Automotive Cardan Shaft: Analysis of Manufacturing Cost-Jiangsu Sitong Cardan Shaft Co.,Ltd
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Automotive Cardan Shaft: Analysis of Manufacturing Cost

Views:45     Author:Cardan Shaft Manufacturer     Publish Time: 2020-06-06      Origin:Sitong Cardan Shaft Co.,Ltd

1. The role of automotive cardan shaft



The automobile cardan shaft is a circular object accessory that can transmit power between two shafts with different axis centers or even change in relative position during work, and connect or assemble various accessories to move or rotate.

 

They act on the wheel drive devices such as steering drive axles and disconnected drive axles, and are mainly used for power transmission in cars. When the car is driven by the rear wheels, the cross shaft type universal joint transmission shaft is often used; when the car is driven by the front wheels, the constant velocity universal joint is often used.

 

Some high-end cars also use constant velocity ball heads. In general, the role of the automobile cardan shaft is to transmit power between the two shafts with different axis centers or even between the two shafts whose relative position changes continuously during the work process.


2. Use of automotive cardan shaft




The use environment and requirements of automobile transmission shaft The automobile cardan shaft generally forms the automobile transmission system with the clutch, transmission, final reducer, differential and half shaft. It mainly uses the power transmission of various types of cars.

Requirements:

1).It is strictly forbidden for cars to start with high-speed gears.

2). It is strictly forbidden to overload or speed the car.

3). The working condition of the cardan shaft should be checked frequently.

4). Always check the tightening of the drive shaft hanger, whether the supporting rubber is damaged, whether the connection parts of the drive shaft are loose, and whether the drive shaft is deformed.

5). In order to ensure the dynamic balance of the cardan shaft, always pay attention to whether the balance welding piece is de-welded. The new drive shaft assembly is provided as an accessory. When installing the new drive shaft, pay attention to the assembly marks of the telescopic sleeve and ensure that the flange fork is in a plane. When repairing and disassembling the drive shaft, the assembly mark should be printed on the telescopic sleeve and the flange shaft, so as to keep the original assembly relationship unchanged when reassembling.



3. Types of automobile drive shafts






Cardan shafts can be classified according to their universal joints. According to whether the universal joint has obvious elasticity in the direction of torsion, it can be divided into rigid universal joint transmission shaft and flexible universal joint transmission shaft.

 

The former relies on the hinge connection of parts to transmit power, while the latter relies on elastic parts to transmit power and has a buffering and vibration reduction effect. Rigid universal joints can be divided into unequal velocity universal joints, quasi-constant velocity universal joints and constant velocity universal joints.

 

Constant speed and unequal speed refer to whether the driven shaft rotates with the driving shaft, whether the rotational angular rates of the two are equal. Of course, the average speeds of the driving shaft and the driven shaft are equal. The angular velocity of the main and driven shafts is still the same when the angle between the two shafts changes. It is called a constant velocity universal joint or constant angular velocity universal joint.


4. Material selection of automobile cardan shaft




The selection of materials should pay attention to the following points in the selection of automotive cardan shaft materials:

 

First, because it needs to withstand static and dynamic loads, it should have sufficient strength.

 

Second, we should also consider the degree of winding caused by twisting or bending when transmitting power.

 

Third, the contact between the automobile cardan shaft and the bearing will produce friction and wear, so it should have sufficient wear resistance.

 

Fourth, it should have fatigue resistance for alternating loads that are subjected to vibration or shock.

 

Fifth, it should be easy to perform heat treatment and surface hardening, and can obtain sufficient hardness. Finally, toughness should also be considered, and full attention should be paid to the inspection of defects.

 

Medium carbon steel has less harmful impurities and non-metallic inclusions, strict chemical composition control, high plasticity and toughness, and is mostly used to manufacture important parts.

 

After proper heat treatment (tempering, surface quenching, carburizing, etc.), good comprehensive mechanical properties can be obtained to achieve parts that are tough at the heart and wear-resistant on the surface. It can meet sufficient strength, stiffness and a certain toughness, good wear resistance, high fatigue strength and good machinability, that is, the spindle has good comprehensive mechanical properties.



5. Selection of forming method of automobile cardan shaft




The specific forming method of the automobile cardan shaft is selected as die forging on the die forging equipment.

 

The high-strength forging die is used to make the metal blank pressurized in the die cavity to produce plastic deformation, and the processing method for obtaining the desired shape, size and internal quality forging, This is called die forging.

 

During the deformation process, due to the restriction of the flow of the metal blank by the die bore, a die forging that conforms to the shape of the die bore can be obtained at the end of forging.

 

Compared with free forging, die forging has the following advantages: higher production efficiency. When die forging, the metal changes.

 

The shape is carried out in the cavity, so the desired shape can be obtained quickly. It can forge forgings with complex shapes, and make the distribution of metal flow lines more reasonable, and increase the service life of parts. The size of the die forging is more accurate, the surface quality is better, and the machining allowance is smaller. Save metal materials and reduce the workload of cutting. Under the condition of sufficient batch, it can reduce the cost of parts.

 

The die forging operation is simple and the labor intensity is low. Die forging is usually divided into open die forging, closed die forging and multi-directional die forging according to the type of die; according to the equipment used, it is divided into hammer die forging, hot die forging press die forging, screw press die forging 、Hydraulic press die forging, flat forging machine die forging and electric heating upsetting, etc. Hammer forging is widely used in production.

