RU2426594C1 - Roll-type particles grinder - Google Patents

Abstract

FIELD: process engineering. ^ SUBSTANCE: invention relates to loose material grinders. Proposed grinder comprises, in fact, horizontal crushing table and set of tolls revolving around vertical shaft. Said set of rolls comprises line of rolls revolving about relevant roll shafts hinged with vertical shaft 5. Said hinge comprises bearing housing and journal Said hinge allows arc-like displacement of roll up and down in plane crossing roll shaft axis. Said set of rolls operates interacting with crushing table. Joint bearing housing diameter exceeds that of journal by at least one percent. ^ EFFECT: higher efficiency and reliability. ^ 5 cl, 3 dwg

Description

FIELD OF THE INVENTION

The present invention relates to a roller mill for grinding granular material, for example cement raw materials, cement clinker and similar materials. The roll grinder comprises a substantially horizontal crushing table and a set of rolls that can rotate around a vertical shaft. The specified set of rolls includes a series of rolls rotating around individual roll shafts connected to a vertical shaft by means of a swivel joint, which includes a bearing housing with a bearing pin included in it and allows free arcuate movement of the roll with up and down displacement in a plane passing through the axis of the roll shaft moreover, the specified set of rolls is configured to work in conjunction with a crushing table.

State of the art

Roller shredders of the above type are well known. In known roller grinders, the swivel joint connecting the roller shaft to the vertical shaft typically includes a plain plain bearing that can be lubricated with a suitable lubricant. This swivel joint is designed so that the rolls can independently follow the changes in height that occur in the layer of material located on the crushing table during the operation of the grinder. The direction of action and the magnitude of the force perceived by this articulated joint are generally constant relative to the bearing journal, the angular displacement of which is caused by changes in the thickness of the material layer and is usually in the range of ± 0.5 to 5 degrees. The frequency of the angular displacements of the bearing journal is usually in the range from 0.5 to 1 Hz. When this known roller mill is used to grind bulk material, such as cement raw materials, cement clinker and similar materials, the swivel joint experiences relatively high pressure, and as a result, the friction between the parts of the swivel joint leads to an increase in harmful heat generation, which cannot be simply reduced by applying lubricant since one-sided permanent pressure and very small angular back-and-forth angles of the bearing journal can prevent the lubricant from being drawn into the zones loading. Other types of bearings available on the market include hydrodynamic lubricated plain bearings, which cannot be used since there is no continuous rotation of the bearing journal and, therefore, a hydrodynamic lubricant film is not formed. From a technical point of view, the ideal solution is a hydrostatic radial bearing, which provides a level of full contact both during static operation and during rotation, but this bearing is too complex, sensitive and expensive, and the roller bearing is not suitable due to the small angular displacements of the bearing journal prevent the lubricant from being drawn into the loading zone. Thus, we have to conclude that none of the traditional types of bearings available on the market have the characteristics necessary for the use of these bearings under the described loading conditions, which would not have significant drawbacks.

Disclosure of invention

An object of the present invention is to provide a roller shredder with which the above-described disadvantages are completely or substantially eliminated.

To solve this problem, a roll shredder of the indicated type is proposed, characterized in that the swivel bearing housing has a diameter exceeding the diameter of the bearing journal included in it by at least 1 percent.

This achieves a significant reduction in friction between the pin and the housing of the swivel bearing and, consequently, a decrease in heat generation in the bearing and its wear rate, in comparison with the bearings used so far. This is because the bearing journal in the bearing housing primarily rotates - in combination with slight angular displacements. In addition, such a swivel joint can work without lubrication and without protection by seals from material crushed in a roller grinder.

In principle, the ratio of the diameters of the trunnion and the bearing housing should be chosen exactly so that small high-frequency angular displacements corresponding to the general changes in the material layer on the crushing table are perceived by the bearing during its rotation and do not cause an excessively high surface pressure, which increases stepwise with increasing ratio diameters. Therefore, according to the present invention, it is preferable that the diameter of the bearing housing exceeds the diameter of the bearing journal included in it by 1 to 25 percent, preferably from 5 to 20 percent.

In the manufacture of the bearing journal and the bearing housing, the same material can be used, for example steel. From the point of view of strength characteristics and economy, this is a clear advantage, which also makes it possible to achieve the most favorable friction conditions in the articulated joint according to the invention.

A brief description of the graphic materials

Below the present invention is described in more detail with reference to the schematic drawings of the accompanying figures, which represent:

figure 1 schematically shows a roller shredder according to the present invention, figure 2 shows a detail of the swivel according to the invention, and figure 3 is a detail of the operation of the swivel in operation.

