JPH05332909A - Friction/abrasion tester - Google Patents

Abstract

PURPOSE:To accurately measure friction characteristics and abrasion characteristics of a material by driving a first urging body to obtain the reciprocation necessary for generation of the friction or abrasion, and measuring the friction or abrasion by means of a measuring part provided at a second urging body. CONSTITUTION:Linear bearings 2 and 3 on a base 1 are provided with first and second urging bodies 4 and 10, respectively. While a sample A and a sample B are respectively mounted on the urging body 4 and an intermediate member 12, a desired weight, is set, in a weight holder 14. The member 12 is balanced around a horizontal shaft 11 by a counter weight 13 when without the weight in the weight, holder 14. Therefore, if the weight is disposed, a load corresponding to the weight acts between the samples A and B. When a motor 5 is rotated with a predetermined rotating number by a control part 7, the urging body 4 reciprocates in the horizontal direction. At this time, the frictional force generated between the samples A and B is transmitted to a load cell of a measuring part 15 secured to the base 1 via the member 12, the horizontal shaft 11 and an arm 17. The output of the load cell indicates the frictional force acting between the samples A and B.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a friction and wear test apparatus for measuring friction or wear characteristics of various materials.

[0002]

2. Description of the Related Art In recent years, in order to meet the demand for wear resistance in industrial materials, ceramic materials have been widely used instead of metal materials.
PVD such as VD or ion plating, or surface treatment such as ion implantation is widely applied.

The evaluation of the wear resistance of industrial materials is based mainly on the judgment of wear loss. The greatest force that leads to this wear is
It is a resistance force, that is, a frictional force, which acts between two objects that are in contact with each other. The ratio of the frictional force to the contact load between two objects that produces it is the frictional coefficient, and the value of the frictional coefficient varies greatly depending on the conditions of the actual contact area. For example,
When abrasion powder is present between two objects that come into contact with each other, the abrasion powder may act as an abrasive powder to promote abrasion, or it may act like a bearing to protect from abrasion. Therefore, when evaluating the wear characteristics of a material based on the magnitude of the friction coefficient, it is essential to consider the behavior of wear particles.

FIG. 2 shows a friction and wear test apparatus already developed by the present inventor. This apparatus is provided with a support 102 for supporting the flat plate-shaped test piece S on one end side of a base 101, and an eccentric cam 104 rotated by a motor 103 on the other end side. A guide cylinder 105 supported by the base 101 is provided between the support body 102 and the eccentric cam 104, and a sliding rod 106 is slidably inserted in the guide cylinder. The eccentric cam 104 is provided at one end of the sliding rod 106.
A cam follower 107 is provided in contact with the cam follower 107, and the cam follower 107 is pressed against the eccentric cam by a compression coil spring 108 arranged between the cam follower 107 and the guide cylinder 105. The other end of the sliding rod 106 extends above the test piece S, and a spherical test piece T is fixedly attached to the lower surface of the tip of the test piece S and is in contact with the upper surface of the test piece S. A weight 109 is hung between the guide tube 105 and the test piece T in the sliding rod 106, and serves to press the test piece T against the test piece S with a constant force. The sliding rod 106 is partially thin,
The strain cage 110 is attached there. Strain gauge 11
The output of 0 is connected to the recorder 112 via the amplifier 111.

When using this apparatus, the motor 103 is rotated at a predetermined speed while the test piece T is pressed against the test piece S, and the sliding rod 106 is reciprocated via the eccentric cam 104. The frictional force acting between the test piece T and the test piece S becomes a resistance force against this reciprocal movement, whereby the sliding rod 106 expands and contracts, and the expansion and contraction is detected by the strain gauge 110 and recorded in the recorder 112. To be done. The friction coefficient is obtained from the ratio of the thus obtained friction force and the weight 109.

However, in this apparatus, the sliding rod 106 is provided with a measuring section (strain gauge 110). As described above, since the reciprocating member is provided with the measuring section, when the weight of the measuring section is increased, the inertia of the reciprocating section is increased and the measurement of the force acting thereon is affected. Therefore, only a measuring member having a small weight can be attached to the measuring section. Strain gauges are light in weight and meet this requirement. However, in order to increase the accuracy of the measurement with the strain gauge, it is necessary to increase the strain at the position where the strain gauge is attached to some extent, and in this device, a part of the sliding rod is thinned. As a result, the thinned portion is likely to cause distortion of a component perpendicular to the sliding direction. This vertical strain has a problem that it affects the measured value of the strain gauge and causes a decrease in measurement accuracy. In addition, since the reciprocating member is provided with the measuring unit, vibration of the driving source and the like cause noise, which affects the measuring unit, and from this point also the measurement accuracy is reduced.

