Method for controlling quenching deformation of internal spline of small and medium-sized gear by cyaniding

Abstract

The present application belongs to the technical field of metal heat treatment, and discloses a method for controlling deformation of small and medium-sized gear inner spline after cyanide quenching. For small and medium-sized gear inner spline parts with a diameter-thickness ratio of 10:1 or more, the deformation amplitude of the inner spline after quenching is improved by optimizing the structure of the variable cross-section position in the axial and radial dimensions of the gear, sequentially horizontally turning the gear according to the high-temperature heat treatment process, using quenching mandrel / teeth top circle diameter size compensation, strictly controlling the quenching transfer time of the parts, and appropriately increasing the quenching oil temperature. The effective combination of the above process measures significantly improves the size tolerance, taper and roundness tolerance and other shape tolerances of small and medium-sized gear inner spline parts after cyanide quenching.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal heat treatment, and particularly relates to a cyanide quenching deformation control method for small and medium-sized gear inner spline. BACKGROUND

[0002] There is a kind of gear inner spline component in the aviation power transmission system. Due to the influence of weight reduction, the structure and function are integrated, the structure and function are highly integrated, the effective wall thickness of the part is thin, the diameter-thickness ratio is usually greater than or equal to 10:1, there are many variable cross-section positions, and the overall rigidity of the part is weak.

[0003] The inner spline of such a part is usually less than or equal to 35 mm in diameter. After experiencing multiple high-temperature heat treatment processes, the quenching deformation is seriously out of tolerance. Due to the small diameter of the inner spline tooth top circle, the roundness and taper out of tolerance caused by quenching deformation cannot be restored to the geometric and form tolerance through grinding in the subsequent machining process.

[0004] At present, for such small and medium-sized gear inner spline parts, after carburizing the tooth profile and cyaniding the inner spline, the product deformation is seriously out of tolerance in the quenching process. The deformation data after quenching is irregular, and due to the small size of the inner spline tooth top circle, the inner spline tooth top circle diameter, the tooth profile taper and the roundness cannot be restored through subsequent grinding. SUMMARY

[0005] The purpose of the application is to provide a cyanide quenching deformation control method for small and medium-sized gear inner spline, which improves the deformation control ability of the tooth profile carburizing + inner spline cyaniding for small and medium-sized gear inner spline parts with a diameter-thickness ratio greater than or equal to 10:1.

[0006] The application is implemented by adopting the following technical solutions.

[0007] A cyanide quenching deformation control method for small and medium-sized gear inner spline is used for small and medium-sized gear inner spline parts with a diameter-thickness ratio greater than or equal to 10:1, and the method comprises the following steps:

[0008] S1, structure optimization is adopted for the axial and radial variable cross-section position regions of the gear inner spline part;

[0009] S2, during carburizing, inner spline cyaniding and overall quenching of the gear inner spline part, horizontal overturning is sequentially performed;

[0010] S3, after quenching of the gear inner spline part, the inner spline tooth top circle size of the gear inner spline part is compensated.

[0011] Further, S1 specifically comprises:

[0012] The variable cross-section position of the gear inner spline part is optimized, and the axial non-carburizing variable cross-section position region is flattened.

[0013] The radial variable cross-section part of the gear inner spline type part is transitioned by a lead circle or an inclined angle.

[0014] Further, S2 is specifically:

[0015] The gear inner spline type part is placed into a carburizing furnace, and the tooth surface of the gear inner spline type part is carburized; before carburizing, one side of the gear inner spline type part is marked, and the side with the mark is placed horizontally upwards;

[0016] After the tooth surface of the gear inner spline type part is carburized and air-cooled, the gear inner spline type part is taken out;

[0017] The carburized gear inner spline type part is placed into a cyaniding furnace, and the inner spline part of the gear inner spline type part is cyanided; the side with the mark is placed horizontally downwards; after cyaniding, the gear inner spline type part is air-cooled and taken out of the furnace, and is high-temperature tempered;

[0018] After the gear inner spline type part is tempered, the side with the mark is placed horizontally upwards before quenching and heating.

