific implementation methods:

[0028] Example

[0029] The indexable gear milling cutter consists of a cutter body 1, an indexable insert 2 and its fastener 4 (set screw). The insert 2 is a key component directly involved in cutting. Its blade shape, quantity, and the number and type of overlaps of the insert 2 are determined according to basic parameters such as the number of teeth and module of the gear to be processed. The design of the insert 2 needs to consider cutting stability and cutting efficiency, as well as the balanced distribution of cutting force. As the main body of the tool, the cutter body 1 is responsible for the assembly of the insert 2 and the connection between the tool and the machine tool. The design of the cutter body 1 needs to determine the geometric parameters and position of the insert slot and the position of the chip groove according to the geometric parameters and installation position of the insert 2 to ensure the fixed reliability of the insert 2 and the smooth discharge of chips. The structural parameters of the cutter body 1 also need to consider stiffness and durability to meet the processing requirements. The set screw plays the role of fixing the insert 2. Selecting a suitable set screw can ensure the stability and cutting quality of the insert 2. Therefore, the steps of designing an indexable gear milling cutter include determining the shape and quantity of the insert 2, designing the structure of the cutter body 1 and the geometric shape and parameters of the insert slot and chip groove, and selecting a suitable set screw. These steps require comprehensive consideration of cutting efficiency, processing quality and tool stability.

[0030] Specifically, as attached Figure 1 As shown: A method for designing an indexable milling cutter for machining large-module gears, the method comprising:

[0031] S1. According to the final tooth profile curve, tooth root machining allowance and tooth side machining allowance of the processed gear, determine the initial contour curve of the tooth groove after rough machining or semi-finishing machining as the theoretical blade profile line; then according to the blade profile error control requirements, use the linear blade profile approximate fitting design to discretize the theoretical blade profile line into a plurality of linear blades composed of indexable inserts 2 to replace it;

[0032] Specifically, a rectangular coordinate system is established with the center O of the gear as the coordinate origin and the symmetry axis of the tooth groove as the Y axis;

[0033] Take any point K on the final tooth profile curve, and its OK radius is r k , the angle between OK and the Y axis is the azimuth angle θ k , calculate the azimuth angle θ by the following formula k :

[0034]

[0035] Among them, m, z, α, χ, and Δs are the module, number of teeth, pitch circle pressure angle, displacement coefficient, and tooth thickness reduction of the processed gear respectively; r b is the base circle radius based on the basic parameters of the gear being processed; inv is the inverse operation.

[0036] In addition, the tooth height coefficient Backlash coefficient c * , tooth root radius rf , Pitch circle radius r c , Tip circle radius r a , as the calculation tooth thickness S, r b and r k The basis of the present invention is the prior art, which will not be described in detail.

[0037] According to the coordinate equation x k =r k sinθ k ,y k =r k cosθ k , calculate the theoretical final tooth profile curve of the processed gear.

[0038] When designing an indexable milling cutter for machining large-module gears, the theoretical final tooth profile curve is calculated by comprehensively considering various parameters of the gear such as module, number of teeth, pitch circle pressure angle, etc., which can ensure that the milling cutter and the gear tooth shape are accurately matched. This precise design not only improves the processing accuracy and ensures the correctness of the tooth shape, but also optimizes the contact between the teeth and reduces operating noise and vibration. At the same time, considering factors such as the displacement coefficient and the amount of thinning of the tooth thickness, it helps to avoid root cutting and enhance the strength of the gear. By adjusting the tooth height coefficient and the tooth clearance coefficient, the lubrication conditions can be improved, wear can be reduced, and the service life can be extended. In addition, the design based on geometric dimensions such as the base circle radius and the root circle radius enables the milling cutter to adapt to the processing requirements of large-module gears of different specifications, thereby improving production efficiency and flexibility. Overall, this design method provides a solid foundation for manufacturing high-quality and high-performance gears.

