CS160692A3 - Process and apparatus for producing extruded hollow sections ofthermoplastic material - Google Patents

Abstract

2.1 The invention is based on the object of increasing the extrusion rate of the hollow profile emerging from the die by 25 to 30 percent. 2.2 To achieve this object the channel or the channels (9, 9a) provided in the die (1) for the passage of air between the inner chamber of the extruded hollow profile and the atmosphere during the extrusion of the hollow profile are used in order to pass a gaseous coolant in the extrusion direction or against the extrusion direction through the inner chamber of the extruded hollow profile. 2.3 The method and the device are used for the production of window or door profiles as well as for roller-blind profiles or the like. <IMAGE>

Description

1

A method and apparatus for producing extruded cavity profiles from a thermoplastic material

Technical field

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a process for the production of extruded cavity profiles of thermoplastic material, in particular to the production of window or door profiles as well as coiling profiles, in which the plastic melt is fed through a nozzle with at least one core in which the core is connected to the body The nozzle and outlet of the nozzle are self-supporting and the core is provided with a channel for supplying air between the inner chambers, or the chamber of the extruded cavity profile, and an atmosphere that emerges out of its nozzle face at the outlet of the nozzle.

The invention also relates to an apparatus for carrying out the method.

BACKGROUND OF THE INVENTION In an extruder, a thermoplastic material is plasticized by the energy supply and is discharged through a nozzle. The extruded material emerging from the nozzle is in a highly plastic state and runs through. The calibration of the cavity profiles is limited exclusively by the outer contour of the profiled strand. Depending on the extruded profile and the construction of the nozzle, a plurality of sequentially arranged calibrating units are formed, and cooling water conduits are formed inside the individual calibrating units or the associated or associated coolers.

The profile material lying inside is cooled from the outside by heat conduction through the heat conduction. The transport of the extruded cavity profile is effected by a caterpillar or chain outlet, which is arranged after the caliber or calibers, or in a cooler, in which the profiled strand cools and stabilizes in shape.

This is followed by a cutting unit by which the extruded profile is adjusted to the desired length, in particular the commercially available storage shelf.

The channel or channels formed in the nozzle core of the air embodiment between the inner cavity or the inner cavity-extruded cavity profile and the atmosphere have the following significance for the different extrusion process.

Extrusion of cavity profiles, in particular; when using a soft, elastic molded material, at its beginning it leads to the closure of the extruded strand by collapsing the profile walls. Gradual extrusion would result in: a vacuum inside the cavity which would further cause the cavity to collapse.

As long as the profile on the front end side is still closed, an atomic pressure is provided by the ventilation system provided inside the nozzle to allow air to flow within the cavity or cavities of the hollow profile. As soon as the frontal strand of the front strand is opened by cutting, ventilation is provided by the open end of the profiled strand. In the case of hollow sections, for example in the case of hoses which are extruded continuously, pressure channels are formed in the core of the nozzle by means of ventilation channels within the profile strand. Also, in this extrusion process, pressure equalization is important, which prevents underpressure in the cavity of the extruded profile, which causes the profile to collapse, and is also detrimental or impossible for external vacuum calibration. The ventilation ducts in the nozzle core are used in the production of compressed air supply foils. The thin-walled hoses are then extruded and subsequently the gauges are not stretched, but instead replaced by pressurized air and brought to a definite dilatation. After the inflated hose has cooled, it is then wound as a raised foil.

The efficiency of the extrusion process depends on its speed. The important parameters in relation to the extrusion rate are the extruded power and the speed of the extruded strand, which is essentially dependent on the cooling of the extruded profile. In the method used up to now, cooling takes place on the outer periphery of the extruded strand. In doing so, the heat inside the extruded cavity profiles must be sufficiently drained through the heat conduction.

Cooling occurs directly or indirectly in a cooler provided with a water inlet.

SUMMARY OF THE INVENTION

The invention provides a basis for such a method or sort of apparatus of the aforementioned type in order to improve both the speed of extrusion and the economy.

