Mechanical ejector

Abstract

The invention relates to a device for removing a cast part (2) with an undercut from a casting mold, in particular an inclined ejector (1), for carrying out a casting or injection molding process using an ejector, comprising an ejector head (16) which has a contour complementary to the cast part (2) with the undercut and which is mounted in a recess (8), the movable part can move between a casting position and an ejection position; an ejector base (5) that moves in a translation direction; and a chain (12) mechanically connecting the ejector head (16) to the ejector base (5) to effect a deflection of force and movement, in which the chain (12) has a plurality of links (121) that engage one another in a longitudinal direction, have low / reverse play with respect to push-pull in the longitudinal direction, and allow inclination with respect to one another in at least a first transverse direction.

Description

Technical Field

[0001] The invention relates to a device for demoulding undercuts in tools for plastic injection molding or in tools for die casting. Background Art

[0002] When injection molding any type of injection molded or die-cast part, it is necessary to eject the molded or injection molded part from the tool, for which purpose cylindrical ejector rods are usually used in the main demoulding direction. Typically in the prior art, the casting or injection molded part is demoulded by a stroke or relative movement of one or more ejector rods or a whole ejector rod arrangement relative to one or more tool plates.

[0003] If a plastic injection molded or die-cast part cannot be demoulded in the main demoulding direction, this is called a negative or undercut. This is remedied by an ejector mechanism in the tool, which releases the plastic injection molded or die-cast part from the mold. Due to the structure of the part to be demoulded, certain areas of the injection mold or die-casting mold have the above-mentioned undercuts, so that it is not possible to demould the cast or injected part by relative movement of the ejector rod or ejector plate with respect to the tool plate. Therefore, so-called tilting slides are used in the prior art to deal with demoulding undercuts.

[0004] Such an ejector device installed in an injection molding tool or a die casting tool is activated by a tilting lever during ejection. Such an ejector, called a tilting slide, is operated by a hydraulic cylinder. The latter is also called an ejector cylinder and generates a stroke by which the tilting slide moves through the tool along the sliding device in the demoulding direction of the injection mold or casting mold. The sliding device is usually arranged as a separate part in the ejector plate of the tool. The ejector device arranged as a tilting slide device is usually designed relative to the sliding mechanism so that it deflects the stroke movement of the tilting slide in the demoulding direction into a movement direction that is angled therewith. The tilting slide device thus moves at an angle relative to the stroke direction of the ejector cylinder; this angle is mainly determined by the shape and angular position of the sliding mechanism. Therefore, an ejector mechanism designed in this way consists essentially of a tilting slide device that slides along the sliding mechanism. The sliding mechanism is designed with a defined friction structure and can be interchangeably mounted in the ejector plate. As mentioned above, it usually accommodates the tilting slide device in a housing. The angle set by the movement of the tilting slide device in the sliding mechanism corresponds more or less to the demoulding angle of the undercut to be demoulded. Thus, the tilting slide device is moved within the tool during the demoulding process so that the desired demoulding is achieved according to the angle formed.

[0005] A first disadvantage of an ejector device designed in this way is that the angle to be realized must be produced individually for each geometry of the undercut to be molded, which results in an insignificant amount of work when designing the ejector device. Another disadvantage is that the ejector device cannot subsequently be adapted to the relevant dimensions, such as its length, for injection molds or casting molds with a variable number of plates in the tool.

[0006] If the cast or injection molded part has a complex shape with undercuts of different shapes or negative molds of different sizes, the demoulding process described becomes more complicated, which makes the design of the tool more expensive and therefore also the ejector mechanism more expensive and thus represents a further disadvantage. As mentioned above, for designs with different draft angles to be provided, the complexity in the application case can be increased and therefore also the space required for accommodating the aforementioned elements of the ejector device in the tool. In particular, if these elements have to be provided in a small injection mold or casting mold, for example for demoulding undercuts or negative molds of small sizes, there may be a lack of available installation space to accommodate all of the aforementioned elements and therefore also a lack of available installation space to provide the different draft angles required for effective demoulding.

[0007] The main feature of a tilted ejector known from EP2261000B1 is the combination of an ejector rod with an inclined ejector head attached thereto, whereby the ejector and the inclined ejector head are guided in a replaceable sliding bushing in the tool. The ejector head is detachably connected to the ejector rod via a joint. The joint enables the ejector head to be tilted toward the longitudinal axis of the ejector rod in order to achieve the clearance angle required for the demoulding undercut. A first disadvantage of this solution is that only a limited lateral displacement can be achieved due to the limited vertical stroke of the tilted ejector and the cross-section of the opening of the inner wall of the sliding guide. Another disadvantage is that sliding bushings suitable for both the plate and the ejector rod with the tilted ejector head must be provided in the tool, which represents an additional expense and requires a considerable amount of space. In addition, the tilted ejectors designed in this way and the solutions listed below according to EP0498102B1 or EP3372377B1 represent individual special solutions that cannot be subsequently changed or adjusted for their effective length.

[0008] EP0498102B1 describes a dimensionally stable and simply constructed tilted slider of an ejector device that ejects undercuts in a plastic injection mold. In its installed position in the mold, the tilted slider is designed at a predetermined angle in a square sliding door in the form of a sliding guide. This angle is achieved by attaching the first end of the tilted slider to a coupler at a fixed angle, which then slides along a retainer attached to the mold ejector plate. In order to be able to replace the elements of the tilted slider when necessary, the individually designed tilted slider is individually designed for the injection tool or die-casting tool and requires a sliding guide adapted thereto and at least one coupling element. This usually requires disassembling the entire tool of the plastic injection mold. The size of the undercut to be demoulded, the required horizontal displacement of the tilted slider, and the required stroke of the entire ejector device determine the angle at which the tilted slider operates. The first disadvantage is that the tilted slider designed relative to the size of the injection tool or die-casting tool requires a special design for each mold. Another disadvantage is that the square pusher must be elastically inserted into the ejector plate of the injection mold or die-casting mold. Therefore, each such ejector device requires all its elements to be specially adapted to a specific injection tool or die-casting tool. Another disadvantage is that such adaptation is usually expensive and time-consuming.

[0009] The main feature of an ejector known from EP3372377B1 is a slide consisting of a flexible push-pull element. The flexible element is represented by a helical spring that cannot be compressed within limits, wherein the coils of the helical spring are ideally always in contact with each other. Another feature of the ejector is represented by an internal wire that extends between the base end and the head end of the ejector, is clamped at these ends, and provides an initial preload for the helical spring in the assembled state. Unlike the inclined slide known from EP0498102B1, the ejector is accommodated in a hole in the ejector plate, so that no separate sliding element is required for guidance in the tool. A special feature of this solution is that this version of the ejector includes a push-pull element with a predetermined initial length in the assembled state, which push-pull element is ostensibly neither compressible nor stretchable. Therefore, another special feature is that the ejector device has a flexibility and elasticity that corresponds more to a mechanical spring than a mechanical spindle. The flexibility of the mechanical spring enables the central element of the ejector device to adapt to the geometry of the aforementioned hole in the ejector plate. Thus, the angular position of the helical spring flexibly follows the line defined by the hole.

[0010] However, the described advantages of this solution have a first disadvantage in the flexibility and therefore also in the elasticity of the coil spring used. This disadvantage manifests itself in a length change caused by the elongation of the coil spring during operation. This elongation can only be limited to a small extent by the internal wire, to which the elongation of the internal wire also contributes. The resulting length change leads to a gradual loss of tension bias in the coil spring, which, together with the push-pull loads occurring during operation, leads to premature fatigue of the push-pull elements of the ejector device. In addition, due to its uneven shape factor, the friction caused by the coil spring on the walls of the hole in the tool increases. This wear caused by friction, which cannot be eliminated, is another disadvantage of this solution. Finally, another disadvantage of this solution is that the elongation of the coil spring and the wear that occurs lead to increased wear of the entire ejector device.

[0011] None of the solutions known from the above-mentioned prior art has a modular concept which can be modified by simple solutions, which means a suitable combination of similar elements and standard parts to effortlessly produce an adapted design corresponding to the respective application.

[0012] The invention is therefore based on the object of further developing the tilting ejector described at the outset for an ejector device for an injection mold or a die casting mold so that, on the one hand, it has a high degree of dimensional stability and low clearance for absorbing large ejection forces and at the same time is flexible and, on the other hand, it consists of replaceable, expandable and adjustable elements that are as similar as possible in order to eliminate the above-mentioned disadvantages of the prior art. Summary of the invention

[0013] This object has been achieved by a device for demoulding a cast component having an undercut from a casting mold for a casting process or an injection molding process using an ejector according to claim 1 .

