JP2000097791A - Screwing torque measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a screwing torque measuring apparatus in which highly accurate measurements can be attained regardless of the rotary operating speed of a tubular body while preventing fluctuation of measurement due to difference of skill of worker. SOLUTION: The screwing torque measuring apparatus comprises a spring mechanism 9 interposed between a screwing bit 4 and a tubular body 1 and generating a resilient force in the direction resisting against rotation of the tubular body, an encoder 10 for detecting distortion of the spring mechanism based on the relative rotation between the screwing bit and the tubular body, means for detecting inversion of the relative rotational direction between the screwing bit and the tubular body based on an output signal from the encoder, and means for storing the measurement of the encoder as a screwing torque for a screw to be measured in response to a detection signal from the means for detecting inversion of the relative rotational direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple screw tightening torque measuring device suitable for, for example, extracting and inspecting a tightening torque of a screw for tightening a product and a part, and particularly easily adaptable to manual operation. Also, the present invention relates to a screw tightening torque measuring device improved so as to enable simple and high-precision measurement.

[0002]

2. Description of the Related Art FIG. 12 is a sectional view showing a mechanism of a sensor section of a conventional screw tightening torque measuring device. In FIG. 12, reference numeral 1 denotes a cylindrical body constituting a drive unit main body of the torque measuring means, which is manually rotated by an operator in the direction of increasing the tightening of the measured screw W when checking the screw tightening torque of the measured screw W. .

[0003] Reference numeral 2 denotes a strain gauge type torque sensor fixed inside the cylindrical body 1. Reference numeral 3 denotes a drive shaft connected to the input shaft 2a of the torque sensor 2. A screw-shaped bit 4 in the form of a driver is detachably attached to the other end of the drive shaft 3.

[0004] Reference numerals 5 and 6 denote bearings for rotatably supporting the drive shaft 3 in the cylindrical body 1, and reference numerals 7 and 8 denote end covers for closing the upper and lower ends of the cylindrical body 1. Torque sensor 2
Of the input shaft 2a during rotation of the cylindrical body 1
It rotates together with the drive shaft 3 and the screw tightening bit 4.

Reference numeral C denotes a controller composed of a microcomputer, which processes an output signal derived from the torque sensor 2 and displays a screw tightening torque of the screw W to be measured on a display unit D.
And when the screw tightening torque indicates an abnormal value, the alarm unit E is driven to notify the abnormal state.

The output of the torque sensor 2 can be displayed numerically in a predetermined torque unit (for example, Kgf-cm) via an external or a circuit module (amplification and digital conversion circuit) in the torque sensor 2. In the stage of shipment as a torque measuring device, it is assumed that calibration is performed individually in accordance with each strain gauge characteristic.

Next, the operation of the conventional screw tightening torque measuring device shown in FIG. 12 will be described with reference to FIG. FIG. 13 shows output characteristics of the torque sensor 2 when the cylindrical body 1 is rotated. The horizontal axis corresponds to time t, and the vertical axis corresponds to detected torque (output torque) T.

When measuring the screw tightening torque using the conventional apparatus configured as shown in FIG. 12, an operator first holds the cylindrical body 1 with his / her hand and covers the cutting edge of the screw tightening bit 4. Insert into the head of the measuring screw W.

Subsequently, by rotating the cylindrical body 1 in the direction of tightening the screw W to be measured, the torque sensor 2,
A drive torque in the additional tightening direction is applied to the head of the screw W to be measured via the drive shaft 3 and the screw tightening bit 4.

When the force (drive torque) applied to the cylindrical body 1 is increased with the lapse of time t when the screw W to be measured is retightened, the detected torque T output from the torque sensor 2 becomes as shown in FIG. As shown by 13, the drive torque increases with an increase in drive torque (time t has elapsed).

In FIG. 13, the moment the detected torque (driving torque) T exceeds the static friction torque (peak torque Tp) between the male screw and the female screw of the screw W to be measured (time tp), the torque sensor The detection torque T of No. 2 is temporarily reduced because the friction between the male screw and the female screw shifts from the static friction region to the dynamic friction region.

After the time tp, an actual retightening region is reached, and the retightening operation of the screw W to be measured proceeds with an increase in the driving torque for the cylindrical body 1. The detected torque T of the torque sensor 2 is led out to an external controller C, digitized by amplification and digital conversion in the controller C, and then analyzed.

The controller C stores the peak torque value Tp (see FIG. 13) when the detected torque T suddenly decreases as "tightening torque" based on the time change of the detected torque T, and displays the current torque value. It is displayed in the section D.

The controller C determines whether or not the detected tightening torque is within an allowable range of a target value. If the detected tightening torque is within the allowable range, it is regarded as normal. An abnormal state is notified by driving an alarm unit E such as the one shown in FIG.

As described above, in the controller C, the tightening torque of the screw W to be measured is detected by focusing on the value (dT / dt) obtained by differentiating the detected torque (drive torque) T with the time t.

However, as shown in FIG. 12, the screw tightening torque measuring device using the strain gauge type torque sensor 2 is used when the cylindrical body 1 is driven to rotate slowly or rapidly, and It is known that noise is generated in the measured value of the tightening torque due to fluctuations in the speed during rotation, and a measurement error is likely to occur.

It is known that in such a rotating operation of the cylindrical body 1, the skilled worker is required to be skilled, and that the measured value is apt to vary depending on the worker. Therefore, conventionally, various measures have been proposed in order to eliminate the cause of the torque measurement error.

For example, in the "Tightening force measuring method" of Japanese Patent Publication No. 8-1402, the rotation angle θ of the driving portion is measured together with the retightening torque T, and the differential value of the retightening torque T by the rotation angle θ is measured. A method of measuring a tightening force by paying attention to (dT / dθ) is described.

