Forming tool

Abstract

Molding tool (200) for producing a plastic overmolding (120) on a plate-shaped component (100), comprising a mixing head (300) for producing liquid plastic from at least two components, comprising at least one first cavity (240) for receiving the plastic to form the overmolding (120), comprising a sprue (210) for connecting the mixing head (300) to the at least one first cavity (240) and a further cavity (220) formed at the transition of the sprue (210) to the first cavity (240), which widens the sprue (210), wherein a sprue cutter (400) with at least one slide (410) is movably mounted on the molding tool (200),which can be moved towards the first cavity (240) by means of at least one actuating cylinder (450) by means of at least one actuating cylinder (450) and in an end position of its movement closes off the first cavity (240) with at least one edge (414) and / or contour (412) against the sprue (210) and / or against the further cavity (220), wherein in the end position of the slide (410) a gap (230) is released between the slide (410) and the mixing head (300) in the area of ​​the sprue (210) to receive excess plastic material.

Description

[0001] The invention relates to a molding tool for producing a plastic overmolding on a plate-shaped component.

[0002] Such a mold has long been known from the production of polyurethane (PU)-encapsulated glass sunroof covers for vehicles. The flap-like sprue remaining at the transition from the sprue to the encapsulation cavity after the polyurethane has cured must currently be carefully cut away from the encapsulation by a worker using a sharp knife. Aside from the additional effort involved, there is also the risk of irreparably damaging the encapsulation with the knife, rendering the entire encapsulated glass cover scrap.

[0003] From CN 206386338 U a tool for the production of a plastic part is known in which a wiper is movably mounted on the tool by means of a hydraulic cylinder.

[0004] From JP S60 089322 A a tool for manufacturing a plastic part is known in which a slide, movable transversely to the sprue channel and extending the sprue channel with a bore, closes the sprue channel after filling a mold-forming cavity.

[0005] Furthermore, a method and a device for producing a foamed injection-molded component are known from DE 10 2009 012 287 A1. The device comprises a mold with a cavity formed by a mold core and a mold die. A slide is arranged in the mold, which is permanently connected via a sprue to an injection nozzle for plasticized plastic material. By extending the slide, the sprue is connected to a cavity whose size can be varied, so that plasticized plastic can be filled into the cavity. The connection is broken by retracting the slide after the cavity has been filled.

[0006] Another device for manufacturing an injection-molded component is known from US Patent 4,767,312 A.

[0007] The object of the invention is to create a forming tool by means of which a plate-shaped component with a foam coating can be removed from the tool without any further processing.

[0008] This problem is solved by a forming tool having the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

[0009] According to the invention, a mold for producing a plastic overmolding on a plate-shaped component has a mixing head for generating liquid plastic from at least two components. The mold has at least one first cavity for receiving the plastic to form the overmolding. A sprue serves to connect the mixing head to the at least one first cavity. A further cavity, widening the sprue, is formed at the transition between the sprue and the first cavity. According to the invention, a sprue cutter with at least one slide is movably mounted on the mold, which can be moved towards the sprue and into the first cavity by means of at least one actuating cylinder. In an end position of its movement, the slide closes off the first cavity from the sprue and / or from the further cavity with at least one edge and / or contour.In the final position of the slide, a gap is provided between the slide and the mixing head in the area of ​​the sprue channel to accommodate excess plastic material.

[0010] It is particularly advantageous if the actuating cylinder is hydraulically connected to a main line of a cleaning cylinder via a branch line, which serves to actuate a cleaning piston for cleaning the mixing head.

[0011] The slide therefore requires no further control, but is executed by the hydraulics of the molding machine simultaneously with the cleaning stroke, which is necessarily controlled after every foaming process anyway. The control system is advantageously configured such that the cleaning piston and the actuating cylinder of the slide valve can only be actuated once the first cavity is completely filled – i.e., after the foaming process has been fully completed. This is preferably done in relation to a defined quantity of plastic produced in the mixing head and delivered into the first cavity.

[0012] According to an advantageous embodiment, the slide is connected to the actuating cylinder by means of a guide element which is slidably mounted in a vertical guide groove.

[0013] A particularly advantageous feature is a mold in which the slide can be moved vertically by means of at least one additional actuating cylinder via the guide groove on the guide element. This allows the slide to be easily raised into a cleaning position for a cleaning process and then lowered back into its operating position.

[0014] According to the invention, in the final position of the slide, a gap is opened between the slide and the mixing head in the area of ​​the sprue channel to receive excess plastic material. This gap serves to return excess, still liquid plastic material in a controlled manner when the slide closes.

[0015] In a preferred embodiment, the slide has a contour on its leading edge facing the first cavity that is adapted to the contour of the foaming material. This contour limits and shapes the foaming material according to its intended contour.

[0016] The slide is advantageously equipped with at least one seal that at least partially surrounds the sprue and the further cavity at a distance. The seal prevents the excess plastic material from spreading too widely and facilitates its orderly return to the gap.