[0039] In this embodiment, the module m of the processed spur involute gear is 20, the number of teeth z is 108, and the pitch circle pressure angle is 20°. Figure 2 The coordinate system shown in the figure is used, and according to the basic parameters of the processed spur cylindrical involute gear and the radius, azimuth, and coordinate equation of any point K on the final gear tooth profile curve, multiple sets of coordinate point values ​​on the tooth profile are theoretically calculated by MATLAB software, and the corresponding transition fillet is designed to obtain the theoretical final tooth profile curve of the involute gear. Among them, since the transition arc part at the bottom of the tooth groove of the processed gear does not participate in the meshing and does not affect the gear processing accuracy, the transition arc adopts the top edge arc of the commonly used 20-module gear indexable insert 2, and its arc radius can be 6mm.

[0040] like Figure 3 As shown, due to the need for rough machining to leave an allowance ( Figure 3(b), according to the tooth root machining allowance and the tooth side machining allowance, the equidistant offset curve of the theoretical final tooth profile curve is reversed, and the equidistant offset curve is used as the initial tooth groove profile curve after the gear is rough-machined or semi-finished. That is, in this embodiment, the theoretical final tooth profile curve of the entire involute gear is equidistantly offset inward to obtain the initial tooth groove profile curve after the gear is machined as the theoretical blade line, and the initial tooth groove profile curve as the theoretical blade line is fitted with an approximate straight line to obtain the fitted blade line, that is, Figure 3 (a) shows the process of converting the theoretical calculated involute profile to the approximate straight line fitting profile. The machining allowance calculation in the above process can ensure the accurate cutting of the milling cutter, improve the gear machining accuracy and surface quality, and enhance the meshing performance.

[0041] S2. Determine the basic parameters of the cutter body 1, wherein the basic parameters include diameter and thickness; import the fitted blade profile line into the three-dimensional design software to determine the spatial position of the cutter body 1 and the blade 2; in the overlap design of the blade 2, use the tool tip point positioning method to determine the position of each blade 2 when the blade 2 overlaps, and control the overlap error of the blade shape, and at the same time determine the cutting angle of each blade 2 and correct the position of the blade 2 so that the cutting edge of the blade 2 is consistent with the overlap blade profile line.

[0042] Specifically, the existing 3D design software is used for modeling, and the basic parameters of the cutter body 1 are determined according to the relationship between the modulus of the processed gear and the final tooth profile curve. In this embodiment, the basic parameters of the cutter body 1 are determined to be 420 mm in diameter, 100 mm in thickness, 90 mm in center hole diameter, 25.4 mm in keyway width, and 12.7 mm in keyway depth. According to the relationship with the theoretical modeling tooth profile, the initial shape model of the axial section of the cutter body 1 is established, and the basic body of the cutter body 1 is obtained by using the rotating boss operation in the 3D design software.

[0043] The blade line is formed by overlapping a plurality of tooth side blades and a tooth top blade. In this embodiment, the basic dimensions of the tooth side blades are selected to be 12.7×12.7×6.35 mm, and the basic dimensions of the tooth top blades are selected to be 19.05×14.3×7.94 mm.

[0044] In the specific process of overlapping, a fitting blade line is introduced into the axial section of the cutter body 1; Figure 4 As shown in (a), the intersection of the side edge and the bottom is confirmed as the tip of the first blade, and the tip of the remaining blades is taken at a certain distance on the fitting blade line; Figure 4As shown in (b), the front cutting face and the back cutting face of the blade 2 are determined according to the front angle and the back angle, and then the radial and axial positions of each blade 2 are determined according to the front cutting face and the back cutting face, and a three-dimensional solid modeling of the blade 2 is established. This solution accurately defines the tip point position of each blade 2 by importing a fitting blade shape line in the axial section of the tool body 1, thereby ensuring the continuity and consistency of the side edge and the top edge. The front cutting face and the back cutting face are determined according to the front angle and the back angle, so as to accurately locate the radial and axial position of the blade 2 and realize three-dimensional solid modeling. Compared with the traditional overlap method, this method improves the installation accuracy of the blade 2, enhances the cutting stability, optimizes the overall performance of the tool, and simplifies the layout design of the blade 2, which helps to achieve efficient and accurate large-module gear processing.