However, also in the measuring method described in the above-mentioned publication, the time change (dT / dt) / (dθ / d) of the driving torque is required as long as the manual operation is performed by an operator.
The calculation of t) is still the same, and the influence of the torque change on the time t cannot be avoided.

In the "Method and apparatus for measuring screw tightening torque" disclosed in JP-A-8-1535, a torque measuring method for storing the torque at the start of rotation of a screw tightening motor while gradually increasing the torque of the motor. Is stated.

However, in the measuring method described in the above-mentioned publication, a screw tightening motor is indispensable, and even at the start of the rotation of the motor, the rotation is not rapidly increased due to the inertia of the motor. Therefore, in this case, since the torque is measured by a loosening operation, a step of retightening the screw W to be measured is required.

[0022]

As described above, the conventional screw tightening torque measuring apparatus pays attention to the time differential value (dT / dt) of the driving torque T, so that measurement noise is generated due to rotation speed fluctuation and the like. There is a problem that the measured values tend to vary depending on the skill of the worker.

Also, in the tightening force measuring method described in Japanese Patent Publication No. 8-1402, attention is paid to the rotational angle differential value (dT / dθ) of the retightening torque T. There was a problem that the values tended to vary.

Further, in the method for measuring the screw tightening torque described in Japanese Patent Application Laid-Open No. H8-1535, a screw tightening motor is required, and the measuring method is a loosening operation. However, there is a problem that the cost increases.

The present invention has been made in order to solve the above-mentioned problems. If the rotational operation speed of the cylindrical body is equal to or less than a predetermined speed, a simple rotational operation speed can be obtained. It is an object of the present invention to obtain a screw tightening torque measuring device that enables a highly accurate measurement result to be obtained by an operation and prevents a variation in a measured value due to a difference in the skill level of an operator.

[0026]

According to a first aspect of the present invention, there is provided a screw tightening torque measuring device comprising: a screw tightening bit inserted into a head of a screw to be measured; and a cylindrical member for rotating the screw tightening bit. In a screw tightening torque measuring device comprising a body and a torque measuring means for measuring a torque applied to the cylindrical body, the torque measuring means is provided between the screw tightening bit and the cylindrical body. A spring mechanism that generates an elastic force to oppose the rotation direction of the body, an encoder that detects a distortion amount of the spring mechanism by a relative rotation amount between the screw tightening bit and the cylindrical body, and an encoder output signal. Rotation change detection means for detecting a reversal change in the relative rotation direction between the screw tightening bit and the cylindrical body based on the rotation change detection signal from the rotation change detection means. The value is obtained is constituted by a storage means for storing a screwing torque about the measured thread.

According to a second aspect of the present invention, there is provided a screw tightening torque measuring device according to the first aspect, wherein the encoder comprises:
A two-phase encoder including a disk formed with a two-phase striped slit row and rotating integrally with a screw tightening bit, and an optical sensor fixed in a cylindrical body so as to be opposed to the disk. And the torque measuring means includes a reversible counter for measuring the relative movement amount between the disk and the optical sensor as the amount of distortion of the spring mechanism.

According to a third aspect of the present invention, there is provided the screw tightening torque measuring device according to the first or second aspect.
The torque measuring means includes a strain gauge type torque sensor provided between the screw tightening bit and the cylindrical body.

According to a fourth aspect of the present invention, there is provided a screw tightening torque measuring device according to any one of the first to third aspects, wherein a target torque and an allowable error range which are criteria for judging the quality of the screw tightening torque are set. Selecting means for determining whether the screw tightening torque is normal or abnormal, based on whether the measured value stored in the storage means is within an allowable error range of the target torque, and torque determining means. Alarm means that is driven when it is determined that the screw tightening torque is abnormal.

According to a fifth aspect of the present invention, there is provided a screw tightening torque measuring device according to any one of the first to fourth aspects, wherein the rotation change detecting means comprises a cylinder corresponding to the direction of retightening the screw to be measured. Pulse generating means for generating a normal rotation pulse in response to a first rotation direction of the cylindrical body, and a reverse rotation pulse in response to a second rotation direction of the cylindrical body corresponding to a direction opposite to the retightening direction. And a reverse rotation amount counter that counts the reverse rotation pulse and is reset by the normal rotation pulse. The reverse rotation amount counter rotates when the count value of the reverse rotation pulse exceeds a predetermined value. It outputs a change detection signal.

According to a sixth aspect of the present invention, there is provided a screw tightening torque measuring device according to any one of the first to fourth aspects, wherein the rotation change detecting means comprises a cylindrical member corresponding to a loosening direction of the screw to be measured. Forward rotation pulse generating means for generating a forward rotation pulse in response to a first rotation direction of the body, and generating a reverse rotation pulse in response to a second rotation direction of the tubular body corresponding to a direction opposite to the loosening direction A reverse rotation pulse generating means, and a reverse rotation amount counter which counts the reverse rotation pulse and is reset by the normal rotation pulse, wherein the reverse rotation amount counter detects a rotation change when the count value of the reverse rotation pulse exceeds a predetermined value. It outputs a signal.

According to a seventh aspect of the present invention, there is provided a screw tightening torque measuring device according to the first aspect, wherein the encoder comprises:
The rotation change detecting means is constituted by a multi-bit absolute value encoder, and detects a reversal change in the relative rotation direction based on a logical judgment of each bit of the encoder.

An eighth aspect of the present invention provides the screw tightening torque measuring device according to any one of the first to seventh aspects, further comprising an electric motor for applying a rotational force to the tubular body. In addition, only the rotation operation and the stop operation are performed without controlling the torque.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention in a sectional view of a sensor section mechanism and a block diagram of a controller section. In FIG. 1, the same components as those described above (see FIG. 12) are denoted by the same reference numerals, and detailed description is omitted.

