The hottest SP202 grinding fluid and its tribologi

SP202 grinding fluid and its tribological performance evaluation

the linear speed of the grinding wheel in modern grinding has been increased from 25m/s before the startup of the bellows ring stiffness testing machine to 100m/s or higher. The deep and slow grinding has realized the historical transformation of "grinding instead of turning". Under such harsh working conditions, emulsion as lubricating and cooling medium can no longer adapt. The chemical synthetic grinding fluid developed in recent years is more suitable for high-speed grinding, but there is still a lack of research on the relationship between the friction properties of grinding fluid and the effect of grinding process. Discussing this aspect will be beneficial to the development of grinding fluid and even grinding process

in this paper, some grinding fluids at home and abroad are selected. Through bench test and grinding ratio test, the relationship between the parameters of grinding fluid, Pb, PD and the grinding process effect (grinding force, grinding efficiency, grinding ratio, grinding surface roughness, etc.) is tested and investigated. On this basis, SP202 grinding fluid with ideal tribological performance is developed

sp202 synthetic grinding fluid and its characteristics

sp202 synthetic grinding fluid (hereinafter referred to as SP202) uses additives with Mo-B and B-N compounds as the main body, which are considered to be non-toxic or low toxic substances. The surfactant used is easily biodegradable and will not cause residual environmental pollution after discharge. The system is stable and can always maintain a transparent state in the process of use. It can maintain the good penetration and cleaning ability of the newly elected chairman Guo Xinqi to discuss the development of the industry with you, and there is no mildew and deterioration. The ratio of the main components of SP202 is as follows:

surfactant, which belongs to polyether and polyol, and the dosage is 6% based on the mass percentage w% (the same below)

oily agent, belonging to fatty acid esters, the dosage is 4%

the antirust agent belongs to molybdenum boron compound agent, and the dosage is 8%

the corrosion inhibitor of non-ferrous metals is benzotriazole, and the dosage is 0.1%

extreme pressure agent is boron nitrogen compound, and the dosage is 10%

the coupling agent belongs to polyols, and the dosage is 1%

the complexing agent is ethylenediamine tetraacetate, and the dosage is 0.5%

defoamer belongs to dispersant and silicone oil, and the dosage is 0.2%

other components are deionized water

according to the technical indicators specified in gb/t, all items of SP202 grinding fluid meet the requirements of the standard. 5% diluent Pb is 431.2n. Gb/t standard stipulates that the diluent Pb of class II synthetic cutting fluid is ≥ 392n, and Pb of class III and IV is ≥ 686n. The friction coefficient and PD value are not specified. However, we found in testing some imported samples that the Pb value of some commodity grinding fluids is lower than 392n and 686n; But almost all of them have lower PD values and higher PD values according to conservative estimates (see Table 1). Therefore, it is considered that the research on the influence of the values of Pb, Pd on the grinding process effect is undoubtedly of certain significance

Table 1 Pb, PD values of domestic emulsions and several imported samples

Pb, PD values and application effect evaluation of grinding fluid

in order to evaluate the influence of Pb, PD values of grinding fluid on grinding force, grinding efficiency and grinding surface quality, we adjusted the content and proportion of oily agent and extreme pressure agent in grinding fluid, prepared test solutions with different Pb and PD values, and carried out grinding force, maximum blockage value of grinding wheel Investigation of grinding efficiency and machining roughness; The relationship between Pb, PD values and grinding process effect is confirmed through the field inspection of grinding machine parts. Finally, the better formula is compared with the same type samples abroad in the tapping torque test, in order to examine and compare its technical level

special bench test

Figure 1 Schematic diagram of special bench for test

schematic diagram of special bench for test is shown in Figure 1. The test solution is 1# and 2# solution. See Table 2 for their respective parameters. The proportioning concentration of the test solution is 5%. The test parameters are:

grinding force (normal grinding force FN and tangential grinding force ft)

maximum blockage value of grinding wheel (a)

grinding efficiency uses the number of workpieces that can be ground after each dressing of the grinding wheel as the grinding efficiency index (piece/time)

surface roughness Ra (m) after grinding, the surface roughness value measured by the last grinding workpiece before wheel dressing and the surface roughness value measured by the first grinding workpiece after wheel dressing are used as index values

it can be seen from table 3: 1 * the lubricating film formed by the test solution is relatively firm due to the high Pb value. More work will be consumed to tear this film at the same time during grinding; In the extreme pressure state, due to the conditions of low PD value, no chemical reaction or physical deposition to form a low shear film, the grinding force is high and the fluctuation is large. As a result of this fluctuation, the roughness of the grinding surface is also correspondingly high. At the same time, the grinding wheel will also be impacted by a large reaction force, which is easy to form adhesive wear and diffusive wear, making the gap of the grinding wheel blocked and blunt

see Fig. 2 and Fig. 3 for the test grinding force record curve

Figure 2 1 # (5%) grinding force curve

Figure 3 2 # (5%) grinding force curve

test detection of grinding ratio

in grinding processing, the grinding ratio G is usually used to characterize the durability of the grinding wheel, and when the grinding wheel, the processed material and other machining conditions are the same, G can be used as one of the evaluation indicators of the quality of grinding fluid. Here, g=vm/vs. Where: VM is the metal removal amount of 100 pieces per grinding workpiece, mm; Vs is the wear amount of the grinding wheel for each 100 pieces of grinding workpiece, mm

in order to find the best grinding ratio g effect, the dosage and proportion of oily agent and EP agent in the formula were readjusted, and test solutions with different Pb and PD values were obtained, which were actually ground and tested on the grinder. The test conditions are:

the machine tool is m8810 external groove grinder

the specification of grinding wheel is gb180r ×； 6. The material is rubber grinding wheel

peripheral speed of grinding wheel vs=24000r/min

the test piece is a bearing jacket, made of GCr15 steel, with a size of 203/01

rotating speed of test piece: nw=840r/min

use a dial indicator to measure the workpiece size and grinding wheel size before and after grinding, and measure VM and vs. Process and measure 100 pieces each time, repeat it for 3 times, and take the average value of the 3 times. The test results are shown in Figure 4. It can be seen that the grinding ratio g increases with the increase of pd/pb ratio. The relationship is almost linear within the set range of the test

Fig. 4 test curve of the influence of pd/pb ratio on grinding ratio g

high PD value and appropriate Pb value can reduce wheel wear and improve grinding efficiency, and the results are consistent with the results of bench test

tapping torque test

based on the above special bench test and grinding ratio test, in order to compare with foreign similar products (synthetic fluid produced in the United States, which is a variety widely used in China's imported equipment), two types of SP202 synthetic grinding fluids of type A and B were prepared, and the tapping torque was measured on the rapid tapping torque tester developed by Shanghai University

the tapping torque test conditions are: 10mm standard tap, tapping material crmo45 steel, tapping speed 200r/min, test solution concentration 5%. See Table 4 for test solution parameters and tapping test results

Table 4 test solution parameters and tapping torque test results

tapping torque test

in the tapping torque test, the Pb and PD values of test solution a are equivalent to those of imported samples, while the tapping torque test results are only reduced by 8.16%. The difference may be due to different penetration and cleaning capabilities. The pd/pb value of test solution B is higher than that of imported samples, and the tapping torque measurement results are compared, which is reduced by 22.75%. This provides a technical basis for SP202 grinding fluid to replace imported products

from the results of the above three tests, the conclusions are consistent, that is, under certain conditions, the pd/pb value of grinding fluid is one of the important parameters that determine the grinding process effect. It is obviously not perfect to judge the friction characteristics of grinding fluid only by Pb value

production verification of grinding fluid

sp202 grinding fluid has been produced and applied in more than ten units for several years. According to the use test report of each unit, compared with the emulsion used in the past, it can improve the grinding ratio 7 times, the grinding amount increases by 40%-75%, the grinding wheel loss decreases by 26%-75%, and the machined surface roughness is improved; Moreover, because it does not contain oil and harmful ingredients,

odorless and irritant, it is conducive to environmental protection and harmless to the health of operators, which is widely welcomed

conclusion

through special bench test and grinding ratio test, it is confirmed that it is not perfect to use PB value only to express the friction characteristics of grinding fluid; Under certain conditions, pd/pb ratio has a linear relationship with the grinding ratio g of grinding fluid, which should be one of the main parameters to judge the performance of grinding fluid. The SP202 grinding fluid developed based on this shows good technical and economic benefits in production