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Maintenance and repair of the machine common research injured

Release time:2012.05.17 News source:Star Of Sky Pipe Industry Co.,Ltd.

In the running for some time, the machine relatively sliding parts and components, such as skateboards and guide shaft and sliding bearings, worm and worm wheel, etc. on the surface often scratches or grooves, we call this phenomenon for the study injury. Undermine the accuracy of machine tools for research injury, affecting the life of the machine, if the repair is not timely study injuries to produce particles, but also intensified the research injury, study injuries to produce the grooves easily filth will also increase research injury severe to make the mutual sliding parts to suspend sliding produce killed phenomenon.

Research injury is essentially non wear and tear under normal circumstances, the research hurt the machine, the causes can be divided into two types: one is adhesive wear and tear type of research injury, the other is abrasive wear research injury . On both types of research injury to produce the reason, preventive measures and repair methods, do a brief introduction.

One adhesive wear type research injured

This research hurt the friction pair in relative motion, due to mutual friction, the contact surface of the material transferred from one surface to another surface, causing friction surface scratches and grooves.

Injury. Adhesive wear and tear type of research the mechanism of

Studies have shown: the solid surface conditions, from the microscopic point of view there is uneven defects, even after polishing can not completely eliminate the convex peak and valley. When two friction surface contact, in fact the two convex peak of the friction surface contact with each other. Contact stress, thus resulting in a bomb, plastic deformation, so that the contact area increases, until able to withstand all loads. In this case, the metal contact surface will be firm adhesion point, this phenomenon is usually about the cold welding adhesive. These adhesion points in case of no surface film, when the surface film on the surface of the friction pair, subject only to the role of the normal force, cold welding, adhesive does not produce. Both the role of the tangential force, and the normal force and tangential force, and in relative sliding, the friction surface temperature will rise, film destruction under high temperature and pressure, resulting in contact with metal surfaces it will soften or melt point of contact to produce adhesive - avulsion - adhesive - avulsion of the cycle, so that the contact surface of the material transfer from one surface to another surface, so that a surface (or surface) the formation of scratches and grooves, that is, the formation of adhesive wear and tear type of research injury.

2 adhesive wear the type of research injury classification

According to the friction pair surface to study injury extent of the damage, we can divide the machine adhesive wear research injured four categories:

(1) applied research injury occurs only in the shallow surface of the soft metal, soft metal thin layer of the injury to smear, to the hard metal surface, such as: copper worm pair running for some time, the worm on the surface of smear In the worm on the surface.

(2) abrasions research injuries occur in the soft metal surface below the surface of the shallow part of the failure modes along the direction of movement of small scratches, and sometimes the hard metal surface may scratch. The most common early in the machine running, axle and plain bearings in the wear of the friction in period.

(3) glue (or avulsion) study injury occurred deeper in the friction between the two parts of one or two sides of the matrix, due to the surface of high local temperature, pressure, so that adhesive the Renyi Ji metal bond strength shear strength, when the friction pair to do the relative sliding surface of the 1st monk hit one of the three avulsion damage, there glued research injury. Cam Vice worm pair, the gear pair, the more common; lack of lubrication caused by dry friction, the skateboard with the rails of the machine, but also often produce such research injured.

(4) killed when the friction pair surface transient flash temperature is quite high, adhesion District adhesion strength of the points is quite high, the bond can not be cut off from the substrate, resulting in relative motion to suspend the phenomenon. Killed is the most severe form of research injury. Such as shaft and sliding bearings when the poor lubrication of axle, Metropolitan Research for this injury; the rail short of oil of large machine tools injury caused by a large area of ​​research will also have killed.

(3) adhesive wear the type of research the impact of the injury factors and preventive measures

Impact of such research injured many factors, these factors we can take appropriate measures to prevent its emergence and development.

(1) factors of grease lubrication state adhesive wear type research injury is great, as long as the friction surface always maintain sufficient strength lubricating film, avoid direct contact between the metal surface in the friction surface and the formation of dry friction or semi-friction, you can effectively prevent and control the emergence and development of adhesive wear and tear type of research injuries. To ensure good lubrication of the friction surface is the most important factor in a variety of factors that affect such research injuries. Add oil or viscosity lubricant additives, lubricant film adsorption capacity and film strength can be doubled to improve the ability of anti-research injured.

