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EP 1 227 889 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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22.03.2006 Bulletin 2006/12 |
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Date of filing: 02.10.2000 |
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International Patent Classification (IPC):
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International application number: |
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PCT/EP2000/009660 |
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International publication number: |
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WO 2001/032311 (10.05.2001 Gazette 2001/19) |
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A ROLLER MILL FOR GRINDING GRANULAR MATERIALS, PARTICULARLY CEREALS
WALZENMÜHLE ZUM MAHLEN VON KÖRNIGEM MATERIAL INSBESONDERE GETREIDE
MOULIN A CYLINDRES POUR LE BROYAGE DE MATERIAUX GRANULEUX, EN PARTICULIER LES CEREALES
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Designated Contracting States: |
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CH DE IT LI |
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Designated Extension States: |
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RO |
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Priority: |
02.11.1999 IT PD990242
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Date of publication of application: |
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07.08.2002 Bulletin 2002/32 |
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Proprietor: Agrex S.p.A. |
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35010 Curtarolo (IT) |
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Inventor: |
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- BARBIERI, Silvano
I-35010 Curtarolo (IT)
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Representative: Fabris, Stefano et al |
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Cantaluppi & Partners S.r.l.
Via Matteotti 26 I-35137 Padova I-35137 Padova (IT) |
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References cited: :
EP-A- 0 949 003 US-A- 1 497 108
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DE-B- 1 146 730
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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Technical Field
[0001] The present invention relates to a roller mill for grinding granular materials, particularly
cereals, according to the preamble to main Claim 1.
Background Art
[0002] Within the field of milling technology, towards which the present invention is particularly
but not exclusively directed, there are known mills which have one or more pairs of
contrarotating rollers spaced apart by a predetermined distance such that a gap is
defined between their respective cylindrical surfaces for the passage of the material
to be ground.
[0003] In these mills, there is generally provision for several successive stages of grinding
of the cereal until flours ground to the desired extent are produced. In this case,
between one grinding stage and the next, there is a stage in which the products of
the grinding are classified to separate the finer material from the coarser material
in a manner such that the products thus separated are sent to subsequent grinding
stages provided according to the dimensions of the ground material.
[0004] A grinding mill having the features of the preamble of claim 1 is known from US 1497108.
[0005] From the European patent application No. EP-A-0949003 is known a mill for grinding
cereals, comprising, in succession, two separate milling passages with respective
contrarotating rollers and a sifting device interposed between the passages. The sifting
device comprises a rotating member which affects the product that leaves the first
milling passage so as to propel it against a screening surface in order to separate
a significant amount of product before the second milling passage. In the roller mill
disclosed in this document it is further provided that the product propelled through
the screening surface and the product which leaves the second milling passage are
successively combined and sent to a separation and classification unit, for example
to a plansifter.
[0006] In regard to this last feature, the known mills have conveyor devices for transporting
the material ground by the rollers into special screening devices. For example, it
is known to provide for the products of the grinding to be transported and lifted
to the inputs of separators having one or more screens with meshes of different sizes
disposed one above another so that, as the product poured in from the top falls down,
it is separated into grades having homogeneous dimensions.
[0007] An arrangement of this type, which requires the provision of conveyors and lifting
devices between the rollers and the separator for each grinding stage, is fairly onerous
and also leads to a degree of structural complexity. Moreover, since the conveyors
permit a localized and concentrated discharge of the material onto the screens of
the separator, a constant and uniform distribution of the material on the screen cannot
be ensured, necessitating a larger screening surface to avoid the risk of excessive
supply and interruptions in the supply of the material and a consequent reduction
in efficiency and output yield.
Disclosure of the Invention
[0008] The technical problem upon which the present invention is based is that of providing
a roller mill for grinding granular materials, particularly cereals, which is designed
structurally and functionally to overcome the disadvantages complained of with reference
to the prior art mentioned.
[0009] This problem is solved by the invention by means of a roller mill formed in accordance
with the appended claims,
Brief Description of Drawings
[0010] The characteristics and the advantages of the invention will become clearer from
the detailed description of an embodiment thereof, given with reference to the appended
drawings, provided by way of non-limiting example, in which:
- Figure 1 is a partially-sectioned perspective view of a roller mill according to the
invention,
- Figure 2 is a partially sectioned side elevational view of the mill of Figure 1,
- Figure 3 is a perspective view corresponding to Figure 1.