[0014] Further embodiments are given in the dependent claims.

[0015] Therefore, a device, in particular a tilting ejector, is proposed, suitable for demoulding a cast part with an undercut from a casting mold for a casting process, in particular for an injection molding process or a die casting process using an ejector, the device comprising: - an ejector head having a profile complementary to the cast part having the undercut and mounted in the recess so as to be displaceable between a casting position and an ejection position, - an ejector base, which moves in a translational direction; - a chain that mechanically couples the ejector head to the ejector base to achieve force and motion deflection, Therein, the chain has a plurality of links which engage with each other in a longitudinal direction, have low backlash with respect to pushing and pulling in the longitudinal direction, and allow tilting relative to each other in at least a first transverse direction.

[0016] A first advantage of the solution of the invention is the adaptability of the tilting ejector, by lengthening or shortening it, so as to adapt it to the geometry of the tool, in particular to the function and size of the plate used therein. To this end, the chain can advantageously be lengthened or shortened by adding or removing links of the same type. In particular, in the tilting ejector of the invention, the properties of a bending-rigid element are combined with the advantages of a flexible chain solution. In this context, bending slack means that the chain is designed to have a low backlash with respect to pushing and pulling in the longitudinal direction (i.e. the direction in which the links are arranged), and the links of the chain are allowed to tilt relative to each other in at least one transverse direction (preferably a first transverse direction extending perpendicular to the longitudinal direction). The chain is designed to be inelastic, beyond the material elasticity to be taken into account in the design, and has no elastic properties, in particular in the longitudinal direction. Therefore, in comparison with tilting ejector solutions that are only designed to be stable in operation and contain springs or elastically designed link rods, the chain has fatigue-resistant properties.

[0017] Another advantage of the solution of the invention is that elements of different design and / or size can be combined to provide different embodiments of the tilting ejector according to the invention for different tools with different plate geometries, number of plates and / or plate functions. For example, due to the standard design of the fastening device according to the standardized threaded connection (ISO thread), the same base piece can be accommodated in a chain with a larger or smaller diameter or a longer or shorter length. In another embodiment, the chain of the aforementioned embodiment can be combined with a transition piece of larger or smaller diameter and / or different length. Finally, in another embodiment, the transition piece of the aforementioned embodiment can be combined with an ejector head with different shapes and / or larger or smaller diameters and / or different lengths. In this way, different embodiments of the tilting ejector according to the invention can be provided by elements that are practically the same but have different shapes and / or sizes.

[0018] In particular, at least two interlocking links may be engaged by inserting a link head of one of the plurality of links into a link head receiving portion of another link in a second transverse direction, in particular perpendicular to the first transverse direction and perpendicular to the longitudinal direction.

[0019] According to this first aspect, advantageously, the bending relaxation element of the tilting ejector can be designed as a chain consisting of similar chain links and base and head parts, the elements of the chain being pushed into each other laterally for their assembly at the joints. Thus, the chain has a structurally designed bending relaxation (in particular in a first transverse direction), while in a second transverse direction perpendicular to the first direction, the bending relaxation is limited beyond the elasticity of the material used in the elements. The elements of the chain can preferably be made of a metallic material, although temperature-resistant plastics or ceramics can also be used as alternative materials.

[0020] In a preferred embodiment, the link may have regions of different shapes. The first region is represented by the link head, the second region is represented by the link neck, the third region is represented by the link shoulder, the fourth region is represented by the link body, and the fifth region is represented by the link base.

[0021] It can be provided that at least one chain link has one or two link heads protruding in the longitudinal direction towards each other, which engage with low backlash in a corresponding complementary link head receptacle of another of the chain links, so that tilting of the chain link is possible only in a first transverse direction.

[0022] Furthermore, at least one of the engaging links may have at least one link head protruding in the longitudinal direction, which link head is cylindrical and has an at least partially segmented, cylindrical side surface, wherein a tapered link neck is arranged relative to the longitudinal direction, so that the two engaging (interlocking) links are each held together by the engagement of one of the link heads in a corresponding link head receptacle and can be pivoted relative to a first transverse direction.

[0023] In particular, the chain link can have a cylindrical base body with respect to the longitudinal direction and an axial through-opening in the longitudinal direction, whereby the bendable fixing element is guided through the through-opening of the chain link to hold the link head of one of the chain links in a corresponding link head receptacle of the other chain link.

