JPS5834264B2 - Bolt axial force management device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bolt 0-axis force management device, and more particularly to a bolt axial force management device that can accurately manage bolt axial force during tightening.

2. Description of the Related Art Bolts and nuts are widely used when fastening objects, such as two steel plates, together.

It is extremely important for safety to control the tightening force of the bolt when tightening the bolt, in other words, the bolt (υ axial force).

Conventionally, methods for managing the axial force of bolts during tightening include the torque method and the nut rotation angle method.

Among these, the torque method utilizes the relationship T = kdF (k is the torque coefficient, d is the nominal diameter of the bolt) between the torque T and the axial force F of the bolt, and uses k and d as coefficients. The purpose is to manage the axial force F by controlling the handling and torque T.

However, in the i-torque method, the torque coefficient k is actually not constant due to the influence of the uneven roughness of the bolt seating surface and threaded part, and therefore the The range of axial force becomes large, making it difficult to adequately manage the axial force.

Furthermore, the conventional nut rotation angle method focuses on the relationship between the rotation angle of the nut and the axial force of the bolt, and attempts to manage the axial force by setting the rotation angle of the nut to a predetermined value. .

In this nut rotation angle method, the bolt is tightened to the plastic range by rotating the nut, so even if there is some variation in the rotation angle of the nut, the variation in the axial force F is small, and therefore the above-mentioned torque The axial force can be managed more stably than the conventional method.

However, in this nut rotation angle method, since the bolt is tightened to the plastic range, there is a risk that the bolt will break, which makes it difficult to use bolts made of materials with low ductility.

When considering axial force management in the elastic region, in the nut rotation angle method, the rotation angle of the nut is read visually, so a large axial force F corresponding to the reading error of the rotation angle is calculated. cause an error.

Therefore, it was impossible to manage the axial force using the conventional nut rotation angle method in the elastic region.

In addition to the conventional axial force control method, the following axial force control method using a washer has been proposed.

FIGS. 1 to 3 are explanatory diagrams illustrating this conventional axial force management method.

In these figures, 1 is an object to be tightened, 2 is a bolt that fastens this object 1, 3 is a nut that is screwed onto the bolt 2, 4 is a plain washer, and 5 is a bolt that penetrates through the bolt 2c. and bolt 2
This is a washer used for zero axial force management.

As shown in FIG. 3, the washer 5 has a curved shape as a whole, and as shown in FIG. It has become.

Figure 1 a corresponds to the view from the direction A of the third diagram;
The figure corresponds to the view from direction B in FIG.

When the tightening is completed, the washer 5 is shown in Figure 2.
is plastically deformed and becomes flat when viewed from two directions.

FIG. 4 shows the above process in terms of the relationship between the axial force F of the bolt 2 and the rotation angle θ of the nut 3.

In G in the same figure, 6 is an elastic region, 7 is a constant axial force region due to plastic deformation of the metal fitting 5, 8 is a region where plastic deformation of the washer 5 is completed and shows re-elastic behavior, and 9 is a plasticity region of the bolt shaft. area.

As shown in this figure, when bolt tightening is completed within the constant axial force region 7 due to plastic deformation of the washer 5, the axial force F of the bolt 2 becomes constant over a very wide range of rotation angle θ of the nut 3, and the nut This means that the setting error of the rotation angle θ of No. 3 can be ignored.

If the axial force Ff at this time is taken into consideration when manufacturing the washer 5, highly accurate axial force management can be performed.

However, in this conventional axial force management method using a washer, the processing of the washer 5 is more troublesome than that of a flat washer that is generally commercially available, and the plastic deformation of the washer 5 causes the bolt 2 to deform. Since the material and shape must be considered depending on the strength of the bolt 2, as occurs with the set axial force Ff, there is a problem in that the manufacturing of the washer 5 requires a lot of cost.

Furthermore, once the washer 5 has been tightened, it is plastically deformed and cannot be reused.