Reference numeral 9 denotes a coil spring having one end fixed inside the cylindrical body 1, and is provided between the screw tightening bit 4 and the cylindrical body 1. The coil spring 9 constitutes a spring mechanism for generating an elastic force so as to oppose the rotation direction of the tubular body 1.

Reference numeral 10 denotes a two-phase encoder (hereinafter, simply referred to as an “encoder”), and a disk 11 that rotates integrally with the drive shaft 3 and the screw tightening bit 4, and a light fixed inside the cylindrical body 1. And a sensor 12.

The disk 11 of the encoder 10 is, for example,
Two-phase light-transmitting slit rows (or reflecting slit rows) composed of 1024 radial stripes are formed.
The optical sensor 12 is disposed to face the disk 11 and generates a two-phase pulse signal (described later) according to the presence or absence of a two-phase light-transmitting slit array (striped pattern) on the disk 11. .

The encoder 10 includes a drive shaft 3 as shown in FIG.
It is arranged in a part of. One end of the disk 11 is connected to the coil spring 9. Accordingly, the encoder 10 detects the amount of distortion (the amount of twist) of the coil spring 9 based on the amount of relative movement between the disk 11 and the optical sensor 12.

CT is a controller for analyzing and processing a pulse signal output from the optical sensor 12 of the encoder 10. In connection with the encoder 10, there is provided a torque measuring means for measuring the torque applied to the cylindrical body 1. Make up.

A selection means F is connected to the controller CT in addition to the display section D and the alarm section E described above.
The selection means F selects and sets a target torque To and an allowable error range R, which are criteria for determining the quality of the screw tightening torque, and inputs them to the controller CT.

FIG. 2 is a block diagram schematically showing the processing functions of the controller CT. In FIG. 2, reference numeral 21 denotes a reversible counter whose count value is increased / decreased (UP / DN). Sensor 1
It is measured as an amount of relative movement with respect to 2.

Numeral 22 denotes a rotation change detecting means, based on a two-phase output signal of the encoder 10, and a screw tightening bit 4.
A change in the relative rotation direction between the motor and the cylindrical body 1 is detected, and a rotation change detection signal V is generated.

Reference numeral 23 denotes storage means for storing the detected value of the screw tightening torque. In response to the rotation change detection signal V, the count value of the reversible counter 21 corresponding to the measured value of the encoder 10 is stored in the screw for the screw W to be measured. It is stored as the fastening torque.

Numeral 24 denotes torque determining means for determining whether or not the screw tightening torque for the screw to be measured W is normal. Whether or not the measured value stored in the storage means 23 is within the allowable error range R of the target torque To. Then, it is determined whether the screw tightening torque is normal or abnormal.

The display section D displays the measured value of the screw tightening torque read from the storage means 23. The alarm unit E is driven when the torque determination unit 24 determines that the screw tightening torque is abnormal, and notifies the occurrence of the abnormality.

FIG. 3 is a block diagram showing the selection setting function of the selection means F. In FIG. 3, the selecting means F includes a target setting unit 31 for setting a target torque To (a target value of the measured torque) and an allowable error setting unit 32 for setting an allowable error range R.

The target setting section 31 has a numerical value setting device 31a including a numeric keypad, a rotary switch or a digital switch. In the illustrated example, the numerical value setting device 31a
For example, a target torque To of a three-digit numerical value “123”
Is constituted by a digital switch capable of setting the. The allowable error setting unit 32 outputs, for example, 2%,
There is a rotary switch 32a for switching the error range between 5% and 10%.

FIG. 4 is a timing chart showing waveforms of pulse signals Pz, Pa and Pb output from the optical sensor 12 of the encoder 10. Here, a forward rotation pulse Pn and a reverse rotation pulse Pr generated in association with each of the pulse signals Pz, Pa and Pb are also shown.

The forward rotation pulse Pn and the reverse rotation pulse Pr are
It is generated based on each pulse signal by the processing in the controller CT. In FIG. 4, the case of the normal rotation waveform is taken as an example, where the normal rotation pulse Pn is a solid line and the reverse rotation pulse Pr is
Are indicated by broken lines.

Pz is a Z-phase pulse for detecting a reference point,
One pulse is generated each time the disk 11 makes one rotation.
Pa is an A-phase pulse, Pb is a B-phase pulse, and these constitute a two-phase pulse output from the optical sensor 12.

The A-phase pulse Pa and the B-phase pulse Pb are
In order to identify the operating direction of the encoder 10, the disk 11
The detection timings are shifted from each other by 90 ° according to the upper stripe pattern. FIG. 5 is a flowchart showing the reverse rotation detection processing operation by the rotation change detection means 22 in the controller CT.

In FIG. 5, S1 is a step for determining whether or not the A-phase pulse Pa is at the “1 (ON)” level.
Is a step of determining whether or not the B-phase pulse Pb has changed from the “1” level to the “0” level, and S3 is a step S1
This is a step of detecting the reverse rotation pulse Pr (see the broken line in FIG. 4) when YES is determined in S2 and S2.

Although not shown, if the logic level condition of the B-phase pulse Pb is inverted from "0 to 1" in the determination step S2 in FIG. 5, the forward rotation pulse Pn (FIG. (Refer to the solid line in).

That is, when the A-phase pulse Pa is at the “1” level, the logic level of the B-phase pulse Pb is changed from “0 →
1 ”, a forward rotation pulse Pn is generated, and B
When the logic level of the phase pulse Pb changes from “1 → 0”, a reverse rotation pulse Pr is generated.

