JP2000117653A - Bolt fastener - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the detection accuracy of a nut fastening starting point by providing a time lag between tool driving and the nut fastening starting point to stabilize the rotation of a tool. SOLUTION: This bolt fastener is provided with a fastening section housing an inner socket 32 in an outer socket 31, and a power transmitting section 30 for rotating the two sockets 31 and 32 by a planetary gear mechanism 36, and a nut is fastened by fitting the nut of a torque shear type high strength bolt and a pin tail to the sockets 31 and 32 to rotate the sockets 31 and 32 in opposing directions. In this case, the outer socket 31 or the inner socket 32 is connected with play to the power transmitting member 30 by an elastic member 41 and, after non-load rotation equivalent to the play, fastening is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torsion-type high-strength bolt or hexagonal high-strength bolt tightening device used for construction and bridges.

[0002]

2. Description of the Related Art Torcia-type high-strength bolts and hexagonal high-strength bolts are known as bolts for construction and bridges. The torcia-type high-strength bolt (1) is, as shown on the left side of FIG.
A pin tail (4) that is caught by a bolt tightening device is provided at the tip of the screw portion (2) via a neck portion (3) serving as a cutting portion. An axially extending groove (4a) is formed on the outer peripheral surface of the pin tail (4) so that the cross section has a W hexagonal shape, and the pin tail (4) is inserted and fitted into an inner socket of a bolt tightening device. The tightening using the torcia-type high-strength bolt (1) is performed until the nut (3) is cut by rotating the nut (5) relative to the pin tail (4). The force is secured.

An example of a bolt tightening device using a torcia-type high-strength bolt (1) is shown below with reference to FIG. The bolt tightening device (6) includes, as a tightening mechanism, a bevel gear (8) that meshes with an external gear (7) driven by a drive source such as an electric motor (not shown) via an intermediate gear; A planetary gear mechanism (9) meshing with (8), a power transmission component (10) for transmitting the revolving motion of the planetary gear, and a power transmission component (1);
0), an inner socket (11) fitted slidably in the front-rear direction, a clutch (12) fixed to the tip (9a) of an annular internal gear of the planetary gear mechanism (9), and a clutch (12). Outer socket (1
3), and these are assembled to the gear box (14).

In the bolt tightening device (6), the inner socket (11) is fitted to the pin tail (4) of the torcia-type high-strength bolt (1) from the state shown in FIG. 5, and the outer socket (13) is connected to the nut. Tightening is started by driving the drive source by fitting in (5). At this time, the rotational torque amplified by the external gear (7), the bevel gear (8), and the planetary gear mechanism (13) is used as a reverse relative rotation of the inner socket (11) and the outer socket (13) to form a torsion-type high-strength bolt. It is transmitted to (1). Then, when the predetermined tightening force is reached, the neck portion (3) of the bolt is cut.

An example of a hexagonal high-strength bolt tightening device is shown below with reference to FIG. FIG. 6 shows a steel member to be tightened (1).
5) Temporarily tightened bolts (high tension bolts) (16), nuts (17), and bolts (1)
6) shows an electric wrench (18) for fully tightening the nuts (17) one by one. The electric wrench (18) accommodates a motor (20) and a reducer (21) composed of a planetary gear mechanism including a reduction gear in an L-shaped main body (19), and a reaction force socket ( 22).

The reaction force socket (22) integrally has a projecting reaction force receiver (23) on the outer periphery and a nut (23) inside.
And a nut socket (not shown) for fitting and rotating. Further, the planetary gear mechanism connects the rotation shaft of the motor (20) to a sun gear located at the center, connects a nut socket to a plurality of (for example, three) planetary gears meshed with the center gear, and sets the internal gear to a planetary gear. The reaction force socket (22) is connected to the annular revolving gear engaged with the gear.

Therefore, the nut (17) is inserted into the nut socket.
When the power is turned on and the motor (20) is rotated, the planetary gear mechanism first rotates the reaction force receiver (23), and the nut socket rotates when it hits the adjacent nut (17 '). The nut (17) is fully tightened.

Here, the bolt and nut tightening procedure including the above-described final tightening and the like will be described. Primary tightening (temporary tightening) is performed so that the members to be tightened are brought into close contact with each other, and about 60% of the standard axial force of the bolt. There is a preliminary tightening to tighten and a final tightening to standard axial force. When performing primary tightening, preliminary tightening, and final tightening with an electric bolt tightening device, tightening is performed to a predetermined target value by mechanical or electrical control. In this case, how accurately the tightening start point is detected is a major factor in determining the tightening accuracy. A conventional example of the tightening start point detecting means will be described below with reference to FIGS. .

