Equivalent double-side method machining method for medium-modulus spiral bevel gear

Abstract

The invention relates to the technical field of spiral bevel gear machining, and particularly discloses a medium-modulus spiral bevel gear equivalent double-face method machining method, which is characterized in that on the basis of a spiral bevel gear small-modulus double-double-face method machining parameter calculation method, adjustment machining parameter calculation of a medium-modulus spiral bevel gear machine tool is completed; whether the contact performance is optimized through concave surface and convex surface modification or not is determined according to the result of a spiral bevel gear tooth double-double-face method gear tooth contact analysis program; through machining path planning, the equivalent double-face machining method for the convex face and the concave face of the small gear of the medium-modulus spiral bevel gear is achieved in the one-time clamping process. The method has the beneficial effects that an original small-modulus double-double-face method machining parameter calculation method suitable for the spiral bevel gear is popularized to a medium-modulus equivalent double-face method machining parameter calculation method, the use amount of machine tools is reduced, the problem of poor product consistency caused by multiple times of clamping is solved, meanwhile, the problem of double-face modification of the tooth face is solved, and the machining efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of processing spiral bevel gears, and in particular to an equivalent double-sided processing method for medium-module spiral bevel gears. Background Art

[0002] It is well known that spiral bevel gears are key basic components for realizing intersecting axis motion and power transmission. They have the advantages of high load-bearing capacity, smooth transmission, and low noise. They are widely used in various mechanical equipment such as engineering machinery, automobiles, and machine tools.

[0003] When processing spiral bevel gears, commonly used processing methods are the "five-knife method" and the "double spiral method" (also called the full-process method).

[0004] Specifically, during the five-tool method, the rough cutting and fine cutting of the large wheel are processed by the double-sided method on different machine tools, and the rough cutting and grooving of the small wheel are also processed by the double-sided method. During fine cutting, a single-sided cutter and different processing parameters are used to achieve separate processing of the two surfaces. A complete production line for the processing of spiral bevel gear pairs requires five machine tools and five milling cutters, and five clampings to complete, so it is called the "five-tool method".

[0005] During the two-cut method, the large wheel and the small wheel are processed on different machine tools. A complete production line only needs two machine tools and two milling cutters. The processing of a pair of spiral bevel gear pairs can be completed in two clampings, so it is called "two-cut method". The two-cut method not only realizes the simultaneous completion of rough cutting and fine cutting, but also realizes fine cutting of the small wheel on both sides.

[0006] However, the above processing method in the prior art has the following technical defects:

[0007] The five-knife method has low processing efficiency and requires more equipment. At the same time, multiple installations will increase errors and errors during manual operation, resulting in poor consistency of products in the same batch.

[0008] Compared with the five-knife method, the two-knife method saves processing equipment, reduces the number of clamping times, and improves processing efficiency. At the same time, high-speed dry cutting technology has been promoted and applied in the two-knife method processing of spiral bevel gears. However, when the two-knife method is used for processing, the small wheel adopts the double-sided method, and the two surfaces are processed at one time using the same machine tool to adjust the processing parameters. It is difficult to design and control the contact performance of the two tooth surfaces at the same time, and it also brings the problem of simultaneous correction of both sides.

[0009] To this end, the present invention proposes an equivalent double-sided machining method for medium-module spiral bevel gears. Summary of the invention

[0010] In order to overcome the defects in the prior art and effectively solve the technical problems in the background technology, the present invention provides the following technical solutions:

[0011] A method for machining a medium-module spiral bevel gear by an equivalent double-sided method, comprising the following steps:

[0012] S1: According to the small module double double-sided method for calculating the processing parameters of spiral bevel gears, the calculation of the adjustment processing parameters of the medium module spiral bevel gear machine tool is completed;

[0013] S2: Analyze the machining parameters by the double-sided and double-sided contact analysis program of the spiral bevel gear teeth, and decide whether to optimize the contact performance by modifying the concave and convex surfaces according to the analysis results;

[0014] S3: After the machine tool adjustment and processing parameter optimization are completed, the workpiece and the cutter head are correctly installed on the CNC machine tool and the following motion processing is performed:

[0015] (1) When machining the convex surface of the small wheel, the inner cutter group and the convex surface of the workpiece participate in the work, the bed slide Z is fed to an appropriate position to ensure the small wheel tooth height, the cutter head axis A rotates at an appropriate speed, the horizontal slide X, the vertical slide Y and the workpiece axis C are in a fixed motion relationship, the cutter head moves from the small end of the small wheel to the large end, the convex surface machining is completed, and the workpiece and the tool are out of contact to a safe position;

[0016] (2) Switch from the secondary to the small wheel concave surface processing program, work offset a certain angle to ensure the small wheel tooth thickness, the outer cutter group and the workpiece concave surface work, the horizontal slide X, vertical slide Y and workpiece axis C are in a fixed motion relationship. The cutter head moves from the large end of the small wheel to the small end. This motion is opposite to the motion during the small wheel convex surface processing;

[0017] (3) After completing the machining of one tooth, the tool returns to the initial position, the workpiece axis C is indexed at an angle of 360° / z1 (z1 is the number of teeth on the small wheel), and the convex surface of the next tooth is started, and S3 is repeated until the small wheel is completely machined.

[0018] As a preferred technical solution of the present invention, in S2, the cutter radius and tooth angle of the small wheel cutting cutter are not optimized during the tooth surface optimization process. When cutting the small wheel, a single-sided cutter disc is not used for small wheel fine cutting in the five-knife method, but a double-sided cutter disc is used like the full-process method. However, the cutter disc has a simple structure, and the purpose is to ensure that the concave and convex surface cutting can be completed in one clamping. At the same time, when optimizing the machine tool to adjust the processing parameters, interference between the cutting tool group and the non-cutting surface should be avoided.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] Based on the original double-sided double-sided method suitable for machining arc bevel gears with small modulus, the present invention proposes an equivalent double-sided machining method for the convex and concave surfaces of the small wheel of the medium modulus arc bevel gear by one clamping, so as to reduce the use of machine tools, avoid the problem of poor product consistency caused by multiple clamping, solve the problem of double-sided tooth surface modification, and improve machining efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the machine tool motion model of the present invention.

[0022] Figure 2 It is a schematic diagram of the double-sided processing movement of the present invention.

[0023] Figure 3 It is a schematic diagram of bed calculation according to the present invention.

[0024] Figure 4 It is a schematic diagram of the large wheel convex surface contact area of ​​the original gear tooth contact analysis result of the present invention.

[0025] Figure 5 It is a schematic diagram of the large wheel concave contact area of ​​the original gear tooth contact analysis result of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1:

[0028] See also Figure 1-5 This embodiment provides a technical solution: a medium modulus spiral bevel gear equivalent double-sided processing method, specifically a medium modulus spiral bevel gear equivalent double-sided processing method for automobile drive axle, and the specific method steps are as follows:

[0029] S1: According to the small module double double-sided method of spiral bevel gear machining parameter calculation method, the medium module spiral bevel gear machine tool for automobile drive axle is used to adjust the machining parameter calculation;

[0030] S2: Analyze the machining parameters by the double-sided and double-sided contact analysis program of the spiral bevel gear teeth, and decide whether to optimize the contact performance by modifying the concave and convex surfaces according to the analysis results;

[0031] S3: After the machine tool adjustment and processing parameter optimization are completed, the workpiece and the cutter head are correctly installed on the CNC machine tool and the following motion processing is performed:

[0032] (1) When machining the convex surface of the small wheel, the inner cutter group and the convex surface of the workpiece participate in the work, the bed slide Z is fed to an appropriate position to ensure the small wheel tooth height, the cutter head axis A rotates at an appropriate speed, the horizontal slide X, the vertical slide Y and the workpiece axis C are in a fixed motion relationship, the cutter head moves from the small end of the small wheel to the large end, the convex surface machining is completed, and the workpiece and the tool are out of contact to a safe position;

[0033] (2) Switch from the secondary to the small wheel concave surface processing program, work offset a certain angle to ensure the small wheel tooth thickness, the outer cutter group and the workpiece concave surface work, the horizontal slide X, vertical slide Y and workpiece axis C are in a fixed motion relationship. The cutter head moves from the large end of the small wheel to the small end. This motion is opposite to the motion during the small wheel convex surface processing;

[0034] (3) After completing the machining of one tooth, the tool returns to the initial position, the workpiece axis C is indexed at an angle of 360° / z1 (z1 is the number of teeth on the small wheel), and the convex surface of the next tooth is started, and S3 is repeated until the small wheel is completely machined.

