WO2007011316A2

WO2007011316A2 - Knife mill

Info

Publication number: WO2007011316A2
Application number: PCT/SK2006/050002
Authority: WO
Inventors: Milan DOCÁR
Original assignee: Docar Milan
Priority date: 2005-07-15
Filing date: 2006-07-06
Publication date: 2007-01-25
Also published as: SK852005A3; CZ200882A3; WO2007011316A3

Abstract

The invention is related to a knife mill for grinding one sort of metal or plastic material, mainly in form of samples, scrap material and scraps where the need is to provide exact output fraction of crushed material. The knife mill compounded of a body (1) with a hopper (2), a holder (3), stator knife (4), rotor (5) with radial claws (6), rotor knife (7) and cylindrical sieve (8). In the body (1) under the hopper (2) is fixed in the holder (3) at least one flat stator knife (4) and cylindrical sieve (8) above which there is fixed rotationaly rotor (5) with at least one radial claw (6) on which is a mirror shape flat rotor knife (7) of a flat stator knife (4) and the flat stator knife (4) is stepped with the inclination from the horizontal position in the direction of rotor (5) rotation in the angle α in the range from 1 to 15 angle degrees and the flat rotor knife (7) is stepped in the front with the inclination from the radial position counterclockwise of the rotor (5) rotation in the angle β in the range from 1 to 15 angle degrees.

Description

Knife mill

Field of the Invention

The invention is related to a knife mill for grinding one sort of metal or plastic material, mainly in form of samples, scrap material and scraps where the need is to provide exact output fraction of crushed material. The most used materials for recycling are plastic materials, rubbers, paper, fabrics, cables, colour metals, etc.

Summary of the present invention

By now in the industry of plastic materials and rubber are used modified small knife mills and for special use are minimills, for example for laboratory purposes on homogenization and grinding dry, fibred material with possible content of oil. For recycling colour metals, cables and electroscraps are used heavy mills of variable construction.

Small knife mills implement homogenization and grinding with the help of sharp cutting knives. The cutting edge is straight and in the process it makes right angle in the clockwise rotation. Knives are thin, the cutting section is generally inclined in the inclination of 15 angle degrees and the section is detrited in the inclination of 30 angle degrees. The source of the cutting power is in this geometrical order the difference in the speed of material and cutting knives. The speed of rotation is from 2000 up to 10 000 rt./min. and it is generally possible to set it up about 500 rt./min. It is also possible to set the time of grinding for 3 minute intervals, at which the mill can be movable. The disadvantage of this machinery is low serviceable life of knives, low output suitable only for laboratory grinding of smaller pre-prepared pieces of material with low hardness and expensive operating.

Other small knife mills are determined for laboratory grinding of raw materialsand materials of hardness 9 Mohsa degrees in the quantity from 100 up to is grinding equipment with race-way free hanged on six strings, compounded of grinding ring and cylindrical or conic cylinder. The upper part of the box is equipped with a cover closing the equipment during the operation. For the easier moving the box is equipped with handles. The mill is supplied by grinding bowls with a grinding ring, which can be hard material-lined, for example by corundum and cylinder. The disadvantage of this machinery is low output suitable only for laboratory grinding of smaller prepared pieces of material with low hardness and expensive operation.

Other small knife mills are based on the principle of millout fragments by double or more segmental knife cutters of rotor in conic stator opening. However this kind of machine has low productivity, expensive operating and it is suitable only for laboratory use.

