JP5532957B2 - Friction test apparatus and friction test method - Google Patents

Description

  In the present invention, a sample such as a tire is brought into contact with an ice layer or a compressed snow layer (hereinafter referred to as an icing layer) formed on a tread surface of a rotating body, and relative friction is caused between the sample and the icing surface. The present invention relates to a friction test apparatus and a friction test method for generating a friction test of a sample.

Conventionally, as a friction test apparatus, an icing layer is formed on the inner wall surface of a cylindrical rotating drum provided in a thermostatic bath, and a sample made of a viscoelastic material is brought into contact with the icing layer at a predetermined pressure. There is known an indoor friction test apparatus that performs a friction test of a sample by generating a relative friction with a surface (see, for example, Patent Document 1).
In addition, this type of friction test apparatus includes an ice surface cutting unit that cuts the surface of the ice layer formed on the inner wall surface of the rotating drum into a uniform smooth surface.

JP-A-8-166339

Generally, when testing the on-ice characteristics of a tire using an indoor friction tester, the test is carried out after cutting the surface of the frozen layer into a smooth surface for each tire or for each tire test condition. Yes.
However, the icing surface in the on-ice test on the general road that became an ice burn or on the test course is not the icing surface that has been machined as in the indoor friction test equipment, but is gently formed by various types of tires. It has a frozen surface with an uneven shape.
On the other hand, in the friction test using the indoor friction test apparatus, it is necessary to adjust the contact pressure of the test tire pressed against the surface of the frozen layer to a predetermined load while the rotating drum is rotated. And even during this adjustment, the test tire is rotated multiple times while rubbing against the surface of the frozen layer, and the circumference of the frozen layer is limited. The shape corresponds to the ground plane.
Further, during the test, the surface of the frozen layer is deformed into a shape close to the shape corresponding to the ground contact surface of the test tire following the rotation of the rotating drum.
Therefore, in the indoor type friction test apparatus, the friction test of the test tire is performed on the surface of the icing layer having a shape corresponding to the ground contact surface of the test tire, in other words, the icing having a different shape for each test tire. A friction test of the test tire will be performed on the surface of the layer.
As a result, there is a problem that the accuracy of the friction test is lowered.

  The present invention has been made in view of the above circumstances, and its purpose is to improve friction test accuracy by forming an icing surface that approximates the icing surface of a general road or test course that has become an ice burn. It is an object of the present invention to provide a friction test apparatus and a friction test method that are advantageous for the purpose.

In order to achieve the above object, the present invention is a friction test apparatus, in which a rotating body on which an icing layer is formed to be rotatably supported and pressed against a sample to be tested is formed, and the rotating body is rotated to rotate the rotating body. A rotation drive mechanism for moving the frozen layer integrally with the first load applying mechanism for pressing the sample against the surface of the frozen layer with a predetermined load, a shaped body for shaping the frozen layer, and the shaped body. A second load applying mechanism that presses against the surface of the frozen layer with a predetermined load, and the shaped body contacts the surface of the frozen layer and melts the surface of the frozen layer by frictional heat with the surface. A hardness for shaping the surface of the frozen layer is made of an elastomer having Hs60 to Hs80 .

Further, the present invention is a method for performing a friction test by pressing a sample against the surface of an frozen layer composed of an ice layer or a compressed snow layer, and moving the frozen layer to the surface of the frozen layer. This occurs when a specimen is pressed with a predetermined load, and a shaped body made of an elastomer having a hardness of Hs60 to Hs80 is pressed against the surface of the frozen layer with a predetermined load, and the shaped body is pressed against the surface of the frozen layer. The surface of the frozen layer is melted and shaped by frictional heat.

  According to the friction test apparatus and the friction test method according to the present invention, it is advantageous in improving the accuracy of the friction test because an icing surface similar to the icing surface of a general road or test course that has become an ice burn can be formed. Become.