(2) stress factors, adhesion wear and tear type of research injury, generally increase with increasing pressure. When the pressure load over a certain value of the Friction Material hardness, friction surface oxide film is crushing between the two surfaces, the new face of the protruding points embedded in each other to make such research injured when a sharp increase in the relative movement, and in severe lead to friction surface gluing, and even killed. The use of machine tools, bench, sliding rails to avoid overload operation, workpiece clamping of the planer, milling machine, boring machine on a workbench, it is necessary to a reasonable distribution, but also do not overweight. Machine when in the overhaul rail quenching process and also have a great effect to prevent such research injured.

(3) the temperature factors are also high temperature to produce the injury affect the adhesive wear type research. The heat generated in the course of friction, the friction surface temperature rises to a certain extent, the light, destruction of the lubricating film, the metal surface to direct contact with the formation of dry friction or semi-friction; severe, can make the material in the back fire status and reduce the hardness of materials; more serious cases, the local area can make the friction surface of the material in the molten state. All these will lead to is such a research injury. Selection of materials with high thermal stability or measures to strengthen cooling is a result of adhesive wear and tear type of research injured effective way to prevent the temperature.

(4) sliding velocity of the factors in the case of a certain pressure, sliding speed, the formation of lubricant film decreases, the smaller film thickness, the film often withstand the pressure of not moving parts, while the partially damaged, resulting in direct contact with the two metal easily lead to research injury. Sliding speed to a certain extent, increased the temperature of the friction pair, easy to damage the lubricant film, it tends to lead to research injury, so the choice of sliding speed can be reduced to produce the tendency to adhesive wear and tear type of research injuries.

(5) The surface roughness factors Generally speaking, the smaller the friction surface roughness, the greater the ability of anti-adhesion WEAR research injured, due to lower surface roughness prevents such research injured for the new machine is often used gradually loaded to run the co-operation, the purpose is to reduce the surface roughness to reduce early produce adhesive wear and tear type of research injury. However, the friction surface roughness drop too low, the lubricant between the friction surface can not be stored, easily lead to research to injury, when the tread wear on the rail of machine tool in the maintenance of machine tools, often re-scraping patterns to facilitate oil storage, prevention research injury.

(6) the material factors brittle material than the plastic material of the anti-adhesive wear ability; miscibility of the material composition of the friction pair than miscibility materials are composed of friction, and more prone to wear the type of research injuries; metal non-metallic composition of the friction pair composed of two metal friction pairs to produce a small tendency to hurt such research. Repair machine, we can use non-metallic coating to repair skateboard rail axis and sets of different materials, or the axis of the surface treatment process, reduce produce adhesive wear the type of research injury.

Second, the abrasive wear research injury

Injury of this research is the pollution to enter the two friction between the surface of hard particles in the surface movement significantly cutting action, resulting in friction surface scratches and grooves.

An abrasive wear study injury mechanism of

Hard particles into two friction between the surface by two forces perpendicular to the surface and parallel with the surface force. Hard particles penetrate the surface under the action of the former, while the latter under the action of tangential movement This leads to the surface plow or cutting, leaving scratches and grooves, namely, research injury.

(2) abrasive wear research injuries.

(1) the rail of the bump caused such as machine tools, by the bump of the high stress of the workpiece or tool, and other items, the rail surface pits, and pits around the same time there will be bumps or glitches. If not repaired, when skateboard sliding rail, raised on the rail or burr, is bound to skateboard research injury.

(2) between the rails and skateboard caused by hard particles between two friction surfaces such as chips or sand into the machine, forming a typical abrasive wear research injuries: chips or sand in the vertical pressure, crush rails or skateboard surface, the move put rail or skateboard research injury.

(3) to enter the dirt caused between the friction surfaces such as dirt between the lubricant into the friction surface, although it will not pressure the friction surface, but can change the contact position of the friction surface, due to the support of the dirt, and dirt in the contact position to withstand the The compressive stress increases, after a long run is bound to make the friction surface abrasions or small scratches.