Well known is also a knife mill for cutting, crushing and grinding techonological materials, for example plastic, leather, rubber, paper and textile, scraps according to the CZ PV 1992-0136, containing stator box which is compounded of right angle welder. Stator box is equipped by two oblique stator knives, from which one stator knife is stepped and fixed in the way, that its pit lays above splitting level in the equivalent distance to the height of the stator knife at which the stator knives include advantageously the angle 4 of angle degrees with rotor knives. The disadvantage of this machine is that its construction is not suitable for grinding metal materials

Well known are also knife mills grinding plastic material and less hard material waste for high operation output. The box of the mill has input shaft in the lower part equipped with long longitudinal stator knife under which in the box is a rotary stepped cylindrical rotor with more radial niches sequenced consecutively in more rows on the rotor perimeter to the stator knife what enables fluent retractoring of scraps to the mill with limited movement while grinding. The grinding is realized by water or dry method. The disadvantage of this machiney is low serviceable life of knives, suitability of material grinding is only with low hardness and expensive operation.. Well known are also heavy knife mills which have a hopper, a box and also a spout tightly secured against a release and opening with safe mechanic-electric system with decoding controlling relay. The service is protected from the danger of an injure. To open the grinding area is possible after the release of safe locks at which the opening of the area ensures the rotating parts to be in steady position. These kinds of rotor mills have obliquelly stepped long rotor knives and long stator knives with balancing cleats and regrinded cutting edges by which they provide effective cut as of long and bigger material. The operation of the mill is denoted by often impacts. Knives are provided by stop bolts and after they are regrinded they can be repeatedly aligned for stepping in the box. Chucking screws are tensioned and they are not possible to be released during the operation. The material of the knives ensures their high hardness and tenacity without any crash risk. In alternative realizations the rotor and statory knives can be made of some segments behind each other. The disadvantage of these kinds of machines is having quite fast wear-off mainly of cutting edges input part of rotor knives by impacts against the surface of a thick material at grinding where their thickness is weakened by regrinding, by which the life is substantially lowered and the expenses for their aligning and service still increase. Unequal deterioration of the whole pit causes fast, mainly at aluminium leaking and sticking of a cut material, or in some cases exchange of cutting pits and using economically demanding pre-arranging machine.

Well known is also a granulator of plastic waste materials according to the CZ patent No. 290444, compounded of operating tank with a hopper, a frame of knife system, electro-drive and operating panel which has a knife system compounded of stationery knifegrate consisting of at least eight stable plate knives and counterclockwise rotating pair of half-round grasped knife segments on parallel shafts where each segment is made of at least seven rotating knives aligned to shafts which cutting edges are at the rotation in the contact with cutting edges of steady knives of a knife grate and create knife pairs with them. The disadvantage of this machine is that the granulator at grinding some material operates with strong and often impacts by which it causes quite fast wear-off of the stator and rotor knives against the surface of a thick grinded material and it substantially lowers its life, at increased expenses for alignig and operating of this kind of mill. Unequal wear-off of the whole top of the knife pits is caused quickly mainly because of aluminium leaking and sticking of a cut material in cutting knives, what demands either often exchange of cutting pits or use of economically demanding pre-arranging machine.

Well known is also a knife mill compounded of a body with a hopper, a holder of stator knife, rotor with radial spouts of a rotor knife and a cylindrical sieve. In the body cylindrical sieve is situated under the hopper and at least two thin flat stator knives of tetragonal cross section fixed in a holder in diagonal way above which there is rotor rotationally stepped with a pair of two thin rotor knives with tetragonal cross section with sharp edges fixed in a radial spout in the way that the exserted pits of stator knives freely interlock to the corresponding mirror depressions of rotor knives, where stator and rotor knives are mostly made of cemented carbide. Stator knives are stepped next to each other in straight and diagonal way exactly with the axis of rotor, rotor knives are stepped next to each other either parallely or obliquely or spirally. The disadvantage of this machine is that at grinding immediate point of grinding material connection comes up with their thin pits of stator and rotor knives by which there is quite fast wear-off of fragile but hard thin material mainly at exserting sharp cutting edges of stator and rotor knives by impacts against the surface of a thick grinded material. This is the reason why the knife life is extremely decreased and the expenses increase for aligning and also for service of this mill. Following, the mill has also small area of cutting tools and low rotor rotations and therefore it has low productivity of grinding. Unequal wear-off of the whole top of the knife pits is caused so quickly mainly because of aluminium leaking and sticking of a cut material in cutting knives what demands either often exchange of cutting pits or use of economically demanding pre-arranging machine.

