AT500749B1 - SIGNALING MAGNETIC TRANSMISSION ELEMENT OF PLASTIC, TOOL FOR THE MANUFACTURE AND METHOD OF OPERATING THE TOOL - Google Patents

Description

2 AT 500 749 B1

The invention relates to a tool for producing a signaling magnetic transmission element and a method for operating this tool according to the preamble of claim 1. 5 Such transmission elements are usually made of plastic and are used to determine the position of the position drive, for example in a DVD drive, a Car headlight readjustment drive and the like more actuators.

In such signaling gear elements, which are usually made of plastic io, it was previously only known to mechanically press the magnetic ring used as a signal element on the plastic part. There was the disadvantage that the connection was not strong enough to withstand certain load conditions. Particularly in the case of highly dynamic load changes, there was the danger that the magnetic ring would strike or jam, which was associated with an intolerable signal inaccuracy. 15

The mechanical pressing of the magnetic ring resulted, moreover, disadvantageously to an undesirable deformation of the ring, which led to a non-round barrel. This also affected the signaling. Moreover, it has hitherto only been possible to press such magnet rings out of a sintered material because magnet rings made of a plastic-ferrite material can not withstand the high forces during pressing. They break. Incidentally, in order to prevent breakage of these plastoferrite rings, it has been known to provide an even greater radial play between the pressing ring and the magnetic ring, so that the plastoferrite ring has been only slightly mechanically stressed.

This, however, undesirably impaired the concentricity because, due to the higher radial play, there was a risk that the pressed-on ring would succeed eccentrically and in turn distort the signal output. 30

This resulted in a corresponding signal inaccuracy or incurred corresponding signal failures, which in turn burdened the entire actuator disadvantageous.

EP 1 008 866 A2 discloses a planar sensor element which has a sensor body of polymeric material in which magnetizable particles are embedded, and wherein the sensor body can be connected to a shaft and / or a sealing ring.

This invention has the disadvantage that a possible connection of the sensor body takes place mechanically on a sealing ring or the like, which can lead to damage of the sensor body Sen or distorts the signal output due to off-center arrangement.

EP 0 213 732 A1 discloses a magnetic ring for detecting rotational movements of an object, wherein the magnetic sensor is arranged in, on, on or about a rotating body and has a synthetic resin material in which the magnetic material is embedded. 45

This invention has the disadvantage that the manner of the connection of this is not apparent, with a mechanical connection between the magnetic sensor and the receiving ring carrier can not be excluded. DE 44 43 655 C1 discloses a magnetic or magnetizable first body which has a positive connection with a second body, the two bodies having a plastic material and the one body being injection molded onto the other body in a two-component injection molding process. However, this invention has the disadvantage that the two bodies have a relatively complex construction, which makes the production relatively expensive overall.

The invention is based on the object, a signaling magnetic transmission element 5 made of plastic, as well as a tool for producing the same in such a way that the signaling magnetic ring can be attached to the plastic part with significantly improved concentricity and under stress least destructive forces.

To solve the problem, the invention is characterized by the technical teaching of claim io 1 and the other independent claims.

The signal is read out via so-called Hall elements, which are arranged in the form of an electronic component on a printed circuit board and must be arranged in a very accurate, small distance from the rotary signal generator. 15

According to the invention, a plasto-ferrite, for example PA12-based with strontium and / or barium ferrite with, for example, 9 pairs of pools, ie 18 signal changes per revolution produced by injection molding and it is a multi-course, for example, 2- or 4-screw from, for example, polyacetal or others integral technical thermoplastic materials integrally formed.

The plastoferrite ring can already receive a magnetic alignment in the tool, but preferably a subsequent magnetic alignment is brought about. The sprue of this injection molded part is made by means of a so-called Schirmangusses with extremely fine Angu-25 ßabmessungen and the punch is integrated into the injection mold. A radial clearance of less than or equal to 0.04 mm or less than or equal to 0.02 mm eccentricity is sought and is required for proper function.

The Plastoferrit is fixed in a Einlegespritzgusswerkzeug by means of special control elements 30 so that during the injection molding process, for example, polyacetal for the production of the screw no expansion and / or Aussermittigkeit and / or no runout occurs, which would adversely affect the signal-generating effect to Hall element.

