DE2557991A1 - Mould core for forming cavities in plastic castings - made of rubber-like material with thin resilient casing - Google Patents

Abstract

Mould core for forming cavities in plastic castings with or without filler materials comprises an elastic core of rubber-like material, with a thin resilient casing which is pref. made of sheet metal and which may be split one or more times in or at an angle to the direction of deformation. Traction forces in the core during removal from the mould are taken up by the casing, and deformation forces due to the unavoidable superficial undulation of the casing caused by its resiliency are transmitted to the core. The core itself is pref. made of synthetic material e.g. silicone rubber. The core need not fill out the whole of the cavity enclosed by the casing, but may be disposed only at the ends of the hollow body. Also, the mould core may consist only of the resilient casing.

Description

Mold core for creating cavities in

Castings The invention relates to novel mold cores for production of cavities in cast parts, especially those made of casting resins.

Such cavities are created in that mold cores prior to potting are inserted at the points where there are cavities in the finished, cast part should be present.

After potting and hardening, these mold cores have to go through a Demolding process can be removed from the casting.

Such mold cores have hitherto essentially been in two versions known: 1. As rigid mold cores made of metal or tool resin, where ai e die The possibility of demoulding is given by the conical design of the surface. These Mold cores have the disadvantage that their production is expensive because of the conicity is. In addition, it is not always desirable that the surface of the resulting cavity is conical in the finished part.

The latter is particularly disadvantageous in those mold cores that have a have a large length in the direction of demolding in relation to their smallest thickness. In addition, the surface waviness of the mold core, which is always present, creates due to its manufacturing process, deformation forces when demolding, the lead to damage to the finished part and wear of the mold core; 2. as elastic mold cores made of flexible material, e.g.

Silicone rubber, rubber, etc. (DT-OS 2 150 085), which are only for one or only a few casting processes are to be used because of their mechanical strength is small compared to the demolding forces.

The aim of the present invention are novel mold cores with which the disadvantages of known mold cores are avoided.

The mandrels of the present invention are essentially characterized characterized in that it consists of an elastic core and a thin, resilient jacket exist. Thanks to this structure, the tensile forces in the mold core when demolding added to this thin, resilient jacket and the deformation forces as a result the unavoidable surface waviness of the mold core shell due to its flexibility passed on to the elastic core. The elastic core of the invention The mold core consists of a flexible material, preferably a plastic (elastomer), such as silicone rubber.

The resilient jacket is preferably made of sheet metal and can can be produced in a simple manner from standard sheet metal profiles.

However, the elastic core does not have to cover the entire length of the jacket fill the enclosed cavity, but can e.g.

also be arranged only at the ends of the hollow body.

It is the same with a corresponding design of the sheet metal profile also possible, the mold core according to the invention only from the resilient sheet metal jacket, thus to produce without an elastic core. It is also possible to make the core from elastic To produce materials in combination with e.g. rigid materials.

The jacket can be slit at suitable points, simply or multiple, with the slots in the demolding direction or at an angle can lie to this. Through these slots, the resilience of the Mold core increased, which is of particular advantage in the case of mold cores with relatively long lengths is in the direction of demolding.

The invention is explained in more detail by the drawing.

Show it: 1 shows a mold core according to the invention from a thin-walled jacket (2) with an elastic core (3) in a cast Plastic part (1); Fig. 2 shows an embodiment of the mold core with a single slit Jacket in the direction of demolding; Fig. 3 shows an embodiment of the mandrel with a lower jacket slit at an angle to the demolding direction; 4 examples of cavity cross-sections, which are easy to manufacture by lining up mold cores according to the invention.

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Claims (5)

Claims: Mold core for creating open cavities in cast parts, in particular those made from filled or unfilled reactive resins or others Plastics, characterized in that it consists of a thin, resilient jacket (2) with an elastic core (3) made of rubber-like material. 2. Molding core according to claim 1, characterized in that the jacket is slotted one or more times in the demolding direction. 3. Mold core according to claim 1, characterized in that the jacket is slotted one or more times at an angle to the demolding direction. 4. Mold core according to claim 1, characterized in that the jacket consists of sheet metal. 5. Mold core according to claim 1, characterized in that the core only partially consists of elastic rubber-like material.