EP2425947A2 - Extrusion device - Google Patents

Abstract

The machine has an extruding press device (4) with a dehumidifier device for small part, and a small part feed (6) arranged upstream of the dehumidifier device. The dehumidifier device produces a level of 6-14 percentage of absolute humidity. The dehumidifier device is designed as a belt humidifier, which includes a movable and air permeable small part support and a heating device for dry air flow having temperature of less than 120 degree Celsius.

Description

The invention relates to an extrusion press for the production of extruded products from binder provided with small vegetable parts, in particular wood small parts.

Conventional extrusion presses consist of an extruder, a downstream channel-like heating section and a subsequent cooling section and possibly a saw arranged at the end, which divides the strand by cross-sections into block-like individual pieces. Conventional heating systems have heated with oil or another medium and at least partly. adjustable walls used in a reversing extruder, e.g. a ram, in the pressing rhythm to achieve a braking effect alternately delivered and lifted. In this contact heat transfer, the setting process takes a relatively long time, which brings a correspondingly large length of the heating passages and also the subsequent Auskühlstrecke with it. In addition, the energy consumption is high.

From the WO 99/48659 Another extrusion press is known in which the strand is pressed and treated with heat and steam. In the steam treatment is operated with excess steam, the excess steam is then sucked with Entdampfungsgeneratoren and recycled in the circuit to the steam generator. In another variant, only the edge zone of the strand is vapor-deposited, which leads to no setting in the entire strand cross-section and requires a further heat input in a subsequent heating cycle. The extrusion press thus also has a great length. The font also shows a variety of different apparatus and process techniques for performing strand vapor deposition. The strand is vaporized from the outside and / or inside. In the Innenbedampfung the steam is guided axially through a press mandrel occurs there frontally in an inner cavity of the strand, which is to be axially sealed by a drag closure.

The DE 299 12 822 U1 shows an extruder for glued wood hardware, the extruder is followed by a heated Aushärtekanal in which in the extrusion direction further away and at a distance from the extruder a pressing station with a steam supply is arranged, which presses the partially cured strand and then emits in a downstream heated Nachhärtezone.

The EP 0 908 281 A1 is also concerned with an extruder for glued wooden parts, wherein the heat energy required to cure the strand and the binder is introduced during the pressing by vapors immediately following the filling station. This can be done by means of a Innenbedampfung or Außenbedampfung, the steamed strand is then pushed on through a heated channel.

The WO 02/34489 A shows a further variant of such an extrusion press, similar to the DE 299 12 822 U1 is formed, wherein the strand is applied in a workstation with contactable walls on the strand. This steaming station can be arranged directly behind a recipient, with a conventional heating channel connecting. In another variant, the heating channel can be connected upstream of the steaming station with a further radial pressing station be.

It is an object of the present invention to provide a better manufacturing technique for extruded products.

The invention solves this problem with the features in the main claim.

The steam treatment of the strand is preferably carried out in such a way that the strand subsequently has a high dimensional stability. This means that it shows no or only insignificant deformations after removal of external pressure. With the claimed technique, it is possible to complete the setting process in the strand by the steam treatment so far that the glue strength is greater than the internal stresses in the strand. This has the advantage that the heating section can be kept very short, which leads to a substantial reduction in the overall length of the extruder. In addition, the cooling section can connect directly to the outlet of the heating section and to the end of the steam supply or the steam treatment. Due to the optimal energy utilization, the cooling section can be kept shorter than in the prior art, which also brings a considerable reduction in the overall length of the extruder with it.

The steam treatment has the further advantage that it allows a faster and more uniform heating of the strand and a faster setting. It is particularly advantageous when working with saturated steam and its condensation in the strand. By changing the state of aggregation, a lot of heat energy can be released quickly and evenly in the strand. It is advantageous, the amount of steam and the vapor pressure on the heat absorption capacity of adapted to tune strand area and dimensioned such that on the one hand the strand can be completely penetrated in the transverse direction and can set and wherein the amount of steam in the strand can condense substantially completely. As a result, excess steam and a complex and space-consuming steam disposal via reactors or the like. Avoid. In addition, the environmental impact is lower.

The claimed evaporation technology also provides the necessary operational reliability in the extrusion of small plant parts with a relatively high degree of moisture. Thanks to the vapor deposition, the extrusion channel can have substantially rigid walls without this leading to damage in the strand. The small parts moisture can be heated and shared via the steam and energy supply for the setting process. In addition, it has been shown that the shape stability of the strand achieved at the end of the vaporization makes its further treatment and in particular the passage through the cooling section unproblematic. In comparative experiments with an incomplete setting by steam supply and with an additional subsequent conventional contact heating by Heizkanalwände has been shown that a high moisture content of small parts can lead to cracks and delamination in the strand. Although this can be prevented by additional measures and is insofar practicable. In contrast, the preferred vapor deposition technique offers further advantages.

