Three eccentric metal hard seal butterfly valve sealing surface processing method

1 overview

The sealing surface of the three eccentric metal hard seal butterfly valve is oblique conical surface, and the contact between the valve body seal ring and the butterfly plate assembly sealing ring is surface contact. Its working principle is that the butterfly plate assembly is directly driven by the torque of the driving device, so that the butterfly plate assembly sealing ring and the valve body sealing ring are fully in contact with the elastic deformation and sealing. As a kind of high performance valve, three eccentric metal hard seal butterfly valve has the advantages of good corrosion resistance, reliable sealing, small opening torque and so on. Three-centric hard seal electric butterfly valve, butterfly plate combination sealing ring material is composite stainless steel plate and asbestos plate sandwich layer combination, the processing quality of the valve body sealing ring and butterfly plate combination sealing ring directly determines the butterfly valve sealing performance.

2 Processing technology

From the analysis of the structure characteristics of three eccentric metal hard seal butterfly valve, butterfly plate assembly parts sealing ring for stainless steel plate and asbestos plate assembly parts, the valve body sealing ring for hard alloy, high hardness, feed is difficult to control, not easy to process molding, and machining surface roughness requirements are very high. In order to ensure the processing requirements, the process for the body or butterfly plate assembly rough machining - body sealing ring surfacing hard alloy - 12h heat treatment to eliminate thermal stress - rough car sealing surface of the upper tooling - fine car sealing surface of the upper tooling - grinding sealing surface of the upper grinding head - body and butterfly plate assembly boring hole - strength test - seal test.

3 Processing tooling

The sealing surface (machining surface) of the butterfly plate combination sealing ring and the valve body sealing ring are inclined cone. The Angle between the center line of the cone of the valve body sealing ring and the vertical line of the space is 8°, and the Angle between the center line of the cone of the butterfly plate assembly sealing ring and the vertical line of the space is 8°. Therefore, the machining tooling of the valve body sealing ring and the sealing ring of the butterfly plate assembly are designed.

4 Valve body sealing ring processing

The sealing ring of the valve body is welded in the valve body. In 2.5m vertical car, the welded body is clamped on the valve body sealing ring processing tooling, and the vertical tool rod is rotated 8°. According to the design requirements of the drawings, the tool is taken along the direction of the conical bus after alignment, and the car reaches the size before the stainless steel welding. Then surfacing stainless steel, finally welding the welded stainless steel body on the upright car, according to the above method to the valve body sealing ring to the drawing requirements. Finally, a grinding head is installed on the vertical tool rest to grind the valve body seal ring to meet the roughness requirements of the drawing design.

5 Butterfly plate assembly sealing ring processing

The sealing part of butterfly plate assembly is the sealing ring. The sealing ring is a inclined cone structure with a cone tip Angle of 16° and a thickness of 13.5mm. It is composed of 5 layers of asbestos board and 4 layers of stainless steel board. The sealing ring must be assembled together with the butterfly plate and pressure ring to prevent the warping of the stainless steel plate and asbestos plate in the interlayer of the sealing ring during processing. According to its structural characteristics, the butterfly plate assembly sealing ring using the following processing methods: (1) in the 2.5m vertical car respectively on the butterfly plate and the pressure ring of each stop processing to the drawing requirements of the size, the outer circle is not processed; (2) Drill the pressure ring and tap the butterfly plate according to the requirements of the drawing; (3) The pressure ring, sealing ring and butterfly plate shall be assembled according to the drawing. The butterfly plate assembly assembly shall be fastened to the valve body assembly with bolts, and then the butterfly plate assembly shall be clamped on it. Rotate the tool rod by 8° to the grinding size of the pressing ring, sealing ring and butterfly plate; ⑷ With the same thickness of steel plate for the sealing ring, the car pressure ring, butterfly plate taper to the drawing size; (5) If the tooling does not move, reassemble the pressure ring, seal ring and butterfly plate according to the requirements, and then install a grinding head on the vertical tool rest to grind the seal ring so that it meets the roughness requirements of the drawing design.

Shaft hole processing of valve stem

Put the butterfly plate assembly into the body, adjust the relative position of the butterfly plate assembly and the body, pour into saponification liquid, no leakage within 5 minutes, the butterfly plate assembly pressing, boring the body and the butterfly plate axle hole.

Using this process to process the valve body seal ring and butterfly plate combination sealing ring, easy to operate, high efficiency, can well ensure the sealing surface of the geometric accuracy.