DE102006055116A1 - Extrusion unit consists of extrusion system that has heat and cooling extension as well as drying system operating at specific humidity - Google Patents

Abstract

The extrusion unit (1) has an extrusion system (4) that has a drying system (3) for plant-like pieces and a small piece feed (6). The drying system may have a humidity level at one end of dryness between 2-20%, preferably 6-14%. The drying system may be built as a sieve dryer, especially as a strip dryer (34). The extrusion system may have heat extension (12) in the extrusion direction (9) after the cooling extension (13).

Description

The The invention relates to a method and an extrusion press for Manufacture of extruded products having the features in the preamble of the method and apparatus main claim.

conventional Extrusion plants have extrusion presses, which consist of a Extruder, a downstream channel-like heating section and a subsequent cooling section and possibly a saw arranged end, which the strand divided by cross-sections into block-like individual pieces. conventional Heizgänge have with oil or another medium heated and at least partly. adjustable Walls, in a reversing extruder, e.g. a ram extruder, in the pressing rhythm to achieve a braking effect alternately delivered and be lifted off. In this contact heat transfer takes the Abbindevorgang relatively long time, resulting in a correspondingly large length of the heatings and also the subsequent cooling section brings with it. Furthermore is the energy consumption 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 document also shows a variety of different apparatus and process techniques for performing strand evaporation. 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. This seal is problematic, the closure must withstand high mechanical loads of the strand feed in the long term.

It Object of the present invention, a better manufacturing technology for extruded products show.

The Invention solves this task with the features in the method and device main claim. A drying of the vegetable small parts, in particular a purposeful Drying with the claimed degree of drying and / or with a sieve or Belt dryer has several advantages. By preparing the small vegetable parts, e.g. as chips or wood chips, can These are better processed and made into a strand of high quality and uniformity be pressed. In particular, it is also favorable for energy reasons, the Small parts only to be dried as far as for the subsequent extrusion process is required. The finished and set product, e.g. from the strand separated blocks, are relatively insensitive to moisture and can be one considerable residual moisture, e.g. up to 30% atro. Because of Energy balance, it is therefore advantageous to the small parts before extrusion not overly strong to dry and for this to operate a high energy expenditure. A small part drying to a moisture content of about 6-18% atro at the exit of the drying is therefore economical and cost effective. The same applies to the use a screen or belt dryer with which the moisture levels mentioned can be achieved. However, the drying can also be reduced to a lower degree of moisture if required to e.g. 2% atro or a higher moisture level up to about 20% atro or more.

The Small parts can while transport with dry air and with a limited temperature level from e.g. up to about 120 ° Celsius, be applied, resulting in a particularly uniform, fast and economic drying results. The Drying can take place in a continuous process, which is production-related Cheap is and ensures a high output when needed. The drying process can also be interrupted. Leave through the mentioned moisture level The small parts after drying in a silo or a other container caching and further processing at a later time. The Recovery of water and moisture and a product change are low here.

For drying in a belt dryer or sieve dryer, it is advantageous to feed the coming from a small parts producer, such as a sawmill, small vegetable parts of a pre-crushing. As a result, the surface is increased, which is favorable for the subsequent drying. After drying, a post-shredding can follow, with which a maximum particle size of the small parts can be adjusted. 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 process also before the drying take place.

For processing of small parts with the said higher degree of humidity, it is favorable to the Setting the binder in the strand required heat through Steam and preferably essentially exclusively by steam and only on a single, localized site. This has It has been shown that by a steam treatment the consumption of binder or glue can be reduced. Accordingly reduced also the over the sizing addition of water or moisture into the hardware section. Accordingly, the own moisture content can be higher be the vegetable small parts.

The Steam treatment also has the advantage of being faster and more even heating of the Strand and a faster setting allows. Here it is in particular cheap, though with saturated Steam and its condensation is worked in the strand. About the change of State of aggregation can provide a lot of heat energy quickly and evenly in the strand be released. It is advantageous, the amount of steam and the vapor pressure on the heat absorption capacity of the acted upon 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 substantially completely condense can. This can be steam surpluses and a complex and space-consuming steam disposal over Avoid reactors or the like. In addition, the environmental impact lower.