[0017] An exemplary embodiment of a tool according to the invention is explained in more detail below with reference to the drawings. It shows: Fig. 1. A perspective overall view of a tool with an inserted glass pane and finished foaming; Fig. 2 a top view of the front part of the tool with the mixing head and the sprue cutter, Fig. 3 A perspective detail view of the front tool area with the sprue cutter, Fig. 4. A perspective sectional view through the slide of the sprue cutter in the area of ​​its actuating cylinder to illustrate its vertical guidance. Fig. 5 a perspective sectional view through the slide of the sprue cutter in the area of ​​the sprue channel, Fig. 6 a perspective sectional view through the slide, raised into its cleaning position, in the area of ​​the sprue channel, Fig. 7 an enlarged perspective section view through the front area of ​​the slide in the filling position for the first cavity, Fig. 8 an enlarged perspective sectional view through the front area of ​​the slide in the closing and separating position of the first cavity from the sprue, Fig. 9 a variant to Fig. 2 with an additional seal on the slide; and Fig. 10 a variant to Fig. 3 with the additional seal on the slide.

[0018] In Fig. Figure 1 shows a mold 200 in an overall view. The mold 200 consists of the lower mold shown and an upper mold (not shown) that can be lowered onto it from above. A plate-shaped component 100, in this example a glass cover 100 for a vehicle sunroof, is inserted into the lower mold 200. The glass cover 100 is surrounded at its edge in the mold 200 by a plastic foam 120.

[0019] A mixing head 300 is used to introduce the liquid plastic. This mixing head is equipped with a plate 310 adjacent to the mold 200, into which a mixing channel 320 opens. Upon exiting the front of the plate 310, the mixing channel 320 formed in the mixing head 300 transitions into a sprue 210 of the mold 200.

[0020] A front part of the sprue channel 210, pointing towards the plate-shaped component 100, is formed in a slide 410, which is part of a sprue cutter 400.

[0021] As in Fig. As shown in Figure 2, a first injection channel 330 for a first component and a second injection channel 340 for a second component open into the mixing channel 320. The plastic produced in the mixing channel 320 is preferably polyurethane (PU). The two mixed components, still in liquid form, are introduced through the mixing channel 320 and the sprue 210 into a first cavity 240 on the mold 200, which forms the negative contour of the overmolding 120 for the glass lid 100. The first cavity 240 is formed between the lower mold 200 and the upper mold (not shown) when these are brought together in a sealed unit by a molding machine.

[0022] At the transition between the sprue 210 and the first cavity 240, a second cavity 220 is formed for the sprue 130. This widened area directs the liquid plastic material flowing from the sprue 210 to the first cavity 240 into the first cavity 240 over a broader front. With conventional molds, after the overmolding 120 is complete, i.e., after the plastic material has cured, the sprue 130 remains attached to the overmolding 120 as a flap-like appendage and must be manually separated from it.

[0023] The slide 410 consists of a central part extending into the second cavity 220 and of two holders 420 arranged laterally by the central part, the front edges of which, viewed from the plate 310, extend only to about half the distance between plate 310 and foaming 120.

[0024] In each of the two holders 420, a T-shaped undercut vertical guide groove 430 is formed, into which a guide element 440, designed as a mushroom-shaped T-nut, engages. The guide element 440 is itself, as can be seen in particular from Fig. As can be seen in Figure 4, the piston 454 is connected to a guide rod 452. The piston 454 is slidably mounted in a horizontal actuating cylinder 450. For this purpose, the horizontal actuating cylinder 450 is connected to a hydraulic branch line 460 ( Fig. 2), which branches off from a hydraulic main line 370.

[0025] The hydraulic main line 370 opens into a cleaning cylinder 355 located in the mixing head 300, in which a cleaning piston 365 is hydraulically displaceable. The cleaning piston 365 is connected to a cleaning plunger 360, which projects into a cleaning channel 350. This cleaning channel connects to the mixing channel 320 as a rear extension of the mixing channel 320 and closes the mixing channel 320 behind the two injection channels 330 and 340 with its end face. The cleaning piston 365 and the cleaning plunger 360 are made of the material in Fig. 2 indicated operating position, in which the components for producing the plastic material are injected or sprayed into the mixing channel 320 from both injection channels 330 and 340, starting from the in Fig. In position 2 shown, the cleaning plunger 360 can be moved to the left into a cleaning position, in which the front end face of the cleaning plunger 360 is pushed from the cleaning piston 365 to the front end face of the plate 310. In this process, the mixing channel 310 is completely cleaned of plastic material by the cleaning plunger 360, which is pushed forward out of the mixing channel.

[0026] Due to the direct coupling of the hydraulic branch line 460 with the main line 370, when the cleaning piston 365 is activated, the pistons 454 in the actuating cylinders 450 are also moved forward (i.e., into) the same way. Fig. 2 to the left). This also moves the slide 410 of the sprue cutter 400 to the left.

