DE2319810B2 - Rotary grinder - Google Patents

Description

60

The invention relates to centrifugal mills, particularly of the pin or paddle wheel mill type.

In the known centrifugal mills, the working element consists of an impeller, which two coaxial Contains attached disks, in which on facing annular surfaces in circular Rows of grinding media are attached. The latter can be very different, for example in shape be made of cylindrical rods, elongated blades with flat or curvilinear working surface.

Recently, grinding media in the form of flat elongated blades have become popular. These Shovels are attached to the disks so that their working surface, which extends to one of the Sides, forms an angle of 5 ... 55 "with the line of the direction of rotation of the impeller. Here is one The end of the work surface, which is further away from the wheel rotation axis, is a little further forward than its other end, which is closer to the impeller axis of rotation, pushed (e.g. GB-PS 1141892 or German patent 12 96 943).

As is well known, the operation of centrifugal mills is based on the multiple striking of the Material to be ground and the grinding media. This is the reason for their, high efficiency and their good technological parameters.

In order to achieve such high characteristics, grinding media with blades in comparison with other known grinding media most successfully. However, it was found in practical use that extremely intensive wear of the grinding media occurs. In the case of grinding media in the form of the elongated flat Blades, which are at an angle to the line of the impeller direction of rotation, are mainly the Worn work surfaces. Nevertheless, it is an advantage of these grinding media that they can be used on their work surfaces forms a protective layer from the material to be processed. This layer reduces its wear and tear Paddles compared to differently shaped grinding media in which no such layer is formed.

To protect the ends of the working surfaces of the grinding media (blades), the blades are attached to the Ends reinforced with elements made of wear-resistant material. The reinforcement elements simply attached to the ends of the work surface, placing them over the work surface of the grinding media protrude, or they can be used in the grinding media so that they together with the rest Working surface of the grinding media form a common surface.

These elements are inserted in the direction perpendicular to the working surface of the whole grinding media stands.

However, such reinforcement was not found to be effective enough, since the reinforcement elements in In this case, they quickly begin to crack and detach from the grinding media.

Objects and advantages of the invention will be apparent from the description below.

The invention is based on the object of the construction of the grinding media, which have the shape of have elongated blades at an angle to the line of impeller rotation, to perfect in terms of wear resistance.

This task is performed with a rotary mill, mainly in the form of a centrifugal mill which the grinding media are attached to the impeller in circular rows and each grinding media with Is reinforced elements that are installed in the peripheral portions of the grinding media and their in relation on the impeller direction of rotation, front surfaces along a line which coincides with the line of the impeller direction of rotation forms an angle, are arranged so that the reinforcement element, which is closer to the impeller axis is located a little behind the impeller in the direction of rotation

Reinforcement element is located, which is further away from the impeller axis of rotation, solved according to the invention in that the front reinforcement element in the impeller direction of rotation is inserted into the grinding body along a line which, with the line along which the front surfaces of the reinforcement elements lie, an angle β of 5 .. 40 °, while the rear element in the same direction is inserted along a line which forms an angle γ of 10 ... 120 ° with the same line along which the front surfaces of the reinforcement members lie

It is advantageous that the front reinforcement element in the direction of rotation of the impeller is used in the grinding body along a line which forms an angle β of 15 ... 30 ° with the line along which the front surfaces of the reinforcement elements lie, while the rear element in the same direction is inserted along a line which forms an angle γ of 50 ... 110 ° with the same line along which the front surfaces of the reinforcing members lie

In order to consolidate the working surface of the grinding media, it is advantageous to have at least one reinforcement element to provide, which occupies a middle position between the peripheral reinforcement elements and in the grinding media is inserted along the line which is aligned with the line along which the front surfaces of the Reinforcement members lie, forms an angle <5 of 10 ... 170 °, whereby the middle reinforcement element somewhat opposite with respect to the line along which the front surfaces of the reinforcing members lie backwards to the direction of rotation of the impeller.

The arrangement of the reinforcement elements at the angles given above significantly reduces this The extent to which the reinforcement parts are destroyed. This even loosens in the case if by blows a reinforcement element cracks in particularly large pieces, no splinters and the element continues to fill its function.

Tests have shown that when reinforcing grinding media with more than two elements The wear resistance of the grinding media increases significantly if the reinforcement elements are arranged in such a way that their front surfaces in the direction of rotation of the impeller lie on a logarithmic curve.

An exemplary embodiment of the invention is described in detail below with reference to the drawing described; it shows

F i g. 1 shows the overall view of the centrifugal mill according to the invention, provided with grinding media (blades), where the impeller is shown in section,

F i g. 2 the spatial image of one of the two impeller disks of the centrifugal mill,

F i g. 3 the actual grinding body reinforced with two elements, the elements according to the invention being arranged on the periphery of the grinding body and being inserted into it (a piece of the material to be ground is shown in the drawing and its direction of movement is indicated by arrow A),

F i g. 4 a grinding body reinforced with three elements, the front surfaces of which, according to the invention, are on a logarithmic curve (in the drawing pieces of the material to be shredded are shown, and through Arrow »/ 4« indicates their direction of movement), and

F i g. 5 the spatial image of the in F i g. 4 shown grinding media.

A centrifugal mill is described as a special case of the mill.

The centrifugal mill contains impellers I and 2 (Fig. 1), of which the unites on a shaft 3 and the others seated on a shaft 4, which are driven by electric motors 5.

Each impeller consists of a disc 6 (Fig. 1, 7). soft in the middle has an opening 7 (Fig.2) for attaching the shaft 3 or 4. The grinding media 8 (FIGS. 1, 2, 3, 4 and 5) are attached to the impeller in circular rows.