The Steaming of the strand is preferably carried out in such a way that the strand subsequently a high dimensional stability Has. This means that after removing external pressure it will not or only shows negligible deformations. With the claimed technology Is it possible, the setting process in the strand through the steam treatment as far too accomplish that the glue strength is greater than the internal stresses is in the strand. This has the advantage that the heating system is very short can be held, resulting in a substantial reduction of overall length the extrusion press leads. Furthermore can be at the outlet of the heating section and at the end of the steam supply or the Steam treatment immediately connect the cooling section. By Optimum energy utilization can also be achieved by the cooling section shorter to be kept in the prior art, which is also a considerable Reduction of the total length brings the extrusion press with it.

The claimed vapor deposition technology also provides the necessary operational safety when extruding small plant parts with a relative high degree of humidity. This small component moisture can be controlled by the steam and energy supply for the Setting process heated and shared. Besides, has It was shown that by the achieved at the end of the evaporation dimensional stability of the strand further treatment and in particular the pushing through the Auskühlstrecke are unproblematic. In comparative experiments with an incomplete setting by steam supply and with an additional subsequent conventional contact heating through heating channel walls has been shown to crack and dry a high moisture content detachments lead in the strand can. This is possible though by additional activities prevent and is insofar practicable. The preferred evaporation technique offers in contrast however, further benefits.

The Steam quantity control also has the advantage of being unique and reproducible process conditions and for ensures a secure setting of the binder in the strand. on the other hand will be excess steam largely avoided, resulting in a substantial reduction of Construction and operating expenses leads. Degassing generators and vapor recirculation are dispensable. Of the preferably saturated Process steam will also be optimal exploited. It condenses in a controllable strand area, being over the phase or aggregate change in an optimal way and with uniform distribution for setting needed Heat released becomes. Cheap is also the fact that worked with relatively small amounts of steam and thus cost can be. The capacity the steaming system can also be smaller and cheaper be interpreted.

For the steam quantity control is a Innenbedampfung from the coat of the press mandrel directly in the adjacent strand region of particular advantage, because thereby a higher one Process reliability guaranteed becomes. Furthermore is the steamed strand area better limited and controllable. The introduced steam can be optimally utilized. alternative or additionally is an outdoor evaporation possible.

In all cases, it is of particular advantage if the vapor deposition is carried out in the outlet region of the recipient and / or in the subsequent section of the heating channel. 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 beneficial if fixed or rigid channel walls are present in the vaporization area. The setting process is significantly improved and accelerated by the targeted evaporation, whereby the heating channel designed shorter and the length of ge velvet extruder can be significantly reduced. This leads to a higher economic efficiency.

Of the Steam can e.g. continuously or intermittently while the strand is stationary supplied become. In both cases is a steam flow control advantage. The drive can be reversing be and have a press stamp. This has the advantage that the Press punches the strand end gas-tight and closes the steam expansion zone limited to the rear. Alternatively, a continuous extrusion, e.g. with a snail, also possible.

The Inner vaporization from the mandrel shell also has the advantage that with relatively small steam-carrying Volumes can be worked in the mandrel area. This is possible Control the amount of steam particularly well and purposefully. The steam quantity control may alternatively or additionally also in an external evaporation be used. For the setting process, it is beneficial in both cases, if the evaporation takes place in a channel region of the extruder, the one in the has substantial fixed channel wall, which is responsible for the shaping of the strand and possibly also a certain braking effect to achieve the desired Compaction in the strand ensures, if necessary in conjunction with another Braking device, e.g. undeliverable channel walls in the cooling section. For the Process security is there as well Cheap, if the axial feed area the steam is limited in the strand and in particular over a Strand feed length from one to two extrusion strokes extends.

In From a process engineering point of view, the use of saturated steam is out Water cheap. A vapor pressure of about 10 to 15 bar and a corresponding steam temperature have proved to be advantageous. The amount of heat required for setting corresponds to a relatively small volume of vapor and is condensed purposefully released in a limited strand element. Besides, they are these steam parameters for the good and uniform penetration the applied strand area and for the effectiveness of the energy conversion advantageous.

In the dependent claims are further advantageous embodiments of the invention indicated.

