JP3636856B2 - Elastic body wear test method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wear test method suitable for use in a wear test of an elastic body, for example, vulcanized rubber, and in particular, the slip ratio between a rotating grindstone and an elastic body test piece pressed against the peripheral surface thereof. The test accuracy is advantageously improved by increasing the setting accuracy.
[0002]
[Prior art]
As a test that has been widely used in the past for the abrasion test of vulcanized rubber, there is a Lambourne abrasion test, and this test is defined in JIS K 6264.
When performing this Lambourn abrasion test using a disk-shaped vulcanized rubber as a test piece, the peripheral surface of the test piece attached to the test piece mounting part is placed on the peripheral surface of the disk-shaped polishing wheel with a predetermined pressing force. And rotating the grinding wheel and the test piece at different peripheral speeds under a predetermined slip ratio to cause wear on the peripheral surface of the test piece. The amount of wear is detected by measuring the mass of.
[0003]
[Problems to be solved by the invention]
By the way, in carrying out such a Lambourn abrasion test, the slip ratio represented by the following equation is calculated as follows: slip ratio = (d−D) ÷ d × 100 (%)
d: Test piece circumferential speed D: Grinding wheel circumferential speed must be set accurately in order to improve test accuracy. For this purpose, it is essential to accurately measure the diameter of the test piece. In this conventional wear test, the test piece diameter is tested using the theoretical value, that is, the mold size when the test piece is manufactured by mold vulcanization, and the size of the cutting blade when the test piece is manufactured by cutting. Since the circumference of the piece, and hence the peripheral speed, was calculated, when the vulcanization return occurred in the test piece or when the cutting edge of the cutting edge deteriorated, the theoretical diameter of the test piece and the test piece A test piece by which a non-negligible fluctuation occurs between the actual static diameter of the test piece and the test piece is sandwiched in the thickness direction by the test piece mounting portion of the wear test device in the wear test. In the radial elastic deformation and the test, The elastic deformation of the specimen by pressing the specimen peripheral surface against the grinding stone peripheral surface with a predetermined force is inevitable, and these are also between the theoretical diameter of the specimen and the actual diameter at the time of the test. Due to the variation in diameter, there is often a large gap between the specimen peripheral speed set based on the theoretical diameter and its actual peripheral speed during the test, hence the wear test. In many cases, it is not possible to realize the slip ratio as expected in the implementation of this, and this is particularly the setting of the slip ratio when performing a wear test with a small slip ratio of about 1 to 5%. There is a problem that it has a great influence on the accuracy and, in turn, the wear test accuracy.
[0004]
The present invention advantageously solves such problems of the prior art, and measures the radius of the test piece for each test piece under the condition in which the actual test conditions are applied. An elastic body wear test method and apparatus capable of greatly increasing the setting accuracy of the slip rate regardless of the magnitude of the slip rate and effectively improving the test accuracy by setting the slip rate based on It is.
[0005]
[Means for Solving the Problems]
According to the wear test method for an elastic body of the present invention, the peripheral surface of a disk-shaped elastic body test piece held by a holder is pressed against the peripheral surface of the rotating grindstone, and the rotating grindstone and the elastic body test piece are Before the start of the wear test in which the elastic test piece is worn by rotating at different peripheral speeds around the rotation axis parallel to the elastic test piece, the elastic test piece held by the holder and rotated freely is the same as during the test. When the elastic grindstone is rotated by the frictional force against the grindstone, the elastic grindstone is rotated at the same peripheral speed as during the test. An interval between the rotation axis of the test piece and the circumferential surface of the grindstone, that is, an interval averaged over the entire circumferential direction of the test piece is compared with a reference interval, and an elastic body test piece is based on a difference between the two intervals. Radius of the test Seeking a radius, from the result, and calculates the elastic body test piece, the peripheral speed at the time of testing.
[0006]
Here, the reference interval between the rotation axis of the test piece and the circumferential surface of the grindstone is less susceptible to dimensional changes due to temperature or the like. For example, a reference sample made of a metal material and having a highly accurate reference dimension is used as the holder. It means an interval when held and pressed against the grindstone circumferential surface with the same force as in the test.
[0007]
In such a test method, when the same condition as the test condition is given to the elastic body test piece, the distance between the test piece rotation axis and the circumferential surface of the grindstone is compared with the reference interval, thereby the test piece. Therefore, it is possible to accurately measure the dimensional difference with respect to the reference sample, and as a result, the dynamic radius at the time of actual test of the test piece can be obtained with high accuracy. By setting the slip ratio, it is possible to sufficiently improve the setting accuracy of the slip ratio and greatly improve the wear test accuracy.
