Hydraulic Wrench - Basic Components

Hydraulic torque wrench is composed of body, electric hydraulic pump, double high pressure oil pipe and high strength sleeve. After the hydraulic pump starts to generate pressure through the motor, the internal hydraulic oil is transmitted to the hydraulic torque wrench through the oil pipe medium, and then pushes the piston rod of the hydraulic torque wrench. The piston rod drives the ratchet at the front of the wrench so that the ratchet can drive the drive shaft to complete the bolt. The preload loosening work.

Hydraulic torque wrench body
The body of the hydraulic torque wrench is mainly composed of three parts, the body (also called the shell), the oil cylinder and the transmission parts. The output force of the oil cylinder, the piston rod of the oil cylinder and the transmission part form a motion pair, the distance from the center of the oil cylinder to the center of the transmission part is the hydraulic wrench amplifying force arm, and the oil cylinder output multiplied by the force arm is the theoretical output torque of the hydraulic wrench.

power unit
The hydraulic wrench pump is the power unit of the hydraulic wrench. The hydraulic wrench pump is a high-pressure pump, and the maximum working pressure is generally 70MPa. The common ones are electric hydraulic pump and pneumatic hydraulic pump.

Hydraulic wrench pump is composed of motor (electric motor or air motor), pump, pipeline, electrical control, etc. The common pumps are secondary pump and tertiary pump, and the general secondary pump is low pressure gear pump and high pressure plunger pump. The gear pump provides hydraulic oil under pressure for the plunger pump, and the exchange pressure between the gear pump and the plunger pump is 7-10MPa. The structure of the three-stage pump is various. The typical structure is a plunger pump, with 4 large-diameter plungers for low pressure, 2 small-diameter plungers for medium pressure, and 2 small-diameter plungers for high pressure. There are also three-stage pumps that use the first-stage pump as a gear pump, and the second-stage and third-stage pumps as plunger pumps;

When the working piston of the hydraulic wrench moves, it is generally in a medium pressure state of 10-32MPa, and the medium-pressure flow is 2.2 times the flow of the high-pressure (32-70MPa) flow. Based on the three-stage pressure flow curve, the speed of the three-stage flow pump is the second-stage flow rate. The flow pump is nearly 2 times. It can be seen that the speed of the tertiary pump is much faster than that of the secondary pump.

Electric hydraulic wrench pump motors are divided into brushless motors and carbon brush motors. Brushless motors are generally induction motors and need to be equipped with capacitors. In order to start the pump under pressure, it is necessary to install a starting capacitor and a running capacitor. The brushed motor is generally a series motor with high speed, which can provide a large flow for the pump, but the noise and vibration are large.

The brushless motor usually has a service life of tens of thousands of hours, but it is very easy to cause the motor to overheat. According to different working conditions, it is not a very effective solution to choose. The continuous working life of the carbon brush motor is 1-10 Years, and they are usually equipped with coolers, so carbon brush motors are more suitable for long-term continuous operation of hydraulic wrench-specific pumps, and these hydraulic pumps are the mainstream configuration.

synchronization system
The main purpose of the hydraulic wrench synchronization system is to avoid the unilateral compression mode on the flange surface, which will cause the gasket on the flange surface to fail due to excessive extrusion, resulting in leakage. Synchronous system is used when two or four hydraulic wrenches are connected to one pump at the same time. According to the hydraulic principle, multiple hydraulic wrenches work at the same time and output the set torque at the same time, the flange can be closed in parallel, and the torque accuracy can reach 3%. The synchronous system can lock the bolts at one time, while the single system needs to be loaded multiple times and locked in steps. It can be seen that the efficiency of the synchronous system is much greater than that of the single system.