1. Performance grade of construction concrete; From this, choose what kind of mixing host to use. For water conservancy projects, a forced mixing host must be selected. In addition, batching stations and storage bins should be selected according to the types of concrete materials that can be mixed.

2. The workload and duration of concrete construction; Use these two parameters to choose which size of mixing plant to use. Let the total task quantity of concrete be M; The duration of concrete pouring is T; The number of working hours per day is H; If the utilization coefficient is K, the specification of the mixing plant should be X=M/(T * H * K), where K is 0.7-0.9. In the selection process, the transportation condition of the finished concrete should also be considered. For example, is it direct pumping or vehicle transportation. The volume of the conveying vehicle is also an important basis for determining the type of mixing plant.

3. Construction environment and construction objects; When choosing to purchase a concrete mixing plant, the impact of the construction object and construction environment should be fully considered to ensure smooth construction and construction quality. We suggest that you be prepared in the following situations.

A When the construction site requires a large amount of one-time pouring, high quality requirements, and there are no nearby reinforcement mixing plants, it is best to choose two smaller mixing plants or a dual machine configuration with one main and one auxiliary.

B When the transportation on the construction site is inconvenient and maintenance personnel need to spend a lot of time entering and leaving the site, it is best to choose a dual machine station with the same smaller specifications or prepare sufficient spare parts to ensure smooth construction progress.

C When the construction site is relatively scattered but the distance between construction sites is not too far, the conveying radius of concrete mixer trucks should not exceed half an hour's drive, and the conveying radius of dump trucks should not exceed 10 minutes' drive. It is best to use multiple job numbers for centralized mixing to improve the utilization rate and construction economic benefits of the mixing plant.

4. Operator quality; Generally speaking, small mixing plants have simpler structures and control systems, so they have lower requirements for operation and maintenance personnel. However, larger stations have complex structures and high levels of automation, so they also have higher requirements for operators. So when purchasing a mixing plant, in addition to considering the previous factors, you should also consider this factor.

5. Configuration selection; In general, manufacturers have mature product formulations, such as specifications, quantities, varieties, etc. You can make special requests when placing an order for the product. We will do our best to meet your requirements. However, when choosing products, it is important to avoid being greedy and seeking perfection, as this can result in significant economic waste.

In addition, when selecting products, in addition to referring to the prices of different manufacturers, special attention should also be paid to the preparation lists of different manufacturers. In addition to the specifications, varieties, and quantities mentioned above, the most important thing is the manufacturer of the supporting parts. Based on the above items, you can always choose the most suitable model for you. When choosing a model, do not pursue the best, but rather the most suitable and satisfying one that meets your needs, because such a choice is the most economical and effective.

 

As an industrial operation, asphalt mixing plants not only require better maintenance and proper use, but also need to understand the source of faults. From the perspective of the consequences of application, the proportion of asphalt supply in asphalt concrete is related to the degree of error.

1. The asphalt weighing system has stopped for reflection, and the weighing sensor and connecting rod are normal without any signs of stagnation; Upon reflection on the connection cable and plug of the weighing sensor, no abnormalities were found.

2. Calibrate the asphalt weighing sensor (electronic scale) with a 50kg standard weight, and then calibrate with a 200kg standard weight. The data displayed by the accounting machine matches the weight added to the scale, indicating that the sensor, connecting cable, and signal adapter are all intact.

3. Reflection was conducted on the asphalt spraying system spraying pipeline, the oil discharge pipeline from the asphalt weighing hopper to the asphalt spraying pump, and the pipeline from the asphalt spraying pump to the asphalt nozzle of the mixing pot. No deformation or blockage was found.

4. Reflect on the opening stroke of the asphalt weighing hopper's oil discharge valve, open the protective cover on the asphalt weighing hopper, check the opening stroke of the oil discharge valve, and ensure that the oil discharge switch cylinder, connecting rod, and oil discharge valve are functioning properly. The cylinder stroke and oil discharge valve opening are both within useful limits.

5. Reflection on the injection volume of asphalt spraying system, the pump flow rate and pressure are sufficient; Electric power and speed meet the requirements of asphalt radial pump; The clearance between the screw and the pump sleeve is normal; The pump sealing ring is sealed without any leakage phenomenon; The asphalt spraying system is functioning properly.

