The invention relates to a quadratic press advantage¬ ously applicable for uniformly compressing under high pressure loose substances, mainly fibrous vegetable materials . In practice, when starting from some coarse fibrous materials, high-density compacted agglomerations are to be obtained, usually several presses are built together to perform series of pressing operations in succession.

Figure 1 shows the functioning of a known two-piston press.

Piston Dl advancing in the space of cylinder HI performs the task of pre-pressing, then the material is compacted by piston D2 forcing the pre-compressed material into the space of cylinder H2. The applied pressure, however, does not propagate uniformly in the material under compression, vaults being produced along the dotted line shown in the figure. These vaults give rise to strong internal friction in the material subject to compression whereby the efficiency of compacting is reduced.

Similar problems arise when fibrous agricultural substances are compressed. Biomasses can be compressed by known presses into solid compact packages only after grinding and chipping. When a biomass predominantly consisting of fibrous vegetable substances has to be split up ana ground, the resulting costs of processing

including trasπportation and drying become excessively high.

Along with recent technological developments, constructions are getting obtainable by which the operation of pressing is performed from several directions simultaneously, highly increasing thereby the efficiency of compacting. These appliances, however, suffer from a number of deficiencies.

So, e.g. the method of compacting metal powders, described in GB 871 373, just as in DE 29 03 690, permit but limited displacement of particles within pressings, rendering these presses unsuitable for balling loose fibrous substances.

The- geometry of two-dimensional (quadratic) compression is completely cleared by GB 2 159 456 describing the details of the compressor, the mechanical driving mechanism proposed for the latter fails to accomplish uniform motion of pressing dies with respect to each other, so thet they tend to get wedged in while moving. The present invention is aimed at eliminating _. the deficiencies mentioned, by proposing an improved quadratic press perfectly meeting both the geometrical and kinematical requirements and being capable of compressing loose fibrous vegetable material into uni- form highly compacted blocks.

Thus, the invention relates to the improvement of a quadratic press to facilitate baling loose materials, mainly fibrous vegetable substances, provided with press blocks confining a pressure space with their planar surfaces, and with a press stand guiding the press blocks with its planar surfaces, and having a set of special features, such as each of said press blocks being provided with two closing surfaces with a sum of 360 of sealing angles enclosed by said surfaces, and the guiding surfaces of the press stand being

arranged so as to be in a position perpendicular to the bisectors of said sealing angles, further, said press stand being provided, parallel to the guiding surfaces, with surfaces preventing angular displacement of said press blocks, and the press having hydraulic power cylinders attached to the press stand and directly moving the press blocks, the operation of said hydraulic power cylinders being controlled by a slide valve causing the four cylinders, to move forward or backward simultaneously .

In conformity with the requirement of low mechanical weight and small machine size raised by mobile agri¬ cultural applications, the invention comprises an improved design of nydraulic cylinders, the latter being arranged within the movable blocks.

Some possible variants of the principle of the invention, a few embodiments thereof along with their operation are described here below, with reference to the attached drawings. Figure 2 shows the arrangement of a square-shaped quadratic press complying with the invention. Figure 3 shows the arrangement of a triangular-shaped quadratic press. Figure 4 shows a quadratic press of hexagonal arrange¬ ment . Figure 5 shows the same having parallel sides. Figure 6 shows a self-a justing hydraulic drive of press blocks . Figures 7 and 8 illustrate longitudinal and cross-sections of an embodiment of a press. Figures 9 and 10 show longitudinal and cross-sections of another embodiment of a press combined with a chopping mechanism. According to Figure 2, each of press blocks (Tl, T2, 3 , T ) confining pressure space 1 has two planar

sealing surfaces (Z1-Z2, Z2-Z3, Z3-Z4, Z4-Z1), each pair of adjacent surfaces enclosing an angle of 90 . Sum of the four 90° closing angles is: al + a2 + a3 + a4 = 360°, i.e. the four sealing surfaces Zl - Z2, Z2 - Z3, Z3 - Z4, Z4 - Zl, bearing against each other by pairs, confine pressure space 1. Guiding surfaces VI, V2, V3 , V4 being arranged so as to be perpendicular to bisectors fl, f2, f3 , f4 of sealing angles al, a2, a3, a4, and causing press blocks Tl, T2, T3, T4, to slide along guiding surfaces VI, V2 , V3 , V4, displace¬ ments el, e2, e , e4 of press edges El, E2, E3, E4 take place perpendicular to bisectors fl, f2, f3, f4, so that the sealed state of pressure space 1 is continuously maintained by closing surfaces Zl, Z2, Z3 ₃ Z4 during the sliding movement of press-blocks Tl, T2, T3, T4. Simultaneously with the progress of the pressing process, pressure space 1 is steadily narrowed down, and press blocks Tl, T2, T3, T4 are subject to an increasing wedging-up torque. Reliving surfaces 51, B2, B3, B4 provided parallel to guiding surfaces VI, V2, V3, V4 however, bear against press stand 2 and prevent wedging- up of press blocks Tl, T2, T3, T4 from, due to their angular displacement.