This object is solved in accordance with the invention in that during the extrusion of the cavity profile, a gas cooling medium flows through the channel or channels in the direction or upstream of the extruzidutin profile.

In particular, air is used as the gaseous cooling medium, which is sucked from the inner cavity or internal cavities during the extrusion of the profile through the nozzle channel or channels, with ambient air flowing through the open-extrusion strand.

To intensify the cooling, the coolant can be fed through the guide means provided in the nozzle and the inner surfaces of the corrugated tube into the inner cavity or the internal cavities of the cavity-4-profile and directed to the inner surfaces of the hollow profile.

Also, turbulent flow of cooling media directed to the inner walls of the cavity profile during their extrusion may be advantageous.

In order not to deteriorate the temperature conditions in the nozzle with the gaseous cooling medium that is directed through the duct or channels, the ducts can be insulated with a layer of thermal insulation.

The channels may also be formed in the nozzle through tubes of heat-dissipating material. These tubes can also be brought out of the face of the nozzle on the outlet side of the nozzle, so that the cooling medium is taken out or transferred.

Further features of the invention are apparent from the subclaims.

BRIEF DESCRIPTION OF THE DRAWINGS Exemplary embodiments of the invention are further illustrated in the drawings and in the following. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 in a perspective view of a simplified longitudinal nozzle; FIG. 2 is a diagram of a method in which the cooling air flow and the extrusion direction of the cavity profile are opposed; Fig. 3 is a diagram of a method in which the cooling air flow and the extrusion direction of the cavity profile are identical; Fig. 4 shows nozzles for producing a multi-chamber profile for windows or doors in perspective representation and partial cut; FIG. 5 is a partial longitudinal sectional view of another embodiment of the nozzle. Examples of the Invention - 5 -

The nozzle 1 shown in FIG. 1 consists of a core 2 which is provided with a semi-bearing die 3 forming an outlet for an extruded cavity profile and is composed of three individual core 4, 6, which form a transverse contour with the die. extruded multiple chamber profile.

The plastic melt is passed through the nozzle 1 in the direction of arrow J. The extruded profile leaves the nozzle in the nozzle outlet section 8. Core 2 is tightly coupled to nozzle 1 near the feed side. Individual cores 4, 5, &amp; they are provided with a channel 9, which first extends through the core 2 in the longitudinal direction and can extend through the channel portions 9a branching at a right angle. The gaseous cooling medium, preferably the cooling air, is moved through these channels 9a and 9a of the channel either upstream or downstream of the cavity profile.

It has proven to be advantageous to conduct the cooling air direction for the extrusion direction of the cavity profile shown in FIG. 2. In this process the air is sucked off during the extrusion, channels 9 and 9a of the air 1 from the inner chamber or inner chambers of the cavity profile, where flows as a cooling air to an open extrusion strand in the inner cavity profile.

Due to the different openings of the inner chamber openings or the inner chambers and channels 9, 9a, the pressure in the inner chamber or inner chambers corresponds to substantially atmospheric pressure without any pressure differences which could reduce the quality of the product. The advantage in the described flow direction of the cooling air is that the cooling air flow to the nozzle is heated, which, in parallel with the external cooling, leads to an effective uniform reduction in the temperature of the extruded article. At the inlet of the cooling air, the air in the periphery of the nozzle 1 heats up so strongly that it does not interfere with the functional temperature of the nozzle 1, while small temperature differences can become ineffective with simple measures 1.

Fig. 2 shows the cooling air flow curve 10 and the external cooling curve 11.

The drawn line shows the temperature curve 12 of the extruded cavity profile. In the diagram of FIG. 3, using the same reference numerals as in FIG. 2, the flow of cooling air coincides with the extrusion direction of the cavity profile. While this method reduces the temperature of the extruded cavity profile immediately downstream of the nozzle 1, the heating of the cooling air by the following profile circuit is not further cooled down so effectively. In order to avoid strong cooling in the nozzle 1, the channels 9 and the channel part 9a must be surrounded by material which is difficult to conduct heat.

The method according to FIG. 2 has the additional advantage that, in particular in the profile circumference, there is a strong drop in temperature, which in turn brings about a strengthening of the material and thus permits a higher discharge rate.

