Abrasive tool abrasives for grinding plates

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Grinding a layer of trace metal off the surface of the workpiece with abrasive tools and abrasives to achieve precise dimensions, accurate geometry, and extremely fine surface roughness is a precision machining method called grinding.

The surface hardness of the grinding tool should be slightly lower than that of the part to be grinded, so that the tiny abrasive particles in the abrasive can be easily embedded on the surface of the grinding tool during grinding to carry out a slight amount of cutting on the surface of the workpiece. Conversely, abrasive grains will be embedded in the surface of the part, causing the grinding tool to be cut during grinding. But the grinding tool should not be too soft.

Otherwise, the abrasive grains will be completely embedded in the grinding tool and the abrasive effect will be lost. The microstructure of the grinding tool material should be fine and uniform, with good wear resistance, so as to ensure that the research parts obtain high size, shape accuracy and fine surface roughness. The materials commonly used in grinding tools are gray cast iron, ductile iron, mild steel, copper, babbitt and lead, the latter two are mainly used for polishing precision bearings made of copper alloys or grinding soft parts.

Abrasives are made by blending abrasives and slurries.

The particle size of the abrasive is divided into 41 numbers according to the particle size, of which there are 27 kinds of grinding powder from 4, the larger the particle size, the finer the abrasive; There are 14 kinds of micronized powder from W63, and the larger the number, the coarser the abrasive. When grinding, it should be selected according to the accuracy and surface roughness required by the workpiece.

The slurry plays a role in blending abrasives, cooling and lubrication in processing, and is commonly used in kerosene, gasoline, N15 or N32 engine oil, industrial glycerin, turbine oil and cooked lard. In addition, add an appropriate amount of paraffin, beeswax and other fillers and oleic acid, fatty acids, stearic acid, etc. with large viscosity and strong oxidation effect to the slurry as needed, and the effect is better.

1) The grinding should be in a free state when calibrating, so as not to produce elastic deformation of the grinding plate due to the action of external force, so the correction of the grinding plate is generally only carried out under the action of its own weight, and no additional pressure is added, when the grinding plate needs to be fixed on the machine tool base, workbench and grinding table with screws, the screws need to be symmetrically distributed, and should rotate evenly and not too tightly.

Grinding plate correction.

2) The bottom surface of the grinding plate and the base of the machine tool, the workbench and the grinding table surface need to have good planarity to ensure good contact between them, for which these surfaces need to be carefully grinded, scraped or grinded.

3) When calibrating, the correct relative motion between the grinding plates is the guarantee that the grinding plates obtain the ideal planarity, and the so-called correct grinding motion refers to the movement that ensures that the points of each point of the two grinding plates are equal in the moving distance, that is, the so-called plane parallel motion. In general, this is difficult to do, but try to get as close as possible to this movement.

Grinding plates. 4) When the grinding plate is corrected, the grinding plate placed on the top is easy to obtain a concave shape, and the grinding plate placed below is easy to obtain a convex shape, so when the grinding plate is corrected, each grinding plate should be placed alternately above and below as much as possible, and the opportunity should be equal as much as possible.

5) When the grinding plate is corrected, the plate surface is sold to a large amount and generates a lot of heat, so the thermal deformation of the grinding plate is large. Therefore, the grinding plate should be calibrated with equal time and controlled within 10 15min, and the time interval between two grinding should be longer to fully isotherm.

Practice has proved that only by paying full attention to the above points can it be possible to achieve the ideal flatness of the grinding plate.

There are two methods of grinding plate grinding, there are three plates and two plates, both have their own advantages and disadvantages, mainly depending on the method that the operator is used to, both methods can process the grinding plate to a better flatness and roughness.

The pressure grinding plate used for the repair of the gauge block is usually made by grinding by the three-plate method. The three-plate method uses three grinding plates of the same specification to conduct mutual research in an inherent order. The sequence is that two upper plates and one lower plate are respectively studied with each other to obtain two convex plates and one concave plate.

Then use two convex core plates to study each other, and the two plates are flattened. Then use the concave plate and the flat plate to study each other, then the concave plate becomes flat.

The scraping plate is a flat reference instrument used for workpiece inspection or marking.

