阅读说明：本技术 一种润滑脂相似粘度测定方法及测定用装置 (Method and device for measuring similar viscosity of lubricating grease ) 是由 刘洪鹏 崔骁良 崔长军 于 2021-06-15 设计创作，主要内容包括：本发明公开了一种润滑脂相似粘度测定方法,所述方法步骤如下：根据待测试剪切速率D确定直线驱动机构的下降速度V；仪器安装；检查装置的密封性；恒温持续时间设置；剪切力τ的确定；润滑脂相似粘度的测定；重复步骤S1-S6,测定不同试验条件下的润滑脂相似粘度数值。本发明提供了一种新的润滑脂相似粘度测定方法,提出了一种恒定剪切速率下的相似粘度的测定方法,即采用驱动装置使润滑脂以恒定剪切速率通过毛细管,通过测试剪切过程中的剪切力,完成相似粘度的测定。该装置与方法结构简单,测试效率高,数据可靠。(The invention discloses a method for measuring the similar viscosity of lubricating grease, which comprises the following steps: determining the descending speed V of the linear driving mechanism according to the shear rate D to be tested; installing an instrument; checking the tightness of the device; setting constant temperature duration; determining the shearing force tau; measuring the similar viscosity of the lubricating grease; steps S1-S6 were repeated to determine similar viscosity values for greases under different test conditions. The invention provides a novel method for measuring the similar viscosity of lubricating grease, and provides a method for measuring the similar viscosity under a constant shear rate, namely, a driving device is adopted to enable the lubricating grease to pass through a capillary tube at the constant shear rate, and the measurement of the similar viscosity is completed by testing the shear force in the shearing process. The device and the method have the advantages of simple structure, high testing efficiency and reliable data.)

1. A method for measuring the similar viscosity of lubricating grease is characterized by comprising the following steps:

s1, determining the descending speed V of the linear driving mechanism according to the tested shearing rate D;

s2, installing an instrument, namely, installing a sample filled with lubricating grease into a grease containing cylinder to finish the installation of a capillary tube and a waste grease cylinder;

s3, checking the tightness of the device;

s4, setting constant temperature duration, adjusting the temperature of the constant temperature bath, placing the capillary tube and the fat containing cylinder in the constant temperature bath when the temperature reaches a preset value, and adjusting the constant temperature duration according to the temperature of the constant temperature bath;

s5, determining the shearing force tau, after the constant temperature duration is reached, enabling the linear driving mechanism to operate at a constant downward speed at the descending speed V determined in the step S1, enabling the ejector rod to extrude the lubricating grease sample through the capillary tube, enabling the pressure sensor to record the pressure F borne by the ejector rod in real time, and enabling the integrated controller to obtain the shearing force tau;

s6, measuring the similar viscosity of the lubricating grease, and obtaining the similar viscosity value of the lubricating grease sample by the integrated controller after the pressure F is stable;

s7, repeating the steps S1-S6, and measuring the similar viscosity value of the grease under different test conditions.

2. The method for measuring the similar viscosity of lubricating grease according to claim 1, wherein: the calculation formula of the lowering speed V of the linear drive mechanism in step S1 is:

wherein R is the capillary radius, L is the capillary length, R1 is the ejector pin radius, and D is the grease shear rate to be tested.

3. The method for measuring the similar viscosity of lubricating grease according to claim 1, wherein: the constant temperature duration is not less than 20 minutes in step S4, and when the temperature is lower than-20 ℃, the constant temperature duration is equal to the absolute value of the temperature.

4. The method for measuring the similar viscosity of lubricating grease according to claim 1, wherein: the calculation formula of the shearing force τ in step S5 is:

wherein, P is the internal pressure of the capillary, R is the radius of the capillary, L is the length of the capillary, and F is the pressure applied to the ejector rod.

5. The method for measuring the similar viscosity of lubricating grease according to claim 4, wherein: similar viscosity in step S6The calculation formula is as follows:

where D is the grease shear rate to be tested and τ is the shear force.