It is a schematic block diagram of the friction test apparatus 100 in 1st Embodiment. It is sectional drawing which follows the AA line of FIG. (A), (B), (C) is a perspective view which shows the structure of the shaping body 18. FIG. It is a schematic block diagram of the friction test apparatus 100 in 2nd Embodiment. It is sectional drawing which follows the BB line of FIG. (A), (B), (C) is a perspective view which shows the structure of the shaping body 18 in 3rd Embodiment. It is explanatory drawing which shows the structure of the shaping body 18 in 4th Embodiment. It is a perspective view which shows the structure of the shaping body 18 in 5th Embodiment. It is a schematic block diagram of the friction test apparatus 100 in 6th Embodiment. (A) is explanatory drawing which shows the example which applied this invention to the outside drum type friction test apparatus 300, (B) is explanatory drawing which shows the example which applied this invention to the turntable type friction test apparatus 400. It is explanatory drawing which shows the experimental example of the surface property of the frozen layer 24 by this invention method and the conventional method.

(First embodiment)
A first embodiment of a friction test apparatus according to the present invention will be described with reference to FIGS. 1 and 2.
As shown in FIGS. 1 and 2, the inside drum friction test apparatus 100 includes a rotating body 12, a rotating body drive mechanism 14, a first load applying mechanism 16, a shaping body 18, a second load applying mechanism 26, and the like. Consists of.

The rotating body 12 used for the friction test is composed of a cylindrical drum whose one end face is opened and the other end face is closed (hereinafter referred to as a rotating drum).
A support shaft 1204 that coincides with the axis L of the rotary drum 12 is provided at the center of the closed end face wall 1202 of the rotary drum 12 so as to protrude outward from the closed end face wall 1202.
Further, on the inner peripheral wall surface 12a of the rotating drum 12, an icing layer 24 that is a sample to be tested, for example, against which the test tire 22 is pressed is formed. The icing layer 24 is composed of an ice layer having a certain thickness (about 10 mm) obtained by freezing water or a compressed snow layer (about 10 mm thickness). Various conventionally known methods can be employed for forming the icing layer 24.
The rotating drum 12 is housed in a conventionally known temperature-controlled thermostat (not shown).

The rotating body drive mechanism 14 includes a support base 1402 that supports the support shaft 1204 of the rotary drum 12 so as to be rotatable about a horizontal axis that coincides with the axis L of the rotary drum 12.
Further, the rotating body drive mechanism 14 includes a conventionally known rotation driving means 1404 that includes a motor, a speed reducer, and the like that rotate the support shaft 1204 at a required speed, that is, rotate the rotary drum 12 at a required speed. .

The first load application mechanism 16 presses the test tire 22 as a sample to be tested against the surface of the icing layer 24 with a required load. In the present embodiment, the test tire 22 is pressed against the surface of the icing layer 24 with a required load, and the test tire 22 is supported around an axis parallel to the axis L of the rotary drum 12 so as to be rotatable and rotatable. Is.
The first load application mechanism 16 can employ various conventionally known configurations. The first load application mechanism 16 is a conventionally known brake means for braking the test tire 22, and the test tire 22 against the icing layer 24. It includes various conventionally known means necessary for a friction test on the ice of the test tire 22 such as a conventionally known adjusting means for adjusting the contact inclination angle (camber angle) and the slip angle.

The shaped body 18 is pressed against the surface of the icing layer 24, melts the surface of the icing layer 24 by frictional heat with the surface, and the surface of the icing layer 24 becomes an icing surface of a general road or a test course that has become an ice burn. It is for shaping into a close shape.
The shaping body 18 is made of an elastomer.
As such an elastomer, various conventionally known natural rubbers and synthetic rubbers can be employed.
The hardness of the shaped body 18 is preferably Hs60 or more from the viewpoint of melting the surface of the frozen layer 24 with frictional heat. Further, when the shape of the frozen layer 24 has a curvature with respect to the traveling direction, the hardness is preferably Hs80 or less.
When the hardness is less than Hs60, the contact surface of the shaped body 18 follows the same surface shape as the surface shape of the icing layer 24, resulting in a problem that the icing layer surface cannot be shaped as desired. When the frozen layer 24 has a curvature with respect to the traveling direction and the hardness exceeds Hs80, the shape of the shaped body 18 cannot follow the shape of the frozen layer 24. For example, the rod 2610 that supports the shaped body 18 And the axis L of the rotating drum 12 is low in parallel, only a part of the shaped body 18 contacts the surface of the ice layer 24, and the pressure distribution in the direction perpendicular to the traveling direction becomes non-uniform. Occurs.

