SU1548705A1 - Method and apparatus for testing materials in abrasive compound - Google Patents

Abstract

The invention relates to the field of testing materials for wear and can be used to assess the performance of parts of agricultural machinery. The purpose of the invention is to improve accuracy by stabilizing the effort of moving the samples relative to the abrasive mass. The device contains a drum 1 with a cavity for an abrasive mass 2, inside which samples 6 are mounted for rotation relative to the shaft. An electric generator 10 is connected to the shaft 8 and a voltmeter 12 is connected to the electrical circuit. When the drum 1 rotates, the abrasive mass 2 condenses and carries the placed there are 6 samples in it, the rotation of which induces an emf. During the test, the EMF values are kept constant. 2 sec. and 1 z. p. f-ly, 4 ill.

Description

The invention relates to the field of testing materials for wear and can be used to assess the performance of parts of agricultural machinery.

The purpose of the invention is to improve the accuracy by stabilizing the effort of moving the samples relative to the abrasive mass and bringing the test conditions to real.

Fig, 1 shows a device for implementing the method; in fig. 2 shows the dependence of sample wear on the test duration; in fig. 3 - dependence of voltage variation from the electric circuit of an electric motor (generator) on the duration of the test; in fig. 4 - the nature of the wear of the samples proposed and known methods.

The device contains a drum 1 with a cavity for abrasive mass 2, a drive motor 3 for rotating the drum 1, rigidly connected to the drive shaft 4 on which the flange 5 of the drum 1 is mounted. samples 6, which is rigidly connected with coi 9 of the electric generator 10 installed coaxially with the driving motor 3. The discharge circuit of the generator 10 is connected to the electrical circuit

11 and a voltmeter 12. i

The method is carried out as follows.

Turn on the engine 3 and begin to rotate the drum 1 with a given angular velocity. The abrasive mass 2 under the action of centrifugal forces compresses and carries samples 6 placed in it, which, together with the holder 7 and the axis 8 rigidly connected with it, begin to rotate at the same speed as the drum 1. At the same time, the wear of the samples 6 This happens because they are motionless relative to abrasive mass 2. After the rotational speed of the drum 1 stabilizes, load resistance 11 is connected to the generator circuit 10 In this case, the rotational speed of the core 9, which is rigidly connected to the axis 8, decreases. Accordingly, the speed of rotation of the 6P specimens mounted on a bracket rigidly connected to the axis 8 will decrease. Due to the difference

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The rotational speeds of the abrasive mass 2 and samples 6 last begin to wear out. After some time, the conditions of interaction between the samples 6 and the abrasive mass 2 begin to change, i.e. the conditions of wear are changed, which is a consequence of the grinding of abrasive grains; changes in the shape and size of samples, temperature and humidity in the zone of friction, and other factors. Ultimately, the torque changes, which is proportional to the friction force between the abrasive mass 2 and the working surface of the samples 6. As the friction force increases, the torque increases and, conversely, as it decreases, the torque decreases. The change in wear conditions is recorded by a 10 voltmeter 12 connected to the generator circuit, the voltage of which increases or decreases depending on the number of revolutions of the core 9,

Thus, in order to maintain the specified wear conditions, i.e. the torque on the core 9 of the generator 10 (or the friction force between the samples 6 and the abrasive mass 2), it is necessary, by crawling with the readings of the voltmeter 12, to restore the original speed number of the core 9. To do this, change the speed of rotation of the drive motor shaft 3, t. e. drum 1 with an abrasive mass of 2,

Example. For testing, specimens were made in a surmet wedge with a hole for mounting on a bracket; one side of which was reinforced with Sormaite-1 alloy by manual welding with a carbon electrode and smoothed by grinding to a thickness of 0.5 mm. Sample material — St3 (this steel grade, as the least wear-resistant, 5 is selected to accelerate the tests and obtain the most pronounced self-sharpening effect of the wedge. The wedge angle at the beginning of the tests for all samples was 60 °

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parts of samples in cross section 15 x 20 mm. Before testing, the samples were weighed on an ADV-200 M scale. In addition, the initial profile of the wedge was fixed on graph paper (for comparison with the profile of a worn sample). Two samples were tested simultaneously.

