DE102015001650B4 - Method and injection molding device for the production of injection molded plastic bodies - Google Patents

Abstract

Method for producing injection-moulded plastic bodies (2), in particular interdental cleaners, dental fiddles and/or fins (4), which have yarn (3) overmoulded with plastic in some areas, the yarn (3) to be overmoulded being attached to an injection mold (5, 10) which has at least defines a plastic body (2), and wherein the yarn (3) is overmoulded in at least one yarn section (7) during the injection molding of the plastic body (2) and the at least one plastic body (2) with the overmoulded yarn (3) after the injection molding process is removed from the injection molding tool (5, 10), characterized in that the yarn (3) is clamped on a yarn holding device (8, 12) before it is fed to the injection molding tool (5, 10) and then the injection molding tool (5, 10) together with the yarn holding device (8, 12) is fed.

Description

The invention relates to a method for producing injection-molded plastic bodies, in particular interdental cleaners, toothed violins and/or flossers, which have yarn overmolded with plastic in some areas.

Yarn to be encapsulated is fed to an injection mold that defines at least one plastic body and is encapsulated in at least one yarn section during injection molding of the plastic body, after which the at least one plastic body with the encapsulated yarn is removed from the injection mold after the injection molding process.

The invention also relates to an injection molding device for the production of injection molded plastic bodies, which have yarn overmolded with plastic in some areas, in particular interdental cleaners, dental violins and/or flossers, with an injection molding tool defining at least one plastic body and with a yarn feeding device with which the yarn can be fed to the injection molding tool, and with Means for injection molding the plastic body and for overmoulding the yarn in at least one yarn section.

In addition, a non-claimed plastic body is disclosed with a yarn overmolded in sections, the plastic body having an arcuate or U-shaped yarn carrier at a first end and a grip area at a second end opposite the first end, the yarn between free carrier ends of the yarn carrier is arranged.

From the pamphlets JP 2001 161 444 A and U.S. 6,544,457 B1 methods and injection molding devices of the type mentioned are already known.

The pamphlet DE 88 08 624 U1 discloses a dental cleaning device with a handle on which a holder with two legs is arranged, between which runs at least one thread-like strand of dental floss. The dental cleaning device is characterized in that at least one leg is angled laterally to the long side of the handle at an angle of between 40° and 50°, and that the holder with its two legs and the strand of dental floss are arranged with the handle in a plane of extension such that the Dental floss strand in use position in a plane to runs.

To clean interdental spaces, interdental cleaners, which are also referred to as dental fiddles and/or flossers or flossettes, have become established as a supplement to manual toothbrushes.

The term "flosser" refers to the English terms "floss" (dental floss) or "flossing" (teeth cleaning with dental floss). Such flossers usually have a handle which, like a fork that acts as a yarn carrier, is divided into two tines, between the ends of which at least one thread of dental floss is already clamped. The dental floss is inserted into the spaces between the teeth, the so-called interdental spaces, with the flosser. With the help of this flosser, the interdental spaces can then be cleaned better than with an ordinary manual toothbrush, for example.

The production of such flossers is still carried out in a predominantly manual process, with an operator operating an injection molding machine. In the injection molding machine, an injection mold is arranged, the dental floss must be fed. The dental floss is introduced into cavities for the flossers in order to be surrounded by the plastic compound during injection molding.

The dental floss, also known as yarn, is usually wound onto spools that are positioned near the injection molding tool. The operator now has the task of pulling the dental floss threads by hand from the spools through the open injection mold and inserting them into the corresponding recesses of the injection mold before each injection molding process.

After threading in the yarn, the operator locks the injection molding tool and initiates the injection molding process. A plastic mass is injected and also encloses the dental floss thread of the flossers that are now being manufactured. After completion of the injection molding process, the finished flossers can be ejected or removed from the injection mold. Protruding yarn remnants are usually removed from the fins in separate operations.

A disadvantage of the method described above can be that the correct insertion of the dental floss yarn into the injection molding tool can depend on the accuracy of the operator. Since the production cycles are becoming increasingly shorter, the associated time pressure leads more and more frequently to inaccuracies when threading or pretensioning the yarn, so that it is difficult to ensure consistently high production quality.

The object of the invention is therefore to provide a method and a device for the production of injection-molded plastic bodies whose production and further processing is simplified compared to the prior art.

In order to achieve the stated object, the features of patent claim 1 are proposed in relation to the method according to the invention. In particular, it is therefore proposed in the method of the type mentioned above that the yarn is clamped on a yarn holding device before it is fed to the injection mold and is then fed to the injection mold together with the yarn holding device. In this way, feeding the yarn to the injection mold can be decoupled from the removal of the yarn from a supply, for example a yarn spool. In this way, the production process can be effectively equalized, particularly when using a plurality of yarn holding devices. In this way, an operator can have more time to position the yarn on the yarn holding device with the required accuracy, since he then no longer necessarily has to be bound to the cycle time specified by the manufacturing process when loading or covering the yarn holding device.

In a further embodiment of the method, it can be provided that the yarn holding device is loaded or covered with yarn, that the yarn is transferred from the yarn holding device to the injection mold, after which the yarn transferred to the injection mold is overmolded in at least one yarn section during injection molding of the at least one plastic body and that the overmoulded yarn is removed from the injection mold together with the at least one plastic body by means of the yarn holding device already mentioned or another yarn holding device or is transferred from the injection mold to the same. The plastic body(s) finished in this way can then be fed to further processing steps.

A great advantage of the method according to the invention is that the yarn no longer has to be unwound directly from a supply roll or yarn spool by the operator and then threaded directly into the injection mold before the actual injection molding of the plastic body to be produced can be carried out.

