Research and development of anti-shedding and variable-type locknut


-), male, Hebei Jingxian people, engineers, engaged in mechanical and electrical equipment management. With the development of fully mechanized mining equipment to heavy-duty and high-power, the requirements for fasteners are getting higher and higher, especially the scraper nut anti-loose technology of the scraper conveyor. The original spring washer and nylon anti-loose can not adapt. Large equipment

-), male, Hebei Jingxian people, engineers, engaged in mechanical and electrical equipment management.

With the development of fully mechanized mining equipment to heavy-duty and high-power, the requirements for fasteners are getting higher and higher, especially the scraper nut anti-loose technology of the scraper conveyor. The original spring washer and nylon anti-loose can not adapt. The need for large-scale equipment production, the scraping of the scraper and the large chain accidents caused by the looseness of the scraper nut often occur. The accidents caused by each working face each year account for about 30% of the accident rate, and the average monthly impact on production More than 48h, a new product is urgently needed to replace the traditional anti-loose fasteners to meet the needs of large-scale mine production. In this case, the electromechanical department of Sima Coal Mine and Ningbo Xiangxiang Large Fastener Co., Ltd. jointly developed the defense. The detachable tooth type locknut was successfully applied to the 1101 fully mechanized mining face of Sima Mine.

1 Research content 1.1 Working condition of standard threaded fasteners Fastener products are a kind of versatile and interchangeable parts all over the world, which play the role of combined fastening.

Ordinary standard threaded fasteners, when the torque is small, the locking force is mainly concentrated on the thread surface of the first tooth, and the subsequent thread of the bolt is almost in the "floating" state in the nut, when the torque is applied. When it is large, the first thread generates bending and shear deformation, so that the thread surface of the second tooth is stressed and a locking force is generated. The other threads are still in the "floating" state. If a larger torque is applied, the stress on the first and second thread surfaces of the common standard nut is generally above 80% of the total load, and then the pressing force on each thread surface is successively decreased, or even zero.

Therefore, the force exerted by the ordinary standard nut is concentrated on the first and second thread faces, and the shear and wear damage encountered is very serious, and even a "sliding tooth" phenomenon occurs. Through the analysis of this phenomenon, the true contact surface of the common standard threaded fastener is only the first and second teeth of the nut, and the other teeth are almost in the "floating".

status. If the threaded fastener operates under a vibration load condition, it is easy to overcome the locking force on the thread contact surface and loosen and loosen due to the radial gap in which the external thread moves. This is the root cause of the loosening of common standard threaded fasteners.

To solve the loosening problem of threaded fasteners. Scientists in many countries in the world have done a lot of experiments and research, usually using locking pieces, pins, deformed threads, inserts or chemical glue bonding methods, and even tightening with multiple nuts to solve the looseness of threaded fasteners. Get off the problem. Practice has shown that the above measures, due to its insurmountable shortcomings, and its locking function is only effective once, can not be reused, especially in high temperature or low temperature environment.

Therefore, to a certain extent, the problem of the looseness of the threaded fastener has not been satisfactorily solved for a long time.

In the late 20th century, after long-term research, foreign scientists found that the key to the self-relaxation of threaded fasteners lies in the structural shape of their threads. Theoretical analysis and laboratory tests have shown that to solve the problem of loose fasteners, the geometry of the threads must be redesigned. After a long period of hard work, the United States took the lead in introducing a variable-cut locknut with a 30-claw slope with internal threads, thus achieving a qualitative breakthrough in the anti-loose technology of threaded fasteners.

1.2 Thread structure of the tooth-type locknut This thread shape differs from the normal standard thread shape in that the root of the internal thread has a wedge-shaped ramp that is cut into 30, and the shape of the external thread on the bolt still maintains a standard triangle shape. When the nut is tightened on the bolt or the bolt is tightened in the nut, the external thread is automatically centered in the internal thread, and the externally threaded crest is tightly wedged onto the 30 slope of the internal thread root, and the load is evenly distributed throughout Each tooth of the diameter. Since the crest of each tooth spread over the entire diameter of its entire diameter is pushed tightly toward the wedge-shaped ramp, the possibility of radial displacement of the external thread is eliminated. For this purpose, it has a good anti-loosening effect and is fully threaded.

