GB2091625A

GB2091625A - Mixing, granulating and sieving apparatus

Info

Publication number: GB2091625A
Application number: GB8137781A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-12-15
Filing date: 1981-12-15
Publication date: 1982-08-04
Also published as: AT366932B; CH655020A5; GB2091625B; DE3149492C2; DE3149492A1; ATA611280A

Abstract

Mixing or granulating apparatus is an improvement on that of U.S. Patent Specification No. 3,946,996 which describes an exhaustable mixing drum 10 with means for mixing, stirring and conveying solid material being treated and a pivotal support 12 for the drum and means 32, 33 for tilting it, and a tubular discharge housing 26 at one end of the drum which contains a sieve or screening means. An externally operable disc valve is now provided, which is operated by the wheel 40, which valve is arranged between the screening means and the drum 10, so that when the disc valve is closed the screening means is sealed from the drum when the screening means is not required to be used. An additional inlet 42 is provided on the screening means housing 26, which inlet is normally covered by a closure plate but can be used to unload the equipment into a container attached at outlet 36. <IMAGE>

Description

SPECIFICATION Mixing, granulating and sieving apparatus The invention relates to equipment for mixing and granulating powdery or granular substances.

To produce a powdered material from several substances such as is required as intermediate and final product in the pharmaceutical, food and cosmetics industry, a plurality of steps are required. Depending upon the product, these steps may comprise metering, mixing, moistening, granulating and drying, and in particular sieving in order to select a certain grain size.

German OLS 2,218,729 and the corresponding U.S. Specification No. 3,946,996 of which I am the inventor describe equipment for mixing and granulating powdery substances which permits the carrying out of these steps in the same machine from the mixing to the unloading of the granulate suitable for making tablets, whose composition and grain size has been previously determined. The U.S. Specification discloses apparatus which includes an exhaustable mixing drum or cylindrical vessel with closable feed and discharge means, a rotatably driven shaft on the drum axis carrying conveyance means for mixing, stirring and conveying the solid material being treated, and pivotal support means to adjustably tilt the drum such that the drum axis and the rotatable shaft are pivoted within a substantially vertical plane.There is preferably a tubular discharge housing at one end of the drum which contains a suitable sieve or screening means at the point where the final granular product is withdrawn from the drum. Preferably the lowermost inner wall line of a tubular discharge housing forms an angle of less than 20 with the corresponding lowermost inner wall line of the drum.

A problem of my prior sieving machine consists in the fact that when fitted to the drum it communicates permanently with the interior of the drum. Consequently, if the sieving machine is superfluous or a nuisance -- even if only temporarily - the entire sieving machine has to be removed during operation of the equipment and replaced e.g. by a closure plate.

Furthermore, cleaning of the aforedescribed equipment is relatively expensive and requires undesirable dismantling work.

It is an object of this invention to improve said equipment so that the sieving machine can be easily separated from the outside of the drum without the necessity of removing it, whereby the entire equipment including the sieving machine can be easily cleaned.

According to the invention this requirement is met in that in mixing apparatus of the aforesaid type a disc valve operable from outside is arranged between the sieve and drum, whereby the open position of the disc valve, the sieve and the rotating discharge unit communicate with the drum and whereby in the closed position the sieve is hermetically sealed against the drum, and a further valve is provided between the sieve and outlet.

The disc valve may be operated by means of a screw operable from outside and extending within the operational axis of the discharge unit.

The invention is further described by reference in the accompanying drawings, in which: Fig. 1 is a side view of a granulating apparatus according to the invention including a sieving discharge unit; and Fig. 2 is a perspective view of the sieving unit folded away from the granulating drum lid.

Referring to Fig. 1, a cylindrical drum 10 is rotatably hinged about a horizontal swivel axis 1 2 and whereby it is supported on a base 11. A rotary shaft (not shown) extending along the axis 1 3 of the drum is driven from a motor 14 attached at one end 1 5. The drum may have a double wall to allow the contents to be heated, and attached to the rotating shaft are mixing, stirring and conveying spirals or screws such as are described in the aforesaid Germany OLS No. 2,218,729 and U.S. Specification No. 3,946,996. The drum 10 is swingable about the axis 12 by means of a motor 32 and linkage 33. A lid 1 8 hinged to the drum at 20 facilitates access to the drum for cleaning and repairing purposes.The lid 1 8 may be provided with various openings for loading and unloading the drum contents; the inlet valve 2 shown is for admission of solid or liquid matter to be treated; this is preferably effected by sucking the material into the evacuated drum. The sieving machine 26 equipped with a motor 38, an outlet pipe 28 and an outlet valve 34 and flange 36 and an additional inlet 42 with a valve is provided for the purpose of sieving and removal of the product and is described in detail in the aforesaid two specifications as including a rotating shaft carrying at least one radial plate as a wiping means passing over the inner wall of a cylindrical sieve or screen.

