A method for hobbing a gear with asymmetric tooth direction modification

Abstract

This invention relates to gear hobbing methods, specifically to a gear hobbing method for asymmetric tooth profile modification. This method addresses the shortcomings of traditional gear hobbing where asymmetric tooth profile modification relies on repeated, cyclical adjustments of machine parameters based on experience. Such adjustments are time-consuming, labor-intensive, and inefficient, leading to low production changeover rates and increased scrap from trial cuts, thus raising production costs. This new asymmetric tooth profile modification method combines helical modification with inverted conical modification, achieving asymmetric tooth profile modification and solving the problem of rapid adjustment for asymmetric tooth profile modification in gear hobbing.

Description

Technical Field

[0001] This invention relates to a gear hobbing method, specifically to a gear hobbing method with asymmetric tooth profile modification. Background Technology

[0002] Gear parts with asymmetrical tooth profiles are currently widely used in the automotive transmission field. They are generally processed using a hobbing process. First, the asymmetrical tooth profile is modified by hobbing, followed by heat treatment. This ensures that the left and right tooth surfaces are ground evenly during the finishing process, preventing the phenomenon of tooth root ridges that reduce gear strength.

[0003] Gear hobbing is a machining process that utilizes a gear hob to perform relative rolling with the gear. It offers relatively high machining accuracy, typically exhibiting small backlash and good tooth profile precision, and can process large batches of gears in a short time. Gear hobbing is commonly used for machining... Figure 1 The same-side inclined spiral shaping or Figure 2 The figure-eight shaped inverted cone profile shown; same-side tilting spiral profile can be achieved by correcting the helix angle. The characteristic is that the left and right tooth directions have the same tilt magnitude, but opposite positive and negative values ​​(actual measured deviation value fHb of the left tooth surface). L Equal to - the actual measured deviation value fHb of the right tooth surface R The reverse cone correction can achieve a figure-eight shaped reverse cone profile, characterized by the same degree of inclination on both the left and right sides of the tooth, with the same positive and negative values ​​(the actual measured deviation value fHb of the left tooth surface). L Equal to the actual measured deviation value fHb of the right tooth surface. R Asymmetric tooth directions are machined using gear hobbing technology, such as... Figure 3 The left-slanted figure-eight shape shown is modified. Figure 4 The left-slanted inverted V-shape shown Figure 5 The right-slanted figure-eight shape shown is modified. Figure 6 The right-sloping inverted V-shape shown in the figure currently lacks a standard processing method for reference in the industry. It can only be achieved by repeatedly adjusting machine tool parameters through experience using a process of "trial cutting - inspection - parameter adjustment - trial cutting again - inspection - parameter adjustment..." This is not only time-consuming and labor-intensive with low production changeover efficiency, but also increases the number of defective trial cuts, leading to increased production costs. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of asymmetric tooth profile modification in gear hobbing, which requires repeated adjustments of machine tool parameters based on experience and multiple cycles of testing. This is not only time-consuming and labor-intensive, resulting in low production changeover efficiency, but also increases the number of defective products and thus production costs. Therefore, this invention provides a gear hobbing method for asymmetric tooth profile modification.

[0005] This invention provides the following technical solution:

[0006] A method for asymmetric tooth profile modification in gear hobbing, characterized by the following steps:

[0007] Step 1: Based on the required tooth profile shape of the asymmetric gear, determine the gear machining parameters for the asymmetric gear. These parameters include the tooth width B and the required tooth deviation value fHb0 on the left tooth surface. L The required tooth direction deviation value for the right tooth surface is fHb0. R ;

[0008] Step 2: Set the inherent tooth direction deviation value fHbe of the left tooth surface. L The inherent tooth deviation value fHbe of the right tooth surface R The initial value is based on the tooth width B and the required tooth deviation value fHb0 on the left tooth surface, obtained from step 1. L The required tooth direction deviation value for the right tooth surface is fHb0. R Calculate the initial helix angle compensation Δβ0 and the initial taper compensation ΔH0;