1.3 Function and quality control of the variable-shaped locknut The variable-cut locknut has a distinctive function. Mainly in the following aspects: 1 excellent anti-vibration and anti-loose ability; 2 system Zhang Lixin: anti-shedding variable-type locknut research and development application can be freely rotated, especially suitable for high-speed assembly occasions; 3 repeatable Use, and the more times the system is screwed on and off, the better the locking performance; 4 all the teeth in the length of the screwing are evenly stressed, no slippery teeth, and have a significant effect on overcoming the problem of easy sliding of soft materials; No need for any auxiliary locking elements, such as spring washers, stop washers, etc.; 6 the force of the force between the internal and external threads is reasonable, has a stable mechanical locking state, increases the shear resistance, and improves the use of bolts and nuts. ;7 The application environment is wide-ranging and is not affected by drastic changes in temperature.

In foreign countries, the variable-shaped locknut has been widely used in aerospace, aviation, machinery, transportation, electric power and bridge, construction steel structure and other fields, and has achieved good results.

The tooth-type anti-loose technology was introduced to China in 1997 and has been adopted by the automobile, machinery and transportation industries. After necessary experimental tests and field trials, it has achieved good results, has been promoted and used, and has considerable market prospects. .

At present, the basic performance software of this technology is controlled by foreign companies. Domestically, the necessary theoretical research has not yet been developed in this respect. The complete technical standards for the characteristics of Chinese users have not yet been developed, and taps and gauges have not been localized. It can be explained that although it has been partially used, there is still some technical blindness.

In summary, it is very necessary and urgent to speed up the development and development of the variable-tooth locknut technology, especially to develop the variable-tooth locknuts suitable for dynamic static state of coal mines to meet the heavy-duty high-power equipment of coal mines. The need is even more prominent.

According to the scientific and technological development at home and abroad, combined with the actual needs of China, after research and experimental analysis and theoretical analysis, the researcher of Sima Mine and Ningbo Xiangxiang Fastener Co., Ltd. found that the key technology of the variable-shaped locknut is how to test Is the produced variable-shaped locknut qualified? That is, the gauge inspection system of the variable-shaped locknut. The truly effective function of this gauge inspection system is to accurately verify all the features required to assess thread quality. Here, the key feature to be tested is the 30 wedge-shaped ramp, in particular the 30-slope, and this ramp has a correct position in the radial direction to accommodate both the maximum and minimum outer diameters of the external thread.

Through technical research, a three-plugging system was designed, consisting of one general rule and two stop rules. The general rule is made into a full thread full shape. If it "passes", it tells us that the medium diameter, the large diameter, the small diameter, and the integrated formed crest are in the correct position, allowing the standard external thread of the maximum tolerance to be rotated. If the two stops can stop, it tells us that the slope and the remaining sides are suitable for matching the smallest standard external thread. The reason for using this two stops is because we need to know whether the change in the diameter is narrow enough. This is related to the slope. It is also necessary to know whether the slope is sufficiently low so that the slope can be transferred to the remaining tail. At the same time, the bolt with the smallest outer diameter can be properly placed on the slope.

The 16th Zhu Lili 2 to this, the internal thread structure design to change, to solve the technical problems of the thread fasteners self-release is completely solved. At present, on the basis of the completion of internal thread research, design and demonstration, a full range of tool taps based on variable-toothed threads and a complete set of gauges for detecting the quality of the deformed nut have been developed, and the mass production specifications are complete. The ability to change the type of locknut, and the corresponding enterprise standard for the variable-shaped locknut, as well as the quality control procedures for the production of the variable-cut locknut and the user guide for the variable-cut locknut. The transfer process from small batch production to mass production has been realized.