The present invention has been made in view of the actual situation in the prior art described above, and its purpose is to accurately manage the axial force of the bolt during tightening, and to eliminate the need for a specially shaped washer. The objective is to provide a management device.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 5 is an explanatory diagram showing the configuration of one embodiment of the bolt axial force management device of the present invention, and FIGS. 6 and 7 are explanatory diagrams of bolt tightening work in the axial force management device shown in FIG. Fig. 6 is a side view including a partial cross section showing the state immediately before tightening, and Fig. 7 is a side view including a partial cross section.
The figure is a side view including a partial cross section showing the state when tightened.

In these figures, reference numeral 10 denotes a round flat washer that can be inserted into a bolt 2 that fastens an object 1 to be fastened.

Sensors 11, 12, 13, and 14 are arranged near the washer 10 in four directions, and output a voltage corresponding to the distance from the circumferential side of the washer 10.

15 is an arithmetic circuit, and the above-mentioned sensors 11, 12, 13,
14, and these sensors 11, 12, 13
, 144, thereby calculating the average value of the output voltages.

A comparison circuit 16 is connected to the arithmetic circuit 15 and compares the average value obtained by the arithmetic circuit 15 with a set value input in advance (described later).

A display circuit 17 is connected to the comparison circuit 16, and receives a signal based on the comparison result between the average value and the set value in the comparison circuit 16 and generates a display signal.

This display circuit 17 is equipped with a means for displaying colored lights such as a lamp, or an alarm buzzer, and based on the comparison result by the comparison circuit 16, a predetermined display signal is sent to the means for displaying these colored lights or Send an alarm buzzer to display colored lights or emit an alarm sound.

Such a display circuit 17 can take various forms by combining known techniques.

In the bolt 0-axis force management device configured in this way, as shown in FIG. An axial force is generated and this bolt 2 is pulled, and the washer 1
Conversely, compressive force is applied to the bolt 2 by the head of the bolt 2 and the object 1 to be fastened.

Therefore, the washer 10 contracts in the thickness direction and expands in the lateral or radial direction, as shown in FIG.

In Figures 5 to 7, Do is 0 immediately before tightening work, washer 1
0 and D are the diameters of the washer 10 when tightened.

If the change in the diameter of the washer 10, that is, D-Do, is JD, then the relationship between this JD and the axial force F of the bolt 2 is as shown in FIG. It is a proportional relationship, and in the plastic region, with respect to the axial force F, ! (D increases rapidly.

Note that ADf is the change in diameter when the axial force is Ff.

Further, as the washer 10 deforms, the distance between the circumferential surface of the washer 10 and the sensors 11, 12, 13, and 14 also changes.

In FIG.

is the distance between the circumferential side of the washer 10 and the sensor 11 immediately before the tightening operation, and l is the distance between the circumferential side of the washer 10 and the sensor 11 at the time of tightening.

Note that the values of lo and l are the same for the other sensors 12913 and 14.

And the peripheral side of the washer 10 and the sensors 11, 12, 13, 1
4, i.e., the change in distance from l.

-4 is All, this AI and sensors 11, 12,
The relationship between output voltages 13 and 14 is expressed as a proportional relationship as shown in FIG.

Note that the above AD and ljl have a relationship of AD=2A11.

From the relationship between Figures 8 and 9, the axial force F of bolt 2 and sensor 1
1, 12, 13.14 and the output voltage e are as shown in FIG. 10, and are proportional within the elastic range.

Therefore, by focusing on the relationship within such an elastic range, the axial force F of the bolt 2 can be managed.

For example, if the management target value of the axial force F is Ff, then this value F
The output voltage e of the sensor corresponding to f is ef from FIG.

This voltage ef may be input to the comparison circuit 16 as the above-mentioned set value, and compared with the output voltage from the sensors 11, 12, 13, and 14.

