JP2002039885A - Bolt fastener with inspection function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a bolt fastener itself to determine whether or not bolt fastening is sufficient. SOLUTION: The fastener, by which a nut subjected to primary fastening (temporary fastening) is firmly fastened through the drive of a motor, has a differentiating circuit for differentiating the driving current of the motor, a primary fastening torque detection circuit, and a nut fastening angle checking circuit. The primary fastening torque detection circuit and the nut fastening angle checking circuit compare variation in a differential value of the differentiating circuit with initial experimental data to calculate the amount of primary fastening torque and the rotational angle of the nut so as to determine whether or not bolt fastening is sufficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric bolt tightening machine having a function of determining whether or not a bolt is properly tightened.

[0002]

2. Description of the Related Art Structural high-strength bolts (hereinafter, simply referred to as bolts) used for joining steel structures such as buildings and bridges are provided with breaking projections at the tip of a screw shaft. When the bolt is tightened by a special tightening machine, the pin tail of the bolt is broken at the notch at the base, so it can be seen at a glance whether or not the tightening is completed. However, in actual construction, due to an abnormality in the manufacture of the bolt or an abnormality during the construction, there is a case where the bolt is not properly tightened even if the pin tail of the bolt is broken.

[0003] In order to discover the above-mentioned tightening abnormality, it is prescribed that the tightening work is performed in the process of primary tightening → marking → final tightening visual inspection (Building Standard Specifications J
ASS6 steel work). The primary tightening is to be carried out by a primary tightening dedicated tightening machine so that the tightening member is in close contact. The marking is to make a mark over a bolt, a nut, a washer, and a member to be fastened. The final tightening is to tighten until the pin tail is broken by a tightening machine. The visual inspection is to check whether or not the bolt is properly tightened by checking the displacement of the mark after the tightening.

[0004] However, marking is expected to be mechanized, but is not realized, and it takes a lot of time for manual marking and visual inspection, which is uneconomical.
In addition, depending on the work position, accuracy may be lacking or oversight may occur, resulting in poor reliability. The present invention clarifies a bolt tightening machine having a function of automatically determining whether a tightened state is acceptable when a bolt is tightened.

[0005]

SUMMARY OF THE INVENTION A bolt tightening machine according to the present invention is a tightening machine for performing a main tightening of a nut to which a member to be tightened has been temporarily tightened (temporarily tightened) in cooperation with a bolt by driving a motor. , A primary tightening torque detection circuit, and a nut tightening angle pass / fail determination circuit. The primary tightening torque detection circuit sets the angle when the differential value of the current differentiating circuit passes from the negative value to the zero point and changes to a positive value (final tightening start point) as θ0, and when the angle exceeds a predetermined angle from θ0. The primary differential torque value is obtained by comparing the current differential value with the data indicating the relationship between the current differential value and the primary tightening torque amount. The nut tightening angle acceptance / rejection determination circuit determines a nut tightening rotation angle θ1 when the differential value reaches a differential value corresponding to a predetermined tightening completion time after the differential value reaches a maximum after θ0, and θ1−θ0. Whether the nut tightening angle is acceptable or not is determined based on whether the angle is within a range of a preset angle from the primary tightening torque value and the length under the neck of the bolt.

[0006]

[Function and Effect] By differentiating the drive current of the motor during the tightening operation, the change in the load on the motor due to the change in the tightening load becomes very easy to understand. Can be determined accurately.
In addition, the final fastening start point can be accurately detected without being affected by the familiarity of the tightening machine. The amount of twist of the bolt itself during tightening differs depending on the difference in the length under the neck of the bolt. Although this cannot be ignored in determining whether the tightened state is acceptable or not, the accuracy of the determination is further improved because the nut tightening angle acceptance / rejection determination circuit makes the determination in consideration of the length under the neck of the bolt.
Each time one bolt is tightened, the tightening inspection is automatically performed, so that there is no omission of the inspection. Further, it is not necessary to perform a laborious manual operation for marking the bolt, the nut, the washer and the member to be fastened as in the related art. Even if the mark is provided, only the mark indicating that the primary fastening has been completed is sufficient.
Since this marking is simple and easy to mechanize, if the primary tightening machine is provided with the simple marking function, further labor saving is possible.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The tightening machine of the present invention has the following four inspection functions. Whether the amount of torque at the time of primary tightening is within the appropriate range. At the time of the final tightening of the next item, since the nut rotation angle varies depending on the magnitude of the primary tightening torque, the primary tightening torque is inspected at the first stage of the final tightening. Whether the rotation angle of the nut in the final tightening is within the appropriate range corresponding to the specified length under the neck of the bolt. When the amount of primary tightening torque and the member to be fastened are known, the rotation angle of the nut for securing the specified tightening force is proportional to the length under the neck. The relationship between the length under the neck and the angle amount in a normal case is obtained in advance, and the amount is compared with the amount to check whether or not it is normal. Whether the maximum torque during final tightening is within the appropriate range. Since the maximum tightening torque of the bolt is almost constant even if the bolt manufacturer is different, a normal range is defined and compared with the amount to check whether the bolt is normal. Whether the pintail break angle is within the appropriate range. When the bolt reaches the specified tightening torque, a torsion break occurs at the notch at the base of the pin tail,
Although the angle in the maximum torque region (= breaking angle of the pin tail) is substantially constant, this angle increases when an abnormality such as the thread portion of the bolt yields earlier than the notch portion occurs.

