Method for producing a hollow cylindrical molded part having a thread

Abstract

The invention relates to a method for producing a molded part (1) comprising a hollow cylindrical main body (2) having a mounting portion (MA), a fastening portion (BA) that adjoins the mounting portion in the axial direction (X-X), and at least one internal thread and / or external thread (10); wherein portions each with a different function are arranged successively in an inner channel (3) of the main body (2) for sealingly accommodating a plug part (4); and wherein the main body (2) is manufactured by injection molding, into a cavity, a fiber-containing (F) plasticized thermoplastic polymer mass (M) that flows around an inner core of the injection mold (100), resulting in the fibers (F) being oriented. According to the invention, the injection mold (100) comprises four segments (S1, S2, S3, S4), by means of which the cavity is formed.

Description

[0001] "Method for manufacturing a hollow cylindrical molded part with thread"

[0002] The present invention relates to a method for manufacturing a hollow cylindrical component with an annular cross-section, such as a screw, a nut, a socket, a pipe connector, a pipe fitting, or the like, wherein the component has a hollow cylindrical base body with a mounting section and with a fastening section adjacent thereto in the axial direction, wherein, in particular, sections with different functions are arranged one another in the axial direction in an inner channel of the base body intended for the sealing reception of a connector part, and wherein the base body has at least one internal thread and / or one external thread and is manufactured by injection molding a fiber-containing plasticized thermoplastic polymeric mass into a cavity of an injection mold, wherein the injection into the cavity is carried out through at least one injection port.wherein the plasticized thermoplastic polymer mass flows in a ring-shaped pattern around an inner core of the injection mold, and wherein the fibers align themselves during injection and cavity filling.

[0003] In particular, if the base body has an external thread in its fastening section, the molded part may have a threadless area with a comparatively small wall thickness in the transition from this fastening section to the axially adjoining assembly section, which usually has a larger diameter than the fastening section and is mostly designed as a flange-like polygon for the engagement of an assembly tool. This area is also referred to as a thread relief, and a seal is often arranged in this area when making a connection, with the thread relief acting as a sealing groove or sealing channel.

[0004] It is well known that brass union nuts are commonly used, particularly in plug-in systems for compressed air applications. However, polymer or hybrid molded parts, especially those manufactured by injection molding as described above, are also known from the prior art. This reflects the desire to replace brass with plastic, primarily for cost savings. Another reason for this trend is that brass threads are now often screwed into aluminum components, which can lead to contact corrosion. For this reason alone, the use of plastic is highly advantageous.

[0005] In practice, the thread relief groove has often proven problematic when using a plastic for the base body. This is due, on the one hand, to the totality of stress concentrations on the outside of a hollow cylindrical molded part of the type mentioned above, which can reach their maximum in this area, particularly when tightening a molded part designed as a cap screw. Stress concentrations are especially noticeable at changes in diameter, circumferential edges, or radii – both on the outside and on the inner contour of the hollow cylindrical molded part.

[0006] Another reason why the thread relief often proves problematic is as follows. Connector components in modern plug-in systems with a hollow cylindrical molded part manufactured according to the aforementioned method are also often made of plastic and have diameters that increase in the opposite direction of mating. The reason for this increasing diameter is that bending or alternating loads acting on the connector are concentrated in a section of the connector located in the upper area, i.e., in the area of ​​the mounting section of the hollow cylindrical molded part, or that protrudes from it. Here, the connector has little or no support. Since the diameter of the inner bore cannot be reduced, the outer diameter of the connector must be increased to ensure sufficient strength.

[0007] This in turn means that the inner diameter of the hollow cylindrical component, as mentioned at the beginning, especially of a union nut, must also be made larger in this area by using a thicker core during manufacturing, and if this is the case in the area of ​​the thread relief, the wall thickness in the thread relief can become so small that it cannot withstand the required tightening or loosening torques, so that breakage may occur in the area of ​​the thread relief.

[0008] The production of molded parts of the type mentioned above is known, for example, from WO 2022 / 136406 A1, WO 2013 / 092234 A1 and WO 2009 / 124994 A1. Similar methods of molded part production are also described in WO 2013 / 124994 A1 and DE 10 2010 010 651 A1, the latter being distinguished by the fact that the base body of the molded part, on the one hand, and any thread locking devices and / or circumferential seals, on the other, are produced from different polymeric materials in a multi-component injection molding process.

[0009] Injection molding is a well-known, discontinuous primary forming process, particularly used for plastics. It allows for the industrial production of large quantities of ready-to-use molded parts with high precision. In the injection unit of an injection molding machine, the respective material or molding compound is plasticized and injected into an injection mold. Modern injection molding machines use a screw that plasticizes the molding compound – which may be supplied as plastic pellets, for example – conveys it, and finally injects it into the mold. The polymer solidifies in the cavity of the mold, after which the molded part can be demolded. While volume shrinkage that occurs during solidification can generally be compensated for – but only up to a certain point – by applying holding pressure before demolding, this is only possible to a certain extent.

[0010] Injection molding can be used to process thermoplastics, thermosets, and elastomers. It is also known to use fillers, especially fibers, in the injection molding of thermoplastics, which allows for the production of higher-strength parts compared to parts without fillers.

[0011] According to a method of the type mentioned above, known from WO 2009 / 124994 A1, for the production of a molded part, it is provided that the injection into the cavity is carried out through at least two injection ports such that the fibers align predominantly in the main directions of axial tension and torsion of the molded part. The injection takes place in the axial direction, with the material flowing in a ring-shaped pattern around an inner core of the mold and converging between the injection ports. Weld lines are formed at these points, which generally exhibit lower strength than the rest of the molded part.

[0012] A stress-resistant structure of the known molded part consists in the fact that, on the one hand, the proportion of fibers oriented perpendicular to a longitudinal axis of the molded part in the circumferential direction of the annular cross-section, and on the other hand, the proportion of fibers oriented in the axial direction of the molded part, is each less than 50 percent. While the method can surprisingly compensate for a negative weld line effect, at least partially, a disadvantage is that, when hot runner nozzles are used, a reliable and uniform cavity filling cannot always be guaranteed with a known multiple gate as described in the document without additional process stabilizing measures.

[0013] It has been shown that in industrial applications of screwed components, such as those mentioned at the beginning, the torsional stress on the component often becomes less important after assembly than the axial tensile stress. However, the maximum torque that can be applied without breakage during the screwing or tightening of the component plays a significant role. In any case, a multiaxial stress state develops—especially during the assembly of a component of the type mentioned above—particularly in the area of ​​the aforementioned undercut. This results, in particular, in the requirement for high tensile strength, increased shear strength, and greater effectiveness in the tightening process during manufacturing.The term "pressure effectiveness" refers in particular to the fact that the applied pressure results in a homogeneous filling of the cavity, free of voids and - if weld lines are present - with high weld line strength.

[0014] The methods of the type mentioned above for the production of molded parts as plastic injection molded parts, known from WO 2009 / 124994 A1 and the other above-mentioned publications, offer advantageous technical solutions under the aforementioned aspects and have generally proven themselves in practice; however, it has been shown that the various registered designs of molded parts - with the exception of those according to WO 2022 / 136406 A1 - could not always take into account the very high stress profiles that often occur in practice, especially during assembly and disassembly, with sufficient stability.Many different reasons can contribute to the partial premature failure of known components, especially those designed as union bolts, such as problems inherent in the manufacturing process, for example dimensional issues, such as out-of-roundness, jamming of the threads in the fastening section, shearing of the threads, up to and including the breaking off of a polygon, preferably forming the, in particular flange-like, assembly section, during tightening or loosening.

