The maintenance of the automatic diaphragm Filter Press is mainly the maintenance of its hydraulic system and transmission system, that is, the maintenance of hydraulic oil, grease, hydraulic parts and transmission parts. Through regular inspection and maintenance of the pull plate mechanism, transmission chain, hydraulic components and other components of the automatic diaphragm filter press, corresponding measures have been taken to prevent the temperature of the hydraulic oil from being too high, air mixing and pollution, to ensure that the hydraulic oil is clean and the oil quality is stable, and the state of the automatic diaphragm filter press is kept intact, and the equipment can operate stably and economically for a long time.

Automatic diaphragm filter press is a kind of batch filtration, washing and pressing equipment, which is used for solid-liquid separation of various suspensions. It relies on the pressing device to press the filter plate to fix the filter cloth and seal, use the chemical pump to suspend the hydraulic pressure into the filter chamber, filter the solid-liquid material through the filter cloth filtration, and also wash the filter residue with water or other liquids, and finally press the filter residue with water or compressed air. The automatic diaphragm filter press has simple structure, good separation effect and easy to use, and is mainly used in mining, chemical industry, metallurgy, medicine, food, environmental protection waste residue wastewater treatment and other industries.

The most widely used now is the automatic diaphragm filter press for polypropylene filter plates. The filter press has the characteristics of small unit filtration area, strong adaptability to materials, wide selection range of filtration area, high filtration pressure, high solid content of filter cake, convenient operation and maintenance, etc., and can automatically control the process of compression, pressure holding, feeding, washing, pressing, pulling plate, and liquid wetting.

1. Installation and workflow of automatic diaphragm filter press

(1) Installation of automatic diaphragm filter press

The automatic diaphragm filter press generally has two supports at the head and tail to bear the weight of the whole machine. The tail plate (thrust plate) is connected with the feed pipe, the washing liquid pipe, the liquid discharge pipe, and the supporting seat of the tail plate is fixed on the foundation with anchor bolts. The head plate (hold-down device) is far away from the tail plate, and the two are connected by two cross beams. The length of the beam of the large filter press is about 10-15m, and there are 1 or 2 support legs in the middle of the beam on each side. During operation, the beam is subjected to the tensile force of the compression device and the gravity of the material during filtration. The compressive force transmitted by the hydraulic cylinder and the piston rod can lead to the elastic elongation of the horizontal direction of the beam, and the elongation of the large filter press can reach 2-5mm, so the head plate should be guaranteed to be free to expand and contract. In the equipment installation, the bearing below the head plate and the cross beam legs on both sides are required to adopt the mode of floating installation, and although the head plate support is floating, there are 2 side baffle irons at the bottom of the bearing, which play a guiding role when telescoping.

(2) The workflow of the automatic diaphragm filter press

(1) Pressing the filter plate→ (2) Pressing the filter process→ (3) Washing process→ (4) Pressing process→ (5) Loosening the filter plate→ (6) Filter plate discharge

After completing the above 6 steps, a working cycle of the automatic diaphragm filter press is completed.

2. Maintenance of the transmission system of the automatic diaphragm filter press

(1) Clean lubrication of the pull plate mechanism and transmission chain

In the process of unloading the filter plate, part of the filter cake often falls into the guide rail of the pull plate trolley, which affects the lubrication of the pull plate mechanism and the transmission chain. Every 3-6 months of operation, the automatic diaphragm filter press opens the chain cover on both sides to clean the dirt and grease inside; At the same time, remove the chain to clean and ｒｅｐｌａｃｅ the grease.

Inspect and maintain the pull trolley and sprocket to keep their action flexible and lubricated. According to the working environment of the filter press, it is easy to splash water and materials on the chain, and the Great Wall 7029A-No. 1 grease is selected for the chain and grease lubrication points, which has good oxidation stability, water spray resistance, and acid gas medium resistance, and is suitable for the working conditions of the automatic diaphragm filter press applied to titanium dioxide washing.

(2) Inspection and maintenance of hydraulic components and interfaces

After the automatic diaphragm filter press runs for a certain period of time, the sealing of the hydraulic components and each interface is worn, which will cause leakage, increase the temperature of the oil, and the external leakage of the hydraulic oil will cause system pollution and affect the smooth operation of the equipment. Therefore, the tightness of the hydraulic components and the individual interfaces needs to be checked and maintained regularly.

