The pressure testing machine is mainly suitable for testing various physical and mechanical properties of concrete, rubber, plastic plates, pipes, profiles, plastic films, wires and cables, waterproof membranes, metal wires, cartons and other materials. So do you know the causes and solutions of pressure testing machine errors? Let's take a look.
1. Errors caused by incorrect installation of testing machines
If the testing machine is not installed horizontally, it will increase the friction between the moving parts, affect the vertical installation, and thus bring errors to the testing machine.
1) The installation of the host part is not horizontal.
Friction will be generated between the working piston and the working cylinder, and the guide wheel between the working platform and one side column of the testing machine will also produce friction, resulting in error, which is generally a positive deviation, and the error decreases with the increase of load.
2) The dynamometer part is not installed horizontally.
If the front and rear installation of the dynamometer is not level, it will cause friction between the pendulum shaft bearings, and the error is generally a negative difference.
The characteristics of the error caused by the combination of the above two factors are that they have a large impact on the small load and a small impact on the large load.
Second, the error caused by frictional resistance
1) The friction resistance of the main engine part.
The frictional resistance of a hydraulic testing machine mainly occurs between the working cylinder and the working piston. In addition to the non-level installation factor, there are dirt in the cylinder, and the viscosity of the oil is too large, which will also cause the friction resistance to increase. In addition, the inappropriate position of the guide wheel of the working platform will also cause the friction with the column on one side to increase.
2) The friction resistance of the dynamometer part.
There are many reasons for the friction resistance of the dynamometer, such as dirt between the force measuring cylinder and the force measuring piston, the viscosity of the oil is too large, the friction of the driven needle on the indication device is large, there is oil stain on the gear tooth rod, dirt or the upper limit of the tooth rod is pressed too tightly, and the force measuring piston belt is worn and broken.
Pressure testing machine error elimination method
For the occurrence of the above errors, the testing machine should first be checked whether the installation is horizontal, and the frame level should be used to level the main engine in the two directions perpendicular to each other in the outer ring of the working cylinder. Adjust the front and rear levels of the dynamometer on the front of the pendulum, align the edge of the pendulum with the inner carved line, and use the level ruler to lean on the side of the pendulum to adjust the left and right levels of the body. The internal organs of the oil cylinder can be drained to clean and replace the oil with suitable viscosity.
If the friction of the driven needle of the dynamometer indicating device is too large and the gear tooth rod is too dirty, it can be cleaned with gasoline and adjust the hold-down screw and the upper limit of the tooth rod, and replace the belt on the force measuring piston, which can achieve the purpose of eliminating errors and making the testing machine reach the qualified use state.