The following article is for jaw crusher maintenance and repair, composed by technical team of Henan Deya Machinery Co., Ltd..
Jaw crusher is a widely use crushing machine in the aggregate plant and mineral process plant, it is mainly used to crush the raw materials to smaller pieces which are suitable for transportation, use and grinding. It has the advantages of simple structure, reliable operation, easy maintenance and low production costs.
The working principle of the jaw crusher is: the electric motor transmits the power to the eccentric shaft through the transmission device, and the eccentric movement of the eccentric shaft makes the movable jaw swing reciprocally relative to the fixed jaw, and the material falling into the crushing chamber is crushed by repeated extrusion, splitting and bending. Due to the heavy workload, harsh working conditions and complex stresses of the jaw crusher, breakdowns are inevitable during production. Therefore, the maintenance technology of the jaw crusher is related to the utilization rate, production cost, economic efficiency and service life of the equipment.
1. Jaw crusher maintenance and operation
The operation and maintenance of the jaw crusher is very important. Proper operation and maintenance not only helps to improve the production capacity of the crusher, but also effectively extends the service life of the crusher, while improper operation and maintenance or negligence in operation are often important causes of accidents.
1.1 Preparation work before starting
(1) Check whether the main parts are intact, whether the fastening bolts and other connections are loose, and whether the safety devices are complete.
(2) Check whether the feeding equipment, conveying equipment, electrical equipment, etc. are in good condition.
(3) Check whether the lubrication device is good, check whether the cooling water pipe valve is open.
1.2 Start-up and normal operation
(1) Start the jaw crusher in strict accordance with the operating procedures, the starting sequence of the jaw crusher is by reversed production process.
(2) Pay attention to the ammeter indication on the control cabinet when starting the main motor, the current will drop to the normal working current value after 20-30s.
(3) Adjust and control the feeding, so that the feeding is uniform and the particle size of the material does not exceed 80%-90% of the inlet width.
(4) Pay attention to the temperature of the bearing, the general sliding bearing temperature should not exceed 60 ℃, rolling bearing temperature should not exceed 70 ℃.
(5) When the electrical equipment automatically tripped, the cause should be identified, forbidden to force continuous start.
(6) In case of mechanical failure and personal accident, stop immediately.
1.3 Precautions when stopping
(1) The stopping order of the jaw crusher is the opposite of the starting order, i.e. in the direction of the production process.
(2) The lubrication and cooling system should be stopped only after the crusher has been stopped, and the circulating cooling water in the bearings should be drained after stopping in winter to avoid the bearings from freezing and cracking.
(3) After shutdown, clean up the sanitary work carefully and check the working condition of all parts of the machine.
The connecting rod bearing, eccentric shaft bearing and thrust plate elbow head of the jaw crusher are lubricated with oil. 70# mechanical oil is suitable in summer, while 40# mechanical oil can be used in winter. If the crusher often works continuously, and there is a lubricating oil heating device in winter, and the ambient temperature is not too high in summer, the crusher can be lubricated with 50# mechanical oil.
Most of the connecting rod bearings and eccentric shaft bearings of large and medium-sized jaw crushers use pressure cycle lubrication. Generally, the motor-driven gear oil pump (or other kinds of oil pump) will be used to press the oil in the oil storage tank into the lubrication part through the pressure tube, and the pressure tube will also pass through the filter and oil cooler, so that the lubricating oil can be filtered and cooled before lubrication, in order to maintain the cleanliness and certain viscosity of the lubricating oil.
In addition, some have oil temperature heaters, and the lubricant can be pre-heated and used in winter. When the oil pump suddenly fails, the crusher needs 15~20min to stop due to the large swing force, then the oil pump should be used to give oil by hand to keep the bearings lubricated without the accident of burning the bearings. The jaw suspension shaft bearing and the elbow head of the thrust plate are generally lubricated by an electric dry oil pump or a manual dry oil pump to achieve pressure lubrication. The bearings of the jaw suspension shaft of a small jaw crusher are usually greased with a grease cup, approximately once every 40-60 minutes. The elbow head of the thrust plate is dripped with thick oil, usually every 3~4h.
1.5 Inspection and Maintenance
The daily inspection and maintenance of the jaw crusher are mainly as follows
(1) Check the heat of the bearings, make sure it is within the normal range indicated by Deya Machinery’s operation manual.
(2) Check whether the lubrication system is working properly.
(3) Check the quality of the oil return pipe.
(4) Check whether the bolts, flywheel keys and other connecting parts are loose.