It is an object of the present invention to solve the above problems of the conventional apparatus and to provide an apparatus capable of accurately measuring the frictional property or wear property of a material.

[0008]

The above objects of the present invention are as follows:
A horizontal supporting surface provided in the stationary system, a first sliding body and a second sliding body slidably supported on the supporting surface in a low friction state, and the first sliding body on the supporting surface. A driving unit for sliding, a first test piece holding unit attached to the first sliding body, an intermediate member attached rotatably around a horizontal axis with respect to the second sliding body, and the intermediate member. Installed,
It is attached to the intermediate member on the side of the second test piece holding section from the horizontal axis, and the second test piece holding section which holds another test piece in contact with the upper surface of the test piece of the first test piece holding section. A weight, and a measuring unit arranged to connect the second sliding body and the stationary system to measure a transmission force acting on the second sliding body from the first test piece through the second test piece. It is achieved by the friction and wear test device characterized by the above.

[0009]

In the friction and wear test apparatus according to the present invention, it is possible to slide on the stationary support surface in a low friction state.
It supports the sliding body and the second sliding body, and the first sliding body supports the first sliding body.
The test piece holding part is provided, the second test piece holding part is provided on the side of the second sliding body, and the two test pieces are brought into contact with each other under the load of the weight. When the first sliding body is reciprocated in this state, the second sliding body tries to move along with the first sliding body based on the frictional contact between the first test piece and the second test piece. On the other hand, a measuring unit is provided between the stationary type and the second sliding body, and the measuring unit has a function of measuring the transmission force acting on the second sliding body from the first test piece through the second test piece. have. Therefore, the transmission force measured by the measuring unit can be regarded as the frictional force. In this way, the reciprocating motion required for the generation of friction or wear is generated by driving the first sliding body, and the measuring section is provided on the second sliding body, so that the measuring section has a relatively heavy weight such as a load cell. Even if a measuring member having a large size is used, the reciprocating motion is not affected by the inertial action. Therefore, in order to reduce the weight, it is not necessary to use a strain gauge that may cause a problem of bending in a direction perpendicular to the reciprocating motion, and various measuring devices can be widely used, and friction or The wear can be measured and evaluated easily and accurately. In addition, since the reciprocating member and the measuring section are separately arranged, there is no problem that vibration of the driving source causes noise and affects the measuring section. Be done.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows a friction and wear test device according to one embodiment of the present invention. This device comprises linear bearings 2, 3 arranged on a base 1 at intervals and each having a horizontal support surface. A horizontally extending first sliding body 4 is placed on the linear bearing 2, and a flat plate-shaped first test piece A is horizontally supported by a first test piece holding portion 8 at one end of the first sliding body. Has been done. The other end of the first sliding body is connected to an eccentric cam 6 axially attached to the motor 5, and the rotation of the motor 5 causes the first sliding body 4 to reciprocate in the horizontal direction with a constant amplitude. Motor 5
A control unit 7 for controlling the rotation speed is connected to the. The second sliding body 10 is provided on the linear bearing 3.
Is mounted, and a horizontal shaft 11 extending vertically to the sliding direction is provided at the upper end portion thereof. A rod-shaped intermediate member 12 is supported on the horizontal shaft 11 so as to be rotatable around the horizontal shaft. One end of the intermediate member 12 extends above the first test piece A, and a spherical second test piece B is held by the second test piece holding portion 9 on the lower surface of the tip end portion thereof. At the other end of the intermediate member 12, counter weights 13 for balancing the weights on both sides of the intermediate member 12 with respect to the horizontal shaft 11 are attached. The weight holder 14 is provided at a position ⅓ of the distance from the horizontal shaft 11 to the second test piece B. The base 1 has a measuring unit 15 near the linear bearing 3.
The measuring unit includes a fixing unit 16 fixed to the base 1 and having a load cell inside, and an arm 17 fixed to the second sliding body and acting on the load cell of the fixing unit 16. There is. The output of the load cell is connected to the computer 21 via the amplifier 20.

In this apparatus, a flat plate-shaped test piece was used as the first test piece and a spherical test piece was used as the second test piece. However, the arrangement of the test pieces can be reversed, and as required. It is also possible to use test pieces of various shapes.

This test apparatus is used as follows. With the sample A attached to the first sliding body 4 and the sample B attached to the intermediate member 12, a desired weight is attached to the weight holder 14. The intermediate member 12 maintains the weight balance around the horizontal axis 11 by the counterweight 13 in the state where there is no weight. Therefore, by attaching the weight, a load corresponding to the weight is applied between the sample A and the sample B. It will work in between. In this example, 1/3 of the weight of the weight acts from the position of the weight holder as described above. In this state, the control unit 7 rotates the motor 5 at a predetermined rotation speed. As a result, the first sliding body 4 reciprocates in the horizontal direction. At this time, the frictional force generated between sample A and sample B is
It is transmitted to the load cell of the measuring unit 15 via the intermediate member 12, the horizontal shaft 11, and the arm 17. The frictional force acting between the samples A and B can be obtained based on the output of the load cell.