6. The apparatus for measuring the similar viscosity of a grease according to any one of claims 1 to 5, wherein: the measuring device comprises a linear driving mechanism, a constant-temperature bath and a grease containing cylinder, wherein a top rod is arranged below the linear driving mechanism and is in transmission connection with the linear driving mechanism, the grease containing cylinder is arranged at the lower end of the top rod, and a capillary tube is arranged at the lower end of the grease containing cylinder.

7. The apparatus for measuring the similar viscosity of a grease according to claim 6, wherein: and a pressure sensor is connected between the ejector rod and the linear driving mechanism through threads.

8. The apparatus for measuring the similar viscosity of a grease according to claim 6, wherein: and the lower end of the capillary tube is provided with a waste grease cylinder.

9. The apparatus for measuring the similar viscosity of a grease according to claim 6, wherein: the linear motion mechanism is provided with an up-down position switch for limiting.

10. The apparatus for measuring the similar viscosity of a grease according to claim 7, wherein: the measuring device further comprises an integrated controller, the signal input end of the integrated controller is in electrical signal connection with the signal output end of the pressure sensor, and the signal output end of the integrated controller is in electrical signal connection with the signal input end of the linear driving mechanism and the signal of the constant-temperature bath tank.

Technical Field

The invention relates to the technical field of lubricating grease similar viscosity measurement, in particular to a lubricating grease similar viscosity measurement method.

Background

The similar viscosity of a grease is a value of the shear force of the grease through a capillary at a certain temperature to the shear rate in Pa · s.

One of the prior art is described in patent application No.: 201911214394X, which is not described herein in detail, can only test similar viscosity values at one temperature point, but cannot test similar viscosities at different shear rates at multiple temperatures, on the premise of one sample loading.

According to the second detection technology, a spring device is used for driving a piston ejector rod, so that the lubricating grease is sheared through a capillary tube, a speed displacement sensor is used for testing the shearing rate of the lubricating grease, a pressure sensor is used for testing the shearing rate of the lubricating grease, and then the similar viscosity of the lubricating grease at different shearing rates is calculated. According to the method, on the premise of one-time sample loading, the driving mechanism drives the spring to compress to the designated position, and then the spring provides pressure for the piston ejector rod, so that after the test process is completed, the test sample is completely consumed, and the next test needs to be loaded again, so that one test can only test the similar viscosity value at one temperature point, and the similar viscosities at different shear rates at multiple temperatures cannot be tested.

Disclosure of Invention

The invention aims to provide a method for measuring the similar viscosity of lubricating grease, which can realize similar viscosity at different shear rates at a plurality of temperatures.

According to the method for measuring the similar viscosity of the lubricating grease, the method comprises the following steps:

s1, determining the descending speed V of the linear driving mechanism according to the tested shearing rate D;

s2, installing an instrument, namely, installing a sample filled with lubricating grease into a grease containing cylinder to finish the installation of a capillary tube and a waste grease cylinder;

s3, checking the tightness of the device;

s4, setting constant temperature duration, adjusting the temperature of the constant temperature bath, placing the capillary tube and the fat containing cylinder in the constant temperature bath when the temperature reaches a preset value, and adjusting the constant temperature duration according to the temperature of the constant temperature bath;

s5, determining the shearing force tau, after the constant temperature duration is reached, enabling the linear driving mechanism to operate at a constant downward speed at the descending speed V determined in the step S1, enabling the ejector rod to extrude the lubricating grease sample through the capillary tube, enabling the pressure sensor to record the pressure F borne by the ejector rod in real time, and enabling the integrated controller to obtain the shearing force tau;

s6, measuring the similar viscosity of the lubricating grease, and obtaining the similar viscosity value of the lubricating grease sample by the integrated controller after the pressure F is stable;

s7, repeating the steps S1-S6, and measuring the similar viscosity value of the grease under different test conditions.

Preferably, the calculation formula of the lowering speed V of the linear driving mechanism in step S1 is:

wherein R is the capillary radius, L is the capillary length, R1 is the ejector pin radius, and D is the grease shear rate to be tested.