(5) Check the wear of jaw plate and transmission parts, and check whether the tension rod spring has cracks and works normally.
(6) Keep the equipment clean, make sure there is no dust, no leakage of oil, water and electricity.
(7) Regularly use gasoline to clean the filter of lubricating oil, after cleaning wait for completely cool and dry before continuing to use.
(8) Regularly replace the lubricant in the oil tank.
2. Repair of Jaw Crusher
2.1 Repair and replacement of the thrust plate and plate holder
The thrust plate of a jaw crusher is mostly made of cast iron, and the thrust plate seat is mostly cast steel or cast iron in variant. The thrust plate is used to transmit motion and force, as well as for safety and protection, and to adjust the size of the discharge. As the thrust plate is installed in the lower part of the body, it is not easy to maintain, so the plate head and the plate seat are most prone to wear. After the wear of the plate head and plate seat, can be repaired by overlay welding after processing, spraying, brushing and other methods. When the thrust plate is broken, because it is difficult to meet the functional role, generally can not be repaired, but should be replaced by a new thrust plate, but for the combined thrust plate, the plate head can be removed to continue to use.
2.1.1 Repair of the moving jaw
Common forms of damage to the movable jaw of a compound jaw crusher are: bore wear, broken spring tie rod hooks and local cracks or overload fractures. Due to the heavy weight and complex manufacturing of the movable jaw, it is one of the main components of the jaw crusher and should be repaired by various methods instead of simply replacing it after damage.
For small and medium jaw crushers, there are two types of movable jaw bore assemblies: one with a barite bushing in the bore, and the other with a rolling bearing in the bore. When the bushings are worn, the spare bushings can be replaced, and then the bushings can be repaired or re-poured. Installed rolling bearing bore, due to micro-motion wear, poor installation, or long-term work, often encounter rolling bearing outer ring loosening and bore wear, the repair method has bore welding and bore set two.
Inner hole welding is the use of manual arc welding at both ends of the inner hole, welding a layer of the same or similar materials, and then re-expansion processing, re-expansion technology must be designed to match the accuracy of the implementation.
The bore-set method of repairing movable jaws is a complex process, but it is suitable for cast iron movable jaws, and the repair process is greatly simplified by replacing the bore-set if the bore is worn again. The bore is bored out, a special sleeve is inserted in the bore to compensate for wear, and the bore is machined to its basic size according to the fit requirements.
2.1.2 Cracking and fracture repair of movable jaws
Cracks and fractures in movable jaws and simple oscillating connecting rods are usually found in the lower part of the jaws, mostly due to abnormal operation and manufacturing quality. When the movable jaws are cracked, a common repair method is the reinforcement super metal buckling method. The metal buckling method is a repair method that uses a special joint made of high-strength alloy steel, the wave key, to mechanically buckle the crack and the two ends of the fracture surface on the machine. If broken, should open a double-sided bevel for welding repair, in order to be safe and reliable, can also be used in the welding seam welding reinforcement plate and other measures.
2.1.3 Spring tie rod hook fracture repair
Tie rod hooks sometimes fracture due to casting defects or due to fatigue or overload. For cast steel movable jaws, manual arc welding can be used to repair the problem. For cast iron movable jaws, one hook can be set.
Some of the spring tie rods of the Simple Pendulum Jaw Crusher are mounted with pins on one pair of lugs of the pendulum, which are cast steel lugs and can be repaired by welding when the pin holes are worn.
2.2 Eccentric Shaft and Bearing Repair
Wear of the eccentric shaft and bearings is common in jaw crushers with sliding bearings.
2.2.1 Repair of eccentric shafts
The main forms of wear of eccentric shafts are severe wear of journals and eccentric section journals, excessive bending of the shaft line and fatigue fracture. If the shaft is straightened and corrected and the broken shaft is repaired, the repair process is complicated and the repair quality is not easy to guarantee, so it is rarely used. If such phenomena occur, the shaft will be scrapped or the shaft material will be reused for other purposes. A small amount of abrasion on the journal or a slight area of wear or pulling can be repaired by hand grinding or diamond grinding; it can also be repaired by on-site brushing. Heavy wear can be repaired by the following three methods.
(1)Turn the worn journal smoothly and use the minimum machining amount to ensure the design surface roughness. Then use the machined journal size and its deviation as the reference, and fit the bearing according to the original design fit performance.
(2)Manual arc welding overlay journal surface, then cutting and machining to achieve the original design journal size. Surfacing should be correctly selected surfacing process to prevent distortion of the distraction shaft bending. Cladding should be reasonable selection of welding rod, welding rod diameter should be small, the current intensity should not be too high. A reasonable centering reference should be selected for machining after cladding to maintain the running accuracy after assembly.
