Method and apparatus for manufacturing an electrically conductive plastic part

Abstract

The invention relates to a method for manufacturing an electrically conductive plastic part, wherein a plastic mass containing ferromagnetic particles (2) is injected into a cavity (7) of an injection mold (6) at a injection point (8), wherein at least a surface section (15) of the inner wall of the cavity (7) or of a wall of an insert (9) projecting into the cavity (7) generates a magnetic field in a partial volume of the cavity (7) which magnetically attracts the ferromagnetic particles (2) during the injection of the plastic mass into the cavity (7).

Description

field of technology

[0001] The invention relates to a method for manufacturing an electrically conductive plastic part, a device for carrying out the method and an electrically conductive plastic part, as well as a device for electrically conductive connection with an electrically conductive plastic part. State of the art

[0002] Electrical circuits are housed in enclosures and sometimes require shielding. Current technology uses electrically conductive enclosure linings or enclosures that are at least partially made of metal for this purpose.

[0003] Electrically conductive plastics are also considered state of the art. These plastics consist of a polymer compound in which electrically conductive particles, such as electrically conductive metal fibers, are embedded. The density of these particles is chosen so that they are at least partially in contact, giving the plastic component electrical conductivity. However, there are hardly any particles in the near-surface areas of a component made from such a plastic. If such a plastic part is to be used for shielding or as a housing for an electrical circuit, measures must be taken to ensure that a shielding conductor can make electrical contact with the particles. This could be achieved by removing material from a specific area of ​​the surface. Summary of the invention

[0004] The invention is based on the objective of improving a generic method and a generic device in such a way that plastic parts can be manufactured that are easier to use as umbrella bodies from a manufacturing perspective.

[0005] The problem is solved by the invention specified in the claims. The dependent claims not only represent advantageous further developments of the invention specified in the dependent claims, but also independent solutions to the problem.

[0006] The basic idea is that a magnetic field is generated in a selected area of ​​the cavity of an injection mold, and that the particles are ferromagnetic. As a result of this magnetic field, the particles are attracted, thus increasing the particle density in the volume section where the magnetic field is present. The particle density is therefore higher there than in other volume sections of the plastic part.

[0007] The injection mold thus has a cavity that includes at least one surface section defining a portion of the cavity volume influenced by a magnet. This surface section can also be formed by an insert, which, for example, creates a cavity in the plastic part. The insert can be permanently attached to the injection mold or, for example, removed from the cavity to demold the plastic part. The magnet can be positioned within the insert, generating a magnetic field surrounding it. This magnetic field causes the ferromagnetic particles in the area surrounding the insert, or in the volume adjacent to the magnet, to become denser. The magnetic field is preferably selected such that the magnetic force it generates is sufficiently strong to attract at least some of the particles to the surface.The surface of the plastic part manufactured in this way becomes electrically conductive. However, it is sufficient if the particle density is increased in an area directly adjacent to the surface, as this allows, for example, the threads of a screw (e.g., with a self-tapping thread) to come into electrically conductive contact with the particles when the screw is inserted. Ideally, the particles should extend into the surface of the plastic part, meaning they should be drawn to the inner wall of the cavity or the outer wall of the insert during manufacturing. In this case, a simple press fit of an electrically conductive component is sufficient to establish an electrically conductive connection between the component and the surface section of the plastic part.

[0008] The plastic part can be a flat body. The magnet can extend across the entire broad side of the cavity. Alternatively, the magnet can extend only across a portion of a broad side of the cavity. A single magnet can be used, or multiple magnets can be used. The magnets can be arranged side-by-side on the same broad side. Alternatively, the magnets can be arranged on different sides of the cavity. The insert can also extend through the entire cavity of the injection mold. It is also possible for a magnet to extend through the entire cavity of the injection mold, for example, from one broad side to the opposite broad side, so that the resulting plastic part is a flat body with a bore, the wall of the bore or an adjacent area having an increased particle density of the conductive particles.Furthermore, multiple injection points can be provided. These injection points can be located in close proximity to one or more magnets. This has the advantage that the plastic material entering the immediate vicinity of the magnet has a lower viscosity than plastic material that has already cooled slightly. However, the injection points can also be located further away from the magnet.

