Features of screw dispensing die suitable for extrusion of wide expanded foam sheets
DATE：2019/10/22 9:05:27 / READ： / SOURCE：This station
Features of screw dispensing die suitable for extrusion of wide expanded foam sheets
At present, the die which can continuously produce low-foamed sheets has a problem of uneven flow velocity in the width direction when producing wide-width foamed sheets. In response to this problem, a screw dispensing die suitable for extruding a wide expanded foam sheet has emerged. This type of die has five characteristics.
(1) Suitable for low temperature extrusion
Since the die is forced to distribute the flow in the width direction by the dispensing screw, it is not necessary to increase the die temperature to reduce the flow resistance as in the T-die, so that it can be extruded at a lower temperature.
(2) Foamed layer with closed cells
The foam layer is relatively uniform in the longitudinal and lateral directions, and has dense independent bubbles, and the adhesion between the skin layer and the core layer (foam layer) is also large.
(3) Wide range of resin applications
The screw head can be used to form a variety of resins, and the fluidity is very poor, and good molded products such as fly ash and PP can be obtained. The foamed sheet can also be extruded using a screw head. Soft PVC (P2000 ~ 3000) with a high degree of polymerization can also extrude sheets. Even the soft low-foamed sheet (with cloth base) produced by rolling can be extruded into pieces after being pulverized.
(4) Free thickness adjustment
The foamable sheet thickness can be molded from the same device to a range of 4-15 mm. And the plate thickness and the core layer thickness ratio can be freely changed.
(5) Good gloss and smoothness
Since the screw head gives the sheet a driving force, even if the resistance at the skin is large, the sheet can be pushed to move under a higher surface pressure. This results in greater friction between the surface of the sheet and the wall of the forming mold, resulting in a smooth surface with a certain degree of gloss (related to the surface roughness of the mold wall). The specific screw head structure is similar to that of the non-foamed plate screw head.
At present, the die which can continuously produce low-foamed sheets has a problem of uneven flow velocity in the width direction when producing wide-width foamed sheets. In response to this problem, a screw dispensing die suitable for extruding a wide expanded foam sheet has emerged. This type of die has five characteristics.
(1) Suitable for low temperature extrusion
Since the die is forced to distribute the flow in the width direction by the dispensing screw, it is not necessary to increase the die temperature to reduce the flow resistance as in the T-die, so that it can be extruded at a lower temperature.
(2) Foamed layer with closed cells
The foam layer is relatively uniform in the longitudinal and lateral directions, and has dense independent bubbles, and the adhesion between the skin layer and the core layer (foam layer) is also large.
(3) Wide range of resin applications
The screw head can be used to form a variety of resins, and the fluidity is very poor, and good molded products such as fly ash and PP can be obtained. The foamed sheet can also be extruded using a screw head. Soft PVC (P2000 ~ 3000) with a high degree of polymerization can also extrude sheets. Even the soft low-foamed sheet (with cloth base) produced by rolling can be extruded into pieces after being pulverized.
(4) Free thickness adjustment
The foamable sheet thickness can be molded from the same device to a range of 4-15 mm. And the plate thickness and the core layer thickness ratio can be freely changed.
(5) Good gloss and smoothness
Since the screw head gives the sheet a driving force, even if the resistance at the skin is large, the sheet can be pushed to move under a higher surface pressure. This results in greater friction between the surface of the sheet and the wall of the forming mold, resulting in a smooth surface with a certain degree of gloss (related to the surface roughness of the mold wall). The specific screw head structure is similar to that of the non-foamed plate screw head.
Author：admin