(3) Journal insert sleeve, the worn journal will be turned smooth, and another steel sleeve will be made, the inner hole of the steel sleeve and the journal should be interference fit (S7/h6), the outer diameter should be processed according to the original design size and tolerance. The steel sleeve should be hot fitted to the journal. The thickness dimension of the steel sleeve should meet D-d>b, D is the outer diameter of the steel sleeve, d is the diameter of the journal, and b is the thickness of the bearing at the journal fit (thickness of copper bush or bartonite).
2.2.2 Repair of bearings
Commonly used materials for sliding bearings are bronze and pasteurized alloy. The crusher with circulating lubrication, due to good lubrication and cooling conditions, the bearings have less accidental wear, when the shaft bush wear, replace the new bush to restore its performance. Oil pool lubrication or dry oil lubrication of the bearing, there are more accidental wear, generally by manual scraping method to repair. More serious wear and tear can be used to repair the local welding, scraping method to repair.
For bearing bush lining scraping should meet the following requirements: under the bush and shaft contact range (i.e., contact angle) in 60 ° ~ 90 °; in the contact range, contact accuracy should reach lcm2 within 1 ~ 2 contact points; bush lining on both sides and between the journal with appropriate side clearance, on the bush and bearing should be specified top clearance, top clearance for the journal diameter of 0.1% ~ 0.2%, side clearance for the top clearance of half; lining bush and shaft There should be proper axial clearance between the liner and the shaft.
If the cylindrical rolling bearing is damaged, it must be replaced with a new rolling bearing; if the inner ring of the bearing is slightly worn, the inner ring and journal of the rolling bearing can be repaired on site with metal brushing technology.
Brush plating of parts, also known as rapid plating, is a new technology for the rapid local electrochemical deposition of metals on the surface of parts. Brushing can repeatedly repair the surface wear parts, improve the service life of the parts, therefore, can reduce the amount of spare parts stock. Brush plating can be applied with different brushing solutions to obtain different materials according to the different conditions of wear resistance, acid resistance and high temperature resistance of the parts.
2.3 Repair of jaws and side liners
The jaws, also called tooth plates, have fixed jaws mounted on the body and movable jaws mounted on the movable jaws, and side liners mounted on the body at the ends of the two jaws. The jaws crush the material directly and are subjected to material reaction forces and material friction. The jaw plate is the most wearable part of the jaw crusher. To improve its wear resistance and impact resistance, it is generally made of high manganese steel. To increase the crushing force and reduce the size of the material, the jaw plate has a triangular tooth surface.
When the lower teeth of the jaws are ground flat, they can be turned up or down. The side liner is mostly made of cast steel, which is a chiseled abrasive wear part. When 3/5 of the jaw height is worn away and 3/5 of the thickness of the side liner is worn, the new jaw and side liner should be replaced, and the replacement jaw and liner can be repaired by overlay welding. When repairing the tooth shape of the jaw plate by overlay welding, a combination of overlay welding method can be used, i.e. structural welding rod for the bottom layer, alloy steel welding rod for the middle of the transition layer, the tooth surface layer with wear-resistant alloy steel or high manganese steel welding rod overlay welding, so that the core of the jaw plate teeth not only has good toughness, the surface layer also has high hardness and wear resistance.
2.4 Frame repair
The frame of a jaw crusher, if it is a combination frame, is mostly a combination of welded profiles or cast steel parts. Small crusher frames are mostly made of cast iron. After many years of operation, the frame will be partially cracked or deformed, and the various connection holes will be worn large or deviated.
2.4.1 Repair of frame cracks
Cracks in the frame mostly occur in the stress concentration area, or the original frame has casting defects. Frame cracks can be repaired by welding repair method, and can also be repaired by metal fastening method.
2.4.2 Screw hole and through-hole wear repair
As the jaw crusher works with great vibration, the micro-motion wear during long-term work, the screw slip buckle, screw hole grinding large, through-hole wear, such as the foot bolt hole, bearing screw hole, spring tie frame support hole, etc.. After these holes wear, in addition to welding repair, bolt through-hole can be added welding pad or increase the thread diameter to replace the bolt.
3. Common faults and repair methods
The common failures of the jaw crusher, the causes of the failures, and the measures to deal with and repair them are shown in Table 1.
