EP0359285B1 - Apparatus for briquetting stalks,in particular straw - Google Patents

Abstract

The apparatus for briquetting plant material, especially stalks, comprises a conical worm compactor (27) of which the worm (29) driveable in rotation possesses, at least at its end at the front in the conveying direction, a conically tapering outer contour defined by a plurality of turns of at least one worm helix (51) projecting from a conical worm core (49) and projects a cone-shaped compactor (33) of a worm housing (35). Ribs (53) project from the inner cone surface (55) of the conical space (33) towards the worm (29) and surround the worm (29) in the form of a conical helix with a turn direction opposite the turn direction of the worm (29). The rib (53) in the form of a conical helix appropriately extends as far as an outlet orifice (41) and screws the compacted stalks, co-rotating with the worm (29) at least to a limited extent, towards the outlet orifice (41). The apparatus possesses a press die (45), the outlet cross-section of which can be varied via a wedge mechanism (73, 79, 81). Inserted between the press die (45) and the conical worm compactor (27) is an annular part (43) which on its inner circumference (57) has a plurality of capillary degassing slots (63) open to the environment. <IMAGE>

Description

The invention relates to a device for briquetting plant crops, in particular straw.

From DE-OS 34 22 658 a straw briquetting device with a screw compactor is known, the rotatably drivable screw of which at its front end in the conveying direction has an outer contour which tapers conically in the conveying direction and is defined by several turns of two helical screw projections projecting from a conical screw core. The conical section of the otherwise cylindrical screw projects into a conical compression chamber of a screw housing, into which the screw, which is mounted on the fly, projects.

Above the cylindrical part of the screw, a hopper for the straw to be briquetted is attached, which is compacted by the rotating screw in the conical screw section and pressed out via an outlet opening at the tapered end of the conical surface of the screw housing. The pressure of the conical screw compressor can be controlled via a tubular press die with a variable outlet cross section, which adjoins the outlet opening of the conical surface.

The straw to be briquetted is strongly compressed under the pressure of the conical screw compactor, whereby it heats up and, due to its lignin content in the heat, is baked into a straw cake that is not very flowable even when warm. Since there may be congestion, particularly at the transition from the inner cone of the screw housing to the press die, which clogs the outlet opening of the conical screw compressor, a press ram is arranged axially displaceably in the screw of the device known from DE-OS 34 22 658, which periodically moves in the screw housing accumulating compacted straw is pushed out into the press die. It has been shown, however, that the lignin content of the straw not only enables the briquetting, but also sticks the press ram, which is displaceably guided in the screw, to immobility with the screw. The known device can thus only be operated in comparatively short operating intervals before it has to be dismantled and cleaned.

From US-A 4 632 795 a straw press with a comparatively long screw compactor is known, the compacting screw of which has a decreasing pitch of its screw helix in a long cylindrical section towards the outlet end and merges into a conical screw only in a short area immediately before the outlet end. The conical screw ends in a conical extension which engages in a conical opening of a piston head which can be displaced axially relative to the conical screw. The piston head is adjusted by a hydraulic drive depending on the delivery pressure of the conical screw. The delivery pressure is detected by means of a pressure sensor. The conical screw is in turn housed in a likewise conical screw housing, which has helical ribs on the inside, the winding direction of which is opposite to the winding spiral. The well-known straw press grinds the straw in the very long cylindrical screw conveyor and presses the ground material into granules. The conical annular gap between the conical projection and the conical opening of the piston head ensures the backflow of the material conveyed by the conical screw.

From WO 84/03252 it is also known in a briquetting device for straw or the like which compresses with a plunger to control the matrix tube composed of two tongues by drives which are fed from a pressure source via a control valve so that the load on the plunger driving motor is kept within predetermined limits.

Another device for producing briquettes from plant fibers is known from German patent 627 048. In this device, a conical screw feeds a conical compression chamber which is closed off from a die tube by a cutter head rotating with the conical screw. The knife head generates the retaining pressure of the screw compressor and cuts off the material compressed in the compressor chamber with a cutting edge. The peeled material is introduced one after the other into die tubes of a step-by-step revolver die.

Finally, a press for solidifying wood waste is known from Swiss patent 261 187, which is fed via a funnel to a cylinder space in which it is compressed by a piston over a predetermined stroke. At the outlet of the cylinder, a conically tapering press die is formed by axial rods, into which the pressed parts compressed in the cylinder are pushed out one after the other. Between the axial rods connected by rings, there are axial slots through which air trapped between the wood waste can escape from the compacts when compressed.

It is an object of the invention to provide a device for briquetting plant crop material, in particular straw, which allows the plant crop material to be briquetted to very hard bodies in the event of a continuous operating process which does not tend to malfunctions.

The starting point of the invention is a device for briquetting plant crop material, in particular straw, with a conical screw compactor, the rotatably drivable screw of which, at least at its front end in the direction of conveyance, has an outer contour tapering in the direction of conveyance and tapering in the direction of conveyance and determined by a plurality of turns of at least one cone-shaped screw core has and protrudes into a conical compression chamber of a screw housing, the The inner cone surface is provided with at least one guide bar for the stalk material projecting towards the screw and has an outlet opening for the compacted stalk material at the tapered end of the inner cone surface, and with a connecting element connected to the screw housing and following the outlet cone of the conical screw in the conveying direction and coaxially with the cone axis of the cone screw. essentially tubular press die with a plurality of radially movable tongues which can be moved relative to one another by a hydraulic actuator for changing the outlet cross section of the die tube of the press die.

