JPS5824774Y2 - Microtorque meter for rotating bodies - Google Patents

Description

[Detailed Description of the Invention] The present invention provides an inexpensive device for easily measuring the minute torque of a rotating body.

BACKGROUND ART Conventionally, devices have been put into practical use that accurately measure relatively large rotational torques and frictional torques using various principles and methods.

However, there are dedicated torque measuring instruments such as Bendix and Asch for measuring extremely small torques, such as bearing friction torque, but they are very expensive.

On the other hand, tape guide rollers used in recorders, VTRs, etc. also require minute torque, and variations in the friction torque of these rollers directly affect the performance of the device, so strict control is required in the manufacturing process. There is.

However, conventionally it has been difficult to easily measure and inspect the friction torque of this type of roller on-site.

The present invention provides a device that can extremely easily measure and inspect the friction torque of this type of roller on-site.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a diagram illustrating torque measurement of a bearing according to the present invention.

Reference numeral 1 denotes a horizontal shaft, which is rotatably supported by a bearing 2.

The outer ring of the bearing 2 is fixed to a main body (not shown).

3 is a drive boot for the shaft 1, which is fixed to the shaft 1 with a screw or the like.

Reference numeral 4 denotes a belt, which is placed around the driving pulley 5 and the drive pulley 3, and transmits the rotation of the electric motor 6 to the shaft 1.

The electric motor 6 is attached to the main body (not shown).

The bearing to be measured, generally designated 10, includes an inner ring 7, a ball 8,
It consists of an outer ring 9.

The inner ring 7 is attached to the shaft 1 with a tight fit that prevents it from idling.

Alternatively, the inner ring 7 may be sandwiched in the left-right direction by flanges 11 and 12 that are connected to the shaft 1 with screws or the like to prevent it from idling with the shaft 1.

13 is an unbalanced weight, to which a pointer 14 is fixed.

A holder 15 is detachably held on the outer ring 9 of the bearing 10 to be measured, and is made of an elastic material and constitutes a holding means for the unbalanced weight, and is fixed to the unbalanced weight 13.

As clearly shown in FIG. 2, the holder 15 is composed of a U-shaped leaf spring, and is detachably attached to the outer ring 9.

Reference numeral 16 denotes a scale plate having a radial scale aligned with the center of the shaft 1, and is fixed to the main body (not shown).

When the shaft 1 is rotated, the inner ring 7 also rotates, but due to the frictional force acting on the balls 8 interposed between the inner ring 7 and the outer ring 9, the outer ring also rotates in the same direction as the shaft.

For convenience of explanation, FIG. 3 omits the balls and is shown assuming that the inner ring 7 and the outer ring 9 are in contact with each other.

Now, when the inner ring 7 rotates clockwise, the point P where it contacts the outer ring 9 is f.

A frictional force of -μW acts.

However, μ is the coefficient of friction between the inner ring and outer ring, and W is the coefficient of friction between outer ring 9 and pointer 1.
4. Weight of the unbalanced weight 13 including the holder 15.

This frictional force fo becomes a moment that rotates the outer ring 9 in a clockwise direction.

Tf = foOP -μW, OP -------11--- ■However, if O is the center of the shaft 1, and Q is the center of gravity of the unbalanced weight 13 including the outer ring 9, pointer 14, and holder 15. , an extra force of gravity in the tangential direction of the outer ring 9 1=W sin α causes a moment to rotate the outer ring 9 in the counterclockwise direction.

Tq=f40Q=OQ V'l sin α---10 However, α is the rotation angle of the outer ring when the above two moments are balanced.

By reading the angle α of the pointer 14 at this time using the scale 16, the friction torque of the bearing 10 to be measured can be determined.

If the angle α is equal to the formula
is determined, and the friction torque is determined by formula (■).

Note that the required minute torque can be measured by appropriately selecting the size of the unbalanced weight.

4 and 5 show a second embodiment of the present invention, in which the bearing to be measured, generally designated 20, consists of a support shaft 21, a rotating cylinder 22, an upper flange 23, and a lower flange 24. It has become.

Such a roller with a shaft is often used as a tape guide for recorders, VTRs, etc., but the rotating cylinder 22 is often made of a soft material such as resin or A1, and a holder as shown in Fig. 1 is used. If 15 is used, the cylinder 22 will be damaged, so it may not be usable.

This embodiment is characterized in that a permanent magnet is used for the unbalanced weight 13' as a holding means.

In addition, in order to measure the torque in the assembled state, a coupling 17 is provided on one side of the shaft 1' to drive the support shaft 21, and when the support shaft 21 is inserted, the electric motor 6
requires a structure that can transmit rotation.

Therefore, in the practical example, the support shaft 21 is rotatably supported by two bearings 18, the coupling 17 is made of an elastic body such as rubber, and the inner diameter of the hole of the coupling 17 is the same as that of the support shaft 21.
1, and drives the support shaft 21 by friction.

