WO2009068921A1

WO2009068921A1 - High speed roller mill

Info

Publication number: WO2009068921A1
Application number: PCT/HU2008/000135
Authority: WO
Inventors: András KERTÉSZ
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-11-26
Filing date: 2008-11-25
Publication date: 2009-06-04
Anticipated expiration: 2010-05-26

Abstract

The subject of the patent is a machine used for milling cereals for human and animal purposes. It has driven grinding rolls rotating against each other. According to our solution, there is a driven accelerative rotor (26) equipped with beating surfaces (27) in one side (25) of the grain guiding hopper (17) which will accelerate the grains fed in. The subject of the patent is also a mill equipped with grain accelerator where there are driven accelerating-breaking rolls (30, 31 ) installed in each side of the grain guiding hopper (17). Here the diameter of the reducing rolls (32, 33) is smaller than the diameter of the accelerating-breaking rolls (30, 31 ). Our solutions make it possible to mill at a high speed, drive the rolls of high revolution number directly by an electric motor, regulate closely the drive ratio of the roll pair thereby the grain size of the grits by a frequency changer during operation and manufacture a simple machine at a low cost.

Description

HIGH-SPEED ROLLER MILL

The patent includes a machine serving for milling cereals for human and animal use. Its rolls rotating against each other are driven by a separate electric motor each, without the necessity of expensive geared transmission. The machine is suitable for the coarse and fine milling of cereals with uniform grain composition, low power demand and at a high speed in an economic way.

Through the solution as per the patent, simple mills can be built at a low cost. By selecting the pole number of electric motors between 2 and 8, sufficient variations of roll speed can be adjusted. The peripheral speed and thereby the milling speed can be set versatilely by selecting the roll diameter in accordance with the required grain size.

Owing to the high milling speed, the number of grains treated simultaneously, the pressure acting on the rolls and thereby the load of the whole structure will decrease. The high speed of revolution makes it possible to apply a roll of smaller diameter than applied so far in practice, even in the event of high peripheral speed.

The application of the high milling speed and the direct electric motor drive as per the patent makes it possible to minimize the dimensions of the mill, build low-cost machine and change the grain size in addition to the known method of grinding gap adjustment, through the simple modification of the milling speed and groove matching.

It is known from practice and literature that cereals are milled by roller or sludge mills prior to use.

The power requirement of the roller mills is favourable and the grain composition is uniform; however, these machines are complicated and expensive. The known sludge mills are simple and cheaper but have the disadvantages that the grain composition shows great distribution, the ratio of flour fraction is high, and therefore the power requirement is also higher. Despite their disadvantages, nowadays roller mills are more and more popular on the users' side.

However, these machines mainly solve the rotation of the roll pairs against each other by gearwheels, with one axle driven by the electric motor through a reducer. This driving method is expensive as a result of the high number of elements and small lot production. Furthermore, classic roller-mills are also known from practice and literature. Their descriptions can be found in the Gabonaipari Ke∑ikόnyv (Cereals Industry Manual), volume entitled Technolόgiai gepek es berendezέsek (Technological Machines and Equipment) (Tibor Tomay, Me∑όgazdasάgi Kiadό, 1973), pp. 501 -531.

These machines are well-established, good but complicated constructions and owing to the low grinding speed they have large dimensions. This is why they are not used for general purposes, for example in agriculture.

The mentioned literature states on pp. 515 that the practical milling speed is 2.5-4.5 m/s, while the material arrival speed is only 2.0-2.5 m/s.

It is known from researches that it would be desirable to increase the arrival speed to the grinding speed. According to the literature, it is impossible with the known solutions. It is stated in the manual mentioned above, in volume entitled Aruismeret es technolόgiai folyamatok (Goods knowledge and technological processes), pp. 172. The same literature, pp. 157 mentions 5-10 m/s roll speed applied in USA as the maximum existing, but does not give any other information.

