DE3116894C2 - Prepress for the production of preform parts from binder-containing molding compounds made of lignocellulose or the like - Google Patents

Abstract

A method is described in which preforms made of fiber mats or the like. can be produced by pressing with binders. At least one of the tools is provided with an elastically deformable coating. In the case of step-by-step deformation, there is thus the possibility that elastically deformable coating areas experience an optimal formation with low compression and tensile loads in a time-controllable sequence of the application of pressure.

Description

a) that at least one mold half (1,2) several deformation areas (3,4,5) with elastic has deformable coating material,

b) that the individual deformation regions (3,4,5) are independent in time of controllable succession from each other on the flow medium can be acted upon, such that a mat of fibers are drawn into the respective opposite pressing mold and teeth interference with the only partly closed mold while pressed into this can, and

c) that all deformation areas are depressurized when closing the die half and thereby the elastic coatings rest against the surface of the die half (s) in a non-positive and form-fitting manner.

2. Press according to claim 1, characterized in that the during the deformation process the elastically deformable coatings exerted pressures for various ice-covered areas (3,4, S) are different.

3. Press according to claim 1 or 2, characterized in that the elastic coatings within one or more areas (3, 4, 5) from different Materials are made and / or are of different wall thickness.

4. Press according to claim 1 to 3, characterized in that both mold halves (1,2) with elastic Coatings are provided in separate areas (3, 4, 5), which are arranged in such a way that that they overlap at most slightly when the device is closed.

5. Press according to claim 1 to 4, characterized in that the elastic coatings of the areas (3,4,5) can be heated locally differently.

6. Press according to claim 1 to 4, characterized in that the elastic coatings of the areas (3,4,5) have reinforcements in the form of fabric inserts or the like.

The invention relates to a press for producing molded parts from molding compounds containing binders made of lignocellulose or the like, with two mutually movable compression mold halves, of which one has a deformation region, which can be pressurized by a flow medium with a elastically deformable cover material is provided

This known device is used to produce hollow bodies which are open on one side and have straight or inclined ones Boundary surfaces in an optionally heatable form (DE-AS 10 88 698). With this press there is one Die half, namely the male part, in its entirety with the elastically deformable coating material coated, which is sealed at its lower edge A pressure medium can be applied to this through suitable openings. Pressing the molded parts happens in that when the press is closed, the coating material is pressurized and thereby the molding compound is compressed. In this context, materials that are elastically deformable under pressure are for example also more natural or artificial

ίο rubber are mentioned as advantageous materials.

The distances between the two compression-molded parts are dimensioned before pressing so that the free space between them the respectively required filling volume of a molding compound that cannot rise, preferably from with

\ r. wood chips mixed with a binding agent, so that the compaction results in the desired soil or soil. Wall thicknesses of the hollow body arise. What is required is the patrix coated over the entire surface with the deformable coating material, because here it is assumed that molding compounds cannot rise and are to be deformed in one deformation step without the need to maintain constant wall thicknesses or precisely predeterminable compression ratios

In order to produce molded parts that are shaped in a spatially complex manner, it is known to use fiber mats made of cellulose fibers or lignocellulose fibers, which are advantageously precompacted for storage and transport. These are first softened by steaming so that they can be pressed into molded parts when the appropriate pressure and temperature are applied. In zones of strong deformation, strong shear forces occur which cannot be absorbed by the loose connection of the fiber fleece, so that the molded parts are formed in two stages has prevailed, in which the preform is first pressed by preforming and pressing and then the finished part is pressed in a further operation. For the production of preforms from flat fiber mats, a process is known in which each fiber mat is deformed step by step, first at the points where the greatest deformation is intended, and then the other points are deformed (DE-PS 23 38 650). The device used to carry out the method consists of two compression mold halves, each of which has a deformation area with a certain deformation or. Compression rams which cover the degree of compression and which can be brought from an open position into a compression position independently of one another in the order of the degree of deformation or degree of compression. As a result, the initially flat fiber fleece mat can be subjected to the lowest possible tensile and compressive loads, since it can be freely retraced anywhere and adjacent to the areas that are gradually successively subjected to deformation loads while the two press mold halves are moving together.
The high quality that can be achieved in this way for molded parts that are also spatially complexly deformed is clouded by the high outlay in terms of device technology resulting from the large number of press rams to be moved against each other and the associated complex control, with the joint gaps between the individual against each other moving part punches not always lead to trouble-free operation, since they can become clogged with pressing material. This allows a certain amount of maintenance,

which reduces the profitability of the process, not avoid. Another disadvantage of the known device is that especially in spatial heavily deformed parts, i.e. larger deformation depths, accepted relatively large overall heights for the pressing device in the mutually movable part punches which often leads to impractical constructions.

