Created on:2021-06-23 15:50

Hydraulic fault diagnosis and elimination of rubber mixer

Hydraulic fault diagnosis and elimination of rubber mixer

(1) Overview

Xm270-20 / 40 internal mixer is one of the key equipment of a company. Its main technical parameters are: total capacity 240L (four edged rotor), working volume 180L, rear rotor speed 20 / 40R / min, rotor speed ratio 1:1.16.

This machine adopts a crank type locking device, and its working principle is shown in Figure M.

(2) Existing problems and Solutions

According to the design, the mechanism has self-locking angle α With 6 ° It is suitable for the locking crank 4 to release the lock under the action of the locking cylinder, and the normal opening and locking time of the discharge door is 2-3s. In the process of use, with the wear of the two contact surfaces between the cushion block 6 and the adjusting block 7, the unlocking time is too long, and sometimes it can't be released, resulting in the production interruption and the rubber temperature exceeding the process requirements. The reason is that with the wear of the contact surface, the increase of the displacement of the locking crank 4 causes the self-locking angle to decrease α reduce. From the force analysis α When it is reduced to a certain extent, the crank 4 will be in the over locked state, which increases the unlocking resistance of the locking cylinder.

It is usually handled by replacing the cushion block 6 and adjusting block 7, and the replacement process is complicated. In view of this situation, try to remove the iron pad 2, reduce its thickness to increase the angle of the mouth. The test results are very obvious, and the original performance is better restored without replacing the iron pad.

At the same time, when the mechanism is used, especially in the mixing process of rubber, it sometimes appears the problem of sudden unlocking, which not only seriously pollutes the environment, but also greatly affects the quality of rubber, causes waste, and reduces the efficiency of the equipment. In the initial stage, the method of replacing the seals of the hydraulic system is used to solve the problem, which is not only costly, but also time-consuming. In order to solve the problem fundamentally, the hydraulic schematic diagram and pump station are analyzed. The matching pump station is a seven valve structure pump station produced by Dalian University of technology. The hydraulic principle of its locking mechanism is shown in Figure n. The locking cylinder is controlled by 24eyo-h20b electro-hydraulic directional valve. When it is in the position shown in the figure (in the loose lock state), the pressure is supplied by the large pump and the energy storage of the double vane pump. In fact, the original pump station is equipped with 24eyo-h20b electro-hydraulic directional valve controlled by 34eyo-h20b-t pilot valve, As a result, the electro-hydraulic directional valve 2 only relies on the hydraulic oil sealed inside to maintain the working state of locking cylinder. With the increase of leakage, the hydraulic control valve will reset under the action of the return spring, resulting in unlocking. In view of this situation, the reset springs on both sides of 34eyo-h20b-t pilot valve of valve 2 are removed, so that the valve core is in a free state. When the working coil on one side loses power, the valve core can still be kept in the original charged position, so as to ensure that the control pressure oil is supplied to 24eyo-h20b main valve, so that the energy accumulator can give full play to the role of pressure maintaining, The pressure drop is supplemented by the work of the pump station, which solves this problem, saves a lot of maintenance costs and ensures the production.

N.jpg

The maximum injection pressure of process hydraulic pump element is Pmax = 32Mpa, which is lower than the maximum injection pressure (P = 72mpa) of the matching lubricating pump (the pump model: dyx7-15). Its oil penetration ability is weak, and the phenomenon of oil hole blockage is very easy to occur. At the same time, due to the existence of the fit clearance and wear of each contact surface, according to the original design, the process oil injection mode is intermittent oil injection with the working state of the upper jack bolt, which increases the chance of oil hole plugging, which has been proved in actual operation. This not only affects the production, but also increases the dry friction, damages the sealing surface and makes the function invalid. Therefore, according to this problem, under the premise of not replacing the process hydraulic pump, the oil supply pressure is increased, and the intermittent oil injection is changed to continuous oil injection, and the sufficient oil supply and clean oil quality are ensured. At the same time, combined with the wear condition of the dynamic and static ring surface, adjust the fork timely to increase the oil supply pressure of the hydraulic cylinder (the pressurization range is 0.2MPa). Through the above adjustment, this problem is well solved. At present, this set of seals has been put into operation for 3 years, and the sealing effect is still good.

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