In particular, various injection molding phases have been developed in this manufacturing process 35 and was taken to ensure that the lowest possible radial pressure is exerted on the plastoferrite ring. Furthermore, attention must be paid to complete ejection of the screw and care is taken in the area of the plastoferrite ring for ventilation or good connection, since the radial accelerations and their frequency are considerable in the normal operation of a DVD drive. 40

In the area of the plastoferrite ring, the thermoplastically produced screw has a bore for receiving the motor shaft and, in this case, pressing forces of, for example, greater than or equal to 30 n and less than or equal to 90 N are specified. The thermoplastic screw generally has a multi-start spiral thread and it is according to the invention a 4-speed spiral with a maximum of 13.76 ° slope (0.3 module) recognized as just produced, because there is otherwise an undercut in the tool and thus demolding would no longer be possible. Thus, in another embodiment of the present invention, the plastoferrite ring and the thermoplastic worm element are produced by means of a so-called twin-screw injection molding process, and according to the invention, the plastoferrite ring is first produced. In a further development, this two-part injection-molded element is replaced by a one-piece element and therefore the entire highly dynamic signaling coupling element is made of plastoferrit. It must be made the configuration such that only an outer ring can be magnetized and causes a sufficient signal generator effect in conjunction with a Hall element. The property of the plastoferrite is hereby considered in the light of the mechanical properties and requirements of a worm drive.

In summary, it is stated that one of the essential features of the invention is that the signaling magnetic transmission element now consists of a magnetic ring of a plasto-io ferrite material and that the Plastoferritring is injection molded in the injection-plastic injection molding process to the plastic injection molding.

In a further development of the present invention, it is provided that the plastoferring ring is protected against destruction in a special way in the tool mold. This is inventively 15 achieved in that in the mold insert of the mold a receiving groove for the deposit of Plastoferritringes is created, in which the Plastoferritring is inserted prior to the production of the plastic injection molding.

In order to protect this plastic ferrite ring, which is very sensitive to radial explosive forces, it is provided in a first step according to the method that radial, circumferentially distributed support elements are arranged on the receptacle for receiving the plastoferrite ring, allowing radial play of e.g. Allow 0.01 to 0.02 mm. The arrangement of the radial support elements on the outer circumference of the plastoferrite ring results in said radial play and, as a result, the ring is initially stressed with no radially directed forces. These support elements are only used for centering the Plastoferritringes in the receiving groove of the mold, without the ring itself is attacked load transfer.

The radially outward play between the inner circumference of the support elements and the outer circumference of the Plastoferritringes is chosen so that in the injection molding process, in which 30, the ring due to the centrally flowing plastic mass radially directed outwardly expanded, this now applies to the inner sides of the support elements However, the Anle-forces are so small that a collapse of the ring is prevented in any case.

To solve the problem of preventing the ring from bursting, not only are the radial support elements given, which cause only a pre-centering, but also position elements which can be directly delivered to the shell circumference of the ring.

These are also directed in the radial direction, evenly distributed around the circumference and complement each other with the likewise radially arranged support elements, so that all Ele-40 elements (support elements and control elements) approximately close to the outer periphery of the Plastoferritringes include and support.

However, the latter actuating elements lie without radial play directly on the outer circumference of the ring. Even a radially inwardly directed biasing force 45 can be set.

According to a development of the invention, the adjusting elements are uniformly driven undeliverable by a circularly driven adjusting ring in the radial direction. The collar drives all control elements synchronously. Thus, they are delivered with uniform force on the jacket so the ring and compensate for the injection pressure, which is directed radially outward from the central region of the mold and tries to blow up the Plastoferritring.

