Sun gear clamping device for reducing heat treatment deformation of internal spline

Abstract

The utility model discloses a sun gear clamping device for reducing thermal treatment deformation of an internal spline. The sun gear clamping device comprises a bearing chassis, the carburizing, quenching and tempering clamps are arranged in multiple layers and are stacked on the bearing base plate in parallel, vertical columns are vertically arranged on the upper surfaces of the carburizing, quenching and tempering clamps, and the vertical columns are distributed in a matrix shape; the stand column is sleeved with the compensation core rod with a gap, the compensation core rod is sleeved with the sun gear with a gap, an annular groove is formed in the outer side face of the compensation core rod, the width of the annular groove is 1 / 3 of the thickness of the sun gear arranged on the annular groove in a sleeved mode, and the annular groove corresponds to the middle position of the sun gear arranged on the annular groove in a sleeved mode. In the heat treatment process, the problem that in the heat treatment production process of an existing thin-wall hollow circular ring structure sun gear with outer teeth and inner splines, the deformation reject ratio of the inner splines is high is solved through the method matched with the device.

Description

TECHNICAL FIELD

[0001] The utility model relates to heat treatment technical field especially a sun gear clamping device of reducing internal spline heat treatment deformation. BACKGROUND

[0002] As a core component of planetary gear transmission system, the sun gear plays a crucial role. It is not only the power output wheel in the system, but also through the combination of the central shaft and multiple gears, it realizes efficient power transmission. In structure, the sun gear usually has more teeth than other gears to ensure the stability and efficiency of transmission. Its working principle is based on the precise meshing between gears, through driving other gears such as planetary gears, to complete the output and conversion of power. In terms of application, the sun gear is almost ubiquitous in all fields that require precise transmission. Whether it is the power transmission of vehicles, the propulsion system of ships, or the complex mechanical structure of spacecraft, even the automatic control of generators, wind turbines and industrial machinery, the sun gear plays an irreplaceable role with its unique transmission performance and wide adaptability.

[0003] The specifications of the sun gear are very diverse, among which the thin-walled, hollow, and ring structure with external teeth and internal spline is commonly used in electric vehicles. The wall thickness of this kind of sun gear is usually only 4-5mm, the ratio of wall thickness to outer diameter is more than 11:1, and the internal spline modulus is small (m n <1mm). When the sun gear with the above structure is processed by the conventional method of carburizing and quenching, the deformation amount and dispersion value are usually high, which leads to difficulties in quality control of the sun gear (the failure rate is generally more than 20%). At this time, the processing allowance of the sun gear can only be increased to ensure that the subsequent processing can be smoothly carried out. However, increasing the processing allowance not only increases the cutting workload of the sun gear during processing, reduces the processing efficiency, and increases the processing cost. At the same time, the increased thickness also affects the carburizing and quenching effect of the sun gear, which increases the uncertainty of the quality of the processed sun gear. Therefore, it is very necessary to develop a way to stably reduce the heat treatment deformation of the sun gear with the above structure. UTILITY MODEL CONTENTS

[0004] The utility model aims at providing a sun gear clamping device for reducing internal spline heat treatment deformation, so as to reduce the deformation amount of the sun gear after heat treatment through the improvement of the clamping device.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical scheme:

[0006] A sun gear clamping device for reducing internal spline heat treatment deformation, comprising

[0007] A load-bearing chassis;

[0008] The carburizing quenching and tempering fixture is provided with multiple layers which are stacked in parallel on a bearing base, and the upper surface of the carburizing quenching and tempering fixture is provided with vertical columns which are distributed in a matrix shape;

[0009] A compensation mandrel with a gap is sleeved on the column, and a sun gear with a gap is sleeved on the compensation mandrel, the outer side surface of the compensation mandrel is provided with an annular groove, the width of the annular groove is 1 / 3 of the thickness of the sun gear sleeved thereon, and the annular groove corresponds to the middle position of the sun gear sleeved thereon.

[0010] Preferably, the outer diameter of the two ends of the compensation mandrel is 1.2-1.5 mm smaller than the inner spline diameter of the sun gear.

[0011] Preferably, the outer diameter of the two ends of the compensation mandrel is 1.2-1.5 mm smaller than the inner spline diameter of the sun gear.