[0015] A complete geometric redesign of a connection, especially a plug connection, using a molded part as mentioned earlier, could potentially resolve all these problems, but would then result in entirely different dimensions. However, these types of connections are widespread, with threaded holes in the inner channel, or even the connecting bores, often having specific dimensions, sometimes even being standardized. Furthermore, it is not easily possible, for example, to reduce the inner diameter of plug components to increase their wall thickness, because this would not create the desired or necessary flow characteristics. For instance, this could negatively affect the response times of pneumatic brakes.

[0016] According to WO 2022 / 136406 A1, the objective is to provide a screw component that avoids the disadvantages known from the prior art – e.g., those from WO 2009 / 124994 A1 – and in particular exhibits a high applicable torque and low manufacturing tolerance. The document describes a screw component with an annular cross-section, in particular a hollow screw or a nut, comprising a hollow cylindrical base body injection-molded at least partially from a fiber-containing plasticized polymeric mass, wherein the base body has at least one internal thread and / or one external thread and an internal channel for arranging and / or passing a piping system element in an insertion direction.wherein the inner channel has at least one sealing section for arranging a circumferential seal for sealing between the inner channel and the piping system element and / or at least one support section for supporting and / or guiding the piping system element and / or at least one retaining section for directly or indirectly locking the piping system element, wherein a preferably metallic insert sleeve is arranged coaxially to the inner channel in the base body, which is at least partially overmolded by the polymeric mass, so that the insert sleeve is at least partially surrounded by the polymeric mass in a radial direction to the inner channel and radially repelling from the inner channel.

[0017] Preferably, the polymeric mass used for production is a thermoset, comprising an epoxy resin (EP), an unsaturated polyester resin (UP), a vinyl ester resin (VE), a phenol-formaldehyde resin (PF), a diallyl phthalate resin (DAP), a methacrylate resin (MMA), a polyurethane (PUR), an amino resin, a melamine resin (MF / MP), or a urea resin (UF). Molded parts with a thermoset matrix cannot be reshaped after curing or crosslinking of the matrix. However, they exhibit a wide operating temperature range and extremely high strength. This is particularly true for heat-curing systems that are cured at high temperatures.

[0018] However, a thermoplastic, such as polyamide (PA), can also be used as the polymeric mass.

[0019] For connectors in plug-in systems with hollow cylindrical molded parts, such as those produced using the aforementioned process, filled polyamide plastics (PA), particularly those filled with 50% glass fibers by mass, are often used. Polyamides (PA), which can exist in various compositions depending on their manufacturing process, are generally classified as engineering plastics, a category that also includes polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), and polyoxymethylene (POM). For the aforementioned application as connectors, PA 6.6, PA 11, or PA 12 are frequently chosen, ensuring cost-effective manufacturing with regard to overall material usage.

[0020] The forces acting on connector components are generally lower than the tightening or loosening torques on screws. Therefore, a material suitable for connectors or other parts in automotive manufacturing is not necessarily well-suited for use in a process of the type mentioned above for manufacturing a hollow cylindrical threaded component. This is also due to the totality of the aforementioned stress concentration factors that come into effect on the outer and inner contours of the hollow cylindrical component, particularly on a union nut. As mentioned, these stress concentration factors act at changes in diameter, circumferential edges, and / or radii, and contribute to the potential shearing off of a hexagon, preferably forming the assembly section, during tightening or loosening.

[0021] Calculating the dimensions of a metal screw-on part is relatively simple compared to determining the design of a mold for manufacturing a comparable part from plastic. The latter is considerably more difficult because – as already illustrated by the example of the connectors above – many additional parameters must be considered.

[0022] As already mentioned, the presence of the preferably metallic insert sleeve according to WO 2022 / 136406 A1 allows for sufficient consideration of the very high stress profiles encountered in practice. However, the molded part disclosed therein only offers a partial technical solution to the fundamental objective of reducing manufacturing costs by replacing metallic components, particularly those made of brass, with plastic. For example, any parts of a metallic insert sleeve that protrude from the base body are still prone to forming local electrical cells with the surroundings, which adversely promotes corrosion. Furthermore, the required separate manufacturing and precise placement of the preferably metallic insert sleeve in the injection mold increases manufacturing costs.

[0023] The present invention is therefore based on the objective of providing a technologically simple manufacturing process of the type mentioned above for a hollow cylindrical molded part with an annular cross-section, such as a nut, a socket part, a pipe plug, a pipe connector, a fluid adapter, a valve part or the like, wherein a high strength appropriate to the stress, in particular axial tensile strength, is ensured for the molded part even at elevated temperatures, and wherein premature failure – as described above – can be prevented without a complete geometric redesign and without the need for the use of inserts, in particular metallic inserts.

[0024] According to the invention, this problem is solved by the injection mold comprising four segments through which the cavity is formed during injection.

[0025] The injection mold can in particular include a head segment, through which the assembly section is formed during injection, furthermore two side segments, through which a thread-bearing section of the fastening section is formed during injection, and finally a foot segment, through which a foot area of ​​the fastening section is formed during injection.

[0026] An injection molding tool designed according to the invention advantageously ensures an optimal forming and demolding process as a basis for the formation of a molded part, which as a product of this process exhibits in particular high strength appropriate to the stresses, because the product properties can be selectively adjusted along the length of the molded part by means of the four segments of the injection molding tool, whereby the individual functions of the inner and outer sections of the molded part can be specifically taken into account by a corresponding segment design.

[0027] A core section for forming the inner channel of the base body can be formed on the head segment and / or the foot segment of the injection mold.

[0028] In particular, it can be provided that a core section, especially a cooled one, is formed on the head segment of the injection mold, which, during injection molding, extends into an area between the side segments of the injection mold. This allows the assembly section and virtually the entire inner contour of the molded part—that is, at least one sealing section inside the molded part for the subsequent arrangement of a circumferential seal to seal between the inner channel and a connector, and / or at least one support section for the subsequent support and / or guidance of the connector—to be formed without undercuts using only one segment of the injection mold, namely the head segment.

[0029] In a preferred embodiment of the method according to the invention, it can be provided that the injection of the polymer mass takes place through the head segment of the injection mold.

[0030] Furthermore, in a preferred embodiment of the inventive method, the injection of the polymer mass can take place at an angle of 20° to 70°, preferably 35° to 50°, to the longitudinal axis of the injection mold. In a particularly preferred embodiment of the inventive method, a needle valve nozzle can be used for injecting the polymer mass. This is a hot runner nozzle that allows direct injection. The molded part according to the invention can thus be advantageously produced entirely without gates. With the needle valve nozzle, after the injection of the fiber-containing polymer mass, the gate diameter is closed by a steel needle, and the injection residue is forced into the plastic part. The needle can be aligned precisely flush with the surface of the plastic part. Only a small, but still recognizable, round mark is visible on the part afterward.This can optionally be raised or slightly recessed relative to the surface. With so-called open hot runner nozzles, however, a small amount of injection residue always remains at the break-off point after injection, even if no feed channels are present. In any case, an injection point can also be identified by the fact that fibers in the solidified polymer mass—if present—are less ordered in the area of ​​the injection points than in other areas.

