With the thrust f of the small piston acting on the pendulum, the pendulum raises an angle H and is in equilibrium. At this time, the pressure bar pushes the tooth bar to move a distance of x, we can get: x=lhGLcosBf where: f—— The force of the small piston on the pendulum; G - the mass of the pendulum; L - the length of the pendulum; l - the distance from the pendulum swing center to the point of action of the force f (ie the length of the short arm); h - pendulum The vertical distance from the center of the hammer to the rack; B—the angle between the edge of the strut and the swing center of the pendulum to the perpendicular of the rack. It can be seen that the displacement of the tester gear is proportional to the test force received by the sample. The l, h, G, L, B, etc. in the formula are constants and are fixed at design time. They are all parameters of the force measuring mechanism. Obviously, as long as there is a change in these parameters, the value of x will change, resulting in an error. Adjustment method When the indication value of each point of the testing machine is basically constant relative to the error symbol size, and is independent of the selection dial, it is generally adjusted by changing the length of the short arm in the pendulum force measuring mechanism. When there is a certain disc indicating value that is out of tolerance and the relative error of each point is basically unchanged, and the other dials are all qualified, the method of increasing or decreasing the pendulum mass corresponding to the dial may be used for adjustment. (3) When the indication error of the test machine changes from positive to negative or from negative to positive, the angle of the push plate should be adjusted. The main part of the B is not installed. If the main part is not installed horizontally, the upper and lower jaws of the test machine are not concentric, and the sample is subject to The force is not in the direction of the axis of the test piece, except for the pressure (pull), the sample is also subjected to the bending moment. Due to the different installations, friction between the working piston and the working cylinder will occur, and the roller between the boat and the column will also generate friction. The appearance of such errors is generally positive. Its characteristic is that its error has a large impact on small loads and a small impact on large loads. The force measurement part is not leveled. The horizontal force measurement part is not horizontal. It mainly causes two problems. First, the function between the parts is different from the design and inspection time, and some additional force is added. Second, the technical parameters of the test machine are generated. change. If the front-rear direction is not horizontal, friction between the pendulum shaft bearings will be generated, and the friction between the force-measuring piston and the force-measuring shaft will be increased, and the pendulum length may also be changed. These frictional forces generally show a negative difference, and have a large influence on small loads and a small impact on large loads. If the left and right directions are not horizontal, the 5 and B angles are simultaneously changed, which may cause a large indication error. The error is expressed as the larger the inclination angle, the larger the error, and the smaller the influence on the small load indication, and the larger the impact on the large load. Error caused by frictional resistance 3.1 The friction of the main part mainly occurs between the working cylinder and the working piston. In addition to the above incorrect installation, there is dirt or rust in the cylinder, and the viscosity of the oil is too large. Frictional resistance. Improper adjustment of the position of the boat table wheel will cause friction between the column and the column. The error caused by the frictional resistance of the main part generally shows a positive difference, and some can produce an error pattern with substantially the same absolute error, and some absolute errors increase with the increase of the load. The friction of the force measurement part generally shows a negative error, and has a large influence on the small load. For the small load, the friction of the small indication mechanism generally produces an error with substantially equal absolute error, that is, the relative error decreases with the increase of the load, but Large local errors can occur when the local friction is large. Pendulum rods, push rods, short arms, and tie rods encounter resistance during operation, which can cause large local negative errors. In short, it is necessary to comprehensively analyze the error factors generated by the testing machine, analyze and judge the parts and causes of the errors according to the laws and properties of these error values, and eliminate them. It is not possible to eliminate the errors by simply increasing or decreasing the quality of the defects. This is not a good idea, because this method was qualified at the time, and it may change if it is not long. vibrating sieves, also called vibrating screen, circular vibrating screen, sand vibrating screener, are used to separate materials into various sizes for further processing or for end use. The material is separated by passing through a vibrating [screen or meshes" which has a number of different sized according to customer`s requirements. The end products can then be used in the building and construction industries. 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Analysis on the problems of hydraulic testing machine in daily life