Dosing device for infusion products

Abstract

Described is a dosing device for depositing doses of product on a continuous strip (S) of filter paper at predetermined distances from each other; the device (100) comprising a dosing chamber (1) configured to receive a product from a feeding hopper (2); a rotary drum (3) configured for rotating about an axis (X) of rotation along a direction (V) of rotation and comprising a plurality of dosing drawers (4); the dosing drawers (4) are positioned along a circular surface of the rotary drum (3) at predetermined distances from each other and configured for receiving the product along an angular loading path (P1) corresponding to a transit zone of the rotary drum (3) facing and in communication with the dosing chamber (1); a first screw feeder (5) housed inside the dosing chamber (1) and having an axis of rotation (X1) positioned tangentially to the rotary drum (3); the first screw feeder (3) is configured for moving the product inside the dosing chamber (1) in a tangential direction (V1), a second screw feeder (7) housed inside the dosing chamber (5) and having an axis (X2) of rotation positioned radially relative to the rotary drum (3); the second screw feeder (7) is configured for moving the product along a radial direction (V2) towards one of the dosing drawers (4) of the rotary drum (3).

Description

[0001] DESCRIPTION

[0002] DOSING DEVICE FOR INFUSION PRODUCTS

[0003] Technical field

[0004] This invention relates to a dosing device for infusion products, in particular products in powder form.

[0005] More specifically, this dosing device is applied on machines for packaging filter bags with infusion products.

[0006] Background art

[0007] These packaging machines comprise a series of operating stations for forming filter bags along a direction of extension of the machine.

[0008] More specifically, the packaging machine on which the dosing device is applied comprises:

[0009] - a station for feeding a web of filter paper along a feed surface;

[0010] - a station for feeding doses of product on the web of filter paper at predetermined distances;

[0011] - a station designed to close the web on itself, wrap the doses of product and, subsequently, longitudinally join the web;

[0012] - a station for cutting pieces of filter paper with a dose of product inside;

[0013] - a carousel equipped with radially protruding grippers, positioned beneath the closing and cutting station and configured to receive individual pieces of filter paper; the carousel, moved stepwise about a horizontal axis, moves each piece of filter paper in the proximity of stations arranged one after another to associate to the piece of filter paper a thread, suitably wrapped around the piece of filter paper, and a tag in turn associated with the thread. The station for feeding the doses, which is of particular relevance to this invention, therefore comprises a dosing device which is able to form doses of product to be placed at predetermined distances on the filters in transit. A prior art dosing device is described in document US 4 628 973.

[0014] This document illustrates a dosing device of the dosing chamber type inside of which a dosing drum rotates in a discontinuous fashion. The apparatus comprises a first fixed hollow body facing towards the body of the dosing device and provided with a vertical feed duct for the product to be dosed.

[0015] A second hollow funnel-shaped body which rotates in an inclined fashion in the fixed hollow body, with the upper opening larger below the feed duct and a lower opening communicating with the dosing chamber close to the dosing drum; a shutter for adjusting the flow of the product along the lower inner surface of the rotary funnel-shaped body at least close to the lower opening and a reduction gear unit with a variable speed controlled by the actuating means of the packaging machine in such a way as to rotate the funnel- shaped body about its inclined axis. A screw feeder is located vertically on the drum and is used to lift and discharge excess product from the drum.

[0016] Another prior art solution of an improved dosing device basically comprises:

[0017] - a hopper for feeding, by gravity, the product to be dosed;

[0018] - a product dosing chamber positioned below the hopper;

[0019] - a drum rotating about an axis of rotation with a direction of rotation (usually anti-clockwise) and comprising a series of dosing drawers; the dosing drawers are positioned along the circumference of the drum at predetermined distances and configured for receiving the product present in the dosing chamber, by gravity, during their passage along a predetermined first angular loading path at the dosing chamber;

[0020] - a contact wall facing the drum and positioned downstream of the dosing chamber, with reference to the direction of rotation of the drum; the contact wall, with an arc-shaped extension, is configured to eliminate the excess product from the drawers filled and in transit (by smoothing the product at the mouth of each drawer) along a second angular path opposite the first angular path; the contact wall is interrupted at the zone for depositing the dose of product on the strip of filter paper in transit.