Preferably, the constant temperature duration is not less than 20 minutes in step S4, and is equal to the absolute value of the temperature when the temperature is lower than-20 ℃.

Preferably, the calculation formula of the shearing force τ in step S5 is:

wherein, P is the internal pressure of the capillary, R is the radius of the capillary, L is the length of the capillary, and F is the pressure applied to the ejector rod.

Preferably, similar viscosity in step S6The calculation formula is as follows:

where D is the grease shear rate to be tested and τ is the shear force.

Preferably, the measuring device comprises a linear driving mechanism, a constant temperature bath and a grease containing cylinder, wherein a mandril is arranged below the linear driving mechanism, the mandril is in transmission connection with the linear driving mechanism, the grease containing cylinder is arranged at the lower end of the mandril, and a capillary tube is arranged at the lower end of the grease containing cylinder.

Preferably, a pressure sensor is connected between the ejector rod and the linear driving mechanism through threads.

Preferably, the lower end of the capillary tube is provided with a waste grease cylinder.

Preferably, the linear motion mechanism is provided with an up-down position switch for limiting; the lower position switch is a forced test ending switch, when the lower position switch is started, the linear motion mechanism stops running downwards, and the test is forced to stop; the upper position switch is a sample filling completion switch, and when the upper position switch is started, the linear motion mechanism stops moving upwards, so that the sample filling is completed.

Preferably, the measuring device further comprises an integrated controller, the signal input end of the integrated controller is in electrical signal connection with the signal output end of the pressure sensor, and the signal output end of the integrated controller is in electrical signal connection with the signal input end of the linear driving mechanism and the signal input end of the constant-temperature bath tank.

The beneficial effects of the invention are as follows: the device and the method have simple structure, high testing efficiency and reliable data, and can realize the similar viscosity of different shearing rates at a plurality of temperatures.

Drawings

In the drawings:

FIG. 1 is a schematic structural diagram of a device for measuring similar viscosity of lubricating grease according to the present invention;

fig. 2 is a flow chart of a method for measuring the similar viscosity of the lubricating grease provided by the invention.

In the figure: 1-linear driving mechanism, 2-pressure sensor, 3-ejector rod, 4-constant temperature bath, 5-grease containing cylinder, 6-capillary tube and 7-waste grease cylinder.

Detailed Description

Referring to fig. 2, a method for measuring similar viscosity of lubricating grease comprises the following steps:

s1, determining the descending speed V of the linear driving mechanism;

s2, installing an instrument, namely, installing a sample filled with lubricating grease into a grease containing cylinder to finish the installation of a capillary tube and a waste grease cylinder;

s3, checking the tightness of the device;

s4, setting constant temperature duration, adjusting the temperature of the constant temperature bath, placing the capillary tube and the fat containing cylinder in the constant temperature bath when the temperature reaches a preset value, and adjusting the constant temperature duration according to the temperature of the constant temperature bath;

s5, determining the shearing force tau, after the constant temperature duration is reached, enabling the linear driving mechanism to operate at a constant downward speed at the descending speed V determined in the step S1, enabling the ejector rod to extrude the lubricating grease sample through the capillary tube, enabling the pressure sensor to record the pressure F borne by the ejector rod in real time, and enabling the integrated controller to obtain the shearing force tau;

s6, measuring the similar viscosity of the lubricating grease, and obtaining the similar viscosity value of the lubricating grease sample by the integrated controller after the pressure F is stable;

s7, repeating the steps S1-S6, and measuring the similar viscosity value of the grease under different test conditions.

The calculation formula of the lowering speed V of the linear drive mechanism in step S1 is:

wherein R is the capillary radius, L is the capillary length, R1 is the ejector pin radius, and D is the grease shear rate to be tested.

The constant temperature duration is not less than 20 minutes in step S4, and when the temperature is lower than-20 ℃, the constant temperature duration is equal to the absolute value of the temperature.

