IL43482A - Installation for the production of mouldings and profiles from fibrous vegetable material - Google Patents

Description

43482/2 Installation isfeeeee for the production of mouldings and profiles from fibrous vegetable material Anton Heggenstaller The invention relates to proe»99»e-an«L installation* for the production of mouldings and profiles, e.g. blocks, rods, tubes, or suchlike from waste products of fibrous vegetable matter, such as chips, fibers and so on, whereby a mixture of waste products and a binding agent is compressed into a strip and solidified by the hardening of the binding agent.

Extrusion presses are known where the material fed into the cylinder is conveyed into a tapering pipe by an eccentric-operated piston, whereby the narrowing-down of the pipe causes damming of the material and thus its compaction* With every piston stroke a certain amount of the material is pressed against the newly-formed strip so that in the course of the strip's advance a rather firm bond is established between the individually transmitted batches* At the present state of technology, cold extrusion of the material, consisting of wood chips and sawdust, produces a strip which can be broken up by hand and used as a concentrated fuel. Although the expenditure for the material and production of this fuel is relatively small, its applicability is still rather limited, so that larger amounts of these waste products are not being used up by the employment of the established methods* However, the well known extrusion presses are also bding used to compress waste material that is mixed with binding agents, and so to manufacture1 industrial products. The main field of application is the production of chip boards which are being manufactured both by the continuous extrusion press method (German Patent Specification 949 902) and the flat platen press method (German Patent Specification 967 632). For the production long-fibered chips of desired length and cross section, mixed with a binding agent and extruded under application of heat. he use of short wood chips or sawdust is avoided, as much as possible, in order not to reduce the strength of the chip board and to keep its surface as smooth as possible. However,, also wood waste from planing and sawing work is known to be used, whereb the above mentioned disadvantages have to be accepted and the resulting chip boards be used for special purposes only.

In all these cases of compression under applicatio of heat the extrusion speed must be adjusted to the setting time of the binding agent. When fast-setting binding agents are used, it is customary to cool the feedings zone of the extrusion press and to heat the outlet of this extrusion press in order thereby to avoid a premature hardening of the strip (French Patent Specification 42 225 to additional patent 726 392). In other cases, where a less rapidly hardening setting agent is being used, it is common practice to store the extruded product in air or drying chambers for the elimination of the still present residual moisture (DAS 1 056 538).

However, the problem of a significant utilization of waste products of the wood-processing industry can not be solved by the presently known methods. In the course of the last years the demand for these waste products in their existing form has greatly diminished. On the other hand, the yield of such waste products has increased to a very great *xtent. Thus, the invention is fundamentally concerned with ,the general aim of appropriately working up •pf^eptHMHE^-^K b- the wastes from wood-processing and those from the processing of other vegetable products, and inexpensively to manufacture industrial products of such a quality that they will - invention is to have the processing of this waste material accelerated in comparison with the established way of chip board production, and altogether to achieve a greater efficiency.

Starting from the described method of manufacturing extrusion press products with the aid of binding agents, the mentioned problem could surprisingly be solved by way of extruding the strip without, special or additional application of heat, and outsHe the extrusion press under contractive pressure exposing it to the hardening process, mainlly by application of heat.

Cold extrusion of a mixture of wastes from wood processing or other fibrous vegetable matter with suitable binding agents is a novel procedure. Apparently, this method makes no sense indeed, as cold extrusion can normally not bring about the hardening of the binding agent. But the installation according to the present invention utilizes this apparently irrational method to achieve with it a faster extrusion procedure. The extruded strip, produced this way, is then conveyed into a zone where a hardening of the Binding agent can ensue while a certain pressure on the strip is maintained. This process will undoubtedly extend theoverall length of the whole arrangement, if very long strips are intended to be extruded.

However, a suitable area is usually available in plants of the wood-processing industry, so that this aspect need not be conted as a disadvantage.

The present invention thus consists in a installation for the production of mouldings and profiles fromja mixture of waste products of fibrous. vegetables material with a binding agent which comprises a cold extrusion press being followed by a beatable hardening channel, which channel is constituted by form walls being divided in the longitudinal direotion, said walls being connected to each other and adopted to the cross section of the strip an interval being provided between the heating channel and the press nozzle of the cold extrusion press, extending co-axially to the pipe axis and bein tapered, wdge or cone like.

Similar installations are known (see for example U.S.

Specification 2.592.470 and DDR Specification 11158). However, in all said installations whereby the extrueion press is directly followed by the hardening channel and not separated by an interval as required in the installation according to the present invention. This interval avoids the entering of the possibly not yet sufficiently compacted head of the strip into the hardening installation, particularly at the start of the extrueion procedure. In extrusion presses of this kind an adequate resistance must at first be built up in order to be able to extrude the subsequently fed material in a proper manner.

