DE102017120503B4 - Injection molded header for a heat exchanger, injection molding tool and method of making such - Google Patents

Abstract

Tool for injection molding a manifold (2) with a first length (L1) in the longitudinal direction (X) and two openings (4) at its ends (6) in the longitudinal direction (X) and a plurality of connection lugs (8) integrally formed one behind the other in the longitudinal direction. , with a first molding means (10) and a second molding means (12) which are movable relative to one another between a closed state and an open state, wherein in the closed state between the molding means (10, 12) a cavity (22) for injection molding the manifold (2) is formed, a slide device (32) with core pins (34) which can be inserted into the cavity (22) at an angle to the longitudinal direction, a first core feed device with a first core (26), which as a rectilinear structure and Is designed to be retractable into the cavity (22) from a first side, a second core feed device with a second core (28), which is in the form of a straight line e and is designed to be retractable in the longitudinal direction into the cavity (22), the cores (26, 28) each having an end (26b, 28b) located at the front in the direction of insertion, which is used for a positive connection to the respective front end (26b, 28b) of the other core, the core feed devices are designed to hold the cores (26, 28) pressed together in the retracted state during a supply of melt with a prestressing force, the slide device (32) and that of the cavity ( 22) facing ends of the core pins (34) are designed such that the ends of the core pins (34) facing the cavity (22) in the state inserted into the cavity (22) on each of the cores (26, 28) to form the connecting lugs at least two sprue points (46, 48) are provided, each of which form an opening opening into the cavity (22), through which the melt can be fed into the cavity (22), wherein the at least two sprue points have at least one first sprue point (46) in the region of the first core (26) and at least one second sprue point (46) in the region of the second core (26) and the at least two sprue points (46, 48) are on the Open the side of the cavity (22) opposite the core pins (34) into the cavity (22) so that the melt is pressed into the cavity (22) from each of the at least two gating points (46, 48) in and opposite to the longitudinal direction will that, when the melt is pressed in and opposite to the longitudinal direction, the melt exerts a force in and opposite to the longitudinal direction on the respective core due to its adhesion to the core, and a position in the longitudinal direction and the size of the opening of the at least one sprue point each Core are selected such that the force resulting from the sum of the forces exerted on the respective core by the melt is the prestressing force, with which the cores (26, 28) are pressed against one another during the feeding of the melt by means of the core feeding devices.

Description

The present disclosure provides a compact injection molding tool and a method of manufacturing an injection molded header for a heat exchanger, and such an injection molded header. The manifold is designed to be used as part of a heat exchanger system in buildings.

Heat exchangers for buildings are increasingly being integrated in ceilings, floors and walls to increase living comfort and reduce the required flow temperature. Modularly designed, and thus adaptable to any room shape, surface heat exchangers that can be integrated into the wall, floor or ceiling, for example, can be plastered, are formed by diagonally flowing through two parallel header tubes via a plurality of connecting tubes that run perpendicular to the header tubes.

Simple plastic pipes are usually (endlessly) extruded in the prior art. Using this technology, however, only components can be produced that have a cross section that remains constant perpendicular to the longitudinal direction. Plastic pipes with a non-constant cross-section, such as header pipes for the above-mentioned heat exchangers, in particular from a length of more than 30 cm, are usually injection molded using the half-shell process. For this purpose, a lower shell of the later tube is injection molded in a first step and an upper shell of the later tube is injection molded in a second step. In a third step, the two half-shells are connected to each other.

From the DE 10 2011 102 368 T5 a method is also known in which an air collector for internal combustion engines is produced in a two-part mold which has two opposite openings in the longitudinal direction and lateral openings through which, before casting, to form a cavity in the form of the air collector, multi-part cores from both sides in the longitudinal direction and additional cores are introduced perpendicular to it.

Furthermore, from the DE 25 37 251 A1 a method and mold core for producing a flexible hollow body open on several sides is known.

Since both the joining of the half-shells to one another to form a collecting pipe and the collecting pipes formed from the half-shells to one another by gluing or welding are susceptible to leaks, there is a need for a device and a method for producing collecting pipes and for collecting pipes themselves, with which leaks be avoided.

This object is achieved with a tool for injection molding according to claim 1 or 13, and a method according to claim 10 and a manifold according to claim 12. Further developments are given in the dependent claims.

Claim 1 specifies a compact tool for injection molding, with which, in cooperation with an injection unit, a collecting tube made of plastic, which can preferably be used in a heat exchanger, is produced. The respective material (base material) is liquefied with the injection unit and injected into the tool at high pressure. For example, a screw-piston injection unit that is common today is used as the injection unit, so that its detailed description is omitted here.

With the specified tool, manifolds with a length of preferably greater than 500 mm to preferably 2000 mm can be easily produced with a minimum wall thickness of preferably 1.5 mm to 4 mm. The inside diameter of the collecting tubes is preferably between 8 mm and 30 mm. The inside diameter in the longitudinal direction of the tube is preferably constant or has a low taper. The taper is achieved, for example, by an inner diameter which is enlarged at the ends of the collecting tube by approximately 0.3 mm with respect to the center of the collecting tube.

The manifold itself is integral, i.e. formed in one piece and in only one step, so that the collecting tube itself does not have the tightness problems known from half-shells. Due to the large length of the header pipe, it is possible to reduce the number of work steps involved in assembling the heat exchanger. Furthermore, the number of header pipes and thus the number of connections between header pipes are reduced, so that a further reduction in possible leaks at connection points of individual header pipes of such heat exchangers is achieved. At the same time, the manifold has a relatively small wall thickness and a relatively small inner diameter to meet the requirements for good heat transfer and good flow.

