JP3980225B2 - Friction tester and friction test method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a friction tester for evaluating the friction force and wear amount of a surface of metal or ceramic, and more particularly to a V block / pin type friction tester.
[0002]
[Prior art]
Conventionally, as a friction tester for evaluating changes in frictional force and wear when a surface treatment is performed on a contact surface with another member such as metal or ceramic or when a medium such as a lubricating oil is used, a V-block is conventionally used. A pin type friction tester is known.
[0003]
In this friction tester, as shown in FIG. 4, two test pieces 101 each having a 90-degree V-shaped notch on the end face of a cylindrical material are used, and both sides are provided on the peripheral surface of a rotating pin 102. The frictional force and the amount of wear on the surface of the test piece are measured by measuring the friction torque of the pin 102 by contacting with a predetermined pressure.
[0004]
[Problems to be solved by the invention]
Such a conventional V block / pin type friction tester has the following problems. 1) Since a V-shaped notch has to be further processed in a columnar material, it takes time to produce a test piece. 2) In order to raise the accuracy of the test, it is necessary to perform a plurality of tests, but the surface once used for the test has a wear mark on the line contact portion and cannot be used unless reworked. 3) Since the V-shaped cut is machined, the surface state varies and the reproducibility is not good. 4) After the test, when the wear state is observed with a microscope, it is difficult to observe because it is V-shaped.
[0005]
Accordingly, the present invention provides a friction tester and method that can use a test piece that does not require a V-shaped notching process, thereby making the test piece easy and capable of measuring with good reproducibility. With the goal. Another object of the present invention is to provide a friction tester and method that can repeatedly use one test piece and can reduce running costs. It is another object of the present invention to provide a friction testing machine and method that can be used without significantly changing the conventional V-block / pin type friction testing machine.
[0006]
[Means for Solving the Problems]
The present invention which achieves such an object includes a rotating pin, a means for rotationally driving the rotating pin about its axis, and a pair of test piece fixing means arranged symmetrically so as to sandwich the peripheral surface of the pin And holding means for holding the test piece fixing means and moving the pair of test piece fixing means so that the test piece fixed to the test piece fixing member contacts the peripheral surface of the pin with a predetermined pressure; Means for measuring a change in torque between the pin and / or a distance between the pair of test piece fixing means, and each of the pair of test piece fixing means includes two regular square columnar test pieces. Provided is a friction tester characterized by comprising means for fixing one side surface of each regular quadrangular column at right angles to each other.
[0007]
Further, the present invention provides a groove member in which the test piece fixing member is provided with a plurality of grooves engaged with two adjacent side surfaces of the regular square columnar test piece as means for fixing the test piece, and a groove of the groove member Provided is a friction testing machine comprising a pair of reinforcing plates that are detachably fixed in a vertical direction and sandwich a test piece engaged with each groove.
[0008]
Furthermore, the present invention provides a friction tester, wherein the test piece fixing member is fixed to the holding means via a universal joint.
[0009]
Further, the present invention also provides a method in which the test pieces fixed to the pair of test piece fixing means are pressed against the peripheral surface of the rotatable pin symmetrically, so that the friction torque during the rotation of the pin and / or the pair of test piece fixing means. A friction test method for measuring a change in distance between the test pieces and measuring a friction force and a wear amount of the test pieces. Four test pieces of four square prisms are prepared as the test pieces. One set of square prismatic test pieces are fixed so that one side of each of them is perpendicular to each other, and two sets of test pieces are fixed at a predetermined pressure on the pin. The friction test method is characterized in that it is held so as to be in contact with each other.
[0010]
In addition, the present invention provides a friction test method characterized by repeatedly measuring the four side surfaces of the four regular square columnar test pieces by sequentially changing the side surfaces in contact with the pins.
[0011]
According to the friction tester and the friction test method of the present invention as described above, a test piece having a square prism shape is used as a test piece. There are very few. In addition, since the four surfaces of the regular quadrangular prism can be sequentially subjected to the test, four tests can be performed with one test piece, and the cost can be reduced. In addition, the surface of the test piece can be easily observed, and unlike a V-shaped notch, the surface of the test piece can be viewed from the front, and the surface can be easily observed. Furthermore, two regular square columnar test pieces are combined into a V shape and pressed against the rotating pin. The mechanism other than the mechanism for holding the test piece is a conventional V-block / pin type friction tester. It can be used as it is.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a view showing an embodiment of a friction testing machine according to the present invention. This friction testing machine mainly includes a mechanism for rotating a metal pin 15 at a predetermined rotational speed, and a peripheral surface of the pin 15. A holding mechanism for pressing the test piece 50 at a predetermined pressure, a temperature adjusting mechanism 30 for adjusting the temperature of the measuring section, and a pin rotating mechanism, a holding mechanism, and a temperature adjusting mechanism 30 and controlling the pin rotation. The control / measurement unit 40 calculates the frictional force and the wear amount by inputting the friction torque and the distance between the test pieces.
