JP2000186991A - Method and device for measuring torsion spring constant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple measuring method and device, capable of measuring accurately and easily a torsion spring constant of a mechanical elementary component using a flexible coupling, a torsion spring and other torsional torque mechanism, in conditions which are to a practical condition. SOLUTION: One end part of a measured object 3 which is a mechanical element component using flexible coupling, a torsion spring and other torsional torque mechanism is fixed to a mounting jig 15 provided in a bearing 11, and the other end part is fixed to a mounting jig 25 provided in a shaft end of a motor 21. An arm 12 and a load cell 10 are provided in the bearing 11 to measure a rotational torque, and a rotary encoder 20 is provided in the motor 21 via a toothed belt 24 for measuring rotational angle. The measured torque and rotational angle measured by the method are calculated, using a prescribed signal processing circuit to calculate a torsion spring constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a flexible shaft coupling (flexible coupling) used for a precision transmission,
The present invention relates to a method and an apparatus for measuring a torsion spring constant of a machine element component using a spring joint and other torsion torque mechanisms.

2. Description of the Related Art In order to measure a torsion spring constant, a torsion angle and a torsion torque must be measured simultaneously. As this method, a method using a commercially available load cell type universal compression and tensile tester is widely and generally used because of its simplicity. In addition, as a method to enhance its convenience,
A dedicated measuring device adapted to the shape of the test sample, that is, a general-purpose spring testing device is used. In any of the above methods, the torsion torque is calculated by arm length × force (measured load by the load cell), and the torsion angle at that time is calculated by coordinate calculation using the movement amount of the arm. The method using a load cell-type universal compression / tensile tester is particularly suitable for a small amount of test because the measurement can be performed by using a minimum mounting jig. This method will be described with reference to FIGS. In FIG. 6, a conventional apparatus 1a includes a moving table 40 mounted on a column (not shown).
The load cell 10a is disposed on the movable table 40a, and the DUT 3a is fixed on the fixed table. When the DUT 3a is a flexible shaft coupling, one hub 31
a is locked to the mounting jig 25a, and the opposite side 31a is locked to the mounting jig 15a. At this time, the arm 12a is integrally arranged at the end of the mounting jig 15a,
a is locked to the fixed base via the mounting jig 25a. FIG. 7 shows that the arm 12a and the load cell 10a are at the initial set position. With the start of the downward movement of the movable table 40a, the load cell 10a rotates the arm 12a downward against the torsional stress of the arm 12a.
At this time, the torsional torque is calculated from the arm length Lx of the arm 12a and the measurement value of the load cell 10a, and the rotation angle α is calculated from the movement allowance of the movable table 40a and the arm length Lx by coordinate calculation. Next, an example of a dedicated measuring device according to a conventional example will be described with reference to FIGS. In FIG. 9, the DUT 3b locks one hub 31b to the mounting jig 25b and locks the other hub 31b to the mounting jig 15b. At this time, the arm 1 is attached to the end of the mounting jig 15b.
2b are arranged integrally, and the DUT 3b is attached to the mounting jig 2
Locked to the fixed base via 5b. FIG.
b and the load cell 10b are at the initial set position. With the start of movement of the movable table 40b, the load cell 10b rotates the arm 12b against the torsional stress of the arm 12b. At this time, the torsional torque is calculated from the arm length Lx of the arm 12b and the measured value of the load cell 10b, and the rotation angle α is calculated from the movement allowance of the moving table 40b and the arm length Lx by coordinate calculation. As described above, in any of the conventional methods, the method of applying the torsional torque is a method including linear movement, and the processing of the measured value requires coordinate calculation. This coordinate calculation is calculated using FIG. 10 and the following calculation formula. Lx ² = (Lx + dx) ² + Ly ² − (Lx + dx) × L
ycos (α / 2) Note that the positions a and b shown in FIG. 10 indicate the initial setting positions of the DUT 3b shown in FIG. 8, and the positions a ′ and b ′ indicate that the load cell 10b in FIG. The position moved by dx in the direction is shown.