The patent of roll number 152077 and 50 c, B 02 d class number entitled Procedure and equipment for milling hard materials offers a quick milling procedure for hard, stone-like materials but not for relatively soft, leathery agricultural cereals applied in cereal industry and agriculture. This solution applies properly the known theory for increasing the grinding speed for hard materials in the event of roll pairs rotating against each other with the same peripheral speed, but does not provide a solution for milling cereals of quite different characteristics by means of roll pairs rotating against each other with different peripheral speeds. It recommends applying a mechanical accelerative mechanism for decreasing the height of the gravitational hopper, but beyond the setting out of the task it does not describe what mechanical device could ensure it.

In addition, the Hungarian patent of roll number 210-278 entitled "Mill for power saving milling of cereals and similar materials" is also known. Its purpose is to produce grist of uniform grain composition with single-stage milling without overmilling,. with favourable power utilisation and at low investment costs.

This solution has achieved the technological aim but it features the disadvantage of relatively high machine production cost because of the driving from an electric motor through V-belt transmission and the application of large-sized pair of gears for rotating the two rolls against each other. Beyond this, the manufacture of the articulated-ring arch sieve means extra cost as compared to normal roller mills. Neither this patent provides a solution for the acceleration of the material to be milled.

We can state that the known cereal industry and agricultural roller mills feature the common disadvantage that the arrival speed of the material to be milled does not reach the forwarding speed of the material in the milling zone. Therefore the material is drawn in by friction force resulting in lossy heat production. It means low material forwarding that is milling speed between the rolls, which, however, at a given power results in great roll length and thereby high roll pressing force, high structural load and large machine dimensions.

In addition, their common disadvantage is that expensive driving gears are applied for ensuring the low rotational speed and rotation of rolls against each other.

The ambition of our patent is to improve the known roller mills further, create a simple method of driving with high-speed rolls, minimise the machine dimensions with the significant increase of the milling speed and ensure the change of grits grain size without more parts.

The patent is based on the recognition and experimental results that the grinding speed is not restricted to the maximum 9-10 m/s value given in the literature when milling cereals, either, but it can be increased further. Thus it is possible to drive the rolls directly with an electric motor and miss the reducer.

Further it is based on the recognition that the gear drive or chain drive ensuring the rotation of the grinding rolls against each other can also be missed if each of the two rolls are driven by a separate electric motor, with the same motor pole number in the event of the same roll speed, while different motor pole number in the event of different roll speed.

As a result of the high grinding speed, smaller roll length can be applied and the number of grains treated simultaneously will also decrease; as a result the grinding pressure acting on the rolls and the structural load of the whole machine will also be reduced. Thus the dimensions of the machine can be minimized. According to our basic recognition, one solution for it can be that we string the small-sized and small-axle-load roll pair onto the shaft of an electric motor each and thus match them next to each other in a way ensuring adjustable milling.

It is a part of our basic recognition that we can change the peripheral speed conditions of the same machine in several steps by the simple selection of another pole number and thereby we can influence the grain size of the grits as well. According to the known practice and the literature, the tendency of grain size can also be influenced by matching the grooves of the grinding rolls that is by the variations EDGE/EDGE, BACK/BACK, EDGE/BACK or

BACK/EDGE. According to our solution, the simplified drive and the minimized dimensions make it possible to change or invert the rolls even during operation, thus achieving the quick matching of grooves required.

Applying the change of rotational speed and matching of grooves jointly, we have raised opportunities for selecting the grits size and quality. For meeting extra demands, the stepwise changes of speed can be completed with the electronic continuous regulation of one of the electric motors.

As per our basic recognition, we can increase the arrival speed of the material to be ground in one step, if we place a rotor equipped with a beating surface above the grinding gap or in the guiding hopper in such a way that we feed the grains to be ground in a height and/or tilt angle adjustable to the rotating beating surface; the feeding speed vector of the grains at the moment of impact will result with the speed vector of the beating surface in a vector sum speed the direction of which is in the grinding plane and shows towards the grinding, while its amount is almost the same as the grinding speed. The gravitational speed increase of the way run till the grinding will also be added to the vector sum.