First, the first detecting means detects the amount of change (acceleration) in the rotational speed of the tightening tool using a pulse detector (24) shown in FIG.
Is a slit plate (2) provided on the rotating shaft (25) of the motor.
The peripheral end of 6) is sandwiched between U-shaped photosensors (27). Then, a pulse detector (24) detects a rotation pulse synchronized with the wrench motor, and converts the rotation pulse into a rotation speed signal based on a change in the number of rotation pulses or a pulse period within a predetermined time. When the switch of the fastening tool is turned on and the motor is driven, the rotation speed signal increases at an accelerated rate and reaches a constant speed. Thereafter, for example, when the reaction force receiver of the tool comes into contact with an adjacent bolt (seating point), the nut rotates, and the bolt starts to be tightened, the rotation speed decreases. The point where the rotation speed decreases becomes the fastening start point, and the rotation speed can be detected by differentiating or peak-holding.

First, when differentiating the rotation speed, as shown in the control block diagrams of FIGS. 8 (a) and 11 (a), the speed is differentiated, and when the speed reaches the 0 level, or when the speed changes from positive to negative. Taking the inverted point as the tightening start point. When the rotational speed is peak-held, as shown in the control block diagrams of FIGS. 9A and 11B, the point at which the rotational speed falls by 3 to 5% from the peak of the speed is the control start point ( Tightening start point).

Next, the second tightening start point detecting means detects a change in load current at the time of bolt tightening. That is,
As shown in the control block diagrams of FIGS. 10 (a) and 11 (c), the load current has reached a constant current with a start current waveform region in which a sudden rise at the start of driving occurs and the start current calms down. The state is divided into a no-load waveform area where no load is applied and a tightening waveform area where the nut is tightened and the load current increases. The load current (I) in the tightening waveform area
And the tightening torque (T) are substantially proportional after the seating point.

From the change in the load current (I), it is estimated that the nut tightening start point is a point at which the rising waveform at the time of startup is stabilized, and starts rising again, that is, the point (H) in the figure. Therefore, the load current (I) detected from the current transformer is differentiated, and a point at which the load current reaches the 0 level or a point at which the load current is inverted from negative to positive is determined as a fastening start point.

[0013]

According to the first nut tightening start point detecting means, as shown in FIG. 8B, the nut tightening is started at the same time as the driving of the tightening tool. If the tool increases speed trying to reach a constant speed,
The speed reduction due to the nut tightening is performed at the same time, and the speed change is later than the actual tightening. In this case, since the tightening start point detecting means based on differentiation detects a point that is considerably tightened from the actual tightening start point as a start point, there is a problem that the tightening is excessively performed.

When detecting a peak hold, FIG.
As shown in (b), when the tightening of the nut is started at the same time as the driving of the tool in a timely manner, a speed increase in which the tool tries to reach a constant speed and a speed decrease due to the tightening of the nut are performed simultaneously. Changes lag behind actual tightening. In this case, the tightening start point detecting means due to the decrease from the speed peak detects a point considerably tightened from the actual tightening start point as a start point, so that the tightening is excessive.

According to the second fastening start point detecting means,
As shown in FIG. 10 (b), when tightening occurs immediately after the tool is driven, there is no load, so that the load current waveform changes immediately from the starting current, and the load current waveform starts from the actual tightening start point. The point is late. In this case, too, the detection of the tightening start point is delayed, so that the tightening is excessive.

In order to avoid the above-mentioned problems by performing a soft start by phase control or the like, the speed at the time of starting has been slowed down, and the workability has been significantly reduced.

An object of the present invention is to provide a bolt tightening device which stabilizes the rotation of a tool by providing a time difference between a tool drive and a nut tightening start point, and improves the detection accuracy of the nut tightening start point. That is.

[0018]

According to the present invention, there is provided a tightening portion in which an inner socket is housed in an outer socket, and a power transmitting portion for rotating both sockets by a planetary gear mechanism.
In a bolt tightening device in which a nut and a pin tail of a torcia-type high-strength bolt are fitted into each of the outer and inner sockets, and the sockets are rotated in opposite directions to each other to tighten the nuts, the outer socket or the inner socket may be counter-tightened. The power transmission unit is connected to the power transmission unit through a play at a predetermined angle by an elastic member that urges in the application direction. After the power transmission unit is rotated by no load for the play, power is transmitted to the socket and tightening is performed. In addition, the nut socket is housed in the reaction force socket, and a power transmission unit for rotating both sockets by a planetary gear mechanism is provided. The nut of the bolt is fitted, and the reaction socket is rotated to lock the reaction force receiver on the adjacent protrusion. In the bolt tightening device for tightening the bolts, the reaction force socket or the nut socket is connected to the power transmission unit through a play at a predetermined angle by an elastic member biasing in the counter-tightening direction, and the power transmission unit has no play. After the load is rotated, power is transmitted to the socket to perform tightening.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a bolt tightening device according to the present invention will be described below with reference to FIGS. First, FIGS. 1A, 1B, and 1C are schematic side views of a main part of a torsion-type high-strength bolt tightening device according to the present invention, a right front view of a planetary gear mechanism, and A in FIG. 1A. 1 (a), (30) is a power transmission unit, (31) is an outer socket, (32) is an inner socket, and each of the outer and inner sockets (31) (32). The fastening part according to the present invention is configured.

The power transmission section (30) is connected to a bevel gear (33) (34) for transmitting the rotational drive of the motor (M) via a speed reducer (35), similarly to the conventional apparatus shown in FIG. And a planetary gear mechanism (3).
6) rotate the outer socket (31) and the inner socket (32) in mutually opposite directions.

The planetary gear mechanism (36) is shown in FIG.
, A sun gear (37) connected to a motor rotating shaft via a bevel gear (34) and the like, three planetary gears (39) meshing with the sun gear (37) at the same time, and an inner peripheral surface. And an annular revolving gear (40) which meshes with the planetary gears (39) and is coaxially and integrally connected to the outer socket (31). The above planetary gear (3
9) are connected to the inner socket (32) with their rotating shafts integrally supported by the annular connecting plate (38), and transmit power to the inner socket (32).

Then, the sun gear (3) is driven by the motor (M).
When 7) is rotated (rotated), three planetary gears (39)
Are revolving as a unitary three planet block (39a) while rotating, and the inner socket (32) rotates. At the same time, the revolving gear (40) rotates to rotate the outer socket (3).
1) rotates in the opposite direction to the inner socket (32).

The nut (5) of the torcia-type high-strength bolt (1) is fitted into the outer socket (31) as in the prior art, and the inner socket (32) is the pin tail (4) of the torcia-type high-strength bolt (1). ) Is fitted.

The inner socket (32) is shown in FIG.
As shown in (c), at least at a connection portion with the connection plate (38), the plate is divided into three portions every 120 °, and correspondingly, the convex plate portion (38a) is formed on the outer periphery of the ring of the connection plate (38) every 120 °. )
Are formed. Then, the divided inner socket (32) and the convex plate portion (38a) are formed at a predetermined angle (= approximately 30 °) by an elastic member, for example, a compression spring (41) that urges in the anti-tightening direction. Are connected through circumferential play (Pa)..., As will be described later, from the power transmission unit (30) to the connecting plate (38), the convex plate (38a) and the spring (41).
Are transmitted to the inner sockets (32). The angle of play (Pa)... (= Approximately 30 °) is derived from an experimental value and is an angle required to reach a steady state, and is a composite center of the inner socket (32) and the convex portion (38a). By setting the angle to about 60 °, play (P
a) is set to about 30 °.

The operation of the present invention based on the above configuration will now be described. First, the motor (M) is driven to drive the power transmission unit (30) via a bevel gear or the like, thereby rotating the planetary block (39a) counterclockwise. Then, as shown in FIG. 1 (c), the connecting plate (38) rotates in the tightening direction shown by the arrow against the elastic force of the springs (41), while the inner socket (32) has not yet rotated. .

Then, after the planetary block (39a) and the connecting plate (38) rotate by no load for about 30 ° of play (Pa), the convex plate portion (38a).
, And both of them start rotating counterclockwise together, and the outer socket (31) is connected to the inner socket (3).
Tighten the nut (5) by rotating in the opposite direction to 2).
That is, the planetary block (39a) of the power transmission unit (30) rotates without load for about 30 ° of play (Pa) before the inner socket (32) starts tightening.
In the meantime, the rotation reaches a steady state, whereby the tightening start point can be reliably detected.