[0024] Thus, an axial through-opening can be located in the link head of the preferred embodiment, the axial through-hole being preferably produced by etching or by a through-hole. A bendable fixing element can be accommodated in this through-opening, which fixing element can be designed as a wire or a flexible rod and fixes the assembled link in the correct position in the chain in the manner of a core.

[0025] In particular, the link neck may be received in the link neck receiving portion with a backlash in a first lateral direction to allow the link to tilt at a predetermined angle.

[0026] In the link body of the preferred embodiment, there may be a recess, which may also be produced by erosion and is referred to as a link head receptacle. The link head receptacle accommodates the link head, which is pivotably arranged therein. The shapes of the link head and the link head receptacle have corresponding profiles, whereby the profiles of the link head and the link head receptacle may represent a circular segment, a cylindrical body of different radii. Both the link head and the link head receptacle may be designed with a clearance fit H7 / g6, which has a maximum bearing tolerance of up to 0.02 mm. This results in a minimum clearance between the link head and the link head mounting.

[0027] Furthermore, at least one link head may be arranged between two link shoulders extending in a first transverse direction and / or facing each other, wherein a link head receiving portion receiving the at least one link head is arranged between two link bases extending in the first transverse direction and / or facing each other, wherein the link shoulders and the link bases face each other and enclose a certain angle within which the link can be tilted at a predetermined angle.

[0028] The link neck of the preferred embodiment is located in the transition area between the link head and the link shoulder and has an undercut. The undercut is characterized by a radius and represents the base of the articulation. The articulation is formed by the positive and frictional play / backlash of the link head in the link receiver above the link neck and the mutual contact between the link shoulder and the link base.

[0029] In a preferred embodiment, the profiles of the link base and the link shoulder can be designed as straight bevels. In this preferred embodiment, when the links are assembled, the bevels of the link base and the link shoulder can form an angle with each other. This angle can be between 1° and 5°, preferably 3°. By means of closely dimensioned complementary contact surfaces between the link head and the receiving part of the link head on the one hand and between the link shoulder and the link base on the other hand, a limited, defined angle can be formed between the links. In a preferred embodiment of the links, the tilting between the links occurs only in one plane, without tilting in a plane perpendicular thereto. This creates a flexible chain that can perform a tilt-translation movement in the free space between the plates in the tool, without any guides, to move the ejector head between the casting position and the ejection position.

[0030] In another conceivable embodiment of the chain link, a link body of "convex" design is conceivable, whereby the link body has a link head and a link neck as well as a link shoulder at its two ends. Complementary to this further conceivable embodiment of the chain link, a link body of "concave" design is conceivable, whereby the link body has a link head receiver and a link base at its two ends. The "convex" and "concave" link bodies can be inserted into each other in an alternating sequence to obtain another embodiment of the chain. Within the "convex" and "concave" link bodies of this further conceivable embodiment, there can be a through-opening, which can preferably be produced by etching or by through-holes. A fixing element can be accommodated in this through-opening, which can be designed as a wire or a flexible rod and fixes the assembled links together in the correct position in the chain in the manner of a core.

[0031] In another conceivable embodiment, the profiles of the link base and the link shoulder may be rounded. In this further embodiment, the rounding of the link base and the link shoulder may preferably have radii of complementary shape or radii that roll against each other. In this further embodiment of the chain link, the angulation between the links may occur in at least one first plane and also in at least one second plane that is inclined relative to the first plane. This further embodiment of the chain link may be used in tools where, due to lateral forces acting on the chain links, the chain needs to be deflected a limited amount into at least a second plane in order to create increased flexibility in the chain on the one hand and to prevent chain breakage on the other hand.