A steam quantity control also has the advantage that it provides for clear and reproducible process conditions and for a secure setting of the binder in the strand. On the other hand, excess steam is largely avoided, which leads to a significant reduction in construction and operating costs. Degassing generators and vapor recirculation are dispensable. The preferably saturated process steam is also optimally utilized. It condenses in a controllable strand area, whereby the heat required for setting is released in an optimal way and with uniform distribution via the phase or aggregate change. Also favorable is the fact that it is possible to work with relatively low quantities of steam and thus cost-effectively. The capacity of the vaporization system can also be designed smaller and cheaper.

For steam flow control, internal vapor deposition from the jacket of the press mandrel directly into the adjoining strand region is of particular advantage, because this ensures greater process reliability. In addition, the steamed strand area is better limited and controllable. The introduced steam can be optimally utilized. Alternatively or additionally, external evaporation is possible.

In all cases it is of particular advantage if the vapor deposition is carried out in the section of the heating channel adjoining the recipient. In these areas, the strand usually has the highest compression, so that the heat introduced by the steam can be optimally used for the setting. It is also favorable if fixed or rigid channel walls are present in the vaporization area and if strand formation takes place in the vaporization area. The setting process is significantly improved and accelerated by targeted evaporation, whereby the heating channel designed shorter and the overall length of the entire extruder can be significantly reduced. This leads to a higher economic efficiency.

The steam can be supplied, for example, continuously or intermittently with the strand standing. In both cases, a steam quantity control is advantageous. The drive can be reversing and have a press stamp. This has the advantage that the press ram seals the strand end gas-tight and limits the steam expansion zone to the rear. Alternatively, a continuous extrusion, for example with a screw, also possible.

The Innenbedampfung from the mandrel shell also has the advantage that you can work with relatively small steam-carrying volumes in the mandrel area. As a result, the amount of steam can be controlled particularly well and purposefully. The steam quantity control can alternatively or additionally also be used for external vapor deposition. For the setting process, it is favorable in both cases if the evaporation takes place in a channel region of the extruder, which has a substantially solid channel wall, which ensures the shaping of the strand and possibly also a certain braking effect to achieve the desired compression in the strand, optionally in conjunction with another braking device, eg undeliverable channel walls in the cooling section. For process reliability, it is also advantageous if the axial feed region of the steam is limited in the strand and extends in particular over a strand feed length of one to two extrusion strokes.

In terms of process technology, the use of steam from water, eg saturated steam, is favorable. A vapor pressure of about 10 to 15 bar and a corresponding steam temperature have proven to be advantageous. The amount of heat required for setting corresponds to a relatively small volume of vapor and is released during the condensation targeted in a limited strand element. In addition, these steam parameters are advantageous for the good and uniform penetration of the impinged strand area and for the efficiency of the energy conversion.

A drying of the vegetable small parts, in particular a targeted drying with the claimed degree of drying and / or with a wire or belt dryer has various advantages. By preparing the small vegetable parts, e.g. As chips or wood chips are present, these can be better processed and pressed into a strand with high quality and uniformity. In particular, it is also favorable for energy reasons to dry the small parts only to the extent necessary for the subsequent extrusion process. The finished and set product, e.g. the blocks separated from the strand are relatively insensitive to moisture and may have a significant residual moisture, e.g. up to 30% atro. For reasons of energy balance, it is therefore advantageous not to excessively dry the small parts prior to extrusion and to operate a high energy expenditure for this purpose. Small-scale drying to a moisture content of about 6 - 18% atro at the end of the drying is therefore economical and cost-effective. The same applies to the use of a screen or belt dryer, with which the moisture levels mentioned can be achieved. However, drying may also be reduced to a lower level of moisture, e.g. 2% atro or a higher degree of humidity up to about 20% atro or more.

The small parts can during transport with dry air and with a limited temperature level of eg up to about 120 ° Celsius, be applied, resulting in a particularly uniform, fast and economical drying. The drying can take place in a continuous process, which is favorable in terms of production technology and, if necessary, ensures high output. The drying process can also be interrupted. Due to the mentioned degree of moisture, the small parts can be after drying in caching a silo or other container and processing it at a later time. The resumption of water and moisture and a product change are low here.

For the drying and extrusion technique a single or multi-stage comminution of small vegetable parts is low, especially a coarse and fine comminution, the coarse crushing before drying and fine comminution can be done after drying and before extrusion. For drying in a belt dryer or screen dryer, it is advantageous to use a small-scale producer, e.g. a sawmill, coming plant small parts of a pre-crushing supply. As a result, the surface is increased, which is favorable for the subsequent drying. After drying, subsequent comminution can follow, with which a particle size of the small parts suitable for extrusion can be set. At the same time a homogenization of the small parts material can be achieved. Both are favorable for the subsequent gluing and the extrusion process. Furthermore, it is advantageous for energetic reasons to carry out this comminution and the adjustment of the particle size after drying. Dried small parts are easier to crush and with less energy and machinery than the wet raw material. Alternatively, this comminution and adjustment can take place before drying.

For the processing of small parts with a higher degree of moisture, it is beneficial to bring the heat required for setting the binder in the strand by steam and preferably substantially exclusively by steam and only at a single, localized location. It has been shown that by a steam treatment, the consumption of binder or glue can be reduced. Accordingly, the addition of glue or water or moisture into the small parts mass is also reduced. Accordingly higher may be the own moisture content of the plant small parts.