The yarn to be encapsulated can be taken from a yarn supply and first fed to the yarn holding device described above, from which the yarn clamped on the yarn holding device can then be delivered to the injection mold, preferably automatically. The provision of an intermediate step when feeding the yarn to the injection mold has the decisive advantage that the removal of the yarn from the yarn supply is decoupled from the actual injection molding process in the injection mold. In addition, it is possible, in particular with an automated transfer of the yarn from the yarn holding device to the injection mold, to reduce or even avoid inaccuracies that can occur during manual threading, as is still necessary with the methods known from the prior art .

In a particularly advantageous embodiment of the method, it can be provided that the yarn is arranged, in particular stretched, on the yarn holding device in the form of a closed yarn ring.

A closed yarn ring can be produced from an endless strand of yarn, for example by unrolling the yarn from a spool, cutting it to a predetermined length and then connecting the free ends of a yarn section produced in this way by gluing, clamping or splicing. However, it is also conceivable for the yarn to be overmoulded to be obtained in the form of closed yarn rings and/or to be kept available for equipping the yarn holding device.

The use of the twine rings described above can promote rapid and precise loading of the twine holding device(s).

In a preferred embodiment of the method it can be provided that the injection molding takes place in several stages, in particular in two stages. In particular, it can be provided that in a first injection mold at least one pre-moulded part of the plastic body is injected and in a second injection mold the at least one pre-moulded part is overmoulded with a further layer of plastic to complete the plastic body.

In this way, plastic bodies can be produced particularly effectively, which are constructed from two different plastics or else from two differently colored plastics.

It can be expedient if the yarn holding device equipped with yarn transfers the yarn to one or the first injection mold for injection molding of at least one preform of the plastic body and if the yarn holding device, after removal of the yarn with the at least one preform from the first injection mold, transfers the thread together with the transfers at least one preform to one, for example the aforementioned second injection mold. Here, the at least one before injection molding and/or the yarn in the second injection mold with a further layer of plastic, for example the one already mentioned above, to complete the plastic body.

In a slight modification of the method described above, however, it can also be provided that the yarn is transferred from the first yarn holding device to a second yarn holding device together with the at least one preform after removal from the first injection mold.

In another embodiment of the method, it can be provided that the yarn together with the at least one preform is removed from the first injection mold by one or the second yarn holding device or is transferred to it, after which the second yarn holding device takes the yarn that has been overmolded at least in some areas together with the preform to a second injection mold, for example the one already mentioned above. In turn, the at least one pre-moulded part and/or the yarn can be overmoulded with a further layer of plastic in this second injection molding tool to complete the plastic body.

It can be advantageous if the yarn is guided and/or held on the first and/or second yarn holding device and/or on the first and/or second injection mold on actuable holding elements, in particular in notched and/or rotatably mounted holding elements.

In addition, the yarn can be transferred from one yarn holding device to another yarn holding device and/or from one yarn holding device to an injection mold and vice versa, by positioning them relative to one another in such a way that the yarn is released by an actuation, in particular a rotation, of holding elements of one, in particular is transported from a notch of these holding elements onto the holding elements of the other, in particular into a notch of these holding elements. In this way, a largely automated transfer of the yarn between the yarn holding devices and/or the injection molds can be made possible.

For the production of the plastic body, it can also be advantageous if the yarn is pretensioned and/or is kept pretensioned on the first and/or second yarn holding device and/or on the first and/or on the second injection mold. In this way it is namely possible to arrange the yarn under a defined pretension in the injection molding tool and ultimately also in the plastic bodies to be produced during the injection molding process and thus to produce a plastic body with a pretensioned yarn. This in turn can simplify the use of the later plastic bodies, particularly if they are designed as interdental cleaners or flossers.

The yarn can be subjected to a higher tension before the injection molding of the plastic body and/or the preform and/or before it is transferred from one yarn holding device to another yarn holding device or to an injection mold and vice versa by actuating a tensioning device. This can also simplify a reliable and, in particular, automated transfer of the yarn between the individual yarn holding devices and/or injection molds.

At this point it should be pointed out that the yarn used in the method for producing injection-molded plastic bodies can be, for example, dental floss, dental tape, monofilament, multifilament or else a cut from the aforementioned.

In the method it can also be provided that the plastic body is an interdental cleaner or a flosser with a fork-shaped or U-shaped yarn carrier. During the production of the plastic body, the yarn can be overmoulded with plastic in a region of free carrier ends of the yarn carrier in order to attach the yarn to the yarn carrier, preferably under tension.

It is also possible to use more plastic on an outside of the fork-shaped or U-shaped yarn carrier, in particular a convex one, facing away from the yarn than on an inside of the yarn carrier facing the yarn, in particular a concave one, and/or a another layer of plastic is injected. In this way, the yarn carrier can have a greater material thickness on its outside than on its inside facing the yarn.

Arranging a larger amount of material on the usually convex outside of the yarn carrier has a stabilizing effect on the entire plastic body and can therefore simplify the use of the plastic body, but also has another surprising side effect: when this additional layer or overmolding cools down The convex outside of the yarn carrier made of plastic has the effect that the yarn carrier can be tensioned by the cooling of this overmoulding or additional layer, and the injected yarn can also be placed under a higher basic tension.

Especially in the case where several plastic bodies are injection molded at the same time it can be expedient if the yarn is severed after production of the preform and/or the plastic body, in particular on the outside of the thread carrier, in order to separate the preform and/or the finished plastic body.

In order to obtain a plastic body that is also visually appealing, it can also be advantageous if yarn ends that protrude beyond the free carrier ends of the yarn carrier are overmolded and/or overmolded during injection molding, in particular one or the additional layer of plastic already mentioned, preferably completely, so that the ends of the yarn located between the two carrier ends are arranged in the material of the plastic body and do not emerge from the material of the plastic body as a free end.

