JP2012137389A - Bearing durability assessing method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assess the remaining service life of a grease-lubricated bearing more quickly than by a conventional method.SOLUTION: A bearing durability assessing method for assessing the remaining service life of a grease-lubricated bearing comprises: a measuring step of acquiring with respect to a test period estimated in advance as a shorter length of time than the remaining service life of the bearing the relationship between the period of rotation and the remaining quantity of base oil contained in the grease as a plurality of measurements; a data processing step of figuring out a regression line representing the relationship between the period of rotation and the remaining quantity of base oil contained in the grease based on the plurality of measurements; and a life determining step of determining the period of rotation at the intersection of an oily content limit line, representing the marginal remaining quantity of base oil, and the regression line as the remaining service life of the bearing.

Description

  The present invention relates to a bearing life evaluation method and apparatus.

  As is well known, grease is a type of lubricant made into a paste by adding a thickener to a base oil. The base oil is, for example, natural mineral oil or artificially synthesized synthetic oil, and is responsible for lubrication performance. On the other hand, the thickener is, for example, a metal salt of a fatty acid (metal soap) or a composite soap in which a fatty acid and an organic acid are combined. .

  Some rolling bearings use such grease as a lubricant, and the life of grease lubricated rolling bearings is governed by the remaining amount of base oil that gradually decreases with use (rotation). It has been known. In other words, it is known that grease lubricated type rolling bearings have an abnormal phenomenon such as seizure when the base oil is reduced from the initial state to a certain amount, resulting in a life span.

  The life evaluation of conventional grease lubrication type rolling bearings is performed by rotating the rolling bearings with a rotary tester and measuring the remaining amount of base oil sequentially each time a specified number of revolutions elapses. The life of the rolling bearing is defined as the point of time (grease life) is reached. For example, the following non-patent literature discloses a life evaluation method for such a grease lubricated type rolling bearing.

S. Komatsuzaki, T. Uematsu anda Y. Kobayashi; Change of Grease Characteristics to the End of Lubricaring Greases, NLGI Sporkesman, 63, 12, (2000) 22.

  By the way, the lifetime evaluation method requires a great amount of time. That is, although depending on the type (type) of the rolling bearing, in order to rotate the rolling bearing to the grease life with the rotation tester, a test time on the order of several thousand to 10,000 hours is required. In some cases, it may be necessary to conduct a life test that requires such a long time as many times as necessary. In such a case, the test time of several thousand to 10,000 hours is multiplied by the number of tests. Since the time becomes the test time, the above-mentioned life evaluation method requires an extremely long time.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to evaluate the life of a grease lubrication type bearing in a shorter time than before.

  In order to achieve the above object, the present invention provides a bearing life evaluation method for evaluating the life of a grease lubricated type bearing as a first solution for the bearing life evaluation method, wherein the period is shorter than the life of the bearing. As a pre-estimated test time, a measurement process for acquiring the relationship between the rotation time and the remaining amount of the base oil contained in the grease as a plurality of measurement values, and the rotation time and the remaining base oil based on the plurality of measurement values A data processing step for obtaining a regression line indicating the relationship with the amount, and a life determination step for determining the bearing life as the rotation time at the intersection of the oil limit line indicating the limit remaining amount of the base oil and the regression line Is adopted.

  As a second solution means related to the bearing life evaluation method, in the first solution means, in the measurement step, a measurement value is obtained by rotating the bearing under a rotation condition corresponding to the actual use state of the bearing. adopt.

  As a third solution means related to the bearing life evaluation method, in the first or second solution means, in the measurement step, measurement values are obtained for a plurality of bearings of the same form, and in the data processing step, for each rotation time, A means is adopted in which an average value of the measured values of each bearing is obtained, and a regression line is obtained based on the respective average values.