When a commercially available universal load cell type universal compression / tensile testing machine is used, the moving distance (arm moving distance) and arm length of the moving table are measured each time measurement is performed, and the coordinates are calculated. In addition, the mounting jig has to be manufactured each time corresponding to the size of the object to be measured. In addition, when a dedicated test device such as a commercially available general-purpose spring test device is used, the convenience is high because the built-in dedicated coordinate calculation program automatically calculates the torsional spring constant. Become. However, an indexing table for rotating the object to be measured thereon, an XY table for moving a load cell section for measuring an arm reaction force of the object to be measured on the table to a predetermined position, and the arm reaction force and the coordinate position Therefore, a series of programs and an arithmetic processing unit for calculating the torsion spring constant from the calculated values and displaying them on the display are necessary, and there is a problem that the device becomes expensive in exchange for convenience. Furthermore, in any of the above methods, some of the test methods include a linear movement, such as a flexible shaft coupling for the purpose of shock relaxation, or a precision positioning coupling for the purpose of vibration damping. In the measurement of the torsional spring constant, there was a problem in the reliability of the measured value because the method of applying the torque was different from the actual method.
That is, there is a problem in that a correct torsional torque does not act on the measured objects 3, 3a and 3b, and an unnecessary bending moment acts on the measured objects 3, 3a and 3b via the arms 12a and 12b.

According to a first aspect of the present invention, there is provided a method for measuring a torsion spring constant, wherein one end of an object to be measured is fixed to a rotatable bearing, and the other end is connected to a motor shaft. After directly connecting and rotating the motor at a predetermined number of revolutions,
The rotational torque is measured by an arm torque detecting means provided on the bearing, and at the same time, the rotational angle is measured by a rotary encoder driven from the motor shaft via a synchronous transmission means, and the torsion spring constant is determined using these measured values. Is a method for measuring the torsion spring constant. The invention according to claim 2 is the method according to claim 1, wherein the synchronous transmission means for driving the rotary encoder is a toothed belt, and the speed increase ratio is at least 2 or more. According to a third aspect of the present invention, in the torsion spring constant measuring apparatus, a bearing for rotatably supporting one shaft end of the object to be measured, and an arm torque detecting means disposed on the bearing to measure a rotational torque are provided. A direct-coupled motor on the side that rotates the device under test around its rotation axis, a rotary encoder driven from the motor shaft via synchronous transmission means, and a rotational torque measured by the arm torque detection means. An arithmetic device for calculating a torsion spring constant using the rotation angle measured by the rotary encoder. The invention according to claim 4 is the torsional spring constant measuring device according to claim 3, wherein the synchronous transmission means for driving the rotary encoder is a toothed belt, and the speed increase ratio is at least 2 or more.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus for measuring a torsion spring constant according to the present invention will be described in detail with reference to the drawings. 1 is a front view of a torsion spring constant measuring device, FIG. 2 is a plan view thereof, and FIG. 3 is an enlarged view of a portion A in FIG. FIG. 4 is a signal processing block diagram of the device according to the present invention, and FIG. 5 is a graph showing measurement results according to the present invention. In FIG. 2, a mounting jig 25 having an end flange shape is attached to a shaft end of the motor 21, whereby the DUT 3 which is a shaft coupling (coupling) can be fixed. In addition, a toothed pulley 22 is assembled to the motor shaft, and the rotary encoder 20 disposed side by side can be driven at a predetermined rotation ratio via a toothed belt 24. The rotation output pulse of the rotary encoder 20 is input to the pulse calculation circuit 61 of the signal processing block diagram shown in FIG. 4, the rotation angle is calculated by the angle calculation circuit 62, and the result is output to the display circuit 63 and the output circuit 64. I do. The bearing 11 that can move in parallel along the motor axis is disposed at a position facing the motor 21.
At one shaft end of the bearing 11, a mounting jig 15 in the form of an end face flange capable of fixing and supporting the device under test 3 from the opposite side facing the motor shaft is assembled, and at the other shaft end, Rotating arm 1 that can measure shaft rotating torque
2 are assembled together. This rotational torque can be obtained by measuring the load force of the load cell 10 connected via a universal joint provided at the tip of the arm 12. The signal of the load cell 10 is applied to the torque calculation circuit 51 of the signal processing block diagram shown in FIG.
To calculate the rotational torque, and display the result in the display circuit 63,
Output to the output circuit 64. The object 3 can be attached by fixing the outer diameter of the hub 31 or by fitting the hole of the object 3 to the shaft end provided integrally with the flange surface. However, any of these can be appropriately performed. Here, details of the DUT 3 will be described below with reference to FIG. The DUT 3 is generally used as a shaft coupling (coupling) for connecting a transmission shaft and transmitting torque, but the shaft coupling (coupling) to which the present invention is applied mainly includes a servo. It is used for precise positioning by connecting a motor shaft composed of a motor, a stepping motor or the like and a moving body represented by a precision XY table. The DUT 3 has a cylindrical appearance, and the hubs 31 at both ends are directly fitted to the motor shaft and the driven shaft, and are integrally fixed by a set screw, a key, a taper lock, or the like. The elastic body 30 made of urethane elastomer, rubber elastomer, or the like at the center is used by being mounted between the hubs 31 on both sides. However, the elastic body 30 can be separated according to the purpose of use, or can be separated integrally with the hubs 31 at both ends. It is classified as one that has been processed to be impossible. The elastic body 3
The number 0 is used for the purpose of shortening the overall machine cycle by quickly absorbing the impact vibration at the time of starting, particularly at the time of stopping the positioning, and at the same time improving the trouble caused by the vibration, for example, the printing accuracy.

