METHOD AND DEVICE FOR EXTRUSION, PARTICULARLY OF EDIBLE MASSES

Abstract: The mass to be extruded is forced into an extrusion duct (die) (1) so as to make it emerge in the extruded state from the outlet end (3) of the duct in a direction (2) generally-axial of the duct itself. An annular flow of fluid is generated around the outlet end (3) of the extrusion duct (1), oriented in an axial direction relative to the extrusion duct (1), and surrounds the extruded mass, preventing it from bending accidentally. The extruded mass is divided into pieces by a cutting operation (9) carried out within (7) the zone in which the annular flow of fluid acts.

Description: The present invention relates to the extrusion of masses through an extrusion duct (die) having an outlet end of predetermined diametral dimensions, in which the mass to be extruded is forced into the duct and emerges from the outlet end of the extrusion duct in the extruded state in a generally-axial direction relative to the extrusion duct itself. Figure 1 of the appended drawings illustrates schematically, in axial section, an extrusion device operating according to the prior art after which the pre-characterising portions of Claims 1 and 6 were patterned. In this case the mass which is being extruded is geneally indicated M. The extrusion duct or die is indicated 1 and its outlet end, centred around the principal axis 2 of the duct 1, is indicated 3. The means which allow the necessary pressure to be exerted on the mass M to be extruded to force it into the extrusion duct 1 are considered to be generally known. Furthermore, their structure and configuration are not relevant per se, either for an understanding of the technical problem on which the invention is based, or for an understanding of the solution according to the invention. The Applicant has noticed that, when an extrusion structure of the type illustrated in Figure 1 is used to extrude an edible, pasty mass, such as a mixture of sugar and pectin, with quite a high linear extrusion velocity, for example of the order of 10-15 m/min or more, deformation of the extruded mass occurs, causing it to move away from the principal axis 2 of the extrusion duct 1, as illustrated schematically in the lower part of Figure 1. This occurs even when the extrusion is carried out vertically, that is with the duct 1 held with its principal axis 2 disposed vertically. Without wishing to tie himself to any specific theory in this regard, the Applicant has reason to believe that the bending of the extruded mass can be attributed essentially to the manifestation of localised adhesion of the external walls of the extruded mass to the edge of the end 3 of the extrusion duct 1. In any case, the bending of the extruded mass is such that,when the mass is subsequently divided into pieces by a cutting operation, carried out, for example, with a rotary blade, the pieces obtained are generally curved in shape, or, so to speak, bean- or banana-shaped. This problem is particularly serious when the pieces obtained from the extruded mass are intended to be coated subsequently in order to form products of the type generally known as "dragees". For example, the coated product sold by the Applicant under the Trade name "TIC-TAC" includes a centre produced from a mixture of sugar and pectin, having a cylindrical shape with a length of approximately 9 mm and a diameter of approximately 2 mm. Up to now, a moulding process has had to be used to make these centres, as it has not been possible - for the reasons explained above to use a method of extrusion and subsequent cutting. The object of the present invention is to provide a method for extruding masses, and in particular edible masses, through an extrusion duct, which does not give rise to the problems explained above, particularly as regards the possibility of obtaining a mass in the extruded state which does not bend at the outlet of the extrusion duct and which can thus be divided into substantially cylindrical pieces. According to the present invention, this object is achieved by means of a method having the features called for in Claim 1. Preferably, the annular flow moves in the same direction as the extruded mass and is generated in a zone which extends for a certain distance from the outlet end of the extrusion duct, in an axial direction relative to the extrusion duct itself; the extruded mass is then divided into pieces by a cutting operation carried out within this zone. The invention also relates to a device for extruding edible masses by a method as set forth in Claim 6. The invention will now be described, purely by way of non-limiting example, with reference to the appended drawings, in which: Figure 1, which refers to the prior art, has already been described above, and Figure 2 illustrates schematically, also in axial section, a device for carrying out the extrusion method of the invention. In Figure 2, the same reference numerals 1 to 3 have been used to indicate parts corresponding to those already described with reference to Figure 1, that is to say, the extrusion duct, its principal axis and its outlet opening. For simplicity of explanation, reference will be made here to an extrusion duct 1 which, like its outlet end 3, has a completely circular section with a predetermined diameter. For example, with reference to the product mentioned in the introduction to the description, the opening 3 may have a diameter of approximately 2 mm. A tubular or sleeve-shaped body indicated 4 has a cylindrical through-hole 5 with a slightly greater diameter than that of the opening 3. The body 4 is applied to the outlet 3 of the extrusion duct 1 in alignment with its principal axis 2. The hole 5 of the body 4 thus defines a tubular duct which extends as an elongation of the extrusion duct 1 from its outlet end 3 and in an axial direction relative to the extrusion duct 1. This auxiliary or additional tubular duct has a generally greater diameter than the predetermined diameter of the outlet end 3 of the extrusion duct 1. Consequently, in use, the wall of the cavity 5 defines an annular separation zone around the external surface of the extruded mass M emerging from the duct 1. A source of pressurised fluid supplies at least one supply duct 6 which opens into this annular zone, preferably adjacent the outlet end 3 of the duct 1, the pressure source consisting, for example, of a pump unit 7 which supplies air (possibly purified and dehumidified) into the duct 6 at a relative pressure in the range 0.5 to 1.5 atmospheres, preferably approximately 1 atmosphere. Operation of the pump unit 7 causes compressed air to flow into the annular separation zone between the internal wall of the cavity 5 and the mass M which emerges, in the extruded state, from the extrusion duct 1. An annular fluid flow (air or gas) is thus generated around the outlet end 3 of the extrusion duct 1 and tends to emerge from the annular zone at the open end 5a of the cavity 5 opposite the outlet end 3 of the extrusion duct 1. The annular fluid flow thus created is centred around the principal axis 2 and therefore moves axially of the extrusion duct 1 in the same direction as the movement of the extruded mass emerging from the outlet end 3 of the extrusion duct 1. The function of this annular fluid flow, which surrounds the mass in the extruded state, is essentially that of stabilising the mass, to prevent it from bending, as illustrated schematically in Figure 1 with reference to the prior art. In other words, the flow which is established within the cavity 5 (formed of air, which, like the extruded mass, is at a temperature substantially equal to the ambient temperature) forms a sort of tubular guide which surrounds the extruded mass, keeping it straight without, however, any physical contact with the wall of the cavity 5 recurring. In particular, although the best extrusion results are obtained from vertical operation, that is, with the principal axis 2 common to the extrusion duct 1 and the auxiliary tubular duct 4 kept vertical, the guiding of the extruded mass by the annular flow of compressed air is effective even when the process is carried out with the axis 2 inclined to the vertical. A cutting element is generally indicated 8 and consists, for example, of a rotary cutter, whose blade 9 acts on the extruded mass M to divide it into pieces at the outlet end 5a of the cavity 5. The Applicant has, in fact, been able to observe that qualitatively better results are obtained when the cutting operation is carried out within the zone in which the annular stabilising flow acts. The effects of this flow are apparent in a zone which extends for a certain distance from the outlet end 3 of the extrusion duct 1 in an axial direction relative to the extrusion duct 1 itself. The effects of this action gradually decrease with increasing distance from the outlet end 5a in which the annular flow acts. It is therefore preferable to operate strictly adjacent (and virtually coincident with) the outlet end, that is, still keeping within the zone in which the annular fluid flow acts. Even though the use of a gas flow is considered preferable, it should be remembered that functionally similar results can be obtained by generating a flow of liquid (for example a food lubricant) within the cavity 5, supplied under pressure through the duct 6.