  According to the present invention, as a first means for solving the bearing life evaluation apparatus, a bearing life evaluation apparatus for evaluating the life of a grease lubrication type bearing, the rotation tester for rotating the bearing under a specific rotation condition. And an oil content measuring device that measures the remaining amount of base oil contained in grease at multiple rotation times for a test time that is estimated as a period shorter than the bearing life, and a plurality of measurements input from the oil content measuring device. Based on the value, a regression line indicating the relationship between the rotation time and the residual amount of base oil is obtained, the intersection of the oil limit line and the regression line indicating the limit residual amount of base oil is obtained, and the rotation time at the intersection is determined by the bearing A means is provided that includes an arithmetic unit that has a lifetime.

  As a second solving means related to the bearing life evaluation apparatus, in the first solving means, a means is adopted in which the rotation tester rotates the bearing under a rotation condition corresponding to the actual use state of the bearing.

  As a third solution means related to the bearing life evaluation apparatus, in the first or second solution means described above, the arithmetic unit calculates the average value of the measured values input from the oil content measuring device for a plurality of bearings of the same form for each rotation time. A method is adopted in which a value is obtained and a regression line is obtained based on each average value.

  According to the present invention, the rotation time and the remaining amount of base oil based on a plurality of measured values indicating the relationship with the remaining amount of base oil obtained within a specific time estimated in advance as a period shorter than the bearing life. The rotation time at the intersection of the oil limit line indicating the base oil limit remaining amount and the regression line is used as the bearing life, that is, up to the base oil limit remaining amount as in the past. Since the rotation test is not performed, the life of the grease lubrication type bearing can be evaluated in a shorter time than before.

It is a block diagram which shows the function structure of the bearing life evaluation apparatus A which concerns on one Embodiment of this invention. It is a flowchart which shows operation | movement of the bearing life evaluation apparatus A which concerns on one Embodiment of this invention. It is a characteristic view which shows the bearing life evaluation method which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the bearing life evaluation apparatus A according to the present embodiment is composed of a rotation testing machine 1, an oil content measuring device 2, and a control arithmetic device 3, and a grease lubrication type bearing is an evaluation object. Such bearings include rolling bearings (ball bearings or roller bearings) using balls and rollers as rolling elements. That is, the object of evaluation of this bearing life evaluation apparatus A is that a rolling element is interposed between the outer ring and the inner ring, and grease as a lubricant is interposed between the outer ring and the rolling element and between the inner ring and the rolling element. Is filled. Such rolling bearings are roughly classified into radial bearings and thrust bearings according to the direction (type) of the load received, but this bearing life evaluation apparatus A has both radial bearings and thrust bearings. Target for evaluation.

  The rotation test machine 1 is a device that rotates a bearing to be evaluated under a specific rotation condition under the control of the control arithmetic device 3. The bearing is used under various rotation conditions depending on the application, for example, rotation speed, use temperature and use load. However, the rotation testing machine 1 performs the bearing under the actual use condition (rotation condition) of the bearing to be evaluated. Rotate. For example, when a bearing used in a use environment in which the rotation speed, the use temperature, and / or the use load fluctuate periodically is to be evaluated, the rotation tester 1 uses the rotation control signal input from the control arithmetic unit 3. Based on this, the bearing is rotated under a rotation condition that simulates the periodic fluctuation.

  Further, the test time K for rotating the bearing by the rotation tester 1 is a time estimated in advance as a period that is significantly shorter than the expected life of the bearing. That is, the rotation testing machine 1 rotates the bearing based on the rotation control signal input from the control arithmetic device 3 with the test time K as the longest rotation time of the bearing, and from the start of rotation within the test time K. The rotation is stopped every time a certain time elapses, that is, the bearing is intermittently rotated every certain time. This fixed time, that is, the time from the start of rotation to the stop of rotation (unit rotation time) is defined by the rotation control signal input from the control arithmetic device 3.

