DE4127621A1 - Injection mould for e.g. toothbrush(es) - has revolving inner tool so that first shot is injected into one end before it is turned and second shot enters e.g. other end of cavities - Google Patents

Abstract

A machine for the production of brushes has an injection mould to make the bodies of the e.g. toothbrushes or similar, where the bodies concerned consist of a number of successively injected parts (particularly away from their heads); for the purpose the mould has a revolving tool and impressions which are preferably arranged on opposite sides of the centre plane running through that revolving tool; the system has a fixed mould plate on the gate side, another plate on the ejector side and a centre revolving component with a shaft passing through the centre of the latter plate; this component has a device to hold the punches for the bristle holes made later in the head of the brush; and the punches provide a holder for the bristles when the component revolves. The ends of the mould impressions for the head or holding part face together the plane through the centre line and also the revolving component; the part of the impressions to produce the brush head where a second shot of material is injected in a further operation faces outwards away from the centre line plane in the plate on the ejector side. ADVANTAGE - The machine has a simple design. It simplifies production. Its mould has a long service life. The whole machine is compact

Description

The invention relates to a brush manufacturing machine machine with an injection mold for the production of plastic Brush bodies for toothbrushes or the like, the Brush body in some areas, especially outside of it Head area, from several, one after the other injected Kompo Nenten exist and the injection mold as a turning tool with respect to a longitudinal center running through the turning axis living opposite nests is formed, which Turning tool a fixed die plate on the nozzle side, one ejector-side mold plate and one of the ejectors as a turning part assigned to the rear mold plate, on one of these centrally has penetrating sliding shaft mounted middle part which one for the later head-side bristle perforation field Punch holder device is provided, which in the Hole punch engaging punch a head-side bracket form for the brush body during the turning process.

With conventional multiple injection molds, this is from one system of flow paths (distribution channels) existing so ge designed that the liquid mass the  through mold cavities (mold cavities) enough. The sprue bushing for coupling the spray nozzle of the Accordingly, the injection unit on the injection mold is preferred centrally and in an extension of the central mold axis. At elongated moldings such as toothbrushes for the above, technical reasons for injection injection or sprue facing each other and to the mold axis directed.

In the case of toothbrushes, these sprue heads are in the back Handle end area, otherwise they would be arranged at the end of the brush head risk of injury in the mouth if used later can represent rich.

Building on this state of the art is already known Injection molding machines of the type mentioned at the beginning with one Turning tool for spraying the best of several components brushes, for example two-tone toothbrushes. In these, a base body is first injected, which follows this injection molding process remains in the part of the mold half where no changes are made. After this he The main injection molding process is the tool holding the base body rotated by 180 degrees, for example, and so the basic body supplied second spraying process. With this second spraying Then, for example, there is a partial encapsulation of the base body, so that the end product is, for example, a two- or multicolored toothbrush body.

After the first spraying process, the base body is replaced by in shaped pins engaging the holes of the later bristle field held. In the remaining area of the base body can in the second injection molding operations are carried out. Around to realize this in the grip area it is already known in the case of whom the base body is held on the outside at the head end to provide openings in the grip areas, through the mold cores of the ejector-side, movable mold  can reach through the plate. The mold cores are on the two Reversible sides designed differently, with the first Spraying part of the mold for the base body and at second injection molding part of the mold for the extrusion coating form.

These mold cores must each be turned before turning the turning part be brought out of its area. This is done by the La the turning part and the ejector-side mold plate on a sliding shaft passing through it, on which also a rack-working gear for the rotation drive is mounted. Because of the large rotational mass of thrower-side molding plate, the sliding shaft for transmission the high forces as an elaborate multi-tooth shaft be.

In the manufacture of the injection mold, it has proven to be very elaborately exposed, the breakthroughs in the turning part to work out. This is done by spark erosive wire snow which, although very much in accordance with the requirements is precise, but requires a high cost, especially since generally correspond to a number of such breakthroughs double the number of products to be ejected in one operation Brush bodies are provided.

It is also expensive that the mold cores are very precise in this Breakthroughs need to be adjusted so that the late Ren brush bodies show no undesirable dividing lines. There both parts - turning part with openings on the one hand and the movable mold plate on the other hand - but movable to each other are arranged, it is inevitable here that at the parting surfaces or their edges are showing signs of wear, which eventually lead to such seams. Due to this fact the tool life is significantly limited. The signs of wear that occur are repara only with a very high expenditure of time and money bel.  

As already mentioned, the turning part has a large mass and thus a large moment of inertia on what is happening in the drive causes increased wear. Generally one is Rack provided as a drive with one on the lot gear shaft mounted gear works together. Ver wear both the multi-toothed shaft and that together with it menive gear rack drive comparatively fast.