The implementation of the invention

Figure 1 shows a sectional view of a roll mill 1, including a horizontal crushing table 3 and a set of rolls 4 working in cooperation with it, these rolls being connected to a vertical shaft 5 and rotating around it. The rollers 4 rotate around individual horizontal roll shafts 6 connected to the vertical shaft 5 by means of a swivel joint 7, which allows the rolls 4, rotating around the shaft, to freely move up and down in a plane passing through the axis 12 of the roll shaft. The plane in which the roll moves does not necessarily pass through the axis of the vertical shaft. To obtain a small slip, or shear effect, in the crushing zone, the roll sometimes — or rather often — rises slightly obliquely, which means that its axis does not always intersect with the axis of the vertical shaft.

The center of rotation of the joint 7 may be located in the same horizontal plane as the axis 12 of the roll shaft. However, in the depicted embodiment, the center of rotation of the hinge joint 7, when viewed in a vertical plane, is located under a horizontal plane passing through the center of mass 8 of the roll 4, the roll shaft 6 and the connected part of the hinge 7b and shown in dash-dot line coinciding, for clarity image, with the axis 12 of the roll shaft. This arrangement causes a centrifugal force acting during the operation of the roll grinder on the roll 4, roll shaft 6 and the connected part of the hinge 7b, creating a moment of rotation around the hinge 7 and, therefore, a downward force contributing to the grinding pressure of the roll 4 on the crushing table 3.

As can be seen from figure 2, the hinge 7 includes a bearing housing 14 with a bearing pin 15 included in it. According to the present invention, the bearing housing 14 has a diameter that is greater than the diameter of the bearing journal 15 by at least 1 percent, thereby achieving a significant reduction in friction between the journal 15 and the swivel bearing housing 14 and, consequently, a reduction in heat generation in the bearing and speed its wear, in comparison with the bearings of the types used so far, provided that the bearing pin 15 in the bearing housing 14 primarily rotates - in combination with slight angular displacements.

In order for small high-frequency angular displacements corresponding to general changes in the material layer on the crushing table to be optimally perceived by the bearing during its rotation and not cause excessive surface pressure, the bearing housing 14 must have a diameter exceeding the diameter of the journal 15 of the bearing by a value of 1 up to 25 percent, preferably from 5 to 20 percent.

As can be seen from figure 3, the contact point of the housing 14 and the journal 15 of the bearing moves from point A to point B when the center C _{0 of the} journal 15 of the bearing rotates clockwise to point C ₁ , which occurs when the roll 4 rolls through the elevation point of the material layer on the crushing table 3.

In the neutral position defined by points A and C ₀ , the reaction force F is directed along the normal vector to the tangent plane at point A. When the bearing journal 15 moves to point C ₁ , the reaction force F is composed of two components, namely: normal force F _N and friction forces F _t . The maximum value of the friction force is F _t = F _N × µ _s , where µ _s is the static coefficient of friction, the approximate value of which for “steel by steel” is assumed to be 0.3. If the specified value of F _{t is} exceeded, the axle 15 of the bearing slides back to point A, occupying a new neutral position for the movement of the roll, corresponding to the increased layer of material on the crushing table 3.

Claims (5)

1. Roll mill (1) for grinding bulk material, such as cement raw materials, cement clinker and similar materials, comprising a substantially horizontal crushing table (3) and a set of rolls rotating around a vertical shaft (5), said roll set comprising a number of rolls (4) rotating around respective roll shafts (6) connected to the vertical shaft (5) by means of a pivot joint (7), which includes a bearing housing (14) with a bearing pin (15) included therein, wherein said hinge The th connection (7) allows free arcuate movement of the roll (4) with up and down displacement in the plane passing through the axis (12) of the roll shaft, and the specified set of rolls (4) is made with the possibility of working in conjunction with the crushing table (3), characterized in that the housing (14) of the swivel bearing (7) has a diameter exceeding the diameter of the bearing journal (15) included in it by at least 1%. 2. The roller grinder according to claim 1, characterized in that the bearing housing (14) has a diameter exceeding the diameter of the bearing journal (15) by 1 to 25 °. 3. The roller grinder according to claim 1, characterized in that the bearing housing (14) has a diameter exceeding the diameter of the bearing journal (15) by 5 to 20 °. 4. Roller chopper according to claim 1, characterized in that the bearing housing (14) and the bearing journal (15) are made of the same material. 5. Roller chopper according to claim 4, characterized in that the bearing housing (14) and the bearing journal (15) are made of steel.

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