[0014]
The pin rotation mechanism includes a motor 11, a rotation shaft 14 connected to the rotation shaft of the motor 11 by a pair of pulleys 12 and a belt 13, and a rotation shaft 14 rotated by the motor 11, and a pin 15 fixed to one end of the rotation shaft 14. The motor 11 is provided with a speed controller 16 controlled by a command from the control / measurement unit 40 and a display unit 17 for displaying the rotational speed of the pin 15.
[0015]
A torque meter (not shown) provided with a strain amplifier 18 is connected to the rotating shaft 14 to which the pin 15 is fixed, and the friction torque at the time of rotating the pin is measured. A signal corresponding to the friction torque from the strain amplifier 18 is input to the control / measurement unit 40, where a predetermined calculation is performed to obtain the friction force.
[0016]
The holding mechanism is fixed to a pair of holding members 21, 21 ′ arranged substantially symmetrically with respect to the pin 15, and one end of these holding members 21, 21 ′, and the test piece is fixed to face the pin 15. And fixing means 22 and 22 'for driving, and driving means 23 for driving the holding members 21 and 21' so as to press the test piece 50 fixed to the fixing members 22 and 22 'against the pin 15.
[0017]
As the driving means 23, an air cylinder or a hydraulic cylinder can be used. The load applied to the test piece is relatively small. For example, when the weight is about 500 kg, an air cylinder is used, and when the load is 1 ton or more, a hydraulic cylinder is used. . Hereinafter, although it demonstrates as an air cylinder, it is not limited to this.
[0018]
As described above, the holding members 21 and 21 ′ are long members having the fixing members 22 and 22 ′ fixed to one end, and the center in the longitudinal direction is fixed to the apparatus main body so as to be freely rotatable. Such holding members 21, 21 ′ are in a direction in which the fixing members 22, 22 ′ fixed to one end thereof are close to each other by the air cylinder 23, that is, in a direction in which the test piece is pressed against the pin 15 existing in the center thereof. Driven. The air cylinder 23 is connected to an air source (not shown) via a precision pressure reducing valve 26, and the test piece pressing force against the pin 15 can be adjusted by adjusting the precision pressure reducing valve 26.
[0019]
A proximity sensor 24 is attached to one end and a pressure sensor 25 is attached to the other end of the holding member 21, 21 ′ opposite to the end where the fixing members 22, 22 ′ are fixed. The proximity sensor 24 is a sensor that detects a displacement (amount of wear of the test piece) between the fixed members 22 and 22 ′ by detecting a distance (amount of displacement) between the end portions of the holding members 21 and 21 ′. A known displacement sensor such as a displacement sensor using a transformer or a capacitance type displacement sensor can be used. A signal from the proximity sensor 24 is input to the control / measurement unit 40, where the amount of wear of the test piece 50 is calculated based on the amount of displacement between the ends of the holding members 21, 21 '.
[0020]
The pressure sensor 25 includes a known pressure sensor such as a load cell using a piezoelectric crystal or a semiconductor pressure sensor, and detects a pressing force applied to the holding member 21 ′ via the test piece 50. The signal from the pressure sensor 25 is input to the control / measurement unit 40 via the instruction amplifier, and the control / measurement unit 40 calculates the frictional force based on this signal and the signal from the torque meter.
[0021]
The temperature adjustment mechanism 30 includes a thermostat 31 containing a heat medium such as oil, a heater 32 for heating the thermostat 31 to a constant temperature, a temperature sensor 33 such as a thermocouple for monitoring the temperature of the thermostat 31, and the heater 32. An adjuster 34 for adjusting the temperature is provided, and a signal from the temperature sensor 33 is input to the control / measurement unit 40. By controlling the adjuster 34 based on this signal, the temperature of the thermostatic bath 31 is feedback-controlled and kept constant. It is kept. The measurement by this testing machine is performed in a state where the end portions of the holding members 21 and 21 ′ to which the test piece 50 is fixed are immersed in such a constant temperature bath 31.
[0022]
Next, details of the test piece 50 and the fixing member 22 will be described with reference to FIGS. Since the other fixing member 22 'is exactly the same, only the fixing member 22 will be described here.
