A rapid method for measuring the lubricating properties of cutting lubricants
October 24, 2022
Nowadays, the application scope of lubricants is extremely broad, and they are used in many fields. As a large manufacturing and production country, China will involve many cutting links of mechanical facilities, so the amount of application of cutting lubricants in China is huge. Therefore, it is necessary to study the lubricating properties of cutting lubricants. Nowadays, there is no effective, simple and fast simulation method to determine the performance of cutting lubricants, except for experiments in actual work.
In China, the four ball machine PB is mainly used as the evaluation index of cutting lubrication, but the materials of the four ball machine and the cutting friction pair are very different, so the four ball machine cannot accurately reflect the lubrication in the cutting process. Tapping torque tester is a measuring device specially used to study the cutting process. The most typical representative device is the American Falex II tapping torque tester. However, the price of this kind of tester is extremely high, and the cost used in the measurement is also very large, so the use is limited.
Therefore, the market developed a simple tapping torque testing device based on the theory of torque testing system and the current four ball machine. Tapping experiments were carried out on different materials with this device, and the test results were basically the same as the actual application results. At the same time, the comparison between common lubricant rapeseed oil and castor oil also showed that this device has good practicability and reliability. At the same time, it also plays an effective role in the selection of lubricants in the laboratory and the inspection of lubricant quality in the factory.
Application principle of test system In this method, the ball jacking fixture of the four ball machine is replaced by a tapping fixture, and the piston of the four ball machine is replaced by a nut sample fixture, which is sheathed in an oil lubricated piston sleeve to reduce friction. The basic principle of this test is to touch the handle of the nut sample fixture with the torque sensor, so that the four ball machine can be adjusted within the speed range of 100-1800 rpm, and then the signal of the sensor is continuously amplified. Finally, a recorder is used to draw the torque time curve. The highest end of the curve represents the maximum torque Tmax during tapping. Among them, Tmax represents the lubrication performance. The smaller Tmax is, the better the lubrication performance is. Reliability Analysis of Testing System In order to verify the reliability of the simple tapping torque device developed by us and the accuracy of this test method on the research of cutting lubricant performance, we took the vegetable oil and castor oil, which are relatively basic in the current cutting process, as the test samples, and compared their performance with that of ordinary mineral oil cutting lubricants, and analyzed their reliability. According to the results of the experiment, it is found that the cutting performance of ordinary mineral oil lubricated stainless steel that is difficult to machine is much worse than that of rapeseed oil and castor oil lubricated stainless steel. The experimental result Tmax of this device is the same as the result summarized by actual experience. It can be seen that the results of this experiment are very true, effective and reliable. Four ball machine test (PB value and wear diameter) can not show that rapeseed oil and castor oil have good cutting lubrication effect (excluding lubricating oil containing extreme pressure agent). Cost of equipment and its operation The cost and expense of the simple tapping torque testing device experiment is much lower than that of the American Falex II tapping torque measuring device, and the device is also very simple, simple and reliable. At the same time, the measurement results are very fast. Each test operation takes about two minutes to get the results. A simple, convenient, fast and easy to operate tapping torque testing device has been developed with reference to the American Falex II tapping torque measuring instrument. The measuring cost and cost of this device are very low, and each experiment takes about 2 minutes to draw a conclusion, so it is very fast. Tapping torque tests were carried out on nuts to be tapped of different materials. The nuts to be tapped mainly include 45 # steel, copper, aluminum and stainless steel. The error is obtained in the experiment, and then the error is processed and analyzed. It is found that the error of the measurement result is within 3.0%. Compared with the PB value of the four ball machine and the wear diameter method, the simple measurement method for evaluating cutting lubricant this time is closer to the fact, and conforms to the empirical results accumulated in practice. Therefore, the practicability, accuracy and reliability of this device are fully verified. At the same time, the advantages of vegetable lubricant and its good lubrication effect on cutting equipment are also found, which not only protects the environment, but also increases the exploration scope of lubricant.