In the case of the injection molding device defined at the outset, the aforementioned object is achieved by the features of patent claim 11 . According to the invention, it is proposed in particular that the yarn feed device comprises a yarn holding device on which the yarn to be overmolded can be arranged, the yarn holding device fitted with yarn being able to be fed to the injection mold for transferring the yarn to the injection mold.

A handling device can be provided on the injection molding device for, in particular, automated feeding of the yarn holding device equipped with yarn to the injection molding tool.

An injection molding device designed in this way is therefore suitable for carrying out the manufacturing method described above.

It can be expedient if the injection molding device has at least one second injection molding tool. In this way, a pre-moulded part can first be produced with the injection molding device, which is then overmolded in a further process step with the aid of the second injection mold. This further encapsulation can either be of a purely visual nature, especially if you choose a plastic for encapsulation that has a different color than the plastic that was used in the production of the preform, or, as already indicated above, have a stabilizing effect have on the plastic body to be produced.

Especially in connection with the provision of a second injection molding tool, it can also be advantageous if the yarn feed device has at least one second handling unit and/or at least one second yarn holding device. It is thus possible to assign a yarn holding device to each of the existing injection molds and a handling unit to each yarn holding device. In this way, a transfer of the yarn holding devices between the two injection molding tools and/or between an assembly station at which the yarn is placed on the yarn holding device and an injection molding tool can be largely or even completely automated.

It should be pointed out that the handling units described above can, for example, be grippers or robotic grippers that are known per se.

In order to be able to process the yarn under a predefined and desired pretension, it can be expedient if the injection molding device has at least one tensioning device for tensioning the yarn. It should be noted that a clamping device can preferably be assigned to each yarn holding device and/or each injection molding tool. In addition, a tensioning device for the yarn can be arranged on each yarn holding device and/or on each injection molding tool.

In order to cut through the yarn and separate pre-molded parts and/or finished injection-molded plastic bodies, particularly when not just one plastic body but several plastic bodies or pre-molded parts are being produced at the same time, it can be advantageous if the injection molding device has a separating device.

In a further embodiment of the injection molding device according to the invention, it can also be provided that one or the yarn holding devices and/or one or the injection molds have actuable, in particular rotatable, holding elements for the yarn. These holding elements can expediently be designed as rotatably mounted half cylinders. It is also possible for the holding elements, which are designed as half cylinders, to be provided on their curved outer sides with at least one notch or groove for receiving and guiding the yarn.

Depending on the shape of the plastic body to be produced, it can also be advantageous if the yarn holding device(s) has/have at least one additional holder for another functional element to be overmoulded, for example an interdental brush and/or a toothpick, of the plastic body to be produced. In this way it is possible, in one of often several injection molding process steps, to provide functional elements on the yarn holding device encapsulate and attach to the plastic body on these functional elements in a manner similar to the yarn to be encapsulated.

As mentioned at the outset, a non-claimed plastic body is also described. The plastic body is characterized in that the curved or U-shaped yarn carrier is provided with a thicker plastic layer on its outside facing away from the yarn than on its inside facing the yarn. This thicker plastic layer can preferably be formed by an overmolding made of plastic. The thicker plastic layer on the usually convex outside of the yarn carrier can have the advantage that when the plastic applied on the outside cools down, it contracts and leads to additional tension in the forked, arched or U-shaped yarn carrier and thus also to a tension of the yarn arranged between the free ends of the beam.

Furthermore, a non-claimed plastic body is also disclosed, in which it is provided that ends of the yarn arranged between the free carrier ends of the yarn carrier are arranged inside the plastic body, i.e. not as free yarn ends from the plastic body, in particular from the free carrier ends of the yarn carrier protrude in a disturbing manner.

It should be pointed out that the plastic bodies described above can be designed as interdental cleaners, flossers or as tooth violins. The yarn used in these plastic bodies can be dental floss, dental tape, monofilament, multifilament, or a cut of any of the foregoing.

• 1: Eine schematische Darstellung einer erfindungsgemäßen Spritzgießvorrichtung mit einem Spritzgießwerkzeug , das zwei über eine Drehvorrichtung miteinander verbundene auswerferseitige Formhälften und eine düsenseitige Formhälfte aufweist, mit einer mit Garn bestückten Garnhaltevorrichtung vor einer Übergabe des Garns an das Spritzgießwerkzeug und mit einer weiteren Garnhaltevorrichtung, in der das aufgespannte Garn sowie insgesamt acht spritzgegossene und über Angussstreben miteinander verbundene Kunststoffkörper zu erkennen sind,
• 2: eine weitere Darstellung einer erfindungsgemäßen Spritzgießvorrichtung, die im Vergleich zu der in 1 dargestellten Spritzgießvorrichtung um ein zweites, im Wesentlichen baugleiches Spritzgießwerkzeug erweitert ist, wobei eine erste Garnhaltevorrichtung mit einem aufgespannten Garnring und eine zweite Garnhaltevorrichtung mit einem aufgespannten Garnring und insgesamt acht spritzgegossenen Vorspritzlingen in einer Position zwischen dem ersten und dem zweiten Spritzgießwerkzeug und dieselbe Garnhaltevorrichtung in einer weiteren Position nach Entnahme der fertig spritzgegossenen Kunststoffkörper aus dem zweiten Spritzgießwerkzeug zu erkennen ist,
• 3: eine erste Ausführungsform eines nicht beanspruchten und als Flosser ausgebildeten Kunststoffkörpers mit einem bereichsweise umspritzten Garn,
• 4: eine Explosionsdarstellung des in 3 dargestellten Flossers,
• 5: eine zweite Ausführungsform eines nicht beanspruchten und als Flosser ausgebildeten Kunststoffkörpers wobei zu erkennen ist, dass der Garnträger dieses Kunststoffkörpers derartig mit einer Umspritzung versehen ist, dass Garnenden im Material der Umspritzung angeordnet sind, also nicht wie bei dem Ausführungsbeispiel gemäß 3 überstehen, sowie
• 6: eine Explosionsdarstellung des in 5 dargestellten Flossers.