The improvement according to the invention is characterized in that the guide bar encloses the screw in the form of a cone helix with a winding direction opposite to the winding sense of the screw, that an annular part connects to the outlet opening of the conical screw compressor, on the inner jacket of which a plurality of axially extending, narrow degassing slots open to the environment flow that the conical screw compressor is assigned a baling pressure sensor and that the actuator can be controlled depending on the baling pressure sensor in such a way that the outlet cross section of the die tube is expanded when a baling pressure setpoint is exceeded and is narrowed when the pressure falls below it.

The invention is based on a guide bar which is arranged on the inner cone surface of the screw housing of the known device and projects toward the screw. In the known device, a plurality of guide strips extending in the axial direction of the screw are provided on the inner cone jacket, by means of which the twisting of the straw cake is to be prevented during compaction. The invention proceeds from this principle and allows the straw cake in the conical screw compactor to rotate. The guide bar encloses the screw in the form of a conical spiral with a sense of turn opposite to the winding sense of the screw, whereby the guide bar screws the rotating straw cake to the outlet opening of the inner cone of the screw housing and ensures a smooth and trouble-free drain to the press die. Press rams or the like, which are provided in the known device, can thus be omitted.

A guide bar is to be understood here and below as an elongated element which is capable of screwing onto the compacted, rotating crop in the conveying direction. The element can in particular also have the shape of a rib or a web, which is also integrally formed on the worm housing, for example by grooves in the worm housing.

The device according to the invention is suitable for briquetting plant stalks of all types and consistency; however, it is used in particular for briquetting dry stalks, such as straw.

Due to the compaction effect of the cone screw compactor, the straw is often heated to such an extent that its water content evaporates at least partially. The invention prevents the steam pressure in the area of the outlet opening of the conical screw compressor from increasing due to the accumulation effect to such an extent that excess pressure damage to the device occurs. Also the danger is avoided that the compacted straw explosive due to excessive vapor pressure is driven out of the press die. Damage and dangers of this type are prevented by the ring part arranged between the outlet opening of the conical compressor chamber of the conical screw compressor and the pressing die which adjoins the outlet opening in the conveying direction and on the inner jacket of which a plurality of degassing channels open to the environment. The degassing channels are capillary channels with a very small width, for example of the order of a tenth of a millimeter, through which the developing steam can escape. The ring part is expediently a component produced using spark erosion technology.

The degassing channels should essentially only allow the passage of steam and possibly also fine dust. They are in the form of axially extending slots which merge into radially overlying, axially extending, wider discharge channels in order to improve the vapor discharge. While the degassing ducts on both axially end faces of the ring part are closed off by surfaces of adjacent components lying thereon, the discharge ducts are open to the surroundings at least on one end face of the ring part, for which purpose, in the adjacent component, for example the worm housing of the conical screw compressor, a ring duct open to the surroundings can be incorporated.

In order to be able to manufacture the ring part more easily, it is expediently not an integral part of the screw housing or the press die, but rather sits as a separate component in a chamber of a die tube of the press die open to the screw housing of the conical screw compressor.

A baling pressure sensor is assigned to the conical screw compressor of the device according to the invention, and the actuator can be controlled as a function of the baling pressure sensor. The baling pressure sensor can respond to the actual pressure acting between the worm and the worm housing, but can be implemented more easily if it senses the baling pressure via an indirect parameter, for example via the drive torque of the worm of the conical screw compressor.

The at the outlet opening of the conical screw compressor of e.g. from DE-OS 34 22 658 known adjoining die has an essentially coaxial to the cone axis of the conical screw compressor, divided by two axial slots in two halves, the outlet cross section can be varied by a radially acting hydraulic pliers. However, the outlet cross section of such a die can only be adjusted relatively inaccurately. In addition, a comparatively high hydraulic pressure must be constantly applied to adjust the outlet cross section.

A more precise adjustment of the outlet cross-section with reduced actuating forces can be achieved if wedge surfaces are provided on the outside of the die tube, which is divided into radially movable tongues by the axially extending slots, which jointly encloses a clamping ring. The clamping ring and the die tube are axially movable relative to each other and are biased by springs in the axial direction against each other. The actuator of the wedge gear formed by the clamping ring and the wedge surfaces adjusts the clamping ring against the force of the springs. The angle of inclination of the wedge surfaces is preferably chosen so that self-locking occurs, so that the actuator no longer has to absorb the baling pressure of the straw. The actuating force to be exerted by the actuator can be reduced even further if the springs prestress the clamping ring and the die tube against one another in the direction of a narrowing of the outlet cross section of the press die. This design of the press die can also be used with other straw briquetting devices than the device explained above.

In a first variant of the press die, the die tube is firmly connected to the screw housing and a machine base of the cone screw compressor. Several springs are distributed around the circumference of the die tube, which are supported on a support flange of the die tube on the one hand and on heads of axially extending tie rods which are fixedly connected to the press die or to the machine base. Such a press die requires only a few components.