6. Reflection on the dynamic operation of the asphalt mixing plant, opening the protective cover on the asphalt weighing hopper, and stabilizing the soil mixing plant, focusing on the condition of the oil release switch cylinder, connecting rod, and oil release valve during the task cycle. It was found during the task cycle that the oil release valve of the asphalt weighing hopper was closed early.

Reflection on the consequences indicates that the asphalt mixing plant has a shortage of asphalt supply ratio when producing asphalt mixture with a high oil to stone ratio on the surface layer, because the oil discharge valve of the asphalt weighing hopper was closed early.

 

In the construction of asphalt pavement, the asphalt mixing plant plays a crucial role. The performance and working condition of the asphalt mixing plant directly affect the quality of the asphalt mixture, which is related to the quality and progress of the entire project. Therefore, the current control technology of asphalt mixing plants is becoming increasingly advanced and the technological content is increasing. This requires mechanical operators to continuously improve their operational skills in order to meet construction needs, ensure the normal operation of machinery, and play its due role to ensure project quality and progress.

So how can we ensure the normal operation of machinery and fully utilize its intended functions.

Firstly, the operator should be proficient in the structure and working principle of each part of the mixing plant. Based on this, strict control should be exercised over various production details, especially the metering system, as the quality of the metering work directly affects the technical indicators of the asphalt mixture.

For the stone measurement system, it should be noted that:

(1) Maintain flexible and rapid opening and closing of each discharge door;

(2) All discharge ports should be kept unobstructed, without sediment, to ensure that the stone can flow down quickly and evenly during measurement;

(3) Each discharge door should be closed promptly and sealed properly. At the end of the single material measurement, there should be no leakage of material;

(4) The area around the aggregate weighing hopper should be kept clean and free of foreign objects to prevent the hopper from getting stuck. The aggregate weighing hopper should be kept completely suspended at all times;

(5) Each aggregate weighing sensor should have balanced preloading, consistent force, and sensitive sensing.

For the powder metering system, the following points should be noted:

(1) Keep the powder conveying pipeline unobstructed without any obstruction;

(2) The feeder or valve should be tightly sealed at the end of the measurement process; No powder leakage is allowed;

(3) Regularly remove dust and debris from the powder measuring hopper to keep it clean;

(4) The entire measuring system should be well sealed to prevent the powder from getting damp and clumping;

(5) The powder weighing and unloading should be thorough, and there should be no residual powder inside the weighing. The unloading door should be tightly closed, and there should be no powder leakage during measurement.

Attention should be paid to the asphalt metering system:

(1) Before starting production, the pipeline heating should be sufficient to ensure that the asphalt temperature in the system reaches the specified value;

(2) The asphalt spraying pipeline should be clean and unobstructed, and the nozzle should not be blocked, otherwise the spraying will be uneven and affect the mixing effect;

(3) The asphalt spraying pump or valve should be tightly closed to ensure that there is no dripping after the asphalt spraying is completed;

(4) The action of the asphalt metering conversion valve should be accurate, timely, and well sealed. The suspension of the asphalt metering bucket should be firm and flexible.

For the entire metering system of the asphalt mixing plant, the operator should regularly check it. Check whether each weighing scale is completely suspended and whether there is any jamming phenomenon. Check whether each weighing sensor works normally and whether the sensing is sensitive. Regularly verify to ensure that the displayed values match the actual values. If any problems are found, they should be resolved in a timely manner to ensure that the measuring system is always in good working condition.

Secondly, the operator should accumulate rich experience, be able to foresee most mechanical failures, and solve and eliminate hidden dangers early. After a malfunction occurs, it should be able to accurately diagnose and promptly eliminate it to ensure the normal use of the machinery. To achieve these, in addition to timely maintenance of the machinery according to regulations, the operator also needs to do the following:

(1) Operators should regularly patrol and observe carefully, and carefully inspect frequently moving parts. Check for looseness at all connections, proper lubrication, flexible movement, and abnormal wear, and promptly address any issues found;

(2) The mixing plant is in motion, and you need to listen with your ears, think with your heart, and understand every sound. If there is any abnormal sound. To identify the cause and handle it properly;

(3) Be good at distinguishing various odors. If the oil temperature is too high, the discharge temperature exceeds the limit, the circuit and electrical appliances are short circuited and burned out, the overheating is caused by abnormal friction, and the electrical appliances and circuits are overloaded and severely heated, different odors will be emitted. Through different odors, partial faults can also be foreseen.

