Injection mold for the production of complex plastic molded parts

Description

[0001] The present invention is in the field of injection molds for producing parts by injection molding from plastic.

[0002] Injection molds for the production of complex plastic parts are known from the prior art. Complex parts are understood to be parts which, due to their geometry, cannot be produced with conventional tools and therefore require injection molds with slides that can move transversely to the general opening direction of the mold in order to be able to demold them at all. The reason for this is that the parts have undercuts in the general demolding direction and thus cannot be easily ejected. The slides of the conventional tools known from the prior art are usually directly coupled to the movement of the tool halves, so that the slides of the slide arrangement are only moved when the tool is opened or closed. One disadvantage is that this coupling can, among other things, lead to time losses in production.

[0003] DE2065568 by Crouzet et Cie. was first published in 1970 and concerns a casting mold for producing cast workpieces, e.g., cam blocks, which have projections on their outer surface running approximately perpendicular to the workpiece's longitudinal axis. The casting mold essentially consists of a pair of radially movable first slide shoes arranged diametrically opposite each other above a fixed base plate, with an outer surface that runs conically from top to bottom.The first sliding shoes serve to receive first mold parts which determine the mutual axial distance between the projections, and a pair of second sliding shoes which are arranged diametrically opposite to one another and offset in the plane of the pair of first sliding shoes, are radially movable and have a conical outer side extending from top to bottom, for receiving second mold parts which determine the radial extent of the projections, and a head part which is arranged on the sliding shoes when the mold is closed and moves axially away from the sliding shoes when the mold is opened.

[0004] DE2422669 from INA Wälzlager Schäffler KG was first published in 1975 and concerns a device for the production of plastic radial rolling bearing cages, in which two annular ribs are connected by circumferentially distributed webs. The injection mold comprises a cylindrical core corresponding to the cage's inner diameter, as well as an outer mold part with radially movable slides. The injection mold has recesses for the simultaneous production of two cages, which are arranged coaxially one behind the other and spaced apart from each other. The slides form the boundaries for the facing end faces of the annular ribs.

[0005] CN101508161A from Ninghai Deke Mould Co. Ltd. was first published in 2009 and concerns a slide valve arrangement comprising several radially adjustable slide valves. The slide valves are driven by a plate rotatable about an axis. This plate has spirally arranged slots into which pins engage, which are attached to the radially adjustable slide valves. The plate is driven by a relatively steep thread, which requires a considerable height. The slide valves are arranged relatively far from the rotating plate, which means that the pins must bridge this distance. This leads to an unfavorable distribution of forces.

[0006] The features of the preamble of claim 1 are known from CN 104 875 338 A and US 3 266 100 A. Further injection molds with slide arrangements are known from 103 072 239 B, US 2018 / 001524 A1, EP 2 883 675 A1, JP H03 43224 A, GB 2 278 801 A, US 3 266 100 A, JP S63 97181 A and JPH09 131772 A.

[0007] An object of the invention is to show an injection mold with a slide arrangement which has a low overall height and enables a robust construction of the slide arrangement, and in principle allows several levels for the production of complex parts.

[0008] The invention is described in the appended set of claims.

[0009] An injection mold according to the invention generally comprises a first mold half and a second mold half displaceable relative to the first in a first direction, wherein at least one of the mold halves comprises a slide arrangement for forming a mold cavity which serves to mold a complex plastic part by injecting plasticized plastic into it and then curing it. Depending on the geometry of the part to be produced, the slide arrangement has at least two slides movable relative to one another between a closed and an open position, each of which is arranged displaceably via first and second guide means with respect to a component of the associated mold half adjacent to the slides. The slides are generally arranged radially to an axis.Depending on the design, they can also be arranged laterally offset from the latter so that the movement vectors of the individual slides do not pass through a common center. Furthermore, a drive for the slides (slide drive) is provided, which is preferably based on third and fourth guide means that are operatively connected to one another and serve to move the slides between the open and closed positions. The drive is advantageously independent of the position of the mold halves of the injection mold and is thus, in contrast to the prior art, decoupled from the movement of the injection mold. The third and fourth guide means of the slide drive are advantageously located on the component of the mold half so that the distances and occurring forces can be kept as small as possible and the design can be kept compact.The slide drive can be designed to be self-locking, preventing the slides from accidentally shifting. The part of the mold half that supports the slides can at least partially enclose the slides or rest against them along one or more surfaces.