[0009] Step 3: Based on the gear machining parameters, the initial helix angle compensation Δβ0 and the initial taper compensation ΔH0 from Step 2, perform trial machining using a gear hobbing machine, and measure the modified gear using a gear measuring instrument to obtain the actual detected deviation value fHb of the tooth direction on the left tooth surface. L Actual deviation value fHb of right tooth surface direction R The corrected inherent tooth profile deviation value fHbe of the left tooth surface was calculated. L The corrected inherent tooth profile deviation value fHbe of the right tooth surface. R ′, let fHbe L =fHbe L ′,fHbe R =fHbe R ′;

[0010] Step 4: Based on the tooth width B from Step 1, the required tooth deviation value fHb0 on the left tooth surface. L The required tooth direction deviation value for the right tooth surface is fHb0. R And the inherent tooth profile deviation value fHbe of the left tooth surface in step 3. L The inherent tooth deviation value fHbe of the right tooth surface R Calculate the helix angle compensation Δβ and the taper compensation ΔH;

[0011] Step 5: Based on the gear machining parameters determined in Step 1 and the helix angle compensation Δβ and taper compensation ΔH obtained in Step 4, use a gear hobbing machine to complete the asymmetric tooth profile modification.

[0012] Furthermore, the inherent tooth direction deviation value fHbe of the left tooth surface is set. L The inherent tooth deviation value fHbe of the right tooth surfaceR Since both are 0, the initial helix angle compensation Δβ0 is calculated according to the following formula:

[0013] Δβ0=arc tan(ΔfHb0 / (B*90%))

[0014] ΔfHb0=-(fHb0 L -fHb0 R ) / 2

[0015] Wherein, ΔfHb0 is the initial tooth deviation compensation amount;

[0016] The initial taper compensation ΔH0 is calculated using the following formula:

[0017] ΔH0=(fHb0 L +fHb0 R ) / 2.

[0018] Furthermore, in step 4, the formula for calculating the helix angle compensation Δβ is as follows:

[0019] Δβ=arc tan(ΔfHb / (B*90%))

[0020] ΔfHb=-(fHb0 L -fHb0 R -fHbe L +fHbe R ) / 2

[0021] Where ΔfHb is the tooth deviation compensation amount;

[0022] The formula for calculating the taper compensation ΔH is as follows:

[0023] ΔH=(fHb0 L +fHb0 R -fHbe L -fHbe R ) / 2.

[0024] Furthermore, in step 3, the corrected device inherent tooth orientation deviation value fHbe on the left tooth surface L The calculation formula is as follows:

[0025] fHbe L ′=fHb0 L -fHb L ;

[0026] The corrected device inherent tooth orientation deviation value fHbe on the right tooth surface R The calculation formula is as follows:

[0027] fHbe R ′=fHb0 R-fHb R .

[0028] Furthermore, in step 1, the gear machining parameters also include gear type, normal module, number of teeth, pressure angle, gear outer diameter, total tooth height, workpiece height, Brinell hardness, accuracy grade, tapered reference width, camber amount, camber reference width, and camber high point position.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] (1) The present invention provides a hobbing method for asymmetric tooth profile modification. By combining spiral modification with inverted cone modification, asymmetric tooth profile modification is achieved, which solves the problem of rapid debugging of asymmetric tooth profile modification in hobbing. It can improve the speed of on-site production changeover, reduce debugging waste, reduce costs, and improve production efficiency.