  The oil content measuring device 2 is a measuring device that measures the residual amount of base oil contained in the grease every time the rotation of the bearing by the rotation testing machine 1 stops under the control of the control arithmetic device 3. That is, the oil content measuring device 2 measures the residual amount of base oil in the bearing based on the measurement start signal input from the control arithmetic device 3 when the rotation of the bearing by the rotation testing machine 1 is completely stopped, and uses it as a measured value. Output to the control arithmetic unit 3. Therefore, the number of measurement values acquired by the oil content measuring device 2 at the test time K is defined by the number of times the bearing stops rotating at the test time K.

  The control arithmetic device 3 controls the rotation testing machine 1 and the oil content measuring device 2 based on a predetermined life evaluation program, and based on a plurality of measured values (remaining amount of base oil) input from the oil content measuring device 2. It is a kind of computer that determines the life of a bearing. That is, the control arithmetic unit 3 acquires each measured value (residual amount of base oil) from the oil content measuring device 2 while controlling the rotation testing machine 1 and the oil content measuring device 2 based on the life evaluation program. The life of the bearing is specified based on (residual amount of base oil).

  More specifically, based on the life evaluation program, the control arithmetic device 3 sets the measurement value (the remaining amount of base oil) sequentially input from the oil content measuring instrument 2 as a set with the rotation time of the bearing, and the remaining base oil. Time series data consisting of quantity and rotation time is sequentially stored as measurement data, and the life of the bearing is obtained by subjecting the measurement data to statistical data processing. Further, as the data processing, the control arithmetic device 3 obtains a life prediction line Y indicating the relationship between the rotation time and the remaining amount of base oil from the measurement data, and the oil content limit line G indicating the limit remaining amount of the base oil and the life. The intersection with the prediction line Y is obtained, and the rotation time at the intersection is defined as the bearing life T. The above-mentioned limit remaining amount is a value estimated as the remaining amount of the base oil that functions normally without causing abnormalities such as seizure of the bearing.

  Next, the operation of the bearing life evaluation apparatus A configured as described above, that is, a bearing life evaluation method using the bearing life evaluation apparatus A will be described in detail with reference to the flowchart of FIG. This flowchart shows the processing procedure of the control arithmetic device 3 based on the life evaluation program, that is, the process of the bearing life evaluation method.

  When starting the process based on the life evaluation program, the control arithmetic device 3 first performs an initial setting process (step S1). This initial setting process is a process for internally setting the above-described bearing rotation conditions, unit rotation time, initial measurement data, the upper limit value (specified number of times) of measurement in the oil content meter 2, the value of the internal counter, the oil content limit value, and the like. It is. In this embodiment, as an example, the rotation speed, the use temperature, and the use load are the rotation conditions, the remaining amount of base oil = 100 (% by weight) and the rotation time = 0 hours (h) are the initial measurement data X0, “5 times” is initially set as the specified number of times, “1” is initially set as the value of the internal counter, and “60 wt%” is initially set as the limit remaining amount.

  Here, the time obtained by multiplying the unit rotation time by the specified number of times is the effective test time K of the bearing in the rotation tester 1, and this test time K is significantly shorter than the expected life of the bearing as described above. It is the longest rotation time of the bearing estimated in advance as time. In other words, the unit rotation time and the specified number of times are set so that the test time K is shorter than the assumed life of the bearing. In this embodiment, as an example, the estimated life of the bearing is estimated to be 2000 hours or more, and the test time K is set to 1000 hours based on this estimate, so that the unit rotation time is 200 hours and the specified number of times is 5 times. Yes.

  Then, the control arithmetic device 3 rotates the bearing in accordance with the rotation condition by outputting the rotation control signal generated based on the rotation condition to the rotation testing machine 1 (step S2). Then, the control arithmetic unit 3 monitors whether or not the unit rotation time has elapsed from the start of rotation of the bearing by the rotation tester 1, and when the unit rotation time has elapsed (step S3), the rotation control signal is sent to the rotation tester 1. Is output to temporarily stop the rotation of the bearing (step S4).

