Shut-off valve for controlling the flow of molten material

Abstract

A shut-off valve for controlling the flow of molten material exiting a sprue into a cavity of a mold is described. The valve comprises a passage for the molten material extending along a first axis toward the sprue; a slide element having a first free end and movably mounted to move along a second axis to approach the first axis, allowing the first free end to move and reach a point within the passage to throttle the flow; and an actuating element mounted to slide back and forth along a third axis. The slide element and the actuating element are coupled via an inclined plane designed to convert a linear displacement of the actuating element into a displacement of the slide element.

Description

[0001] The invention relates to a shut-off valve designed as a plate slide for controlling a flow of molten material during injection molding.

[0002] It is known how to control the flow of molten material exiting a sprue into a mold cavity using a stem (pin or slide) that can be moved linearly back and forth, with the movement corresponding to the flow of molten material. However, the presence and reciprocating motion of the stem increase flow disturbances, creating areas of material accumulation and stagnation. This can lead to processes such as color-changing injection molding, requiring multiple purge injections with significant material loss. Skewed stems, as described in EP520345, have the disadvantage of forcing the material against the inner surface of the passage, further compressing it until it exits. This squeezing effect results in defects in the finished part.

[0003] To attempt to solve this problem, the shank closure was replaced by a plate slide gate at the material outlet. This solution, used for the simultaneous opening and closing control of several injection nozzles arranged in series and controlled by a single actuator, is described, for example, in WO 01 / 83191 A1 (EP 1 409 222), in particular Fig. 13. However, a single moving slide causes the material to be squeezed towards the periphery of the sprue opening, which has a lower temperature, resulting in defects in the cast product.

[0004] A better solution, as described in WO 99 / 42274 A1 (EP 1 064 138), is the use of two opposing slides whose closing point is in the middle of the passage, where the temperature is higher. However, WO 99 / 42274 A1 specifies two planar slides driven by a single actuator located at the far edge of the mold, which significantly complicates handling and results in inaccurate control of the slide position. Installation is also complicated and expensive, as the proximity of the slides to the sprue (the outlet for the plastic material) and thus to the mold cavity necessitates a thin mold lining and therefore very strong and expensive materials. Despite these efforts, it remains impossible to eliminate the marks (small cylindrical protrusions) that this solution leaves on the cast part.

[0005] The object of the invention, which is defined in the attached claims, in which the dependent claims define advantageous embodiments, is to improve this prior art.

[0006] In particular, the operation of moving, sealing parts should be improved.

[0007] Another advantage is the improvement of the performance and / or properties of an injector (or nozzle) for injection molding.

[0008] The problem is solved by a shut-off valve according to the independent claim.

[0009] The inclined plane ensures good contact between the actuator and the slide. The contact area between the two can be increased, distributing the pressure of the molten material over a larger area and reducing the risk of damage to these contact surfaces. By reducing the risk of seizing or wear, it becomes possible to use less powerful and less hard, and therefore less expensive, materials.

[0010] It is then possible to move the positioning point of the actuating element away from the critical area of ​​the mold, since the inclined plane makes it possible to position and align the actuating and sliding elements relative to each other.

[0011] Furthermore, such kinematics make it easy to reduce the dimensions of the system.

[0012] In a preferred embodiment, the valve comprises two or more sliding elements connected via an inclined plane to a respective actuating element, wherein each sliding element and each actuating element has one or more of the features defined above or in the claims, wherein the two or more sliding elements are arranged so that they move along - the diagonals of an imaginary polygon, preferably a regular polygon whose center lies on the first axis; or - of the same line, or - the edges of a pyramid whose base is the aforementioned imaginary polygon and whose vertex lies on the first axis (as in WO 2024 095074).

[0013] In a preferred embodiment, the sliding element has the form of a straight shaft, one end of which is free and the opposite end of which is connected to the actuating element.

[0014] In a preferred embodiment, the actuating element is movably installed in a cavity of a mold plate.

[0015] In one embodiment, the opposite end comprises a bore and is inserted into a lateral slot of the actuating element, with a bolt passing through the bore and projecting from the opposite end in opposite directions with two heads, the heads sliding into two linear grooves that face the body of the actuating element on the inner walls of the slot and are recessed therein. The grooves extend along an axis that follows a bisector of the angle formed by the feed direction of the sliding element and the feed direction of the actuating element.

[0016] In a preferred embodiment, the opposite end has a rider projecting from the profile of the slide element, and the actuating element comprises a slot engaging two sides of the same and transversely penetrating an edge of the same, the slot having two substantially parallel side walls and a rear wall at a T-shaped extension of the section of the slot, the extension having a profile corresponding to that of the rider to form a guide for the rider.

