GB2188247A - Dosing and blending unit for food/ plastics processing - Google Patents

Abstract

The dosing and blending unit has a mixing bowl (11) having a lid which at its centre supports a drive motor (10) for an agitator (12). Situated around this lid and equidistant from its centre there are metering heads. These metering heads consist of rotating discs (15) with holes which volumetrically meter materials in various forms into the mixing bowl. Drive to each of these discs is taken from the central drive motor (10) via timing belts and pulleys (13). The use of clutches (16) enables this drive to be intermittent to vary the ratio of one material to another. Because of the dusty conditions inside the mixing bowl the drive pulleys/ clutches etc. are totally enclosed in a sealed closure fitted to the underside of the top lid. <IMAGE>

Description

SPECIFICATION Dosing and blending unit for food/plastic processing This invention relates to a dosing and blending unit commonly used in feed processing/plastics processing and other related industries.

Dosing and blending units can be used in a wide range of industries whereby two or more materials in either powder, granule or liquid form need to be accurately dosed into a central mixing chamber where they are then blended together using a stirring arm. The dosing of each of these materials is carried out by depositing a quantity of the particular material into a canister which is set above the mixing bowl. At the bottom of each canister is a rotating disc which carries a quantity of holes. As the disc rotates a precise quantity of material drops through an orifice which holds a rubbertube 18. The rubber tube just touches the face of the rotating disc thereby acting as a wiper blade. Hence material can only be metered if an empty hole passes beneath the rubber tube (orifice) i.e. when the disc is rotating.Therefore with the disc rotating material fills the hole at one side of the canister and then falls out on the other side into the mixing bowl see fig 3.

Hence dosing and blending units generally require the use of a series of electric motors one to operate a mixing arm and one to operate each of the dosing discs, of which there could be several i.e. one for each material. The particular recipe or blend of material is achieved by rotating each disc for a different length of time.

Electric motors along with their switchgear are however relatively expensive. Furthermore when in use in the mode described i.e. with constant switching on and off, they are also prone to overheating.

According to this particular invention see fig 1 there is provided only one central mixing motor 10 which points down into the mixing bowl 11 and holds the stirring arm 12 this motor generally has a low R.P.M. i.e. 1S50 R.P.M. and rotates continuously. Now this same motor on the same shaft carries also a number of timing pulleys 13 which in turn drive other timing pulleys 14 spaced around the first. The second timing pulleys can therefore be used to rotate the disc 15 which meters the granular or powder materials. Now on the shaft of this second timing pulley an electrically operated clutch 16 can be mounted, this can be used to switch on and off the drive to each of the discs.

Hence from one central mixing motor we can also cheaply and efficiently provide intermittent drive to each of the dosing discs of which there could be numerous.

The length of time for which each disc rotates determine the particular blend or recipe of materials and this depends upon how long each clutch is left engaged, this is controlled digitally by means of an electronic control panel in the normal way.

EXAMPLE OF FOUR STATION BLENDING UNIT i.e.

FOUR ADDITIVES See fig 2 This is purely an example and in fact any number of additives can be metered in the same way.

Referring to the drawing fig 2 the central motor is mounted onto a rigid plate 17 which takes the form of the mixing bowl lid. The shape of the lid is such that it can accept any number of additive canisters around its circumference. The same lid is machined such that it can hold each of the bearing mounted clutches 16. Also machined in the lid are two holes for each of the additive canisters. These holes are used to allow material to drop either into the mixing bowl during operation (position 1) or external to the mixing bowl during callibration (position 2). This callibration is an important part of any volumetric metering system. Callibration is made easier with this invention since when the clutches are not engaged each of the canisters can be turned through 1800 to the callibration position. Similarly they can be also removed for cleaning purposes.

1. dosing and blending unit comprising a round conical stainless steel mixing bowl The mixing bowl itself carries a close fitting machined covered lid on which is mounted a central mixing motor with stirring arm.

2. A dosing and blending unit as claimed in claim 1 wherein timing pulleys are mounted onto the mixing arm. These pulleys provide rotary drive to various other points around the central drive motor.

3. A dosing and blending unit as claimed in claim 1 and 2 wherein the secondary drive pulleys are fixed via a common shaft to an electrically operated clutch. This clutch therefore provides intermittent rotary drive to a metering device situated above the lid ofthe mixing chamber.

4. A dosing and blending unit as claimed in claim 3 also carries any number of metering heads. The concept of each head is of the form of a rotary disc containing a number of holes. As the disc rotates past an orifice (wiper blade) material is allowed to fill each hole to its top. Each hole full of material is then allowed to fall into the mixing area.

