Detailed explanation of technical transformation of three-way lock

SHANGHAI SHIBANG MACHINERY CO., LTD is one high-tech enterprise, which involves R&D, production, sales and service as well. In the past 20 years, we devote to producing mining equipments, sand making machines and industrial grinding mills, offering expressway, rail way and water conservancy projects the solution of making high grade sand and matched equipments.

Detailed explanation of technical transformation of three-way lock air valve of vertical roller mill

Vertical mill three-way air lock valve is a device for feeding materials to the vertical roller mill. As a wind sweeper, the vertical roller mill requires as little air leakage as possible to meet the needs of the production process. The three-way valve is widely used in various vertical roller mill systems due to its better air-locking effect.
The vertical roller mill needs to work under negative pressure. Therefore, the three-way air lock valve must reduce the leakage of the system as much as possible while ensuring the normal feed amount of the vertical roller mill, and realize the air lock function. However, due to the harsh working environment of the three lock dampers, the dust is large and the wear is serious. Some problems such as “wearing of the valve plate and damage of the non-drive side bearing” often occur, which affects the normal operation and technical specifications of the mill system. The SBM heavy machine introduced the technical transformation of the three lock dampers with good results.

1. Problem analysis

In the actual use process, on the one hand, the wear layer of the valve body gradually wears and peels off due to the feed impact of the material, and the gap between the valve plate and the bottom plate increases. As a result, the pressure difference of the vertical roller mill system is reduced, the grinding temperature is lowered, and the mill output is decreased. On the other hand, since the original sealing structure of the non-transmission side bearing of the lock valve is a felt ring seal, dust is easily entered into the bearing, resulting in bearing damage. So forced to stop processing.

To this end, SBM heavy machine technicians have carried out technical transformations and achieved good results.

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2. Transformation method

  • (1) Use the inspection time to repair the three valve plates and the bottom plate to enhance the wear resistance. Re-weld the valve plate and add reinforcing ribs to enhance the tensile strength of the valve plate. At the same time, the D707 tungsten carbide wear-resistant electrode is welded on the impact surface of the valve plate and the bottom plate to a thickness of 3 to 5 mm to enhance the wear resistance of the valve plate and the bottom plate and prolong the service life. In the process of repair welding, it is necessary to ensure that the gap between the valve plate and the bottom plate is ≤ 3mm to ensure the stability of the internal pressure difference and the grinding temperature, which is beneficial to the operation of the mill and the increase of the production time.
  • (2) Using the waste conveyor belt to form the rubber strip (the corresponding size of the width between the two sides of the valve body and the bottom plate), bolted to the back of the valve plate to form a tight elastic contact with the bottom plate to reduce air leakage.
  • (3) Technical transformation of the original sealing structure of the non-drive side bearing of the lock damper. The original felt ring seal was transformed into a “U” type skeleton seal, and a labyrinth sleeve and bearing fit were added. The labyrinth gap was less than 2 mm, and the combined seal structure was effectively used to prevent the intrusion of dust.

3. Transformation effect

After the above technical transformation, and through the verification of the actual operation of the production, the service life of the three modified air lock valves has been improved from about 2 months to about 8 months. Moreover, the transformation cost is low, the structure is simple, and it is worth promoting. The effect comparison before and after the transformation is shown in Table 1.

The working environment of the three-way lock damper is harsh, dust is heavy and wear is serious. Problems such as wear of the valve plate and damage of the non-drive side bearing often occur, which affects the normal operation and technical indexes of the vertical roller mill system. In this paper, the SBM heavy machine introduces the technical transformation of the three-way lock air valve in detail, and the effect is good. It is hoped that the shortage of the existing vertical roller mill can be improved. If you don’t understand anything, you can always consult the SBM heavy machine.

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