GB2225545A

GB2225545A - Plan sifting machine

Info

Publication number: GB2225545A
Application number: GB8926077A
Authority: GB
Inventors: Bodo Koos; Wolfgang Kricke; Richard Guenther
Original assignee: Nagema VEB
Current assignee: Nagema VEB
Priority date: 1988-11-18
Filing date: 1989-11-17
Publication date: 1990-06-06
Anticipated expiration: 2009-11-17
Also published as: CH678288A5; DE3935176A1; DD288285A7; GB8926077D0; IT1237043B; IT8948561A1; GB2225545B; IT8948561A0

Description

- 1 1 1 2,2-25545 PLAN SIFTING MACHINE The present invention relates to a

plan sifting machine.

In plan sifting machines, riddles are disposed one above the other in sieve stacks and are tightened together in a frame which is susVend- ed to be capable of free oscillation. For a variety of reasons, it is required to release the tightening. Thereafter, each riddle can be drawn out individually and independently of the one arranged thereabove or therebelow. To achieve this, each riddle is equipped with lateral strips which, in the untightened state of the stack, rest on guide rails. These guide rails are connected at equal spacings with vertical profiles and together with these form riddle ladders. The spacing of the guide rails is such that an air gap exists between the relieved sieves, which permits individual withdrawal of any one of the riddles. The ladders are firmly mounted on a frame of the machine.

During the vertical tightening operation, the riddles are raised one after the other and pressed one against the other after overcomming all air gaps. The lateral strips of the riddles in that case are raised from the guide rails.

For the vertical tightening from above, the pair of ladders is mounted on the frame to be vertically displaceable. During the tightening. operation, the ladders are lowered so that the riddles are laid one upon the other upwardly from below and one after the other, and are then pressed against each other.

The principle disadvantage of these arrangements is that the maximum number of the riddles able to be disposed one above the other is limited. The maximum number is dependent on the overall height of the riddles and the spacing of the riddles in the relieved state.

There is thus a. need to achieve an increase in performance in a -1 plan sifting machine by better utilisation of the available space, by improvement of mass-power ratio and by reduction in the specific energy consumption, in particular by increas ing the maximum number of the riddles that may be able to be disposed in the stack.

According to the present invention there is provided a plan sifting machine comprising a plurality of riddles arranged one above the other in a sifting compartment of the machine, a plurality of riddle ladders to support the riddles in a relieved state free from contact with each other, and tightening means for tightening the riddles together to form a sieve stack, the ladders being divided into pairs of mutually opposite ladder sections.

In a preferred embodiment, the machine comprises riddle ladders for each plan sifting machine compartment for the reception of riddles which, in the state in which they are tightened together, form a sieve stack and in the relieved state rest without mutual contact one among the other on the ladders. The ladders are subdivided into pairs of mutually opposite ladder sections, of which one pair is fast and the remaining pairs are substantially vertically movable, or all pairs are substantially vertically movable. Thus, on tightening of the riddles into a sieve stack, the process of contacting of the riddles one among the other is initiated continuously in sequence anew at each pair of riddle ladder sections, and in reverse during relief of the stack. The disadvantage of a limitation of the maximum number of the riddles able 'to be disposed one above the other in dependence on'the height of the individual riddles, and the spacing between the riddles in the relieved state, is thereby basically eliminated.

In one preferred embodiment, the uppermost Dair of ladder sections is immovable and the remaining pairs of riddle ladder sections are vertically movable in the machine compartment. The movable ladder sections can be guided by way of rollers on guide columns firmly connected with a carrier frame. The minimum and maximum spacing of the ladder sections disposed one above the other is preferably settable in the relieved state by adjustable stop means. The stop means can comprise adjustable abutments firmly connected with a frame. The spacing between the abutments and the lowermost Dair of ladder sections is preferably greater, apart from an air gap between the relieved riddles, than the sum of all air gaps below the relieved riddles which belong to the pair of ladder sections.

An embodiment of the present invention will now be more particular ly described by way of example with reference to the accompanying draw ings, in which:

Fig. 1 is a schematic elevation of part of a machine embodying the invention, with riddles of the machine in a tightened state; and Fig. 2 is a schematic elevation of another part of the machine, with the riddles in a relieved state.

Referring now to the drawings, there is shown part of a plan sift ing machine comprising a plurality of riddles 8 disposed one above the other to form a sieve stack. The machine can include two, four, six or eight sieve stacks, which are each arranged together in a carrier frame 4.

A tentering frame 7, with which adjustable abutments 5 are firmly canta-ected, is dispDsed above a tightening device (not illustrated).

A lower pair of riddle ladder sections or segments 1 is movable 1 1 1 vertically and guided by rollers 2 which are fastened thereto and run on guide columns 3 firmly connected with the frame 4. An upper pair of ladder segments la is rigidly connected with the frame 4. Each ladder segment 1 is loosely connected with the segment la thereabove by way of an adjustableabutment 6.

On actuation of the tightening device arranged below the frame 7, the riddles 8 are raised one after the other upwardly from below. In that case, the air gaps between the riddles 8 are removed and the riddles are brought into contact with each other and no longer rest on support strips 9 of the ladder segments. When spacing between the abutments 5 and the ladder segments 1 has been overcome, as well as the air gaps between the riddles 8 associated with the ladder segments 1, these segments are moved upwardly by the abutments5 in the further course of the tightening operation. Consequently, the process of the bringing together of the riddles 8 associated with the segments 14 is initiated in sequence and continued until the riddles are compressed together in a sieve stack.

Claims

- 5 CLAIMS 1. A plan sifting machine comprising a plurality of r iddles

arranged one above the other in a sifting compartment of the machine, a plurality of riddle ladders to support the riddles in a relieved state free from contact with each other, and tightening means for tightening the riddles together to form a sieve stack, the ladders being divided into pairs of mutually opposite ladder sections.
2. A machine as claimed in claim 1, wherein the ladder sections comprise upper and lower pairs movable in a substantially vertical direction.
3. A machine as claimed in claim 1, wherein the ladder sections comprises an upper pair which is immovable and a lower pair which is movable in a substantially vertical direction.
4. A machine as claimed in either claim 2 or claim 3, wherein each of the movable ladder sections is guided by way of rollers on a guide column secured to a frame of the machine.
5. A machine as claimed in any one of claims 2 to 4, comprising adjustable strip means to determine the spacing of the upper and lower pairs of ladder sections in the relieved state of the riddles.
6. A machine as claimed in claim 5, the stop means comprising adjustable abutments carried by a frame.
7.

A vj?,chi..ne as clainied, in clairR 6, wherein abutments are co-operable with the lower pair of ladder sections and in the relieved state of the riddles the abutments are spaced from the lower pair of ladder sections by an amount which is greater than the sum of air gaps below the riddles associated with that pair.
8. A machine substantially as hereinbefore described with reference to the accompanying drawings.

1 ne Th Wt, Published 1990 at The Patent Office. State House. 66 71 High I-Io2born. London WCIR 4TP. Further copies maybe obtai dfrom eP ertOMCC Sales Branch. St Maly Cray. Orpington. Kent BR5 3RD- Printed by Mult-plex techniques ltd. St Mary Cray. Kent- COr- 1 8-'