[0031] The use of a needle valve nozzle is particularly suitable for low-viscosity polymer melts, as it allows the plastic melt to pass through only during the injection process, which takes place under high injection pressure. When the injection cylinder is lifted, the melt is prevented from escaping the nozzle. The outlet opening, usually a bore in the nozzle tip, is sealed inside the nozzle by a shut-off needle, which is held under spring pressure in a cylindrical, pressure-tight guide. In another design, the pressure on the shut-off needle is applied hydraulically or pneumatically via levers outside the nozzle. Needle valve nozzles guarantee a clean, continuous injection molding process. The controlled closure prevents dripping of the plastic material. Likewise, disruptive stringing, which negatively impacts quality, is also prevented.Overall, a reliable and trouble-free process, as well as highly efficient production due to shorter cycle times compared to open nozzles, can be guaranteed.

[0032] In the case of the presence of a cooling system, in particular a cooling element, and a needle valve nozzle in or on the head segment, the distance between the cooling element and the needle nozzle can be only a few tenths of millimeters to a few millimeters.

[0033] When injecting the polymer mass, preferably with only a single, and especially obliquely angled, nozzle into the mold, the mass flow can cause an air bubble to form in the area on the side opposite the nozzle, preventing the cavity, particularly in the head segment, from being completely filled. To prevent this, a vent can preferably be arranged in this critical area, particularly in the form of an axially movable slide that allows the air to escape during injection.

[0034] Even with just one injection point, a homogeneous distribution of the polymer mass can be achieved within the base body. In particular, no multiple weld lines form in the polymer material of the base body during manufacturing, which could later represent weak points.

[0035] Regarding the composition of the fiber-containing plasticized thermoplastic polymer mass, it is particularly advantageous if the thermoplastic polymer is one which, in the non-plasticized state, exhibits a tensile strength according to ISO 527-2:2012 (test speed: 5 mm / min) of at least 260 MPa, particularly at least 280 MPa, and most preferably at least 300 MPa. Such polymers are, in particular, polyarylamides (PARA), such as those that can be described, for example, by the following chemical formula:

[0036] Therefore, due to the presence of ring-shaped aryl constituents in the molecule, it is in particular a semi-aromatic - and also partially crystalline - polyamide.

[0037] With PARA, which, for example, has a mass fraction of 50% glass fibers – flat glass fibers are particularly well-suited for the production of a union nut as a preferred molded part with a hollow cylindrical body – a tensile strength of approximately 300 MPa (breaking strength according to ISO 527-2:2012 at a test speed of 5 mm / min), similar to the strength of aluminum, can advantageously be achieved. PARA with 50% glass fibers thus has a strength approximately 40% higher than PA 6.6 and is stable up to at least 120 °C, with comparatively low water absorption. Flat glass fibers result in particularly excellent strength properties at an angle of 90° to the flow direction during injection molding.

[0038] In the design of the relief groove, it is particularly advantageous if its contour, i.e., the transition from the fastening section to the assembly section, is shaped according to a so-called tree root geometry. The design is carried out using the well-known "thrust triangle method," preferably with additional rounding, as detailed below.

[0039] Finally, in an advantageous embodiment of the method according to the invention, a strip-shaped flattening of the thread extending axially along its length can be provided, particularly in the area of ​​a joint between the two side segments preferably made of injection-molded thermoplastic polymeric material, so that any burr formed during injection molding lies within this flattening. This minimizes axial stress components occurring during the assembly of the molded part produced according to the invention in the base body, and also largely avoids significant frictional forces during screwing in or out.

[0040] The flattening does not have a significant negative impact on the load-bearing capacity of the thread, especially when using glass fiber reinforced PARA.

[0041] Furthermore, the hollow cylindrical molded part according to the invention can be conditioned, whereby conditioning is understood to mean the controlled absorption of moisture in plastics. The moisture absorption of the individual plastics varies considerably. Non-polar plastics such as polyolefins, styrene polymers, and fluoropolymers absorb very little moisture. Polar plastics such as polyurethane (PUR) or cellulose esters, on the other hand, absorb more water.

[0042] Polyamides – also known as polyarylamides (PARA) – can be conditioned well with only comparatively low water absorption. For example, the base body of a molded part according to the invention, made from polyarylamide, can have a maximum water absorption of 3.7% in the saturated state at 23 °C, as determined according to ISO 62. However, it is not conditioned to its maximum water absorption capacity, but only until an equilibrium with the environment is reached. Once this state is reached, it remains almost constant in the European climate. Even with an initial maximum water absorption, for example by immersion in water, the base body loses moisture again as soon as it is removed from the water until an equilibrium is reached. This does reduce the strength to some extent, e.g.,The tensile strength and flexural strength are maintained, while preventing potential subsequent deterioration of properties during long-term operation under environmental influences. Other properties, such as the modulus of elasticity, toughness, and the friction and wear properties—particularly important for the thread of the hollow cylindrical component according to the invention—remain constant or are even positively influenced. Conditioning can also reduce the loss of preload force after assembly.

[0043] A further advantage of the manufacturing process according to the invention is that only a single injection point for the inner channel of the screw part to be produced is arranged at the end of the mold and angled such that the polymer mass is injected into the closed mold at an acute angle to the inner channel. Such angled injection advantageously offers the benefit that more free space is available for the core part in the area of ​​the inner channel, which is formed by a core part that can be inserted perpendicularly in the insertion direction, in particular by a core section of the head segment. This design also makes it possible, in particular, to actively cool the corresponding core part of the mold by means of core cooling. Core cooling advantageously increases the production speed and extends the service life of the mold, especially of the head segment.

[0044] Further advantageous features of the invention are contained in the dependent claims and in the following description.

[0045] The invention will be explained in more detail below using a preferred embodiment. Figures 1 to 3 each show a longitudinal section through an exemplary embodiment of an injection mold for implementing the method according to the invention in various manufacturing phases.

[0046] Fig. 4 shows a top view of an exemplary embodiment of a hollow cylindrical molded part produced according to the invention.

[0047] Fig. 5 shows a section through the molded part produced according to the invention as shown in Fig. 4, along line 11-11 in Fig. 4.

[0048] Fig. 6 shows a perspective view of the molded part produced according to the invention from Figs. 4 and 5,

[0049] Fig. 7 shows a schematic representation of the preferred construction of a transition from a fastening section to an assembly section of a molded part manufactured according to the invention.

[0050] Fig. 8 shows a longitudinal section through a molded part produced according to the invention, in the assembled state with a plug part,

[0051] Fig. 9 shows a longitudinal section through another exemplary embodiment of an injection mold for realizing the method according to the invention in a manufacturing phase as shown in Fig. 3.

[0052] Fig. 10 in a representation as in Fig. 8, a longitudinal section through a further embodiment of a molded part produced according to the invention, in the assembled state with a plug part, Fig. 11 a perspective view of the further embodiment of the molded part produced according to the invention from Fig. 10.

[0053] Regarding the following description, it is expressly emphasized that the invention is not limited to the exemplary embodiments and not to all or several features of the described combinations of features; rather, each individual partial feature of the exemplary embodiment(s) can have an inventive significance independently of all other partial features described in connection with it, both on its own and in combination with any features of another exemplary embodiment.