It is thus created with the adjusting elements adjustable depending on the injection pressure force-transmitting sleeve on the outer circumference of the Plastoferritringes and this is thereby secured against splashing 55. 5 AT 500 749 B1

Of course, each actuator is initially radially deliverable separately to allow basic adjustment. If this absolutely necessary basic setting has been carried out, then all the adjusting elements can be uniformly driven inwards and outwards in the radial direction by the aforesaid rotary drive-type adjusting ring. 5

The synchronous contact with the outer periphery of the Plastoferritringes takes place before the introduction of the injection molding compound, so that even before the initiation of the plastic mass of Plastoferritring is supported load-transmitting on its entire outer circumference. In a further development of the invention, however, it may additionally be provided that the adjusting elements are adjusted in their radial feed drive in the direction of the jacket of the Plastoferritringes depending on the injection pressure or certain cycle times during injection molding. 15 It is important that these adjusting elements can also be adjusted radially outward for the purpose of removal of the Plastoferritringes after completion of the plastic injection molding, so as to get the receiving cavity free again and to be able to entform the finished gear element. Important in the invention is therefore that for pre-centering of the Plastoferritringes in the receiving relatively relatively rigid support elements are arranged, which result in a radial clearance to the arranged in the interior Plastoferritring.

It is also important that evenly distributed further adjusting elements are present, but 25 create the load-transferring on the outer circumference of the Plastoferritringes and supported against the injection pressure.

In the following the invention will be explained in more detail with reference to drawings showing only one embodiment. In this case, 30 further inventive features and advantages of the invention will become apparent from the drawings and their description.

Show it:

FIG. 1 shows a gear element according to the invention in a perspective side view, FIG. 2 shows the gear element according to FIG. 1 in another embodiment,

FIG. 3: top view of the magnetic ring,

4 shows a section through the magnetic ring in FIG. 3, FIG.

FIG. 5: a longitudinal section through the transmission element according to FIG. 1,

FIG. 6: top view of the mold insert with adjusting ring; FIG. 7: section through the right side of the mold, namely the nozzle side.

In Figures 1 to 5, a transmission element 1 is generally shown in plastic, which consists essentially of a shaft 2, which carries a toothing 3. The toothing can be formed as spiral toothing, involute toothing or else as straight toothing according to FIG.

The shaft 2 is materially integral with a likewise made of plastic head 4, in the region of said magnetic ring is embedded. The magnetic ring is referred to in the following description as Plastoferritring 5, although it could also consist of other materials. The material specification Plastoferrit is therefore not to be understood as limiting the right of protection.

This means that if you have a magnetic ring made of another material, e.g. a sintered material, the same advantages would be achieved according to the invention. 55

I 6 AT 500 749 B1

Even with this very brittle sintered material, the advantages of the invention are achieved, namely the non-destructive spraying of such a ring 5 to the plastic body of the transmission element 1. 5 The transmission element 1 has, moreover, a central axis of rotation 6, and is otherwise in the head region of a lower conical approach 7, which goes beyond the ring 5 in a likewise conical projection 9. In the area of the top surface and the projection 9 radially directed webs 8 are arranged, which serve as Anspritzkanal and as injection point for the production of the plastic injection and the rest of the head 4 mechanically stabilizing-io ren.

FIG. 2 shows that such an injection point 12 is arranged radially outward on the end face of a web 8. However, the invention is not limited thereto. The injection point 12 could also be arranged, for example, in the region of the shaft 2, in particular in its end face.

In the head region of the head 4, the webs form an upper cover surface 10, which is penetrated by a central bore 11 which passes through the entire plastic body, as can be seen from FIG. 20

FIG. 3 shows such a plastoferrit ring in plan view, and it can be seen that recesses 13 which are distributed uniformly around the circumference are present, which serve for anchoring in the plastic material of the plastic injection molding. He has, moreover, a central bore 15, and the embedding of this ring 5 in the plastic material is shown in detail in Figure 5.

Here it can be seen that a receiving space 16 is formed in the head area, and now engage in the receiving space 16, the recesses 13, so that the plastic material engages during the injection molding in these recesses 13 and the ring 5 non-positively toothed in the plastic material. It is thus interlocked against radial and against forces directed in the circumferential direction.

The annular flange 14 of the magnetic ring is thus embedded in a particularly load-transmitting manner in the plastic body of the transmission element 1.

In Figure 6, the top view of a mold 17 is now shown on the nozzle side. This mold is shown in Figure 7 still in section. A middle cavity is formed in the mold 17, which consists essentially of the central core bore for a core pin 22. From this central core bore extends radially outwardly a cone groove 20, by means of which the previously described projection 9 is formed in the head 4 of the transmission element 1. Radially outwardly from this conical groove 20, the receiving groove 18 extends for receiving the magnetic ring 5. From the cone groove 20, extending channels or slots 19 which serve to form the webs 8 shown in Figure 2 on the head 4 of the transmission element 1 extend , Thus, at one of the webs opens a sprue 21, which is arranged in the region of a support element 23 and over which the plastic material flows into the head area.