Best Mode of Carrying out the Invention
[0011] With reference to Figure 1, a roller mill for grinding cereals, such as corn, wheat
and the like, formed in accordance with the present invention, is generally indicated
1.
[0012] The mill 1 comprises one (or more) pairs of contrarotating rollers 2 between which
a gap 3 is defined for the passage of the material to be ground, and a feed device,
generally indicated 4, positioned above the rollers 2 and including a vibrating hopper
5 for holding the material to be ground as well as supplying it and directing it into
the gap 3 by means of deflector elements 6.
[0013] The rollers 2 are supported rotatably on a framework 7 of the mill and are located
inside a body 8 which, below the rollers, has walls 8a inclined so as to converge
at an outlet 8b aligned vertically with the gap 3.
[0014] Drawer-like bodies, indicated 9, positioned between the rollers 2 and the outlet
8b, are mounted removably on the body 8 and serve for collecting samples of the ground
material output by the rollers.
[0015] The mill 1 also comprises a screening device, generally indicated 10, mounted beneath
the rollers 2 by means of a framework 11. Defined in the device 10 are a first chamber
12 in communication with the outlet 8b and a second chamber 13 separated from and
in communication with the chamber 12 by means of a perforated screening surface 14a
of a screen 14.
[0016] The screen 14 comprises a substantially semicylindrical frame 14b extending parallel
to the longitudinal axes of the rollers and having a length substantially corresponding
to the axial length of the rollers. This represents a preferred selection, although
the screen may have an orientation and an axial dimension different from those of
the rollers.
[0017] The frame 14b is fixed to the framework 11 removably and a net or a cloth with interwoven
threads, constituting the perforated screening surface 14a of the screen, is stretched
over it.
[0018] In the first chamber 12 there are also stirring means comprising a rotor 15 with
radial blades 16 and with an axis of rotation preferably parallel to the axes of rotation
of the rollers 2 and spaced from a vertical plane tangential to the rollers in the
region of the gap 3.
[0019] Each blade 16 comprises a plurality of appendages 16a projecting radially from the
rotor 15 in a rake-like configuration. The positioning of the rotor 15 inside the
chamber 12 is selected in a manner such that the free ends of the blades pass close
to the perforated surface of the screen 14 on their circular path. Brushes 17 are
also provided at the free ends of the blades 16 to constitute means for cleaning the
surface of the screen.
[0020] On the opposite side to the screen 14, the chamber 12 has a polygonal-profiled configuration
defined by a pair of inclined deflectors 18, 19 the second of which also constitutes
means for directing the flow of ground material supplied to the chamber 12 through
the outlet 8b.
[0021] Concerning this, it should be noted that, by means of the deflector 19, the ground
material is directed to fall by gravity on the screening surface 14a with a path substantially
directed tangentially to the surface (Figure 2).
[0022] The chamber 12 is also in communication with an end of a duct 20, through an opening
21 from which the material rejected by the screen 14 is discharged, as will be explained
further in the following description. The opposite end of the duct 20 is connected
to a conveyor means 22, for example of the vertical screw type, provided for lifting
the ground material rejected by the screen up to the hopper 5.
[0023] The second chamber 13 comprises side walls 13a which are inclined so as to converge
at an output opening 23 beneath which a horizontal conveyor 24, for example of the
screw type, is disposed. The conveyor 24 is provided for transporting the ground material
into a pneumatic conveyor 25 which in turn is intended to transport the material to
subsequent processing stages in accordance with the preselected grinding pattern.
[0024] In addition to the functions described above, the rotor 15 with radial blades serves,
as a result of its rotation, to give rise to an intake of air through one or more
intakes positioned in the upper portion of the body 8, which are for example formed
by a perforated portions 8c of the body. The air drawn in is discharged through one
or more outlets positioned at the side walls 13a of the chamber 13, labeled by the
reference 13b, and at the output of the conveyor 24 in the region of the intake of
the pneumatic conveyor 25.
[0025] By virtue of the intake of air discharged in the region of the output of the conveyor
24 and of the side walls of the chamber 13, a circulation of air, the function of
which will become clearer from the following description, is also induced and drawn
through the rollers 2 as well as through the first and second chambers 12, 13. This
air circulation takes place through the above-mentioned air-intakes. In Figure 3,
the flow direction of the forced circulation of air is schematically indicated by
arrows labelled A.