It has been found that two advantages can be achieved by using two cores which can be inserted into the cavity in opposite directions: firstly, the force with which each core is pulled out of the tool after the melt has hardened before the mold is opened must be significantly reduced (essentially halved) compared to a corresponding tool with only a core that is twice as long. On the other hand, the possible diameters and wall thicknesses of the cores, and thus their pull-out strength (which depends on the cross-sectional area), are significantly increased when using conical cores with the same maximum header tube inner diameter (which is determined from the largest core outer diameter) compared to a corresponding tool only one, but twice the core. This is particularly the case when using hollow cores.

By designing the (lengths of) the cores in such a way that one or both ends of the cores come into contact with a core pin, the ends connected to one another are further improved when the melt is fed in, supported by the corresponding core pin against deformation perpendicular to the longitudinal direction. The cores are preferably asymmetrical with an even number of lugs, i.e. with an unequal length, while with an odd number of connection lugs they are symmetrical, i.e. can be formed with the same length.

By forming at least one sprue point per core in such a way that it opens into the cavity on the side opposite the core pins, it is achieved that the melt only applies a force in one direction to the respective core that is in the plane of the core pins or the core itself and has at least one component in the direction of the core pins. The cores are therefore supported by the core pins against the force applied by the injected melt, so that bending is prevented. At the same time, the force applied to the cores by the supplied melt leads to an increase in the contact pressure of the cores on the core pins, so that a gapless contact of the core pins on the cores is achieved. This can ensure that the interiors of the connecting lugs formed with the melt are continuously connected to the interior of the collecting tube. Post-processing, for example to pierce a plastic film that can form between the core and the core pin if the core pin is not tight, can be avoided.

The sprue points are usually arranged and designed such that the melt is injected in and against the longitudinal direction starting from the sprue point. The sprue points and the further parameters of the melt feed are preferably designed such that the sprue point (s) formed in the area of the first core also only feed melt which also forms the corresponding section of the collecting pipe in the area of the first core. In other words, the melt supplied in the region of the first core preferably connects approximately in the region of the contact points of the cores with the melt supplied in the region of the second core. In the case of an elongated cavity, injection is therefore usually carried out in the middle of the corresponding region in order to reduce the distance that the melt has to travel to fill the cavity, which ultimately improves the flow behavior, etc. If the path is too long, the melt may cool even before reaching the end points, i.e. before completely filling the cavity. If there are several gating points, the distance between the gating points should be selected so that the melt of one gating point can combine with the melt of the other gating point to form an integral body. For this, it must be ensured that the melt has not yet set at the point of contact with the other melt.

Contrary to the usual central design of the sprue points, it has proven to be particularly advantageous not to arrange the sprue points centrally with respect to the area to be filled by them, but rather in relation to the center of the cavity in the longitudinal direction further out. By such a positioning of the gates in such a way that each core ultimately or in total exclusively towards the other core or at least not away from it during the feeding of the melt through the melt pressed into the cavity in and against the longitudinal direction is pressed, it is ensured that the cores are not separated from one another even during and after the injection of the melts. In other words: starting at one end in the longitudinal direction Z the cavity 22 with a total length L1 the first gate is preferably at one position X1 1 / 8xL1 <X1 <1/4 × L1 and the second gate is preferably at one position X2 3/4 × L1 <X2 <7/8 × L1.

The same effect can be achieved, in particular if more than two sprue points per core are provided, by specifying the size and thus the volume flow through the respective sprue point. For example, a larger volume flow through the outer gate also ultimately results in a force towards the other core.

The complementary conical design of the mutually facing ends of the cores results in a self-centering and secure connection of the cores which seals with little force.

Due to the hollow design of the cores, a cooling channel for cooling the core, preferably with compressed air, is available. The is preferred Cooling device designed such that in the state in which both cores are sealingly connected, a compressed air stream flows through both cores, and in the state in which both cores are not connected to one another, for example in the extended state, the cores each have their own compressed air stream is flowed through in opposite directions. This enables efficient cooling and thus higher cycle times and improved quality.

The combination of the above-mentioned features makes it possible to economically produce a particularly long header pipe with integrally formed connecting lugs, in which there are no joints and thus possible leaks are not only avoided but also excluded.

By holding the cores pressed together by means of at least one spring, it can be prevented that when the cores expand, the cores or the other tool are deformed or compressed. At the same time, it is ensured that the force with which the cores are pressed onto one another is maintained in order to prevent the melt from penetrating between the cores.

To further improve the flow behavior of the melt and / or the cycle time, several, for example two, gating points can be provided per core. It must be ensured. be that the sum of the forces acting on the respective core by the melt when the same is injected results in a force in the direction of the other core, at least not in a force in the direction away from the other core. A force is preferably continuously generated in the direction of the other core during the supply of the melt by means of the same. In particular, the melt should not result in any opposite force on the respective core in any state.

Even if there are several gates per core, the arrangement of the cores must ensure that the respective partial flows of the melt combine well. To achieve the stated goals (no force on cores in the direction away from one another, good bonding of the melts), both the position and the size of the gates or the gates supplying the gates must be taken into account and designed.

The collecting tube optionally has reinforcing ribs in the longitudinal direction and / or in the transverse direction.

Instead of using cores which have a conical second section, cores without conicity, i.e. Cores that have a constant cross section perpendicular to the longitudinal direction are used.

