DE3028242A1 - Moulding of flat tangled fibre fleece mats - in two strokes in single press without intermediate cooling - Google Patents

Abstract

Moulded parts are produced from flat tangled fibre fleece mats (I) pref. formed from binder-contg. cellulose or lignocellulose fibres in which (I) softened and swollen by heating is compressed by press tools and opt. provided with a decorative surface layer (II). In the process, premoulding and final moulding takes place in 2 stages performed at the same heat in successive strokes in a single press without intermediate cooling and the opt. (II) is permanently joined to the moulded part after final moulding. Also claimed is appts for performing the process having guides for inserting and removing the premoulding tool and permitting its vertical adjustment. The number of process stages and number of tools required are reduced. The energy requirement, cycle times and waste are also reduced giving a better quality prod. with better utilisation of binder.

Description

Method and device for producing molded parts

made of flat random fiber fleece blanks, preferably made of a binder provided cellulose or lignocellulose fibers The invention relates refers to a method and an apparatus for producing molded parts from planes Random fiber fleece blanks, preferably made of cellulose with a binding agent or lignocellulosic fibers.

In the production of molded parts from blanks of random fiber fleece, which consist of cellulose or lignocellulose fibers provided with binding agents, Special care is required, as the nonwovens can be used for example Forming must be softened by / steaming and made formable. Here is the fiber composite caused by the binder largely dissolved, so that during of the deformation process taking place in the heat there is a great risk that the fiber composite is interrupted, whereby in each case the molded body is rejected attack.

It is known (DE-PS 23 38 650) to perform the deformation in a press, in which a step-by-step deformation takes place in that the mold has several, each covering a deformation area with a certain degree of deformation Has ram, which are independent of one another in the order of the degree of deformation be transferred from an open position to a pressed position. Except for the expensive construction of the press and that too tedious and costly processes, it is necessary to precompact the blank in the places at which there is a strong final deformation.

It has therefore recently begun to soften it by heating it up Cut to size by pressing tools that can move against one another, initially by preforming partially and then finally shaped by final molding. To this Purposes are, as is known, two separate molds used by one of which is used for preforming and the other for final shaping. Here is the blank is removed from a stack and placed in a preform after it is softened on a heating station and to a temperature sufficient for deformation has been brought. The preform consists of a known per se with a die and a press equipped with a male mold, the shaping surfaces of which are designed in this way are that the heated and softened blank follow the pre-deformation satisfactorily could. After the pre-deformation has taken place, the intermediate product, i.e. the pre-formed Molded part to be allowed to cool in the preform in order to remove it from this and in the press used for final forming to form the final molded body.

This press, which is used for final forming, also consists of one Die and a male mold, in which a renewed heating of the intermittently cooled Preform must be made so that the final molding between the hot Molding tools can be carried out when the preform is sufficiently softened, and the thermosetting binders of the tangled fiber fleece are finally activated.

If this known method also lead to satisfactory moldings can, it has significant disadvantages, which are once in the multitude of necessary Steps, i.e. the transport of the individual blanks to a heating station, the removal of the heated blank from the heating device and the introduction into the preform, the implementation of the preforming process, the cooling of the intermediate product on a transportable solidified state, the removal of the intermediate product from the preform and the introduction into the finished mold, and the implementation of the finished molding exist. These necessary steps make the deformation very work- and above all time consuming. The main disadvantage, however, is the fact that the blank must be subjected to a double heating, through which the binder is adversely affected because it is after the preform and the cooling by the second heating changes in its property what to a lower binding force and thus tearing of the blank during the Final deformation leads.

The invention is based on the object of the known two-stage Deformation process to eliminate inherent disadvantages, and the process and to train its implementation serving device so that under essential Reduction of the necessary process steps, the pre-forming and the final forming in one and the same heat, i.e. without intermediate cooling of the tangled fiber fleece, can be done.

This object is achieved with a method according to the preamble of the main claim by the features specified in its characterizing part. The subclaims following the method serve the advantageous development the invention according to the main claim.

The device used to carry out the method is in the Claim 6 by in its characterizing Part specified Characterized features, the subsequent subclaims serve the advantageous Further development of the device.

According to the invention, the previously required preforming is used Press superfluous because the heated blank is in the one used for the finished form The press is preformed and finished by inserting a preforming tool into the open finishing press is retracted, through which the blank with the help of a Tool of the finished press is preformed and placed on this tool, so that after the preforming tool has been moved out of the finishing press, this immediately is then closed and the preformed blank to the final Shaped body. "Tool" in the present and future sense is in each case to understand a tool half, that is to say male or female part. Preforms and Forming is done with the help of two tools.

It is advantageous that a finished molding tool is also used for preforming is, so that only three tools are required in the fiction, contemporary method and not, as in the previous state of the art, four tools.

The shared tool is usually the die of final molding.

