Connecting device for the positive reception of a connecting element in a cast object taking into account material-specific shrinkage

Abstract

The connecting device for the positive and non-positive integration of a rotationally symmetrical connecting element (1) into a cast object (11), characterized in that it comprises the following aspects: A receiving device (4) with a rotationally guided guide structure (7); a driver element (2) on the connecting element (1), wherein the driver element (2) can be introduced into the guide structure (7) by a rotary movement. The guide structure (7) is designed in such a way that it enables a positive locking depending on a material-specific shrinkage behavior, wherein the geometry of the connecting element (1) and the receiving device (4) is designed such that that the connecting device is functionally scalable and remains adaptable to different object geometries.

Description

Technical area

[0001] The technical design concerns the detachable connection of rotationally symmetrical connecting elements with cast objects made of polymeric, ceramic, or mineral materials. The connection is made without the use of adhesives or tools and takes into account the material-specific shrinkage behavior of the casting material used (9) to enable positive and non-positive locking. State of the art

[0002] No technical joining devices are known in the prior art that enable the positive or non-positive integration of joining elements (1) into cast objects (11) while structurally considering the material-specific shrinkage behavior of the casting material (9). Known methods are limited to simple applications without technical locking, such as handicrafts involving paper or cardboard. Task of technical design

[0003] The goal is a stable, reusable connecting device that enables the manually detachable integration of a rotationally symmetrical connecting element (1) into a cast object (11) without adhesives or tools. The shrinkage behavior of the casting material (9) that occurs during curing is structurally compensated by the geometry of the connecting device, thus achieving a precise locking fit. Solution

[0004] The connecting device comprises a receiving device (4) with a rotationally guided guide structure (7) into which a driver element (2) of the connecting element (1) can be screwed in a force-fitting and form-fitting manner. The guide structure (7) is geometrically designed—e.g., stepped, inclined, or spiral—to compensate for different shrinkage behaviors and enable secure locking. Special features and advantages • Adhesive-free, manually removable connection • Reusability of the connecting element (1) • Positive and mechanically stable locking • Compensation of material-specific shrinkage behavior of different casting materials (9) • Reproducible production using elastomeric silicone mold (6) • Simple and efficient implementation in the casting process Example of implementation and drawing explanations

[0005] To ensure that the connecting element (1) is locked precisely in the receiving device (4), it is necessary to take into account the material-specific shrinkage during curing.

[0006] The following table shows examples of the required minimum groove widths depending on the casting material used (9), assuming a target groove dimension of 3 mm after complete curing. The values ​​are based on typical shrinkage rates of engineering materials: Table 1: Calculated groove width before shrinkage for different materials material Shrinkage rate [%] Required groove width [mm] Epoxy resin 1,5 % 3.05 mm Plaster (model plaster) 0,8 % 3.02 mm Ceramic (air-drying) 6,0 % 3.19 mm Concrete (fine concrete) 0,5 % 3.02 mm Polyurethane resin 1,2 % 3.04 mm UV-curing resin 2,5 % 3.08 mm

[0007] The materials mentioned are examples; the guide structure (7) can be adapted to different shrinkage behaviors.

[0008] The required groove width b0 results from the desired target dimension b and the material-specific shrinkage rate s according to the following calculation formula: b0=b1−s

[0009] Where b is the desired target dimension (e.g., 3 mm) and s is the shrinkage rate as a decimal (e.g., 0.05 for 5%). For a target dimension of 3 mm and a shrinkage of 5%, the following results: b0=3mm1−0.05=3.16mm

[0010] The groove widths are therefore deliberately adjusted depending on the material type to ensure the locking effect through a positive and non-positive connection. This material-based differentiation represents a central element of the technical design.

[0011] Optionally, the groove-side adjustment can also be achieved by means of an inclined guide structure (7), in which the friction point is located further up or down depending on the material.

[0012] To ensure the precise locking of the connecting element (1), hereinafter referred to as the ball (1), the material-specific shrinkage during curing must be taken into account in the holding device (4). The following figures show the individual steps and components of the technical solution. Fig. 1: Exploded view of the connecting device with spherical element (1), grid structure (3), and receiving unit (4). The driver element (2) on the ball (1) is clearly visible. Fig. 2: Assembled view after inserting the ball (1). The ball (1) is locked into the cast object (11) by manual rotation. Fig. 3: Locking mechanism along the stepped guide structure (7) • Top: Insert the driver element (2) into the groove. • Middle: Rotational movement of the ball (1) along the guide structure (7), which is adapted to the specific material. • Bottom: Form-fitting end position at a defined step contour (8). Depending on the casting material used (9), the ball (1) sits firmly on a suitable step. This creates a noticeable click and reliably secures the ball. Fig. 4: Top view of the fully engaged position. The ball has been rotated along the guide structure; as a result, the driver element (2) is now fully in the locked position. Fig. 5: Comparison of the embodiments for compensation of shrinkage: • Variant A - Multi-level gradation: Allows differentiated locking for various materials with different shrinkage behavior, e.g., casting materials (9) such as epoxy resin, plaster, and concrete. Each step contour (8) represents a potential anchor point. • Variant B - Sloping transition surface: A uniformly inclined guide structure (7) allows stepless adjustment to continuous shrinking. • Variant C - Simple power amplifier: Designed for a specific material with a precisely defined target dimension. The ball (1) engages precisely at a point on the step contour (8). Fig. 6: Positive model (5) for producing the silicone mold (6). Contains all functional elements such as the mounting fixture (4) and guide structure (7) for the subsequent ball joint (1). Serves as a template for molding the silicone mold (6). Fig. 7: Molded silicone mold (6) (negative mold) after removal of the positive model (5). This elastomeric mold forms the technical geometry for the subsequent production of the cast object (11) with integrated surround (10) and a positive locking connection along the guide structure (7). Fig.8: Bar chart graphically depicting the required groove widths for various casting materials (9) as a function of their shrinkage rate. The dashed line marks the target dimension of 3 mm, and the bars show the calculated groove width for each material.

[0013] This representation allows for complete traceability of the technical implementation as well as the material-specific adaptation to ensure a positive connection.

[0014] The ladybug design shown in the figures serves solely as an example to illustrate the joining technology. The technical design is not limited to this external design, but encompasses all forms in which the described mechanical joining device is used – regardless of the design, decoration, or purpose of the cast object. List of reference symbols

[0015] Reference symbol designation 1 connecting element (e.g. ball) 2 Driving element (e.g. nose, projection) 3 locking structure (groove guide, profile track) 4 Mounting device 5 Positive model for making the silicone mold 6 Silicone mold (flexible negative mold made of elastomer) 7 Guide structure (along the locking structure) 8 step contour (multi-step groove / end stop) 9 Casting material (e.g. epoxy resin, plaster, concrete) 10 Inlet area for the connecting element 11 Cast object

Claims

[1] The connecting device for the positive and non-positive integration of a rotationally symmetrical connecting element (1) into a cast object (11), characterized by that it includes the following aspects: A receiving device (4) with a rotationally guided guide structure (7); a driver element (2) on the connecting element (1), wherein the driver element (2) can be introduced into the guide structure (7) by a rotary movement. The guide structure (7) is designed in such a way that it enables a positive locking depending on a material-specific shrinkage behavior, wherein the geometry of the connecting element (1) and the receiving device (4) is designed such that that the connecting device is functionally scalable and remains adaptable to different object geometries. [2] Connecting device according to claim 1, characterized by , that the management structure (7) is designed in such a way that that it has at least one geometric section, which is designed as a stepped, inclined or spiral track, to enable a controlled rotational movement of the driver element (2) to the locking position. [3] Connecting device according to claim 1 or 2, characterized by , that the guide structure (7) has at least one step contour (8), in which the driver element (2) engages positively when a defined position is reached, thereby ensuring secure, mechanically stable locking. [4] Connecting device according to one of the preceding claims, characterized by , that the management structure (7) is designed in such a way that its geometry compensates for different material-specific shrinkage behavior of different casting materials and thus ensures secure, form-fitting locking regardless of the casting material used. [5] Connecting device according to one of the preceding claims, characterized by that a casting mold (9) with a negative structure of the guide structure (7) and the step contour (8) is used. [6] Connecting device according to one of the preceding claims, characterized by , that the guide structure (7) has an inlet area (10) with adjustable dimensions in order to to facilitate the insertion of the driver element (2). [7] Connecting device according to one of the preceding claims, characterized by , that the driver element (2) is positively attached to the connecting element (1); that it engages in a step contour (8) when rotated; without the use of glue or tools. [8] Use of a connecting device according to one of the preceding claims for the detachable integration of decorative or functional components in polymeric, ceramic or mineral cast objects.

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