[0021] The dosing chamber is also provided with a motor-driven screw feeder at a constant speed positioned tangential to the surface of the rotary drum.

[0022] The screw feeder is used to move the product in a direction opposite to the direction of rotation of the drum in such a way as to prevent an accumulation of the product, due to contact with the rotary drum, at an end of the chamber. The screw feeder also has the purpose of pushing the product towards a side portion of the dosing chamber configured in the form of a well and wherein the product starts to be dosed inside each drawer in an initial stretch of the first angular path of transit of the drawers.

[0023] In short, the product fallen into the side chamber must immediately start entering, in a natural manner, the inside of the drawer of the drum and then complete the filling in the remaining path before the drawer intercepts the contact wall.

[0024] However, these types of dosing devices have shown some drawbacks.

[0025] A first drawback is due to the structure of this dosing device which may have problems if a high dosing speed is requested, since the loading of the drawers with the product, performed only by natural gravity falling into the drawers, may be not very precise.

[0026] Another drawback is due to the difficult feeding of products which are not very slidable, that is to say, with mixtures of creamy products such as herbs, cocoa and the like which have high adhesiveness characteristics on the surfaces present in the chamber. These products tend to layer, for example, in the zone of falling towards the side dosing chamber with a trap creating a bridge effect which, in effect, reduces the presence of product close to the base of the trap with the risk of incorrect feeding of the drawers in transit.

[0027] Disclosure of the Invention

[0028] The aim of the invention is to provide a dosing device for infusion products which overcomes the drawbacks of the prior art described above.

[0029] More specifically, the aim of this invention is to provide a dosing device for infusion products which is able to obtain a precise and fast feeding of the drawers irrespective of the type of product to be handled.

[0030] A further aim of this invention is to provide a dosing device for infusion products which is able to feed the product to the drawers with a high level of operating flexibility required by the speeds of the machine.

[0031] Said aims are fully achieved by a dosing device for infusion products according to the invention as characterised in the appended claims.

[0032] Brief description of the drawings

[0033] The main features of the invention will become more apparent from the following detailed description of a preferred, non-limiting embodiment, illustrated purely by way of example in the accompanying drawings, in which:

[0034] - Figure 1 illustrates a schematic front view, with some parts cut away to better illustrate others, of a machine for packaging filter bags with infusion products comprising the dosing device according to the invention;

[0035] - Figure 2 illustrates a perspective view from above with some parts cut away in order to better illustrate others of the dosing device according to the invention;

[0036] - Figure 3 illustrates a front perspective view of a drum and a pair of screw feeders forming part of the dosing device of the drawing;

[0037] - Figure 4 illustrates a perspective view from above of a part of the dosing device of Figures 2 and 3;

[0038] - Figure 5 illustrates an exploded perspective view of a dosing chamber of the dosing device of Figures 2 to 4;

[0039] - Figure 6 illustrates an exploded perspective view of the rotary drum and a relative contact wall.

[0040] Detailed description of preferred embodiments of the invention

[0041] With reference to the accompanying drawings, in particular Figures 1 and 2, the dosing device, labelled 100 in its entirety, is used for depositing doses of product on a continuous strip S of filter paper at predetermined distances from each other.

[0042] As illustrated in Figure 1 , the dosing device 100 may be applied on a machine for packaging filter bags with infusion products, in particular, but without limiting the scope of the invention, tea, coffee, camomile and the like.

[0043] As illustrated in Figure 1 , the packaging machine has a plurality of forming stations 20-27 configured for making filter bags, including:

[0044] - a station 21 for feeding the strip S of filter paper;

[0045] - a station 20 for feeding the product comprising a dosing device 100;

[0046] - a station 22 configured for closing the strip S wrapping the doses of products (with longitudinal joining of the strip).