(3) Adjustment of the pull plate mechanism

After the automatic diaphragm filter press runs for a certain time, the distance between the dial jaw of the pulling plate mechanism and the lugs of the filter plate gradually increases, so that the pulling plate mechanism has irregular channeling or springboard phenomenon, and the pulling plate mechanism should be adjusted in time.

3. Maintenance of the hydraulic system of the automatic diaphragm filter press

(1) Prevent the oil temperature from being too high

(1) The influence of high oil temperature on the hydraulic system The hydraulic oil temperature in the hydraulic system is generally in the range of 30-65 °C, if the oil temperature exceeds this range, it will bring many adverse effects to the hydraulic system. The increase of oil temperature reduces the viscosity of the oil, increases the internal leakage of the hydraulic system, reduces the efficiency of the hydraulic pump, and the lubricating oil film between the surfaces of the relative moving parts becomes thinner, and the expansion of the hydraulic components after heating will increase the wear of the hydraulic components. When the oil temperature is high, the hydraulic oil is easy to oxidize, oxidation to form organic acids, so that the acid value in the oil increases, and the oil has a corrosive effect on the metal. Oxidation produces viscous insoluble slag precipitate and soluble oxidation polymer, which increases the viscosity of the oil, and the high-temperature oxide has an emulsifying effect, which emulsifies the oil and water, and the oxidation reduces the anti-emulsion and anti-wear performance of hydraulic oil.

(2) Measures to prevent the oil temperature from being too high

The hose installation in the system avoids sharp bends and reduces oil wear. When the pump, hydraulic cylinder and other hydraulic components are worn, they should be replaced in time, as worn components will cause an increase in leakage and increase the temperature of the oil. Keep the hydraulic system clean, contaminants in the system can exacerbate wear and tear, leading to oil leaks that can cause oil temperatures to rise.

(2) Prevent air from mixing into the hydraulic system

(1) The harm of bubbles to the hydraulic system There are generally two ways for air to enter the hydraulic system: suspension and dissolution. The air mixed into the hydraulic system is suspended in the hydraulic oil in a bubble state with a diameter of 0.05-0.5mm, which has a serious impact on the volumetric elastic modulus of the hydraulic oil and the viscosity of the hydraulic oil. When the amount of mixed air increases, the volume elasticity coefficient of the hydraulic oil decreases sharply, the propagation speed of the pressure wave in the hydraulic oil slows down, the dynamic viscosity of the oil increases linearly, and the stiffness of the oil itself is greatly reduced, resulting in the actuator action error, automatic control failure, and crawling of the working mechanism, which destroys the working stability of the hydraulic system.

After the air enters the hydraulic system, it will cause hydraulic oil shock, hydraulic pump cavitation, pipeline pressure pulsation, noise and vibration. When the bubbles in the oil are compressed instantaneously, the temperature rises sharply, causing the oil temperature to rise, resulting in the destruction of various additives in the oil, producing free carbon, acid and cement-like precipitate, and causing the oil to turn black, accelerating the deterioration of the oil quality, and at the same time, it will also cause chemical corrosion of the metal.

(2) Measures to prevent air from mixing into the hydraulic system

To prevent external gas from entering the system, the oil volume of the fuel tank should be checked frequently to avoid the phenomenon of air absorption. The height of the liquid level in the tank, its height

It should be kept on the oil mark engraving line. At the lowest level, the suction nozzle and the return nozzle should also be guaranteed to be below the liquid level, and must be separated by a partition. At the same time, check the oil condition in time to avoid oil deterioration. In the maintenance and installation, the air in the hydraulic components and pipelines must be drained, and the suction pipe and pump body must be filled with oil to keep the oil pipe well sealed.