[0009] The magnet is preferably an electromagnet that is activated during injection of the plastic compound by passing an electric current through it. The area within the injection mold where the magnetic field exerts its effect is preferably adjacent to a injection point, where an opening is arranged through which the warm, free-flowing plastic compound is injected into the cavity. Here, the plastic compound has a higher flowability, allowing the ferromagnetic particles within it to be moved by the magnetic field.

[0010] However, it can also be advantageous to have the injection point spaced away from the magnet, especially if the magnet is part of an insert. The injection of the plastic compound into the cavity takes place at high pressure, for example, 200 bar. Spacing the injection point away from the magnet prevents potential damage or deformation.

[0011] In this process, a static magnetic field is first generated in a portion of the cavity. A plastic mass, made fluid by heating, is then injected into the cavity. This plastic mass contains metallic particles with ferromagnetic properties. The particles can be fibrous, fine shavings, or sections of fine wire. The particles, distributed approximately uniformly within the plastic mass, are subjected to force by the magnetic field and drawn towards the cavity wall or towards the magnet. Inhomogeneity in the magnetic field can be advantageous in this process.

[0012] The invention further relates to a device for electrically conductive connection with a plastic component that has been made electrically conductive by embedding electrically conductive particles. The device can be used, in particular, with a plastic part as previously described. The device has at least one first fastening element that has penetrating elements which, in particular with a sharp edge, can penetrate a plastic matrix that has been made electrically conductive by embedding electrically conductive particles. Preferably, the device is formed by a screw connection. In this case, the fastening element is designed as a threaded part. The fastening section is formed by a thread. The fastening section can interact with a fastening section of a second fastening element.The second fastening element can form a pressure flank that is arranged opposite a projection of the first fastening element, so that the plastic component can be positioned between the projection and the pressure flank. The second fastening element can form a mating thread corresponding to the first thread. The device, in particular the screw connection, can be used with a plastic part as described above. However, the screw connection can also be used with a plastic part containing electrically conductive particles, in whose manufacture the previously described method was not used, but in which the electrically conductive particles are substantially uniformly distributed throughout the entire plastic matrix. In this preferred variant, the particles can consist of non-ferromagnetic material, but also of copper or a similarly highly conductive material.The penetrating elements are preferably associated with a contact section that makes electrical contact with the particles via the penetrating elements. This contact section can be designed as a through-hole section for mounting the device in an opening. For mounting the device to an edge of the component, the contact section can have a different shape.

[0013] The screw connection preferably has a first threaded portion, which has a first thread and a through-pass section that can be inserted through an opening in the component. Adjacent to the through-pass section is a projection, for example, a collar, which is suitable for resting on an edge region of an opening in the plastic component. The device has a second threaded portion, which has a second thread that can be engaged in a screw connection with the first thread. For example, the first thread can be an external thread and the second thread an internal thread. However, it is also possible for the first thread to be an internal thread and the second thread an external thread. The second threaded portion forms a pressure flank that can bear against a second edge region of the opening.The second edge of the opening is opposite the first edge of the opening, so that the projection or collar is pressed against the first edge when the two threads are screwed together.

[0014] To improve the conductive connection between the screw fitting and the component, it is proposed that the first threaded portion, and in particular the projection, have one or more indenters that are pressed into the plastic matrix of the component during the screw connection process. This creates an electrically conductive connection with the particles. The indenters can be located adjacent to the projection and directly adjacent to it.

[0015] According to a preferred embodiment of the invention, the one or more indenters have a sharp edge. This edge forms a cutting edge that digs into the edge region of the opening when the two threaded parts are screwed together. Flanks may adjoin the cutting edge. The flanks may have a triangular shape. The cutting edge preferably runs obliquely to an axis of the two threaded parts. The cutting edge may extend obliquely from a shank of the first threaded part to a contact surface formed by the projection, for example, a collar. The two flanks each abut the shank and the contact surface, respectively, with a marginal edge.