To improve the sealing connection between the two cores, an O-ring or the like can be used. be provided in the connection extension or connection receptacle. Furthermore, the connection extension and the connection receptacle are preferably matched to one another in such a way that the cores abut one another seamlessly in the connected (retracted) state. This ensures that the channel formed in the interior of the collecting tube is formed with a constant diameter throughout in the longitudinal direction.

To improve the cooling of the cores, the compressed air supplied is preferably cooled. For example, a vortex tube with which conventional compressed air is split into a cool and a warm compressed air flow can be used for this purpose.

The changeover between joint cooling of the cores (in the retracted state) preferably takes place starting from only one end of one of the cores and cooling, in which both cores are cooled starting from their respective outer ends, by a 3/2 way valve.

To reduce the cycle time, limit switches are preferably provided for the core end positions (retracted and extended).

To reduce the friction between the second molded part 12 and the cores can the second molding 12 alternatively, be opened before the cores are extended.

An ejection device can be provided to support the ejection of the collecting tube after the melt has solidified and the tool has been opened. Such an ejection device usually consists of ejector pins provided in the first molded part, which can be inserted into the cavity from below and press the collecting tube out of the first molded part without damage.

The manifold is made of PE, for example. For example, the material SA-BIC Vestolen P 9421 is used.

The tool can be designed in such a way that only a single continuous cavity for forming a single header pipe is formed by the molded parts or several (separate) cavities are formed for the simultaneous formation of several header pipes by the two molded parts. In the case of several cavities, there are also several Gate devices (at least one per cavity), sprue points (at least two per cavity) and cores (two per cavity) are provided. In the case of several cavities, the core feed devices can also feed several cores at the same time. Alternatively, a separate core feed device can be provided for each core.

• 1 eine skizzenhafte perspektivische Ansicht eines beispielhaften Werkzeugs in geöffneter Position gemäß einer ersten Ausführungsform,
• 2 eine Aufsicht auf das Spritgusswerkzeug gemäß der ersten Ausführungsform,
• 3 eine Querschnittsansicht des teilweise geschlossenen Spritgusswerkzeugs gemäß der ersten Ausführungsform,
• 4 in a) einen beispielhaften skizzenhaft dargestellten ersten Kern und in b) einen beispielhaften zweiten Kern zur Verwendung in einem Werkzeug gemäß der ersten Ausführungsform,
• 5 ein beispielhaftes skizzenhaft dargestelltes Sammelrohr gemäß einer ersten Ausführungsform,
• 6 einen beispielhaften skizzenhaft dargestellten Wärmetauscher, in dem ein Sammelrohr gemäß der ersten Ausführungsform verwendet wird.

In the following, embodiments and modifications are described with reference to the attached figures, of which show

• 1 2 shows a sketchy perspective view of an exemplary tool in the open position according to a first embodiment,
• 2 a plan view of the injection molding tool according to the first embodiment,
• 3 2 shows a cross-sectional view of the partially closed injection molding tool according to the first embodiment,
• 4 in a) an exemplary sketched first core and in b) an exemplary second core for use in a tool according to the first embodiment,
• 5 1 shows an exemplary header pipe according to a first embodiment,
• 6 an exemplary sketched heat exchanger in which a manifold according to the first embodiment is used.

That in the 3 completely and in the 1 and 2 partially shown tool (clamping unit) according to an exemplary first embodiment is used to form an in 5 shown manifold 2 with a first length ( L1 ) in an X direction (longitudinal direction) and two openings 4 at its ends 6 in the longitudinal direction and several integrally formed lugs 8th which are opened one behind the other in the longitudinal direction and in a Y direction (transverse direction) which is perpendicular to the longitudinal direction. In this embodiment, the manifold further shows how 5 can be seen in the areas where there are no connection lugs 8th are formed, preferably reinforcing ribs 9 which have a substantially rectangular outer contour in cross section perpendicular to the longitudinal direction and are connected to one another in the longitudinal direction by a web located above and below. The reinforcing ribs are optional and their design can be varied.

As is customary in the case of tools for injection molding, the device has a molding tool which is in two halves, namely a first molding 10 (Molding agent) and a second molding 12 (Molding agent) is divided. In the present embodiment, the first molded part extends 10 essentially rectangular in an XY plane, the long side of the rectangle in the X direction (longitudinal direction) and the transverse side of the rectangle in the Y direction (transverse direction). The first molding 10 is in a Z direction (height direction) on a base plate 14 (first platen) mounted. The base plate 14 is adapted to be rigidly attached to an injection unit, not shown.

The second molding 12 (Ejector side) is adapted to be attached to a further clamping plate, not shown, in an injection molding machine. The second molding 12 is with the second platen by means of a moving mechanism (not shown; mostly hydraulic) in the height direction Z movable between an open state and a closed state. In the opened state there is a predetermined distance between the first molded part 10 and the second molding 12 guaranteed to remove an injection molded manifold. The second molded part comes in the closed state 12 on the first molding 10 in a predetermined position as in Fog. 3 is shown for lying. In this position, a first contact surface lying in an XY plane touches 16 of the first molding 10 a second contact surface of the second molded part lying in an XY plane 12 ,

In every molding 10 . 12 are the first recesses in the contact surfaces 20 intended. The first cutouts are preferably essentially symmetrical with respect to the contact surfaces. When closed, through the first recesses 20 a cavity 22 formed the outer shape of the manifold to be manufactured 2 including connection lugs 8th and reinforcing ribs 9 Are defined. The first cutouts 20 The cavity formed is therefore the first length ( L1 ) in the X direction (longitudinal direction) to form the longitudinal extension of the collecting tube and a plurality of regions extending one behind the other in the longitudinal direction and in the Y direction (transverse direction) to form the connecting lugs 8th , The first recesses are so that the collecting tube can be removed after injection molding 20 each formed in a purely concave manner with respect to the respective contact surface.