[0023]
As shown in FIG. 2, the test piece 50 is a regular quadrangular prism having a side surface processed with high accuracy, and has a cross section of 5 mm × 5 mm and a length of about 12 mm, for example. Such a test piece 50 can be manufactured, for example, by dividing a columnar material having a cross section of 5 mm × 5 mm and a length of about 48 mm into four in the longitudinal direction. In the friction tester of the present invention, two such test pieces 50 are made into a set and fixed to the fixing member 22.
[0024]
As shown in FIG. 2, the fixing member 22 includes a block 221 in which two V-shaped grooves with which two side surfaces of the two test pieces 50 are engaged, and the block 221 from above and below in the groove direction. It consists of reinforcing plates 222 and 223 fixed to the block 221 so as to be sandwiched, and a back plate 224 fixed to the back surface of the block 221 (the back surface of the surface on which the groove is formed).
[0025]
As shown in FIG. 3A, the angle formed by the inner surface of the V-shaped groove is 90 degrees, and when the test pieces 50 are engaged with the two grooves, the side surfaces 50a adjacent to each other of the two test pieces 50 are shown. , 50a forms 90 degrees, and these two side surfaces are configured to contact the pin 15. The width d of the inner surface of the V-shaped groove is substantially equal to the width of the side surface of the test piece 50, but may be larger or smaller than this. In short, the two adjacent corners of the two test pieces 50 do not interfere with each other and the two test pieces 50 project outside the block 221 when the peripheral surface of the pin 15 is brought into contact with the side surfaces 50a, 50a of the two test pieces 50. What is necessary is just to be arrange | positioned with respect to a test piece in the position which does not exceed the center of a pin the line which connects the corner | angular of a test piece.
[0026]
The height h of the block 221 (the length of the V-shaped groove in the groove direction) is the same as the height of the test piece 50 as shown in FIG. When tightened from above and below at 223, the test piece 50 is securely fixed between the reinforcing plates. The reinforcing plates 222 and 223 are fixed to the block 221 with screws or the like, and the test piece 50 is attached to and detached from the fixing member 22 by removing the reinforcing plate.
[0027]
The block 221 is connected to one end of the holding member 21 by a universal joint 27. For this reason, a hemispherical spherical seat that receives the spherical portion of the universal joint 27 is formed on the back side of the block 221. The back plate 244 fixes the universal joint 27 to the block 221, and an opening with which a part of a sphere of the universal joint 27 engages is formed at the center of the plate.
[0028]
The end portion of the holding member 21 to which the fixing member 22 is fixed moves in an arc shape by the rotation of the holding member 21. However, by connecting the fixing member 22 and the support member 21 by the universal joint 27, Although the movement trajectory of the part is circular, the side surface of the test piece 50 can be brought into pressure contact with the peripheral surface of the vertical pin 15 in close contact. Further, even if the pair of fixing members 22 and 22 'are slightly deviated from the 180 degree position (symmetric position) with respect to the center of the pin, that is, the position of the fixing member shown in FIG. Even when the fixing member is rotated by the universal joint, the four test pieces 50 can always be brought into pressure contact with the pin 15.
[0029]
Next, a friction test method using the friction tester configured as described above will be described. In the friction test of the present invention, the test piece itself is used as a sample to measure the amount of wear and frictional force of the surface, and a medium such as a lubricating oil is interposed between the pin and the test piece so that the medium is rubbed. It can also be applied when evaluating effects on wear and wear. Here, the case where the wear amount and frictional force of the test piece itself are measured will be described.
[0030]
First, four square prismatic test pieces 50 having the same shape and the same size are prepared, and the two pieces are fixed to the fixing members 22 and 22 ′ as one set. Next, the air cylinder 23 is driven, and the fixing members 22 and 22 ′ fixed to the holding members 21 and 21 ′ are pressed against the pin 15 with a predetermined pressing force. This pressing force is detected by the pressure sensor 25 and input to the control / measurement unit 40.
[0031]
In this state, the holding members 21, 21 ′ to which the fixing members 22, 22 ′ are fixed are immersed in the thermostat 31, and after waiting for the temperature of the test piece to reach a constant temperature, the motor 10 is driven to drive the pins 15. Rotate. The rotation speed is controlled by the speed controller 16 that receives a command from the control / measurement unit 40 so as to have a predetermined value. The test time, that is, the time for which rotation is continued, varies depending on the sample and the object of measurement (friction force or wear amount), but is usually about several minutes to 48 hours. Torque applied to the rotary shaft 14 during rotation is measured by the torque meter 18 and sent to the control / measurement unit 40. The control / measurement unit 40 calculates a friction force F and a friction coefficient μ from the torque TQ and the pressing force Wg to the pin detected by the pressure sensor 25 based on the following equations.