[0019] Further, S3 is specifically:

[0020] When the inner spline tooth top circle of the gear inner spline type part shrinks after quenching, a quenching mandrel is used to prevent the shrinkage;

[0021] When the inner spline tooth top circle of the gear inner spline type part expands after quenching, according to the expansion size, reverse size compensation is performed in the machining process.

[0022] Further, the outer diameter of the quenching mandrel is the middle value of the process dimensional tolerance.

[0023] Further, during quenching, the quenching transfer time of the gear inner spline type part is ≤7s.

[0024] Further, according to the material properties of the gear inner spline type part, the quenching oil temperature is reduced by (10-30) °C based on the normal quenching oil temperature of the material.

[0025] Further, after the gear inner spline type part is quenched, ice cooling treatment and low-temperature tempering are performed.

[0026] The technical effect of the present application is that the small and medium-sized gear inner spline cyanide quenching deformation control method optimizes the structure in two dimensions of the axial and radial variable cross-section position area, respectively, and the gear is carburized, the inner spline is cyanided, and the whole part is quenched, and the gear is turned horizontally in turn, and after quenching, the inner spline roundness and taper are greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The schematic diagram of the small and medium-sized gear structure with the internal spline structure provided by the embodiment of the present application is shown in the figure.

[0028] Figure 2 The schematic diagram of the internal spline structure after the axial and radial optimization provided by the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings.

[0030] Embodiment 1

[0031] The embodiment of the present application provides a small and medium-sized gear internal spline cyanide quenching deformation control method, which is used for the small and medium-sized gear internal spline parts with a diameter-thickness ratio of greater than or equal to 10:1, and improves the deformation control capability of the tooth profile carburizing + internal spline cyanide.

[0032] Firstly, the variable cross-section position of the gear internal spline part is optimized, the axial non-carburizing variable cross-section position area is flattened, and the number of axial variable cross-section position areas is reduced.

[0033] When the variable cross-section size difference in the radial direction is large, a lead circle transition or an inclined angle transition is adopted.

[0034] The part is placed in a carburizing furnace, and the tooth profile is carburized. Before carburizing, the gear internal spline part is marked, and the side with the mark is placed horizontally upwards.

[0035] After the tooth profile carburizing is completed and air cooling is completed, the part is taken out.

[0036] After the carburized part is placed in a cyanide furnace, the internal spline part of the part is cyanide treated, and the side with the mark is placed horizontally downwards. After cyanide, the part is air cooled and taken out of the furnace, and high-temperature tempering is performed.

[0037] After the part is tempered and before quenching, the side with the mark is placed horizontally upwards, and quenching heating is performed.

[0038] After quenching, when the internal spline tooth tip circle shrinks, a quenching mandrel can be adopted to prevent shrinkage. The outer diameter of the quenching mandrel is taken as the middle value of the process dimensional tolerance.

[0039] After quenching, when the internal spline tooth tip circle expands, according to the expansion size, reverse size compensation is performed in the machining process.

[0040] During quenching, the quenching transfer time of the part is less than or equal to 7s.

[0041] According to the material properties of the part, the selected quenching oil temperature is decreased by (10-30)℃ based on the normal quenching oil temperature of the material.

[0042] After quenching, ice cooling and low temperature tempering are carried out.

[0043] Example 2

[0044] The small and medium-sized gear with the inner spline structure made of 9310 has an inner spline tooth tip circle diameter of φ(25.0±0.02)mm, and the inner spline length is 5.80mm, as shown in the following figure. Figure 1

[0045] After carburizing the gear tooth profile at 900℃, cyaniding the inner spline at 840℃, quenching the whole part at 840℃, ice cooling at -70℃ and tempering at 150℃, the requirements are as follows: the inner spline tooth tip circle diameter is φ(25.0±0.03)mm, the roundness and taper deformation is less than or equal to 0.03mm, and the actual working condition is that the inner spline tooth tip circle diameter is φ(24.94-25.01)mm, and the roundness and taper deformation is greater than or equal to 0.05mm, and after quenching, the inner spline presents a "waist drum type" deformation.

