The close contact between the profile and the sizing device is achieved by vacuuming the vacuum grooves and holes in the outer wall of the given device. If there is no floating plug in the profile, just increase the atmospheric pressure. However, for closed hollow profiles, there are a large number of shaping devices. For example, there are three sections for the shaping device of the door and window profiles, each of which is about 400 to 500 mm long.
In the first stage, the profile is plastically deformed by tension and pressure, and is attached to the inner wall of the cavity to form a cross-sectional shape conforming to the sizing device. If there are special parts on the profile, such as grooves, flanges, etc., it can be formed in the last section of the sizing device to prevent clogging of the profile.
2. Pressurization setting
This type of shaping mainly relies on the compressed air inside the profile introduced by the die core die. Generally, the air pressure reaches 0.02-0.1 MPa, so that the surface of the profile can be completely attached to the cavity surface of the sizing device.
Because there is a certain pressure inside the profile, and the contact time of the profile and the sizing device is long, when the shaping method is adopted, a profile with a higher outer surface dimensional accuracy and a brighter surface can be obtained.