The calculation formula of the shearing force τ in step S5 is:

wherein, P is the internal pressure of the capillary, R is the radius of the capillary, L is the length of the capillary, and F is the pressure applied to the ejector rod.

Similar viscosity in step S6The calculation formula is as follows:

where D is the grease shear rate to be tested and τ is the shear force.

Referring to fig. 1, the measuring device comprises a linear driving mechanism 1, a constant temperature bath 4 and a grease containing cylinder 5, wherein a mandril 3 is arranged below the linear driving mechanism 1, the mandril 3 is in transmission connection with the linear driving mechanism 1, the grease containing cylinder 5 is arranged at the lower end of the mandril 3, and a capillary tube 6 is arranged at the lower end of the grease containing cylinder 5; a pressure sensor 2 is connected between the ejector rod 3 and the linear driving mechanism 1 through threads; the lower end of the capillary tube 6 is provided with a waste grease cylinder; the linear motion mechanism 1 is provided with an up-down position switch for limiting; the lower position switch is a forced test ending switch, when the lower position switch is started, the linear motion mechanism 1 stops downwards running, and the test is forcibly stopped; the upper position switch is a sample filling completion switch, and when the upper position switch is started, the linear motion mechanism 1 stops moving upwards to complete sample filling; the measuring device also comprises an integrated controller, the signal input end of the integrated controller is in electric signal connection with the signal output end of the pressure sensor 2, and the signal output end of the integrated controller is in electric signal connection with the signal input end of the linear driving mechanism 1 and the signal of the constant temperature bath 4.

The constant temperature bath 4 is used for providing a constant temperature environment for testing the lubricating grease, and the temperature is adjustable;

the grease filling cylinder 5 is used for filling a lubricating grease sample;

capillary 6 is used for grease shearing and is the main element for testing;

the linear driving mechanism 1 is used for driving the piston mandril 3 to move up and down at a constant speed;

the pressure sensor 2 is used for measuring the stress of the ejector rod 3 and further converting the stress into the shearing force borne by the lubricating grease;

the integrated controller is used for controlling the constant temperature bath 4, the linear driving mechanism 1, collecting pressure signals, speed signals, calculation results and the like.

Experiment 1, using a grease (3# universal lithium base, -10 ℃, shear rate 10s-1), the following data were measured using standard test methods:

TABLE 1 comparison of test results under Standard test methods

Test sequence number	1	2	3	4	5	Mean value of
							Test results	637.6	645.5	639.5	652.3	660.2	647.02
Deviation of results	-1.46％	-0.23％	-1.16％	0.82％	2.04％	——

Experiment 2, a grease (3# universal lithium base, -10 ℃, shear rate 10s-1) was used to perform multiple constant shear rate term similar viscosity tests to determine instrument repeatability, with the following data:

TABLE 2 comparison of test results under constant shear Rate test method

Experiment 3, a lubricating grease (0# extreme pressure lithium base grease, shear rate 10s-1) is adopted, and a plurality of times of similar viscosity tests of constant shear rate items are carried out at different temperatures on the premise of not changing samples, and the data are as follows:

and (4) conclusion: the test method under the constant shear rate has the advantages of good test result repeatability, accurate result and good credibility.

The test results of the new test method are slightly larger than those under the standard test method, and the reasons are analyzed: under a standard test method, the lubricating grease is in a motion mode from a high shear rate to a low shear rate and has certain inertia, and under a constant shear rate method, the inertia effect is much smaller, so the test result of the new method is slightly larger, but the use condition is closer to the actual use condition.

On the premise of the same tube sample, the new test method can collect similar viscosity values at different temperatures, and improves the working efficiency.

In summary, the following steps: the invention provides a novel method for measuring the similar viscosity of lubricating grease, and provides a method for measuring the similar viscosity at a constant shear rate, namely, a driving device is adopted to enable the lubricating grease to pass through a capillary tube at the constant shear rate, a spring is not driven to compress through the driving device, pressure is provided for an ejector rod under the action of the spring, and the measurement of the similar viscosity is completed by testing the shear force in the shearing process.