In the subclaims further advantageous embodiments of the invention are given.

Figur 1:

eine Schemadarstellung einer Strangpressanlage,

Figur 2:

eine Seitenansicht einer Strangpresseinrichtung,

Figur 3:

einen abgebrochenen Längsschnitt durch eine Strangpresse und einen anschließenden Heizkanal mit Innenbedampfung,

Figur 4:

einen abgebrochenen Längsschnitt durch eine Strangpresse und einen anschließenden Heizkanal mit Außenbedampfung,

Figur 5 bis 8:

einen Heizkanal in perspektivischer Ansicht sowie in verschiedenen geklappten Seiten-, Front- und Draufsichten,

Figur 9 und 10:

eine ausschnittsweise Darstellung einer Auskühlstrecke in Seitenansicht und geklappter Frontansicht und

Figur 11 bis 13:

einen Bandtrockner in Seitenansicht, Stirnansicht und Draufsicht.

The invention is illustrated by way of example and schematically in the drawings. In detail show:

FIG. 1:

a schematic representation of an extrusion press,

FIG. 2:

a side view of an extrusion press,

FIG. 3:

a broken longitudinal section through an extruder and a subsequent heating channel with Innenbedampfung,

FIG. 4:

a broken longitudinal section through an extruder and a subsequent heating channel with external evaporation,

FIGS. 5 to 8:

a heating channel in perspective view and in various folded side, front and top views,

FIGS. 9 and 10:

a partial view of a Auskühlstrecke in side view and folded front view and

FIGS. 11 to 13:

a belt dryer in side view, front view and top view.

FIG. 1 shows in a schematic plan extruder (1) for producing a strand (2) from small plant parts, especially small pieces of wood such as sawdust, wood chips or the like., Which are mixed with a thermo-reactive binder or adhesive, for example. The small vegetable parts may alternatively or additionally consist of another plant material. she are from a small parts producer (51), for example, a sawing or planing mill, where they arise as a processing waste, fed to the extrusion press (1).

The strand (2) can have any cross-sectional shape, e.g. may be circular, oval or prismatic, in particular substantially square or rectangular, with possibly rounded, chamfered or chamfered corner areas. The side walls of the strand (2) may be flat, curved or profiled. The strand (2) may be massive or in places, e.g. in the middle, be hollow. The ratio of width to height of the strand cross-section is e.g. in the range of about 1, in particular in the range between 0.7 to 2, as e.g. is common for pallet blocks. The strand (2) has thereby e.g. the rod shape shown in the drawings. Alternatively, the width to height ratio may be significantly greater, thereby giving the strand (2) a board or board shape.

The extrusion press (1) consists of a drying device (3) for the small vegetable parts and an extruder (4), which can be connected to each other via a small parts feeder (6) in the form of one or more suitable conveyors or the like.

In the area of the drying device (3), one or more comminution devices (52, 53) for the small vegetable parts may be present. Before the entrance of the drying device (3), for example, a pre-crushing (52) is arranged, in which, for example, supplied as coarse sawdust or wood chips vegetable small parts are brought to a size suitable for drying. For example, they are coarsely crushed to increase their free surface for subsequent drying. Behind the outlet of the drying device (3) can be post-shredding (53) be arranged, in which the dried vegetable small parts are brought to a maximum particle size, which is suitable for the subsequent extrusion process. In this case, a homogenization of the small parts material and a homogenization of the particle sizes can take place. The shredders (52, 53) are equipped with suitable machinery and tools and may also include measuring equipment for particle size measurement and shredding control and regulation. Alternatively, it is already possible to set the particle size suitable for extrusion in the pre-shredding (52) and to dispense with subsequent comminution (53).

The extrusion press (1) may further comprise a gluing station (50) at a suitable location, e.g. in the conveying direction behind the secondary comminution (52) and in the area of the small parts feed (6). Here, the preferably previously dried vegetable small parts are provided with the binder, e.g. is sprayed on. In a modification of the illustration shown can also be arranged not shown intermediate storage in the form of a silo or other container in the region between the drying device (3) and the extruder (4).

The extruder (4) has an extruder (5) with a downstream heating section (12) and a subsequent cooling section (13), which are arranged one behind the other in the pressing direction (9). At the end of the cooling line (13) or at a distance therefrom, a separating device (14) for the strand (2) may be arranged. This may be, for example, a saw, which divides the strand by the cross sections into a plurality of block-like individual pieces, eg pallet blocks. The extruder (4) may further comprise one or more conveyors or conveyor lines (15) behind the Auskühlstrecke and / or behind the separating device (14) are arranged.

The drying device (3) is used for drying the vegetable small parts before further processing and extrusion. In the drying device, the small parts of your natural moisture content are dried down so far that they are e.g. at the end of the drying a residual moisture content or degree of moisture of about 6 to 20% atro, preferably from about 6 to 14% atro, have. The degree of moisture may also be lower, e.g. up to about 2% atro or higher up to about 20% atro or more. The drying device (3) can be of any suitable design for this purpose.

