Device for forming a mold section onto a workpiece

Abstract

Device for forming a mold section onto a workpiece, comprising a tool arrangement (22) with a first tool part (26) and a second tool part (24), which, in a closed position of the tool arrangement (22), together with the first tool part (26), defines a frame-like mold cavity (32) which can be filled with a molding material to form the mold section, and which bears against a counter surface (30) of the first tool part (26) via a contact surface (28), such that a parting plane (T) is defined between the contact surface (28) and the counter surface (30), characterized in that a cavity is formed on the contact surface (28) which surrounds the mold cavity (32) in a frame-like manner, which borders the parting plane (T) and which is separated from the mold cavity (32) by a gap that is formed in the closed position of the tool arrangement (22) in the region of the parting plane (T) between the two tool parts (24, 26). can be filled with the molding material.

Description

[0001] The invention relates to a device for forming a mold section onto a workpiece, comprising the features of the preamble of claim 1.

[0002] Such a device is known in practice and serves, particularly in the case of a plate-like workpiece, which may be made of a glass sheet or the like, to mold a plastic frame. This frame may be made of polyurethane foam and serves to attach inserts, such as retaining tabs or reinforcing plates, to the plate-like workpiece. The plate-like workpiece may be a cover element of a roof opening system for a vehicle roof and may be made of glass or plastic. The device by means of which the molded section is formed onto the workpiece comprises a tool arrangement with a first tool part, in particular an upper tool, and a second tool part, in particular a lower tool. The two tool parts are movable relative to each other and, in a closed position of the tool arrangement, define a mold cavity for forming the molded section.In this process, the two tool parts abut each other over corresponding surfaces, so that the mold cavity is sealed all around in a mold parting line by compression. Complete sealing in the area of ​​the mold parting line is neither desirable nor possible. Instead, a gap results in the area of ​​the mold parting line, through which the mold cavity is vented when material is introduced to form the mold section. However, this also leads to material penetrating the gap, resulting in an undefined material protrusion or oozing in the area of ​​the gap, which must be mechanically removed in a subsequent process. This mechanical rework can have disadvantages with regard to product quality. Furthermore, mechanical rework is time-consuming and therefore costly.

[0003] From publication EP 2 127 848 A1, a tool arrangement is known which comprises an upper tool and a lower tool, which together form a mold cavity for the frame-like formation of a mold section on a workpiece. The tool arrangement has an additional cavity which is connected to the frame-like mold cavity via a narrow channel.

[0004] From the publication DE 20 2008 005 802 U1, a device for manufacturing a cover for a vehicle roof is known. This device comprises a lower tool and an upper tool, which together form a cavity that is provided with a sprue area and an ejection area.

[0005] The invention is based on the objective of creating a device designed according to the type mentioned in the introduction, which is optimized with regard to mechanical post-processing of the mold section.

[0006] This problem is solved according to the invention by the device with the features of claim 1.

[0007] According to the invention, a device for forming a mold section onto a workpiece is proposed, comprising a tool arrangement with a first tool part and a second tool part, which, in a closed position of the tool arrangement, together with the first tool part, defines a frame-like mold cavity that can be filled with a molding material to form the mold section. In the closed position, the second tool part rests against a counter surface of the first tool part via a contact surface, so that a parting line is defined between the contact surface and the counter surface.In order to provide a tear-off aid for material ejection, the device according to the invention has a cavity formed on the contact surface which surrounds the mold cavity in a frame-like manner, which borders the parting line and which can be filled with the mold material from the mold cavity via a gap which is formed in the closed position of the tool arrangement in the area of ​​the parting line between the two tool parts.

[0008] The device according to the invention thus has an auxiliary cavity which serves solely to hold mold material in the area of ​​the parting line. This material, once hardened, serves to tear off the material protrusion or excess material attached to the actual mold section. Tearing can be performed manually after demolding or automatically when the workpiece with the mold section attached is demolded. This is possible because the material protrusion formed in the gap adjacent to the mold section is thinner than the material that has hardened in the auxiliary cavity. The material film adjacent to the mold section can therefore be torn off flush, so that essentially no disruptive material protrusions remain on the outer surface of the mold section. Further mechanical post-processing can thus be eliminated or, if necessary, reduced to a minimum.This leads to advantages in terms of time, cost and quality compared to previous solutions.

[0009] The device according to the invention can in particular be a so-called RIM (Reaction Injection Molding) device, in which the molding material reacts and hardens in the mold cavity. Preferably, the molding material is a polyurethane material, which is introduced into the mold cavity for reaction by means of a suitable reaction head.

[0010] The workpiece, which can be provided with a molded section by means of the device according to the invention, is in particular a plate-like workpiece, which may be made of glass or a suitable plastic. The mold cavity is preferably designed such that an edge foam in the form of the molded section can be formed onto the plate-like workpiece. The mold cavity then preferably forms a circumferential boundary around the edge of the plate-like workpiece.

[0011] The cavity, by means of which the tear-off aid for the material ejection can be created, can be formed only on the contact surface or also on both sides of the parting line, i.e. on the contact surface and on the opposite surface.

[0012] In a preferred embodiment of the device according to the invention, the cavity is formed by a groove which is formed on the first tool part and which represents an interruption of the contact surface.

[0013] To achieve automated tearing off of the material ejected during demolding of the workpiece, which is provided with the mold section, from the tool assembly, the cavity can be provided with an undercut in a special embodiment of the device according to the invention. The tear-off aid is then held in the cavity during demolding.

[0014] To form the circumferential edge foaming of the workpiece, the mold cavity is designed in a frame-like manner. The cavity for forming the breakaway aid surrounds the mold cavity in a frame-like manner; that is, the cavity for forming the breakaway aid follows the mold cavity for forming the mold section.

[0015] The cavity for forming the breakaway aid is preferably arranged at a distance from the mold cavity for forming the mold section. The gap between the two tool parts, extending between the mold cavity and the cavity, has, for example, a width of between 2 mm and 10 mm parallel to the parting line. In this strip-like area, the film-like section of the material ejection forms, which can be separated from the actual mold section by means of the breakaway aid formed in the cavity.

[0016] To ensure a good grip on the tear-off aid, the cavity preferably has a height between 2 mm and 5 mm perpendicular to the parting line.

[0017] Further advantages and advantageous embodiments of the subject matter of the invention can be found in the description, the drawing and the patent claims.

[0018] An exemplary embodiment of a device according to the invention is shown schematically simplified in the drawing and is explained in more detail in the following description. It shows: Fig. 1 a perspective view of a vehicle roof with a cover element that is provided with an edge foam covering; Fig. 2 a section through a device for shaping the edge foam; and Fig. 3 A top view of a lower tool of the device.

[0019] In Fig. Figure 1 shows a vehicle roof 10, which is provided with a roof opening 12 that can be closed by means of a cover element 14 of a roof opening system (not shown in detail). The cover element 14 is adjustable by means of an adjustment mechanism between a closed position, in which the roof opening 12 is completely filled, and an open position, in which the roof opening 12 is at least partially open.

[0020] The cover element 14 comprises a glass pane 16 made of tempered safety glass (ESG) or laminated safety glass (VSG) and a circumferential edge foaming 18, which accommodates inserts to connect the cover element 14 to the adjustment kinematics.

[0021] The edge foaming 18, which follows the edge of the glass pane 16 in a frame-like manner, is made of a polyurethane material and is applied by means of a Fig. 2 and Fig. 3. Device 20, as shown in more detail, is formed onto the glass pane 16, which represents a workpiece.

[0022] The device 20 for forming the edge foam 18, which represents a mold section, comprises a tool arrangement 22 with a tool part 24 representing a lower tool and a tool part 26 representing an upper tool. In a closed position of the tool arrangement 22, the two tool parts 24 and 26 abut each other via a contact surface 28 of tool part 24 and a counter surface 30 of tool part 26, so that a parting line T is formed between the two tool parts 24 and 26. As further described below, Fig. As can be seen from Figure 2, the two tool parts 24 and 26, in the closed position of the tool arrangement 22, define a mold cavity 32 for forming the edge foaming 18. The mold cavity 32 borders the glass pane 16 inserted into the tool arrangement 22.

[0023] A groove 34 is formed in the contact surface 28 of the tool part 24. This groove forms a cavity and surrounds the mold cavity 32 like a frame, or follows the contour of the mold cavity 32. The groove 34 is located approximately 2 mm to 5 mm from the outer edge of the mold cavity 32.

[0024] When a polyurethane material is introduced into the mold cavity 32 to form the edge foam, it penetrates the groove 34 through a minimal gap between the contact surface 28 and the counter surface 30, forming a cord-like polyurethane section within the groove. This section encloses the edge foam 18 formed in the mold cavity 32 like a frame and is connected to it by a film section, at least before demolding. When the glass pane 16 with the molded edge foam 18 is demolded from the tool assembly 22, the film section is torn off the actual mold section forming the edge foam 18 by means of the cord-like polyurethane section formed in the groove 34. Alternatively, the film section can be torn off the mold section after demolding by manually grasping the cord-like polyurethane section. Reference symbol list 10 Vehicle roof 12 Roof opening 14 Cover element 16 glass panes 18 Edge foaming 20 Device 22 Tool arrangement 24 tool parts 26 Tool part 28 Plant area 30 Counter surface 32 Mold cavity 34 Nut

Claims

[1] Device for forming a mold section onto a workpiece, comprising a tool arrangement (22) with a first tool part (26) and a second tool part (24), which in a closed position of the tool arrangement (22) together with the first tool part (26) defines a frame-like mold cavity (32) which can be filled with a mold material to form the mold section, and which bears against a counter surface (30) of the first tool part (26) via a contact surface (28), so that a parting line (T) is defined between the contact surface (28) and the counter surface (30), characterized by , that a cavity is formed on the contact surface (28) which surrounds the mold cavity (32) in a frame-like manner, which borders the parting plane (T) and which can be filled with the mold material from the mold cavity (32) via a gap which is formed in the closed position of the tool arrangement (22) in the area of ​​the parting plane (T) between the two tool parts (24, 26). [2] Device according to claim 1, characterized by , that the cavity continues on the opposite surface (30). [3] Device according to claim 1 or 2, characterized by , that the cavity is formed by a groove (34) which is formed on the second tool part (24). [4] Device according to claim 3, characterized by that the cavity has an undercut. [5] Device according to any one of claims 1 to 4, characterized by , that the gap between the mold cavity (32) and the cavity parallel to the parting line (T) has a width between 2 mm and 10 mm. [6] Device according to any one of claims 1 to 5, characterized by , that the cavity at a defined angle to the parting plane (T) has a height which is a multiple of the thickness of the gap, and in particular has a height between 2 mm and 5 mm perpendicular to the parting plane (T).

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