Analysis of agricultural machinery overhaul fundamentals

In recent years, with the promotion of the use of agricultural machinery and the development of the rural economy, in the country promulgated the “Agricultural Mechanization Promotion Law”, the implementation of agricultural machinery purchase subsidies related to the promotion of the policy, mountain small agricultural mechanization technology and tools in the southern hilly mountainous areas have been widely used, the development of the rapid, only microtiller ownership in the southwest at an average annual growth rate of nearly 30%, is gradually becoming the mountain agricultural production One of the main agricultural machinery.

Affected by geographical conditions and technical level, the use and maintenance of agricultural machinery in mountainous areas is backward, resulting in low level of machinery, poor quality of operation, high failure rate, and even more casualties.

When the agricultural machinery failure anomalies, can not work or work quality is not high, it is necessary to check and repair the machinery to restore its work performance. As the vast majority of agricultural machinery users lack basic maintenance techniques, there is no suitable maintenance site maintenance tools and accessories.

Due to the lack of maintenance technology, experience and less, the need for repair of agricultural machinery more difficult or more serious failure, can only be sent to a special repair store to repair or ask professional agricultural machinery maintenance personnel to overhaul to ensure the quality of agricultural machinery maintenance. Here I am on the common agricultural machinery fault generation principle, fault diagnosis, maintenance of general methods and procedures to do a simple introduction to help agricultural machinery use personnel to recognize the general fault, can remove and simple operation fault by themselves. The concept of failure, machinery in the process of use, due to wear and tear of parts, deformation, corrosion or other reasons caused by the relative position of parts, the ability to work down or lost.

Such as engine starting difficulties, increased fuel consumption, power down or other abnormalities (such as oil leaks, water leaks, gas leaks, abnormal sounds, etc.), or even can not work, when some of its technical indicators exceed the permissible limit, it is said that the machinery has a fault.

Machinery has a fault, should take the necessary technical measures to eliminate, not “sick” work. Otherwise, a vicious circle will be formed, intensifying the wear and tear of parts, causing more serious failures, and even lead to accidental cycle. Some mechanical problems, after the necessary maintenance, adjustment, can be eliminated. Such as valve clearance is too large or too small; injectors due to improper adjustment of insufficient pressure; loose bolts and screws, or loose pipes lead to oil leakage, water leakage, gas leakage, etc.. And oil pump plunger wear, piston ring wear and other conditions occur, it is necessary to immediately repair, in order to restore the normal working performance of agricultural machinery.

The formation and causes of agricultural machinery failure

The formation of the fault is due to the parts or parts with one or another wear or damage, that is, the parts or parts with defects. Its manifestations are several.

1, the connection with the nature of damage. Mainly refers to the dynamic, static with the nature of the damage. Parts with the main gap between the fit (dynamic fit), excessive fit and excess fit (static fit) and other forms. When the nature of the fit is damaged, machine operation abnormalities, that is, the formation of a fault. Such as crankshaft bearings and journal working surface wear, clearance increases, the oil will leak out, resulting in a drop in oil pressure, poor lubrication, increased resistance, higher temperature, and knocking sound.

2, the relationship between the mutual position of the parts does not meet the requirements. Mutual position relationship between parts (between shaft and shaft, between gears, etc.) in the design and assembly, there are certain requirements to ensure that the movement between the parts flexible and normal work. After the mutual position relationship changes (such as parallelism, perpendicularity, concentricity, center distance does not meet the requirements), the parts may appear abnormal wear or other mechanical damage, the formation of failure. This defect is due to the foundation parts (such as cylinder block) has been deformed, or installation base (such as bearing seat) was damaged.

3, institutional workability decline or loss. Agricultural machinery consists of a number of components, in the work process, the need for the institutions according to the prescribed time, mutual relations and the corresponding work quality of accurate coordination of action (such as oil supply time, oil supply quality and fire time coordination), if this coordination relationship is damaged will form a failure.

4, defects in the working ability of the parts. Some failures are caused directly by defects in the parts, which are manifested in the geometry, surface quality, mechanical properties, physical and chemical properties of the parts have changed. Such as oil seal wear or aging deformation, bending or misalignment of the shaft, increased roughness of the journal or rust oxidation, etc. can also cause failure.

Turning to the causes of agricultural machinery failure formation.

1, natural damage. Under normal circumstances, machinery after long-term use or parking, due to the mutual friction and wear of mating parts, long-term exposure to high temperature, subject to various nature of the load, as well as the corrosive effect of surrounding media, so that the surface of the parts are worn and corroded, material fatigue or aging, resulting in mechanical failure. These phenomena in the process of agricultural machinery work is bound to happen, people can only be properly mitigated through technical measures, but can not fundamentally eliminate it, so called natural damage or natural deterioration.

