JP2987742B2 - Friction test equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction test apparatus for a viscoelastic material such as rubber, and more particularly, to a thermostat using a specimen as a tire constituent material without producing various tires for trial operation. The present invention relates to an improvement in a friction test device that can obtain the same effect as a friction test of a prototype tire by performing a friction test on ice or a wet road surface in a rotating drum provided in a tank.

[0002]

2. Description of the Related Art Conventionally, a friction test apparatus for a viscoelastic material such as a tire is a slip resistance type friction test apparatus for performing a friction test by sliding a sample made of a viscoelastic material against a friction surface, or Japanese Patent Publication No. As disclosed in JP-A-10062, a pin-on-desk type friction test apparatus is mainly used, and as disclosed in Japanese Patent Publication No. 3-63012, a friction test apparatus on a road is proposed as a rotary type. Have been.

Further, as a recent friction test apparatus, an apparatus for performing a friction test by bringing a sample into contact with an inner wall surface of a cylindrical rotating drum has been proposed (Kautsch und Gummi Vol. 2).
2, P373, (1969)). However, such conventional friction test apparatuses are mainly based on slip resistance, which is measured while sliding a sample against a friction surface.
When performing a friction test on a tire, friction data of a friction test based on slip resistance had to be used despite the rolling resistance, which was different from the actual use conditions.

[0004] In addition, the evaluation road test of studless tires and all-season tires, the test on a test course, and the like, utilize an indoor tire test apparatus for snowy and icy roads. An ice layer having a predetermined thickness is formed on the inner wall surface of the rotating drum installed in the tank, and a prototype of a snow and ice road tire to be actually used is mounted on the inner surface side of the rotating drum, and the rotating drum is rotated. This is a device that performs a friction test of a prototype while doing so (Transactions of the Society of Automotive Engineers of Japan, N038, P71, (198)
8)).

In general, when conducting a friction test on a tire, evaluation of the material constituting the tire itself is important as a screening test before trial production of the tire. It is done using tires,
Not only the evaluation of the tire constituent material itself, but also the evaluation as a selection test of the constituent material is an expensive test.In the case of the conventional device as described above, the slip resistance is mainly used as described above. Not a rotary type that simulates the running of actual tires, but a lot of labor and time, and a lot of cost, because many types of tire prototypes must be manufactured and performed. was there.

[0006] In order to solve such a conventional problem, the applicant of the present application has filed a statement on January 28, 1993 (Japanese Patent Application No.
No. 12906, Japanese Patent Application Laid-Open No. 6-221990), when performing a friction test on a viscoelastic material,
A friction test can be easily simulated by using a sample of a variety of products without having to manufacture a prototype of the product to be actually used.This greatly reduces the time and effort required for product prototypes. We have proposed a friction test device that can reduce costs as well as being able to do so.

[0007]

However, according to the invention of the applicant of the present invention, the material of the rotating drum in the above invention is preferably a lightweight and non-rusting metal, and the rotating drum is rotated at a high speed. Considering the correction of the uniformity of the rotating drum in the case of doing, it is difficult to correct the uniformity with the rotating drum made of glass as described above,
Further, in consideration of the centrifugal force and inertia force, and further the price, durability and life-span, it has been found that a metal rotary drum is the best.

The present invention relates to the improvement of the above-mentioned invention of the applicant of the present invention, in which a sample piece as a tire constituent material is pressed on the inner wall surface of a rotating drum provided in a constant temperature bath, and the sample is pressed on ice or wet. The purpose of the present invention is to provide a friction test device that performs a friction test on a road surface and enables a long-term operation, particularly during a test on ice, reduces vibration of a rotating drum, and improves measurement accuracy of a friction force. Is what you do.

[0009]

According to the present invention, in order to achieve the above object, a hollow cylindrical rotary drum made of a metal material is rotated via a driving device inside a thermostat provided with a refrigerating device and a heating device. A sample holder unit which is freely mounted and has a disk-shaped sample rotatably and detachably mounted at the tip thereof in the rotary drum, and the sample rotatably mounted on the sample holder unit is provided on an inner wall surface of the rotary drum. A torque meter is provided in the vicinity of the sample in the rotary drum, which is covered with a cover made of a heat insulating and waterproof material, in the vicinity of the sample in the rotary drum, and ice formed on the inner wall surface of the rotary drum is provided. The gist is that an ice surface cutting unit that cuts the surface into a uniform and smooth surface, and an ice surface cutting and cleaning device that collects the ice chips cut by this ice surface cutting unit and discharges it to the outside of the thermostat are provided. Is shall.

