DE202008015329U1 - Electric tube heating cartridge - Google Patents

Abstract

The cartridge has a heated filament coil (15) for producing different heating power densities with coil sections of different grade and/or coil distances (d1-d3), where the coil sections are wound on a winding core (16) with diameter lesser than 1 millimeter. The coil is embedded with the winding core in a metal-shell (11) in an insulating material package (17). The package is made of metal oxide i.e. magnesium oxide, such that the sections with low grade and smaller coil distances and/or high heating power form sections of a cartridge coil and/or a cartridge chain with high power densities.

Description

The The invention relates to a flexible electric tubular heating cartridge for Formation of a cartridge spiral with different gradients and / or for Formation of a meandering cartridge snake on the circumference of a cylindrical tubular body to be heated and / or for insertion into coherent, with different Gradients helical grooves of a metal, tubular Hollow body of a pipe spiral cartridge, in particular for metal plastic injection nozzles of injection molding systems, wherein the tubular heating cartridge with at least one on a flexible Winding core of insulating material wound Heizdrahtwendel provided that is in a metal shell of a metal shell filling, enclosed compacted insulating material.

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.

Tubular Cartridge Heaters of the generic type are known. One understands including 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 Heating wire coil with front side emerging from the metal jacket electrical connections is housed. It is this consisting of a spiral strand or more helical strands Heizdrahtwendel electrically insulated against the metal sheath in a originally fine-grained and after filling to a homogeneous heat conductor compressed Isolierstoffpackung embedded. As a rule, the metal coats have such Tubular heating cartridges bend easily and with a small bending radius to be, a diameter or a thickness of less than 5 mm. Their usually coreless filament helices can usually a design for high performance Thickness of 0.2 mm to 0.6 mm. Their gradients or winding distances are constant over the entire length, which means that they have the same heat output at each point to have. Here is the slope or are the Windungsabstände the Heizdrahtwendel to the highest possible heating power density to reach, kept as small as possible.

To such a Rohrheizpatrone with a so-called. Rohrwendelpatrone (also "Wendelrohrpatrone", see: Peter Unger "hot runner technology", ISBN 3-446-22585-4, www.hanser.de, Carl Hanser Verlag Munich ) to be able to produce with axially different Heizleistungsabschnitten, the Rohrheizpatrone is arranged with different pitches 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 2907 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 which is arranged electrically isolated in a Metallman tel. 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 by radial compression under a diameter reduction a quarter highly compressed.

The thus produced tubular heating cartridge is flexible and about 150 cm long. It can lead to a cartridge spiral with a winding diameter of about 25 mm or less and for heating hot runner tools, Injection molding machines or the like. Be used.

It It is known that so-called tube coiled cartridges for heating Angle nozzles are used, their heat requirements over the length of the pouring nozzles in sections can be very different. It follows that also the Heat supply and thus the heat output in sections differently have to be.

at the application of such Rohrheizpatronen with Heizdrahtwendeln throughout the same slope is the adaptation of the heating power profile a predetermined temperature profile z. B. along a casting nozzle an injection molding system insofar limited as the spatial Compaction of the turns of the cartridge spiral by the diameter or by the width of the grooves in which the tubular heating cartridges performed are, is limited. If with closely spaced turns the cartridge spiral achievable by higher heating Heating power must be increased, also increases inevitably the heating power in the sections of the pouring nozzle, in which a higher heating is not desired is. That means a smoothing of the temperature profile or an adaptation of the pipe spiral cartridge to the heat demand profile not is possible to the desired extent.

Of the Invention is the object of a Rohrheizpatrone the above to create this type, with which it is possible over the axial length of a metal component to be heated, in particular a tubular body or another elongated Machine element, such. B. an Angießdüse an injection molding system, a given to a given temperature profile to produce adapted Heizleistungsprofil. It should in particular in the sections with higher heat demand one greatly increased heating capacity are made possible without the heating power in the sections with minimum heat requirement to increase.

