Pay attention to the application of hydraulic wrench in installation

Pay attention to the application of hydraulic wrench in installation

I. Brief Introduction of Hydraulic Wrench

1. Characteristics of hydraulic wrench

Hydraulic torque wrench (hereinafter referred to as hydraulic wrench) is a professional bolt tightening tool powered by hydraulic pressure to provide large torque output. It is often used to tighten and remove bolts larger than M20. Each wrench is applicable to different bolt size ranges and corresponding torque ranges. Generally, a wrench head is equipped with several sleeves to adapt to the bolt size. The wrench head, hydraulic oil pipe and hydraulic pump form a complete hydraulic wrench system.

The maximum output torque of hydraulic wrench can reach 11000N?m, which not only improves the work efficiency, reduces the labor intensity, but also greatly improves the installation quality, and is also conducive to the site safety management. The use of hydraulic wrench is very wide, in the shipbuilding, petrochemical, construction, electric power, mining, metallurgy and other industries in the construction, maintenance, installation and other work, hydraulic wrench for the installation and removal of large specifications of the bolt is a very important tool. It has the irreplaceability of other tools, not only easy to use and light, but also the huge torque value provided is very accurate, and the torque repetition accuracy reaches about 3%.

2. The working principle of hydraulic wrench

Hydraulic wrench is composed of working head, hydraulic pump and high pressure oil pipe. The power is transmitted to the working head through the high-pressure oil pipe and the hydraulic pump to drive the working head to tighten or loosen the rotating nut. The hydraulic pump may be driven by electricity or compressed air.

The working head of the hydraulic wrench is mainly composed of three parts: frame (also called shell), cylinder and 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 amplification arm of the hydraulic wrench. The output of the oil cylinder multiplied by the arm is the theoretical output torque of the hydraulic wrench. Due to the existence of frictional resistance, the actual output torque of the hydraulic wrench is less than the theoretical output torque.

3. Categories of hydraulic wrenches

Hydraulic wrenches are divided into hydraulic torque wrenches, electric hydraulic wrenches, pneumatic hydraulic wrenches, driven hydraulic wrenches, Maanshan hydraulic wrenches, KERUIDA hydraulic wrenches, etc. The driven hydraulic torque wrench is used with standard socket. It is a universal hydraulic wrench and has a wide range of applications. The thickness of the hollow hydraulic wrench is thin, and it is especially suitable for places with narrow space. It is suitable for marine engineering, petrochemical, construction, electric power, mining, metallurgy, transportation, aviation and other industries.

II. Use in Installation and Construction

In the process of installation and construction, the use of hydraulic wrenches is very common; there are generally the following characteristics. First, the working environment is bad; second, the work is in a state of overload for a long time. Third, the use of large, large number of bolts; large torque; torque requirements are accurate; tight on-site construction period; unstable on-site power supply.

1. Key points for hydraulic wrench purchase

① The torque value can be accurately controlled; ② The working speed is fast (3~4 times faster than other brand wrenches);③ It can work continuously for 24 hours and the hydraulic pump basically does not generate heat. ④ The working stroke is large and there will be no jam. ⑤ Strong, durable and long service life; ⑥ The nominal working pressure of the hydraulic wrench is 70 MPa, and the key is that the high pressure seal does not leak. Such as the piston cylinder liner and rotary joint part of the sealing capacity, these places are the weakest, tubing joints can not be ignored. ⑦ The mechanical performance index of hydraulic wrench under heavy load conditions, fatigue damage of ratchet wheel, ratchet tooth and other components; ⑧ The voltage design of the hydraulic pump motor is to adapt to the possible voltage fluctuation of the generator installed on site; ⑨ The hydraulic oil pump should use the model without carbon brush as far as possible.

2. Maintenance and maintenance of hydraulic wrench

① The hydraulic wrench belongs to precision tools and equipment, and should avoid falling and pressure impact during use.
②To avoid contact with acid, alkali, oily, and corrosive substances, use anti-rust oil (ordinary) when necessary, and wipe it clean with a dry cloth.
To ensure the accuracy of the torque, should avoid the use of high frequency, torque wrench in the use of the process to have a certain time gap (a use of the time and the second use of the gap, to have a certain time gap, the recommended time for the recovery of no-load after 5~8s).
④ In order to ensure accuracy and prevent the increase of error, the torque wrench must be used to zero (I. e. the minimum value of the torque wrench).
4, pay attention to the optimization of hydraulic wrench
Because hydraulic wrenches are often used in small spaces and convenient transportation during construction, the volume and weight of wrenches are the most important indicators. In order to reduce the size of the components, the use of high-strength alloy materials and heat treatment, coupled with finite element analysis to optimize the design, is a very important part, but also must be more than 1000 MPa strength and stability, the current domestic products are still difficult to meet such standards, can choose foreign brands, which is the premise of product quality and reliability guarantee.

In short, there is no international product and test standards for hydraulic wrenches. Because the hydraulic wrench is a very important tool for the installation and removal of large bolts, it is irreplaceable. We should step up the pace of research to catch up with the progress of the development of fasteners in the world.