[0054] In the various figures of the drawing, identical parts are always provided with the same reference symbols, so that they are usually only described once.

[0055] As can be seen from Figures 1 to 3, which – as mentioned – show an exemplary embodiment of an injection mold 100 for realizing the inventive method in various manufacturing phases (Figure 1: injection molding, Figures 2 and 3: demolding), a hollow cylindrical molded part 1 with an annular cross-section, such as a screw, a nut, a socket part, a pipe plug, a pipe connector, a fluid adapter, a valve part or the like, can be produced by such a method.

[0056] Figures 1 to 3, but in enlarged form, and in detail also Figures 4, 5, 6 and 8 show embodiments of a molded part 1 that can be produced according to the invention, which – as is particularly illustrated by the view in Figure 4 – has an annular cross-section. Specifically, the molded part 1 is a hollow screw that is produced according to the injection molding process of the invention.

[0057] As can be clearly seen in Figures 1 to 3, the injection mold 100 comprises four segments S1, S2, S3, and S4, which form the cavity during injection. The injection mold 100 includes a head segment S1, by means of which an assembly section MA of the molded part 1 is formed during injection. Furthermore, the injection mold 100 comprises two semi-shell-shaped side segments S2 and S3, forming a hollow cylinder, by which a threaded section of a mounting section BA is formed during injection. Finally, the injection mold 100 includes a base segment S4, by which a base area of ​​the mounting section BA is formed during injection.

[0058] A core section KA1, KA2 for forming an inner channel 3 of a base body 2 can preferably be formed on the head segment S1 and / or on the foot segment S4 of the injection mold 100. In particular, it can be provided that a cooled core section KA1 is formed on the head segment S1 of the injection mold 100, which, during injection molding, plunges into an area between the side segments S2, S3 of the injection mold 100.

[0059] A needle valve nozzle 110 can preferably be used for injecting the polymer mass M, which is advantageous in terms of its details and its

[0060] The advantages of the I-component have already been explained above. The injection of the polymer mass M preferably takes place through the head segment S1 of the injection mold 100.

[0061] As has already been explained, it is advantageous if - as shown in Fig. 1 - the injection of the polymer mass M takes place at an acute angle p in the range of 20° to 70°, in particular in the range of 35° to 50°, to the longitudinal axis XX of the injection mold 100.

[0062] To prevent voids from remaining in the molded part 1, it is advantageous to arrange a vent 120 in the head segment S1, in particular an axially movable slide arranged in a channel, which allows air to escape from the cavity during the injection of the polymer mass M. Such a vent 120 is also shown in Figures 1 to 3.

[0063] To carry out the actual injection molding process, all segments S1, S2, S3, S4 are brought together to form the cavity for the molded part 1, as shown in Fig. 1, after which the injection of the mass M takes place.

[0064] After the mass has solidified, prior to which a holding pressure may be applied, the head segment S1 of the injection mold 100 remains stationary. The remaining segments are lowered in the axial direction XX, as shown in Fig. 2. In particular, this exposes the assembly section MA of the molded part 1.

[0065] Finally, the two side segments S2 and S3, which form the thread-bearing section of the fastening section BA, are moved radially outwards to the positions shown in Fig. 3. The molded part 1 remains, in particular freestanding, on the base segment S4 and can be gripped there manually or mechanically and removed from the injection mold.

[0066] The molded part 1 produced according to the invention has a hollow cylindrical base body 2 with a mounting section MA and a fastening section BA adjacent to it in the axial direction X-X, wherein, in an inner channel 3 of the base body 2, which is intended in particular – as illustrated especially in Fig. 8 – for the sealing reception of a connector part 4, sections with different functions, not further specified in detail, are arranged one another in the axial direction XX, and wherein the base body 2 has at least one internal thread and / or – as shown – an external thread 10 in the fastening section BA. The molded part 1 according to the invention can be screwed to another component via this external thread 10 in a manner not shown in the figures. In the illustrated embodiment, the mounting section MA is designed as a hexagonal flange for possible tool engagement.

[0067] A transition area from the assembly section MA to the axially adjacent fastening section BA XX is called a relief groove and is symbolized in the drawing by the reference numeral FS. A circumferential seal 11 can be arranged in the relief groove FS – see Fig. 8.

[0068] The sections in the inner channel 3 can serve to accommodate one or more circumferential seals 5, 6, which may be located particularly on the connector part 4, as well as for the direct or indirect retention and / or locking of the connector part 4 and / or, in a conical or cylindrical form, for supporting and / or guiding the connector part 4, whereby they may have different inner diameters. It should also be noted that the inner channel 3 may taper in the insertion direction S of the connector part 4, particularly in a stepped or continuous manner, whereby the inner diameter remains constant in at least some sections. Thus, with an approximately constant outer diameter in the axial direction XX, different wall thicknesses preferably result.

[0069] To produce a molded part 1 according to the invention, a plasticized polymer mass M containing fibers F is injected through at least one injection opening of the mold 100 into a cavity of the mold 100 (Fig. 1), and after the polymer mass has solidified, the molded part 1 is demolded from the mold (Figs. 2 and 3). The fact that the base body 2 is thus produced from a plasticized thermoplastic polymer mass containing fibers F by injection molding is visualized by the breakout in Fig. 5.

[0070] Preferably, the thermoplastic polymer of the fiber-containing thermoplastic polymer mass M is one that, in its unplasticized state, exhibits a tensile strength according to ISO 527-2:2012 (test speed: 5 mm / min) of at least 260 MPa. In particular, the polymer of the fiber-containing thermoplastic polymer mass M can be one that, in its unplasticized state, exhibits a tensile strength according to ISO 527-2:2012 (test speed: 5 mm / min) of at least 280 MPa, preferably 300 MPa.

[0071] In particular, the polymer of the fiber-containing thermoplastic polymer mass M can be a polyarylamide (PARA). Polyarylamide (PARA) can be produced by polycondensation of an aromatic diamine and an aliphatic diacid, in particular by polycondensation of an aliphatic diacid with 3 to 12 carbon atoms, such as adipic acid, and an aromatic diamine, such as xylenediamine, and in particular metaxylenediamine, whereby the polymer of the fiber-containing thermoplastic polymer mass M is in particular a partially aromatic and / or partially crystalline plastic.

[0072] A semi-aromatic polyarylamide is a polyamide-type polymer that contains aromatic groups along the polymer chain, as expressed by the chemical formula given above.

[0073] Semicrystalline polymers comprise a crystalline phase, which corresponds to zones within the solidified polymer matrix where the macromolecules are arranged regularly in space. A second phase is characterized by a disordered (amorphous) arrangement of the macromolecules. This partial crystallinity is advantageous for optimally absorbing multiaxial stress states, for example, in the area of ​​the undercut FS under the influence of a turning or twisting torque. Fiber-reinforced plastics with a thermoplastic matrix can be subsequently formed or welded. After cooling, the molded parts are ready for use, but soften at elevated temperatures. Their tendency to creep decreases with increasing fiber content. The advantage of PARA lies particularly in its high matrix strength and suitability for use under elevated temperature loads.

[0074] According to the invention, amorphous fibers F, such as glass fibers, anisotropic fibers F, such as carbon fibers, and / or aramide fibers can be used as fibers F.