Various shapes and arrangement structures of the shaped body 18 are conceivable as shown in FIGS. 3 (A), (B), and (C).
3A, 3 </ b> B, and 3 </ b> C, an arrow A indicates a direction in which the shaped body 18 is pressed against the surface of the icing layer 24 with a required load, and an arrow B indicates the moving direction of the icing layer 24. Show.
3A, 3 </ b> B, and 3 </ b> C, the shaping body 18 is held by a holding member 19.
The shaped body 18 shown in FIG. 3A is configured as a single rectangular plate-like portion 1802. The shaped body 18 is attached to the lower surface of a rectangular holding member 1902 having rigidity made of metal or other hard member.
The shaped body 18 shown in FIG. 3B is configured as a plurality of ridges 1804 extending in a direction perpendicular to the moving direction B of the icing layer 24 with an interval in the moving direction B of the icing layer 24. The shaped body 18 is attached to the lower surface of a rectangular holding member 1904 having rigidity made of metal or other hard member.
With this configuration, by reducing the contact area of the shaped body 18 with the surface of the icing layer 24, a higher pressure can be applied to the icing layer 24 with a small load, and the second load applying mechanism 26. This is advantageous in simplifying the configuration.

The shaped body 18 shown in FIG. 3 (C) is configured as a plurality of ridges 1806 extending in the moving direction B of the icing layer 24 at intervals in the direction orthogonal to the moving direction B of the icing layer 24. The shaped body 18 is attached to the lower surface of a rectangular holding member 1906 having rigidity made of metal or other hard member.
With this configuration, as in FIG. 3B, by reducing the contact area of the shaped body 18 with the surface of the frozen layer 24, a higher pressure can be applied to the frozen layer 24 with a small load. it can. Furthermore, the uneven shape formed on the ground contact surface of the test tire 22 can be broken, and uneven portions corresponding to the plurality of protruding portions 1806 can be formed on the surface of the frozen layer 24.

The second load applying mechanism 26 presses the shaped body 18 against the surface of the frozen layer 24 with a predetermined load.
As shown in FIGS. 1 and 2, the second load applying mechanism 26 includes a base 2602, a mounting base 2604, a screw screw 2606, a drive motor 2608, a rod 2610, and the like.
The base 2602 is installed on the floor surface, located on the opening end side of the rotating body 12.
On the base 2602, a mounting base 2604 is supported by a plurality of guide rods 2620 so as to be movable in a vertical direction perpendicular to the axis of the rotary drum 12.
The screw screw 2606 is for moving the mounting table 2604 in the vertical direction. The lower part of the screw screw 2606 is rotatably supported by the base 2602, and the upper part thereof is screwed into a nut 2612 provided on the mounting table 2604. ing.
In addition, a rotating shaft of a drive motor 2608 capable of rotating in the forward and reverse directions is connected to the lower end of the screw screw 2606.

The rod 2610 extends from the mounting table 2604 toward the rotating drum 12 and extends in parallel with the axis L thereof.
One end of the rod 2610 is fixed to an attachment member 2622 provided on the mounting table 2604, and the holding member 19 that holds the shaping body 18 is connected to the other end.
The second load applying mechanism 26 includes a load sensor (not shown) such as a load cell that measures the load on the surface of the frozen layer 24 of the shaped body 18. This load sensor is provided, for example, at a contact location between the mounting member 2622 and the rod 2610.
Therefore, the shaping body 18 moves away from the surface of the frozen layer 24 via the screw screw 2606, the guide rod 2620, the mounting table 2604, the mounting member 2622, the rod 2610, and the holding member 19 by forward and reverse rotation of the drive motor 2608. Moved.
Therefore, the second load applying mechanism 26 includes a first moving mechanism that moves the shaping body 18 in a direction in which the shaping body 18 moves away from and approaches the surface of the frozen layer 24. And the load by which the shaping body 18 is pressed against the surface of the frozen layer 24 is adjusted by controlling the movement amount of the shaping body 18.
In addition, the structure of the 2nd load provision mechanism 26 is not limited to embodiment, Various conventionally well-known structures are employable.