It is important that in the area of this mold insert 31 a plurality of evenly distributed circumferentially arranged support members 23 are present. In the exemplary embodiment shown, these are three support elements 23, which are directed in the direction of the central mold cavity. 7 AT 500 749 B1

It is also possible to use more or less than three support elements 23. It is important that the front end of the support elements 23 - which are directed next to the lateral surface to the ring 5 - form a radial clearance 25 in the direction of the receiving groove 18. In this receiving cap 18 of the magnetic ring 5 is inserted. 5

After inserting the magnet ring 5 in the receiving groove 18 now an outer - rotationally driven in the circumferential direction - collar 28 is set in motion.

The adjusting ring 28 has in each case inwardly directed parking ramps 29, which are formed io inclined in the circumferential direction. These adjustment ramps 29 are made of a highly wear-resistant steel and form sliding surfaces for rolling bearings 42, which are arranged at the radially outer ends of adjusting elements 26. These adjusting elements 26 are held radially displaceable and lockable in respective setting scenes 27. With the rotary drive of the adjusting ring 28, therefore, the rolling bearings 42 slide on the inclined ramps 29 and are thus moved radially inwardly, for example in the direction of arrow 24. Thus, the radially inwardly directed ends of the adjusting elements 26 engage in a load-transmitting manner on the outer circumference of the magnetic ring 5. The adjustment is exactly synchronous, i. the forces with which the respective actuating element 26 rest against the ring are precisely dimensioned by a presetting of the respective actuating element in such a way that all the actuating elements engage with the same circumference on the outer circumference of the Mag-20 netringes.

The bearing of the adjusting ring 28 in this case takes place in housing-fixed outer guide elements 34 which are arranged on the mold plate. 25 There are also shown fastening screws 41 which show a guide cover for the mounting of the adjusting ring 28.

The figure 7 shows a section through the nozzle-side half of the mold 32. It consists essentially of a mold plate 33, with the mold insert 31. There is a Ausspritzdüse 30 38 is provided, which injects into a directed against the mold parting plane 40 nozzle orifice 37 from. It is important that the plastic material from the nozzle orifice 37 enters the opposite - not shown in the drawing - half of the mold, where it is guided into a bypass channel and the bypass channel in turn flows into the arranged on the mold plate 33 Anspritztunnel 39. 35th

The plastic material is thus injected from the Anspritzdüse 38 first in the opposite mold half, and then back to return and to get into the Anspritztunnel 39 of the mold plate 33. This is considered to be particularly advantageous because it does not require space consumption in the region of the steep elements according to FIG. 6.

The injection tunnel 39 opens into the injection point 12, which is shown in FIG. In the region of the central axis 35, a bore core pin 36 is arranged, which centers the right-hand forming tool 32 with the left-hand molding tool (not shown in the drawing).

From Figure 7 it can be seen that the adjusting elements 26 are displaced approximately flush with the mold parting plane. 50

It can be seen that the front ends at least partially comprise the outer circumference of the magnetic ring, wherein an encompassing area per actuator of e.g. 30 ° is present and all three adjusting elements then give a surrounding area of 90 °, while the rest of the surrounding area is effected by the enclosure by means of the support elements 23. 55

Claims (13)

