FR2889818A1 - EXTRUDER WITH ADJUSTABLE GAP AND EXTRUSION SCREW - Google Patents

Abstract

The extruder (1) comprises at least one extrusion screw (2), a sheath (3), and an extrusion die (4), the sheath (3) and the extrusion die (4) forming a assembly which is movable relative to the extrusion screw (2) and which is guided in translation along an axis (D) substantially parallel to the longitudinal axis of the extrusion screw. It further comprises actuating means (6) which make it possible to translate the sleeve (3) / die assembly (4) in translation between a first configuration, called a working configuration, in which the extrusion screw (2) is housed inside the sleeve (3), and a second configuration, called open, in which the extrusion screw (2) is disengaged from the sleeve (3). These actuating means (6) also allow in the first working configuration a millimetric adjustment of the gap, that is to say the position of the die (4) with respect to the extrusion screw ( 2), over a short predefined distance.

Description

EXTRUDER WITH ADJUSTABLE GUN AND EXTRUSION SCREW

discoverable

  TECHNICAL FIELD The present invention relates to a new and improved extruder 5, which can be used in particular in the food industry.

  PRIOR ART In the agri-food industry, it is customary to manufacture by extrusion expanded products intended in particular for human food (for example biscuits, chips, cereal bars, etc.) or for animal feed (for example, pet foods). such as dogs, cats, ..., aquaculture food products, feeds for cattle, including cattle, ovids, pigs, equines).

  Generally, the expanded products are obtained by kneading, baking and extrusion in an extruder, of particulate material (s) based in particular on flour or semolina from the grinding of cereals (soybean, wheat, maize, rice, etc.). ) or animals (eg fish meal, shrimp, ...).

  By way of example, the international patent application WO01 / 72150 describes an installation comprising in series a preconditioner, an extruder, and a feed screw interposed between the preconditioner and the extruder. The extruder usually comprises at least one extrusion screw rotatably mounted inside a heating sleeve (for example sheath equipped with heating collars).

  Dry particulate matter (eg flour from the grinding of cereals or animals) or dry mix of particulate material (eg mixture of one or more flours and additive (s) in particulate form, eg vitamins, vitamin mineral supplements) is introduced into the preconditioner. Where appropriate, one or more liquid or semi-liquid products (for example liquid nutritional supplement, fat, oil, dye, materials of plant or animal origin) are also introduced into the preconditioner. Water and, if appropriate, water vapor are also introduced into the conditioner.

  The mixture in the preconditioner is intensely kneaded and partially cooked. At the outlet of the conditioner, a homogeneous mixture is obtained which is then introduced into the extruder either directly or by means of a feeding device. Preferably, but not necessarily, there is used a twin-screw extruder comprising two co-rotating and co-penetrating parallel rotating screws.

  Under the action of heat, pressure and shear, the material, as it progresses in the extruder, expands and cooks. When the operation of the extruder is stabilized (after the initial start-up phase), an extruded final product is obtained at the outlet of the extruder in the form of a continuous and shaped strand whose cross-section is given by the exit section of the extruder die. This expanded bead is then cut into products of predefined length by any appropriate in-line cutting means.

  When using an extruder, it is essential to be able to adjust and control the quality of extruded products, including their density. To allow this adjustment, it is necessary to finely adjust the size of the space between the head of the extrusion screw and the extrusion die. For example, Japanese Patent Application JP03262471 proposes a technical solution for adjusting the distance (commonly referred to as air gap) between the head of the extrusion screw and the extrusion die. This solution is based on the implementation of short cylinders (referenced (9) in Figures let 2 of the publication JP03262471) and mounted at the rear part of the sheath of the extruder.

  To carry out maintenance operations (especially cleaning or checking), modification, repair or replacement of the extrusion screw or screws, it is also necessary to have access to the extrusion screw (s) housed inside the sheath.

  For this purpose, with an extruder such as that described for example in the aforementioned publication JP03262471, one is forced to manually remove and remove the sleeve in order to completely disengage the extrusion screw or screws. On the one hand, this requires a heavy manual intervention.

  On the other hand, one is prejudiced to wait for the cooling of the screw and the sheath before any intervention.

  OBJECT OF THE INVENTION The main object of the present invention is to propose a new extruder, in particular that can be used in the food industry, which allows both a quality adjustment of the extruded products and a quick and easy access to the screw (s). extrusion, especially during maintenance operations or modification or replacement of said extrusion screw or screws.

  SUMMARY OF THE INVENTION The subject of the invention is thus an extruder which, in known manner, comprises at least one extrusion screw, a sleeve and an extrusion die.

