DE3837467A1 - Pulp mould for the production of bodies from fibrous pulp - Google Patents

Abstract

The pulp moulds previously known for the production of bodies from fibrous pulp consist essentially of a fine wire cloth as a sieve, against which the fibres are applied. This wire cloth must be shaped in a complicated way and, because of the complicated shape and of the pressure occurring, must be supported on the rear side. The pore opening of the wire cloth can often not be guaranteed in an exactly uniform way because of the shaping. In order to eliminate these disadvantages, a spherical-layer sieve is proposed which consists of small spheres joined to each other at their points of contact, the size of the spheres determining the porosity of the sieve.

Description

The invention relates to a suction mold for the production of pulp bodies according to the Preamble of the main claim.

In the manufacture of pulp bodies, ins special egg trays or fruit trays or other Packaging containers, suction molds are used, which have a fine wire screen on the mold side, which is adapted to the shape of the body to be molded. This wire screen is inserted into a molding chamber sets, connect to the suction and pressure lines. By applying negative pressure, the sponge becomes the paper or wood pulp against the sieve sucked, which catches the fabric fibers and firmly holds, while the water mainly through the Form over a vacuum chamber by Förderlei is sucked off. The molded article can then from the shape by switching to overpressure be blown off.

For example in the production of egg trays need the complicated elevations and recesses and side edges of the wall supporting the eggs range of the tray to be formed from the wire mesh to be formed, which is only possible in laborious work is and requires considerable attention. There with the production of the complex corners and edges the diameter of the tissue openings inevitably varies, it always happens that individual  Holes in the fabric are too large so that they are then in can use pulp fibers in these fabric openings. In the prior art it is then necessary to From time to time this can be called a tool to clean fine wire mesh and also arise due to the blockage of the tissue openings not ge wanted irregularities in the finished product, what not very important for egg trays or fruit trays is significant, but with higher quality products Can have meaning.

In addition, the fine wire mesh must go over one visibly their shape also complicated trained support device are supported, which in turn requires considerable expenses.

The invention has for its object a work to create stuff for the suction molds that so far Usual fine wire mesh replaced, easier to produce is no longer prone to constipation and which is so stable in itself that so far required complicated support devices ver be avoided.

This object underlying the invention will solved by the teaching of the main claim.

In other words, according to the Er proposed the actual sieve of the Form suction mold as a fixed tool part, which in itself is stable and to its respective No longer making the tedious and note-taking manual labor is necessary, son the be in a mold once created can be produced as often as required. For this it is suggested  gene that the actual sieve through a ball layer is formed which is based on their contact form tightly connected spheres stands. The production of this spherical film sieve can be done in that the beads in a prefabricated form can be filled in this form are heated so that they adhere to each other Connect contact points so that to create the in large numbers in a production machine Sieve only once the production of Sieve shape is required, in which then again and again by filling and processing the beads each because of the required spherical film screens can be.

By bending a wire mesh in the loading no longer rich in corners, edges and deflections is required to ensure that this Spherical-layer sieve despite a complicated surface design always has the same sieve pore size, regardless of whether on a corner or on a full one Area, so that the drawing in of pulp fibers in un intentionally large sieve pores can no longer occur. As a result, the working time of such a sieve considerably enlarged, as required in between Cleaning work is not necessary. In addition, through Use of a layered sieve a "depth filter" created that is particularly effective.

Because the spherical layer screen keeps its shape in itself is, the previously required are very complicated th support devices in the suction form to the bottom support of a wire mesh screen is no longer necessary dig.  

It is therefore possible with the proposal according to the invention Lich, much cheaper the actual ones Create suction forms and at the same time cost-effectively operation of the machine since Maintenance and repair work to a minimum be reduced.

The spherical layer sieve is preferably made of small metallic balls, their connection by Sintering is achieved. At temperatures below the Melting point of the metal ball are by Diffusion bridges between the metal spheres forms and one from the metal balls in the cold Zu "Agglomerate" is formed by sintering to a body without losing its shape. The throughflow is determined by the choice of the ball size Availability, the filter fineness and strength influences, while the choice of the metal Corrosion resistance is addressed. One are made of steel balls and bronze, but also made of nickel, titanium, aluminum, Tantalum and certain special alloys. When using of bronze metal balls, which are suitable for the The present case is particularly suitable position depressurized in the so-called bulk process, by shaping the beads during sintering tools remain. Become metal balls used with a higher melting point, the Shaping usually by pressing and demolding before sintering. The sintering creates that the metal particles grow together by diffusion processes at temperatures below the melting point After and after sintering, the grain boundaries run beyond the original sphere boundaries. The ge created elements become dimensionally stable,  metallic solid bodies and can be used as self-supporting construction elements. The Pores of the spherical layer sieve thus created mechanically unchangeable due to the sintering Size and location.

But it is also according to another proposal Invention possible to use plastic beads at their contact points with a material fit communicate with each other.

After removing this tool from the manufacturer form is the tool, i.e. so the ball Layer sieve, theoretically infinitely long able to.

While in the previous the use of the inventor ball layer screen according to the invention essentially the production of egg trays or fruit trays has been explained, it is obvious that a sol ches layered sieve also generally at the Her setting of objects made of paper pulp can be set.

Claims (3)

1. suction mold for the production of bodies made of pulp with a sieve arranged on the mold side, which is followed by a suction or pressure chamber, characterized in that the sieve consists of a layer formed by a spherical shaped body consisting of their contact points firmly connected balls is formed, the ball size determines the sieve passage. 2. suction form according to claim 1, characterized records that the spherical layer of sintered metal balls. 3. suction form according to claim 1, characterized records that the spherical layer of art there are spheres of material that are material-locking are interconnected.