JPH0127175B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for molding articles, and in particular to an apparatus for three-dimensionally deforming and molding a web-like nonwoven fabric containing a binder.

When forming a fibrous material made of a stretchable material such as cellulose chips containing a binder, the article is formed by the action of pressure and heat, and even when the bending radius is relatively small, the material structure changes. It is known that when the elongated length exceeds the average length, the displacement is not necessarily uniform. To solve this problem, cold deformation is performed before the actual forming process. The molds for this purpose are equipped with a rubber cover as an elastic support surface in order to improve the distribution of deformation stresses (Klauditz, E. Stegman, W. Kratz: ``In particular, furniture Research on possibilities of manufacture and properties of wood-shaving molded articles.
and the characteristics of wood shaving
molded acticles, particurly for making
furniture-Cologne and Opladen 1965,
pp.37/38).

A further development of this technique is the known apparatus for producing preforms from lignocellulose and nonwoven fleece in the form of entangled fibers by preforming in molds. The molding surface of this mold is composed of a plurality of relatively movable partial surfaces, and each molding partial surface of at least one of the mold members constituting this mold jointly has at least one It acts on a continuous elastically deformable intermediate layer consisting of a support layer. The shaping forces are transmitted to the fibrous fleece by this supporting layer, in which case this elastically deformable supporting layer, which consists of an endless belt, for example, is fixed to the frame structure or is movable relative to the mold. Retained (West German Publication No. 2701480).

With this known device, flat non-woven fabrics (flat non-woven fabrics are molded materials whose tension and compression forces that can be applied during the molding process are limited) can be curved to a considerable extent without the aforementioned drawbacks. It is possible to form it into a molded article. Most of the locally increased expansion and compression forces are absorbed by the elastically deformable support layer before the forming force is transmitted to the nonwoven fabric. However, if the elongation locally increases further, the inherent elasticity of the support layer is often insufficient to compensate for the elongation, and the support layer becomes unusable within a short period of time. This is disadvantageous from a cost standpoint. Changing the material of the support layer to one with higher elasticity does not have much effect.
The reason is that these supporting layers, which have a stabilizing effect, must easily adapt to the desired three-dimensional shape with considerable local elongation, and any permanent deformation of the material of the supporting layer must occur at the end of each molding process. On the other hand, the stabilizing effect of the support layer (i.e., the ability to distribute this local stretching and compression over the surface) may be offset by the formation of tears and
This is because the length of the fiber coverage in the material to be deformed must be accommodated as much as possible in order to prevent thinning beyond permissible limits. This is only possible with support layers whose inherent elasticity is not too low.

In this way, by using a support layer with relatively low elastic extensibility, it is possible to advantageously locally distribute shear force etc. over the entire portion of the nonwoven fabric to be deformed where the force is applied, but the elasticity of the support layer is , is not recoverable enough to use the same support layer for multiple molding operations with good results.

This drawback is also found in other known devices, in which fabrics of not very high inherent elasticity are used, in particular made of a stabilizing layer or a deformable support layer (DE 2713527).

The problem of the present invention is that the stretch of the stabilizing support layer can be optimally matched to the deformation of the non-woven fabric without the risk of overstretching the support layer, making it possible to use the support layer repeatedly. The objective is to further develop and improve this type of equipment.

This problem is solved by the present invention.

By elastically fixing the stabilizing support layer,
Through the elasticity of the elastic tensioning element, the support layer has the advantage that the stabilizing support layer can follow the movements of the shape until the end of the forming operation, without having to use its own elasticity. This makes it possible to use stabilizing support layers with a low inherent modulus of elasticity, but which are still suitable for locally distributing the forces applied to the surface onto the nonwoven fabric. As a result, the support layer can be formed from a fabric made from fibers with a relatively low modulus of elastic deformation.

As a result of the deformability of the individual meshes of the fabric,
In the case of a reversible behavior of the surface distribution, there are many fabrics with a global deformation rate that primarily takes into account local crushing forces and tension forces within the permissible movement range of the overlapped fibers of the fleece. Therefore, the mesh of the fabric can only be elastically deformed to the extent that the fabric returns to its original shape when the stress is removed.
The ability of fabric to deform even in local areas depends on the type of fabric,
It is determined by the thickness of the fibers and the shape of the mesh, and can be optimally matched to the degree of deformation of the fiber material by means of the stretching element. However, during the whole molding process,
The insufficiency of the elastic mesh deformation of the fabric, with respect to its function as a stabilizing layer, is optimally compensated for by the elastic attachment of the fabric support layer. That is, sufficient local elongation is initially uniformly distributed over a large area of the fibrous material via the added elastic stretching elements before forming forces are transferred to the nonwoven by the fabric layer. The degree of elongation of a stabilizing support layer with a high inherent modulus, such as a rubber elastic layer, is determined by the elasticity of the additional elastic stretching element, which is selected to be at least temporarily less than the force required for elastic elongation of the support layer. can be influenced. Therefore, the overall elongation of the support layer can be reduced and advantageously adapted to the requirements of non-woven fabrics.

The stabilizing support layer can be resiliently secured to the molding device or another component. Therefore, unlike the prior art, the support layer is no longer directly fixed to the mold or to the parts fixed to the mold, but is held by elongated elements with additional elasticity.

A technically simple and advantageous construction of these elongated elements for the stabilizing support layer is in the form of rubber-elastic or viscoelastic strips, or in the form of plastic cords or springs. The elastic modulus or inherent elasticity of this elongated element can be preselected or adjusted such that only a limited holding force is applied to the stabilizing support layer at the beginning of the deformation, and the holding force increases as the deformation progresses. . Initially, the support layer deforms without significant inherent elongation, and elongation of the support layer is only taken into account when the formation progresses further.
It is therefore possible to match the overall elongation of a stabilizing support layer with a high modulus of elasticity to the fiber coverage length of the material, or to use a support layer with a low specific modulus of elasticity. The maximum force applied by the elastic elongation elements to secure the support layer can be selected such that the support layer is not permanently deformed.

Another embodiment of this device, in particular for producing molded articles of complex shape and highly deformed, is for example by means of a pneumatic cylinder or a hydraulic cylinder.
Provides adjustable elastic properties to the elongated elements of the support layer.

By using stretching elements with different elastic properties to suspend or attach the stabilizing support layer, the overall elongation of the stabilizing layer can be further adapted to the fiber coverage length. It is therefore advantageous, for example, to use springs with different moduli of elasticity in order to locally adapt the suspension or mounting forces on the support layer to the conditions of the article to be molded. The same thing can be achieved by distributing identically acting extension elements differently.

Many molding operations are facilitated and advantageous if the stabilizing support layer is fixed to the mold or to the supporting means of the corresponding part only in one direction, i.e. longitudinally or transversely to the elastic elongation elements. can be done.

If the stabilizing support layer is stretched as an endless belt between two or more rollers, a unidirectional elasticity of the suspension is obtained since at least one roller is arranged flexibly.
The flexibility of this device can be adjusted by means of spring elements, pneumatic cylinders, hydraulic cylinders or at least one roller with torque-controllable reversal.

Next, the present invention will be explained based on drawings showing a preferred embodiment.

FIG. 1 shows an apparatus for forming three-dimensional articles from nonwoven fabric. This device comprises a support means or support frame 3 by means of elastic extension means 6, for example four elastic addition elements or springs.
It has a stabilizing support layer 1 attached to it. The elastic extension element 6 is connected to the support frame 3 as a support means by means of adjusting the elastic properties of the spring 6. Preferably, this adjustment means comprises a fluid operated cylinder 5, such as a hydraulic cylinder or a pneumatic cylinder. In FIG. 1, the cylinders are in their final position.
A mat-like fibrous material 2 is placed on the support layer 1. By means of the guide rod 9 and the guide sleeve 4, the support frame 3 can be moved, for example in a horizontal direction, to move the fiber material 2 between the steaming station and the press 7. The press 7 includes a preforming device 8 . The device 8, as shown in FIGS. 2, 3 and 4, consists of an upper mold member 8' and a lower mold member 8''.