[0075] For amorphous fibers, the advantage of the fiber shape lies almost exclusively in the utilization of the size effect. The elastic modulus of the compact material and the elastic modulus of the fiber are approximately the same, although the general aim should be for the fibers to exhibit a higher elastic modulus and tensile strength in their longitudinal direction than the solidified polymer mass. The elongation at break of the matrix should also be higher than that of the fibers. However, amorphous fibers drawn from the melt have the advantage that compressive residual stresses develop on their surface during cooling, which can prevent the formation of cracks in the fiber.

[0076] Anisotropic fibers F, particularly carbon fibers, are used when high strength and stiffness per unit mass are required. Carbon fibers, which typically have a diameter of about 5 to 8 pm and are now predominantly made of polyacrylonitrile I, exhibit significantly higher strength and stiffness in the fiber direction than perpendicular to the fiber direction. Their key characteristic is high tensile strength. The use of commercially available flat fibers is also possible. According to the invention, aramid fibers can also be used as fibers F. Aramids, or aromatic polyamides, are defined by the US Federal Trade Commission as long-chain synthetic polyamides in which at least 85 percent of the amide groups are directly bonded to two aromatic rings.This is therefore a similar or identical material to that preferably used for the thermoplastic matrix within the scope of the invention. Aramid fibers, like carbon fibers, have a negative coefficient of thermal expansion, meaning they shorten when heated. Their specific strength and modulus of elasticity are lower than those of carbon fibers. However, in combination with the positive coefficient of thermal expansion of the matrix material, highly dimensionally accurate molded parts 1 can be manufactured. Compared to molded parts 1 containing carbon fibers, the compressive strength of such molded parts 1 is lower, and a potentially similar melting point for the fibers and matrix could also prove problematic.

[0077] The plasticized polymer mass can contain a volume fraction of fibers F in the range of 2.5 to 75 percent, preferably a mass fraction in the range of 30 to 70 percent, particularly 50, 60, or 65 percent by mass, preferably glass fibers, and especially preferably flat glass fibers. The filler content further increases the strength, particularly the tensile strength according to ISO 527-2:2012, compared to the unfilled polymer.

[0078] The fibers F, particularly in the form of glass fibers, preferably flat glass fibers, can have a length in the range of 0.1 mm to 10 mm, preferably in the range of 0.2 mm to 0.5 mm. The fibers F can have a mean diameter in the range of approximately 3 pm to 35 pm, preferably in the range of 5 pm to 20 pm. Flat glass fibers have an approximately elliptical cross-section (rounded rectangles) and thus possess a major and a minor semi-axis. As a first approximation, the mean diameter can be considered to be half the value of the sum of the two semi-axes.

[0079] The approximately rectangular cross-sectional shape of flat glass fibers promotes optimal fiber distribution in the injection mold 100 during injection molding, and subsequently optimal fiber orientation in the molded part 1, whereby the fibers F in the base body can align themselves predominantly parallel to the axial direction XX. A flat glass fiber is defined, in particular, as one whose wide side 1 in cross-section is 1.5 to 3 times larger than its narrow side. An equivalent mean diameter of the fiber F can be easily calculated by dividing the circumference of the cross-section by π.

[0080] Examples of fiber-reinforced aramid materials include the commercially available materials AKROLOY® PARA GF 50 HU black (8596) and AKROLOY® PARA FGF 50 1 black (8186), both of which are polyarylamides reinforced with 50% glass fiber by mass. Even in their conditioned state, these materials offer very high strength due to their low moisture absorption. Furthermore, these materials are distinguished by their excellent flowability during processing and their high surface quality in the finished product. In the latter material, the PARA is reinforced with flat glass fibers, which further improves the flow properties during injection molding.

[0081] Key properties of AKROLOY® PARA GF 50 HU black (8596) are shown in Tables 1 to 3 below, categorized by general properties (Table 1), mechanical properties (Table 2), and thermal properties (Table 3). For the ISO standards listed in the tables for determining the respective parameters, the versions applicable at the time of filing must be observed. For tensile strength and elongation at break, this is version ISO 527-2:2012.

[0082] Table 1: General properties

[0083] Table 2: Mechanical properties Table 3: Thermal properties

[0084] The parameters of AKROLOY® PARA FGF 50 1 differ only slightly from those of AKROLOY® PARA GF 50 HU black (8596). In particular, the tensile strength (see Table 2) in the dry state (ISO 527-2:2012 / test speed: 5 mm / min) is completely identical for both materials and is 295 MPa. Conditioning, whereby the maximum water absorption in the saturated state at 23 °C, determined according to ISO 62, can be as low as 3.5% (see Table 1), advantageously results in a strength reduction of no more than 11% for both materials. The melting point according to ISO 11357-3 (DSC, 10 K / min), which can be found in Table 3, makes both materials ideal for processing the plasticized thermoplastic polymer mass, especially in the temperature range of approximately 270 °C to 300 °C.

[0085] Polyarylamides (PARA) also form a very smooth surface during injection molding, which is particularly advantageous from the perspective that frictional forces in the thread 10 can be minimized when screwing in or out the hollow cylindrical molded part 1 produced according to the invention. According to the invention, especially when using PARA as the plastic in the plasticized thermoplastic polymer mass M containing the fibers F produced by injection molding, the thread 10 is capable of bearing the axial forces acting on the thread teeth, particularly shear forces, during tightening or loosening.

[0086] For high component stability, it has proven advantageous if the injection into the cavity is carried out in such a way—for example, near the end faces of the molded part 1—that the fibers F in the base body 2 align themselves favorably for the torsional stress that later occurs when screwing in the part using a screwing tool 100. This can be verified, for example, by computed tomography X-ray analysis. It should be noted that while the tool does apply a torsional moment during the aforementioned stress, the forces occurring in the thread of the screw part 1 during screwing in also generate axial mechanical stresses, resulting in a triaxial stress state with high axial forces in the area of ​​maximum load near the point of force application.

[0087] The perspective view of the molded part 1 produced according to the invention shown in Fig. 6 illustrates an advantageous embodiment of the invention, in which, particularly in the area of ​​a joint between two side segments S2, S3 used for injection molding the plasticized thermoplastic polymer mass containing the fibers F, a strip-shaped flattening 12 extending axially along the length of the thread 10 is provided, so that any burr formed during injection molding lies in this flattening 12. This minimizes axial stress components occurring during the assembly of the molded part 1 according to the invention in the base body 2, and also largely avoids significant frictional forces during screwing in or out.

[0088] Fig. 7 illustrates a previously mentioned construction, preferably used within the scope of the invention, for obtaining a so-called tree root geometry for the undercut FS. The construction is carried out—not, as is also known, by means of a circular arc segment, in particular a quarter-circle segment—in the following manner: First, in a first step, a construction line “a” is created, which is always at a construction angle |JK to the mounting section MA, wherein the angle |JK can be in particular in the range between 30° and 60°, preferably at 45°. In the second step, a construction line “b” is created, which originates from the center of the hypotenuse of the triangle formed in the first step. This construction line “b” is led either to the mounting section MA or to the fastening section BA in such a way that another triangle is formed.In the third step, a construction line "c" is generated, originating from the midpoint of the hypotenuse of the triangle formed in the second step. Here, another isosceles triangle is created, as shown in Fig. 7. This construction method is known per se and is called the "method of draw triangles." In a final fourth step, the endpoints EP and FP of construction lines "c" and "a" are connected by an arc. This arc approximately rounds the polygonal structure formed in the first three steps and then forms the contour of the undercut FS. Several circular arcs, tangentially intersecting each other, can be used for this purpose. Radii corresponding to such circular arcs are labeled R1, R2, R3, and R4 in Fig. 7.Likewise, the design is not limited to three construction lines, but any further number can be added, preferably depending on the angle PK. By means of such a contour, which reduces notch stresses, the torsional moment that the molded part 1 produced according to the invention can withstand when screwed into the component is advantageously increased by up to approximately 20 percent compared to a component with the conventional simple circular arc shape.