The object of the present invention is a Bust making machine of the type mentioned with egg ner injection mold in to simplify the design Overall reduce manufacturing costs significantly and Increase the service life of the injection mold. In addition, one compact design also with regard to injection molding form interacting injection molding machine, may be possible.

To solve this problem, the invention proposes that the mold nests with their at least the brush head or the same holding area ends approximately to each other and facing the longitudinal median plane and with these ends on the Reversible part are arranged and that part of the mold nests for the area of the brush body in which in another Another spray material component is sprayed is groundbreaking from the longitudinal median plane to the outside located in the ejector-side mold plate.

By arranging the with their preferably brush head egg The holding area facing each other can form cavities The turning part is dimensioned with regard to its outer dimensions be that it is only the top and center Form ends covered. The turning part can thus be much smaller ner and therefore especially with regard to his rotati ons inertia mass can be significantly reduced.  

This reduced rotational mass advantageously allows Way a simplification of the drive transmission and also less wear.

A significant advantage results from the very considerable reduced effort in the production, since now the turning part no complex to manufacture and susceptible to wear Breakthroughs more for reaching through the cores of the die rear, movable molded part required.

The injection mold belonging to the brush making machine can also be made much more compact by the invention as the one required for turning the turning part Space due to its smaller and more practical design example, halved outer dimensions, also reduced is. This also allows the injection mold between Füh Place pillars with a smaller side distance. The Ab stand of the guide rails defines the size of the to be connected Spraying machine firmly, so that now an adjustment and optimization between the required closing pressure of the injection mold and the matching spraying machine is possible.

Preferably, at least in the transverse to the longitudinal extent the parting area between the turning part and the corresponding to the formation of half-forms rear mold plate, conical partitions provided. When retracting the turning part into the recess of the ejector-side mold plate is with this training receiving recess conically widening towards the receiving opening tion of the ejector-side mold plate and accordingly fit partitions of the turning part, the risk of damage The edges of the mold are practically excluded.

Additional embodiments of the invention are in the others Subclaims listed. Below is the invention with  their essential details with reference to the drawings explained in more detail.

It shows:

Fig. 1 is a side view of an injection molding machine with the open injection mold,

Fig. 2 is a side view of a closed injection mold,

Fig. 3 is a side view of a partially open injection mold and

Fig. 4 is a side view of an injection mold fully open for turning.

An injection molding machine shown in FIG. 1 is used to manufacture toothbrush bodies 2 . It has in the usual way on the left side a clamping unit 3 and on the right and above each an injection unit 4 and 5 .

The injection mold 6 is located between the clamping unit 3 and the injection units 4 and 5 . From this injection mold 6 , which is shown here in the open state, the closing unit 3 is facing a movable, ejector-side mold plate 7 and opposite a fixed, nozzle-side mold plate 8 and between these mold plates 7 and 8 be sensitive turning part 9 recognizable.

The injection molding machine shown is designed to produce brush bodies 2 from two components that are injection molded one after the other. Accordingly, it also has the two injection units 4 and 5 , in each of which a Spritzzy cylinder 10 , 10 a, a drive 11 , 11 a therefor and a filling funnel 12 , 12 a for supplying the molding compound, which is usually in the form of granules.

In the clamping unit there is a drive for the movable mold plate 7 , the drive being shown in dashed lines in the exemplary embodiment as a toggle lever drive. The turning part 9 is attached to the end of a sliding shaft 13 which is slidably mounted within the movable mold plate 7 . Guide bars 14 are provided for guiding and holding the mold plates.

The structure of the injection mold 6 can be seen in FIGS. 2 to 4. Particularly in Fig. 4, the essential parts of the injection mold 6, namely the fixed nozzle-side mold plate 8, the movable ejector-shape plate 7, which is displaceably mounted in the sliding shaft 13 and the inner mold at the end of the sliding shaft 13 mounted turning part 9 can be seen.

The movable mold plate 7 has a central recess 15 in which the turning part 9 fits, as can be seen clearly in FIGS. 2 and 3.

In the movable mold plate 7 and the turning part 9 therein and also in the fixed mold plate 8 , oppositely arranged mold cavities 16 (cavities) are provided, which form or limit the mold cavities when the injection mold is closed. The mold nests in the movable mold plate 7 and the turning part 9 each consist of two sections 16 a and 16 b, of which each one in the mold plate 7 ( 16 b) and the continuation of the second section ( 16 a ) is in the turning part.

The injection mold 6 shown in the exemplary embodiment is used to produce toothbrush bodies 2 consisting of two injection components.