[0047] - a cutting station 23 for separating the filter bags with the product inside them;

[0048] - a carousel 24 equipped with radially protruding grippers positioned downstream of the cutting station 23.

[0049] - a station 25 for feeding string,

[0050] - a station 26 for feeding labels and

[0051] - a station 27 for feeding a piece of paper for the over-wrapping.

[0052] All the stations just mentioned are illustrated schematically only to illustrate one of the possible fields of application of the dosing device 100 according to this invention.

[0053] As also illustrated in Figures 2 to 6, the device 100 comprises a dosing chamber 1 configured for receiving a product from a feeding hopper 2. The chamber 1 is positioned below the feeding hopper 2, and receives the product by gravity,

[0054] The device 100 also comprises a rotary drum 3 configured to rotate about an axis of rotation X along a direction of rotation V and comprising a plurality of dosing drawers 4.

[0055] The dosing drawers 4 are positioned along a circular surface of the rotary drum 3 at predetermined distances from each other and configured to receive the product along an angular loading path R1 corresponding to a transit zone of the rotary drum 3 facing and in communication with the dosing chamber 1 .

[0056] Moreover, the device 100 comprises a first screw feeder 5 (rotary) housed inside the dosing chamber 1 and having an axis of rotation X1 positioned tangentially to the rotary drum 3.

[0057] This first screw feeder 3 is configured for moving the product inside the dosing chamber 1 in a tangential direction V1 (opposite to the direction V of rotation of the rotary drum 3).

[0058] As illustrated, the dosing device 100 also comprises a second screw feeder 7 housed inside the dosing chamber 5 and having an axis of rotation X2 positioned radially relative to the rotary drum 3.

[0059] This second screw feeder 7 is configured for moving the product (present in the side chamber 6 with a trap) towards one of the dosing drawers 4 of the rotary drum 3.

[0060] In other words, the dosing device 100 is equipped with an additional screw feeder which is able to feed, as described below, the product into the drawers so as to accelerate the filling of the drawers.

[0061] Again as illustrated, the dosing chamber 1 comprises a main zone 5a and a side zone 6.

[0062] The main zone 5a houses the first screw feeder 5 and is positioned above the rotary drum 3.

[0063] The side zone 6 houses the second screw feeder 7 and is positioned laterally to the rotary drum 3 under the main zone 5a.

[0064] This side zone 6 (or side chamber with a trap) is positioned along the angular loading path P1 .

[0065] It should be noted that the first screw feeder 5 and the second screw feeder 7 lie in a shared plane perpendicular to the axis of rotation X of the rotary drum 3.

[0066] In light of this, the second screw feeder 7 is positioned along the first angular loading path P1 .

[0067] More specifically, the second screw feeder 7 is positioned in the side zone 6 and close to the bottom of the side zone 6 in such a way as to feed the product at the start of the loading path P1 (at 3 o'clock).

[0068] It should be noted that the second screw feeder 7 has a shaft 8 equipped with a spiral 9 having a cross section configured for pushing the product towards the rotary drum 3.

[0069] As illustrated, the first screw feeder 5 and the second screw feeder 7 are connected, respectively, to a first drive unit 10 and a second drive unit 11 which are independent of each other.

[0070] This structure makes it possible to modify the speeds of the two screw feeders independently and according to the operational dosing requirements.

[0071] In light of this, the second screw feeder 7 has a longitudinal extension less than the longitudinal extension of the first screw feeder 5.

[0072] The first screw feeder 5 has a first portion configured in the form of a spiral (for moving the product in the direction V1 ) and a second portion with radial arms protruding from its shaft positioned above the side zone 6 to allow a greater speed of falling of the product towards the bottom of the side zone 6 and towards the second screw feeder 7.

[0073] As illustrated, the dosing chamber 1 has a sloping rear wall 12.

[0074] This inclined extension defines a chute for the falling of the product towards the rotary drum 3.

[0075] This geometry allows a greater continuity and speed of falling of the product from the hopper towards the drum.

[0076] In light of this, the dosing chamber 1 has a front wall consisting of a closing cover 13.