In a second variant, the die tube and the screw housing of the conical screw compressor form a structural unit which is guided so as to be movable in the axial direction of the screw relative to the screw and the machine base. This variant has the advantage that not only the outlet cross section of the die can be varied, but also the free internal volume of the conical screw compressor. The wedge surfaces are arranged in such a way that when the outlet cross section of the press die is widened, the screw housing is removed from the screw in the conveying direction thereof. The pressure in the compressor chamber thus decreases immediately due to the adjustment movement due to the expansion of the compressor chamber and instantly supports the relief effect of the opening die. In the opposite case, the pressure rise in the compressor chamber is accelerated when the die is closed.

In the matrix tubes explained above, the material stowed in the matrix tube is pushed out at the end of the matrix tube opposite the outlet opening by the delivery pressure of the conical screw compressor. The die tube must therefore be so long that the compacted material has cooled to a solid mass at its outlet end. This requires comparatively long die tubes in order to solidify the molding compound under pressure in the die tube.

Taking this problem into account, the invention further relates to a device for briquetting plant stalks, in particular straw, with a conical screw compressor, the rotatably drivable screw of which at least at its front end in the conveying direction into a conically tapering in the conveying direction and at least one of a conical by several turns The helical screw protruding from the screw core has a certain outer contour and protrudes into a conical compression chamber of a screw housing, the inner cone surface of which is provided with at least one guide bar for the straw material projecting towards the screw and has an outlet opening for the compacted straw material at the tapered end of the inner cone surface, and one in front of the outlet opening of the cone screw compressor arranged press die arrangement, wherein the device is characterized in that the guide bar with the screw in the form of a cone spiral m winding direction of the screw encloses opposite winding sense that the press die arrangement is designed as a turret press die, the die tubes arranged on a common, rotatably mounted turret head can be individually aligned in succession to the outlet opening and that an annular part is arranged between the outlet opening of the compressor chamber and the turret press die the inner jacket of which opens into a plurality of axially extending, narrow degassing slots which are open to the environment.

The turret press die can be assigned an ejection station which is offset from the outlet opening in the circumferential direction of the turret head. The turret press die then comprises a plurality of die tubes, which are dimensioned exclusively from the point of view of the briquette formation and the achievement of a sufficiently high retaining pressure of the conical screw compressor, which facilitates the control of the briquetting process, since the compression process takes place independently of the ejection step.

Advantageously, the turret has a stationary closure wall axially opposite the outlet opening of the conical screw compressor, which at least closes the die tube, which is oriented toward the outlet opening, on the side facing away from the outlet opening. The matrix tube forms, together with the closure wall, a chamber into which the screw compressor feeds and which preferably already has the final size of the briquettes to be produced. In this way, the division step required for the above-described, open-ended die tubes is eliminated. The opening edge of each die tube facing the outlet opening expediently forms an annular knife edge which shears off the strand of material emerging from the outlet opening of the conical screw compressor during the indexing movement of the turret head.

In an expedient embodiment, the die tubes are arranged at a distance from one another on the turret head in the circumferential direction and form radially open cooling air passages between them. A cooling air blower conveys cooling air from radially inside to radially outside through these cooling air passages, so that the briquetted material can cool down during the gradual approach to the ejection station. For this purpose, the ejection station is angularly offset in the conveying direction by the largest possible number of die tubes against the position aligned with the outlet opening of the conical screw compressor.

For the step-by-step drive of the turret head, an optionally hydraulically driven ratchet step mechanism has proven to be suitable.

The inner conical surface of the screw housing normally extends beyond the screw in the conveying direction of the screw in both aspects of the invention explained above. In this way, a tapering chamber remains in the screw housing in front of the screw at the entrance to the pressing die, through which the pressing pressure of the screw must drive the straw that has already been compacted. This is considerably facilitated if the guide strip extends into the area of the inner cone surface which extends beyond the screw and expediently reaches as far as the outlet opening. It is understood that the cone helix can optionally also be designed as a multi-start cone helix consisting of several guide strips.

Crops, especially straw, must be compacted for briquetting with a comparatively high volume ratio. With e.g. Briquetting device known from DE-OS 34 22 658 is associated with the conical screw compressor coaxially with a screw pre-compressor which is fed with the straw material from above via a filling funnel. The screws of the cone screw compressor and the screw pre-compressor have a common screw core, so that there is a considerable overall length of the device.

To reduce the dimensions, it is provided in a preferred embodiment that the screw of the conical screw compressor has a conical shape over almost its entire conveying length and that the screw pre-compressor with a screw axis running transversely, in particular perpendicularly, to the screw axis of the conical screw compressor directly to an inlet opening in the Screw housing of the cone screw compressor connects. The resulting comparatively compact arrangement can be further reduced in favor of downsizing the screw pre-compressor if, on the side of the screw pre-compressor on which the outlet opening of the cone screw compressor is located, a pre-press roll mill with at least two axially parallel to one another and to the screw axis of the screw pre-compressor rotatably driven pre-press rollers is arranged, which press the straw between them and push them into an inlet opening of the screw pre-compressor transversely to its screw axis. The straw to be compacted is fed on the side of the pre-press roller mill facing away from the screw pre-compactor, for example via a conveyor belt, and passes through an essentially U-shaped path during the transport and compacting process, on which the respective processing components can be arranged relatively close together. The two pre-press rollers can be arranged axially parallel one above the other and, if necessary, be adjustable relative to one another, and, depending on their direction of rotation, a rotationally driven blow bar roller can also provide either an additional pre-press effect or a combing effect that equalizes the loading rate.

