JPS59214569A - Screw clamping control method - 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 (Field of Industrial Application) The present invention relates to a screw tightening method, and more particularly to a nut runner torque control method for tightening a nut to a specified torque value.

(Prior art) In the conventional nut runner, as a screw tightening control method,
A method of fastening screws using a mechanical mechanism, a method of cutting off the shaft drive source at a constant torque or angle using a torque sensor or an angle sensor, etc. have been used.

The former has problems in terms of mechanical durability and cost, while the latter has problems in maintaining the quality of the screw axial force due to variations in the shaft drive source. In particular, when trying to apply a specified tightening torque to both, automation is not possible due to mechanical inertia.
Open control is performed by determining the stop timing. Further, mechanically, it is difficult to maintain constant torque transmission efficiency between the reduction gear portion and the joint portion.

(Object of the Invention) The present invention relates to a screw tightening control method. This was done to improve the above-mentioned drawbacks, and provides a screw tightening control method that shuts off the shaft drive source without overrunning the nut run rate.

(Structure of the Invention) A feature of the present invention is that a torque sensor installed in a shaft drive device collects data in time series, and based on the data, a control device calculates a rate of change in torque, and uses the data as a base point for calculation. The method is to extrapolate the tightening torque from the determined change rate to predict the stop timing before overrun of the shaft drive device due to inertia, and to stop the shaft drive device based on the predicted value.

(Example) Hereinafter, one embodiment of the present invention will be explained with reference to the drawings.

The tightening torque of the nut runner is measured by a torque sensor, and when the shaft power source cutoff torque is reached.

Even if you try to shut off the shaft drive source, it will not stop immediately due to the response delay of the solenoid valve, inertia, and other effects.
Torque values measured in advance by a torque sensor installed in the shaft drive device of the nut runner are stored in chronological order, and as shown in Fig. 1, the tightening torque becomes the control starting torque T.
Control is performed using the torque value and torque change rate Gt after reaching s. The target value of the final tightening torque is T
o, and the torque value Tc for cutting off the shaft drive source is the overrun time set value Δt, where the time is t.
"tt From t+, Tc=To-riT×Δt...
...(1) Calculate and obtain by t. This is done for each tightening cycle to automatically predict and control.

The actual processing steps, as shown in FIG. 2, first check the torque value to see if the tightening torque has reached the control start torque T8 (procedure 1).

If the torque value is below Ts, repeat the same procedure.

If the torque value is 18 or more, one equation is calculated using the torque conversion rate G, and the result is set as t Tc (step 3). Compare whether the value of Tc is larger than the upper limit set value Tcu of torque when the drive source is cut off (Step 4)
, if Tc is larger than TCU, set the value of Tc to TCU
, and proceed to the next step (Step 5). Next, Tc
The value of is the lower limit setting of the torsion when the drive source is cut off, and the set value TC
Compare whether Tc is smaller than L (step 6). If Tc is smaller than TCL, replace the value of Tc with the value of TCL and proceed to the next step (step 7). Check the torque value to see if the tightening torque has reached Tc (step 8).

If the tightening torque has not reached Tc, repeat the same procedure.

If the torque value has reached Tc, the shaft drive source is shut off (step 9), and it is determined whether the final tightening torque is acceptable (step 10).

In this way, the timing for shutting off the shaft drive source of the nut runner can be predicted and corrected from the torque value during tightening and the rate of change at that time. Also, by applying torque while correcting each tightening cycle, timely tightening control becomes possible. For this reason,
Appropriate tightening control can be performed depending on the parts to be tightened and the process.

In the above embodiment, the tightening torque is measured and compared, but as an application example, an angle sensor that detects the screw rotation angle is installed in the shaft drive device, and the specified rotation is performed based on the measured value of the rotation angle. Torque control can also be indirectly performed using a method that performs predictive control on the angle.

(Effects of the Invention) In the screw tightening control method according to the present invention as described above, the cutoff timing of the shaft drive source of the nut runner is predicted from the torque value during tightening, and is corrected to prevent the shaft drive source from overrunning. It can be blocked. Therefore, the accuracy of tightening control is improved, and it can be easily adapted to changes in the usage environment and the tightening conditions of the product.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for calculating the torque value when the shaft drive source is cut off in the method according to the present invention, and FIG. 2 is a flowchart showing the torque control procedure in the method according to the present invention. To...Aim value of the final tightening torque Tc...Torque value when the shaft drive source is cut off TCU...Upper limit set value of Tc Tct,...Lower limit set value of Tc Ts...Control start torque value (Torque value for calculating torque change rate) Δt...Overrun time T1...Torque change rate patent Applicant Toyota Motor Corporation agent Patent attorney Yu Kaede 1 person yjl Time tt tz

Claims (1)

[Claims] (1) The torque sensor installed in the shaft drive device collects data in time series, the control device calculates the rate of change in cytosine based on the data, and then performs the analysis using the base data and the calculated rate of change. A screw tightening control method characterized by extrapolating applied torque to determine a stop timing before overrun due to inertia of a shaft drive device, and stopping the shaft drive device based on the predicted value.