Levelling insert for glass injection tools

0001The invention relates to a leveling insert for injection molding tools for overmoulding a glass pane according to the preamble of claim 1.

State of the art:

0002In glass encapsulation, glasses such as vehicle windows are placed in injection molds and completely or partially encapsulated with plastic molding compounds in order to form a seal, for example. The glass pane must be reliably sealed with respect to the casting mold in order to form a defined cavity or so that no casting material contaminates the workpiece or the glass pane or so-called flashing occurs.

0003Due to manufacturing-related thickness tolerances and geometric deviations of the glasses, the brittle glass material breaks again and again if the seal acts too strongly on the glass or plastic oversprays on the glass pane if the influence is too weak. This in turn means that splinters have to be removed manually from the injection molding machine or the plastic from the pane, which is laborious. In both cases, this unnecessarily ties up labor and wastes resources, resulting in costly production stoppages and higher manufacturing costs.

0004In order to avoid this, an attempt is made to react to this on the tool side.

0005Depending on the component geometry, a separately cut tool insert called a glass saddle can be used, for example, which can be mechanically changed in position relative to the glass with screws, washers or hydraulically, whereby dimensional and geometric deviations can only be compensated to a limited extent. However, the use of such a glass saddle is limited by the fact that not every product can be equipped with such a glass saddle. In addition, the production and maintenance costs are relatively high.

0006Another way to compensate for glass tolerances is to use plastic inserts that are screwed into the tool. However, these are heavily stressed by the working temperatures of up to 200°C and the large number of pieces in series production, so that the inserts have to be replaced frequently as wear parts in order to avoid leaks during injection molding or to prevent the so-called flash that occurs as a result .

0007From the<patcit id="pcit0001" dnum="DE202019100414U1"><text>DE 20 2019 100 414 U1</text></patcit> plastic inserts are also known in which no separate fixing elements such as the previously customary screws for fixing and loosening the sealing element are necessary, although here too there is wear on the compensating element due to high working temperatures and, moreover, high costs for the injection molding tool for producing such plastic inserts comes.

Object and advantages of the invention:

0008In contrast, the object of the invention is to propose a leveling insert for injection molding tools for overmoulding a pane of glass, which enables the injection molding tool to be operated more economically.

0009Starting from a leveling insert of the type mentioned in the introduction, this object is achieved by the features of claim 1 . Advantageous embodiments and developments of the invention are possible as a result of the measures mentioned in the subclaims.

0010Accordingly, a leveling insert according to the invention is characterized in that at least one metal sheet, in particular steel, preferably high-grade steel, is formed.

0011Metal, especially steel, is particularly resistant to temperature changes, pressure and abrasion when compared directly to most plastics. At the same time, contrary to expectations, it turned out that the glass is no more damaged by scratches or the like with leveling inserts made of metal than with the use of plastic inserts.

0012It is also conceivable that the leveling insert is designed as a stack of the two or more metal sheets in an embodiment with two or more metal sheets. The use of several thin metal sheets has the advantage that you do not have to have several prefabricated inserts of different dimensions ready, but you can easily add the sheets and stack them on top of each other or remove them from the stack of the leveling insert until the required height of the leveling insert is reached is.

0013By combining different sheet thicknesses, almost any height can be achieved and fluctuations that occur for each glass can be easily compensated.

0014In a preferred embodiment, at least one metal sheet has a corrugated surface structure and/or a surface structure that deviates from a flat surface in order to absorb pressure on the flat sides of the at least one metal sheet, in particular through elastic deformation. If the surface structure is skilfully selected, the metal sheet can deform under pressure in such a way that this pressure is at least partially compensated, whereby the pressure on the glass is reduced and glass breakage is counteracted. Since the metal sheet initially only deforms in the areas with higher pressure, the metal sheet also automatically adapts to the shape of the glass and compensates for fluctuations in glass thickness and glass geometry.

0015Also possible is the combination of metal sheets that are flat and metal sheets that have a surface structure that differs from a flat surface, that is, for example, are corrugated or arched.

0016The at least one metal sheet preferably has a wire-eroded, laser-cut or water-jet-cut contour. With the help of such contours, the metal sheets can be positioned evenly one above the other and adapted to the article contour in the injection mold. Contours that are produced in other ways are also conceivable.

0017At least one fastening element in the form of a socket, a pin, a threaded bolt or a clip is preferably introduced onto the at least one metal sheet. This ensures that the metal sheet does not slip during the clamping of the glass pane and during the spraying process, so that permanent quality assurance can be guaranteed.

0018According to the invention, an injection mold for overmoulding a glass pane, which has a mold for receiving the glass pane to be overmoulded, which can be separated into at least two mold parts along a parting plane, at least one of the mold parts has at least one leveling insert as described above. For overmoulding, the glass pane is placed on the at least one leveling insert and clamped between the molded parts. Plastic molding compound is pressed onto the glass in a resulting cavity, with the leveling insert compensating for small manufacturing-related thickness tolerances and geometric deviations of the glass.

0019In a preferred embodiment, at least one leveling insert, in particular two leveling inserts, each consisting of at least one metal sheet is/are provided, which is/are arranged on at least one side of the parting plane and/or on both sides of the parting plane. With an arrangement of two or more leveling inserts, in particular on both sides of the glass pane, deviations in the glass geometry can be compensated even better and plastic overspray on the glass or glass breakage can be avoided even better.

0020The mold and/or at least one of the mold parts preferably has a receiving device adjacent to the parting plane of the injection mold for receiving and holding the glass pane during overmolding and/or for forming an overmolding area to be filled during overmolding. Such a measure can ensure that the position and size of the encapsulations are always the same, so that rejects can be kept to a minimum for these reasons.

0021The mold and/or at least one of the molded parts preferably has an insert receiving device which is connected to the receiving device and/or is adjacent to the receiving device and/or is integrated into the receiving device and/or is adjacent to the parting plane, the insert receiving device for receiving the at least one leveling insert is designed so that the glass pane to be held is at least partially on one of the leveling inserts, in particular in an embodiment with two or more metal sheets on one of the outer metal sheets in at least one leveling insert. The at least one leveling insert is thus always in the same position in the mold or the molded part and is also always in contact with the same point on the glass pane. In addition, the leveling inserts cannot slip, making the molding process less prone to errors, resulting in less plastic over-molding on the glass or glass breakage.

0022It is advantageous if the insert receiving device and/or the leveling insert and/or at least one of the insert receiving device and/or at least one of the leveling inserts is arranged on one or both sides of the parting plane. In this way, the design of the injection mold can be made compact. When arranged on both sides, the pressure that occurs when clamping and sealing the glass pane for overmoulding can be evenly distributed. At the same time, production-related geometric deviations in the glass pane can also be compensated for on both sides.

0023It is conceivable that at least one fastening element is provided in the form of a socket, a pin, a threaded bolt or a clip, which couples to and holds the at least one leveling insert and/or the leveling stack. In this way, the leveling insert can also be secured against unintentional slipping.

0024An embodiment is also possible in which a fastening device is provided for fastening the at least one leveling insert and/or for interacting with the fastening element and/or for holding the fastening element. This is an additional safeguard to prevent unwanted displacement of the leveling insert.

0025According to the invention, a method for overmoulding a glass pane, wherein the glass pane is accommodated in a mold or two mold parts, is characterized in that at least one leveling insert as above is inserted between the glass pane and the mold or at least one of the two mold parts.

Description of an example:

0026An embodiment of the invention is shown in the drawing and is explained in more detail below with reference to the figures.

0027In detail shows:<dl id="dl0001"><dt>figure 1</dt><dd>schematically shown a leveling insert according to the invention,</dd><dt>figure 2</dt><dd>a schematic structure of an injection mold with a leveling insert according to the invention, and</dd><dt>figure 3</dt><dd>a schematic structure of an injection mold with leveling inserts on both sides of the glass pane according to the invention.</dd></dl>

0028In<figref idref="f0001">figure 1</figref> A possible embodiment of a leveling insert 1 consisting of several metal sheets 5, 5' is shown. In this case, straight sheets 5 and corrugated sheets 5' are alternately layered to form a stack. When the glass pane is clamped by means of one or more such leveling stacks, the corrugated metal sheets 5' can be locally deformed by the force exerted on the leveling inserts 1 and the glass pane 3 in such a way that they approach a straight shape. The force is distributed to the leveling inserts 1 at the points on the glass pane 3 where it would lead to glass breakage without such compensating measures and is derived from the local points on the glass pane 3 . At the points on the glass pane 3 where, for geometric reasons, the force acts less strongly, the corrugated metal sheets 5' deform less or not at all.

0029In<figref idref="f0001">figure 2</figref> 1 is an embodiment of an injection molding tool 2 according to the invention with metal sheets 5, 5' stacked to form a leveling insert 1. A pane of glass 3 is inserted between two mold parts 4a, 4b of a mold 4 of the injection mold 2. Since glass panes 3 are sometimes subject to considerable thickness tolerances and geometric deviations during production, the tool for overmoulding must be adapted to the respective glass pane, otherwise if the glass gap in the mold 4 is too small, there will be glass breakage and if the glass gap is too wide, overmoulding will occur when an overmoulding 8 is applied the glass pane 3 can lead.

0030For this purpose, the mold 4 is supplemented with at least one leveling insert 1 made of a metal sheet 5, 5' or a stack consisting of at least two metal sheets 5, 5', which adjoins the glass pane 3. The leveling insert 1 shown here consists of several metal sheets 5, 5', which are layered one on top of the other and is accommodated in a receiving device introduced in the mold 4 so that it always contacts the glass pane 3 at the same point, so that the quality of the overmoulding is maintained can be.

0031An additional fastening element 6 can be used to fasten the leveling insert 1 or an individual metal sheet 5, 5' to the receiving device or to a fastening device 7 or directly to the mold 4 or, as shown here, to one of the mold parts 4a, 4b.

0032<figref idref="f0002">figure 3</figref> shows an embodiment of the invention in which two leveling inserts 1 consisting of several metal sheets 5, 5' are attached on both sides of the parting plane of the mold 4 and the glass pane 3, respectively. In this way, the geometric deviations on both sides of the glass pane 3 can be compensated for.

Reference list:

0033<dl id="dl0002" compact="compact"><dt>1</dt><dd>leveling insert</dd><dt>2</dt><dd>injection mold</dd><dt>3</dt><dd>glass pane</dd><dt>4</dt><dd>shape</dd><dt>4a, 4b</dt><dd>molding</dd><dt>5, 5'</dt><dd>sheet</dd><dt>6</dt><dd>fastener</dd><dt>7</dt><dd>fastening device</dd><dt>8</dt><dd>overmolding</dd></dl>