How to eliminate the hydraulic impact of unloading and reversing of hot press

How to eliminate the hydraulic impact caused by the unloading and reversing of the hot press? When unloading or reversing, the high-pressure and large-flow hydraulic circuit will produce pressure impact, causing serious vibration. According to the pulse heating principle of Shenzhen hot press, due to the special design of the welding head surface, the resistance of the welding surface is very small, and the current will pass through the section with the minimum resistance. By constantly changing the voltage, adjusting the current level, and rapidly heating the welding head. The hydraulic hot press uses pulse heating technology, with accurate temperature control and temperature sampling frequency of 0.1s. High-temperature hot press is an electrical and mechanical connection device that heats two parts coated with flux tin in advance to a temperature sufficient to melt and flow solder, and forms a * * * between the parts and solder after curing. The basic methods to eliminate such problems are as follows. (1) The press releases the pressure in the circuit in advance. When people release the pressure energy enclosed in the hydraulic cylinder in an appropriate way, and then operate the main hydraulic system, the pressure impact can be eliminated.
There is a two-position two-way solenoid valve in the oil circuit of the upper chamber of the hydraulic cylinder for pressure relief. After the work is completed, switch the main reversing valve forward and open the pressure relief valve through the time relay. The time is about 3~5s. When the circuit pressure drops to 0 or close to 0, open the main reversing valve again, and there will be no pressure impact at this time. Note that the pipe of the pressure relief valve must be small enough (within 6mm in diameter), otherwise new pressure impact will occur. The pressure relief circuit composed of the reversing valve and the throttle valve, that is, when the electro-hydraulic reversing valve 1 returns to the neutral position, the pressure in the upper chamber of the hydraulic cylinder 2 is slowly released through the throttle valve 3 and the check valve 4, so the hydraulic cylinder does not need special pressure relief when it goes up. (2) Hydraulic pressure relief time extension hydraulic control check valve is widely used for pressure maintaining and pressure relief of large hot press. During the pressure maintaining process of the hydraulic system, when the pressure is released, the energy stored by the compression of the oil, the expansion of the pipeline and the elastic deformation of the machine will be released suddenly; During the return process of the hydraulic cylinder at the end of pressure maintaining, the lower chamber pressure has not been released, and the upper chamber pressure may have increased, causing the main valve core of the unloading valve and the hydraulic control check valve to open at the same time, resulting in sudden oil discharge from the upper chamber of the hydraulic cylinder; The combination of the two aggravates the impact vibration and noise of the hydraulic system. The hydraulic control oil path of the hydraulic control check valve is equipped with a one-way throttle valve, which can control the flow of the hydraulic control port, thus reducing the movement speed of the control piston, extending the pressure relief time, and eliminating the pressure impact. A circuit to prevent hydraulic shock when the hydraulic pump is unloaded. The outlet of overflow valve 1 is equipped with anti-shock valve 2 to prevent impact during unloading. The anti-shock valve 2 is composed of a pressure reducing valve A and a throttle valve b. When the outlet of the solenoid directional valve 3 is connected to the oil tank, control the outlet to discharge a certain amount of flow, so that the overflow valve can slowly open to relieve pressure, and avoid the impact caused by the sharp drop in pressure. For the proportional pressure relief valve, the pressure relief time can be changed by adjusting the corresponding potentiometer on the amplifier circuit board.