[0077] The cover 13 has a sloping surface 14 facing the sloping rear wall 12. Moreover, the side zone 6 has a configuration tapered towards (a zone, that is, the bottom) the second screw feeder 7.

[0078] In light of this, the side zone 6 has a side wall 15 close to the rotary drum 3 with an arc-shaped extension and decreasing towards the bottom 16 of the side chamber 6 with a trap.

[0079] This geometry of the dosing chamber and of its side zone 6 is configured to create chutes for the guiding and falling of the product as quickly as possible and with reduced surfaces which are able to create deposits in zones not used for dosing the drawers.

[0080] In light of this, each dosing drawer 4 is formed by a respective radial negative pressure present on the circular surface of the rotary drum 3.

[0081] As illustrated, the dosing device 100 comprises a fixed containment wall 17 facing the rotary drum 3 along an angular path P2 for transit of product contiguous to / and downstream of the angular loading path P1 , with reference to the direction V)of rotation of the rotary drum 3.

[0082] In light of this, the containment wall 17 comprises a head 18 for smoothing the product positioned adjacent to the angular loading path P1 .

[0083] The smoothing head 18 has a central vertex and two sloping side surfaces in such a way as to allow a lateral evacuation of the excess product during the transit of the drawers 4.

[0084] It should be noted that the containment wall 17 forms a channel 19 facing the rotary drum 3 along the angular transit path P2.

[0085] In light of this, the channel 19 has a variable depth decreasing along the direction V of rotation of the rotary drum 3, so as to prevent the creation of excessive friction between the drum 3 and the side walls formed by the containment wall 17 and which could block the rotation of the drum 3 along the angular transit path P2 and up to a zone for discharging the doses of product on the strip S of filter paper.

[0086] This invention also relates to a machine for making filter bags with infusion products comprising a plurality of forming stations 20-27 configured for making filter bags, and a station 20 for feeding the product comprising a dosing device 100 as described above and the feeding hopper 2 configured for feeding the product to the dosing device 100.

[0087] A dosing device for depositing doses of product on a continuous strip S of filter paper at predetermined distances from each other, wherein the device 100 comprises:

[0088] - a dosing chamber 1 configured for receiving a product from a feeding hopper 2;

[0089] - a rotary drum 3 configured to rotate about an axis of rotation X along a direction of rotation V and comprising a plurality of dosing drawers 4;

[0090] - the dosing drawers 4 being positioned along a circular surface of the rotary drum 3 at predetermined distances from each other and configured for receiving the product along an angular loading path P1 corresponding to a zone of passage of the rotary drum 3 facing and in communication with the dosing chamber 1 ;

[0091] - a first screw feeder 5 housed inside the dosing chamber 1 and having an axis of rotation X1 positioned tangentially to the rotary drum 3.

[0092] The first screw 3 is configured for moving the product inside the dosing chamber 1 in a tangential direction V1 (opposite to the direction V of rotation of the rotary drum 3);

[0093] - a fixed containment wall 17 facing the rotary drum 3 along an angular path P2 for transit of product contiguous to and downstream of the angular loading path P1 , with reference to the direction V of rotation of the rotary drum 3 and where

[0094] - the containment wall 17 forms a channel 19 facing the rotary drum 3 along the angular transit path P2, and wherein the channel 19 has a variable depth decreasing along the direction V of rotation of the rotary drum 3, in such a way as to avoid the creation of excessive friction between the drum 3 and the side walls formed by the containment wall 17 and which could block the rotation of the drum 3 along the angular transit path P2 and up to a zone for discharging the doses of product on the strip S of filter paper.

[0095] Thanks to this dosing device, the preset aims are achieved thanks to the presence of a second screw feeder designed to feed the product into the drawers in a precise and fast manner.

[0096] The internal geometry of the dosing chamber allows a constant and continuous feeding of the product along the entire transit path to be maintained, avoiding accumulations which could limit the feeding to the drawers.