Specific Inspection Means In order to determine the four inspection items described in the preceding paragraph, the present invention has implemented the following three means. First Embodiment: Tightening current and rotation angle characteristics of a tightening machine are used. Second Embodiment: The tightening speed and the rotation angle characteristics of the tightening machine are used. Third Embodiment A tightening torque and a rotation angle characteristic of a tightening machine are used. This will be specifically described below.

"Example 1" (Utilization of Tightening Current and Rotational Angle Characteristics of Tightening Machine ) Configuration of Bolt Tightening Machine As shown in FIGS.
The inner socket can be retracted through the anti-licking mechanism (12) concentrically with the outer socket (11) protruding from the tip of (1).
(13) is deployed, and both sockets (11) and (13) are planetary gear mechanisms.
The two output shafts (14) are connected to an internal gear (14d) meshed with a planetary gear (14c) and a planetary gear support frame (14a) in the embodiment. Motor (16) via planetary gear mechanism (14) via gear train (15)
As shown in FIG. 3, a pin tail (21) of a bolt (2) is attached to an inner socket (13) and an outer socket (11) as shown in FIG.
When the bolts and nuts are tightened by applying rotational forces in opposite directions to each other in a state where the nuts (22) are fitted to the back, respectively, the pin tails (21) are broken. From the start of the motor to the start of actual tightening, a mechanism is installed in which the socket idles at a predetermined angle or more, in this embodiment, at least 20 °, and the mechanism slides the inner socket (13) in the axial direction. Holder (1
A known mechanism in which a play of at least 20 ° is provided in the rotational direction between the planetary gear support frame (3a) and the planetary gear support frame (14a), and is biased in one direction by a torsion spring (14b) (JP-A-57-83381, etc.) Has been implemented. A pin tail discharge rod (17) is provided concentrically with the two sockets (11) and (13) so as to be able to advance and retreat, and as shown in FIG. 3, when the inner socket (13) is pushed back by the pin tail (21) and retreats, The discharge rod (17) is also pushed against the spring (17a) and retreats, pulling the pin tail (21) remaining in the inner socket (13) after the tightening is completed and pulling the discharge lever (17b) Thus, the holding of the discharge rod (17) is released, and the discharge rod (17) is advanced by the spring force to discharge the pin tail (21). The tightening machine has a built-in marking device for marking an end face of the nut (22) with respect to the improperly tightened bolt.

In the marking device of the embodiment, a marker (3) is provided so as to penetrate the peripheral wall of the inner socket (13) and to be slidable in parallel with the axis of the socket, and a coil spring is provided at the rear end of the marker (3). The mark pins (32) are connected in a straight line via (31). The marker (3) is a felt body and is soaked with ink. The marker (3) slightly protrudes from the front end face of the inner socket (13), and the mark pin (32) is the inner socket.
(13) Projecting greatly from the rear end. Planetary gear mechanism (14)
A cylindrical shaft (33) is provided by penetrating through the axis of the cylindrical shaft and slidably fitted to the discharge rod (17), and a hitting head is provided at the front end of the cylindrical shaft (33).
(33a) is projected. An enlarged thickness portion (33b) is formed at the rear end of the cylindrical shaft (33), and a spring (33c) is applied to the enlarged portion (33b) to constantly urge the cylindrical shaft (33) backward. At the rear of the housing (1), the cylinder shaft
Cover the front of the thickened part (33b) of (33) with the electromagnetic coil (3
Deploy 4). By energizing the electromagnetic coil (34) in response to a tightening failure signal from the computer (4) described later, the cylinder shaft (33) moves forward against the spring (33c),
(33a) hits the mark pin (32) to protrude the marker (3), so that the end face of the nut (21) can be marked. The ink can be supplied to the marker (3) from the opening side of the inner socket (13).

