JPH04348878A - Bolt fastening tool white can measure axial force of bolt - Google Patents

Abstract

PURPOSE:To precisely measure an axial force of a fastening bolt by providing a spring for urging the measuring surface of an ultrasonic sensor to push out the same from the peripheral edge of an opening in a sensor holding cylinder. CONSTITUTION:An ultrasonic or magnetic sensor 19 which is fitted in a socket 13 adapted to be coupled to a torque wrench body, may be tilted by a resilient force of a spring 21 so that the measuring surface of the sensor 9 can be made into close contact with the head surface of a bolt 24, irrespective of the socket 13. Accordingly, the axial force of the bolt 24 can be measured with a high degree of reliability.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt tightening tool capable of measuring bolt axial force during bolt tightening using an ultrasonic or magnetic force sensor.

0002

[Prior Art] For example, when tightening a bolt, the torque method,
There are rotation angle methods, torque gradient methods, etc., but with these control methods, even if it is possible to determine the axial force of the bolt and manage variations in axial force, it is difficult to measure changes in axial force over time. was considered difficult.

[0003] Therefore, in recent years, an axial force measuring method using an axial force meter using ultrasonic waves or magnetic force has been developed as a practical means that can also measure aging of tightening bolts. This measurement method calculates the axial force by measuring the elongation of the bolt before and after bolt tightening.
Calculating the axial force involves the following three steps. In other words, (a) Initial value measurement step: An ultrasonic or magnetic force sensor is installed on the bolt head to measure the initial length of the bolt before tightening, and an axial force meter using an ultrasonic or magnetic force sensor is used to measure the initial length of the bolt before tightening. Set the value to zero.

(b) Tightening step: Remove the sensor from the bolt head and tighten the bolt with a tightening tool such as a torque wrench.

(c) Axial force measurement: The above sensor is pressed against the bolt head again to measure the bolt length after tightening.

[0006] In this method of measuring the axial force of a bolt through three steps, it is necessary to attach and detach the sensor before and after tightening with a tightening tool, which is complicated. It is difficult to always position the sensor at the same position, and furthermore, the state of contact between the bolt head and the sensor changes when the sensor is attached or detached, resulting in a reduction in measurement accuracy.

In order to solve this problem, a fastening tool as shown in FIG. 1, for example, is known in which a sensor is incorporated into the socket of the fastening tool.

That is, the fastening tool shown in FIG. 1 has an ultrasonic sensor 4 inside a socket 2 fitted into the head of a torque wrench 1, which is always urged outward by the elasticity of a spring 3. When tightening the bolt 6 to be fastened to the object to be tightened 5 with this torque wrench 1,
By fitting the socket 2 to the head 6' of the bolt 6, the sensor 4 is moved to the head 6' by the elastic force of the spring 3.
', and thereby the axial force of the bolt 6 before and after tightening is measured by the axial force gauge 7.

[0009]

However, in the socket 2 in which the sensor 4 is installed, if there is a gap between the inner surface of the socket 2 and the outer surface of the bolt head 6', for example, as shown in FIG. The socket 2 tends to tilt together with the torque wrench 1, which causes the tip end surface of the sensor 4 to not come into close contact with the bolt head surface, resulting in a problem that stable axial force measurement cannot be performed.

Furthermore, as shown in FIGS. 3A and 3B, the bolt head used for fastening is often provided with a protruding mark 8 indicating the manufacturer's symbol or strength classification. In this case, the mark 8 is shaved off to ensure close contact with the sensor 4, but during this cutting process, it is extremely difficult to process the cutting head so that it is a plane perpendicular to the bolt axis. However, as shown in FIG. 4, for example, since the cutting surface is inclined, the sensor 4 cannot be brought into close contact with the bolt head surface, which also causes a problem in that stable axial force measurement cannot be performed.

Furthermore, in the conventional example shown in FIGS. 2 and 4, the lead wire 9 is pulled out from the side of the socket 2 and connected to the ultrasonic axial force meter 7. Due to lack of consideration, the lead wire 9 tends to become entangled with the socket 2, which causes the wire to break, making measurement impossible.

0012

[Means for Solving the Problems] The present invention has been made in view of the above-described problems in the prior art. The measuring surface of the sensor is made to be tiltable by elastic force so that the measuring surface of the sensor can be brought into close contact with the head surface of the bolt by the elastic force of the spring regardless of the inclination of the socket, thereby increasing the reliability of measurement. takes into account the part of the lead wire that is drawn out from the sensor, and prevents the lead wire from breaking.
Another object of the present invention is to provide a bolt fastening tool that can facilitate the handling of a torque wrench and improve fastening workability.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained in detail below based on embodiments shown in the drawings.