Exemplary embodiments of the invention are described in more detail below with reference to the drawings. It shows in a partly highly schematized representation:

• 1 : A schematic representation of an injection molding device according to the invention with an injection mold that has two mold halves on the ejector side connected to one another via a rotary device and a mold half on the nozzle side, with a yarn holding device equipped with yarn before the yarn is transferred to the injection mold and with a further yarn holding device in which the clamped Yarn and a total of eight injection-moulded plastic bodies connected to one another via sprue bars can be seen,
• 2 : a further illustration of an injection molding device according to the invention, which, in comparison to that in 1 The injection molding device shown is expanded by a second, essentially structurally identical injection mold, with a first yarn holding device with a stretched yarn ring and a second yarn holding device with a stretched yarn ring and a total of eight injection-molded preforms in one position between the first and second injection mold and the same yarn holding device in another Position can be seen after removal of the finished injection-molded plastic body from the second injection mold,
• 3 : a first embodiment of a non-claimed plastic body designed as a flosser with a yarn overmolded in some areas,
• 4 : an exploded view of the in 3 depicted flossers,
• 5 1: a second embodiment of a plastic body designed as a flosser, wherein it can be seen that the yarn carrier of this plastic body is provided with an overmolding such that yarn ends are arranged in the material of the overmolding, i.e. not as in the exemplary embodiment according to FIG 3 survive, as well
• 6 : an exploded view of the in 5 illustrated flossers.

First, the structure of the injection molding device according to the invention will be explained in more detail with reference to the figures.

the 1 and 2 show an injection molding device, designated as a whole by 1, which is suitable for carrying out the method described above and explained in more detail below.

The injection molding device 1 is used to produce injection-molded plastic bodies 2, which have yarn 3 overmolded with plastic in some areas.

The in the 1 until 6 The plastic bodies 2 shown are designed as so-called interdental cleaners or flossers 4 . The injection molding device 1 has in the present case a total of eight plastic bodies 2 defining injection mold 5 and a yarn feed device 6, with the yarn 3 can be fed to the injection mold 5 in a clamped form.

Furthermore, the injection molding device is equipped with means 45 for injection molding the plastic body 2 and for overmoulding the yarn 3 in at least one yarn section 7 .

The yarn feed device 6 comprises a yarn holding device 8 and a handling device 9. The yarn 3 to be overmolded can be arranged on the yarn holding device 8 and the yarn holding device 8 equipped with yarn 3 can be fed to the injection mold 5 for transferring the yarn 3 to the injection mold 5. The feeding takes place by means of the handling unit 9.

Based on the in 2 In the illustrated exemplary embodiment of the injection molding device, the injection molding device 1 has at least one second injection mold 10 and the yarn feed device 6 has at least one second handling unit 11 and also a second yarn holding device 12 .

the 1 and 2 show that each of the two injection molds 5 and 10 has a nozzle-side mold half 13 and two ejector-side mold halves 14a and 14b with cavities 15 defining the plastic bodies 2. The yarn 3 is introduced into these cavities 15 with the aid of the yarn holding devices 8, 12 in order to overmold it at least in regions during the injection molding of the plastic body 2.

It should be pointed out that the two mold halves 14a and 14b on the ejector side of the injection molds 5 and 10 are constructed identically. While one mold half 14a is inserted in the injection mold 5 or 10 so that the plastic body 2 can be injected, the other mold half 14b is ready to be loaded with yarn 3 (cf. 1 and 2 ). This enables a largely uninterrupted production process.

the 1 and 2 10 further show that each yarn holding device 8 and 12 and each injection mold 5 and 10 each have at least one tensioning device 16 for tensioning the yarn 3 in the respective injection mold 5 and 10 or in the respective yarn holding device 8 and 12.

The injection molding device 1 is also equipped with a separating device 17, which is used for severing the yarn and separating pre-molded parts 18 (cf. 2 ) And / or finished injection molded plastic bodies 2 can be used.

The yarn 3 can then be severed in a manner known per se mechanically or, for example, also thermally with the aid of a flame, a hot blade or a laser.

the 1 and 2 12 also show that the yarn holding devices 8 and 12 and each of the two injection molds 5 and 10 have holding elements 19 that can be actuated. These are designed as rotatably mounted half cylinders 20 which are each provided on their curved outer sides 21 with at least one notch or groove 22 for receiving and guiding the yarn 3 .

The in the 1 and 2 Yarn holding devices 8 and 12 shown consist of an x-shaped or cross-shaped base support 23 which has a total of four free support arms 24 .

At the ends of the support arms 24 four holding elements 19 designed as half cylinders 20 are rotatably mounted. In addition, the tensioning device 16 for the yarn 3 assigned to one of the yarn holding devices 8 or 12 is also arranged on one of the carrier arms 24 .

The holding elements 19 of the injection molding tools 5 and 10, which are designed as half cylinders 20 and are also rotatably mounted, are arranged on the two mold halves 14a and 14b in a very similar way. The clamping devices 16 are also provided on the two mold halves 14a and 14b of the two injection molds 5 and 10 that have the holding elements 19 .

The mold halves 14a and 14b in FIGS 1 and 2 The injection molding tools 5 and 10 shown are connected to one another via a rotary device 25 . This rotating device 25 serves to move the two mold halves 14a and 14b from a closed position into one 1 and 2 shown open position, in which the yarn 3 is transferred from the respective yarn holding device 8 and 12 to the corresponding mold half 14a or 14b.