Because the preforming and final molding in a single press in front of you intermediate cooling is superfluous, so that especially when heated Finished form both the preform and the finished form in one and the same Heat is feasible. The following should also be noted: According to the status of Technique, deformable nonwovens contain two different binders: 1) an irreversibly hardening thermosetting resin that gives the finished part the necessary Gives stability and strength, and 2) a thermoplastic binding agent, that guarantees the required cohesion as a semi-finished product for the tangled fiber fleece and with Preform the preform after its cooling in the state of the art the technique used separate preform press for handling and transport stability confers. Since in the method according to the invention, the preform is not transported needs to be, can be dispensed with its handling and transport stability will: Intermediate cooling with all its disadvantages is not more necessary.

In addition, there are only the following in the method according to the invention Process steps required: removing the blank from a stack and heating the same in a manner known per se with the help of radiant heating, contact heating, High frequency or gaseous heating media, such as superheated steam, either in a heating station located in front of the press tool or in a suitable manner during the transport of the blank from the stack into the finishing press, placing the by heating the softened blank on one tool of the finishing press, Entry of the preforming tool into the press, preforming of the blank in the Press, extending the preform tool and closing the press for the purpose of Final molding. This ensures that the pre-forming and final forming of the blank takes place in successive strokes within one and the same press without The preform has to cool down between the strokes, with the result that that the pre-forming and final forming can take place in one and the same heat.

The method according to the invention thus offers the following advantages: 1) Reduction in the number of procedural steps required; 2) Reduction of the need for tools; 3) Reduction of the energy requirement and the cycle time expenditure, since the intermediate cooling after preforming and reheating before final molding is not required; 4) product improvement, because the preform is heated more homogeneously and better without intermediate cooling than after an intermediate cooling and brief reheating, which leads to improved Deformation behavior during final molding leads. According to the current state of the art show the cooled preform parts, namely in the state of transport and handling capability, Changes in dimensions due to the springing of the material. Since they are in this state in the heated Finished molding tool are inserted, they have poor fit, which on the one hand the renewed warming impaired, on the other hand to additional stress of the preform part when forcibly adapting to the final molding tool at the beginning the final pressing leads.

As a result of the inadequate heating of the preform to this At this point, the thermoplastic binding agents are still largely effective (not yet fully softened) and the preform has insufficient deformability, as a result, cracking is often observed in the finished part; and 5) better Utilization of the duroplastic binder components in the tangled fiber fleece, since the time Shortened between pre-molds and finished molds and thus quality-reducing pre-condensation the binder is lowered.

The method according to the invention also offers the possibility in to retain state-of-the-art deformation aids that have proven themselves in practice.

These are above all preforming tools, their shaping surfaces consist of at least two mutually movable partial surfaces, one after the other are moved into their deformation technically effective end position, and Foil or fabric coverings, the deformation characteristics of which are the mean overlap length the fibers of the random fiber blank is adapted.

Both measures can improve the effectiveness of the preforming will. The effect of the film or fabric coverings can be supported by that they are suspended elastically, for example with the help of springs.

It is particularly advantageous to have one that can be moved into and out of the mold Carrier to use that holds the preform tool, the cold blank and a heating element contains, so that already during the retraction of the carrier in the press the required The blank can be heated. The carrier remains in place the retracted position as the preform tool is opposite the carrier for the purpose the preform can be lowered downwards and the heated one received in it Placed blank with release on the lower tool of the press, so that immediately after extending the carrier, the lower tool, acting as a patrix with the upper tool of the press can come into engagement for the purpose of final molding.

The accompanying drawings show exemplary embodiments the device used to carry out the method, and it means: Fig. 1 schematic representation of the device in the starting position; Fig. 2 representation according to FIG. 1 in the preform position; FIG. 3 shows the representation according to FIG. 1 in the final form; FIG. Fig. 4 is a schematic representation of an altered th device with an extendable Carrier for the preform tool in the starting position; Fig. 5 representation according to 4 in the preforming position; and FIG. 6 shows the representation according to FIG. 4 in the final form.

As FIGS. 1 to 3 show, the device consists of a vertical arranged press 1, which has an upper press tool 3 and a lower fixed Pressing tool 2 has. The upper press tool 3 is through the upper piston of the press 1 movable up and down.

The press 1 is shown in the open position with the preform tool retracted 4, the lower one used to preform the heated blank 6 ' Has surface 4 'which is softer than the shaping surface of the tool 3 of the press 1. The preform tool 4 is arranged on horizontal rails 5, the height-adjustable for engagement of the preform tool 4 with the heated blank 6 are, as shown by the arrows.