Even if the cylinder 22 is made of a non-magnetic material such as resin or a soft metal such as A1, the present invention can be applied when the support shaft 21 is made of a ferromagnetic material.

That is, in FIG. 6, the balance of forces at point P' when the support shaft 21 is at rest is expressed by the following equation.

WmR0+ Fm −−−−−−−−−−
−−−−−■W=WH+Wm+Wi −−−−−−−−
−−−−−−−−− ■Here, Ro: Cylinder 22, permanent magnet 1 located at point P' of axis 21
3', Reaction force of gravity WR acting on the pointer 14: Gravity acting on the cylinder 22 Wm: Weight W acting on the permanent magnet 13': Gravity Fm acting on the pointer 14: Acting on the permanent magnet 13' and the shaft 21 The magnetic force of the permanent magnet 13' must be Fm>Wm+Wj.

Also, Fig. 6 shows the case of W>Fm>Wm+WI, but F
When m>W, the sign of the reaction force R8 may be set to negative in equation (2).

Next, when the shaft 21 rotates clockwise, the balance of forces in the following equation is established in FIG.

WR+Mi+Wi=R□+Fmcosα −−−−−■
The cylinder 22 is also rotated clockwise due to the frictional force between the support shaft 21 and the cylinder 22, but this frictional moment Tf is
It is given by Eq.

Tf=μRO・OP=μ(W-FmCO8α)○P-■
On the other hand, the gravitational moment due to WR+Wm+%=W acts counterclockwise at the center of gravity Q of W, and its magnitude T
g is given by the formula 0.

Wsina-OQ Since formulas ■ and ■ are balanced, ■ From formula 0, the friction coefficient μ is a function of the angle α, and by finding the angle α, the friction coefficient μ can be found, and the friction moment (= friction torque) can be calculated by formula ■. Seek.

Next, consider the case where the support shaft 21 is non-magnetic and the cylinder 22 is ferromagnetic.

In this case, since the permanent magnet 13' does not exert any force on the non-magnetic support shaft 21, the friction moment (■) is expressed as T±=□W, ○P −−−−m−−−−−−−■○
P, and sin α=μ−, which is the same as equation (2).

OQ Therefore, the friction torque can be calculated using the formula (■).

As described above, the torque measuring device according to the present invention is capable of measuring minute torques (1 g-0 m or less) by selecting a small moment due to gravity acting on the unbalanced weight and pointer.

In addition, it has an extremely simple configuration and is inexpensive, and has the advantage of being accurate because there are no sources of error due to its simple structure.

Furthermore, by increasing the rotational speed of the shaft excessively, it is also possible to read torque fluctuations during one revolution of the shaft.

Furthermore, since the measurement principle is based on only the coefficient of friction and gravity, the measurement of torque due to changes in environmental conditions such as temperature and humidity has the advantage of being able to be measured without error under actual operating conditions.

As described above, the present invention has a holding means that removably engages the unbalanced weight with the rotating body to be measured, so it can be quickly applied to a large number of objects to be measured. It is extremely useful for the purpose of determining and inspecting the relative value of an object between 1 and 1 lux, and is of great industrial value.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of a minute torque meter for a rotating body according to an embodiment of the present invention, Fig. 2 is a front view of the same, Fig. 3 is an explanatory diagram explaining the same measurement principle, and Fig. 4 is an illustration of the micro torque meter of the present invention. FIG. 5 is a longitudinal cross-sectional view showing the second embodiment, FIG. 5 is a front view thereof, and FIGS. 6 and 7 are explanatory diagrams illustrating the same measurement principle. 1...shaft, 2...bearing, 3...
・Drive pulley, 4...Belt, 5...
Driving pulley, 6... Electric motor, 10.20...
...Bearing to be measured, 13.13'...Unbalance weight, 14...Pointer, 15...
・Holder, 16... Scale plate, 17...
Coupling, 18...Bearing.

Claims (2)

[Scope of utility model registration request] (1) A shaft held horizontally, a bearing for the shaft, a rotating means for the shaft, a rotating body to be measured that is externally pushed by the shaft, and a shaft that is detachably attached to the outer periphery of the rotating body to be measured. It consists of an unbalanced weight having a retaining means for mating, a pointer integrally constructed with the unbalanced weight, and a scale plate that coincides with the center of the shaft and has a radial scale, and the shaft is rotated. A minute torque meter for a rotating body that measures rotational friction torque by balancing the frictional force generated between the rotating body and the rotating body to be measured and the gravity acting on the unbalanced weight. (2) A minute torque meter for a rotating body according to claim 1, wherein only either the shaft or the rotating body to be measured is made of a magnetic material, and the means for holding the unbalanced weight is made of a permanent magnet. .