The general structure of the above-mentioned tightening device will be described below with reference to FIG. First, FIGS. 2 (a), 2 (b), and 2 (c) are a left front view, a longitudinal sectional side view, and a cross-sectional view taken along line BB of FIG. In the drawing, the upper half of the chain line in FIG. 2 (b) shows the state before tightening,
The lower half shows the state at the time of completion of tightening. In the figure, (30)
Is a power transmission unit, (31) is an outer socket, (32)
Is an inner socket, and (36) is a planetary gear mechanism.

As the power transmission section (30), a planetary gear mechanism (36) is illustrated. The planetary gear mechanism (36) includes a sun gear (37), three planetary gears (39),. 40), and the planetary gears (39)... Are integrally connected as a planetary block (39a) by an annular connecting plate (38), and (37a) shown in FIG. ) Is the sun gear axis. The outer socket (31) is revolved by a clutch (42).
Connected to. The inner socket (32) is connected to the convex portion (38a) of the connecting plate (38) via a play (Pa) by a compression spring (elastic member) (41), and the pin tail holding cylinder (43) is inserted into the inner socket. Spring (4
It is slidably fitted while being urged by 4).

Next, another embodiment of the bolt tightening device according to the present invention will be described with reference to FIGS. First, FIG.
(A), (b) and (c) are front views, side sectional views, and main part front sectional views of a hexagonal high-strength bolt tightening device, and FIGS. 4 (a) and (b) are exploded perspective views of a socket portion and a clutch. In the figure, (45) is a reaction force socket (outer socket), (4)
6) is a nut socket (inner socket), (47)
Is a base, and (48) is a clutch.

The reaction force socket (45) integrally has a projecting reaction force receiver (49) on the outer periphery, and a nut socket (46) for fitting a nut of a bolt therein has a radial ring (50) and a stopper. It is arranged via a ring (51).
As shown in FIG. 4 (a), a plurality of driving claws (45a) are provided at a rear end face of the reaction force socket (45) at a predetermined pitch (every 120 °) along the circumferential direction, and will be described later. The clutch claws (48a) of the clutch (48) are driven claws (45a) ...
, And the rotational force is transmitted by abutting from the circumferential direction. FIG.
As shown in FIG. 4 (c) and FIG. 4 (a), the hooks (52a) (52b) at both ends of the circular band spring (elastic member) (52) which urges in the counter-tightening direction are connected to the reaction force socket (45). And the base (47) are hooked from each inner peripheral surface side, and the two are interposed by the spirolox (54) while the circular band spring (5) is interposed therebetween.
Connect by 2). Further, the clutch (48) is housed in the base (47) from the rear end side, and the embedded screw (53) is inserted.
Thus, the clutch (48) is fixed to the base (47) to integrate them.

The clutch (48) is shown in FIGS.
As shown in (b), clutch claws (48a) are provided on the front end face.
Are protruded at every 120 degrees along the circumferential direction. As described above, the clutch claws (48a)... Come into contact with the driving claws (45a) of the reaction force socket (45) to reduce the rotational force during the tightening rotation. introduce. Further, as described above, the clutch (48) is housed in the base (47), and the screw hole (48b) shown in FIG.
And a clutch (48) is fixed to the base (47) via a retaining ring (55).

At this time, as shown in FIG. 3 (c), when there is no load, the driving claw (45a) of the reaction force socket (45) has a predetermined angle (= approximately 30 °) with the clutch claw (48a). P
a), the clutch pawl (48a) comes into contact with the driving pawl (45a) after a no-load rotation of about 30 ° of play (Pa) during the tightening rotation (clockwise). The reaction force socket (45) and the base (47) rotate together,
Tighten the nut.

The rear end of the clutch (48) has a cylindrical internal tooth (annular revolving gear) (5) through a thrust plate (56), a retaining ring (57) and a ball bearing (58).
Fixed to 9). The internal teeth (59) are radial rings (6
0), the internal gear is engaged with the planetary gear. Planet gears are nut sockets (46)
And meshes with the sun gear, which is connected to the rotating shaft of the motor.