At the in FIGS. 11 to 13 the embodiment shown, the drying device (3) as a belt dryer (34) is formed. Here, the lying on an air-permeable small parts carrier (36) small parts are dried by a heated dry air stream. This can be done stationary or during the transport of small vegetable parts.

The in FIGS. 11 to 13 shown belt dryer (34) has four drying lines, which are each equipped with at least one endless circulating small parts carrier (36), at least one circulating means (46) for the dry air flow and at least one heating device (44). The four drying lines are housed together in a common machine frame (35). In a modification of the embodiment shown, the number of drying lines may vary. The belt dryer (4) may have only one line or any other number of lines.

The small parts carrier (36) is designed as an air-permeable and perforated, elastic and tensile transport belt, for example, which is guided in an endless loop through the dry line and is set in circulation with a drive (38). The band (36) has a straight and substantially horizontally extending upper strand and an underlying lower strand and is guided over rollers (41) and deflected. The drive (38) is arranged on the output side and can be accompanied by a clamping device with at least one adjustable roller (41), which in FIG. 11 is indicated by the loop representation on the right side.

The small vegetable parts are transported on the upper run and traversed during transport through the heated dry air flow transverse to the Banderstreckung and dried. At the entrance side and at the beginning of the upper run, a feed station (39) is arranged, which is provided with a metering device, e.g. a worm, can be equipped and with the small parts are applied to the upper strand. The bed is preferably uniform and covers the upper run of the band (36) in full area. Laterally, the upper strand is sealed and supported in a longitudinal tape guide (37). The band (36) has such a high inherent stability that the transverse sag is limited. At the end of the upper run a delivery point (40) is arranged, at which the dried vegetable small parts are released from the belt (36) and conveyed in a suitable manner.

In the direction of the upper strand several chambers (48) are arranged one behind the other, through which the upper strand and the plant small parts are transported. In these chambers (48) a dry air flow is generated and directed transversely to the belt surface. The circulation device (46) has several fans (47) or other suitable Luftumwälzgeräte, each of which is connected to one or more chambers (48) and there generate the dry air flow. The eg externally arranged blower (47) generate in the chamber (48) a negative pressure below the upper run of the belt (36). Above the upper run, an air supply (42) is arranged in the chambers (48). This may be an inlet opening for the ambient air, which is closed by a grid or possibly a filter. The fan (47) is connected in each case in the space between the upper and lower run of the belt (36) laterally to the chamber (48) with a suction shaft and is provided on the output side with an air duct (49) through which the exhaust air laden with moisture (43 ) is delivered, possibly to the environment.

The heater (44) may be formed in different and possibly multi-stage manner. In the embodiment shown, a plurality of heating coils (45) are arranged in the flow path of the supply air (42) before reaching the belt upper run, in which the supply air is heated. The heating and the formation of the heating register (45) may be formed in any desired manner. The supply air may e.g. be passed through a heat exchanger or heated by a firing. The heating register (45) can be arranged at a small distance above the upper run and the small parts bed. The supply air flows through the heating register (45) and is heated to the desired drying temperature. In a multi-stage heater (44), e.g. a preheating of the supply air done by a heat exchanger, which is fed by a flue gas condensation from a cogeneration plant.

The drying temperature may be in a range of up to 120 ° C, for example. The heated dry air flows through the small parts bed on the upper strand and thereby takes Moisture on. The chamber area above the belt upper run can be sealed in such a way that in the chambers (48) the supply air can only flow through the heating register (45). The heating registers may in this case have a smaller area size than the chamber base area.

Alternatively, the drying device (3) may be formed as a stationary sieve dryer, in which the small vegetable parts are poured onto tray or pallet-like sieves and are flowed through in a drying oven by heated dry air. Several sieves can be housed in a rack or dolly. In a further modification, the guidance of the dry air flow may be different and need not be guided transversely to the main plane of the small parts carrier (36). There may also be oblique or parallel flow directions.

The extruder (5) may be of any suitable type. In the embodiment shown, it is a ram extruder with a reversing driven pressing member (8), eg a ram. The basic form of such an extruder (5) is for example from the WO 99/48659 A1 or the WO 02/34489 A1 known.

The extruder (5) consists of a with the small parts supply (6) connected filling station (11) for filling the small vegetable parts in a filling and pressing shaft. A recipient (16) adjoins the filling station (11) in the extrusion direction (9), into which the filling material is pushed by a pressing member (8) and thereby compacted. The recipient (16) is formed as a closed channel with rigid and stationary channel walls, which form the strand (2) in the outline and which may have a slight conical extension. Behind the filling station (11), for example in the intermediate space to the recipient (16), a cooling area, for example with a water-cooled channel wall, be installed, which prevents heat transfer from the heating section (13) in the filling station (11).