The The invention is for example and schematically in the drawings shown. In detail show:

1 : a schematic representation of an extrusion press,

2 : a side view of an extrusion press,

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

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

5 to 8th : a heating channel in perspective view and in various folded side, front and top views,

9 and 10 : a fragmentary representation of a Auskühlstrecke in side view and folded front view and

11 to 13 : a belt dryer in side view, front view and top view.

1 shows an extrusion line in a schematic plan ( 1 ) for producing a strand ( 2 ) from small vegetable parts, especially small wood parts 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. They are supplied by a hardware manufacturer ( 51 ), such as a sawing or planing mill, where they arise as a processing waste, the extrusion press ( 1 ).

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

The extrusion press ( 1 ) consists of a drying device ( 3 ) for small vegetable parts and an extruder ( 4 ), which are connected to one another 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 shredders ( 52 . 53 ) be present for the vegetable small parts. In front of the entrance of the drying device ( 3 ) is eg a pre-shredding ( 52 ), in which for example, the small vegetable parts supplied as coarse sawing or wood chips are brought to a size suitable for drying. For example, they are coarsely crushed to increase their free surface for subsequent drying. Behind the exit of the drying device ( 3 ), a post-shredding ( 53 ), 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 machines and tools and may also have measuring equipment for detecting the particle size and for controlling and regulating the size reduction.

The extrusion press ( 1 ), a gluing station ( 50 ) at a suitable location, eg in the conveying direction behind the post-shredding ( 52 ) and in the area of small parts feeder ( 6 ), exhibit. Here, the preferably previously dried vegetable small parts are provided with the binder, which is sprayed, for example. In a modification of the illustration shown can also still not shown intermediate storage in the form of a silo or other container in the area between the drying device ( 3 ) and the extruder ( 4 ) can be arranged.

The extrusion press ( 4 ) has an extruder ( 5 ) with a downstream heating section ( 12 ) and a subsequent Auskühlstrecke ( 13 ), in the pressing direction ( 9 ) are arranged one behind the other. At the end of the cooling section ( 13 ) or at a distance, a separating device ( 14 ) for the strand ( 2 ) can 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 extrusion press ( 4 ) may further include one or more conveyors or conveyor lines ( 15 ) behind the cooling section and / or behind the separating device ( 14 ) are arranged.

The drying device ( 3 ) is used to dry 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, for example, at the end of drying a residual moisture content or moisture content of about 6 to 20% atro, preferably from about 6 to 14% atro have. The degree of humidity may also be lower and, for example, down 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 11 to 13 the embodiment shown is the drying device ( 3 ) as a belt dryer ( 34 ), educated. Here, the air-permeable small parts carrier ( 36 ) are dried by a heated dry air stream. This can be done stationary or during the transport of small vegetable parts.

The in 11 to 13 shown belt dryer ( 34 ) has four drying lines, each with at least one endless circulating small parts carrier ( 36 ), at least one circulating device ( 46 ) for the dry air flow and at least one heating device ( 44 ) are equipped. The four drying lines are in a common machine frame ( 35 ) housed. 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, flexurally elastic and tensile transport belt, for example, which is guided in an endless loop through the dry line and with a drive ( 38 ) is set in circulation. The ribbon ( 36 ) has a straight and substantially horizontally extending upper strand and an underlying lower strand and is over rolls ( 41 ) guided and diverted. The drive ( 38 ) is arranged on the output side and can by a clamping device with at least one adjustable roller ( 41 ) accompanied in 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 is a Aufgabestelle ( 39 ), which can be equipped with a metering device, for example a screw, and with which the small parts are applied to the upper strand. The bed is preferably uniform and covers the upper strand of the tape ( 36 ) in full area. The upper strand is laterally in a longitudinal tape guide ( 37 ) guided and supported sealed. The ribbon ( 36 ) has such a high intrinsic stability that the transverse sag is limited. At the end of the upper run is a delivery point ( 40 ), on which the dried vegetable 36 ) and be forwarded in a suitable manner.

