JPS5924981Y2 - Bolt axial force measuring device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a bolt axial force measuring device that measures the axial force acting on the bolt to be measured by inserting the bolt to be measured into a load cell and tightening it with a nut.

When tightening parts using bolts and nuts,
Tension, or axial force, is generated in the bolt in the axial direction, but in order to measure the axial force of the bolt, the bolt to be measured is usually inserted into a load cell equipped with a measuring mechanism called a bolt axial force meter, and the bolt is inserted into the nut. The axial force of the bolt is measured by measuring the displacement of the load cell that occurs during tightening with a measuring mechanism.

Generally speaking, the torque method is used to manage the axial force of bolts, which controls the tightening torque required for bolt tightening. Even nuts vary considerably depending on the manufacturing lot and storage time, so the tightening torque value that should be controlled using an axial force meter and torque wrench is determined on site during use.

Since the axial force of the bolt that actually tightens the member to be tightened cannot be measured in the tightened state, the tightening torque of this bolt is measured with a torque wrench, and if the measured tightening torque value is a predetermined value. , it is estimated that the axial force is at a predetermined value.

By the way, the load cell used in the conventional bolt axial force meter converts the displacement into oil pressure and indicates the pressure with a Bourdon tube to convert the axial force.

Therefore, in order to improve the measurement accuracy of the axial force, the load/displacement relationship in the load cell is made small.

In addition, electric nut runners that can adjust the tightening torque have recently come to be used as bolt and nut tightening tools, but these electric nut runners apply additional tightening torque due to inertia energy when the power is disconnected. However, the tightening torque due to this inertial energy increases as the load/displacement relationship of the member to be tightened increases.

Therefore, when setting the tightening torque for the electric nut runner in an axial force meter with a small load/displacement relationship, the inertial energy of the electric nut runner increases the tightening torque by 1 to 100 lbs. Since this is smaller than the increase in tightening torque when tightening a tightening member, there is a drawback that the tightening torque is larger when the tightened member is actually tightened than when it is set using an axial force meter.

In addition, the nut rotation angle method, in which the axial force of the bolt is controlled by controlling the rotation angle of the nut during tightening, is also used.
If the displacement relationship is different, it is natural that the axial force will be a completely different value even if the nut is rotated at the same angle, so it is necessary to match the load/displacement relationship of the tightened member and the axial force meter. Otherwise, the rotation angle of the nut for proper tightening cannot be determined.

In this way, unless the relationship between the load/displacement of the axial force meter and the actual fastened member is the same, the axial force meter cannot accurately measure the axial force to estimate the axial force of the bolt actually used. I can't do it.

On the other hand, when tightening a nut with an electric nut runner, the reaction force of the electric nut runner is often received by the bolt adjacent to the nut. If a bolt receives a reaction force, the nut receives only a torsional moment and no force from the side, but when only one bolt receives a reaction force, it receives a force from the side in addition to the torsional moment, which increases frictional force. As a result, the input of the electric motor is consumed by friction, and the tightening torque decreases.

For this reason, when setting the tightening torque value for the electric nut runner using the axial force meter, an error will occur unless the reaction force receiver is mounted with a bolt at the same mounting position as the actual conditions and does not receive the reaction force.

Conventionally, the tightening torque to be controlled for bolts was determined using an axial force meter and a torque wrench, and after the bolt was actually tightened to the member to be tightened using an electric nut runner, it was checked with a torque wrench to set the electric nut runner. The axial force of the bolt was managed through the troublesome effort of calibrating the bolt.

The present invention was developed in view of the above-mentioned circumstances, and when the plate thicknesses of the load cell and the actual member to be tightened are different, the predetermined tightening can be achieved by matching the load/displacement relationship between the two using a plate thickness adjustment adapter. The axial force of the bolt measured with a load cell when the bolt is tightened to the specified torque or rotation angle, and the axial force of the bolt when the actual measured member is tightened with bolts from the same production lot using the same tightening torque or rotation angle. A plate can be used to create a reaction force receiver with multiple mounting holes in different positions, and a bolt can be used to make the reaction force of the electric nut runner almost the same. The present invention provides a bolt axial force measuring device that can easily measure accurate axial force without causing errors due to reaction force receiving.

An embodiment of the present invention will be described below with reference to drawings.