At the recipient (16), the heating section (13), which is formed by one or more heating channels (17), which may be provided with heaters and in which the strand (2) cured by supplying heat of heating devices of any kind, not shown is, the binder sets and glued the wood small parts. The directly adjacent to the recipient (16) subsequent heating channel (17) may be a Vorheizgang also rigid and stationary channel walls (18), which surround the strand (2) circumferentially tight. The recipient (16) may be part of the extruder (5). As an alternative and as in the embodiment shown, it can at least partially extend into the heating channel (17) or be arranged there. FIGS. 2 to 8 show such embodiments.

The strand (2) is advanced in the embodiment shown intermittently or clocked and pressed. For this purpose, the pressing member (8) is designed as a reciprocating ram connected to a suitable reversing drive (7), e.g. can be designed as a hydraulic cylinder, as an electric crank mechanism or the like.

The extruder (5) further comprises a vaporization device (21), which comprises a steam generator (22) with one or more steam lines (23) and a steam supply (24) for acting on the strand (2). The steam generator (22) produces, for example, a saturated or superheated steam of water or other suitable medium. The generated vapor pressures and temperatures depend on the small parts material, the strand dimensions, in particular the diameter, the applied strand volume and others Specifications and can vary accordingly. Conveniently in practice, for example in the saturated steam generation from water pressures of 5 bar and more, eg 10 bar or more and the associated steam temperatures. The steam is transported via the line (s) (23) to the steam supply (24) and placed there on or in the strand (2).

The steam is supplied to the strand (2) in the manner explained below from the inside with an internal supply (26) through at least one channel-like opening. FIG. 3 shows this variant. Alternatively or additionally, the steam can be supplied from the outside with an external feed (25) to the strand casing according to the in FIGS. 4 to 8 shown variant.

The vapor deposition takes place in these variants preferably in the region of maximum strand density, i. in the region of the recipient (16) and / or the area of the heating channel (17) adjoining in the extrusion direction (9). The vaporization may e.g. be made only in one place and only in the aforementioned area. Alternatively, several vapor deposition sites may be present in the extrusion direction (9), with the vaporization parameters mentioned below being valid for the first vaporization site at the recipient (16) or at the channel region.

The vaporization device (21) further comprises a valve for opening and closing the steam supply, which is connected to a controller and controlled by this. The amount of steam introduced is controlled, for example, via the opening time and / or the opening width of the valve. The controller may be coupled to the drive (7) of the ram (8) and control the valve in response to the drive movements.

In the embodiment of FIG. 3 a hollow strand (2) is produced by means of a pressing mandrel (29) arranged centrally in the recipient (16) and possibly also in the heating channel (17). Alternatively, a plurality of mandrels distributed arbitrarily over the strand cross-section may be present. The press mandrel (29) is on the back by means of a fitting in the machine frame (10) of the extruder (5) releasably held. The ram (8) is provided on the inside with a recess and slides over the press mandrel (29). The press mandrel (29) has a constant over its length and, for example, circular cross-section with a cylindrical shell. Alternatively, the mandrel (29) may have a different cross-sectional shape, for example a prismatic cross-section. Accordingly, the internal cavity in the strand (2) is designed.

The recipient (16) and the heating channel (17) may also have any cross-sectional shape, which may be circular, oval, prismatic or otherwise formed.

In the embodiment of FIG. 3 with the Innenbedampfung (26) is the inside hollow mandrel (29) is a part of the vapor deposition device (21) and has on its jacket, preferably in the region of the free end, a peripheral steam outlet region (27) for steaming the tightly adjacent strand (2) , The jacket here has a uniform contour over the mandrel length. On the front side, the press mandrel (29) is closed, so that the steam preferably exits only radially on the jacket via local steam outlet openings (28) and passes directly into the adjoining strand (2). The steam exit region (27) has a limited length that is shorter than the mandrel length.

At the in FIG. 3 shown embodiment of the press mandrel (29) projects only a little way into the heating channel (17). The steam outlet area (27) is located, for example, at the end of the mandrel and in the entrance area of the heating channel (17). He may alternatively extend a little way back into the region of the recipient (16). Alternatively, the steam outlet region (27) can also be located in an outlet-side subregion of the recipient (16). These are the areas in the extruder (5) in which the strand (2) has the highest compression. In the area of the filling station (11), the mandrel jacket is closed and possibly thermally insulated.

The steam outlet region (27) is at the same time the feed region, to which the strand (2) the steam is supplied. In the strand (2) which is porous by the small-part structure, the vapor can spread somewhat in the axial direction and also penetrate into the strand regions adjoining the feed region (27). The feed area (27) is so far away from the filling station (11) that preferably no steam can penetrate into the filling space. By steaming the strand (2) in the region of its highest density, also the axial steam expansion is limited.

In the in FIGS. 4 to 8 In the embodiment shown, the strand (2) can alternatively or additionally be vapor-deposited from the outside. In the walls of the recipient (16) and / or the subsequent area of the heating channel (17) for this purpose suitable steam outlet openings (28) of any type, size and arrangement are available. These may be, for example, holes or slots in the duct wall, which are connected to distribution channels in the Heinzkanal walls (18) and hereby to the steam line (23). Also in this case, the feed region (27) is limited in length and is located in the outlet region of the recipient (16) and / or in the subsequent area of the heating channel (17). At the in FIGS. 4 to 8 shown design can be dispensed with a press mandrel (29), wherein a solid strand (2) is formed.