In the direction of the upper strand are several chambers ( 48 ) arranged one behind the other, through which the upper strand and the plant small parts are transported. In these chambers ( 48 ) becomes one Dry air flow generated and directed transversely to the belt surface. The circulation device ( 46 ) has several fans ( 47 ) or other suitable air circulating devices, each to one or more chambers ( 48 ) are connected and generate there the dry air flow. The externally arranged blowers ( 47 ) generate in the chamber ( 48 ) a negative pressure below the upper run of the band ( 36 ). Above the upper run is in the chambers ( 48 ) each one air supply ( 42 ) arranged. This may be an inlet opening for the ambient air, which is closed by a grid or possibly a filter. The blower ( 47 ) is in the space between the upper and lower strand of the band ( 36 ) laterally to the chamber ( 48 ) is connected to a suction shaft and is equipped with an air shaft ( 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 illustrated embodiment, in the flow path of the supply air ( 42 ) before reaching the belt top several heaters ( 45 ), in which the supply air is heated. The heating and the formation of the heating registers ( 45 ) may be formed in any way. The supply air can for example be passed through a heat exchanger or heated by a firing. The heating registers ( 45 ) can be arranged at a small distance above the upper run and the small parts bed. The supply air flows through the heating coil ( 45 ) and is heated to the desired drying temperature. In a multi-stage heater ( 44 ), for example, a preheating of the supply air through a heat exchanger, which is fed by a flue gas condensation from a heating 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 absorbs moisture. The chamber area above the belt upper run can be sealed in such a way that in the chambers ( 48 ) the supply air only through the heating coil ( 45 ) can flow. The heating registers may in this case have a smaller area size than the chamber base area.

Alternatively, the drying device ( 3 ) be designed as a stationary sieve dryer, in which the small plant 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 does not have to be transverse to the main plane of the small parts carrier ( 36 ). There may also be oblique or parallel flow directions.

The extruder ( 5 ) can be of any suitable type. In the embodiment shown is a piston extruder with a reversing driven pressing member ( 8th ), eg a press stamp. The basic form of such an extruder ( 5 ) is eg from the WO 99/48659 A1 or the WO 02/34489 A1 known.

The extruder ( 5 ) consists of one with the small parts feeder ( 6 ) connected filling station ( 11 ) for filling the vegetable small parts in a filling and pressing shaft. To the filling station ( 11 ) closes in the extrusion direction ( 9 ) a recipient ( 16 ), in which the contents by a pressing member ( 8th ) is pushed and compacted. The recipient ( 16 ) is formed as a closed channel with rigid and stationary channel walls, the strand ( 2 ) in outline and which may have a slight conical extension. Behind the filling station ( 11 ), eg in the space between the recipient ( 16 ), a cooling area, for example, with a water-cooled duct wall, be installed, which is a heat transfer from the heating section ( 13 ) in the filling station ( 11 ) prevented.

To the recipient ( 16 ) the heating section closes ( 13 ) by one or more heating channels ( 17 ), which may be provided with heating devices and in which the strand ( 2 ) is cured under heat of heating devices of any kind, not shown, wherein the binder sets and glued the small wood parts. The directly to the recipient ( 16 ) subsequent heating channel ( 17 ), a preheating with also rigid and fixed channel walls ( 18 ) that are the strand ( 2 ) enclose surrounding tightly. The recipient ( 16 ) can be part of the extruder ( 5 ) be. As an alternative and as in the embodiment shown, it can be inserted into the heating channel (at least in some areas). 17 ) or arranged there. 2 to 8th show such embodiments.

The strand ( 2 ) is advanced and compressed in the embodiment shown intermittently or clocked. For this purpose, the pressing element ( 8th ) is designed as a reciprocating press die, which is provided with a suitable reversing drive ( 7 ), which may be formed, for example, as a hydraulic cylinder, as an electric crank mechanism or the like.

The extruder ( 5 ) further comprises a vapor deposition device ( 21 ), which is a steam generator ( 22 ) with one or more steam lines ( 23 ) and a steam supply ( 24 ) for applying the strand ( 2 ). The steam generator ( 21 ) produces, for example, a saturated or superheated steam of water or other suitable medium. The generated steam pressures and temperatures depend on the small parts material, the strand dimensions, in particular the diameter, the applied strand volume and other specifications and can vary accordingly. Favorable in practice, for example in saturated steam pressures of 5 bar and more, eg 10 bar or more and the associated saturated steam temperatures.