Next, the operation of the friction test apparatus shown in this embodiment will be described.
First, the test tire 22 is held by the first load applying mechanism 16 and positioned in the rotating drum 12, and the shaping body 18 held by the second load applying mechanism 26 is positioned in the rotating drum 12.
Next, the test tire 22 is pressed against the surface of the frozen layer 24 by the first load applying mechanism 16 with a predetermined load.
Further, the mounting table 2604 is lowered, and the shaped body 18 is pressed against the surface of the icing layer 24 with a predetermined load by the second load applying mechanism 26.
In this case, the contact pressure (load) that presses the shaped body 18 against the surface of the icing layer 24 makes the unevenness formed on the surface of the icing layer 24 by the test tire 22 gentle, so that the test is performed on the surface of the icing layer 24. It is preferable to be equal to or greater than the maximum ground pressure (load) for pressing the tire 22. For example, it is preferably about 1 to 1.5 times the maximum ground pressure for pressing the test tire 22 against the surface of the frozen layer 24.
When the ground contact pressure for pressing the shaped body 18 against the surface of the frozen layer 24 is smaller than the maximum ground pressure for pressing the test tire 22 against the surface of the frozen layer 24, the surface of the frozen layer 24 is gently uneven by the shaped body 18. It is difficult to shape. Further, when the ground contact pressure that presses the shaped body 18 against the surface of the icing layer 24 exceeds 1.5 times the maximum ground pressure that presses the test tire 22 against the surface of the icing layer 24, This is because the amount of wear (the amount dissolved by heat and lost) increases.
In this state, the rotary drum 12 is rotated at a required speed by the rotation drive mechanism 14, and the test tire 22 is rotated by the first load applying mechanism 16 at the required rotation speed.

In the friction test of the test tire 22, for example, the rotating drum 12 and the test tire 22 are rotated at the same speed, and the test tire 22 is braked while rotating the rotating drum 12 at a constant speed, and the rotation speed is gradually increased. Slow down. Alternatively, the rotating drum 12 and the test tire 22 are rotated at the same speed, and the test tire 22 is driven and the rotational speed thereof is gradually accelerated while the rotating drum 12 is rotated at a constant speed.
In this case, since the test tire 22 is pressed in a slip state, when the shaped body 18 is not present, the surface of the frozen layer 24 is shaved by the uneven portion (tread pattern) of the test tire ground contact surface, and the shape of the uneven shape is determined. Grooves are formed. Accordingly, the friction test of the test tire 22 is performed on the surface of the frozen layer 24 having a different shape for each test tire 22, and the accuracy of the friction test is lowered.
On the other hand, in the first embodiment, since the shaped body 18 is pressed against the surface of the icing layer 24 by the second load applying mechanism 26 with a predetermined load, the shaped body 18 was shaved on the ground contact surface of the test tire 22. The concavo-convex shape is melted by frictional heat with the shaped body 18 and shaped into a gentle concavo-convex shaped icing surface.
Therefore, the surface of the icing layer 24 is shaped into a shape close to the icing surface of a general road or test course that has become an ice burn.
Therefore, even if the test tires 22 are different, the friction test of the test tire 22 is performed on the surface of the ice layer 24 having a substantially uniform shape, and the friction test is performed on the surface of the ice layer 24 having a different shape for each test tire 22. The accuracy of the friction test is improved.

  Further, in the first embodiment, the shaped body 18 can be moved to the surface of the icing layer 24 detachably by the second load applying mechanism 26. Therefore, when shaping of the surface of the frozen layer 24 by the shaped body 18 is unnecessary, for example, the shaped body 18 can be separated from the surface of the frozen layer 24 immediately after the friction test of the test tire 22 is completed. This is advantageous in reducing wear.

(Second Embodiment)
A second embodiment of the friction test apparatus according to the present invention will be described with reference to FIGS.
In the following embodiments, the same or corresponding parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted or simplified, and is different from the first embodiment. Will be described in detail.
The inside drum friction test apparatus 200 shown in the second embodiment is similar to the first embodiment in that the rotating body 12, the rotating body drive mechanism 14, the first load applying mechanism 16, the shaping body 18, It is comprised including the 2 load provision mechanism 26 grade | etc.,.

In the second embodiment, the configuration of the second load applying mechanism 26 is different from that of the first embodiment.
That is, the second load applying mechanism 26 of the second embodiment includes the first moving table 2630 disposed on the mounting table 2604 so as to be movable in the horizontal direction perpendicular to the axis L of the rotating drum 12. I have.
The attachment member 2622 is disposed on the first moving table 2630 so as to be movable in a direction parallel to the axis L of the rotary drum 12.
The mounting table 2604 is moved up and down by a guide rod 2620, a screw screw 2606, a drive motor 2608, and the like.

The first moving table 2630 is moved in the horizontal direction perpendicular to the axis L of the rotary drum 12 by a guide and drive motor 2632 (not shown).
Therefore, also in the second embodiment, the second load applying mechanism 26 is configured to include a first moving mechanism that moves the shaping body 18 in the direction of separating and approaching the surface of the frozen layer 24. And the load by which the shaping body 18 is pressed against the surface of the frozen layer 24 is adjusted by controlling the movement amount of the shaping body 18.
The attachment member 2622 is moved in the horizontal direction parallel to the axis L of the rotary drum 12 by the screw screw 2634, the drive motor 2636, and the guide groove 2630A of the first moving table 2630, and the shaped body 18 follows the movement. It is moved in the horizontal direction parallel to the axis L of the rotary drum 12.
Therefore, the second load applying mechanism 26 includes a second moving mechanism that reciprocally moves the shaped body 18 in a direction intersecting with the moving direction of the icing layer 24 (a direction orthogonal in this embodiment). By this second moving mechanism, the shaped body 18 is reciprocated in a direction intersecting the moving direction of the frozen layer 24 in a state where the shaped body 18 is pressed against the surface of the frozen layer 24, and along the axis L of the rotary drum 12. The surface of the icing layer 24 can be shaped by the shaping body 18 in the entire width direction.
That is, according to the second embodiment, in addition to the effects of the first embodiment, the shaped body 18 shorter than the length in the width direction of the frozen layer 24 parallel to the axis L of the rotary drum 12 can be used. The effect is that the entire surface of the icing layer 24 can be shaped.

(Third embodiment)
Next, a third embodiment will be described with reference to FIG.
In the first and second embodiments, the load sensor for detecting the load of the shaping body 18 to be brought into contact with the surface of the icing layer 24 is provided at the contact portion between the mounting member 2622 and the rod 2610. In the embodiment, the load sensor 30 is provided on the shaped body 18.
As the load sensor 30, for example, various conventionally known sensors such as a load sensor can be used. FIGS. 6A, 6B, and 6C show the load sensor 30 as shown in FIGS. The example provided in the shaping body 18 shown to (C) is shown.
The load sensor 30 is arranged between the holding member 19 and the shaping body 18 so as to be located in the entire area where the shaping body 18 is arranged.
By providing the load sensor 30 on the shaped body 18, the load of the shaped body 18 on the surface of the frozen layer 24 can be accurately detected.
Therefore, the load control applied to the shaped body 18 by the second load applying mechanism 26 based on the detection result of the load sensor 30 can be reliably performed, which is advantageous in improving the accuracy of the friction test of the test tire 22. .

(Fourth embodiment)
Next, a fourth embodiment will be described with reference to FIG.
The fourth embodiment is different from the first embodiment in the configuration and arrangement of the shaping body used in the friction test apparatus of the present invention.
In the fourth embodiment, a plurality of shaped bodies 1810, 1812, 1814, and 1816 are arranged along the moving direction B of the surface of the frozen layer 24.
Each of the shaped bodies 1810, 1812, 1814, and 1816 has different surface roughnesses in contact with the surface of the icing layer 24, and the surface roughness indicates the moving direction of the surface of the icing layer 24 as shown in FIG. It arrange | positions so that it may become small gradually along B.