In the illustrated example, the frictional force F at 1/2 cycle can be obtained by the following equation. F = κ (T−i) / 2 where κ is a correction value specific to each load cell for reading the voltage value obtained by the load cell into a load value, T is the measured voltage amount, and i is the second sliding body and The weight of the accessory itself is the amount of voltage corresponding to the frictional force acting on the contact surface between the second sliding body and the stationary system. This friction force F and vertical load N
Therefore, the friction coefficient μ can be obtained from the following equation.

Μ = F / N The value of "i" can be obtained, for example, as follows. Under a minimum vertical load, select a low friction material for the first and second test pieces, and use a lubricant to reduce the frictional force between both test pieces to a very low level. Even if the second slide body is reciprocated, the second slide body remains stationary or no force is detected by the measurement unit. For example, polytetrafluoroethylene is used as both test pieces, and a low-viscosity lubricating oil is interposed between them. In this state,
The frictional force between the second sliding body and the stationary system is the same as the first test piece and the second test piece.
Greater than frictional force between test pieces. From this state, the frictional force between the first test piece and the second test piece is increased by changing the lubricant, and the second sliding body moves or reciprocates with the reciprocating movement of the first sliding body, or The force is detected and the frictional force at this time is read. This substantially corresponds to the above-mentioned "i".

By continuing the reciprocating motion of the first sliding body of the test apparatus for a predetermined time and reading the output from the load cell, it is possible to measure the changes with time in the friction characteristics and wear characteristics between the samples. In this example, since the output from the load cell is connected to the computer, by sampling the output at a predetermined time interval, it is possible to read the change over time in the friction force or the friction coefficient in real time.

Tests and test results conducted using the illustrated apparatus will be described below. The test conditions were as follows.

First test piece: length 75 mm, width 25 mm,
Flat test piece with a thickness of 1 mm 2nd test piece: Spherical test piece with a diameter of 10 mm Material of test piece: 1st test piece SUS304 2nd test piece SUS304 and SUJ2 (all surface finished by lapping) 1st slide Reciprocating stroke of moving body: 10 mm Vertical contact load of the second test piece to the first test piece: 0.9
8N and 4.9N Vibration frequency of the first sliding body: 1 Hz and 2 Hz Reciprocating frequency of the first test piece: 7200 cycles The obtained results are shown in FIGS. 3 to 6. 3 to 5 are
FIG. 3 shows the test results when the frequency of the first sliding body is set to 2 Hz and the material of the test piece and the vertical contact load are changed.
FIG. 4 is a graph showing the relationship between the number of reciprocating movements of the first sliding body and the friction coefficient, and FIG. 5 shows the wear marks after the reciprocating movement of 7200 cycles under each test condition. It is a profile shown by the cross section perpendicular to the moving direction. FIG. 6 is a graph showing the relationship between the number of repetitions and the coefficient of friction when the frequencies of the first sliding body are 1 Hz and 2 Hz.

Both the first and second test pieces are SUS3
In the case of No. 04, despite the relatively low friction coefficient as shown in FIGS. 3 and 4, the wear scar shown in FIG. Also shows a considerable size, and shows an extremely wide width when the vertical contact load is 4.9 N. This can be explained by the action of the "third body" proposed by Godet and Iwabuchi. The third body is a contact surface inclusion existing between two objects that come into contact with each other, and in the case of the present invention, means a wear powder. That is, this is a device based on the theory that wear particles are generated and aggregated in the wear process to form a deposited layer while being densified, and that this exhibits a single object-like appearance at the contact interface.
In order for the aggregate of wear particles to act to prevent the metal contact between the two solids in contact with each other, it is necessary to have a proof stress for supporting the contact load acting between the two solids in contact with each other. The strength of this strength is mainly
It is considered that it depends on four factors such as the degree of agglomeration of wear particles, the size and hardness of the densified friction particles, and the thickness of the deposited layer. In the case of reciprocal sliding friction due to ball-to-plane contact as in this test, the factors that directly affect these four factors are the specimen size, reciprocating amplitude, reciprocating frequency, and vertical It can be estimated that it is a contact load. For example, as shown in FIG. 6, even with the same combination of test pieces under a constant vertical contact load condition, different results are obtained only by changing the reciprocating frequency from 1 Hz to 2 Hz. This clarifies the influence of the above-mentioned reciprocating frequency on the behavior of the friction powder. Similarly, when the vertical contact load is changed from 0.98 N to 4.9 N, different results are obtained as shown in FIGS. 3 and 4. From this fact, the behavior of the abrasion powder during this frictional wear test can be inferred to some extent.

