RU2614868C1 - Extrusion head for polymer tubular film production - Google Patents

Abstract

FIELD: mechanical engineering.

SUBSTANCE: proposed device for readjustment of the extruder head for producing a tubular film of polymer on the desired size of the film does not require replacement of the mandrel with subsequent centering. The change in the shape of the gaps is achieved by varying the diameter of the surface of the mandrel, which forms the gap. For this purpose, the mandrel an annular cavity is formed by cylindrical surfaces coaxial with the mandrel surface, in which the liquid is supplied under the pressure. Under the influence of fluid pressure, the mandrel deforms and changes its diameter. The installation of the required diameter of the mandrel and hence the gap and the film thickness is carried out by adjusting the fluid pressure in the annular cavity.

EFFECT: accelerating changeover process the die to the required size of the film and the simplification of the structure.

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Description

The invention is intended for use in aircraft, engineering and in other areas of the national economy.

Known extrusion head for the manufacture of tubular products containing a forming sleeve, a mandrel with a channel for supplying compressed air, forming a forming gap with the forming sleeve (patent SU 1763227). Its disadvantage is the method of readjustment to the required film size, requiring replacement of the mandrel, which suggests the presence of a number of mandrels of various diameters. The process of readjustment involves disassembling the head, actually replacing the mandrel and its centering using four linear correctors with noni.

The purpose of the invention is to accelerate the process of readjustment to the required film size and simplify the design of the device.

This goal is achieved by the fact that in the extrusion head containing the forming sleeve, the mandrel with a channel for supplying compressed air, forming a forming gap with the forming sleeve, according to the claimed invention, an annular cavity is formed in the mandrel, formed by cylindrical surfaces coaxial with the surface of the mandrel, and having a tap for supplying fluid, the end surface of the mandrel and the annular cavity protruding beyond the end of the forming sleeve, and the diameter of the mandrel outside the forming sleeve is less than the diameter of the surface of the mandrel forming forming gap.

In the proposed device for readjustment to the required film size, disassembly of the head is not required, the mandrel is replaced and its centering is made, which makes it possible to save time and money.

Brief Description of the Drawings

The invention is illustrated by drawings in which the same or similar elements are provided with the same reference position.

FIG. 1 represents an extrusion die device.

FIG. 2 is a section along AA in FIG. one.

FIG. 3 is a shell formed by the outer cylindrical surface of the mandrel with a diameter D and the outer cylindrical surface of a cavity 4 with a diameter d _n , length l (FIG. 1).

FIG. 4 is a scan of a half shell shown in FIG. 3.

In FIG. 1 shows an extrusion head containing a forming sleeve 1 and a mandrel 2 with a channel 3 for supplying compressed air. An annular cavity 4 is formed in the mandrel 2, formed by cylindrical surfaces coaxial with the outer surface of the mandrel, and having a tap 5 for supplying fluid. The forming sleeve 1 and the mandrel 2 form a forming gap 6. To eliminate edge effects and ensure the consistency of the forming gap 6 along its entire length, the end surface 7 of the mandrel and the annular cavity 4 protrude beyond the end face 8 of the forming sleeve 1. To prevent the film from sticking to the surface of the mandrel outside the forming the gap 6, the diameter d of the mandrel 2 outside the forming sleeve 1 is less than the diameter D of the surface of the mandrel forming a gap.

Adjusting the size of the forming gap 6 is as follows. To, for example, reduce the gap 6 into the annular cavity 4 through the outlet 5, liquid is supplied under pressure, due to which the mandrel 2 is deformed, its diameter D increases and the gap 6 decreases. The increase in the gap 6 is achieved by reducing the fluid pressure in the annular cavity 4.

A calculation showing the feasibility and practicability of the invention.

Consider the section of the mandrel, which is a shell formed by the outer cylindrical surface of the mandrel with a diameter D and the outer cylindrical surface of the cavity 4 with a diameter d _n , length l (Fig. 1, Fig. 2 and Fig. 3). This section of the mandrel together with the forming sleeve form a forming gap.

The calculation is made for the following values of the determining parameters:

mandrel material - steel N18K7M5T σ _in = 1800 MPa E = 2⋅10 ¹¹ Pa shell inner radius R = d _n / 2 = 150 mm shell thickness δ = 3 mm margin of safety n = 3

Rated voltage

internal pressure force in the shell under consideration

where p is the fluid pressure in the cavity 4 (Fig. 1 and Fig. 2);

the cross-sectional area of the shell, perceiving the force of internal pressure,

tensile stresses in the shell

where from

Consider a scan of half the shell (Fig. 4).

Hooke Extension

An increase in the radius of the shell (a decrease in the size of the forming gap) taking into account (5)

This will require pressure (4)

In the considered example, by changing the pressure from 0 to 120 atmospheres, it is possible to adjust the forming gap, for example, from 0.5 mm to 0.05 mm.

Claims (1)

An extrusion head for manufacturing a polymeric tubular film containing a forming sleeve, a mandrel with a channel for supplying compressed air, forming a forming gap with the forming sleeve, characterized in that the mandrel has an annular cavity formed by cylindrical surfaces coaxial with the surface of the mandrel and having an outlet for fluid supply, while the end surface of the mandrel and the annular cavity protrude beyond the end of the forming sleeve, and the diameter of the mandrel outside the forming sleeve is less than the diameter of the surface of the mandrel forming uyuschy gap.

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