The two mold halves 14a and 14b can be brought from their open position to their closed position on the nozzle-side mold half 13 by means of a 180° rotation about an axis A by means of the rotating device 25 .

In the 1 and 2 the mold halves 14a are each shown in their closed position on the mold halves 13 and cover them. The mold halves 14b are in both 1 and 2 shown in their open positions and are ready for loading with yarn 3.

At this point it should be mentioned that the yarn 3 stretched on the respective yarn holding device 8 and 12 can be applied in the form of a closed yarn ring 26 to the respective yarn holding device 8 and 12 and can be stretched there with the aid of a hammer-shaped clamping device 16 .

Since the individual injection-moulded plastic bodies 2 are connected to one another via a so-called sprue 27, they can be laid down in a defined manner in a simple manner after injection molding has taken place and, if necessary, transported further to downstream processing stations.

• Das Verfahren dient der Herstellung von spritzgegossen Kunststoffkörpern 2, insbesondere Interdentalreinigern, Zahngeigen oder, wie im vorliegenden Fall, Flossern 4. Diese Flosser 4 weisen bereichsweise mit Kunststoff umspritztes Garn 3 auf, wobei zu umspritzendes Garn 3 dem Spritzgießwerkzeug 5, 10, das wenigstens einen und im vorliegenden Ausführungsbeispiel insgesamt acht Kunststoffkörper 2 definiert, zugeführt wird.

The method or injection molding method described below can be carried out on the injection molding device 1 described above:

• The method is used to produce injection-molded plastic bodies 2, in particular interdental cleaners, dental fiddles or, as in the present case, flossers 4. These flossers 4 have yarn 3 overmoulded with plastic in some areas, with yarn 3 to be overmoulded being attached to the injection mold 5, 10, which has at least one and in the present embodiment, a total of eight plastic bodies 2 defined, is supplied.

The yarn is encapsulated in at least one yarn section 7 during injection molding of the plastic body 2 . After production, the plastic bodies 2 with the overmoulded yarn 3 can be removed from the respective injection mold 5, 10. The method provides that the yarn holding device 8, 12 is loaded with yarn 3, that the yarn holding device 8, 12 loaded with yarn 3 transfers the yarn 3 to the injection mold 5, 10, that the yarn 3 transferred to the injection mold 5, 10 the plastic body 2 is overmoulded in at least one yarn section 7 during injection molding and that the overmoulded yarn 3 is removed from the injection mold 5, 10 together with the plastic bodies 2 produced by means of the or another yarn holding device 8, 12. As already mentioned above, the yarn 3 is arranged on the respective yarn holding device 8, 12 in the form of a closed yarn ring 26, in the present case clamped.

The yarn 3 can be removed as an endless strand from a yarn store, in particular from a yarn spool, in a preceding method step and severed from the endless strand in a defined length. It is then possible to form the yarn ring 26 described above by gluing, clamping, splicing or otherwise connecting free yarn ends of the yarn 3 to one another. However, it is also possible to provide already prefabricated yarn rings 26 and to clamp them on the yarn holding devices 8, 12.

the inside 1 The arrow Pf1 illustrated here illustrates the insertion direction, i.e. the direction in which the yarn holding device 8, 12 is moved by means of the handling unit 9, 11 to the injection molding tool 5, 10 or to one of the two mold halves 14a, 14b of the respective injection molding tool 5, 10 . the inside 1 The arrow labeled Pf2 illustrates the removal direction, i.e. the direction in which the respective yarn holding device 8, 12 is moved together with the plastic bodies 2 or together with the preforms 18 to remove the yarn 3 or the yarn ring 26. Analogous arrows Pf1 and Pf2 can also be found in the representation according to FIG 2 . In this representation, however, further arrows Pf3 and Pf4 are shown, which illustrate the direction of insertion or removal into or from the second injection mold 5, 10.

According to 2 At least one pre-moulded part 18 of the plastic body 2 is injected in a first injection mold 5 and the at least one pre-moulded part 18 is overmoulded with a further layer 28 of plastic in a second injection mold 10 to complete the plastic body 2 .

That based on 1 and 2 The method illustrated provides that the yarn holding device 8 equipped with yarn 3 transfers the yarn 3 to the first injection mold 5 for injection molding of the total of eight preforms 18 of the plastic body 2 and that the yarn holding device 12 after removal of the yarn with the total of eight via the sprue 27 together connected preforms 18 from the first injection mold 5 transfers the yarn 3 together with the eight preforms 18 to the second injection mold 10.

When the yarn 3 is transferred to the injection molds 5, 10, the present embodiment of the method provides that the yarn 3 is released from the respective yarn holding device 8, 12 to a mold half 14a or 14b of the respective injection mold 5, 10. By moving the mold half 14a or 14b equipped with yarn 3, this then moves together with the yarn 3 into the position on the mold half 13 in which the yarn 3 is partially inserted during the production of the plastic body 2 in the cavities 15 of the injection mold 5, 10 can be overmolded.

In the second injection mold 10, the eight preforms 18 and the yarn 3, which is also present as a yarn ring 26, are overmoulded with the additional layer 28 of plastic to complete the plastic body 2. The yarn 3 can be transferred from the first yarn holding device 8 to the second yarn holding device 12 together with the eight preforms 18 after removal from the first injection mold 5 . The yarn 3 and the eight preforms 18 are then transported to the second injection mold 10 with the aid of the second yarn holding device 12 . It is also It is possible for the yarn 3 to be removed from the first injection mold 5 together with the eight preforms 18 by the second yarn holding device 12, after which the second yarn holding device 12 transfers the yarn 3, which has been overmolded at least in some areas, together with the eight preforms 18 to the second injection mold 10, in in which the eight preforms 18 and the yarn 3 are overmoulded with a further layer 28 of plastic to complete the plastic body 2 . Furthermore, it is conceivable to use one and the same yarn holding device 8 for transferring and removing the yarn 3 to or from the first injection mold 10 and for transferring and removing the yarn 3 together with the plastic bodies 2 or preforms 18 from the second injection mold 10 or 12 to use.