When performing predetermined bolt tightening work with such setting values inputted in advance to the comparator circuit 16, the sensors 11, 12, 13.
An arithmetic circuit 15 calculates an average value based on the voltage output from the voltage generator 4, and a comparison circuit 16 compares the average value with a set value.

This comparison circuit 16 issues a signal to the display circuit 17 when, for example, the average value and the set value match.

The display circuit 17 includes a lamp that lights up in red, for example, and sends a display signal to the lamp based on the signal from the comparison circuit 16, thereby lighting the lamp.

A worker who is performing bolt tightening work stops the bolt tightening work when this lamp lights up in red.

In the above description, the washer 10 is described as having a round or flat plate shape, but it is not limited to this, and may be rectangular or cylindrical.

As mentioned above, the bolt 0-axis force management device is equipped with multiple sensors around the washer that can penetrate the bolt, and uses the sensors to detect changes in the lateral dimension of the washer when the bolt is tightened. Since it is configured to manage the axial force of the bolt through a circuit and a display circuit, it produces the following effects.

■ Since it is not affected by the friction of the bolt seating surface or threaded part, which is the case with conventional torque methods, the axial force of the bolt can be accurately controlled, resulting in high tightening accuracy.

- Unlike the conventional nut rotation angle method, it is possible to manage the axial force in the elastic range O, which eliminates bolt breakage due to over-tightening and improves safety.

- Since there is no need to make the washer into a special shape, a commercially available washer can be used and can be reused, and the cost required for the washer can be suppressed.

[Brief explanation of drawings]

1 to 3 are explanatory diagrams illustrating a conventional bolt axial force management method using a washer, and FIG. b is a side view showing the state before tightening, Fig. 2 is a side view showing the state after tightening is completed, Fig. 3 is a perspective view showing the washer used in this conventional axial force management method, and Fig. 4 5 is a characteristic diagram showing the relationship between the bolt axial force and the rotation angle of the nut in the bolt axial force management method illustrated in FIGS. 1 to 3, and FIG. FIGS. 6 and 7 are explanatory diagrams showing the configuration of one embodiment, and are explanatory diagrams illustrating bolt tightening work in the bolt axial force management device shown in FIG.
FIG. 6 is a side view including a partial cross section showing the state immediately before tightening, FIG. 7 is a side view including a partial cross section showing the state when tightening, FIGS. 8, 9, and 10. The figures are characteristic diagrams illustrating the effects of the bolt axial force management device shown in Figure 5, Figure 8 is a characteristic diagram showing the relationship between changes in washer diameter and bolt axial force, and Figure 9 is a characteristic diagram illustrating the effect of the bolt axial force management device shown in Figure 5. 10 is a characteristic diagram showing the relationship between the change in the distance between the washer and the sensor and the output voltage of the sensor, and FIG. 10 is a characteristic diagram showing the relationship between the axial force of the bolt and the zero output voltage of the sensor. 10... Washer, 11, 12, 13, 14...
...Sensor, 15...Arithmetic circuit, 16...
... Comparison circuit, 17... Display circuit.

Claims (1)

[Claims] 1 In a bolt axial force management device that manages the axial force when tightening a bolt that fastens an object to be fastened, a flat or cylindrical washer that can penetrate the bolt, and a washer that is close to the circumferential side of the washer A plurality of sensors are arranged and output a voltage corresponding to the distance to the circumferential surface, and connected to these sensors,
An arithmetic circuit that calculates the average value of the voltage output by these sensors, a comparison circuit connected to this arithmetic circuit that compares the average value obtained by the arithmetic circuit with a pre-input setting value, and this comparison circuit. and a display circuit that receives a signal based on the comparison result in the comparison circuit and issues a display signal, and the bolt is tightened with the washer penetrated into the bolt, and the bolt is tightened with the washer inserted into the bolt. A bolt axial force management device characterized in that the bolt zero axial force is managed based on changes in the lateral dimension of the washer.