Next are at the ends of the first cutouts 20 in the longitudinal direction in the first and the second molded part 10 . 12 second recesses 24 trained, each with a core 26 . 28 Can be inserted in the longitudinal direction, with which the cavity / interior of the manifold in the longitudinal direction X will be produced. Next are at the ends of the areas for forming the lugs 8th the first cutouts 20 third recesses 30 for one Shift means 32 into the cavity 22 (first recesses) insertable core pins 34 educated. The core pins 34 similar to the cores serve to form the openings / channels in the connection lugs 8th and the connection to the interior of the manifold 2 , The core pins are preferably arranged at a uniform distance from one another in the longitudinal direction, more preferably symmetrically with respect to the center of the collecting tube in the longitudinal direction. The connection lugs 8th are designed for later connection of connecting pipes.

A first core 26 is via a first core feeder into the cavity 22 retractable or retractable against the X direction. A second core 28 is in the cavity in the X direction via a second core feed device, ie opposite to the first core 26 insertable. Both cores are in the inserted position 26 . 28 pressed together. The core feed devices each have a core holding plate which can be displaced in or against the X direction 36 on. Every core holding plate 36 is slidable in the X direction on slide rods 38 held on the base plate 14 are mounted in the longitudinal direction X extend. Every core 26 . 28 is preferably detachable at one end on a respective core holding plate 36 attached. For moving each core holding plate 36 each core holding plate is in the X direction 36 via a hydraulic cylinder 39 with the base plate 14 connected. The core feed devices can preferably be locked in the retracted position. The contact pressure of the cores is preferably held against one another in the locked / retracted position by means of a spring (disc spring; not shown) which, for example, is between the core holding plate 36 and the core 26 . 28 is arranged. This ensures that the cores expand in the longitudinal direction due to the heat of the melt 26 . 28 bend or deform under rigid clamping.

To guide every core 26 . 28 when inserted into the cavity 22 is an interchangeable guide 40 (for example socket) provided on the base plate 14 or the first molded part 10 (from the inside out) following the second recess 24 is arranged.

4a shows a detailed view of the first core 26 . 4b a detailed view of the second core 28 , In this embodiment, the first core is 26 with a first ending 26a and a second end 26b as a tubular body with a constant first inside diameter d1 educated. Starting from the first end 26a is the first core 26 in the longitudinal direction essentially divided into two sections. A first section 26c with a second length 12 in the longitudinal direction has a constant first outer diameter d2 on. A second section 26d with a third length 13 tapering in the longitudinal direction (with a first taper of k Degrees) starting from the first section 26c conical to the second end 26b out. The first end 26a serves to fasten the first core 26 on the corresponding core holding plate 36 , The first end is preferred 26a therefore designed with a corresponding mounting flange.

The second end 26b is for connection to a second end 28b of the second core. For this, the second end points 26b in this embodiment, a frustoconical, tapering end of the hollow connection extension 26e on, for inserting or inserting into a correspondingly complementarily designed, conically widening connection receptacle 28e in the second end 28b of the second core 28 suitable is. The connection extension 26e has a slight oversize compared to the connection receptacle 28e , so that a secure and tight fit is guaranteed. Alternatively or additionally, an O-ring can be provided.

Essentially analogous to the first core 26 is the second core in this embodiment 28 with a first ending 28a and a second end 28b as a tubular body with preferably the same constant first inner diameter d1 educated. Starting from the first end 28a is the second core 28 is essentially divided into two sections in the longitudinal direction. A first section 28c with a fourth length 14 in the longitudinal direction has the constant first outer diameter d2 on and a second section 28d with a fifth length 15 lengthens in the longitudinal direction (with the same first taper of k Degrees) start from the first section 28c conical to the second end 28b out. The first end 28a serves to fasten the first core 28 on the corresponding other core holding plate 36 , The first end is preferred 28a therefore designed with a corresponding mounting flange. The second end 28b is, as described above, for connection to a second end 26b of the first nucleus 26 with the connection receptacle 28e educated.

The lengths 13 and 15 The conical sections are preferably dimensioned so that in the state in which the cores 26 . 28 into the cavity 22 are retracted in the cavity 22 part of each core 26 . 28 the second section 26d . 28d , which is conical. This ensures that only the second sections 26d . 28d surrounded by the melt and pulling out the cores 26 . 28 is relieved due to the taper.

In the present embodiment, the lengths are 13 and 15 still different formed, in such a way that the second ends 26b . 28b itself at one point with respect to the longitudinal direction of the cavity 22 hit that at least one of the ends 26b . 28b , preferably both ends 26b . 28b by retracting one of the core pins 34 , preferably one of the middle core pins 34 (with an even number of core pins) or the middle core pin 34 (with an odd number of core pins) can be brought into contact with it.

The lengths 12 and 14 of the first sections 26c . 28c are dimensioned so that the second sections 26d . 28d over the first sections 26c . 28c that are in the retracted state of the cores 26 . 28 through the second recess 24 and the leadership tool 40 extend to the core holding plates 36 are attachable.