For better understanding, Figures 3, 4 and 5 illustrate graphically a few possible embodiments of the principle utilized in the quadratic press, omitting the latter symbols from the drawings.

The triangular quadratic press geometry of Figure

3 and the hexagonal quadratic press geometry of Figure

4 are suitable for producing pressings of regular polyginal cross-sectional areas.

The quadratic press geometry of Figure 5 is aimed at producing parallel-sided brick-shape pressings.

As it is apparent from Figures 2, 3, 4 and 5, pressure space 1 is fully surrounded by press stand

2, i.e. a closed press stand of arbitrary thickness can be formed around pressure space 1. For increasing the pressing force, however, in addition to making press stand 2 sufficiently strong, the high-power drive of press blocks Tl, T2, T3, T4 has also to be solved.

Figure 6 illustrates direct hydraulic drive of the quadratic press complying with the invention.

Press blocks Tl, T2, T3, T4 are directly driven by hydraulic power cylinders Ml, M2 , M3 , M4 mounted on press stand 2. Operation of the press is controlled by a simple slide valve 3. The four power cylinders are simultaneously connected to pressure and, after pressing, to reverse flow through slide valve 3. Synchronizing of the movement of individual power cylinders Ml, M2 , M3 , M4 is provided for by way of self- regulation by press blocks Tl, T2, T3, T4 themselves. Use of a costly synchronizing gear is not only super¬ fluous, but it is definitely harmful.

Figures 7 and 8 illustrate a quadratic press designed for compacting wet biomasses.

Prior to pressing, pressing space 1 has to be shut off by pushing together closing plates 5 and 6 by using pneumatic power cylinders 7, 8 and 9. By doing so, the wet biomass is prevented from flowing out of pressing space 1 'during the pressing operation. Pressing plates 10, 11, 12, 13 of press blocks Tl, T2, T3, T4, however, just as closing plates 4, 5 and 6 are provided with small-diameter (1 to 4 mm) through holes 14, 15. During pressing, most of the moisture escapes through said holes 14, 15.

For adjusting the quadratic press into its working position, telescopic legs 16 held together by bracing roαs, are provided by means of which the press is adjusted to the hieght required by the working _ process .

In other respects, the geometry and movements of

press blocks Tl, T2, T3, T4 are identical with those described along with Figure 2, while the operation of the hydraulic drive is similar to that of Figure 6. The operating clearance of sliding plates 17 of relieving surfaces Bl, B2, B3, B4 preventing the wedging-iπ of press blocks Tl , T2, T3, T4 are adjustable by means of screws 19 bearing on distance pieces 18. Figures 9 and 10 illustrate a quadratic press performing the baling of dry biomasses. Since the fibres of dry vegetable substances do not elongate during pressing, there is no need to shut off pressing space 1 either from above or from below, so that the air from the pressings can leave freely in these directions.

While rather high (600 to 1000 bar) pressures are required to obtain solid-compacted pressings from dry fibrous substances, the size and dead weight of pressing machines must not be excessive, since they have to per¬ mit their transport on agricultural vehicles (trailers towed by tractors) during operation. Low weight of a press combined with the possibility of applying high pressures is provided by arranging the hydraulic cylinders within the moving pressing blocks. E.g. hydraulic power cylinder 21 fixed into hollow pressing block 20 by screws 23 is displaced, while support piston 22, fixed by screws 24 and bearing against press stand segment 25 through an interposed resilient seating ring 36, remains in stationary position. By this arrangement there is no need to-provide a cutout in press stand segment 25 for passing through the piston rod through the latter, so that it can be made of high-strength sectional steel of continuous cross-sectional area. Hydraulic power cylinder 21 fixed in hollow press block 20 can follow, in a self-adjusting way, the elastic deformation of guide flanges through interposed resilient sealing rings 36, preventing cccurence of jamming or

seizing .

The fibres of some vegetable substances to be baled being long (e.g. sunflower- or cornstalks), severel (e.g. three as shown in Figure 9) closed frames KI, K2, K3 are heaped up to form a row of frames, using ^• spacer rings 30 between individual frames and held to¬ gether by screws 35. In course of the process, the long rod-like pressing formed in pressing space 1 is cut into shorter pieces by means of cutting blades 33, 34 moved by hydraulic power cylinders 31, 32 mounted into the row of frames KI, K2, K3. The biomass blocks thus obtained can be transported and stored efficiently.

The most outstanding advantage of the quadratic press specified herein is its suitability for the achieve- ment of substantial volume reductions, besides ensuring uniform compacting over the entire cross-sectional area.

The press blocks automatically synchronize each other's motion during the pressing operation, so that no separate synchronizing gear is required by the hydraulic or pneumatic drive.

With the arrangement where the hydraulic power cylinders are accomodated within the moved press blocks, extremely high pressing torques can be produced.

Providing the press blocks with the pressing plates having through holes and employing similar through holes in the plates serving; for sealing the pressing space, it can be achieved that when compacting moist substances, considerable proportion of gases and fluids will escape from the pressing.

In the course of pressing dry fibrous materials into solid-compact products, by cutting them into shorter pieces, efficiently transportable and storable ^p ressings can be obtained.