At this point it should be mentioned that in principle more than two spray components can be processed in succession in a corresponding number of spraying processes. For example, with a four component, for. B. four color brush body corresponding to a processing in four spray positions. In this case, the injection mold would expediently make a quarter turn with its turning part 9 from one injection position to the next.

In the two-component injection mold shown in the exemplary embodiment, base bodies 2 a are produced in a first injection process and then in a second injection process these base bodies are overmolded in regions and then form the finished toothbrush body 2 .

According to the invention, the injection mold 6 is designed in such a way that the mold cavities 16 face each other with the area which, at least on one side, forms the holding area when the turning part 9 is rotated. In the present case, the mold cavities are arranged with the head ends 17 facing each other, as can be clearly seen in FIG. 3. It is here that the head end and in particular also the later bristle hole field of the toothbrush body 2 or of the base body 2 a is provided as the holding area. To form the holes in the punch field, punch punches engage there, which are connected to a punch punch holding device 18 . These punches form during the turning process a sufficient hold for the base body 2 a when the shape is open for the Wen devorgang. Due to the arrangement of the Hal tebereiche 19 near the axis, the turning part 9 can be made small and with a small rotational mass.

The turning part 9 is dimensioned so that the area 16 a of the mold cavity 16 , which also forms the holding area 19 , can be brought under.

In the mold cavity area 16 b and 16 b 'located outside of the holding area, which are in the movable mold plate 7 , it is taken into account that here in the two spray processes the base body 2 a and in the second spraying process the overmolding and formation of the finished toothbrush body 2 he follows.

The base body 2 a are in the lower mold area 16 b 'Herge provides and the extrusion coating to the finished toothbrush body take place in the upper mold area 16 b. The turning part 9 is in FIG. 4 just in a position where the base body sprayed in the lower area was turned upwards for the second spraying process. After this turning process, the finished toothbrush bodies 2 are ejected at the bottom of the turning part 9 , as is indicated by the arrow Pf 1 .

With its outer boundary facing away from the longitudinal center plane L, the turning part 9 forms the separating region from the part on the griffseiti of the mold nests 16 . In this transverse to the longitudinal extension of the mold cavity separating area between turning part 9 and the associated to form mold halves, ejector-side mold plate 7 has conical partitions 20 , 21 . As a result, after the turning process, a good centering of the insertion of the turning part 9 into the receiving recess 15 is possible, with the conical design of the partition walls avoiding edges, in particular in the mold cavity area.

The turning part 9 is Stigt 13 BEFE at the inner end of the sliding shaft and can be by means of the rotatably guided in the auswerferseiti gen mold plate 7 sliding shaft 13 from the central receiving recess 15 at the open injection mold to the position shown in Fig. 7 position eject. The sliding shaft 13 is also connected to a rotary drive in order to be able to turn the turning part 9 into its two different working positions. To the rotary drive includes a longitudinally displaceable and non-rotatably mounted on the sliding shaft and cooperating with a gear rack drive gear. For the rotationally fixed, but longitudinally displaceable mounting of the drive gear, the sliding shaft 13 is provided with a keyway into which a key of the drive gear engages. Because of the low mass of the turning part 9 you can get by with a single wedge-wedge groove connection and the use of an expensive multi-shaft is avoided.

Fig. 2 shows the injection mold in the closed position. Since at the same time body 2 a and finished toothbrush body 2 are injected. The mold is then opened by pulling back the movable mold plate 7 together with the reversible part 9 therein ( FIG. 3 partially opened). From stood between the two mold plates 7 and 8 is in the fully open position then so large that the turning part 9 can be brought from the movable mold plate 7 into the space between the mold plates by moving the sliding shaft 13 . The turning part 9 is then rotated by 180 degrees, the base body 2 a produced in the lower region being held on the turning part 9 . The toothbrush body 2 finished in the upper region is ejected downwards after this half turn. Thereafter, the turning part 9 is brought back into the receiving recess 15 of the mold plate 7 , the base body 2 a coming to rest with its handle-side ends in the mold cavity area 16 b.

The mold is then closed, rich base body 2 to be injected again at the bottom Be a, while at the same time made in the previous operation, the base body are injection-molded to finished toothbrush bodies 2 in the upper region.

By designing the turning part 9 , its mass could be reduced to a third of the original mass. Since the radius of the rotational inertia mass is quadratic, this results in a very considerable reduction in the effective rotational mass.