[0016] The first thread can be an external thread. The shank of the first threaded section, which has the external thread, can be inserted into the opening of the component. The first threaded section can have a second external thread that, relative to the projection, is opposite the first thread. The first threaded section can be designed as a sleeve. It can have a cavity that extends axially through the entire first threaded section. The base of a connector, for example, can be inserted into this cavity. A mating connector's union nut can be screwed onto the second external thread.The first threaded section is preferably made of an electrically conductive material, for example, metal, and is brought into electrical contact with the electrically conductive particles contained in the component by the penetration of the penetrating elements, so that a shield of a cable connected to the connector can be electrically connected to the component via the first threaded section. The component can thus be used as a shielding element.

[0017] The indenters are preferably arranged in a transition area between a side surface of the projection facing the component, which preferably forms the contact surface, and a shank forming the first thread, the first thread preferably having an axial distance from the contact surface. The indenters can be arranged in a uniform circumferential distribution on an outer wall of the shank.

[0018] The second threaded section can be formed by a nut whose internal thread can be screwed onto an external thread of the first threaded section. A bead can project from a broad surface formed by the second threaded section, creating a pressure flank that, when the nut is screwed onto the external thread of the first threaded section, exerts pressure that presses the penetrating elements into the plastic material of the component. The bead can have an axial length greater than the axial extension length of the penetrating elements. In a transport state, with the second threaded section screwed onto the first, the bead can rest against the contact surface of the projection without the penetrating elements coming into contact with the second thread.

[0019] The contact surface of the first threaded section can have an annular groove in which an O-ring made of an elastic material is seated. The annular groove can be the same distance from the axis as the bead, so that the bead can bear against the O-ring in the transport position.

[0020] The invention further relates to a plastic shielding element comprising electrically conductive particles that are in electrical contact with one another, and a connection element that can be configured like the device described above. The connection element is attached to the component by means of one or more fastening sections. The connection element has penetrating elements that penetrate the plastic matrix and are in electrically conductive contact with the particles, so that a cable or the like can be connected to the connection element. Brief description of the drawings

[0021] Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. These show: Fig. 1 schematically in a section a first embodiment of an injection mold 6 with an insert 9 which has a magnet 10, Fig. 2 a plastic part 1 manufactured with an injection mold 6 of the first embodiment, comprising ferromagnetic particles 2 arranged therein, Fig. 3. the cut according to line III-III in Fig. 2, Fig. 4 a representation according to Fig. 1 of a second embodiment, Fig. 5 a representation according to Fig. 1 of a third embodiment, Fig. 6 a representation according to Fig. 1 of a fourth embodiment, Fig. 7 a fifth embodiment of the invention for manufacturing a component 1 which is designed as a flat body and has two openings according to section line VII-VII in Fig. 8, Fig. 8 the cut according to the cut line VIII-VIII in Fig. 7 by a parting line where two mold halves 6', 6'' of the injection mold 6 meet, Fig. 9 in cross-section a screw connection consisting of a first threaded part 16 and a second threaded part 25, Fig. 10 the screw connection according to Fig. 9 in view of the arrow X in Fig. 9, Fig. 11 enlarges section XI in Fig. 10, Fig. 12 the cut according to the section line XII-XII in Fig. 10, Fig. 13 an exploded view of the screw connection with a component 1, Fig. 14 a cut according to the cutting surface XIV in Fig. 9, wherein a shaft 17 of the first threaded part 16 is inserted into an opening 5 of the component 1, before the nut 25 is screwed onto the external thread 19, Fig. 15 a follow-up presentation to Fig. 14 after screwing the nut 25 onto the external thread 19 and penetration of penetrating elements 24 into an edge area 5' of the opening 5, Fig. 16 the cut according to line XVI in Fig. 15 and Fig. 17 a representation according to the cross-sectional area XIV of the screw connection in a transport position. Description of the embodiments

[0022] Reference numeral 6 designates an injection mold having a cavity into which an injection molding compound can be injected. This cavity is subsequently referred to as cavity 7. The wall of cavity 7 can have one or more injection points 8. A plastic compound can be injected into cavity 7 through each of the injection points. The plastic compound is injected into the cavity at a pressure of, for example, more than 200 bar. The pressure can be generated by a suitable extruder, which melts the plastic granules and then injects them into cavity 7 through an opening provided at injection point 8. Ferromagnetic particles 2, for example, fibrous particles, are added to the plastic granules or other raw material. These particles are electrically conductive. A magnetic field can exert an attractive force on the particles.