The slide device 32 is designed to the core pins 34 to form the openings or interior spaces of the connection lugs 8th before feeding the melt into contact with the cavity 22 inserted cores 26 . 28 bring to. Because of the cores 26 . 28 formed and extending in the longitudinal direction of the tube interior (cavity) of the header 2 with the openings (cavities) of the connection lugs 8th The core pins must be communicatively connected 36 that the openings of the lugs 8th train in close contact with the respective core 26 . 28 brought (slider inking). For this purpose, the ends of the core pins facing the respective core have 36 a concave surface that corresponds to the outer diameter of the respective core corresponding to the respective position 26 . 28 corresponds and thus a sealing system to the core 26 . 28 allowed. Next is the slide device 32 trained to use the core pins 34 after the melt has hardened from the cavity 22 to pull out into the third recesses. This will remove the manifold 2 from the molded parts 10 . 12 allows.

Furthermore, in the contact surfaces of the molded parts 10 . 12 a fourth recess each 42 trained with the at least one sprue 44 and two gates 46 . 48 be formed. With the sprue 44 the melt from the injection unit, not shown, to at least two sprue points 46 . 48 that are in the cavity 22 open, directed.

It turned out to be advantageous to use the gate points 46 . 48 based on the cavity 22 on the opposite side of the core pins 34 and parallel to the same (i.e. in the Y direction) into the cavity 22 training open. The gate points 46 . 48 are designed so that melt emerging from them hits the corresponding core and this in the direction of the core pins 34 suppressed. So the kernels 26 . 28 when feeding the melt to the core pins 34 supported. In addition, the adjacent connection from core to core pin is strengthened.

A first gate 46 is in a state where the tool is closed and the cores 26 . 28 into the cavity 22 are retracted in the area of the first core 26 provided (see 2 , Position X1 ). A second gate 48 is in a state where the tool is closed and the cores 26 . 28 into the cavity 22 are retracted in the area of the second core 28 provided (see 2 , Position X2 ). In the present embodiment, the sprue points have the same size and essentially the same volume flow of melt is fed to each sprue point via the sprue channel.

As described above, it has turned out to be advantageous not to arrange the sprue points in the center with respect to the length of the corresponding core (area), but rather slightly outwards, that is to say offset to the outer ends of the cores. In other words: starting at one end in the longitudinal direction Z the cavity 22 with a total length L1 the first core is preferably at one position X1 1/8 × L1 <X1 <1/4 × L1 and the second core is preferably at one position X2 3/4 × L1 <X2 <7/8 × L1 (see 2 ). The sprue points should not be arranged any further out, otherwise there may be disadvantages with regard to the connection of the melts in the middle (contact point of the cores). The gating points are preferably at the same distance from one another as the point of contact of the two cores, so that the individual melt flows flowing inward meet one another essentially at the point of contact of the cores. Alternatively, the size or position of the gate points can be varied.

By supplying melt through the gates 46 . 48 the melt is pressed into the cavity. The melt is inside the cavity 22 starting from the corresponding gate 46 . 48 pressed in and against the longitudinal direction. When the melt is pressed in one direction, the melt also exerts a force in the same direction on the respective core due to its adhesion to the respective core.

With only one gate 46 . 48 per core 26 . 28 the forces per core cancel each other in and against the longitudinal direction at the beginning of the supply of the melt, since the melt originates from the respective gate 46 . 48 is pressed equally in and against the longitudinal direction. With respect to a core, the respective sprue point is arranged in the center 46 . 48 this equilibrium of forces is maintained until the melt is completely supplied. With the present relocation of the sprue point 46 . 48 outwards (away from the Point at which the retracted cores are connected), depending on the degree of displacement to the outside, after a period of equilibrium the corresponding core 26 . 28 inside, towards the other core 26 . 28 there, oppressive force. Because the cavity 22 fully filled in an outward direction before the cavity 22 is completely filled in an inward direction, the entire volume flow of the melt will ultimately be directed inward and apply a corresponding force to the respective core.

Furthermore, a cooling device (not shown) for cooling the cores is preferred 26 . 28 provided by means of which the cores 26 . 28 can be cooled. The cooling device is designed to be in a state in which the cores 26 . 28 into the cavity 22 are retracted and connected to a tube at one outer end of one of the cores 26 . 28 Compressed air for cooling the cores 26 . 28 feeds from the inside. This allows the cores 26 . 28 be cooled during the supply of the melt and during the curing. Furthermore, the cooling device is designed such that it is during and after the extension or before and during the insertion of the cores 26 . 28 at the outer first ends 26a . 28a both cores 26 . 28 Compressed air for cooling the cores 26 . 28 feeds from the inside. This allows the cores 26 . 28 after hardening, ie while the cores are being extended and retracted 26 . 28 and with the cores extended 26 . 28 be cooled.

Furthermore, a cooling device (not shown) for cooling the molded parts is preferred 10 . 12 provided by means of a cooling fluid, being in the molded parts 10 . 12 cooling channels 49 are provided, through which a cooling fluid is passed.

In the following, the method is described in which the manifold is made using the tool described above 2 as it is in the 5 is shown, is formed.

The in the 1 and 2 Assembly shown (tool without a second molded part 12 ), as described above, is fixedly mounted on an injection unit, preferably in such a way that the longitudinal extent (X direction) runs vertically. The vertical arrangement allows the use of tools in conventional spraying machines designed for the spray volume without special adaptation. The second molding 12 is in contact with the first molded part by means of a traversing mechanism 10 brought (and preferably locked) so that the cavity 22 between the molded parts 10 . 12 is trained.

