EP0177412A1 - Apparatus for crushing products, especially feedstuffs - Google Patents

Abstract

1. Crusher device for produce, agricultural food produce in particular, comprising a dispenser (1) allowing the device to be supplied with a produce (P) which moves against hammers (2) wherein the crushed material (3) appears on a grill, whilst the rejected particles (5) accompany the hammers, provision being, moreover, made for means for recycling these rejected particles, to allow these rejected particles (5) to be detached from the hammers and to be recycled, characterized in that the recycling means comprise a shaft (6), or a double wall through which the rejected particles (5) rise up to redescend into the crusher, the shaft (6), or double wall being arranged to issue in a zone (7) situated at the bottom of the dispenser (1) in such a way that the rejected particles (5) and/or the air fanned by the crusher carry the produce (P) supplied by the dispenser with them.

Description

The invention relates to a device for grinding products, in particular agrifood products, of the type which includes a distributor allowing the device to be supplied with a product which goes against hammers and in which the ground material is presented on a grid. , while the rejected particles accompany the hammers, means for recycling these rejected particles being further provided to allow these refused particles to be separated from the hammers and recycled.

Grinding devices of this type are known, in particular from US-A-1,975,406 which shows a grinding device in which the means for recycling the rejected particles are constituted by a kind of adjustable deflector flap. Such recycling means, by directing the rejected particles against the hammers, make it possible to avoid an excessive accumulation, in the grinding device, of rejected particles. However, the efficiency of such a grinding device needs to be improved, in particular with a view to reducing the energy consumed, the quality of the grinding and a reduction in noise; it is also desirable to minimize the heating of the product in the grinding device and its water losses.

The object of the invention is, above all, to make grinding devices of the kind defined above such that they meet the various requirements of the practice better than hitherto and in particular such that they no longer have, or to a greater extent lesser, the disadvantages mentioned above.

According to the invention, a device for grinding products, in particular agrifood products, of the type in question, is characterized in that the recycling means comprise a chimney, or a double wall, by which the rejected particles rise up to descend into the grinder.

Presented from another angle, a grinding device of the kind in question, according to the invention, is characterized in that the recycling means comprise a chimney or a double wall, determining a curved pipe which has an outlet branch, substantially rectilinear, whose outer surface is substantially coincident with a plane tangent to the path of the hammers, to allow the rejected particles to leave the grinding chamber, and a return branch capable of bringing the rejected and recycled particles back to the chamber grinding.

Advantageously, the chimney or double wall is arranged to open out at the bottom of the distributor so that the rejected particles, and / or the air ventilated by the crusher, entrain the product to be grind supplied by the distributor.

The grating of the grinding device is generally of semi-cylindrical shape, turning its concavity upwards, the upper edges of this grating being situated in a horizontal plane passing substantially through the axis of the grinder; the distributor is arranged above the hammers so as to ensure a supply of product substantially in the vertical plane passing through the longitudinal axis of the grid and the grinder.

The chimney, or the double wall, determines a curved pipe which has a vertical ascending branch, or substantially vertical, the outer surface of which is substantially coincident with a plane tangent to the upper edge of the grid, located last according to the direction of rotation of the drum carrying the hammers, said ascending branch bending, at its upper end, to descend and connect to the distributor, so that in the lower part of this distributor, located above the grinding chamber itself, the rejected and recycled particles entrain the product arriving by the distributor against hammers.

The chimney or the double wall makes it possible to recycle the air ventilated by the hammer mill and the rejected particles, recycled by this chimney or this double wall, are entrained at a relatively high speed. Thus, the momentum of the recycled particles is reused, thanks to the chimney, to increase the shock of these rejected particles, and of the product arriving by the distributor, against the hammers, so that the grinding is carried out in better conditions; the chimney or the double wall modifies the direction of this amount of movement so as to orient it in the proper direction to ensure such an increase in the grinding efficiency.

The return branch of the chimney, or of the double wall, can make an average angle of about 45 ^* with the outlet branch. The connection between the exterior surfaces of the outlet branch and the return branch is ensured by a substantially semi-cylindrical surface turning its concavity towards the interior of the chimney; preferably, the radius of curvature of this surface is at least equal to 150 mm.

Advantageously, the chimney or the double wall are arranged in such a way that the speed of the rejected recycled particles, on their entry into the grinding chamber, is substantially of the order of half the peripheral speed of the hammers. In the case of a crusher whose hammers have a speed of around 90 m / s, the rejects are recycled with a speed of around 40 m / s.

