Reasons for extrusion mold large caps are generally caused by uneven die surface leading to unclean shear and gradual adhesion of aluminum to the outside. The following are several reasons for extrusion mold that may lead to extrusion large caps:
1. The end face of the extrusion die is uneven or has defects, so that the locking surface has gaps and aluminum channeling. The defect of the mold should be repaired in time, and the mold surface must be milled.
2. If the outer circle of the feed chamber is too large (the die distance is too short), the locking area of the die barrel will be small ------. The distance between the outer circle of the feed chamber and the cylinder wall is normal, and the limit of 10mm shall not be less than 5mm. When using such extrusion die production, the center of the upper and lower left and right must be aligned to prevent the deviation of die distance.
3. There is no milling water outlet in the extrusion mold, the closed surface of the mold is too large, the compression value per unit area is small - less than the outlet pressure, and the shear of the mold surface after aluminum sticking to aluminum is not clean, resulting in uneven mold surface. This kind of big hat is difficult to make clean. Note that the cylinder surface should be properly oiled and no longer stick to aluminum. The aluminum on the mold surface can be cut off many times. The indentation of the cylinder on the mold surface can be coated with oil, so that the aluminum on the mold surface will not stick to the mold and the mold will be cut out. Make it a success if you have a little flying edge now and then.
4. The size of the water outlet of the extrusion mold is smaller than the size of the barrel working face, and the closed area of the barrel die is small and it is easy to damage the barrel working face. Note that when the small machine mold is refitted to the large machine, the diameter of the mold water mouth should be the same as the diameter of the large barrel working face.
5. The thickness of the extrusion die is not enough, and the extrusion cylinder is stressed on the die sleeve. The thickness of die and die sleeve should conform to the principle of first 3 and then 1, that is, the guide surface of the die should protrude the die sleeve by 1mm. ------ Die sleeves are never directly subjected to extrusion pressure, otherwise, die sleeves are vulnerable to damage and deformation.
6. The clearance between the mold sleeve and the mold is too large, and the aluminum sticking in the clearance leads to unclean shear and uneven mold surface. This kind of situation is usually seen in the mold modified from the small machine.
7. The extrusion ratio is too high, the exit resistance is greater than the extrusion pressure, the locking surface is uneven, and the aluminum flows out from the locking surface. Most of these cases will occur stuffy car phenomenon, can be properly increased rod temperature mold temperature, cylinder temperature. If necessary, the mould sleeve or even gasket can be heated before machine production, at the same time, can be appropriate to reduce the length of the rod, reduce the size. The aluminum bar can be pressed for a short time instead of blindly increasing the bar temperature. The high bar temperature is easy to come out of the cap, which also limits the improvement of the speed.