Fig. 1

eine teilweise schematische Schnittansicht einer Vorrichtung zum Brikettieren von Halmgut, insbesondere Stroh;

Fig. 2

eine Schnittansicht durch die Vorrichtung, gesehen entlang einer Linie II-II in Fig. 1;

Fig. 3

eine vergrößerte Darstellung eines Teils der Vorrichtung aus Fig. 1;

Fig. 4

eine Schnittansicht durch die Vorrichtung, gesehen entlang einer Linie IV-IV in Fig. 3;

Fig. 5

eine Schnittansicht durch die Vorrichtung, gesehen entlang einer Linie V-V in Fig. 3

Fig. 6

eine Schnittansicht durch einen Teil einer anderen Ausführungsform einer Vorrichtung zur Brikettierung von Halmgut, insbesondere Stroh,

Fig. 7

eine Schnittansicht durch einen Teil einer weiteren Ausführungsform einer Vorrichtung zur Brikettierung von Halmgut, insbesondere Stroh, und

Fig. 8

eine teilweise Schnittansicht durch die Vorrichtung, gesehen entlang einer Linie VIII-VIII in Fig. 7.

Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Here shows:

Fig. 1

a partially schematic sectional view of a device for briquetting straw, in particular straw;

Fig. 2

2 shows a sectional view through the device, seen along a line II-II in Fig. 1;

Fig. 3

an enlarged view of part of the device of FIG. 1;

Fig. 4

a sectional view through the device, seen along a line IV-IV in Fig. 3;

Fig. 5

3 shows a sectional view through the device, seen along a line VV in FIG. 3

Fig. 6

2 shows a sectional view through part of another embodiment of a device for briquetting straw crops, in particular straw,

Fig. 7

a sectional view through part of a further embodiment of a device for briquetting straw, in particular straw, and

Fig. 8

a partial sectional view through the device, seen along a line VIII-VIII in Fig. 7th

1 and 2 show a straw briquetting device with which loosely poured straw, which has not previously been comminuted or ground, can be compressed into compact straw briquettes of high density of at least 0.5 kg / dm 3. The straw is placed on a hopper 1 on an endless conveyor belt 5 moving in the direction of an arrow 3, which conveys the straw between two pre-press rolls 7, 9 of a pre-press roll mill, generally designated 11, one above the other with a horizontal axis. The pre-pressing rollers 7, 9 provided on their circumference with gripping teeth, strips or the like are driven in opposite directions to one another. The upper pre-press roller 9 is, for example, vertically movably guided on arms (not shown in detail) and is biased against the pre-press roller 7 by springs or weights. In the vicinity of the pre-press roller 9, a strip roller 13 is arranged above the conveyor belt 5, axially parallel, in the same direction is driven to the pre-press roller 9 and ensures a further pre-compression of the straw introduced by the conveyor belt 5 between the pre-press rollers 7, 9. Alternatively, the slat roller 13 can also be driven in the opposite rotating manner, in which case it then serves as a combing roller and ensures an even straw flow on the conveyor belt 5. On the outlet side of the pre-press roll mill 11 there is a screw pre-compressor 15 with a compressor screw 19 arranged in a screw housing 17, axially parallel to the pre-press roll mill 11. The screw pre-compactor 15 deflects the pre-pressed straw transported in the direction of arrow 3 in the axial direction of the compacting screw 19 and ensures further compaction of the straw. The compressor screw 19 has a substantially cylindrical screw core 21 and an at least single-start screw helix 23, which tapers conically at its discharge end 25. A motor 26 drives the screw pre-compressor 15, the pre-press roll mill 11, the strip roll 13 and, if appropriate, the conveyor belt 5. The components explained above ensure that the straw is largely pre-compacted, but this is not yet sufficient for briquetting.

The briquetting takes place in a cone screw compressor 27, the cone screw 29 of which is arranged with the screw axis 31 extending at right angles to the axis of the precompressing screw 19 in a conical compressor space 33 of a screw housing 35 firmly connected to the screw housing 17. The conical screw 29, which is mounted on the screw housing 35 or on a machine base via bearings 37, is driven by a drive motor (not shown in more detail) via a belt drive 39. The conical compressor chamber 33 opens at an axial distance from the free end of the conical screw 29 in an outlet opening 41, which, as will be explained in more detail below, is followed by a degassing ring 43 and a press die 45 with a hydraulically controllable outlet cross section. The conical screw compactor 27 picks up the pre-compacted straw directly from the screw precompressor 15, the compacting screw 19 of which engages for this purpose with its end 25 in the region of the larger-diameter end of the conical screw 29 in a conical inlet opening 47 of the screw housing 35. The conveying direction of the conical screw compressor 27 is horizontal and opposite to the conveying direction 3 of the conveyor belt 5. This results in an essentially U-shaped processing path, the components of the straw briquetting device being able to be arranged in a comparatively narrow space.

3 to 5 show details of the conical screw compressor 27, the degassing ring 43 and the pressure die 45. The conical screw 29 of the conical screw compressor 27 has a truncated cone-shaped screw core 49, from which a single or multiple-flight screw helix 51 with a truncated cone-shaped outer contour protrudes radially. Radially outward, the conical compressor space 33 is delimited by an inner conical surface 55 provided with radially projecting strips or ribs 53, which extends in the conveying direction of the conical screw 29 over its tapered end to the outlet opening 41 and is also provided with ribs 53 in this area. The ribs 53 enclose the conical screw 29 in the form of a single or multi-start helix, the winding direction of which is opposite to the winding direction of the helical screw 51 and can be limited or formed by grooves which are incorporated into the worm housing 35.

