Variable-pressure-angle variable-modulus tooth profile machining process

Abstract

The invention provides a variable-pressure-angle variable-modulus tooth profile machining process method. The variable-pressure-angle variable-modulus tooth profile machining process method is characterized by comprising the steps that A, raw materials are forged; b, the forged blank is subjected to semi-finish turning, scribing and drilling; c, a transition tooth profile is designed, and gear hobbing is conducted according to the gear hobbing technology requirement; d, rough gear grinding is conducted on the workpiece on a numerical control gear grinding machine, it is guaranteed that the tooth surface allowance is uniform, and the extension length meets the design requirement; e, the workpiece is subjected to carburizing and quenching heat treatment, and tooth surface hardness and hardened layer depth are guaranteed; f, the gear subjected to heat treatment is subjected to finish machining; g, gear grinding machining; h, magnetic powder inspection detection is conducted on the ground tooth part; i, finally carrying out pickling detection; and J, final inspection. The carburized and quenched gear of the wind power gear box can be machined without special hob machining.

Description

Technical Field

[0001] The invention relates to the field of carburizing and quenching gear processing for wind power gear boxes, and in particular to a variable pressure angle and variable modulus tooth profile processing method. Background Art

[0002] The processing flow of carburized and quenched gears in wind turbine gearboxes is generally: gear hobbing (grinding and root digging) → carburizing and quenching → gear grinding. In order to avoid grinding the tooth root after carburizing and quenching heat treatment, there is no grinding step at the tooth root transition. The gear hobbing process needs to use a special hob to partially dig the root of the tooth root transition curve and meet the design requirements for the tooth root arc radius and extension. However, for the development of new products or prototype trial production, there is often a situation where there is no ready-made hob.

[0003] Especially in the field of wind power aftermarket processing and maintenance, it is often the case that only some gears of the entire gearbox need to be replaced. For the processing of such single-piece small-batch gears, the procurement and customization cycle of the hob used for gear hobbing is long, and the processing cost allocated to a single gear is high, which causes great problems in production. It is often the case that a gearbox is missing only one gear and cannot be assembled.

[0004] Normally, the hob is selected to have the normal modulus and normal pressure angle of the hob equal to the normal modulus and normal pressure angle of the workpiece. If they are not equal, a special hob needs to be customized. Under the premise of not delaying production and ensuring the quality of the gear, consider using a variable pressure angle and variable modulus tooth profile processing method. The specific solution is to pre-process the tooth profile before carburizing, quenching and hardening the gear: hobbing + rough grinding, to solve the problem of not having a special hob for processing. The tooth profile processing process is: hobbing → rough grinding → carburizing, quenching → grinding. Summary of the invention

[0005] The present invention provides a variable pressure angle and variable modulus tooth profile machining process method, the purpose of which is to solve the shortcomings of the prior art and to machine the carburized and quenched gears of a wind power gear box without the need for special hob machining.

[0006] The technical solution adopted by the present invention to solve its technical problem is:

[0007] A variable pressure angle and variable modulus tooth profile machining process method, characterized by:

[0008] The steps include:

[0009] A: Forging of raw materials;

[0010] B: Semi-finishing turning, marking and drilling of forged blanks;

[0011] C: Design the transition tooth profile and perform gear hobbing according to the gear hobbing process requirements;

[0012] D: Roughly grind the workpiece on a CNC gear grinding machine to ensure that the tooth surface allowance is uniform and the length meets the design requirements;

[0013] E: The workpiece is subjected to carburizing and quenching heat treatment to ensure the hardness of the tooth surface and the depth of the hardened layer;

[0014] F: Finishing of the gears after heat treatment;

[0015] G: Gear grinding;

[0016] H: Conduct magnetic particle inspection on the teeth after grinding;

[0017] I: Finally, pickling test is carried out.

[0018] J: Final inspection.

[0019] Wherein step C is:

[0020] Roughly select the hob; adjust the transition tooth profile; verify the length; determine whether the length verification is satisfied, if not, re-roughly select the hob, if yes, verify the root digging amount; determine whether the root digging amount is satisfied, if not, adjust the displacement coefficient and adjust the transition tooth profile, if yes, output the parameters.

[0021] The present invention is beneficial in that:

[0022] The invention meets the requirements of single-piece small-batch production, solves the problem of lack of special hobs for heat-treated hardened gears, saves costs, and takes into account quality, efficiency and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0024] Figure 1 It is a schematic diagram of the tooth profile machining process;

[0025] Figure 2 It is the process of designing and verifying the parameters of transition tooth profile. DETAILED DESCRIPTION

[0026] In order to more clearly illustrate the technical solution of the present invention, the following will briefly introduce the drawings required for the description. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without creative work. In order to facilitate the understanding of the present invention, the present invention is described in more detail below in combination with the drawings and specific embodiments.

[0027] It should be noted that when an element is described as being "fixed to" another element, it may be directly on the other element, or one or more centered elements may exist therebetween. When an element is described as being "connected" to another element, it may be directly connected to the other element, or one or more centered elements may exist therebetween. The terms "upper", "lower", "inner", "outer", "bottom", etc. used in this specification indicate an orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc., etc. are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] The present invention considers using a variable pressure angle and variable modulus tooth profile processing method without delaying production and ensuring the quality of the gear. The specific solution is to pre-process the tooth profile before carburizing, quenching and hardening the gear: hobbing + rough grinding, to solve the problem of replacing the processing without a special hob. The tooth profile processing process is: hobbing → rough grinding → carburizing, quenching → grinding.