[0010] According to the invention, the first guide means have a first groove and the second guide means have an upper part of a sliding block arranged in the first groove. The third guide means are formed by a second groove and the fourth guide means by a lower part of the sliding block which is arranged in the second groove. The groove of the third guide means is arranged on and / or in a disc which is rotatable about an axis of rotation and which can also be designed as a ring. The disc is preferably arranged in a plane and has a toothing on its circumference via which it can be driven to rotate about the axis of rotation, e.g. via a toothed rack integrated in the mold half. Due to the very compact design, several slide assemblies can easily be arranged laterally next to one another or in a grid.

[0011] The first and third guide means can be arranged at a constant angle and / or at an angle that varies over the course of the path, so that when the disc rotates about the axis of rotation, the associated slides are moved between an open and a closed position. Depending on the area of ​​application, the slides can be arranged in one plane and / or at an angle to a plane. It is also possible, as shown in the exemplary embodiments, to arrange slides on several levels, which are driven individually or jointly. The slides of the slide arrangement can be used, for example, to form a spherical mold cavity with which spherical objects, e.g. golf balls and the like, can be efficiently manufactured.Multi-layered objects can be manufactured using differently driven sliders. Certain sliders can be left stationary for a specific purpose, thus freeing up an area for another material component. The arrangement of the sliders can also create depressions on the surfaces, which under normal circumstances would result in undercuts and thus cannot be demolded. Golf balls are also cited as an example here: for aerodynamic reasons, they can have dents on the surface that cannot be produced using conventional injection molding tools because they are difficult to demold.

[0012] Two adjacent slides in the slide arrangement normally interact via one or more sealing surfaces. Alternatively or additionally, the slides can support each other via the sealing surfaces in the closed position. The sealing surfaces can be flat and / or spatially curved. The sealing surfaces are advantageously located in a plane of symmetry between two mutually assigned slides. If required, the slides can have a locking surface that opposes the opening direction of the slides and interacts with a correspondingly arranged counter-surface when the injection mold is in the closed position, so that the slides are locked against the injection pressure acting inside the mold cavity during injection molding. This also ensures that the slide drive can be relieved of negative forces.The counter surface is advantageously arranged on the other half of the injection mold, so that the operative connection is established in the closed position. Alternatively or additionally, the counter surface can also be arranged on the rotatable disc, so that when this reaches a defined position, the counter surface presses against the locking surface and thus the slides are held in the closed position. The counter surfaces can interact directly or indirectly with the locking surfaces. The counter surfaces can, for example, be arranged on a projecting area of ​​the disc or a part operatively connected to it. Depending on the area of ​​application, at least one mold core is present, which forms part of the outer wall of the mold cavity between the slides in the closed position of the injection mold. The part of the outer wall of the mold cavity formed by the mold core can be convex or concave, i.e.In the closed position, they protrude into the mold cavity or are located outside it. The mold core can correspond to the mold cavity through an opening in a component of the mold half. If necessary, both mold halves can have a slide arrangement, with the slides interacting directly to form the mold cavity in the closed position of the injection mold.

[0013] Aspects of the invention are explained in more detail with reference to the exemplary embodiments shown in the following figures and the associated description. They show: Fig. 1 a slide arrangement in a perspective view from above and in front in closed view; Fig. 2 the slide arrangement according to Figure 1 in open state; Fig. 3 the slide arrangement according to Figure 1 in a side view; Fig. 4 the slide arrangement according to Figure 1 in a plan view; Fig. 5 a sectional view through the slide arrangement according to Figure 4 ; Fig. 6the slide arrangement according to Figure 1 in an exploded view; Fig. 7 a second slide arrangement in a perspective view obliquely from above and from the front, which is not part of the invention; Fig. 8 a side of the slide arrangement according to Figure 7 without fixed parts; Fig. 9 the slide arrangement according to Figure 8 in an exploded view.