Each grinding media is in the form of an elongated paddle which is attached to the disc so that the one, end of the blade further away from the disc in the direction of rotation of the impellers 1, 2 (the direction of rotation is indicated by the arrow "ffc") a little further forward than its other end, which is closer to the axis of rotation of the disk, is pushed.

Each grinding body can be reinforced with two elements 9 and 10 made of wear-resistant material, which at the periphery of the grinding media (Figs. 3 and 4), d. H. at the blade ends are arranged.

In addition, each grinding body can be reinforced with at least one element 11, which one Intermediate position between the peripheral elements 9 and 10 assumes.

The elements 9, 10, 11 have the shape of elongated parts extending over the entire length (1) of the grinding body and are inserted into this along their entire width (d) ( FIG. 5) as follows:

The element 9, which is installed in the front end of the grinding body 8 in the direction of rotation of the impeller 1, 2, is inserted into this along a line 12 which forms an angle with the line 13 along which the front surfaces of the reinforcing elements 9 and 10 lie β of 5 ... 40 °, in the optimal case of 15 ... 30 °. The element 10 is introduced along a line 14 which forms an angle γ of 10 ... 120 ° with the line 13, in the optimal case of 50 ... 110 °.

Each middle reinforcement element 11 is in the grinding media inserted along a line 15, which also forms an angle ό of 10 ... 170 ° with the line 13. Here, the central reinforcement element is with respect to the line 13, along which the front surfaces of the Elements 9 and 10 are set back somewhat opposite to the direction of rotation of the impeller 1,2.

The line 13, along which the front surfaces of the reinforcement elements 9 and 10 lie, is determined by the starting position of the work surface. The latter is inclined at the angle α to the line of the direction of rotation of the impellers 1, 2. As is known, this angle of inclination is in the range of 5 ... 55 °. For elements 9 and 11, the angle β or ό is selected to be larger the larger the angle λ, while for element 10 the angle γ is selected to be smaller, the larger the angle <x.

For example, at an angle «= 35 °, the angle 0 = 20 °, the angle y = 55 ° and the angle <$ == 90 °, while at an angle« = 55 °, the angles β = 30 °, γ = 90 ° and ό = 110 ° can be selected.

If three or more reinforcement elements 9, 10 and 11 are present, these will be so in the grinding media arranged so that their front surfaces lie along a logarithmic curve 16.

In the case of grinding media with three reinforcing elements, the working surface can be aligned in advance along a logarithmic Curve, but it is also possible to arrange the reinforcement elements only in such a way that that their front surfaces lie on the logarithmic curve without the working surface beforehand

is edited somehow. In this case, the work surface is used during operation of the device by the action of pieces of the material to be shredded depending on the specific location of the Reinforcement elements 9, 10 and 11 formed in the grinding media.

Grinding media with three reinforcing elements are used in centrifugal mills, which are used to grind one Mixture of materials of different hardness are determined. Reinforcing the grinding media with more than three elements is not justified.

In other mills, for example hammer mills or impact mills, the reinforcement elements are analogous to how this was described for centrifugal mills arranged.

Thanks to the reinforcement of the grinding media 8 is during operation of the centrifugal mill or a Another grinding plant designed according to the invention, the wear of the end sections of the grinding media (the blades) and at the same time the reinforcement elements significantly reduced, which are almost entirely in the Grinding media are used and where only the front surfaces 17 and 18 and the edge 19 of the corresponding elements 9, 10 and 11 are exposed. As a result, the reinforcement elements loosen,

ίο even if they crack, do not remove them from the grinding media. Tests have shown that the service life of the grinding media is threefold.

The design of the grinding media according to the invention not only increases their wear resistance, but also also ensures, as has been proven by tests, a more even grist.

1 sheet of drawings

Claims (1)

Patent claims: 1. Rotary mill, mainly in the form of a centrifugal mill, in which the grinding bodies are attached to the impeller in circular rows and each grinding body is reinforced with elements which are built into the peripheral portions of the grinding body and whose front surfaces with respect to the direction of rotation of the impeller along a line , which forms an angle with the line of the impeller rotation, are arranged so that the reinforcement element, which is closer to the impeller axis, is located in the impeller rotation direction somewhat behind the reinforcement element which is further away from the impeller rotation axis, characterized in that in the direction of rotation of the impeller (1, 2) front reinforcement element (9) is inserted into the grinding body (8) along a line (12) which forms an angle with the line (13) along which the front surfaces of the reinforcement elements (9 and 10) lie β of 5 ... 40 °, while the rear element (10) in the same direction is inserted along a line (14), d ie with the same line (13) along which the front surfaces of the reinforcement elements (9 and 10) lie an angle γ of 10 ... 120 °. 2. Plant according to claim 1, characterized in that the in the direction of rotation of the impeller (1, 2) front reinforcement element (9) in the grinding body (8) along the line (12) is inserted with the line (13), along the the front surfaces of the reinforcement elements (9 and 10) are located, forming an angle β of 15 ... 30 °, while the rear element (10) in the same direction is inserted along the line (14) which coincides with the same line (13), along which the front surfaces of the reinforcement elements (9 and 10) lie, forms an angle γ of 50 ... 110 °. 3. Plant according to claim 1, characterized in that at least one reinforcement element (11) is provided which occupies a central position between the peripheral reinforcement elements (9 and 10) and is inserted into the grinding body (8) along a line (15), which with the line (13), along which the front surfaces of the reinforcement members (9 and 10) lie, an angle δ of 10 ... 170 °, the middle reinforcement member (11) with respect to the line (13), longitudinally which are the front surfaces of the reinforcement members (9 and 10), slightly opposite to the direction of rotation of the impeller (1,2) is set back. 4. Plant according to claim 3, characterized in that the direction of rotation of the impeller (1, 2) front surfaces of all reinforcement elements (9, 10, 11) lie on a logarithmic curve (16).