A hydraulic control system and hydraulic test steel pipe machine oil-water balance system

Abstract

The invention discloses a hydraulic control system and a hydrostatic testing steel pipe machine oil-water balance system with the hydraulic control system. The hydraulic control system comprises multiple master cylinders, a constant pressure variable pump, a proportional pressure reducing valve, a proportional overflow valve, an electromagnetic overflow valve, a prefilled valve and a top petrol tank. The multiple master cylinders are connected in parallel. The constant pressure variable pump is driven by an electrical machine. The inlet of the constant pressure variable pump communicates with the top petrol tank. The outlet of the constant pressure variable pump communicates with the master cylinders. Each of the electromagnetic overflow valve and the proportional overflow valve is arranged between the constant pressure variable pump and the top petrol tank in a communicated mode. The proportional pressure reducing valve is arranged in series between the constant pressure variable pump and the master cylinder. The prefilled valve is arranged between the top petrol tank and the master cylinder in a communicated mode. Pre-sealing compress water filling is carried out towards the testing steel pipe by the proportional pressure reducing valve. The pressure of pre-sealing is stable and the controlled pressure is small. Pressure maintaining is carried out towards the master cylinder by the proportional overflow valve so that the pressure following is stable and reliable and the responsive time is short.

Description

technical field [0001] The invention relates to an oil-water balance system of a steel pipe engine for a hydraulic test, in particular to a hydraulic control system for the oil-water balance system of a steel pipe engine for a hydraulic test. Background technique [0002] The hydrostatic test steel pipe machine is used to carry out hydrostatic pressure test on large-diameter longitudinal submerged arc welded pipes, check whether there are leakage defects in the steel pipes within the specified pressure holding time, assess the overall pressure bearing capacity of the steel pipes, and eliminate part of the residual stress of the pipe body to Guarantee the performance of the steel pipe. Among them, the oil-water balance system is the core control system of the hydraulic testing machine. When the high-pressure water test is performed on the steel pipe, the system can make the oil pressure stable, timely and accurately track the water pressure value in the test steel pipe, so as...

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Problems solved by technology

[0009] 1. During the test, for the test steel pipe 10 with small diameter and small wall thickness, the minimum control pressure of the proportional relief valve 34 is often large (when there is no control signal input, the dead zone pressure can reach 7bar), that is, the load on The inlet pressure on the main hydraulic cylinder 20 is high, which easily causes the test steel pipe 10 to be crushed and deformed, and easily damages the end face sealing ring 14, which brings great uncertainty to the test work;

[0010] 2. During the pressure maintaining process, the maximum bearing pressure of the T ports of the two-position three-way cut-off electromagnetic directional valves 351 and 352 is 150 bar, but in the actual test process, the balance oil pressure of some test steel pipes 10 exceeds the two-position three-way cut-off The maximum withstand pressure of the T ports of the type electromagnetic directional valves 351, 352 cannot meet the pressure-holding process requirements in the test of the test steel pipe 10;

[0011] 3. During the pressure maintaining process with two-position three-way cut-off electromagnetic directional valves 351 and 352, due to the internal leakage of the system or the quality defect of the test steel pipe 10 itself, the water pressure in the test steel pipe 10 will fluctuate, and the main hydraulic cylinder 20 The oil pressure in the tank cannot be changed synchronously with the change of water pressure, which may cause the test steel pipe 10 to be accidentally bent and the end face sealing ring 14 to be damaged.

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