As shown in FIG. 1, a computer (18) is connected to a portion (18) connecting the grip (10) of the tightening machine and the tip of the motor (16).
(4) Bolt length input section (41), multiple indicator lamps
(LED) (42) is provided. The tightening machine is provided with a CT sensor (not shown) for detecting a current value of the motor.
The motor (16) has one rotation of the motor for several pulses (in the embodiment, 1 pulse).
The rotation sensor (19) that detects as (pulse) is linked,
A signal is sent to each computer (4). Motor 1
The number of pulses for rotation is determined by a preliminary experiment when the rotation speed and reduction ratio of the motor are different. The motor is driven by the trigger switch (16a). The under-neck length input section (41) improves the accuracy of the pass / fail judgment of bolt tightening by manually inputting each time the operator changes the under-neck length of the bolt. It is of course desirable to enter the actual length and correspond to the actual length, but if accuracy allows, select from a range of about 2 to 5 steps such as short, standard, long, etc. Can be. It should be noted that a difference in the nominal diameter of the bolt can be dealt with by using a dedicated tightening machine for the nominal diameter. In addition, it is possible to provide a changeover switch (not shown) to make the bolt compatible with two or more bolts having different nominal diameters.

The computer (4) inputs the pulse detected by the rotation sensor (19) and the current value (actually converted to voltage) detected by the CT sensor, and decelerates the tightening machine. The output angle of the tightening machine is calculated from the ratio (secured as stored data), and the current differential value (ΔI / Δθ) is calculated using the angle increment Δθ per unit time and the current increment ΔI. As an additional function, the power supply voltage supplied to the tightening machine is measured. It is not necessary.

Inspection judgment A bolt having a nominal diameter of 22 mm and a neck length of 85 mm is subjected to a primary tightening torque of 1000 kg-cm, 2000 kg-cm, and 3000 kg-cm.
In this case, the final tightening was performed. Inspection determination at that time was performed after the main fastening, and the inspection determination at that time will be described based on the current waveform at the time of member tightening in FIG. 5 and the current differential waveform at the time of member tightening in FIG. 5 and 6, the number of pulses obtained from the motor shaft is added and accumulated in a predetermined cycle (for example, 10 ms, which is changed according to the performance of the computer and the reduction ratio of the tightening machine), and the motor rotation is calculated. Is converted into an angle based on the reduction ratio of the socket with respect to. The current axis in FIG. 5 is obtained by detecting the current value of the motor at the above-described predetermined cycle, and detecting the current by the CT sensor and converting the output voltage of the CT sensor into a current value. The differential axis in FIG. 6 represents the relative value (ΔI: 1 from the current value) of the current data taken in each of the predetermined cycles.
The value obtained by subtracting the value before the cycle) is used as the relative value (Δ
θ) (ΔI / Δθ). Note that the current waveform of the primary tightening torque of 1000 kg-cm is displayed at points in the above-described predetermined cycle, but other current waveforms are connected as solid lines between the points and are displayed as continuous lines having different thicknesses.