The operation of the present invention based on the above configuration will now be described. First, the nut of the hexagonal high-strength bolt is fitted into the nut socket (46), and when the motor is driven, the internal teeth (59), the clutch (48) and the base (4) are driven by the planetary gear mechanism.
7) rotates, and the clutch pawl (48a) rotates in the tightening direction (clockwise) against the elastic force of the band spring (52), as shown in FIG. Then, clutch claws (48
After a) is rotated by no load for about 30 ° of play (Pa),
When the driving claw (45a) of the reaction force socket (45) abuts, the rotational driving force of the clutch (48) is transmitted to the reaction force socket (45). Therefore, reaction force socket (45)
At the same time, the reaction force receiver (49) rotates to rotate the next nut (61).
The nuts are fully tightened from the point of contact. That is, since no-load rotation is performed for a play (Pa) of about 30 ° before the start of tightening, the rotation reaches a steady state during that time, whereby the tightening start point can be reliably detected. .

[0035]

According to the present invention, in a bolt tightening device such as a torcia-type or hexagonal high-strength bolt, a play at a predetermined angle is provided before the start of tightening, so that a constant play is required from tool driving to tightening. A no-load condition is created, and the tightening start point can be reliably detected.

[Brief description of the drawings]

FIG. 1A is a schematic cross-sectional side view showing an embodiment of a torsion-type high-strength bolt tightening device according to the present invention. (B) is a front view showing the planetary gear mechanism of the power transmission unit according to the present invention.
FIG. 2C is a sectional view taken along line AA of FIG.

FIG. 2 (a) is a left front view showing a general configuration of a torsion-type high-strength bolt tightening device according to the present invention. (B) is FIG.
(A) The principal part longitudinal section side view of an apparatus. (C) is B in FIG. 2 (b).
In the cross-sectional view taken along the line B, the upper half of the chain line shows the state before tightening,
The lower half shows the state at the time of completion of tightening.

FIGS. 3 (a), (b) and (c) are a front view, a longitudinal sectional view and a main part front sectional view showing an embodiment of a hexagonal high-strength bolt tightening device according to the present invention.

4 (a) and 4 (b) are exploded perspective views of a socket portion and a clutch portion of the hexagonal high-strength bolt tightening device according to the present invention.

FIG. 5 is a longitudinal sectional view showing a conventional example of a torcia-type high-strength bolt and its tightening device.

FIG. 6 is a longitudinal sectional view showing a conventional example of a hexagonal high-strength bolt tightening device.

FIG. 7 is a side view of a main part of the pulse detector.

FIG. 8A is a graph showing torque, speed, speed derivative, and control output showing a rotation speed decrease detecting means based on speed derivative.
(B) is a graph of torque, speed, speed derivative, and control output when fastening is started at the same time as tool driving, showing the problem of the present invention.

FIG. 9A is a graph of torque and speed showing rotation speed decrease detection means by speed peak hold. (B) is a graph of the torque and the speed when the tightening is started at the same time as the driving of the tool, showing the problem of the present invention.

10A is a graph showing torque, load current, load current derivative, and control output showing rotation speed decrease detection means by load current detection at the time of bolt tightening. FIG. (B) is a graph showing torque, load current, load current derivative, and control output when tightening is started at the same time as tool driving, showing the problem of the present invention.

FIG. 11A is a control block diagram of a rotation speed decrease detection unit based on speed differentiation. (B) is a control block diagram of a rotation speed decrease detection means by speed peak hold. (C) is a control block diagram of a rotation speed decrease detection means by load current detection at the time of bolt tightening.

[Description of Signs] 30 Power transmission unit 31 Outer socket 32 Inner socket 36 Planetary gear mechanism 41 Elastic member

Claims (2)

[Claims] The present invention has a tightening portion in which an inner socket is housed in an outer socket, and a power transmission portion for rotating both sockets by a planetary gear mechanism. In a bolt tightening device that fits a pin tail and rotates each socket in a direction opposite to each other to tighten a nut, the outer socket or the inner socket has a play at a predetermined angle by an elastic member that urges in a counter tightening direction. A bolt tightening device that is connected to a power transmission unit via the power transmission unit, rotates the power transmission unit with no load for play, and then transmits power to the socket to perform tightening. 2. A nut socket having a tightening portion in which a nut socket is accommodated in a reaction force socket and a power transmission portion for rotating both sockets by a planetary gear mechanism, wherein a reaction force receiver is provided on the outer periphery of the reaction force socket. A bolt tightening device for rotating a nut socket and tightening a nut in a state in which a nut of a bolt is fitted to the nut and a reaction socket is rotated to lock a reaction force receiver on an adjacent convex portion. The nut socket is connected to the power transmission unit through a play at a predetermined angle by an elastic member that urges in the anti-tightening direction, and after rotating the power transmission unit without load for the play, transmits power to the socket. A bolt tightening device for performing tightening.