The rotating drum is formed of a lightweight, non-rusting metal material such as aluminum, stainless steel, duralumin, and the like, and the ice surface cutting and cleaning device collects ice chips on the ice surface at one end of the rotating drum. It comprises a cleaning blade and a vacuum device for discharging the collected ice shavings out of the thermostat. In addition, a fan inside the thermostat provided with a refrigerating device and a heating device is provided with a fan inside the bath that can control the number of rotations and the direction of rotation when freezing or defrosting the bath.

[0011]

The present invention is constructed as described above. For example, when simulating friction on ice or wet road surfaces such as studless tires and all-season tires, a product is placed in a rotating drum provided inside a thermostat. With the tire test piece set and the sample pressed against the inner wall surface of the rotating drum, defrosting is performed by controlling the fan inside the tank, enabling long-term operation during ice tests. , It is possible to evaluate on the ice surface of the same quality.

Further, by keeping the temperature of the torque meter constant and the temperature constant, it is possible to improve the measurement accuracy of the frictional force, and to remove ice chips from the ice surface formed on the inner wall surface of the rotating drum. By providing a cutting and cleaning device, the workability of cutting the ice surface can be improved.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 is a longitudinal sectional front view of a friction test apparatus showing an embodiment of the present invention, FIG. 2 is a partially enlarged sectional view taken along the line AA of FIG. 1, and FIG. 3 is a partially enlarged view taken along the line BB of FIG. FIG. 3 shows a cross-sectional view, wherein the friction test device is provided with a refrigerating device 10A and a heating device 10B on the upper part, and is capable of temperature adjustment (−20 ° C. to 40 ° C.).
A hollow cylindrical rotary drum 3 is rotatably mounted via a plurality of bearings 2 in a substantially central portion of a constant temperature chamber 1 having a constant temperature (° C.).

The cylindrical rotary drum 3 is made of a lightweight, rust-resistant and highly heat-conductive metal material such as aluminum, stainless steel or duralumin, and has a uniform thickness (about 10 mm) on its inner surface. An ice layer or an aqueous layer can be formed. A drum holding bearing 4 for rotation transmission is attached to an outer peripheral surface on one end side of the rotary drum 3, and the drum holding bearing 4 for rotation transmission,
A drive shaft 5 for rotational drive installed on the upper part of the thermostat 1
A timing belt 7 is wound around a timing pulley 6 attached to the rotary drum 3, and the rotary drum 3 is driven to rotate.

On one side of the thermostat 1, there is provided an opening / closing door 8 provided with a glass window 8a having a double structure so that the rotating drum 3 inside can be seen through. As shown in FIG. 3, an opening / closing door 8a for attaching and detaching a sample W to and from a sample holder unit 11, which will be described later.
Is provided. A thermostat 1 is provided inside the rotating drum 3.
A guide rail 10 penetrating through the hollow portion of the rotary drum 3 via supporting legs 9a and 9b provided at the bottom of the sample holder, and a sample holder unit 11 for detachably attaching a sample W to a tip of the guide rail 10 is mounted on the guide rail 10. The provided base plate 12 is slidably mounted.

The guide rail 10 is provided with a water supply means (not shown) for supplying a fixed amount of water to the inner wall surface of the rotating drum 3 when an ice layer is formed on the inner wall surface of the rotating drum 3. The water supply means is connected to a water supply source outside the thermostat 1. As shown in FIG. 1 to FIG. 4, the base plate 12 is provided with a feed screw rod 14 at the tip through an opening 13 formed on a side surface of the thermostat 1.
The nut 16 provided on the base plate 12 is screwed into the feed screw rod 14.

Accordingly, when the rotating shaft 15 is driven to rotate, the base plate 12 provided with the sample holder unit 11 moves right or left along the guide rail 10 via the nut 16 screwed onto the feed screw rod 14. Is what you do. As shown in FIG. 1, a rotating shaft 15 protruding outward from an opening 13 formed on a side surface of the thermostat 1 is connected to a sample moving shaft 19 supported on a bearing 18 via a coupling 17, The sample moving shaft 19 is provided with a clutch 20.

A servo motor 21 is provided below the sample moving shaft 19, and a drive shaft 24 supported by a bearing 23 via a coupling 22 is mounted on a motor shaft 21a of the servo motor 21. It is installed in parallel with 19. The drive shaft 24 and the sample moving shaft 19 are connected to the low-speed pulleys 25a and 25b and the high-speed pulleys 25a 'and 2 respectively.
5b 'is attached, and the low-speed pulleys 25a, 25b and the high-speed pulleys 25a', 25b 'are connected via pulley belts 26a, 26b, and the drive shaft 24 is connected to a low-speed clutch 27a and a high-speed clutch 27a. Clutch 27
b.

The tip of the drive shaft 24 and the sample moving shaft 19
Means the drive pulley 2 provided via the clutch 27c.
8a and a tension pulley 28 are attached, respectively. The drive pulley 28a and the tension pulley 28 have a toothed belt on a transmission pulley 28c provided on a rotary drive shaft 5 installed above the constant temperature bath 1. 29 are interlocked. The drive shaft 5 for rotational drive includes:
The drive shaft 5 is provided with a coupling 30 so as to be rotatable on the upper part of the thermostat 1 via a bearing 5 a.

The clutch 20 provided on the sample moving shaft 19 and the low speed clutch 27 provided on the drive shaft 24 are provided.
a, a high-speed clutch 27b, a clutch 27c, and a coupling 30 provided on the drive shaft 5. Next, as shown in FIGS. 4 to 6, the sample holder unit 11 provided on the base plate 12 is provided with a hollow vertical movement screw 32 that penetrates a gear box 31. It is attached to the tip of a support shaft 33 inserted through the center.

The vertically moving screw 32 is spline-fitted to an outer cylinder 34 rotatably provided in the gear box 31 via a bearing. Note that a ball spline shaft may be used as the vertical movement screw 32. A worm wheel 35 is provided integrally with the outer cylinder 34, and a worm gear 37 connected to a drive motor 36 as shown in FIG. Accordingly, when the worm gear 37 is rotationally driven via the drive motor 36, the outer cylinder 34 integrally provided with the worm wheel 35 is rotated, and the vertically moving screw 32 meshed within the outer cylinder 34 is moved up and down in the axial direction. It is configured to be.

In the sample holder unit 11 attached to the tip of the support shaft 33, a holder support plate 38 is horizontally fixed to the tip of the support shaft 33, and a plurality of base plates 39 of the sample holder unit 11 are mounted on the holder support plate 38. It is detachably attached via the bolt 40 of the. As shown in FIGS. 1 and 6, a support frame 41 having a U-shaped cross section is suspended from the base plate 39 of the sample holder unit 11.
A sample W is clamped via a collar 43 to a sample mounting shaft 42 rotatably provided in a bearing 1 via a bearing 42a.
One end of the sample mounting shaft 42 is fastened and fixed via a washer 44 and a bolt nut 45.

The sample holder unit 11 includes a support frame 41 suspended from the base plate 39 and having a U-shaped cross section.
A sample mounting shaft 42 provided on the support frame 41,
The sample W clamped and fixed to the sample mounting shaft 42 is 1
It is configured as one unit, and is used by replacing each unit. A guide rod 46 is erected on one side of the holder support plate 38 attached to the tip of the support shaft 33. The guide rod 46 penetrates the gear box 31 and has a support plate 47 at its upper end.
Is mounted horizontally.

An upper end of a support shaft 33 inserted through the center of the vertically moving screw 32 is fixed to the support plate 47, and a screw rod 48 is formed on an upper end of the support shaft 33 protruding from the support plate 47. A plurality of weights G for urging the sample W with a predetermined weight on the inner surface of the rotary drum 3 are detachably attached to the screw rod 48, and are configured to be fastened and fixed via nuts 49. I have.

In place of the unitized sample holder unit 11, an ice formed on the inner surface of the rotary drum 3 as shown in FIG. An ice surface cutting unit 50 for cutting the surface of the layer Ax into a uniform smooth surface is used. In this ice surface cutting unit 50, a tool holder 52 is attached via a bolt 53 to a support frame 51 having a U-shaped cross section suspended from a base plate 39, and a cutting bead 54 is provided with a screw 56 on the tool holder 52. It is attached detachably through the.

As shown in FIGS. 1 and 6 to 8, the sample mounting shaft 42 constituting the sample holder unit 11 is connected to one end of the sample mounting shaft 42 protruding from the support frame 41 via a universal joint 57. A rotation shaft 58 is connected, and one end of the sample rotation shaft 58 and one end of a motor shaft 60 of a drive motor 59 (servo motor) described later are spline-coupled via spline shafts 61a and 61b.

The other end of the motor shaft 60 is
As shown in the figure, a coupling 68, a clutch 66,
The drive motor 59 is connected to a torque meter 63 connected via a brake 67 and a coupling 68.
The torque meter 63 is configured to be covered with a cover 65 made of a heat insulating and waterproofing material 64 in order to prevent fluctuation and water wetting based on a temperature change of the thermostat 1.

The driving motor 59 and the driving motor 36
When provided inside the thermostat 1, it is necessary to cover it with a cover 65 made of a heat insulating and waterproofing material 64 as shown in FIGS. 7 and 8. It is not necessary to provide the cover 65 made of the heat insulating and waterproofing material 64 as long as the cover 65 is formed. Next, as shown in FIGS. 5 and 9, an ice surface cutting and cleaning device 70 for removing ice chips from the ice surface formed on the inner wall surface of the rotary drum 3 is provided in the rotary drum 3.

The ice surface cutting and cleaning apparatus 70 is used for cutting the surface of the ice layer formed on the inner surface of the rotary drum 3 into a uniform and smooth surface by the cutting dies 54 of the ice surface cutting unit 50. It collects and efficiently discharges debris to the outside of the thermostat 1, and is configured as follows.
That is, as shown in FIG. 9, the ice surface cutting and cleaning device 70 has support plates 71a and 71b erected on both sides of the rotary drum 3 and is rotatably supported by the support plates 71a and 71b via the pins 72. A creeling blade 74 slidably in contact with the inner wall surface of the rotating drum 3 is attached to the guide plate 73.

5 and 9, the creeping blade 74 extends in the longitudinal direction of the rotating drum 3 so as to collect ice chips toward a vacuum nozzle 75 provided on the inner surface at one end of the rotating drum 3. As shown in FIG. The vacuum nozzle 75 is provided with a vacuum device 77 installed outside the thermostat 1 through a vacuum pipe 76.
(Suction pump).

The cutting blade 54 of the ice surface cutting unit 50 causes the rotating drum 3 to rotate.
It is used only for cutting the surface of the ice layer formed on the inner surface of the slab. In other cases, the grip 78 prevents free rotation of the creeling blade 74.
As shown in FIGS. 1 to 3, a refrigeration unit 10 </ b> A and a heating unit 10 </ b> B provided at the upper part of the thermostat 1 are provided at the upper part of the thermostat 1 with a flow passage 81 through which the air of the thermostat 1 circulates. A chamber 82 is defined at the lower portion, and a refrigerator 8 is provided in the chamber 82.
3 and a heater 84 used at the time of defrosting are incorporated.

A plurality of in-tank fans are provided in the flow passage 81. The in-tank fans are cooled by a forward rotation fan, a reverse rotation fan 85 and a forward rotation fan 86 (stirring fan) used for defrosting. A pair of two normal rotation fans 87a and 87b (circulation fans) for circulating the air in the thermostat 1 are installed in parallel. A pair of two forward fans 87a, 8;
7b is a drive motor 89 installed above the thermostat 1.
a, 89b and 90a, 90b. The drive motors 89a, 89b and 90a, 90b change the frequency by operating buttons provided on a control panel (not shown) installed outside the thermostat 1, and the rotation speed is changed. Is controlled.

When the refrigerator 83 is driven to form an ice layer on the inner surface of the rotating drum 3, the flow of the cool air is caused by the rotation of the normal rotation fans 87a and 87b as shown by the arrow Q in FIG. The cool air is blown out from the upper part and the side part of the rotating drum 3 through the inside of the flow passage 81, and the cool air flows in from one of the rotating drums 3, flows to the other, returns to the refrigerator 83, and circulates again. The temperature in the thermostat 1 and the thickness of the ice layer formed on the inner wall surface of the rotating drum 3 can be arbitrarily set by controlling the refrigerator 83.