In a preferred embodiment, the stabilizing support layer 1 consists of a fabric that has little elasticity in the direction of the stress shown. However, as a result of the mesh deformation, the stabilizing support layer 1 has sufficient shape adjustability in certain directions in order to transmit forming forces to the fibrous material 2 between both mold members.

Since the adjustment means or cylinders 5 fixed to the support frame 3 are in their end or final position, they stress the elastic tensioning means or springs 6, so that the support layer 1 does not sag during transport. The fibrous material 2 can be transferred without any problems.

The operation of the apparatus of the present invention will be explained with reference to FIGS. 2, 3, and 4. FIG. 2 shows a fibrous material 2 in the gap between the upper and lower mold members 8', 8'' in the initial separated state.
2 shows the state of the device of the present invention when it is introduced.

As shown in FIG. 3, the initial stage of forming a three-dimensional article from the fibrous material 2 begins with the downward movement of the upper mold member 8' towards the lower mold member 8''.
During this pressing movement, the adjusting means or cylinder 5
is pressurized and moved to the position shown in FIG. During this process, the tension of the elastic extension means, ie the spring 6, is continuously reduced. The stress in the support layer 1 is thus reduced so that compressive forces are transmitted through the support layer 1 to the fibrous material 2 during the preforming process, which reduces the tension created in the fibrous material 2 during the process. This prevents the formation of tears in the fiber material 2. At the same time, the shape adjustability of the support layer 1 is improved by reducing the longitudinal stress of the support layer 1 and adjusted to the desired preforming process.

The final stage of operation of the device of the invention is illustrated in FIG. At this stage, the upper mold member 8' of the preforming device has been lowered to its lowest position and is close to the lower mold member 8'', forming the fibrous material 2 into a compressed preform part 2'. During the final stage, the elastic stretch adding means or springs 6 are applied to the support layer 1.
Continue to apply a slight tension in the longitudinal direction. This pressure is selected to be commensurate with the forming properties of the fibrous material 2.

After completion of the preforming process, the upper mold member 8' is moved away from the lower mold member 8'' to a spaced open position, as shown in FIG. 2, and pressure is applied to the cylinder 5 to bring it into its final position. This pressure increases the force exerted on the support layer 2 via the spring 6, so that the preformed part 2'
is released from the lower mold member 8'' of the preforming device.
The finished part can be removed from the press 7 by moving the support frame 3 horizontally along the guide rod 9 to the position shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a plan view of an apparatus that is an embodiment of the present invention, and FIGS. 2, 3, and 4 are partial cross-sectional views of the molding device of the apparatus shown in FIG. 1, showing the operating order of the device. be. 1... Stabilizing support layer, 2... Fibrous material, 3...
Support frame (supporting means), 4... Guide sleeve, 5... Fluid actuation cylinder, 6... Elastic extension element (spring), 7... Press, 8... Preforming device, 8', 8''... Mold member, 9...Guide rod.

Claims (1)

Claims: 1. The forming forces of at least one mold half under the action of pressure and heat are transmitted to the nonwoven fabric by at least one stabilizing, elastically deformable support layer, the support layer being is fixed to a support means movable relative to the mold or stationary relative to the mold, comprising a web-like non-woven fabric, preferably a web-like non-woven fabric of cellulose fibers or lignocellulose fibers, comprising a binder; An apparatus for forming articles deformed three-dimensionally from A device for forming shaped articles. 2. Device according to claim 1, characterized in that the elongated additional element is a rubber-elastic or viscoelastic element, such as a spring, a rubber band or a plastic cord. 3. Device according to claim 1 or 2, characterized in that the elongated elements of the support layer can be adjusted in elasticity, for example by means of pneumatic or hydraulic cylinders. 4. Device according to any one of claims 1 to 3, characterized in that the elongated elements used for fixing the same support layer can have different elasticities. 5. A device according to any one of claims 1 to 4, characterized in that the support layer is elastically fixed in one direction, longitudinal or transverse. 6. The device according to any one of claims 1 to 5, wherein the support layer is stretched as an endless belt between two or more rollers, and at least one roller is fixed. , and the roller has reversibility with controllable torque.