The steam becomes the strand ( 2 ) in the manner explained below from the inside with an internal feeder ( 26 ) fed through at least one channel-like opening. 3 shows this variant. Alternatively or additionally, the steam from the outside with an external feed ( 25 ) are fed to the strand jacket according to the in 4 to 8th shown variant.

In these variants, the vapor deposition takes place preferably in the region of the maximum strand density, ie in the region of the recipient ( 16 ) and / or in the extrusion direction ( 9 ) subsequent area of the heating channel ( 17 ). The evaporation can be made only at one point and only in the aforementioned range, for example. Alternatively, several vaporization sites in the extrusion direction ( 9 ), wherein the evaporation parameters mentioned below for the first evaporation point on the recipient ( 16 ) or at the channel area.

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

In the embodiment of 3 becomes a hollow strand ( 2 ) by means of a centralized ( 16 ) and possibly also in the heating channel ( 17 ) arranged press mandrels ( 29 ) generated. 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 ) held releasably. The press stamp ( 8th ) 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 spine ( 29 ) have a different cross-sectional shape, for example a prismatic cross-section. Accordingly, the internal cavity in the strand ( 2 ) 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 3 with the Innenbedampfung ( 26 ) is the inside hollow mandrel ( 29 ) a component of the vapor deposition device ( 21 ) and has on its jacket, preferably in the region of the free end, a peripheral steam outlet area ( 27 ) for steaming the strand close to it ( 2 ). The jacket here has a uniform contour over the mandrel length. Front side is the press mandrel ( 29 ), so that the steam preferably only on the jacket via there steam outlet openings ( 28 ) emerges radially and directly into the adjacent strand ( 2 ). The steam outlet area ( 27 ) has a limited length that is shorter than the mandrel length.

At the in 3 In the embodiment shown, the press mandrel protrudes ( 29 ) 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 ). Alternatively, he can back to the recipient's area ( 16 ). Alternatively, the steam outlet area ( 27 ) also in an outlet-side section of the recipient ( 16 ) are located. 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 shell is closed and possibly thermally insulated.

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

In the in 4 to 8th illustrated embodiment, the strand ( 2 ) alternatively or additionally vaporized from the outside. In the walls of the recipient ( 16 ) and / or the subsequent area of the heating channel ( 17 ) are suitable steam outlet openings ( 28 ) in any kind, size and arrangement 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 over it with the steam line ( 23 ) are connected. Also in this case, the feed area ( 27 ) is limited in length and is located in the outlet area of the recipient ( 16 ) and / or im closing area of the heating channel ( 17 ). At the in 4 to 8th shown design can on a press mandrel ( 29 ), whereby a massive strand ( 2 ) is formed.

The axial length of the steam outlet area ( 27 ) or the Dampfzuführbereichs is limited. The length is eg equal to or smaller than the strand feed length of one to two extrusion strokes. This is the feed length of the strand ( 2 ), from the stroke length of 1 to 2 press strokes of the pressing member ( 8th ) results. The length of the steam outlet area ( 27 ) may be, for example, about 150 to 500 mm, preferably about 250 mm. In the preferred embodiment, vaporization of the strand only occurs in the described range (US Pat. 2 ) instead of.

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

In the variant with the Innenbedampfung ( 26 ) the press mandrel ( 29 ) For example, from 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 distributed over the pipe circumference (US Pat. 28 ) for the steam. 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. Alternatively, they can be connected on 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.

face side is the steam pipe at the free front end by a lid or Like. Steam-tight. At the other end is the steam pipe flush and aligned with the support tube connected. This can be a detachable connection, e.g. Be a screw to the steam pipe to cleaning and To remove maintenance and replace it if necessary. alternative For example, a solid compound, e.g. a weld, be present. At this End is as well a seal for preventing the axial steam outlet arranged which is e.g. located at a neck of the steam pipe, which one piece in the support tube via a corresponding recess protrudes.

The steam is supplied to the steam pipe via an internal steam pipe, which is smaller in diameter than the steam pipe ( 23 ), which via the said remote controllable valve with the steam generator ( 22 ) connected is. The steam line ( 23 ) is formed, for example, as a laid in the support tube rigid feed tube, which is held and fixed 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. On the front side, the feed pipe is open, so that here escape the steam and distribute in the steam chamber and through the outlet openings ( 28 ) in the strand ( 2 ) can escape. Due to the thin feed tube, the vapor volume located behind the valve is relatively small. For steaming the strand ( 2 ) supplied amount of steam can be controlled via the valve and its opening times with high accuracy.