The arrival speed can also be ensured by a two-roll accelerator, applying relatively great grinding gap. This two-roll grain accelerator can also be used for breaking greater-sized grain. In the solution as per our recognition, the cumulated arrival speed of the grain is almost the same as the speed of the material flowing through the grinding gap that is the so-called grinding speed, and it is not greater than this.

Through this solution, the material will get into the grinding gap without friction that is heat production, resulting in power saving and advantageously cold grits.

The flat guiding hopper placed in the grinding plane serves for the baffling of the grains possibly spread.

The advantageous effects of the patent are provided by that the high-speed roller mill has at least two driven grinding rolls rotating against each other, adjustable grinding gap, a hopper guiding the grains to be ground and one roll is stationary fixed on the standing structure, while the other roll is fixed in a removable, adjustable way with gap adjuster and compressive mechanism; according to this invention, an accelerative rotor equipped with more than one beating surfaces is built in one side of the guiding hopper, and its grinding rolls are highspeed rolls.

Integrally with those mentioned above, the advantageous effects of the patent are also provided by that the high-speed roller mill has at least two driven grinding rolls rotating against each other, adjustable grinding gap, a hopper guiding the grains to be ground and one roll is stationary fixed on the standing structure, while the other roll is fixed in a removable, adjustable way with gap adjuster and compressive mechanism. According to the basic concept of this invention, driven grain-accelerating-breaking rolls are built in both sides of the guiding hopper rotating against each other. One accelerating-breaking roll is stationary fixed on the standing structure, while the other is fixed in a removable, adjustable way with gap adjuster and compressive mechanism. In addition, the diameter of the grinding rolls is smaller than that of the grain-accelerating-breaking rolls.

The advantageous effects are ensured also by that for intensive grinding motors of different speed and power are assigned to the rolls rotating against each other. Certainly it is not excluded that the two rolls rotate with the same speed.

It also contributes to the advantageous effects of the patent that the grinding rolls and the accelerating-breaking rolls are directly driven by a separate electric motor each. Another driving method is not excluded, either, but more advantages can be achieved by using the electric motors.

The opportunity of continuous grain size regulation during operation as per the invention is ensured by that we connect an electronic continuous speed regulator to the electric motor of the quickly rotating grinding roll, for example a frequency changer. In accordance with our solution, an even simpler and cheaper machine can be produced if the grinding rolls are made without axle and bearing support in a symmetric design. In this case the rolls are strung onto the shaft of the driving electric motor. For this latter application, the advantageous features of our patent solution are obviously certified since we can find motors of the same size even with different speed and power requirement as you can see in the table in Figure 7.

The advantageous effects resulting in the manufacture of a simple, compact machine are also provided by that one roll-motor unit of the roll pair rotating against each other is fixed onto a stationary, closed case-half, while the other roll-motor unit is fixed onto a floating, closed case-half. The case-halves are connected together with a swivel-pin. The dividing lines of the case sides standing oppositely are shifted to the right and to the left from the grinding plane. The advantageous features of the roller mills as per our invention will completely appear if we install a feeding trough equipped with a vibration motor in between the hopper receiving the cereals to be ground and the roller mill. The vibration motor producing the circling movement is placed on the end of the feeding trough opposite to the outlet that is under the manual shut- off of the hopper.

The advantageous effects of the grain accelerator as per the invention are ensured by that a grain guiding plate of adjustable height and/or adjustable tilt angle is connected to the hopper side being opposite to the accelerative rotor. The patent is described in details with examples of design, on the basis of drawings.