The yarn 3 is guided and held on both yarn holding devices 8, 12 and on both injection molding tools 5, 10 on the actuatable, rotatably mounted holding elements 19 provided with notches 22. The yarn 3 can be transferred from one yarn holding device 8, 12 to another yarn holding device 8, 12 and from one yarn holding device 8, 12 to an injection mold 5, 10 and vice versa by positioning them relative to one another in such a way that the yarn 3 can be , in particular a rotation, is transported from holding elements 19 of one to the holding elements 19 of the other. The yarn 3 can be moved from the notch 22 of the holding elements 19 of one into the notch 22 of the holding elements 19 of the other, be it a yarn holding device 8, 12 or an injection mold 5, 10. The yarn 3 is held biased and biased at each of the yarn holding devices 8,12 and at each of the two injection molds 5,10.

All of the holding elements 19 shown in the figures have the same structure and consist of a rotatably mounted semi-cylinder 20 which has a notch 22 on its convex outer side 21 for guiding the yarn 3 .

Both the injection molds 5 and 10 and the yarn carrier devices 8 and 12 have four holding elements 19 .

In the method it can also be provided that the yarn 3 before the injection molding of the plastic body 2 and/or the pre-molded parts 18 and before a transfer from one yarn holding device 8, 12 to another yarn holding device 8, 12 or to an injection mold 5, 10 by actuation the clamping device 16 is placed in a higher voltage.

The yarn 3 processed in the method can be dental floss, dental tape, monofilament or multifilament or a cut from the aforementioned.

The plastic bodies 2 produced with the method are designed as interdental cleaners or flossers 4 each with a fork-shaped or U-shaped yarn carrier 29 . During the production of the plastic bodies 2, the yarn 3 is overmoulded with plastic in a region of free carrier ends 30, 31 of the yarn carrier 29. This serves to attach the yarn 3 to the yarn carrier 29, preferably under tension.

According to the 2 In the method illustrated, in a second process step, more plastic is applied to a convex outside 32 of the fork-shaped or U-shaped yarn carrier 29 facing away from the yarn 3 than to a concave inside 33 of the yarn carrier 29 facing the yarn 3 in the form of a further layer 28 made of plastic injected. This takes place in the second injection molding tool 10. In this way, the yarn carrier 29 is given a greater material thickness on its convex outer side 32 than on its inner side 33 facing the yarn 3. The yarn 3 can be molded after the production of the preforms 18, but preferably only after the production of the plastic body 2, in particular on the outsides of the yarn carrier, are severed in order to separate the preforms 18 or the finished plastic bodies 2 from one another and to isolate them. However, it is also possible to overmold yarn ends 34, 35 protruding beyond the free support ends 30, 31 of the yarn carrier 29 during injection molding of, for example, the previously mentioned additional layer 28 of plastic, preferably completely.

• Die Kunststoffkörper 2 sind mit einem abschnittsweise umspritzten Garn 3 versehen. An einem ersten Ende 36 weist der Kunststoffkörper 2 den Gabel- oder U-förmigen Garnträger 29 und an einem dem ersten Ende 36 gegenüber liegenden zweiten Ende 37 einen Griff- oder Haltebereich 38 auf. Wie die Figuren deutlich zeigen, ist das Garn 3 zwischen den freien Trägerenden 30, 31 des Garnträgers 29 angeordnet bzw. eingespannt. Der Gabel- oder U-förmige Garnträger 29 ist gemäß beiden Ausführungsbeispielen an seiner konvexen Außenseite 32 mit einer dickeren Kunststoffschicht in Form einer zusätzlichen Lage 28 aus Kunststoff als an seiner konkaven Innenseite 33 versehen. Die an der konvexen Außenseite 32 des Garnträgers 29 vorgesehene dickere Kunststoffschicht oder Lage 28 aus Kunststoff ist von einer Umspritzung aus Kunststoff, die je nach Wunsch eine andere Farbe haben kann als der Kunststoff, der zum Spritzgießen der Vorspritzlinge 18 verwendet wird, gebildet.

The plastic bodies 2 and Flosser 4 produced on the injection molding device 1 by the method described above are in the 3 until 6 shown:

• The plastic bodies 2 are provided with a yarn 3 overmolded in sections. The plastic body 2 has the fork-shaped or U-shaped yarn carrier 29 at a first end 36 and a gripping or holding area 38 at a second end 37 opposite the first end 36 . As the figures clearly show, the yarn 3 is arranged or clamped between the free carrier ends 30, 31 of the yarn carrier 29. According to both exemplary embodiments, the fork-shaped or U-shaped yarn carrier 29 is provided with a thicker plastic layer in the form of an additional layer 28 made of plastic on its convex outer side 32 than on its concave inner side 33 . The provided on the convex outer side 32 of the yarn carrier 29 thicker plastic layer or layer 28 made of plastic is from an overmolding made of plastic, depending on may be a different color than the plastic used to injection mold the preforms 18 if desired.

While the yarn ends 34, 35 at the in 3 illustrated embodiment of the plastic body 2 or flosser 4 protrude beyond the two carrier ends 30, 31 of the yarn carrier 29, the yarn ends 34, 35 of the yarn 3 are in the in 3 illustrated embodiment of the plastic body 2 or the flosser 4 is arranged within the plastic body 2, so do not project beyond the two carrier ends 30, 31 of the yarn carrier 29.