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

The strand ( 2 ) is saturated steam in a controlled amount of steam over the steam outlet area ( 27 ) or fed to the feed. The amount of steam and the vapor pressure are matched to the heat absorption capacity of the impinged strand area and, for example, so dimensioned that the supplied steam in this strand area provides the necessary setting and thereby substantially completely condenses. Steam surpluses can essentially be avoided, so that the strand ( 2 ) no steam or little steam on the outside. 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 at the lower limit is such 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 is sufficient. To the top, the amount of steam is such that essentially the entire in the strand ( 2 ) introduced saturated steam there condensate ren and that preferably no excess steam on the strand ( 2 ) exit. It is the aim of avoiding any excess vapor. In practice, this does not always achieve the desired level. It is within the scope of the invention if the conditions and conditions mentioned are at least substantially achieved.

By the condensation becomes the heat energy contained in the saturated steam or enthalpy abruptly released in the acted strand area and takes care of a uniform warmth and an extreme acceleration of the thermal setting reaction of the Strand material. The process may be due to a possibly existing external Additional heating in the chamber walls supports become.

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 shortened and is for example about 1.5 m.

The bonding of the strand ( 2 ) required energy is introduced essentially by the steam. When exiting the steam supply ( 24 ) or from the heating channel ( 17 ) is the setting process in the strand ( 2 ) so far completed 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 the setting is the glue strength, which is responsible for the cohesion of the small parts in the strand ( 2 ), greater than the internal stresses in the strand ( 2 ).

The porous Volume of material is able to absorb the volume of vapor because on contact with the colder Chipboard material that has a very large contact surface Offers shavings, the condensation process starts immediately and the vapor volume collapses, before the material mixture the press channel section closed on all sides leaves and the vapor pressure could cause cracks in the product strand. The Condensate falls homogeneously distributed in the material volume. On the cured product There is no difference to products without vaporization.

In order to elevated the amount of water and product moisture. Provided the condensed water remains about 100% in the product and does not evaporate, e.g. on cooling When packing, partially off again, the product moisture increases about 11.4% atro. This is e.g. for pallet blocks less critical Value.

The steam quantity control is in the embodiment of 3 with an interior vaporization ( 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 4 to 8th can the steam quantity control also with an external evaporation ( 25 ) of the strand ( 2 ) in the said area at the recipient ( 16 ) and / or subsequent area of the heating channel ( 17 ) be combined. The steam quantity control is also combined with combined indoor and outdoor steaming ( 25 . 26 ) of the strand ( 2 ) can be used.

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

In the area of the steam supply ( 24 ) with the inside and / or outside evaporation ( 25 . 26 ), the heating channel ( 17 ) at least one limited movable channel wall ( 19 ), which is arranged for example at the top. The mobility may consist in a pivoting movement, wherein the front end of the channel wall ( 19 ) is obtained in the manner of a joint on the subsequent solid wall portion and the rear end can swing up and down. For the adjustment of the mobility and the channel wall position is an adjusting device ( 20 ), which has a suitable controllable drive, for example a hydraulic cylinder. Alternatively, the movable channel wall ( 19 ) and the adjusting device ( 20 ) in favor of continuous solid channel walls ( 18 ) accounted for.

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 pressure in the hollow channel interior occurs.

Alternatively, the movable channel wall ( 19 ) can be used as a strand brake, in order to obtain the counter-pressure required to achieve the strand compaction with respect to the feed force of the pressing element ( 8th ) to create. During the press feed, the movable channel wall ( 19 ) from the actuator ( 20 ) with controlled force and possibly a controlled path to the strand ( 2 ) pressed and brakes it by friction. 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 ) and lifted the braking effect.