FIG. 1 is a front sectional view of a bolt axial force measuring device according to an embodiment of the present invention, and FIG. 2 is a plan view of a reaction force receiver plate.

As shown in Fig. 1, the bolt axial force measuring device of the present invention is
A load cell 1, a plate thickness adjustment adapter 5 arranged concentrically above the load cell 1, and a plate thickness adjustment adapter 5
A reaction force receiver arranged concentrically on the upper part of the plate 7 is a reaction force receiver, and a pair of reaction force receivers fixed to the plate 7 are POL) 10. ,
102, and a support fitting 12 for attaching the bolt to be measured.

The load cell 1 includes a strain gauge 3 provided on its outer periphery and an indicator 4 connected to the strain gauge 3.
It has an insertion hole 2 in the center for inserting the bolt to be measured.

The load cell 1 has a predetermined thickness, and the relationship between load/displacement (ratio of applied load and displacement due to this load) according to the thickness is that of an actual tightened member of the same thickness. This is done to match the load/displacement relationship.

Therefore, the amount of displacement of the load cell 1 that is proportional to the axial force of the bolt 13 to be measured is measured via the strain gauge 3, and it is indicated to the indicator 4, and from the amount of displacement indicated by the indicator 4, The axial force acting on the measuring bolt 13 can be converted.

The plate thickness adjustment adapter 5 is a circular plate having an insertion hole 6 in the center for inserting the bolt to be measured, and the load/displacement relationship according to its thickness is the same as the load of the actual member to be tightened with the same thickness. /displacement relationship, and when the thickness of the load cell 1 is smaller than the actual thickness of the member to be tightened, the load cell 1 and plate thickness adjustment adapter 5 are stacked concentrically on one end of the load cell 1. and the reaction force receiver are adjustment tools to make the total thickness of the plate 7 the same as the thickness of the member to be tightened, and are available in several thicknesses depending on the thickness of the member to be tightened. Then select the one with the required thickness and use it.

The plate 7 of the reaction force receiver is a circular plate with an insertion hole 8 in the center for inserting the bolt to be measured, and the load/displacement relationship according to its thickness is similar to that of an actual member to be tightened with the same thickness. A plurality of pairs of reaction force receiving bolts 10 are arranged symmetrically with respect to the center and are arranged at different radial positions from the center so as to match the load/displacement relationship.
A mounting hole is provided for mounting □ and 102.

Then, when tightening the bolt 13 to be measured with the electric nut runner, a pair of reaction force receivers that receive the reaction force of the electric nut runner are used.10. ．． 10□ is screwed into the mounting hole and attached, and used by stacking it on the load cell 1 or plate thickness adjustment adapter 5.

In this embodiment, as shown in FIG. 2, three pairs of reaction force receivers are provided with mounting holes for mounting bolts.

That is, the reaction force receivers are located at radii R1, R2, R3 from the center of the plate 7, and the reaction force receivers are installed symmetrically with respect to the center of the plate 7 through mounting holes 9□, 91 with different thread diameters d1; thread diameter d2. Mounting holes 9□, 9□ and mounting holes 93, 93 with a thread diameter d3 are provided.

In addition, the reaction force receiver is usually inserted into the insertion hole 8 of the plate 7 for the bolt 1 to be measured.
3, the reaction force receiver plate 7 must be different depending on the diameter of the bolt 13 to be measured, and normally the bolt 13 to be measured and the reaction force receiver are the same as the bolt 7. 1
Since the diameters of bolts 01 and 102 are the same, the plate 7 of the reaction force receiver must be prepared separately depending on the type of bolt 13 to be measured.

However, in some cases, the plate 7 of one reaction force receiver is used for several types of bolts to be measured, so several types of reaction force receivers are provided with mounting holes for bolt attachment on the plate 7. Good too.

The reaction force receiver is POL) 10. , 102 engage with the reaction force receiver of the electric nut runner to receive the reaction force.Depending on the shape of the reaction force receiver, the reaction force receiver is inserted into the mounting hole 9. of the plate 7. ．．
9. :9□, 9□: Select either 93.93,
The reaction force receiver is fixed to the plate 7 by a nut 11, and the reaction force receiver is mounted symmetrically with respect to the center of the plate 7.

