EP2190255A1 - Electrical tubular heating cartridge - Google Patents

Abstract

The flexible electric tube heating cartridge (6, 36) serves to form a cartridge spiral (12, 20) with different pitches and / or for forming a meandering tubular heating coil (35) on the circumference of a cylindrical tubular body (2) to be heated. In this case, the tubular heating cartridge (6, 36) with at least one wound on a flexible winding core (16) of insulating Heizdrahtwendel (15) provided in a metal shell (11, 22) by a metal shell filling, compacted insulating material (17) is enclosed , The Heizdrahtwendel (15) is wound to produce different Heizleistungsdichten with helical sections of different pitches or winding pitches (d1, d2, d3, etc.) on a thread, yarn or cord-like winding core (16) with less than 1 mm in diameter and with this Winding core (16) in the metal shell (22) in a with the metal shell (2) compressed insulating material (17) of metal oxide, in particular MgO or the like. Embedded, such that the helical sections of Heizdrahtwendel (15) with the lowest slopes and winding spacings (d3 ) or with the highest heat output form the sections (E1, E2) of the cartridge spiral (12) or the cartridge coil (35) with the highest power densities.

Description

The invention relates to a flexible electric Rohrheizpatrone to form a cartridge spiral with different pitches and / or for forming a meandering cartridge snake on the circumference of a heated cylindrical tubular body and / or for insertion into contiguous, with different gradients helical grooves extending a metal, tubular hollow body a Rohrwendelpatrone, in particular for metal plastic injection nozzles of injection molding systems, wherein the Rohrheizpatrone is provided with at least one wound on a flexible winding core of insulating Heizdrahtwendel which is enclosed in a metal shell of a metal shell filling, compacted insulating material.

• Rohrheizpatrone(n);
• Heizdrahtwendel; das ist der zu einer Wendel geformte Heizdraht der Rohrheizpatrone;
• Wendelstrang; darunter versteht man einen sich vom einen Ende zum anderen Ende des Metallmantels einer Rohrheizpatrone erstreckender Anschnitt der Heizdrahtwendel;
• Rohrwendelpatrone(n); darunter ist ein Heizelement zu verstehen, das aus einem Rohrkörper besteht, der mit einer mäanderförmig und/oder wendelförmig verlaufenden Rohrwendelpatrone versehen ist;
• Patronenwendel; darunter ist die zu einer Wendel geformte Rohrheizpatrone zu verstehen;
• Patronenschlange; darunter ist eine zu einem mäanderförmigen Verlauf geformte Rohrheizpatrone zu verstehen.

In the following description and in the claims, the following terms are used:

• Tubular heating cartridge (s);
• heating coil; that is the filament-shaped heating wire of the tubular heating cartridge;
• Spiral strand; this is understood to mean a section of the heating wire coil extending from one end to the other end of the metal shell of a tubular heating cartridge;
• Tubular cartridge heater (s); this is understood to mean a heating element which consists of a tubular body which is provided with a meander-shaped and / or helically extending tube spiral cartridge;
• Wendel cartridges; this is to be understood as meaning the tube heating cartridge formed into a helix;
• Cartridges snake; underneath is meant a tubular heating cartridge shaped into a meandering course.

Pipe radiators of the generic type are known. It is understood in the industry both cylindrical and oval and flattened heating elements with a slightly flexible metal sheath, preferably copper, a copper alloy, nickel, steel or stainless steel, in which at least one Heizdrahtwendel is housed with the front side emerging from the metal sheath electrical connections. In this case, this consisting of a spiral strand or more helical strands Heizdrahtwendel against the metal sheath is electrically isolated in an originally fine-grained and compacted after filling a homogeneous heat conductor Isolierstoffpackung. In general, the metal shells of such Rohrheizpatronen to be light and bendable with a small bending radius, a diameter or a thickness of less than 5 mm. Their usually coreless filament helices can at For high performance design usually have a thickness of 0.2 mm to 0.6 mm. Their pitches are constant over the entire length, which means they have the same heating power at each point. In this case, the slope or the Windungsabstände the Heizdrahtwendel to achieve the highest possible heat density, kept as small as possible.