[0027] While the slide 410 in the Fig. In the operating position shown in Figure 7, while the liquid plastic for creating the foaming 120 flows through the cavity 220 and the vertical feed channel 225 into the cavity 240 to completely fill it, the slide 410 closes in the position shown in Figure 7. Fig. In the position shown in Figure 8, the front edge 414 of the slide 410 engages the feed channel 225. The quarter-circular contour 412 of the slide 410 in cross-section fits precisely against the round end contour of the upwardly directed, rounded rib of the foaming 120 and supports its shaping during the curing of the plastic material.

[0028] Since the front edge 414 of the slider 410 is in the Fig. In the closing position shown in Figure 8, when the entire feed channel 225 is closed, the excess liquid plastic is forced to flow from the cavity 220 for the gate 130 to the rear into the gap 230, which the slide 410 creates as it moves forward from the Fig. 7 shown position in the in Fig. The position shown in section 8 is exposed on its back.

[0029] How well from the Fig. 4 and Fig. As can be seen in Figure 6, in a preferred embodiment the slide 410 is not only movable horizontally, i.e., parallel to the sprue channel 210, but also vertically. For this purpose, additional actuating cylinders 470 are arranged below the holders 420 of the slide 410. The pistons 472, which are movable in the actuating cylinders 470, are connected to the holders 420 via a linkage 474. During the vertical movement of the slide 410 from the in Fig. 4 situations shown in the Fig. In the position shown in Figure 6, the holders 420 are guided by the vertical guide grooves 430 on the guide elements 440. The in Fig. The raised position of the slide 410 shown in Figure 6 serves to thoroughly clean the mold tool 200, in which plastic material that has flowed back into the gap 230 can also be removed.

[0030] In the Fig. 9 and Fig. The embodiment shown in 10 is in addition to the Fig. 2 and Fig. 3. An additional seal 416 is arranged on the upper side of the slide 410, extending forward on both sides of the sprue 210, widening in the area of ​​the second cavity 220 or the sprue 130, and surrounding it on both sides. This seal 416 effectively prevents the liquid plastic from flowing laterally towards the holders 420.

[0031] Unlike known molds, the glass lid 100 with the finished overmolding 120 can be removed from the mold 200 according to the invention after the plastic material has cured, without any sprue 130 remaining on the overmolding 120 that still needs to be removed. Costly manual rework is thus completely eliminated, as is the risk of irreparably damaging the overmolding 120 during manual rework. Reference symbol list 100 (plate-shaped) component (glass lid) 120 Foaming 130 sprue 200 forming tools 210 Gate channel 220 Cavity (for sprue) 225 Supply channel 230 gap 240 cavities (for 120) 300 mixing head 310 plate 320 mixing channel 330 Injection channel (component 1) 340 Injection channel (component 2) 350 cleaning channel 355 cleaning cylinders 360° cleaning plunger 365 cleaning pistons 370 Main line 400 sprue cutters 410 slides 412 contour 414 Leading edge 416 Seal 420 holders (at 410) 430 (vertical) guide groove 440 Guide element (T-nut) 450 actuating cylinders (horizontal) 452 Guide rod 454 pistons 460 Branch Management 470 Actuating cylinders (vertical) 472 pistons 474 connection

Claims

[1] Molding tool (200) for producing a plastic overmolding (120) on a plate-shaped component (100), comprising a mixing head (300) for producing liquid plastic from at least two components, comprising at least one first cavity (240) for receiving the plastic to form the overmolding (120), comprising a sprue (210) for connecting the mixing head (300) to the at least one first cavity (240) and a further cavity (220) formed at the transition of the sprue (210) to the first cavity (240), which widens the sprue (210), wherein a sprue cutter (400) with at least one slide (410) is movably mounted on the molding tool (200),which can be moved towards the first cavity (240) by means of at least one actuating cylinder (450) by means of at least one actuating cylinder (450) and in an end position of its movement closes off the first cavity (240) with at least one edge (414) and / or contour (412) against the sprue (210) and / or against the further cavity (220), wherein in the end position of the slide (410) a gap (230) is released between the slide (410) and the mixing head (300) in the area of ​​the sprue (210) to receive excess plastic material. [2] Molding tool according to claim 1, characterized by , that the actuating cylinder (450) is hydraulically connected by means of a branch line (460) to a main line (370) of a cleaning cylinder (355), which serves to actuate a cleaning piston (365) for cleaning the mixing head (300). [3] Forming tool according to claim 2, characterized by, that the cleaning piston (365) and the actuating cylinder (450) can only be actuated when the first cavity (240) is completely filled. [4] Forming tool according to any one of claims 1 to 3, characterized by , that the slide (410) is connected to the actuating cylinder (450) by means of a guide element (440) which is slidably mounted in a vertical guide groove (430). [5] Forming tool according to claim 4, characterized by , that the slide (410) can be moved vertically by means of at least one further actuating cylinder (470) via the guide groove (430) guided on the guide element (440). [6] Molding tool according to any one of the preceding claims, characterized by , that the slide (410) has a contour (412) adapted to the contour of the foaming (120) at its front edge (414) facing the first cavity (240). [7] Molding tool according to any one of the preceding claims, characterized by, that the slide (410) is provided with at least one seal (416) which surrounds at least partially the sprue channel (210) and the further cavity (220) at a distance.

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