[0045] At this time, the envelope formed by the overlap of each blade 2 is used as the blade overlap line with a processing allowance for the indexable gear milling cutter. During the process, the cutting angle of the blade 2 is gradually optimized through scanning and measuring operations of the three-dimensional design software, so that the error value between the boundary contour line obtained by circumferential scanning of the cutting edges of the axially overlapping blades 2 and the blade overlap line is within the allowable range, and the allowable error value is controlled within a range of less than or equal to 0.1 mm.

[0046] At the same time, the overlapping length of the target cutting edge is selected, and the blade overlap line is optimized to control the blade overlap error; wherein, the cutting edges composed of two adjacent blades 2 have a certain overlap in cutting marks during cutting, and the overlapping length of the cutting edges is selected according to the ratio of the overlapping length of adjacent cutting marks to the total cutting mark length of adjacent cutting edges, wherein the ratio is targeted to be between 30% and 50% to ensure the continuity and smoothness of the gear tooth surface.

[0047] Compared with the traditional method, the above process can significantly reduce the error between the boundary contour line and the blade overlap line between the two axially overlapping blades, ensure high-precision blade consistency, improve the tool processing accuracy and surface quality, and at the same time simplify the adjustment process, enhance production efficiency and tool life.

[0048] S3, determine the distribution quantity and spatial position of the blade 2 on the cutter body 1, then determine the distribution position and shape size of the blade groove and the chip groove 3, check whether there is interference between the blade groove and the chip groove 3, and complete the overall geometric modeling of the indexable gear milling cutter;

[0049] Specifically, in S3, the number of blades 2 distributed on the blade body 1 is determined as:

[0050] Based on the number of tooth side blades required for single-sided tooth groove forming is N, the length of the tooth side blade is l c , calculate the height H of the blade overlap projection in the tooth groove depth direction d ; Specific calculation is based on the following formula:

[0051]

[0052] Where N is the number of tooth side blades required for single-side tooth groove forming, l c is the tooth side blade length, ψ i is the tooth side blade edge correction angle, l d is the tooth tip blade length, ψ d is the correction angle of the blade edge line at the tooth top, and Δl is the blade edge overlap length.

[0053] According to the overlap of blade 2 to form the tooth groove edge shape H d The relationship with the tooth groove height h satisfies h≤H d ≤h+l c cosα, calculate the number of tooth side blades N, where α is the pitch circle pressure angle of the gear being processed.

[0054] During the gear milling process of the indexable gear milling cutter, because the top edge processing state is relatively poor, the blade 2 is prone to greater wear. Therefore, when designing an indexable rough milling cutter, the number of top edge blades involved in forming the effective tooth shape is usually 1.5 to 3 times that of the side edge blades.

[0055] The number of milling cutter teeth Z is calculated by the following formula:

[0056] Z = 12.6 × D / (D + 4a e )

[0057] Where D is the target diameter of the milling cutter, a e Target milling depth for the milling cutter.

[0058] The number of side cutting blades of the milling cutter is 2N×Z.

[0059] In this embodiment, the blade overlap Δl is 2 mm, ψ d , i Both are 5°. Substitute the lengths of the tooth side and tooth top blades into the above two formulas and calculate the number of side tooth blades N to be 4.

[0060] Taking into account the problem that the top blade wears more seriously, the number of effective teeth of the top blade is increased to twice the number of effective teeth of the side blade, thereby improving the service life and processing efficiency of the tool while meeting the processing requirements.