2 shows the to the heating line ( 12 ) subsequent cooling section ( 13 ). This is also formed like a tube or channel and consists of at least one cooling channel ( 30 ), which is in 9 and 10 is shown. Several such, for example, module-like cooling channels ( 30 ) can according to 2 be arranged one behind the other and a cooling line ( 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 ) may consist of rigid and fixed channel walls ( 31 ) and movable channel walls ( 32 ) or wall sections are formed, which may be distanced to the adjacent longitudinal edges to form free spaces. The movable channel walls ( 32 ) are equipped with one or more adjusting devices ( 33 ) controlled to deliver and lift the movable channel walls ( 32 ) from the strand ( 2 ) can be controlled. The parts are together at one with the extruder ( 5 ) possibly connected machine frame ( 10 ) arranged and stored. The adjusting devices ( 33 ) have a suitable drive, such as hydraulic cylinders, with the above-mentioned control of the extruder ( 5 ) are connected. 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 ) and clamp the strand ( 2 ) firmly. Once the desired compression is achieved, the movable channel walls ( 32 ) and release the strand feed. During the return stroke of the extrusion process ( 8th ) the strand ( 2 ) are held again.

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

In the embodiment shown, the extrusion press plant ( 1 ) the described drying device ( 3 ), the shredders ( 52 . 53 ) and the extrusion press ( 4 ). These components each have independent inventive significance. The drying device ( 3 ) and in particular the belt dryer ( 34 ) may alternatively be used in conjunction with a different type of extruder ( 4 ) are used, for example, according to the WO2002 / 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 extrusion press ( 4 ) and in particular the extruder ( 5 ) with the described vapor deposition technique to obtain a dimensionally stable strand ( 2 ) after vapor deposition, on the other hand, in conjunction with another drying device ( 3 ) or without such a drying device ( 3 ) are used. 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 is arbitrary. The press organ ( 8th ) can be eg a worm and also provide for a continuous feed. The design of the vapor deposition device ( 21 ) and its components is arbitrarily changeable. The same applies to the structural design of the press mandrel ( 29 ) and the steam pipe. The targeted and locally limited steam outlet 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.

1

Extrusion plant

2

strand

3

drying device

4

Extrusion facility

5

extruder

6

Hardware supply

7

Drive, cylinder

8th

Press organ press die

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

channel 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

feeding, Steam outlet region

28

feed

29

Press Dorn, mandrel

30

Auskühlkanal

31

channel wall firmly

32

channel wall movable

33

setting device

34

sieve-, belt dryer

35

machine frame

36

Small parts carrier, sieve, tape

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

Hardware producers, Sawmill

52

precomminution

53

shredding

Claims (30)

