齿轮的机械加工

齿轮的机械加工（机造齿轮）

齿轮可以通过加工铸件、锻件、挤压件、冲压件、扎制件、粉末冶金、金属薄板（可以用来加工微小齿轮，比如用于手表和小钟）获得。非金属的齿轮可有铸造得来。

以下是锻件和铸件的两种机械加工齿轮的方法：仿形法和范成法。

仿形法：

在仿形法中，切削刀具是一把类似于两轮齿间距形状的铣刀。轮齿的形状是由刀具在齿轮坯圆柱表面上反复切削形成的。刀具以适当的深度沿着轮齿的长短方向作轴向运动，加工出轮齿的轮廓。加工完一个轮齿后，刀具复位，齿轮坯分度，刀具加工另一个轮齿，重复以上过程直至（齿轮上）所有的轮齿都加工完。

每把刀都是为加工一定范围齿数设计的。仿形加法出来的轮齿轮廓精度取决于刀具的精度、机床的精度、本身的强度。仿形加工可以在把刀具装在轴上、齿轮坯装在分度头上的铣床上进行，但是（仿形加工的）效率低。

由于刀具有固定的位置，所以仿形加工适用于固定宽度的轮齿。比如，正齿轮和斜齿轮，但是不适用后于锥齿轮。像齿条这样轮齿在直表面上内轮齿的加工，采用在仿形机床上装有轮齿

形状轮廓铣刀的方法来加工。

仿形加工法是加工各种各样轮齿轮廓相对简单的一种方法；但是它的运作太慢，许多类型的机床要求有熟练的操作工。所以它只适用于低质量的生产。用具有半自动装置的机床来加工仿形产品更为经济。

范成法：

范成法切削刀具可能是以下几种中的一种:

●齿轮形状刀具

●齿条形状刀具

●滚刀

a、齿轮状的刀具可以看成是相互啮合的一对齿轮中的一个，另一个是齿轮坯；我们把这种机床叫插齿机。刀具平行齿轮坯并以缓慢的速度绕齿轮坯转动，一相同的节距圆速度作轴向的往复运动。一组轮系能提供刀具轴和齿轮坯间所需的相关运动。

b、在齿条刨床上，范成刀具是齿条的一部分，它平行于齿轮坯轴做往复运动。因为齿条刀

具的实际齿数不多于6~12个，所以刀具回到起始点的时间间隔必须是可调的，但齿轮坯固定不变。

c、当铣削直齿齿轮时，铣刀和齿轮的夹角是90°减去罗纹铣刀的导程角。铣削的所以运动都是螺旋运动，铣削和齿轮不停的做圆周运动，两齿轮啮合在一起直至所以的轮齿加工完。

由于生产各种齿轮的效率高、尺寸精度高，滚齿加工齿轮的方法广泛用于工业生产。虽然这种加工方法适用生产低性能的产品，但是对于生产中高性能的产品也是很经济的。

齿轮的后续加工工艺：

许多后续工序对提高轮齿表面质量是至关重要的。加工方法要根据齿轮的制造方法和齿轮经过热处理后是否会变硬来选择。热处理会导致部分畸变。因此，对齿轮的精加工和热处理都是合适的后续加工。

摩擦抛光 轮齿的表面粗糙度可以通过摩擦抛光的方法得到改善。在20世纪60年代，用特别坚硬齿轮形状的砂轮磨削和用表面滚压的方法来加工轮齿的方法，主要会产生塑性变形。采用冷加工方法加工轮齿时，可以提高轮齿的表面粗糙度和降低表面的残余应力，还有增加它的抗疲劳寿命。但是摩擦抛光不能明显的提高轮齿的精确度。

抛光 研磨 对于要求高平面精度、节距和表面粗糙度的齿轮要经过抛光、研磨的后续处理。特制的抛光轮既可以加工仿形法加工出来的轮齿表面又可以加工范成法加工的轮齿表面。齿轮抛光机床的种类很多，但是带有分度头的机床是最常用的。在仿形抛光机关方法中，砂轮具有同一的齿距形状。在范成法加工方法中，砂轮的运作方式类似于前面讲述的范成刀具的运作方式。

周全设计齿轮机床

设计周全的齿轮生产操作包括以下的几点:

a、齿轮坯料的设计很重要，尤其是复杂的轮齿，机床的夹具必须保证安全可靠。

b、尽可能用经济的生产方法制造出合格的平面精度和表面粗糙度的齿轮。

c、对于机床来说宽齿比窄齿难加工。

d、齿轮的制造要求高精度的机床主轴。

e、轮齿和法兰间应有和是的间隙，轴肩、还有其他的一些相关的特性要求也是如此。

f、设备应尽可能采用标准刀具。

齿轮的经济化生产

在生产加工中，随着表面精度和质量的提高，生产的费用也在增加。下表显示了有关齿轮自己了性能的制造成本，它是有AGMH（美国齿轮制造协会）DIN（德国齿轮制造协会）制定的数据。数值越高，表明轮齿的 尺寸公差就越小。注意变化幅度引起成本的变化。

概括总结

● 许多形状复杂的零件可以通过镶嵌、车削、和端铣削、拉削来加工。铣削是最常用的方法之一，因为它可以加工出各种形状复杂的零件。

● 虽然这三种加工工艺类似于车削、钻削的加工方法，但是后者的加工多采用多刃刀具在可变的轴上加工出所要求的零件。

● 这些机床刀具的有计算机控制，进行灵活管理。

● 齿轮除了前面介绍的成形加工方法外，齿轮还可以采用机床生产（仿形切削和范成加工），后者具有高的表面粗糙度和尺寸精度。后者通过剃齿、抛光、研磨等后续加工工艺来提高轮齿的表面粗糙度和尺寸精度。

Gear machining (machine-made gear)

Gear can be processed castings, forgings, squeezing pieces, stamping parts, parts, powder metallurgy, metal plate (can be used to micro-processing gear, such as for watches and small bell) was. Non-metallic gear may have cast them.

Following is the forgings and castings machining gear two ways: Profiling law and Generating law.

Profiling Law:

In profiling law, a cutting tool is similar to the shape of two teeth pitch cutter. the shape of a tooth from the cutter in the gear blanks cylindrical form on the surface of the repeated cutting. Tool to the appropriate depth along the length of tooth axial direction for the movement, processing the outline of a tooth. End processing of a tooth, the reduction tool, the gear blanks, another tool processing gear, repeat the above process until the (gear on) all the teeth are processing End.

As the knives have a fixed position, so copying processing apply to a fixed width of the tooth. For example, is gear and helical gears, but does not apply after the bevel gear.

Tooth in the rack like this straight on the surface of the tooth processing, used in copying machine is equipped with tooth shape outline cutter approach to processing.

Tooth can also through a special machine to process it on top with tooth outline of the template control of the cutting tool. Because they can make the tooth than the number of templates, dimensional accuracy is improved.

Profiling is the process of processing a variety tooth outline of a method is relatively simple, but its operation is too slow, and many types of machine tools required skilled operatives. Therefore, it is only applicable to low-quality production. With a semi-automatic device copying machine to process more economical products.

Generating Law:

Generating law cutting tool may be in one of the following:

● gear cutter shape

● tool rack shape

● hob

a gear-like tool can be seen as a mutual engagement of a gear in one of the other gear blanks; we have such a machine called slotting machine. Tool parallel gear blanks and to slow the speed of rotation around the gear blanks, a round at the same pitch for the reciprocating axial movement. A tool to provide round of the shaft and gear blanks requirements related to the campaign.

b in the rack planer, generating tool rack is part of its axis parallel to the gear blanks do reciprocating movement. Tool rack because the actual teeth of not more than 6 to 12, the cutter returned to the starting point must be adjustable time intervals, but the gear blanks fixed.

c When Milling straight Gear, cutter and gear is the angle between minus 90 ° rib cutter the lead angle. So the campaign are milling spiral movement, milling and gear to keep the circular motion, the two gears meshing together so until the end of the tooth processing.

As the efficiency of the production of high gear, size, high precision, gear hobbing processing methods widely used in industrial production. Although this method is

suitable for the production of low processing performance of products, but for the production of high-performance product is also very economical.

Bevel gear processing：

Many processing methods have been introduced, the tooth surface and dimensional accuracy difficult to achieve the requirement. In addition, (the work) noise, mechanical properties, fatigue life is not high enough. Many follow-up processes to improve the tooth surface quality is of utmost importance. Processing methods according to the manufacturing methods and gear after gear after heat treatment to choose whether it will harden. Heat treatment will lead to some distortion. Therefore, the gear finishing and heat treatment are appropriate follow-up processing.

Friction Pao Guanglun the tooth surface roughness can be friction polishing methods to improve. In the 1960s, and especially hard-shaped gear grinding wheel and the use of surface rolling approach to the method of processing gear, will mainly produce plastic deformation. Cold processing method used when the tooth, can improve the tooth surface roughness of the surface and reduce the residual stress, and increase its anti-fatigue life. However, friction polishing can not be significantly improved the precision of the tooth.

Polishing and grinding requirements for high precision plane, pitch and surface roughness of the gear to go through polishing, lapping the follow-up treatment. Pao Guanglun special processing profiling method can be processed by the tooth surface can also generating processing method for processing tooth surface. Gear many types of polishing machine, but with the head of the machine is the most commonly used. Polish authorities in the profiling method, the wheel has the same shape of the pitch. In the generating of processing methods, similar to the way the operation of grinding wheel on the front generating tool mode of operation.

Well-designed machine tools gear

The well-designed gear production operations include the following points:

a gear blanks design is very important, especially the complex gear, the machine must ensure safe and reliable fixture.

b as far as possible the economic production methods used to manufacture the plane passing accuracy and surface roughness of the gear.

c the machine is narrower than the width teeth tooth difficult process.

b gear manufacturing requirements of high-precision machine tool spindle.

e tooth between the flange and the gap is due and, shoulder-axis, there are a number of other related requirements of the same is true.

F equipment should be a standard tool as far as possible.

Gear's economic production

In the production and processing, with surface accuracy and the improvement of quality of the production costs are also increasing. The following table shows the gear on the performance of their manufacturing costs, it is AGMH (USA Gear Manufacturing Association) DIN (Germany Gear Manufacturing Association) developed the data. The higher the value that the tooth of the smaller size of tolerance. Attention to costs arising from changes in the rate of change.

Summary

● many parts of the complex shapes can be mounted, turning, milling and end, Broaching to process. Milling is one of the most commonly used method, because it can

be processed to various parts of complex shape.

● Although the three processing technology similar to turning, drilling the processing methods, but the latter processing a multi-bladed knives and more variable in the shaft to the required processing components.

● these machine tools are computer-controlled, flexible management.

● gear on the front in addition to forming processing methods, gear also can be used machine tool production (generating profiling cutting and processing), which has a high dimensional accuracy and surface roughness. Shaving latter, polishing, grinding, and other follow-up processing technology to improve the tooth surface roughness and dimensional accuracy.