[0017] In a preferred embodiment, the valve comprises two or more actuating elements, each with a sliding element, wherein the actuating elements have axes of movement parallel to each other and are rigidly connected by a common connecting element arranged around the injector. Preferably, the common connecting element comprises a bracket or a plate with a central hole into which the injector is inserted, and two or more actuating elements are connected at opposite ends of the bracket or plate.

[0018] The advantages of the invention become even clearer through the following description of a shut-off valve. Fig. Figure 1 shows a cross-sectional view of an injector. Fig. 2 and Fig. Figure 3 shows a top view of a shut-off valve. Fig. Figure 4 shows a three-dimensional partial view of a shut-off valve actuator. Fig. Figure 5 shows a three-dimensional partial explosion view of the drive mechanism. Fig. 4. Fig. Figure 6 shows a three-dimensional partial view of a second shut-off valve actuator. Fig. Figure 7 shows a three-dimensional partial explosion view of the drive mechanism. Fig. 6. Fig. Figure 8 shows a cross-sectional view of a second injector. Fig. Figure 9 shows a three-dimensional partial view of a third shut-off valve actuator. Fig. Figure 10 shows a sectional view of a third injector connected to the system made of Fig. It is equipped with 9.

[0019] In the figures, identical elements are marked by the same numbers, and to avoid overloading the drawings, sometimes only some numbers are shown.

[0020] In Fig. Figure 1 shows the end 18 of a conventional injector 10, which is used to inject molten material into a cavity 12 of a mold. The injector 10 is mounted within one or more plates 500 that form the mold and is attached to a conventional melt distributor (the so-called “manifold” is also mounted within the plates 500, not shown). The injector 10 consists of an inner hollow body 14 that defines an axial cavity 16 extending longitudinally along a central axis Y (which is preferably also rotationally symmetrical for the injector 10). The end 18 of the injector 10 rests on a casting insert 20 with an opening that defines a sprue 98, allowing the molten material to flow through the cavity 16 to the sprue 98. Overall, the design of injector 10 is known and does not need to be repeated.

[0021] Unlike conventional injectors, there is no valve pin in cavity 16. The system for regulating the flow of molten material through sprue 98 is located in the Fig. 2 ff. are shown in detail.

[0022] In a passage 30 of the insert 20 or another plate connected thereto, a slider 32 in the form of a pin 34 is installed, which is free at one end 36 and coupled at the opposite end 38 to an actuating means, an example of which is shown in the Fig. 4 and Fig. Figure 5 shows that the passage 30 and the slide 32 preferably have complementary shapes.

[0023] The end 38 is connected to an actuating element 44 (e.g., a shaft) which is movably installed in a cavity 48 of the insert 20 near the cavity 16 and is displaceable therein along an axis W. The end 38 includes a bore 50 and is inserted into a lateral slot 56 of the actuating element 44. A bolt 52, which projects from the end 38 with two heads facing in opposite directions, passes through the bore 50. The heads engage slidably in two linear grooves 54, which face the body of the actuating element 44 and are recessed into the inner walls of the slot 56.

[0024] The grooves 54 are accessible from the outside via the slot 56 and run along an axis S, which in the top view is as shown in Fig. 2 follows an angle bisector of the angle formed by the axis Z and the axis W.

[0025] When the actuating element 44 is displaced along the axis W, orthogonal to a plane passing through the axis Y, the grooves 54 displace and press the heads of the bolts 52 along the walls of the grooves 54. These walls act like an inclined plane for the bolt 52, which is driven to slide in the grooves 54 along the axis S. This corresponds to a displacement of the slide 32 along the axis Z.

[0026] As a result, the grooves 54 convert a linear displacement of the actuating element 44 into a proportional linear displacement of the slide 32. It is then possible to slide the end 38 back and forth along the axis Z to achieve a proportional displacement of the slide 32 inside the passage 30, which leads to a more or less large protrusion of the end 36 inside the channel of the gate 98. This protrusion determines the degree of closure of the gate 98, from fully open ( Fig. 2) to completely closed ( Fig. 3) Intermediate positions are also possible.

[0027] In the example shown, the angle between axis Z and axis Wein is a right angle. However, it could also be acute or obtuse.

[0028] Another example of a drive for the slide 32 is in Fig. 6 and Fig. 7 shown.