  Characteristically according to the invention, the sheath and the extrusion die form an assembly which is movable with respect to the extrusion screw and which is guided in translation along an axis (D) substantially parallel to the longitudinal axis ( A) the extrusion screw; the extruder comprises actuating means which make it possible to move the sheath / die assembly in translation between a first configuration, known as work configuration, in which the extrusion screw is housed inside the sheath, and a second configuration , said open, in which the extrusion screw is disengaged from the sleeve, and the actuating means further allow in the first working configuration a millimetric adjustment of the position of the die with respect to the extrusion screw on a short distance (d) predefined.

  More particularly, the installation of the invention comprises the following additional and optional features, taken separately or, if appropriate, in combination: the actuating means comprise a first bidirectional linear actuator for translating the sheath / die between the first working configuration and the second open configuration, and a second bidirectional linear actuator for millimetric adjustment of the position of the die; the first actuator is a two-position cylinder; the first actuator is a hydraulic, pneumatic or electric cylinder; the second actuator is a millimeter cylinder.

  the second actuator is a hydraulic or electric cylinder; the first and second actuators consist of two linear actuators mounted in opposition; in an alternative embodiment, the actuating means comprise a plate which is movable relative to the extrusion screw and guided in translation, and on which is mounted the sheath / die assembly; - Preferably, the extruder comprises a cutting device which is mounted at the die outlet, and which is movable in translation with the sleeve / die assembly.

Description of figures

  Other features and / or advantages of the invention will appear more clearly on reading the detailed description below of a preferred embodiment of an extruder of the invention. This detailed description is given by way of non-limiting and non-exhaustive example of the invention, and with reference to the accompanying drawings in which: - Figure 1 is a side view of an extruder of the invention, the whole sheath / die being in the so-called working configuration, - Figure 2 is a side view of the extruder of the invention, the sheath / die assembly being in the so-called open configuration, - Figure 3 is a view of Figure 4 is a top view of the extruder of Figure 2, Figure 5 is a detail view of the space between the screw head and the die. extrusion, in the working configuration of the extruder, said space being adjusted with a minimum air gap, - Figure 6 is a detailed view of the space separating the head of the screws and the extrusion die, in the configuration of working of the extruder, said space being adjusted with a maximum air gap, Figure 7 is a diagram of the actuating means for moving the extrusion sleeve / die assembly.

detailed description

  FIGS represented in the figures an extruder 1 that can be used in the food industry for the continuous manufacture of food products based in particular and for example flour from the grinding of cereals or animals.

  Said extruder 1 may for example (but not exclusively) be used in an installation of the type described in publication WO 01/72150, and comprising, upstream of the extruder, means for feeding and preparing the material to be extruded. (In particular preconditioner and possibly feed screw).

  With reference to FIGS. 1 and 3, the extruder 1 comprises, in the usual manner per se: two co-rotating and co-penetrating extrusion screws 2, whose longitudinal axes (A) are substantially parallel, a heating sleeve 3 comprising mainly a substantially cylindrical tubular element 30 intended to receive the extrusion screws 2, and equipped on its outer periphery with heating collars 31 or any other equivalent heating means, - an extrusion die 4 which is fixed to the front end of the tubular element 30 of the sheath 3, and which in the particular example illustrated has a convergent 41 allowing during extrusion guiding the material so that the two screws 2, motorized means 5 (geared motor) and associated motion transmission kinematic chain) for rotating, at a controlled speed, the two extrusion screws 2 along their longitudinal axis (A).

  The novelty of the extruder 1 of the accompanying figures lies in the implementation of the actuating means 6 of the sheath 3 / die assembly 4, a particular example of structure and operation will now be detailed.

  The extrusion screws 2 and the sheath 3 are fixed on a plate 60, by means of supports 61. This plate 60, and by the same assembly sheath 3 / die 4 embedded, is movable in translation relative to the extrusion screws 2, along an axis D parallel to the longitudinal axes (A) of the extrusion screws 2, and between two extreme positions: a first extreme position corresponding to the working configuration of the figures let 3, a second extreme position corresponding to the open configuration of Figures 2 and 4.

  The movable plate 60 is guided in translation along the axis D with respect to the fixed frame B of the extruder 1, in particular by means of rollers 62 mounted free to rotate.

  To allow the translational movement of the movable plate 60 and the sleeve assembly 3 / die 4 on board, the actuating means 6 comprise two cylinders 64 and 65 in opposition. The jack 64 is a bidirectional linear hydraulic cylinder with two positions (jack type all or nothing) and long stroke. The jack 65 is a bidirectional linear hydraulic cylinder of millimeter type and short stroke. The body 64a of the jack 64 is fixed to the carrier frame B, below the level of the movable plate 60. The jack 65 is embedded on the movable plate 60, the body 65a of this jack 65 being fixed on the lower face of the movable plate 60 The two rods 64b and 65b of the two jacks 64 and 65 are attached end to end by means of a coupling sleeve 66.

