FI77686C - Feed screw for piece peat / granulator. - Google Patents

Description

77686

The invention relates to a peat / granulation machine feed screw with which peat is compressed along a feed pipe towards a matrix plate or other nozzle member to extrude pulp through the nozzle member to provide a compact.

10 Current production methods for peat and also for pellets are usually based on drying the peat in the field from which it was extracted. The work steps have been combined so that the same machine simultaneously removes, cultivates and spreads the raw peat on the field. The machines are used to form 15 extracts of raw peat, which are intended to be applied as evenly as possible to the field. When the surface of the extrudates dries, it becomes hard and water-repellent. The entire production is dominated by the effort to efficiently dry the extrudates. Matrix slab-based shaping machines are mainly used to produce a compact 20 smaller than normal peat size. Due to the smaller diameter of the compact, it dries faster than normal lump peat. The typical diameter of peat extrudates is 50 ... 80 mm and that of pellets 10. ..30 mm.

In all known machines, the peat is pressed with a screw in the supply pipe to such a high pressure that it exudes through the nozzle members as a compact. The nozzle members can be, for example, holes in the matrix plate or transverse pipe nozzles connected to the cone of the peat machine. This compression step takes up a substantial part of the power used by the entire machine, for example the peat peat machine.

In a machine with a disc mill, the disc lifts the raw peat from the swamp and throws it into the feed pipe. Part of the peat-35 jet impinges perpendicular to the screw axis and is left to slow down the mass feed.

One notable problem with current machines is corrosion. This occurs in the feed screw in particular on both sides of the thread, 2 77686 in which the peat mass is packed immobile.

The object of the present invention is to provide an advantageous feed screw structure which increases the output and reduces the power requirement 5 and the susceptibility to corrosion. The main features of the invention are clear from the appended claim 1. The feed screw according to the invention causes less longitudinal resistance than before, because the peat is better able to slide longitudinally along the screw slot and not against the stationary peat mass packed at the root 10. Corrosion is also considerably less, as less peat is packed onto the surface of the pipe than before. These features can still be considerably emphasized by the means set out in claims 2, 3 and 4. The A-shaped profile is the most economically advantageous from a manufacturing point of view, but the rounded profile achieves the lowest frictional resistance.

The embodiment according to claim 4 enables optimal treatment of peat along the entire length of the pipe. In practice, it has been found that the effective gut area is reduced in any case at the end of the screw by the peat packed in the gut. In this case, the sliding also takes place against this packaged peat. With the screw adapted to this natural shape, the sliding takes place against the metal-25 surface of the screw itself, whereby the friction is lower than before.

The embodiment according to claim 5 improves the operation of the screw at the initial end. This is especially useful if the disc is placed close to the screw. The conical front portion of the screw 30 turns the peat jet inside the screw tube, increasing the output compared to previous screws.

In the following, the invention is illustrated by the accompanying figures, which show some embodiments of the invention.

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Figure 1 shows a granulating machine with a disc mill. Figure 2 shows a side view of the feed screw

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Figure 3 shows a longitudinal cross-section at Figure 2

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Fig. 4 shows another embodiment of the feed screw 5 The front part of the granulating machine consists of a disc mill which throws the peat removed from the bog into the feed pipe 3. From this the peat is pressed against

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The feed screw 3 consists of a thread 4 placed around the shaft tube, Fig. 2. The thread 4 is made of two threaded plate strips 5 and 6 welded diagonally to each other, welded to the shaft, Fig. 3. This A-profile has been found in practical experiments to pack previous screw designs on the bottom of the slot. less peat mass.

Figure 4 shows a screw with an initial cone 9 and a variable thread profile. The initial cone 9 is fitted at the disc-20 cutter, whereby the initial cone 9 turns the peat jet parallel to the feed screw and into the feed pipe 2. In the embodiment of Figure 4, the initial end 7 of the screw has a standard 2-ended thread. At the end 8 there is a preferred variable profile and thus variable slotted thread. The reduction of the slot 25 at the end of the screw 8 is intended to correspond to the natural reduction of the flow cross-section during the compression of the peat, whereby the peat slides to the end of the screw, up to the matrix plate against the metal surface of the screw.

The screw can also be coated with known coatings to further reduce friction. In this case, the full benefits are obtained, because the surface of the screw can be used more efficiently than before.

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Claims (5)

A peat (granulation machine feed screw (3) for pressing peat 5 along a feed pipe (2) towards a matrix plate (1) or other nozzle member to extrude pulp through the nozzle member to produce a compact, characterized in that the screw (3) has at least part of the screw length of the profile from the root widened. 10 Feed screw (3) according to Claim 1, characterized in that the profile of the thread (4) is substantially A-shaped. Feed screw (3) according to Claim 1 or 2, characterized in that the profile of the thread (4) is rounded at the root in the direction of the axis of the screw (3). Feed screw (3) according to Claim 1, 2 or 3, characterized in that the profile of the thread (4) is adapted to increase, i.e. to decrease, the area of the slot towards the end of the screw (3). 4 77686 Feed screw (3) according to Claim 1, 2, 3 or 4, in particular in a machine with a disc mill, characterized in that the initial part of the screw (3) has a cone (9) at the disc, which is adapted to reverse the peat flow from the screw (3). in the direction of the axis.