In this embodiment, the reaction force receiver is shown in which bolts 101 and 102 are attached to mounting holes 9□ and 91.

The support fitting 12 is fitted into the open end of the insertion hole 2 of the load cell 1 to support the head of the bolt 13 to be measured, and is available in several sizes depending on the diameter of the bolt 13 to be measured. will be prepared.

The bolt to be measured 13 is inserted into the insertion hole 2 of the load cell 1, the insertion hole 6 of the plate thickness adjustment adapter 5, and the reaction force receiver is inserted into the insertion hole 8 of the plate 7.
The threaded portion at the tip of the reaction force receiver is temporarily tightened with a nut 14 on the outside of the plate 7.

Next, taking as an example the case where a member to be tightened that is thicker than the load cell 1 is to be tightened with a bolt using an electric nut runner, the tightening torque of the bolt is set using the torque method using the bolt axial force measuring device having the above-mentioned configuration. Let's explain the case.

As shown in Fig. 1, first, the load cell 1, the plate thickness adjustment adapter 5, and the reaction force receiver have bolts 10□, 10□ fixed to them. Adjust the thickness using the plate thickness adjustment adapter 5 so that the thickness is the same as that of
A pole to be measured 1-13 having the same dimensions as the bolt is inserted through the support fitting 12 and the insertion hole 2.6.8, its head is supported by the support fitting 12, and a nut 14 is screwed into the threaded portion of the tip. At the same time, the bolt 13 to be measured is temporarily tightened.

After that, the pair of reaction force receiving claws of the reaction force receiver provided on the electric nut runner are brought into contact with the pair of reaction force receiving bolts 101 and 102 so as to receive the reaction force when the electric nut runner is driven to rotate. At the same time, the socket of the electric nut runner is fitted into the nut 14 screwed into the bolt 13 to be measured.

Next, when the electric nut runner is driven to rotate, the nut 14 rotates, the bolt 13 to be measured is tightened, and the load cell 1, plate thickness adjustment adapter 5, and reaction force receiver compress the plate 7.

At this time, the amount of compressive displacement of load cell 1 is the strain gauge 3
, and the indicator 4 is instructed to do so.

When the load cell 1, plate thickness adjustment adapter 5, and reaction force receiver compress the plate 7, tension or axial force acts on the bolt 13 to be measured along the axial direction, and this axial force causes the compression displacement of the load cell 1. Since there is a correlation, the compressive displacement can be converted into an axial force, and the axial force of the bolt 13 to be measured for a predetermined tightening torque can be measured.

Here, in the bolt axial force measuring device, the load cell 1, the plate thickness adjustment adapter 5, and the reaction force receiver plate 7 are combined to determine the overall load/displacement relationship between the load/displacement of the member to be tightened that is actually used.
Since the displacement relationship is set to be the same as that of the displacement relationship, the displacement of the load cell 1, plate thickness adjustment adapter 5, and reaction force receiver plate 7 when the bolt 13 to be measured is tightened with a predetermined tightening torque is the same tightening torque. The displacement of the bolt to be tightened when the bolt is actually tightened is approximately the same as the displacement of the bolt to be tightened. It is approximately the same as the axial force acting on the bolt that tightens the attachment member.

Therefore, the axial force of the bolt 13 to be measured can be measured under the same conditions as when actually tightening the member to be tightened, and the axial force of the bolt to be actually used can be estimated from the axial force.

In particular, when tightening using an electric nut runner and setting the tightening torque value, the actual tightening torque value must be adjusted by taking into account the torque increase due to the electric nut runner's power cut-off during calibration using a bolt axial force measuring device. Accurate axial force measurement can be performed by eliminating the difference from the actual tightening torque.

Similarly, the relationship between the rotation angle of the nut 14 of the bolt axial force measuring device and the axial force of the bolt 13 to be measured is the same as when the member to be tightened is actually tightened with bolts and nuts. When tightening a bolt or nut using the rotation angle method, by setting a predetermined rotation angle on the electric nut runner, the axial force of the bolt when the tightened member is actually tightened can be measured by measuring the bolt 13 to be tightened. It is possible to make it approximately the same as the axial force of.

