3.High Frequency Welding

1. Temperature: The tube blank needs to be guided by a guide roller before heating to ensure that the tube seam does not have any deflection. Under the action of the high-strength current in the inductor, it quickly reaches the welding temperature, and the welding is achieved under the action of the squeeze roller purpose.

2. Pressure: The squeeze roller should apply sufficient welding pressure to the edge of the tube blank. The welding pressure is one of the main factors affecting the quality of the weld. If the pressure is too small, the bonding force between the molten metals is small, the low melting point inclusions are not easy to squeeze, and the weld is easy to crack when stressed. If the pressure is too high, it is easy to make the joints, the burrs inside and outside the weld are large, and the planer blade is uneven and affects the appearance, so the squeeze roller should be moderate. In order to ensure the fullness, uniformity and continuity of the welding ribs in the pipe, the appearance of overlap can be avoided.

3. The opening angle and length of the welding seam. The opening angle refers to the angle between the two edges of the tube blank before the squeeze roll, which usually varies between 4-7 degrees. The size of the opening angle is related to the stability of the sintering process. The quality influence is great. Reducing the opening angle can strengthen the proximity effect, increase the heating temperature of the edge, and increase the welding speed, but the opening angle cannot be too small. If the opening angle is too small, the distance from the meeting point to the center line of the extrusion will be lengthened. As a result, the edges are squeezed side by side at the highest temperature, which reduces the welding quality. If the opening angle is too small, after the liquid is excessively opened, it will move to the welding point under the action of the magnetic line of force (the density of the magnetic line of force at the V-shaped angle is the largest) and gather into a large excessive explosion and form a deep pit that is difficult to press. Welding quality: If the opening angle is too large, the proximity effect will decrease, the welding speed will decrease, and the power consumption will increase. The distance from the center line of the squeeze roller to the sensor is the length of the opening angle. The length of the opening angle will increase the impedance of the welding seam and reduce the effective value of the current. Therefore, the length of the opening angle should be of different specifications without affecting the welding quality. Adjustment.

4. Magnetic rod: High-frequency welding magnetic rod (ferrite) has higher specific resistance and low eddy current loss. It is widely used as an intensifying element in high-frequency welded pipes, so that electromagnetic energy is more concentrated in The welding surface of the pipe seam increases the welding speed, but the magnetic permeability of the magnetic bar decreases with the increase of temperature, and it starts to drop sharply at 250 degrees. Therefore, during the production process, it must be fully cooled with water. If the cooling is not good , It will cause the magnetic rod to break and affect the welding quality. The position of the magnetic bar should be adjusted properly after the opening angle is adjusted. The position of the magnetic bar should be adjusted according to the welding temperature. Generally, one end of the magnetic bar should be placed in the center of the two squeezing rollers.

5. The material of the inductor is red copper plate or steel pipe. In the case of no discharge, the closer the distance between the leads, the better, the closer the leads will increase the inductance, and make the weld current intensively flow on the weld surface , And improve welding efficiency.

4.Welding Scar

The planer knife plays a great role in the appearance and quality of the product, and it is also a key process in the product quality. Therefore, the grinding of the planer knife is important. The burr squeezed onto the surface of the steel pipe during welding should be removed by the planer knife. The amount of knife should be moderate. The surface should be smooth and flat, without unevenness, and no traces of welding scars.