WO2006117067A1

WO2006117067A1 - An improved roll mill for cereals

Info

Publication number: WO2006117067A1
Application number: PCT/EP2006/003505
Authority: WO
Inventors: Silvano Barbieri
Original assignee: Agrex S.P.A.
Priority date: 2005-05-02
Filing date: 2006-04-18
Publication date: 2006-11-09
Also published as: ITPD20050122A1

Abstract

A roll mill for cereals is described, comprising at least one pair of rolls (4,5) capable of being driven in relative contra-rotation about their respective principal axes of rotation (Xl, X2), the rolls defining an opening (6) for the passage of the material to be milled, fed through a corresponding fall zone (C) for the material between the rolls, one (4) of the rolls being fixed, held by first supports (4a) fitted to respective shoulders (2) of the roll mill, and the other roll (5) being movable, mounted on respective second supports (5a) articulated on the shoulders (2) at a respective articulation axis (X3), wherein the articulation axis is disposed on the opposite side from the axis of rotation (Xl) of the fixed roll (4) with respect to the axis of rotation (X2) of the movable roll (5). The articulation axis (X3) is also positioned, with respect to the plane (P) containing the axes of rotation (Xl,X2),of the rolls (4,5), on the opposite side from the fall zone (C) for the material to be milled, the positioning being such that the movable roll (5) is caused to pivot, by the effect of its own weight, about the articulation axis (X3), to come closer to the fixed roll (4).

Description

An improved roll mill for cereals Technical field

The present invention concerns a roll mill for cereals according to the preamble of the main claim. Technical background

In the field of milling technique in which the present invention is placed, roll mills are known that are provided with one or more pairs of contra-rotating rolls maintained at a predetermined, adjustable distance, such as to define between their respective outer surfaces an opening for the passage of the material to be milled. In the applications of roll mills with horizontal rolls, at which the invention is particularly, but not exclusively, directed, provision is made for such rolls to be driven in rotation at different speeds.

In the known roll mills, provision is also made for one of the two rolls to be fixed, held by supports fitted to the shoulders of the machine while the other roll is movable, that is, mounted on supports articulated, at one end thereof, at said shoulders by systems capable of allowing adjustment of the independent horizontal displacement of the two supports of the movable roll, which displacement is necessary for the operations of adjustment aimed in particular at compensating the inevitable wear of the rolls or for restoring the parallelism between the milling surfaces thereof and in each case for varying or bringing back to the desired value the characteristics of the milled product. Provision is also made for each support of the movable roll to be connected at the other opposite end to a respective operating device arranged for the adjustment of the mutual positioning of the milling rolls and also provided with springing means yielding resiliency in the direction of distancing of the movable roll from the fixed roll. These springing means serve to prevent damage to the rolls if at any time, in normal operation, a foreign body should be included with the material to be milled, inasmuch as by means of their resilient yielding they allow instantaneous distancing of the movable roll from the fixed roll for the passage of the foreign body. Disclosure of the invention

In this specific technical field, it is a principal aim of the present invention to improve as a whole the efficiency of the roll mill, in particular with regard to the contribution to the milling provided by the movable roll and to its interaction with the fixed roll in the milling zone.

Another aim is that of improving the degree and quality of milling obtainable, and also the extraction yield of the milled product, at the same time optimising the output of the roll mill for each type of operation and treatment of the material to be milled, whether this entails simple crushing of the material or milling or refining of same, each of such treatments being distinguished by corresponding and distinct degrees of fineness and uniformity of milling. These and other aims which will become clear hereinafter are achieved, according to the present invention, by means of a roll mill for cereals having the characteristics mentioned in the attached claims. Brief description of the drawings

The characteristics and advantages of the invention will become clearer from the following detailed description of a preferred exemplary embodiment thereof, illustrated by way of non-limiting example with reference to the appended drawings, in which:

Figure 1 is a perspective view of a roll mill according to the present invention, - Figure 2 is a view in side elevation of the roll mill of Figure 1,

Figure 3 is a diagrammatic partial side view of the roll mill of the preceding figures, - Figures 4, 5 and 6 are diagrammatic views, in partial section, of respective details of the roll mill of figures 1 and 2. Preferred embodiments of the invention

With reference to the figures mentioned, the reference 1 indicates as a whole a roll mill for cereals, produced according to the present invention and comprising a bearing structure formed by two opposed shoulders 2 rigidly connected to each other by a base 3 and by respective cross- members.