This takes into account that the head of the strip still lacks sufficient compactness, and therefore ought not enter the hardening installation, to begin with.

In said known installations the cooling cannot be obtained with simple means or alternatively is not sufficient. However in the installation according to the present invention due to the - 5 - 43482/2 Advantageously, the hardening channel has split pipes, the halves of which can be screwed together and which have an inner profile, corresponding with the cross section of the strip. This arrangement of the pipe has the purpose, in case of a work stoppage, to keep the strip from getting caked in the pipe, or else to be able to remove the hardened or even oaked strip from the pipe. Moreover, the tightening screws of the split pipes allow to control the degree of pressure exerted onto the strip while in the hardening zone.

The hardening channel may also be followed by a cooling zone.

Finally, it is recommended to provide a device at the outlet of the hardening installation which will exert back pressure onto the strip. Such devices exist in various forms. This will avoid an undesirable distention of the strip in the direction of the extrusion action. Such a back pressure device can for instance, consist of tapering the pipe or of back pressure springs, cylinders or similar devices which will exert a force onto the head of the strip, counteracting the direction of extrusion.

In order to reduce the work area or high extrusion pressures, the installation according to the present invention provides that the hardening . channel-;-. „ may also consists of a series of pipe like forms which can be shifted from a position do-axial to the extrusion press into a storage position for hardening.

These pipe like forms serve the purpose of holding the strip or guiding it in its advance and, at the same time, exerting a As the conveying of the extruded strip through heated pipe like forms consumes energy, it is recommended) in accordance with the present invention, to operate with an 2 increased extrusion pressure of, say, 700 to 1000 kp/cm . Hereby it is desirable to produce an extruded strip of a density of about 0.6 to 1.2 g/cm . Of course, all these recommended figures are to be taken as examples only, as the individual data might have to be considerably varied dependent on the material used, the extrusion press cross section, the intended use, and so on.

Dependent on the nature of the waste product used, it is possible to operate at a temperature of about 120° to 200°C according to one exemplified embodiment of the invention. Especially suitable waste products are sawdust and wood chips and/or broken-up or else not broken-up particles of flax, hemp, sea-weed, bark, waste from sugar cane or rice produce, vegetable fibres, or suchlike. Thus, utilizing the installation according to the present invention, wastes of agricultural products, too, can be usefully processed.

A cold-hardening binding agent may be used as binding agent.

When the strip, extruded and treated in this way, leaves the hardening channel, it can be processed in the usual manner by either storing the strips or by manufacturing the individual products directly from the strip through cutting, sawing or suchlike* The hardening time of the extruded strip depends on its cross section and the extrusion speed.

- It is of special importance to use a suitable binding agent for the operation of the process in the installation according to the present invention. In this, the use of phenolic resin has proved itself particularly well, as this resin has the characteristic not to set when interior heat is formed in the course of the process in the strip during the cold extrusion. The setting takes place only during the subsequent hardening process, where in one exemplified embodiment heat is applied a purpose. However, phenolic resin, is not the only suitable binding r agent because all that matters is the use of suoh binding agents which will not set during the cold-extrusion operation but during the subsequent hardening process.

In a concrete exemplified embodiment a phenolic resin binder with added emuleion and accelerator was mixed at a rate of about 37.5 parts (by weight) of binding agent to 100 parts of wood chips (dry weight). The extruded strip, about 30mm thick, was subjected to a pressure of ca. 20 kp/cm , at a temperature of about 170°C, over a period of 15 minutes. It is obvious that these data might have to be considerably varied, dependent on the intended use of the raw material, the binding agent, the different cross section of the strip and, finally, any change In the extrusion speed.

The present invention will now be illustrated with reference to the accompanying drawings without being limited by them.

In these drawings: 43482 2 Fig. 1 shows a schematic side view of a cold extrusion press with an attached hardening channel; Pigs. 2 and 3 show cross sections through the hardening channel in two design versions; and Fig. 4 shows a front view of a magazine with several movable pipe forms.

In the exemplified embodiment of Fig. 1, an extrusion press is schematically shown under 1. The waste materials, mixed with binding agents., are fed through the feeding hopper 2 into a cylinder which guidee the to-and-from motion of a piston, propelled by the eccentric drive 3· This piston thrusts the material, fed into the cylinder, in direction of the extrusion nozele 4, the inner section of which tapers either conically or in a wedge shape, so that nozzle 4 builds up a resistance against the thrust of the piston, leading to the compaction of the waste material. The strip comes out of the nozzle and is fed into a hardening installation 6 which is arranged at some interval from the cold-extrusion press 1. This distance serves to have the head of the strip disposed off, because it is not yet sufficiently compacted at the beginning of the extrusion process. Of course, the interval can also be bridged - -β- - by guides to ensure the secure, intromdooion of the strip into the hardening installation. Anyhow, after having reached the desired degree of density, the head of the strip is fed into the hardening insolation 6 and advanced along same through the thrust effect, of the eccentric drive 3. In the examplified embodiment the hardening installation 6 is heated so that in the course of its advance the strip is increasingly hardened. If the hardening process causes the release of moisture vapours, these can be allowed to escape from the hardening install tion through suitable ventilation devices, e.g. vent-holes.

