JPS6293887A - Control of induction heating of electrically welded tube - 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 [Technical Field of the Invention] The present invention relates to an induction heating control method for efficiently annealing a seam weld portion of an electric resistance welded tube.

[Technical deficiencies in inventions and their problems]

In controlling the post annealer that anneales the seam weld part of an ERW pipe by induction heating, the section between the seam and open seam part of the ERW pipe is detected, the inductor is lowered in the seam section, and the inductor is lowered in the open seam section. Inductor elevation control is performed to raise the inductor.

If the seam section of an ERW pipe is short, it cannot be used as a product, but in the past, the inductor descends to perform induction heating regardless of the length of the seam section, which results in wasted power and
There was a problem in that the inductor moved up and down unnecessarily.

Further, since it takes 1 to 2 seconds to raise and lower the inductor, there is a problem in that even if the seam length is usable, sufficient annealing cannot be achieved in which the inductor can be lowered in time, even if the line speed is high.

[Purpose of the invention]

The present invention prevents the inductor from lowering even in the seam section when the length of the seam portion is less than a predetermined value, thereby preventing wasted power and unnecessary operation of the inductor, and reducing the line speed as necessary. The purpose of the present invention is to provide an efficient induction heating control method for electric resistance welded pipes that improves the heating yield.

[Summary of the invention]

The present invention performs l-racking on the seam section and line speed of a seam-welded ERW tube, and changes the length of the seam section to a length that can be used as a product and the ERW tube moves during the elevation and descent of the inductor in the post annealer. By comparing the sum with the distance, it is determined whether or not the inductor can be raised and lowered, induction heating is possible, and whether the line speed needs to be reduced.Based on this, the inductor can be raised and lowered, induction heating,
This is an induction heating control method for an electric resistance welded pipe, in which the seam weld portion can be efficiently annealed by controlling the line speed and the necessary minimum heating power and the number of times the inductor is raised and lowered.

[Embodiments of the invention]

An embodiment of the invention is shown in the drawings.

In the drawing, 1 is an electric resistance welding tube, 2 is a seamless erg, 3 is a measuring roll for detecting the line speed of the electric resistance welding tube, 4 is a speedometer, 5 is a programmable controller for control (hereinafter referred to as PC), 6 is the post-annealer, and 7 is the inductor of the post-annealer.

8 is a solenoid valve that raises and lowers the inductor 7.

PO2 is Taiminogui from Seamuraerg 2: No. 1
The electric resistance welded tube 1 is tracked using the speed signal V from the speedometer 4, and the ascending and descending timing of the inductor 7 and the line speed control of the electric resistance welded tube 1 are controlled based on this signal.

Tracking is performed by shifting the focus of the register in PO5, dividing the ERW tube 1 into small sections starting from the welder 2, and determining in which small sections the seam part and the open seam part are located from the integral value of the speed V. demand.

In this case, when the welder is ON, the bit in the register is set to ``1'' to indicate that there is a seam, and when the welder is OFF, it is assumed that there is no seam, and the bit in the register is set to ``it'', thereby tracking each small section.

In the electric resistance welded tube 1 shown in the drawing, the seam section is between C and D and E and F, and the open seam section is between D and EIIJI and F-0, and M, L, and N are determined by tracking for each length. It is determined by the number of bits.

When the length of the seam is sufficiently long, for example in the case of E - F, when point E reaches point B of the inductor 7, a descending command is issued to lower the inductor 7 and induction heating is started, and the point F is reached. When reaches point A, heating is stopped and the inductor 7 is raised.

In this case, the conditions for M are v(t□+t,)+Q M≧□ ...■ where V Niline speed (s+/5ee) tl: Inductor falling time (see) t2: Inductor rising time ( see) Q: Minimum seam length that can be used as a product IIn) m: Length of the electric resistance welding tube corresponding to 1 bit IllI+).

Assuming that the minimum allowable line speed is V', when M is in the range, induction heating is performed by reducing the line speed to the minimum V'. In this case, the applied power for heating is also reduced in proportion to the speed.

If M decreases further and becomes v'(tz"tt) + Q)M...(3), an ERW tube cannot be obtained as a product, so the inductor will not be raised or lowered, and therefore heating will not be performed. do not have.

All of the above calculations are also performed at PO2, and thereby induction heating of the electric resistance welded tube is performed using the minimum necessary heating power and the minimum number of raising and lowering operations of the inductor.

〔Effect of the invention〕

As explained above, according to the present invention, the seam section of the ERW tube is tracked, and when the seam length is sufficiently long, the normal heating operation is performed, and the seam length is adjusted so that the rising and falling time of the inductor is within the interlayer. If the seam length becomes too short, reduce the line speed and reduce the heating power proportionally, and if the seam length becomes even shorter and the product as an ERW pipe cannot be obtained, do not lower the inductor, and No heating is performed, and as a result, induction heating for annealing the electric resistance welded tube can be performed using the minimum necessary heating power and the minimum number of inductor raising and lowering operations.

[Brief explanation of drawings]

The drawing is a system diagram showing one embodiment of the present invention. 1... ERW pipe 2... Seam welder 3...
・Measuring roll 4... Speed meter 5... Programmable controller (PC) 6... Post annealer 7... Inductor 8... Solenoid valve for inductor elevation

Claims (1)

[Claims] Track the seam section and line speed of seam-welded ERW tubes, and compare the length of the seam section with the sum of the product usable length and the distance that the ERW tube moves during the raising and lowering of the inductor in the post-annealer. to determine whether it is possible to raise and lower the inductor and perform induction heating, and whether or not it is necessary to reduce the line speed.
A method for controlling induction heating of an ERW tube, the method comprising controlling the elevation and lowering of an inductor, induction heating, and line speed based on this to anneal a seam weld portion of an ERW tube.