[0089] The cavity of the injection mold 100 is to be designed in a complementary manner to form this contour of the undercut FS, whereby this complementary contour - as shown in Figs. 1 to 3 - can be formed in particular on the (upper) side of the two side segments S2, S3, which rests against the head segment S1 during the injection molding process.

[0090] Figure 8 shows a molded part 1 produced according to the invention, with identical inner and outer diameters (not specified) and length L, together with a mounted connector 4. Advantageously, a feature according to WO 2022 / 136406 A1 can be omitted, according to which a preferably metallic insert sleeve is arranged coaxially to the inner channel of the known injection-molded base body. With technologically simplified manufacturing, the molded part 1 produced according to the invention can also maintain high stress-appropriate strength, in particular axial tensile strength, even at elevated temperatures, and premature failure can be prevented.

[0091] A possible design of the base body 2 within the framework of the inventive method, using a plasticized thermoplastic polymeric mass M containing fibers F, in which the polymer exhibits a tensile strength according to ISO 527-2:2012 (test speed: 5 mm / min) of at least 260 MPa in the unplasticized state, allows for a reduction in the length LB of the fastening section BA compared to the known design. This, in turn, enables a displacement of the inner contour in the opposite direction of insertion, such that an extended, for example conical, diameter region of the inner contour, which in a non-inventive molded part lies in the area of ​​the transition from the fastening section to the assembly section, can be displaced into the assembly section MA of the base body 2. It thereby reaches, in particular, the area of ​​the flange-like hexagon of the exemplary capping part.The wall thickness in the area of ​​the undercut FS is thus increased compared to the known molded part, so that a torsional moment and notch factors usually applied for assembly and disassembly can no longer act in such a way that tearing in the area of ​​the undercut FS is possible.

[0092] While maintaining the overall axial length L of the molded part, shortening the fastening section BA can be accompanied by lengthening the assembly section MA. Characteristically, fastening sections BA produced according to the inventive method are preferably shorter than conventional fastening sections not produced according to the invention, and the assembly sections MA preferably produced according to the invention are longer than is known from the prior art.

[0093] While for a known molded part, for example, the ratio of the length of the fastening section to the total axial length is in the range of 60% to 80%, preferably about 65%, for a molded part 1 produced according to the invention, the ratio of the length LB of the fastening section BA to the total length L (sum of LB and LM as the length of the mounting section MA) is preferably in the range of only 38% to 57%, preferably about 54%.

[0094] Fig. 10 shows – as already mentioned – in a representation similar to Fig. 8, a longitudinal section through a further embodiment of a molded part 1 produced according to the invention, in the assembled state with a plug part 4, and inserted together with this into a connecting bore of a further component 20 which carries an internal thread 22. The molded part 1 (shown in perspective in Fig. 11), a union screw, is produced according to a variant of the method according to the invention, which is illustrated by Fig. 9.

[0095] In contrast to the embodiment in Fig. 8, where the inner channel 3 tapers in the insertion direction S of the plug part 4, in particular in a stepped or continuous manner, with the inner diameter remaining constant in at least some sections, the inner channel 3 of the molded part 1 according to Fig. 10 has a constant inner diameter over almost its entire length, which, however, does not detract from the fact that in the inner channel 3 intended for the sealing reception of a plug part 4, XX sections with different functions are arranged next to each other in the axial direction.

[0096] Starting from the insertion side of the molded part 1 for the connector part 4, the first section features a recess, specifically designed as a continuous taper (inclined surface SF1 in Figs. 10 and 11), for visual inspection to ensure correct insertion. This section is followed by the sealing area for the dirt seal 6. Unlike Fig. 8, Fig. 10 does not show any of the seals 5, 6, and 11 themselves; however, the corresponding groove 6A for receiving the dirt seal 6 is clearly visible. A relatively short support area for the connector part 4 follows, and then another section serves as a further sealing area, specifically for the media seal 5. Again, only the corresponding receiving groove 5A is shown. Finally, a relatively long support area for the shaft of the connector part 4 completes the assembly.The sealing areas and the support areas are preferably designed with the same diameter. The two support areas can also be considered as a single support area, interrupted only by the sealing area for the media seal 5.

[0097] The sealing position 11 A for the circumferential seal 11 is located on the outer diameter of the molded part 1 in the area of ​​the undercut FS.

[0098] To assemble the connection shown in Fig. 10, a spring element 30 is first inserted into the connecting bore of the further component 20 – specifically, below the base of a mating thread 22 for the thread 10 of the molded part 1. Next, a retaining clip 8A is inserted, which is an alternative to the locking cage 8 shown in Fig. 8. The retaining clip 8A is inserted so that it lies flat against the base of the mating thread 22. The spring element 30 and the retaining clip 8A are annular and symmetrical. Subsequently, the molded part 1, designed as a union nut and on which a greased O-ring has already been pre-mounted as a circumferential seal 11 at the sealing surface 11A, is screwed into the threaded bore and tightened. A design in the area of ​​the undercut FS, as described above, ensures optimal stress distribution in the base body 2 when the torsional moment is applied, particularly stress-free stress concentrations.

[0099] Finally, the connector part 4 is inserted. Unlike the embodiment in Fig. 8, an outer ring bead 7 for interaction with the retaining clip 8A is not provided on the base body 2 of the molded part 1. Instead, the retaining clip 8A engages below the molded part 1 in a circumferential groove on the outer diameter of the connector part 4, with the tip of the connector part 4 bearing against or in the spring element 30, as shown in Fig. 10.

[0100] The correct execution of the mating process is typically checked by inserting a test fork under a circumferential collar 41 on the connector part 4, which is typically present and dimensioned as standard, and then attempting to pull the connector part 4 out of the molded part 1 using the test fork. However, with molded parts 1 made of plastic, a fork test may fail due to insufficient clearance between the collar 41 on the connector part 4 and the assembly section MA of the molded part 1. In any case, a visual inspection must be carried out as follows: If the dirt sealing ring 6, which is preferably in a warning color such as red, is visible because it is positioned above the molded part 1, the mating process has not been executed correctly.

[0101] In comparison to known brass coupling parts, the length LM of the assembly section MA of a plastic molded part 1 manufactured according to the invention is greater, specifically the head / hexagon is taller. This length LM is one of the few dimensions of the molded part 1 that can be modified to a limited extent, while the geometry of the plug part 4 must not be altered. As a result, compared to a brass part in the plug connection 4 / 1, the axial distance between the circumferential collar 41 on the plug part 4 and the end face of the molded part 1 facing the plug part 4 is reduced. This can lead to the dirt sealing ring 6 not being visible even when the plug part 4 is not fully inserted, because it is covered by the collar 41, making the use of a test fork impossible.

