EP0347544A2 - Device for applying powdery or flocculent material to a substrate - Google Patents

Abstract

A device for applying a powdery or flocculent material to a substrate has a conveying device which conveys the powdery or flocculent material from a reservoir to an applicator, and supplies the applicator with a moveable sequence of receptacles for receiving the powdery or flocculent material; the powdery or flocculent material coming from the reservoir is sucked at one point of its movement into a receptacle and at another point of its movement is blown out of the receptacle and fed to a discharge orifice. <IMAGE>

Description

The invention relates to a device for applying a powder or flake material to a substrate.

Although similar problems also occur in other technical fields, for example in the powder coating or flocking of high-polymer materials, only the application of the powdery or flaky material known under the name "superabsorbent" will be dealt with below.

In order to achieve the best possible absorbency or moisture absorption in hygienic articles, for example baby diapers, sanitary napkins and the like, a moisture-absorbing material in the form of fibers or flakes is added to the flakes made of cellulose or synthetic materials usually used in the production of these articles.

In recent years, a new absorbent has been developed, which is referred to as "superabsorbent" and has a significantly higher moisture absorption and absorption rate with a smaller volume compared to conventional materials. This material is made in powder or flake form and must be processed accordingly.

Superabsorbent is used in various manufacturing processes, for example for the manufacture of baby diapers or sanitary napkins, so that versatile application devices are required. The required, relatively low application weights of about 1 g to 25 g per product represent a problem, in particular in connection with the high production speeds of 50 to 100 products per minute required.

A universal system is therefore required for the supply, metering and application of superabsorbent, which can also work both in cycles and continuously.

A particular difficulty is the exact, volumetric dosage of superabsorbent, regardless of the production speed; For superabsorbent in powder form, this problem has so far only been solved at extremely high cost. Dosing systems for the exact, volumetric dosing of superabsorbent in flake form, which meet these requirements, have so far not become known on the market.

The invention is therefore based on the object of providing a device for applying a powdery or flaky material, in particular the material known under the name "superabsorbent", to a substrate in which the disadvantages mentioned above do not occur. In particular, a device is to be proposed which enables the exact, volumetric metering of this material in powder or flake form, regardless of the production speed.

This is achieved according to the invention by the features specified in the characterizing part of claim 1.

Appropriate embodiments are defined by the subclaims.

The advantages achieved by the invention are based on the use of a module system consisting of an applicator which can apply the material in powder and flake form, and a transport device which is based on the powder or flake form of the material and the material from one Feed reservoir to the applicator.

In particular, there is also the possibility of removing the material directly from its transport container, for example a sack, and feeding it to the applicator.

In order that there is always a sufficient amount of material available in the feed or transport container, a corresponding material sensor, which works for example capacitively, can be provided. In this case, it is advisable to physically separate the transport container and the storage container, i.e. not to feed the material directly from its transport container to the applicator, but rather to transfer the material from its transport container to the storage container so that enough material is in the container when the transport container is changed Storage container remains in order to be able to bridge the changeover time without stopping the machine.

As an alternative to this, it is of course also possible to use the transport container directly as a storage container, that is to say to load the applicator directly from the transport container.

While this embodiment is particularly suitable for the powdery material, a special flake storage container with driven "comb shafts" must be provided for the flaky material, which prevents the material from clumping or bridging over the transport device and at the same time for evenly loosened material in the area of the transport device must worry.

The storage container for the flake-shaped material can, for example, have a conical shape, that is to say taper from top to bottom, so that the material is removed from the deepest and narrowest point of the storage container can be pulled. This ensures that the remaining material collects on the floor in the area of the transport device and is thus conveyed safely and reliably.

As an alternative to this, however, the storage container for the flake-like material can also have parallel side walls, kettles, pyramids or another shape.

In a preferred embodiment, at least one comb shaft with at least one two-bladed rotor is arranged in the storage container for the flaky material; the two blades of the rotor can either run in a straight line or at an angle to one another.

A hose spiral, a screw, suction by negative pressure, a pneumatic pump or a similar conveying device can be provided as the transport device for the transfer of the powdery or flaky material from the storage or transport container to the applicator.