Determination Step The inspection determination step will be described in detail with reference to the block diagram of FIG. 7 and the flowchart of FIG. (1). Enter the length under the neck (a) : Enter the length under the neck of the bolt,
Input to the input section (41). (2) Start tightening (b) : Pin tail (21) and nut (2)
Fit sockets (13) and (11) in 2). Nuts at this stage (22)
If the protrusion length of the bolt from is too short, the marker (3) abuts on the nut end face, and a rejection display is made before the final tightening. At the end of the primary tightening, the protruding length of the bolt from the nut (22) does not reach the expected length, that is,
There is a problem in the introduction of the primary tightening torque value or the selection of the length under the neck of the bolt, and it is natural that a rejection is displayed. Turn on the trigger switch (16a) and start the motor (16). The switch shall not be turned off until tightening is complete or abnormal stop. Voltage measurement at the same time when the trigger switch is turned on (c)
Pulse measurement (d) and current measurement (e) are started. At the same time, calculation of the current derivative is executed. (3) Power supply voltage judgment (g) : Power supply voltage measurement circuit (406) until the trigger switch is turned on and the angle θ0 is detected.
To monitor the power supply voltage and determine whether the voltage is within ± 10% of the reference voltage. If the voltage exceeds ± 10% of the reference voltage, the test is rejected. At that time, a rejection is displayed after the forced stop (power supply to the motor is cut off) or the tightening is completed. (4). Detection of the angle θ0 (h) : When the current differential value (ΔI / Δθ) calculated by the current differentiating circuit (400) changes from a negative value to a positive value beyond the zero point after the trigger switch is turned on. Is θ0. (5). Judgment of idle running (i) : Angle θ after starting the motor
If the angle is less than the predetermined angle (20 ° in the embodiment) until the angle reaches 0, sufficient idling time cannot be secured, so the current change at the start of tightening differs from the standard state, and the primary tightening torque value is calculated and the nut rotation angle is detected. Can not be done. If the idle running angle determined by the idle running determination circuit (401) is equal to or less than the predetermined angle, the calculation of the primary tightening torque value and the inspection of the nut rotation angle are not performed, and after the tightening, an indication of an untested state is displayed. Note that the angle for judging pass / fail of the idle running is an angle until the inrush current when the motor starts is substantially stabilized, and differs depending on the reduction ratio of the tightening machine. I do. (6). Primary tightening torque value (j) : The primary tightening torque detecting circuit (402) detects a current differential value when the angle exceeds a predetermined angle (8 ° in the embodiment) from θ0, and performs an experiment in advance. The primary tightening torque is obtained by comparing the current differential value obtained in the above with the relational expression of the primary tightening torque or a data table. The predetermined angle from θ0 can be set in the range of 5 to 15 ° in the embodiment, but the setting changes depending on the tightening condition of the bolt and the characteristics of the tightening machine, and when the reduction ratio changes, a larger angle is set. It could be. In addition to the method of obtaining the primary tightening torque, in addition to the embodiment, the maximum current differential value is detected, and the maximum current differential value and the primary tightening torque amount, or the angle from θ0 at the maximum current differential value and the primary tightening torque are detected. It can be obtained from the relationship of the torque amount. (7). Detection of Angle θ1 (k) : The angle at which the current differential value becomes the maximum after the angle θ0, then decreases, and reaches a predetermined amount (a value obtained by a preliminary experiment) is defined as θ1. (8). Nut rotation angle (l) : The angle θ1−θ0 is calculated by the nut tightening angle pass / fail determination circuit (403), and the primary tightening torque value and the length under the neck based on the result obtained in advance by an experiment are calculated. A pass / fail judgment is made by comparing the angle of the calculation formula or the data table used as an index with the measured angle θ1−θ0.
The primary tightening torque value uses the value obtained in the above step (6). In the case of rejection, rejection is displayed after tightening is completed. (9) Maximum current value detection (m) : Maximum current judgment circuit (404)
Thereby, it is monitored whether or not the maximum current value after the detection of the angle θ1 falls within the range between the lower limit current value and the upper limit current value set in advance. If the current value exceeds the upper limit current value, the tightening machine will be damaged. If the current value does not exceed the lower limit current value and reaches the maximum current value, it is rejected due to insufficient torque, and a rejection is displayed after the tightening is completed. (10). Abnormal elongation judgment (n) : Abnormal elongation judgment circuit (405)
As a result, the current value when the angle θ1 exceeds the angle (30 ° in the embodiment) obtained by the preliminary inspection from the angle θ1 is detected. In the embodiment, the current value is 9% when the maximum current value is 100%.
Check if it is less than 5%. If it is 95% or more, it is determined that abnormal elongation has occurred, forcibly stopped, and a defect is displayed. 95% or less shall be accepted. Note that the angle from θ1 for determining abnormal elongation and the ratio to the maximum current value (in the embodiment, 95%).
%) Depends on the characteristics of the bolt and the tightening machine, so set a value that has been investigated in advance. In addition, in addition to the above, the method of performing the abnormal elongation determination is to detect the maximum current value after θ1, detect the angle when the current value decreases to a predetermined ratio, and determine whether the angle is within the preset angle. It is possible to judge by whether or not. (11). Indication of failure (o) : In the above inspection process, when an abnormality such as “fail”, “forced stop”, “not inspected” or the like occurs, the failure indication is classified by abnormality cause so that the cause can be understood. The display lamp (LED) (42) is turned on. In addition, a buzzer (not shown) may be provided in the tightening machine to notify an operator of a sound that the tightened bolt is abnormal. (12) Marking (p) : When the inspection result is unacceptable, a signal is output from the computer, and the electromagnetic coil (34) is energized by a switch operated by the signal. As described above, the marker 3 containing ink is pressed against the nut 22 by the action of the magnetic force of the energized electromagnetic coil. The nut is marked to indicate a defect by the above method. (13) Reset (q) : When the tightening has been completed normally, when the trigger switch (16a) is turned off, it returns to the initial state and waits for the next bolt tightening. In the case of an abnormal end, for the lighting (buzzer) and marking of the lamp (LED), the failure display is maintained for a few seconds even after the trigger switch is turned off, and then the initial state is restored. However, the lighting of the defective lamp may be continued until the next time the trigger switch is turned on.

FIG. 9 shows a specific example of the nut rotation angle determination in the step (8). Nominal diameter 22mm, length under the neck 85
mm bolt, the primary tightening torque is 1000kg-cm, 2000kg-cm,
In the case of 3000 kg-cm, after marking the bolts, nuts, washers, and the members to be fastened, the final tightening was performed.A: The rotation angle of the nut (visually measured using an angle gauge) Angle) B: A graph showing the relationship with the nut rotation angle (θ1−θ0) obtained from the data of the current derivative of the tightening machine.
Large black circles have primary tightening torques of 1000kg-cm, 2000kg-cm,
Average value for 15 bolts of 3000 kg-cm. Both the case of visual observation and the case of data fall within the range of ± 5 °, which is the range of error by visual observation. Obviously there is no.