In short, the operator should pay attention to checking the appearance and color, using various senses and different instruments to identify each abnormal change, carefully analyze, determine the cause, and identify hidden dangers. Due to the complex structure and diverse types of components of the mixing plant, it involves electrical and pneumatic control systems, asphalt supply systems, combustion systems, metering systems, dust removal systems, etc. It is very difficult for an operator to master all parts, accurately judge and eliminate all faults in a short period of time. Therefore, in order to be an excellent operator, one must observe carefully, think diligently, summarize seriously, and constantly accumulate experience.

In addition to being proficient in equipment, operators should also have knowledge of product quality control. Familiarize oneself with the temperature, oil stone ratio, gradation, and other factors of asphalt mixtures, and be able to make technical judgments on the mixture in a mature manner, analyze and solve problems that arise in the mixture in a timely manner.

(1) Temperature control of the mixture:

The temperature of the mixture is one of the qualification evaluation criteria for the mixture. If the temperature is too high or too low, it is considered waste and cannot be used. Therefore, how to control temperature is one of the basic skills that operators should possess.

The factors that affect the temperature of the mixture include the quality of the fuel. If the quality of the fuel is poor, the calorific value is low, and the combustion is not sufficient, it will cause unstable heating of the stone material, low temperature, and residual materials remaining in the mixture after combustion, seriously affecting the quality of the mixture. If the fuel viscosity is too high, the impurity content is high, and the water content is high. It will cause difficulty in ignition, pipeline blockage, and temperature control; The moisture content of raw materials is another factor that affects temperature. The moisture content of raw materials is relatively high and uneven, making it difficult to control the heating temperature of stone materials during the production process; In addition, the technical condition of the combustion system, the pressure of the fuel supply pump, and the amount of fuel injection are all related to the temperature of the mixture. The wear, leakage, and blockage of the combustion system prevent various components from maintaining their original performance, resulting in low system pressure, unstable fuel supply, poor atomization combustion effect, and serious impact on stirring temperature.

Therefore, experienced operators should be able to accurately judge the quality of fuel, the dryness and wetness of raw materials, and the working condition of the combustion system. Discover problems and take corresponding measures in a timely manner.

Although current mixing equipment has automatic temperature control capabilities, temperature control has a lag due to the process required from temperature detection to adjusting the temperature by adding or subtracting flames. In order to ensure that the mixing temperature of the mixing plant does not produce waste, the operator should carefully observe the rate of temperature change, predict the temperature change results in advance, and manually adjust the flame or feed amount to control the temperature change, so that the change results do not exceed the specified range, thereby reducing or eliminating waste.

(2) Grading control of mixture:

The gradation of the mixture directly affects the performance of the road surface. If the gradation of the mixture is not reasonable, the road surface may suffer from defects such as excessive or insufficient void ratio, permeability, rutting, etc., which will reduce the service life of the road surface and seriously affect the quality of the project. Therefore, controlling the gradation of the mixture is also one of the skills that operators must possess.

The factors that affect the gradation of the mixture include changes in the particle size of the raw materials, changes in the sieve mesh of the mixing plant, and the range of measurement errors.

The particle size of raw materials directly affects the gradation of the mixture. When changes are found in the raw materials, operators should cooperate with the laboratory to fine tune the production mix ratio. The variation of the hot material sieve in the mixing plant is an important factor affecting the gradation of the mixture. If the sieve is blocked and the hot material sieve is not fully screened, the gradation will become finer. If the sieve is broken, damaged, leaked, or worn beyond the limit, the gradation of the mixture will become coarser; The measurement error of the mixing plant also directly affects the grading. If the measurement error range is adjusted too large, it will cause a significant deviation between the production mix proportion and the target mix proportion, seriously affecting the quality of the mixture. If the adjustment of the measurement error range is too small, it will increase the measurement time and affect the output, and it will also frequently exceed the measurement limit, affecting the normal operation of the mixing plant.

In short, operators should pay close attention to changes in raw materials, regularly check the sieve, promptly solve problems, and adjust the measuring range to the optimal state based on the characteristics of the mixing plant and other factors. Carefully consider other factors that affect grading to ensure the mix proportion of the mixture.

(3) Oil stone ratio control of the mixture:

The optimal asphalt aggregate ratio of asphalt mixture is determined by the gradation of mineral aggregate and the content of powder aggregate. It is the fundamental guarantee for the strength and performance of the road surface. Excessive or insufficient asphalt dosage can cause different pavement diseases.

