JB/T 9181-1999 JB/T 9181-1999 Structural design specification for hot-forged precision straight bevel gears JB/T9181-1999 Standard download decompression password: www.bzxz.net

JB/T9181-1999
This standard is a revision of ZBJ32008-89 "Structural Design Specifications for Precision Forgings of Straight Bevel Gears". Compared with ZBJ32008-89, the main technical content of this standard has changed as follows: the precision forgings in the original standard are changed to precision hot forgings. This standard replaces ZBJ32008-89 from the date of implementation. This standard is proposed and managed by the National Forging Standardization Technical Committee. The drafting unit of this standard: Shanghai Automotive Co., Ltd. Automobile Gear Factory. The main drafters of this standard: Yang Qihua, Kong Wenkai, Zhuang Jianhua, Shen Zhenyao. 383
1 Scope
Machinery Industry Standard of the People's Republic of China
Precision hot forgings of straight bevel gear
Structural design specifications forprecision hot forgings of straight bevel gearJB/T9181:1999
Replaces ZBJ32008--89
This standard specifies the structural elements, dimension marking and measurement of precision hot forgings of steel straight bevel gears; and according to the characteristics of precision hot die forging process, the optimized structural form of precision hot forged straight bevel gears is proposed. This standard is applicable to precision hot forgings of straight bevel gears produced by precision die forging process on hot die forging presses, die forging hammers, screw presses and other equipment, with a weight of less than 20kg, a maximum outer diameter and a total thickness of less than 250mm. Its gear tooth surface is no longer processed and reaches the 9~12 grade accuracy of GB/T11365--1989 "Precision of Bevel Gears and Hypoid Gears". This standard is used when formulating the process of precision hot forging spur bevel gears, and can also be used as a reference for product design. 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest version of the following standards. GB/T11365--1989 Precision of bevel gears and hypoid gears JB/T42011999 Technical conditions for precision hot forgings of spur bevel gears 3 Definitions
This standard recommends the use of the following definitions.
3.1 Precision hot forgings of spur bevel gears and precision hot forged spur bevel gears The tooth surface of spur bevel gears obtained by precision hot die forging is no longer cut or diced, and the accuracy reaches above grade 12 specified in GB/T11365. This type of forging is generally called precision hot forgings of spur bevel gears (hereinafter referred to as precision forgings). The finished parts obtained by subsequent processing of precision hot forgings of spur bevel gears are called precision hot forged spur bevel gears (hereinafter referred to as precision forged gears). 3.2 Spoke plate
The annular plate connecting the wheel rim and the wheel hub on the precision hot forging is called the spoke plate. 4 Structural elements
4.1 Parting surface
The parting surface of the precision hot forging is a plane perpendicular to the axis and contains the maximum diameter of the precision forging (Figure 1, Figure 2). Approved by the State Bureau of Machinery Industry on June 24, 1999 384
Implemented on January 1, 2000
4.2 Draft Angle and Tolerance
Parting Surface
JB/T9181-1999
Spoke Plate
The draft angle (such as α, β in Figure 1) and its tolerance of precision forgings shall comply with the provisions of 4.3.3 of JB/T4201-1999. 4.3 Fillet Radius and Tolerance
The fillet radius (such as R, r in Figure 1) and its tolerance on precision forgings shall comply with the provisions of 4.3.2 of JB/T4201-1999. 4.4 Spoke Plate Thickness
The minimum thickness of the spoke plate of precision forgings (Figure 2) can be selected according to Table 1 based on the projection area S of the precision forgings on the parting surface. Table 1
>25～50
>50～100
Note: The t values ​​listed in the table are allowed to be negotiated and changed according to equipment, process and other conditions. 4.5 Surplus block
≥100～200
200~400
Parting surface
≥100~800
When the distance Ci between the tooth root on the back cone surface of the precision forging and the back surface E is less than 3mm, a surplus block C2 needs to be placed on the back surface. The sum of C, and Cz should be greater than 3mm (Figure 3).
4.6 Flash or chamfer
On the back cone surface of the precision forging, there are flashes connected between the teeth, which are umbrella-shaped or tooth-shaped, and their thickness C, should not be less than 1mm (Figure 3). After the flash is removed, the precision forging has a chamfer perpendicular to the parting surface on the back cone surface (Figure 4). The trimming requirements shall be in accordance with the provisions of Table 4 in JB/T4201--1999.