  The jack 65 makes it possible to control a bidirectional and millimetric displacement of the sheath 3 / die assembly 4, when said sheath 3 / die assembly 4 is in the working configuration [see below air gap adjustment (d)]. The jack 64 makes it possible to control a bidirectional displacement over a long stroke of the sheath 3 / die assembly 4 between the working configuration of FIGS. 1 and 3 and the open configuration of FIGS. 2 and 4.

  More particularly, with reference to FIG. 7, the control means 67 of the two jacks 64 and 65 mainly comprise a hydraulic circuit comprising: an oil reservoir 670 for supplying oil to the two jacks 64 and 65; a gear pump 671 controlled by an electric motor 672 and for supplying parallel oil to a solenoid valve 673 for the control of the jack 64 and a servo-distributor 674 for the control of the jack 65, - between the pump 671 and the two cylinders 64 and 65 , a pressure gauge 675a isolated by a valve 675b, a non-return valve 675c, a pressure filter 675d, a 675e pressure switch with digital display, - an oleopneumatic accumulator 676 which is associated with a manually operated safety block 677, and which allows to overcome any leaks in the hydraulic circuit of the cylinder 65 by maintaining a constant oil pressure in the cylinder chamber 65 when it is adjusted in position.

  Also to control in position the rod 65b of the cylinder 65, the control means 67 comprise an electrical control circuit which is associated with the jack 65, and which mainly comprises: detection means 678 of the instantaneous position of the rod 65b, which detection means deliver a detection signal 678a which encodes the instantaneous position of the rod 65b of the jack 65, a comparator 679 which receives as input the aforementioned detection signal 678a and a reference signal Sc delivered by a control automaton ( not shown) and coding the desired adjustment position for the rod 65a of the cylinder 65, said comparator 679 outputting an error signal 679a as a function of the difference between the detection signal 678a and the reference signal Sc; this error signal 679a allows the adjustment by the distributor 674 of the desired positioning for the rod 65b of the jack 65.

  Adjusting the air gap (d) With reference to FIG. 6, the distance (d) measures the distance between the rear face 41a of the die 4 and the free end before 2a of the extrusion screws 2, when the sheath 3 / die assembly 4 is in the working configuration. This gap (d) is commonly called gap. In FIG. 6, the gap (d) is set to a maximum value (dmax); in FIG. 5, the gap (d) is set to a minimum value (dmin). The maximum and minimum values (dmax) and (dm; n) of the gap (d) of the extruder 1 are predefined parameters. For example, and without limitation of the invention, dmax is 13 mm and drain is 1 mm, which corresponds to a 12 mm Ad adjustment range for the gap (d).

  The adjustment of the gap value (d) between the two maximum (dmax) and minimum (dm; n) predefined values depends on the extruded product, and conditions the quality of this product, in particular its density. It will therefore be advantageously adjusted case by case depending on the extruded product.

  When the sleeve assembly 3 / die 4 is in the working configuration (FIG. 1), the adjustment of the value of the gap (d) between the two predefined limits (dmax) and the minimum limit (dmin) is carried out with precision millimeter by means of the cylinder 65, the final position of the rod 65b of the cylinder being set by means of the aforementioned setpoint signal Sc.

  When the rod 65b of the jack 65 is moved in the direction of the rod 64b of the other cylinder 64 (FIG. 1 / arrow E1), it bears on the fixed rod 64b of the jack 64 and the jack 65 regrows in a millimetric manner. set plate 60 / sleeve 31 / die 4 in the opposite direction (Figure 1 / arrow E2), which results in increasing the value of the gap (d). Conversely, when the rod 65b of the jack 65 is moved in the opposite direction (FIG. 1 / arrow E2), the jack 65 pulls on the plate 60 / sleeve 3 / die assembly 4 and moves millimetrically together in the opposite direction (Figure 1 / arrow El), which results in decreasing the value of the gap (d).

  Once the air gap (d) has been adjusted to millimetric accuracy by means of the cylinder 65, the extruder 1 can be used to extrude the product. During extrusion, it is possible to control the quality of the extruded product, and to adjust the air gap (d) by means of the jack 65 with millimetric precision.

  Opening / Closing of the Extruder When the operator wishes to access the extrusion screws 2, for example to perform cleaning, checking, modification or replacement operations on these screws, he actuates the movable plate 60 by means of the cylinder 64 (displacement of the rod 64b of the cylinder in the direction of the arrow O of FIG. 1), so as to bring the on-board sheath 3 / die assembly 4 into the open configuration of FIGS. 2 and 4.

