Summary of experience in the design of hydraulic valve blocks
1. The shape of the valve block body is generally rectangular hexahedron.
2. The material of the valve block body should be 35 steel forgings or continuous casting billet parts.
3. The maximum side length of the valve block should not be greater than 600mm, and the number of two-way cartridge valve inserts included should not be greater than 8.
4. When the hydraulic circuit contains more than 8 plug-ins, it should be broken down into several valve blocks, which are connected to each other with bolts, and the connection orifice at the joint surface is sealed with an O-ring to form an integral block group. The rectangular performance of the connecting bolts should be not less than 12.9 grade.
5. The main orifice of the block should be designed to minimise flow resistance losses and to facilitate processing.
6. The diameter of the main level orifice is estimated according to formula (1) and selected as follows
D - diameter of orifice, mm;
Q - the maximum working flow rate that can flow through the orifice, L/min;
vmax - the maximum working fluid flow rate allowed in the orifice, m/s.
In general, for pressure orifices, vmax is not greater than 6m/s; for return orifices, vmax is not greater than 3m/s.
According to the formula (1) estimated orifice diameter should be gardened to the standard through diameter value.
7. When the main level orifice and multiple plug-in through, in order to reduce the local flow resistance loss at the penetration, it is appropriate to use the method of partial penetration with the plug-in hole (so that the centre line of the main level orifice and the centre line of the plug-in hole offset). Generally the centre line of the main orifice is tangential to the wall of the plug-in hole. At the same time can also increase the diameter of the aperture, increase the diameter of the passage should not exceed the provisions of GB2877.
8. In order to improve the deep hole process, the design can be considered to increase the hole diameter or use the two ends of the drilling butt method.
9. Design should try to avoid setting complex connections in the body of the valve block control orifice and three-dimensional oblique hole, should make full use of the control orifice within the control cover, or use pilot control block and other special control orifice connection body. The diameter of the pilot orifice should be consistent with the provisions of GB2877. If the diameter of the pilot orifice is reduced due to process requirements, a check should be made to confirm that it does not affect the control requirements of the main stage valve.
10. Inclined orifices should be avoided. Where inclination is necessary, the angle of inclination of the orifice should not exceed 35° and a good seal of the orifice should be ensured. For main-stage inclined orifices, the long axis dimensions of the elliptical orifice resulting from the inclined orifice machining should be marked on the relevant view.
11. When the smaller orifice hole diameter is not greater than 25 mm, the distance between the two adjacent orifice walls shall be not less than 5 mm; when the smaller orifice hole diameter is greater than 25 mm, the distance between the two adjacent orifice walls shall be not less than 10 mm.
12. In order to avoid the deposition of contaminants, for connected orifices, the hole depth should generally be up to the centre line of the orifice with which it is connected.
13. The external oil port of the main stage orifice is generally connected by a flange. For smaller orifices with a through diameter of 25mm or less, threaded connections can also be used. The external oil port of the pilot orifice should be threaded.
14. The process orifice should be plugged with a screw plug, flange and other removable means to facilitate the cleaning, washing and inspection of the orifice. The threads of the screw plugs should conform to the provisions of GB2878. When the location does not allow, for the diameter of the orifice is not greater than 12mm, it is allowed to use the ball up plug to seal.
15. The main level orifice and the main pilot orifice should be set up with the necessary test ports in order to test the working parameters of the hydraulic circuit. The ports should normally be fitted with quick-connect fittings.
16. All external oil ports and test ports of the valve block should be marked with the same mark as the corresponding mark on the hydraulic schematic.
17. the mounting position of the nameplate should be reserved in a conspicuous part of the valve block.
18. The body of the valve block should have a lifting structure, generally using lifting ring screws.
19. When using forging blanks, they should be normalised to eliminate residual internal stress. If necessary, non-destructive testing should be carried out to check its internal quality.
20. The edges should be chamfered 2 x 45°, or 1.5 x 45° when the valve body is small.
21. The oil passage orifice should be kept sharp-edged and not chamfered, but should be deburred. The chamfering depth of the threaded orifice of each pipe joint should be no greater than one-half of the pitch.
22. Remove burrs and flying edges, carefully remove chips and impurities from the orifice, and clean it.
23. Mark the corresponding orifice with a steel mark next to each orifice, which should be no less than 6mm from the orifice (so as not to affect the sealing performance of the O-ring).
24. When the surface of the valve block body is treated with chemical nickel plating, the plating thickness is 0.008-0.012mm.
25. After processing, the valve block body should be protected from rust, dust and other protective measures, the surface should be covered and stored in a clean and dry place.
Hydraulic valve blocks,Design