4.7 Blind holes, through holes and punching holes
4.7.1 Blind holes
Blind holes are truncated cones and are divided into one-way blind holes (Figure 5) and two-way blind holes (Figure 6). The hole depth h should not be greater than 0.7 times the diameter D of the large end of the truncated cone.
The thickness ti between the two-way blind holes shall not be less than the minimum thickness t of the spoke plate specified in Table 1. 4.7.2 Through holes
The through holes are truncated cones, and their large end diameter D: not less than 30mm (Figure 7). 4.7.3 Punching holeswww.bzxz.net
The diameter of the punching hole D. Not less than 25mm (Figure 8) Figure 5
5 Dimensional tolerances and machining allowances of precision forgings JB/T9181-1999
Dimensional tolerances and machining allowances of precision forgings shall comply with the provisions of 4.2 and 4.3 of JB/T4201-1999. 6 Marking and measurement of dimensions of precision forgings
6.1 Marking and measurement of dimensions of precision forgings perpendicular to the parting surface The marking and measurement of dimensions of precision forgings perpendicular to the parting surface are the same as those of general die forgings. 6.2 Marking and measurement of dimensions of precision forgings parallel to the parting surface 6.2.1 Dimensions of precision forgings parallel to the parting surface shall be marked according to the theoretical intersection unless otherwise specified (Figure 9). 6.2.2 Dimensions marked according to the theoretical intersection shall be directly measured by moving a distance K×r, or K×r2 (Figure 10). The value of K shall be selected according to Table 2.
Die forging slope
0°00°
0°30°
JB/T 9181-1999
3°00°
10°00
If it is an odd number of teeth, the measured size is calculated according to formula (1) 6.2.3 If the precision forging has an even number of teeth, the pre-circular diameter of the tooth can be directly measured with an external diameter gauge. Calculation (Figure 11):
Where: d.-measured size;
d. —tooth top diameter;
S.\tooth top thickness,
—number of teeth.
6.3 Measurement of machining allowance of precision forgings
1 → cos
The machining allowance of precision forgings should be measured based on the gear teeth. 6.4 Measurement of transmission accuracy of precision forged gears
arcsin
Measurement of transmission accuracy of precision forged gears can be carried out after positioning the gear teeth and cutting out the measurement reference. The measurement method is the same as that of precision forged gears.
7 Optimized structure of precision forged gears
End face closed structure
The teeth of precision forged gears can be designed as a structure with a closed rear end face (Figure 12, Figure 13) or a closed front end face (Figure 14). This structure cannot be manufactured by gear cutting.
Precision forged gears with general use requirements, especially precision forged gears with high requirements for mechanical strength, should adopt this structure, such as jack gears (Figure 12), speed increaser gears (Figure 13) and heavy machinery gears (Figure 14), but their mating gears cannot adopt an end face closed structure.
7.2 Combined structure
JB/T9181-1999
In mechanical transmission, the front end or (and) the rear end of the precision forged gear is often connected to other parts. In this case, it can be designed as a whole to form a combined structure (Figure 15, Figure 16, Figure 17).
Precision forged gears that are forgeable and conducive to mechanical manufacturing technology, especially precision forged gears that have high requirements for the connection strength between each assembly, should adopt this type of structure, such as slurry gears (Figure 15), textile machinery gears (Figure 16) and tank gears (Figure 17). However, Figures 16 and 17 are not suitable for precision forged gears. The mating gear of the bevel gear in Figure 17 cannot adopt the end face closed structure. Cam
7.3 Vertical chamfer structure
Circular loss gear
According to the provisions of 4.6, a chamfer perpendicular to the parting surface is designed on the back cone surface of the precision forged gear, which is a vertical chamfer structure. Precision forged gears with a non-end face closed structure with a back cone surface should all adopt this structure. 7.4 Tooth profile modification and tooth direction modification structure
In batch production, precision forged gears can adopt tooth profile modification and tooth direction modification structures that are difficult to manufacture by cutting methods. This structure is quite beneficial for use.
7.5 Structure without front cone
In the structural design of precision forged gears or precision forgings, the structure without front cone should be used as much as possible (Figure 18). Figure 18
7.6 Structure without back cone
Precision forged gears with an appearance close to oblate sphere or cylindrical cone should adopt this structure without back cone, such as differential gears (Figure 19), chuck gears (Figure 20) and half-axle gears (Figure 21). 388
JB/T 9181--1999
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