GB2239210A

GB2239210A - Apparatus far dividing screw extruded strips of ceramic material

Info

Publication number: GB2239210A
Application number: GB9027354A
Authority: GB
Inventors: Eberhard Steffens; Holger Kiessling; Gunter Fiedler
Original assignee: KEMA KERAMIKMASCHBAU GmbH
Current assignee: KEMA KERAMIKMASCHBAU GmbH
Priority date: 1989-12-22
Filing date: 1990-12-18
Publication date: 1991-06-26
Anticipated expiration: 2010-12-18
Also published as: GB9027354D0; CZ277787B6; CS607790A3; DE4028558A1; GB2239210B; DD290615A5; RU1838103C

Abstract

The apparatus comprises a mixer shaft which extends through a screen plate (4) of a press through which ceramic strips extrude into the vacuum chamber of the press. A cutting tool in the form of a cutting star, formed by a hub (5) and a plurality of cutting blades (6) extending radially therefrom, is mounted on the shaft downstream of the plate to cut the strips. The blades have angular position relative to the axis of the hub which rises from down 15 DEG at their base to 75 DEG at their free end. The blades (6) are helically twisted along their length at an angle to the hub axis which may be from down to 15 DEG at the face of the blades, to up to 75 DEG at their radially outward ends. The spacing between the blades (6) and the screen (4), is adjustable by shims. <IMAGE>

Description

1 i _1 C APPARATUS FOR DIVIDING A PLURALITY OF SMALL STRIPS OF CERAMIC

MATERIAL INTO SHORT SECTIONS The invention relates to an apparatus for dividing a plurality of small strips of ceramic material into short sections. The apparatus is disposed immediately downstream-of the screen plate of a vacuum press, as is used in the ceramics industry, and divides the strips issuing from the screen plate into short sections.

The area of use of the invention is thus in the ceramics industry.

In the fine ceramic industry, removing of air from the ceramic material during the processing and shaping procedures in the vacuum press is a matter of great significance. A material from which air has been effectively removed substantially affects the quality of the end product. In recognition of that situation, an adjustable screen plate has been used, as disclosed for example in DD patent specification No. 120 828. The plate comprises two bar plates which are rotatable relative to each other, whereby the geometrical shape of the strips of material issuing therefrom is to be influenced. Because the strips are of a sawtooth-like configuration, it is to be expected that they will be torn apart, thus providing an improved air removal effect. A disadvantage of that construction is, however, that it is not possible to achieve defined division of the strins.

Another known solution substantially eliminates that disadvantage. In that arrangement, disposed downstream of the pre- press and the vacuum chamber is a milling screw which mills up the elongate tubular strip produced by the pre-press, into fine chips or pieces. That arrangement thus provides that the, strip is divided up in a defined manner, as a pre-requisite for the 4 removal of air from the material in a highly effective manner.

That apparatus suffers from the disadvantage of involving a relatively high level of expenditure, the apparatus requiring both its own drive and a special mounting arrangement.

In another solution as described in German published specification (DEAS) No. 1 542 408 and which -serves for the production of granulate material from raw cement dust, a swing frame is disposed at the mouth opening of the screw press. The swing frame can be driven by way of a crank drive and a motor, while wires which are tensioned in the frame divide up the strips of material issuing from the press.

In another alternative construction the arrangement has a cutting wire which is rotated by means of a chain drive, for dividing up the strips of material. That construction also suffers from the disadvantage of requiring an additional drive.

It is also though that the arrangement of such an apparatus within the vacuum chamber of a screw press gives rise to problems, because of the cutting wires used.

The aim of the invention is defined division of the strips of material issuing from a screen plate within the vacuum chamber of a screw press.

The invention is based on the problem of providing an apparatus which, while being of relatively simple structure and with the avoidance of additional drive, permits defined division of the strips of material issuing from the screen plate of a vacuum press, within the vacuum chamber.

In accordance with the invention the specified problem is solved in that the cutting tool is arranged on the mixer shaft which is passed through the screen plate 1 1 4 way that a plurality of, preferably from three to six, radially directed cutting blades are fitted on the hub of the cutting star which is releasably connected to the mixer shaf t, and the cutting blades', starting f rom the base, have an angular position of 150 which rising to the free end of the cutting blade reaches a value of 750.

It is also a feature of the invention that the cutting blades are at a variable spacing relative to the screen plate and the cutting blades are sharpened at their cutting side at an angle of preferably 450.

It has been found advantageous for the angular position of the cutting blades to rise from 300 at their base to 600 at the free end.

The invention will now be described in greater detail, by means of an embodiment, with reference to the accompanying diagrammatic drawings, in which:

Figure 1 is a side view of the apparatus in the pre-press which is shown in partial section; Figure 2 is a front view of Figure 1; Figure 3 is a view of part of the cutting star; Figures 4 to 6 show three views in section through a cutting blade of 1,, )pe cutting star; and Figure 7 is a plan view of a cutting blade, without taking account of the angular position thereof.

Figure 1 is a diagrammatic view of an apparatus according to the invention which comprises a mixing casing 1 through which passes a mixer shaft 2 provided with mixing and kneading vanes 3.

The mixer shaft 2 passes through a screen plate 4 which is mounted in the mixing casing 1 and at its end carries a cutting star. The cutting star essentially comprises a hub 5 fitted with a plurality of cutting blades 6. The cutting star and the mixer shaft 2 are connected by means of a screw 7 so that their connection is releasable. The spacing between the cutting blades 6 - 4 and the screen plate 4 can be variably adjusted by spacers or shims (not shown).

Figure 2 shows the arrangement of the cutting blades 6, in the illustrated example six blades, which, are radially directed and jointly with the hub 5 form the cutting star.

Figures 3 to 6 show the configuration of the cutting blades 6 in closer detail. They are arranged on the hub 5 in such a way that at their base or root they are at an angular position of 300 relative to the axis of the hub 5. That angular position increases uniformly to the free end of the cutting blades 6 to about 600 (Figures 4 to 6), the blades thus being of a slightly helical configuration.

By using a different number of cutting blades 6, it is possible to influence the free passage through the screen plate 4.

As can be seen from Figure 7, the cutting side of the cutting blade 6 is sharpened at an angle of preferably 450.

1 z 4

Claims

1. Apparatus for dividing a plurality of strips of ceramic material, passing through the screen plate of a press, incorporating a mixer shaft, into short sections, wherein the apparatus comprises a cutting tool which is arranged immediately downstream of the screen plate, is mounted on the mixer shaft which passes through the screen plate, and is in the form of a cutting star including a plurality of cutting blades fitted on a hub and extending radially therefrom, the hub being releasably connected to the mixer shaft, and said blades, starting from their base, have an angular position of 150 relative to the axis of the hub which rising to their free ends reaches a value of 750.

2. Apparatus according to Claim 1 wherein the cutting star has 3 to 6 of said cutting blades.

3. Apparatus according to Claim 1 or 2, wherein the spacing of the cutting blades relative to the screen plate is variable.

4. Apparatus according to Claim 1, 2 or 3, wherein the cutting blades are sharpened at their cutting side at an angle of substantially 450.

5. Apparatus according to any one of Claims 1 to 41 wherein the angular position of the cutting blades rises from 300 at their base uniformly to 600 at their free end.

6. Apparatus according to Claim 1, constructed, arranged and adapted to operate substantially as herein described with reference to, and as shown in, the accompanying drawings.

Published 1991 at 71e Patent Office, State House. 66171 High Holborn, London WC1 R 47P. Further copies may be obtained from Sales Branch. Unit 6. Nine Mile Point Cwmfehnfach. Cross Keys. Newport NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent.