GB2162788A

GB2162788A - Co-extrusion die assembly for a cooker extruder

Info

Publication number: GB2162788A
Application number: GB08420216A
Authority: GB
Inventors: Maurice Vincent
Original assignee: VINCENT PROCESSES Ltd
Current assignee: VINCENT PROCESSES Ltd
Priority date: 1984-08-09
Filing date: 1984-08-09
Publication date: 1986-02-12
Also published as: GB8420216D0

Abstract

A co-extrusion die assembly (4) for extruding a tube of cooked material around a filling is fed under pressure from a cooker extruder (1) with cooked material which passes through the die (4) along a passage to an outlet (5). A filling tube (6) with internal surface of low coefficient of friction follows a straight path through the die passage (3). The straight path avoids heat degradation of the filling that otherwise occurs with a filling tube extending along a path e.g. turning through 90 DEG , that is not straight. A plurality of passages and filling tubs may be provided in a single die (Fig 2), the passages each having an outlet parallel to a single inlet from the cooker extruder, with intermediate passage parts extending at an angle between the inlet and the outlets. <IMAGE>

Description

SPECIFICATION Co-Extrusion Die Assembly For A Cooker Extruder This invention relates to a co-extrusion die assembly for cooker extruders.

Existing die assembly designs used in the manufacture of co-extruded food products usually call for the exterior casing of the extrusion cooked food material to be produced and ejected from the die substantially in the form of a tube, and substantially in a direction along the centre line of the cooker extruder barrel.

Filling material is normally taken through the side of the die assembly to the centre of the extrusion cooked tube; at that point the flow direction of filling material is turned through 90 so that the direction is then in the same sense as the tube itself. Thereby, the filling and extrusion cooked tube leave the die head concomitantly, giving a continuously filled tube.

Thereafter, the filled tube may either be cut by means of a guillotine, crimped, or otherwise sectioned to give food products in piece form. Arrangements are also known wherein the tube profile can be changed either by changing the profile in the die head or by passage of the tube through external forming devices so that the resulting product may be of a different cross sectional shape to the essentially circular shape described above. Such shapes can be polygonal, and include triangular, square, rectangular, trapezoidal and may or may not have protrusions adhering to the outer casing.

Such a technique is satisfactory where the filling material meets certain requirements. For example, the filling material must not be so thermosensitive that it could adhere to the filling tube inside the die assembly, which can often reach quite high temperatures. Such filling material also need to be at such a viscosity that they can be satisfactorily injected by means of a pumping system or other technique. The existing designs of co-extrusion die assemblies call for the filling material to be turned through an angle of 90 ; the filling material is introduced through what is essentially a small bore tube; and temperatures can frequently be high.

Hence there is a limitation in terms of the rheological properties of acceptable filling materials as well as in their sensitivity to heat degradation.

It has been found by experiment, for example, that fillings which include appreciable percentages of natural cheese or real chocolate are difficult to handle in the conventional filling system because they tend to burn inside the filling tube in the die assembly.

The present invention has as its object to overcome or mitigate the difficulties experienced with the known co-extrusion die assemblies.

The present invention provides a co-extrusion die assembly for a cooker extruder, the die assembly comprising a passage for cooked material, said passage having an inlet end for receiving cooked material from a cooker extruder and an outlet end from which the cooked material is extruded as a tube, and a filler tube extending through at least the outlet end portion of said passage for feeding a filling material into the interior of the extruded cooked material, the filler tube following a substantially straight path'through the die assembly.

To enable the filler tube to follow a substantially straight path through the die assembly the outlet end of said passage may be angled or offset with respect to the inlet end thereof.

Preferably, the filler tube has an internal surface which is such that the filling material will not readily adhere thereto. To this end the filling tube may be formed from or lined with a material, such as a suitable plastics material, having a low coefficient of friction and a high degree of resistance to thermal degradation.

The present invention will be more particularly described with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a plan view of part of a typical cooker extruder fitted with a co-extrusion die assembly according to the invention, and Figure 2 is a view similar to Figure 1 but showing another embodiment of die assembly according to the invention.

Referring to Figure 1 the die assembly is shown attached to a twin screw cooker extruder; however, it could also be used in conjunction with simpler, single screw extruders if desired.

In operation, food materials such as cereal formulations would be cooked in the cooker extruder barrel 1. The cooked food product leaves the barrel and enters a right angled diverter 2. The extrusion cooked material passes, by virtue of the pressure generated in the cooker extruder barrel, along an annular cavity 3, through a co-extrusion die 4, and leaves the die assembly at outlet 5, essentially as a circular or profiled tube.

Filling material is injected into the tube by means of a plastics filling tube 6, which is inserted through a metal tube 7. The metal tube 7 is integral with the co-extrusion die 4, and is secured by means of a plate and seal system 8. In this way, the process material passing through channel 9 and channel 3, is totally enclosed and cannot escape except through the desired outlet 5. The inside of tube 7 is therefore at substantially atmospheric pressure and can receive tube 6 without the need for any pressure connections.

In operation, the filling tube 6 is connected to any desired system for transferring filling material into the cereal tube; such a system may employ a positive displacement or other type of pump, or other type of motive force to transfer the filling through tube 6 at a predetermined rate, into the cereal tube.

Figure 2 illustrates another embodiment of the invention in which like parts have been given like reference numerals and in which a multiple discharge arrangement is shown with several plastics filling tubes 6 inserted from the back of the die assembly. In the general case, one filling tube 6 would be used for each cereal tube produced.

Claims

1. A co-extrusion die assembly for a cooker extruder, the die assembly comprising a passage for cooked material, said passage having an inlet end for receiving cooked material from a cooker extruder and an outlet end from which the cooked material is extruded as a tube, and a filler tube extending through at least the outlet end portion of said passage for feeding a filling material into the interior of the extruded cooked material, the filler tube following a substantially straight path through the die assembly.

2. A die assembly according to claim 1, wherein the outlet end of said passage is angled or offset with respect to the inlet end thereof.

3 A die assembly according to claim 2, wherein the outlet end portion of said passage extends at right angles to the inlet end portion thereof and said filler tube extends coaxially of the outlet end portion of said passage.

4. A die assembly according to claim 2, wherein the outlet end portion of said passage is offset with respect to the inlet end portion thereof and extends parallel thereto, the outlet end portion and inlet end portion of said passage are connected by an intermediate portion which extends at an angle thereto and said filler tube extends through the die assembly coaxially of the outlet end portion of said passage.

5. A die assembly according to claim 4, comprising a plurality of outlet end portions of said passage each of which is connected to said inlet end portion by a said intermediate portion, each said outlet end portion having a said filler tube extending coaxially thereof.

6. A die assembly according to any one of the preceding claims, wherein said filler tube has an internal surface such that the filling material will not readily adhere thereto.

7. A die assembly according to claim 6, wherein said filler tube is formed from or lined with a material having a low coefficient of friction and a high degree of resistance to thermal degradation.

8. A die assembly according to claim 7, wherein said material having a low coefficient of friction is a plastics material.

9. A co-extrusion die assembly for a cooker extruder substantially as herein described with reference to Figure 1 or Figure 2 of the accompanying Drawings.