[0097] The presence of a contact wall with a channel with a variable geometry makes it possible to always obtain a correct and balanced dosing of product in the individual drawers.

Claims

CLAIMS1 . A dosing device for depositing doses of product on a continuous strip (S) of filter paper at predetermined distances from each other; said dosing device (100) comprising:- a dosing chamber (1 ) configured to receive a product from a hopper (2);- a rotary drum (3) configured to rotate about an axis (X) of rotation along a direction (V) of rotation and comprising a plurality of dosing drawers (4); said dosing drawers (4) being positioned along a circular surface of the rotary drum (3) at predetermined distances from each other and configured to receive the product along an angular loading path (P1 ) corresponding to a transit zone of the rotary drum (3) facing and in communication with the dosing chamber (1 );- a first screw feeder (5) housed inside the dosing chamber (1 ) and having an axis of rotation (X1 ) positioned tangential to the rotary drum (3), said first screw feeder (5) being configured to move the product within the dosing chamber (1 ) in a tangential direction (V1 ) , said dosing device being characterised by further comprising a second screw feeder (7) housed inside the dosing chamber (5) and having an axis of rotation (X2) positioned radially with respect to the rotary drum (3); said second screw feeder (7) being configured to move the product along a radial direction (V2) towards one of the dosing drawers (4) of the rotary drum (3).

2. The device according to claim 1 , wherein the first (5) and second (7) screw feeders lie on a common plane which is perpendicular to the axis (X) of rotation of the rotary drum (3).

3. The device according to claim 1 or 2, wherein the second screw feeder (7) has a shaft (8) provided with a spiral (9) having a cross section configured for pushing the product towards the rotary drum (3).

4. The device according to any one of the preceding claims, wherein the first screw feeder (5) and the second screw feeder (7) are respectively connected to a first drive unit (10) and a second drive unit (11 ) which are independent to one another.

5. The device according to any one of the preceding claims, wherein said second screw feeder (7) has a longitudinal extension less than the longitudinal extension of said first screw feeder (5).

6. The device according to any one of the preceding claims, wherein the dosing chamber (1 ) has a sloping rear wall (12) .

7. The device according to claim 6, wherein the dosing chamber (1 ) has a front wall consisting of a closing cover (13); said closing cover (13) having a sloping surface (14) facing the sloping rear wall (12).

8. The device according to any one of the preceding claims, wherein each dosing drawers (4) is formed by a respective radial depression provided on the circular surface of the rotary drum (3).

9. The device according to any one of the preceding claims, comprising a fixed containment wall (17) facing the rotary drum (3) along an angular path (P2) for transit of product contiguous to / and downstream of the angular loading path (P1 ), with reference to the direction (V) of rotation of the rotary drum (3).

10. The device according to claim 9, wherein the containment wall (17) comprises a head (18) for smoothing the product positioned adjacent to the angular loading path (P1 ).

11. The device according to claim 9 or 10, wherein the containment wall (17) forms a channel (19) facing the rotary drum (3) along the angular transit path (P2); said channel (19) having a variable depth decreasing along the direction (V) of rotation of the rotary drum (3), in such a way as to avoid the creation of excessive friction between the drum (3) and the side walls formed by the containment wall (17) and which could block the rotation of the drum (3) along said angular transit path (P2) and up to a zone for discharging the doses of product on the strip (S) of filter paper.

12. The device according to any one of the preceding claims, wherein said dosing chamber (1 ) comprises main zone (5a) and a side zone (6), and wherein the main zone (5a) houses the first screw feeder (5) and is placed above the rotary drum (3), and the side zone (6) houses the second screwfeeder (7) and is placed lateral to the rotary drum (3) under the main zone (5a).

13. The device according to claim 12, wherein said side zone (6) has a configuration tapered towards the second screw feeder (7).

14. A machine for making filter bags with infusion products comprising a plurality of forming stations (20-27) configured for making filter bags, and a station (20) for feeding the product comprising a dosing device (100) according to any one of the preceding claims and a feeding hopper (2) configured for feeding the product to said dosing device (100).

Images