DE29606641U1 - Hollow roller for pelleting plant material - Google Patents

Description

DESCRIPTION Hollow roller for pelletizing plant material

The invention relates to a hollow roller for pelletizing plant material, in particular stalk material, into pourable pressed products, the cylinder part of which is profiled like a tooth on the outside, with a row of conical bores arranged in each tooth base, which open into the interior of the hollow roller.

Such a pelletizing device is known from US-A 4 824 352. There, two such hollow rollers engage with each other like teeth. They receive the material to be compacted from a storage container via a screw, which then enters the inlet gusset between the two hollow rollers. The teeth engaging in the respective tooth gap compact the material and guide it through the radial holes into the interior of the hollow roller. On the way there, the material is compacted into a respective strand, which is broken off in the interior of the hollow roller.

The problem with the previously known pelletizing device is that sufficient throughput of the material to be pelletized cannot be achieved and the pelletizing device tends to block quickly.

The subject matter of WO 93/22132 does indeed prevent blocking of the pelletizing hollow rollers and achieve a high throughput of the material to be pelletized. However, in this previously known arrangement, the individual hollow roller consists of a large number of radially arranged and spaced apart webs, which must be connected with flanges on their narrow front sides. The material to be pelletized is conveyed through the shafts between the webs and to

combustible heating elements. However, the large number of webs and their fastening results in high costs, which hinders the economical use of the previously known pelletizing device.

The invention is therefore based on the object of developing a hollow roller for pelletizing plant material, in particular stalk material, which avoids the disadvantages of the previously known arrangements, can be produced inexpensively and allows a high degree of efficiency to be achieved with regard to a high material throughput with optimal compaction while avoiding blockages.

Based on US-A 4 824 352, the invention consists in that the bores have a conical cross-section that widens towards the interior and the material webs located in the tooth base between the bores are convex.

The invention therefore takes the opposite approach to the teaching of US-A 4 824 352. There, the holes are also conical; however, they narrow from the outside to the inside and thus lead to excessive accumulation of the material to be compacted, resulting in rapid blockage.

In the invention, the holes are widened inwards in a radial direction. This is achieved by initially making the holes cylindrical. A reamer or a similar tool with an adjustable diameter is then inserted into the hole, which causes the holes to widen when moved radially from the outside to the inside.

The conicity can be relatively small. In one example of the invention, a 12 mm bore expands to 12.15 mm over a length of approx. 150 mm

Diameter. This means a conicity of 0.05%. It is surprising that such a small conicity is enough to prevent the compacted strand from blocking.

It is crucial for the invention that the material reaching the tooth base does not accumulate before it is compressed in the radial bores. In US-A 4 824 352, such accumulation is virtually

&iacgr;&ogr; is caused because the tooth base and the web area between the holes are flat. However, if the material webs are curved convexly, no material can build up on them.

In one embodiment of the invention, it is provided that the convex curvatures of the material webs are formed by a ball milling cutter guided in an arc along the tooth base from hole to hole. This ball milling cutter preferably has a diameter corresponding to the width of the tooth base. It is guided in an arc so that on the one hand it gives the inlet cross-section of the individual hole a dome shape and on the other hand, when moving to the next hole, it mills off the free end faces of the material webs located between the holes to form the convex curvature.

Furthermore, in accordance with the invention, the individual bore in the tooth base is provided with a bevel of e.g. 60°.

The hollow roller according to the invention has a large number of rows of holes on its circumference. It has proven to be advantageous if the adjacent rows of holes are arranged offset from one another. In particular, it is recommended that the offset be half a division of the hole spacing.

This measure has the advantage that the material to be pressed that enters the inlet gusset is well distributed into the individual rows of holes and that the strands released in the interior of the individual hollow rollers are not released in radial planes one behind the other, but offset from one another, which makes it easier to break off the strands.

The result of this measure is that a hole at the end of the row has a greater distance from the front of the cylinder part than the other edge hole in the same row. To this end, the invention recommends that between the last hole and the front end of the tooth base, an outlet is provided that rises diagonally from the tooth base and widens, if necessary with a concave, groove-shaped base. A blockage of material should also be avoided at this point.

As part of an independent invention, the invention discloses a special form of hollow roller, according to which a hollow cylinder insert is inserted into the interior of the hollow roller, which has an increased wall thickness of the cylinder part and has aligned holes that widen conically inwards. It proves to be advantageous if the hollow cylinder insert is made of plastic, because it can then be manufactured inexpensively.

This measure of the invention is of independent importance because it does not matter in what form the radial holes or openings are formed. The hollow cylinder insert has the effect that the time in which the material passes through the cylinder part of the hollow roller is extended at the same circumferential speed. This also reduces the effect of the compaction pressure and the temperature

extended, which leads to an improved quality of the granulate. In this way, it is also possible to use plant material with a higher initial moisture content, because the extended compaction time eliminates any excess moisture.