Extrusion plant for the production of extruded products from small vegetable parts provided with binders, in particular wood small parts, whereby the extrusion press ( 1 ) an extrusion press ( 4 ), characterized in that the extruder ( 4 ) a drying device ( 3 ) for the small vegetable parts and a small parts feeder ( 6 ) are connected upstream. Extrusion plant according to claim 1, characterized in that the drying device ( 3 ) produces a moisture level at the end of the drying of about 2-20% atro, especially 6-14% atro. Extrusion plant according to claim 1 or 2, characterized in that the drying device ( 3 ) as a sieve dryer, in particular as a belt dryer ( 34 ), is trained. Extrusion plant according to claim 1, 2 or 3, characterized in that the sieve dryer or belt dryer ( 34 ) at least one moving, air-permeable small parts carrier ( 36 ), in particular a circulating belt, and at least one circulation device ( 46 ) and at least one heating device ( 44 ) for a dry air flow. Extrusion plant according to one of the preceding claims, characterized characterized in that the dry air flow is a temperature of less than or equal 120 ° C has. Extrusion plant according to one of the preceding claims, characterized in that the drying device ( 3 ) a shredding device ( 53 ), in which a predetermined maximum particle size of the dried vegetable small parts is adjusted. Extrusion plant according to one of the preceding claims, characterized in that the drying device ( 3 ) a shredding device ( 52 ), in which the small vegetable parts are roughly pre-shredded. Extrusion plant according to one of the preceding claims, characterized in that the extrusion press device ( 4 ) an extruder ( 5 ) and a heating section ( 12 ) with a vapor deposition device ( 21 ) for the strand ( 2 ) having. Extrusion plant according to one of the preceding claims, characterized in that the extrusion press device ( 4 ) one of the heating section ( 12 ) in the pressing direction ( 9 ) downstream cooling section ( 13 ) having. Extrusion plant according to one of the preceding claims, characterized in that the heating section ( 12 ) and the vaporization device ( 21 ) are designed such that the binding of the small parts in the strand ( 2 ) required heat energy is introduced substantially by steam. Extrusion plant according to one of the preceding claims, characterized in that the heating section ( 12 ) and the vaporization device ( 21 ) are formed such that the strand ( 2 ) at the end of the sputtering device ( 21 ) is dimensionally stable. Extrusion plant according to one of the preceding claims, characterized in that the heating section ( 12 ) at least one heating channel ( 17 ) with a steam supply ( 24 ) for the strand ( 2 ) having. Extrusion plant according to one of the preceding claims, characterized in that the steam supply ( 24 ) as external feeding ( 25 ) to strand casing and / or as internal feeder ( 26 ) to at least one inner channel in the strand ( 2 ) is trained. Extrusion plant according to one of the preceding claims, characterized in that the vapor deposition device ( 21 ) has a steam generator for saturated steam, wherein the steam supply ( 24 ) is controlled to the strand ( 2 ) Steam is supplied in a controlled amount of steam, wherein the amount of steam and the vapor pressure are matched to the heat absorption capacity of the impinged strand area and dimensioned such that they on the one hand for the transverse penetration and the setting of the strand ( 2 ) and on the other hand the amount of steam in the strand ( 2 ) can substantially completely condense. Extrusion plant according to one of the preceding claims, characterized in that the steam supply ( 24 ) in the strand-forming channel region with substantially rigid channel walls ( 18 ) is arranged. Extrusion plant according to one of the preceding claims, characterized in that the steam supply ( 24 ) in the recipient ( 16 ) of the extruder ( 5 ) or in the pressing direction ( 9 ) subsequent channel region is arranged. Extrusion plant according to one of the preceding claims, characterized in that the feed area ( 27 ) the steam supply ( 24 ) has an axial length that is less than or equal to the strand feed length of one to two extrusion strokes. Extrusion plant according to one of the preceding claims, characterized in that the feed area ( 27 ) has an axial length up to about 0.5 m Extrusion plant 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 plant according to one of the preceding claims, characterized in that the heating channel ( 17 ) a limited movable channel wall ( 19 ) and a controllable actuating device ( 20 ) having. Extrusion plant according to one of the preceding claims, characterized in that the cooling section ( 13 ) a cooling channel ( 30 ), which is connected to the heating channel ( 17 ). Extrusion plant according to one of the preceding claims, characterized in that the cooling channel ( 30 ) fixed and movable channel walls ( 31 . 32 ) and at least one controllable adjusting device ( 33 ) for the movable duct walls ( 32 ) having. Extrusion plant according to one of the preceding claims, characterized in that the cooling section ( 13 ) has an axial length of up to about 9 m. Extrusion plant according to one of the preceding claims, characterized in that the cooling line ( 13 ) a separating device ( 14 ) for the strand ( 2 ) is subordinate. Extrusion plant according to one of the preceding claims, characterized in that the extrusion press ( 5 ) a filling station ( 11 ), a drive ( 7 ) and at least one movable pressing member ( 8th ), in particular a press ram having. Process for the production of extruded products from small vegetable parts provided with binders, in particular wood small parts, whereby the extrusion press ( 1 ) an extruder ( 5 ), characterized in that the small vegetable parts before extrusion in a drying device ( 3 ) are dried. Method according to claim 26, characterized in that that the vegetable small parts to a degree of dryness in the final product from about 2-20% atro, especially 6-14% atro, dried. A method according to claim 26 or 27, characterized in that the vegetable small parts in a wire dryer, in particular a belt dryer ( 34 ) are dried during transport with a heated stream of dry air. A method according to claim 26, 27 or 28, characterized in that the small vegetable parts in the extruder ( 4 ) for setting in the strand ( 2 ), wherein the heat energy required for setting substantially by steam, preferably saturated steam, is introduced, wherein the strand ( 2 ) is dimensionally stable at the end of the evaporation. Method according to one of claims 26 to 29, characterized in that the strand ( 2 ) intermittently with a pressing member ( 9 ) is compressed and advanced, wherein the vapor is supplied continuously.