[0102] The recess, designed as a circumferential taper – inclined surface SF1 in Figures 10 and 11 – offers a technical solution to this problem. If the connector is not inserted correctly, the sealing ring 6 can be seen. However, the conical recess should be designed within a specific angular range (pi in Figure 11). If the angle pi is too steep, and therefore too deep, the dirt sealing ring 6 will still be in the recess even if the connector part 4 is not inserted correctly, and the installer may not be able to see into the recess because it will be obscured by the collar 41 on the connector part 4. If the recess is too shallow, the dirt sealing ring 6 may protrude even if the connector is inserted correctly, or the recess may extend so close to the outer diameter of the mounting section MA that the stability gained by the additional height of the mounting section MA compared to a brass part is lost.

[0103] From this perspective, the angle pi between the inclined surface SF1 and the longitudinal axis XX (Fig. 11) should be in the range between 30° and 70°, preferably at 60°. An annular rim RR remaining next to the inclined surface SF1 should have a radial width BR that is not less than half the radial width BF of the entire end face of the base body of the molded part 1, i.e., the sum of the area of ​​the annular rim RR and the area of ​​the axial projection of the inclined surface SF1.

[0104] To further improve the visibility of the dirt ring seal 6 required for visualizing the plug-in state, a second inclined surface SF2 can optionally be provided, particularly as a partial surface of the aforementioned inclined surface SF1, which is then to be referred to as the first inclined surface, and which is at an angle p2 between the inclined surface SF2 and the longitudinal axis XX (Fig.

[0105] 11) is arranged in the range between 25° and 35°, preferably at 30°. The conical recess is then a double cone.

[0106] The inclined surface(s) SF1 - and optionally SF2 - of the molded part 1 can be easily generated during injection molding in accordance with the inventive method by means of a complementary conical contour CK on the core section KA1 of the head segment S1 (Fig. 9) of the injection molding tool 100.

[0107] The invention is not limited to the illustrated embodiments, but also includes all embodiments that have the same effect in the sense of the invention, for example those with an internal thread in the inner channel 3.

[0108] Furthermore, the person skilled in the art may provide additional advantageous technical measures without departing from the scope of the invention. For example, in the illustrated embodiment, a particularly delicate outer ring bead 7 is located in a terminal retaining section on the outer circumference of the base body 2. A preferably annular locking cage 8, shown in Fig. 8, can be attached, in particular snapped onto this bead for the indirect retention and / or locking of the connector part 4. This locking cage interacts with at least one locking element 9 on the connector part 4. This indirect retention and / or locking can be implemented in various ways; for details, reference is made in full to EP 0 913618 B1.

[0109] The outer ring bead 7 located on the outer circumference of the base body 2, which - as Fig. 1 shows - can be formed by the interaction of the two side segments S2, S3 with the core section KA2 of the base segment S4, makes it advantageously possible to keep the injection-molded part 1 stable in the demolding phase shown in Fig. 3.

[0110] The invention is not limited to the combinations of features defined in independent claims 1 and 18, but can also be defined by any other combination of specific features from all disclosed individual features. This means that, in principle, virtually any individual feature of the independent claims can be omitted or replaced by at least one individual feature disclosed elsewhere in the application. Therefore, the claims should be understood merely as a first attempt at formulating the invention.

[0111] In particular, it can be summarized that, advantageously, in a plug connection with a hollow cylindrical molded part 1 produced according to the invention, the following values ​​commonly used in practice do not need to be changed:

[0112] geometry

[0113] - Thread diameter and pitch;

[0114] - Maximum length of the plug-in system in the inner channel;

[0115] - Flow cross-sections of recorded plug parts.

[0116] Forces and Moments

[0117] - For example, for thread M 22 x 1.5: breaking torque approx. 30 Nm (double safety factor with a tightening torque of 14 - 15 Nm); - For example, for thread M 16x1.5: breaking torque approx. 20 Nm (double safety factor with a tightening torque of 10 Nm).

[0118] Reference symbol list

[0119] 1 molded part

[0120] 2 basic shapes of 1

[0121] 3 inner channel of 1

[0122] 4 connector part

[0123] 5 Perimeter seal at 4, media seal

[0124] 5A Nut for 5 (Fig. 10)

[0125] 6 Perimeter seal on 4, dirt seal

[0126] 6A Nut for 6 (Fig. 10)

[0127] 7 Outer ring bead at 2

[0128] 8 locking cages for 4

[0129] 8A Retaining clip for 4 (Fig. 10)

[0130] 9 locking element of 4

[0131] 10 threads from 1

[0132] 11 Perimeter seal in FS

[0133] 11A Sealing space for 11 (Fig. 10)

[0134] 12 Flattening of 10

[0135] 20 Component with connection hole

[0136] 22 internal threads in 20, mating threads to 10

[0137] 30 spring element

[0138] 41 Circumferential band at 4 (Fig. 10)

[0139] 100 injection molds

[0140] 110 needle valve nozzle out of 100

[0141] 120 vents of 100 a, b, c construction lines (Fig. 7)

[0142] BA fastening section of 1 with 10

[0143] BF radial total width frontal area of ​​1

[0144] BR radial width of RR

[0145] CK cone contour on KA1 (Fig. 9)

[0146] EP Endpoint of c (Fig. 7)

[0147] F fibers in M

[0148] FP Endpoint of a (Fig. 7)

[0149] FS free stitch from 2

[0150] KA1 Core section of S1

[0151] KA2 core section of S4

[0152] L Length of 1

[0153] LB length of BA

[0154] LM length of MA

[0155] M polymer mass

[0156] MA assembly section of 1

[0157] R1, R2, R3, R4 radii (Fig. 7)

[0158] RR Ring edge of the front surface of 1

[0159] S1 head segment of 100

[0160] S2, S3 page segments of 100

[0161] S4 foot segment of 100

[0162] SF1 first inclined surface in MA

[0163] SF2 second inclined surface in MA

[0164] XX Longitudinal axis of 1, 4, 20 p Injection angle pi Angle between SF1 and XX (Fig. 11)

[0165] P2 Angle between SF2 and XX (Fig. 11)

[0166] PK construction angle (Fig. 7)

Claims

Claims 1. Method for manufacturing a hollow cylindrical component (1) with an annular cross-section, such as a screw, a nut, a socket, a pipe connector, a pipe fitting, a fluid adapter, a valve part or the like, wherein the component (1) has a hollow cylindrical base body (2) with an assembly section (MA) and with a fastening section (BA) adjoining it in the axial direction (XX), wherein, in particular, sections with different functions are arranged in an axial direction in an inner channel (3) of the base body (2) intended for the sealing reception of a connector part (4), and wherein the base body (2) has at least one internal thread and / or one external thread (10) and is manufactured by injection molding a plasticized thermoplastic polymeric mass (M) containing fibers (F), wherein the injection into the cavity is carried out through at least one injection port of an injection mold (100),wherein the plasticized thermoplastic polymeric mass (M) containing the fibers (F) flows in a ring-shaped manner around an inner core of the injection mold (100), and wherein the fibers (F) align themselves during injection and cavity filling, characterized in that the injection mold (100) comprises four segments (S1, S2, S3, S4) by which the cavity is formed during injection.

