ROTOR, GRINDING MACHINE, AIR EXTRACTION CASING, AND GRINDING ELEMENT FOR A GRINDING MACHINE

Abstract

A rotor (1) for a grinding machine (2) for the foodstuffs and feedstock industry, having an external diameter of between 0.5 and 0.6 m, comprising a plurality of substantially cylindrical, in particular hollow cylindrical, grinding elements (3). One such grinding element (3) has an outer grinding surface (4) substantially in the form of a circular cylinder jacket, and the grinding elements (3) are arranged coaxially above one another and in such a way that a substantially annular air gap (5) is produced between the grinding surfaces (4) of two adjacent grinding elements (3). A ratio between an enveloping surface (H) of the rotor (1) and a total grinding surface of the rotor (1) is greater than 1.05 and less than 1.25.

Claims

1. A rotor for a grinding machine for the foodstuffs and feedstock industry, comprising a plurality of substantially cylindrical grinding elements each having an outer grinding surface substantially in the form of a circular cylinder jacket, wherein the grinding elements are arranged coaxially above one another and in such a way that a substantially annular air gap is produced between the grinding surfaces of two adjacent grinding elements, wherein a ratio between an enveloping surface of the rotor and a total grinding surface of the rotor is greater than 1.05 and less than 1.25, and the rotor has an outer diameter between 0.5 and 0.6 m.

2. The rotor according to claim 1, wherein the rotor has at least one of a total grinding surface between 0.7 and 1.2 m.sup.2 or an enveloping surface between 0.8 and 1.5 m.sup.2.

3. The rotor according to claim 1, wherein the rotor has a height between 0.5 and 0.6 m.

4. The rotor according to claim 1, wherein a ratio between the grinding element height and outer diameter is between ? and 1/12.

5. The rotor according to claim 1, wherein the height of the annular air gap is between 5 and 9 mm.

6. The rotor according to claim 1, wherein a grinding element comprises a main body having an outer surface substantially in the form of a circular cylinder jacket and also comprises a coating applied to the outer surface, and the coating is a diamond coating, preferably a galvanic diamond coating with preferably a mean particle size between 0.3 mm and 0.8 mm.

7. A grinding machine for the foodstuffs and feedstock industry, comprising a rotor according to claim 1, a rotor housing with an inlet and an outlet for the product that is to be ground and for the product that has been ground, respectively, and a drive for driving the rotor, wherein the rotor is directly driven.

8. The grinding machine according to claim 7, wherein a grinding chamber with a chamber wall of the rotor housing that is substantially in a form of a circular cylinder jacket coaxially surrounds the rotor, and a distance between the chamber wall and grinding surface is between 15 and 25 mm.

9. The grinding machine according to claim 7, wherein the chamber wall is provided with a plurality of air passage openings.

10. The grinding machine according to claim 7, wherein the chamber wall is provided with protruding braking strips and backup strips , which extend substantially parallel with or in a manner running coaxially around the rotor axis, and the braking strips are adjustable, such that a protrusion relative to the chamber wall can be adjusted between 4 mm and 10 mm.

11. The grinding machine according to claim 7, wherein the grinding machine also comprises an air extraction device.

12. A grinding element for a grinding machine for the foodstuffs and feedstock industry according to claim 7, wherein a ratio between the grinding element height and outer diameter of the grinding element is between ? and 1/12.

13. An air extraction casing for a grinding machine for the foodstuffs and feedstock industry, having a rotor that can be driven and that is surrounded by a chamber wall provided with air passage openings comprising a lateral surface, which can be arranged around the chamber wall and can be fluidically connected to an air extraction device in order to generate a negative pressure, wherein a radial distance between the lateral surface and at least one of the chamber wall or the rotor axis increases at least in portions in a circumferential direction of the rotor.

14. The air extraction casing according to claim 13, wherein the air extraction casing also comprises a plurality of radial bases, which extend between the chamber wall and the lateral surface.

15. The air extraction casing according to claim 13, wherein the chamber wall extends in a spiralled manner.

Description

[0064] The invention will be better described hereinafter on the basis of a preferred exemplary embodiment in conjunction with the drawing, in which:

[0065] FIG. 1 shows a perspective sectional view of a preferred embodiment of a grinding machine;

[0066] FIG. 2 shows a perspective view of the grinding machine of

[0067] FIG. 1 with opened chamber wall;

[0068] FIG. 3 shows the grinding machine of FIG. 2 in its entirety with closed chamber wall;

[0069] FIG. 4 shows the grinding machine of FIG. 3 without rotor housing;

[0070] FIG. 5 shows a sectional view through stacked grinding elements;

[0071] FIG. 6 shows a radial sectional view through the preferred embodiment of the grinding machine;

[0072] FIG. 7 shows a view of the preferred embodiment of the grinding machine without rotor, with visible annular orifice; and

[0073] FIG. 8 shows a perspective view of a further embodiment of a grinding machine with opened chamber wall.