[0012] Preferably, the height of the compensation mandrel is 0.5-1.0 mm higher than the sun gear sleeved thereon.

[0013] Preferably, the carburizing quenching and tempering fixture comprises a support plate, the support plate is in a grid shape, and the columns are vertically arranged on the grid nodes of the support plate.

[0014] Preferably, the cross section of the column is in a triangular star shape, and the outer diameter of the column is 1-1.5 mm smaller than the inner diameter of the compensation mandrel.

[0015] Beneficial effects:

[0016] 1. The sun gear carburizing quenching and tempering fixture and the compensation mandrel are preferably designed, under the condition that the original carburizing quenching process parameters remain unchanged, the technical requirements of hardness, layer depth and metallographic structure on drawings are met, the thermal deformation of the thin-walled sun gear is effectively reduced, the deformation and runout of the outer teeth and the inner spline are reduced, the machining process of the inner spline after heat treatment is cancelled, and the size and precision of the inner spline are ensured.

[0017] 2. After the special sun gear carburizing quenching and tempering fixture and the compensation mandrel are put into production, the thermal deformation defect rate is reduced from more than 20% to less than 0.4%.

[0018] 3. The special sun gear carburizing quenching and tempering fixture and the compensation mandrel are simple and reasonable in structure, convenient for operators to assemble and disassemble, and high clamping efficiency is maintained. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is a structural schematic view of the utility model;

[0020] Figure 2 The utility model discloses a bearing chassis in the utility model;

[0021] Figure 3 The utility model discloses a detection data table of example 1 in the utility model;

[0022] Figure 4 It is the sectional view of the compensation core rod in the utility model.

[0023] Fig. 1. Bearing chassis 2. Carburizing quenching fixture 21. Support plate 22. Column 3. Compensation core rod 31. Annular groove 4. Sun gear. DETAILED DESCRIPTION

[0024] The technical scheme of the utility model will be described below in connection with the drawings. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.

[0025] In the description of the utility model, it is necessary to explain that the orientation or position relation indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like is the orientation or position relation shown in the drawings, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as the limitation of the utility model. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0026] In the description of the utility model, it is necessary to explain that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integrally connected, can be mechanical connection, can also be electrical connection, can be directly connected, can also be indirectly connected through the intermediate medium, can be the communication inside two elements. For the person skilled in the art, the specific meaning of the above terms in the utility model can be understood according to the specific circumstances.

[0027] Example 1

[0028] The embodiment discloses a sun gear clamping device for reducing the heat treatment deformation of internal spline, to overcome the problem that the internal spline deformation of the existing thin-walled, hollow, and circular ring structure sun gear with external teeth and internal spline is high in heat treatment production.

[0029] Specifically, as Figures 1-4As shown, it includes a load-bearing base 1. The load-bearing base used in this embodiment is a general model used in continuous furnaces, with specifications of 600x600x50mm, to ensure that this clamping device has wide adaptability.

[0030] like Figure 1 As shown, multiple layers of carburizing, quenching, and tempering fixtures 2 are stacked on the load-bearing chassis 1. Each layer of carburizing, quenching, and tempering fixtures can hold the sun gear 4 that needs to be heat-treated. It should be noted that the specific height of the carburizing, quenching, and tempering fixtures 2 needs to be adapted according to the thickness of the sun gear being treated. That is, there can be multiple selectable specifications for the carburizing, quenching, and tempering fixtures to ensure that after the sun gear is held on each layer of carburizing, quenching, and tempering fixtures, there is still enough space for the carburizing atmosphere and quenching oil to be present on the sun gear.

[0031] It should be noted that, in this embodiment, the selection principle for the carburizing, quenching, and tempering fixture 2 is to ensure that the height of the stacked carburizing, quenching, and tempering fixtures is as close as possible to the effective processing height of the heat treatment equipment, while ensuring that after the sun gear is clamped on the carburizing, quenching, and tempering fixture 2, the distance between the upper end face of the sun gear and the bottom face of the stacked carburizing, quenching, and tempering fixtures above is not less than 20mm. This ensures that the carburizing atmosphere and quenching liquid can smoothly pass through the sun gear during carburizing and quenching. Specifically, taking this embodiment as an example, if the overall height of the carburizing, quenching, and tempering fixture in this solution is about 63mm, and the effective processing height of the heat treatment equipment is about 600mm, then after stacking 7 layers of the carburizing, quenching, and tempering fixtures, the maximum height of the effective processing range during the heat treatment process will be reached. With this number of stacked layers, the carburizing and heat treatment effect of each layer of sun gear clamped on the carburizing, quenching, and tempering fixture is uniform and stable, ensuring the uniformity of the sun gear quality in the same batch.