[0026] In operation, the material ground by the rollers 2 falls into the chamber 12 of the
screening device by gravity and is separated by means of the screen 14. The separated
material falls into the chamber 13 where it passes through the outlet 23 and is collected
by the conveyor 24 and transported to the intake of the pneumatic conveyor 25 which
transports the material to subsequent processes, whilst the material rejected by the
screen 14 is moved and transported into the duct 20 by the bladed rotor 15 in order
to be lifted up to the hopper 5 by the vertical conveyor 22 and to be ground further
by another pair of rollers of a subsequent passage. It should be noted that the transportation
of the rejected material into the duct 20 is facilitated by the deflectors 18, 19
provided in the upper portion of the chamber 12. During the rotation of the rotor
15, the brushes 17 provided at the ends of the blades 16 keep the perforated surface
14a of the screen clean so as to facilitate the separation of the ground material
which falls into the chamber 12 continuously by gravity. Moreover, the rotation of
the rotor is such as also to create swirling air movements inside the chamber 12 which,
by drawing air from the upper portion of the body 8, induce a circulation of air through
the rollers, in the body, as well as through the chambers of the separator. This circulation
of air, to which any contribution provided by the suction means (not shown) associated
with the pneumatic conveyor is added, is such as to bring about cooling of the rollers
as well of the ground material.
[0027] The invention thus solves the problem posed, achieving many advantages in comparison
with known arrangements.
[0028] A first advantage lies in the fact that, since the ground material is supplied directly
onto the screening device of the mill according to the invention by falling by gravity,
no conveyor and/or lifting means are required for supplying this device, with the
consequence of structural simplifications as well as greater efficiency of the system
by virtue of the related saving in energy and power.
[0029] A second advantage is due to the fact that the material ground by the rollers falls
on the screening surface of the screen substantially in the form of a continuous "film"
which is uniform over the entire axial length of the rollers so as to tangentially
cover (Figure 2) the screening surface of the screen with a uniform and even distribution,
without excessive supply or interruptions, thus achieving an improved output yield
of the material and requiring less maintenance.
[0030] Another advantage consists of the fact that the circulation of air induced by the
rotation of the screening device of the invention helps to keep continuously cooled
the rollers and the cereal itself which tend to be heated during the grinding operations,
so that the chemico-physical characteristics of the cereal are kept intact and an
improved overall efficiency of the mill is achieved. Moreover, the air circulation
permits a greater homogenization of the product during the grinding operations.
[0031] Also another advantage is that the mill according to the invention allows a complete
classification of the ground product without requiring any further classification
unit (plansifter) or sifting machines, downstream to the mill.
[0032] The installation plant costs are also reduced because the mill according to the invention
involves overall spaces more limited than the known solutions in which the presence
of plansifters or similar devices requires vertical extensions also of three or four
times larger.
1. A roller mill for grinding granular materials, particularly cereals, comprising:
- at least one pair of contrarotating rollers (2) between which a gap (3) is defined
for the passage of the material to be ground, and
- a screening device (10) associated with the rollers (2) for separating the products
of the grinding according to the dimensions of the ground material, the screening
device (10) comprising a screening surface (14a) positioned lower down to the rollers
(2) in such a position to be directly supplied by gravity, by falling of the material
ground by means of the rollers (2),
characterized in comprising
- conveyor means (19) interposed between the rollers (2) and the screening surface
(14a) to direct the material supplied by gravity, by falling from the rollers, along
a falling path on the screening surface (14a) which is substantially directed tangentially
to said surface (14a).
2. A mill according to Claim 1, in which the screening device (10) comprises a first
chamber (12) supplied with the falling material ground by the rollers (2), a second
chamber (13) separated from and in communication with the first chamber (12) by means
of said screening surface (14a), the second chamber (13) being intended to collect
the material screened by means of said surface (14a) .
3. A mill according to Claim 2, in which stirring means (15,16) are provided in the first
chamber (12) for stirring and transporting the rejected material from the screening
surface (14a) towards an outlet (21) from the first chamber (12).
4. A mill according to Claim 3, in which first conveyor means (22) are provided for lifting
up the ground material rejected by the screening surface (14a) and discharged through
said outlet (21), to a supply hopper (5) of the rollers (2) to be ground further by
the rollers.