[0023] For the sake of clarity, only one injection point 8 is shown in the exemplary embodiments.

[0024] A magnet 10 is provided in the cavity 7. Preferably, this is an electromagnet which can be supplied with current from a power source 11 via conductors 12, so that the magnet 10 generates a magnetic field in a partial volume of the cavity. The magnetic field is designed to exert an attractive effect on the particles 2 contained in the base material mass.

[0025] In the Fig. In the embodiment shown in Figure 1, the magnet 10 is attached to the lower end of an insert 9, the upper end of which forms a holder 13. The holder 13 can, for example, be surrounded by plastic insulation. The insert 9 can be firmly anchored in the cavity 7. However, it is also possible to pull the insert 9 out of the cavity 7 for demolding purposes. The arrows illustrate the flow of the plastic material in the cavity 7. The plastic material flows past the insert 9 and thus past the magnet 10. Since the injection point 8 is located very close to the magnet 10, the plastic material flowing around the insert 9 has a relatively high flowability. The particles can therefore move within the material when they enter an area where the magnetic field generated by the magnet 10 exerts an attractive force.This area is a surrounding region around surface section 15, behind which magnet 10 is located. The concentration of particles 2 thus increases in a volume region surrounding this surface section 15. In the . Fig. 2 this is indicated by a higher density of particles 2 compared to a volume area that is away from the surface section 15.

[0026] The Fig. 2 and Fig. 3 show a device in accordance with Fig. A manufactured plastic part 1 has a cavity 5, which includes a surface section 3 below which the density of the particles 2 is increased. Preferably, the magnetic field is strong enough that during the manufacturing of the plastic part 1, at least some of the particles 2 are drawn up to the surface section 15, so that these particles 2 lie within the surface 3 of the plastic part 1. A bolt or other metallic object, for example, can then be inserted into the cavity 5, which is in conductive contact with the inherently conductive plastic part 1. A power line can be connected to this bolt, allowing the plastic part 1 to be used as a shield. The plastic part 1 can, for example, be a housing or part of a housing.

[0027] The one in Fig. The second embodiment shown in Figure 4 differs from the first embodiment essentially only in the position of the injection point 8 and the design of the insert 9. Here, the insert also projects through an opening in the wall of the injection mold 6 into the cavity 7. Here, too, the magnet 10, which can also be an electromagnet, is located in a section of the insert 9 that projects into the cavity 7.

[0028] The one in Fig. The third embodiment shown in Figure 5 differs from the second and first embodiments only in the shape of the insert 9 and the position of the injection point 8. Here, the insert 9 has a surface section 15 with an external thread 14. Before demolding, the insert 9 must be pulled out of the thread 14.

[0029] In the Fig. In the fourth embodiment shown in Figure 6, the magnet 10 is part of a wall of the injection mold 6. Here, too, a magnetic field is generated in a volume section that is immediately adjacent to the surface section 15 of a magnetic zone, which, when the plastic mass containing the ferromagnetic particles is injected, causes an enrichment of the particles 2 in the vicinity of the surface section 15.

[0030] The workpieces that can be produced with the devices described above can preferably be used for shielding electronic circuits. To connect the workpieces to a shielding conductor, the method described above creates at least one surface section of the workpiece in which the concentration of the ferromagnetic particles 2 is increased in an area beneath this surface section, or in which at least some of the ferromagnetic particles 2 protrude to the free surface, such that contact by means of a metallic contact element, for example a screw or a clamp, is sufficient to electrically connect the electrically conductive workpiece to the power line.

[0031] However, it may be sufficient that the concentration of electrically conductive particles 2 below this surface section is merely increased, so that an electrically conductive connection with a contact element is associated with minimal mechanical effort.

[0032] In the Fig. 7 and Fig. In the embodiment shown in Figure 8, the injection mold 6 consists of a first mold half 6' and a second mold half 6''. A flat body can be produced using the injection mold 6. The flat body has two openings 5. For producing the openings, the injection mold 6 has two inserts 9, each formed by a magnet 10. The injection mold 6 also has several injection points 8 at which the plastic material containing electrically conductive and ferromagnetic particles can be injected into the cavity 7.