Solved This object is achieved according to the invention in that the Heizdrahtwendel for generating different Heizleistungsdichten with helical sections of different pitches or pitches wound on a winding core with less than 1 mm in diameter and with this winding core so in the metal shell in one with the Metal jacket densified insulating metal oxide, in particular Magnesium oxide is embedded, that the helical sections of the heating wire coil with the lowest slopes or winding distances the sections the cartridge spiral or the cartridge snake with the highest Form heating power densities.

Of the particular advantage of this solution is that the Performance profile of the cartridge spiral the temperature profile or the analogue heat requirement profile of the machine component to be heated much better and over larger temperature ranges can be adjusted more precisely. In the sections of the cartridge spiral with the highest power requirement, the Heizdrahtwendelabschnitte arranged with the lowest slopes or winding distances while in the cartridge spiral sections with the lower or lowest power requirement heating wire coil sections with greater slope or with the largest th Slope or with the largest pitches can be arranged or become.

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

The need differently wound sections of the heating wire coil already during the winding process in the respective predetermined lengths be generated.

In order to it is even possible to use a heating wire coil with different gradients or winding distances manufacture, it requires the use of a in the Heizdrahtwendel remaining hub. This winding core is also required so that the slopes generated when winding the Heizdrahtwendel or Windungsabstände during further processing, especially during the insertion of the heating wire coil in the tubular metal shell and during subsequent filling of the Isolierstoffgranulats in the metal shell, do not change.

With The embodiment of the invention according to claim 2 can their advantages are used optimally.

Even though it is also possible in principle for the To provide winding core other insulating materials, has the claim 3 made execution insofar advantages, as such 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 turns out to be particularly favorable. This one for use upcoming ceramic thread consists of several very thin, spun or twisted fibers, giving it a high tensile strength and give flexibility.

By the embodiment of the invention according to claim 4 can be compared the only provided with a helical strand tubular heating cartridges a manufacturing technology considerable advantage can be achieved. This is that the electrical connections of the ends of the heating wire coil can be led out the same end of the metal casing pipe. This feature opens up the possibility of the tubular heating cartridge as a catchy tubular heater spiral in or on one To install tubular body while the two connections to have in the same place. The electrical connections can be made of wires, strands, metal rods, Plug od. Like. Exist.

With Tubular heaters, which have only one strand of wire can the two led out at the two ends of the metal casing pipe Connections only then merged at a common point when the tubular heating cartridge bifilar, d. H. with two parallel Strands of the same tubular heater, is wound. To It is necessary, from the original single-ranked, stretched tubular heating cartridge before winding a two-tier tubular heating cartridge to form in which they are at half their length hairpin is bent. The hairpin-shaped curved end of the double strand forms the beginning of the heating cartridge spiral. These cumbersome and costly way of working can be avoided by the embodiment of the invention according to claim 4 become.

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

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

1 in 3D representation a pipe spiral cartridge;

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

2a in enlarged sectional view a coiled tubing section IIa out 2 ;

2 B in enlarged sectional view a coiled tubing section IIb out 2 ;

3 greatly enlarged in 3D representation of a Heizdrahtwendelabschnitt with half-cut metal casing pipe and insulating material;

4 greatly enlarged in 3D representation of the closed end portion of a tubular heater with two Heizdrahtwicklungssträngen;

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

4b greatly enlarged an insulating tube in 3D representation;

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

6 in enlarged sectional view of a helix section VI 5 ;

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

The pipe body 2 the in 1 shown pipe spiral cartridge 1 is on its circumference with a helical groove 3 Mistake. This groove 3 is formed doppelzügig; ie it consists of two mutually parallel Nutzügen 3.1 and 3.2 , which in their starting area by a U-bow 4 connected to each other and at a remote location 5 end of the tube circumference. In the end areas E1 and E2 of the tubular body 2 has this groove 3 a very small pitch with very small pitches w1 on. 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 is a tubular heating cartridge 6 in the form of a cartridge spiral 12 inserted or pressed, their electrical connections 7 and 8th at the end of the groove 3 directed radially outward. In the middle section M and in the end region E2 runs parallel to the zweizügigen groove 3 a second groove 9 in which a thermocouple 10 is guided.