Finally, there is also a device for producing preforms from random lignocellulose nonwovens known, in which also a step-by-step deformation with the help of the tools described above Art takes place (DE-OS 27 Ol 480). The shaping partial surfaces of at least one tool half act here together on at least one elastically deformable, continuous intermediate layer, so that the Deformation forces are transmitted through this intermediate layer to the fiber fleece. The function of this elastic The intermediate layer consists of the absorption of tensile and shear stresses that otherwise exist between the nonwoven to be deformed and the shaping surface of the pressing tool occur, as well as in one Deliberate delay in heat transfer and prevention of contamination of the press tool. However, the high manufacturing costs for the large number of individual press punches are also disadvantageous here, as well as the relatively large overall height.

The present invention is based on the object of providing a device as defined in the preamble of claim 1 type mentioned to improve and further develop that so that preform share can be made from fiber mats essentially according to the method of DE-PS 23 38 650, without the disadvantages of previously used devices, namely high manufacturing costs and large Occur overall height.

This object is achieved according to the invention by what is specified in the characterizing part of claim 1 Features achieved

The fact that, under the condition of the deformation taking place gradually, several and different at least shaping surface sections provided with elastically deformable transfer material one half of the compression molding tool can be deformed bulging by applying pressure, these areas take one of the surface contour of the die half, i.e. the die or patrix, different shape, in a time-controllable order. It can be advantageous here be that first the points of greatest deformation are detected, so that the fiber fleece can be freely tracked towards these is what is sequential equally for when the two mold halves move together approaching other areas applies. In practice, in addition, by means of a pressure medium by means of the coatings Deformable areas begin the deformation of the fiber mat even before the associated Surface section of the pressing tool is drawn to the corresponding surface area of the fiber mat has The deformation process is essentially completed before the two press-forming halves have fully reached their closed end position. This will be used for the deformation process Particularly critical sub-areas brought up to the system on one half of the form, while the rest Areas can still be moved freely and thus ensure adequate tracking of nonwoven material, without inadmissible forces occurring in local sections of the fiber fleece mat when tightening, which would lead to thinning or even tearing of the same.

A staggering of the pressurization of the different areas caused by the elastic Covering material can also be molded is of great importance. A temporal aspect seems advantageous progressive pressurization of the rubber-elastic surface areas, beginning from the point of greatest deformation, subsequently to those of less severe and medium deformation up to towards those with a low degree of deformation. However, other sequential controls are also conceivable, for example those in which individual areas are intermittently pressurized during molding will. It is also advantageous that the elastically deformable during the deformation process Form coatings exerted pressures for different elastic deformation areas differently.

Individual areas can still be used during the molding process can be returned to an unpressurized state. The advantage here is that the rubber-elastic Coatings in the unpressurized state non-positively and positively on the shaping surface of the relevant Press mold half rest, so that they have the desired final shape of the preform part contour in this state fully comply.

A particularly optimal adaptation of different shapes in areas to the molding process with staggered inflation of the rubber-elastic areas on the one hand and through the shaping ones Surface of the compression molding tool on the other hand to the dependent upsetting and shear forces that on the nonwoven material are applied is more advantageous Way possible by using different materials for the elastic covers and / or different wall thicknesses for the individual rubber-elastic coatings, whereby the material change and / or variation of the wall thickness of the coating material is also conceivable within one and the same area (claim 4). This then results Deformation properties that can be optimally controlled for these areas and intermediate contour specifications that can be influenced in any way during the Ansiorm process.

The change in the elasticity of the coating material due to the change in the wall thickness of the same is also conceivable through other measures, for example through different local heating (claim 6) or, for example, by reinforcing the

Covering material by means of local fabric inserts and the like more (claim 7).

For manufacturing reasons they are advantageous the elastically coated areas should preferably be introduced in one mold half Shaping, however, it can be useful that both mold halves with elastic coatings are provided in separate areas, which are arranged so that they are when the device is closed not or only slightly cover (claim 5). This allows for additional freedom gain in the design of an intermediate geometry that becomes effective during the deformation and the load on the fiber mats during the deformation can be additionally reduced and the possibilies before the degree of deformation is increased compared to the previously known.

In the present device, the temporal or spatial graduation of the pressure load by a

5 6

mechanical, electrical or electronic program- F i g. 3 ff way indicated enables example control, for example using a misse, compressed air is a preferably usable pressure microprocessor, which take place with the movement of the medium. The press ram, which actuates the device, is coupled. The press mold halves 1,2 are connected in a known manner

In this way, an automatically running 5 active surfaces (not shown) of a press can be attached Process, which is exactly reproducible, specify and with and are moved vertically against each other, with Change of parameters without great effort, the lower mold half 1 prefers to be fixed

program. The controls required for this are mounted while the upper mold half 2 is the

such as valves, relays, program parts and the like, the required movement stroke is carried out,

easily exchangeable. io After a fiber mat 7, for example, one with

The coordination of press movement and pressure binding agent acted upon mat made of lignocellulose, loading of the elastically withdrawn areas between the two in FIG. 1 shown in the open position can be done so that the press stroke has been continuously inserted mold halves 1 and 2 begins It can, however, also be expedient for the pressing process, where, as in FIG. 2 shows a step press stroke to run in stages and the 15 wise deformation is initiated in the sense that Closing movement of the device for the duration of the initial de-pressure application of one or more elastically to the points of greatest deformation and thereby interrupting the material of the fiber-covered areas or sub-areas 7, as indicated by the arrows in FIG. 2 displayed by exposed on all sides from the outskirts