[0029] First, let's explain the pre-processing requirements of the tooth profile before hardening:

[0030] 1) The gear should have a certain amount of undercut at the root of the tooth;

[0031] 2) The grinding allowance of the hot-grinded teeth should be appropriate and uniform;

[0032] 3) The involute length of the gear after grinding meets the requirements;

[0033] 4) The root of the gear tooth is required to have a larger radius of curvature before grinding.

[0034] In order to meet the above-mentioned tooth profile pre-processing requirements before heat treatment, this solution adopts the gear hobbing + rough grinding method.

[0035] Here’s how it works Figure 1 As shown:

[0036] Figure 1 From left to right are the three states of processing:

[0037] a) Gear hobbing state: a transitional tooth profile is achieved through gear hobbing, which can include the tooth profile required for pre-heating. The root transition curve part has a root digging, and the involute tooth surface part has uneven margins;

[0038] b) Rough grinding state: The tooth profile required by pre-heating pre-processing is produced by rough grinding. Only the involute tooth surface is ground, and the tooth root transition curve is not ground;

[0039] c): Grinding state: Grinding is performed on the tooth profile after rough grinding.

[0040] Specific implementation process of the plan:

[0041] The steps include:

[0042] A: Forging of raw materials according to forging ratio and other requirements;

[0043] B: Perform semi-finishing turning, marking, drilling and other processes on the forged blank;

[0044] C: According to Figure 2 The process uses a hob, designs a transition tooth profile, and performs gear hobbing according to the gear hobbing process requirements;

[0045] That is:

[0046] Roughly select the hob; adjust the transition tooth profile; verify the length; determine whether the length verification is satisfied, if not, re-roughly select the hob, if yes, verify the root digging amount; determine whether the root digging amount is satisfied, if not, adjust the displacement coefficient and adjust the transition tooth profile, if yes, output the parameters.

[0047] D: Roughly grind the workpiece on a CNC gear grinding machine to ensure that the tooth surface allowance is uniform and the length meets the design requirements;

[0048] E: The workpiece is subjected to carburizing and quenching heat treatment to ensure the hardness of the tooth surface and the depth of the hardened layer;

[0049] F: Finishing the heat-treated gears, including finishing turning, grinding the outer circle, keyway processing, etc.

[0050] G: Gear grinding: because the root cutting of the transition curve by gear hobbing will not grind to the transition curve, the residual stress at the root of the tooth is still tensile stress, which is beneficial to improve the bending fatigue strength of the tooth root;

[0051] H: Conduct magnetic particle inspection on the teeth after grinding;

[0052] 1: carry out pickling detection;

[0053] J: The final inspection is passed and the workpiece processing process is completed.

[0054] Existing technology patents include: Chinese patent: CN201210380607.8, a gear cutting device and a gear cutting method for an involute gear tooth profile

[0055] Compared with the above-mentioned prior art patents, this patent has the following advantages:

[0056] The rough tooth grinding of the scheme of CN201210380607.8 includes tooth surface grinding and tooth root grinding, while the scheme of this patent only grinds the tooth surface without grinding the tooth root; tooth root grinding will increase the wear of the grinding wheel, increase the power loss of the equipment, and increase the processing cost; the rough tooth grinding of the scheme of this patent only grinds the tooth surface without grinding the tooth root, which can avoid the above problems, and also reduce the grinding time, reduce the cost and improve the processing efficiency;

[0057] The solution of CN201210380607.8 has high requirements for tooth root grinding calculation, and the verification trial and error cost is high. In addition, the formation principles of transition curves of different brands of gear grinding equipment are inconsistent, and the simulation calculation of the transition curve cannot be verified;

[0058] The solution of CN201210380607.8 requires that in the rough grinding of teeth, the tooth profile angle of the grinding wheel for the second grinding must be 4°-8° smaller than that of the first grinding, and the requirement that "if it is less than 4°, bosses are likely to appear when the deformation during heat treatment is large". This requirement places very high demands on the heat treatment of the previous process, and will cause great problems when the parts are greatly deformed; the requirement that "if it is greater than 8°, the grinding wheel may lack rigidity", this requirement may cause the grinding wheel to be unable to process.

[0059] This patent overcomes the above-mentioned shortcomings of the prior art.

[0060] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the embodiments can be referred to each other. The above description of the disclosed embodiments enables professionals and technicians in this field to implement or use the present invention. Various modifications to these embodiments will be obvious to professionals and technicians in this field, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown in this article, but will comply with the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A variable pressure angle and variable modulus tooth profile machining process, characterized in that: The steps include: A: Forging of raw materials; B: Semi-finishing turning, marking and drilling of forged blanks; C: Design the transition tooth profile and perform gear hobbing according to the gear hobbing process requirements; D: Roughly grind the workpiece on a CNC gear grinding machine to ensure that the tooth surface allowance is uniform and the length meets the design requirements; E: The workpiece is subjected to carburizing and quenching heat treatment to ensure the hardness of the tooth surface and the depth of the hardened layer; F: Finishing of the gears after heat treatment; G: Gear grinding; H: Conduct magnetic particle inspection on the teeth after grinding; 1: carry out pickling detection; J: Final inspection.

2. A variable pressure angle and variable modulus tooth profile machining process as claimed in claim 1, characterized in that: Wherein step C is: Roughly select the hob; adjust the transition tooth profile; verify the length; determine whether the length verification is satisfied, if not, re-roughly select the hob, if yes, verify the root digging amount; determine whether the root digging amount is satisfied, if not, adjust the displacement coefficient and adjust the transition tooth profile, if yes, output the parameters.

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