In order to use such a tube heating cartridge, a so-called tube spiral cartridge (also called "spiral tube cartridge", see: Peter Unger "Hot Runner Technology", ISBN 3-446-22585-4, www.hanser.de, Carl Hanser Verlag Münch en) to be able to produce with axially different Heizleistungsabschnitten, the Rohrheizpatrone is arranged with different gradients or Windungsabständen on serving as a winding support tube body close fitting on the circumference or laid in correspondingly extending grooves. In this case, the grooves may be arranged on the circumference or in the inner surface of the tubular body. The tubular body itself can be closed over its entire circumference. But there are also known tubular body, which are provided with an axial separating slot in order to obtain a certain radial spring elasticity.

Out DE 29 07 870 an electric tubular heater is known, which has the properties of a tubular heater of the generic type and over its entire length has the same cross-sections with a tube diameter of about 3 mm. This tubular heater is provided with a running in two parallel helical strands Heizdrahtwendel electrically isolated in a metal jacket is arranged. The metal shell is closed at one end by a tight metal disc. At the ends of Heizdrahtwendel connecting conductors are fixed, which protrude from the metal plate opposite end of the metal shell end face. The Heizdrahtwendel is wound over the entire length with the same pitch or with the same Windungsabständen on a over its entire length extending winding core of insulating material, namely on a glass fiber core. In the metal shell is a cylindrical ceramic body which almost cross-sectionally fills the cavity of the metal shell and which is held by an insulating granule filling of the closing metal disc at a certain distance. This ceramic body terminates flush with the metal disc opposite end of the metal shell. The Heizdrahtwendel is housed with one spiral strand in two axially parallel channels of the ceramic body. The two equally long spiral strands of Heizdrahtwendel are much shorter than the ceramic body and its channels, so that the connections between the ends of the Heizdrahtwendel and the connections are within the channels. In this state, this tube heater is compacted by radial compression under a diameter reduction by a quarter high. The tubular heating cartridge produced in this way is flexible and about 150 cm long. It can be wound into a cartridge coil having a coil diameter of about 25 mm or less and used for heating hot runner tools, injection molding machines or the like.

It is known that so-called tube spiral cartridges, which are used for heating Angießdüsen whose heat demand over the length of the Angießdüsen sections can be very different. It follows that also the heat supply and thus the heat output must be different in sections.

In the application of such Rohrheizpatronen with Heizdrahtwendeln continuously the same slope is the adjustment of the Heizleistungsprofils to a predetermined temperature profile, for. along a Angießdüse an injection molding system insofar limited as the spatial compression of the turns of the cartridge helix is limited by the diameter thereof or by the width of the grooves in which the Rohrheizpatronen are guided. If the achievable heating must be increased by higher heating capacity in closely spaced turns of the cartridge spiral, also inevitably increases the heating power in the sections of the Angießdüse in which a higher heating is not desirable. This means that a smoothing of the temperature profile or an adaptation of the tube spiral cartridge to the heat demand profile is not possible to the desired extent.

The invention has for its object to provide a Rohrheizpatrone of the type mentioned, with which it is possible over the axial length of a heated metal component, in particular a tubular body or other elongate machine element, such as a Angießdüse an injection molding system on a given Temperature profile to produce adjusted Heizleistungsprofil. In this case, a greatly increased heating capacity should be made possible, especially in the sections with higher heat demand, without increasing the heat output in the sections with minimal heat demand.

This object is achieved according to the invention in that the Heizdrahtwendel wound to produce different Heizleistungsdichten with helical sections of different pitches or Windungsabständen on a winding core with less than 1 mm in diameter and with this hub in the metal shell in a compacted with the metal jacket Isolierstoffpackung of metal oxide, in particular magnesium oxide is embedded, that form the filament portions of the Heizdrahtwendel with the lowest pitches or winding intervals, the portions of the cartridge coil or the cartridge coil with the highest heat power densities.