[0014] Figure 1 shows a first variant of a slide arrangement 1 in a perspective view obliquely from above and at the front in a closed position. Figure 2 shows the slide arrangement 1 according to Figure 1 in an open position. Figure 3 shows the slide arrangement 1 in a side view and Figure 4 shown in a top view with the invisible edges shown as dashed lines. Figure 5 shows the slide arrangement 1 in a sectional view along the section line DD according to Figure 4 . Figure 6shows the slide arrangement 1 in an exploded view.

[0015] Figure 7 shows a variant of a slide arrangement 1 in a perspective view, which is not part of the invention. Figure 8 shows parts of a slide arrangement 1 according to Figure 7 from above and from the front. Figure 9 shows one side of the slide arrangement according to Figure 7 in an exploded view from above and at the front.

[0016] The slide assembly 1 is generally installed in an injection mold and is not visible or only partially visible from the outside. The injection mold and its other components are not shown in detail. The injection mold has a first mold half and a second mold half that is displaceable relative to the first mold half, which are installed in an injection molding machine (also not shown) to produce parts. With reference to the slide assembly 1 shown in the figures, the first and second mold halves are moved in the direction of the z-axis (first direction) of the coordinate systems of the slide assembly 1. This direction corresponds to the opening and closing direction of the injection mold, or the general demolding direction of the parts produced using the injection mold.

[0017] The slide assembly 1 is used for the efficient production of complex parts made of injection-molded plastic and the like. Unlike the prior art, the slide assembly 1 has a very small footprint and a very low overall height. Furthermore, the slide assembly 1 allows the simultaneous or staggered control of multiple slides 2, which, if necessary, can also be arranged in several planes, parallel to one another, or spatially at an angle to one another.

[0018] The slides 2 of the slide arrangement 1 are mounted displaceably relative to a component 3 of the mold half via first and second guide means 6, 7. The component 3 of the mold half can, as shown in the Figures 1 to 6 shown, have the shape of a plate and / or the slides 2 can be integrated, for example, into a molded plate and at least partially enclose it (cf. Figures 7 to 9 ) .Depending on the area of ​​application, component 3 may consist of one part or be made up of several parts.

[0019] The slides 2 are moved back and forth between an open and a closed position via a slide drive 4. As shown in Figure 6 As can be seen, the slide assembly 1 comprises, in addition to the slides 2 and the component 3, which serves to support the slides 2, a disk 5 rotatable about an axis 14 (z-direction). The disk 5 has a plurality of third guide means 8, which, in the embodiment shown, are incorporated in a surface in the form of grooves 8. Fourth guide means 9 engage in the grooves 8 in the assembled state.

[0020] From the viewer's perspective, the sliders 2 are arranged above the plate 3 and are mounted radially displaceably relative to the plate by means of the first and second guide means 6, 7 (other directions, which, for example, do not run through the center or are offset from one another, are possible). In the variant shown, the first guide means 6 are radially extending grooves 6. For each slider 2, an upper part 7 of a specially shaped, double-acting sliding block 10, which is operatively connected to the grooves 6, is arranged in these grooves and can be displaced in the direction of the grooves 6. These upper parts 7 project vertically through a groove 6 assigned to them and open at their lower end into a lower part 9 of the sliding block 10.The lower parts 9 of the T-nuts 10 are each arranged in a spiral groove 8 of a disc 5 and are arranged so as to be displaceable in the circumferential direction along the course of the groove 8, while the disc 5 is rotated about an axis of rotation 14 relative to the plate 3. The upper parts 7 and lower parts 9 of the T-nuts 10 are advantageously manufactured in one piece. Depending on the application, other, even multi-piece, designs are possible. As shown in the exploded view according to . Figure 6 As can be seen, the upper part 7 and the lower part 9 of a sliding block 10 are arranged essentially at right angles and adapted to the shape of the movement to be performed. They have an elongated design in the direction of movement, which increases the contact area and thus improves the distribution of forces.

[0021] Depending on the geometry requirements of the part to be manufactured, the slides can also be arranged along a straight line that does not pass through a center. The center is defined as a point where the movement directions of the slides converge. The inventive concept enables variants that have a non-straight path of movement by designing the guide means accordingly.

