GB2323545A

GB2323545A - Hammer mill or hammer crusher

Info

Publication number: GB2323545A
Application number: GB9805580A
Authority: GB
Inventors: Reinhard Hoffmann
Original assignee: Noell Service und Maschinentechnik GmbH
Current assignee: Noell Service und Maschinentechnik GmbH
Priority date: 1997-03-29
Filing date: 1998-03-16
Publication date: 1998-09-30
Also published as: BR9801139A; GB9805580D0; FR2761279A1; AU5840298A; CN1194886A; DE19713264C1; ZA981814B; FR2761279B1; CA2229957A1; JPH10277417A

Abstract

The invention relates to a hammer mill or hammer crusher which is provided with two rotors 2, 3 inside the housing 1. The rotors are essentially encircled by grinding paths 13, which are laterally retractable from the housing in an essentially horizontal direction. Provision is thereby made for the innermost section 23 of the grinding path located behind the rotor and projecting upwards from the lowest part of each rotor to be tilted downwards on retraction of the grinding path 13 and thus freeing this part to pass beneath the rotor. According to the invention, curved flanges (24, 25) are provided on the downwardly tiltable section, which are supported by a counter-support (30) when the grinding path is advanced from its withdrawn position to its working position to raise the tiltable section 23 to its working position.

Description

2323545 Hammer mill or hammer crusher The invention relates to a hammer

mill or hammer crusher equipped with at least one rotor fitted with impacting implements and at least one grate or rrOing unit as counteracting implement allotted to the rotor or to each rotor and at least partially encircling the rotor and comprising impact bars, grate bars or screens and corresponding retaining side waNs, the said grate or milling unit being provided with a guide device having a plurality of roller pairs and rails which allows its movement in an essentially horizontal direction for withdrawal of the grate or mfifing unit from the housing, with a device to permit sufficient lowering of that section of the grate or milling unit which is designed to tilt downwards and whick when viewed from the direction of retraction, lies behind the is vertical sectional plane passing through the rotor axis and projects upwardly from the lowest part of the rotor so that, on withdrawal of the grate or milling unit from the rotor, the said tiltable section can swing downwards on hinges connecting it to the fixed part of the grate or milling unit and pass freely underneath the bottom of the rotor.

in such types of mill or crusher, the crushing process is effected through impact by the rapidly rotating hammers in conjunction with counter-acting implements. Such machines are designed with one or two rotors as singleor double-shaft hammer mills or crushers, and have a high crushing efficiency. The counter-acting implements encircle the rotors and are only interrupted by the material inlet. Depending on the properties of the feed material and the degree of crushing required, the counter-acting implements are provided as screens, milling grates or grinding paths, or a combination of all these implements. The crushed material is discharged pneumatically from the rrO or crusher via the screens or grates; the material outlet can be arranged underneath or above the rotor(s). In order to achieve maximum capacity and crushing efficiency, each rotor is enclosed extensively by the counter-acting implements.

2 Such counter-acting implements are subjected to high wear and must be easily replaceable. In the case of the afore-mentioned impact or hammer mills according to DEPS 472 243, the screen unit provided underneath the rotor is equipped with a guide device to permit its horizontal movement and which comprises pairs of rollers and corresponding rails to accommodate them. In order that the section of the screen unit projecting upwards from the lowermost point of the rotor behind the vertical sectional plane passing through the rotor axis can pass freely underneath the rotor when the screen unit is withdrawn from the crusher housing, the section is designed to tilt downwards on hinged j o ints.

For this purpose, the downwardly-tiltable section is movably connected by means of an axle to the carriage-type frame which accommodates the retainers or side bars carrying the screens. The axle firmly connected to the downwardly-tiltable section features a lever which is in engagement with a tie-rod, the end of which is designed as a threaded spindle.

By means of a cranking handle attached to the threaded spindle, the lever can be pivoted and the tiltable screen section tilted downwards. This design is, however, costly, and in addition to the fact that the movable parts, such as]ever, tie-rod and in particular the threaded spindle are located in the material flow and subjected to fouling and wear, actuation of the crank handle can only be effected manually and is thus onerous.

Furthermore, this manual actuation cannot be utflised in larger hammer mills or crushers.