The enclosed drawings include the following figures:

Figure 1 direct-drive roller mill with long, bearing supported rolls, motor, in top view

Figure 2 roller mill as per the patent in divided case, with strung rolls, flanged motor, in side view

Figure 3 section a-a taken in Figure 2

Figure 4 the grain accelerator in schematic section, with speed vectors

Figure 5 schematic roll arrangement of the two-roll accelerator-breakers as per the patent

Figure 6 section b-b taken in Figure 2

Figure 7 building dimensions of the three-phase motors

According to the patent, electric driving is possible; the grinding rolls 1 , 2 rotating against each other are built in the high-speed roller mill shown in Figures 1, 4, matching together with grinding gap 5. The guiding hopper 17 is placed above the gap in the line of the grinding plane 17. Separate electric motors 6 and 7 are connected to the grinding rolls 1 and 2, for this design with clutch. The use of another method of driving is not excluded, either. Grinding roll 1 and electric motor 6 as well as grinding roll 2 and electric motor 7 constitute one roll-motor unit each.

One roll-motor unit is stationary fixed on the standing structure 10, while the other is fixed in a removable, adjustable way with gap adjuster 13 and compressive mechanism 14. According to this solution of the patent, as it can be seen in Figure 4, an accelerative rotor 26 equipped with more than one beating surfaces 27 is built in one side of the guiding hopper 25. It cannot be seen in Figure 1 , but it is obvious that the adjustable roll-motor unit is fixed onto the standing structure 10 by means of a slide shoe or swivel pin 12 seen in Figure 4 as well. Small-diameter grinding rolls 32, 31 rotating against each other are built with grinding gap 5 in the roller mill possible according to the invention. They are equipped with the electric- driven two-roll grain accelerator shown in Figure 1 and 8. The guiding hopper 34 is located above the grinding gap, in the line of the grinding plane 16. Separate electric motors 6 and 7 are connected to the small-diameter grinding rolls 32, 33 without reducer, with known solutions. One roll-motor unit is stationary fixed onto the standing structure 10, while the other is fixed in a removable, adjustable way with gap adjuster 13 and compressive mechanism 14.

According to this solution of the patent, one great-size accelerator-breaking roll each is installed in both sides of the guiding hopper 34, which are connected together with an accelerating-breaking gap. These also have separate electric motor 6, 7 without reducers. Other driving methods are not excluded from the solution as per the patent. One accelerating-breaking roll-motor unit is stationary fixed onto the standing structure 10, while the other is fixed in a removable, adjustable way with gap adjuster 13 and compressive mechanism 14.

The diameters of all rolls mentioned in our description are smaller or not greater than those applied nowadays in practice, and it relates to the accelerating rolls, too. For the small- diameter grinding roll, the smaller diameter is meant as compared to the diameter of the accelerating roll.

In any other design form of the two solutions described, we assign electric motors of different speed and different power to the rolls of each pair of rolls, but the axle dimensions, bearing of the motors selected in accordance with table of Figure 7 are of the same dimensions and meet the load requirements.

We can connect an electronic continuous 50-speed regulator, for example a frequency changer to the engines of any mill driven by an electric motor. However, in the event of a roll pair of different speed, these are connected only to the high-speed engines 6, 30, 32 for which the speed ratio of the roll pair can be changed by reducing the highest speed. Rolls 1, 2, 30, 31, 32, 33 of any roller mill as per the patent equipped with electric motor can be made in symmetrical, reversible design without axle and bearing support, and strung onto the shaft of the driving electric motor. Thus high extent of machine price reduction can be achieved, while gaining operating advantages.

For some design forms, one roll-motor unit 1 , 6 is fixed onto the stationary closed case-half 18, while the other roll-motor unit 2, 7 is fixed onto the floating, closed case-half 19. These case-halves 18, 19 are connected together with the swivel pin 12 ensuring their turning. Grinding gap 5 is ensured with gap adjuster 13 and compressive mechanism 14, since these are fixed onto the case-halves 18, 19.

Any design form as per the patent can be equipped with feeding trough 40 with vibration motor 41. Here the vibration motor 40 is placed at the end 46 opposite to the outlet 45 in order that the cereal can be baffled and flow properly. In the event of connecting a cereal feed chute, the top edges of feeding trough 43 have flexible connection elements 44. For certain design forms, grain guiding plate 29 of adjustable height and/or adjustable tilt angle is placed onto the side 28 of guiding hopper 17 opposite to the accelerative rotor 26. This guiding plate can be placed in the continuation of the outlet 45 or oppositely to it.