[0022] The slides 2 are designed such that, in the closed state, they form at least part of a mold cavity 15, which serves to mold a plastic part by injecting plasticized plastic into it and then curing it. The mold cavity 15 generally has an opening 16 below and / or above between the slides 2, which, in the closed position of the injection mold, serves to receive and enclose a mold core (not shown in detail), which is also a component of the mold cavity and forms an inner and / or outer contour of the part to be produced. When the slides 2 are opened, the mold core can serve to hold the part produced between the slides.

[0023] In the closed position, two slides 2 interact, generally laterally, along at least one sealing surface 12. The slides 2 can, if required, have a locking surface 13 which, when the injection mold is in the closed position, relieves the slide drive 4 of the injection pressure acting in the mold cavity. In the arrangement shown, the locking surfaces 13 are arranged on the rear side of the slides 2 and are inclined relative to the above-mentioned closing direction (z-direction) of the injection mold. The injection mold has a counter-surface corresponding to the closing surface, which is attached to the opposite mold half and, when the injection mold is in the closed position, presses the locking surfaces 13 of the slides 2 from behind in the closing direction in a controlled manner, so that they abut one another at least via the sealing surfaces 12.

[0024] Figure 7schematically shows a first and a second mold half 18, 19 (schematically shown by a dashed line 20) which is displaceable relative to the first in a first direction (z-axis). In order to make the interior of the second mold half 19 visible, it is shown tilted by 90°. In the arrangement shown, which is not part of the invention, both mold halves 18, 19 are constructed identically and each have a slide arrangement 1 for forming a spherical mold cavity 15 which, like the surface of a golf ball, can have undercuts (not shown in detail) which can be demolded by the slides. Other geometries are of course possible. In the arrangement shown, which is not part of the invention, the slides 2 of both

[0025] Mold halves 18, 19 fit directly together in the closed position of the injection mold 17. Each mold half 18, 19 has a plurality of slides 2 that are movable relative to one another between a closed and an open position, each of which is displaceably arranged via first and second guide means 6, 7 with respect to a component 3 of the associated mold half 17, 18 adjacent to the slides 2.

[0026] As in the Figures 8 and 9As can be seen, the slides 2 are connected via a slide drive 4 to third and fourth guide means 8, 9, which are operatively connected to one another and serve to move the slides 2 between the open and closed positions. As can be seen, the third and fourth guide means 8, 9 of the slide drive 4 bear against the component 3 of the mold half. In the arrangement shown, which is not part of the invention, the component 3 of the mold half encloses the slides 2 at least partially. In contrast to this, it lies in the injection mold according to the Figures 1 to 6only laterally. The first guide means here is an opening 6 in component 3 of the mold half for each slide 2. The second guide means is formed by the slide 2 itself, which is arranged in the opening and guided by its inner walls (not shown in detail). The third guide means are formed by a comb 8 and the fourth guide means by a groove 9 in the slide 2. As can be seen, the third guide means 8 are arranged on the disc 5, which can rotate about the axis of rotation 14. In the variant shown, the disc 5 is annular and has third guide means 8 both at the top and bottom, which serve to drive the slides 2 arranged on two levels. The first and third guide means 6, 8 are arranged at an angle to one another, so that when the disc is rotated about the axis of rotation 14, the associated slides 2 are moved between an open and a closed position.In the closed position, two slides 2 interact via sealing surfaces 12. This applies both to adjacent slides 2 of a mold half 18, 19 (per level and across multiple levels) and to mutually assigned slides 2 of the first and second mold halves 18, 19.

[0027] The slides 2 can have a locking surface 13, which, in the closed position of the injection mold, interacts with a correspondingly arranged counter-surface of the other mold half of the injection mold, so that the slides 2 are locked in the closed position against the injection pressure acting inside the mold cavity 15. In contrast to the first variant, there is no mold core, which, in the closed position of the injection mold, forms part of the outer wall of the mold cavity 15 between the slides 2. The entire mold cavity 15 is formed by the slides 2.