At the outlet of the hardening, installation 6 a back pressure device 10 is located which will cause a limited build-up of pressure in the hardening installation 6 and prevent any disten-tion of the transmitted strip indirection of the extrusion action-» This back pressure device can. consist, for instance, of clamping jaws or a narrowing-down of the inner cross section. On leaving the outlet of the hardening installation 6, the strip can either be divided up in individual portions, say, by sawing, cutting or similarly, or else be carried off by a suitable conveyor system 11, to be stored for a later division into required lengths* The heating 9 of the hardening installation 6 can, of course, be done by various means. For instance, the pipes 7 of the hardening installation 6 can be surrounded by a heating coil or be provided with infra-red radiators. Or else steam may be te into suitable cavities surrounding the strip, or some other contact heating be arranged, able to heat the strip evenly over a long distance.

In the exemplified embodiment the hardening installation Rh wn η split pipe 7, the halves 6f which are connected with each pipe 7 proves to be practical, because a strip, having come, to a stop by, say, a work stoppage, tends tp adhere to the inner face of pipe 7. In such a case In the exemplified embodiment of Fig. 2 the cross section of pipe 7 is practically circular, while in Fig. 3 the pipe has a U-shaped cross section. Obviously, also board or sheet-like forms or any other strip profiles can b4 produced with the described method. In cases where the surface of the strip is so large that an excessive resistance is built up, it is recommended range to provided means of propulsion within the e-eapa-s-e- of the hardening installation 6, as for instance conveyors that act on the strip detracting and aid its advance without e-ft»e-e-¾ri-»g the extrusion pressure* A great variety of articles can be manufactured from the strip, produced according to the invention* A particularly important field of application is the production of distance blocks for pallets or stacking boards. It is common knowledge how such blocks can be produced from wastes of the wood processin industry by compacting them. For this, however, forms are being used into which the material is rammed and where the hardening is achieved by application of heat. Obviously, this method will not allow the application of mass production. ep«**-#*«M de c d-ei tr-oH -t¾¾—com netien-ppoo-e-ew On the other hand, the invention permits an uninterrupted and rapid, and therefore economical roduction of such distance blocks which will have - 11 - 45482 2 9 the advantages of fully adequate strength, surface protection by the binding agent, nailability, and indifference to shock*.

But also quite different articles can be produced by the described method, for instance fence battens, railing posts, toys, moulding for the furniture Industry, boards, sheets and suchlike, so that the disadvantage of the yield of waste products can in practically limitless fashion be more than compensated by the advantage of inexpe sibly producible industrial products. Through the selection of suitable binding agents these products one obtains high density, surface insulation against climatic effects, nailability, loadcarrying capacity, and so on.

In another exemplified emboctment, according to Fig. 4, eeveral pipes 7 are successively brought into a co-axial position with extrusion nozzle 4, by means of a conveyor 12. There they receive a part of the cold-extruded strip which thereupon is cut off so that the following pipe 7 can be loaded with the strip. Upon the cutting off of the strip in a appropriate manner, the pipe which receives the strip is carried away, either sideways or axially, and either stored or led to a hardening installation 14. there, the pipes are picked up by a revolving conveyor 13 and the strips inside them hardened. At point 15 the pipes 7 leave the hardening installation for the removal of the strips and are then returned to the conveyor 12.

The invention is not limited to the presented exemplified embodiments, but covers all variations which, are able to solve the set problem in the same or similar manner.

Claims (5)

- 12 - 43482/3 Claims

1. Installation for the production of mouldings and profiles from a mixture of waste products of fibrous vegetables material with a binding agent which comprises a cold- extrusion press being followed by a heatable hardening channel, which channel is constituted by form walls being divided in the longitudinal direction, said walls being connected to each other and adopted to the cross section of the strip jan interval being provided between the heabing ohannel and the press nozzle of the cold extrusion press, extending co-axially to the pipe axis and being tapered, wedge or cone like.

2. Installation according to Claim 1, wherein a device is provided at the outlet of the hardening channel which has a braking effect on the strip.

3. · Installation according to Claim 2, wherein said braking device is constituted by clamping jaws.

4. Installation according to Claim 2, wherein said braking device is constituted by a reduction of the cross-section of the hardening channel.

5. Installation for the production of mouldings, and profiles, substantially as hereinbefore described with reference to the accompanying .drawings. For the Applicant Dr. Yitzhak Hess