The particular advantage of this solution is that the performance profile of the cartridge spiral the temperature profile and the corresponding analog heat demand profile of the machine component to be heated much better and can be more accurately adjusted over larger temperature ranges. In the sections of the highest power cartridge coil, the heater wire coil sections may be arranged with the lowest pitches, while in the lower and lowest power cartridge coil sections, higher pitch and largest heater wire coil sections, respectively Slope or can be arranged with the largest winding distances or be.

It is also possible to concentrate the highest heat output on one or more very short lengths of the machine component, for example an injection molding or pouring nozzle.

The differently wound sections of Heizdrahtwendel must be generated during the winding process in the respective predetermined lengths.

So that it is even possible to produce a Heizdrahtwendel with different slopes or winding distances, it requires the use of a remaining in the Heizdrahtwendel winding core. This winding core is also required so that the pitches or winding pitches produced during winding of the heating wire coil during further processing, especially during insertion of the heating wire coil in the tubular metal shell and during subsequent filling of the insulating granules in the metal shell, do not change.

With the embodiment of the invention according to claim 2, its advantages can be optimally utilized.

Although in principle it is also possible to provide for the winding core other insulating materials, the embodiment taken according to claim 3 has advantages, as such a ceramic thread both as a winding core during winding of the heating wire coil as well as during bending and insertion of the heating wire coil in a metal casing pipe is particularly proves favorable. The ceramic thread used here is made up of several very thin, spun or twisted fibers which give it high tensile strength and flexibility.

Due to the configuration of the invention according to claim 4, a manufacturing technology significant advantage can be achieved compared to the only provided with a helical strand tubular heating cartridges. This is that the electrical connections of the ends of the Heizdrahtwendel can be led out of the same end of the metal casing pipe. This feature opens up the possibility of installing the tubular heating cartridge as a single-pass tubular heating element spiral in or on a tubular body and thereby to have the two connections in the same place. The electrical connections can consist of wires, strands, metal bars, plug-in pins or the like. With tubular heaters, which have only one strand of helix, the two led out at the two ends of the metal casing pipe connections can only be brought together at a common location when the Rohrheizpatrone bifilar, ie with two parallel strands of the same Rohrheizpatrone is wound. For this purpose, it is necessary to form a two-strand tubular heating cartridge from the originally single-stranded tubular heating cartridge before winding in which it is bent in a hairpin shape over half its length. The hairpin-shaped bent end of the double strand forms the beginning of the heating cartridge spiral. This cumbersome and costly operation can be avoided by the embodiment of the invention according to claim 4.

Further advantageous embodiments of the invention are specified in the subclaims 5 to 8.

Fig. 1

in 3D Darstellung eine Rohrwendelpatrone;

Fig. 2

stark vergrößert in 3D Darstellung, eine aus ei- ner Heizrohrpatrone mit flachem Querschnitt ge- wickelte, kernlose Heizrohrwendel;

Fig. 2a

in vergrößerter Schnittdarstellung einen Rohr- wendelabschnitt IIa aus Fig. 2;

Fig. 2b

in vergrößerter Schnittdarstellung einen Rohr- wendelabschnitt IIb aus Fig. 2;

Fig. 3

stark vergrößert in 3D Darstellung einen Heiz- drahtwendelabschnitt mit hälftig geschnittenem Metallmantelrohr und Isolierstoffpackung;

Fig. 4

stark vergrößert in 3D Darstellung den geschlos- senen Endabschnitt einer Rohrheizpatrone mit zwei Heizdrahtwicklungssträngen;

Fig. 4a

den gleichen Heizpatronenabschnitt wie Fig. 4, jedoch mit in Isolierstoffröhrchen geführten Heizdrahtwicklungssträngen;

Fi. 4b

stark vergrößert ein Isolierstoffröhrchen in 3D Darstellung;

Fig. 5

in schematisierter 3D Darstellung eine bifilar in mäanderförmigen Schlangenlinien gewickelte und zylindrisch gebogene Patronenschlange;

Fig. 6

in vergrößerter Schnittdarstellung einen Wen- delabschnitt VI aus Fig. 5;

Fig. 7

eine in zwei Gruppen mäanderförmig verlaufende Patronenwendel in einer Ebene liegend.