"Second Embodiment" (Utilizing Tightening Speed and Rotation Angle Characteristics of Tightening Machine ) Configuration of Bolt Tightening Machine The bolting machine of the first embodiment can be omitted from the CT sensor.

The computer (4) calculates the output angle of the tightening machine from the pulses detected by the rotation sensor (19) and the reduction ratio of the tightening machine, and the motor makes one rotation based on the time between the pulses. Measure time and convert to speed. Using the angle increment Δθ and the speed increment Δν per unit time, the speed differential value (Δν
/ Δθ) is calculated. As an additional function, the power supply voltage supplied to the tightening machine is measured. It is not necessary.

Inspection judgment A bolt having a nominal diameter of 22 mm and a neck length of 85 mm is subjected to a primary tightening torque of 1000 kg-cm, 2000 kg-cm, and 3000 kg-cm.
In this case, the final tightening was performed. Regarding the inspection judgment at that time, the velocity waveform at the time of member tightening in FIG.
A description will be given based on the speed differential waveform at the time of member tightening. As in the case of the first embodiment, the angle axes in FIGS. 10 and 11 are converted into angles based on the reduction ratio of the socket with respect to the motor rotation and displayed. The speed axis in FIG. 10 detects the time for one rotation of the motor at a predetermined cycle (10 ms in the embodiment, which is changed according to the performance of the computer and the reduction ratio of the tightening machine, etc.). Is the value counted by the reference clock. In this case, the count value increases as the speed decreases. In the embodiment, "count maximum value-count value" is set to make it easier to understand, and the data becomes smaller as the speed becomes slower. When displaying the graph, the maximum speed after the start of tightening is displayed as 100%. I have. The differential axis in FIG. 11 indicates the relative value of the speed data taken in each of the above-described predetermined cycles in the same manner as in the first embodiment.
(Δν) divided by the relative value (Δθ) of the angle data (Δν
/ Δθ). The waveform display is the same as in the first embodiment.

Determination Process Referring to the block diagram of FIG. 12 and the flowchart of FIG.
The details of the inspection determination process will be described in the order of the first embodiment. (1) Input of length under neck (a) : Same as in the first embodiment. (2) Tightening start (b) : Same as in the first embodiment. (3) Power supply voltage judgment (g) : Same as in the first embodiment. However,
Current measurement should be read as speed measurement. (4). Detection of angle θ0 (h1) : The speed differential value (Δν / Δθ) calculated by the speed differential circuit (400a) falls below the zero point from the positive value and changes to a negative value after the trigger switch is turned on. The angle at this time is defined as θ0. (5) Idling (i) : Same as in the first embodiment. (6). Primary tightening torque value (j1) : The primary differential torque detection circuit (402a) detects a velocity differential value when the angle exceeds a predetermined angle (8 ° in the embodiment) from θ0, and performs an experiment in advance. The primary tightening torque amount is obtained by comparing the speed differential value obtained in the above with the relational expression of the primary tightening torque amount or a data table. The predetermined angle from θ0 can be set in the range of 5 to 15 ° in the embodiment, but the setting changes depending on the tightening condition of the bolt and the characteristics of the tightening machine, and when the reduction ratio changes, a larger angle is set. It could be. In addition to the method of obtaining the primary tightening torque, the maximum speed differential value is detected in addition to the embodiment, and the maximum speed differential value and the primary tightening torque amount, or the angle from θ0 at the maximum speed differential value and the primary tightening torque value are detected. It can be obtained from the relationship of the torque amount. (7) Detection of angle θ1 (k1) : The angle at which the velocity differential value becomes minimum after angle θ0, then rises, and reaches a predetermined amount (a value obtained by a preliminary experiment) is defined as θ1. (8) Nut rotation angle (l) : Same as in the first embodiment. (9). Maximum current value detection (m1) : This corresponds to the maximum current detection of the first embodiment, and the minimum speed after the angle θ is detected by the minimum speed determination circuit (404a) is equal to the preset lower limit speed. It monitors whether it is within the upper limit speed range. If the speed is lower than the lower limit speed, the tightening machine will be damaged. If the minimum speed is reached without exceeding the upper limit speed, it will be rejected due to insufficient torque,
After tightening is completed, a rejection is displayed. (10). Abnormal elongation judgment (n1) : Abnormal elongation judgment circuit (405)
According to a), the speed when the angle θ1 exceeds the angle (30 ° in the embodiment) obtained by the preliminary inspection is detected. In the embodiment, the difference between the speed at the angle θ0 and the minimum speed is 1
When the speed is set to 00%, it is checked whether the speed is increased by 5% or more from the minimum speed. If it is 5% or less, it is determined that abnormal elongation has occurred, and the forced stop is performed, and a rejection is displayed. Pass 5% or more. Note that the angle from θ1 and the ratio to the minimum speed (5% in the embodiment) for determining abnormal elongation differ depending on the characteristics of the bolt and the tightening machine, so that a value checked in advance is set. In addition, the method of performing the abnormal elongation determination is, in addition to the embodiment, θ
It is also possible to detect the minimum speed after 1 and then detect the angle at which the speed has decreased to the predetermined ratio, and determine whether the angle is within the preset angle. (11) Defect indication (o) : Same as in the first embodiment. (12). Marking (p) : Same as in Example 1. (13) Reset (q) : Same as in the first embodiment.