[0032]
[Expression 1]
F = TQ / r (1)
μ = F / 4W (2)
W = (1/2) × {Wg / cos (90-θ / 2)} (3)
[0033]
In equations (1) to (3), r is the radius of the pin, W is the pressing force applied in the radial direction (perpendicular to the surface) from the surface of one test piece 50, and θ is the adjacent test. The angle (90 degrees here) formed by the two side surfaces of the piece 50 is represented.
[0034]
Further, since the rotation is continued for a relatively long time, the distance between the two pairs of test pieces changes due to wear of the test piece 50. The proximity sensor 24 detects this change in the distance between the test pieces as a change in the distance between the holding members 21 and 21 ′ and sends it to the control / measurement unit 40. The control / measurement unit 40 calculates the wear amount from this displacement amount.
[0035]
In order to increase the accuracy of the measurement, it is desirable to repeat the above-described measurement a plurality of times. In that case, the same test piece 50 is used, but the fixing position to the fixing member 22 (22 ′) is changed. That is, since only one side surface 50a of the columnar test piece 50 is used in the above measurement, all the test pieces 50 are re-fixed so that the other side surface is in contact with the pin 15, and the same measurement is performed. I do. This allows up to four measurements using the same test piece. Since all of the side surfaces of the test piece used in the four measurements are formed by plane processing, the processing accuracy is good, and as a result, a reproducible measurement result can be obtained.
[0036]
The frictional force and the wear amount thus measured are displayed and printed by a display device or a printing device (not shown) connected to the control / measurement unit 40. The test piece used for the four measurements can be reused by polishing the side surface thereof.
[0037]
In the above-described embodiments, the friction tester that abuts the test piece against the pin by rotating the holding member that fixes the test piece by a driving mechanism such as an air cylinder has been described. It is also possible to adopt a method of moving in the horizontal direction by the drive mechanism. Further, the mechanisms and sensors employed in the respective parts of the above embodiments can be replaced with various known mechanisms and sensors.
[0038]
【The invention's effect】
The friction tester and method of the present invention can perform a high-precision friction / wear test simply and at low cost by using four test pieces having a square prism shape in combination as test pieces.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram showing an embodiment of a friction tester of the present invention. FIG. 2 is an exploded view showing a test piece and a fixing member used in the friction test of the present invention. FIGS. 4A and 4B are diagrams showing an embodiment of a test piece fixing member, in which FIG. 4A is a top view and FIG. 4B is a side view. FIG. 4 is a diagram showing a conventional V-block / pin type friction tester.
11 .... Motor (rotation drive means)
15... Rotating pin 21, 21 ′ ...... Holding member 22, 22 ′ ...... Fixing member 40 ...... Control / measuring unit 50 ...... ·Test pieces

Claims (5)

A rotating pin, a means for rotationally driving the rotating pin about its axis, a pair of test piece fixing means arranged symmetrically so as to sandwich the peripheral surface of the pin, and holding each test piece fixing means; Holding means for moving the pair of test piece fixing means so that the test piece fixed to the test piece fixing member comes into contact with the peripheral surface of the pin at a predetermined pressure; and torque during rotation of the pins and / or the In a friction tester equipped with a means for measuring a change in the distance between a pair of test piece fixing means,
Each of the pair of test piece fixing means includes a means for fixing two regular square columnar test pieces so that one side surface of each regular square column is perpendicular to each other. The test piece fixing means, as means for fixing the test piece, is a groove member provided with a plurality of grooves engaged with two adjacent side surfaces of the regular square columnar test piece, and is detachable up and down in the groove direction of the groove member. The friction tester according to claim 1, further comprising a pair of reinforcing plates that are fixed to each other and sandwich a test piece engaged with each groove. The friction tester according to claim 1 or 2, wherein the test piece fixing member is fixed to the holding means via a universal joint. The test pieces fixed to the pair of test piece fixing means are pressed against the peripheral surface of the rotatable pin symmetrically, and the friction torque during the rotation of the pin and / or the change in the distance between the pair of test piece fixing means. Is a friction test method for measuring the friction force and wear amount of the test piece,
As the test piece, four regular square columnar test pieces are prepared,
Fix two of the four test pieces as a set, and fix a set of regular quadrangular columnar test pieces so that one side thereof is perpendicular to each other,
A friction test method characterized in that two sets of test pieces are held so that two side surfaces forming a right angle are in contact with the pin at a predetermined pressure. The friction test method according to claim 4, wherein the four test pieces are repeatedly measured for four side faces by sequentially changing the side faces in contact with the pins.

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