The basics of the invention

Given imperfections remove in considerable rate the knife mill compounded of the body with a hopper, a holder, a stator knife, a rotor with radial spouts, a rotor knife and a cylindrical sieve. The basic of the invention is that in the body under the hopper is fixed in the holder at least one flat stator knife and cylindrical sieve, above which there is fixed rottationaly rotor with at least one radial claw on which is a mirror shape flat rotor knife of a flat stator knife. The flat stator knife is stepped with the inclination from the horizontal position in the direction of rotor rotation in the angle α and in the range from 1 to 15 angle degrees and the flat rotor knife is stepped in the front with the inclination from the radial position counterclockwise of the rotor rotation in the angle β in the range from 1 to 15 angle degrees.

At the same time it is profitable if the flat rotor knife has bevelled cutting edge from the tangent in the centre of cutting edge from both sidesin the angle δ and δ^' in the range from 1 to 30 angle degrees and if there are at the same opposite each other oriented angles δ and δ^' two-side believed the flat rotor knife^'s cutting edge from the tangent in the centre of the cutting edge.

Other advantage is that if at least one pit of the flat rotor knife cutting edge ended with radius and/or if it has at least part of the rotor cutting edge the shape of radius or if the cutting edges of the flat rotor knife and the flat stator knife are two-side symetric.

The advantage is also if the flat stator knife compounded from at least two segments fixed next to each other in the holder and/or if the flat rotor knife compounded from at least one segment.

Just as the advantage is if the segments of the flat rotor knife are towards the axis either diagonal or oblique or spiral or sloping or arrowy.

The biggest advantage of the knife mill is according to the invention is that for milling are used thick tough flat stator knives from which all four edges by appropriate fixation in the holder slope of the stator knives and in radial claws of rotor create cutting edges without the need of bevelling and weakening the surface. The exchange of cutting edges is very simple and not demanding on time. Moreover used a big angle on the pits of knives expressively increases their serviceable life, decreases expenses on aligning and gives the suitability of the machine for a high output appropriate not only for big unprepared pieces of material for laboratory purposes with high hardness but also for current low expensive operating grinding - crushing metal materials in the form of waste materials, for examples scraps. Whereas the knife mill operates with minimal impacts of grinded material against the edge of cutting knives and it has relatively equal wear-off of the whole pit of a knife, does not appear at it, mainly at alluminium leaking and sticking of grinded material in the centre among cutting knives, what shortens mending time and replacement of cutting knives, at which this machine does not demand the use of economically expensive pre-prepared machine while grinding, but it is suitable also for this purpose. The knife mill is according to the invention compared to mentioned machines in the present status operates with substantially higher rotations of the rotor and it has substantially higher productivity of processed material crushing by which it is suitable for machines capable to processed operating links.

Brief description of the drawings

The example of a knife mill according to the invention is shown in attached drawings where in the Fig. 1 is schematically depicted knife mill with one flat stator knife and four rotor knives, in the Fig. 2 is schematically depicted the beginning of an adjacent segment stator knives pair cut and segment of the rotor knife, the Fig. 3 schematically shows the depiction of the cut ending of adjacent segment stator knife and segment rotor knive pairs, the Fig. 4 schematically shows the flat rotor knife with cutting sharp knife with two cutting sharp pits, the Fig. 5 schematically shows the flat rotor knife with two cutting sharp pits, the Fig. 6 schematically shows the flat rotor knife with a pit of the cutting edge with radius and the Fig. 7 schematically showsflat rotor knifewith curved cutting edge.