In FIG. 5, reference numeral 11 denotes a head portion of a torque wrench 12, and a socket 13 having a central axis perpendicular to the axial direction of the torque wrench 12 is rotatably supported inside the head portion 11. There is. This socket 13
A portion of the outer circumferential surface located within the head portion 11 includes:
A ratchet gear 14 is formed, and a ratchet pawl 15 that is pivotally supported within the head portion 11 is removably engaged with the ratchet gear 14. 16 is a sensor holding cylinder fixed concentrically within the socket 13,
A female thread 17 is formed on the inner periphery of the upper end of the sensor holding cylinder 16, and an adjustment screw 18 is screwed into this female thread 17. Reference numeral 19 denotes an ultrasonic sensor having an outer diameter smaller than the inner diameter of the sensor holding cylinder 16. It is supported so that it can tilt. 21 is a spring interposed between the adjustment screw ring 18 and the ultrasonic sensor 19 to bias the ultrasonic sensor 19 toward the open end of the socket 13; 22 is a lead wire drawn out from the ultrasonic sensor 19; 23 is a stopper collar, 24 is a tightening bolt, and 25 is a rotary connector that is fixed to the upper end of the socket 13 by a mounting screw 38 and connects the lead wire 22; , a rotary electrode 26 is provided, and a lead wire 28 connected to an ultrasonic axial force meter 27 is drawn out from the rotary electrode 26. Reference numeral 29 denotes a connector case in which a connector 30 connected to the lead wire 28 is attached and is fixed onto the head portion 11 with a mounting screw 31.

The configuration of this embodiment has been described above, and its operation will now be described.

In this embodiment, when tightening the tightening bolt 24 to the object 32 using the torque wrench 12, the socket 13 of the torque wrench 12 is inserted into the tightening bolt 2.
4, the handle portion of the torque wrench 12 is reciprocated from side to side, and the screw is tightened using the power transmission means of the ratchet gear 14 and the ratchet pawl 15.
By measuring the axial force of the tightening bolt 24 before and after the screw tightening operation, the tightening force of the tightening bolt 24 can be measured.

Therefore, the axial force of the tightening bolt 24 can be measured by bringing the tip end surface of the ultrasonic sensor 19 incorporated into the head portion 11 into close contact with the head surface of the tightening bolt 24. The socket part 11 fitted into the head of the tightening bolt 24 is oversized if the central axis a of the socket part 11 is parallel to the central axis (b) of the tightening bolt 24, as shown in FIG. 6(a). The end face of the ultrasonic sensor 19 is brought into close contact with the end face of the tightening bolt, but when the socket portion 11 is tilted with respect to the tightening bolt 24 as shown in FIG. 6(b), the ultrasonic sensor 19
There is a concern that the tip end face of the bolt may not be brought into close contact with the head face of the tightening bolt.

However, in this embodiment, as shown in FIG.
It is supported so as to be tiltable with respect to the axis of the holding cylinder 16 via a support ring 20, and moreover, the holding cylinder 16 is supported by a spring 21.
Since the ultrasonic sensor 19 is biased to protrude from the opening edge, the tip surface of the ultrasonic sensor 19 can be brought into close contact with the head surface of the tightening bolt at any time by the elastic force of the spring 21. , the axial force of the bolt 24 can be determined accurately.

Further, in FIG. 6, the socket head portion 11
Considering the inclination angle of
When the gap between the socket and bolt is ΔS, and the height of the bolt head is k,

[0020]

[Math 1]

It is determined by:

For example, in the case of width across flats 17 according to JIS B4363 Socket Wrench Socket Annex, the tolerance is +0.05 to +0.30, and S
S=17.2mm. On the other hand, the bolt is JIS B1
180 Annex ISO 4014-4018 Width across flats 17 at average finishing level with hexagonal bolts
In the case of , the tolerance is 0 to -0.7, and within the tolerance range SB
= 16.6mm, the bolt head height is 7mm, and the tolerance is ±0.3mm, so k = 6.8mm within the tolerance range.
In this case, θ≈5°. This estimated value of θ is under relatively good conditions, and it is expected that a larger θ will occur in practical use. The dimensional tolerance of the socket used there, the gap △S with the bolt expected to be used,
By considering the height of the bolt head and providing a protrusion that relieves the inclination angle θ of the socket, that is, the support ring 20 shown in FIG. Bolt 2 due to force
4.It can be placed in close contact with the head, improving measurement accuracy. Furthermore, according to this embodiment, the lead wire 22 drawn out from the sensor 22 is drawn out to the outside via the rotary connector 25 and the rotary electrode 26, so that the lead wire is connected to the instrument as the torque wrench rotates. Tightening workability is improved without twisting.

FIG. 7 shows the torque wrench 1 in the above embodiment.
2, the initial value setting switch 33 and the head section 11
For example, when the tightening force of the tightening bolt 24 is not loaded, the setting switch 33 is fixed to the limit switch 34.
By operating the axial force meter 27, the axial force of the tightening bolt 24 under no load can be measured.

Next, the tightening bolt 24 is tightened by operating the torque wrench 12, and when the tightening value of the bolt 24 reaches a predetermined value, the toggle 35 is operated, which causes the microswitch to operate, and the tightening bolt 24 is tightened. The bolt axial force value at the end of attachment is displayed on the ultrasonic axial force meter 27 using a signal from the ultrasonic sensor.