A hose spiral is particularly suitable because of its small volume, which is inserted directly into the transport container for the powdery material, for example, and gradually empties it. When using a storage container with a conical cross section, the hose spiral can be arranged at the lowest point of the cone, so that this storage container can be completely emptied.

The applicator, which serves as a discharge and metering device, can process both pulverulent material and flake material and consists of a fixed, central bearing core which has a cylindrical shape and is provided on one side with an air intake line and on the opposite side with an outlet line . According to a preferred embodiment, the air suction line and the outlet line, which are acted upon by negative pressure, are at a distance from one another, but are symmetrical to one another in the two halves of the cylindrical bearing core.

The outer wall of the bearing core has, at least in the area of the intake line and the blow-out line, a multiplicity of openings which are formed by bores, slots, perforations or the like. In principle, such breakthroughs can also be provided in the other areas; however, this could impair the required vacuum in the bearing core.

There is no connection whatsoever between the suction or exhaust line on the one hand and the associated openings on the other.

A driven, approximately ring-shaped jacket rotates around the stationary bearing core and is provided with at least one recess perforated in the bottom, which serves to hold the powdered or flake material. The dimensions, in particular the length and width of the depressions, are adapted to the amount of powdered or flake material to be metered.

The rotating jacket can be completely replaced to adapt to different product sizes or product numbers per jacket revolution.

In order to obtain additional variation options, different pockets can be inserted into the recesses of the rotating jacket, which are also perforated in the bottom; this also enables different application weights to be achieved, with only the individual pockets having to be replaced when the specified application weight changes.

These pockets can be provided with so-called “dosing pins” which protrude into the pockets and reduce the volume of the interior of the pocket; In this way it is possible, for example, to balance small differences in volume in the case of different powdery or flaky materials.

These dosing pins can, for example, be combined with the fastening screws for the pockets and protrude into the pocket as an extension of the fastening screws in order to reduce the volume of their interior.

The rotating jacket can be driven directly via the drive shaft of the associated production machine and thus run at a speed that is directly, for example linearly dependent on the machine speed. Of course, as an alternative to this, a continuous drive via independent or DC-voltage-driven motors or an intermittent drive via stepper motors or similar drive devices is also possible.

While the air is usually sucked in continuously, the blow-out line can be operated both continuously and intermittently. In the case of intermittent operation, a corresponding control valve is provided in the blow-out line.

The rotating jacket of the applicator is expediently surrounded by a cover which is broken only in the area of the material feed and the material discharge. The size of the feed or discharge opening formed in this way, seen in the longitudinal direction of the applicator and perpendicularly here, depends on the nature of the product to be manufactured and on the production speed.

The pulverulent or flaky material conveyed by the transport or feed container via the transport device is sucked through the feed opening in the cover of the applicator into a recess in the rotating core, specifically by means of the suction line of the bearing core, which is acted upon by negative pressure and which has a precisely defined pressure difference between the supply opening of the cover on the one hand and the suction line on the other. This pressure difference leads to an air flow from the supply opening of the cover over the depressions or pockets in the rotating jacket, the perforations in the depressions or pockets and the stationary bearing core to the suction line.

As a result, a quantity of material collects in each pocket or recess of the rotating bearing core, which depends on the nature of the material, the internal volume of the recess or pocket and the flow rate. Excess material is wiped off by the rotation of the jacket on the edge between the pocket or recess and the feed opening in the cover of the applicator.

This amount of material, the volume of which can be precisely determined, is taken along with the rotation of the rotating jacket and now reaches the opposite side of the bearing core, where the exhaust air from the blow-out line through the bearing core, the openings in the jacket of the bearing core and the perforations in the depressions or pockets of the jacket get into the recesses or pockets and take the material located there to the discharge opening. Since the entire amount of material in the pockets or recesses is expelled, an exact dosage can be made.

By regulating the transport device, but also the applicator, for example a level or pressure control on the applicator, it is ensured that a sufficient amount of material is constantly present at the feed opening in the cover of the applicator, that is to say in the suction area.

At the discharge opening in the cover of the applicator, for example, a nozzle-shaped extension, if necessary with an additional elbow, can be provided in order to bring the amount of material blown out to the actual processing point, for example a coating device for diapers.