[0033] In exemplary embodiments not shown, the magnet 10 can extend over an entire broad side surface of the injection mold 6. Several magnets 10 can be arranged on a single broad side surface. Multiple magnets 10 can also be arranged on different surfaces. Preferably, the magnet or magnets 10 are each arranged in the immediate vicinity of a section of the injection mold 6 that forms an opening in the plastic part. The particle density of the conductive particles is then increased in the area of ​​the opening. The component can be a flat body. It can have several openings, and it is particularly intended that all openings intended to make electrical contact with, for example, a screw connection, have an increased particle density of the conductive particles at their edges.

[0034] The Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13, Fig. 14, Fig. 15, Fig. 16 to Fig. Figure 17 shows an embodiment of such a screw connection, which is used in an exemplary application with a component as previously described. Preferably, however, this screw connection is used with a plastic part, as known from the prior art, in which electrically conductive particles are embedded in a plastic matrix and are at least partially electrically connected to one another, wherein these particles can consist of both ferromagnetic and non-ferromagnetic materials, for example, copper.

[0035] A first threaded section 16 is designed as a screw. The threaded section 16 has a shank 17 with a through-pass section that can be inserted through an opening 5 of the component 1. The through-pass section 17 has an external thread 19. The external thread 19 is spaced apart from a bearing surface 18' of a circumferential projection 18. Several penetration elements 24 extend within this space, arranged at uniform angular intervals around an axis A of the external thread 19. The projection 18 is preferably formed by a circumferential collar. On the side of the projection 18 facing away from the external thread 19, there is another thread 20, which is also designed as an external thread. The two threads 19, 20 are coaxial. A cavity 21 extends through the two threads 19, 20, so that the first threaded section 16 is designed as a sleeve.

[0036] The one or more penetrating elements 24 each have a cutting edge 24'' that runs obliquely to the axis A. The cutting edge 24'' connects an outer wall of the shaft 17 with a contact surface 18' of the projection 18, which is formed by a broad side of the collar forming the projection 18. Adjoining the cutting edge 24'' are flanks 24' that run obliquely to each other. The flanks 24' each have the shape of a triangle, with one edge of the triangle forming the cutting edge 24', another edge running in the contact surface 18', and the third edge running in the outer surface of the shaft 17.

[0037] An annular groove 22 extends in the contact surface 18'. The annular groove 22 extends radially outside the indenters 24. An O-ring 23 made of an elastic material is located in the annular groove 22. The diameter of the blank 23 is slightly larger than the depth of the annular groove 22, so that a portion of the O-ring 23 projects beyond the contact surface 18'.

[0038] A second threaded part 25 is designed as a nut and has a second thread 26, which is designed as an internal thread, which can be screwed onto the external thread formed by the first thread 19.

[0039] A bead 27 projects from a broad side surface of the second threaded part 25, forming a pressure flank. The bead 27 has an axial length dimensioned such that in a Fig. In the transport position shown in Figure 17, the second threaded part 25 is screwed to the first threaded part 16 and the bead 27 rests against the contact surface 18' or against the O-ring 23, and the internal thread 26 does not touch the one or more indenters 24. The cutting edges 24'' are thus protected in the transport position.

[0040] The screw connection described above is used, for example, as follows:

[0041] First, according to Fig. 14 the shaft 17 of the first threaded part 16 having the external thread 19 is inserted through an opening 5 of a component 1 which is made of plastic and has electrically conductive particles, for example fibers, embedded in the plastic mass which are in electrically conductive connection with each other.

[0042] The internal thread 26 of the second threaded part 25 is then screwed onto the external thread 19 until the bead 27 comes into contact with the edge region 5'' of the opening 5. By further turning the nut 25, the indenters 24 enter the edge region 5' of the opening 5, which is opposite the edge region 5''. The indenters 24 are designed as cutting edges and have an edge 24'' that digs into the material of the component 1. The flanks 24' come into contact with the electrically conductive particles 2 contained in the plastic of the component 1, as shown in the Fig. 15 and Fig. 16 is shown.