On the other hand, for the reaction force receiver of the bolt axial force measuring device, a plate 7 corresponding to the bolt 13 to be measured is prepared according to the actual usage conditions, and a plate 7 corresponding to the bolt 13 to be measured is prepared according to the actual usage conditions. ,9. ~ Select 93, 93 and use the reaction force receiver as pol) 10. ．． 10□ can be installed, so when performing a tightening operation using an electric nut runner, the same reaction force receiver as when actually tightening the member to be tightened can be used at the bolt installation position and the reaction force with the thread diameter. Force receiver is bolt 100,10
2 can receive reaction force.

Therefore, it is possible to eliminate the difference between the axial force of the bolt to be measured measured by the bolt axial force measuring device of the present invention and the axial force of the bolt that actually tightens the member to be tightened.

Based on these facts, the tightening torque to be controlled for the bolt is determined using an axial force meter and a torque wrench as in the past, and after the bolt is actually tightened to the member to be tightened using an electric nut runner, it is checked using a torque wrench. There is no need to go through the trouble of calibrating the settings of the electric nut runner.

The plate thickness adjustment adapter 5 is used to set the load cell 1 and reaction force receiver to the same value when the relationship between the thickness of the plate 7 and load/displacement is different from the actual thickness and load/displacement of the member to be tightened. The reaction force receiver plate 7 is used to receive reaction force under the same conditions as in reality when tightening with an electric nut runner, and the plate thickness adjustment adapter 5 is used when necessary. .

The bolt axial force measuring device of the present invention can be widely used to measure the axial force of a bolt.

As explained above, the bolt axial force measuring device of the present invention has the following features:
The bolt to be measured is inserted into the load cell, the plate thickness adjustment adapter and the reaction force receiver are inserted into the insertion holes of the plate, and the nuts are screwed together. This electric nut runner tightens the nut screwed onto the bolt to be measured by applying the reaction force of
This is a device that measures the axial force of the bolt to be measured, and can set the load/displacement relationship of the load cell to be the same as the load/displacement relationship of the actual tightened member, and can Since the tightening torque or the increase in the rotation angle of the nut is also included, the axial force of the bolt to be measured can be measured under the same conditions as in reality.

Further, since the reaction force receiver receives the reaction force of the electric nut runner with the bolt in the same state as in reality, it is possible to eliminate the difference between the set torque of the electric nut runner and the tightening torque during actual tightening.

Therefore, when measuring the axial force of a bolt using an electric nut runner under the same conditions as when actually tightening the member to be tightened, it is possible to measure the same axial force as when actually tightening. To accurately and directly estimate the axial force of a bolt without any troublesome effort.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the bolt axial force measuring device of the present invention, and FIG. 2 is a plan view of a reaction force receiver plate. 1...Load cell, 3...Strain gauge, 5...Plate thickness adjustment adapter, 7...
...The reaction force receiver is a plate, 9. 9□, 9□, 93, 93...Mounting hole, 108,
102...Reaction force receiver is bolt, 13...
Volt to be measured.

Claims (1)

[Scope of utility model registration request] A load cell that includes a strain gauge provided on the outer periphery and an indicator connected to the strain gauge and has an insertion hole in the center, and a plate that is arranged concentrically with the load cell and has an insertion hole in the center. An adjustment adapter, a counter-mounting plate that is arranged concentrically with the plate thickness adjustment adapter, has a plurality of pairs of mounting holes of different thread diameters provided at different distances from each other symmetrically with respect to the center, and has an insertion hole in the center. The force receiver is attached to a plate, the reaction force receiver is screwed into the mounting hole of the plate, and the reaction force receiver is fixed to the plate in accordance with the actual tightening conditions. The load cell, plate thickness adjustment adapter, and reaction force receiver are adjusted by the plate thickness adjustment adapter so that the sum of the plate thicknesses is equal to the actual thickness of the member to be tightened, and the bolt to be measured is is inserted into the insertion hole, and the bolt to be measured is tightened to detect the reaction force, and the reaction force receiver is fixed symmetrically with respect to the center of the plate to match the actual tightening conditions. The receiver is received by a bolt, and the bolt to be measured is tightened with a nut under the same conditions as when the member to be tightened is actually tightened with a bolt or nut, and the bolt is set on the load cell as instructed by the indicator. A bolt axial force measuring device characterized in that the axial force of the bolt to be measured is measured from the amount of compressive displacement of a strain gauge.