[0029] The end of 38 this time shows ( Fig. 7) a rider 60 projecting from the profile of the pin 34, while an interacting actuating element 70, corresponding to the actuating element 44, has a slot 62 engaging two adjacent sides of the actuating element 70 and transversely penetrating one edge thereof. The slot 62 has two substantially parallel side walls 63 and a bottom 64 at a T-shaped widening 66 of the cross-section of the slot 62. The widening 66 has a profile corresponding to that of the rider 60, so that it forms a guide for the rider 60, allowing the rider 60 to slide linearly within (and along) the widening 66.

[0030] The base 64 is inclined with respect to the axis W like the grooves 54 and by a certain angle, and the rider 60 is inclined with respect to the axis Z by a complementary angle.

[0031] The rider 60 corresponds in function to the bolt 52 and the widening 66 to the grooves 54. In particular, the base 64 forms an inclined plane on which the rider 60 can slide.

[0032] Due to the geometry of the parts, a displacement of the actuating element 70 leads to a displacement of the slider 32 along the axis Z, as shown in the Fig. 2 and Fig. 3 explained.

[0033] Fig. Figure 8 shows another example of the actuation of the slide 32. This time, the actuating element 44 is mounted in a cavity 72, which extends parallel to the cavity 16 and can be moved back and forth along an axis W parallel to the axis Y. The operating principle is the same as for the slide 32 from Figure 8. Fig. 1.

[0034] Fig. Figure 9 shows an embodiment of the system in which more than one slider can be moved simultaneously, in this example two opposing sliders 32 that can be moved along the same line. However, it is also possible to move more than two sliders simultaneously by copying the mechanisms.

[0035] Each slider 32 is, as in the Fig. 4 and Fig. As described in section 5, the position of the two slides is controlled by a corresponding actuating element 44 and the associated kinematic chain. The two actuating elements 44 have parallel axes W and are rigidly connected by a bracket 80. By moving the bracket 80 back and forth, the two slides 32 are moved simultaneously, whereby their ends 36 at the gate 98 are brought closer together or moved further apart.

[0036] Fig. Figure 10 shows an example of an implementation of the system of Fig. 9 including the injector 10.

[0037] The bracket 80 is mounted around the injector 10, with the body 14 being inserted into a central hole 82 of the bracket 80. The axes W of the two actuating elements 44 run parallel to the axis Y. In other embodiments, they may also run non-parallel. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 520345

[0002] WO 01 / 83191 A1

[0003] EP 1 409 222

[0003] WO 99 / 42274 A1

[0004] EP 1 064 138

[0004] WO 2024 095074

[0012]

Claims

[1] Shut-off valve for controlling a flow of molten material exiting from a sprue (98) towards a cavity, the valve comprising: - a passage for the molten material, which runs from a first axis (Y) to the sprue (98), - a sliding element (32) having a first free end and being movably mounted to move along a second axis (Z) to approach the first axis (Y) so that the first free end (36) can move and reach a point inside the passage to narrow the passage and limit the flow, - an actuating element (44,70) which is mounted to be displaceable back and forth along a third axis (W), wherein the sliding element (32) and the actuating element (44,70) are coupled via an inclined plane (64) which is configured to convert a linear displacement of the actuating element (44) into a displacement of the sliding element (32). [2] Shut-off valve according to claim 1, wherein the displacement of the slide element (32) is linear and / or curved. [3] Shut-off valve according to one of the preceding claims, wherein the actuating element (44,70) is configured to slide in a plane orthogonal to the first axis (Y) or in a plane passing through the first axis (Y). [4] Shut-off valve according to one of the preceding claims, wherein the inclined plane (64) is integral with or in the actuating element (44, 70) and / or with or in the slide element (32). [5] Shut-off valve according to one of the preceding claims, wherein the second axis (Z) and the third axis (W) are orthogonal to each other. [6] Shut-off valve according to one of the preceding claims, wherein the second axis (Z) and the third axis (W) form a plane and this plane is parallel or orthogonal to the first axis (Y). [7] Shut-off valve according to one of the preceding claims, wherein the inclined plane (64) is a groove in the actuating element (44, 70) and / or in the slide element (32). [8] Shut-off valve according to one of the preceding claims, wherein the actuating element (44, 70) and the slide element (32) each have an inclined plane (64) and these inclined planes are in sliding contact with each other. [9] Shut-off valve according to any of the preceding claims, wherein the or each inclined plane extends along a direction between the second axis (Z) and the third axis (W). [10] Shut-off valve according to one of the preceding claims, comprising two or more actuating elements (44, 70) with a respective slide element (32), wherein the actuating elements (44, 70) have parallel displacement axes (W) and are firmly connected to each other by a common connecting element which is attached around an injector having the passage.

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