• Zum einen weist der Kunststoffkörper 2/der Flosser 4 an seinem zweiten Ende 37 eine Interdentalbürste 39 aus eingedrehten Drähten auf. Zudem ist der Haltebereich 38 des Kunststoffkörpers 2/des Flossers 4 von einer Knicklinie 40 durchzogen, die eine Materialschwächung des Haltebereichs 38 darstellt und entlang derer der Haltebereich 38 umgeknickt werden kann. Im Bereich der Knicklinie 40 ist zum Anderen ein zweischenkliges Kunststoffelement 41 angeordnet, kann dieses durch ein Abknicken des Haltebereichs 38 entlang der Knicklinie 40 aus seiner in den 3, 4, 5 und 6 dargestellten Nichtgebrauchsstellung herausbewegt oder herausgebrochen und dann als Zahnstocher benutzt werden.

The two in the 3 , 4 , 5 and 6 The plastic body 2 or flosser 4 shown shows that the plastic body 2/flosser 4 is equipped with two further functional elements at its second end 37:

• On the one hand, the plastic body 2/the flosser 4 has an interdental brush 39 made of twisted wires at its second end 37. In addition, the holding area 38 of the plastic body 2/the flosser 4 is traversed by a fold line 40, which represents a material weakening of the holding area 38 and along which the holding area 38 can be folded over. In the area of the fold line 40, on the other hand, a two-legged plastic element 41 is arranged; 3 , 4 , 5 and 6 moved out of the non-use position shown or broken out and then used as a toothpick.

In order to increase comfort when using the plastic element 41 arranged in the holding area 38 and to prevent the bent holding area 38 from moving back into its original position on its own, the holding area 38 of the plastic body is also equipped with a locking device 42. This locking device 42 consists of two parts 43 and 44, one of which is arranged on one side of the fold line 40 in each case. The two parts 43, 44 of the locking device 42 are arranged at the same distance from the fold line 40 and can, similar to a push button, be brought into engagement with one another when the holding area 38 is flexed along the fold line into a latching position.

At least the yarn holding device 8 has two additional holders 46 for the interdental brushes 39 . In this way, the interdental brushes can be fed together with the yarn 3 to the injection molding tool 5 and 10 during injection molding of the plastic body 2 so that it can be attached to the plastic body.

the 1 and 2 12 show that corresponding cavities 47 are formed in the mold halves 13 and 14a and 14b for receiving and for encapsulating the interdental brushes 39.

Before the yarn 3 is fed to the injection mold 5, 10 of the injection molding device 1 according to the invention, the yarn 3 is clamped on a yarn holding device 8, 12 and then fed to the injection mold 5, 10 together with the yarn holding device 8, 12, in order to a non-claimed plastic body 2, which is designed in particular as a flosser 4, to be overmolded at least in regions.

Reference List

1

injection molding device

2

plastic body

3

yarn

4

flosser

5

injection mold

6

yarn feeding device

7

yarn section

8th

twine holding device

9

handling device

10

injection mold

11

handling device

12

twine holding device

13

mold half

14a

mold half

14b

mold half

15

cavity

16

clamping device

17

separator

18

preform

19

holding element

20

half cylinder

21

outside

22

notch or groove

23

base carrier

24

carrier arms

25

rotating device

26

yarn ring

27

sprue

28

another layer of plastic

29

yarn carrier

30

free beam end of 29

31

free beam end of 29

32

outside of 29

33

Inside of 29

34

yarn end

35

yarn end

36

first end of 2

37

second end of 2

38

grip or holding area

39

interdental brush

40

crease line

41

two-legged plastic element

42

locking device

43

part of 42

44

part of 42

45

Means for injection molding the plastic body

46

additional holder

47

Cavity for injection molding of interdental brushes

Claims (16)