[0008]
An elastic wear test apparatus that can be used in the practice of the present invention is provided with a grindstone drive shaft on which a rotating grindstone is mounted, and extends in parallel with the grindstone drive shaft and at a position facing the grindstone circumferential surface. A test piece drive shaft having a holder for holding a plate-like elastic test piece and having a clutch in the middle is provided, and the test piece drive shaft is attached to the fixed base so that the test piece drive shaft is attached to the fixed base. A movable base that can be displaced in a direction approaching and separating from the grindstone drive shaft is provided, and a displacement sensor that detects the displacement direction and amount of the movable base relative to the fixed base is further provided.
[0009]
Note Here, the displacement sensor can be preferably used capacitance type sensor of non-contact type, eddy current sensors, air micrometer, magnetic sensors, various sensors such as an optical sensor.
For example, the movable base 7 can be moved forward and backward in the direction orthogonal to the axis of the test piece drive shaft 3 under the action of the guide rail 9 laid on the fixed base 8. While maintaining the parallel state, it can approach and displace it.
-Mount the heads 11 on the fixed base 8 respectively.
[0010]
In such a test apparatus, the reference sample held in the holder is pressed against the circumferential surface of the grindstone with the same force as during the test, and the distance between the test piece rotation axis and the grindstone circumferential surface at this time is used as a reference. Prior to the start of the actual wear test, hold the elastic body specimen in the holder and allow the specimen to rotate freely with the clutch released. The elastic body test is performed by pressing the peripheral surface of the elastic body test piece against the peripheral surface of the grindstone with a force equivalent to the pressing force during the test, and rotating the grindstone at the peripheral speed during the test. The piece is rotated at a speed equal to the circumferential speed of the grindstone. At this time, the distance between the rotation axis of the elastic body test piece and the grindstone circumferential surface is compared with the reference distance using a displacement sensor, and the distance relative to the reference distance is measured. Detecting the direction and amount of displacement The dynamic radius of the elastic body test piece is determined with high accuracy, and the setting speed is sufficiently increased by setting the peripheral speed of the elastic body test piece, and thus the slip ratio, based on the dynamic radius. Can do.
Therefore, when starting the wear test thereafter, the wear test accuracy can be greatly improved by rotating the test piece at the required peripheral speed calculated based on the dynamic radius.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below based on the drawings.
FIG. 1 is a plan view showing an essential part of an apparatus that can be used for carrying out the method according to the present invention. In the figure, 1 is a rotating grindstone having a known diameter, and 2 is a rotating grindstone 1. A grindstone drive shaft attached to one end is shown, and the other end of the grindstone drive shaft is connected to a servo motor or other rotational drive means (not shown).
[0012]
Here, a test piece drive shaft 3 is disposed so as to extend in parallel with the grindstone drive shaft 2, and a holder for holding a disc-shaped elastic body test piece 4 at one end of the test piece drive shaft 3. 5 is provided, and the other end is connected to a rotation driving means (not shown) which is separate from the rotation driving means, and a clutch 6 is provided at an intermediate portion thereof.
[0013]
Here, the holder 5 includes a receiving pad 5a provided on the drive shaft side and a clamp pad 5b that is displaced forward and backward with respect to the receiving pad 5a by, for example, a cylinder disposed immediately below the test piece drive shaft 3. These pads 5a and 5b hold the elastic test piece 4 disposed between them with a required force from the thickness direction of the pad 5a and 5b so that the peripheral surface of the test piece faces the peripheral surface of the grindstone 1. Position. Therefore, here, based on the rotation operation of the test piece drive shaft 3, the test piece 4 rotates with the pads 5a and 5b at the same speed as the drive shaft 3.
[0014]
Here, the clutch 6 functions to control connection / disconnection of the test piece drive shaft 3, more directly the holder 5, to the rotational drive means. By releasing the clutch 6, the holder 5 and the test Allow the piece 4 to rotate freely.
[0015]
By the way, such a test piece drive shaft 3 is mounted on the movable base 7 and the test piece drive shaft 3 is operated under the action of a guide rail 9 laid on the fixed base 8, for example. By making it possible to move forward and backward in a direction perpendicular to the axis of the wheel, it is possible to approach and displace it while maintaining a parallel state with the grindstone drive shaft 2.
[0016]
Further, here, in order to detect the relative displacement direction and amount of the movable base 7 with respect to the fixed base 8, a laser displacement meter including a light shielding plate 10 and a sensor head 11 is used as the displacement sensor 12, and the light shielding plate 10 is used as the movable base. 7 and the sensor head 11 are attached to the fixed base 8, respectively.
[0017]
The displacement sensor 12 has a light incident on the light receiving portion 11b of the laser emitted from the light emitting portion 11a of the sensor head 11 in accordance with the amount of the light shielding plate 10 attached to the movable base 7 entering the sensor head 11. Based on the fluctuation, the displacement amount and the displacement direction of the movable base 7 with respect to the fixed base 8 from the reference position are detected.