The preform tool 4 has on its, the shaping surface 4 'opposite side a recess 4 "into which the tool 3 of the press 1 engages in its downward movement and the preform tool 4 to the tool 2 keeps the press centered. When the tool 3 moves downward, the press 1 becomes the preform tool 4 taken down while adjusting the height of the rails 5 and comes to pressure engagement with the heated blank 6 'for Formation of the preform 6 ″. The tool 3 of the press 1 then moves upwards out and at the same time the rails 5 with the preform tool 4 are after guided above, so that the preform tool 4 can emerge from the press. Thereon As shown in FIG. 3, the tool 3 of the press 1 is again moved downwards until the pressure engagement with the lower tool 2, whereby the preform 6 "to the finished molded body 6 "'is molded.

Below the preform tool 4 are resilient brackets 8.9 for a film-like fabric or the like is provided that when lowering the preform tool 4 is deformed with this and as a detachable intermediate layer between the preform tool 4 and the heated blank 6 'is used.

The operation of the device is as follows.

A cold blank 6 is on a side of the tool 2 of the Press 1 arranged conveyor belt 7, for example a chain conveyor, placed and passed through a continuous furnace 7 in which the blank 6 is heated.

The heated blank 6 'is removed from the conveyor element 7 and placed on the lower tool 2 of the press 1. Then the tool 3 is the Press 1 is lowered and brings the shaping surface while lowering the rails 5 4 'of the preform tool 4 via the film 10 with the heated blank 6' in engagement and thus produces the preform 6 ″ according to FIG. 2. The tool 3 then becomes the press 1 followed by the preform tool 4 moved upwards with upward movement of the Rails 5, and the preform tool 4 is with the clamping device 8, 9 and the Slide 10 extended from the press. Then, according to FIG. 3, the tool 3 is the Press 1 is lowered again and comes into pressure engagement with the preform 6 ″ and deforms it between the tools 3, 2 of the press 1 to the finished part 6 "', the is then removed from the press 1.

Fig. 4 shows the structure of a further advantageous device for Implementation of the method according to the invention. The press 1 is a lower piston press executed. The finishing mold 2 is vertically movable, the corresponding Counter tool 3 arranged in a stationary manner in the press 1.

The box-shaped support part 12 contains the preform tool 4, the with the help of the hydraulically or pneumatically acting lifting cylinders 13 vertically and is movable. The shaping surface of the preform tool 4 has a separate one positionable partial surface 4 "'. As in the device shown in FIGS is located under the preform tool 4, a film or fabric layer 10, which is elastically attached to the support part 12 with the aid of the resilient elements 9. Of the The box-shaped carrier part 12 follows on from the still cold random fiber fleece blank downwards, and is fixed in this position by the holding elements 16. 14th are inlet openings for a gaseous heating medium, for example for superheated steam. As an alternative or in addition, the carrier part 12 can also be equipped with another heating device be equipped, for example with radiant heaters.

The carrier part 12 and the components connected to it are with The help of the fixed to the press 1 arranged guide elements 5, the side of the Tool 3 run horizontally movable.

The carrier part 12 can be inside the press with the help of the stop 15 can be positioned. Fig. 4 shows the starting position of the device.

When the carrier part 12 is extended, the tangled fiber fleece is by means of a not shown stacking device and taken over by the holding elements 16 fixed.

During the retraction of the carrier part 12 into the open press 1, the random-fiber fleece blank is heated and maintains its good deformability.

Fig. 5 shows the device after completing the preforming.

The heated random-fiber fleece blank was removed by opening the holding elements 16 after positioning the carrier part 12 in the press 1 on the lower tool 2 filed. The lifting cylinders 13 have then moved the preform tool 4 downwards and the random fiber fleece blank is formed into the preform part 6 ″.

Finally, FIG. 6 shows the completion of the final molding. after the Lifting cylinder 13 moves the preform tool 4 back into the starting position according to FIG. 4 have transported back within the carrier part 12, will this extended from the press 1 and again fitted with a random fiber fleece blank. During this time, the final molding takes place in the heated tools 2 and 3. Fig. 6 shows the positions of the individual components of the device at the end of the final molding.

Then the piston press is opened and the finished part is removed and the manufacturing cycle is over.

The device described in FIGS. 4 to 6 allows an additional one advantageous development, which is not shown for the sake of clarity Is provided by suitable design of the tool 3, for example by Local undercuts on the tool edge, ensuring that the finished part on the tool 3 is liable, it can be done with the help of ejectors, claws or similar aids placed on the carrier part 12 during the preforming of a subsequent blank and after preforming it is transported out of the press for automatic destacking will.

For the preforming process, it can be useful that the preforming tool 4 optionally has a different temperature than the final molding tools 2 and 3. If the preform tool 4 has a higher temperature, it can be used for an additional Warming up of the random fiber fleece blanks and thus for a shortening of the cycle time care for. Lower temperatures may be useful to reduce the tendency to stick of the not fully compressed preform part on the preform tool, especially intestine if preforming is to be carried out without a film or fabric-shaped intermediate layer.