Next, an embodiment of a torsion spring constant measuring apparatus according to the present invention will be described. The DUT 3 has an outer diameter of 40
mm, a total coupling length of 50 mm and a rated torque of 1.0 kgfm, a small coupling manufactured by Mitsuboshi Belting Co., Ltd., HAS-40 (registered trademark, Chemi-chan) was used. In addition, the motor 21
Has 0.2 kW, 1.5 rpm, and output torque of 78.5.
A general-purpose three-phase induction motor of kgfm was used, and a rotary encoder RP-432Z manufactured by Ono Sokki Co., Ltd. of 600 (pulse / rotation) was used as a rotary encoder. The rotation ratio between the motor shaft and the encoder was increased six times using a toothed belt. As a result, an encoder output of 3600 pulses per one rotation of the measurement shaft became possible. As a result, the angular resolution is changed from 0.6 (deg./pulse) to 0.1 (deg./pulse), and the resolution is 6 (deg./pulse).
There was a double precision improvement. The load cell 10 was a TU-BR500K made by TEAC Co., Ltd. with a rating of 500 kgf, the effective length of the arm 12 was 0.1 m, and the measurable torque was MAX 50 kgfm. FIG. 5 shows the result of measurement using the apparatus having the above configuration.
In FIG. 5, the vertical axis indicates the rotational torque (kgfm) and the torsion angle (degree), and the horizontal axis indicates the time and the measurement mode. As a result of the calculation, the torsion spring constant of the object to be measured is 0.45 kgfm / deg. Met. As described above, in the present embodiment, a small shaft coupling is used for the DUT 3, but the DUT 3 is not limited to this, and any measurement can be performed as long as it is a mechanical element using torsion torque means. it can. Further, the speed increase ratio between the motor shaft and the encoder shaft is set to 6 times in the embodiment, but since this speed increase ratio is proportional to the angular resolution, if the speed increase ratio is at least 2 times or more, the angular resolution is increased. It is effective for improvement. The speed increase ratio is limited by the tensile strength, rigidity of the toothed belt, the minimum pulley diameter determined by the tooth strength, the minimum number of meshing teeth determined by the rotation ratio and the distance between the shafts, or the dimensional restrictions due to the mounting space, etc. Generally, the speed increase ratio is limited to 10 times.

According to the method of the first aspect of the invention, there is an effect that an accurate measured value can be obtained in a state where the torsion spring constant of the shaft coupling (coupling) is closer to the actual use condition of the actual machine. According to the second aspect of the invention, there is an effect that the rotation angle resolution can be easily and inexpensively improved. Claim 3
According to the invention of (1), the torsion spring constant of the shaft coupling (coupling) can be measured exactly under the same conditions as the actual machine, so that an apparatus with extremely high accuracy and excellent convenience can be obtained.
According to the invention of claim 4, it is possible to increase the rotational angle resolution of the shaft coupling (coupling) by an easy and inexpensive method, and it is possible to provide a device that enables more accurate performance evaluation.

[Brief description of the drawings]

FIG. 1 is a front view of an apparatus for measuring a torsion spring constant according to the present invention.

FIG. 2 is a plan view of an apparatus for measuring a torsion spring constant according to the present invention.

FIG. 3 is an enlarged view of a portion A in FIG. 2;

FIG. 4 is a signal processing block diagram of the measuring device according to the present invention.

FIG. 5 is a graph showing measurement results according to the present invention.

FIG. 6 is a side view of an apparatus for measuring a torsion spring constant according to Conventional Example 1a.

FIG. 7 is a front view of a device for measuring a torsion spring constant according to Conventional Example 1a.

FIG. 8 is a side view of a torsion spring constant measuring device according to Conventional Example 1b.

FIG. 9 is a front view of an apparatus for measuring a torsion spring constant according to Conventional Example 1b.

FIG. 10 is a schematic diagram showing a coordinate calculation method according to a conventional example.

[Explanation of symbols]

 1, 1a, 1b Torsional spring constant measuring device 3, 3a, 3b DUT 10, 10a, 10b Load cell 11 Bearing 12 Arm 15, 15a, 15b Mounting jig 20 Rotary encoder 21 Motor 22 Toothed pulley 23 Toothed pulley 24 Toothed belt 25, 25a, 25b Mounting jig 30 Elastic body 31, 31a, 31b Hub 40a, 40b Moving table 50 Load cell AMP 51 Torque calculation circuit 52 Display circuit 53 Output circuit 60 Motor control circuit 61 Pulse calculation circuit 62 Angle calculation circuit 63 Display circuit 64 Output circuit

Claims (4)

[Claims] In a method for measuring a torsion spring constant, one shaft end of an object to be measured is fixed to a rotatable bearing, the other shaft end is directly connected to a motor shaft, and the motor is rotated at a predetermined rotation speed. After that, the rotational torque is measured by the arm torque detecting means provided on the bearing, and simultaneously, the rotational angle is measured by the rotary encoder driven from the motor shaft via the synchronous transmission means, and these measured values are used. A method for measuring a torsion spring constant, comprising calculating a torsion spring constant. 2. The method according to claim 1, wherein the synchronous transmission means for driving the rotary encoder is a toothed belt, and the speed increase ratio is at least 2 or more. 3. A torsion spring constant measuring apparatus, comprising: a bearing rotatably supporting one shaft end of an object to be measured; an arm torque detecting means arranged on the bearing to measure a rotational torque; A direct-coupled motor that rotates the device under test around its rotation axis, a rotary encoder driven from the motor shaft via a synchronous transmission unit, a rotation torque measured by the arm torque detection unit, An arithmetic unit for calculating a torsion spring constant using a rotation angle measured by a rotary encoder. 4. The torsional spring constant measuring apparatus according to claim 3, wherein the synchronous transmission means for driving the rotary encoder is a toothed belt, and the speed increase ratio is at least 2 or more.