By regulating the amount of air or the air pressure in the discharge area, the powdery or flaky material can be accelerated as desired or can be spread without pressure if necessary without compressed air.

In particular with continuous application of flake-like material, the exact separation of the individual dosing quantities is not too important, so that in this case a single, "endless" depression can be provided in the rotating jacket, that is to say a single, circumferential channel. The metering then takes place essentially via the control of the suction or. Exhaust air.

Although it is also possible to work with such an endless depression in the continuous application of a powdery material, it is advisable here to form narrow transverse webs on the jacket in order to ensure a better hold for the powdery material.

In the case of discontinuous, intermittent operation, it is of course necessary either to provide a plurality of separate depressions or to insert the pockets mentioned into the “endless” depression.

It is even possible to work alternately with different dosing quantities, for example by attaching two different types of bags with different volumes to the jacket.

• Fig. 1 eine Darstellung einer Vorrichtung zum Auftragen eines pulver- oder flockenförmigen Superabsorbents auf eine Windel,
• Fig. 2 eine Darstellung eines Vorratsbehälters für flockenförmiges Super­absorbent mit Transportvorrichtung,
• Fig. 3 eine Seitenansicht des Vorratsbehälters nach Fig. 2,
• Fig. 4 eine Darstellung eines Vorratsbehälters für flockenförmiges Su­perabsorbent und seiner Transportvorrichtung,
• Fig. 5 eine Seitenansicht des Vorratsbehälters nach Fig. 4,
• Fig. 6 einen senkrechten Schnitt durch den Applikator, und
• Fig. 7 eine Seitenansicht von außen auf den Applikator.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the accompanying schematic drawings. Show it:

• 1 is an illustration of a device for applying a powder or flake superabsorbent to a diaper,
• 2 shows a storage container for flake-shaped superabsorbent with a transport device,
• 3 shows a side view of the storage container according to FIG. 2,
• 4 shows a storage container for flake-shaped superabsorbent and its transport device,
• 5 shows a side view of the storage container according to FIG. 4,
• Fig. 6 is a vertical section through the applicator, and
• Fig. 7 is a side view from the outside of the applicator.

Although similar problems also occur in other applications of powder or flake materials, only one device for applying powder or flake superabsorbent in the manufacture of a diaper will be described below.

The device for applying superabsorbent to a diaper, which is shown in FIG. 1 and is generally indicated by reference number 10, has a reservoir 12, which is connected to the "diaper machine" 16 via a hose spiral 14. An applicator 18, which is only schematically indicated in FIG. 1, is located on the diaper machine 16.

In Fig. 1, the structure of the diaper machine 16 is only indicated schematically, namely by a winding spool 20 and an unwinding spool 22 for the diaper material. These two coils are arranged so that the diaper material 24 is transported between them on a horizontal path and is coated from above with the superabsorbent 26, which emerges from an elongated nozzle 28 of the applicator 18.

A further variant is indicated in FIG. 1, namely two coils 20, 22 arranged vertically one above the other, between which the diaper material 24 runs in the vertical direction. Now the superabsorbent 26 is applied from the nozzle 28 from the side, as can be seen in FIG. 1.

2 and 3 show an embodiment of a storage container 12 for powdery superabsorbent; this storage container 12 has a funnel-shaped filling opening 30, which is followed by conical walls 32 which converge at the bottom of the storage container 12.

At this lowest, narrowest point of the storage container 12, a transport spiral 33 serving as a transport device is arranged, which is rotated by an electric motor 34 and thereby conveys the powdery superabsorbent from the bottom of the storage container 12 via the hose spiral 14 to the applicator 18.

On a side wall of the reservoir 12 there is a capacitive material sensor 36, which monitors the fill level in the reservoir 12 and, for example, generates an alarm signal when the fill level falls below a predetermined value and thus alerts the operator that the reservoir 12 must be refilled.

Such a transport spiral 14, 33 can also convey the powdery material directly from the transport container, for example a barrel, a sack, a container or the like, so that the transport container also serves as a storage container.

4 and 5 show an embodiment of a storage container 12 for flake-shaped superabsorbent. This storage container 12 also has a funnel-shaped filling opening 30 and conical side walls 32, a capacitive material sensor 36 and the transport spiral 33 on the bottom of the storage container 12.

