In the field of blister, the product requirements are different, and the forming method used is also different. Of course, the effect that appears is also different. In the blister process, there are many ways and expressions of vacuum forming, such as: vacuum forming of concave mold, vacuum forming of convex mold, vacuum forming of concave and convex molds, vacuum forming by blowing, auxiliary convex mold vacuum forming and Vacuum forming with gas buffer device and other methods.
The punch is vacuum-formed, and the tightened plastic sheet is heated and softened under a heater. After heating, the softened sheet is cooled when it contacts the punch, and loses its thinning ability. It continues to be heated and softened. The melted material continues to move downwards until it is completely in contact with the punch, and then vacuuming begins, and the edges and surroundings are formed by thinning.
The concave mold is vacuum-formed. Place the plastic sheet on top of the mold, fix it with the surroundings, and heat it to soften it; then pull it under the mold and vacuum to make the softened sheet tightly Glue it to the mold, and when it gradually cools, blow in air from the bottom of the mold to take out the plastic part.
The concave and convex molds are evacuated and formed successively. The plastic sheet is fastened on the concave mold and heated, and the heater is removed after softening; then the convex mold is blown into the compressed air upwards, and the concave mold is evacuated to bulge the plastic sheet, and finally convex The mold is inserted downward into the bulging plastic plate and a vacuum is drawn from it, while compressed air is passed into the concave mold, so that the plastic plate is attached to the outer surface of the convex mold to form.
The auxiliary punch is vacuum-formed. The plastic plate fixed to the concave mold is heated to a softened state, and then the heater is removed, and the plastic plate is pushed down with the auxiliary punch. The air in the concave mold is compressed, and the softened plastic plate is assisted by The thrust of the male mold and the enclosed air move and extend, and then the female mold is vacuum-formed.
Blowing and vacuum forming, heating the sheet, and then sending compressed air into the airtight box to blow up the sheet, and then raise the punch to form a closed state with the sheet, and finally draw from the vacuum hole on the punch Vacuum, using the outside atmospheric pressure to shape it. The forming method is to simultaneously thin all parts of the sheet in advance, so that the thickness of the plastic part in the final forming is roughly the same.
Compressed air forming method, after the sheet is heated, it is tensioned on the mold, and compressed air (6-8kg/cm2) is introduced from the upper platen to make the softened sheet closely adhere to the mold for cooling and shaping.