The next step is the cores 26 . 28 into the cavity from both sides in opposite directions by means of the core feed device 22 retracted and pressed together. The cores are over the guide means or in the second recess 24 and through the core holding plates 36 held or led. By providing the conical connection extension 26e on the first core 26 and the correspondingly conical connector 28e in the second core 28 become the kernels 26 . 28 When the end positions are reached, they are aligned coaxially with one another and their interiors are tightly connected to one another to the environment, in particular to the cavity.

In a next step, using the slide device 32 the core pins 34 perpendicular to the longitudinal direction in the cavity 22 retracted and in contact with the cores 26 . 28 brought.

In this state, the melt can be injected through the fourth recess 42 , ie the sprue 44 respectively. When the melt enters the cavity 22 is in the area of the respective gate 46 . 48 a force perpendicular to the longitudinal direction on the respective core 26 . 28 applied. A corresponding shift or deformation of the respective core 26 . 28 is by means of the core pins arranged opposite 34 prevented.

Due to the described positioning of the gate points 46 . 48 in the longitudinal direction is the force with which the cores 26 . 28 pressed together in the middle, increased, at least not reduced.

The cores are used for a high cycle time and uniform solidification of the melt 26 . 28 cooled by one side in the longitudinal direction X Compressed air is passed through both cores.

After the melt solidifies, the cores can 26 . 28 by means of the hydraulic cylinders 39 be removed from the now solidified melt. The friction forces between the solidified melt and the core that occur in this process are reduced due to the taper. Furthermore, the small outer diameter and the short lengths of the cores contribute to a low pull-out force. Preferably before extending the cores 26 . 28 become the core pins 34 also moved outwards (perpendicular to the longitudinal direction) so that the cores 26 . 28 without additional friction on the core pins 34 can be pulled out.

Already during extraction, at the latest afterwards, the cores are cooled further 26 . 28 two cores 26 . 28 Compressed air supplied separately, for example by switching a 3/2 way valve of a compressed air supply provided for this purpose.

After removing the cores 26 . 28 and the core pins 34 becomes the second molding 12 removed and the injection molded manifold 2 removed from the tool. In a post-processing, if necessary, through the sprue 44 formed webs removed.

The manifold designed in this way 2 can like it in 6 is shown, then to form a heat exchanger 50 be used.

Furthermore, possible modifications are described which can be used individually or in combination with the described embodiment and the objects specified in the claims.

The core pins can also be oriented obliquely to the longitudinal direction and / or arranged irregularly. The reinforcing ribs partially shown in the figures are optional, in particular are shown in FIGS 1 to 3 shown cavity no corresponding recesses for forming such ribs shown.

The first length L1 the manifold or the cavity 22 is preferably between 500 mm and 2000 mm, more preferably between 800 mm and 1300 mm and even more preferably between 950 mm and 1050 mm, such as 1014 mm (first preferred example) or 984 mm (second preferred example).

The second length l2 of the first section 26c of the first core 26 is preferably between 80 mm and 150 mm, more preferably between 90 mm and 130 mm and even more preferably between 110 mm and 130 mm, such as 126 mm (first and second preferred example).

The third length l3 of the second section 26d of the first core 26 without the connection extension 26e is preferably between 300 mm and 1000 mm, more preferably between 400 mm and 800 mm and even more preferably between 500 mm and 600 mm, such as 540.25 mm (first preferred example) or 540 mm (second preferred example).

The fourth length l4 of the first section 28c of the second core 28 is preferably between 80 mm and 150 mm, more preferably between 90 mm and 130 mm and even more preferably between 110 mm and 130 mm, such as 126 mm (first and second preferred example).

The fifth length l5 of the second section 28d of the second core 28 without the connection receptacle 28e is preferably between 300 mm and 900 mm, more preferably between 400 mm and 800 mm and even more preferably between 450 mm and 550 mm, such as 489.35 mm (first preferred example) or 489 mm (second preferred example).

The taper k of the second sections 26d . 28d the kernels 26 . 28 is preferably between 0.001 ° and 0.1 °, more preferably between 0.01 ° and 0.05 ° and even more preferably between 0.015 ° and 0.04 °, such as 0.02 °.

The first inside diameter d1 the core is preferably 1 mm to 5 mm, more preferably 1.5 mm to 4 mm and even more preferably 2 mm to 3 mm, such as 2.5 mm (first and second preferred examples).

The second outside diameter d2 the kernels 26 . 28 in their first sections 26c . 28c is preferably 8 mm to 30 mm, more preferably 10 mm to 15 mm and even more preferably 11 mm to 13 mm, such as 11.95 mm (first preferred example) or 12.2 mm (second preferred example).

The third outside diameter d3 of the manifolds 2 or the inner diameter d3 the cavity 22 (each with the exception of the reinforcing ribs, ie only that diameter which forms the tube itself, ie without reinforcing ribs) is preferably 8 mm to 40 mm, more preferably 12 mm to 20 mm and even more preferably 14 mm to 18 mm, such as 16.2 mm (first and second preferred example).

The minimum wall thickness of the cores is preferably between 2 mm and 8 mm with a maximum molded core length of 600 mm for non-conical cores.

The distance between the center points of the connecting lugs is preferably between 10 mm and 100 mm, more preferably between 20 mm and 80 mm, such as 50 mm or 70 mm.

It is explicitly emphasized that all features disclosed in the description and / or the claims are considered separate and independent from each other for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention regardless of the combinations of features in the embodiments and / or the claims should. It is explicitly stated that all range indications or indications of groups of units disclose any possible intermediate value or subset of units for the purpose of the original disclosure as well as for the purpose of restricting the claimed invention, in particular also as a limit of a range specification.