[0061] The effective cutting tooth shape of the indexable gear milling cutter is composed of the top edge and the side edge overlap on the corresponding two sides. One tooth shape consists of 2 top edges and 8 side edges. The diameter of the designed indexable gear milling cutter D = 420mm, the milling depth is the tooth height a e=45mm is substituted into the corresponding calculation formula above, and the number of milling cutter teeth is calculated to be 9. However, considering the convenience of tool manufacturing and the arrangement of blades, the number of milling cutter teeth should not be an odd number. Therefore, in this embodiment, the number of milling cutter teeth is selected to be 10, and the required number of top blades is 20, the effective number of top blade teeth is 10, the effective number of side blade teeth is 5, and the number of side blade blades is 2N×5, i.e. 40. This can ensure that during the processing, the wear of the top blade matches the number of side blade blades, while ensuring the processing quality and efficiency.

[0062] The face positioning method of the indexable insert 2 ensures that the position of the insert on the cutter body is relatively stable and not prone to displacement or twisting, thereby maintaining stability during the cutting process. In addition, the face positioning method fixed by the set screw only requires the installation and removal of the indexable insert in the insert slot of the cutter body to change the blade without the need for a complicated adjustment process, such as Figure 5 As shown, Figure 5 (a) is the top blade positioning method, Figure 5 (b) is the side blade positioning method.

[0063] A chip groove 3 needs to be designed in the cutting direction of the insert slot where the insert is installed. The shape and size of the chip groove 3 can affect the flow direction of the chips and the efficiency of chip removal. Properly increasing the chip groove can increase the chip space, which helps to ensure smooth chip removal, improve the efficiency and quality of gear processing, and make the tool have good cutting performance. However, it is also necessary to consider that an excessively large chip groove size will affect the strength of the tool body. Its size should be reduced while ensuring the cutting performance as much as possible to avoid affecting the strength and life of the tool body. Taking into account the characteristics of gear milling processing, this scheme designs the chip groove 3 into a semi-cylinder-like form (i.e., similar to a semi-cylinder), determines the size of the chip groove 3 according to the chip removal effect, processing efficiency and tool body strength, and determines the chip space size of the insert groove 3 according to the amount of chip removal removed by the tool when it rotates one circle, which is 5 times or more. The minimum radius r of the chip groove 3 is calculated. p , you can choose r p =10mm, and at the same time make the three peripheral surfaces of the chip groove tangent to the rake face to ensure smooth chip removal, such as Figure 5 (c) is the chip groove structure. Check whether there is interference between each insert groove and the chip groove 3. If there is interference, eliminate the interference through the preset method, which includes adjusting the offset angle, the number of circular arrays and modifying the chip groove shape. This part is a rough adjustment.

[0064] In S3, the blades 2 are staggered on the cutter body 1 by circumferential offset, i.e., circumferential rotation offset operation, through the three-dimensional design software, and the distribution is optimized according to the cutting performance; the spatial position of a group of blades is preliminarily determined, and then the spatial arrangement of the blade slot and the chip groove is determined, and the blade slot and chip groove models are established by stretching and cutting operations, such as Figure 6(a) and (b); and the array and symmetric operation are used to overlap adjacent blades in the axial direction and stagger adjacent blades in the circumferential direction so that each blade type covers the entire blade body, as shown in FIG. Figure 7 As shown in the figure, the structural design of the entire cutter body is completed. The indexable insert is assembled to the cutter body, and fasteners such as screws are used. The assembly modeling of the indexable gear rough milling cutter is shown in the figure. Figure 8 shown.

[0065] S4. For the designed indexable gear milling cutter model, detect its overlapping blade line, and analyze the deviation between the detected overlapping blade line and the fitting blade line to optimize the design in S1-S3.

[0066] Specifically, after obtaining the milling cutter model, it is also necessary to check whether there is interference between the blade groove and the chip groove. At this time, further inspection is performed after the blade is installed. The machining contour curve formed by the overlap of the blade of the designed indexable gear milling cutter is detected by tool presetting and measuring instrument to ensure the design accuracy requirements of the indexable milling cutter disc. Fig. 9 , Fig.10 The instructions are as follows:

[0067] For example Figure 7 The three-dimensional model of the indexable gear rough milling cutter shown is used to check whether there is interference between each blade groove and the chip groove. If there is interference, it can be eliminated by adjusting the offset angle and the number of circular arrays or the shape of the chip groove.