[Embodiment 3] (Utilizing tightening torque and rotation angle characteristics of the tightening machine ) Constitution of the bolt tightening machine The bolt tightening machine has a torque sensor as shown in FIGS.
(5) is added and the CT sensor is omitted. As shown in FIG. 18, the torque sensor is a known torque sensor (5).
It can be arranged on the shaft of the sun gear (14a) of the planetary gear mechanism (14). This is one in which two types of grooves (51) and (52) having opposite twisting directions are machined in a shaft portion, and two annular coils (53) and (54) are provided so as to surround the shaft portion. A dielectric electromotive voltage is generated from the reverse magnetostriction effect on the grooves (51) and (52) due to the application of the torque to the shaft portion, and a voltage output proportional to the torque can be obtained.

Computer The computer (4) calculates the output angle of the tightening machine from the pulse detected by the rotation sensor (19) and the reduction ratio of the tightening machine, and calculates the torque value detected by the torque sensor. Using the angle increment Δθ and the torque increment ΔT per unit time from
Calculate the torque differential value (ΔT / Δθ). As an additional function, the power supply voltage supplied to the tightening machine is measured. It is not necessary.

Inspection judgment A bolt having a nominal diameter of 22 mm and a neck length of 85 mm was subjected to a primary tightening torque of 1000 kg-cm, 2000 kg-cm, and 3000 kg-cm.
In this case, the final tightening was performed. The inspection determination at that time will be described based on the torque waveform at the time of member tightening in FIG. 14 and the differential torque waveform at the time of member tightening in FIG. The angle axes in FIG. 14 and FIG. 15 are converted into angles based on the reduction ratio of the socket with respect to the motor rotation in the same manner as in the first embodiment. The torque axis in FIG. 14 indicates a value obtained by converting the output voltage from the torque sensor into a torque value. The differential axis in FIG. 15 indicates the relative value of the torque data (Δ
T) divided by the relative value (Δθ) of the angle data (ΔT / Δ
θ). The waveform display is the same as in the first embodiment.

Determination Process Referring to the block diagram of FIG. 16 and the flowchart of FIG.
The details of the inspection determination process will be described in the order of the first embodiment. (1) Input of length under neck (a) : Same as in the first embodiment. (2) Tightening start (b) : Same as in the first embodiment. (3) Power supply voltage judgment (g) : Same as in the first embodiment. However,
Current measurement should be read as torque measurement. (4). Detection of angle θ0 (h2) : Torque differentiation circuit (400b)
The angle at which the torque differential value (ΔT / Δθ) calculated by the above becomes maximum after the trigger switch is turned on is defined as θ0. (5) Judgment of idle running (i) : Not required when using a torque sensor. (6). Primary tightening torque value (j2) : The primary tightening torque detection circuit (402b) calculates the maximum torque differential value and a relational expression or data table of the torque differential value and the primary tightening torque amount obtained by an experiment in advance. , The primary tightening torque is obtained. (7) Detection of the angle θ1 (k2) : The angle at which the torque differential value decreases after the angle θ0 and reaches a predetermined amount (a value obtained by a preliminary experiment) is defined as θ1. (8) Nut rotation angle (l) : Same as in the first embodiment. (9). Maximum torque detection (m2) : This corresponds to the maximum current detection of the first embodiment, and the maximum torque value after detection of the angle θ1 is determined by the maximum torque determination circuit (404b) as the lower limit torque value set in advance. It is monitored whether it falls within the range of the upper limit torque value. If the torque exceeds the upper limit, the tightening machine will be damaged. If the maximum torque is reached without exceeding the lower limit torque value, it is rejected due to insufficient torque, and a rejection is displayed after the tightening is completed. (10). Abnormal elongation judgment (n2) : Abnormal elongation judgment circuit (405)
According to b), the torque value when the angle θ1 exceeds the angle (30 ° in the embodiment) obtained by the preliminary inspection from the angle θ1 is detected. In the embodiment, it is checked whether or not the torque is 95% or less when the maximum torque value is 100%. If it is 95% or more, it is determined that abnormal elongation has occurred and forced stop is performed, and a rejection display is made. 95% or less shall be accepted. Note that the angle from θ1 and the ratio to the maximum torque value (95% in the embodiment) for determining abnormal elongation differ depending on the characteristics of the bolt and the tightening machine, and therefore, a value checked in advance is set. In addition, in the method of performing the abnormal elongation determination, in addition to the embodiment, the maximum torque value after θ1 is detected, and then the angle at which the torque value decreases to a predetermined ratio is detected. If it passes, if it is more than the set angle, it is possible to judge that it is abnormal extension. (11) Defect indication (o) : Same as in the first embodiment. (12). Marking (p) : Same as in Example 1. (13) Reset (q) : Same as in the first embodiment.

