The anti pendulum impact test is a key method for evaluating the dynamic impact resistance performance of materials, but in practical operation, the test results are often distorted due to equipment failures, operational errors, or environmental factors. The following are common problems and targeted solutions:

1、 Abnormal fracture surface of the sample: The fracture surface appears as "two-sided fracture" or non center fracture

Reason: The main body of the testing machine is not installed vertically, the quality of the jaws is poor, or the upper and lower jaws are not concentric.

Solution:

Use a level to calibrate the main body of the testing machine, ensuring that the verticality difference is ≤ 0.1mm/m;

Check if the teeth of the jaws are worn, and replace them immediately if there is any slippage;

By measuring the concentricity of the upper and lower jaws with an inspection rod and a dial gauge, adjust the lifting guide wheel to an error of ≤ 0.05mm. For example, in a laboratory, after adjusting the guide wheel, the qualification rate of the sample fracture increased from 75% to 98%.

2、 Abnormal return of pendulum: sometimes fast, sometimes slow, or not returning after impact

Reason: Blockage of buffer valve, abnormal viscosity of oil, or excessive clearance between steel ball and valve seat.

Solution:

Clean the buffer valve and use kerosene to remove impurities from the oil hole;

Adjust the gap between the steel ball and the valve seat to 0.5mm, and re mark the mark of the weight;

Replace the appropriate viscosity oil according to the ambient temperature (such as using 46 # anti-wear hydraulic oil in winter). After replacing the oil, a certain enterprise improved the stability of the pendulum's return time by 40%.

3、 Pointer zero drift: The pointer deviates from zero after a blank strike

Reason: The testing machine is not leveled, the active needle is loose, or the swing rod is bent.

Solution:

Re calibrate the level of the testing machine to ensure that the height difference between the four corners is ≤ 0.02mm;

Tighten the fixing screw of the active needle and check the friction between the pointer and the dial;

Use a dial gauge to check the verticality of the swing rod. If the bending exceeds the tolerance, it needs to be straightened or replaced. After straightening the pendulum, a certain testing institution reduced the zero drift from ± 0.5% to ± 0.1%.

4、 Large data fluctuations: high dispersion of repeated test results

Reason: Unstable friction force (such as rusting of swing shaft bearings), oil leakage in the oil system, or unstable sample clamping.

Solution:

Clean the pendulum shaft bearings, gear bars, and pointers, and add clock oil;

Check the sealing of the oil circuit joint and replace the broken oil pipe;

Ensure that the sample is vertically aligned with the clamping table, and that the notch vertex is coplanar with the upper surface. After optimizing the clamping method, a laboratory reduced the standard deviation of data by 60%.

5、 Equipment operation failure: Difficulty hanging or inability to release the pin

Reason: The operating mechanism is corroded or poorly lubricated.

Solution:

Disassemble the relevant parts, clean them with kerosene, and apply lubricating grease;

Check the distance between the magnetic roller and the armature of the tooth embedded electromagnetic clutch and adjust it to 1.2-2mm. After maintenance, the equipment failure rate of a certain enterprise decreased from 3 times per month to 0.5 times.

Preventive maintenance recommendations

Regular calibration: verified by legal institutions every six months to ensure energy error ≤ ± 1%;

Environmental control: Maintain room temperature of 20 ± 5 ℃, humidity ≤ 65%, and avoid changes in oil viscosity;

Spare parts management: Reserve commonly used vulnerable parts (such as pliers, buffer valve steel balls) to shorten maintenance cycles.

By systematically checking equipment status, standardizing operating procedures, and strengthening preventive maintenance, the accuracy and repeatability of anti pendulum impact testing can be significantly improved, providing reliable data support for material performance evaluation.