Therefore, strict control of asphalt usage is an important aspect of production control. In production, operators should pay attention to the following aspects:

Try to minimize the error range of asphalt measurement during operation, so as to achieve precise asphalt measurement; The amount of added powder is also an important factor affecting the optimal oil stone ratio, so the measurement of powder should be carefully controlled; Adjust the opening of the induced draft fan reasonably according to the dust content of the fine aggregate, so that the dust content in the mixture is within the design range.

In modern construction, advanced equipment is necessary to ensure the quality of the project, and good operating techniques are also necessary to fully utilize the advantages of the equipment. First class equipment, first-class operational skills, and first-class management are the key to producing first-class products and quality. Only then can we ensure that the project is completed on time, with high quality, and smoothly.

 

1. Air source malfunction

(1) Air compressor faults include: damaged check valve, severe wear of piston ring, damaged intake valve plate, and clogged air filter.

To determine if the check valve is damaged, simply turn off the power after the air compressor has automatically stopped for more than ten seconds, and manually rotate the large tape roller. If it can be easily rotated once, it indicates that the check valve is not damaged; On the contrary, the check valve is damaged; In addition, it can also be judged from the exhaust situation of the exhaust port under the automatic pressure switch. Generally, the exhaust should be stopped after about ten seconds after the air compressor stops automatically. If the exhaust continues until the air compressor starts again, it means that the check valve is damaged and needs to be replaced.

When the pressure of the air compressor rises slowly and accompanied by oil leakage, it indicates that the piston ring of the air compressor has been severely worn and should be replaced in a timely manner.

When the intake valve plate is damaged or the air filter is clogged, it will also cause the pressure of the air compressor to rise slowly (but without oil leakage). When checking, place your palm on the air inlet of the air filter. If there is hot air blowing outwards, it indicates that the intake valve is damaged and needs to be replaced; If the suction is small, it is usually caused by a dirty air filter, and the filter should be cleaned or replaced.

(2) The faults of the pressure reducing valve include: inability to adjust the pressure high, or slow increase in pressure.

The inability to adjust the pressure is often caused by the breakage of the pressure regulating spring or diaphragm, and must be replaced with a new one; The slow increase in pressure is usually caused by clogged filter screens and should be removed for cleaning.

(3) Pipeline faults include leakage at pipeline joints, hose rupture, and accumulation of condensed water.

When there is a leak in the pipeline joint or a hose rupture, the location of the leak can be determined by the sound, and it should be repaired or replaced in a timely manner; If condensed water accumulates in the pipeline, it should be drained in a timely manner. The characteristic is that in winter in the north, condensed water is prone to freeze and block the air path.

(4) The faults of the compressed air processing component (triple unit) include: oil-water separator fault, pressure regulating valve and oil mist device fault.

The faults of oil-water separators can be further divided into situations such as clogged or damaged filter elements, and inflexible moving parts of the drain valve. Regularly clean the filter element during work to remove oil and impurities from the drain.

The malfunction of the pressure regulating valve is the same as the malfunction of the pressure reducing valve mentioned in (2) above.

The fault phenomena of the oil mist device include: no oil dripping, water deposition at the bottom of the oil cup, and damaged sealing ring at the mouth of the oil cup. When the oil mist device does not drip oil, check whether the air flow rate at the inlet is lower than the fogging flow rate, whether there is air leakage, and whether the oil volume adjustment needle valve is blocked; If moisture accumulates at the bottom of the oil cup, it should be promptly removed; When the sealing ring is damaged, it should be replaced in a timely manner.

2. Pneumatic actuator (cylinder) malfunction

Due to improper assembly and long-term use of cylinders, pneumatic actuators (cylinders) are prone to internal and external leakage, insufficient output force, unstable operation, poor buffering effect, and damage to piston rods and cylinder heads.

(1) Internal and external leaks in a cylinder are generally caused by eccentric installation of the piston rod, insufficient supply of lubricating oil, wear or damage to the sealing ring and sealing ring, impurities in the cylinder, and scratches on the piston rod. Therefore, when there is internal or external leakage in the cylinder, the center of the piston rod should be readjusted to ensure the coaxiality between the piston rod and the cylinder barrel; Regularly check the reliability of the oil mist device to ensure good lubrication of the actuator components; When the sealing ring and sealing ring are worn or damaged, they must be replaced in a timely manner; If there are impurities in the cylinder, they should be removed in a timely manner; When there are scars on the piston rod, it should be replaced with a new one.