In the injection mold 6 according to the invention there is also a substantially more compact structure, by which a larger number of mold nests can be accommodated under given space conditions. In the present embodiment, it is a so-called "10 + 10 machine" in which gleichzei tig ten basic body 2 a and ten finished toothbrush body 2 can be injected. In spite of the high number of molds, the injection mold 6 can be designed so compactly by the design according to the invention that it can work in conjunction with a clamping unit 3 , the clear spar spacing of which is 420 mm. The frame size and the closing pressure of the machine are determined by the distance between the bars.

If, for example, the clear spar spacing were 620 mm as before, the use of a clamping unit with approximately twice the clamping force would be required, which would be almost 100% oversized with the proposed injection mold. There is therefore also a very considerable economic advantage with regard to the clamping unit when purchasing and also later during operation, since the energy requirement for a clamping unit 3 with a lower closing pressure is correspondingly lower.

In the practical example, instead of a 250 Ton machine a sufficient 130 for this injection mold Ton machine can be used.

As already mentioned, the holding of the base body 2 a during the turning process takes place in principle in the area where no changes are made during the second spraying process. In the exemplary embodiment shown, this is the end region of the toothbrush on the head side and here the bristles on the field side. If necessary, overmouldings on the back of the brush body could take place over the entire length.

Is the intended holding area for the basic body is only very small, so that correspondingly low retention forces are present, there is the possibility that, outside the holding area at the turning part 9 an effective during the turning process, and is preferably provided outside of the turning part 9 on the base body engaging auxiliary support. Such an additional bracket can also prevent deformation of the not yet fully hardened brush body during the turning process.

All in the description, the claims and the drawing features shown can be both individually and in be any combination with each other be essential to the invention.

Claims (8)

1. Brush production machine with an injection mold for the production of plastic brush bodies for toothbrushes or the like, the brush bodies in some areas, in particular outside their head area, consisting of several components which have been sprayed in succession and the injection mold as a turning tool with respect to a longitudinal center plane running through the turning axis Opposite mold nests is formed, which ches a nozzle-side, fixed mold plate, a die plate on the launcher side and a reversible part which is assigned to the ejector-side mold plate, is mounted on a central shaft which penetrates this central shaft, on which a punch holder device is provided for the later head-side bristle perforated field is, wherein the punches engaging in the perforated field form a head-side holder for the brush body during the turning process, characterized in that the mold cavities ( 16 ) m it their at least the brush head or the like holding area forming ends pointing towards each other and towards the longitudinal center plane (L) and with these ends on the turning part and that the part of the mold nests for the area of the brush body, in which another process in the next step Spray material component is sprayed from the longitudinal center plane to the outside and then located in the ejector-side mold plate ( 7 ). 2. Brush manufacturing machine according to claim 1, characterized in that the at least the area provided for the brush head or the like holding part of the mold cavity or turning part ( 9 ) is connected to the inner end of the rotatable sliding shaft ( 13 ) and that the turning part with it outer boundary facing away from the longitudinal center plane (L) forms the separating area from the handle-side part of the mold cavities. 3. Brush manufacturing machine according to claim 1 or 2, characterized in that the turning part ( 9 ) by means of the rotatable in the ejector-side mold plate ( 7 ) guided sliding shaft ( 13 ) from a central receiving recess ( 15 ) of the ejector-side mold plate ( 7 ) when the injection mold is open can be disengaged and rotated into the other turning position by means of a rotary drive. 4. Brush manufacturing machine according to one of claims 1 to 3, characterized in that at least in the transverse to the longitudinal extension of the mold cavity separating area between the turning part ( 9 ) and the associated to form mold halves, ejector-side mold plate ( 7 ) conical partitions ( 20 , 21 ) are provided. 5. Brush manufacturing machine according to one of claims 1 to 4, characterized in that on both sides of the longitudinal center (L) of the injection mold are preferably provided parallel to each other mold cavities ( 16 ), preferably before 10 mold cavities. 6. Brush manufacturing machine according to one of claims 1 to 5, characterized in that outside of the preferably head-side holding area ( 19 ) of the mold cavities ( 16 ) for the brushes an effective at least during the turning process, in particular on the free brush handle or the same attacking additional holder is provided. 7. Brush manufacturing machine according to one of claims 1 to 6, characterized in that the sliding shaft ( 13 ) a longitudinally displaceable and non-rotatably mounted thereon, preferably with a rack as a drive cooperating drive gear which preferably carries the rotary connection by a single key-spline connection is formed and that, if necessary, the sliding shaft ( 13 ) is designed as a multi-tooth shaft. 8. Brush manufacturing machine according to one of claims 1 to 7, characterized in that the injection mold ( 6 ) is dimensioned with a total of 20 mold nests ( 16 ) in their outer dimensions suitable for clear spacing of the mold guide rails ( 14 ) of about 420 mm.