2. Method according to claim 1, characterized in that the injection molding tool (100) comprises a head segment (S1) by means of which the assembly section (MA) is formed during injection.

3. Method according to claim 1 or 2, characterized in that the injection molding tool (100) comprises two side segments (S2, S3) which, during injection, form a thread-bearing section of the fastening section (BA).

4. Method according to one of claims 1 to 3, characterized in that the injection molding tool (100) comprises a foot segment (S4) by which a foot area of ​​the fastening section (BA) is formed during injection.

5. Method according to one of claims 1 to 4, characterized in that a core section (KA1 , KA2) for forming the inner channel (3) of the base body (2) is formed on one / the head segment (S1 ) and / or on one / the foot segment (S4) of the injection molding tool (100).

6. Method according to claim 5, characterized in that a conical contour (CK) for forming a depression with an inclined surface (SF1) circumferentially surrounding the end face in the base body (2) is formed on the core section (KA1) of the head segment (S1) of the injection molding tool (100).

7. Method according to claim 6, characterized in that the cone contour (CK) in the base body (2) forms a recess designed as a double cone with two inclined surfaces (SF1 , SF2) circumferentially on the end face.

8. Method according to one of the preceding claims, characterized in that a cooled core section (KA1) is formed on a / the head segment (S1) of the injection molding tool (100), which dips into an area between the side segments (S2, S3) of the injection molding tool (100) during injection molding.

9. Method according to one of the preceding claims, characterized in that a needle valve nozzle (110) is used for injecting the polymeric mass (M).

10. Method according to one of the preceding claims, characterized in that the injection of the polymeric mass (M) takes place at an angle (p) in the range of 20° to 70°, in particular in the range of 35° to 50°, to the longitudinal axis (XX) of the injection mold (100).

11. Method according to one of the preceding claims, characterized in that the injection of the polymeric mass (M) is carried out through a / the head segment (S1 ) of the injection molding tool (100).

12. Method according to one of the preceding claims, characterized in that a vent (120) is arranged in the head segment (S1), in particular an axially movable slide arranged in a channel, which causes air to escape from the cavity during the injection of the polymer mass (M).

13. Method according to any one of claims 1 to 12, characterized in that the polymer of the plasticized thermoplastic polymeric mass (M) containing fibers (F) is a semi-aromatic and / or semi-crystalline plastic and in particular is such a polymer which, in the non-plasticized state, exhibits a tensile strength according to ISO 527-2:2012 (test speed: 5 mm / min) of at least 260 MPa, preferably 280 MPa, particularly preferably 300 MPa.

14. Method according to any one of claims 1 to 13, characterized in that the polymer of the plasticized thermoplastic polymeric mass containing fibers (F) is a polyarylamide (PARA), wherein preferably the polyarylamide (PARA) is a polycondensate of an aromatic diamine and an aliphatic diacid, in particular a polycondensate of an aliphatic diacid having 3 to 12 carbon atoms, such as adipic acid, and an aromatic diamine, such as xylenediamine, and in particular metaxylenediamine.

15. Method according to any one of claims 1 to 14, characterized in that the plasticized polymer mass contains a volume fraction of fibers (F) in the range of 2.5 to 75 percent, preferably a mass fraction in the range of 30 to 70 percent, in particular 50, 60 or 65 percent by mass, of glass fibers, preferably in an embodiment as flat glass fibers, wherein the fibers (F), in particular in an embodiment as glass fibers, preferably in an embodiment as flat glass fibers, have a length in the range of 0.1 mm to 10 mm, preferably in the range of 0.2 mm to 0.5 mm, wherein the fibers (F) in particular have a mean diameter in the range of about 3 pm to 35 pm, preferably in the range of 5 pm to 20 pm.

16. Method according to one of claims 1 to 15, characterized in that the base body (2) of the hollow cylindrical molded part (1 ) is conditioned after demolding from the injection molding tool (100), wherein the base body (2) has a maximum water absorption of 3.7% in the saturated state at 23 °C as determined according to ISO 62.

17. Method according to one of claims 1 to 16, characterized in that, in particular in the area of ​​a joint between the two side segments (S2, S3) used for injection molding the fibers (F) containing the plasticized thermoplastic polymeric mass, a strip-shaped flattening (12) extending axially over the length of the thread of one / the external thread (10) of the molded part (1) is formed, so that a flash formed during injection molding lies in this flattening (12).

18. Method according to one of claims 1 to 17, characterized in that in the transition from the fastening section (BA) of the molded part (1) which in particular carries an external thread (10) to the axially adjoining assembly section (MA) which has a larger diameter than the fastening section (BA) and in particular is designed as a flange-like polygon, the base body (2) of the molded part (1) has a thread-free area which is referred to as a thread relief (FS), wherein the contour of the relief (FS) is designed according to a so-called tree root geometry using the “method of pull triangles”, preferably with additional rounding.

19. Method according to one of claims 1 to 18, characterized in that the ratio of an axial length (LB) of the fastening section (BA) to an axial total length (L) formed summarily from a length (LB) of the fastening section (BA) and a length (LM) of the mounting section (MA) is in the range of 38% to 57%, preferably around 54%.

20. Molded part (1) , manufactured according to a method according to any one of claims 1 to 19.

21. Molded part (1 ) according to claim 20, characterized in that the sections arranged in the axial direction (XX) in the inner channel (3) of the base body (2) intended for sealing reception of a plug part (4) are designed to provide a seal for one or more circumferential seals (5, 6) and for direct or indirect retention and / or locking of the plug part (4) and / or in a conical or cylindrical form for supporting and / or guiding the plug part (4).

22. Molded part (1) according to claim 20 or 21, characterized in that the inner channel (3) has a constant inner diameter.

23. Molded part (1) according to claim 20 or 21, characterized in that the inner channel (3) tapers in the insertion direction (S) of the plug part (4), in particular in a stepped or continuous manner, wherein at least in some sections the inner diameter of the inner channel (3) remains constant.

24. Molded part (1 ) according to one of claims 20 to 22, characterized in that the inner channel (3) starting from the insertion side of the base body (2) of the molded part (1 ) has a conical recess with a circumferential inclined surface (SF1 ) for the plug part (4).

25. Molded part (1 ) according to claim 24, characterized in that an angle (pi) between the inclined surface (SF1 ) and the longitudinal axis (XX) of the base body (2) lies in the range between 30° and 70°, preferably at 60°.

26. Molded part (1 ) according to claim 25, characterized in that a ring edge (RR) remaining next to the inclined surface (SF1 ) has a radial width BR which is not less than half the radial width (BF) of the entire end face of the base body (2), wherein the end face is formed as the sum of the area of ​​the ring edge (RR) and the area of ​​the axial projection of the inclined surface (SF1 ).

27. Molded part (1 ) according to one of claims 24 to 26, characterized in that the inner channel (3) starting from the insertion side of the base body (2) for the plug part (4) has a double-conical recess with a first inclined surface (SF1 ) and with a second inclined surface (SF2), in particular designed as a partial surface of the first inclined surface (SF1 ).

28. Molded part (1 ) according to claim 27, characterized in that an angle (p2) between the second inclined surface (SF2) and the longitudinal axis (XX) of the base body (2) lies in the range between 25° and 35°, preferably at 30°.

Images