GB2162458A

GB2162458A - Machinery for compressing materials with particular characteristics of compression

Info

Publication number: GB2162458A
Application number: GB08402308A
Authority: GB
Inventors: John Kenneth Creffield; John George Pape
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-01-28
Filing date: 1984-01-28
Publication date: 1986-02-05
Also published as: GB8402308D0

Abstract

Apparatus for compressing a material in which the resistance to compression increases substantially as the volume is decreased, e.g. straw, comprises a pair of jaws for compressing the material and drive means to effect relative movement of the jaws. The mechanical advantage of the drive with respect to the moving jaw progressively increases throughout compression of the material. This is achieved by using a toggle linkage driven by a hydraulic cylinder assembly, or a link driven by a cam or crank.

Description

SPECIFICATION Improvements in or relating to machinery for compressing materials with particular characteristics of compression The invention relates to machinery such as presses or compactors or the like used for decreasing the volume of particular materials, where a characteristic of these materials is that their resistance to compression increases substantially as their volume is decreased.

The object of the invention is to make economic reductions in the energy required to compress these materials. Most immediately, therefore, the invention is concerned with those materials where the resistance to compression is markedly in excess of being directly proportional to the corresponding decrease in volume. The ratio, therefore, of the initial work requirement to the terminal work requirement during compression is particularly high.

However, if in the future, the cost of energy becomes disproportionately high, then it is foreseeable that materials with a less score ratio of said work requirement can be economically compressed in the manner to be described.

Therefore, the invention is concerned with the compression of materials where the characteristics are such that economical savings in energy can be made when the principles of the invention are applied to the machinery used to compress them.

Examples of materials having the characteristic of said most concern are to be found in low value agricultural and industrial by-products, often of a fibrous nature, such as straw, and industrial and domestic waste.

Such materials are normally mixed with a proportion of air and often moisture within the overall bulk of their normally processed state.

Initial compression of such combinations of fluid and solid can require a relatively low effort, which magnifies considerably as compression progresses.

The invention is concerned with machinery of a relatively simple design for applications where the additional complexity of incorporating a flywheel with associated mechanism or comparable means of storing energy is not justified. A typical example of such relatively simple machinery is a hydraulically operated press having a sliding ram to effect compression.

In such machinery where a ram or rams or equivalent mechanism is used to compress aforesaid materials the power requirements are dictated by the effort to overcome the resistance of the said material towards the completion of the stroke of said ram(s). This means that because of the aforesaid characteristic of the said material under compression that a comparatively large prime mover has to be used to power said ram(s) and a large proportion of this power is consequently wasted during the initial part of the compression stroke.

The object of the invention is to minimise the total power requirements by incorporating into the design of the machine means to equate the thrust of said ram or rams or the like to that demanded by the compressive resistance of said material throughout the said compression stroke.

Such means to equate thrust to requirement will hereinafter be referred to as the equative means.

With the high cost of energy in the world at the present time this principle can result in substantial reductions in the running costs of such machinery.

Of particular relevance is where the material being compressed is to be used to replace more conventional fuels in stoves or furnaces.

The lower the preparation costs of these materials then the more attractive they can be as alternative fuels.

By way of an example of a machine embodying said 'equative means', this can be illustrated by considering the aforesaid hydraulic press. Such a machine comprising, in a simple form, a pair of opposed jaws or like means, related to effect compression to the material along one axis. Conveniently, one jaw being fixed and the second forming the face of a slideable moving ram or like means. Said slideable ram being caused to move effectively by the extension of a piston rod from a hydraulic cylinder assembly. These elements being conveniently attached either directly or indirectly to a static frame or like mounting and support structure.

Said equative means comprising a mechanism interposed between the connection of the moving part of the said hydraulic cylinder assembly with the said slideably moving ram.

Said mechanism comprising a lever and link assembly acting to effect a toggle action to the motion of said slideably moving ram, such that the mechanical advantage of the said hydraulic cylinder assembly with respect to the said slideably moving ram progressively increases, throughout the said compression stroke. The ratio of the said mechanical advantage at any point along the stroke of said slideably moving ram being such as to at least approximate satisfactorily to give the thrust required to said hydraulic cylinder assembly to overcome the compressive resistance of the material at that particular point.

In a preferred configuration the lever of the said interposed mechanism would be in the form of a bell-crank or similarly effective element, such that the axis of the said hydraulic cylinder assembly lies below or behind as appropriate substantially in the same plane as the line of action between said pair of opposed jaws.

Alternative configurations would be to utilise either a hydraulic or electric motor in place of the said hydraulic cylinder assembly, to drive a crank or cam to act in place of the said lever of the interposed mechanism.

In the case of the cam the aforesaid link of the interposed mechanism would be substituted by a follower or like means bearing against the effective track of the cam and connected directly or indirectly to the aforesaid slideably moving ram. An advantage of the cam is that its said effective track could normally be more precisely matched to suit the compressive characteristics of the material to be compressed.

Other alternative embodiments envisaged include a multiplicity of motive power units where the power from each is introduced progressively through the said compression stroke as the power requirement increases.

Alternatively, there could be a multiplicity of power supplies to a single motive power unit, as with a low and high pressure hydraulic circuit arrangement. A switch being made from the low to the high pressure supply at a suitable point during the said compression stroke.

A combination could be made of these last two alternatives comprising multiple power units with multiple power supplies where this was justified by the compressive characteristics of the material to be compressed and the comparable costs of energy.

Claims

1. Apparatus for compressing a material comprising a pair of jaws movable relative one to another for compressing the material when located between the jaws, a power source and drive means for transmitting power from the source to effect relative movement of the jaws, the arrangement being such that the mechanical advantage of the drive means progressively increases throughout compression of the material in relation to the compressive characteristics of the material being compressed.

2. Apparatus as claimed in claim 1 wherein the drive means comprises a first member mounted for arcuate movement on an axis, a second member adapted to engage with the first member for transmitting drive from the first member and means driven from the power source for effecting arcuate movement of the first member on the axis.

3. Apparatus as claimed in claim 2 wherein the second member is elongate, an end portion of which is adapted to engage with the first member and a remote end portion of which is adapted to be engaged with one of the jaws.

4. Apparatus as claimed in claim 3 wherein the first member comprises a crank.

5. Apparatus as claimed in claim 3 wherein the first member comprises a cam a surface of which is adapted to engage with the second member.

6. Apparatus as claimed in claim 3 wherein the first member comprises a lever which is pivotally connected with the said end portion of the second member at a location spaced from said axis.

7. Apparatus as claimed in claim 6 wherein the lever comprises a portion which extends from the said axis in a direction away from said pivotal connection, the said portion being pivotally connected to the drive means.

8. Apparatus as claimed in claim 1 wherein there is provided a plurality of drive means and control means for controlling power from the power source whereby thrust is transmitted progressively by the drive means during compression of the material.

9. Apparatus as claimed in claim 1 wherein there is provided a plurality of power sources and control means for controlling the sources whereby thrust is transmitted progressively by the drive means during compression of the material.

10. Apparatus as claimed in claim 1 wherein there is provided a plurality of power sources, a plurality of drive means and control means for controlling the sources and drive means whereby thrust is transmitted progressively by the drive means during compression of the material.

11. Apparatus for compressing a material substantially as hereinbefore described.