JPS6056871A - Method of clamping bolt and nut - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for tightening bolts and nuts, and an object of the present invention is to provide a method for always tightening bolts and nuts 1 with an optimal tightening torque value.

That is, the method of tightening the nut to port 1 of the present invention is D.
When tightening Pol 1- and Narrow 1- with the Pol 1-/Nut tightening device using the C motor as the drive source, the tightening torque value is set at regular intervals after the Pol I/Nut is seated. The tightening torque is measured, and the rate of change of the sequentially measured tightening torque value is calculated with respect to the immediately preceding value, and when this rate of change becomes less than or equal to a predetermined value,
Moreover, when this continues a predetermined number of times, the power source of the drive source is stopped while being reversed.

First of all, the 1-torque tightening curve for bolts and nuts is expressed as shown in FIG. 1, with the time required for tightening on the horizontal axis and the 1-torque tightening on the vertical axis.

In Figure 1, point A is the point where the bolt/nut begins to be screwed into the screw hole/pole I-, point B is the point when the bolt/nut has finished screwing in and is seated, and point 0 is the seating point B. The tightening torque starting from reaches the maximum and Pole 1/Nara 1- is the yield point where the elastic region transitions to the plastic region.

Here, the tightening of bolts and nuts corresponds to the period from seating point B to before reaching yield point C in the tightening torque curve of FIG. 1, and this is also called an elastic region.

By the way, an appropriate tightening torque value for bolts and nuts exists within an elastic range as close as possible to the yield point C, which can be called the end point of the elastic range. That is, by tightening the bolt/nut to the end point of this elastic range, the maximum usable tightening torque of the bolt/nut can be achieved.

The present invention always attempts to tighten Pol 1- and Nara 1 with an optimal tightening torque value within the elastic range as close as possible to the yield point in the tightening 1-torque curve, and for this reason, the invention The authors focused on the fact that the tightening torque curve shown in Figure 1 has a gentler slope in the portion near the yield point C in the elastic region, and calculated the change in the rate of change based on the tightening torque values measured at regular time intervals. Detects that the tightening has reached just before the yield point C using
This is an attempt to control the tightening device. That is, after the bolt/nut is seated, the tightening torque value is measured at fixed time intervals 15, and the rate of change of the sequentially measured tightening torque value with respect to the immediately preceding one is calculated, and when this rate of change becomes smaller, it is set in advance. Detects that it is close to yield point C when it reaches a value (a small rate of change value near yield point C),
In addition, the calculated rate of change value must be less than or equal to the preset value.If this phenomenon occurs only once, it is practically unreliable, so only when this phenomenon reaches the preset number of times will the power supply of the drive source of the tightening device be turned off. This will cause the system to stop.

What should be noted here is the time interval for measuring the tightening torque, and in order to ensure accurate measurement, it is desirable to keep the time interval as short as possible at regular intervals. What is even more important is the set value and set number of times of change, which are the conditions for stopping the tightening device. You have to decide on something suitable. However, since these vary depending on the shape and size of the bolts and nuts, the tightening device, etc., they are not uniform and must be set appropriately according to a number of conditions.

In addition, when stopping the power source of the drive source of the tightening device, the power source of the drive source is stopped while being reversed so that the inertia force is canceled and the tightening device suddenly stops.

Next, examples of the present invention will be described.

In this embodiment, for example, when tightening a head cover tightening bolt to an engine head using a tightening device driven by a DC motor, the bolt is seated for 50 minutes.
Tightening torque value T immediately before the tightening torque value 'rn (at time tn) that is sequentially measured by subtracting the tightening torque value at fixed time intervals of 0 μsec. -5 (time tn-1), and when this rate of change becomes less than the set value 2710 and this happens 5 times in a row, the power source of the drive source is stopped while reversing the power source. be.

Next, Fig. 2 shows an example of a device for carrying out the present invention, in which a strain gauge (3) is attached to the rotational tightening shaft (2) of the tightening device (1).
is set, the tightening torque is measured, this output is read by the torque value reading means (4), and the torque curve storage means (
5), and further inputted to the torque curve comparison means (6), where the rate of change from the immediately previous torque value stored in the torque curve storage means (5) is calculated, and this is stored in advance in the comparison standard setting means (6). 7), and when the number of times set by the setting means (7) has been reached, the drive control section (8) of the tightening device (1) is controlled to control the DC motor drive source. (9) The power supply is stopped while being reversed.

In addition, each means (4), (5), (6) in Figure 2
, (7) can be easily configured with a microcomputer (CC, PU).

As described above, the method for tightening bolts and nuts 1- of the present invention involves measuring the tightening torque at regular time intervals from the seating point to the yield point, and measuring the tightening torque immediately before tightening the bolts and nuts 1-. The rate of change is calculated, and tightening is terminated when this rate becomes less than a predetermined value and the tightening is completed a predetermined number of times, so the optimum tightening torque value is always accurately as close as possible to the yield point. It is now possible to tighten.

[Brief explanation of drawings]

FIG. 1 is a tightening torque curve for bolts and nuts, and FIG. 2 is an explanation of an example of the device according to the present invention. Patent applicant Tokyo Boeki Co., Ltd.

Claims (1)

[Claims] When tightening bolts and nuts with a bolt/nut tightening device that uses a DC motor as a drive source, Pol 1 ~ / Nara 1 ~
After the seat is seated, the tightening torque is increased at regular intervals,
Calculate the rate of change of the sequentially measured tightening torque values with respect to the immediately preceding one, and when this rate of change becomes less than a predetermined value and this continues for a predetermined number of times, the A method for tightening bolts and nuts 1~, characterized by stopping them.