  Then, when the bearing is completely stopped in this way, the control arithmetic device 3 outputs a measurement start signal to the oil content measuring device 2 to measure the remaining amount of the base oil contained in the grease filled in the bearing ( Step S5). Then, the control arithmetic device 3 obtains a measurement value (remaining amount of base oil) as a measurement result from the oil content measuring device 2, and internally stores the measurement value and the rotation time as first (initial) measurement data X1. Store (step S6). That is, at this point, since the unit rotation time has elapsed since the start of the evaluation of the bearing, the control arithmetic device 3 stores the measurement value and the rotation time as the first measurement data, and an internal counter indicating the number of times of measurement. The initial value is incremented from “1” to “2”.

  Then, the control arithmetic device 3 determines whether or not the number of measurements has reached the specified number (5 times) (step S7). At this point, since the first measurement data X1 has been acquired, the determination result is “No”. Therefore, the control arithmetic device 3 subsequently executes the process of step S2 to rotate the bearing again. Further, the second (second) measurement data X2 is stored in the inside by executing the processing of steps S3 to S6. That is, the control arithmetic device 3 stores the first to fifth measurement data X1 to X5 therein by repeatedly executing the processes of steps S2 to S7.

  Then, the control arithmetic unit 3 obtains the first to fifth measurement data X1 to X5 obtained based on the processing in steps S2 to S7 and the initial measurement data X0 (first) set in the processing in step S1. A regression line indicating the relationship between the rotation time of the bearing and the remaining amount of base oil is obtained by performing statistical data processing (for example, processing based on the least square method) on (measurement data of 0) (step S8). That is, the control calculation device 3 obtains the equation of the fitting regression line (regression line or regression curve) as the life prediction line Y in the 0th to 5th measurement data X0 to X5.

  FIG. 3 is a characteristic diagram showing the life prediction line S most fitting to the 0th to 5th measurement data X0 to X5 as a regression curve. The control arithmetic unit 3 performs the life determination process based on such a life prediction line S and the oil limit line G given by the limit remaining amount (60 wt%) initially set in the process of step S1 (step S9). ). That is, the control arithmetic unit 3 obtains the coordinates of the intersection point P by solving the simultaneous equations composed of the equation of the life prediction line S and the equation of the oil limit line G, and the coordinate value of the horizontal axis among the coordinates of the intersection point P A certain rotation time is specified as the bearing life T.

  According to this embodiment, as can be easily seen from FIG. 3, the 0th to 5th measurement data X0 to X5 are acquired at the test time K estimated as a period significantly shorter than the bearing life T. Since the life prediction line S is obtained based on the 0th to 5th measurement data X0 to X5 to estimate the bearing life T, that is, the limit remaining amount of the base oil (60% by weight) as in the conventional case. Since the bearing life T can be specified without taking the test time as the test time, the life of the grease lubrication type bearing can be evaluated in a shorter time than before.

  Here, the life prediction line S is estimated based on the 0th to 5th measurement data X0 to X5. Therefore, the estimation accuracy of the life prediction line S dominates the estimation accuracy of the life T of the bearing. In order to improve the estimation accuracy of the lifetime T, it is effective to increase the number of measurement data (measurement values). Further, the estimation accuracy of the life T can be improved by bringing the test time K closer to the expected life of the bearing (2000 hours or more), that is, by increasing the test time K. However, increasing the test time K is a measure that goes against the object of the present invention. That is, since the test time K and the estimation accuracy of the lifetime T are in a trade-off relationship, the test time K is appropriately set according to the required level of the estimation accuracy of the lifetime T.

  Further, according to the present embodiment, the control arithmetic device 3 automatically acquires each measurement value (residual amount of base oil) from the oil content measuring device 2 while automatically controlling the rotation testing machine 1 and the oil content measuring device 2. Since the life prediction line S is obtained, the workability of life evaluation is very good.

