Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2000-01-03
2002-09-10
Yao, Sam Chuan (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S245000, C264S054000, C264S480000
Reexamination Certificate
active
06447627
ABSTRACT:
The invention concerns a procedure for the production of structured parts with cavities consisting of plastics, cellulose or wood granulate, in particular of light-weight construction compound parts, using molding tools. Gas-creating insertion elements are also used in the procedure.
The European patent EP 0 478 535 [B1] already contains a description of plastic-coated parts such as pressure pads and rolls, whereas a further layer for the reduction or removal of adhesion is applied between the part and the epoxy coating in a locally limited procedure. To create cavities in the layer, the layer is filled with fluids or gas, through which the epoxy coating will arch outwards. Consequently, the surrounding area of a roll can be deformed in a desired manner depending on order and size of the cavities.
The German patent application DE 33 24 705 A1 describes a procedure for the production of a sound-absorbing lining with cavities which is made of textiles; this lining is preferably used for the construction of vehicles in order to line sound-sensible fields on the one hand and protect against airborne sound on the other hand. The lining consists of at least two mats that are made of textiles, for example reprocessed wool, that have been fabricated with a binding agent at raised temperature. A plastic part, i.e. a continuous tape, is inserted between the mats. The individual layers are then shed with needles and pressed together. In certain areas, the mats and the continuous tape will be pressed more strongly than in others. During the pressing procedure, the plastic part will melt or create gas at the processing temperature; as a consequence, cavities are created in the areas with smaller compression. The areas with higher compression serve as bindings to stiffen the mats. Furthermore, the mats will be combined area by area by binding agents which become effective under the heat and thus the mat will be bound. The plastic parts are preferably made of polystyrol foam, e.g. of thermoformable plastics or other epoxies with low melting temperature.
The composite material described in the European patent application EP 0 679 501 A1 is particularly known for its use in the production of sealing materials in automobile technology which are used for sealing cavities. This composite material consists of a cavity forming supporting material which again contains a “hot-foaming” material. Hot-foaming means that such a material (e.g. polymerics or copolymers of ethylene and unsaturated acrylic esters) will transform at least partly when they are heating up. The temperature of the supporting material, e.g. with polyamide plastic components, is higher than the temperature at the beginning of the foaming process. The composite material is always fabricated in pre-selected forms; afterwards the form will be placed in an installation site designed for the sealing process. For this procedure, the supporting material has to have at least one, preferably two oppositely arranged apertures, through which the foaming material will exit after the activation; the foam will consequently seal the composite material with the walls. An example for the production procedure of composite material parts would be the extrusion of hot-foaming material between two polyamid foils. The composite material parts are then punched into the pre-selected form, thus combining the two external structures.
The support material will not deform during the production process, it will only lead the foam leaking out through the cavities towards the sealing areas.
Furthermore, there is a process for reaction plastics injection molding as described in the German Disclosure DE-OS 1 926 688 which has been developed for the production of a mold part with a dense outer layer made of a polyurethane thermoset. The tool parts are used in automobile technology and household appliance industry, where big-size high-quality tool parts with thick cross sections required. The reaction plastics injection molding of foaming polyurethane thermoset takes place in a mold with core parts. The core is formed by an elastic wrapper with a cylinder-shaped opening and is filled with a gas or a liquid.
As described in the European Patent Application EP 0 443 364 A2, there is a laminated plastic which consists of stable fixings in a foaming or honeycomb core layer made of a temperature-resistant epoxy. In the core layer, foaming inserts that have a higher density than the core layer are placed near the fixing places. The core layer is coated with at least one layer of a fiber-reinforced temperature-resistant epoxy. Such laminated plastics are preferably used for the construction of interior parts for airplanes. An example for the incorporation of the inserts into the core layer would be the shaping of hollows into the core layer, and inserting a granular material blowing agent. The foaming granular material enters into the core layer and anchors there. Self-cutting tapped bushings can then be screwed into the insert. The blowing agents are used for foaming an epoxy in order to create a foam with high density.
The U.S. Pat. No. 4,113,909 also specifies the production of hexagonal structures of a plastomer to be used in light-weight building boards. A plate of the thermoplast is inserted between two molding boards, then heated up; afterwards the boards are drawn apart. Hereby the thermoplast form, now in heated condition, sticks to the molding boards and the drawn-apart thermoplast material forms a honeycomb structure.
The present invention aims at developing a procedure to manufacture particularly light, but at the same time solid, molding tools, in particular of light-weight construction compound parts.
This goal can be achieved through a procedure for manufacturing structured parts with cavities consisting of plastics, cellulose or wood granulate, in particular to form light-weight compound parts making use of tool parts following the features submitted under claim
1
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The said procedure for the production of structured parts with cavities made of plastics, cellulose or wood granulate using tool parts allows an expansion of the matrix material by inserting pre-shaped gas-creating substances in the matrix material at pre-selected places, and subsequently activating the insertion elements in the tool parts to produce gas, thus creating light-weight macro-cavities, which are preferably filled only with gas and the residue of the blowing agent and not with heavy foam.
The present invention extends the state of the art by offering the possibility to create several, but separately structured macro-cavities inside a matrix material without external gas conduction, which will preferably lead to a honeycomb structure formation with a homogeneous combination with the surface layers.
The said insertion elements which consist of gas-creating substances and a surrounding or solid coating, will be applicated to fiber webs in the form of circular, polygon or ring-shaped discs and implemented as single parts between at least two of the pre-fabricated layers of plastic, wood, or granulated material in double-sided films; these pre-fabricated layers are then inserted into the mold and subsequently coated by injection molding or extrusion or pressing to a homogeneous compound ready to be triggered for gas creation on the implemented inserts for lift-off in order to create the hollow structure.
A further possibility for the stationary fixing of the insertion elements would be the use of textile inserts. During the weaving process, the weaving machine pointedly places the insertion elements in the programmed pattern.
Multiple-staged weaving machines will insert the gas-creating substances in the said offset pattern in two layers. The prefabricated weavings with the included insertion elements positioned in the mold and the left cavity of the mold are filled by injected plastics. The subsequent creation of gas causes a tension of the reinforcement until the yielding point is reached. Due to the reinforcement, the compound part will be of greater solidity.
The submitted p
Nawalanic Frank J.
Yao Sam Chuan
LandOfFree
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