[0032] like Figure 3 As shown, the carburizing, quenching, and tempering fixture 2 in this scheme specifically includes a support plate 21 and several columns 22 evenly arrayed on the support plate 21. The columns 22 set on the support plate 21 extend vertically so as to support the upper carburizing, quenching, and tempering fixture 2 when stacking carburizing, quenching, and tempering fixtures.

[0033] At the same time, such as Figure 4 As shown, this solution also includes several corresponding compensation mandrels 3 fitted onto the column 22. These compensation mandrels are used to improve the problem of excessive internal spline deformation of the existing sun gear during heat treatment.

[0034] Specifically, the compensation mandrel 3 in the present scheme has a tubular structure with a middle axial through hole to be sleeved on the column. Meanwhile, an annular groove 31 is formed on the outer surface of the compensation mandrel, which is located in the middle of the compensation mandrel to ensure that the annular groove is opposite to the middle position of the sun gear after the sun gear is sleeved on the compensation mandrel. Preferably, the width of the annular groove on the compensation mandrel is 1 / 3 of the thickness of the sun gear.

[0035] It should be noted that the compensation mandrel is designed as a dumbbell structure with an annular groove in the middle in the present scheme, and the main reason is that if a traditional cylindrical guide column is used to sleeve and clamp the sun gear, the smoothness of the atmosphere during carburizing and the quenching oil when entering the inner spline through the gap between the guide column and the inner spline is not the same, especially after entering the middle position, the flow rate will be lower than that of the two ends, at this time, it will cause the temperature variation of the two end regions and the middle region of the sun gear inner spline to be out of sync, and the thermal deformation amount of each region of the inner spline will also have certain differences (mainly the difference between the two end regions and the middle region), at this time, the middle part of the sun gear inner spline will be deformed radially inward / outward, that is, the thermal deformation amount of the middle part of the inner spline has a large difference, and the two ends of the sun gear clamped by the traditional cylindrical guide column are forced to change the structure following the heat treatment. Finally, the measured end jump value and M value of the sun gear after heat treatment using the traditional clamping device and clamping method are greatly different from the design requirements, the heat treatment yield of the sun gear is generally low, the subsequent processing cost of the sun gear is high, and the uncertainty of the product is increased.

[0036] By opening an annular groove on the outer surface of the compensation mandrel, the gap between the compensation mandrel and the middle position of the sun gear inner spline is increased, and the problem that the temperature variation caused by the low flow efficiency of the carburizing atmosphere and the quenching oil cannot be synchronized with the two ends is effectively solved, and the deformation amount of the sun gear after heat treatment is naturally reduced, thereby effectively improving the yield of the sun gear.

[0037] As a preferred, in the present scheme, to ensure that the carburizing atmosphere and the quenching liquid during quenching can smoothly flow through the surface of the sun gear inner spline and fully contact the surface of the sun gear inner spline. The outer diameter of the two ends of the compensation mandrel with larger diameter is 1.2-1.5mm smaller than the inner diameter of the sun gear inner spline.

[0038] It should be noted that under the above numerical value, the carburizing atmosphere and the quenching oil can pass through the surface of the sun gear inner spline at a suitable rate, ensuring the optimal treatment of carburizing and quenching.

[0039] It should be noted that as a further optimization, the outer diameter of the two ends of the compensation mandrel 3 is 1.0 mm larger than the outer diameter of the annular groove 31 in the middle of the compensation mandrel 3. That is, the annular groove is radially contracted inward by 1.0 mm based on the outer diameter value of the two ends of the compensation mandrel. At this time, the gap between the annular groove 31 and the inner diameter of the sun gear is between 1.1 and 1.25 on one side. It should be noted that through production verification, the gap value is the best interval value for maintaining the temperature change speed synchronization of the two ends and the middle part of the sun gear inner spline under the structure in the present scheme. That is, under the gap value, the two end parts and the middle part of the sun gear inner spline can maintain synchronous temperature rise and fall, and the quenching and carburizing effect is not affected.