Claims: A method of extruding a mass (M) through an extrusion duct (1) of a die, the extrusion duct having an outlet end (3) centred around the principal axis (2) of the extrusion duct (1) so as to form a cylindrically shaped extruded mass, characterised in that for the purpose of preventing the extruded mass from bending, a tubular duct (4) is provided, which tubular duct (4) extends as an elongation of the extrusion duct (1) from its outlet end (3) in an axial direction relative of the extrusion duct (1), which tubular duct (4) has an inner cylindrical shape of a diameter greater than the diameter of said outlet end (3) so as to form an annular separation zone around the cylindrical surface of the extruded mass, said tubular duct (4) has a conduit (6) opening into said annular separation zone, the conduit (6) is connected to a pressurised fluid supply means (7),wherein the extruded mass is exclusively guided by means of the generated annular flow of the fluid within said separation zone. A method according to Claim 1, characterised in that it includes the operation of generating the annular fluid flow in a zone (5) extending for a certain distance from the outlet end (3) of the extrusion duct (1) in an axial direction relative to the extrusion duct (1) itself and the operation of dividing the extruded mass into pieces (8, 9) by a cutting operation carried out within (5a) the said zone. A method according to Claim 1 or Claim 2, characterised in that the annular fluid flow is generated in the same direction as the direction of movement of the extruded mass (M) emerging from the outlet end (3). A method according to any one of Claims 1 to 3, characterised in that the fluid flow consists of a gas flow (5a). A method according to any one of Claims 1 to 4, characterised in that, in use, the extrusion duct (1) is oriented substantially vertically. A device for extruding a mass (M) through an extrusion duct (1) of a die, the extrusion duct having an outlet end (3) centred around the principal axis (2) of the extrusion duct (1) so as to form a cylindrically shaped extruded mass, characterised in that for the purpose of preventing the extruded mass from bending, a tubular duct (4) is provided, which tubular duct (4) extends as an elongation of the extrusion duct (1) from its outlet end (3) in an axial direction relative of the extrusion duct (1), which tubular duct (4) has an inner cylindrical shape of a diameter greater than the diameter of said outlet end (3) so as to form an annular separation zone around the cylindrical surface of the extruded mass, said tubular duct (4) has a conduit (6) opening into said annular separation zone, the conduit (6) is connected to a pressurised fluid supply means (7),wherein the extruded mass is exclusively guided by means of the generated annular flow of the fluid within said separation zone. A device according to Claim 6, characterised in that said conduit (6) is located principally adjacent the outlet end (3) of the extrusion duct (1). A device according to Claim 6 or Claim 7, characterised in that the fluid-supply means comprise a compressed gas source (7). A device according to Claim 8, characterised in that the gas source (7) generates gas at a relative pressure within the range substantially 0.5 to 1.5 atmospheres. A device according to Claim 8, characterised in that the gas source (7) generates gas at a relative pressure of substantially 1 atmosphere. A device according to any one of Claims 6 to 10, characterised in that the tubular duct (4) has an inlet end applied to the outlet end (3) of the extrusion duct (1) and an outlet end (5a), and in that cutting means (8, 9) are provided for dividing the extruded mass (M) emerging from the outlet end (3) of the extrusion duct (1) into pieces, and in that the cutting means (8, 9) act in correspondence with the outlet end (5a) of the tubular duct (4).

Inventors: FERRERO, PIETRO
Applicants: FERRERO S.P.A.
Application year: 1987
Main classification: B30B11
IPC codes: B30B11, A23P1, A23G3