 

The die forging hammer has a fast impact speed, a large impact energy, and the weight of the impact can be arbitrarily controlled by the operator, so it has good adaptability to forgings, and can forge various complex shapes of forgings under 1 kg to about 200 kg, such as engines Connecting rod, crankshaft, car universal joint, front beam and various gears. Hammer forging has high productivity and less equipment investment.


6.Selection of machining method for automobile cardan shaft



Selection of processing method The choice of processing method for automotive cardan shafts is turning and grinding.

 

 

The technical characteristics of turning are:

 

(1) it is easy to ensure that the workpiece has a high position accuracy between various machining surfaces;

(2) it is suitable for the finishing of non-ferrous metal parts;

(3) the cutting process is relatively stable;

(4) the tool is simple

(5)  higher productivity.

 

The characteristics of the grinding process are:

 

(1) , the machining accuracy is high and the surface roughness value is small;

(2) the second grinding wheel is self-sharpening.

(3) high-hardness materials can be processed;

(4) the grinding temperature is high;

(5) the radial cutting component is larger.

 

According to different process objectives and requirements, the grinding processing methods are usually divided into four methods according to the grinding processing form of the grinder product and the processing objects: rough grinding, semi-finish grinding, fine grinding, and mirror grinding according to the grinding accuracy , Super-finishing; cut into grinding according to the feed form, longitudinal grinding, slow feed grinding, non-feed grinding, constant pressure grinding, quantitative grinding.;

 

according to the grinding form divided into abrasive belt grinding, centerless grinding Grinding, end grinding, peripheral grinding, wide grinding wheel grinding, profile grinding, profiling grinding, oscillating grinding, high speed grinding, strong grinding, constant pressure grinding, manual grinding, dry grinding, wet Grinding, grinding, honing, etc.;

 

according to the processing surface divided into external grinding, internal grinding, surface grinding and sharpening. Grinding processing has a wide range of applications. He not only finishes the inner and outer cylindrical surfaces, inner and outer conical surfaces, flat surfaces, various grooves, threads, gears, splines and various forming surfaces, but also can be general Processor It is difficult to process all kinds of high hardness materials for finishing.

 

With the development of new technologies such as precision grinding, high-speed grinding and powerful grinding, the application fields of grinding processing are also expanding, such as grinding instead of scraping in finishing, and grinding instead of planing in roughing.

7.Heat treatment of automobile drive shaft




The choice of heat treatment of automobile cardan shaft is normalizing and modulation treatment. Normalizing is a heat treatment process in which subeutectic steel is heated to 30-50C above Ac3, 30-50C above Accm, and then kept in air to obtain a pearlite structure.

 

For medium carbon steel, normalizing can make the structure uniform and fine, and prepare the structure for quenching treatment. Quenching + high temperature tempering = quenching and tempering. Quenching and tempering is a double heat treatment of quenching and high temperature tempering, and its purpose is to make the workpiece have good comprehensive mechanical properties.

 

The heat treatment of the transmission shaft is that the whole shaft is rolled into a bar and then normalized. After heating at 840-860°C-air cooling after a fixed time, a ferrite + pearlite structure is obtained, and a good cutting performance is obtained.

 

The whole after processing Carry out quenching and tempering heat treatment, generally 840-860°C after heating for a certain period of time, oil quenching, and then carrying out high temperature tempering at 550-650°C to obtain tempered sorbite structure with good strength, toughness and plasticity The comprehensive mechanical properties (torsion resistance, bending resistance, no brittle fracture), and then finishing the spline, the spline hardness is low (about HRC35-40) is not wear-resistant, and the spline needs two The secondary heat treatment is strengthened.

 

At present, most of them are high-frequency induction heat treatment to obtain cryptocrystalline martensite. The hardness of the spline surface can reach HRC58-62, which has a high anti-wear life.


8.Material comparison of automobile cardan shaft



Medium carbon steel and gray cast iron have good wear resistance and good cutting performance. And the compressive strength of gray cast iron is also equivalent to that of medium carbon steel.

 

However, due to the severe fracture of the flake graphite in the gray cast iron to the substrate, it is easy to cause stress concentration at the sharp corners of the graphite, so that the tensile strength, plasticity and toughness of the gray cast iron are much lower than that of the medium carbon steel.

 

The main function of the automobile cardan shaft is to support the slewing body and transmit power. Working conditions-generally withstands alternating torque and tension and compression loads, and the journal and key parts are subject to greater friction and wear. Therefore, it is better to choose medium carbon steel than gray cast iron.

 

The automobile cardan shaft is an important part of the automobile, which requires high precision, smooth surface, and can be mass produced.


9. Cost accounting of automobile cardan shaft




It is cheaper and cheaper to manufacture automobile cardan shafts with medium carbon steel than alloy steel, and the die forging production efficiency is high, which can produce more products within a certain time, saving labor costs and other related manufacturing costs. Moreover, the use of ordinary processing techniques such as turning and grinding does not incur high processing costs. Compared with annealing, normalizing saves more capital.



10. Cardan shaft development trends




The disadvantage of the universal joint cardan shaft is that the amount of metal is large, it is easy to vibrate, and the reliability is not high enough.

 

The most fundamental way to eliminate the above shortcomings is to replace the metal with a polymer material. The experience of many foreign automobile companies proves this point. For example, the United States Grantze, Spasser (Glanzer Spicer) is preparing to produce drive shafts from synthetic material tubes, which are first used on 4x4 cars.

 

The Soviet Automobile Research Institute has also developed this series of cardan shafts for cars or trucks. Therefore, how to develop advanced materials to overcome the shortcomings of automobile cardan shafts is the development trend of cardan shafts.



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