[0018]
Here, the reference position of the movable base 7 refers to a displacement sensor in which a reference sample having a known radial dimension held by the holder 5 is pressed against the circumferential surface of the grindstone 1 with a predetermined force under the displacement of the movable base 7. In other words, when the calibration of 12 is performed, in other words, the fixed base 8 of the movable base 7 when the distance between the center axis of the reference sample and the circumferential surface of the grindstone is the reference distance equal to the radial dimension of the reference sample. Means relative position to.
[0019]
When a wear test of an elastic body test piece is performed using the apparatus configured as described above, the elastic test piece 4 is held in the holder 5 and the test piece drive shaft is set prior to the start of the test. 3, the test piece drive shaft 3, or directly the movable base 7, is advanced and displaced toward the grindstone drive shaft side under the action of an advancing / retreating drive means (not shown). The peripheral surface of the piece 4 is pressed against the peripheral surface of the grindstone 1 with a force equivalent to that during the wear test, and the grindstone 1 is rotated at a speed equal to the peripheral speed during the test, thereby elastic test piece 4 Is rotated by the frictional force on the grindstone 1.
[0020]
Then, the distance between the rotation axis of the test piece 4 and the circumferential surface of the grindstone during such rotation is measured by the displacement sensor 12 for each of the displacement amount and the displacement direction of the movable base 7 with respect to the reference position. Then, the measured value is obtained by addition / subtraction with respect to the reference position dimension, and the calculated value at this time is set as the dynamic radius of the elastic body test piece 4.
[0021]
In this case, the distance between the rotation axis of the test piece and the circumferential surface of the grindstone is slightly changed depending on the contact position in the circumferential direction between the test piece 4 and the grindstone 1 due to a molding error of the elastic test piece 4 and the like. However, the influence of the change can be sufficiently reduced by measuring the interval a plurality of times during the rotation of the test piece 4 and averaging the measured values.
[0022]
Therefore, after that, from the dynamic radius of the test piece 4 obtained as described above, the circumference of the test piece 4 at the time of the test is obtained, and by setting the required slip ratio based on this circumference, The slip rate can be set with high accuracy regardless of the size.
[0023]
By the way, this slip ratio is set according to the circumference of the test piece 4 with the rotational drive means while the clutch 6 of the test piece drive shaft 3 is in the connected state in the wear test. It can be achieved by rotating at the rotational speed to bring the desired circumferential speed difference between the grinding wheel circumferential speed and the specimen circumferential speed. Each of the grindstone 1 and the test piece 4 is predetermined by pressing the grindstone 1 and the test piece 4 rotating by the difference with a predetermined force under the advancing displacement of the movable base 7 or after pressing both of them. It can be started by rotating at a peripheral speed.
[0024]
Thus, according to the present invention, the radius of the elastic specimen 4 under the test condition, that is, the dynamic radius can be measured with high accuracy, and thereby the circumference under the test condition can be sufficiently accurately measured. Therefore, the setting accuracy of the slip ratio can be greatly increased as compared with the conventional technique using the theoretical diameter, and as a result, the test accuracy of the wear test can be effectively improved.
[0025]
【The invention's effect】
As is apparent from the above description, according to the method of the present invention, the setting accuracy of the slip ratio can be increased and the wear test accuracy can be greatly improved, and according to the implementation apparatus of the present invention, The dynamic radius of the elastic specimen can be measured simply, easily and accurately.
[Brief description of the drawings]
FIG. 1 is a plan view showing an essential part of an apparatus that can be used for carrying out a method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Grindstone 2 Grindstone drive shaft 3 Test piece drive shaft 4 Elastic body test piece 5 Holder
5a Receiving pad
5b Clamp pad 6 Clutch 7 Movable base 8 Fixed base 9 Guide rail
10 Shading plate
11 Sensor head
11a Light emitter
11b Receiver
12 Displacement sensor

Claims (1)

The peripheral surface of the disk-shaped elastic body test piece held by the holder is pressed against the peripheral surface of the rotating grindstone, and each of the rotating grindstone and the elastic body test piece is moved around the rotation axis parallel to each other. A wear test method in which an elastic specimen is worn by rotating at high speed,
Prior to the start of the test, the elastic test specimen held by the holder and made rotatable is pressed against the rotating grindstone with the same force as during the test, and the rotating grindstone is rotated at the same peripheral speed as during the test. In this case, the interval between the rotation axis of the elastic specimen and the peripheral surface of the grindstone is compared with the reference interval, and the radius of the elastic specimen is tested based on the difference between the two intervals. this result of the elastic body test piece, abrasion test method of the elastic body you and calculates the peripheral speed at the time of testing.

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