Design of new forging die for spiral bevel gear

According to the deformation of metal, the precision die forging of spiral bevel gear can be divided into open die forging and closed die forging. Figures 1 and 2 respectively show the part drawing and three-dimensional modeling drawing of driven spiral bevel gear of Chinese automobile. The parameters of spiral bevel gear are shown in the table.

It can be seen from figures 1 and 2 that the shape of spiral bevel gear is relatively special, so it is difficult to adopt the die structure used in the usual closed die forging. For a long time, the research on the precision forging of this kind of spiral bevel gear is only limited to open die forging. Because the forging produced by open die forging will inevitably have flash and skin, which increases the cross-sectional area of the forging and increases the forging forming force required for processing, which will not only increase the subsequent processing, waste energy, and even damage the forging die due to excessive stress. Therefore, it is necessary to find a new closed die forging method to form spiral bevel gear. Based on the brief description of the open die forging die structure of spiral bevel gear and its problems in actual production, the new process of precision forging of spiral bevel gear is analyzed, and the new die structure is discussed.

Serial number	Name	Code	Company	Calculation formula and description	Parameter value
1	Number of teeth	Z		Known	25
2	Large end modulus of tooth profile	m	mm	Known	9
3	Tooth profile angle	α	（°）	Known	20
4	Addendum height coefficient	h*α		Select by table	0.85
5	Top clearance coefficient	c*		Select by table	0.188
6	High displacement coefficient	x		x=-0.39(1-1/u*u)	-0.29
7	Tangential displacement coefficient	xτ		Select by table	0
8	Helix angle at the midpoint of tooth profile	β	（°）	Known	35
9	Spiral direction				Dextral
10	Split cone angle	δ	（°）	Select by table	62.5
11	Graduation circle diameter	d	mm	d = mz	225
12	Cone distance	R	mm	R = d/2sinδ	126.801
13	Tooth width coefficient	φR		φR = 1/3.5-1/3	0.315
14	Tooth width	b	mm	Take b= φR and b = 10m the smaller	40
15	Addendum height	ha	mm	ha = (h*a+x)m	5.04
16	Full tooth height	h	mm	h = (2h*a+c*)m	16.992
17	Root height	hf	mm	hf = h-ha	11.952
18	Addendum circle diameter	da	mm	da = d+2hacosδ	229.6504
19	Root angle	θf	（°）	tanθf = hf/R	5.385
20	Tooth apex angle	θa	（°）	θa2 = θf1	3.039
21	Top cone angle	δa	（°）	δa = δ + θa	65.5
22	Root cone angle	δf	（°）	Δf = δ – θf	57.1
23	Cutter head diameter	D0	mm	Known	228.6