FIG. 2 and 3 show only the tendencies of the temperature course.

FIG. 4 shows a die 13 of a second embodiment with an intermediate core 14 of a second embodiment, the channels of which are formed to guide a gaseous cooling medium or cooling air in the periphery of the nozzle as a tube. so that the cooling medium flowing through the tubes 1g does not affect the nozzle temperature or only marginally. In the periphery of the die 13, the plasticity of the cavity profiles 16-7 must be maintained. As can be seen from FIG. 4, the tubes 15 protrude on the nozzle outlet side from the core face 17 or the die face 18, which mates with the face 17. The orifices 19 of the tubes 15, which are made not only of a material which is difficult to conduct heat, but also of a high refractory material, are spaced from the core face 17 and the die face 18, so that the flow gas cooling fluid, ends at the suction device at a distance from the core face 17 and from the die face 18 or starts before the face 17, 18 by feeding the tubes 15 in the inner chamber of the extruded cavity profile 16, in both cases no current gaseous cooling fluid to the nozzle by cooling effects, since iso is located up to the core face 17 an airy pillow. In the exemplary embodiment of FIG. 5, a collar 24 adapted to the inner chamber 22 of the extruded cavity profile 23 of the third embodiment is attached to the outlet opening of the die 20 of the third embodiment, prior to which the guide plate 25 &quot;

In the exemplary embodiment shown, the bottom 28 of the sleeve 24 is provided with a through hole 27 by means of a flange 29 of a threaded sleeve 30 to a core 21 of a third embodiment which is screwed in a threaded bore 31 of the core 21 of the third embodiment.

In an exemplary embodiment, the flow gap between the guide 25 and the inner lining of the extruded cavity 23 of the third embodiment is of the same orbital length.

If the extruded cavity profile 23 is formed with more chambers, the intermediate walls of which have a different thickness of the profile wall, the dimensions of the gap between the guide plate 25 and the partition or outer wall are different. A wall of greater thickness 8, which must be cooled more intensely than the hollow partition, is provided with a smaller flow gap so that the flow velocity of the coolant gas increases in this gap and the cooling is intensified.

However, it is also possible to create a turbulent flow, whereby the cooling medium is joined at a high velocity of the non-cooled surface and a flow of turbulence is created in the inner chamber or in the inner cores or in the gap between the guide plate 25 or the guide plates 25 and the cooled inner wall. FIG. 5 shows that the cooling air flow through the guide plate 25 through the gap between the webs 26 into the inner space of the sleeve 24 and then flows through the threaded sleeve 30 and then passes through the channel 9 to the vacuum pump. Thus, in the nozzle of FIG. 5, an intensive cooling of the extruded tin profile 23 of the third embodiment occurs at a distance from the die 20 of the third embodiment, so that the coolant flow is heated and there are no disadvantageous effects on the nozzle temperature when flowing through the channel.

The intensive cooling of the walls of the cavity profile 23 of the third embodiment, as well as of its inner walls, provides reinforcement to these walls and also ensures that the profile removal rate can be increased.

Since the profiles are divided into lengths by a saw, it must also be avoided that, when the cooling air is flowing in the same direction as the cavity profile, it does not result in a short-term closure of the inner chamber or internal chambers. rotating cutting blade. Depending on the cooling air, there would be overpressure or underpressure in the inner chamber of the throat profile. - 9 -

This vacuum or overpressure in the inner chamber of the extruded hollow profile can be prevented by dividing the saw blade at the periphery, providing holes through the cooling medium.

There is also the possibility of providing a saw blade body set laterally with a protruding tungsten carbide cutting edge, so that there is a mezzanine cooling medium between the tungsten carbide and the blade body.

Another technical possibility is that it is fitted with a switching valve through which the cooling air is introduced into the vacuum pump. In the short-term closure of the front openings in the extruded hollow profile with the blade engaging the valve, the flow of cooling air in the inner chamber of the hollow profile is briefly interrupted and ambient air is sucked in. cooling air sucks in the inner chamber; profile.