The invention will be explained in more detail below with reference to the drawings. From the drawings shows:

Fig. 1

in 3D representation a pipe spiral cartridge;

Fig. 2

greatly enlarged in 3D, a coreless heating tube coil wound from a heating tube cartridge with a flat cross-section;

Fig. 2a

in enlarged sectional view of a pipe Wendelabschnitt IIa Fig. 2 ;

Fig. 2b

in enlarged sectional view of a pipe Wendend section IIb Fig. 2 ;

Fig. 3

greatly enlarged in 3D representation a heating wire coil section with half-cut metal casing pipe and insulating material packing;

Fig. 4

greatly enlarged in 3D representation of the closed end section of a tubular heating cartridge with two Heizdrahtwicklungssträngen;

Fig. 4a

the same cartridge section as Fig. 4 , but with Heizdrahtwicklungssträngen guided in insulating tube;

Fi. 4b

greatly enlarged an insulating tube in 3D representation;

Fig. 5

in a schematic 3D representation of a bifilar wound in meandering serpentine lines and cylindrically curved cartridge snake;

Fig. 6

in an enlarged sectional view of a turning delimited VI Fig. 5 ;

Fig. 7

a meandering in two groups cartridge spiral lying in a plane.

The tubular body 2 of in Fig. 1 Pipe spiral cartridge 1 shown is provided on its circumference with a groove 3 extending groove. This groove 3 is formed doppelzügig; ie it consists of two mutually parallel payloads 3/1 and 3/2, which are connected to each other in their initial area by a U-bend 4 and terminate at a remote location 5 of the tube circumference. In the end regions E1 and E2 of the tubular body 2, this groove 3 has a very small pitch with very small pitches w1 . In the much larger middle section M , the pitch is so great that this middle section is bridged by only one turn.

In this groove 3, a Rohrheizpatrone 6 is inserted or pressed in the form of a cartridge coil 12, the electrical connections 7 and 8 are directed at the end of the groove 3 radially outward. In the middle section M and in the end region E2 , a second groove 9, in which a thermocouple 10 is guided, runs parallel to the two-pass groove 3.

The tubular body 2 has an outer diameter of about 20 mm to 30 mm. The cross-section of the groove 3 is chosen so that a Rohrheizpatrone 6 can be taken with a thickness of about 2 mm to 5 mm fitting in it.

Like from the Fig. 3 to 4a can be seen, the Rohrheizpatrone 6 in a metal shell 11, arranged concentrically, a Heizdrahtwendel 15 which is wound on a thread, yarn or cord-like winding core 16 made of insulating material. The heating wire coil 15 may have a wire thickness of about 0.1 mm to about 0.8 mm in such applications.

Preferably, this about 0.3 mm to 0.7 mm thick winding core 16 made of a ceramic thread or a ceramic cord, which has not only the required tensile strength, but also a sufficient bending elasticity. This winding core 16 is used to provide the Heizdrahtwendel 15 during the winding process, ie when generating the Heizdrahtwendel 15 with sections of different slopes or winding pitches d1, d2 and d3, ie, with different Windungsdichten. In this case d3 corresponds to a minimum, d2 to a middle and d1 a larger winding distance.

With these different winding densities, it is possible along the tubular heating cartridge 6 or along the cartridge spiral 12 to achieve sections with different heat power densities with the same power consumption, which behave at least approximately proportionally to the respective winding densities and reciprocally to the winding spacings d1, d2, d3 .

As is well known, the heating wire coil 15 is embedded in a highly compressed insulating material 17, which forms a good heat conductor to the metal shell 11 and at the same time a good electrical insulation against the metal shell 11.

Such a tube heating cartridge 6 or cartridge spiral 12 originally produced as a long simple strand is inserted into the double-groove 3 of the green spiral cartridge 1. For this purpose, it is necessary in advance, the tube heater 6 hairpin in a half of their length or U-shaped bend to obtain a zweizügige shape that can be inserted into the also two-way groove 3 and optionally pressed so that they the cartridge coil 12 forms.