The terms “approximately”, “approximately”, “approximately”, “essentially” or “in general” used here, which are used in connection with a measurable value such as a parameter, a quantity, a shape, a time duration or the like , deviations or fluctuations of ± 10% or less, preferably ± 5% or less, more preferably ± 1% or less and further preferably ± 0.1% of the respective value or of the respective value, if these deviations are included the implementation of the disclosed invention in practice are still technically useful. It is expressly pointed out that the value to which the term “approximately” refers is expressly and specifically disclosed as such. The indication of ranges by start and end values includes all those values and fractions of these values which are enclosed by the respective range, as well as its start and end values.

LIST OF REFERENCE NUMBERS

2

manifold

4

Longitudinal openings at the ends

6

Longitudinal ends

8th

connection lugs

9

reinforcing ribs

10

first molding (molding compound)

12

second molding (molding compound)

14

baseplate

16

first contact surface

20

first recess

22

Cavity for manifold

24

second recess

26

first core

26a

first end

26b

second end

26c

first section

26d

second part

26e

Terminal extension

28

second core

28a

first end

28b

second end

28c

first section

28d

second part

28e

terminal receiving

30

third recess

32

Shift means

34

core pin

36

Core support plate

38

sliding bars

39

hydraulic cylinders

40

guide means

42

fourth recess

44

runner

46

first gate

48

second gate

49

cooling channels

50

heat exchangers

L1

Length of collecting tube (first length)

12

first section first core

13

second section first core

14

first section second core

15

second section second core

d1

Inner diameter cores

d2

Outside diameter of the first section of cores

d3

Outside diameter of collecting pipe (without reinforcing ribs)

Claims (13)