DE 32 15 882 AI refers to a hammer crusher in which the grate units underneath the rotor are equipped with a guide device which allows essentially horizontal movement, said device comprising pairs of rollers and rails to accommodate them. On retraction of the grate units from the crusher housing, in order to permit free movement underneath the rotor of the grate section which is located behind the vertical sectional plane passing through the rotor axis and which projects upwardly from the lowermost point of the rotor, the rails are arranged in a sloping manner so that the grate units are lowered during the retraction movement.

3 In order to achieve this, however, it is necessary for the rails for the eont and rear rollers to be arranged in an offset manner, so that a total of four rails is required per grate unit, or the design of the outer rollers must be executed adjustably by means of an additional mechanism. Additionally, provision is made for the crushing pressure to be absorbed by a carrier tube onto which the particular grate unit with its grate side plates has to be seated. This design is complicated and thus expensive, as there has to be an exact and precise matching of the rails with their slopes to the rollers as well as the grate units to the corresponding carrier. tube and other housing parts. Moreover, in addition to the grates, which of course can also be designed as grinding paths, the double-shaft hammer crusher described therein is provided centrally with an anvil, which is only separately exchangeable with some effort.

The same applies to the hanuner crusher according to DE 21 40 026 Al. It differs from the present state of technology described above in that the retractable frame with the is associated housing section, reception side plates and grate, which is allotted to each rotor is mounted on different rails. In the outer zone, the rails are embedded in the foundation which supports the hammer crusher and carry the outer rollers affixed to the retractable housing section. Moreover, the side plates connected to the housing section are themselves designed as rails which ride on pairs of rollers laterally affixed to the housing. In addition, outer and inner counter-supports are provided for the housing and grate. Furthermore, only a small section of the inner- facing part of the grate is in interaction with the rotor, so that the grate does not need or hardly needs to be lowered. The hammers are movably attached to the rotor, so that they are free to avoid any collision. With this design, the inside grate (or in the case of double- rotor crushers, the grates arranged near to the centre) have to be changed separately.

An object of the invention is to avoid the disadvantages of the present state of technology described above and to present a hammer rnill or hammer crusher with counter-acting implements which enclose the particular rotor to the maximum extent for the purpose of increasing the corarninution effect, whereby all grinding path, milling grate or screen 4 parts arranged underneath the rotor(s) are easily accessible and hence easily replaceable. At the same time, in respect of the fabrication process, the necessary matching of the components should be easy to execute, resulting in reduced costs.

According to the invention, the downwardly-tiltable section of each grate or milling unit features at least one curved flange, by means of which, when the grate or milling unit is advanced and runs against a countersupport, the tiltable section is pushed upwards into the operational position. Thereby, it is possible to move the tiltable section located behind the rotor into the operational position by simply 10 advancing the grate or milling unit into the housing.

This feature permits designs in which the milling units enclose each rotor extensively, so that in double-rotor crushers or mills, for example, counter-acting implements such as anvils, etc. securely affixed to the housing between the rotors are superfluous. Since the tiltable section of the grate or, rnilling unit no longer projects above the lowest point of the associated rotor, the grate or mining unit can be retracted without hindrance.

It is a fact that DE-AS 19 30 038 reveals a double-rotor hammer crusher, in which the rotors are enclosed by grates, whereby the grates are designed as whole units which are tfitable downwards and outwards. The side housing parts are of multi- tiltable design by means of hinged joints to permit access to the rotors from above. At the same time, however, access to the grates is difficult and they are only exchangeable as a whole unit, resulting is very high maintenance costs.

Preferably rollers are provided on the counter-support to guide the curved flanges of each grate or milling unit, thereby reducing the effort required to advance and retract the grate or milling unit.

It is also preferred that, in the double-rotor design, the tiltable sections of the grate or milling unit are designed to support each other in the operational position. This relieves grinding pressure on the counter-support, so that the latter and the rollers provided thereto can be of a lighter construction.

By way of example, an embodiment of the invention will be described with reference to the accompanying drawings in which:- Fig. 1 is a longitudinal view through a hammer mill according to the invention, which can also be designated as a hammer crusher; Fig. 2 is an enlarged view of part of the tiltable section of the grate or milling units of the hammer mill of Fig. 1; and Fig. 3 is an enlarged view of part of the tiltable sections of the partially-retracted grate or milling is Units.