5. A mill according to Claim 3, in which the stirring means comprise a bladed rotor (15)
and the screening surface (14a) extends at least partially along a portion of the
path described by the rotation of the blades (16).
6. A mill according to Claim 5, in which the rotor (15) has an axis of rotation substantially
parallel to the axis of rotation of the rollers (2).
7. A mill according to one or more of Claims 1 to 4, in which second conveyor means (24,
25) are associated with an outlet (23) of the second chamber (13) for the transportation
of the material separated by the screening surface (14a) .
8. A mill according to Claim 7, in which the conveyor means are pneumatic or mechanical.
9. A mill according to Claim 7, in which air-intake means are associated with said second
conveyor means (24, 25) .
10. A mill according to Claim 9, in which said air-intake means comprise one or more intakes
(8c) provided upstream to the rollers, the rotation speed of the rotor (15) being
selected so as to induce and draw a forced air circulation through the rollers (2).
11. A mill according to one or more of the preceding Claims, in which the screening surface
(14a) is fixed in the screening device (10) removably.
1. Walzenmühle zum Mahlen von körnigem Material, insbesondere Getreide, umfassend:
zumindest ein Paar von gegendrehenden Walzen (2), zwischen denen ein Spalt (3) für
den Durchgang des zu mahlenden Materials definiert ist, und
eine Siebvorrichtung (10), die mit den Walzen (2) in Verbindung steht, um die Produkte
des Mahlvorgangs gemäß den Abmessungen des gemahlenen Materials zu trennen, wobei
die Siebvorrichtung (10) eine Sieboberfläche (14a) umfasst, die unterhalb der Walzen
(2) in einer solchen Position angeordnet ist, dass sie direkt durch die Schwerkraft
beschickt wird, indem das gemahlene Material mittels der Walzen (2) herabfällt, dadurch gekennzeichnet, dass sie umfasst:
eine Fördereinrichtung (19), die zwischen den Walzen (2) und der Sieboberfläche (14a)
angeordnet ist, um das Material, das durch Schwerkraft durch Herabfallen von den Walzen
zugeführt wird, entlang eines Fallpfades, der im Wesentlichen tangential zu dieser
Oberfläche (14a) ausgerichtet ist, auf die Sieboberfläche (14a) zu leiten.
2. Mühle nach Anspruch 1, bei welcher die Siebvorrichtung (10) eine erste Kammer (12),
welcher das von den Walzen (2) gemahlene, herabfallende Material zugeführt wird, eine
zweite Kammer (13), die mittels der Sieboberfläche (14a) von der ersten Kammer (12)
getrennt und mit dieser verbunden wird, umfasst, wobei die zweite Kammer (13) dazu
ausgelegt ist, das Material, dass mittels der Oberfläche (14a) gesiebt wurde, zu sammeln.
3. Mühle nach Anspruch 2, bei welcher eine Rühreinrichtung (15, 16) in der ersten Kammer
(12) zum Rühren und Transportieren des von der Sieboberfläche (14a) abgesonderten
Materials von der ersten Kammer (12) zu einem Auslass (21) vorgesehen ist.
4. Mühle nach Anspruch 3, bei welcher eine erste Fördereinrichtung (22) zum Anheben des
gemahlenen Materials, das von der Sieboberfläche (14a) abgesondert und über den Auslass
(21) ausgegeben wurde, zu einem Zuführtrichter (5) der Walzen (2) vorgesehen ist,
damit es von den Walzen weiter gemahlen wird.
5. Mühle nach Anspruch 3, bei welcher die Rühreinrichtung einen mit Schneiden versehenen
Rotor (15) umfasst und die Sieboberfläche (14a) sich zumindest teilweise entlang eines
Bereichs des Pfads, der durch die Drehung der Schneiden (16) beschrieben wird, erstreckt.
6. Mühle nach Anspruch 5, bei welcher der Rotor (15) eine Rotationsachse aufweist, die
im Wesentlichen parallel zur Rotationsachse der Walzen (2) verläuft.
7. Mühle nach einem oder mehreren der Ansprüche 1 bis 4, bei welcher eine zweite Fördereinrichtung
(24, 25) mit einem Auslass (23) der zweiten Kammer (13) in Verbindung steht, um das
Material, das mittels der Sieboberfläche (14a) getrennt wurde, zu transportieren.