Although the forward rotation pulse Pn and the reverse rotation pulse Pr are generated by the processing in the controller CT, they may be generated by a circuit module (not shown) built in the encoder 10.

Next, the operation of the first embodiment of the present invention will be described with reference to FIGS. First, FIG.
As described above, the cutting edge of the screw tightening bit 4 is inserted into the head of the screw W to be measured, and while the output state of the Z-phase pulse Pz displayed on the display unit D is checked, the cylindrical body 1 is increased. Rotate in the tightening direction.

As a result, the torque to be measured is transmitted to the screw W to be measured via the coil spring 9, the drive shaft 3 and the screw tightening bit 4, so that the screw W to be measured is further tightened. At this time, in the initial stage when a rotational force is applied to the cylindrical body 1, the screw tightening bit 4 and the measured screw W
Does not rotate immediately, and only the tightening of the coil spring 9 is performed.

Therefore, the optical sensor 1 of the encoder 10
2 rotates ahead of the disk 11 together with the inner wall of the cylindrical body 1, and the forward rotation pulse Pn associated with the disk 11
Generate

The elastic force of the coil spring 9 accumulates with the amount of rotation of the cylindrical body 1 and the optical sensor 12, and the torque applied to the screw tightening bit 4 varies depending on the degree of rotation. But increase in a stable state.

When the rotational torque of the cylindrical body 1 continues to increase, the tightening of the coil spring 9 further progresses, and the encoder 10 outputs a signal corresponding to the forward rotation pulse Pn, as shown in FIG.
Continue generating phase pulses.

Therefore, the addition counting circuit in the reversible counter 21 counts the two-phase pulse signal by integration. The current value of the reversible counter 21 is multiplied by a previously adjusted correction count, and the corrected count value (measured value) is displayed on the display unit D as the current drive torque.

When the frictional force between the male screw and the female screw of the measured screw W changes from the static friction region to the dynamic friction region, the screw tightening bit 4 urged by the coil spring 9 accumulates. Rotation in the tightening direction causes the disk 11 of the encoder 10 to rapidly follow the optical sensor 12.

As described above, the rotation of the disk 11 following the optical sensor 12 indicates that the disk 1
This is a phenomenon equivalent to the backward movement of the optical sensor 12 in the reverse rotation direction with respect to 1, and therefore, the reverse rotation pulse Pr is generated.

That is, in FIG. 5, the A-phase pulse Pa
Is determined to be at the logical “1” level (step S
1) If it is determined that Pa = 1 (that is, YES),
Subsequently, the B-phase pulse Pb changes from the logic “1” level to “0”.
It is determined whether or not the level has changed (step S2).

If it is determined in step S2 that the B-phase pulse Pb has changed from "1" to "0" (ie, YES), a reverse rotation pulse Pr is detected at this point (step S3), and FIG. Exits the processing routine.

In this case, the reverse rotation pulse Pr is used as a rotation change detection signal V (see FIG. 2), and the storage means 23 stores the count value of the reversible counter 21 at the time of generation of the rotation change detection signal V into a screw. It is stored as the tightening torque.

That is, when the peak torque Tp (see FIG. 13) is reached and the reverse rotation pulse Pr is generated, the rotation change detection means 22 generates a rotation change detection signal V, and the storage means 23 stores The count value after calibration of the current value is stored. The measured value stored in the storage means 23 is displayed on the display unit D as the peak torque value Tp of the measurement result.

The torque determination means 24 compares and determines the preset target torque To and the allowable error range R with the stored measurement value. If the measured value is abnormal, the alarm unit E is driven. An alarm display (or a buzzer for a predetermined time) is executed.

As described above, by interposing the coil spring 9 (spring mechanism) between the cylindrical body 1 and the screw tightening bit 4, a stable rotational force can be obtained through the elastic force of the coil spring 9. 4 can be given.

The cylindrical body 1 and the screw tightening bit 4 are connected via an encoder 10 having a disk 11 rotating integrally with the screw tightening bit 4 and an optical sensor 12 integrally rotating with the cylindrical body 1. By detecting the relative rotation amount and the rotation direction, the detection accuracy does not vary depending on how the operator applies force, and a highly accurate and highly accurate screw tightening torque can be detected.

Here, the coil spring 9 is set, for example, to have a maximum rated torque as a torque measuring device with a distortion amount of about 90 ° so as to be suitable for one wrist rotation operation of an operator. Shall be

By using the coil spring 9 having such an energy storing characteristic, when the rotation angle θ of the cylindrical body 1 increases and reaches the peak torque Tp of the screw W to be measured, the screw tightening bit 4 becomes , And rotates independently by a slight angle substantially proportional to the rotation angle θ.

The rotation speed of the screw tightening bit 4 at this time does not depend on the manual operation speed of the operator. Therefore, stable and highly accurate torque measurement can be realized by detecting the independent quick following operation of the screw tightening bit 4.

Further, the optical sensor 1 of the encoder 10 is used as the torque measuring means without using the expensive torque sensor 2.
Since the number of pulses generated from 2 is counted by the reversible counter 21 and the amount of distortion of the coil spring 9 is measured, an inexpensive torque measuring device can be realized.

Embodiment 2 In the first embodiment, the peak torque Tp is sensitively detected in response to one reverse rotation pulse Pr. However, for example, the peak torque Tp is continuously detected in order to avoid the influence of noise superimposed on the reverse rotation pulse Pr. The peak torque Tp may be detected when a plurality of reverse rotation pulses Pr are generated.

FIG. 6 is a block diagram showing a functional configuration according to a second embodiment of the present invention in which a torque measurement value is stored in response to a plurality of reverse rotation pulses Pr.
0 is a flowchart showing a processing operation of the controller according to the second embodiment of the present invention.