The roll mill 1 comprises a pair of contra-rotating rolls, indicated by 4 and 5, having respective main axes of rotation Xl, X2 parallel to each other. Between the rolls 4, 5 is defined an opening 6, of adjustable cross- section, for the passage of the cereal to be milled. The roll mill 1 has a typical configuration with horizontal rolls, in which the cereal to be milled is fed in by means of a feeder device, not shown in detail, positioned above the rolls.

In the following, the terms "bottom", "top", "horizontal" and

"vertical" will therefore refer to this specific configuration with horizontal rolls, in which the material to be milled is fed by gravity in a substantially vertical direction and will be understood to be correlated with such spatial arrangement. In particular, the gravity fall zone of the material to be milled, indicated by the arrow C in Figure 3, is located above the opening 6 between the rolls. Mounted in a facing position, on each shoulder 2, there are supports

4a, 5a for the two respective milling rolls 4, 5. In particular, the roll 4 is otherwise defined as the "fixed roll", inasmuch as it is rotatably held by the supports 4a rigidly connected to the shoulders 2, without any possibility of relative movement, while the roll 5 is otherwise indicated as the "movable roll" inasmuch as the supports 5a on which it is rotatably mounted are articulated on the corresponding shoulder 2 at an articulation axis X3, directed parallel to the axes of rotation of the rolls.

With particular reference to Figure 3, the articulation axis X3 is conveniently disposed on the opposite side from the axis of rotation Xl of the fixed roll with respect to the axis of rotation X2 of the movable roll, this latter therefore remaining interposed between the axes Xl and X3. Furthermore, the articulation axis X3 is positioned, with respect to the plane containing the axes of rotation Xl and X2, indicated by P in the figure, on the opposite side from the fall zone C of the material, therefore being disposed below the plane P in the configuration of Figure 3. This positioning of the articulation axis X3 means that the movable roll 5 is caused to move, under the effect of its own weight, with the permitted pivoting movement about the axis X3, in the direction of moving closer to the fixed roll 4. With respect to that configuration, provision may further be made for the plane P containing the axes Xl, X2 to be inclined with respect to a substantially horizontal plane, indicated by Q in Figure 3, and which extends perpendicularly to the direction of vertical fall by gravity of the material to be milled. This inclination, preferably slight, is selected such that the axis of rotation X2 of the movable roll is positioned on the opposite side from the articulation axis X3, with respect to said horizontal plane Q, as is clear from the aforesaid drawing.

With the spatial arrangement of the articulation axis X3 with respect to the rolls that has just been described, the result obtained is that, in operation, the movable roll, driven in contra-rotation to the fixed roll, tends to "lean" on the outer surface of the fixed roll owing to the effect of the weight of the roll itself acting through the lever arm between the axes X2 and X3. This therefore favours the tendency to the aforesaid leaning movement of the movable roll 5 against the fixed roll 4 in which, in particular, the movable roll is caused to move in a trajectory interfering with the fixed roll. With this relative positioning, an improved milling effect has been found in the region of the opening 6 between the rolls, in particular an improved effect of wedging of the material between the two contra-rotating rolls. This improvement is principally due to the pressing action and tangential urging generated by the movable roll in the relative milling movement with the fixed roll, which improvement arises from a combination of effects linked in part to the difference between the rotation speeds imparted to the rolls and in part linked to the relative positioning of the rolls which is described above. Tests conducted by the Applicant have confirmed this improved milling efficiency and quality of the milled product that are obtained by the aforesaid relative positioning of the rolls.

Each support 5a of the movable roll 5 has a substantially elongate configuration, in the sense that in addition to the necessary cylindrical cavity 7 which accommodates a bearing of the movable roll 5, it is extended in a bottom appendage 8 and in a top appendage 9. The bottom appendage 8 is provided at the free end 8a with a smaller cylindrical cavity 8b in which is accommodated a complementary cylindrical member 10, mounted eccentrically on, and secured in rotation with, a pin formation 11. The pin formations 11 constitute opposite ends of a drive shaft 11a rotatably supported between the shoulders 2 and which is further firmly connected to a gear lib of a rack transmission, shown diagrammatically, by means of the driving in rotation of which each respective cylindrical member 10 is rotated eccentrically about the axis of rotation X3. Owing to that eccentricity, to the rotation of the cylindrical member 10 there also corresponds a translation thereof, and therefore a translation of the bottom end of the support 5a. By acting suitably on the drive means it is therefore possible to effect the desired adjustment in a precise manner. The top appendage 9 of each support 5a is pierced by a cylindrical cavity 12 for the passage of a tie-rod 13 for controlling the movement of attack of the movable roll. The tie-rod has a first part 13a slidingly received in the cavity 12 and an axially extended second part 13b, of larger diameter, with definition of a shoulder region capable of locating the top appendage 9.