[0068] After the blade is installed, if the blade circumferential position interferes, the circumferential adjustment method is adopted, including:

[0069] The blade i is used to replace the top edge and the blade groove and chip groove of the adjacent overlapping side edges on the cutter body, and the initial circumferential position angle is θi, and the corresponding blades are evenly distributed in the circumference;

[0070] The initial circumferential position of blade i=2 satisfies the non-interference relationship with the circumferential position of blade i=1; the initial circumferential position of blade i>2 satisfies the non-interference relationship with the circumferential positions of blade i-1 and blade i-2, and also satisfies the non-interference relationship with the axial position on the same side of blade i-2, so as to determine the preliminary design position of each blade groove without interference with the chip groove;

[0071] Among them, the factors determining the circumferential position non-interference condition include the angular difference of circumferential interference, the circumferential adjacent angles of the top edge on the same side, and the circumferential distribution circumferential angles occupied by the i-th blade and the corresponding chip groove in the circumferential direction; the circumferential adjacent angles of the side edge on the same side are considered in the circumferential non-interference condition of the corresponding blade. This method can more accurately avoid the interference problem between the blade and the chip groove, optimize the tool design, improve the processing efficiency and tool reliability, and reduce the risk of tool damage caused by interference.

[0072] The details are as follows:

[0073] Circumferential adjacent angles of top cutting edges on the same side θ a =2π / Z a , where Za is the effective number of teeth on the top edge;

[0074] Circumferential adjacent angle of side cutting edge on the same side θ c =2π / Z c , where Zc is the effective number of teeth on the side edge;

[0075] The circumferential distribution angle of the i-th insert and the corresponding chip groove in the circumferential direction Where bi is the width of the i-th blade, r mini is the shortest distance from the i-th blade to the chip groove and the origin;

[0076] The angular difference α that causes interference in the circumferential direction g .

[0077] In this embodiment, i=1, 2, 3, 4, 5, blades 1 to 5 are set, and their initial circumferential position angles θ 1 ,θ 2 ,θ 3 ,θ 4 ,θ 5 , the corresponding blades are evenly distributed around the circumference. Since the blade body near the top edge is thinner, it is more likely to interfere. Take the initial circumferential position angle θ of blade 1 1 =18°.

[0078] The initial circumferential position of blade i=2 satisfies the condition that there is no interference with the circumferential position of blade i=1:

[0079] Blade i=2 initial circumferential position θ 2 =θ 1 +θ a / 4, the side edges adjacent to the top edge blade 1 do not interfere with each other in the circumferential direction, and the circumferential distribution angle of the blade i=2, blade i=1 and the corresponding chip groove in the circumferential direction is smaller than the interval angle between the top edge and the adjacent opposite side top edge: θ m2 +θ m1 <θ a / 2; also satisfying the same side top edge 1 and side edge 2: θ 2 -θ 1 >α g , and the top edge and the adjacent opposite side top edge: θ 1 +θ a / 2-θ 2 >α g .

[0080] The initial circumferential position of blade i>2 satisfies the condition that there is no interference with the circumferential position of blade i-1 and blade i-2, and also satisfies the condition that there is no interference with the axial position on the same side of blade i-2:

[0081] Side edge i-1 and side edge i on the same side: θ i -θ i-1 >a g ,θ i-1 +θ c -θ i >a g , top edge i-2 and side edge i on the same side: θ i -θ i-2 >a g ,θ i-2 +θ a -θ i >a g .

[0082] Convert to θ i-2 Relationship: θ i -θ i-2 -θ a / 4>a g ,θ i-2 -θ i +3θ a / 4>a g . , Blade i>2, the circumferential distribution angles do not need to be compared.