5. A dosing and blending unit as claimed in claim 4 wherein the metering head when the clutch is deenergised can be via the operation of two simple catches, either removed for cleaning or alternatively turned through 1800 such that the design port is moved from the automatic position i.e. dosing into the mixing chamber to a second position external to the mixing chamber for callibration purposes.

6. A dosing and blending unit substantially as described herein with reference to figures 1-3 of the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Dosing and blending unit for food/plastic processing This invention relates to a dosing and blending unit commonly used in feed processing/plastics processing and other related industries. Dosing and blending units can be used in a wide range of industries whereby two or more materials in either powder, granule or liquid form need to be accurately dosed into a central mixing chamber where they are then blended together using a stirring arm. The dosing of each of these materials is carried out by depositing a quantity of the particular material into a canister which is set above the mixing bowl. At the bottom of each canister is a rotating disc which carries a quantity of holes. As the disc rotates a precise quantity of material drops through an orifice which holds a rubbertube 18. The rubber tube just touches the face of the rotating disc thereby acting as a wiper blade. Hence material can only be metered if an empty hole passes beneath the rubber tube (orifice) i.e. when the disc is rotating.Therefore with the disc rotating material fills the hole at one side of the canister and then falls out on the other side into the mixing bowl see fig 3. Hence dosing and blending units generally require the use of a series of electric motors one to operate a mixing arm and one to operate each of the dosing discs, of which there could be several i.e. one for each material. The particular recipe or blend of material is achieved by rotating each disc for a different length of time. Electric motors along with their switchgear are however relatively expensive. Furthermore when in use in the mode described i.e. with constant switching on and off, they are also prone to overheating. According to this particular invention see fig 1 there is provided only one central mixing motor 10 which points down into the mixing bowl 11 and holds the stirring arm 12 this motor generally has a low R.P.M. i.e. 1S50 R.P.M. and rotates continuously. Now this same motor on the same shaft carries also a number of timing pulleys 13 which in turn drive other timing pulleys 14 spaced around the first. The second timing pulleys can therefore be used to rotate the disc 15 which meters the granular or powder materials. Now on the shaft of this second timing pulley an electrically operated clutch 16 can be mounted, this can be used to switch on and off the drive to each of the discs. Hence from one central mixing motor we can also cheaply and efficiently provide intermittent drive to each of the dosing discs of which there could be numerous. The length of time for which each disc rotates determine the particular blend or recipe of materials and this depends upon how long each clutch is left engaged, this is controlled digitally by means of an electronic control panel in the normal way. EXAMPLE OF FOUR STATION BLENDING UNIT i.e. FOUR ADDITIVES See fig 2 This is purely an example and in fact any number of additives can be metered in the same way. Referring to the drawing fig 2 the central motor is mounted onto a rigid plate 17 which takes the form of the mixing bowl lid. The shape of the lid is such that it can accept any number of additive canisters around its circumference. The same lid is machined such that it can hold each of the bearing mounted clutches 16. Also machined in the lid are two holes for each of the additive canisters. These holes are used to allow material to drop either into the mixing bowl during operation (position 1) or external to the mixing bowl during callibration (position 2). This callibration is an important part of any volumetric metering system. Callibration is made easier with this invention since when the clutches are not engaged each of the canisters can be turned through 1800 to the callibration position. Similarly they can be also removed for cleaning purposes. CLAIMS

1. dosing and blending unit comprising a round conical stainless steel mixing bowl The mixing bowl itself carries a close fitting machined covered lid on which is mounted a central mixing motor with stirring arm.

2. A dosing and blending unit as claimed in claim 1 wherein timing pulleys are mounted onto the mixing arm. These pulleys provide rotary drive to various other points around the central drive motor.

3. A dosing and blending unit as claimed in claim 1 and 2 wherein the secondary drive pulleys are fixed via a common shaft to an electrically operated clutch. This clutch therefore provides intermittent rotary drive to a metering device situated above the lid ofthe mixing chamber.

4. A dosing and blending unit as claimed in claim 3 also carries any number of metering heads. The concept of each head is of the form of a rotary disc containing a number of holes. As the disc rotates past an orifice (wiper blade) material is allowed to fill each hole to its top. Each hole full of material is then allowed to fall into the mixing area.

5. A dosing and blending unit as claimed in claim 4 wherein the metering head when the clutch is deenergised can be via the operation of two simple catches, either removed for cleaning or alternatively turned through 1800 such that the design port is moved from the automatic position i.e. dosing into the mixing chamber to a second position external to the mixing chamber for callibration purposes.

6. A dosing and blending unit substantially as described herein with reference to figures 1-3 of the accompanying drawing.