How to control the extrusion and blow molding process conditions of fishing buoys?

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How to control the extrusion and blow molding process conditions of fishing buoys?

(1)Extrusion temperature.

① cylinder temperature. According to pvc- U pipe material washing machine material Formula characteristics, cylinder temperature setting is higher, area I 150 ~ 160 ℃; Area II 170 ~ 175 ℃; 11I area 180-185 ℃; 1V area 185 ~ 190 ℃. If the temperature of the machine is set too low, the viscosity of the material melt will be higher, the extrusion of the tube blank will be unstable and easy to bend, resulting in difficulty in blow molding and uneven wall thickness of the formed buoy, which will affect the compression strength.

② head temperature. If the head temperature control is too high, the extruded tube blank will droop under the action of gravity, resulting in smaller diameter of the extruded tube blank and uneven longitudinal wall thickness, which will affect the buoyancy and pressure resistance of the buoy; In addition, a longitudinal weld line may be generated on the surface of the extruded tube blank, damaging the appearance of the buoy. If the head temperature is too low, the melt viscosity of the extruded tube blank increases, which is unfavorable to blow molding and makes the buoy surface rough. The head temperature is strictly controlled at 190-Within the range of 195 ℃.

(2)Screw speed. The selection of screw speed directly affects the output and quality of buoys. Appropriately increasing the screw speed can increase the extrusion speed of the molten tube blank, which is conducive to increasing the output and melting and plasticizing of materials, but the increase of the screw speed must be adapted to the blow molding speed. During normal production, a higher screw speed is selected, and its table value (Tachometer display value)For 100 ~ 120r/min.

(3)Blowing pressure. In order to inflate a certain length of molten tube blank into a buoy in the mold and make the outline of the mold cavity and the text pattern completely and clearly reveal, 0 must be controlled. 40 ~ 0. 45MPa blowing pressure. The blowing pressure is too small, the character pattern on the outer surface of the buoy is unclear, the vertical and horizontal grooves are not completely sunken, the operation is easy to slip off, and the appearance quality is not satisfactory; If the blowing pressure is too large, it may blow through the molten tube blank or make it difficult to demould the buoy.

(4)Blow molding time. In addition to the large blowing pressure, the buoy mold should be cooled by water when blowing the buoy. Therefore, the control of blowing time is directly related to the setting effect and production efficiency of the buoy. Appropriately increasing blow molding time is beneficial to buoy forming, but it will affect output and is not convenient to demould; If the blow molding time is shortened, the buoy can be produced more, but it is easy to deform after demoulding. Blow molding time is generally controlled at 4 ~ 58.