As can be seen in FIG. 5, a total of five comb shafts 38 are mounted in the two opposite, parallel side walls of the storage container 12, which (see FIG. 4) protrude somewhat beyond the side wall and are rotated by a common drive, namely a belt drive 40 be connected to the electric motor 34 for the transport spiral 33.

A plurality of four-bladed rotors 42 sit on each comb shaft 38, the blades of which are arranged at a right angle to one another. As an alternative, the four wings can also run at an angle to one another. After all, a single blade per rotor is sufficient for many cases.

These comb shafts 38 with the rotating rotors 42 prevent the flake-shaped superabsorbent from clumping or bridging over the transport spiral 33 and at the same time ensure that superabsorbent is always loosened uniformly in the region of the transport spiral 33.

In the same way as for the powder supply from the storage container 12 according to FIG. 2, the flake-shaped superabsorbent is fed to the applicator 18 by means of the transport spiral 33 and the hose spiral 14.

FIGS. 6 and 7 show details of the applicator 18, which has a closed, housing-like cover 45, which on one side, as shown in FIG. 6 the top, with a feed opening 44 connected to the hose spiral 14 for the flake or powder form Superabsorbent and on the opposite side, ie according to the illustration in FIG. 6 of the lower side, is provided with a discharge opening 46. The direction of transport for the superabsorbent is indicated by the two arrows.

In the center of the applicator 18 there is a hollow cylindrical, stationary bearing core, which is closed on one end face, as shown in FIG. 7 the left end face, and on the opposite end face, that is, as shown in FIG. 7, with an intake line 50 and a blow-out line 52 is provided. A negative pressure is applied to the suction line 50, so that the air is sucked out of the stationary bearing core 48 in the direction of the double arrows, while the blow-out line 52 is pressurized with compressed air, as indicated by the double arrows.

As can be seen in FIG. 6, the feed opening 44, the suction line 50, the blow-out line 52 and the discharge opening 46 are in a straight line, but are not directly connected to one another. The suction line and the blow-out line 52 are arranged symmetrically to one another and vertically one above the other in the two halves of the cylindrical bearing core 48.

The stationary bearing core 48 has a series of openings in its outer wall, specifically on its side facing the feed opening 44 and on the other hand on its side facing the discharge opening 46. These breakthroughs can be formed by bores, slots, perforations or the like. If necessary, the entire wall can be provided with such openings.

The stationary bearing core 48 is surrounded by a rotating jacket 54, the inner surface of which rests on the outer wall of the stationary bearing core 48 and which has the shape of a hollow cylinder.

The two end faces of the jacket 54 are closed; on an end face there is a shaft 56 which is coupled via a drive belt 58 to the electric motor 60 of the diaper machine 16 (see FIG. 1) and is thereby driven directly by the diaper machine, so that the rotational speed of the jacket 54 is directly dependent on the machine speed.

The jacket 54 thus rotates coaxially to the stationary bearing core 48 in the direction of the arrows around it and has three schematically indicated depressions 58 in its outer surface, which have openings at their bottom Chen, so holes, slots, perforations or the like are provided.

Perforated pockets 60 are also inserted into these three depressions 58 and fastened by screws; the pockets, like the entire jacket 54, can be replaced and thus adapted to different operating conditions.

The powdered or flake-shaped superabsorbent conveyed by the hose spiral reaches the supply opening 44 in the cover 45 of the applicator 18 and thus in the area of the suction line 50, and the air from the supply opening 44 into the pocket 60 in the upper one, as shown in FIG. 6 Indentation 58 and from there through the perforations in pocket 60 and indentation 58 sucks into the interior of the stationary bearing core 48. The powdered or flaky superabsorbent is transported into the pocket 60 by the sucked-in air in an amount that depends on the flow rate of the suction air, the rotational speed of the jacket 54 and the inner volume of the pocket 60.

Upon further rotation of the casing 54 in the direction of the arrows, the excess superabsorbent is stripped off at the edge between the pocket 60 and the feed opening 44 and the pocket 60 is transported further in the direction of the arrows until it reaches the lower position as shown in FIG. 6 reached and thus in the effective range of the blow-out line 52, the compressed air through the openings in the stationary bearing core 48 and the openings in the pocket 60 or the recess 58 of the rotating jacket 54 blows into the interior of the pocket 60, so that the located there Material is discharged through the discharge opening 46 in the direction of the double arrows.