  In the open configuration of Figures 2 and 4, the extrusion screws 2 are discovered and easily accessible by an operator. The use of the jack 64 advantageously facilitates the withdrawal operations of the sheath assembly 3 / die 4 (open configuration) and implementation of this assembly on the extrusion screws 2 (working configuration). Also, the use of the jack 64 advantageously makes it possible to discover the extrusion screws 2 without having any contact with the sheath 3. It is therefore possible to discover the extrusion screws 2 by removing the sheath 3 / die assembly. 4 without waiting for the sheath 3 has cooled, which advantageously decreases the response time.

  When the operator wishes to put back into operation the extruder 1, he repositioned by means of the jack 64 the whole sheath 3 / die 4 with respect to the extrusion screws, by moving the rod 65b of the jack in the direction of the arrow F of FIG. 2 until the sheath 3 / die assembly 4 is brought into the working configuration of FIG. 1.

  Preferably, in the example illustrated in the accompanying figures, the extruder 1 comprises, at the outlet of the die 4, a cutting device 7, which allows in operation to cut the continuous coil of expanded product from the extrusion die 4, in the form of expanded products of smaller dimensions. The cutting system 7 is known per se and can be of any known type. In particular it may consist of a cutting system using a rotary cutting wire or by means of one or more cutting blades, or a water jet cutting system.

  The novelty of the implementation of this cutting device 7 lies in the fact that it is embedded and fixed on the movable plate 60, so that during the opening operation of the extruder, the device of cutout 7 is spaced apart from the extrusion screws 2, at the same time as the sheath 3 / die assembly 4.

  The invention is not limited to the implementation of the two hydraulic cylinders 64 and 65 above, which can be replaced by any actuator or set of actuators equivalent performing the same function. By way of non-exhaustive examples, the jack 64 may also be a pneumatic or electric cylinder. The millimeter cylinder 65 can also be an electric cylinder. Also each cylinder 64 65 can be replaced by an equivalent linear actuator and for example by a rack / gear assembly controlled by a motor or geared motor.

  When the jack 65 is replaced by another type of linear actuator, it is important that this actuator allows a displacement of the sleeve 3 / die assembly 4 with millimeter precision when this set is in the working configuration.

  Also, the invention is not limited to a twin-screw extruder, but can be implemented on any extruder comprising at least one extrusion screw 2.

Claims (10)

  An extruder (1) comprising at least one extrusion screw (2), a sleeve (3), and an extrusion die (4), characterized in that the sleeve (3) and the extrusion die ( 4) form an assembly which is movable with respect to the extrusion screw (2) and which is guided in translation along an axis (D) substantially parallel to the longitudinal axis (A) of the extrusion screw, in that it comprises actuating means (6) which make it possible to translate the sleeve (3) / die assembly (4) in translation between a first configuration, called a working configuration, in which the extrusion screw (2) is housed inside the sheath (3), and a second configuration, called open, in which the extrusion screw (2) is disengaged from the sheath (3), and in that the actuating means (6) allow in addition in the first working configuration a millimetric adjustment of the position of the die (4) relative to the extrusion screw (2) over a short distance (d) predicted over.   2. Extruder according to claim 1 characterized in that the actuating means (6) comprise a first bidirectional linear actuator (64) for translational movement of the sleeve assembly (3) / die (4) between the first working configuration and the second open configuration, and a second bidirectional linear actuator (65) for millimetric adjustment of the position of the die (4).   3. Extruder according to claim 2 characterized in that the first actuator (64) is a cylinder with two positions.   4. Extruder according to claim 2 or 3 characterized in that the first actuator (64) is a hydraulic cylinder, pneumatic or electric.   5. Extruder according to claim 2 characterized in that the second actuator (65) is a millimeter cylinder.   6. Extruder according to claim 5 characterized in that the second actuator (65) is a hydraulic or electric cylinder.   7. Extruder according to one of claims 2 to 6 characterized in that the first and second actuators are constituted by two linear cylinders (64, 65) mounted in opposition.   8. Extruder according to one of claims 1 to 7 characterized in that the actuating means (6) comprise a plate (60) which is movable relative to the extrusion screw (2) and guided in translation, and on which is mounted the sleeve assembly (3) / die (4).   9. Extruder according to one of claims 1 to 8 characterized in that it comprises a cutting device (7) which is mounted at the die outlet (4), and which is movable in translation with the sleeve assembly (3). ) / die (4).   10. Extruder according to claims 8 and 9 characterized in that the cutting device (7) is fixed on the movable plate (60).