Detailed description of the preferred embodiment

The knife mill is according to the invention shown in the Fig. 1 compounded of a body 1. with a hopper 2, a holder 3, a stator knife 4, a rotor 5 with radial claws 6, a rotor knife 7 and a cylindrical sieve 8. Above the cylindrical sieve 8 is in the body 1_ stepped flat stator knife 4 fixed in the holder 3. Further above the cylindrical sieve 8 under the hopper 2 is rotationally stepped rotor 5 with four flat rotor knives 7 fixed on radial claws 6 with two-side bevelled cutting edges from the tangent in the middle of the cutting edge under the hopper in the angle δ and δ^' at the value of 15 angle degrees. The flat stator knife 4 is next stepped with the inclination form the horizontal position in the way of the rotor 5 rotation in the anlge α at the value of 8 angle degrees and the flat rotor knife 7 is stepped in the front with the inclination from radial position with the inclination counterclockwise of the rotor 5 rotation in the angle β at the value of 6 angle degrees. The angles δ and δ^' oriented opposite each other which have two-side bevelled the cutting edge of the flat rotor knife 7 as well of the stator flat knife 4 are two-side symetric and make up right angle in the middle of the cutting edge (see Fig. 4). The flat stator knife 4 has a mirror shape flat rotor knife 7 and it is compounded from two segments fixed in the holder 3 and flat rotor knife 7 is composited by only one segment fixed on the radial claw 6 of rotor 5 (see Fig. 2, Fig. 3) and the segments of the flat rotor knife 7 are located paralelly towards the axis of rotor 5.

In the initial position of the knife mill the material is set for grinding, e.g.: colour metal scraps, etc, either in doses or it is fluently forwarded to the hopper 2 of the rotor mill while rotor 5 rotating and subsequently it falls to the hopper 2 by gravitation on the surface of the rotor 5 rotation to the rotor knives 7, which fluently with their cutting edge in the counterclockwise cutting edge of the stator knife 4 from time to from fluently cut from the pit of the rotor knife 7 (see Fig. 2) up to the pits of the stator knife 4 (see Fig. 3). The cut-off material then falls down and it is subsequently pressed by rotor knives 7 along the internal side of the cylindrical sieve 8 to not shown general transporting container - pallette or to the hopper of a suitable transporting equipment. Bigger clips of a material than the holes in the cylindrical sieve 8 are at the same time transferred by rotor knives 7 along the internal side of the cylindrical sieve 8 into the hopper 2 of the body 1. of the knife mill where they are mixed and the re-filled material set for grinding at which the described operation cycle still repeats at known clips offtaking under the cylindrical sieve 8 until the whole material is completely grinded. In the case of some cutting edge damage either of stator knife 4 or rotor knife 7, the rotor 5 of the knife mill stops and the material set for grinding is removed from the hopper 2. Following the damaged knives 4, 7 are replaced either by new ones or their damaged cutting edge is replaced by another not damaged cutting edge, i.e. after the release of correspondent knives 4_± 7 in the holder 3 or in the radial claw 6 of the rotor 5_ is by a suitable combination of knives^' turn 4, 7 about 180 degrees in some of their both axis of symmetry following by the known way are fixed in the holder 4 or in the radial claw 7 of the rotor 5 of the knife mill with the knife mill operation starts rotating by which the machine is again in the initial position for grinding of needed material.

The described and shown example of the knife mill is not the only possible according to the invention, to what extent, it can consist two or more flat stator knives fixed in a self-standing holders, the rotor can consist 1 , 2, 3 or more than 4 flat rotor knives fixed on the radial claws, two-side bevelled cutting edges from the tangent, in the middle of the cutting edge they can be made in the angle δ and δ^' in the range form 1 to 30 angle degrees, at which δ and δ^' can be different from each other. The flat stator knife can be stepped with the inclination from the horizontal position in the rotor rotation direction in the angle α in the range from 1 to 15 angle degrees and flat rotor knife can be stepped with the inclination from the radial position of the opposite the rotor rotation direction in the angle β in the range from 1 to 15 angle degrees. One or more pits of the rotor knife cutting edge can be ended by radius or at least part of the cutting edge of the flat rotor knife can have the shape of radius. The flat stator knife can also be compounded from 1 or 2 pieces and more segments stepped in the holder next to each other and flad rotor knife can be stepped from 1 or 2 and more segments fixated parallel on the radial claw of the rotor. Segments of the flat rotor knife can be oblique or spiral or arrowy or rounded to the axis of the rotor.