2 Pilot application of the first batch of domestic variable-size locknuts for domestic mining. In June 2005, the underground application test was carried out in the 1101 fully mechanized mining face of Sima Coal Mine of Chun'an Group. The M24 variable-proof locknut was applied to SGZ-800/800 scraper. Conveyor and SZZ960/250 bridge transfer machine scraper fastening, M30 variable tooth lock nut for SGZ830/800 scraper conveyor scraper fastening, M36 variable pressure locknut for crusher and transfer machine Connection. After two months of operation, the M36 nut showed excellent anti-shock and anti-loose performance after the first tightening. The M24 and M30 scraper nuts normally take 7~8d time due to the long tightening period. Under dynamic conditions, After the vibration and friction between the large and small squeegees are combined, the individual nuts are loosened, and they fall off if they are not re-tightened in time. For this situation, the technical personnel of both sides have scientifically demonstrated that they have been installed on the variable-proof locknuts. An anti-off nylon ring solves this technical problem. Through the application of the M24 variable tooth lock nut, the overall performance of the nut is improved, adapting to the actual situation of the Chinese coal mine, and according to the operation of the equipment, the well is tight. TL type preset torque wrench and afterburning torque wrench have been developed for factors such as solid environment and tightening cycle, and relevant information such as the use of anti-shedding and varnished locknuts have been prepared to make anti-shedding and anti-loosening nut technology. Formed a complete system engineering from production, application and management.

3 Application standards and instructions for use of anti-shedding and anti-loosening nuts 3.1 Environmental temperature. Non-plated nuts: -50 ft~+300 弋; electroplated nuts: -50 弋~+230 弋.

Environmental conditions. Nuts should not be used in corrosive environments.

3.2 The strength matching of the threaded connecting pair is to ensure that the threaded tripping does not occur when the stress in the threaded connecting pair reaches its guaranteed load or yielding load, and the corresponding external threaded parts should be matched with the provisions, see Table 1. Table 1. The strength of the connection pair matches the performance level of the internal thread. The performance level of the externally threaded part is 5.8 and below and the following is 8.8. Note: The heat-treated shank locking nut is not recommended and the performance is lower than 8.8. The screw thread is matched with the 3.3 threaded connection pair. The precision is matched with the variable-type locking locknut. The thread precision is above 6H. In order to properly play the locking and anti-loosening ability, the threaded external thread is required to be 6g or 5g. 3.4 Mounting direction The thread of the locking type locking nut is directional. Therefore, be sure to look at the surface without the iVS mark as the nut bearing surface. The male screw must be screwed from the bearing surface. Otherwise its locking ability will be less than the level of ordinary threaded nuts.

3.5 Mounting torque variable-tooth locking locknut The locking anti-loose function must be visible after the load is applied. Therefore, the threaded sub-belt must be in a stressed state during use, and its load must be sufficient, otherwise it will be Can not play the lock against the loosening effect.

Table 2 shows the preload of the recommended squeezing locknuts.

Table 2 Variable-tooth locking type anti-loose mother-loading pre-tightening performance nut specification level In the lubrication state, the installation torque should be controlled according to the specified pre-tightening force, see Table 2, the installation torque is calculated by the following formula: m' is the twisting The coefficient is determined by the test; P is the pre-tightening force, kN; d is the thread size of the bolt, mm. Moment, see Table 3. The recommended moment values ​​listed in the table are calculated on the basis of the theoretical factors combined with the application of the moment. result.

It is recommended to install and select the upper limit of the recommended torque in the lubrication state when using the variable-tooth locking locknut. The wrench should use a torque wrench with high precision and convenient control. Guaranteed load and recommended installation force of variable-tooth locking locknut Table 3 Variable-tooth locking type Locking-proof mother-prepared load and installation torque (in the lubrication state) Guaranteed load installation torque 91 Bubao load 17.2/Mounting torque Guaranteed load installation torque 5 guarantee load installation torque 4 development and use of torque wrench 4.1 Development of torque wrench In order to adapt to the application and promotion of variable tooth locknut, TL type preset torque and afterburning torque wrench were developed, from 200 4.2 How to use the torque wrench Set the torque value of the wrench according to the specification and installation torque of the nut. When setting the torque value, insert the hexagonal adjustment key of the torque wrench into the end of the wrench, then rotate and adjust the scale tick to Pull out when the value is needed.