In order to let in the two end portions E1 and E2 of the tubular body 2 to take effect much higher heating than in the middle section M , not only the winding distances w1 and w1 of the cartridge coil 12 are substantially smaller than in the middle section M , but it is in the in these end regions E1 and E2 lying portions of the Rohrheizpatrone 6 and the cartridge coil 12, the Heizdrahtwendel 15 with a much smaller pitch or with smaller pitches of, for example, d3, ie provided with a substantially higher winding density than in the middle section M. Thus, the Heizleistungsunterschiede between the individual lengths of the tubular body 2 can not only be made larger but also variable.

Fig. 2 shows in a schematically simplified 3D representation of a cylindrically wound, coreless cartridge helix 20, the tubular heating cartridge 21 has a flattened cross-section. As the 4 and 4a show, in the metal shell 22 of this tube heater 21 a Heizdrahtwendel 15 laid in two winding strands 23 and 24, which is embedded as usual in a compacted insulating material 17. Again, the heating wire coil 15 with different Windungsabständen d1 and d2 wound on a winding core 16, which, however, need not be the same size as in Fig. 3 ,

In the Fig. 2a and 2b are shown in an enlarged sectional view, the two coil sections IIa and IIb schematically simplified. While in the coil section IIa, the two winding strands 23 and 24 each have a high winding density and a small winding spacing, the same winding strands 23, 24 in the region of the coil portion IIb with a smaller winding density, ie provided with a larger winding spacing. How out Fig. 2 can be seen, the helical section IIa has a smaller pitch than the helical section IIb. Depending on requirements, the remaining coil sections of the cartridge spiral 20 may have different winding densities, with which different heating power densities or heating powers along the cartridge tube coil 20 can be generated.

In such a tubular heating element 21, the winding ends of the heating wire coil 15 provided with terminals 28, 29 are located at the same end 26 of the metal shell 22 closed at the other end 27. The cartridge spiral 20 can therefore be wound in a catchy manner.

In the execution according to Fig. 4 is at the closed end 27 of the metal shell 22 U-shaped bent Heizdrahtwendel 15 fixed by guide elements, not shown, within the metal shell in parallel position of the two winding strands. In the embodiment of the Fig. 4a however, the two winding strands 23, 24 respectively separately in two parallel bores 31 and 32 of several, seamlessly lined up and together over the entire length of the metal shell 22 extending ceramic tube 30 and thus electrically insulated from each other and against the metal shell 22. In this case, the Heizdrahtwendel 15 in the holes 31, 32 before filling the Isolierstoffgranulats so much radial clearance that the Heizdrahtwendel 15 within these holes 31, 32 can be completely enveloped with the Isolierstoffgranulat and results in compacting an at least almost homogeneous insulating 17.

Depending on the conditions at the place of use and the Heizleistungsrefordernissen arising from a given temperature profile, the winding distances d1, d2, d3 , etc. can be selected and executed on the two winding strands 23, 24 different.

As further exemplary embodiments show, tubular heating cartridges, which have heating wire coils 15 with sectionally different winding densities or winding distances d1, d2, d3, etc., can also be used to produce meandering cartridge coils.

In Fig. 5 is a schematic 3D representation of a coreless bifilar wound in meandering serpentine lines and shaped into a cylindrically curved cartridge coil 35 tubular heating cartridge 36, which is suitable and intended to be placed on a cylindrical machine part to heat this. Bifilar means that the tubular heating cartridge 36 two equal length, parallel strands 37, 38 forms, which are integrally connected by a preferably provided with a minimum bending radius arc portion 39. This arc portion 39 also forms the beginning of the cartridge snake 35, wherein the end 40 of the two adjacent ends 41 and 42 of the tubular heater 36 is formed.

In Fig. 7 This cartridge snake 35 is lying in a plane, quasi in an extended position shown.

This cartridge coil 35 consists of two groups of turns 43 and 44, which are interconnected by a straight cartridge portion 45. It follows that the machine part on which this cartridge snake 35 is placed, in each case more heated in the region of the two winding groups than in the middle section.