In FIG. 6, the configuration not shown is as described above (see FIG. 2), and the same components as those described above are denoted by the same reference numerals and will not be described in detail. CTa and 21a correspond to the controller CT and the reversible counter 21, respectively.

In this case, the controller CTa includes a first counter 21a functioning as a reversible counter, a normal rotation pulse generating means 22a for generating a normal rotation pulse Pn, a reverse rotation pulse generating means 22b for generating a reverse rotation pulse Pr, A reverse rotation amount counter 22c that generates a rotation change detection signal V based on the rotation pulse Pn and the reverse rotation pulse Pr.

The normal rotation pulse generating means 22a, the reverse rotation pulse generating means 22b and the reverse rotation amount counter 22c correspond to the rotation change detecting means 22 described above. The forward rotation pulse generating means 22a is provided in the cylindrical body 1 corresponding to the tightening direction.
Generates a forward rotation pulse Pn in response to the first rotation direction (forward rotation).

The reverse rotation pulse generating means 22b generates a reverse rotation pulse Pr in response to a second rotation direction (reverse rotation) of the cylindrical body corresponding to a direction opposite to the retightening direction. The reverse rotation amount counter 22c counts the reverse rotation pulse Pr and is reset by the normal rotation pulse Pn.
When the count value of r exceeds a predetermined value, the rotation change detection signal V
Is output.

As described above, when the circuit module in the encoder 10 includes the functions of the forward pulse generator 22a and the reverse pulse generator 22b, the forward pulse generator 22a and the reverse pulse generator 22a in the controller CTa are used. The generating means 22b is omitted.

The operation of the second embodiment of the present invention will be described below with reference to FIGS. In FIG. 7, first, when a worker presses a start button (not shown), the controller CTa performs initialization (step S10) prior to starting execution of a series of torque measurement operation processing routines, and Resets various parameters such as stored values and alarm displays.

Subsequently, a screw tightening bit 4 (see FIG. 1)
Is fitted to the screw W to be measured to start the rotation of the cylindrical body 1 (step S11), and the rotational force of the cylindrical body 1 is increased.

At this time, when the driving of the cylindrical body 1 is started, a natural state in which the Z-phase pulse Pz is generated from the encoder 10 (a state in which the coil spring 9 is not involved).
And then increase the drive torque.

The rotation of the cylindrical body 1 causes the coil spring 9 to be tightly wound, and the forward rotation pulse generating means 22a
The normal rotation pulse Pn generated from the (or the encoder 10) is integrated and counted by the first counter 21a.

On the other hand, when the reverse rotation pulse Pr is generated due to the fluctuation of the rotational force applied to the cylindrical body 1, etc.
The count value of the first counter 21a is decremented. As a result, the first counter 21a keeps holding the absolute rotational position from the zero phase (Z phase). The current value of the first counter 21a is multiplied by a correction count adjusted in advance, and is displayed on the display unit D as the current drive torque.

Eventually, the peak torque point time tp (FIG. 13)
), The reverse rotation pulse Pr generated from the reverse rotation pulse generating means 22b (or the encoder 10).
Are counted by the second counter 22c.

At this time, the controller CTa determines whether or not the number of reverse rotation pulses NPr has exceeded a predetermined value Nr (step S12), and NPr ≦ Nr (that is, Np).
If it is determined as O), the number of generations of the reverse rotation pulse Pr is regarded as the noise level, and the process returns to step S11 to continue the rotation of the tubular body 1.

On the other hand, if the number of reverse rotation pulses Pr is continuously generated by a predetermined amount and the number of reverse rotation pulses NPr exceeds a predetermined value Nr, it is determined in step S12 that NPr> Nr (that is, YES).

At this time, the number of generations NP of the reverse rotation pulse Pr
Since r is a high level of reliability, the controller CTa
, Assuming that the cylindrical body 1 is actually relatively reversed, and stores the calibrated count value of the first counter 21a in the storage means 23 as a measurement result (current measurement value) (step S13). This stored value is displayed on the display unit D as the peak torque Tp of the measurement result.

Subsequently, the current measured value stored in the storage means 23 is displayed on the display unit D (step S14), and it is determined whether or not the stored measured value is within the allowable error range R (step S14). S15).

If the stored measurement value is within the allowable error range R
If it is determined that the value is within the range (that is, YES), the screw tightening torque of the measured screw W (see FIG. 1) is normal, and the inspection routine of FIG. 7 ends.

On the other hand, in step S15, the stored measurement value deviates from the allowable error range R (ie,
If NO), it is considered that the screw tightening torque of the screw W to be measured is abnormal. Therefore, the alarm unit E is driven to display an alarm or sound a buzzer for a predetermined time (step S16). The inspection routine based on the torque measurement is ended.

FIGS. 8 to 10 are flowcharts focusing on the operations of the first counter 21a (reversible counter), the second counter 22c (reverse rotation counting counter), and the display unit D. FIG. 8 shows a reset operation based on the detection of the Z-phase pulse Pz, and shows a processing operation when the first counter 21a is reset by the Z-phase pulse Pz.

FIG. 9 shows an adding operation according to the detection of the forward rotation pulse Pn, and shows a processing operation when the first counter 21a is counted up and the second counter 22c is reset by the forward rotation pulse Pn. ing.

FIG. 10 shows a subtraction and an addition operation in response to the detection of the reverse rotation pulse Pr, and shows a processing operation when the first counter 21a is counted down and the second counter 22c is counted up by the reverse rotation pulse Pr. ing.

In FIG. 8, the controller CTa first determines whether there is a Z-phase pulse Pz (step S2).
1) If it is determined that there is no Z-phase pulse Pz (that is, NO), a standby state is established until the Z-phase pulse Pz is input.

If it is determined in step S21 that there is a Z-phase pulse Pz (ie, YES), the controller CTa resets the count value of the first counter 21a to 0 (step S22), and resets the current value of the first counter 21a. The display unit D displays a calibration count value obtained by multiplying the value by a predetermined magnification (step S23), and returns.

In FIG. 8, when the Z-phase pulse Pz is detected (step S21), the first counter 21a
Was reset (step S22), but the first counter 21a may be reset in conjunction with the start button for starting the measurement.

In FIG. 9, the controller CTa
First determines the presence or absence of the forward rotation pulse Pn (step S
31) If it is determined that the normal rotation pulse Pn is absent (that is, NO), the standby state is established until the normal rotation pulse Pn is input.

If it is determined in step S31 that the normal rotation pulse Pn is present (ie, YES), the first counter 21a is counted up (UP) (step S3).
2), the second counter 22c is reset (step S3)
3) Display the calibration count value of the first counter 21a on the display unit D (step S23), and return.

In FIG. 10, the controller CT
First, it is determined whether there is a reverse rotation pulse Pr (step S41), and there is no reverse rotation normal rotation pulse Pr (that is, N
If it is determined as O), a standby state is established until the reverse rotation pulse Pr is input.

If it is determined in step S41 that there is a reverse rotation pulse Pr (ie, YES), the first counter 21a is counted down (DN) (step S4).
2) The second counter 22c is counted up (UP) (step S43), the calibration count value of the first counter 21a is displayed on the display unit D (step S23), and the process returns.

The predetermined magnification for calibration multiplied by the count value of the first counter 21a is a correction value for converting the current value of the first counter 21a into a screw tightening torque. Obtained on the basis of actual measurement confirmation. This calibration conversion value is input in advance to a memory (not shown), and is used as a predetermined magnification in the correction calculation.

As shown in FIG. 9, the second counter 22c is cleared to 0 when the forward rotation pulse Pn is detected (step S3).
3), as shown in FIG. 10, when the reverse rotation pulse Pr is detected,
1 is added (step S43), and the amount of the continuous reverse rotation pulse Pr is counted. The count value of the reverse rotation pulse Pr thus obtained is used in the determination step S12 in FIG.

As described above, a plurality of continuous inversion pulses P
By detecting the peak torque Tp at the time of generation of r, redundancy is realized by slowing down the detection sensitivity, and noise resistance can be improved.

For example, even if a worker accidentally looses his hand during the rotation operation of the cylindrical body 1 and a slight reverse rotation pulse Pr is generated, erroneous detection of the peak torque Tp due to this is prevented. Can be.

By avoiding the delicate timing immediately before or immediately after the time tp of the torque peak point at which the torque tends to become unstable, the torque at the time when the static friction torque is changed to the dynamic friction torque is reliably measured as the peak torque Tp. The reliability can be further improved.

Embodiment 3 In the first embodiment, only the encoder 10 is used as the torque measuring means. However, a high-precision strain gauge type torque sensor 2 may be used in combination.

FIG. 11 is a cross-sectional view showing a sensor unit according to the third embodiment of the present invention in which a strain gauge type torque sensor 2 is used together.
The same components as those described above are denoted by the same reference numerals, and detailed description thereof is omitted.

In this case, the torque measuring means has a strain gauge type torque sensor 2 provided between the screw tightening bit 4 and the cylindrical body 1 in addition to the encoder 10.

The output of the torque sensor 2 is, as described above,
The device is calibrated individually according to the strain gauge characteristics at the stage of shipping the device so that a numerical value can be displayed in a predetermined torque unit via the amplification and digitizing circuit.

Since the configuration of the sensor unit according to the third embodiment of the present invention shown in FIG. 11 is a combination of FIGS. 1 and 12, the operation of the third embodiment of the present invention is the same as that described above, and therefore will be described. Is omitted.

In this case, since the peak torque Tp is detected from the outputs of the encoder 10 and the torque sensor 2, the reliability of the torque measurement is further improved, and even if one of the measuring means goes down, the other means is used. Can be backed up.

Embodiment 4 It should be noted that the first to the first embodiments
In 3, the measurement of the screw tightening torque by the retightening is described. However, a changeover switch (not shown) may be provided in the torque measuring device and used for measuring the loosening torque.

In this case, at the beginning of the start of driving, the above-described reverse rotation pulse Pr is generated as a normal rotation pulse based on the output pulse of the encoder 10, and at the time of transition from the static friction torque to the dynamic friction torque, the normal rotation pulse Pr is generated. Is generated as a reverse rotation pulse.

Therefore, for example, as described above (see FIG. 6)
The first counter 21a performs cumulative counting (UP counting) using the reverse rotation pulse Pr as the normal rotation pulse, and performs the normal rotation pulse P
Subtraction count (DN count) is performed using n as the reverse rotation pulse.

The second counter (reverse rotation amount counter) 22c counts the forward rotation pulse Pn as a reverse rotation pulse, and is reset by the reverse rotation pulse Pr. Further, in the above-described determination step S12 (see FIG. 7), the presence or absence of the normal rotation pulse Pn is determined as the presence or absence of the reverse rotation pulse.

Embodiment 5 FIG. It should be noted that the first to the first embodiments
In No. 3, the amount of distortion of the coil spring 9 is measured by the reversible counter 21 (see FIG. 2) or the reversible counter of the first counter 21a (see FIG. 6) using an incremental value method by two-phase pulses as the output signal processing of the encoder 10. However, an encoder other than the two-phase encoder may be used.