The pipe 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 tubular heating cartridge 6 with a thickness of about 2 mm to 5 mm can be accommodated therein.

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

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

With these different winding densities can be along the tube heater 6 or along the cartridge spiral 12 Achieve sections with different heating power densities at the same power consumption, which behave at least approximately proportional to the respective winding densities and reciprocally to the winding distances d1, d2, d3.

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

Such a tube heater originally made as a long simple strand 6 or cartridge spiral 12 is in the double groove 3 the Rohwendelpatrone 1 inserted. For this purpose, it is necessary in advance, the tubular heating cartridge 6 to bend hairpin-shaped or U-shaped halfway along its length in order to obtain a bifurcated shape that fits into the equally splined groove 3 can be inserted and possibly pressed, so that they the cartridge spiral 12 forms.

To in the two end regions E1 and E2 of the tubular body 2 To allow much higher heat outputs to be effective than in the middle section M, not only the winding distances w1 and w1 of the cartridge spiral are 12 is substantially smaller than in the middle section M, but it is in the lying in these end regions E1 and E2 sections of the tubular heating cartridge 6 or the cartridge spiral 12 the heating wire coil 15 with a much smaller pitch or with smaller pitches of, for example, d3, ie provided with a much higher winding density than in the middle section M. Thus, the heating power differences between the individual lengths of the tubular body 2 not only bigger but also more variable.

2 shows in a schematically simplified 3D representation of a cylindrically wound, coreless cartridge helix 20 , their tubular heating cartridge 21 has a flattened cross-section. As the 4 and 4a show is in the metal jacket 22 this tubular heating cartridge 21 a heating wire coil 15 in two winding strands 23 and 24 laid, as usual, in a compacted Isolierstoffpackung 17 is embedded. Again, the heating wire coil 15 with un ferent winding distances d1 and d2 on a winding core 16 wound up, which however need not be the same size as in 3 ,

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

In such a tubular heating cartridge 21 are those with connections 28 . 29 provided coil ends of the heating wire coil 15 at the same end 26 at the other end 27 closed metal mantle 22 , The cartridge spiral 20 Can therefore be wrapped catchy.

In the execution according to 4 is the one at the closed end 27 of the metal mantle 22 U-shaped bent heating wire coil 15 fixed by guide elements, not shown, within the metal shell in parallel position of the two winding strands. In the embodiment of the 4a however, the two winding strands are 23 . 24 depending Weil separately in two parallel holes 31 and 32 several, seamlessly lined up and together over the entire length of the metal shell 22 extending ceramic tube 30 led and so against each other and against the metal shell 22 electrically isolated. The heating wire coil has 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 when compacting an at least almost homogeneous Isolierstoffpackung 17 results.

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. on the two winding strands 23 . 24 be chosen differently and executed.

As further exemplary embodiments show, tubular heating cartridges, the heating wire spirals, can be used 15 have sections with different winding densities or winding distances d1, d2, d3, etc., also for producing meandering ver use running cartridge snakes.

In 5 is a schematic 3D representation of a coreless bifilar wound in meandering serpentine lines and a cylindrically curved cartridge snake 35 shaped tubular heating cartridge 36 shown, which is suitable and intended to be placed on a cylindrical machine part to heat it. Bifilar means that the tubular heating cartridge 36 two equally long, parallel strands 37 . 38 forms, by a preferably provided with a minimum bending radius arc section 39 are integrally connected to each other. This bow section 39 also forms the beginning of the cartridge snake 35 , whose end 40 from the two adjacent ends 41 and 42 the tubular heating cartridge 36 is formed.