According to the fourth embodiment, the frozen layer 24 is roughly shaped at first by each shaped body 1810, 1812, 1814, 1816, and gradually shaped finely.
Therefore, it is advantageous in stabilizing the surface properties of the icing layer 24 and advantageous in improving the friction test accuracy of the test tire.
In this case, in order to further stabilize the surface properties of the frozen layer 24, the surface roughness of each shaped body 1810, 1812, 1814, 1816 is the same, and the frozen layer 24 of each shaped body 1810, 1812, 1814, 1816 has the same surface roughness. It is optional to change the pressure on the surface or to change the shape and size.
That is, in the present invention, in order to further stabilize the surface properties of the frozen layer 24, a plurality of shaped bodies 1810, 1812, 1814, 1816 are arranged along the moving direction B of the surface of the frozen layer 24, and each shaped body 1810 is arranged. , 1812, 1814, 1816, the surface roughness of each shaped body 1810, 1812, 1814, 1816 on the surface of the icing layer 24, and the shape and size of each shaped body 1810, 1812, 1814, 1816 Is optional.

(Fifth embodiment)
Next, a fifth embodiment will be described.
The fifth embodiment relates to temperature control of the shaped body used in the friction test apparatus of the present invention.
The temperature of the surface of the icing layer 24 after contact of the test tire 22 may vary depending on the test tire 22 depending on the properties of the test tire 22. In such a case, the icing layer 24 having a different temperature for each test tire 22. As a result, a friction test is performed on the surface of the metal and the test accuracy is lowered.
Therefore, in the fifth embodiment, as shown in FIG. 8, the shaped body 18 is provided with temperature adjusting means 32 for adjusting the temperature of the shaped body 18.
Thus, by adjusting the temperature of the shaped body 18 by the temperature adjusting means 32, the temperature of the surface of the frozen layer 24 can be adjusted, so that the friction test can be performed on the surface of the frozen layer 24 having a uniform temperature. This is advantageous in improving the accuracy of the friction test of the test tire 22.
As such a temperature adjusting means 32, conventionally known various temperature regulators including heating and cooling such as a heater that generates heat when current is supplied can be used. The shaped body 18 can be embedded and disposed.

(Sixth embodiment)
Next, a sixth embodiment will be described.
FIG. 9 shows the friction test apparatus 100 shown in FIGS. 1 and 2 provided with a water absorption mechanism 34.
The water absorption mechanism 34 is formed by moisture generated by melting the surface of the freezing layer 24 by frictional heat between the surface of the freezing layer 24 and the shaped body 18, or by freezing frictional heat between the surface of the freezing layer 24 and the test tire 22. It absorbs moisture generated by melting the surface of 24.
As such a water absorption mechanism 34, various types of conventionally known structures such as a non-contact vacuum type, or a felt or cloth using a contact with the surface of the icing layer 24 can be used.

It is preferable that the place where the water absorption mechanism 34 is arranged varies depending on the temperature and ice temperature.
That is, when the temperature and ice temperature are relatively high temperatures of about 0 ° and −1 °, a large amount of moisture is generated due to friction between the surface of the frozen layer 24 and the test tire 22.
In this case, a water absorption mechanism 34 is disposed at a position behind the test tire 22 and in front of the shaped body 18 in the rotation direction of the rotary drum 12.
Thereby, a lot of moisture generated by the friction of the test tire 22 is surely absorbed, and moisture reaching the shaped body 18 is suppressed, so that the shaping of the surface of the frozen layer 24 by the shaped body 18 is stabilized.
On the other hand, when the temperature and ice temperature are relatively low such as −5 degrees and −6 degrees, moisture is generated due to friction between the surface of the frozen layer 24 and the shaped body 18.
In this case, as shown in FIG. 9, a water absorption mechanism 34 is disposed at a location behind the shaped body 18 and in front of the test tire 22 in the rotational direction of the rotary drum 12.
Thereby, the water | moisture content generated by the friction of the shaping body 18 is absorbed reliably, the water | moisture content which reaches the test tire 22 is suppressed, and the precision of the friction test of the test tire 22 is raised.

