Treatment of the problem of too wide heat-affected zone of small-diameter thick-walled pipe welds

In the process of high-frequency induction welding, especially in the production of products with thick wall and small diameter, such as small pipes of 1 inch and below, the wall thickness is relatively thick. Generally, we will encounter a particularly wide heat affected zone at the weld, exceeding 1 / 3 of the pipe diameter arc surface, or even 1 / 2 of the pipe diameter arc surface. If the pipe diameter is small, the whole pipe will even turn red, It will adversely affect the final welding performance requirements of some products, and even lead to waste products.

How to deal with the above situation, we can usually take the following measures:

1.Improve the welding frequency of high-frequency equipment. When we clarify the product requirements, we should have requirements for the selection of equipment rated frequency.

2.The induction coil used shall be matched with the application of the impedance, and the reasonable specification of the impedance shall be selected.

3.The coil designed with conductive magnet avoids the magnetic circuit and ensures the effective action of the magnetic field on the weld.

4.Improve the welding speed of high-frequency welder, speed up the production speed and limit the heat diffusion time.

5.Accurately select the coil style, adjust the winding material width of the coil, scientifically and reasonably select the copper pipe specification, and reduce the heating length of the coil.

6.Reduce the opening angle as much as possible when the spark amount of ignition allows.

High frequency welding products are used for pipes. When the pipe diameter is very small, especially when the pipe diameter is less than 1 / 2, the wall thickness is very thin, and the wall thickness is 1mm, when the steel strip enters the extrusion rod after passing through the high-frequency induction coil, it sometimes encounters the phenomenon that the steel strips on both sides of the triangular area cannot be extruded, that is, the edges on both sides are misaligned, which we call it flanging.

Reasons for this phenomenon:

1.The pipe specification and wall thickness are too thin;

2.The overall torsional strength of small diameter raw materials is not high;

3.High speed during high-speed welding;

These reasons are the objective factors of edge flanging in the process of high frequency welding.

How to avoid this phenomenon? The following measures are recommended:

1.Try to shorten the space distance between the extrusion rod and the last forming rod (guide rod) immediately following it;

2.Adjust the appropriate extrusion force;

3.Minimize the width of heat affected zone of high-frequency welding;

4.For the triangular zone of the high-frequency welding zone of the extrusion rod, it is very important for the steel belt to maintain a certain stable tension in three-dimensional space.