[0043] A connecting element attached to a component 1 in this manner, which in the exemplary embodiment is formed by the two threaded parts 16, 25, forms a shielding element for shielding, for example, an electrical circuit. The shielding element can be a flat body, a profiled body, or the wall of a housing. The connecting element can be designed as in the exemplary embodiment shown in the figures. However, the connecting element can also be formed by a clamp that is clamped to an edge of the component 1. Two clamping flanks then each form a mounting section with a contact flank and a pressure flank. It is essential that the connecting element has one or more penetrating elements, for example, formed by cutting edges or needles, which can penetrate the plastic body of the component 1 in such a way that they establish an electrically conductive connection with the electrically conductive particles 2.A cable or other electrically conductive element can then be connected to the connecting element. The connecting element itself can be made of metal, and in particular copper. It is considered advantageous if the aforementioned method is used in the manufacture of the plastic part, with the magnet then positioned at the location where the connecting element will later connect to the plastic part.

[0044] The foregoing statements serve to explain the inventions covered by the application as a whole, which each independently further develop the prior art at least through the following combinations of features, whereby two, several or all of these combinations of features may also be combined, namely:

[0045] A method characterized in that at least a surface section 15 of the inner wall of the cavity 7 or of a wall of an insert 9 projecting into the cavity 7 generates a magnetic field which attracts the ferromagnetic particles 2 during the injection of the plastic mass into the cavity 7 in a partial volume of the cavity 7.

[0046] A method characterized in that the surface section 15 is a section of the wall of the cavity 7.

[0047] A method characterized in that the surface section 15 is formed by an insert 9 projecting into the cavity 7.

[0048] A method characterized in that the magnetic field is generated by an electromagnet 10.

[0049] A method characterized in that the electromagnet 10 is arranged outside the injection mold 6 or inside the insert 9.

[0050] A method characterized in that the magnetic field has sufficient strength to produce a compaction of the electrically conductive ferromagnetic particles 2 in a volume region of the plastic part 1 adjacent to a surface section 3 of the plastic part 1.

[0051] A device for carrying out a method according to one of the preceding claims with an injection mold 6, which has a cavity 7 into which a plastic mass containing ferromagnetic particles can be injected at a injection point 8, characterized in that a magnet 10 is assigned to a surface section 15 of the cavity or to an insert 9 projecting into the cavity 7, with which a magnetic field can be generated in the area of ​​a volume region of the cavity 7 adjacent to the surface section 15.

[0052] A device characterized in that the magnet 10 is an electromagnet and / or that the injection point 8 is adjacent to or spaced away from the surface section 15.

[0053] A plastic part characterized in that the plastic part 1 has at least one surface section 3 which borders a volume region in which the density of the ferromagnetic particles 2 is increased compared to a volume region located further away from it.

[0054] A plastic part characterized in that the surface section 3 is at least partially electrically conductively connected to the ferromagnetic particles 2 arranged in the volume.

[0055] A device characterized in that one or more indenters 24 project from the contact section 17, which are pressed into the plastic matrix when the contact section 17 is brought into contact with the component 1 in order to create an electrically conductive connection with the particles 2.

[0056] A device characterized in that the first fastening part 16 has a first fastening section 19 which can be connected to a second fastening section 26 of a second fastening part 25, wherein the first fastening part 16 has a projection 18 for bearing on a first edge region 5' of the component 1 and the second component 25 forms a pressure flank 27 for bearing on a second edge region 5'' opposite the first edge region 5'.

[0057] A device characterized in that the contact section 17 is a through-pass section 17 which can be inserted through an opening 5 of the component 1, the first fastening part 16 is a threaded part, the first fastening section is a first thread 19, the second fastening part 25 is a second threaded part and the second fastening section 26 is a second thread 26 which can be brought into a screw connection with the first thread 19.

[0058] A device characterized in that the one or more indenters 24 are adjacent to the projection 18.

[0059] A device characterized in that the one or more indenters 24 have a sharp edge 24'', wherein in particular it is provided that the edge 24'' runs obliquely to an axis A of the threads 19, 26.