Install the corresponding sleeve on the wrench head, and wrap the fastener, and then slowly apply force on the surface. When tightening to the signal “嗒” (the pre-tightening torque value has been reached), (continued on page 70) Masked, balance bar and other hollow steel pipe, the door frame structure is the number of detachable doors, improve the safety of the folk damper, and also reduce the type, the standard bolt connection between the large parts, together with the positioning material Fees, labor costs, maintenance fees, in the long run have a good economic sales and positioning beams to ensure the reliability and accuracy of the installation of the damper. benefit.

2 Promotion and application of pressure-balanced damper 3 suggestions for the performance characteristics of the damper. During the construction of the well, the pressure-balanced damper of Changzhi Kean Co., Ltd. was installed between the main entrance and exit of the well, and the material construction and construction of the damper was constructed. The indicators such as difficulty level, air leakage degree, and opening force are compared with traditional wooden dampers. It can be seen from Table 1 that the pressure balance damper can fully meet the safety requirements, which not only effectively improves the ventilation conditions, but also reduces the wind due to The damper is opened in the opposite direction, which may cause the vehicle to crash into the damper at the beginning of use. Therefore, in the initial stage of operation, the training of the employees must be done well.

It is necessary to further improve the automatic protection device for the car before and after the damper, effectively blocking the sports car so as not to damage the damper.

Table 1 Performance difference between wooden damper and pressure balance damper Project Wood damper pressure balance damper wall thickness / mm per square meter section brick / block construction difficulty level need to construct forward and reverse damper, it is difficult to open difficult Easy to seal the situation Single-sided seal Double-sided seal Air leakage /% Wind condition Reverse air door air-proof two-way air isolation, no reverse damper operation is required. Facade is forced to be heavy, maintenance is difficult. Two-way non-forced situation, running balance damper The impact strength of the mine is poor and the impact is high. The overall strength is high. The closing effect is automatically closed and the automatic closing is closed (upper page 55) to complete the tightening operation.

4.3 Fastening method for scraper squeegee Firstly apply lubricating oil to the bolt rod, first tighten the middle nut with a torque wrench, and then tighten the two nuts.

After the first pass is completed, tighten the second pass from the middle nut.

4.4 anti-shedding teeth anti-loose scraper with nut tightening cycle anti-shedding teeth anti-loose scraper nut put into use, the first time after tightening once according to the torque requirements, the equipment runs the next day, the last day, the last day, seven days Tighten the second time; use the seven-day tightening for the third time. Check the nut for looseness after one month of use. If it is loose, it needs to be tightened again. Check it once a month.

5 Application effect M24 variable tooth locknut with anti-shedding nylon ring was installed. In October 2005, the SGZ800/800 scraper conveyor on the rear part of the 1101 fully mechanized mining face of Sima Mine of Chun'an Group was carried out. Application, this application completely manages the nut according to the standard and instructions. After the first tightening, the second tightening is started the next day. The eighth day is tightened for the third time. The M24 and M30 nuts are each selected as the test. Target, check and test once a month, each time with the higher precision adjustable torque wrench to test the residual torque of the nut, the test results, see Table 4 anti-shedding teeth type anti-loose tamper detection table loose condition detection date MM -8 installation residual torque residual torque average October 4th November 10th December 17th January 17th February 17th March 17th April 18th May 18th June 15th 6 conclusions anti-shedding The successful development of the tooth-type locknut has filled the gap in the domestic coal machine industry, shortened the technical gap between domestic and foreign countries, solved the problem of dynamic tightening for the heavy-duty president of China, reduced the accident rate and improved the operating rate. Reduced the labor intensity of workers and promoted the machine

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