[0035] Furthermore, in S2, the cutter radius and tooth angle of the small wheel cutting cutter are not optimized during the tooth surface optimization process. When cutting the small wheel, the single-sided cutter used in the five-cutting method for small wheel precision cutting is not used, but a double-sided cutter is used as in the full-process method. However, the cutter structure is simple, and the purpose is to ensure that the concave and convex cutting can be completed in one clamping. At the same time, when optimizing the machine tool and adjusting the processing parameters, the interference between the cutting tool group and the non-cutting surface should be avoided.

[0036] In this embodiment, the specific data table and related algorithm formula are as follows:

[0037] 1. The basic parameters of medium modulus spiral bevel gear pairs for automobile drive axles are shown in Table 1, and the processing parameters adjusted by computer tools are shown in Table 2.

[0038] Table 1 Basic parameters of spiral bevel gear pair

[0039]

[0040] The machining parameters for spiral bevel gear cutting include machine tool adjustment parameters, such as radial tool position S r , angular tool position q, rolling ratio R a , Beds X B , Machine installation angle γ m And cutter parameters, such as cutter radius r, tool tooth angle α and offset distance W.

[0041] The cutter radius r and cutter tooth angle α in the tool parameters are selected according to the gear specifications and production conditions, and the offset distance is calculated as follows:

[0042] The machine tool adjusts the processing parameters and the offset distance is calculated at the corrected midpoint cone distance R'. The purpose is to ensure that the correct helix angle can be obtained at the cone distance R' when the cutter parameters are used to ensure that the gear pair can mesh normally. The calculation is as follows:

[0043]

[0044] N is the cutter number of the cutter head, and z0 is the equivalent number.

[0045] tooth

[0046] The calculation of tool error is as follows:

[0047]

[0048] R e is the outer cone distance, h f2 is the large wheel tooth root height. The above data can be calculated based on the basic parameters of the spiral bevel gear.

[0049] The machine tool adjustment processing parameters are calculated as follows:

[0050] First, the bed X B The calculation is explained below. The tooth shape after the tooth root is tilted is as follows: Figure 4 In order to ensure that the tooth depth direction meets the requirements, the bed position should also have a correction amount. The specific correction amount is calculated as follows:

[0051] X Bi =R'tanΔθ fi

[0052] Δθ fi is the root cone inclination.

[0053] Machine installation angle γ m is the root cone angle δ of the corresponding machined gear i , vertical wheel position E m and horizontal wheel position X g Both are 0.

[0054] H i =R'-r i sinβ

[0055] V i =r i cosβ

[0056]

[0057] In the formula, i=1,2, which are the small wheel and the big wheel respectively.

[0058] Table 2 Machine tool adjustment processing parameters

[0059]

[0060] 2. Perform gear tooth contact analysis on the processing parameters to obtain the contact area as follows Figure 4-5 shown.

[0061] This part of the content is an existing mature technology and will not be described in detail here (for specific content, please refer to the published paper "Research on Tooth Contact Analysis (TCA) of Spiral Bevel Gears Based on Double Double-Sided Method", and the results are given directly).

[0062] 3. In order to better improve the contact performance of the spiral bevel gear and improve the processing efficiency at the same time, the method proposed by the present invention is used to complete the flexible and efficient double-sided processing of the medium-modulus spiral bevel gear small wheel for automobile drive axle in one clamping. For the tooth surface modification of the spiral bevel gear, the corresponding machine tool adjustment processing parameters after the tooth surface modification are calculated under the premise of ensuring that the cutter head and the tooth surface do not interfere with each other.

[0063] The specific process of tooth surface modification is as follows:

[0064] First, according to the calculated machine tool adjustment processing parameters, calculate the original tooth surface r2 of the large wheel and the conjugate tooth surface r e and the original tooth surface r1 of the small wheel and the corresponding unit normal vector n1;

[0065] On the conjugate tooth surface of the large wheel r e On the basis of the modified surface, the target tooth surface r of the small wheel is constructed t ;

[0066] Calculate the tooth surface deviation between the target tooth surface of the small wheel and the original tooth surface of the small wheel and express it as

[0067] r=r t -r1

[0068] The relationship between tooth surface deviation and machine tool adjustment processing parameters is established and written as

[0069] r=r t -r1(ψ j )

[0070] Where Ψ j Represents processing parameters, j=1~k.

[0071] Differentiating it gives

[0072]

[0073] Multiply both sides of the equation by the unit normal vector n1 of the original tooth surface of the small wheel, and we can get

[0074]

[0075] because

[0076]

[0077] The unit normal vector n1 is and Vertical, simplified

[0078]

[0079] In the formula, the left side of the equation δr·n1 represents the tooth surface deviation, and the right side of the equation It represents the sensitivity coefficient of tooth surface deviation to small changes of the kth machining parameter.

[0080] Let Δδ m Represents the tooth surface deviation of any tooth surface grid point, then the sensitivity coefficient η corresponding to the jth processing parameter j It can be approximately expressed by difference

[0081] η j =Δδ / Δψ j

[0082] The tooth surface is divided into p×p grid points, uniformly numbered as m, then the tooth surface deviation corresponding to the m grid points can be expressed by the matrix as

[0083]

[0084] In the formula, Δδ m represents the tooth surface deviation at the mth grid point, η km represents the sensitivity coefficient of the tooth surface deviation at the mth grid point caused by the kth machining parameter, ΔΨ k Represents the correction amount of the kkth processing parameter.

[0085] Abbreviated as

[0086] {Δδ i}=[η ij ]{Δψ j}(i=1,2...,m; j=1,2...,k)

[0087] In the formula, {Δδ i} represents the tooth surface deviation of all mesh points on the tooth surface, which refers to the deviation between the original tooth surface of the small wheel and the target tooth surface of the small wheel; [η ij ] represents the tooth surface deviation sensitivity matrix; {Δψ j} represents the correction amount of the basic processing parameters of the machine tool.

[0088] Since the number of basic machining parameters of the machine tool is much smaller than the number of mesh points on the tooth surface, that is, k<<m, the equation is an overdetermined system of equations. This paper uses the least squares method to solve:

[0089] {Δψ j}=([η ij ] T [ηij ]) -1 [η ij ] T {Δδ i}

[0090] Perform TCA based on the calculated processing parameter correction amount. If the contact area and transmission error are not ideal, adjust the correction amount and repeat the above process until the ideal contact area and transmission error are obtained. At the same time, verify that there is no interference when adjusting the processing parameters after the correction.

[0091] According to the tooth surface modification method, the machine tool adjustment processing parameters after the concave and convex surfaces of the small wheel are trimmed are shown in Table 3.

[0092] Table 3 After the machine tool adjustment processing parameters are corrected

[0093] Convex Concave <![CDATA[Radial tool position S r / (mm)]]> 110.65 98.55 Angular tool position q / (°) 65.27172 65.27172 <![CDATA[Vertical wheel position E m / (mm)]]> 7.5 -5 <![CDATA[Bed X B / (mm)]]> 0.96 0.96 <![CDATA[Wheel blank installation angle γ m / (°)]]> 24.42 24.42 <![CDATA[Horizontal wheel position correction value X g / (mm)]]> 0 0 <![CDATA[Roll ratio R a > 3.13 2.13

[0094] 4. Install the workpiece on the processing equipment according to the installation requirements and write the CNC code for processing.

[0095] The first step is to start the cutter shaft A and select the appropriate speed according to the cutting material and cutting amount. The installation angle of the wheel blank is adjusted to the right position (the workpiece box rotary axis B). Depending on the processing equipment, it can be adjusted manually or by the root cone adjustment device. The root cone angle will not be adjusted in the subsequent processing process.

[0096] In the second step, when machining the convex surface of the small wheel, the inner cutter group and the convex surface of the workpiece are involved in the work. The workpiece axis C is set to 0°, which is recorded as the workpiece offset angle. The purpose is to determine the angle of the workpiece axis when machining the concave surface to ensure the tooth thickness of the machined workpiece.

[0097] The third step is to link the horizontal slide X, vertical slide Y, workpiece axis C, and bed slide Z to align the tool tip cutting point with the corrected midpoint of the pitch cone surface, and ensure that the tool tip plane maintains a certain safe distance from the pitch cone plane, and record the bed slide position Z1;

[0098] In the fourth step, the horizontal slide X, vertical slide Y and workpiece axis C move the cutter head from the corrected midpoint of the small wheel to the small end under a fixed motion relationship, and then the bed slide Z is fed to Z2 to ensure the tooth height of the processed workpiece;

[0099] Step 5: The horizontal slide X, vertical slide Y and workpiece axis C move the cutter head from the small end of the small wheel to the large end under a fixed motion relationship, the workpiece and the cutter are out of contact to a safe position, the convex surface processing is completed, and the bed slide moves to Z1;

[0100] Step 6: When machining the concave surface of the small wheel, the outer tool group and the concave surface of the workpiece work. The workpiece axis C is adjusted to -7.7°. The horizontal slide X and the vertical slide Y move the large end of the small wheel, and then the bed slide moves to Z2;

[0101] Step 7: The horizontal slide X, vertical slide Y and workpiece axis C move the cutter head from the large end of the small wheel to the small end under a fixed motion relationship to complete the concave surface processing, and the bed slide moves to Z1;

[0102] Step 8. After completing the processing of one tooth, the workpiece axis C indexing angle increases by 360° / z1 (z1 is the number of teeth on the small wheel). The horizontal slide X and the vertical slide Y move to the small end of the small wheel, and repeat steps 5, 6, and 7. It should be noted that the C-axis angle in step 6 is -7.7°+360° / z1.

[0103] Step 9. Repeat step 8 until the small wheel processing is completed.

[0104] The processed spiral bevel gear small wheel and large wheel are subjected to rolling test at the theoretical installation distance.

[0105] Comparing the original contact area with the contact area after the equivalent double-sided method shaping process, the contact area can be flexibly controlled, and the number of clamping times is also reduced, thereby improving the processing efficiency. The present invention provides a method for efficiently processing medium-module spiral bevel gears for automobile drive axles based on domestic CNC machine tools.

[0106] In addition, the processing method in this embodiment is also applicable to the processing of spiral bevel gears in various mechanical equipment such as engineering machinery, automobiles, and machine tools.

[0107] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

[0108] References:

[0109] [1] Geng Longlong, Deng Xiaozhong, Cao Xuemei. Research on spiral bevel gear tooth contact analysis (TCA) based on double double-sided method [J]. Mechanical Transmission, 2014, 38(06): 34-36.

Claims

1. A method for machining medium modulus spiral bevel gears by an equivalent double-sided method, characterized in that: The following steps are involved: S1: According to the small module double double-sided method for calculating the processing parameters of spiral bevel gears, the calculation of the adjustment processing parameters of the medium module spiral bevel gear machine tool is completed; S2: Analyze the machining parameters by the double-sided and double-sided contact analysis program of the spiral bevel gear teeth, and decide whether to optimize the contact performance by modifying the concave and convex surfaces according to the analysis results; S3: After the machine tool adjustment and processing parameter optimization are completed, the workpiece and the cutter head are correctly installed on the CNC machine tool and the following motion processing is performed: (1) When machining the convex surface of the small wheel, the inner cutter group and the convex surface of the workpiece participate in the work, the bed slide Z is fed to an appropriate position to ensure the small wheel tooth height, the cutter head axis A rotates at an appropriate speed, the horizontal slide X, the vertical slide Y and the workpiece axis C are in a fixed motion relationship, the cutter head moves from the small end of the small wheel to the large end, the convex surface machining is completed, and the workpiece and the tool are out of contact to a safe position; (2) Switch from the secondary to the small wheel concave surface processing program, work offset a certain angle to ensure the small wheel tooth thickness, the outer cutter group and the workpiece concave surface work, the horizontal slide X, vertical slide Y and workpiece axis C are in a fixed motion relationship. The cutter head moves from the large end of the small wheel to the small end. This motion is opposite to the motion during the small wheel convex surface processing; (3) After completing the machining of one tooth, the tool returns to the initial position, the workpiece axis C is indexed at an angle of 360° / z1 (z1 is the number of teeth on the small wheel), and the convex surface of the next tooth is started, and S3 is repeated until the small wheel is completely machined.

2. The method for machining medium modulus spiral bevel gears by equivalent double-sided method according to claim 1, characterized in that: In S2, the cutter radius and tooth angle of the small wheel cutting cutter are not optimized during the tooth surface optimization process. When cutting the small wheel, a single-sided cutter disc is not used for small wheel fine cutting in the five-knife method, but a double-sided cutter disc is used as in the full-process method. However, the cutter disc has a simple structure, and the purpose is to ensure that the concave and convex surface cutting can be completed in one clamping. At the same time, when optimizing the machine tool and adjusting the processing parameters, interference between the cutting tool group and the non-cutting surface should be avoided.

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