If the refrigerator 83 has been driven for a long time, frost adheres to the refrigerator 83 and the refrigerating function deteriorates. Therefore, the refrigerator 83 is periodically stopped, and the heater 84 and the forward and reverse rotations are performed. The defrosting is performed by rotating the fan 85 and the normal rotation fan 86. At the time of defrosting, the normal rotation and the reverse rotation fan 85 are reversely rotated, and one of the normal rotation fans 86 is rotated forward, so that the air flow Qa
Circulates and efficiently defrosts the refrigerator 83 as shown in FIGS. In this case, the circulation normal rotation fans 87a and 87b stop.

By the way, when the temperature in the thermostat 1 is -7.degree.
Defrosting is performed every hour, and at −3 ° C., defrosting is performed every 12 hours. Further, when a 10 mm ice layer is formed on the inner wall surface of the rotating drum 3, 300 cc to 400 cc of water is supplied every 30 minutes while rotating the rotating drum 3,
It is formed by repeating several tens of times. Next, a method of controlling the fan in the constant temperature bath 1 will be briefly described with reference to a block diagram shown in FIG.

A control circuit of a control panel (control device) installed outside the thermostatic bath 1 has a program for a normal operation of a friction test of the sample W on ice or a wet road formed on the inner wall surface of the rotating drum 3 according to a program. (A normal operation routine) and a sequence in which a time for repeating the defrosting of the refrigerator 83 according to the program when frost adheres to the refrigerator 83 is set.

When a defrost command and a reverse rotation command are issued by operating the buttons on the control panel (operation panel), in the normal operation routine, the sample is stored in the constant temperature layer 1 at a set temperature by the refrigerator 83. A W friction test is performed. During such a friction test, when a defrosting command (defrosting command) of the refrigerator 83 is output for a preset time, the heater 84 for performing defrosting starts to operate, and corrects via the relay circuit. Forward and reverse rotation commands are issued to the drive motors 89a and 89b of the forward and reverse fans 85 and the forward fan 86 (stirring fan), and the frequencies of the drive motors 89a and 89b are changed (inverters) to perform forward, reverse and rotation speeds. (Speed variable) control, and at the same time, by specifying the speed of the forward rotation fans 87a and 87b (circulation fans), the frequency of the drive motors 90a and 90b is changed (inverter), and the forward rotation and rotation speed (variable speed) are performed.
Is performed.

In the embodiment of the present invention, when simulating friction on ice or wet road surfaces such as studless tires and all-season tires as described above, product tires are placed in the rotating drum 3 provided inside the thermostat 1. Sample W (test piece) is set, and used when performing a friction test in a state where the sample W is pressed on an ice layer formed on the inner wall surface of the rotating drum 3 when defrosting provided in the thermostat 1 Forward rotation,
Reverse fan 85 and forward fan 86 (fan for stirring)
By controlling the rotation direction and the number of rotations of a pair of forward rotation fans 87a and 87b (circulation fans) for circulating the cooled air in the thermostat 1, periodic defrosting is performed. It enables long-term operation during the on-ice test and enables evaluation on the same quality ice surface.

Further, the torque meter 63 is connected to the heat insulating and waterproof material 64.
Since the torque meter 63 is always kept warm and can always keep a constant temperature, as a result, the measurement accuracy of the frictional force can be improved. . Furthermore, the rotating drum 3
By providing the ice surface cutting and cleaning device 70 that automatically removes the ice chips from the ice surface formed on the inner wall surface, a uniform ice surface can be obtained at all times, thereby improving the workability of cutting the ice surface. Can do that.

In the above embodiment, the sample W
As the (test piece), a disk-shaped one having an outer diameter of about 60 mm and a thickness of about 10 to 20 mm is used. The rotating drum 3 is made of metal and has a diameter of about 700 mm, a length of 500 mm, and a thickness of 10 mm. The sample W is driven independently of the sample W and driven at a rotational speed of 0 to 60 km / H.

[0041]

According to the present invention, a hollow cylindrical rotary drum made of a metal material is rotatably mounted inside a thermostat provided with a refrigerating device and a heating device via a driving device as described above. In the rotating drum, a sample holder unit for rotatably and detachably mounting a disk-shaped sample is provided at the tip, and the sample rotatably mounted on the sample holder unit can be pressed or separated from the inner wall surface of the rotating drum. Provided,
In the vicinity of the sample in the rotating drum, a torque meter covered with a cover made of a heat insulating and waterproof material is provided in a rotation driving system for the sample, and an ice surface formed on an inner wall surface of the rotating drum is cut into a uniform smooth surface. The surface of the rotating drum provided in the constant temperature bath is provided with an ice surface cutting unit to perform and an ice surface cutting and cleaning device that collects the ice chips cut by the ice surface cutting unit and discharges it to the outside of the constant temperature bath. The test piece (sample) as a tire constituent material is pressed against the tire, and a friction test is performed on ice or on a wet road surface. In particular, a long-term operation during the test on ice can be performed, and the vibration of the rotating drum is reduced to reduce friction. There is an effect that the accuracy of force measurement can be improved.

Further, since the torque meter is configured to be covered with a cover made of a heat insulating and waterproof material, the torque meter can always be kept at a constant temperature while being kept at a constant temperature. As a result, the frictional force can be measured. There is an effect that accuracy can be improved. Furthermore, by providing an ice surface cutting and cleaning device that automatically removes ice chips from the ice surface formed on the inner wall surface of the rotating drum, a uniform ice surface can be obtained at all times. There is an effect that can be improved.

When conducting a friction test on a viscoelastic material,
A friction test can be easily simulated by using a sample of a variety of products without having to manufacture a prototype of the product to be actually used.This greatly reduces the time and effort required for product prototypes. In addition to this, there is an effect that costs can be reduced. Further, since the constituent materials of the product are evaluated in advance, there is an effect that the material is extremely effective as a screening test before the trial production of the product.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view of a friction test apparatus showing an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view taken along the line AA of FIG.

FIG. 3 is a partially enlarged sectional view taken along the line BB of FIG. 1;

FIG. 4 is a partially enlarged cross-sectional view of a sample holder unit.

FIG. 5 is a partially enlarged sectional view of the ice surface cutting unit.

FIG. 6 is a schematic configuration diagram showing a rotation drive system of a sample holder unit.

FIG. 7 is a plan view showing a rotation drive system of the sample holder unit.

FIG. 8 is a front view showing a rotation drive system of the sample holder unit.

FIG. 9 is a schematic configuration diagram of an ice surface cutting and cleaning device provided in a rotating drum.

FIG. 10 is a block diagram for controlling a fan in a constant temperature bath.

[Explanation of symbols]

Reference Signs List 1 constant temperature bath 3 rotating drum 10A refrigerating device 10B heating device 11 sample holder unit 50 ice surface cutting unit 63 torque meter 64 heat retaining waterproof material 70 ice surface cutting and cleaning device 85 forward rotation, reverse rotation fan 86 forward rotation fan (fan for stirring) 87a , 87b Forward fan (circulation fan) W sample

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Sato 1053-1 Yayoi, Ichiya, Tokyo Within Japan Applied Technology Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 19/02

Claims (4)

(57) [Claims] 1. A hollow cylindrical rotary drum made of a metal material is rotatably mounted inside a thermostat provided with a refrigerating device and a heating device via a driving device.
A sample holder unit for rotatably and detachably mounting a disk-shaped sample is provided at a tip, and a sample rotatably mounted on the sample holder unit is provided on an inner wall surface of a rotary drum so as to be pressurized or separated therefrom. An ice surface for providing a torque meter covered with a cover made of a heat insulating and waterproofing material in the rotation drive system of the sample in the vicinity of the sample inside, and cutting the ice surface formed on the inner wall surface of the rotating drum into a uniform smooth surface A friction test apparatus, comprising: a cutting unit; and an ice surface cutting and cleaning device that collects ice chips cut by the ice surface cutting unit and discharges the ice chips out of a constant temperature bath. 2. The friction test apparatus according to claim 1, wherein the rotating drum is formed of a non-rusting metal material such as aluminum, stainless steel, and duralumin. 3. The ice surface cutting and cleaning device comprises a cleaning blade for collecting ice chips on the ice surface at one end of a rotating drum, and a vacuum device for discharging the collected ice chips to the outside of a thermostat. Claim 1 or Claim 2
3. The friction test device according to 1. 4. A fan inside a thermostat provided with a refrigerating device and a heating device, the fan being controllable in rotation speed and rotation direction during freezing or defrosting in the bath. 3. The friction test device according to 1.