[0040] It should be noted that the sun gear has chamfered inner spline ports at both ends, and the length of the compensation mandrel is set to be 0.5-1 mm greater than the thickness of the sun gear set on the outside of the compensation mandrel to ensure that the compensation mandrel can completely cover the inner spline.

[0041] The carburizing and quenching fixture 2 in the present scheme is mainly composed of a support plate 21 and an array of columns 22 on the support plate. In order to facilitate the entry of carburizing atmosphere and quenching oil from the lower port of the sun gear during the heat treatment process, the support plate 21 is arranged in a grid shape, and the columns 22 are arranged on the grid nodes of the support plate. Preferably, a honeycomb structure can be provided. Under this structure, the stability and physical properties of the carburizing and quenching fixture can be effectively guaranteed, and the grid structure can also effectively reduce the overall weight of the clamping device in the present scheme, achieving the purpose of weight reduction and energy saving.

[0042] In addition, it should also be noted that during the heat treatment process, in order to ensure that the compensation mandrel inserted into the sun gear can maintain the same temperature as the surrounding environment, so as to avoid unnecessary disturbance to the temperature of the sun gear, the cross section of the column in the present scheme is in a triangular shape, that is, when the compensation mandrel is set on the column, the column and the inner control of the compensation mandrel leave a channel for the entry of quenching oil and carburizing atmosphere. Through this structure, the present scheme realizes the rapid heat exchange between the internal part and the outside of the compensation mandrel, ensures the consistency of the temperature of the compensation mandrel and the external environment, and avoids disturbing the temperature of the sun gear during the heat treatment process (mainly to avoid the compensation mandrel being wrapped by the sun gear. If there is no heat exchange channel between the compensation mandrel and the outside, it is difficult to realize the rapid synchronization with the external environment temperature, which will cause the temperature difference between the inside and outside of the sun gear, and then cause the inconsistent heat deformation of the sun gear, resulting in the shape distortion of the sun gear).

[0043] It should also be noted that in order to facilitate the compensation mandrel to be easily set on the column and then easily removed from the column, there is a size difference of 1-1.5 mm between the outer diameter of the column 22 and the inner diameter of the compensation mandrel 3.

[0044] Working principle: the heat treatment of the sun gear is implemented according to the following steps, specifically:

[0045] Step 1: according to the specification of the sun gear to be treated, a layer of carburizing quenching and tempering fixture with an appropriate stand spacing is selected, and the carburizing quenching and tempering fixture is installed horizontally on the load-bearing base. Specifically, the selected carburizing quenching and tempering fixture needs to ensure that when the sun gear is clamped to the carburizing quenching and tempering fixture in this scheme, the gap between adjacent sun gears is not less than 12 mm, so as to ensure that the workpieces do not bump into each other and facilitate the smooth flow of atmosphere during carburizing and the uniform and orderly flow of quenching liquid during quenching. At the same time, it is also necessary to ensure that when the sun gear is clamped to the carburizing quenching and tempering fixture, there is a height difference of not less than 20 mm between the upper end face of the sun gear and the bottom face of the carburizing quenching and tempering fixture above it, so as to ensure that the upper and lower workpieces are not crushed and facilitate the smooth flow of atmosphere during carburizing and the uniform and orderly flow of quenching liquid during quenching.

[0046] Step 2: the compensation core rod is vertically sleeved onto the corresponding stand of the carburizing quenching and tempering fixture;

[0047] Step 3: the sun gear is sleeved onto the compensation core rod, filling a layer, and it needs to be noted that after the sun gear is sleeved onto the sun gear compensation core rod, the annular groove in the middle of the sun gear compensation core rod needs to be positioned in the middle of the sun gear;

[0048] Step 4: the second layer of the carburizing quenching and tempering fixture is stacked and loaded onto the first layer of workpieces that have been filled;

[0049] Step 5: repeat steps 2-4 until the stacking height reaches the height that is suitable for the heat treatment furnace, so as to maximize the utilization of equipment during each heat treatment.

