Domestic Crankshaft Machining Steps into 3.0 Time –
Tianrun Crankshaft Co., LTD.
 



 What is the heart of a vehicle? Of course, it is the engine. Every one would agree on this point. Then, what is the “heart” of “the heart”? Maybe few can answer this question. Tianrun Crankshaft, developing from agricultural cooperative Blacksmith workshop to a listed company specializing in manufacturing crankshaft for vehicles, Tianrun’s connection to crankshaft represents China’s manufacturing history of crankshaft. Nowadays, with SMTCL, Tianrun continues taking the lead of automobile crankshaft manufacturing industry.

 The “Heart” of “the Heart”

 Automobile’s engine consists of five parts: cylinder body, cylinder head, crankshaft, camshaft and connecting rod. As an important part to bear impact load and transmit power, crankshaft has higher requirements on machining process and accuracy. It is the most difficult one to assure its quality among the five parts. And its quality directly affects engine's performance and service life. The crankshaft production line must have high stability and conveying system of each process must have high reliability. As a result, crankshaft is always called as the “heart” of “the heart”. Tianrun Crankshaft Corporation, ranking the first place in China, third in the world, carried out technical upgrade after going public. Having reviewing various domestic and international production lines, Tianrun finally determined to build production lines with Tianrun characteristics.

 Four Types of Production Lines

 Currently, main crankshaft production lines in China can be divided into the following types:

 Type one is the crankshaft production line built in 1970-80s ,which is made up of domestic manual lathe, grinder and transfer machine. The production line has long work process distance, scattered work processes and low machining efficiency. Manual control causes unstable machining accuracy. It has strong production inflexibility and can nearly produce only one kind of product. Nowadays, this kind of production line has nearly get out of fashion.

 Type two is the production line built in 1990s, which is made up of imported NC lathe, special NC grinder and domestic rigid modular machine tool. Although its machining accuracy and efficiency has been improved greatly, its key component—eccentric NC crank pin grinding machine, which achieves eccentric grinding though eccentric jig, has a low machining efficiency and is difficult to change machining type or upgrade. It is more difficult to change machining type in case of rigid transfer machine.

 Type three is the production line built by overseas production line service provider like Germany’s Rwe Group. Its rough machining process is carried out with journal turn-turn broaching, connecting rod journal high speed internal milling, external milling and soft transfer machine etc.; precision work is carried out with CBN super high speed grinding and trailing type numerical control grinding technology. The machining quality and pace of production line is monitored through information system and work process database. This kind of production line is very expensive. Domestic enterprises can’t affordable to it.

 Type four is the production line built by domestic automobile or engine companies with work process technology through adopting the new technologies mentioned in type three and combing imported equipment and domestic equipment. However, this kind of production line is mainly designed for engine body factory. It is not suitable for specialized crankshaft manufacturer who has high requirements on market adaptability.

 Tianrun Building Production Lines with Chinese Characteristics

 None of the aforesaid four production lines are suitable for Tianrun. Tianrun, even other automobile engine’s crankshaft manufacturers, need the following requirements: first, the production line must be suitable for multi-type and small-lot production and has a high flexibility; second, the production line must ensure quick delivery; last but the most important, the production line should need relatively low early investment. Having compared with several machine tool manufacturers, Tianrun selected Shenyang Machine Tool Co., Ltd. as its partner. Our company's excellent capacity in crankshaft set equipment field has impressed Tianrun and render it entrust us such an important plan to us. In fact, SMTCL has long before demonstrated its excellent performance. In 2005, our company has successfully completed the reconstruction of Guilin Fuda Crankshaft Co., Ltd. which invested over RMB 100 million. After reconstruction by SMTCL, Guilin Fuda has suddenly become a top three steel crankshaft company from an ordinary small private factory.

 Through field study, on the basis of Tianrun’s specific circumstance Shenyang Machine Tool Co., Ltd. provided Tianrun with over twenty kinds of products including NC end milling & center hole drilling machine which has independent intellectual property right , mass centering machine, crankshaft main journal lathe-lathe-pull machine, crankshaft connecting rod journal lathe-lather-pull machine, crankshaft single and double ends oil hole driller machining center with MQL technology, crankshaft two faces holes machining center, crankshaft bearing holes machining machine tool and full automatic balancing machine etc. Then, SMTCL researched and developed connecting equipment such as mechanical hand and logistics system. Finally, a full automatic production line was assembled to apply the automatic machining technology of crankshaft.

Table 1 Comparison of Car Crankshaft Production Lines 

 
Domestic traditional production line 
Imported production line
Tianrun’s new production line
Total number of work processes
28
22
22
Total number of equipments
35~40
22
25
Workers on the production line
80
15
15
Capacity utilization rate
>70%
>85%
>85%
Process technique
>1.00
>1.33
>1.33
Machining accuracy Cylindricity
0.008mm
0.005mm
0.005mm
Surface roughness
Ra0.8μm
Ra0.2μm
Ra0.2μm
Production line flexibility Flexible production, however, its accuracy depends too much on workers’ technical level and large amount of tooling.
Flexible production, it needs more time and cost to change products.
Flexible production, it needs little time and cost to change products.
Annual output
60000
100000
100000
Construction cost of production line
RMB 25~40 million
RMB 150 million
RMB 9 billion

 Up to now, Tianrun has signed 10 crankshaft production line contracts, involving 153 pieces of equipment and a value over RMB 300 million. Now, 75 sets of equipment have been put into operation. Tianrun’s technical reconstruction has stepped out a great step under the support of Shenyang Machine Tool Co. Ltd.. We believe that Tianrun, the emperor of crankshaft, will made more splendid achievement in the world after the 10 new production lines are put into operation.

 
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