Advantageously, the chimney or the double wall extend along the entire axial length of the grinding device. This chimney or double wall can form a removable assembly suitable for being fixed on corresponding connection zones provided on the grinding chamber itself and on the distributor.

The product distributor in the crusher can be equipped with a densimetric separation device arranged to deflect laterally the product flow going towards the mill and to collect the heavier particles which undergo a less lateral deflection than the lighter particles.

The dispenser can also be fitted with a magnetic separator. An adjustable orientation flap can be provided at the entrance to the grinding chamber to adjust the flow of the mixture of the product and recycled rejected particles towards the hammers.

A grinding device, in accordance with the invention, exhibits markedly improved performance.

• La figure 1, de ces dessins, est une coupe transversale d'un dispositif de broyage conforme à l'invention.
• La figure 2, enfin, est une vue suivant la ligne II-II de la figure 1.

The invention consists, apart from the arrangements set out above, of a certain number of other arrangements which will be more explicitly discussed below in connection with a particular embodiment described with reference to the attached drawings, but which is in no way limiting.

• Figure 1 of these drawings is a cross section of a grinding device according to the invention.
• Figure 2, finally, is a view along line II-II of Figure 1.

Referring to the drawings, in particular to FIG. 1, one can see a grinding device or grinder B supplied by a distributor 1 with product P to be ground; this product to be ground P is in particular of the agro-food type and is constituted by grains of cereals or others. The product P falls by gravity into the distributor 1 and descends at a speed which can be considered as zero. This product P goes against hammers 2 articulated at the periphery of a rotary drum or rotor R. The grinding of product P is essentially carried out at the moment of the impact of a hammer 2 with product P coming from the distributor 1.

The ground material 3 is presented, at hammer speed, on a grid G of semi-cylindrical rotating shape its concavity upwards and located at the bottom of the mill. The two upper horizontal edges of the grid G are located in a horizontal plane Q passing through or substantially through the axis A of rotation of the rotor R. The grid G selects the finest particles 4 which pass through the grid and are collected in the bottom of the grinder.

The larger particles, as a result of insufficient grinding, constitute the rejected particles 5, or refusals, and accompany the hammers, upwards, at a speed close to these.

The crusher B includes means for recycling the rejected particles 5 allowing them to be separated from the hammers and recycled.

These recycling means, according to the invention, include a chimney 6 or a double wall through which the rejects 5 go up as indicated by the arrow 11 directed vertically upwards, to descend again, as indicated by the arrow f2 by entraining the product P in grains or seeds. The rejects 5 are therefore recycled in the zone 7 located at the bottom of the distributor and above the inlet of the grinding chamber 8 proper.

This enclosure 8 has a prismatic shape the cross section of which, visible in FIG. 1, has the shape of a rectangle surmounted by two inclined walls 9, 10 converging upwards, to ensure the connection between the enclosure and the lower part of the dispenser 1. Advantageously, this enclosure is formed by two assemblies, namely a sort of base 11, corresponding to the rectangular section, on which is fixed, removably by means of bolts or the like, the assembly 12 comprising the walls 9 and 10. The distributor 1 is itself fixed, in a removable manner, on the edges of the upper opening 13 of the assembly.

The chimney 6, or double wall, is fixed removably on the one hand at the level of the base 14 of the rising part on the edges of an opening 15 provided on the side of the enclosure 8, above the plane Q and, on the other hand, at the base 16 of the descending part, on the edges of an opening 17 distributor 1 for the connection of this chimney, above the opening 13.

This opening 13 extends along the entire axial length of the mill, above the rotor R, and preferably admits the vertical longitudinal plane passing through the axis A of the rotor, as the plane of symmetry. The product P to be ground arrives from one side of the opening 13, for example according to the representation in FIG. 1, from the left side of this opening 13; the recycled rejects 5 arrive on the other side of the opening 13, that is to say in the case of FIG. 1, on the right side of this opening 13. To promote mixing and entrainment of the product P with the recycled refuse 5, the partition 18 between the extension of the return from the chimney 6 and the product inlet pipe P stops at a distance h from the plane of the opening 13 sufficient for the desired drive be carried out in good conditions, as well as the mixture.

The plane of the opening 13 is itself located at a sufficient distance a above the horizontal tangent greater than the circle described by the ends of the hammers 2.

The distributor 1 can be arranged so as to allow the separation of undesirable particles before the product enters the grinding chamber 8 proper.