For example, a multi-bit absolute value encoder (not shown) may be used to detect the start of reverse rotation by logical determination of each bit and store the peak torque Tp at the time of detection of reverse rotation.

Embodiment 6 FIG. It should be noted that the first to the first embodiments
In 3, the coil spring 9 shown in FIG. 1 or FIG. 11 is used as the spring mechanism. However, as another spring mechanism, for example, a mainspring spring or a strip-shaped leaf spring may be used. Further, these various spring mechanisms may be replaced with those having appropriate elastic force according to the size of the screw W to be measured.

Embodiment 7 FIG. It should be noted that the first to the first embodiments
In FIG. 3, the sampling inspection by the manual operation of the worker has been described. However, the inspection may be replaced with an electric operation and used as an automatic inspection device in a production line.

In this case, an electric motor (not shown) for driving the cylindrical body 1 does not require torque control, and uses the simplest motor which merely performs a rotating operation and a stopping operation. As a result, the cost does not increase.

Embodiment 8 FIG. It should be noted that the first to the first embodiments
In 3, the controller CT or CTa stores the data indicating the pass or fail of the screw W to be measured, together with the screw tightening peak torque Tp sequentially detected after the start of the measurement, and further analyzes the stored data. Then, processing data such as variation in the detection result such as the peak torque Tp and standard deviation may be created and displayed on the display unit D, or may be printed out on a printer (not shown).

[0125]

As described above, according to the first aspect of the present invention, a screw tightening bit inserted into the head of a screw to be measured,
A screw tightening torque measuring device comprising: a cylindrical body for rotating a screw tightening bit; and torque measuring means for measuring a torque applied to the cylindrical body, wherein the torque measuring means includes a screw tightening bit and a cylinder. Spring mechanism that is provided between the cylindrical body and generates an elastic force to oppose the rotation direction of the cylindrical body, and the amount of distortion of the spring mechanism due to the relative rotation between the screw tightening bit and the cylindrical body , A rotation change detection means for detecting a reversal change in the relative rotation direction between the screw tightening bit and the cylindrical body based on an output signal of the encoder, and a rotation change detection signal from the rotation change detection means. And a storage means for storing the measured value of the encoder as a screw tightening torque for the screw to be measured in response to the Constant result can be obtained, screw tightening torque measuring device which prevents the occurrence of measurement variations due to differences in skill level of the workers is the effect obtained.

According to a second aspect of the present invention, in the first aspect, the encoder includes a disk having a two-phase striped slit row formed therein and rotating integrally with the screw tightening bit; A two-phase encoder having an optical sensor fixed in the tubular body so as to be opposed to the optical sensor, wherein the torque measuring means measures a relative movement amount between the disk and the optical sensor as a distortion amount of the spring mechanism. A high-precision measurement result irrespective of the rotation speed of the cylindrical body, and prevented the occurrence of measurement value variations due to differences in the skill levels of workers. There is an effect that a screw tightening torque measuring device can be obtained.

According to a third aspect of the present invention, in the first or second aspect, the torque measuring means is a strain gauge type torque sensor provided between the screw tightening bit and the cylindrical body. , The measurement result can be obtained with higher accuracy and higher reliability, and the effect of obtaining the screw tightening torque measuring device which prevents the occurrence of the measurement value variation due to the difference in the skill level of the workers can be obtained. is there.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the selection means for setting the target torque and the allowable error range, which are criteria for determining the quality of the screw tightening torque. And torque determining means for determining whether the screw tightening torque is normal or abnormal depending on whether the measured value stored in the storage means is within the allowable error range of the target torque, and determining whether the torque determining means is abnormal in the screw tightening torque. And a warning means that is driven when it is determined that the screw tightening torque can be checked with high reliability.

According to a fifth aspect of the present invention, there is provided a screw tightening torque measuring device according to any one of the first to fourth aspects, wherein the rotation change detecting means includes a cylinder corresponding to the direction of retightening the screw to be measured. Pulse generating means for generating a normal rotation pulse in response to a first rotation direction of the cylindrical body, and a reverse rotation pulse in response to a second rotation direction of the cylindrical body corresponding to a direction opposite to the retightening direction. And a reverse rotation amount counter that counts the reverse rotation pulse and is reset by the normal rotation pulse. The reverse rotation amount counter rotates when the count value of the reverse rotation pulse exceeds a predetermined value. A change detection signal is output, so highly accurate and highly reliable torque measurement results in the tightening direction can be obtained, preventing the occurrence of measurement value variations due to differences in the skill level of workers. Screw tightening torque measuring device has an effect to be obtained.

According to a sixth aspect of the present invention, in any one of the first to fourth aspects, the rotation change detecting means is provided on the first cylindrical body corresponding to the loosening direction of the screw to be measured. Forward rotation pulse generation means for generating a normal rotation pulse in response to the rotation direction, and reverse rotation pulse generation means for generating a reverse rotation pulse in response to a second rotation direction of the cylindrical body corresponding to the direction opposite to the loosening direction And a reverse rotation amount counter that counts the reverse rotation pulse and is reset by the normal rotation pulse. The reverse rotation amount counter outputs a rotation change detection signal when the count value of the reverse rotation pulse exceeds a predetermined value. As a result, a highly accurate and highly reliable torque measurement result in the loosening direction can be obtained, and a screw tightening torque measurement device that prevents the occurrence of measurement value variations due to differences in the skill levels of workers can be obtained. There is an effect.

According to a seventh aspect of the present invention, in the first aspect, the encoder is constituted by a multi-bit absolute value encoder, and the rotation change detecting means is based on a logical judgment of each bit of the encoder. , The reversal change of the relative rotation direction is detected, so that high-precision measurement results can be obtained regardless of the rotational operation speed of the cylindrical body. This has the effect of obtaining a screw tightening torque measuring device in which the above is prevented.

According to an eighth aspect of the present invention, in any one of the first to seventh aspects, an electric motor for applying a rotational force to the tubular body is provided, and the electric motor is controlled in torque. Since only the rotation operation and the stop operation are performed without performing, there is an effect that a screw tightening torque measuring device capable of obtaining a highly accurate and highly reliable torque measurement result at low cost is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing Embodiment 1 of the present invention together with a cross-sectional view of a sensor unit.

FIG. 2 is a functional block diagram showing the first embodiment of the present invention.

FIG. 3 is a block diagram illustrating functions of a selection unit according to the first embodiment of the present invention.

FIG. 4 is a timing chart showing an output signal waveform of the encoder according to the first embodiment of the present invention.

FIG. 5 is a flowchart for explaining the operation of the first embodiment of the present invention.

FIG. 6 is a functional block diagram showing a second embodiment of the present invention.

FIG. 7 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 8 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 9 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 10 is a flowchart for explaining the operation of the second embodiment of the present invention.

FIG. 11 is a configuration diagram showing Embodiment 3 of the present invention together with a cross-sectional view of a sensor unit.

FIG. 12 is a cross-sectional view showing a mechanism of a sensor unit of a conventional screw tightening torque measuring device.

FIG. 13 is a characteristic diagram showing a torque output characteristic of a conventional screw tightening torque measuring device.

[Explanation of symbols]

Reference Signs List 1 cylindrical body, 2 torque sensor, 4 screw tightening bit, 9 coil spring (spring mechanism), 10 encoder, 11 disk, 12 optical sensor, 21 reversible counter, 21a first counter (reversible counter), 22 rotation change detection Means, 22a forward rotation pulse generating means, 22b
Reverse rotation pulse generation means, 22c Second counter (reverse rotation amount counter), 23 storage means, 24 torque determination means, CT, CTa controller, D display section, E alarm section, F selection means, Pa, Pb two-phase pulse, Pn positive Reverse pulse, Pr reverse pulse, R allowable error range, To
Target torque, V rotation change detection signal, W Screw to be measured.

Claims (8)

[Claims] 1. A screw tightening bit inserted into a head of a screw to be measured, a cylindrical body for rotating the screw tightening bit, and a torque measuring means for measuring a torque applied to the cylindrical body. Wherein the torque measuring means is provided between the screw tightening bit and the cylindrical body and generates an elastic force so as to oppose the rotation direction of the cylindrical body. A spring mechanism, an encoder that detects an amount of distortion of the spring mechanism based on a relative rotation amount between the screw tightening bit and the tubular body, and the screw tightening bit based on an output signal of the encoder. Rotation change detection means for detecting a reversal change in the relative rotation direction with respect to the cylindrical body; and measuring the encoder in response to a rotation change detection signal from the rotation change detection means. Screw tightening torque measuring device, characterized in that said constituted by a storage means for storing a screwing torque about the measured screws. 2. The encoder according to claim 1, wherein the encoder includes a disk having a two-phase striped slit array formed therein and rotating integrally with the screw tightening bit, and the encoder is provided in the cylindrical body so as to face the disk. The torque measuring means includes a reversible counter for measuring a relative movement amount between the disk and the optical sensor as a distortion amount of the spring mechanism. The screw tightening torque measuring device according to claim 1, wherein: 3. The torque measuring unit according to claim 1, wherein the torque measuring unit includes a strain gauge type torque sensor provided between the screw tightening bit and the cylindrical body. Screw tightening torque measuring device. 4. A selecting means for setting a target torque and a permissible error range serving as a criterion for determining whether or not the screw tightening torque is good, and a measured value stored in the storage means is within an allowable error range of the target torque. A torque determining unit that determines whether the screw tightening torque is normal or abnormal, and an alarm unit that is driven when the torque determining unit determines that the screw tightening torque is abnormal. The screw tightening torque measuring device according to any one of claims 1 to 3. 5. A normal rotation pulse generating means for generating a normal rotation pulse in response to a first rotation direction of the cylindrical body corresponding to a tightening direction of the screw to be measured, Reverse rotation pulse generating means for generating a reverse rotation pulse in response to a second rotation direction of the cylindrical body corresponding to a direction opposite to the retightening direction; counting the number of the reverse rotation pulses and resetting by the forward rotation pulse 5. The reverse rotation amount counter outputs the rotation change detection signal when the count value of the reverse rotation pulse exceeds a predetermined value. 6. The screw tightening torque measuring device according to any one of the above. 6. The normal rotation pulse generating means for generating a normal rotation pulse in response to a first rotation direction of the cylindrical body corresponding to a loosening direction of the screw to be measured; Reverse rotation pulse generating means for generating a reverse rotation pulse in response to a second rotation direction of the cylindrical body corresponding to a direction opposite to the loosening direction; a reverse rotation which is counted by the reverse rotation pulse and reset by the normal rotation pulse 5. The reverse rotation amount counter outputs the rotation change detection signal when the count value of the reverse rotation pulse exceeds a predetermined value. 6. The screw tightening torque measuring device according to any one of the above. 7. The encoder according to claim 1, wherein the encoder comprises a multi-bit absolute value encoder, and wherein the rotation change detecting means detects an inversion change of the relative rotation direction based on a logical determination of each bit of the encoder. The screw tightening torque measuring device according to claim 1, wherein: 8. A motor according to claim 1, further comprising an electric motor for applying a rotational force to said cylindrical body, wherein said electric motor performs only a rotation operation and a stop operation without torque control. 7. The screw tightening torque measuring device according to any one of 7 to 7.