The axial length of the steam outlet region (27) or of the steam supply region is limited. The length is e.g. equal to or less than the strand feed length of one to two extrusion strokes. This is the feed length of the strand (2) resulting from the stroke length of 1 to 2 pressing strokes of the pressing member (8). The length of the steam exit region (27) may be e.g. about 150 to 500 mm, preferably about 250 mm. In the preferred embodiment, vaporization of the strand (2) takes place only in the described range. Alternatively, further vaporization areas may be present.

At the in FIGS. 2 to 8 variants shown may be in the channel area at or before the steam supply (24) of the strand (2) in addition and eg from the outside to be heated. The channel walls (18) may for this purpose have heating elements or be heated by the steam from the inside. In the pressing direction (9) behind the steam supply (24) preferably no heating or heating of the strand (2) takes place more. The steam supply (24) is preferably also at the corresponding end of the heating channel (17).

In the variant with the Innenbedampfung (26) consists of the press mandrel (29), for example, a support tube with the fitting at the rear end. At the front free end of the support tube, a steam tube is arranged, which has the same outer contour as the support tube. The steam pipe has an internal steam chamber and a plurality of outlet openings (28) for the steam distributed around the circumference of the pipe. The outlet openings (28) are formed, for example, as radial through-holes in the jacket of the steam pipe. Such through holes are sufficient on their own. she may alternatively be connected to the outside with laterally leading away and, for example, crosswise arranged distribution channels. The distribution channels may be formed, for example, as outside grooves in the jacket, which open at the said through hole.

At the front, the steam pipe at the free front end by a lid or the like. Vapor-tight. At the other end, the steam pipe is flush and flush with the support tube. This may be a detachable connection, e.g. be a screw to remove the steam pipe for cleaning and maintenance purposes and to replace if necessary. Alternatively, a solid compound, e.g. a weld, be present. At this end, there is also disposed a seal for preventing the axial steam escape, e.g. is located at a neck nozzle of the steam pipe, which projects a piece into the support tube via a corresponding recess.

The steam is supplied to the steam pipe via a reduced in diameter relative to the steam pipe internal steam line, which is connected via the said remote controllable valve with the steam generator (22). The steam line is designed, for example, as a rigid feed tube laid in the carrier tube, which is held and fastened here by radial guides. The feed tube protrudes through the seal into the steam chamber. If necessary, it can slide back and forth in the seal to compensate for thermal expansion. At the front side, the feed pipe is open, so that the steam can escape here and be distributed in the steam chamber and can escape through the outlet openings (28) into the strand (2). Due to the thin feed tube, the vapor volume located behind the valve is relatively small. The steam supplied to the strand (2) can be controlled via the valve and its opening times with high accuracy.

Alternatively, the press mandrel (29) as in the illustration of FIG. 3 be designed as a single-stranded steam tube with a single continuous internal cavity. Further, it is possible to supply the steam continuously and independently of the press cycle to the strand (2). The valve ensures an evenly constant steam supply and steam quantity control. A single-stranded mandrel (29) and a throttle valve are particularly suitable for permanent vapor deposition.

The strand (2) is e.g. saturated steam in a controlled amount of steam via the steam outlet region (27) and fed to the feed. The amount of steam and the vapor pressure are matched to the heat capacity of the applied strand area and e.g. so dimensioned that the supplied steam provides in this strand area for the required setting and thereby substantially completely condensed. Excess steam can be substantially avoided, so that the strand (2) on the outside no steam or little steam escapes. On the usual vaporization generators, feedback devices or the like. And the associated disposal problems can be dispensed with. In addition, evaporation losses are avoided.

The amount of steam is at the lower limit so that it is sufficient for the penetration of the entire cross-section of the strand (2) and for the setting of the strand (2) or the binder contained therein in the entire applied strand area. Upwards, the amount of steam is so dimensioned that substantially all the saturated steam introduced into the strand (2) can condense there and that preferably no excess vapor exits the strand (2). It is the aim of avoiding any excess vapor. In practice, this does not always achieve the desired level. It lies within the framework of Invention, when said conditions and ratios are at least substantially achieved.

As a result of the condensation, the heat energy or enthalpy contained in the saturated steam is abruptly released in the impinged strand area and ensures uniform heating and extreme acceleration of the thermal setting reaction of the strand material. The process can be supported by a possibly existing external additional heating in the chamber walls. The hardening and setting process in the strand (2) can be effected solely by the condensation. Compared to the prior art, the Heizstreckenlänge can thereby be significantly reduced and is e.g. about 1.5 m.

The energy required to set the strand (2) is essentially introduced by the vapor. When exiting the steam supply (24) or from the heating channel (17) the setting process in the strand (2) is completed so far that the strand has reached its dimensional stability. This means that the strand (2) shows no or substantially no deformation when removing an external pressure and an external guide. By setting the glue resistance, which ensures the cohesion of the small parts in the strand (2), greater than the internal stresses in the strand (2).