[0074] FIGS. 1 to 7 show a grinding machine 2 which is equipped with a rotor 1. The rotor 1 is arranged in a grinding chamber 14 of a rotor housing 9 of the grinding machine 2, wherein a rotor axis R is arranged parallel to a gravity vector G.

[0075] The rotor 1 is composed of ten grinding elements 3, which are stacked in such a way that an air gap 5 is formed between two adjacent grinding elements 3.

[0076] Each grinding element 3 consists of a metallic hollow cylindrical main body 6 having an outer surface 7. A galvanic diamond coating 8 has been applied to the outer surface 7.

[0077] The coatings 8 as a whole form the grinding surface 4 of the rotor.

[0078] The rotor 1 is surrounded by a chamber wall 15, which is better visible in FIG. 2, since one chamber half is opened about a hinge 21, as is the case for example when cleaning the grinding machine 2. The air passage openings formed as slots are shown in part in FIG. 2.

[0079] The rotor 1 at its upper end has a conical cover 22, which is used to distribute the product that is to be ground.

[0080] During operation the rotor 1 is driven in a direction of rotation D by an electric motor 12, which is arranged beneath the rotor 1. A drive shaft 13 of the electric motor 12 is connected to a rotor shaft 23 directly and coaxially with the rotor 1. The rotor 1 is mounted only in the region between electric motor 12 and rotor shaft 23. When feeding product through an inlet opening 10, the product can thus be directed towards the apex of the conical cover 22 and can thus be distributed over the entire circumference of the rotor 1.

[0081] The product falls as a result of the force of gravity through the grinding gap S formed between the grinding surface 4 and chamber wall 15, said grinding gap having a gap width of 20 mm. In so doing, the surface of the product is contacted and ground down by the grinding surface 4 of the quickly rotating rotor (1500-1800 revolutions/minute).

[0082] In order to prevent product particles from escaping the grinding surface 4 or in order to increase the residence time in the grinding gap, braking strips and backup strips 17 and 18 are arranged on the chamber wall 15 and deflect the product. The braking strips 17 extend in the axial direction of the rotor 1 and the chamber wall 15, which are arranged concentrically, whereas the backup strips 18, which are visible in FIG. 8, are formed as a circumferential segment and extend in the circumferential direction of the chamber wall 15. The radial distance between grinding surface 4 and braking strip 17 can be adjusted.

[0083] The product then leaves the grinding chamber 14 through an annular outlet 11. An annular orifice 19 is arranged at the outlet 1 and can be seen particularly clearly in FIG. 7 and is movable by means of an actuator 24. The annular orifice 19 can block the outlet 11, such that product is backed up in the grinding gap S. By adjusting an outlet cross-section, the annular orifice 19 can also define a throughput of the grinding machine 2.

[0084] The grinding dust produced during the grinding of the product and which consists of the abraded surface of the product is removed from the product flow via an air extraction device (not shown). In so doing, a negative pressure is generated in the grinding chamber 14 by means of the air extraction device. The chamber wall 15 is formed as a sieve surface and has a plurality of air passage openings 16, which are embodied as slots and which are dimensioned in such a way that they retain the product, but enable extraction of the grinding dust.

[0085] Air flows through inlet openings 27 in the motor region and in the region of the drive shaft 13 on account of the negative pressure prevailing in the grinding chamber 14 and is guided to the hollow interior of the rotor 1. The air gaps 5 of the rotor enable the air to flow through. Here, the created grinding dust is entrained by the airflow and is removed from the grinding gap S through the openings 16 of the chamber wall 15. In order to generate a uniform extraction power over the entire height h of the rotor 1, four ring channels 25 are arranged around the grinding chamber 14. Each ring channel is connected at one end to the intake port 26 of the air extraction device and runs around the grinding chamber 14. Radial bases 29 are formed between the ring channels 25 and extend between the chamber wall 15 and a lateral surface 28 of an air extraction casing 20. Since a wall of the ring channel 25 is formed by the chamber wall 15, the flow of air out from the grinding chamber 14 is thus possible. The other end of the ring channel 25 has small intake openings, which enable a small amount of air to be sucked in from the surrounding environment. Air, however, is sucked in primarily (more than 80% of the intake volume) through the inlet openings 27.

[0086] The lateral surface 28, as can be seen in FIG. 6, does not run concentrically with the rotor 1 or the chamber wall 15, but in a spiralled manner, starting from the small intake openings and in the circumferential direction (equal to the direction of rotation) of the rotor 1. A constant intake capacity is thus generated over the entire circumference of the rotor 1 and counteracts blockages and material accumulations.