The upper spherical test piece (first test piece) is SUJ2.
In the case where the lower flat plate-shaped test piece (second test piece) is a combination of SUS304, as shown in the results of both FIG. 3 and FIG. 4, a very high friction coefficient is exhibited in the first stage of sliding, Immediately after that, the value sharply decreased to around 0.4. Thereafter, although it fluctuates to some extent, it reaches a value of 0.8 to 0.9 after about 800 cycles and maintains that value. Since the driving force for generation of wear particles is considered to be a large frictional force due to metal contact, it is considered that active friction particles are generated at the contact portion by repeated sliding for about 800 cycles. As shown in FIG. 3, the vertical contact load is 0.
At 98 N, a high friction coefficient is shown over the entire friction and wear test, but a sharp decrease in the friction coefficient is recognized around 3600 cycles and 5000 cycles. Similarly, when the vertical contact load is 4.8 N, 2700,
This phenomenon is observed near 4500 and 5800 cycles. It is considered that this abrupt decrease is due to the fact that wear particles are deposited between the two solids in contact with each other and a layer having a certain thickness is formed, so that it behaves like a bearing. Therefore, when the vertical contact load is 0.98 N, the reciprocal sliding amplitude is 10 mm, which is relatively large.
The generated wear debris was easily discharged from the contact portion, and the contact 2 solid was always in metal contact, and it is considered that such a high friction coefficient was generally exhibited. Even with the same combination of test pieces, when the vertical contact load is 4.9 N, a low friction coefficient of about 0.6 is constantly shown after 5800 cycles. FIG. 5 showing wear damage under these conditions
From the profile of the wear mark in (c), it is understood that the wear appearing on the surface of the lower flat plate-shaped test piece tends to expand the damage in the depth direction. Therefore, it is considered that the wear damage increases in depth by repeating up to about 5,800 cycles, and the generated wear powder accumulates in the wear damaged portion. In addition, since a relatively large vertical load of 4.9 N is applied to the contact portion, the accumulated wear debris is not easily discharged, which prevents metal contact between the two solids, and the wear debris always keeps the bearing. It is thought that it plays such a role. From this consideration, it is possible to simultaneously explain the results of FIGS. 5A and 5C in which the wear damage width does not significantly differ even when the vertical contact load changes from 0.98 N to 4.9 N. That is, it is considered that even with a vertical contact load of 4.9 N, the damage that would increase the wear width was not achieved due to the protection of the wear particles existing in the contact portion. On the other hand, when the upper and lower test pieces are the combination of SUS304, it can be inferred that a considerable amount of abrasion powder is generated at the very early stage of sliding friction. From the change of the friction coefficient when the vertical contact load is 0.98 N shown in FIG. 3, it should be judged that the contact state becomes completely different at about 4000 cycles. Similar to the friction coefficient after 5800 cycles when the upper spherical test piece in FIG. 4 is SUJ2 and the vertical contact load is 4.9 N, even when the vertical contact load is 0.98 N in the combination of SUS304 shown in FIG. It is believed that up to 4000 cycles, wear debris generated in the very early stage of friction was present between the two solids in contact, which acted to prevent metal contact between the two solids.

[Brief description of drawings]

FIG. 1 is a front view schematically showing an embodiment of the present invention.

FIG. 2 is a front view showing a conventional friction and wear test device.

FIG. 3 is a graph showing test results obtained by the test apparatus according to the present invention.

FIG. 4 is a graph showing test results obtained by the test apparatus according to the present invention.

FIG. 5 is a graph showing test results obtained by the test device according to the present invention.

FIG. 6 is a graph showing test results obtained by the test apparatus according to the present invention.

[Explanation of symbols]

 1 base 2 and 3 linear bearing 4 first sliding body 5 motor 6 eccentric cam 8 first test piece holding part 9 second test piece holding part 10 second sliding body 12 intermediate member 14 weight holder 15 measuring part

Claims (1)

[Claims] 1. A horizontal support surface provided in a stationary system, a first slide body and a second slide body slidably supported on the support surface in a low friction state, and the first slide body. A drive unit that slides on the support surface, a first test piece holding unit attached to the first slide body, and an intermediate member attached to the second slide body so as to be rotatable about a horizontal axis. A second test piece holding part attached to the intermediate member and holding another test piece in contact with the upper surface of the test piece of the first test piece holding part, and the second test piece holding part from the horizontal axis. On the side, the weight attached to the intermediate member, and the transmission force that is arranged so as to connect the second sliding body and the stationary system and that acts on the second sliding body from the first test piece through the second test piece. A friction and wear test apparatus, comprising: