Treatment methods and precautions for the deflection of mining hoist brake disc

The hoist plays an important role in mine operation, and the brake disc deflection is one of the common faults of the hoist. The brake disc deflection easily leads to insufficient braking torque, brings about unsafe production and affects the stable operation of the hoist. Therefore, when the brake disc deflection is found, it must be handled in time to control the brake disc deflection and ensure the reliable operation of the hoist.

1、 Treatment method of hoist brake disc deflection

1. Preparation

Use a dial indicator to measure the drum, measure the actual deflection data of the brake disc, determine the deflection area, propose a treatment plan for the defects of the brake disc, and prepare construction tools, mainly including dial indicator, portable grinder, whiteboard, feeler gauge, etc.

2. Measure the deflection of brake disc

Clean the oil and dust on the inside and outside of the brake disc, fix the magnetic gauge base on the brake base, put the dial gauge into the gauge base, and find a benchmark. The gauge base and the dial gauge cannot be moved during the whole construction process. The deflection value of the whole brake disc is measured on site. In order to improve the measurement accuracy, one observation point is established every 200mm. Determine the section to be processed through the measured data, mark it with white slate, draw a sketch for the processing record, and arrange personnel to make records for the position and original data to be corrected.

3. Heating brake disc

Preheat the area with large deflection of the brake disc to prepare for correction. The drum operates at a speed of 0.3m/s. The root of the heated brake disc is the joint of the drum and the brake disc. The arc length should be 300mm beyond the correction area, and the width should be kept at 30mm. The distance between the cutting torch and the calibration surface is 15 ~ 25mm. The depth of flame heating is 50% of the thickness of the brake disc. The temperature is adjusted by the speed of moving the cutting torch. The moving speed is 3.5m/s, The temperature is controlled between 500 and 700 ℃. Generally, the key heating area shall be marked in advance, so that the drum can be heated accurately

4. Initial calibration inspection

After the initial calibration, the expected heating temperature is reached, the heating of the brake disc is stopped, the cutting torch is turned off, the hoist motor is powered off, the brake disc is gently applied, and the drum is slowly stopped in the state of pressing the brake. The brake disc is in the free state and naturally cooled down. Generally, it takes 40min. According to the original marked value, re measure and compare with the value before calibration, and record the value, Accumulate experience as the basis for the next correction.

5. Secondary correction

Through the previous correction, the correction size of the position with small deflection basically meets the requirements, the positions of the secondary correction are less, the correction process is less than the secondary correction time, and the focus is more prominent. The first is pre heating. The drum operates at the speed of 3m / s, and the cutting torch is used to heat the marked part. Then the drum operates at the speed of 5m / s. the heating time of the cutting torch is the same as that of the front. The length and width of the heating area are adjusted according to the corrected size. After the heating time is met, cool naturally and re measure. The record shall be marked with the same method as above. After three times of correction, the deflection can be basically corrected. In some cases, it is necessary to add one more time, or there is a deviation in the treatment process, and the treatment method is unreasonable. It needs to be corrected in reverse, which is a waste of time. The key work is to keep the valley value as the benchmark for correction and avoid excessive correction

6. Processing interface

The roller of the hoist is composed of four halves. The roller and the hub are connected by four bolts. After the treatment of the whole roller, the two semicircular interfaces are severely deformed. The method of heating shall be continued to correct the connection of the interface. Since there is no rigid limit at one side of the interface, it is often The results are not very satisfactory, time-consuming and laborious, and it is difficult to ensure the deviation at the interface. Sometimes, it is necessary to polish the interface with a portable grinder to ensure that the connection at the interface is within the allowable range.

7. Adjust the brake clearance

Due to the deflection of the brake disc, the brake clearance switch is prevented from misoperation, and the brake clearance is adjusted to 1.8 ~ 2.0mm. After the brake disc deflection is processed, the 16 pairs of brakes shall be adjusted once by measuring the correction results, so that the braking force of the hoist can meet the requirements, and the test run can be started after the ram clearance is adjusted to 1.2 ~ 1.8mm. Empty bucket shall be used for the trial operation, and the speed shall be controlled at 3m / s, and the pressure shall be observed,. At the same time, observe whether there is any impact sound between the interface of the roller and the brake panel, and whether the current on the instrument panel is biased. It can run at full speed under normal conditions. Make records and the test run is completed.

2、 Precautions for treatment of hoist brake disc deflection

1. Position with dial gauge

The positioning of the dial indicator is very important. It is required that only the indicator is sensitive and reliable, and the position must be fixed. Otherwise, the reference will be offset, and all previous work will be discarded. The heating position shall be accurate, the length and width of heating shall be planned and marked on the roller. The heating process shall be carried out in strict accordance with the predetermined scheme and shall not be changed at will.

2. Correct heating speed

The moving speed during correction heating shall be well controlled, and the distance between the cutting torch and the brake disc shall be kept consistent to prevent overheating and burning of the brake disc. After the heating of the brake disc reaches the expected effect, the natural cooling method must be adopted. It is not allowed to reduce the temperature in a hurry, such as forced cooling by physical means such as watering, so as not to cause the deformation of the brake disc and increase the processing difficulty.

3. The hoist cannot operate

During the treatment of the brake disc, attention shall not be paid to the high-speed operation of the hoist, which will cause the friction heat between the brake disc and the ram, and the deformation of the brake disc, which will increase the difficulties for the field treatment. After the treatment of the brake disc, the clearance of the ram shall be adjusted in time to make the force of each pair of brake uniform and the braking torque synchronous.

To sum up, the treatment method of hoist brake disc deflection is to first prepare construction tools, measure the deflection data and area, then measure the deflection value of the whole brake disc, heat the brake disc, correct it twice, and then deal with the interface and adjust the brake clearance. In the process of treatment, there are several key points that need attention, such as the behavior of the dial indicator, the correction of the heating speed, and the high-speed operation of the elevator during the process. Correcting the brake disc deflection is also helpful to eliminate many hidden dangers such as insufficient braking torque, and plays an important role in safety production.