Fitted to the end, remote from the roll, of each tie-rod 13, is a respective spring-holding cap 14 constituting a seating and locator for one end of a helical spring 15, the opposite end of which is located by the actual appendage 9 of the support. Each spring 15 is biased by means of an adjusting nut 13c screwed to the threaded free end of the tie-rod 13, and can yield resiliently in the direction of distancing of the movable roll from the fixed roll. The opposite end of the tie-rod 13 is connected in an articulated manner to a first pin formation 16 having a threaded end portion 16a. A second pin formation 17 is disposed in axial extension of the first formation and in turn comprises a respective threaded end portion 17a. The portions 16a and 17a are engaged by screwing into the nut screw of a common sleeve 18, having a polygonal outer profile for the engagement of a spanner. By means of rotation of the sleeve, the relative axial distance between the pin formations 16, 17 can be adjusted. On the opposite side from the portion 17a, the pin formation 17 is configured as a cylindrical ring 17b capable of receiving rotatably, and with a preselected eccentricity, a pin 19 rotatably supported on the corresponding shoulder 2 via a bearing-type support 20. The pin 19 is further secured in rotation to the hollow output shaft 21a of a reduction gear 21, preferably with orthogonal axes, the input shaft of which is driven in rotation by means of an operating wheel 22. Through the rotation of the pin 19, by means of the reduction gear with wheel 21, by the effect of the aforesaid eccentricity, the assembly formed by the tie-rod 13 and the pin formations 16, 17 is translated axially along the axis of the tie-rod and consequently each support 5 is pivoted about the corresponding axis X3, in order to permit suitable adjustment of the amplitude of the opening 6 between the outer surfaces of the rolls. By means of the aforesaid device, therefore, the adjusting operations are carried out that are necessary for the take-up of any play and principally for the adjustment of the passage section of the opening 6 between the outer surfaces of the rolls 4, 5. Moreover, if during normal operation a foreign body, such as a piece of metal, should accidentally fall between the two rolls 4, 5 together with the cereal to be milled, any possible damage to the rolls is prevented by the resilient yielding of the springs 15 which permit the instantaneous distancing of the movable roll 5 from the fixed roll 4 for the passage of the foreign body. For the transmission of the rotational motion to the rolls 4 and 5, a first drive transmission shaft 25 is provided, rotatably supported between the shoulders 2 and having an axis of rotation, indicated by X4, parallel to the axes of the rolls Xl, X2.

At the opposite axial ends of the shaft 25, protruding at the respective opposed shoulders 2, respective pulleys 26 are mounted, capable of transmitting the rotational motion to the rolls at each of the two axial ends of same. Two separate belt drives are therefore provided, capable of transmitting the motion from the shaft 25 to the rolls 4, 5 in each end of same, but only one of such drives will be described in detail hereinafter, the other being arranged in a mirror image at the opposite lateral end of the roll mill. Each drive provides a respective drive belt 27 wound on the pulley 26 and on respective pulleys 28 and 29 keyed onto the ends of shafts 28a, 29a rigidly connected to the corresponding rolls 4, 5. The reference 31 indicates a further pulley of a tensioning device for the belt drive. As is clear in particular from Figure 2, the axis X2 of the movable roll is interposed between the axis Xl of the fixed roll and the axis X4 of the shaft 25. With this arrangement the winding of the belt, required for imparting a relative contra-rotatory motion to the rolls, is selected such that the belt 27 is engaged on the pulley 29 (preferably having a toothed profile) associated with the movable roll through an arc D which extends below the plane P containing the axes of rotation Xl and X2. In this way the tensions on the belt 27 that are acting at the ends of the arc D are oriented such as to have a predominant component directed vertically upwards in opposition to the action of the weight of the movable roll itself. From this is advantageously derived a kind of resilient holding and support of the movable roll, due to the intrinsic resilience of the sections of belt 27 developed at the ends of the arc D on the pulley 29. Moreover, owing to the provision of a respective belt drive in each of the axial ends of the rolls, further advantages are obtained, including an improved and more balanced transmission of the power which is reflected in a greater uniformity of milling over the entire front of the rolls, and also a greater overall output of the drive. Last but not least is the advantage of distributing in a balanced manner all the stresses induced by the tensioning of the belt drives at both the opposed axial ends of the rolls, obtaining greater precision in the adjustment of the amplitude of the opening 6, over the entire front of the milling zone, with a consequent improvement in the uniformity, homogeneity and yield of the milled product.