In the present embodiment, the bolts are specified as a set including bolts and nuts, and bolt tails for fastening steel structures for buildings and bridges having almost no variation in tightening characteristics even if the manufacturer is different. Although it was a bolt,
Of course, it can be used for fastening bolts (including bolts without pin tails) exhibiting similar fastening characteristics.
In the embodiment, the idle running angle of the socket is set to 20 ° or more. However, this is a case limited to the present embodiment, and when the nominal diameter and the tightening machine are different, even if the idle running angle is small, The waveforms in FIGS. 5, 6, 10, and 11 may appear normally.
Bolt tightening machines with inner and outer sockets are designed to run to some extent in order to cope with the phase shift between the nut and the pin tail. There may not be. The present invention is not limited to the configuration of the above embodiment, and various modifications are possible within the scope of the claims.

[Brief description of the drawings]

FIG. 1 is a front view of a bolt tightening machine.

FIG. 2 is a sectional view of a main part of a bolt tightening machine before tightening.

FIG. 3 is a sectional view of a main part of a bolt tightening machine in a state where a bolt and a nut are engaged.

FIG. 4 is a sectional view of a main part of the bolt tightening machine in a state where a mark is applied to a nut.

FIG. 5 is a diagram of a current waveform when a member is tightened.

FIG. 6 is a diagram of a current differential waveform according to the first embodiment;

FIG. 7 is a determination block diagram in the case of using current data.

FIG. 8 is a flowchart of the above.

FIG. 9 is a graph of a specific example of a viewing angle and a determination angle.

FIG. 10 is a diagram of a speed waveform at the time of member tightening.

FIG. 11 is a diagram of a velocity differential waveform according to the first embodiment;

FIG. 12 is a determination block diagram in the case of using speed data.

FIG. 13 is a flowchart of the above.

FIG. 14 is a diagram of a torque waveform when a member is tightened.

FIG. 15 is a diagram of a torque differential waveform according to the first embodiment;

FIG. 16 is a determination block diagram in the case of using torque data.

FIG. 17 is a flowchart of the above.

FIG. 18 is a sectional view of a tightening machine incorporating a torque sensor according to another embodiment.

[Explanation of symbols]

 (11) Outer socket (13) Inner socket (16) Motor (19) Rotation detection sensor (3) Marker (4) Computer (40) Bolt neck length input section

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[Procedure amendment]

[Submission date] November 2, 2000 (200.11.
2)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

Inspection judgment A bolt having a nominal diameter of 22 mm and a neck length of 85 mm is subjected to a primary tightening torque of 1000 kg-cm, 2000 kg-cm, and 3000 kg-cm.
In this case, the final tightening was performed. The inspection determination at that time will be described based on the current waveform at the time of member tightening in FIG. 5 and the current differential waveform at the time of member tightening in FIG. The angular axes in FIGS. 5 and 6 are obtained by adding and accumulating the number of pulses obtained from the motor axis at a predetermined cycle (for example, 10 ms, which is changed according to the performance of the computer and the reduction ratio of the tightening machine).
The angle is converted from the speed reduction ratio of the socket to the motor rotation and displayed. The current axis in FIG. 5 is obtained by detecting the current value of the motor at the above-described predetermined cycle, and detecting the current by the CT sensor and converting the output voltage of the CT sensor into a current value. The differential axis in FIG. 6 represents the relative value of the current data (ΔI: the value obtained by subtracting the value one cycle before from the current value) taken at each of the above-mentioned predetermined periods, as the relative value of the angle data.
The value is divided by (Δθ) (ΔI / Δθ). Note that the current waveform of the primary tightening torque of 1000 kg-cm is displayed at points in the above-described predetermined cycle, but other current waveforms are connected by solid lines between the points and are displayed as continuous lines having different thicknesses. .

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] FIG.