Referring to the drawings, Fig. I shows a hammer mill comprising a housing 1, in which there are arranged two rotors 2, 3 fitted with a number of hammers 4 which are pivotably-mounted in the rotors on bolts 5. The hammer mill features a material inlet 6 and an outlet 7 for the crushed/milled material, which in the example shown is pneumatically discharged upwards with the aid of a flow of air. During operation, the rotors turn at a high speed in the direction of the arrows x around axes 8, 9. Whereas the material inlet 6 is open, material outlet 7 is provided with grate bars 10, which enclose the rotor 3 in the form of a circular segment and only allow passage of correspondingly comminuted material through the bar gaps. The other sectors of grinding chambers 11, 12 are closed by grinding paths 13 made up of impact bars 14 alternately separated by spacer bars 15.

Such grinding paths are provided at the top between the two rotors 2, 3 where they are more easily accessible, but also underneath the rotors as well, in which location, they can only be serviced and the impact or spacer bars exchanged if they are first moved into a 6 position where they are accessible to maintenance personnel. To do this, the lower grinding paths are attached to side walls 16, 17 which can be retracted frorn the housing 1 and which each externally together with a housing wall 18, 19 form a housing closure. The undersides of the side plates are provided with pairs of rollers 20, which support on rails 21, 22 the grinding units thus formed. The grinding units can be moved in and out of the mill housing 1 by means of suitable moving devices (not illustrated), such as hydraulic cylinder piston units.

The inner-facing part 23 of each grinding path 13 projects upwards beyond the lowest point of the associated rotor 2, 3 by a considerable amount. In order that each milling unit can be retracted from the housing I with the grinding path 13, part 23 of the milling unit which projects upwardly of the fixed rotor parts is designed so that it is downwardly tiltable. As can be seen in particular in Fig. 2, this part comprises curved flanges 24, 25 arranged in pairs onto which the impact bars 14 and spacers 15 aare secured by means of retainers 26. The flanges 24, 25 are tiltably attached to the flanges 16, 17 by hinged joints 27, 28.

In the centre of the mill housing 1 at the bottom between the housing walls is provided a beam 29 on which is arranged a counter-support 30 which interacts with the curved flanges 24, 25. For the purpose of facilitating the movement operations and to guide the flanges 24, 25, the counter-support 30 is fitted with rollers 31, 32. The corresponding connections between the side walls 16, 17 and the sides of the flanges 24, 25 facing them are made by cross-bars 33, 34 and 35, 36. The tiltable section of each n-jlling unit is provided at its top end 37 with bars 38 and 39 respectively, whereby both bars 38, 39 touch and support each other and hence the tiltable sections of the milling units.

As shown in Fig. 3, on retraction of the milling units, the curved flanges 24, 25 ride on the rollers 31, 32 of the counter-support 30, during which with, together with the associated parts 23 they tilt downwards far enough to enable the whole milling unit to be moved horizontally to the outside underneath the rotor 2, 3 arranged above it.

7

Claims

CLAIMS:

A hammer rrill or hammer crusher equipped with at least one rotor fitted with impacting implements and at least one grate or milling unit as counter-acting implement allotted to the rotor or to each rotor and at least partially encircling the rotor and comprising impact bars, grate bars or screens and corresponding retaining side walls, the said grate or milling unit being provided with a guide device having a plurality of roller pairs and rails which allows its movement in an essentidy horizontal direction for withdrawal of the grate or milling unit from the housing, with a device to permit sufficient lowering of that section of the grate or milling unit which is designed to tilt downwards and which, when viewed from the direction of retractior lies behind the vertical sectional plane passing through the rotor axis and projects upwardly ftom the lowest part of the rotor so that, on withdrawal of the grate or milling unit from the rotor, the said tiltable section can swing downwards on hinges connecting it to the fixed part of the grate or mWing unit and pass freely underneath the bottom of the rotor, wherein the downwardly tiltable section of each grate or milling unit features at least one curved flange, with which the tiltable section can be pressed upwards into the operational position by running against a counter- support when the grate or milling unit is advanced.
2.
3.

A hammer mill or hammer crusher according to claim 1, including rollers on the counter-support to guide the curved flanges.

A hammer mill or hammer crusher according to claim 1, wherein, in the double-rotor design, the downwardly tiltable sections of the gate or milling unit are designed to support each other in the operational position.
4. A hammer mill or hammer crusher substantially as hereinbefore described with reference to and as shown in the accompanying drawings.