The volume of porous material is capable of accommodating the volume of vapor because, upon contact with the colder chip material offering a very large contact surface of the chips, the condensation process begins immediately and the vapor volume collapses before the mixture leaves the squeeze channel section closed on all sides and the vapor pressure cracks could cause in the product strand. The condensate is homogeneously distributed in the material volume. The cured product is no different from products recognizable without steaming.

This increases the amount of water and product moisture. Provided the condensed water remains about 100% in the product and does not evaporate, e.g. when cooling down before packaging, partially off again, the product moisture increases to about 11.4% atro. for pallet blocks uncritical value.

The steam quantity control is in the embodiment of FIG. 3 provided with a Innenbedampfung (26) from the press mandrel (29) in the contact area with the strand (2), wherein the steam from the outlet openings (28) and possibly the distribution channels directly into the strand (2) penetrates. In the variant of FIGS. 4 to 8 the steam quantity control can also be combined with an external vapor deposition (25) of the strand (2) in the region at the recipient (16) and / or subsequent region of the heating channel (17). The steam quantity control can also be used in conjunction with a combined internal and external vapor deposition (25, 26) of the strand (2).

At the in FIGS. 2 to 8 In the illustrated embodiments, the steam supply (24) is located at the rear end of the heating channel (17) behind the recipient (16) in the pressing direction (9). In the front area, which can form at the same time the recipient (16) or a part thereof, the heating channel (17) in both variants rigid and fixedly arranged channel walls (18) surrounding the strand (2) circumferentially tight and form in its outer contour , where in the region of the channel may possibly have a slight conical or stepped extension.

In the region of the steam supply (24) with the inner and / or outer vaporization (25,26), the heating channel (17) at least a limited movable channel wall (19), which is arranged for example at the top. The mobility may be in a pivotal movement, wherein the front end of the channel wall (19) is obtained in the manner of a hinge on the subsequent fixed wall portion and the rear end can pivot up and down. For the adjustment of the mobility and the channel wall position, an adjusting device (20) is present, which has a suitable controllable drive, for example a hydraulic cylinder. Alternatively, the movable channel wall (19) and the adjusting device (20) may be omitted in favor of continuous solid channel walls (18).

The movable channel wall (19) can be held and locked in the extrusion operation with such a force that it does not evade under normal operating conditions and evades only when an abnormal overpressure occurs in the hollow channel interior.

Alternatively, the movable channel wall (19) can be used as a strand brake in order to produce the counter-pressure required to achieve the strand compaction with respect to the feed force of the pressing member (8). When pressing feed the movable channel wall (19) of the adjusting device (20) with controlled force and possibly a controlled path to the strand (2) is pressed and brakes it by frictional force. This braking effect is present only over a portion of the extrusion stroke until the required compression is achieved and the strand (2) can then be advanced along the entire length. In this period, the channel wall (19) is released and canceled the braking effect.

FIG. 2 shows the subsequent to the heating section (12) Auskühlstrecke (13). This is also formed like a tube or channel and consists of at least one cooling channel (30) in FIGS. 9 and 10 is shown. Several such, for example, modularly formed cooling channels (30) can according to FIG. 2 behind each other be arranged and form a Auskühlstrecke (13) with the desired length. The module or channel length can be for example about 3 m, so that, for example, by two or three modules, a distance of 6 m or 9 m can be achieved.

The cooling channel (30) can be formed by rigid and stationary channel walls (31) and by movable channel walls (32) or wall sections, which are possibly spaced at the adjacent longitudinal edges to form free spaces. The movable channel walls (32) are connected to one or more adjusting devices (33) which can be controlled controlled for advancing and lifting the movable channel walls (32) from the strand (2). The parts are arranged and mounted together on a machine frame (10) possibly connected to the extrusion press (5). The actuators (33) have a suitable drive, e.g. Hydraulic cylinder, which are connected to the aforementioned control of the extruder (5). The adjusting devices (33) are actuated in the extrusion cycle. During the compression phase of the filled small parts material, the movable channel walls (32) are turned on and clamp the strand (2). Once the desired compaction is achieved, open the movable channel walls (32) and release the strand feed. During the return stroke of the extrusion process (8), the strand (2) can be held again.

The channel walls (31,32) can absorb the thermal energy contained in the strand (2) by heat conduction and release by convection to the environment. Furthermore, active cooling of the channel walls (31, 32) with water or other suitable media is possible. The distances or free spaces between the channel walls (31,32) allow evaporation of excess moisture from the strand (2).

In the embodiment shown, the extrusion press (1) includes the described drying device (3), the shredders (52, 53) and the extruder (4). These components each have independent inventive significance. The drying device (3) and in particular the belt dryer (34) shown can alternatively be used in conjunction with a differently configured extrusion press (4), which, for example, according to W02002 / 034489 A1 is trained. The same applies to the comminution (52,53) and their coupling with other drying devices (3) and / or extrusion presses (4). The extruder (4) and in particular the extruder (5) with the described evaporation technique to achieve a dimensionally stable strand (2) after the evaporation can on the other hand be used in conjunction with another drying device (3) or without such a drying device (3). For example, it is possible to process small vegetable parts with a natural moisture content incurred in woodworking, such as wood chips, wood shavings or the like. Such small parts are not dried again separately, but can be fed directly to the extrusion process after mixing with binder. The extrusion and steaming technique described can also be used with vegetable small parts, which have a lower moisture content.