Let us continue the description of the patent by showing the operation of the design example no. 2.

Pour the cereal to be ground or other bulk grained materials into hopper 39 and care that hopper contains material to be ground permanently. Start the electric motor 6 and 7 driving the grinding rolls 1 and 2 rotating against each other, the accelerative rotor driving the accelerating electric motor 47 and the vibration motor 41 moving the feeding trough 40. Set the layer regulator 49 and the slope of the feeding trough to minimum value. Open the manual shut-off 48 installed in the bottom of the hopper and then the grinding will start with minimum power. The part of the feeding trough above the vibration motor moves along a vertical circle and spreads the cereal. This movement will pass into straight-line progressive motion at the outlet and the fed spread cereal grains fall through the surface of the scale separator equipped with a permanent magnet onto the material guiding plate 29 of adjustable height and/or tilt angle. It will slide the grains between the beating surfaces 27 of the accelerative rotor 26 rotating oppositely. The direction of speed of the grains can be adjusted by means of the inlet plate 29. The beating surface 27 of accelerative rotor 26 accelerates one row of grains by beating them; they will forward along the grinding plane 16 towards the grinding gap 5, while their speed will grow further to the grinding speed or a speed approximating it as a result of the gravitational acceleration. Then they will get into the grinding gap without heat production of friction or drawing in or with small heat production. Here the grinding takes place between the grooved roll bodies 3, 4 of different peripheral speed. Cold grits will leave the grinding gap. If the speeds of the rolls 1 , 2 are the same, then roll bodies 3, 4 will only snap, flatten the grains, without shear stress.

The amount of grain size can be influenced in several ways. Amount of grinding gap 5 can be regulated by means of gap adjuster 13, for example by a screw or any other adjuster. During the adjustment the floating closed case-half 19 is moved around the swivel pin 12 against the stationary case-half 18. The electric motor 7 built on it as well as the two symmetrical grinding rolls strung onto the motor shaft will move together with it. Following the adjustment of the grinding gap, set the grinding pressure by means of the spring compressive mechanism 14. The compressive mechanism will allow the rolls to move off each other only in the event hard objects for example stone, iron pieces get into the gap. Following the adjustments, grow the amount to be ground by the layer regulator 49 until the load of electric motor 6, 7 permits it.

On a pilot machine, electric motor 7 moved with 750 1/min and 1.5 kW power while electric motor 6 moved with 3000 1/min synchronous speed and 4.0 kW.

As it can be seen, the motor power depends on the speed ratio of the roll pair. The roll diameter applied for grinding wheat, barley, oat, with the high-speed roll's peripheral speed being 20 m/sec. The effective passing speed of the material is determined jointly by the peripheral speeds of the two rolls.

We suppose to apply a feeding device for the operation of the roller mill equipped with two- roll grain accelerator shown in Figure 5, too.

The accelerating/breaking roll pair 30, 31 will accelerate the cereal to be ground fed into the top section of the guiding hopper 16. The speed reached here is not greater than the fine grinding speed between small-diameter rolls 32, 33, even with the speed increase reached in the lower part section of the guiding hopper 34 added. The necessary arrival speed can be adjusted by changing the speed of the accelerating rolls 30 and 31. It can be achieved and finely regulated during operation through the regulation of the higher-speed roll 30 by means of a 50-frequnecy changer.

On the high-speed roller mills as per our patent, in addition to the grinding gap 5 and grinding pressure the peripheral speed of grinding rolls 1 , 2, the peripheral speed ratio of rolls 1, 2 rotating against each other can also be adjusted through the selection of the pole number of driving electric motors 6, 7 for the actual task as well as the formation of grooves in the surface of roll bodies 3, 4. On an actual machine, the rolls can be turned around, or changed with each other, which means the opportunity of selecting the groove matching to the task. The pole numbers and synchronous speeds of the electric motors applied to various grinding tasks are as follows: 2 poles - 3000 1/min, 4 poles - 1500 1/min, 6 poles - 1000 1/min and 8 poles - 750 1/min. Opportunities of groove matching are: edge-to-edge, back-to-back, edge- to-back, back-to-edge, in the way already known.