[0050] It needs to be noted that in step 5, i.e. during the implementation of layer-by-layer stacking of the sun gear, the following arrangement can also be made. Specifically, when clamping the sun gear, one layer is left empty after clamping every two layers, so as to ensure that the upper and lower parts of every two sun gears are empty. Through the above arrangement, the smooth flow of atmosphere during carburizing (to make the carburized layer of the whole batch of products uniform and consistent) and the uniform and orderly flow of quenching liquid during quenching (to make the hardened layer and the deformation of the whole batch of products uniform and consistent) are facilitated.

[0051] The surface hardness of the product produced by the process of this embodiment is above 700HV1, the core hardness is 340-400HV1, and the hardened layer (550HV1) is 0.4-0.7 mm. The single-furnace yield reaches 588 pieces, the internal spline deformation is stable and reaches within 0.03 mm, and the heat treatment process qualification rate of the sun gears produced in large quantities reaches above 99.6%. The specific data are referred to Tables 2-1 and 2-2.

[0052] Comparative example

[0053] The difference between the clamping device of the sun gear in this scheme and that in Embodiment 1 is that the support plate in the carburizing quenching fixture 2 is non-grid-shaped, and the guide column for clamping the sun gear is only a cylindrical structure. The clamping method of the sun gear is:

[0054] Step 1: According to the specification of the sun gear to be processed, a layer of fixture with an appropriate stand spacing is selected, and the fixture is installed horizontally on the load-bearing chassis;

[0055] Step 2: The sun gear is sleeved onto the guide column of the fixture, and a layer is filled;

[0056] Step 3: The second layer of the fixture is stacked and loaded onto the first layer filled with workpieces;

[0057] Step 4: Repeat steps 2-3 until the stacking height reaches the height suitable for the heat treatment furnace to maximize equipment utilization during each heat treatment.

[0058] The actual data of the sun gear after heat treatment through the above structure and method can be referred to Table 1-1, Table 1-2.

[0059] It should be noted that, according to the comparison of the detection data of Table 1-1, Table 1-2 and Table 2-1, Table 2-2, the yield of the sun gear is obviously improved by using the clamping device and clamping method disclosed in this scheme.

[0060] Table 1-1

[0061]

[0062] Table 1-2

[0063]

[0064] Table 2-1

[0065]

[0066] Table 2-2

[0067]

[0068] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to these embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A sun gear clamping device for reducing heat treatment distortion of internal splines, characterized by: The utility model relates to a kind of carburizing quenching fixture, including Load chassis (1); Carburizing quenching fixture (2) is provided with multiple layers, and is stacked in parallel on load chassis (1), and the upper surface of carburizing quenching fixture (2) has vertical column (22) arranged vertically, and vertical column (22) is distributed in matrix form; Compensation mandrel (3) with gap is sleeved on vertical column (22), sun gear with gap is sleeved on compensation mandrel (3), and annular groove (31) is arranged on the outer side of compensation mandrel (3), the width of annular groove (31) is 1 / 3 of the thickness of sun gear sleeved thereon, and annular groove (31) corresponds to the middle position of sun gear sleeved thereon.

2. The sun gear clamping device for reducing heat treatment distortion of internal spline as claimed in claim 1, wherein: The outer diameter of both ends of compensation mandrel (3) is 1.2-1.5mm smaller than the inner spline diameter of sun gear.

3. The sun gear clamping device for reducing heat treatment distortion of internal spline as claimed in claim 2, wherein: The outer diameter of both ends of compensation mandrel (3) is 1.0mm larger than the outer diameter of annular groove (31) in the middle of compensation mandrel (3).

4. The sun gear clamping device for reducing heat treatment distortion of internal spline as claimed in claim 3, wherein: The height of compensation mandrel (3) is 0.5-1.0mm higher than sun gear sleeved thereon.

5. A sun gear chucking device for reducing heat treatment distortion of internal splines as set forth in claim 4, characterized in that: Carburizing quenching fixture (2) includes support plate (21), and support plate (21) is in grid form, and vertical column (22) is vertically arranged on the grid node of support plate (21).

6. A sun gear chucking device for reducing heat treatment distortion of internal splines as set forth in claim 5, characterized in that: The cross section of vertical column (22) is in triangular star form, and the outer diameter of vertical column (22) is 1-1.5mm smaller than the inner diameter of compensation mandrel (3).

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