The conical screw 29 conveys the pre-compacted straw supplied via the inlet opening 47 to the outlet opening, where it is jammed by the subsequent press die 45 and compressed under high pressure. The compaction effect increases the temperature of the straw cake to such an extent that it bakes the straw cake into a briquette material that is compact and can be subjected to mechanical stress after the subsequent cooling. Since the compacted straw is not only driven by the conical screw 29 in the conveying direction, but is also at least partially rotated about the screw axis 31, the helically arranged ribs 53 support the conveying action, since they screw the rotating straw in the conveying direction due to the opposite sense of the winding from the screw helix 51 . In particular, the ribs 53 in the region of the outlet opening 41 support the passage of the compacted straw into the essentially cylindrical outlet channel 61 formed by an opening 57 of the degassing ring 43 and a die tube 59 of the press die 45. The ribs 53 thus prevent the outlet opening 41 from being blocked unintentionally.

The heating of the compacted straw in the compression chamber 33 is so strong that water vapor can form in particular in the area of the outlet opening 41 due to the drying process, which can lead to overpressure damage to the device, but in particular the compressed straw contained in the matrix tube 59 explosively from the compression tube 59 can drive out. To prevent this, a plurality of degassing slots 63 distributed in the circumferential direction are provided in the degassing ring 43 adjoining the outlet opening 41. The degassing slots 63 are designed as capillary slots with a slot width on the order of 1/10 mm and extend over the entire Length of the degassing ring 43. The degassing slots 63, which open radially on the inside to the opening 57, open into radially overlying wider discharge channels 65, which wedge-shaped widen towards the conical screw compressor 27 and open at the end face of the degassing ring 43 into an annular channel 67 which is open to the environment. The degassing slots 63 and the discharge channels 65 can be incorporated into the degassing ring 43, for example, by means of electrical erosion processes. The degassing ring 43, which is designed as a separate component for easier manufacture, is seated in a chamber 69, open towards the screw housing 35, of a foot part 71 of the pressing die 45 holding the die tube 59 on the screw housing 35.

In order to be able to adjust the outlet cross section of the pressing die 45, the die tube 59 has an outer jacket 73 which widens conically toward the conical screw compressor 27 and is divided into a plurality, here eight, radially resilient tongues 77 by a plurality of circumferentially arranged axial slots 75. The outer cone of the die tube 59 is surrounded by two clamping rings 79, 81, which are connected by adjustable spacer bolts 83 to form a unit which can be moved along the die tube 59. The clamping ring 79 carries a radially projecting ring flange 85 which is guided on several, here three, circumferentially offset guide rods 87 projecting from the foot part 71. On the side of the ring flange 85 axially facing away from the foot part 71, plate spring assemblies 89 are guided on guide rods 87, which are supported between the ring flange 85 on the one hand and screw heads 91 of the guide rods 87 on the other hand. The conical surface 73 of the die tube 59 and the clamping rings 79, 81 form a self-locking for the radial pressure in the die tube 59 Wedge gear, the plate spring assemblies 89 pretensioning the clamping rings 79, 81 in the closing direction of the die tube 59. The transmission effect of the wedge gear is sufficient to be able to close the die tube 59 against the pressure of the compacted straw. To open the die tube 59, several, here three, mutually offset, hydraulic piston-cylinder units 93 are provided on the base part 71, which are supported on the ring flange 85 and the clamping rings 79, 81 against the force of the plate spring assemblies 89 to the tapered end of the Press cone surface 73 towards. In this way, the outlet cross section of the die 45 can be controlled with relatively little hydraulic effort. The control can take place automatically if, as shown in FIG. 1, the hydraulic pressure of the cylinders 93 is increased by means of a switch 95 responsive to the drive torque of the conical screw 29, if the drive torque and accordingly the pressing pressure of the conical screw compressor 27 increases above a predetermined value , or is reduced when the drive torque and thus the pressure drops below the predetermined value.

The straw heated due to the pressing action by the conical screw compressor 27 cools during the pushing out through the outlet channel 61 to a briquette strand, which is cut into pieces at the outlet of the pressing die 45 by suitable tools, for example a saw or the like. The length of the die tube 59 can be shortened if the individual tongues 77 are provided with axially extending cooling water channels 97. Correspondingly, for example, cooling water channels 99 can be provided on the outer circumference of the degassing ring 43. Inlet and outlet lines to the cooling water channels 97, 99 are not shown for the sake of simplicity.

FIG. 6 shows a variant of a device for briquetting straw, which differs from the device of FIGS. 1 to 5 essentially only in the type of control of the outlet pressure of the conical screw compressor. Parts having the same effect are designated in FIG. 1 with the reference numbers of FIGS. 1 to 5 and provided with the letter a to distinguish them. To explain the structure and function of these parts, reference is made to the description of FIGS. 1 to 5.