[0060] A device characterized in that the one or more indenters 24 are arranged in a transition area between a contact surface 18' pointing towards the component 1 of the projection 18, for example designed as a collar, and a shaft 17 forming the first thread 19.

[0061] A device characterized in that several indentation elements 24 are arranged in a uniform circumferential distribution on an outer wall of a shaft 17.

[0062] A device characterized in that the second threaded part 25 is a nut which is screwed onto an external thread formed by the first thread 19 with its internal thread 26, wherein a bead forming the pressure flank 27 projects from a broad side of the second threaded part 25 facing the component 1.

[0063] A device characterized in that a broad side 18' of the first threaded part 16, pointing towards the first thread 19, has an annular groove 22 in which an O-ring 23 is inserted.

[0064] A device characterized in that the bead 27 has an axial distance to the second thread 26 which is greater than the axial extent of the indenter 24.

[0065] A device characterized in that the first threaded part 16 has a cavity 21, wherein the cavity 21 is formed by a sleeve section with a third thread 20 in the form of an external thread.

[0066] A device characterized in that the outer diameter or plan view of the projection 18 corresponds approximately to the outer diameter or plan view of the second threaded part 25.

[0067] A shielding element characterized in that penetrating elements 24 of the connecting element 16, 25 are electrically conductively connected to the particles 2 by engaging in the plastic matrix.

[0068] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of this application hereby incorporates in full the disclosure content of the associated / attached priority documents (copy of the earlier application), also for the purpose of including features of these documents in the claims of the present application. The dependent claims, even without the features of a referenced claim, characterize independent inventive developments of the prior art, in particular for the purpose of filing divisional applications based on these claims. The invention specified in each claim may additionally include one or more of the features described above, in particular those identified by reference numerals and / or listed in the reference numeral list.The invention also relates to design forms in which individual features mentioned in the preceding description are not realized, in particular insofar as they are recognizably unnecessary for the respective purpose or can be replaced by other technically equivalent means. List of reference symbols 1 component, plastic part 2 ferromagnetic particles 3 Surface section 4 Surface 5 Cavity, opening 5' Edge area 5'' edge area 6 injection mold 6' Half of the mold 6'' mold half 7 Cavity 8 Injection point 9 deployment 10 Magnet 11 Power source 12 Supply line 13 bracket 14 threads 15 Surface section 16 first threaded part, screw, fastening part 17 Through-pass section, shaft 18 lead, federal government 18' Plant area 19 first thread, external thread, fastening section 20 threads, external threads 21 Cavity 22 Ring groove 23 O-ring 24 Penetrating element, cutting edge 24' Flank 24'' edge, cutting edge 25 second threaded part, nut, fastening part 26 second thread, internal thread, fastening section 27 Pressure flank, bead Axis