Tool for injection molding a manifold (2) with a first length (L1) in the longitudinal direction (X) and two openings (4) at its ends (6) in the longitudinal direction (X) and a plurality of connection lugs (8) integrally formed one behind the other in the longitudinal direction , With a first molding means (10) and a second molding means (12) which are movable relative to each other between a closed state and an open state, wherein in the closed state between the molding means (10, 12) a cavity (22) for injection molding the Collector tube (2) is formed, a slide device (32) with core pins (34) which can be inserted into the cavity (22) at an angle to the longitudinal direction, a first core feed device with a first core (26), which as a rectilinear structure and is designed to be retractable in the longitudinal direction into the cavity (22), a second core feed device with a second core (28), which is a rectilinear Ge and is designed to be retractable in the longitudinal direction into the cavity (22), the cores (26, 28) each having an end (26b, 28b) lying at the front in the retracting direction, which for the form-fitting connection to the respective front end (26b, 28b) of the other core, the core feed devices are designed to hold the cores (26, 28) pressed together in the retracted state during a supply of melt with a pretensioning force which The slide device (32) and the ends of the core pins (34) facing the cavity (22) are designed in such a way that the ends of the core pins (34) facing the cavity (22) in each case on one of the cores in the state inserted into the cavity (22) (26, 28) to form the connecting lugs, at least two sprue points (46, 48) are provided, each of which form an opening opening into the cavity (22), via which the melt can be fed into the cavity (22), wherein the at least two sprue points have at least one first sprue point (46) in the region of the first core (26) and at least one second sprue point (46) in the region of the second core (26) n and the at least two sprue points (46, 48) open into the cavity (22) on the side of the cavity (22) opposite the core pins (34), so that the melt starts from each of the at least two sprue points (46, 48) in and opposite to the longitudinal direction is pressed into the cavity (22) such that when the melt is pressed in and opposite to the longitudinal direction, the melt exerts a force in and opposite to the longitudinal direction on the respective core due to its adhesion to the core, and a position in the longitudinal direction and the size of the opening of the at least one sprue point per core are selected such that the force resulting from the sum of the forces exerted on the respective core by the melt is the prestressing force with which the cores (26, 28) during the feeding of the melt by means of the core feeders are not reduced. Tool after Claim 1 , in which the first length (L 1) of the cavity (22) for forming the manifold (2) fulfills the following condition: 500mm <L1 <2000mm, and / or an outer diameter (d3) of the manifold formed in the cavity (22) ( 2) is between 10.6 mm and 40 mm, the outer diameter (d3) of the collecting tube (2) formed in the cavity (22) being at least 2.6 mm larger than the outer diameter (d2) of the cores, and / or a The outer diameter (d2) of the cores is between 8 mm and 30 mm, and / or the minimum wall thickness of the collecting tube (2) is between 1.3 mm and 4 mm. Tool after Claim 1 or 2 , in which the lengths of the cores are designed such that at least one of the front ends (26b, 28b) of the cores (26, 28) in the state of the positive connection with the other front end (26b, 28b) after the retraction of the Core pins (34) are in contact with one of the core pins (34). Tool according to one of the preceding claims, in which the melt which is fed in via the first sprue point in the region in which the respectively front ends of the cores touch one another in the retracted state with the melt which is fed in via the second sprue point , comes into contact. Tool according to one of the preceding claims, in which a total of two sprue points are provided, a first sprue point being designed for supplying melt in the region of the first core and a second sprue point being designed for supplying melt in the region of the second core and each of the sprue points in a distance in the longitudinal direction from the point of contact of the cores in the retracted state is greater than half the length (13, 15) of the respective part of the core which is in the cavity in the retracted state. Tool according to one of the preceding claims, in which the connecting lugs are opened in a first direction (Y) which is perpendicular to the longitudinal direction (X). Tool according to one of the preceding claims, in which the cores (26, 28) are designed as a tube, and a cooling device for cooling the cores (26, 28) connected to one another in the retracted state by passing air in or opposite to the longitudinal direction (X) through the two cores (26, 28) together and / or for cooling those not connected to one another in the extended state Cores (26, 28) is provided by passing air together or separately through each of the cores (26, 28). Tool according to one of the preceding claims, in which the cores (26, 28) are cylindrical or have a cross-sectional shape that is constant in the longitudinal direction (X) or the cores (26, 28) are at least partially cylindrical or partially in the longitudinal direction (X) with a constant cross-sectional shape and partially conical or or Cores (26, 28) are conical, and / or the cores (26, 28) are hollow and the mutually facing ends (26b, 28b) of the cores (26, 28) have a conical fit, by means of which a coaxial, self-aligning and tight connection between the cores (26, 28) is achieved. Tool according to one of the preceding claims, in which the force with which the cores in the retracted state are kept pressed together, thereby achieving that at least one of the cores in the retracted position is kept pressed towards the other core by means of a spring. Process for injection molding a manifold (2) with a first length (L1) in the longitudinal direction (X) and two openings (4) at its ends (6) in the longitudinal direction (X) and a plurality of integrally formed connecting lugs (8) in the longitudinal direction (X) one behind the other and in a first direction (Y), which is perpendicular to the longitudinal direction (X), with the following steps: Insertion of two cores (26, 28) into a cavity (22) formed between two molding means (10, 12) in such a way that the ends (26b, 28b) of the cores facing each other are held against one another with a prestressing force, Pushing in a plurality of core pins (34) running one behind the other in the longitudinal direction and at an angle to the cores to form connecting lugs (8) such that the core pins (34) come into contact with one of the cores (26, 28) . Injecting melt from a side opposite the core pins (34) in the cavity (22) into the cavity (22) through at least two gating points (46, 48), each of which forms an opening opening into the cavity (22), wherein the at least two sprue points have at least a first sprue point (46) in the region of the first core (26) and a second sprue point (46) in the region of the second core (26), which are arranged such that the melt starts from each of the at least two Gating points (46, 48) in and opposite to the longitudinal direction are pressed into the cavity (22) in such a way that when the melt is pressed in and opposite to the longitudinal direction, the melt, due to its adhesion to the core, exerts a force in and opposite to the longitudinal direction exercises the respective core, and a position in the longitudinal direction and the size of the opening of the at least one sprue point per core are selected such that the force resulting from the sum of the forces exerted on the respective core by the melt is the prestressing force with which the cores (26, 28) during the feeding of the melt is pressed against one another by means of the core feeding devices, not reduced, Removing the cores (26, 28) by pulling the cores (26, 98) out of the cavity (22) in mutually opposite directions in and against the longitudinal direction (X), and Open the mold (10, 12) and remove the injection-molded manifold (2) after the melt has solidified. Procedure according to Claim 10 , in which the cores (26, 28) are tubular and cooled by passing air through them during the introduction of the melt, during and / or before and / or after the insertion and / or extension of the cores (26, 28) become. Injection molded integrally formed manifold (2) for a heat exchanger with a first length (LI) between 500mm and 2000mm in the longitudinal direction (X), a wall thickness between 1.5 mm and 4 mm, two openings (4) at its ends (6) in the longitudinal direction (X) and a plurality of integrally formed connecting lugs (8) which are opened one behind the other in the longitudinal direction (X) and in a first direction (Y) which is perpendicular to the longitudinal direction (X), which is achieved by the method steps according to Claim 10 or 11 was produced. Tool for injection molding a manifold (2) with a first length (LI) in the longitudinal direction (X) and two openings (4) at its ends (6) in the longitudinal direction (X) and a plurality of connection lugs (8) integrally formed one behind the other in the longitudinal direction. , With a first molding means (10) and a second molding means (12) which are movable relative to each other between a closed state and an open state, wherein in the closed state between the molding means (10, 12) a cavity (22) for injection molding the Collector tube (2) is formed, a slide device (32) with core pins (34) which can be inserted into the cavity (22) at an angle to the longitudinal direction, a first core feed device with a first core (26), which as a rectilinear structure and is designed to be retractable in the longitudinal direction into the cavity (22), a second core feed device with a second core (28), which is a rectilinear Ge and is designed to be retractable in the longitudinal direction into the cavity (22), the cores (26, 28) each having an end (26b, 28b) lying at the front in the insertion direction, which for positive connection to the one at the front Is formed at the end (26b, 28b) of the other core, the core feed devices are designed to hold the cores (26, 28) pressed together in the retracted state during a supply of melt with a biasing force, the slide device (32) and that of the cavity (22) facing ends of the core pins (34) are designed such that the ends of the core pins (34) facing the cavity (22) in the state inserted into the cavity (22) on each of the cores (26, 28) to form the Contact lugs, two sprue points (46, 48) are provided, each of which form an opening opening into the cavity (22) through which the melt enters the cavity (22) can be supplied, the two sprue points having a first sprue point (46) in the region of the first core (26) and a second sprue point (46) in the region of the second core (26), the two sprue points (46, 48) being on the Open the core pins (34) on the opposite side of the cavity (22) into the cavity (22) so that the melt is pressed into the cavity (22) starting from each of the two gates (46, 48) in and opposite to the longitudinal direction, and each of the gates is spaced in the longitudinal direction from the contact point of the cores in the retracted state which is greater than half the length (13, 15) of the respective part of the core which is in the cavity in the retracted state.

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