1 to 5, the clamping rings 79, 81 connected to one another can be displaced relative to the cone surface 73 of the die tube 59 and the cone tube 59 is firmly connected to the machine base of the device via the foot part 71 and the worm housing 35, 6, the two clamping rings 79a and 81a, which are connected to one unit via spacer bolts 83a, are immovably fastened to the machine base indicated at 103 and supporting the conical screw 29a by means of spacer bolts 101. The die tube 59a is fastened to the worm housing 35a of the conical screw compressor 27a via its foot part 71a receiving the degassing ring 43a and, together with the foot part 71a and the worm housing 35a, forms a one which is displaceable in the direction of the worm axis 31a relative to the machine base 103 and thus relative to the clamping rings 79a and 81a Unit. The unit comprises an annular flange 105, which is arranged here on the worm housing 35a and protrudes radially outwards and is guided on a plurality of guide rods 107, which are offset relative to one another in the circumferential direction, in a manner that prevents rotation but is displaceable. The guide rods 107 projecting axially from the machine base 103 have screw heads 109 at their free ends and guide plate spring assemblies 111, which are located between the ring flange 105 and support the screw heads 109 and pretension the unit consisting of worm housing 35a and die tube 59a against the conveying direction of the conical screw 29a towards the machine base 103. In the exemplary embodiment in FIG. 6, instead of a continuously continuous conical surface, the clamping rings 79a, 81a are assigned two conical surface sections 73a which follow one another to form a step. The conical surface sections 73a taper towards the conical screw compressor 27a, with which the plate spring assemblies 111 in turn preload the pressing die 41a in the closing direction. When the die tube 59a closes the outlet cross section and faces the conical screw 29a, not only the outlet cross section of the press die 45a is reduced, but also the radial distance between the conical screw 29a and the inner cone surface 55a of the screw housing 35a. As the distance decreases, the pressure generated by the conical screw 29a also increases. In contrast to the exemplary embodiment in FIGS. 1 to 5, the pressure in the compressor chamber 33a does not have to build up gradually due to the accumulation effect of the press die 45a.

To relieve the pressure chamber 33a, several hydraulic piston-cylinder units 113 are provided on the machine base 103 which are offset in the circumferential direction and which are supported on the ring flange 105 and which consist of worm housing 35a, degassing ring 43a and die tube 59a against the force of the Move cup spring assemblies 111. Because of this relative displacement, the outlet cross section of the die 45a is increased on the one hand, and the screw housing 35a is removed from the conical screw 29a on the other hand. This reduces the jamming effect of the press die 45a on the one hand, and on the other hand there is an immediate reduction in pressure in the compressor chamber 33a. The plate spring assemblies 111 and the cylinder-piston units 113 correspond in their function to the components 89 and 93 of the exemplary embodiment in FIGS. 1 to 5.

The worm housing 35a is in turn provided on its inner conical surface 55a with ribs 53a which helically enclose the conical screw 29a in the form of a single-start or multi-start helix and extend beyond the conical screw 29a to the outlet opening 41a. The winding direction of the ribs 53a is opposite to the winding direction of the screw helix 51a, which supports the conveying action of the conical screw 29a, in particular in the region of the outlet opening 41a. In addition, in the device of FIG. 6, the pumping effect resulting from the axial movement between the conical screw 29a and the screw housing 35a also contributes to preventing undesired clogging in the region of the outlet opening 41a.

7 and 8 show a variant of a device for briquetting straw, in which, in contrast to the device of FIGS. 1 to 6, a turret press die 121 is provided instead of a single die tube with a controllable cross section. The turret press die 121 replaces the press die 45 of the briquetting device of FIGS. 1 to 5. Components having the same effect are identified by the reference numerals of FIGS. 1 to 5 and, to distinguish them, by the letter b. To explain these components, reference is made to the description of FIGS. 1 to 5.

The turret press die 121 directly adjoins a degassing ring 43b of the one already explained above Type, which in turn follows the outlet opening 41b of the conical screw compressor 27b. The conical screw compressor 27b corresponds to the construction of the compressor 27 of FIGS. 1 to 5. The turret press die 121 has a turret head 123 which is rotatably mounted on a machine frame 127 about an axis of rotation 125 parallel to the screw axis 31b. On a circle around the axis of rotation 125, a plurality of matrix tubes 129 are arranged offset to one another in the circumferential direction and axially parallel to the axis of rotation 125, such that one of the matrix tubes 129 is aligned coaxially with the outlet opening 41b, while another matrix tube is simultaneously aligned with an ejection station 131, in which a plunger 135 displaceable by a hydraulic cylinder 133 can empty the die tube. A ratchet mechanism 137, shown schematically at 137 and directly engaging the turret head 123, transports the die tubes 129 successively through the position aligned with the outlet opening 41b, in which the screw compressor 27b conveys compressed material into the die tube 129 and subsequently into the ejection station 131. The one facing the degassing ring 43b The opening edge 139 of each die tube 129 forms an annular knife edge, which shears off the compacted material strand together with a counter cutting edge formed by the degassing ring 43b during the gradual rotation of the turret head 123. The individual die tubes 129 have an inner jacket 141 which widens slightly in the ejection direction of the ejection station 131 in order to facilitate the ejection of the briquette which has already been pressed into its final shape by the die tube 129. At least in the position axially opposite the outlet opening 41b, a closure wall 143, which is fixed to the machine frame, closes in succession through this position transported die tubes 129.

The briquettes formed in the die tubes 129 cool while the die tubes 129 are transported from the position determined by the outlet opening 41b of the conical screw compressor 27b to the position determined by the ejection station 131. In order to achieve the longest possible cooling time, the ejection station 131 is located in the direction of rotation 145 (FIG. 8) as far as possible from the filling position determined by the screw compressor 27b. The number of matrix tubes 129 located in the direction of rotation 145 between the filling position and the ejection position should therefore be as large as possible, compared to the remaining matrix tubes or those remaining in the opposite direction between these two positions.