Building profiles that are used to make windows, door blinds, or the like generally have an outer wall thickness that prevents the internal walls of the chamber from being thermally insulated by its material.

Outside by direct cooling, for example by water cooling, the result of the external calibration is affected. The dimensional stability of the inner walls of the chambers is only supported when the velocity of the extruded profile is chosen such that a sufficient heat dissipation chamber is maintained.

By introducing internal cooling, the inner walls of the chamber are reinforced and dimensionally dimensioned, which are usually thin as contours. With this dimensional fixation, but also with early stabilization and strength it can increase the rate of consumption and thus the cost-effectiveness of profile production. 10 -

By introducing internal gaseous medium cooling, an increase in the cavity profile extrusion rate of at least 25 to 30% is achievable.

Claims (1)

PATENT REQUIREMENTS 1) A method for producing extruded cavity profiles of thermoplastic material, in particular for producing window or door profiles as well as rolled profiles and the like, in which the plastic melt is fed through a nozzle provided with at least one core which is melting at the inlet side. The plastic is connected to the nozzle body and is self-supporting at the nozzle outlet and is provided with an air duct between the inner chamber or the inner chambers of the extruded cavity profile and the atmosphere which emerges from the nozzle face at the periphery of the nozzle. that during extrusion of the cavity profile (16, 23); flowing through the channel (9) of the nozzle (1), and the inner chamber or inner co-morals of the cavity profile (16, 23) in the direction of extrusion, or gaseous cooling medium opposite the extrusion direction of the cavity profile (16, 23). 2. A method according to claim 1, characterized in that, when the extruded strand is separated by a saw, a flow-through opening is discharged in the circumference or the flow of cooling medium is short-circuited for a short time. 3. Method according to claim 1, characterized in that during the extrusion of the cavity profile (16, 23), air is sucked out of the inner chamber or inner chambers of the cavity profile through the air channel (9) and ambient air is sucked on the open extrusion strand. 4. Method according to claims 1 to 3, characterized in that the gaseous heating medium is supplied by a guide means connected to the nozzle core (2,14,21) along the inner surface formed in the inner chamber or inner chambers. cavity profile (16,23). 5. A method according to claims 1 to 4, characterized in that the shifted moving gaseous cooling medium feeds a speed at which turbulent flow occurs. 6. A method according to claim 5, characterized in that during the extrusion of the cavity profile, a flow of turbulence is added to the inner chamber or inner chambers, which is indirectly or directly connected to the core (2,14,21) of the nozzle (1). 7) Apparatus for producing extruded cavity profiles of thermoplastic material, in particular for producing window or door profiles as well as rolled profiles and the like, with a nozzle through which a plastic melt is injected with at least one core which is connected to the nozzle body and is self-supporting at the nozzle outlet and is provided with an air duct between the inner chamber or the inner chambers of the extruded cavity profile and the atmosphere which emerges from its face at the periphery of the nozzle exit; wherein the channels (9) and their channel portions (9a) formed in the core (2,14,21) or individual cores (4,5,6) are provided with a layer of thermal insulation. 8) Device according to claim 7, characterized in that in the core (2,14,21); tubes (15) are formed of a material which is difficult to conduct heat. 9) Apparatus according to claim 8, characterized in that the tubes (15) on the front face of the nozzle (11) protrude from the face (17) of the core. Apparatus according to claim 7, characterized in that a sleeve (24) adapted to the inner chamber (22) of the extruded casting profile (23) is attached to the core (2,14,21) at the outlet side of the nozzle (1) before by which it is fixed on a wall (261 guide plate (25) which, together with the shell (24), delimits an intermittent gap in the web (26). the profile section divides the saw blade to a commercial length, characterized in that the saw blade body is circumscribed by openings for conducting the cooling medium. 12. Apparatus according to claim 7, characterized in that the body-blade sheet is provided with a hard-metal protruding cutting edge. Apparatus according to claim 7, characterized in that the channel (9) or its part (9a) or the nozzle tubes (15) of the nozzle (1) are connected to a switching valve.