Torsion balance operation application introduction

(1) Working principle and type of torque balance

Its working principle is that when the torque generated by the hairspring or tension wire twists and the weight of the object to be weighed reaches a balance, the weighing result is indicated on the dial through the reading pointer. Its advantages are that it does not use codes, is easy to operate, and has fast weighing speed. The torsion balance can be used for weighing trace substances, especially suitable for moving to various work sites.

Its types are divided into three types according to the structure: shaft tip bearing type, leaf spring support (hanging skin) type and tension wire type. According to the tube ratio, there are equal tube and different types.

The JN-A precision torque balance is widely used at present, its performance is shown in Table 7-8, and the schematic diagram is shown in Figure 7-7. In addition, there is TW type, the maximum cutting load is 1kg.

(2) Operation steps

The measurement performance of the force balance includes three items: sensitivity, change of indication value and accuracy of indication value. Its operation and precautions are as follows:

(1) Hang the weighing pan on the weighing object with weight tweezers, and then put on the measuring box.

(2) Turn the reading knob to align the reading pointer with the zero line. Then turn on the balance and observe whether the verification pointer coincides with the verification mark on the dial. If the verification pointer deviates from the verification mark line, you need to gently pull out the retainer in the middle of the reading knob, and use a small screwdriver to slightly turn the screw in the middle to correct the deviation. When the verification pointer coincides with the verification marking line, the protective cover is not good.

(3) Put the standard magnetic code equivalent to the maximum load of the balance on the weighing pan, close the metering box, and turn the reading knob counterclockwise until the reading pointer is aligned with the finish line. Turn on the balance, at this time the verification pointer needs to coincide with the verification marking line. If there is any deviation, turn the reading knob so that the verification pointer coincides with the verification marking line. At this time, the reserve shift between the reading pointer and the finish line is the indication error when the balance is under the maximum load (when calculating the indication error, the correction value of the standard weight should be taken into consideration, and if necessary, add Compensation of sub-temperature and acceleration of gravity), and calculate whether the error of the displayed value is within the allowable error.

(4) Turn off the balance, remove the standard weight, and turn the reading knob back to the zero position, then the balance can be used.

(5) The zero position should be corrected during use. When correcting the zero position, the balance can be turned on three times in a row. If the position of the verification pointer remains unchanged, it means that the balance is balanced.

(6) Put the weighing sample on the weighing pan, turn on the balance, turn the reading knob, and observe the verification pointer at the same time. When the verification pointer coincides with the verification marking line, the value indicated by the reading pointer on the dial is the mass of the sample being weighed.

(7) The balance should be turned off when taking the magnetic code or sample; the weighing sample should not exceed the maximum load of the balance; it should be handled with care, and do not hit or pull the scale fishing; when the knob part is rotated, it should be operated slowly; foreign countries Do not open the back plate easily; the silica gel should be replaced frequently in the metering box.

(8) Close the balance immediately after weighing the rate, and return the reading pointer to zero to prevent the hairspring from being stretched for a long time.