[0031] (2) The hobbing method of asymmetric tooth profile modification of the present invention is a pre-processing of asymmetric tooth profile modification for hot grinding, thereby ensuring uniform removal of the left and right sides during the asymmetric tooth profile modification grinding process, avoiding the tooth root rise and reducing the gear strength, having higher process stability, and higher processing efficiency, and is suitable for high-volume production needs. Attached Figure Description

[0032] Figure 1 A schematic diagram of the tooth direction of a helical gear with an inclined profile on the same side;

[0033] Figure 2 A schematic diagram of the tooth direction of a figure-eight shaped inverted bevel gear;

[0034] Figure 3 This is a schematic diagram of the tooth direction of a left-slanted, figure-eight modified gear;

[0035] Figure 4 A schematic diagram of the tooth direction of a left-sloping, figure-eight modified gear;

[0036] Figure 5 This is a schematic diagram of the tooth direction of a right-angled, figure-eight modified gear;

[0037] Figure 6 A schematic diagram of the tooth direction of a right-sloping, inverted V-shaped modified gear;

[0038] Figure 7 This is a schematic diagram of the axial shaping path for a hob without shaping.

[0039] Figure 8 A schematic diagram of the axial shaping path of a hob with a drum-shaped shaping feature;

[0040] Figure 9 This is a schematic diagram illustrating the principle of a hobbing method for asymmetric tooth profile modification according to the present invention. Detailed Implementation

[0041] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0042] Common hob axial profile modification paths are Figure 7 The unmodified or Figure 8 The drum-shaped modification shown is an asymmetric tooth-direction modification. Because the drum-shaped modification adds a taper modification, an inclined tool path needs to be added to the hob axial modification path.

[0043] This invention proposes a hobbing method for asymmetric tooth profile modification, such as... Figure 9 As shown, spiral shaping and inverted cone shaping are combined to achieve asymmetric tooth profile shaping;

[0044] The asymmetric tooth profile modification hobbing method includes the following steps:

[0045] Step 1: Based on the required tooth profile shape of the asymmetric gear, determine the gear machining parameters for the asymmetric gear. These parameters include gear type, normal module, number of teeth, pressure angle, gear outer diameter, total tooth height, workpiece height, Brinell hardness, precision grade, tapered reference width, crowning amount, crowning reference width, crowning high point position, tooth width B, and the required tooth deviation value fHb0 on the left tooth surface. L The required tooth direction deviation value for the right tooth surface is fHb0. R ;

[0046] Step 2: Set the inherent tooth direction deviation value fHbe of the left tooth surface. L The inherent tooth deviation value fHbe of the right tooth surface R Since both are 0, the initial helix angle compensation Δβ0 is calculated according to the following formula:

[0047] Δβ0=arc tan(ΔfHb0 / (B*90%))

[0048] ΔfHb0=-(fHb0 L -fHb0 R ) / 2

[0049] Wherein, ΔfHb0 is the initial tooth deviation compensation amount;

[0050] The initial taper compensation ΔH0 is calculated using the following formula:

[0051] ΔH0=(fHb0 L +fHb0 R ) / 2;

[0052] Step 3: Based on the gear machining parameters from Step 1, and the helix angle compensation Δβ and taper compensation ΔH from Step 2, perform trial machining using a gear hobbing machine, and measure the modified gear using a gear measuring instrument to obtain the actual detected deviation value fHb of the tooth direction on the left tooth surface. L Actual deviation value fHb of right tooth surface direction R The corrected inherent tooth profile deviation value fHbe of the left tooth surface is calculated according to the following formula. L The corrected inherent tooth profile deviation value fHbe of the right tooth surface. R ′:

[0053] fHbe L ′=fHb0 L -fHb L ,

[0054] fHbe R ′=fHb0 R -fHb R ;

[0055] Let fHbe L =fHbe L ′,fHbe R =fHbe R ′;

[0056] Step 4: Based on the tooth width B from Step 1, the required tooth deviation value fHb0 on the left tooth surface. L The required tooth direction deviation value for the right tooth surface is fHb0. R And the inherent tooth orientation deviation value fHbe of the left tooth surface in step 3. L The inherent tooth deviation value fHbe of the right tooth surface R The helix angle compensation Δβ and the taper compensation ΔH are calculated according to the following formula:

[0057] Δβ=arc tan(ΔfHb / (B*90%)),

[0058] ΔfHb=-(fHb0 L -fHb0 R -fHbe L +fHbe R ) / 2,

[0059] ΔH=(fHb0 L +fHb0 R -fHbe L -fHbe R ) / 2;

[0060] Where ΔfHb is the tooth deviation compensation amount;

[0061] Step 5: Based on the gear machining parameters from Step 1, the helix angle compensation Δβ from Step 4, and the taper compensation ΔH, use a gear hobbing machine to complete the asymmetric tooth profile modification.