(3) abrasive wear study injury prevention

(1) to prevent the friction surface knock hurt bumps stacked tools, measuring tools, workpieces and other debris such as not on the rail of machine tool, followed by the friction surface bump injury repair in a timely manner, for example, produce the bumps and burrs use Whetstone or scraper repaired flat, to prevent the research hurt the friction surface; pit that appears as patches, to prevent filth pits within the injury to the Institute to stay hidden.

Between (2) fortification and configuration shields to prevent, such as chips, sand and other hard particles into the friction between surfaces, once the hard particles or debris into the friction surface should be immediately ruled out to prevent the research injury or extended.

(3) time and maintenance tools, and timely removal of dirt, grease rails, skateboard hole and dead ends, to prevent dirt from the friction surface between the formation of abrasive wear type of research injury.

Third, the injury repair

Friction pairs of the machine in the event of research injury, you must immediately stop the operation, identify the causes and research the extent of injury, different measures. In general, smear a class of research injury, you can do to repair but to enhance lubrication, to prevent the expansion; abrasions (including dirt, abrasions), to remove dirt and oil stone or scraper scrapes site Shuhei can continue to run: glued killed and research of hard particle-induced injury, must be repaired. Friction pairs of Common Research and injury repair will be some brief:

Sliding bearings and shaft repair

(1) the sliding bearing surface ground injury, the preferred repair program should be scraping the mason method of repair. In general, sliding bearings have left a margin for adjustment and repair, to meet the machine to a repair cycle. If research injury is very serious, and repair the margin can not meet, you need to consider replacing. Two half-watt of sliding bearings research injury, can be thinned gasket re-assembled, scraped bearing bore accuracy, continue to use after the repair.

(2) When the journal with research hurt, can be ground small journal, the replacement of the sliding bearing. Journal grinding should not be too large, such as machine tool spindles, grinding amount should not exceed the journal surface hardening or carburizing, nitriding, cyaniding the thickness of the journal surface hardness after grinding shall not be less than the lower limit of the original design of hardness ; size for the drive shaft, the journal should not be less than the assembly in the assembly direction of the front-end journal or convex.

If the welding repair method to fix the journal, then to consider the welding repair of heating process on the axis of the geometric accuracy, mechanical strength and surface hardness. Journal repair, are generally required by the journal re-equipped with a sliding bearing (or sleeve).

(2) Machine Tool Repair

Minor research for Machine Tool injuries and abrasions, as long as Joe knife or Whetstone repair, you can continue to run. Injury, you need to weld up or filling stick complement to repair glued sex research, even a larger area of ​​research injury, as long as the retention of intact larger portion of the rail surface, can also be used such methods to repair. Until the machine injunctions Vulgar, then fine planing, grinding or sticky board, paneling and other methods to repair.

Machine Tool Research hurt weld up and stick complement, relative to process more complex, especially the repair of a large area of ​​the injury, before the construction of more consideration should be given careful; must first consider the repair process on the rails precision has adversely affected the mechanical properties, such as welding repair and sticky make up most still require heating, the temperature is in the process will lead to rail deformation, will change the mechanical strength and surface hardness of the rail. Second, we must consider the adaptability of the repair process of rail materials such as cast iron materials, rail generally do not use cast iron surfacing due to poor casting weldability, easy to produce cracks, holes and other defects, and the processing is also difficult . High temperature process (refer to gas welding) could easily cause a rail deformation. Third, we must consider the repair layer itself mechanical strength and guide the actual work environment. For example, we have the same tin-bismuth alloy welding repair the 4m planer rails, and T68 boring set rail, the former rail lubrication conditions, has been used for 20 years, still in good condition; the latter due to poor lubrication conditions, the working environment The only off over three years. Short as possible to make the repair layer to meet the life cycle.

In the overhaul of the machine on the rail generally take the following two methods to repair: First, the rail bed to the fine planing, precision milling or grinding will hurt Shuhei, repair to the size of the bed rail and skateboard wear and tear or replace the skateboard, or other compensation on a skateboard rail bonding materials, such as poly PCE soft with wear-resistant coating of epoxy, insert nylon board or metal plate, etc., to compensate for another dimension chain The way is bordered on the rail bed after finishing the pre-heat treatment of steel rails or hardened steel strip.

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