Process for producing injection-moulded plastic bodies (2), in particular interdental cleaners, dental fiddles and/or fins (4), which have yarn (3) overmoulded with plastic in some areas, the yarn (3) to be overmoulded being attached to an injection mold (5, 10) which has at least defines a plastic body (2), and wherein the yarn (3) is overmoulded in at least one yarn section (7) during the injection molding of the plastic body (2) and the at least one plastic body (2) with the overmoulded yarn (3) after the injection molding process is removed from the injection molding tool (5, 10), characterized in that the yarn (3) is clamped on a yarn holding device (8, 12) before it is fed to the injection molding tool (5, 10) and then the injection molding tool (5, 10) together with the yarn holding device (8, 12) is fed. procedure after claim 1 , characterized in that the yarn holding device (8, 12) is covered with yarn (3), that the yarn (3) is transferred from the yarn holding device (8, 12) to the injection molding tool (5, 10), that the injection molding tool (5, 10) transferred yarn (3) is overmoulded in at least one yarn section (7) during injection molding of the at least one plastic body (2) and that the overmoulded yarn (3) together with the at least one plastic body (2) by means of the or a further Yarn holding device (8, 12) is removed from the injection mold (5, 10) or transferred to it by the injection mold (5, 10). procedure after claim 1 or 2 , characterized in that the yarn (3) is arranged, in particular stretched, on the yarn holding device (8, 12) in the form of a closed yarn ring (26). Procedure according to one of Claims 1 until 3 , characterized in that in a first injection mold (5, 10) at least one pre-moulded part (18) of the plastic body (2) is injected and in a second injection mold (5, 10) the at least one pre-moulded part (18) for completing the plastic body (2) is overmoulded with a further layer (28) of plastic. Procedure according to one of Claims 1 until 4 , characterized in that the yarn holding device (8, 12) fitted with yarn (3) transfers the yarn (3) to a or the first injection mold (5, 10) for injection molding of at least one pre-moulded part (18) of the plastic body (2) and that the yarn holding device (8, 12), after the yarn (3) with the at least one preform (18) has been removed from the first injection mold (5, 10), transfers the yarn (3) together with the at least one preform (18) to one or the second Injection molding tool (5, 10), wherein in the second injection molding tool (5, 10) the at least one preform (18) and/or the yarn (3) with one or the other layer (28) of plastic to complete the plastic body (2) is overmoulded, or that the yarn (3) is transferred from the first yarn holding device (8, 12) to a second yarn holding device (8, 12) together with the at least one preform (18) after removal from the first injection mold (5, 10). becomes or that the yarn (3 ) together with the at least one preform (18) is removed from the first injection molding tool (5, 10) by one or the second yarn holding device (8, 12), after which the second yarn holding device (8, 12) inserts the yarn (3) overmolded at least in certain areas together with the at least one preform (18) to one or the second injection mold (5, 10), in which the at least one preform (18) and/or the yarn (3) is combined with a further layer (28) of plastic to complete the Plastic body (2) is overmoulded. Procedure according to one of Claims 1 until 5 , characterized in that the yarn (3) on the first and/or second yarn holding device (8, 12) and/or on the first and/or second injection molding tool (5, 10) is actuatable, in particular notched and/or rotatably mounted , Holding elements (19) is guided and / or held and / or that the yarn (3) from a yarn holding device (8, 12) to another yarn holding device (8, 12) and / or from a yarn holding device (8, 12). injection mold (5, 10) and vice versa by positioning them relative to each other in such a way that the yarn (3) is released by an actuation, in particular a rotation, of holding elements (19) of one, in particular from a notch (22) of these holding elements (19) onto the holding elements (19) of the other, in particular into a notch (22) of these holding elements (19). Procedure according to one of Claims 1 until 6 , characterized in that the yarn (3) is pretensioned and/or held pretensioned on the first and/or second yarn holding device (8, 12) and/or on the first and/or on the second injection mold (5, 10). Procedure according to one of Claims 1 until 7 , characterized in that the yarn (3) before the injection molding of the at least one plastic body (2) and/or one or the at least one preform (18) and/or before a transfer from one yarn holding device (8, 12) to another yarn holding device (8, 12) or to an injection molding tool (5, 10) and vice versa by actuating a clamping device (16) to a higher voltage. Procedure according to one of Claims 1 until 8th , characterized in that the plastic body (2) is an interdental cleaner or a flosser (4) with a fork or U-shaped yarn carrier (29), the yarn (3) during the production of the plastic body (2) in a range of free carrier ends (30, 31) of the yarn carrier (29) is overmoulded with plastic in order to attach the yarn (3) to the yarn carrier (29), preferably under tension, and/or that on a yarn (3) facing away, in particular convex outer side (32) of the forked or U-shaped yarn carrier (29), in particular in a second process step, more plastic than on a preferably concave inner side (33) of the yarn carrier (29) facing the yarn (3) and/or or a further layer (28) of plastic is injection-molded on, so that the yarn carrier (29) has a greater material thickness on its outside (32) than on its inside (33) facing the yarn (3). Procedure according to one of Claims 1 until 9 , characterized in that the yarn (3) is severed after production of the preform (18) and/or the plastic body (2), in particular on the outer sides (32) of the thread carrier, in order to separate the preform (18) and/or the finished plastic body (2 ) and/or that yarn ends (34, 35) protruding beyond the free carrier ends (30, 31) of the yarn carrier (29) are injection molded around and/or overmolded, preferably completely, during injection molding of one or the other layer (28) of plastic . Injection molding device (1) for producing injection-moulded plastic bodies (2), which have yarn (3) overmoulded with plastic in some areas, in particular interdental cleaners, toothed violins and/or fins (4), with an injection mold (5, 10 ) and with a yarn feed device (6) with which the yarn (3) can be fed to the injection mold (5, 10), and with means for injection molding the plastic body (2) and for overmoulding the yarn (3) in at least one yarn section (7) , characterized in that the yarn feed device (6) comprises a yarn holding device (8, 12) on which the yarn (3) to be encapsulated can be arranged, the yarn holding device (8, 12) equipped with yarn (3) being attached to the injection mold (5, 10) for transferring the yarn (3) to the injection mold (5, 10) can be fed. Injection molding device (1) after claim 11 , characterized in that a handling device (9, 11) is provided for feeding the yarn holding device (8, 12) equipped with yarn (3) to the injection mold (5, 10). Injection molding device (1) after claim 11 or 12 , characterized in that the injection molding device (1) has at least one second injection mold (10) and/or that the yarn feed device (6) has at least one second handling unit (11) and/or at least one second yarn holding device (12). Injection molding device (1) according to one of Claims 11 until 13 , characterized in that the injection molding device (1) has at least one tensioning device (16) for tensioning () the yarn (3), with each yarn holding device (8, 12) and/or each injection molding tool (5, 10) preferably having a tensioning device (16 ) assigned. Injection molding device (1) according to one of Claims 11 until 14 , characterized in that the injection molding device (1) has a separating device (17) for severing the yarn (3) and for separating pre-molded parts (18) and/or finished injection-molded plastic bodies (2). Injection molding device (1) according to one of Claims 11 until 15 , characterized in that one or the yarn holding devices (8, 12) and/or one or the injection molds (5, 10) have actuable, in particular rotatable, holding elements (19) for the yarn (3), the holding elements (19) preferably are designed as rotatably mounted semi-cylinders (20) and/or are each provided with at least one notch or groove (22) on curved outer sides (21) for receiving and guiding the yarn (3).

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