Owing to the solutions as per the basic recognition, there are more opportunities for adjustment and selection as compared to the roller mills known and applied in practice. The synchronous speed of the quick roll can be decreased and the speed ratio of the roll pair changed continuously by a frequency changer. Thus the grain size can be continuously regulated through an electronic way.

The adjustments and operational tasks as well as the necessary skills are just the same as for the already known roller mills.

As it can be seen, the patent roller mill without gears has very simple structure, minimized dimensions, is producible at low cost, has favourable power consumption and is suitable for preparing great number of kinds of grits. It preserves the advantages of the known and well- established roller mills, but exceeds its disadvantageous features.

It can be applied as a single machine or placed in a production line for preparing traditional edible flour and agricultural fodder grits, both for tasks of low and high power.

Claims

1. High-speed mill for grinding cereals which has at least two driven grinding rolls (I₅ 2) rotating against each other, adjustable grinding gap (5), guiding hopper (17) and one grinding roll (1) is stationary fixed onto the standing structure (10) while the other grinding roll (2) is fixed in a removable and adjustable way with the gap adjuster (13), compressive mechanism (14), characterised with that there is a driven accelerative rotor (26) equipped with more than one beating surfaces (27) and built in one side of the guiding hopper (17) and the grinding rolls (1, 2) are high-speed rolls.

2. High-speed mill for grinding cereals which has at least two driven reducing rolls (32, 33) rotating against each other, adjustable grinding gap (5), guiding hopper (34) and one reducing roll (32) is stationary fixed onto the standing structure (10) while the other reducing roll (33) is fixed in a removable and adjustable way with the gap adjuster (13), compressive mechanism (14), characterised with that there are two driven accelerating-breaking rolls (30, 31) rotating oppositely, matched with accelerating-breaking gap (51) and one of the accelerating-breaking rolls (30) is stationary fixed onto the standing structure (10), while the other accelerating- breaking roll (31) is fixed in a removable and adjustable way with the gap adjuster (13), compressive mechanism (14), and the diameter of the reducing rolls (32, 33) is smaller than the diameter of the accelerating-breaking rolls (30, 31).

3. Any of the mills as per Point 1 or 2, characterised with that the grinding rolls (1, 2) and the accelerating-breaking rolls (32, 33) are driven directly by separate electric motors (6, 7) each.

4. Any of the mills as per Point 3, characterised with that electric motors (6, 7) of different speeds and different powers are assigned to the rolls (I₅ 2) (30, 31) (32, 33) rotating oppositely to each other.

5. Mill as per any of Points 3-4, characterised with that the electric motor (6) driving the quickly rotating grinding rolls (I₅ 30, 32) has electronic, continuous 50-speed regulator.

6. Mill as per any of Points 3-5, characterised with that its grinding rolls (1, 2, 30, 31, 32, 33) are of symmetrical and reversible design without axle and bearing support and are strung onto the shaft of the driving electric motor (6, 7).

7. Mill as per any of Points 3-6, characterised with that one roll-motor unit of the roll pair is fixed onto a closed case-half (18), while the other roll-motor unit is fixed onto a closed floating case-half (19); these case-halves are connected with swivel pin (12) and the dividing line (22) of the opposite sides (30, 31) is shifted from the grinding plane (16).

8. Mill as per any of Points 1-7, characterised with that hopper and feeding trough (40) equipped with vibration motor (41) are built in, where the vibration motor (41) is placed at the end of the feeding trough (46) opposite to the outlet (45) and the top edges (43) of the feeding trough have flexible connection elements (44).

9. Mill as per any of Points 1 and 3-8, characterised with that an adjustable grain guiding plate (29) is connected to the hopper side (28) opposite to the accelerative rotor (26).