In the present invention, a tire having no groove on the tread surface can be used as the shaping body 18.
In this case, the second load application mechanism 26 may have the same configuration as the first load application mechanism 14 that is the load application mechanism of the test tire 22.
Further, as shown in FIG. 10 (A), the shaped body 18 of the present invention is an outside drum type friction test apparatus in which an icing layer 24 is formed on the outer peripheral surface of the rotary drum 12 centered on the horizontal axis L. 300 and other conventionally known various types such as a turntable friction test apparatus 400 in which an icing layer 24 is formed on a turntable 40 that rotates about a vertical axis L1 as shown in FIG. Applicable to various friction test equipment.
In the embodiment, the case where the sample used for the friction test is a tire has been described. However, in the present invention, the sample is not limited to the tire, and various other types such as a tire tread compound and a rubber piece made of a viscoelastic material. Applicable to various test specimens.

(Experimental example)
Next, an experimental example of the surface properties of the frozen layer 24 according to the method of the present invention and the conventional method will be described with reference to FIG.
The friction test apparatus used in this experimental example is an inside drum type tire friction tester, in which an icing layer 24 is formed on the inner wall surface of the rotating drum and the shaped body 18 of the present invention is used, A comparison was made with the conventional method when the shaped body 18 of the present invention is not used.
The air temperature and the surface temperature of the frozen layer 24 are −5 ° C.
The tire 22 used for the friction test is 195 / 65R15, rim width: 61/2, and air pressure: 200 kPa.
The experimental procedure is performed in the following order (1) to (6).
(1) The surface of the icing layer 24 is cut with a cutter to form a smooth cylindrical icing surface without irregularities. At this time, the ice surface property in a direction parallel to the axial center of the surface of the cylindrical ice layer 24 is measured.
(2) The rotating drum is rotated so that the speed of the surface of the frozen layer 24 is 37 km / h.
(3) The tire is brought into contact with the surface of the frozen layer 24 having a speed of 37 km / h, the load applied to the tire is set to 3.0 kN, and the tire is allowed to run for 5 minutes in a free rolling state.
(4) After running the tire at a speed of 35 km / h (slip rate is about 5.4%) for 2 minutes, the tire is separated from the surface of the frozen layer 24.
(5) Stop the rotation of the rotating drum, and measure the properties of the cylindrical frozen surface after the tires contact in the slip state.
(6) The difference between the ice surface property measured in (1) and the ice surface property measured in (5) is obtained.
In FIG. 11, the broken line indicated by reference sign S0 indicates the reference position of the surface of the icing layer 24 formed in step (1), that is, 0 mm, and the positions recessed by 1 mm and 2 mm from the reference position are respectively broken lines. 1 and a broken line 2.

The result of the experiment performed in the above procedure will be described with reference to FIG.
When the experiment is performed according to the procedures (1) to (6) without using the shaped body 18 of the present invention, the surface of the frozen layer 24 is in contact with the tire 22 as shown in FIG. An uneven shape 50 corresponding to the unevenness 22a (tread pattern) on the ground was formed. That is, the friction test of the test tire 22 is performed on the surface of the frozen layer 24 having a different shape for each test tire 22.
On the other hand, the shaped body 18 made of a rubber plate having a thickness of 10 mm and a hardness of Hs70 is used, and the load of the shaped body 98 on the surface of the frozen layer 24 is set to 1.2 times the load of the tire. When the experiment was performed according to the procedures (1) to (6), the surface of the icing layer 24 was shaped into a concavo-convex icing surface as shown in FIG.
That is, even if the test tires 22 are different, the friction test of the test tire 22 is performed on the surface of the ice layer 24 having a substantially uniform shape, and the ice freeze having a shape close to the ice surface of the general road or the test course that has become an ice burn. A friction test will be performed on the surface of layer 24.