[0062] The specific gear machining parameters used in step 6 of this embodiment are shown in Table 1.

[0063] Table 1

[0064]

[0065]

Claims

1. A method for asymmetric tooth profile modification in gear hobbing, characterized in that, Includes the following steps: Step 1: Based on the required tooth profile shape of the asymmetric gear, determine the gear machining parameters for the asymmetric gear. These parameters include the tooth width B and the required tooth deviation value fHb0 on the left tooth surface. L The required tooth direction deviation value for the right tooth surface is fHb0. R ; Step 2: Set the inherent tooth direction deviation value fHbe of the left tooth surface. L The inherent tooth deviation value fHbe of the right tooth surface R The initial values ​​are all 0. Based on the tooth width B and the required tooth deviation value fHb0 on the left tooth surface from step 1, L The required tooth direction deviation value for the right tooth surface is fHb0. R The initial helix angle compensation Δβ0 is calculated according to the following formula: △β0=arctan(△fHb0 / (B*90%)) △fHb0=-(fHb0 L -fHb0 R ) / 2 Where △fHb0 is the initial tooth deviation compensation amount; Calculate the initial taper compensation ΔH0 using the following formula: △H0=(fHb0 L +fHb0 R ) / 2; Step 3: Based on the gear machining parameters, the initial helix angle compensation △β0 and the initial taper compensation △H0 from Step 2, perform trial machining using a gear hobbing machine, and measure the modified gear using a gear measuring instrument to obtain the actual detected deviation value fHb of the tooth direction on the left tooth surface. L Actual deviation value fHb of right tooth surface direction R The corrected inherent tooth profile deviation value fHbe of the left tooth surface was calculated. L The corrected inherent tooth profile deviation value fHbe of the right tooth surface. R ′; The corrected device inherent tooth orientation deviation value fHbe on the left tooth surface L The calculation formula is as follows: fHbe L ′=fHb0 L -fHb L ; The corrected device inherent tooth orientation deviation value fHbe on the right tooth surface R The calculation formula is as follows: fHbe R ′=fHb0 R -fHb R ; Let fHbe L =fHbe L ′,fHbe R =fHbe R ′; Step 4: Based on the tooth width B from Step 1, the required tooth deviation value fHb0 on the left tooth surface. L The required tooth direction deviation value for the right tooth surface is fHb0. R And the inherent tooth profile deviation value fHbe of the left tooth surface in step 3. L The inherent tooth deviation value fHbe of the right tooth surface R Calculate the helix angle compensation Δβ and the taper compensation ΔH; Step 5: Based on the gear machining parameters determined in Step 1 and the helix angle compensation △β and taper compensation △H obtained in Step 4, the asymmetric tooth profile modification is completed using a gear hobbing machine.

2. The asymmetric tooth profile modification hobbing method according to claim 1, characterized in that, In step 4, the formula for calculating the helix angle compensation Δβ is as follows: △β=arctan(△fHb / (B*90%)) △fHb=-(fHb0 L -fHb0 R -fHbe L +fHbe R ) / 2 Where △fHb is the tooth deviation compensation amount; The formula for calculating the taper compensation ΔH is as follows: △H=(fHb0 L +fHb0 R -fHbe L -fHbe R ) / 2。 3. A hobbing method for asymmetric tooth profile modification according to claim 1 or 2, characterized in that, In step 1, the gear machining parameters also include gear type, normal module, number of teeth, pressure angle, gear outer diameter, total tooth height, workpiece height, Brinell hardness, accuracy grade, tapered reference width, camber amount, camber reference width, and camber high point position.

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