WO1996014157A1

WO1996014157A1 - Impact mill for adhesive products

Info

Publication number: WO1996014157A1
Application number: PCT/EP1995/004216
Authority: WO
Inventors: Jan Van Den Meersche
Original assignee: Henkel Kommanditgesellschaft Auf Aktien
Priority date: 1994-11-04
Filing date: 1995-10-26
Publication date: 1996-05-17
Also published as: DE4439449A1

Abstract

The invention concerns an impact mill which comprises a substantially cylindrical mill housing (1) and an inlet and outlet opening (12), with beaters (19) which can rotate about the housing axis and are directed towards the inner wall of the housing (1), and with at least one stripper (4, 5) which can rotate in the same or opposite sense about the housing axis. In the axial direction, the peripheral end of the stripper (4, 5) extends at least over the axial region occupied by the beaters (19) and is at a shorter distance from the inner wall of the housing (1) than the beaters (19). The end of the stripper (4, 5) which is directed towards the inner wall of the housing (1) comprises saw-like teeth with a triangular tooth shape, and the acute peripheral ends of the teeth are at most 1 mm from the inner wall of the housing (1). Relatively coarse particles are prevented from emerging through the outlet opening (12) so that a connected pneumatic conveying system is not blocked.

Description

"Impact grinder for sticky products"

The invention relates to a beater mill for sticky products with a mainly cylindrical mill housing, an inlet and an outlet opening, with beaters which can be rotated about the housing axis and directed towards the inner wall of the housing and with at least one wiper which can be rotated in the same direction or in the opposite direction about the housing axis. the peripheral end of which extends in the axial direction at least over the axial area occupied by the rackets and is at a smaller distance from the inner wall of the housing than the rackets.

When comminuting sticky products in impact or impact mills, problems frequently arise due to caking of the product inside and at the outlet opening of the mill. These products include, for example, detergents and cleaning agents rich in surfactants as well as their ingredients and premixes.

The mills of the type mentioned tend to become blocked when processing sticky material, for example moist material or material that tends to cake for some other reason. Various measures are known from the prior art with which this problem can be solved.

Particular difficulties arise when the sticky material is to be conveyed pneumatically after comminution. In this case, the particles must be small enough to be carried along by the air flow and not to clog the transport lines.

The problem of clogging by sticky regrind is solved in the impact mill known from German patent specification 1 220 237 by lining the impact plates with an elastic material, for example rubber. However, this mill points through the inside of the Mills housing protruding attachments of the baffle plates on a variety of dead spaces in which the sticky, prone to caking material accumulates during operation. This impact mill is also designed for processing pre-shredded particles. Coarser granules pass through the mill without being crushed and lead to the blockages already mentioned in pneumatic conveying lines.

A further impact mill, which is suitable for comminuting material which tends to stick, is described in German Auslegeschrift 1,296,941. Baking of the sticky products is also prevented here, as in the impact mill already mentioned, by lining the inner surfaces of the housing with an elastic material with a smooth surface. The lining of all inner walls of the mill, which can be reached by the sticky particles, leads to a relatively high outlay.

Another impact mill does not have a lining of the inner walls. This mill, which is known from EP 0 353 576 A2, is equipped with removal beaters or scrapers in order to avoid blockages due to caking of the product. The beater wheel is equipped with two diametrically opposed, enlarged wipers which keep a grinding chamber on the periphery of the beater wheel free and thus prevent the beater wheel from blocking due to caking product. The peripheral edge of the clearing racket is provided with a toothing which is arranged in such a way that the tooth of one clearing racket falls into the gap of the other. With this measure, a long service life of the impact mill can be achieved without great effort, even if heavily caking or sticky products, for example detergents, are ground. But problems also arise here if the ground product is to be conveyed pneumatically. If coarser particles adhere to the inner wall of the housing, they are conveyed to the outside by the scraper or scraper without having been crushed beforehand. These relatively large particles are not conveyed further by the air flow and gradually block the transport lines. The invention is therefore based on the object of preventing a coarse particle of the type mentioned from escaping through the outlet opening of coarser particles which would clog a pneumatic conveyor system connected to the outlet.

This object is achieved in that the end of the scraper facing the inner wall of the housing has saw-like teeth with a triangular tooth shape and the pointed peripheral ends of the teeth are at a distance of at most 1 mm from the inner wall of the housing.

According to the invention, coarser particles are no longer scraped off the inner wall of the housing by the scraper, even if coarse particles bake there. On the one hand, such coarse particles are crushed by the pointed, saw-like teeth during scraping. On the other hand, thicker layers cannot form on the inner wall of the housing, since the teeth have a maximum distance of at most 1 mm from the housing.

The sawtooth shape of the scraper leads to another advantage. Previously, the mill had to be cleaned after it had been stopped in order to be able to start it up again without any problems, since the layer applied to the inner surface of the mill housing would have required the motor to start up too quickly. In the sawtooth-like shape of the scraper according to the invention, cleaning before restarting is no longer necessary, since only a relatively low starting torque is required even with a layer attached to the inner surface of the housing.

With the shape of the scraper according to the invention, the detached product batch cannot be pressed between the inner wall of the mill and the scraper. Such pressing is completely ruled out if, in an advantageous embodiment of the invention, the end face of the teeth of the scraper facing the inner wall of the housing forms a wedge gap tapering in the circumferential direction of the scraper with this inner wall.

In a preferred embodiment of the invention, the surfaces of the teeth of the wiper pointing in the direction of movement have the shape of equilateral triangles. In a particularly preferred embodiment of the invention, a plurality of wipers with teeth offset from one another are provided. Two wipers are preferably provided, the teeth of one wiper falling into the gaps between the teeth of the other wiper.

The teeth of the leading scraper tear open the product batch in a strip. The main part of the remaining product approach strips is removed from the teeth of the subsequent stripper. The sawtooth-like shape of the stripper ensures that the product batch is reduced to small enough particles during the scraping process, which are carried by the air flow in a pneumatic conveying system downstream of the mill and thus do not cause blockages in the transport system.

The downtimes of the production plant due to coarse particles which the mill releases into the pneumatic conveying line can be further reduced in an advantageous embodiment of the invention. In addition to a cylindrical area of the inner wall of the housing, the impact mills frequently have zones, so-called dead zones, which deviate from the cylindrical shape, in the area of the outlet opening of the mill. So that no product layer builds up in this part and the line can no longer be blocked by particles flaking off this layer, it is proposed to attach fittings to the dead zones which enlarge the cylindrical area of the inner wall.

In addition, the dead zones can advantageously be lined with an elastic material which likewise prevents the product from caking.

These measures according to the invention made it possible to operate a mill with a service life of more than one week. Before these measures were implemented, the idle times were between 4 and 8 hours.

The invention further consists in the use of the abovementioned beater mill for comminuting sticky ones and those which tend to form agglomerates Granules, especially granules that are active in washing and cleaning. Due to their surfactant content, these granules are particularly prone to agglomerate formation and caking.

In a further use according to the invention of the abovementioned beater mill, it is used for comminuting coarse fractions of a premix which is intended for the production of compacted granules by extrusion and division of the extruded strand to the desired granule size, the granules being used in washing machines. and cleaning agents are provided.

In addition, the impact mill can be used advantageously for crushing these compacted granules.

Such granules and their preparation are described in more detail, for example, in WO 91/02047. The granules are extruded from homogeneous premixes with the addition of a plasticizer and / or lubricant through perforated shapes with opening widths of the predetermined granule dimension at high pressures between 25 and 200 bar. After exiting the hole shape, the strand is cut to the predetermined granule size by means of a cutting device, sieved and powdered. After rounding off the edges in a rounding device, the granules are dried and cooled.

The impact mill according to the invention is particularly suitable for use in this process. The coarse fractions to be comminuted with the impact mill are obtained on the one hand after the premix has been sieved and, on the other hand, after the cut granules have been sieved before they are powdered. The above-mentioned problems occur here to an increased degree, because the premix and the warm, not yet powdered granules, because of their surfactant content, have a very strong tendency to stick to one another and thus to form coarse agglomerates and to bake inside the beater and their outlet opening.

An embodiment of the invention is described in more detail with reference to drawings. Show it FIG. 1 shows a side view of a hammer mill according to the invention in the direction of the mill axis, partly in section,

FIG. 2 shows a view of the impact mill in the direction of arrow II in FIG. 1,

FIG. 3 shows a section transverse to the longitudinal axis of the impact mill according to FIG. 1,

Figure 4 shows a detail of Figure 3 and

5 shows the view A of the peripheral end of the scraper in FIG. 4.

In a mainly cylindrical housing 1, which is surrounded by a cover 2, rotated on a beater wheel 18 and radially extending from there bats 19 and a scraper ring 3. On the outside of the scraper ring 3 are two opposite, over the entire length the stripper 4, 5 extending striker attached. The scraper ring 3 rotates in the direction of arrow 6 in the opposite direction to the beater wheel 18, which rotates in the direction of arrow 7.

The cylindrical inner wall in the upper part of the housing 1 continues downwards as a flat vertical wall. To adapt to the upper cylindrical inner wall, fittings 8, 9 are attached to the vertically extending walls 10, 11.

The shredded product falls down through the outlet opening 12 into the pneumatic conveying area. Conveying air flows in from the left, which is indicated by the arrow 20, and the product is pneumatically transported in the direction of the arrow 21. Caking in the area of the outlet opening 12 is avoided by the lower ends of the shaped pieces 8, 9 passing into rubber aprons 13, 14, the other ends of which are fastened to the lower edge of the outlet opening 12.

FIG. 2 shows, among other things, the product inlet 22 through which the still unreduced product is fed to the beater wheel 18. To the comminution, the product falls down and exits the product outlet 23 in order to be transported pneumatically. The structure and the mode of operation of the mill can be seen particularly clearly from this drawing and is therefore not explained again. Here, as in the other drawings, the same reference symbols have the same meaning.

The parts of the exemplary embodiment which are essential for the invention, namely the upper region of FIG. 1, are shown again in FIG. 3 for the sake of clarity.

Figure 4 shows the scraper 4 in an enlarged form. The scraper consists of a solid profile 15 which carries a sharply ground toothed knife 16. The sawtooth tips of the knife 16 are only 1 mm from the inside of the housing wall 1.

FIG. 5 shows view A in the direction of arrow 17 of FIG.

B e z u g s z e i c h e n l i s t e

casing

cover

Scraper ring

Wipers

arrow

Fitting

Fitting vertical wall vertical wall

Outlet opening

Rubber apron

profile

knife

arrow

Bat wheel

bat

arrow

Product inlet

Product outlet

Claims

Patent claims

1. Impact mill for sticky products with a mainly cylindrical mill housing (1), an inlet and an outlet opening (12), with beaters (19) which are rotatable about the axis of the housing and directed towards the inner wall of the housing (1) and with at least a scraper (4, 5) which can be rotated in the same direction or in the opposite direction, the peripheral end of which extends in the axial direction at least over the axial area occupied by the beaters (19) and a smaller distance from the inner wall of the housing (1) than that Racket (19), characterized in that the end of the scraper (4, 5) facing the inner wall of the housing (1) has saw-like teeth with a triangular tooth shape and the pointed peripheral ends of the teeth are at most 1 mm from the inner wall of the Have housing (1).

2. Impact mill according to claim 1, characterized in that the end face of the teeth of the stripper (4, 5) pointing towards the inner wall of the housing (1) with this inner wall a in the circumferential direction of the stripper (4, 5) tapering wedge gap.

3. Impact mill according to one of the preceding claims, characterized gekenn¬ characterized in that the surfaces pointing in the direction of movement of the teeth of the stripper (4, 5) have the shape of equilateral triangles.

4. Impact mill according to one of the preceding claims, characterized gekenn¬ characterized in that a plurality of wipers (4, 5) are provided with mutually offset teeth.

5. Impact mill according to the preceding claims, characterized in that two wipers (4, 5) are provided and the teeth of one wiper fall into the gaps between the teeth of the other wiper (4, 5).

6. Impact mill according to one of the preceding claims, with a cylin¬ area of the inner wall of the housing and from the cylindrical shape deviating zones (dead zones) in the region of the outlet opening of the mill, characterized by fittings (8, 9) attached to the dead zones, the enlarge the cylindrical area of the inner wall.

7. impact mill according to the preceding claim, characterized in that the dead zones are lined with an elastic material (13, 14).

8. Use of the impact mill according to one of the preceding claims for comminuting sticky granules which tend to form agglomerates, in particular granules which are active in washing and cleaning.

9. Use of the impact mill according to one of claims 1 to 7 for crushing coarse fractions of a premix which is intended for the production of compacted granules by extrusion and division of the extruded strand to the desired granule size, the granules for use in washing - And cleaning agents are provided.

10. Use of the impact mill according to one of claims 1 to 7 for crushing compacted granules which are used in washing and cleaning agents and which have been produced from a premix by extrusion and division of the extruded strand to the desired granule size are.