In order to supply sufficient heat to the individual radial bores, the cylinder part of the hollow roller has a large number of axially parallel bores between the radial rows of bores for passing a heating medium through. Such a measure has already become known from WO 93/22132. However, the bores are located in the individual webs, whereas the subject matter of the invention provides a closed annular cylinder part that has both the radial and the axially parallel bores and can thus be manufactured more cheaply.

Finally, the subject matter of the invention is a measure according to claim 10, which is to be regarded as a subsidiary claim.

This claim 10 no longer assumes that radial bores are provided in the cylinder part, but that instead radially extending openings are provided as narrow, possibly trapezoidal or wave-shaped shafts with an inwardly widening cross-section.

Such shafts with a wedge-shaped extension can best be produced in accordance with the invention using electrodes with a cross-section that are adapted to the hollow cylinder and that electrochemically remove material from the cylinder part of the hollow cylinder. Experience has shown that the higher the current intensity, the more intensive this material removal is. For this purpose, salt water is passed through the electrode, which flows to the free front side of the electrode and acts against the metal there. This salt water then flows through the

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forming gap along the outer surface of the electrode.

These and other measures of the invention are shown schematically and by way of example in the drawing. Show:

figure

figure

15 Figure

a schematic side view of a pelletizing device;

a plan view of the cylinder part of a hollow roller with several rows of holes;

a cross-section along the line IH-III through the cylinder part according to Figure 2;

Figures 4 and 5 : Radial sections through the two

End areas of the tooth base of a row of holes;

Figure 6 : a partial side view of a

Cylinder part with a
Hollow cylinder insert and

Figure 7 : a partial plan view of a cylinder part

(in reduced form) according to Figure 2 with wave-shaped openings).

The embodiment shown in Figure 1 is intended to show the arrangement of a hollow roller (2) in a pelletizing device (1). The plant material to be compacted, in particular stalk material, is introduced through the material feed (3) into the inlet gusset between the two hollow rollers (2). The cylinder parts (4) of the hollow rollers (2) are provided on the circumference with a tooth-like

Profiling (7). This means that the individual tooth (8) of one hollow roller, which extends parallel to the hollow roller axis, is inserted into the associated tooth base

(9) of the other hollow roller (2). 5

Radial holes (10) extend from these tooth bases (9) inwards to an interior (5) of the individual hollow roller (2). Through these radial holes

(10) the tooth base (9) is guided and guided by the

The material compacted by the engaging tooth (8) is compacted to form a strand. Many revolutions of the hollow roller (2) are required until the individual strand section formed in the tooth base (9) reaches the interior (5) and is broken off there from time to time by a scraper (6). The broken off strand passes through the interior (5) which is open at the front to the outside.

The embodiments of Figures 2 and 3 show that the individual cylinder part (4) has a number of radial holes in rows. It is expedient if the individual rows of holes are offset from one another, with Figure 2 showing that the offset corresponds to half a division of the hole spacing. This means that at the end of each row of holes the last radial hole (10) is further away from the front edge of the cylinder part (4) than the other last hole in the same row. In order to prevent this greater distance caused by the offset from causing the material to accumulate, the invention provides a sloping outlet (17) (see also Figure 5), which can even be designed in the form of a concave groove (18) and has the task of allowing the material that reaches the area of this outlet (17) to slide easily into the adjacent radial hole (10).

Figure 3 shows the unique course of the individual radial bore (10) that is essential according to the invention. First of all, it should be noted that the tooth base (9) has the spatial shape of a milled groove that is prismatic in cross section. The radial bores (10) are then made in this groove-shaped tooth base (9) at the desired distance. According to the teaching of the invention, these bores (10) should have a conicity (15) that widens from the outside to the inside. This conicity (15) is achieved by radially inserting a friction element that is adjustable in diameter into the originally cylindrical bore (10), the diameter of which is changed as the radial movement progresses.

In one embodiment of the invention, the inlet cross-section (11) has a diameter of e.g. 12 mm and the outlet cross-section (12) has a diameter of 12.15 mm with a bore length of approx. 150 mm. This conicity corresponds to approximately 0.05%. It is sufficient to avoid blocking the strand in the bore (10).

Care must now be taken to avoid a backlog of the incoming material to be compacted in the area of the inlet cross-section (11) at each bore (10). To this end, a bevel (13) is first made in the inlet cross-section (11), which widens the bore (10) by a circumference of approximately 60°. The web material (21) (see Figure 5) between the individual radial bores (10) is then machined using a ball milling cutter (14).

For this purpose, Figure 5 shows the contour of a ball milling cutter (19) in dotted lines, which is inserted centrally into the inlet cross-section of the individual radial bore (10) and thereby continues the bevel (13) without edges. This ball milling cutter (19) is now moved along the

circular movement path (20) from bore (10) to bore (10), whereby this circular arc guide leads to the material web (21) receiving a convex curvature (16). There is therefore no flat surface or even an edge at any point on the material web (21), so that it is guaranteed that the material that has reached the tooth base (9) is conveyed through the radial bores (10) without backing up.

You can also see the contours of the outlet (17) in the example in Figure 5. For this purpose, a ball cutter

(22) of smaller diameter, which allows a groove-shaped transition of the tooth base wall to be achieved.