The invention thus achieves the aims proposed, providing the advantages listed above with respect to the known solutions.

Claims

1. A roll mill for cereals comprising at least one pair of rolls (4,5) capable of being driven in relative contra-rotation about their respective principal axes of rotation (X1,X2), the rolls defining an opening (6) for the passage of the material to be milled, fed through a corresponding fall zone (C) for the material between the rolls, one (4) of said rolls being fixed, held by first supports (4a) fitted to respective shoulders (2) of the roll mill, and the other roll (5) being movable, mounted on respective second supports (5a) articulated on said shoulders (2) at a respective articulation axis (X3), characterized in that said articulation axis (X3) is disposed on the opposite side from the axis of rotation (Xl) of the fixed roll (4) with respect to the axis of rotation (X2) of the movable roll (5), and in that said articulation axis (X3) is positioned, with respect to the plane (P) containing the axes of rotation (X1,X2) of the rolls (4,5), on the opposite side from said fall zone (C) for the material to be milled, the positioning being such that the movable roll (5) is caused to pivot, by the effect of its own weight, about said articulation axis (X3), to come closer to the fixed roll (4).

2. A roll mill according to claim 1, configured with substantially horizontal rolls (4,5), in which, with respect to a direction of fall by gravity of the material to be milled on the rolls, said fall zone (C) of the material is positioned above the plane (P) containing the axes of rotation (X1,X2) of said rolls (4,5) and said articulation axis (X3) is positioned below said plane

(P).

3. A roll mill according to claim 2, wherein the plane containing the axes of rotation (X1,X2) of the rolls (4,5) is further inclined with respect to a plane (Q) that is substantially horizontal and extends perpendicularly to the vertical direction of fall by gravity of the material on the rolls, the inclination being selected such that the axis of rotation (X2) of the movable roll (5) is positioned on the opposite side from said articulation axis (X3), with respect to said horizontal plane (Q).

4. A roll mill according to one or more of the preceding claims, wherein each support (5a) of the movable roll (5) is articulated at a first end on a cylindrical body (10) eccentrically mounted on a connecting pin (11) rotatably supported on the corresponding shoulder (2) and rigidly connected to a control member, on actuation of which, to a rotation of the cylindrical body (10) there corresponds a translation of the corresponding support (5a) of the movable roll (5) away from and towards the fixed roll (4).

5. A roll mill according to claim 4, wherein each support (5a) of the movable roll (5) is connected at the other second end to a device for controlling and adjusting the mutual position of the rolls (4,5), with the interposition of springing means (15) resiliently yielding in the direction of distancing of the movable roll (5) from the fixed roll (4).

6. A roll mill according to claim 4 and claim 5, wherein each support (5a) comprises a central cylindrical cavity (7) for the rotatable support of the roll (5), and also a first and a second appendage (8,9) extending from said cavity (7) respectively as far as said first and second ends.

7. A roll mill according to one or more of the preceding claims, comprising a drive transmission shaft (25) with axis (X4) parallel to the axes (Xl, X2) of the rolls and at least one belt drive (27) provided at one of said shoulders (2), said belt (27) being wound on respective pulleys (26,28,29) respectively mounted at the end of said drive shaft (27) and at the ends of shafts (28a, 29a) rigidly connected to the rolls (4,5), the axis (X2) of the movable roll (5) being interposed between the axis (Xl) of the fixed roll (4) and the axis (X4) of said drive shaft (25), said belt (27) being engaged on the pulley (29) associated with the movable roll (5) through an arc (D) extending below the plane (P) containing the axes (Xl, X2) of said rolls.

8. A roll mill according to claim 7, wherein respective belt drives

(27) are provided in each of the shoulders (2), each of said pair of belts (27) being wound between respective sets of pulleys associated with the corresponding axial ends of the transmission shaft (25) and of the shafts (28a, 29a) associated with the rolls (4,5) associated with each of said shoulders (2).