The invention is to be drawn in the following on the basis of the drawing. The distance between the two mold halves 1,

gen are explained in more detail, the one only example 2 to each other is greater than the thickness of the at each point

Reproduce embodiment. It shows undeformed flat fiber mat 7 in FIG. 1. F i g. 1 is a schematic sectional view through FIG. 3 shows the next deformation step Der

the device for the production of preforms with an elastically coated area 3 is through the bore

compressed air is applied to the two compression mold halves in an extended 25 3 'and takes »balloon-

Position and inserted fiber mat, shaped "shape. This reduces the deformation of the mat 2 shows a representation according to FIG. 1, after the beginning of the formation at the point of the greatest deformation,

of the deformation process when partially closed. As indicated by arrows, can thereby

driven mold halves, further from the peripheral areas of the fiber mat 7

F i g. 3 shows a representation according to FIG. 1 can be retightened in a material because the distance between the

compared to F i g. 2 more advanced pressing condition, both mold halves still at this stage

F i g. 4 shows a representation in a time which is even later than the thickness of the fiber mat 7.

renAusformungsstaat, Fig. 4 demonstrates an even later one

5 shows a corresponding sectional illustration of a brief step in the deformation sequence. The mold half 2

before the end of the formation of the fiber batt and 35 has moved further downwards, whereby the pressure im

F i g. 6 the end stage of the deformation in the case of completely elastically coated area 3 has been reduced. There

dig closed mold. already in the one shown in FIG. 3 shown pressing stage of

According to the embodiment according to FIG. 4 shown halves 1 and 2, the lower mold half 1 the 40 is no additional tensile forces in this area Die and the upper die half 2, the male die bil-pressed material, it is only compacted here is in different elastically covered area 4 separated from each other with compressed air over the Areas 3, 4 and 5 are acted upon by elastically flexible material bore 4 '. As a result, the fiber material, for example a rubber-like film, is covered, 45 tenwerkstoff in the edge area of the greatest deformation their technical values with regard to elasticity are recorded and compressed to such an extent that they produce tensile forces Strength heat resistance pressure absorption and limited can absorb. The minor deformation has the like just started, adapted to the given requirements; the fiber mats required for this. Areas 3, 4 and 5 are deformable material and can be drawn in the direction of the arrow from the outer area of the fiber on particularly exposed areas, that is, during the shaping process. The printing process of the fiber mat 7 critical points, applied, elastically coated area 4 - brought in. The elastic areas 3, 4 and 5 thereby overcome an undesirable dragging of fiber-gripping material can directly onto the molded mat material from the edge area of the largest surface of the press mold half lying with its molding, which would lead to thinning of the preform part in the edge areas being clamped into it or into this area and thus parting into the scrap-shaping surface of the press tool.

be sen. That for the elastically deformable areas 3, The F i g. 5 shows the penultimate stage of the molding 4, 5 rubber-elastic upper material used is exercise, i.e. H. a state shortly before the end of the choice not only fluid-tight along its edge areas in or continuously or discontinuously carried out on the die surface, but there is also 60 baren pressing process. At this point in time, the area S covered by an area S which is inert with respect to the pressure medium via the bore 5 'is also included rial with gas- and / or liquid-tight properties. Compressed air is applied as a result of which in the direction of the arrow the fibers - apart from the sealing fastening of the rubber lamellar mat material in the deformation area of the post-zostic layer in the areas 3, 4 and 5, this is gene. Finally, FIG. 6 shows the final stage of loosely on the surface of the die half and is 65 deformation reached The compressed air from the areas Via bores 3 ', 4' and 5 'with pressure sources 3, 4 and 5, the series of their previous conditions, via which a fluid can be supplied, which a metering impact is drained off and the device in bulging of the mentioned areas in the moved into their end position.

material to the desired final density of the preform evenly compressed, with no significant tensile stresses emerging, since already in the in 5 shows the required mat material from the edge areas into the deformation areas was transported.

Ff>: the procedure described can be additional Deformation aids known per se can be used, such as cover or intermediate layers for the fiber mat 7 with stabilizing pads of different elasticity. The in the F i g. 1 to 6 shown shaping example also explains that the present device requires minimal installation height, so that it can also be used where previously known devices with mutually movable Partial rams can no longer be used due to excessive lifting heights.

For this purpose 3 sheets of drawings

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Claims (1)

'■ -'i ■ χ Claims: 1. Press for the production of molded parts from binders Molding compounds made of lignocellulose or the like, with two mutually movable Die halves, one of which has a deformation region, which with a through a Flow medium is provided with an elastically deformable coating material that can be acted upon, thereby marked,