(2) The insufficient output force and unstable movement of the cylinder are generally caused by the piston or piston rod being stuck, poor lubrication, insufficient air supply, or condensation water and impurities in the cylinder. For this, the center of the piston rod should be adjusted; Check whether the operation of the oil mist device is reliable; Is the gas supply pipeline blocked. When there is condensed water and impurities in the cylinder, they should be removed in a timely manner.

(3) The poor buffering effect of the cylinder is generally caused by wear of the buffering sealing ring or damage to the adjusting screw. At this point, the sealing ring and adjusting screw should be replaced.

(4) Damage to the piston rod and cylinder head of a cylinder is usually caused by eccentric installation of the piston rod or ineffective buffering mechanism. For this, the center position of the piston rod should be adjusted; Replace the buffer seal ring or adjust the screw.

3. Fault in directional valve

The faults of the reversing valve include: the valve cannot reverse or the reversing action is slow, gas leakage, and the electromagnetic pilot valve is faulty.

(1) The inability or slow switching action of the directional valve is generally caused by poor lubrication, spring jamming or damage, oil stains or impurities jamming the sliding part, and other reasons. For this, it is necessary to first check whether the oil mist device is working properly; Is the viscosity of the lubricating oil appropriate. If necessary, the lubricating oil should be replaced, the sliding parts of the directional valve should be cleaned, or the spring and directional valve should be replaced.

(2) After prolonged use, directional valves are prone to wear on the valve core sealing ring, damage to the valve stem and seat, resulting in gas leakage inside the valve, slow valve movement, or inability to reverse direction normally. At this point, the sealing ring, valve stem, and valve seat should be replaced, or the directional valve should be replaced with a new one.

(3) If the inlet and outlet holes of the electromagnetic pilot valve are blocked by debris such as oil sludge, poorly sealed, the movable iron core is stuck, or there is a fault in the circuit, it can all cause the reversing valve to fail to reverse direction normally. For the first three situations, the oil sludge and impurities on the pilot valve and movable iron core should be cleaned. Circuit faults are generally divided into two categories: control circuit faults and electromagnetic coil faults. Before checking for circuit faults, the manual knob of the directional valve should be turned a few times to see if the directional valve can change direction normally under the rated air pressure. If it can change direction normally, it is a fault in the circuit. During inspection, an instrument can be used to measure the voltage of the electromagnetic coil to see if it has reached the rated voltage. If the voltage is too low, further inspection of the power supply and associated travel switch circuit in the control circuit should be carried out. If the reversing valve cannot reverse direction normally under rated voltage, the connector (plug) of the electromagnetic coil should be checked for looseness or loose contact. The method is to unplug the plug and measure the resistance of the coil (usually between a few hundred ohms and a few thousand ohms). If the resistance is too high or too low, it indicates that the electromagnetic coil is damaged and should be replaced.

4. Malfunction of pneumatic auxiliary components

The main faults of pneumatic transmission components include: oil mist device failure, automatic drain device failure, muffler failure, etc.

The faults of the oil mist device include: the adjustment amount of the adjusting needle is too small, the oil circuit is blocked, and the pipeline leaks, which can prevent the liquid oil droplets from atomizing. Regarding this, blockages and leaks should be promptly addressed, and the oil drip rate should be adjusted to around 5 drops per minute. During normal use, the oil level in the oil cup should be kept within the upper and lower limits. The water deposited at the bottom of the oil cup should be promptly removed.

 

The stable soil mixing station has a large workload, and long-term work can generate a lot of pressure, so some common problems often arise. Don't rush when problems arise, there are always solutions. Below are some common troubleshooting methods.

1、 Air source malfunction. The common gas source failures in stabilized soil mixing stations mainly occur in air compressors, pressure reducing valves, pipelines, and compressed air processing components. If the pressure cannot be adjusted high, it is often due to the breakage of the pressure regulating spring or the rupture of the diaphragm, which must be replaced; The pressure rises slowly, usually due to clogged filter screens, and should be removed and cleaned.

2、 Cylinder malfunction. Leakage inside and outside the cylinder is generally caused by eccentric installation of the piston rod, insufficient supply of lubricating oil, wear or damage of the sealing ring and sealing ring, impurities in the cylinder, and scratches on the piston rod. The center position of the piston rod should be readjusted, and the reliability of the oil mist device should be checked regularly to promptly remove impurities from the cylinder; When there are scars on the piston rod, a new part should be replaced.

3、 Reversing valve malfunction. The inlet and outlet holes of the pilot solenoid valve are blocked by debris such as oil sludge, resulting in poor sealing, the movable valve core being stuck, and circuit faults, all of which can cause the directional valve to fail to change direction normally. Oil sludge and other impurities on the pilot solenoid valve and movable valve core should be cleaned in a timely manner.

4、 Pneumatic auxiliary component malfunction. The oil and moisture in the automatic sewage discharge device of the stabilized soil mixing plant sometimes cannot be automatically discharged, and should be removed for inspection and cleaning. When the muffler installed on the directional valve is too dirty or blocked, it will also affect the sensitivity of the directional valve, and the muffler should be cleaned regularly.

Don't be in a hurry when encountering these problems, these methods can help solve them. It is important to pay attention to maintenance when using them, as this is the best way to maintain machinery.

 

How to control the quality of concrete produced in a concrete mixing plant? Firstly, the mix proportion of concrete should be correct; Secondly, the weighing system in the mixing plant should be precise; Thirdly, the selection of raw material quality is accurate. The following are the requirements for controlling the selection of concrete raw materials: the quality of cement, coarse and fine aggregates, additives, and mineral admixtures should be strictly controlled from the source, and the quality requirements of raw materials should be clearly stated in the supply contract.

1. Cement: Cement must be sampled and inspected according to regulations before entering the site. Each batch of cement entering the site is required to undergo standard consistency and temperature testing in a timely manner. Those with doubts about the quality are strictly prohibited from entering the warehouse, and other indicators (such as stability) testing must continue. Cement that fails the inspection is strictly prohibited from entering the site. It is strictly prohibited to directly use hot cement without homogenization (digestion) in engineering. The used cement should be traced and a "Cement Usage Traceability Form" should be filled out.

2. Aggregates: Coarse and fine aggregates must be sampled and inspected according to regulations before they can be used. Coarse aggregate should be selected from crushed stones or pebbles with reasonable grading, good particle shape, uniform and strong texture. Various indicators of coarse aggregate should meet the requirements of relevant standards and specifications; Control the mud content and mud block content, conduct timely testing, and strictly prohibit the entry and unloading of vehicles that fail the inspection.

3. Admixtures: When admixtures enter the site, inspection and testing should be strengthened. Check whether the packaging of admixtures clearly indicates the following contents: product name, model, net content or volume (including content or concentration), manufacturer name, production date and factory number; Check whether the contents indicated on the packaging match the product manual and certificate of conformity provided by the manufacturer; Whether liquid additives precipitate and whether they have exceeded their expiration date.

4. Mineral additives: tested according to the requirements of relevant standards and specifications. The laboratory should constantly monitor the quality changes of mineral additives. When mineral additives enter the site, they must be tested for water demand ratio, loss on ignition, and fineness. Only products that pass the inspection can be stored; And pay attention to comparing with the results of previous experiments to determine the fluctuation of quality and ensure the quality of the project. During the use of mineral additives, the relative stability of the additives should be ensured as much as possible. Communication should be made with the material department to ensure that for similar additives, a mixing plant should use products from the same manufacturer as much as possible. When the requirements cannot be met, the testing department should promptly adjust the mix proportion and strictly prohibit the mixing of mineral additives.

5. The material handler at the mixing plant should pay timely attention to the inventory situation, have foresight and a sense of crisis, actively organize material preparation, avoid work stoppage and waiting for materials, and pay special attention to the inventory of bulk cement. Inventory materials should be labeled and marked to ensure the stacking of materials on site at all times, and raw materials should be stored strictly according to warehouse classification.