For this, according to the embodiment of Figures 1 and 2, the distributor 1, above the opening 13, is arranged to make the product P describe a winding path; the product P is first deflected laterally on a first side, with respect to the vertical (on the left, according to the representation in FIG. 1) by a deflector flap 19 orientable by rotation around an axis parallel to its edge upper perpendicular to the plane of Figure 1; the wall of the distributor 1, located on the side opposite the deflector 19, is also offset, in its upper part, on the same side as the deflector 19 relative to the vertical; this wall 20 then returns, in its lower zone 21, in an opposite direction, relative to the vertical, so as to deflect the product P again to bring it to the opening 13.

A sort of bucket 22, open upwards, and extending along the entire axial length of the mill, is provided against the wall 18, below the deflector 19 so as to extend laterally a little beyond the deflector in the direction of the wall 20 of the distributor 1; a grid 23, with adjustable passage opening, is provided in the mean longitudinal vertical plane, between the bucket 22 and the upper part of the deflector 19 to allow an intake of aspirated air flowing substantially in the direction of the arrow f3, this current of air then being deflected by the wall 21 and heading towards the opening 13.

The assembly of the deflector 19 and the cup 22, combined with the shape of the distributor 1 ensuring the lateral deviations of the product flow P, constitutes a densimetric separator. The heaviest particles are not sufficiently deflected laterally, during their fall, to escape the cup 22 which collects them; on the other hand, the light particles considered to be acceptable to be sent for grinding, bypass the bucket 22 and can reach the opening 13.

One can provide, in the lower part 21 of the distributor 1, a magnetic separator 24 comprising one or more magnets or electromagnets 25 closing an opening provided in the wall 21, these magnets or electromagnets, being themselves mounted on a frame 26 articulated around an axis, parallel to the axis A. It is thus possible to disengage these magnets 25 and recover the magnetic particles contained in the product P and stopped by this separator 24.

Below the opening 13, on the side of the distributor 1 with respect to the longitudinal vertical plane passing through the axis A, a deflector flap 27 can be provided articulated around an axis extending along its longitudinal upper edge, and whose angular position can be adjusted so that the flow of the mixture of product P and recycled rejects 5 is directed at the best angle to meet the hammers 2. On the side opposite the flap 27, one can provide a sort of tank 28 located above the horizontal tangent higher than the circle described by the hammers 2, and substantially at the level of the lower part of the deflector 27. This tank 28 is intended to recover heavier foreign particles, recycled with refusals 5. A hatch 29, which can be opened, is provided in the wall 10, above the tank 28 to give access to the latter and remove the particles therefrom.

The drum R has a cylindrical shape and comprises, at its two longitudinal ends, flanges 30, 31 (FIG. 2) in the form of discs whose plane is orthogonal to the axis A. These flanges 30, 31 are connected by rods 32, forming spacers, parallel to the axis A. Preferably, an intermediate flange 33, located mid-length of the mill, and similar to the flanges 30, 31, is provided. This flange 33 is crossed by the rods 32 which it supports. These rods 32 are located radially inwardly relative to the outer contour of the flanges.

The flanges 30, 31 and 33 are provided with holes, in the vicinity of their external contour, through which axes 34 pass, parallel to the geometric axis A, on which the hammers 2 are articulated. These axes 34 are distributed over all the periphery of the flanges so that the rotor R resembles a squirrel cage.

The hammers 2 are formed by sorts of articulated rectangular plates, in the vicinity of one of their short sides, on the axes 34. The hammers 2 are mounted to rotate freely on these axes 34; when rotation of the rotor R, under the effect of centrifugal force, the longitudinal direction of the hammers is oriented radially; in fact, the center of gravity of these hammers is located beyond, in the radial direction, of the axes 34. Spacer rings 35 are crossed by the axes 34 and serve, in particular, to support these axes to resist centrifugal forces. According to the embodiment of FIG. 2, two hammers 2 are provided in the longitudinal interval between two successive crowns 35 or between a crown 35 and the neighboring flange 30, 31 or 33. The crowns 35 leave a free space for the interior for the passage of the rods 32. Cylindrical sockets 36, threaded on the axes 34, serve as spacers between the hammers 2.

The flanges 30, 31, 33 are supported by a shaft 37 whose axis coincides with the geometric axis A. This shaft 37 passes through the end walls such that 38 closing the grinding chamber 8, and is supported, outside this enclosure, by bearings such as 39, provided with grease nipples such as 40. The shaft 37 is driven in rotation by an electric motor not shown, linked to said shaft 37 by a coupling. According to the representation in FIG. 2, the electric drive motor would be located on the left, with its axis in the extension of the shaft 37.