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Claims (20)

CLAIMS Process for the production of molded parts from flat random fiber fleece blanks, preferably from cellulose or lignocellulose fibers provided with binding agents, in which the cut softened and swollen by heating through against each other movable pressing tools first partially through preforming and then through The final form is finally formed so that it is not possible to use it that the pre-forming and the final forming with one and the same heat in successive Strokes carried out in a single press without intermediate cooling of the tangled fiber fleece will. 2. The method according to claim 1, characterized in that between the tools in the press that are in the open position are used to preform the Tool serving the cutting retracted, with the cutting in pressure engagement and is disengaged again and extended from the press, and that immediately afterwards the tools of the press for the purpose of final molding of the a tool of the press adjacent pre-deformed blank in pressure engagement with one another brought and the finished molding is removed from the press. 3. The method according to claim 1 or 2, characterized in that the The heated blank is placed on the lower tool of the press with the press open is that then the preforming tool under the action of with his Centering back surface engaging upper tool of the press in pressure engagement lowered with the blank, together with the upper tool of the press again is raised and then extended from the press, and that immediately afterwards the upper tool of the press for the purpose of final shaping of the blank with the lower one , as a die serving tool of the press is brought into pressure engagement. 4. The method according to claim 1 or 2, characterized in that the cold cut into one of these fixing, the preform tool and one of the heating the element containing the blank is inserted that the carrier while heating the blank in the open press with centering of the preform tool is retracted to the lower tool of the press that the preform tool towards the carrier as a whole or with at least one of its parts downwards in pressure engagement with the lower die of the press lowered and After the blank has been released, it is placed on the lower tool of the press and again is raised, that the carrier is extended from the open form, and that immediately then the lower tool of the press in pressure engagement with the upper tool the press is raised. 5, method according to one of claims 1 to 4, characterized in that that the tool of the press receiving the preheated blank is used as a pressing tool half is used for preforming as well as for final molding. 6. Device for performing the method according to one of the claims 1 to 5, characterized in that a stationary, with the shape of the molded body corresponding press tools equipped press is provided in which a press tool is designed to be adjustable in height, and that the retraction and extension of the preform tool or the carrier that receives them in the open press, A height adjustment of the preform tool permitting guides are provided. 7. Apparatus according to claim 6, characterized in that when used a preforming tool received directly on the guides, the guides are designed to be adjustable in height. 8. Apparatus according to claim 7, characterized in that the preform tool on its side opposite the shaping surface in whole or in part has the negative contour of the tool of the press assigned to this side, with preferably the vertical or inclined surfaces of the negative contour of the centering of the preform tool in the press. 9. Apparatus according to claim 7 and 8, characterized in that the guides serving for the inward and outward movement of the preform tool are horizontal Guide rails are formed. 10. Apparatus according to claim 9, characterized in that the Lifting movement of the press, the guide rails can also be moved in the lifting direction. 11. The device according to claim 10, characterized in that the Guide rails are resiliently suspended in the stroke direction of the press. 12. The device according to claim 6, characterized in that when used of a carrier receiving the preform tool, the guide rails of the carrier are arranged stationary, and that the preforming tool with respect to the carrier, for example is height adjustable by piston-cylinder arrangements. 13. The apparatus according to claim 12, characterized in that the Preform tool in a manner known per se from several mutually movable There is partial surfaces that successively their end positions during the preforming achieve, and that the preforming takes place in a press train. 14. Device according to one of claims 6 to 13, characterized in that that the shaping surface of the preform tool has a smaller contour than the shaping surface of the corresponding tool of the press. 15. Device according to one of claims 6 to 14, characterized in that that the preform tool at a different temperature, preferably a lower one Temperature when the tools of the press is held. 16. Device according to one of claims 6 to 15, characterized in that that the side of the blank facing the preform tool is replaced by an easily formable one Foil or fabric cover is covered, the deformation characteristics of which is the middle Coverage length of the fibers of the blank is adapted, and during the preforming is deformed with and removed after preforming. 17. Device according to one of claims 6 to 16, characterized in that that the preform tool is provided with heating elements and / or cooling elements. 18. Device according to one of claims 1 to 17, characterized in that that the preform tool on its shaping surface with a heat insulating Layer is provided in order to cool the associated tool of the press prevent. 19. Device according to one of claims 1 to 18, characterized in that that clamping elements are attached to the preform tool, on which a resiliently mounted Cloth, an elastic intermediate layer or the like is held in place at the preforming between the shaping surface of the preforming tool and the surface of the cut 20. Device according to one of claims 6 to 9, characterized that at least two different, one after the other in the open form einm mobile and extendable preforming tools are provided which have different shaping surfaces so that the preforming takes place gradually in at least two press strokes, the preforming tools into it on different sides around the press can be stored retractable.