 

After the installation and commissioning of the concrete mixing plant equipment, due to factors such as the processing, assembly, and adjustment of new machine components, the friction surface is rough, the contact area of the mating surface is small, and the surface pressure state is uneven, resulting in a running in period. What are the characteristics of the running in period of concrete mixing plants? There are mainly five aspects: fast wear, poor lubrication, looseness, leakage, and frequent operational errors. Below are detailed introductions to these aspects:

1. Fast wear rate

Due to the influence of factors such as processing, assembly, and adjustment of new machine components, the friction surface is rough, the contact area of the mating surface is small, and the surface pressure state is uneven. During the operation of the machine, the concave and convex parts on the surface of the parts interlock and rub against each other, and the metal debris that falls off serves as abrasives, continuously participating in friction and accelerating the wear of the mating surfaces of the parts. Therefore, during the break in period, it is easy to cause wear on components (especially mating surfaces), and the wear rate is fast. At this point, if overloaded operations occur, it may lead to damage to components and early failures. For example: blades of the main engine of the mixing plant;

2. Poor lubrication

Due to the small fit clearance of newly assembled components and the difficulty in ensuring the uniformity of fit clearance due to assembly and other reasons, lubricating oil (grease) is not easy to form a uniform oil film on the friction surface to prevent wear. As a result, the lubrication efficiency is reduced, causing early abnormal wear of the components. In severe cases, it can cause scratches or biting on the friction surface of precision fit, leading to the occurrence of faults.

3. Causing looseness

The newly processed and assembled components have deviations in geometric shape and fitting dimensions. In the early stages of application, due to alternating loads such as impact and vibration, as well as factors such as heat and deformation, and rapid wear, the originally fastened components are easily loosened.

4. Leakage occurs

Due to the looseness, vibration, and thermal effects of machine components, leakage may occur at the sealing surfaces and pipe joints of the machine; Some drawbacks such as casting and processing are difficult to invent during assembly and debugging, but due to vibration and impact during the operation process, these drawbacks are exposed, manifested as oil (water) leakage. Therefore, leakage is prone to occur during the running in period.

5. Multiple operational errors

Due to insufficient understanding of the structure and performance of the machine (especially for new operators), it is easy to cause malfunctions and even mechanical accidents due to operational errors.

 

Ensure that the concrete mixing plant undergoes pre use inspection, post use maintenance, weekly inspection and maintenance, weekly inspection and maintenance, as well as annual inspection and maintenance and major repairs. What parts need to be inspected and maintained for each type of inspection? The Zhengzhou Fulaier Concrete Mixing Plant website will provide you with a detailed introduction: In order to ensure the normal operation of the mixing plant and fully utilize its benefits, maintenance and repair of the mixing plant should be carried out.

1. Check before each use

Check whether the self-protection device of the air compressor is reliable and whether the air pressure is stable; Check if the water pump is fully filled and if the pipeline is unobstructed; Whether the opening and closing of hopper doors, cement hopper doors, intermediate aggregate hopper doors, discharge doors, etc. are flexible and reliable; Check if the connecting bolts of the mixing host blades are secure; Check whether each electrical device is safe and reliable, and whether each limit switch action switch is flexible and reliable; Check if there is sufficient lubricating oil in the emergency gearbox at each lubrication point.

2. After use maintenance for each shift

Clean up the accumulated materials inside and outside the mixer, as well as on the material door, and rinse them clean; Add lubrication points to each lubrication point, especially at the shaft end seal, which must not be missed; During winter, the liquid in the waterway should be drained; Drain the gas and accumulated water from the air compressor storage cylinder; After shutdown, all switches are in a non working state and the power is cut off.

3. Weekly inspection and maintenance

Check the setting of residual concrete in the mixing tank of the main unit of the mixing plant. If there is any setting, stop the machine and remove it (note that the power should be cut off and a dedicated person should supervise). Check the gap between the mixing blades and the lining plate, and adjust it if it is not suitable; Check if there is any air leakage in the pneumatic system and if the cylinder operation is reliable; Check the quality and liquid level of the lubricating oil in the gearbox, and add or replace it if necessary; Check if the suction bottom valve in the water supply system is reliable; Check for any damage to electrical components, repair or replace as necessary, and inspect for loose wiring; Unscrew the blockage and check the sealing condition of the shaft end. If there are no abnormalities, then screw in the blockage.

4. Surrounding inspection and maintenance

Check the tension of the belt and make appropriate adjustments; Check the wear of the blades and lining plates; Check whether the connecting bolts of the upper and lower frames, material bin, large inclined belt conveyor and other components are firm, and whether the foundation has sunk; Check for lumps and debris inside the bolt conveyor, and remove them if present.

5. Annual inspection, maintenance, and major repairs

After running the equipment for one year, in addition to checking items 1, 2, 3, and 4, other components should also be inspected for comprehensive inspection, maintenance, and replacement.