In the embodiment shown, the rotor R rotates around the axis A in the direction of the arrow K (Figure 1), that is to say in the counterclockwise direction.

The outer edge of the opening 15 and the outer wall of the rising or outlet part 6a of the chimney or double wall 6, are located in a longitudinal vertical plane substantially tangent to the upper edge of the grid G located last in the direction of rotation K. In the embodiment of FIG. 1, the rising part 6a of the chimney and the opening 15 are therefore located on the right of the mill B.

Thus, the refusals 5 which accompany the hammers 2 can escape tangentially upwards at the level of the opening 15.

The width 1 of the chimney 6 is the same as that of the opening 15. This width 1 can be of the order of 10 cm. The chimney 6 extends along the entire axial length V (Figure 2) of the mill.

The height & of the rectilinear part of the rising or exit branch 6a can be between 150 cm and 200 cm. The examples of numerical values are given for a rotor R whose axes 34 have their centers situated on a circumference whose diameter is of the order of 100 cm.

The chimney 6 determines a bent pipe.

The outer wall of the rising part 6a is connected to the outer wall of the descending branch 6b by a curved zone 41, constituted by a part of cylindrical surface turning its concavity inwards. The radius of curvature C of this surface 41 is of the order of at least 20 cm or more.

The mean line of the descending part 6b forms with the mean line of the rising branch 6a, that is to say with the vertical, an angle θ which is advantageously of the order of 45 °, and more generally between 40 ° and 50 °. The descending part 6b is delimited by an outer wall 42 and an inner wall 43. These two flat walls can converge slightly towards one another in the direction of the opening 16. The wall 43 can be connected by forming a dihedral, as shown in Figure 1, with the inner wall of the rising branch 6a. As a variant, this wall 43 could be connected to the interior surface of the branch 6a by a portion of cylindrical surface parallel to the surface 41.

We see that the rejects 5 recycled through the chimney 6 and entrained in the air stream stirred by the rotor R and circulating in the chimney 6, arrive at the bottom of the descending branch 6b with a speed oriented substantially at 45 ° relative to the vertical which, despite the deflector effect of the wall 18, allows the speed vector of these recycled rejects 5 to retain a horizontal component in the direction opposite to the rising branch 6a, that is to say towards the left according to the representation of FIG. 1. This component promotes the mixing of these refusals 5 with the product P which arrives, and therefore the entrainment of this product P, which has practically no speed, by the refusals 5 recycled . The deflector 27 allows the flow of product P and refusals 5 to engage in the free space 43 between the inner edge of the tank 28 and the deflector 27 to fall on the hammers 2 which arrive at the top of their circular trajectory. It should be noted that even in the absence of recycled rejects 5, the air flow stirred by the rotor R and circulating in the chimney 6 ensures the entrainment of the product P through the opening 13 at a significant speed which increases the impact of the product against the hammers 2, which is favorable for the good bursting of this product and for its grinding.

The operation of the mill according to the invention immediately results from the foregoing explanations.

The product P coming from a reserve, not shown (for example a hopper) situated above the mill, flows by gravity into the distributor 1. The too dense particles are collected in the cup 22 belonging to the densimetric separator. The magnetic particles, which constitute foreign bodies, are stopped by the magnetic separator 24.

The product P falls, through the opening 13, on the upper part of the rotor R. The grains of the product P are crushed by the impact with the hammers 2. They are driven, anticlockwise the movement of the rotor R to the grid G.

The particles 4, as already explained, sufficiently fine, pass through this grid G to be collected subsequently in the bottom of the grinding chamber 8.

The refusals 5 leave the enclosure 8, in a vertical upward direction, tangentially to the rotor, escaping through the outlet branch 6A, which is vertical in the example considered, to return to the upper part of the enclosure 8 via the return branch 6b.

These rejects 5 recycled by the chimney 6, as well as the air stirred by the rotor R, which return to the upper part of the grinding chamber 8 to enter through the opening 13 cause the product P at high speed.

The crusher, with the chimney 6, behaves somewhat like a fan.

This results in a significant improvement in the efficiency of the grinding and a reduction in the heating of the products inside the grinder.

In practice, with a rotor R rotating at a speed of 1500 revolutions / minute, in a grinder according to the invention, performance is obtained equivalent to that obtained with conventional grinders whose rotors rotate at 3000 revolutions / minute. Mechanical parts driven in rotation are therefore subject to lower stresses.