[0083] Taking blade 3 as an example, the initial position of blade 3 needs not to interfere with the circumferential position of blade 2 and blade 1, and also needs not to interfere with the axial position on the same side of blade 1. The condition for no interference in the circumferential position is: side edge 2 and side edge 3 on the same side: θ 3 -θ 2 >α g ,θ 2 +θ c -θ 3 >α g , top edge 1 and side edge 3 on the same side: θ 3 -θ 1 >α g ,θ 1 +θ a -θ 3 >α g . Converted to θ 1 Relationship: θ 3 -θ 1 -θ a / 4>α g ,θ 1 -θ 3 +3θ a / 4>α g Similarly, we can obtain θ4 With θ 5 The circumferential adjustment range of the blade axial position can be adjusted by adding θ C The calculation was used to solve the problem. The symmetrical arrangement on both sides was considered without interference. The indexable gear milling cutter body was expanded in the circumferential direction. Finally, the blade distribution was obtained as follows Fig. 9 shown.

[0084] The tool presetting and measuring instrument is used to magnify the machining contour curve (blade overlap line) formed by the blade overlap of the designed indexable gear milling cutter by 50 times for precise axial and radial detection. The data points of the detected blade overlap line are analyzed with the theoretical blade overlap line to check the internal and external deviations between the theoretical blade overlap line of the blade overlap and the detected blade overlap line, and the blade line detection deviation diagram is obtained, as shown in Fig.10 As shown, the deviation is controlled within ±0.05mm, and the internal and external tolerance accuracy of the tool when cutting into the workpiece when the spindle rotates is controlled within 0.02mm.

[0085] The design process in S1-S3 above can be optimized with deviations, and is not limited to fitting and lap design.

[0086] Based on a method for designing an indexable milling cutter for machining large-module gears, this embodiment further provides an indexable milling cutter for machining large-module gears, the indexable gear milling cutter comprising a cutter body, an indexable insert and a fastener; the structure of the indexable gear milling cutter is designed using the above-mentioned method for designing an indexable milling cutter for machining large-module gears. The specific process will not be repeated.

[0087] The present embodiment provides a method for designing an indexable milling cutter for processing large-module gears. Compared with the prior art, the method adopts a design method for discretely approximating the gear contour curve by overlapping universal conventional blades. That is, in the roughing or semi-finishing indexable gear milling cutter, multiple universal conventional linear blades are combined together by overlapping blades to approximate the tooth shape. This method greatly improves the efficiency of roughing and semi-finishing of gears, reduces the cost of special customized blades, and has better versatility and good applicability.

[0088] The error of the blade overlap line is controlled through the relevant operations of the 3D design software, that is, through the scanning and measurement operations of the 3D software, the cutting angle of the blade is gradually optimized, so that the allowable error value between the boundary contour line obtained by scanning the axially overlapping blade cutting edges and the blade overlap line is controlled within a range of less than or equal to 0.1mm, thereby eliminating the processing errors of different gears and improving the processing accuracy.

[0089] By analyzing the mutual interference between the blade slot and the chip groove, as well as the relative positional relationship between the blade and the blade slot and the chip groove, the spatial distribution of the blade slot and the chip groove is determined directly by the blade position. This method of spatial position distribution of the blade, blade slot and chip groove can achieve accurate coverage of the entire tool body by each blade edge type, eliminate interference effects, and improve design efficiency. In the existing method of directly opening a suitable blade slot on the tool body, it is necessary to establish multiple reference planes, axes and points when designing in 3D software. It is quite cumbersome to determine the specific moving distance and rotation angle of these reference values, resulting in low efficiency in the design of the blade slot.

[0090] The above is only an embodiment of the present invention. The common sense such as the known specific structure and characteristics in the scheme is not described in detail here. The ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field of the invention before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply the conventional experimental means before that date. The ordinary technicians in the relevant field can improve and implement the scheme in combination with their own abilities under the enlightenment given by this application. Some typical known structures or known methods should not become obstacles for the ordinary technicians in the relevant field to implement this application. It should be pointed out that for the technicians in this field, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent.

Claims

1. A method for designing an indexable milling cutter for machining large-module gears, characterized in that: The method comprises: S1. According to the final tooth profile curve, tooth root machining allowance and tooth side machining allowance of the processed gear, the initial tooth groove profile curve after rough machining or semi-finishing machining is determined as the theoretical blade profile line; then, according to the blade profile error control requirements, the theoretical blade profile line is discretized into a plurality of linear blades composed of indexable inserts by linear blade profile approximation fitting design; S2. Determine the basic parameters of the cutter body, wherein the basic parameters include diameter and thickness; import the fitting blade shape line of the linear blade into the 3D design software to determine the spatial position of the cutter body and the blade, determine the blade position by the tool tip point positioning method, and control the overlap error of the blade shape, and at the same time determine the cutting angle of each blade and correct the blade position so that the cutting edge of the blade is consistent with the overlap blade shape line; S3, determine the number and spatial position of the blades on the cutter body, then determine the distribution position and shape size of the blade slots and chip slots, and check whether there is interference between the blade slots and chip slots, and complete the overall geometric modeling of the indexable gear milling cutter; S4. For the designed indexable gear milling cutter model, detect its overlapping blade line, and analyze the deviation between the detected overlapping blade line and the fitting blade line to optimize the design process in S1-S3.

2. The method for designing an indexable milling cutter for machining large-module gears according to claim 1, characterized in that: In S1, a rectangular coordinate system is established with the center O of the gear as the coordinate origin and the symmetry axis of the tooth groove as the Y axis; Take any point K on the final tooth profile curve, and the OK radius is r k , the angle between OK and the Y axis is the azimuth angle θ k ; According to the coordinate equation x k =r k sinθ k ,y k =r k cosθ k , calculate the theoretical final tooth profile curve of the processed gear; According to the machining allowance of tooth root and tooth side, the equidistant offset curve of the theoretical final tooth profile curve is reversed, and the equidistant offset curve is used as the initial tooth groove profile curve after gear rough machining or semi-finishing, and the initial tooth groove profile curve is used as the theoretical edge line; The initial contour curve of the tooth groove as the theoretical blade shape line is fitted with an approximate straight line to obtain the fitted blade shape line.

3. The method for designing an indexable milling cutter for machining large-module gears according to claim 2, characterized in that: The azimuth angle is calculated by the following formula: Among them, m, z, α, χ, and Δs are the module, number of teeth, pitch circle pressure angle, displacement coefficient, and tooth thickness reduction of the processed gear respectively; r b is the base circle radius calculated according to the basic parameters of the processed gear; inv is the inverse operation.

4. The method for designing an indexable milling cutter for machining large-module gears according to claim 1, characterized in that: In S2, the basic parameters of the cutter body are determined according to the relationship between the final tooth profile curve and the module of the gear being processed; the initial shape model of the axial section of the cutter body is established using 3D design software, and the basic body of the cutter body is obtained thereby; a blade line is formed by overlapping multiple tooth side blades and a tooth top blade, and a fitting blade line is introduced into the axial section of the cutter body, and the intersection of the side blade and the bottom is confirmed as the tip point of the first blade, and the tip points of the remaining blades are taken at a certain interval on the fitting blade line, and the front and rear faces of each blade are determined according to the front and rear angles of each blade, and then the radial and axial positions of each blade are determined according to the front and rear faces, and a 3D solid model of the blade is established; the envelope formed by overlapping each blade is used as the blade overlap line with machining allowance of the milling cutter, and during the overlapping process, the overlapping length of the cutting edge is selected, and the cutting angle of the blade is gradually optimized to optimize the blade overlap line and control the blade overlap error.