8. Mühle nach Anspruch 7, bei welcher die Fördereinrichtung pneumatisch oder mechanisch
betätigt ist.
9. Mühle nach Anspruch 7, bei welcher eine Lufteinlasseinrichtung mit der zweiten Fördereinrichtung
(24, 25) in Verbindung steht.
10. Mühle nach Anspruch 9, bei welcher die Lufteinlasseinrichtung eine oder mehrere Einlassöffnungen
(8c) umfasst, die stromaufwärts der Walzen vorgesehen ist/sind, wobei die Drehgeschwindigkeit
des Rotors (15) so gewählt wird, dass eine erzwungene Luftzirkulation durch die Walzen
(2) bewirkt und hervorgerufen wird.
11. Mühle nach einem oder mehreren der vorhergehenden Ansprüche, bei welcher die Sieboberfläche
(14a) abnehmbar in der Siebvorrichtung (10) befestigt ist.
1. Appareil à cylindres pour broyer des matières granulaires, en particulier des céréales,
comprenant :
- au moins une paire de cylindres tournant en sens inverse (2) entre lesquels un espace
(3) est défini pour le passage de la matière devant être broyée, et
- un dispositif de filtrage (10) associé aux cylindres (2) pour séparer les produits
du broyage selon les dimensions de la matière broyée, le dispositif de filtrage (10)
comprenant une surface de filtrage (14a) positionnée plus bas que les cylindres (2)
dans une position telle qu'elle puisse être directement alimentée par gravité, par
la chute de la matière broyée au moyen des cylindres (2), caractérisé en ce qu'il comprend :
- des moyens de convoyage (19) interposés entre les cylindres (2) et la surface de
filtrage (14a) pour diriger la matière fournie par gravité, par la chute à partir
des cylindres, le long d'un chemin de chute sur la surface de filtrage (14a) qui est
sensiblement dirigé de manière tangentielle vers ladite surface (14a.
2. Appareil selon la revendication 1, dans lequel le dispositif de filtrage (10) comprend
une première chambre (12) alimentée avec la matière broyée par les cylindres (2) qui
tombe, une seconde chambre (13) séparée de et en communication avec la première chambre
(12) au moyen de ladite surface de filtrage (14a), la seconde chambre (13) étant destinée
à récupérer la matière filtrée au moyen de ladite surface (14a).
3. Appareil selon la revendication 2, dans lequel des moyens de vibration (15, 16) sont
fournis dans la première chambre (12) pour faire vibrer et transporter la matière
rejetée en provenance de la surface de filtrage (14a) vers un orifice d'évacuation
(21) à partir de la première chambre (12).
4. Appareil selon la revendication 3, dans lequel des premiers moyens de convoyage (22)
sont fournis pour soulever la matière broyée rejetée par la surface de filtrage (14a)
et déchargée à travers ledit orifice d'évacuation (21), vers une trémie d'alimentation
(5) des cylindres (2) pour être à nouveau broyée par les cylindres.
5. Appareil selon la revendication 3, dans lequel les moyens de vibration comprennent
un rotor à lames (15) et la surface de filtrage (14a) s'étend au moins partiellement
le long d'une partie du chemin décrit par la rotation des lames (16).
6. Appareil selon la revendication 5, dans lequel le rotor (15) a un axe de rotation
sensiblement parallèle à l'axe de rotation des cylindres (2).
7. Appareil selon l'une quelconque des revendications 1 à 4, dans lequel des seconds
moyens de convoyage (24, 25) sont associés à un orifice d'évacuation (23) de la seconde
chambre (13) pour le transport de la matière séparée par la surface de filtrage (14a).
8. Appareil selon la revendication 7, dans lequel les moyens de convoyage sont pneumatiques
ou mécaniques.
9. Appareil selon la revendication 7, dans lequel des moyens d'entrée d'air sont associés
aux second moyens de convoyage (24, 25).
10. Appareil selon la revendication 9, dans lequel lesdits moyens d'entrée d'air comprennent
une ou plusieurs prises d'air (8c) fournies en amont des cylindres, la vitesse de
rotation du rotor (15) étant sélectionnée de façon à induire et à forcer une circulation
d'air forcée à travers les cylindres (2).
11. Appareil selon l'une quelconque des revendications précédentes, dans lequel la surface
de filtrage (14a) est fixée dans le dispositif de filtrage (10) de manière amovible.