Modifications of the embodiments shown are possible in various ways. This concerns on the one hand the structural design of the extruder (5) and its components, which can be selected arbitrarily. The pressing member (8) may for example be a worm and also provide for a continuous feed. The design of the vapor deposition device (21) and its components is also freely changeable. The same applies to the structural design of the press mandrel (29) and the steam pipe. The targeted and localized steam escape at the press mandrel (29) can also be achieved with a different structural design. Furthermore, you can work with other types of steam, eg superheated steam.

LIST OF REFERENCE NUMBERS

1

Extrusion plant

2

strand

3

drying device

4

Extrusion facility

5

extruder

6

Hardware supply

7

Drive, cylinder

8th

Press organ, press stamp

9

pressing direction

10

machine frame

11

filling station

12

heating section

13

Auskühlstrecke

14

Separator, saw

15

conveyor line

16

recipient

17

heating duct

18

Channel wall firmly

19

Duct wall movable

20

setting device

21

vaporization

22

steam generator

23

steam line

24

steam supply

25

External supply, external evaporation

26

Internal feeder, interior vaporization

27

Feed area, steam outlet area

28

feed

29

Press mandrel, thorn

30

Auskühlkanal

31

Channel wall firmly

32

Duct wall movable

33

setting device

34

Sieve dryer, belt dryer

35

machine frame

36

Small parts carrier, sieve, band

37

Guide, tape guide

38

drive

39

application site

40

delivery point

41

role

42

air supply

43

exhaust

44

heater

45

heater

46

circulation

47

fan

48

chamber

49

airshaft

50

glueing

51

Small parts producer, sawmill

52

precomminution

53

shredding

Claims (15)

Extruder for producing extruded products from small plant parts provided with binders, in particular wood small parts, wherein the extruder (4) comprises an extruder (5) with a filling station (11) and a recipient (16) following in the extrusion direction (9) and one to the recipient ( 16) subsequent heating section (12) with a vaporization device (21) for the strand (2) and a heating section (12) in the pressing direction (9) downstream cooling section (13), wherein the heating section (12) at least one heating channel (17) with a steam supply (24) for the strand (2) and wherein the steam supply (24) is arranged in the strand-forming channel region with substantially rigid channel walls (18). Extruder according to claim 1, characterized in that the recipient (16) is formed as a closed channel with rigid and stationary channel walls, which form the strand (2) in outline and have a slight conical extension, wherein behind the filling station (11) Cooling area is installed, which prevents heat transfer from the heating section (13) in the filling station (11). Extrusion device according to claim 1 or 2, characterized in that the heating channel (17) in the front region of rigid and fixedly arranged channel walls (18) which surround the strand (2) circumferentially tight and form in its outer contour, wherein in the region of the channel possibly has a slight conical or stepped extension. Extrusion device according to claim 1, 2 or 3, characterized in that the steam supply (24) as outer feed (25) to the strand casing or as an inner feed (26) to at least one inner channel in the strand (2) is formed. Extrusion device according to one of the preceding claims, characterized in that the heating section (12) and the vapor deposition device (21) are designed such that the heat energy necessary for setting the small parts in the strand (2) can be introduced essentially by steam. Extrusion device according to one of the preceding claims, characterized in that the heating section (12) and the vapor deposition device (21) are designed such that the strand (2) is dimensionally stable at the end of the vapor deposition device (21). Extrusion device according to one of the preceding claims, characterized in that the heating channel (17) has a length of less than or equal to 1.5 m. Extrusion device according to one of the preceding claims, characterized in that the Auskühlstrecke (13) has a cooling channel (30) which connects to the heating channel (17). Extrusion device according to one of the preceding claims, characterized in that the Auskühlstrecke (13) has an axial length of up to about 9 m. Extrusion device according to one of the preceding claims, characterized in that the cooling channel (30) has fixed and movable channel walls (31, 32) and at least one controllable adjusting device (33) for the movable channel walls (32). Extrusion device according to one of the preceding claims, characterized in that the channel walls (31, 32) of the cooling channel (30) absorb the heat energy contained in the strand (2) by heat conduction and release it to the environment by convection. Extrusion device according to one of the preceding claims, characterized in that the cooling channel (30) has an active cooling of the channel walls (31, 32) with water or other suitable media. Extruder according to one of the preceding claims, characterized in that the cooling line (13) is arranged downstream of a separating device (14) for the strand (2). Extrusion device according to one of the preceding claims, characterized in that the extruder (5) has a drive (7) and at least one movable pressing member (8), in particular a press ram. Extruder according to one of the preceding claims, characterized in that the extruder (4) is preceded by a drying device (3) for the small vegetable parts and a small parts supply (6).

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