Claims

Method for manufacturing an electrically conductive plastic part, wherein a plastic mass containing ferromagnetic particles (2) is injected into a cavity (7) of an injection mold (6) at a injection point (8), characterized in that at least a surface section (15) of the inner wall of the cavity (7) or of a wall of an insert (9) projecting into the cavity (7) generates a magnetic field in a partial volume of the cavity (7) which magnetically attracts the ferromagnetic particles (2) during the injection of the plastic mass into the cavity (7). Method according to claim 1, characterized in that the surface section (15) is a section of the wall of the cavity (7). Method according to claim 1, characterized in that the surface section (15) is formed by an insert (9) projecting into the cavity (7). Method according to one of the preceding claims, characterized in that the magnetic field is generated by an electromagnet (10). Method according to claim 4, characterized in that the electromagnet (10) is arranged outside the injection mold (6) or inside the insert (9). Method according to one of the preceding claims, characterized in that the magnetic field has sufficient strength to produce a compaction of the electrically conductive ferromagnetic particles (2) in a volume region of the plastic part (1) adjacent to a surface section (3) of the plastic part (1). Apparatus for carrying out a method according to one of the preceding claims with an injection mold (6) having a cavity (7) into which a plastic mass containing ferromagnetic particles can be injected at a injection point (8), characterized in that a magnet (10) is assigned to a surface section (15) of the cavity or to an insert (9) projecting into the cavity (7), with which a magnetic field can be generated in the area of ​​a volume region of the cavity (7) adjacent to the surface section (15). Device according to claim 7, characterized in that the magnet (10) is an electromagnet and / or that the injection point (8) is adjacent to or spaced away from the surface section (15). Plastic part with ferromagnetic particles (2) contained in a plastic mass, characterized in that the plastic part (1) has at least one surface section (3) which borders a volume region in which the density of the ferromagnetic particles (2) is increased compared to a volume region located away from it. Plastic part according to claim 9, wherein the ferromagnetic particles (2) in the volume of the plastic part (1) are at least partially electrically conductive in contact with each other, such that the plastic part (1) has an electrical conductivity, characterized in that the surface section (3) is at least partially electrically conductively connected to the ferromagnetic particles (2) arranged in the volume. Device for electrically conductive connection with a component (1) made of plastic, which is made electrically conductive by embedding electrically conductive particles (2) in a plastic matrix, with an electrically conductive first fastening part (16) which has a contact section (17), characterized in that one or more indentation elements (24) project from the contact section (17), which are pressed into the plastic matrix when the contact section (17) is brought into contact with the component (1) to create an electrically conductive connection with the particles (2). Device according to claim 11, characterized in that the first fastening part (16) has a first fastening section (19) which can be connected to a second fastening section (26) of a second fastening part (25), wherein the first fastening part (16) has a projection (18) for bearing on a first edge region (5') of the component (1) and the second component (25) forms a pressure flank (27) for bearing on a second edge region (5'') opposite the first edge region (5'). Device according to claim 11 or 12, characterized in that the contact section (17) is a through-pass section (17) that can be inserted through an opening (5) of the component (1), the first fastening part (16) is a threaded part, the first fastening section is a first thread (19), the second fastening part (25) is a second threaded part, and the second fastening section (26) is a second thread (26) that can be brought into a screw connection with the first thread (19). Device according to one of claims 11 to 13, characterized in that the one or more indenting elements (24) adjoin the projection (18). Device according to one of claims 11 to 14, characterized in that the one or more indenters (24) have a sharp edge (24''), wherein in particular it is provided that the edge (24'') runs obliquely to an axis (A) of the threads (19, 26). Device according to one of claims 11 to 15, characterized in that the one or more indenting elements (24) are arranged in a transition area between a contact surface (18') of the projection (18), for example designed as a collar, which points towards the component (1), and a shaft (17) forming the first thread (19). Device according to one of claims 11 to 16, characterized in that several indentation elements (24) are arranged in a uniform circumferential distribution on an outer wall of a shaft (17). Device according to one of claims 11 to 17, characterized in that the second threaded part (25) is a nut which is screwed onto an external thread formed by the first thread (19) with its internal thread (26), wherein a bead forming the pressure flank (27) projects from a broad side of the second threaded part (25) facing the component (1). Device according to one of claims 11 to 18, characterized in that a broad side (18') of the first threaded part (16) facing the first thread (19) has an annular groove (22) in which an O-ring (23) is inserted. Device according to one of claims 11 to 19, characterized in that the bead (27) has an axial distance to the second thread (26) which is greater than the axial extent of the indenter element (24). Device according to one of claims 11 to 20, characterized in that the first threaded part (16) has a cavity (21), wherein the cavity (21) is formed by a sleeve section with a third thread (20) in the form of an external thread. Device according to one of claims 11 to 21, characterized in that the outer diameter or a plan view of the projection (18) corresponds approximately to the outer diameter or a plan view of the second threaded part (25). Shield element made of plastic with electrically conductive particles (2) embedded in the plastic mass of the shield element, which are at least partially in an electrical conductive connection with each other, wherein an electrically conductive connecting element (16, 19) is in an electrical conductive connection with the electrically conductive particles (2) and is attached to the component (1) by means of one or more fastening sections (19, 25), characterized in that penetrating elements (24) of the connecting element (16, 25) are electrically conductively connected to the particles (2) by engaging in the plastic matrix. Method, device, plastic part or screen element, characterized by one or more of the characterizing features of one of the preceding claims.

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