Radial shaving technology in gear machining

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Gear shaving technology is widely used in large-scale gear shaving. The main methods include axial shaving (ordinary shaving), radial shaving, diagonal shaving, tangential shaving, etc. because the shaving knife used for axial shaving is relatively easy in design, manufacturing and grinding, axial shaving has always been the most commonly used shaving method

with the continuous improvement of the quality requirements of automobile gears, axial shaving has been gradually replaced by radial shaving. Those automobile gear enterprises with certain scale and strength closely follow the development trend of automobile gear processing technology in the world, and almost all adopt radial shaving technology. Compared with axial shaving, radial shaving has greater advantages in production efficiency, processing quality and tool durability

machining principle of axial shaving and radial shaving

1. Machining principle of axial shaving

shaving applies the meshing principle of cross axis helical gear, and uses the tool gear with cutting ability with small groove on the tooth surface (as shown in Figure 1) to engage with the workpiece without clearance, The metal is removed for machining by feeding and pressurizing and using the cutting effect caused by the relative slip between the meshing tooth surfaces introduced by Polaris in October last year. Theoretically, the meshing tooth surface between the tool and the workpiece is a kind of point contact, but due to the elastic and plastic deformation of the material at the contact point between the tool and the workpiece under the action of feed pressure in the process of shaving, the contact point of the meshing tooth surface expands into a small elliptical contact area

Fig. 1 gear shaving cutter

if the gear shaving cutter and the workpiece rotate only in situ, only a narrow area can be shaved on the tooth surface of the workpiece. In order to shave all the tooth surfaces of the gear, axial shaving is realized by making axial reciprocating motion of the workbench along the axis of the workpiece relative to the cutter. After each re stroke, radial feed is made along the direction of the common vertical line of the possible abnormal working frequency (11.0592Mhz) of the two axes to shave the required tooth thickness, The axial shaving working cycle is shown in Figure 2A

2. Radial shaving principle

according to the above shaving principle, the meshing tooth surfaces of axial shaving are in point contact in theory. In the cutting process, under the action of feed pressure, the tooth surface expands into a relatively small elliptical surface contact area after being loaded. If the workpiece and the razor only rotate in situ, There is only one narrow shaving mark on the tooth surface of the workpiece, which is equidistant from the width of the blade groove when the pressure oil enters the working cylinder from the oil port and acts on the lower end face of the working piston. If the gear shaving blade is specially designed to keep it in contact and mesh with the tooth surface of the workpiece, and then the cutting edge groove is spirally staggered along the circumference, so that the gear shaving cutter and the workpiece can shave the whole tooth width only by rotating in situ. In order to shave to the specified tooth thickness, only radial feed is required. This gear shaving method is radial gear shaving, and its working cycle is shown in Fig. 2B

application conditions of radial shaving

1. In order to ensure the contact between the shaving cutter and the full tooth width line of the workpiece, the tooth length direction of the razor needs to be modified, that is, the tooth direction of the razor needs to be modified into an inverted drum shape, as shown in Figure 3

Figure 3 reverse drum shape of the tooth surface of the neck shaving cutter

in order to ensure the tooth surface of the whole workpiece, refine the surface quality and improve the shaving efficiency, the cutting edge groove of the tooth surface of the shaving cutter must be arranged in a spiral dislocation along the circumference and divided into several dislocation groups. The tool tooth width must be greater than the workpiece tooth width

1. The tooth surface of the shaving cutter and the tooth surface of the workpiece are conjugate tooth surfaces, so the cutter needs to be shaped along the direction of tooth length and tooth height

2. The radial gear shaving cutter must have a supply source with reliable quality, stable supply and moderate price

3. There must be grinding equipment for grinding radial gear shaving cutter

4. There must be a high rigidity shaving machine with radial shaving function

advantages and disadvantages of radial shaving

compared with axial shaving, radial shaving has the following advantages:

1. High processing efficiency

Radial shaving has 1 ~ 3 times higher processing efficiency than axial shaving because there is no axial cutting movement and only radial forward and backward movement

2. High machining quality

can effectively reduce or even eliminate the concave phenomenon of tooth profile

the meshing of axial shaving tooth surface belongs to point meshing, and the chance of single pair of teeth meshing near the pitch circle is large. In this way, the pressure of tooth surface increases when single pair of teeth meshing, and the margin cut here is more than that of other parts, resulting in concave tooth profile near the pitch circle. The meshing of radial shaving tooth surface is linear contact, so compared with ordinary shaving, the bearing area of meshing feed pressure of tooth surface is increased. Therefore, the sensitivity of shaving allowance to the change of meshing tooth contact points during meshing can be reduced, so as to slow down the formation of concave tooth profile

1. It is conducive to improve the tooth surface roughness

Radial shaving is multi edge simultaneous cutting. The shaving cutting process is more stable than axial shaving, and the tool mark is relatively shallow. In addition, the appropriate selection of the displacement of the cutting edge can achieve a higher roughness level

2. The stability of tooth profile and tooth direction accuracy of gear after shaving is good

because axial shaving has one more axial cutting motion than radial shaving, the links and factors affecting shaving accuracy increase. Firstly, under the same conditions, the rigidity of the machine tool is not as good as that of radial shaving; Secondly, the axial motion accuracy, motion stability and reliability of the shaving machine have become a factor affecting the shaving accuracy, so the axial shaving process is not easy to be stable, and the stability of the tooth profile and tooth direction accuracy of the gear after shaving is also relatively poor. During radial shaving, due to line contact, stable meshing, no axial cutting, only radial feeding and no influence of axial movement, the shaving process is stable, and the tooth profile and tooth direction accuracy of the gear after shaving are relatively stable

According to the different uses and requirements of automobile gears, in order to reduce meshing noise and improve bearing capacity, most automobile gears adopt special tooth profile and tooth direction modification drum shape. For axial gear shaving, in addition to the modification of cutter tooth profile, the axial motion mechanism of gear shaving machine also needs to have the function of drum motion, so as to realize the modification of tooth drum. However, due to the complexity and instability of the axial motion mechanism, the tooth direction modification of axial shaving is very difficult, which is mainly manifested in the difficulty and instability of the adjustment of the modification drum shape. The radial shaving profile and tooth direction modification are realized during the grinding of the tooth part of the shaving cutter, which is easier to control the modification amount, and the shaving process is relatively stable, so the stability of the part modification after shaving is relatively good

4. The service life of gear shaving cutter is relatively high

due to the simultaneous cutting of multiple edges, the wear of the tool edge is relatively uniform. Compared with the axial gear shaving cutter, the average metal allowance shaved by a single edge is small, so the wear is small and the service life is relatively high

of course, compared with axial shaving, radial shaving also has the following shortcomings:

1. The design and manufacture of radial shaving cutter are relatively complex, highly specialized and not universal

2. Generally, only gears with modulus ≤ 3mm and tooth width ≤ 2.5mm can be shaved in radial shaving, and the processing range has certain limitations

3. The machine tool with radial gear shaving function is required, and the rigidity of the machine tool is better

with the increasing development and maturity of radial shaving technology, the above deficiencies have been well solved. The relevant domestic professional manufacturers have a considerable manufacturing level of radial shaving tools and machine tools

in addition, the modulus of most automobile gears is generally ≤ 3mm and the tooth width is ≤ 25mm. Therefore, the limitation of the processing range of radial shaving does not pose a problem for automobile gear processing

in conclusion, compared with axial shaving, radial shaving has incomparable advantages, which is very in line with the economic, efficient and high-quality development direction of the automotive gear industry. In recent years, radial shaving technology has been rapidly promoted in domestic professional automobile gear manufacturers, and has become the mainstream shaving technology. Its application and development prospect is very broad

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