The supply of the grinding chamber with product P through the opening 13 takes place at a high speed with the machine's own energy thanks to the chimney 6 or double jacket. The latter is advantageously arranged so that the linear speed of the refusals 5 recycled in the zone 7 is equal to substantially half of the tangential speed of the hammers 2. For a tangential speed of the hammers 2 of the order of 90 m / s , the speed of refusals recycled in 7 is advantageously of the order of 40 m / s or more.

The shrinkage (loss of water from the product to be ground by heating) is reduced. The grinding cycle time is also reduced.

Air consumption is reduced; as a result, the requirements for necessary filtering surface are also reduced.

The invention is suitable for all products having to undergo a treatment with a view to reduction with hammer mills.

It is possible to moisten the product, to fix reals, molasses, protein, etc., in particular by introducing additives into the chimney 6.

You can grind wet or greasy products, because all these products tend to clog or grease machines.

Claims (12)

1. Grinding device for products, particularly agrifood products, comprising a distributor (1) allowing the device to be supplied with a product (P) which meets hammers (2) and in which the ground material (3) is present on a grid, while the rejected particles (5) accompany the hammers, means for recycling these rejected particles being further provided to allow these rejected particles (5) to be separated from the hammers and recycled, characterized in that the recycling means include a chimney (6), or a double wall, through which the rejected particles (5) rise to descend into the crusher. 2. Grinding device for products, in particular food products, comprising a distributor (1) allowing the device to be supplied with a product (P) which meets hammers (2) and in which the ground material (3) is present on a grid, while the rejected particles (5) accompany the hammers, means for recycling these rejected particles being further provided to allow these rejected particles (5) to be separated from the hammers and recycled, characterized in that the recycling means comprise a chimney (6) or a double wall, determining a curved pipe which has an outlet branch (6 &), substantially rectilinear, whose outer surface is substantially coincident with a plane tangent to the path of the hammers to allow particles refused (5) to leave the grinding chamber (8), and a return branch (6h) suitable for bringing the rejected and recycled particles to the grinding chamber. 3. Device according to claim 1 or 2, characterized in that the chimney (6) or double wall is arranged to open, in a zone (7) located at the bottom of the distributor (1) so that the particles rejected ( 5) and / or the air ventilated by the grinder entrain the product to be ground (P) supplied by the distributor. 4. Device according to any one of the preceding claims, characterized in that the outlet or rising branch (6 &) of the chimney or double wall, is a vertical rising branch, or substantially vertical, whose outer surface is substantially coincident with a plane tangent to the upper edge of the grid (G), located last according to the direction of rotation (K) of the drum (R) carrying the hammers (2), said ascending branch (6a) bending, at its upper end , to descend and form the return branch (6b) and connect to the distributor (1) so that in the lower part (7) of this distributor, located above the grinding chamber (8) proper , the particles (5) rejected and recycled entrain the product (P) arriving by the distributor against the hammers (2). 5. Device according to any one of the preceding claims, characterized in that the return or descending branch (6b) of the chimney (6) or of the double wall, makes an average angle (θ) of approximately 45 ° with the output or rising branch (6a). 6. Device according to any one of the preceding claims, characterized in that the connection between the external surfaces of the outlet or rising branch (6a) and of the returning or descending branch (5-b) is ensured by a surface (41) substantially semi-cylindrical turning its concavity towards the inside of the chimney. 7. Device according to claim 6, characterized in that the radius of curvature (C) of the semi-cylindrical surface (41) of connection is at least equal to 150 mm. 8. Device according to any one of the preceding claims, characterized in that the chimney (6) or double wall is arranged so that the linear speed of the rejects (5) recycled, upon their entry into the grinding chamber (8) is substantially equal to the half of the tangential speed of the hammers (2), and that in particular for a tangential speed of the hammers (2) of the order of 90 m / s, the speed of the refusals (5) recycled is of the order of 40 m / s. 9. Device according to any one of the preceding claims, characterized in that the distributor (1) is arranged above the hammers (2) so as to ensure a supply of product (P) substantially in the vertical plane passing through the longitudinal axis (A) of the mill. 10. Device according to any one of the preceding claims, characterized in that the chimney (6) or double wall, extends along the entire axial length of the grinding device. 11. Device according to any one of the preceding claims, characterized in that the chimney (6), or double wall, forms a removable assembly capable of being fixed on corresponding connection zones (15, 17) provided on the grinding end (8) proper and on the distributor (1). 12. Device according to any one of the preceding claims, characterized in that the dispenser (1) is equipped with a densimetric separation device (19, 22) arranged to laterally divert the flow of the product (P) going towards the grinder and collect the heavier particles which undergo a smaller lateral deflection than the light particles.

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