(3) Prevent pollution of hydraulic system

(1) The harm of pollutants to the hydraulic system

Solid particle pollutants mainly include chips, casting sand, welding slag, dust, burrs, etc. The solid particle pollution of hydraulic oil will aggravate the wear of hydraulic components, shorten the life and work abnormally; and may break the seal and increase the leakage; It will also accelerate the deterioration of the oil and shorten the service life of the oil. Liquid contaminants mainly include moisture, cleaning fluids or materials. Mixing water into the working oil can emulsify the oil, cause system corrosion, reduce lubrication performance, and deteriorate low-temperature performance. The mixing of other liquids with working fluids will cause oil deterioration, reduce the physical and chemical properties of the oil, and lead to premature aging and failure of the oil. The gum produced by oil deterioration not only increases the viscosity of the oil, but also clogs the filter and affects the normal operation of the equipment. According to some data, 70%-80% of the unstable and faulty work of the on-site hydraulic system is related to the pollution of hydraulic oil.

(2) Measures to prevent pollution of hydraulic systems

A: Choose the right filter

The filter is a key component of the hydraulic lubrication system to remove impurities. The impurities in the hydraulic oil, except for the oil tank can precipitate a part of the larger particles, mainly rely on the filter to filter out, and the selection of the appropriate filter and accuracy is of great significance to the pollution control of the system.

The imported filter, in order to prevent the oil pump from sucking oil from the oil tank to suck pollutants into the pump, the filter is set on the suction pipeline of the pump, which can effectively filter out the residual pollutants in the oil tank and the pollutants that enter people through the air, and has the effect of protecting the pump, and the filtration accuracy of the oil filter of the oil suction pipeline is about η≥50%.

Return oil filter, the filter press generally does not have an oil return filter, it is recommended to install a filter on the return line to filter out the pollutants generated in the system before returning to the oil tank.

b: Application of circulating filtration system

The circulating filtration system is an important measure to improve and ensure the cleanliness of the hydraulic system. The difference in saturated vapor pressure at negative pressure is used to separate other liquids, moisture or air from the oil. Molecular adhesion is used to separate soluble and insoluble substances in oil, and solid particles, free water and emulsified water are separated. Every 3-6 months, the hydraulic oil is filtered with a circulating filtration system to remove impurities, and the hydraulic oil tank and pipeline are cleaned at the same time. According to the requirements of the ISO4406 hydraulic system for oil cleanliness, the hydraulic oil cleanliness control index of the automatic diaphragm filter press is 16/13 ISO4406 (>5μm, >15μm).

c: Control contamination while repairing equipment

In the daily maintenance of equipment, attention should be paid to reducing the pollution to the system. An important aspect is not to cause contamination during equipment maintenance, which requires care at all times to ensure that contaminants are not introduced or left in the system.

D: Prevent the piston rod from carrying contaminants into the hydraulic system

In the operation of the filter press, the main piston rod and the flap piston rod are retracted many times, and the hydraulic oil is in contact with the air, if not protected, the exposed metal surface of the piston rod is easy to bring pollutants into the hydraulic system, it is recommended to use a special dust jacket and clean it regularly.

Fourth, the replacement and maintenance of hydraulic oil

After the automatic diaphragm filter press runs for a certain period of time, the hydraulic oil will be affected by high temperature, oxidation, wear, impurities, metal catalysis and other factors and change all the time, if the additives are affected by high temperature, oxidation, wear, etc. in the operation of the equipment, the oil performance is greatly reduced, so the hydraulic oil needs to be checked and maintained during use.

Every 3-6 months, the index of hydraulic oil is inspected, and the water, air, soluble and insoluble substances in the oil can be removed through the circulating filtration system, and the hydraulic oil can be replaced in time after passing the inspection. In the process of changing the oil fluid, the old and new hydraulic oil are not mixed, and the hydraulic oil of the same brand from different manufacturers is not mixed.

The maintenance of the automatic diaphragm filter press is mainly the maintenance of its hydraulic system and transmission, that is, the maintenance of hydraulic oil, grease and hydraulic transmission parts. Use scientific methods to correctly ｓｅｌｅｃｔ, maintain and ｒｅｐｌａｃｅ hydraulic oil to ensure that the hydraulic oil is clean and the oil quality is stable, so that the hydraulic system is controlled and action is in place, so as to ensure the long-term stable and economical operation of the equipment. Therefore, it is important to ensure that the performance indicators of hydraulic oil such as temperature, cleanliness, moisture, and air content are within a reasonable range.