JPS5825821A - Control of tube expanding - Google Patents

Abstract

PURPOSE:To minimize dispersions of wall thinning rate in tube expanding and to improve product qualities by integrating a torque wave form above a prescribed level, and by ending expanding when the integration reaches a prescribed value. CONSTITUTION:A torque converter 2 is provided between a tube expanding mandrel 1 and a drive motor 3 for rotating the mandrel 1, and a torque detector 4 detects a torque required for a tube expanding. A torque setter 6 with a slightly higher setting than normal used as a means for detecting abnormalities. A torque level setter 8 is input with output signals of the torque detector 4, and outputs torque signals above a prescribed level to a torque wave form integrater 9. The integrater 9 integrates torque signals per unit time, and outputs them to a comparator 11. At the same time the comparator 11 is input with prescribed torque values from a torque wave form setter 10 and compares both input torque values and stops the drive motor 3 to complete expanding when the integrated torque value reaches a prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method of controlling a tube expansion process in which a tube is fixed to a tube plate by expanding the tube.

The roller expansion method is often used to secure the tubes and tube sheets of multi-tube heat exchangers and the like together. In other words, rollers are arranged around a tapered mandrel at a feed angle, and the mandrel is rotated to force the tube into the hole in the tube plate using the roller and fix it. Conventionally, this process was controlled. is performed using either the peak tube expansion current value or the peak torque value.

However, with this control method, there is a problem that the tube expansion rate of thinning varies widely and uniform processing cannot be performed, resulting in a decrease in the reliability of products such as heat exchangers.

In view of the actual situation of the conventional method described above, the present invention aims to provide a highly reliable tube expansion method with small variations in the tube expansion thinning rate, and also has the effect that the conventional control device can be used as is, and the machining torque is increased. of the detected torque, extracts only the torque signal above a certain level, integrates the torque signal per unit time, and stops the pipe expansion process when the integrated torque value reaches a certain value. It is something to do.

Embodiments of the present invention will be described below with reference to FIG. The area surrounded by the dotted line in FIG. 1 shows a conventional device that performs control using a peak torque value. That is, a torque converter 2 is provided between a tube expansion mandrel 1 and a drive motor 3 that rotationally drives the tube expansion mandrel, and a torque detector 4 detects the torque for tube expansion processing. Conventionally, the signal from the torque detector is input to the comparator 5 along with the output from the peak torque setter 6, and the two are compared.

The result is input to the controller 7, and when the torque for tube expansion reaches a certain value, the drive motor 3 is stopped and the machining is completed.9 In this embodiment, the setting value of the peak torque setting device 6 is specified. By making it slightly higher, it can be used as a means of detecting abnormalities during tube expansion processing.

Reference numeral 8 represents a torque level setter, which is connected to the torque level setter 1.8 of the torque detector 4.
An output signal is input, and only torque signals above a certain level are output to the torque waveform integrator 9. The torque waveform integrator 9
Then, torque signals per unit time are integrated and outputted to the comparator 11. At the same time, the torque value set to a predetermined value from the torque waveform setting device 10 is input to the comparator 11, and the two are compared. When the integrated torque value reaches a certain value, the controller 7 stops the drive motor 3. to finish machining.

According to the present invention, during pipe expansion processing, the torque waveform above a certain level is integrated, and processing is terminated when the value reaches a certain value, thereby reducing variations in the pipe expansion thinning rate compared to conventional methods. It is possible to make it smaller. This is clear from the machining results lζ shown in FIGS. 2 and 3.

This is the distribution of meat percentage. FIG. 3 shows the control method using the conventional torque peak value. FIG. 3(a) shows the torque waveform during pipe expansion, and FIG. 3(2)) shows the distribution of the wall thinning rate during pipe expansion. Comparing the two, it can be seen that the control method of the present invention has smaller variations in the tube expansion wall thinning rate. Note that the torque level set value greatly affects the controllability of the tube expansion thinning rate, so it is necessary to prepare data in advance based on the 9 dimensional specifications of the tube material, etc., and to deal with this.

As is clear from the above, according to the control method of the present invention, it is possible to obtain machining results with smaller variations in the tube expansion thinning rate compared to machining using conventional peak torque control.
Improve product quality. Further, as the apparatus for controlling processing according to the present invention, it is possible to use an apparatus based on a conventional peak torque control method as is.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment according to the present invention. FIG. 2 shows the results of processing according to the present invention, in which (a) is a torque waveform and level setting value during tube expansion, and (b) is a diagram of the distribution of the wall thinning rate during tube expansion. Further, FIG. 3 shows processing results according to the conventional method, in which (a) is a torque waveform during tube expansion, and (b) is a diagram showing the distribution of the rate of wall thinning during tube expansion. 1... Mandrel for pipe expansion, 2... Drive motor, 3...
... Torque converter, 4... Torque detector, 7... Controller, 8... Torque level setter, 9... Torque waveform integrator, 10 - Torque waveform setter, 11 - Comparison Figure 3 (Ron & Kankei + (Z)

Claims (1)

[Claims] In pipe expansion processing using a roller expander. The processing torque is detected, only the torque signals above a certain level are extracted from the detected torque, the torque signals are integrated per unit time, and the pipe expansion processing is stopped when the integrated torque value reaches a certain value. Characteristic control method for tube expansion processing.