5. The method for designing an indexable milling cutter for machining large-module gears according to claim 4, characterized in that: When overlapping, the cutting edges formed by two adjacent blades have a certain overlap in cutting marks during cutting. The overlapping length of the cutting edges is selected according to the ratio of the overlapping length of adjacent cutting marks to the total cutting length of adjacent cutting edges, wherein the ratio is between 30% and 50%; The blade overlap error is such that the allowable error value between the boundary contour line obtained by circumferential scanning of the axially overlapping blade cutting edges and the blade overlap line is controlled within a range of less than or equal to 0.1 mm.

6. The method for designing an indexable milling cutter for machining large-module gears according to claim 1, characterized in that: In S3, the number of blades distributed on the cutter body is determined as: Based on the number of tooth side blades N required for single-sided tooth groove forming, the tooth side blade length l c , calculate the height H of the blade overlap projection in the tooth groove depth direction d ; H according to the overlap of the blade to form the tooth groove edge shape d The relationship with the tooth groove height h satisfies h≤H d ≤h+l c cosα, calculate the number of tooth side blades N, where α is the pitch circle pressure angle of the gear being processed; Based on the wear of the top blade, the number of top blades is set to 1.5 to 3 times the number of side blades; According to the milling cutter diameter D and milling depth a e , calculate the number of milling cutter teeth Z = 12.6 × D / (D + 4a e ); The number of side cutting blades of the milling cutter is 2N×Z.

7. The method for designing an indexable milling cutter for machining large-module gears according to claim 1, characterized in that: In S3, the blades are staggered on the cutter body in a circumferential offset manner through 3D design software, and the distribution is optimized according to the cutting performance; the spatial position of a group of blades is preliminarily determined, and then the spatial positions of the corresponding blade slots and chip grooves are determined, and the blade slot and chip groove models are established. Each blade type covers the entire cutter body in an axially adjacent overlapping and circumferentially adjacent staggered manner, completing the structural design of the cutter body, and cooperating with fasteners to complete the assembly modeling of the milling cutter.

8. The method for designing an indexable milling cutter for machining large-module gears according to claim 7, characterized in that: The chip groove is designed to be in the form of a semi-cylinder. The size of the chip groove is determined according to the chip removal effect, processing efficiency and tool body strength. The chip space size of the insert groove is determined based on 5 times or more of the chip removal amount of material removed by the tool during one rotation. The minimum radius r of the chip groove is calculated accordingly. p , and at the same time make the chip groove peripheral surface tangent to the rake face; Check whether there is interference between each insert slot and the chip slot. If there is interference, eliminate the interference through the preset method, which includes adjusting the offset angle, the number of circular arrays and modifying the chip slot shape.

9. The method for designing an indexable milling cutter for machining large-module gears according to claim 1, characterized in that: In S4, when the circumferential position of the blade interferes, the circumferential adjustment method is used to handle it, including: The blade i is used to replace the top edge and the blade groove and chip groove of the adjacent overlapping side edges on the cutter body, and the initial circumferential position angle is θi, and the corresponding blades are evenly distributed in the circumference; The initial circumferential position of blade i=2 satisfies the condition of no interference with the circumferential position of blade i=1; the initial circumferential position of blade i>2 satisfies the condition of no interference with the circumferential positions of blade i-1 and blade i-2, and also satisfies the condition of no interference with the axial position on the same side of blade i-2, so as to determine the preliminary design position of each blade groove that does not interfere with the chip groove; Among them, the determining factors of the circumferential position non-interference condition include the angle difference causing circumferential interference, the circumferential adjacent angles of the top blade on the same side and the circumferential distribution circular angle occupied by the i-th blade and the corresponding chip groove in the circumferential direction; the circumferential adjacent angles of the side blades on the same side are considered in the circumferential position non-interference condition of the corresponding blade.

10. An indexable milling cutter for machining large-module gears, characterized in that: The indexable gear milling cutter includes and fasteners; the structure of at least the cutter body and the indexable blade of the indexable gear milling cutter is designed using the indexable milling cutter design method for processing large-module gears described in any one of claims 1-9.

Images