Industrial applicability

Knife mill wherein the invention can be used in the industry for adjustment of scrap and waste material, mainly of colour and iron metal in the metalurgy, for laboratory crushing or pre-granulation of hard samples in the metalografi, for crushing plastics, tyres, leather, rubber, paper, waste wood and also as pre-granulator of wood matters at the production of woo chip board, etc.

Claims

P A T E N T C L A I M S

1. The knife mill compounded of a body (1 ) with a hopper (2), a holder (3), stator knife (4), rotor (5) with radial claws (6), rotor knife (7) and cylindrical sieve (8), wherein in the body (1 ) under the hopper (2) is fixed in the holder (3) at least one flat stator knife (4) and cylindrical sieve (8) above which there is fixed rotationaly rotor (5) with at least one radial claw (6) on which is a mirror shape flat rotor knife (7) of a flat stator knife (4) and the flat stator knife (4) is stepped with the inclination from the horizontal position in the direction of rotor (5) rotation in the angle α in the range from 1 to 15 angle degrees and the flat rotor knife (7) is stepped in the front with the inclination from the radial position counterclockwise of the rotor (5) rotation in the angle β in the range from 1 to 15 angle degrees.

2. Knife mill as claimed in claim 1 , wherein the flat rotor knife (7) having bevelled two-side cutting edge from the tangent in the middle of the cutting edge in the angle δ and δ^' in the range from 1 to 30 angle degrees.

3. Knife mill as claimed in claim 2, wherein the opposite oriented angles δ and δ^' two-side bevelled cutting edge of the rotor knife (7) are the same from the tangent in the middle of its cuttin edge.

4. Knife mill as claimed in claim 1 , wherein the flat rotor knife (7) having bevelled two-side cutting edge from the tangent area in the axis direction in the angle δ and δ^' in the range form 1 to 30 angle degrees.

5. Knife mill as claimed in claim 2, wherein having opposite oriented angles δ and δ^' bevelled two-side cutting edge of the flat rotor knife (7) from its tangent position are the same.

6. Knife mill as claimed in claim 1 , wherein the having at least one pit of the cutting edge of the rotor knife (7) is ended with radius.

7. Knife mill as claimed in claim 1 or 2, wherein the having at least one part of the flat rotor knife (7) cutting edge the shape of radius.

8. Knife mill as claimed in claim 1 or 2 to 5, wherein the cutting edge of the flat rotor knife (7) and the flat stator knife (4) being two-side symetric.

9. Knife mill as in the claim 1 or 2 to 6, wherein the flat stator knife (4) being compounded from at least two segments fixed next to each other in the holder (3).

10. Knife mill as in the claim 1 or 2 to 6, wherein the flat rotor knife (7) being compounded from at least one segment.

11. Knife mill as claimed in claim 8, wherein the having the segments of the flat rotor knife (7) parallel to the axis of the rotor (5).

12. Knife mill as claimed in claim 8, wherein the having the segments of the flat rotor knife (7) oblique to the axis of the rotor (5).

13. Knife mill as claimed in claim 8, wherein the having the segments of the flat rotor knife (7) spiral to the axis of the rotor (5).

14. Knife mill as claimed in claim 8, wherein the having the segments of the flat rotor knife (7) rounded to the axis of the rotor (5).

15. Knife mill as claimed in claim 8, wherein the having the segments of the flat rotor knife (7) arrowy to the axis of the rotor (5).