GB2144342A

GB2144342A - Screen and frame assembly for hammer mill

Info

Publication number: GB2144342A
Application number: GB08417926A
Authority: GB
Inventors: Graham Calderbank; Richard Godfrey Ingleton
Original assignee: INGLETON ENGINEERING Ltd E
Current assignee: INGLETON ENGINEERING Ltd E
Priority date: 1983-07-28
Filing date: 1984-07-13
Publication date: 1985-03-06
Also published as: GB8417926D0; GB2144342B; GB8320384D0

Abstract

The perforated screen plate 12 can easily be renewed when worn since the frame includes inner and outer frame elements 20 and 22 between which the perforated screen plate (12) is sandwiched. <IMAGE>

Description

SPECIFICATION Screen and frame assembly for hammer mill The invention relates to screens for hammer mills of the kind used for grinding cereals and other commodities for the production of animal feeding stuffs.

Hammer mills of the kind referred to include a horizontally disposed rotor having a plurality of flail-type beaters, the rotor being driven at high speed within a generally cylindrical chamber partly defined by perforated plates (hereinafter referred to as screen plates). The mill has a heavy cast iron or fabricated steel body with an aperture in its top through which the cereals or other commodities to be ground can be fed to fall through a space between upper portions of oppositely disposed screen plates. Material which has passed through the screen plates is entrained in a flow of air passing around the outside of the screen plates and passes through an outlet in the underside of the mill body.

The perforated screen plates are mounted in screen frames which can be slid into position in the mill body, or removed therefrom, when a blanking plate has been removed. (This is facilitated by the provision of handles at the outer ends of the screen frames). In this way the perforated screen plates can be renewed when worn. Heretofore, it has been usual for the screen plates to be riveted or bolted in position in the screen frames.

Consequently, it has taken a certain amount of time and skill to effect such a renewal of the screen plates. The object of the invention is to simplify the operation to at least some extent.

According to one aspect of the invention, there is provided an assembly of a screen plate and a screen frame for a hammer mill, the frame including inner and outer frame elements between which the perforated screen plate is sandwiched. The outer frame element will preferably include partcircular end plates, the perforated screen plate being seated in contact with curved surfaces of said end plates. The inner frame element may also include part circular end plates, the arrangement being such that when the frame elements have been brought together to make the perforated screen plate captive between them they can be secured together by bolts which extend through aligned holes in the part-circular end plates of the elements.Longitudinal and arcuate bracing members may be welded in position in the outer frame element so that the perforated screen plate is adequately supported along its entire length. Longitudinal side frame members of the inner frame element may be of a cross section providing slide surfaces for the slide mounting of the assembly in the mill. They may also provide seating surfaces for respective pre-formed lip portions formed along the longitudinal side edges of the perforated screen plate.

According to a further aspect of the invention, there is provided a hammer mill having a generally cylindrical chamber partly defined by screen plates each of which forms a part of a screen plate and screen frame assembly as referred to above.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a perspective view of a hammer mill embodying the invention, showing the perforated screen plates, mounted in screen frames, being removed for renewal, and Figure 2 is an exploded view illustrating the construction of a screen plate/screen frame assembly.

Referring now to Fig. 1 of the drawings, the hammer mill there illustrated includes a horizontally disposed rotor (not shown) having a plurality of flail-type beaters (not shown), the rotor being capable of being driven at high speed by an electric motor 10 within a generally cylindrical chamber partly defined by perforated screen plates 12.

The mill has a heavy cast iron or fabricated steel body 14 within which screen frames 16 carrying the screen plates are slidably mounted. In Fig. 1 the screen frames are shown partly withdrawn from the body for replacement of the screen plates. The mill body has an aperture 18 in its top through which the cereals to be ground can be fed to fall through a space between upper portions of oppositely disposed screen frame and plate assemblies. In use of the mill, material which has passed through the screen plates is entrained in a flow of air passing around the outside of the screen plates and passes through an outlet (not shown) in the underside of the mill body.

Referring now to Fig. 2, there is there illustrated the construction of an assembly of a screen plate and a screen frame whereby, in a hammer mill embodying the invention, the screen plates can be renewed very quickly and easily when worn. As shown, the assembly includes inner and outer frame elements 20 and 22 between which a preformed perforated screen plate 12 is sandwiched.

The perforated screen plate, which has been rolled to a required curvature, is placed in position so that it is snugly seated in contact with curved surfaces 24 of part circular end plates 26 of the outer frame element. Spaced longitudinal and arcuate bracing members 28 and 30 are welded in position in the outer frame element as shown, so that the perforated screen plate is adequately supported along its entire length. Longitudinal side frame members 32 of the inner frame element are of a cross section providing slide surfaces for the slide mounting of the assembly in the mill and also providing seating surfaces for respective pre-formed lip portions 34 formed along the longitudinal side edges of the perforated screen plate 12. When the frame elements have been brought together to make the screen plate captive, the inner and outer frame elements are secured together by bolts 36 which extend through aligned holes in the part-circular end plates of the elements.

It has been found that by using screen plate/ screen frame assemblies as just described the operation of replacing worn screen plates is very sim ple and can be performed by unskilled workers.

However, various modifications may be made. For example, the manner in which the inner and outer frame elements are secured together may be varied in numerous ways.

Claims

1. An assembly of a screen plate and a screen frame for a hammer mill, the frame including inner and outer frame elements between which the perforated screen plate is sandwiched.

2. An assembly according to claim 1, in which the outer frame element includes part-circular end plates, the perforated screen plate being seated in contact with curved surfaces of said end plates.

3. An assembly according to claim 2, in which the inner frame element also includes part-circular end plates, the arrangement being such that when the frame elements have been brought together to make the perforated screen plate captive between them they can be secured together by bolts which extend through aligned holes in the part-circular end plates of the elements.

4. An assembly according to any one of the preceding claims, in which longitudinal and ar cuate bracing members are welded in position in the outer frame element so that the perforated screen plate is adequately supported along its entire length.

5. An assembly according to any one of the preceding claims, in which longitudinal side frame members of the inner frame element are of a cross section providing slide surfaces for the slide mounting of the assembly in the mill.

6. An assembly according to any one of the preceding claims, in which longitudinal side frame members of the inner frame element provide seating surfaces for respective pre-formed lip portions formed along the longitudinal side edges of the perforated screen plate.

7. An assembly of a screen plate and a screen frame for a hammer mill, substantially as hereinbefore described with reference to and as illustrated by the accompanying drawings.

8. A hammer mill having a generally cylindrical chamber partly defined by screen plates each of which forms a part of a screen plate and screen frame assembly according to any one of the preceding claims.