The magnetic ring 5 is therefore essentially encompassed over its entire jacket area by the support elements 23 and adjusting elements 26 directed towards it. Advantage of the mold is so that now very sensitive to injection molding forces Mag-5 ning rings can be molded onto a plastic part, without causing damage to this magnetic part. The production takes place in a single shot, because yes with the injection molding of the transmission element 1 and with the insertion of the magnetic ring 5 in the mold, the entire plastic molded part is produced in one operation. This is a significant labor savings compared to the aforementioned mechanical mounts between the magnet ring and plastic injection molding. Drawing legend 1 Gear element 22 Core pin 15 2 Shaft 23 Support element 3 Gearing 24 Direction of arrow 4 Head 25 Radial clearance 5 Plastoferrit ring 26 Adjustment element 6 Axle 27 Adjustment gate 20 7 Conical projection 28 Adjustment ring 8 Struts 29 Stellrampe 9 Approach 30 Direction of arrow 10 Deck surface 31 Form insert 11 Center bore 32 Molding tool (nozzle side) 25 12 Injection point 33 Mold plate 13 Recess 34 External guide element 14 Ring flange 35 Axis 15 Center bore 36 Bore stylus 16 Receptacle 37 Nozzle mouth 30 17 Mold 38 Injection nozzle 18 Receiving groove (for 5) 39 Injection tunnel 19 Slot (for 8) 40 Mold parting plane 20 Cone groove (for 7) 41 Fastening screw 21 Gating channel (for 12) 42 Rolling bearings 35 Claims: 1. Signaling magnetic gear element made of plastic with a shaft (2) carrying a toothing and a magnetic ring acting as a signal element, which is frictionally engaged with the shaft ( 2) is connected because characterized in that the magnet ring is formed as a plastoferrite ring (5) by injection molding on the shaft (2). 2. Magnetic gear element according to claim 1, characterized in that the shank (2j 45 is designed as a thermoplastically produced screw, which is a single or multi-start spiral thread, for example, 1-2-3-4 common threads are possible, However, in this case the maximum pitch is in each case smaller than having a 4-speed spiral with a maximum of 13.76 ° pitch (0.3 modulus) .su 3. Magnetic gear element according to claim 1 or 2, characterized in that both the shaft ( 2) as well as the plastoferrite ring {5) are made of the same magnetically activatable material. 4. Tool for producing a signaling magnetic gear element of Art-55 fabric, characterized in that the plastoferrite ring (5) in the Einleigespritzguss- 9 AT 500 749 B1 tool is fixed by means of special adjusting elements (26) that in a receiving groove (18), in which the Plastoferrit ring (5) is inserted, supporting elements (23) are arranged, which on the outer circumference of the receiving groove (18) a radial clearance of eg 0.01 to 0.02 mm to the inserted Plastoferrit ring (5), and that the Plastoferrit ring (5) integrally formed on the thermoplastic 5 of the shaft (2). 5. Tool according to claim 4, characterized in that the sprue of the injection molded part has a so-called Schirmanguss. 6. Tool according to one of claims 4 to 5, characterized in that the adjusting elements (26) create directly on the outer circumference of the Plastoferrit ring (5). 7. Tool according to one of claims 4 to 6, characterized in that the adjusting elements (26) exert a radially inwardly directed biasing force on the Plastoferrit- 15 ring (5). 8. Tool according to one of claims 4 to 7, characterized in that the adjusting elements (26) are uniformly driven deliverable by a circularly driven adjusting ring (28) in the radial direction. 20 9. Tool according to one of claims 4 to 8, characterized in that depending on the injection pressure, an adjustable, force-transmitting sleeve on the outer circumference of the Plastoferrit ring (5) is applied and this is thereby secured against splashing. 25 10. A method for operating a tool according to one of claims 4 to 9, characterized in that the plastoferrite ring (5) and the thermoplastic worm element is produced by means of a twin-screw injection molding process and in this case the plastoferrite ring is first produced. 30 11. A method of operating a tool according to any one of claims 4 to 9, characterized in that the plastoferrite ring (5) and the thermoplastic worm element have the same material and are produced in a single injection molding process. 12. A method for operating a tool according to one of claims 4 to 9, characterized in that the plastoferrite ring (5) is injection-molded in the injection-plastic injection molding process to the plastic injection molding. 13. A method of operating a tool according to one of claims 4 to 9, characterized 40 characterized in that the radial feed drive of the adjusting elements (26) is adjusted in the direction of the shell of the Plastoferrit ring depending on the injection pressure or of certain sequences during injection molding , 14. The method according to any one of claims 10 to 13, characterized in that the Plasto- 45 ferrite ring (5) already receives a magnetic alignment in the tool. 15. The method according to any one of claims 10 to 13, characterized in that the plastoferrite ring (5) receives a magnetic alignment after demolding from the tool. 50 plus 5 sheets of drawings 55