The matrix tubes 129 are arranged at a distance from one another in the circumferential direction and delimit radial cooling air openings 147 between them, through which a fan 149 arranged coaxially with the axis of rotation 125 conveys cooling air from radially inside to radially outside.

The turret press die 121 explained above can, after it manages with comparatively short die tubes 129, also be used without the degassing ring 43b explained above. The turret 123 then connects essentially directly to the outlet opening 41b of the conical screw compressor 27b.

Claims (28)

1. Apparatus for briqueting stalk-plant material, in particular straw,
   comprising a conical screw compactor (27) of which the rotatably driven screw (29) evinces, at least at its front end as seen in the direction of conveyance, an outer contour tapering conically in the direction of conveyance and determined by several turns of at least one screw coil (51) projecting from a conical screw shank (49) and enters a conical compaction chamber (33) of a screw housing (35) of which the inside conical surface (55) is provided with at least one guide strip (53), for the stalk material,
   projecting toward the screw (29) and has a discharge opening (41) for the compacted stalk material at the tapered end of the inside conical surface (55),
   and comprising an essentially tubular die (45) connected to the screw housing (35) and following, as seen in the direction of conveyance, coaxially with the conical axis (31) of the conical screw, the discharge opening of the compaction chamber (33), said die (45) comprising several radially movable tongues (77) which are mutually movable by a hydraulic adjustment drive (93; 113) for changing the discharge cross-section of the die-pipe (59) of the die (45),
   characterized in that
   the guide strip (53) encloses the screw (29) in the form of a conical coil with a winding sense opposite the winding sense of the screw (29),
   in that an annular part adjoins the discharge opening of the conical screw compactor (27), with a plurality of axially extending, narrow degassing slits open to the ambient issuing on the inside surface of said annular part, in that a pressure sensor (95) is associated with the conical screw compactor (27),
   and in that the adjustment drive (93; 113) is so controllable as a function of the pressure sensor (95) that the discharge cross-section of the die-pipe (59) is enlarged and narrowed respectively when reference pressure values are being crossed upward and downward.
2. The apparatus according to claim 1, characterized in that the die-pipe (59) of the die (45) is provided on its outside with wedge surfaces (73), in that the radial axial spacing of the tongues (77) is determined by at least one common clamping ring (79, 81) enclosing the wedge surfaces (73), and in that the clamping ring (79, 81) and the die-pipe (59) are axially movable relative to each other and are pre-stressed by springs (89; 111) toward each other, and may be moved by an adjustment drive (93; 113) toward each other against the pre-stressing force of the springs (89; 111).
3. The apparatus according to claim 2, characterized in that the springs (89; 111) pre-stress the clamping ring (79, 81) and the die-pipe (59) toward each other in the sense of constricting the discharge cross-section of the die (45).
4. The apparatus according to claim 3, characterized in that the die-pipe (59) is rigidly joined to the screw housing (35) of the conical screw compactor (27) and the wedge surfaces (73) taper away from the screw housing (35), in that the clamping ring (79, 81) comprises a radially projecting rest flange (85) and that several tension rods (87) axially parallel to the die-pipe (59) and located around the die-pipe (59) are rigidly joined to the screw housing (35), and in that the springs (89) which especially are designed as cup springs are guided on the tension rods (87) and are clamped between the rest flange (85) and a head (91) at the end of the tension rod (87) far from the screw housing.
5. The apparatus according to claim 2 or 3, characterized in that the screw housing (35a) and the die-pipe (59a) are combined into a structural unit guided displaceably relative to the screw (29a) of the conical screw compactor (27a) in the direction of the screw axis (31a) on a machine base (103) supporting the screw (29a), in that the clamping ring (79a, 81a) is rigidly joined to the machine base (103) and in that the springs (111) are clamped between the structural unit (35a, 59a) and the machine base (103).
6. The apparatus according to claim 5, characterized in that the structural unit (35a, 59a) comprises a radially projecting rest flange (105) and that several tension rods (107) axially parallel to the screw axis (31a) and located around the structural unit (35a, 59a) are rigidly joined to the machine base (103), and in that the springs (111) which especially are designed as cup springs are guided on the tension rods (107) and are clamped between the rest flange (105) and a head (109) at the end of the tension rod (107) far from the machine base (103).
7. The apparatus according to one of claims 2 to 6, characterized in that several clamping rings (79, 81) mutually offset in the axial direction of the die-pipe (59) are combined into a structural unit.
8. The apparatus according to one of claims 1 to 7, characterized in that the pressure sensor (95) responds to the drive torque of the screw (29) of the conical screw compactor (27).
9. Apparatus for briqueting stalk-plant material, in particular straw,
   comprising a conical screw compactor (27) of which the rotatably driven screw (29) evinces, at least at its front end as seen in the direction of conveyance, an outer contour conically tapering in said direction of conveyance and determined by several turns of at least one screw coil (51) projecting from a conical screw shank (49) and enters into a conical compaction chamber (33) of a screw housing (35) of which the inside conical surface (55) is provided with at least one guide strip (53), for the stalk material, projecting toward the screw (29) and has a discharge opening (41) for the compacted stalk material at the tapered end of the inside conical surface (55),
   and comprising a die arrangement arranged in front of the discharge opening (41b) of the conical screw compactor (27b),