[0028] Figure 9shows schematically a mold half 18, 19 of the injection mold 17 according to Figure 7 , which is not part of the invention, disassembled in an exploded view with respect to the z-axis. The slides 2 can be seen, which are arranged here in two groups on two levels A, B. The slides 2 serve to form a spherical mold cavity 15 in the closed position of the injection mold. Differently designed mold cavities are possible. The slides 2 are driven by the third and fourth guide means 8, 9 via the annular disc 5. The slides 2 are mounted so as to be linearly displaceable in grooves or openings 6 in the components 3 of the mold half. In the embodiment shown, they are aligned radially with respect to the axis of rotation 14 in the horizontal direction (x, y plane). In the vertical direction (z-axis) they are arranged at an angle to the axis of rotation 14. LIST OF REFERENCE SYMBOLS

[0029] 1Slide arrangement 2Slide 3Mold half component, plate, mold plate (injection mold) 4Slide drive 5Disk 6First guide means, first groove 7Second guide means, upper part of sliding block 8Third guide means, second groove (disk) 9Fourth guide means, lower part of sliding block 10Sliding block 11Surface (mold half component) 12Sealing surface (slide) 13Closing surface (slide) 14Rotation axis 15Mold cavity 16Opening (mold cavity) 17Injection mold 18First mold half 19Second mold half 20Opening movement 21Toothing (disk)

Claims

1. An injection mold having a. a first mold half and a second mold half, which is displaceable relative to the first mold half in a first direction (z), wherein at least one of the mold halves having a slide arrangement (1) for forming a mold cavity (15), having b. at least two slides (2) which are movable relative to one another between a closed position and an open position, each of which is arranged such that it can be displaced via first and second guide means (6, 7) in relation to a component (3) of the associated mold half that is adjacent to the slides (2), wherein the slides (2) being arranged above the adjacent component (3), wherein c. each slide (2) has a holding-shut surface (13) which, in the closed position of the injection mold, interacts with a correspondingly arranged counter-surface of the other half of the injection mold, such that the slides (2) are locked against the injection pressure acting inside the mold cavity (15), and d. a slide drive (4) having third and fourth guide means (8, 9) which are interconnected and serve to displace the slides (2) between the open and closed positions, characterized in that i) the first guide means are a first groove (6), and the second guide means are an upper part (7), which is arranged in the first groove (6), of a sliding block (10), and ii) the third guide means are a second groove (8), and the fourth guide means are a lower part (9) of the sliding block (10), wherein the third guide means (8) are arranged on and / or in a disk (5) which can be rotated about an axis of rotation (14), and iii) the first and the third guide means (6, 8) are arranged at an angle to one another such that, upon rotation of the disk about the axis of rotation (14), a displacement of the associated slides (2) between an open or a closed position is brought about and iv) the upper part (7) and the lower part (9) have an elongated design in the direction of movement, which causes an increase in the contact area and thus a better distribution of the forces.

2. The injection mold as claimed in patent claim 1, characterized in that the third and fourth guide means (8, 9) of the slide drive (4) bear against the component (3) of the mold half.

3. The injection mold as claimed in either of the preceding patent claims, characterized in that the component (3) of the mold half at least partially encloses the slides (2) or bears against them along a surface.

4. The injection mold as claimed in one of the preceding patent claims, characterized in that the slides (2) are arranged with respect to one another in one plane and / or at an angle to one plane.

5. The injection mold as claimed in one of the preceding patent claims, characterized in that the slides (2) serve to form a spherical mold cavity (1 5).

6. The injection mold as claimed in patent claim 5, characterized in that the slides (2) serve to form a spherical mold cavity (15) with local undercuts.

7. The injection mold as claimed in one of the preceding patent claims, characterized in that in each case two slides (2) interact in the closed position via a sealing surface (12).

8. The injection mold as claimed in one of the preceding patent claims, characterized in that at least one mold core is present which, in the closed position of the injection mold, forms part of the outer wall of the mold cavity (15) between the slides (2).

9. The injection mold as claimed in patent claim 8, characterized in that the mold core corresponds with the mold cavity (15) through in an opening in a component (3) of the mold half.

10. The injection mold as claimed in one of the preceding patent claims, characterized in that the two mold halves (18, 19) have a slide arrangement (1), wherein the slides (2) directly interact in the closed position of the injection mold (17).