The transport routes of the powder or flake superabsorbent are indicated in Fig. 6 by the arrows.

In particular during continuous application of the flake-shaped superabsorbent, an “endless” depression 58 can be provided in the rotating jacket 54, that is to say a circumferential channel which is provided with perforations on its base.

When continuously applying a powdery superabsorbent, it is advisable to provide narrow crossbars to ensure a better hold for the material.

In the case of the intermittent order, either separate depressions 58 or the pockets 60 already explained are provided, which enable the discrete order.

While the intake air usually works continuously, the blown air can be operated both continuously and intermittently via a corresponding control valve, in particular a solenoid valve, which is indicated in FIG. 1 by reference number 19.

The size of the feed opening 44 or the discharge opening 46 in the longitudinal direction of the applicator 18 depends on the nature of the product to be manufactured, for example a diaper, and the production speed.

As can be seen in Fig. 1, a nozzle-like extension 28 is connected to the discharge opening 46, which brings a precisely metered amount of material to the actual processing point.

Deflections in the conveying direction are also possible by using a suitable bend.

By regulating the amount of air or the air pressure in the application area, the superabsorbent material can be accelerated as desired or spread without pressure, as is possible, for example, when applying the product vertically down onto a horizontal substrate.

Claims (18)

1. Device for applying a powder or flake material to a substrate, characterized by the following features: a) a transport device (14, 33) conveys the powder or flake material from a storage container (12) to an applicator (18); b) the applicator (18) has a movable sequence of receiving containers (58, 60) for receiving the powdery or flaky material; and c) the powder or flake material coming from the storage container (12) is received at a first point in a movable receiving container (58, 60) and discharged at a second point from this receiving container (58, 60) and a discharge opening (46 ) fed. 2. Device according to claim 1, characterized in that the transport container for the material, in particular for the powdery material, serves as a storage container. 3. Apparatus according to claim 1, characterized in that in the storage container (12) at least one driven shaft (38) with rotors (42) are arranged. 4. The device according to claim 3, characterized in that each rotor (42) has at least one wing projecting from its shaft (38). 5. Device according to one of claims 1 to 4, characterized in that the transport device (14) extends into the storage or transport container (12). 6. Device according to one of claims 1 to 5, characterized in that the transport device (14) is formed by a hose spiral, a screw, a vacuum system or a pneumatic pump. 7. Device according to one of claims 1 to 6, characterized by a material sensor (36) for the fill level of the storage or transport container (12). 8. Device according to one of claims 1 to 7, characterized in that the material is sucked into the receptacle (58, 60) at the first point and is blown out of the receptacle (58, 60) at the second point. 9. Device according to one of claims 1 to 8, characterized in that the applicator (18) has a stationary bearing core (48) with at least one suction line (50) and at least one blow-out line (52). 10. The device according to claim 9, characterized in that the bearing core (48) is provided with openings at least in the region of a feed opening (44) for the powder or flake material coming from the storage container (12) and the discharge opening (46). 11. Device according to one of claims 9 or 10, characterized in that the stationary bearing core (48) is surrounded by a rotating jacket (54) with depressions (58) or pockets (60) with openings. 12. The apparatus according to claim 7, characterized in that the rotating jacket (54) and / or the pockets (60) are interchangeable. 13. Device according to one of claims 11 or 12, characterized in that the rotating jacket (54) rotates depending on the machine speed. 14. Device according to one of claims 11 to 13, characterized in that the rotating jacket (54) is provided with a continuous, circumferential groove (58). 15. The apparatus according to claim 14, characterized in that the channel (58) has transverse webs. 16. The device according to one of claims 1 to 15, characterized in that the applicator (18) has a cover (45) with the feed opening (44) and the discharge opening (46). 17. The apparatus according to claim 16, characterized in that the feed opening (44), the suction line (50), the blow-out line (52) and the discharge opening (46) are arranged on a line. 18. Device according to one of claims 9 to 17, characterized in that the suction line (50) and blow-out line (52) open into an end face of the stationary bearing core.

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