  DESCRIPTION OF SYMBOLS 12 ... Rotating body, 14 ... Rotating body drive mechanism, 16 ... 1st load application mechanism, 18 ... Shaped body, 22 ... Test tire, 24 ... Freezing layer, 26 ... 2nd load application mechanism, 32 ... Temperature adjusting means, 34 ... Water absorption mechanism, 40 ... Turntable, 100,200 ... Inside drum friction tester, 300 ... Outside drum friction tester, 400 ... Turntable friction test apparatus.

Claims (14)

A rotating body on which an icing layer is formed that is rotatably supported and pressed against a sample to be tested;
A rotation drive mechanism for rotating the rotating body and moving the frozen layer integrally with the rotating body;
A first load application mechanism for pressing the sample against the surface of the frozen layer with a predetermined load;
A shaped body for shaping the frozen layer;
A second load applying mechanism that presses the shaped body against the surface of the frozen layer with a predetermined load;
The shaped body is made of an elastomer having a hardness of Hs60 to Hs80 that contacts the surface of the frozen layer and melts the surface of the frozen layer by frictional heat with the surface to shape the surface of the frozen layer.
A friction test apparatus characterized by that. A second load applying mechanism, wherein the first load applying mechanism presses the shaped body against the surface of the frozen layer with a load equal to or greater than a load pressing the sample against the surface of the frozen layer;
The friction test apparatus according to claim 1. The large load is more than 1 time and not more than 1.5 times the load by which the first load applying mechanism presses the sample against the surface of the frozen layer.
The friction test apparatus according to claim 2. The shaped body is friction test apparatus of any one claim 1 to 3, characterized in that it is formed as a plurality of convex portions spaced from each other. The friction test apparatus according to claim 4 , wherein the protrusions extend in a moving direction of the frozen layer and are arranged in a direction perpendicular to the moving direction of the frozen layer. 5. The friction test apparatus according to claim 4 , wherein the protrusions extend in a direction orthogonal to a moving direction of the frozen layer and are arranged in the moving direction of the frozen layer. A plurality of the shaped bodies are provided,
The plurality of shaped bodies are different from each other in surface roughness of the surface in contact with the surface of the frozen layer,
Either each shaping body to claims 1 to 6, characterized in that arranged along the moving direction of the frozen layer to be pressed against the frozen layer in the order of smaller from the largest of the surface roughness 1 The friction test apparatus according to item.   The friction test apparatus according to claim 1, wherein a tire having no groove in a tread portion is used as the shaping body. The said 2nd load provision mechanism is comprised including the 1st movement mechanism which moves the said shaping body in the direction which spaces apart and approaches the surface of the said freezing layer, The any one of Claim 1 thru | or 8 characterized by the above-mentioned. The friction test apparatus according to item. The said 2nd load provision mechanism is comprised including the 2nd moving mechanism which reciprocates the said shaping body in the direction which cross | intersects the moving direction of the said freezing layer, The any one of Claim 1 thru | or 9 characterized by the above-mentioned. The friction test apparatus according to item 1. The friction test apparatus according to any one of claims 1 to 10 , further comprising a water absorption mechanism that absorbs moisture generated on a surface of the frozen layer. The friction test apparatus according to any one of claims 1 to 11 , wherein the shaped body is provided with temperature adjusting means for adjusting a temperature of the shaped body. A method in which a sample is pressed against the surface of an ice layer or a frozen layer consisting of a compressed snow layer to perform a friction test,
Moving the frozen layer;
Press the sample with a predetermined load on the surface of the frozen layer,
Pressing a shaped body made of an elastomer having a hardness of Hs60 to Hs80 to the surface of the frozen layer with a predetermined load,
Melting and shaping the surface of the frozen layer with frictional heat generated when the shaped body is pressed against the surface of the frozen layer;
A friction test method characterized by the above. The friction test method according to claim 13 , wherein a load pressing the shaped body against the surface of the frozen layer is equal to or greater than a load pressing the sample against the surface of the frozen layer.

Images