As a drum for the abrasive mass, a tire from a motor bike was used. The driving motor is a direct current electric motor fed through a rectifier and a LATR, and the generator 10 is a generator from a passenger car (with a nominal voltage of 12V). As resistance 11, a wire resistor is used in the generator circuit 10. The voltage was measured with a voltmeter with a division value of 0.1 V. Homogeneous fine river sand was used as the abrasive mass 2. For each trial (experiment), a fresh portion of sand weighing 4 kg was poured into the drum 1.

The unwinding of the drum 1 with an abrasive mass of 2 (sand) was made gradually (using LATR) and brought to 500 rpm. In all experiments, this speed of rotation of the drum 1 was accepted (when tested by a known method, this speed was constant until the end of the experiment). After stabilization of the revolutions of the core 9, carried by the abrasive mass 2 through samples 6 (in 3-5 s), a load was applied to it. The magnitude of the load was chosen conditionally, so that the voltage on the voltmeter 12 was 5 V. Thus, the beginning of the test took the moment when the shaft of the driving motor 3 rotates at 500 rpm and the voltage in the generator circuit is 5 V.

According to the test results, the graphs of the dependence of wear on the operation time (Fig. 2), as well as changes in voltage over time (Fig. 3) were compiled when tested using proposed and known methods.

As can be seen from FIG. 2, the wear schedules proposed and by known methods are consumed. This was achieved by the fact that the test modes of the proposed method were continuously adjusted, i.e. the voltage value was constantly maintained at 5 V (Fig. 3), and when worn in a known manner, the test modes were set first and were not corrected until the end of the experiment. The same increase in wear in the first 3-4 hours is explained by the intensity of blunting (rounding) of the cutting edge of the wedge (blade). Then the voltage in the generator circuit increases, i.e. There is an increase in the number of revolutions of the core, which is a consequence of an increase in the strength

friction between the samples and the abrasive mass (Fig. 3, Izv) .. Further wear without changing the modes leads to a drop in voltage, since in this case the sample sizes decrease and the grinding of sand particles (abrasive mass) begins, which leads to a decrease in the friction force between samples and abrasive mass.

The wear tests of the proposed method showed the possibility of creating the most favorable conditions for self-sharpening under laboratory conditions. Stabilization of the movement of the samples relative to the abrasive mass reduces the dull edge of the sample during wear and brings the test conditions closer to actual wear conditions. FIG. Figure 4 shows the changes in the shape of the edge of the sample at various stages of testing.

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Claims (3)

1. Method of testing materials in the abrasive mass, which consists in placing the samples on the shaft, rotate the samples, compress the abrasive mass by rotating it and moving the samples relative to the abrasive mass, adjust the speed of moving the samples relative to the abrasive mass regardless of the speed of the abrasive mass, and determine the wear of the samples, characterized in that stabilizing the movement of the samples relative to the abrasive mass, connect the shaft of the samples with the shaft of the electric generator, the samples are rotated by compaction of the rotating ab azivnoy mass, the brake torque is set at the generator shaft register corresponding electrical voltage generated by the generator, and this voltage is maintained during the test constant. 2. An apparatus for testing materials in an abrasive mass, comprising a body, a drum with an abrasive mass cavity, installed in rotatably, the drum rotates, the sample holders placed in the drum cavity, and the shaft mounted rotatably relative to the housing and rigidly connected to the holders, characterized in that, in order to improve the accuracy by stabilizing the movement force of the samples relative to abrasive mass, it is equipped with an electric generator, “which is connected to the shaft, a rheostat, included in the electric a generator circuit for regulating the current in the circuit and a device for registering the electrical voltage generated by the generator included in the electrical circuit. 3. A device according to claim 2, characterized in that the walls of the cavity of the drum are made elastic. U 75 cpuz.Z W t.uac. Sample wear The proposed method Fest way Start Sormeigl (NCS55) I measurement I measurement F measurement Yu 75 Fig.Z ZQ t.vac. h w§ tin U $ II §1 th-ss §1  xj AND S Qi l Sv Stes . ttfl