[0046] Firstly, the variable cross-section size positions of the inner spline are evaluated in the axial direction, and the variable cross-section size positions in the axial direction are optimized, as shown in the following figure 1, 2, 3, 4, 5, 6, 7, 8. Figure 2 These variable cross-section positions are respectively consistent with the outer shaft diameter and the inner shaft diameter size.

[0047] In the radial direction, the positions at 9, 10, 11 and 12 are transitioned by a fillet with a diameter of 6mm, and the positions at 13, 14, 15 and 16 are replaced by the original variable cross-section.

[0048] When the gear tooth profile is carburized, the *** mark surface faces upward. After the carburizing is completed, the part is taken out of the furnace after air cooling.

[0049] When the gear inner spline is cyanided, the *** mark surface faces downward. After the cyaniding is completed, the part is taken out of the furnace after air cooling.

[0050] When the whole part is quenched, the *** mark surface faces upward. After the quenching is completed, ice cooling and low temperature tempering are carried out.

[0051] According to the size shrinkage characteristics of the inner spline after quenching, a quenching mandrel with an outer diameter of φ25.00mm is used.

[0052] Since the material is 9310 steel, the quenching oil temperature is set to 60℃.

[0053] After the optimization of the axial and radial dimensions, the tooth end surface is turned over in sequence during the carburizing, cyaniding and quenching processes, combined with the quenching tooling and the quenching oil temperature, the inner spline tooth tip circle size of the part after quenching is φ(24.98-25.00)mm, and the taper and roundness are both less than or equal to 0.02mm, which meets the requirements between processes.

[0054] ​The technical effect of the application is that the method for controlling the deformation of the medium and small size gear inner spline cyanation quenching, respectively, for the axial and radial variable cross-section position area two dimensions to take structure optimization, gear carburizing, inner spline cyanation and part overall quenching, in turn, horizontal overturning, after quenching, the inner spline roundness and taper are greatly improved.

Claims

1. A method for controlling quenching distortion of cyaniding of small and medium-sized gear inner spline, which is used for small and medium-sized gear inner spline parts with a diameter-thickness ratio of ≥10:1, characterized in that, The method comprises: S1, adopting structural optimization on axial and radial variable cross-section position regions of the gear inner spline part; S1 is specifically: performing process optimization on the variable cross-section position of the gear inner spline part, performing flattening treatment on the axial non-carburizing variable cross-section position region, and adopting lead circle transition or bevel transition on the radial direction variable cross-section part of the gear inner spline part; S2, sequentially performing horizontal overturning during carburizing, inner spline cyaniding and overall quenching of the gear inner spline part; S3, after quenching of the gear inner spline part, compensating the inner spline tooth top circle size of the gear inner spline part; S3 is specifically: after quenching of the gear inner spline part, when the inner spline tooth top circle of the gear inner spline part shrinks, adopting a quenching mandrel to prevent shrinkage; after quenching of the gear inner spline part, when the inner spline tooth top circle of the gear inner spline part expands, according to the expansion size, reverse size compensation is performed in the machining process.

2. The method according to claim 1, wherein S2 is specifically: The gear inner spline part is placed in a carburizing furnace, the tooth profile of the gear inner spline part is carburized, one side of the gear inner spline part is marked before carburizing, and the side with the mark is placed horizontally upwards; After the tooth profile of the gear inner spline part is carburized and air-cooled, the gear inner spline part is taken out; The carburized gear inner spline part is placed in a cyanide furnace, the inner spline part of the gear inner spline part is cyanided, and the side with the mark is placed horizontally downwards; after cyaniding, the gear inner spline part is air-cooled and taken out of the furnace, and high-temperature tempering is performed; After tempering of the gear inner spline part, the side with the mark is placed horizontally upwards before quenching, and quenching is performed.

3. The method according to claim 1, wherein The outer diameter of the quenching mandrel is the middle value of the dimensional tolerance between processes.

4. The method according to claim 1, wherein During quenching, the quenching transfer time of the gear inner spline part is less than or equal to 7s.

5. The method according to claim 4, wherein According to the material properties of the gear inner spline part, the quenching oil temperature is decreased by (10-30) °C based on the normal quenching oil temperature of the material.

6. The method according to claim 1, wherein After quenching of the gear inner spline part, ice cooling treatment and low-temperature tempering are performed.

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