   characterized in that
   the guide strip (53) encloses the screw (29) in the form of a conical coil with a winding sense opposite the winding sense of the screw (29),
   in that the die arrangement is designed as a revolving die (121) of which the die-pipes (129) arranged on a common, rotatably supported turret (123) can be individually and consecutively aligned with the discharge opening (41b),
   and in that an annular part (43b) is arranged between the discharge opening (41b) of the compaction chamber and the revolving die (121), with a plurality of axially extending, narrow degassing slits open to the ambient issuing on the inside surface of said annular part.
10. The apparatus according to claim 9, characterized in that an expulsion station (131) circumferentially offset in the direction of the turret (123) relative to the discharge opening (41b) of the conical screw compactor (27b) is associated with the revolving die (121).
11. The apparatus according to claim 10, characterized in that the revolving die (121) comprises a stationary closing wall (143) axially opposite the discharge opening (41b) of the conical screw compactor (27b), said closing wall (143) closing at least the particular die-pipe (129) which is aligned with the discharge opening (41b) on that side facing away from the discharge opening (41b).
12. The apparatus according to claim 11, characterized in that the inside surface (141) of the die-pipes (129) conically flares in the direction of expulsion of the expulsion station (131).
13. The apparatus according to one of claims 9 to 12, characterized in that the issue rim of each die-pipe (129) pointing to the discharge opening (41b) forms an annular knife blade (139).
14. The apparatus according to one of claims 9 to 13, characterized in that the die-pipes (129) are arranged circumferentially spaced apart on the turret (123) and between themselves form radially open cooling-air gaps (147), and in that a cooling-air blower (149) is provided which moves cooling air from the radial inside to the radial outside through the cooling-air gaps (147).
15. The apparatus according to one of claims 10 to 14, characterized in that the number of die-pipes (129) between the die-pipe (129) aligned with the discharge opening (41b) and the die-pipe (129) aligned with the expulsion station (131), as seen in the direction of rotation (145) of the turret (123), is larger than the number seen opposite the direction of rotation (145).
16. The apparatus according to one of claims 9 to 15, characterized in that a ratchet stepping mechanism (137) is provided to drive the turret (123).
17. The apparatus according to one of claims 1 to 16, characterized in that the inside conical surface (55) of the screw housing (35) extends beyond the screw (29) in the direction of conveyance of the screw (29) and in that the guide strip (53) extends into the region of the inside conical surface (55) that reaches beyond the screw (29).
18. The apparatus according to claim 17, characterized in that the guide strip (53) reaches as far as the discharge opening (41).
19. The apparatus according to one of claims 1 to 18, characterized in that several guide strips (53) jointly form a multiple conical coil.
20. The apparatus according to one of claims 1 to 19, characterized in that the screw (29) of the conical screw compactor (27) is conical approximately over its entire length of conveyance and that the conical screw compactor (27) by means of an intake opening (47) of its screw housing (35) directly adjoins a screw pre-compactor (15) of which the screw axis is transverse, in particular perpendicular, to the screw axis (31) of the conical screw compactor (27).
21. The apparatus according to claim 20, characterized in that a pre-compression roll assembly (11) with at least two oppositely rotatingly driven pre-compression rolls (7, 9) of which the axes are mutually parallel and parallel to the screw axis of the screw pre-compactor (15) is arranged on the side of the screw pre-compactor (15) where the discharge opening (41) of the conical screw compactor (27) is located, said pre-compression rolls (7, 9) pre-compressing the stalk material between them and inserting it into an intake opening of the screw pre-compactor (15) transversely to its screw axis.
22. The apparatus according to claim 21, characterized in that the two pre-compression rolls (7, 9) are superposed and that the upper pre-compression roll (9) is vertically movably supported and elastically pre-stressed toward the lower pre-compression roll (7) by a pre-stressing force.
23. The apparatus according to claim 21 or 22, characterized in that a conveyor belt (5) is arranged on the side of the pre-compression roll assembly (11) facing away from the screw pre-compactor (15), with a rotatingly driven strip impact roll (13) being arranged with its axis parallel to the pre-compression roll assembly (11), adjacent thereto and above the conveyor belt (5).
24. The apparatus according to one of claims 1 to 23, characterized in that the slits (63) of the annular part (43) merge into axially extending, wider drain ducts (63) located radially above and open toward the ambient at one end face of the annular part (43).
25. The apparatus according to claim 24, characterized in that the drain ducts (63) axially issue into a ring duct (67) of the screw housing (35) of the conical screw compactor (27), said ring duct (67) being open to the ambient.
26. The apparatus according to claim 24 or 25, characterized in that the drain ducts (63) are wedge-shaped and taper away from the conical screw compactor (27) in the axial direction.
27. The apparatus according to one of claims 1 to 26, characterized in that the die (45) comprises a chamber (69) open toward the conical screw compactor (27) on the side of its die-pipe (59) facing the conical screw compactor (27), said chamber (69) receiving the annular part (43) and together with the die (45) being affixed to the screw housing (35) of the conical screw compactor (27).
28. The apparatus according to one of claims 1 to 27, characterized in that several cooling-water ducts (97, 99) are provided in a circumferentially distributed manner both in the region of the annular part (43) and in that of the die (45).

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