Shibello anti-loose nuts and taps for heavy duty drive axle applications

    

After the reorganization of China National Heavy Duty Truck in 2000, it has grown from an annual output of less than 10,000 vehicles to nearly 200,000 heavy-duty trucks per year. It has become a leading company in the heavy truck industry. There are many secrets to its success, and the development and application of new technologies are emphasized. Constantly meeting customer needs is necessarily one of them.

In 2009, in order to meet the demand of the mining vehicle market, the company developed a special model suitable for use in the mine environment. Due to the harsh environment, the AC16 mining axle produced by the Heavy Duty Truck Box Company in 2009 showed many cases of feedback. The oil leakage failure occurred in the joint position between the reduction and the axle housing, and the quality of the bolt was loosened by the service station personnel.

Original structural failure analysis

Through the failure analysis of the AC16 mining axle, it was found that the main bolt was loose and the original structure adopted a common anti-loose structure, that is, a spring washer and a threaded fastening rubber. The use environment and overload phenomenon made the conventional anti-loose technology dwarf. . Due to the looseness of the nut, a slight amount of slippage occurs between the axle housing and the main reduction, so that the connecting bolt between them is broken, and the screw hole of the axle housing is cracked.

improve proposals

In order to solve the above problem of the looseness of the drive axle nut, our company's technical personnel and the quality department after-sales service room, heavy truck service station and other units have repeatedly discussed and confirmed that due to the large tonnage of our company's heavy-duty vehicles, complex working conditions, the implementation of fasteners Gluing, spring Washers, double studs and other solutions are not obvious; actively find relevant anti-loose technology, obtain industry resource information, with the support of manufacturers and leaders, we cooperate with Shanghai Technical experts from Special Precision Fasteners Co., Ltd. conducted research and analysis on the oil leakage failure of heavy-duty vehicle drive axles, and determined the implementation plan for testing and verification using the company's anti-loose technology.

1. Firstly, the SBI nuts installation experiment is carried out at the service station where the customer feedback amount is concentrated. The nut is replaced and the nut usage is tracked for the vehicle with oil leakage; three experimental schemes are adopted:

(1), 16 nuts are all replaced with Shibello anti-loosening nut tracking test;

(2), replacing 4 of the fine nut with the Schmidt lock nut tracking test;

(3) Change the 12 coarse nuts into the Schmidt locknut tracking test.

2. If the effect of the use is obvious, the second stage is carried out, that is, the processability of the anti-loose technology is certified, and the processing technology of the axle housing is adjusted. The performance and cost of the Spiral tool and the means of implementing the test are determined. .

3. Report the situation and results of the technical experimental research to the design department, and recommend the structure suitable for the anti-loose technology to improve the quality and design level of the whole vehicle, reduce the failure rate of after-sales oil leakage, and promote the defense in the company. Pine technology.

The principle of the anti-loose solution

The squid thread is essentially different from the normal standard thread, and the sturdy thread can effectively solve the loosening problem. Because the Schmidt thread has a unique structure. There is a 30-degree wedge-shaped bevel at the bottom of the female thread. When the bolts and nuts are tightened to each other, the tip of the bolt is tightly placed on the wedge-shaped inclined surface of the sturdy thread, resulting in a large locking force. . Due to the change in the angle of the tooth, the normal force generated by the contact between the threads is at an angle of 60 degrees to the axis of the bolt, rather than a 30 degree angle like a normal thread. Obviously, the normal pressure of the Squid thread is much greater than the fastening pressure, so the resulting anti-loose friction force will inevitably increase greatly. At the same time, when the male thread crest is engaged with the Spitzgium thread, the tip of the tooth is easily deformed, so that the load is evenly distributed over the entire length of the contact spiral (see Figure 1), avoiding the common standard thread engagement. More than 80% of the total load is concentrated on the thread faces of the first and second teeth.