In addition, this invention is not limited to the said embodiment, For example, the following modifications can be considered.
(1) In the above-described embodiment, the control arithmetic device 3 automatically acquires each measurement value (residual amount of base oil) from the oil content meter 2 while automatically controlling the rotation test machine 1 and the oil content meter 2. However, the present invention is not limited to this. The rotation testing machine 1 and the oil content measuring device 2 operate individually to acquire each measured value (residual amount of base oil), and manually input each measured value (residual amount of base oil) to the control arithmetic device 3. Anyway.

(2) In the above-described embodiment, one rotation tester 1 is provided, but the present invention is not limited to this. For example, by providing a plurality of rotation test machines 1, a plurality of bearings of the same form (same model number) are subjected to a rotation test in parallel, and the measured values of each bearing are sequentially acquired by a single oil content measuring device 2 to perform the same rotation. An average value of measured values obtained from the respective bearings may be obtained every time, and a life prediction line S (regression line) may be obtained based on the respective average values. In this case, since the life prediction line S is obtained based on the measured values measured for a plurality of bearings of the same form (same model number), although the individual is different, the life T of the bearing having higher estimation accuracy than that of the above embodiment is obtained. be able to.

(3) The test time K (1000 hours), the specified number of times (5 times), the limit remaining amount of base oil (60% by weight) and the expected life of the bearing (2000 hours or more) in the above embodiment are merely examples, The present invention is not limited to this.
(4) Although the life prediction line S is shown as a regression curve in FIG. 3, whether the life prediction line S is a regression curve or a regression line is determined solely by the 0th to 5th measurement data X0 to X5. Dependent. Therefore, the life prediction line S may be acquired as a regression line.

  A ... Bearing life evaluation device, 1 ... Rotation tester, 2 ... Oil content measuring device, 3 ... Control operation device

Claims (6)

A bearing life evaluation method for evaluating the life of a grease lubrication type bearing,
For a test time estimated in advance as a period shorter than the life of the bearing, a measurement process for acquiring a relationship between the rotation time and the remaining amount of the base oil contained in the grease as a plurality of measurement values;
A data processing step for obtaining a regression line indicating the relationship between the rotation time and the remaining amount of base oil based on a plurality of measured values;
A bearing life evaluation method comprising: a life judging step in which a rotation time at an intersection of an oil content limit line indicating a limit remaining amount of the base oil and a regression line is used as a bearing life.   The bearing life evaluation method according to claim 1, wherein in the measurement step, the measurement value is acquired by rotating the bearing under a rotation condition corresponding to an actual use state of the bearing.   In the measurement step, measurement values are obtained for a plurality of bearings of the same form, and in the data processing step, an average value of the measurement values of each bearing is obtained for each rotation time, and a regression line is obtained based on the average value. The bearing life evaluation method according to 1 or 2. A bearing life evaluation device for evaluating the life of a grease lubrication type bearing,
A rotation testing machine that rotates the bearing under specific rotation conditions;
An oil content measuring device for measuring the remaining amount of base oil contained in grease at a plurality of rotation times for a test time estimated in advance as a time shorter than the life of the bearing;
A regression line indicating the relationship between the rotation time and the remaining amount of base oil is obtained based on a plurality of measurement values input from the oil content measuring instrument, and the intersection of the oil limit line and the regression line indicating the limit remaining amount of the base oil is obtained. A bearing life evaluation apparatus comprising: an arithmetic unit that obtains the rotation time at the intersection and determines the bearing life.   The bearing life evaluation apparatus according to claim 4, wherein the rotation tester rotates the bearing under a rotation condition corresponding to an actual use state of the bearing. The bearing life according to claim 4 or 5, wherein the arithmetic unit obtains an average value for each rotation time with respect to the measurement values input from the oil content measuring instrument for a plurality of bearings of the same form, and obtains a regression line based on each average value. Evaluation device.

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