2, manufacturing and maintenance defects. Parts manufacturing and maintenance of poor quality, such as materials and processing and repair quality does not meet the requirements, etc., improper assembly and adjustment, can cause failure.

3, improper transportation and storage. Such as transportation and storage process of collision, extrusion, moisture, cold, long shaft type parts flat, etc., may become mechanical failure potential.

4, improper use and maintenance. Machinery has certain operating procedures and maintenance measures, must be in accordance with the requirements of the instruction manual and general mechanical principles of correct use, maintenance on time. Illegal operation and maintenance, often cause failures and even accidents. Such as winter parking without cooling water, may lead to freezing and cracking of the machine; engine long-term oil replacement or use of poor quality oil will lead to crankshaft, cylinder rapid wear and so on.

Agricultural machinery common failure phenomenon

1, the role of abnormal. Some institutions, systems or parts can not be completed by people’s instructions or prescribed action. Such as pressing the start switch engine does not start, step down the clutch pedal clutch separation is unclear, start or shift gears when hanging gears, take off the gears difficult, trigger the hydraulic lifting handle hanging implements can not rise, the generator does not generate electricity, engine speed control does not work.

2, sound abnormal. Machinery appears all kinds of repeated changes in the abnormal sound and vibration. Such as machine parts collide with each other to send out a variety of knocking sound, high pressure waves on the metal impact generated by the knocking sound, continuous vibration of the whistling sound of the machine parts, the sibilant sound of air leakage, the sound of the exhaust pipe release.

3, temperature anomalies. Tank temperature is too high or even “open” or exhaust pipe sparking and other phenomena indicate that the engine is overheating. Temperature is normal in addition to the state of the cooling system is good, this and the cylinder liner piston group clearance is appropriate, oil supply time is correct, whether the gas distribution phase is out of tune, whether the combustion chamber carbon and other factors.

4, appearance abnormal. Exhaust smoke is white, black or blue; oil, gas, water and electricity leakage; deformation of the lever. Wheel swing; meter readings exceed the normal indication range; difficult to start, engine horsepower, etc.

5, the smell is abnormal. Machinery in the work of burning oil smell, rubber smell, baking paint smell and other strange smell.

6, consumption abnormal. Mechanical fuel consumption, oil consumption is too large.

To repair a faulty machinery, in general, can be used to increase or decrease the shim or adjust the adjusting screw to compensate for the process gap caused by the wear of parts, or the parts to flip, change direction, head, in order to change the assembly position of the parts or the relative position of the working surface relationship, so as to achieve the repair method to eliminate mechanical failure caused by the wear of parts. This method is simple process, the size of the site does not have strict requirements, economic and applicable.

Therefore, many agricultural machinery in the design and manufacture, the structure is considered in the assembly and use of the process of adjustment to compensate for the clearance caused by parts wear. For example, the use of increasing or decreasing shims or adjusting the threads to change the gear side clearance, the clearance between the shaft and the shaft, valve clearance, oil supply time; turn the head, turn the face to use the parts of the unworn surface, etc..

In addition to this, the replacement method can be used. The repair method of replacing damaged parts with new or repaired new parts to eliminate machine failure. For those in the structure can not be adjusted, and no repair value of spare parts, generally have to replace. Such as worn piston rings, burned out electrical components, aging plastic parts, etc.

The final method is the repair and repair size method. Restoration is the use of overlay welding, spraying, plating, bonding, extrusion, machining and other repair processes to restore the original technical performance of the parts to eliminate mechanical failure repair methods. Restoration, on the other hand, is generally used for the repair of large parts of high value. Such as boxes, shells, shafts, etc.

Repair size method, only consider restoring the nature of the fit of the parts, allowing the original size has changed. It is the more valuable or complex parts of the mating parts, according to the wear and tear processing, to eliminate its defects, to meet the technical requirements. The other part is replaced with a fitting of the corresponding size, or its worn mating surface is repaired according to the corresponding size. With the repair size method to repair the mating parts, the size is different from the original standard size, the new size of the part is called repair size. This method of repair small amount, high quality, low cost, widely used. For example, the crankshaft and shaft wear, the crankshaft journal grinding small, replace the bore reduction repair size of the shaft; cylinder wear, the cylinder neck boring large, replace the piston, etc..

Through the above summary of agricultural machinery failure and maintenance of the discussion, you can greatly improve the working life of agricultural machinery at the same time, and can save more manpower and material resources.