In some cases, the effect diagram of the anti-spinning nut was used for 23 days .
Technical requirements for processing and assembly

Through consultation, the recommendations and recommended parameters of Shanghai Deute Precision Fastener Co., Ltd. were adopted, and the basic operation requirements for the products of the heavy truck company were formulated: 1. The outer thread should be processed without decarburization layer, and the outer diameter of the thread should be Be sure to meet the requirements of the national standard. 2. Keep the mounting surface of each component clean before assembly. 3. Apply a little cleaning oil to the external thread surface before assembly. 4, pre-tightening torque: coarse teeth 90N.m; fine teeth 120N.m. 5. Provisions have also been made for forced re-tightening.

Performance and reliability verification

In June and July of 2009, QC Bridge Box Company and Shanghai Deote Precision Fastener Co., Ltd. jointly conducted verification experiments at Beiyue Service Station in Quzhou City, Shanxi Province and Haifeng Service Station in Wuhai City, Inner Mongolia. The test results are as follows: :

It can be seen from the test that there is a great difference between the use of the Schmidt and the partially used Schmidt loose nuts, and the use of the Schmidt locknuts and the use of the Schmidt lock nuts are also very different. However, even if all of the Schmidt loose nuts are used, the nuts will loosen and oil leakage will eventually occur, and such problems are not completely solved.

After the structural analysis, it is considered that there is a problem in the way of fastening the fasteners in this part. Here is a double-headed stud coupling scheme: one end is screwed into the base of the axle housing, and the other end is tightened with a Schmidt locknut. Although the outer end can be made loose, the section of the double-headed stud screwed into the base of the axle housing cannot guarantee the actual anti-loose requirement due to the common threaded coupling mode.

The technicians of the Heavy Duty Bridge Box Company decided to further improve the bolt connection scheme: the shell shell was machined with the Shibong tap, and the Shibong thread was machined on the axle shell, and then screwed in with ordinary standard bolts.

The improved axle structure has simple structure, greatly improved reliability, reduced machining difficulty, reduced installation components, simple installation and installation, greatly reduced overall cost, and can be widely used in large quantities. Heavy Duty Truck Box Company switched this new technology from January 1, 2010. After one year passed, the after-sales service department never received the loosening of the axle housing of the AC16 bridge after adopting the new technology. The batch complaints in the aspect completely solved such problems, and directly saved the company's after-sales service losses of millions of yuan, and at the same time improved the reputation of product quality.

Conclusion

After applying the anti-slipping nut and tap to the heavy-duty vehicle drive axle, it effectively reduces the failure of the connecting gear bolt to cause the oil leakage of the main reducer connection plane. By the end of 2010, including the heavy truck mining vehicle axle. A number of products have begun to apply the technology, and the effect is obvious, which saves the after-sales cost for the enterprise; the application of the new technology brings about the reduction of the processing cost, and the long life of the Spitzer cone provided by Shanghai Deote Precision Fastener Co., Ltd. The number of threaded holes that can be machined by one tap exceeds the life of high-speed steel ordinary taps by 10-12 times, while the average taper of the same specification is only 20m in average life of the same material; the life of the Shibong tap is 200-220m. This not only improves the production efficiency, but also reduces the workload of the operator's tool change; because the assembly process does not need to apply anti-loose rubber, no spring washers, etc., reducing the procurement cost of accessories and standard parts. China is gradually implementing the truck recall system, which is both an opportunity and a challenge for China National Heavy Duty Truck Co., Ltd.; China National Heavy Duty Truck is willing to adopt new technologies to solve user problems. It is China’s automobile industry to go abroad and become a strong global brand. cornerstone!

Fastening For Urban Transit

Main components:

2 Rail clip
2 T bolts with hex nut and washers
4 Sleeper screw
4 Lock washers
4 Plastic Inserts
1 Rail pad
2 Insulator
1 Vibration absorber
1 Resilient sole pad

Components description:

W type Rail Elastic Clip/ SKL clip

Metro Fastening System,Underground Fastening System,Fastening For Light Rails,Fastening For Tram

TAICANG ZHONGBO RAILWAY FASTENING CO., LTD. , https://www.railfastener.com