Jaw crusher is an important equipment for brick and bush production. It has simple structure, reliable operation, wide application, convenient operation and maintenance, low cost of equipment, strong crushing capacity, and is suitable for coarse and medium crushing of hard lumpy materials. However, it generates a large inertia force when working, the parts are subjected to a large load, the energy consumption is relatively high, the crushing ratio is not large, the product size is not uniform, and it is not suitable for crushing sticky wet and dry flaky materials. As the jaw crusher is a powerful crushing machine, the parts are easily damaged during the work, resulting in frequent problems and failures of the equipment. If the malfunction is not properly maintained or repaired in time, it will not only affect the crushing efficiency and product quality, but also affect the normal production. Therefore, it is important to master the basic knowledge of jaw crusher maintenance, to accurately and timely eliminate all kinds of malfunctions and problems in the production equipment, to ensure the safe, reliable and efficient operation of the machine, and to maintain the stable and smooth production.
Table 1 Main faults and treatment of jaw crushers
|1||The temperature of the bearing exceeds the allowable value, and the temperature of the return oil exceeds 60℃.||1. Bearing bush is pressed too tightly||1. Use shims to adjust the compression degree of the shaft bush|
|2. Insufficient lubricating oil, blocked lubricating oil path, unclean lubricating oil||2. Increase the amount of lubricating oil, clean the oil groove and lubricating oil path, and replace the lubricating oil|
|3. uneven bearing scraping, uneven force on the shaft bush||3. Check the shaft level and position, re-scraping the bearing|
|4. Interruption of cooling water||4. check the cooling system|
|2||The temperature of water discharged from the cooler is too high, the temperature exceeds 45℃||1. Insufficient cooling water, cooling system pollution||1. Increase the water supply to the cooling system and clean the cooling system|
|2. Severe heating of bearings||2. Check the bearings and deal with them|
|3||Oil flow indicator cut off||1. Oil pump failure||1. Check the oil pump, repair or replace the oil pump|
|2. Oil viscosity increases due to low temperature||2. Heat the oil properly|
|3. The switch is closed too tightly||3. check whether the switch gate valve has been opened|
|4. Leakage in the pipe||4. Check, clean and unclog the pipes|
|4||The oil pressure of the oil feed system increases and the bearing and return temperatures rise accordingly.||Oil pipe or crusher parts in the oil resistance ditch plug, oil impurity, impurities||1. Stop the crusher operation, clean the oil pipe and the oil groove in the crusher parts|
|2. Check the oil or change the oil|
|5||Water enters the oil feed system||1. The pressure of cooling water in the filter cooler is higher than the pressure of oil in the oil feed system||1. Make the pressure of cooling water about 50kpa higher than the pressure of oil pipe|
|2. Leakage of cooling water pipe||2. Check and repair the water leakage|
|6||The crushing jaws shake and produce a metallic impact sound||1. Loose jaw plate set screw||1. Stop the operation, check the fixing screws and tighten|
|2. jaw plate liner is off||2. Check the gasket, if it is off, should be re-gasketed|
|3. Fixed wedge iron is not tight||3. Squeeze the wedge iron tightly|
|7||Thrust plate support produces impact sound||1. Insufficient spring tension or broken spring, worn support pad||1. Adjust the spring tensioning force, replace the spring and support pad|
|2. Fastening bolt cap is not locked||2. Tighten the nut and adjust the tightness|
|8||Impact sound from the connecting rod head or eccentric shaft plate||Eccentric shaft bearing wear||Rescrape the shaft bush, or replace it with a new one|
|9||Increased particle size of crushed product||Significant wear on the lower part of the tooth plate||Turn the tooth plate 180° or adjust the size of the protruding mouth|
|10||Strong metal fracture sound, the moving jaw stops swinging, and the flywheel continues to rotate, the connecting rod swings back and forth, and the tie rod is slack||1. metal enters the jaws and fractures the thrust plate||1. Replace the thrust plate|
|2. The connecting rod is broken||2. Repair or replace the connecting rod|
|11||Flywheel rotates, crusher stops working, thrust plate falls off||Spring damage, tie rod damage or tie rod nut detachment||Check damaged parts and replace them, install thrust elbow|
|12||The flywheel oscillates significantly, and the eccentric shaft rotates slowly||Loose or damaged keys of belt pulley and flywheel||Stop operation, repair keyway, replace key|
|13||Crash sound in the lower part of the breakage||Tie rod spring loss of elasticity or damage||Spring replacement|
|14||Full machine vibration||Loose fastening screws, especially loose screws and loose ground bolts of the combined frame||Systematically tighten all screws and check the level of the crusher|