Scraping plates are widely used. It is used in mechanical engineering. Chemical industry. Hardware. Aerospace. Petroleum. Automobile manufacturing. Instrument manufacturing and other industries.

Scraping cast iron plates are flat datum instruments used for workpiece inspection or marking. Scraping plates are widely used. It is used in mechanical engineering.

Chemical industry. Hardware. Aerospace.

Petroleum. Automobile manufacturing. Instrument manufacturing and other industries.

Scraping plate: It is mainly used as a benchmark for inspecting the error of the workpiece. The scraping plate plays a vital role in the mechanical manufacturing process, and it is the most basic reference tool for the pre-factory inspection of each workpiece.

Scraping plate (scraping platform) purpose: suitable for all kinds of inspection work. Fiducial planes for precise measurements.

It is used for machine tool inspection and measurement datum to check the dimensional accuracy or shape and position deviation of parts. And do precision scribing. It is also an indispensable basic tool in machine building.

The grinding plate is a cast iron plate after scraping, and then grinding it with grinding sand (from coarse to fine) for many times, and finally smoothing the pits on the surface of the grinding plate, and then making it after fine polishing.

Grinding plate (grinding platform) is a kind of cast iron plate derived from the finishing of the machined surface by using abrasive particles coated or embedded in the grinding plate in order to ensure the accuracy and surface finish of the workpiece, and the relative movement of the grinding plate and the workpiece under a certain pressure.

Finishing (e.g., machining) on the machined surface is carried out by the relative motion of the grinding tool and the workpiece under a certain pressure by using abrasive particles coated or pressed on the grinding tool. Grinding can be used to process a variety of metallic and non-metallic materials, the surface shapes are flat, inner and outer cylindrical and conical, convex and concave spherical surfaces, threads, tooth surfaces and other profiles. The machining accuracy can reach IT5 01, and the surface roughness can reach microns.

Grinding is a very complex process, so there is no unified theory that can explain all the grinding phenomena, after long-term observation and research, at present, there are three main types: Mechanical grinding theory: it is believed that the cutting of cerium oxide particles is similar to the cutting of CG and diamond particles.

Chemical action theory: The protruding peaks of the convex and concave layers of the glass are removed by hydrolysis. Thermal Surface Flow Theory:

The frictional heat causes a hot melt flow, resulting in a smooth surface. The above three theories have a certain degree of correctness to varying degrees, and based on the comprehensive effect of the three, a fourth view is now put forward, that is, grinding is an intricate process of mechanical, chemical and physical effects. Principle of abrasive chip formation:

The abrasive grains are randomly distributed in the spacing and height of the abrasive grains on the grinding tool, and the abrasive grains are a polyhedron, each of which can be regarded as a cutting edge, with a tip angle of roughly 90° 120° and a tip of an arc with a radius of a few microns to tens of microns. The surface of the abrasive grain of the finely trimmed abrasive tool will form some tiny cutting edges, which are called micro edges. The abrasive grains have a large negative rake angle when grinding, with an average value of around -60°.

The cutting process of abrasive grains can be divided into 3 stages.

There are generally two grinding methods of flat plates: one is the three-plate mutual research method, the result of this method of sand pressing is that the flatness of the three plates is very good, the sand pressing effect of the three plates is basically the same, and the three plates can be used, the sand is not often pressed, but the repair technology requirements are higher, the so-called three-plate mutual research method refers to the mutual research between the three plates in turn, and each plate can only be used as a plate twice, and the actual total grinding is 6 times.

Another method is the mutual research method of two plates, also known as the mother-in-law pressure method. This method is to use only two plates to study each other, and the result of sand pressing with this method is that the flatness of the two plates is basically consistent, the flatness of the upper plate is concave, the flatness of the lower plate is convex, and the sand pressing effect of the lower plate is better than that of the upper plate. Because the upper plate is concave in the middle, it is not easy to repair the measuring block, and generally does not use the upper plate, only the lower plate.

The disadvantage is that the protrusion of the lower plate is not easy to control, and only a flat plate can be used. Each sand pressing time requires 3 to 4 times to complete. Each pass takes about 6 minutes.

The former is usually preferred over the two methods.