The example in Figure 3 also shows a large number of axially parallel bores (26) which are provided in the cylinder part (4) of the individual hollow roller (2) and are intended to bring a heating medium as close as possible to the radial bores (10). The teaching of the previously published WO 93/22132 is used for this purpose.

The example in Figure 6 shows that the compression path along a radial bore (10) can be significantly increased if an annular hollow cylinder insert (23) is inserted into the cavity (5) of the individual hollow roller (2). This hollow cylinder insert (23) also has a large number of radial bores (24) arranged in rows, which must be aligned with the bores (10) of the cylinder part (4).

The radial bores (24) of the hollow cylinder insert

(23) widen conically from the outside to the inside, although the conicity can be greater. In one embodiment, the inlet cross-section (30) has a diameter of 12.5 mm and the outlet cross-section (31) has a diameter of 13.5 mm. This means that with a bore length of approx. 160 mm,

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Conicity of approx. 0.3%.

According to the invention, the hollow cylinder insert (23) can be made of plastic. However, this plastic should have the property of being heat-conducting and insensitive to abrasion.

Finally, Figure 7 shows, using an independent embodiment, that instead of the radial bores &iacgr;&ogr; (10) according to Figure 2, radially continuous openings

(27) can be provided in the individual tooth base (9). These openings (27) can, for example, have a trapezoidal shape (28), wave shape (29) or other configuration.

Such openings (27) are obtained with the help of electrodes which have water passage holes for salt water as an electrolyte and which have the shape of the opening (27) to be formed. These electrodes are inserted into the tooth base (9). The material of the cylinder part (4) is removed by a radial feed. This flows back with the water on the outer surfaces of the electrode. By regulating the current strength, a change in the gap size is brought about, whereby the inner cross section of the individual opening is allowed to expand radially from the outside to the inside.

: .· · PARTS LIST Pelletizing device Hollow roller 1 Material supply 2 Cylinder part 3 inner space 4 Scraper 5 tooth-like profiling 6 Tooth 7 Tooth base 8th radial bore 9 Inlet cross-section 10 Outlet cross-section 11 Bevel 12 Ball milling 13 Conicity 14 convex curvature 15 Outlet 16 cove 17 Ball nose cutter (large diameter) 18 Movement path 19 Material bridge 20 Ball end mills (small diameter) 21 Hollow cylinder insert 22 drilling 23 Conicity 24 axially parallel bore 25 breakthrough 26 Trapezoidal forming 27 Waveforming 28 Inlet cross-section 29 Outlet cross-section 30 31

Claims (10)

PROTECTION CLAIMS 1.) Hollow roller (2) for pelletizing plant material, in particular stalk material, into pourable pressed products, the cylinder part (4) of which is profiled on the outside like a tooth (7), whereby in each individual tooth base (9) a row of conical holes (10) is arranged, which open into the interior (5) of the hollow roller (2), thereby characterized in that the bores (10) have a conical cross-section widening towards the interior (5) and the (9) material webs (21) located between the holes (10) are convexly curved (16). 2.) Hollow roller according to claim 1, characterized in that the convex curvatures (16) of the material webs (21) are formed by a longitudinal tooth base (9) from bore (10) to bore (10) are formed by a ball milling cutter (19) guided in an arc shape (20). 3.) Hollow roller according to claim 1 or 2, characterized in that the individual bore (10) in the tooth base (9) has a bevel (13) of e.g. 60°. 4.) Hollow roller according to claim 1 or 2, characterized in that the adjacent rows of bores (10) are arranged offset from one another. 5.) Hollow roller according to claim 4, characterized in that the offset corresponds to half a division of the bore spacing. 6.) Hollow roller according to claim 4 or 5, characterized in that between the last bore (10) and the front end of the tooth base (9) an outlet (17) is provided which rises obliquely from the tooth base (9) and widens, optionally with a concave groove-shaped base surface. 7.) Hollow roller, in particular according to claim 1 or one of the following, characterized in that a hollow cylinder insert (23) is inserted in the interior (5) of the hollow roller (2) to increase the wall thickness of the cylinder part (4) and has aligned bores (24) that widen conically inwards. 8.) Hollow roller according to claim 7, characterized in that the hollow cylinder insert (23) consists of plastic. 9.) Hollow roller according to claim 1 or one of the following, characterized in that the cylinder part (4) has a plurality of axially parallel bores (26) between the radial rows of bores (10) for passing through a heating medium. 10.) Hollow roller for pelletizing plant material, in particular stalk material, into pourable pressed products, the cylinder part (4) of which is profiled on the outside in a tooth-like manner (7), whereby openings (27) are provided which extend radially inwards from the tooth base (9) to the interior (5), characterized in that the openings (27) are designed as narrow, optionally trapezoidal or wave-shaped (28,29) shafts which widen inwards in cross-section and which are penetrated by means of an electrode with a cross-section adapted to electro-chemical material removal, where the cross-sectional change is achieved by changing the current intensity.