[Correction method] Change

[Correction contents]

FIG. 11

Continuation of front page (72) Inventor Yasushi Kanayama ▲ Nobu ▼ 3-14-3 Fukaekita, Higashinari-ku, Osaka City, Osaka Prefecture F-term (reference) 2F051 AA11 AB06 AC07 BA03 3C038 AA04 BC04 CA07 CB02 EA02

Claims (7)

[Claims] 1. A tightening machine for fully tightening a primary-tightened (temporarily-tightened) nut by driving a motor, comprising a current differentiating circuit for differentiating a drive current of the motor, a primary-tightening torque detecting circuit, and a nut tightening angle pass / fail determination circuit. The primary tightening torque detecting circuit is configured such that the angle at the time when the differential value of the current differentiating circuit passes from the negative value to the zero point and changes to a positive value (final tightening start point) is θ0, and the current differentiation after θ0 is performed. The primary tightening torque is determined by comparing the value with the data indicating the relationship between the primary tightening torque. The nut tightening angle acceptance / rejection determination circuit completes the predetermined tightening after the differential value reaches a maximum after θ0. The time at which the differential value has decreased to the differential value corresponding to the time is defined as the tightening rotation angle θ1 of the nut, and θ1−θ0 is determined based on whether the primary tightening torque value and the length under the neck of the bolt are within a range of a preset angle. An electric bolt tightening machine with an inspection function, which determines whether or not a nut tightening angle is acceptable. 2. An abnormal elongation determination circuit, which detects a current value when the angle exceeds a predetermined angle from the angle θ1, and a ratio of the current value to a maximum current value is equal to or more than a predetermined ratio. In the case of, or the current value after the angle θ1 becomes the maximum, the angle when the current value decreases to a predetermined ratio with respect to the maximum current value is detected, and when the angle is equal to or more than the preset angle, abnormal elongation is detected. The electric bolt tightening machine with an inspection function according to claim 1, wherein the electric bolt tightening machine outputs a failure signal upon determining that the bolt has been tightened. 3. A tightening machine for fully tightening a temporarily tightened (temporarily tightened) nut by driving a motor, wherein a speed differentiating circuit for differentiating the rotation speed of the motor, a primary tightening torque detecting circuit, and a nut tightening angle pass / fail determination circuit are provided. The primary tightening torque detection circuit determines the angle at which the differential value of the speed differentiating circuit has passed from the positive value past the zero point to a negative value (final tightening start point) as θ0, and the speed differential after θ0. The primary tightening torque is obtained by comparing the value with the data indicating the relationship between the primary tightening torque. The nut tightening angle acceptance / rejection determination circuit completes the predetermined tightening after the differential value becomes minimum after the above θ0. The time point at which the differential value has risen to the differential value corresponding to the time point is defined as the tightening rotation angle θ1 of the nut, and θ1-θ0 is determined based on whether the primary tightening torque value and the length under the neck of the bolt are within a range of a preset angle. An electric bolt tightening machine with an inspection function, which determines whether or not a nut tightening angle is acceptable. 4. An abnormal elongation determination circuit, wherein the abnormal elongation determination circuit detects a speed when the angle exceeds a predetermined angle from the angle θ1, and when a ratio of the speed to the minimum speed is equal to or less than a predetermined ratio, Alternatively, the speed after the angle θ1 becomes the lowest, and the angle at which the speed increases to a predetermined ratio with respect to the lowest speed is detected. If the angle is equal to or larger than the preset angle, it is determined that abnormal elongation has occurred, and a fault signal is generated. The electric bolt tightening machine with an inspection function according to claim 3, which emits. 5. A tightening machine for fully tightening a temporarily tightened (temporarily tightened) nut by driving a motor, comprising a torque differentiating circuit for differentiating the nut tightening torque, a primary tightening torque detecting circuit, and a nut tightening angle pass / fail determination circuit. The primary tightening torque detection circuit sets the angle at which the nut tightening torque differential value reaches a maximum as θ0 and compares the maximum torque differential value with data indicating the relationship between the torque amount and the torque differential value. The nut tightening angle acceptance / rejection determination circuit determines the angle when the differential value decreases after θ0 and reaches a predetermined amount as θ1.
An electric bolt tightening machine with an inspection function, which determines whether or not 1-θ0 is within a predetermined angle range from the primary tightening torque value and the length under the neck of the bolt. . 6. An abnormal elongation judging circuit, which detects a torque value when the angle exceeds a predetermined angle from the angle θ1, and sets the amount of torque to a predetermined ratio with respect to the maximum torque value. In the above cases, or when the torque value after the angle θ1 becomes the maximum and the torque value decreases to a predetermined ratio with respect to the maximum torque value, the angle is detected. 6. The electric bolt tightening machine with an inspection function according to claim 5, wherein a failure signal is issued upon judging the extension. 7. A marker is provided on the tightening socket so as to be movable in the axial direction of the socket, and a reject signal activates the solenoid to move the marker, thereby marking the tightening member fitted in the socket. An electric bolt tightening machine with an inspection function according to claim 1.