Like the enlarged winding section VI of Fig. 6 shows the Heizdrahtwendel 15 in the region of the lower portions A of the straight coil sections 47, 48, 49 and 50 and in the areas of the sheets B and C respectively with a higher winding density, that is provided with smaller pitches d3 than in the remaining sections and in the upper arc regions 39 and 39 ', where the winding pitches are given for example with d2 and d1 . This is only to show that the winding density over the entire length of the tubular heating cartridge 36 sections corresponding to the respective requirements can be adjusted by the appropriate choice of Windungsabstände d1, d2, d3 , etc., or winding density. So can in the other straight coil sections and in the arc sections of the cartridge coil other under different winding densities, ie Windungsabstände be provided to correspond to a particular temperature profile or Heizleistungsprofil along a machine component to be heated.

Whether the tubular heating cartridge 6 is used in the form of a cartridge coil 12 or 20 or in the form of a cartridge coil 35 or in the form of another distribution system is indifferent per se. The achievable by the scheduled sections different winding densities or winding spacings of the heating wire coil 15 advantages are independent of the shape of the tubular heating cartridge.

Claims (8)

Flexible electric tube heating cartridge (6, 36) for forming a cartridge spiral (12, 20) with different pitches and / or for forming a meandering tubular heating coil (35) on the circumference of a cylindrical tubular body (2) to be heated and / or for insertion into coherent , with different pitches helically extending grooves (3) of a metal, tubular hollow body of a Rohrwendelpatrone (1), in particular for metal plastic injection nozzles of injection molding systems, the Rohrheizpatrone (6, 36) with at least one wound on a flexible winding core (16) of insulating Heizdrahtwendel (15) is provided, which is enclosed in a metal shell (11, 22) by a metal jacket filling, compressed insulating material (17),
characterized,
that the Heizdrahtwendel (15) wound to produce different Heizleistungsdichten with helical sections of different pitches or pitches (d1, d2, d3, etc.) on a thread, yarn or cord-like winding core (16) with less than 1 mm in diameter and with this winding core (16) in the metal shell (22) in one embedded with the metal shell (2) insulating material packing (17) of metal oxide, in particular Mg0 or the like., Is embedded such that the helical sections of Heizdrahtwendel (15) with the lowest slopes and winding distances (d3) or with the highest heat output sections ( E1, E2) of the cartridge spiral (12) and the cartridge coil (35) form the highest power densities. Electric tubular heating cartridge for insertion into contiguous, with the same and / or different gradients helical circumferential grooves (3) of the metal tubular body (2) a Rohrwendelpatrone (1) according to claim 1, characterized in that the slopes and Windungsabstände the Heizdrahtwendel (15) in the End portions (E1, E2) of the tubular body (2) are substantially smaller than in the central portion (M) of the tubular body (2). Electric tubular heating cartridge according to claim 1 or 2, characterized in that the winding core (16) consists of a thickness of 0.1 to 0.7 mm having ceramic thread or a ceramic cord formed of ceramic fibers. Electric tubular heating cartridge according to claim 1 or 2, characterized in that the heating wire coil (25) within the metal shell (22) in two parallel, electrically mutually insulated helical strands (23, 24) extends. Electric tubular heating cartridge according to claim 4, characterized in that the spiral sections with the different pitches (d1, d2, d3) of the one strand (23) arranged differently and / or are formed as that of the other coil strand (24). Electric tubular heating cartridge according to claim 4 or 5, characterized in that at least one of the two spiral strands (23, 24) is guided by insulating tubes, in particular ceramic tubes (30). Electric tubular heating cartridge according to claim 4 or 5, characterized in that the metal shell (22) has a flattened cross-section. Electric tubular heating cartridge according to one of claims 1 to 7, characterized in that the cartridge spiral (20) is formed as a coreless helix and with a radial tension generating fit on the cylindrical circumference of a tubular body to be heated, in particular a Angießdüse an injection molding system, can be placed.

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