At the upper end of the drum, remote from the lid 18, the equipment is preferably provided with a flange or similar arrangement forming the connection 1 6 for a conventional vacuumproducing and controlling system.

A flange provided at the lower end of the lid 18 serves as disc valve seat, and the sieving machine 26 is flange-mounted thereto. Fig. 2 shows the way in which the sieving machine 26 may be folded away from the lid 18 upon a hinge 62. In the closed, operative condition a gasket 54 attached in the flange 50 of the sieving unit 26 presses against a sealing surface in the valve seat 48 and heremetically seals the interior of the drum and the interior of the sieving unit from the outside atmosphere.

Inside the sieving machine 26 is a disc valve 58 which is movable, externally in the direction of the axis 44 of the sieving unit. At its outer circumference the disc valve 58 is provided with a gasket 42, which may e.g. consist of the fluorelastomer Viton or another suitable resistant material. If the disc valve 58 is moved in the direction of the drum by means of a manually or mechanically operated crank drive 40 (spiral), the disc valve 58 comes to rest against the valve seat 48, and the interior of the drum 10 is hermetically separated from the interior of the sieving machine by means of the gasket 42 during granulation. in the discharge unit 60 rotated by means of a drive motor 38, in Fig. 2 are seen three curved radial wiping plates, in end view.

An outlet 28 for discharge of sieved product is provided in a lower section of the jacket of the sieving machine 26. At the end of outlet 28 a valve 34 is arranged; this valve has an outlet flange 36 to which a hose or container for receiving product may be flange-mounted.

For discharge, the disc valve 58 is opened by the spira! shaft operated by wheel 40, when the apparatus is tilted so that the drive motor 14 is downwards. Discharge is effected through the rotating screen of the unit 26, preferably by slow mixing and gradually tilting the apparatus to tip the contents of the drum into the sieving unit 26, to avoid blocking the screen with excessive material.

By this construction according to the invention, the sieving machine may remain permanently on the granulating apparatus and the entire apparatus including the sieving machine can easily be washed. For this purpose the valve 34 is closed and the disc valve 58 is opened so that drum and sieving machine may be filled with water or another cleaning agent. Thereupon all the mechanisms are operational and the equipment is cleaned. With the equipment according to the invention it is possible to drain the dirty cleaning agent, which may contain toxic or highly dangerous substances, into special tanks without opening the equipment, this ensures effective protection of the operating personnel.

If after cleaning and draining of the cleaning agent it is required to dry the entire apparatus, the valve 34 is simply closed, whilst the disc valve 58 is opened and the entire apparatus is exhausted by means of a vacuum pump.

The upper part of the sieving machine 26 has an additional inlet 42 which terminates in a flange 52, which in the arrangement shown in Fig. 1 is short-circuited via a hose 24 from the drum inlet valve 22. However, during normal operation the flange 52 is covered by a closure plate (not shown). The purpose of connection of apertures 22 and 42 via hose 24 is to unload the equipment into a container which is hermetically attached at outlet 36, to avoid air overpressure in the container by the helix of the sieving unit. This air propulsion of the helix is conducted back through hose 24 into the apparatus.

Claims

1. Mixing or granulating apparatus which comprises an evacuable drum which is mounted so as to be pivotable in the plane containing the axis of the drum, and which contains a drive shaft arranged on the drum axis and carrying mixing, stirring and conveying means, a discharge screening means being mounted in a housing hinged onto one end of the drum and an externally operable disc valve being arranged between the screening means and the drum whereby when the disc is closed the screening means is sealed from the drum.

2. Apparatus as claimed in Claim 1, wherein the disc valve is operated by a screw extending in the operational axis of the discharge unit.

3. Apparatus as claimed in Claim 1, substantially as hereinbefore described with reference to or as shown in the accompanying drawings.

4. A method of operating apparatus as claimed in Claim 1,2 or 3, wherein the discharge screening means is not required the disc valve is closed to seal the drum from the screening means.