In 7 is this cartridge snake 35 lying in one plane, quasi in an extended position.

This cartridge snake 35 consists of two groups of turns 43 and 44 passing through a straight cartridge section 45 connected to each other. 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 Windungsgruppen than in the middle section.

Like the enlarged winding section VI of 6 shows is the Heizdrahtwendel 15 in the region of the lower sections A of the straight snake sections 47 . 48 . 49 and 50 and in the areas of the bends B and C are each provided with a higher winding density, ie with smaller pitches d3 than in the remaining sections and in the upper arc areas 39 and 39 ' where the winding distances 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 can be adapted in sections to the respective requirements by the appropriate choice of the winding distances d1, d2, d3, etc. or winding density. So Kings nen different winding densities, ie Windungsabstände be provided to meet a certain temperature profile or Heizleistungsprofil along a machine component to be heated in the other straight snake sections and in the arc sections of the cartridge snake.

Whether the tubular heating cartridge 6 in the form of a cartridge spiral 12 respectively. 20 or in the form of a cartridge snake 35 or used in the form of another distribution system, is indifferent per se. The different winding densities or winding spacings of the heating wire coil due to the planned sections 15 achievable benefits are independent of the shape of the tubular heating cartridge.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 2907870 [0005]

Cited non-patent literature

• - "Wendelrohrpatrone" called, see: Peter Unger "hot runner technology", ISBN 3-446-22585-4, www.hanser.de, Carl Hanser Verlag Munich [0004]

Claims (8)

Flexible electric tube heating cartridge ( 6 . 36 ) for forming a cartridge spiral ( 12 . 20 ) with different slopes and / or to form a meandering tubular heating coil ( 35 ) on the circumference of a cylindrical tubular body to be heated ( 2 ) and / or for insertion into contiguous, with different pitches helically extending grooves ( 3 ) of a metal, tubular hollow body of a pipe spiral cartridge ( 1 ), in particular for metal plastic injection nozzles of injection molding systems, wherein the tubular heating cartridge ( 6 . 36 ) with at least one on a flexible winding core ( 16 ) of insulating material wound Heizdrahtwendel ( 15 ) provided in a metal jacket ( 11 . 22 ) of a metal shell filling, compacted insulating material ( 17 ) is enclosed, characterized in that the Heizdrahtwendel ( 15 ) for generating different Heizleistungsdichten with helical sections of different pitches or pitches (d1, d2, d3, etc.) on a thread, yarn or cord-like winding core ( 16 ) wound with less than 1 mm in diameter and with this winding core ( 16 ) in the metal shell ( 22 ) in one with the metal shell ( 2 ) compacted insulating material package ( 17 ) is embedded from metal oxide, in particular MgO or the like, in such a way that the helix sections of the heating wire helix ( 15 ) with the lowest slopes and winding spacings (d3) or with the highest heating power, the sections (E1, E2) of the cartridge spiral ( 12 ) or the cartridge snake ( 35 ) with the highest power densities. Electric tube heating cartridge for insertion in continuous, with the same and / or different gradients helical circumferential grooves ( 3 ) of the metal tubular body ( 2 ) a pipe spiral cartridge ( 1 ) according to claim 1, characterized in that the slopes and pitches of the heating wire coil ( 15 ) in the end regions (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 ceramic thread having a thickness of 0.1 to 0.7 mm or a ceramic cord formed of ceramic fibers. Electric tubular heater according to claim 1 or 2, characterized in that the Heizdrahtwendel ( 25 ) within the metal shell ( 22 ) in two parallel, electrically mutually insulated helical strands ( 23 . 24 ) runs. Electric tubular heating cartridge according to claim 4, characterized in that the helical sections with the different pitches (d1, d2, d3) of the one helical strand ( 23 ) are arranged differently and / or formed than those of the other helical 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 ) by Isolierstoffröhrchen, in particular ceramic tubes ( 30 ) is guided. 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.