Therefore, according to this embodiment, the axial force value of the tightening bolt 24 under no load is measured by operating the initial value setting switch 33, and thereafter, the axial force value of the tightening bolt 24 is measured when the tightening of the tightening bolt 24 is completed using a torque wrench. The feature is that the axial force value can be measured automatically.

FIG. 8 shows an embodiment in which the manual torque wrench 12 in the previous embodiment is replaced with a power torque wrench. Therefore, in this embodiment, the power source of the power torque wrench 36 and the ratchet gear 14 provided in the socket 13 in the head portion 11 are connected via a reduction gear group 37. The head portion 11 can be driven by power, and labor savings for the operator can be achieved. Note that the function of the ultrasonic sensor 19, which is the gist of the present invention, is the same as the embodiment shown in FIG.

FIG. 9 shows the torque wrench body 39 and head portion 1.
By making the head parts 11 removable and having sockets 13 of various sizes prepared in advance, it is possible to tighten the tightening bolts 24 of various sizes by replacing the head parts 11. , the same torque wrench body 39
It has the advantage of being able to be carried out.

[0028]

As described above, the present invention provides a sensor holding cylinder 1 whose both ends are open inside a socket 13 which is rotatably held within the head part 11 of a bolt tightening torque wrench.
6 is fixed, and an adjusting screw ring 18 is screwed to one end of this sensor holding cylinder, and an ultrasonic wave sensor having an outer diameter smaller than the inner diameter of the holding cylinder is provided inside the sensor holding cylinder 16. sensor 19
is loosely fitted coaxially with the sensor holding cylinder 16, and the inner periphery of the holding cylinder and the outer periphery of the ultrasonic sensor 19 are held in line contact by circumferential protrusions so as to be tiltable in the axial direction of the holding cylinder 16. , further the adjustment screw ring 18 and the ultrasonic sensor 1
9, the measurement surface of the ultrasonic sensor 19 is connected to the sensor holding cylinder 1.
Since this is a bolt fastener that can measure the bolt axial force, the bolt fastener is equipped with a spring 21 that urges the bolt to be pushed out from the other side opening edge of the bolt fastener. It is certain that the tip surface (measurement surface) of the sensor is brought into close contact with the head surface of the tightening bolt 24, and the axial force of the tightening bolt can be measured very easily and accurately when using a torque wrench. This effect can be obtained.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional example.

FIG. 2 is an explanatory diagram of a conventional example.

FIG. 3 is an explanatory diagram showing a conventional bolt head surface.

[Fig. 4] Explanatory diagram of conventional example

FIG. 5 is an explanatory diagram showing an embodiment of the bolt tightening tool according to the present invention.

FIGS. 6A and 6B are explanatory diagrams of the operation of this embodiment.

FIG. 7 is a structural explanatory diagram showing a second embodiment of the present invention.

FIG. 8 is a structural explanatory diagram showing a third embodiment of the present invention.

FIG. 9 is a structural explanatory diagram showing a fourth embodiment of the present invention.

[Explanation of symbols]

11...Head part 12
...Torque wrench 13...Socket
14...Ratchet gear 15...Ratchet pawl
16...Sensor holding cylinder 17...Female thread 18...Adjustment screw ring 19...Ultrasonic sensor 20
...Support ring 21...Spring
22... Lead wire 23... Stopper collar
24...Tightening bolt 25...Rotary connector
26... Rotary utility pole 27... Ultrasonic axial force meter
28...Lead wire 29...Connector case 30...Connector 31...Mounting screw 32...To be fastened 33...Initial value setting switch 34...Limit switch 35...Toggle 3
6...Power torque wrench 37...Reduction gear group 38...
Mounting screw 39...torque wrench

Claims (4)

[Claims] Claim 1: A sensor holding cylinder (16) with open ends on both sides is fixed inside a socket (13) which is rotatably held in a head part (11) of a bolt tightening torque wrench. An adjustment screw ring (18
) are screwed together, and inside the sensor holding tube (16) there is an ultrasonic sensor (16) having an outer diameter smaller than the inner diameter of the holding tube.
9) is loosely fitted coaxially with the sensor holding cylinder (16), and the inner periphery of the holding cylinder and the outer periphery of the ultrasonic sensor (19) are connected with respect to the axial direction of the holding cylinder (16) by circumferential protrusions. The adjusting screw ring (1
8) and the ultrasonic sensor (19).
9) A bolt fastener capable of measuring bolt axial force, characterized in that a spring (21) is inserted to bias the measurement surface of item 9) to be pushed out from the other side opening edge of the sensor holding cylinder (16). 2. An initial value setting switch (33) for measuring the no-load axial force of the tightening bolt is attached to the handle of a torque wrench for bolt tightening, and the head of the torque wrench is used to complete tightening of the tightening bolt. 2. The bolt fastening tool according to claim 1, further comprising a limit switch (34) for measuring the axial force of the bolt. 3. The bolt tightening tool capable of measuring bolt axial force according to claim 1, wherein the bolt tightening torque wrench is a power type. 4. The bolt tightening tool capable of measuring bolt axial force according to claim 1, wherein the bolt tightening torque wrench is detachable from the handle portion and the head portion.