[0032] In a preferred embodiment, as described above, the chain links that can be connected to each other by engagement can be designed as a close-fitting joint in the manner of a hinge by a low backlash fit H / 7g6, whereby the resulting flexible chain has high strength and dimensional stability on the one hand and flexibility that can be achieved in a defined direction on the other hand. By chamfering or rounding the chain link base and the chain link shoulder, an inclination angle β can be set after the engagement between the chain links, at which the first chain link body can be inclined relative to the other chain link body. The larger this inclination angle β is relative to the diameter D of the chain, the larger the bending line that the chain can pass independently or in a bushing or guide, characterized by the inclination angle α. The achievable horizontal ejection offset S is proportional to the inclination angle α and extends transversely to the reference axis A. The inclination angle α results from the geometric superposition of the inclination angles β occurring between the chain links. Therefore, the inclination angle β determines the movement of the tilting ejector at the inclination angle α relative to the reference axis A. This advantageously means that a predetermined lateral ejection offset S can be achieved by a vertical ejection stroke L, which depends on the movement process of the tilting ejector, which is characterized by the inclination angle α of the chain. The direction of movement of the tilted ejector is therefore geometrically generated by the superposition of the vertical ejection stroke L and the lateral ejection offset S. The larger the vertical ejection stroke L and the lateral ejection offset S, the larger the undercut that can be demolded. Depending on the design of the undercut and the number of plates used in the mold, the superposition of the vertical ejection stroke L and the lateral ejection offset S required for optimal demolding and ejection results can be achieved. Another advantage is that, depending on the number of plates used in the tool, the effective length of the tilted ejector can be changed by inserting additional chain links into the chain, while the ejection stroke L remains unchanged. When changing the tool, for example by changing the number of plates in the tool or their respective thicknesses, in particular when changing the cavity plate, a suitably configured tilted ejector can achieve different ejection angles for undercuts of different shapes by variation. Therefore, the size of the vertical ejection stroke L and the adjustable lateral ejection offset S is crucial for successful demolding and subsequent ejection of the undercut.

[0033] The base of the chain may have an internally threaded portion at a first end and a head at a second end, the profile of which corresponds to the link head found in the chain. The head of the chain may have an internally threaded portion at a first end and a receiver at a second end, the profile of which corresponds to the link head receiver found in the chain.

[0034] For this purpose, it may be provided that a fixing element is additionally mounted in a sliding manner in the through hole to fix the base of the chain, as well as the head and the links of the chain, against mutual shearing in the second transverse direction.

[0035] In continuous operation, despite the tight fit, bushing or hinge wear inevitably occurs between the chain links, which reduces the dimensional stability of the chain and causes wear between the chain links, resulting in very small changes in the length of the chain. Due to the dynamic elongation or compression of the chain, the above-mentioned effect is intensified, resulting in the ejector head of the tilted ejector protruding from the head-side demolding area of ​​the cavity plate during injection molding or die-casting, or being located below the head-side demolding area, in other words, no longer flush with the upper edge of the cavity plate. This can lead to the formation of undercuts and / or irreparable errors in demolding until the forming area of ​​the cavity plate or injection plate in the mold is partially destroyed. Therefore, due to this incorrect position of the ejector head, the number of defective undercuts and therefore the number of defective plastic injection molded or die-cast parts may increase significantly. This can be prevented by an adjustable and re-adjustable chain bias tension during the initial operation and continuous operation of the tool, the bias tension being achieved by an adjustable base with a fastening portion.

[0036] Due to the high mechanical stresses during the injection molding or casting process, the chain of the tilt ejector is compressed or elongated in alternating cycles, whereby a dynamic compression or elongation of the chain occurs in the micrometer range. The biasing of the chain is achieved by means of an adjustable base with a fastening section, which is screwed into a thread in the base of the chain during assembly and tightened with an initial torque. During continued operation, this screw connection can be retightened with the aid of a retightening torque. The biasing produces a pre-tensioning of the chain, so that the initial elongation of the chain is 0.1 mm.

[0037] In all embodiments, at least the first link and at least the second link can each have a recess, wherein the recess extends in the axial longitudinal direction of the link and represents an inner hole arranged concentrically with the outer diameter of the link. One or more links and the recesses therein can preferably be produced by wire etching, in particular by electrospark machining or spark etching, in order to produce a uniform, precise and fine contour on and in the link. The recess can accommodate a fixing element, which can be designed as a wire or a flexible rod and serves to fix the links in the correct position relative to each other and to prevent the links from migrating or shifting relative to each other. A first advantage thereof is that the links are fixed in their position and cannot be lost during assembly or disassembly of the tilting ejector in the tool plate.

[0038] According to another advantageous aspect, the chain head and the transition piece of the inclined ejector can be slidably mounted on the inner wall of the bushing and / or the guide, whereby the bushing and / or the guide can have a circular cross section in particular. The feed-through is preferably designed as a hole and can include a plurality of sections with different diameters and can have different profiles in certain areas depending on its size and geometric arrangement in the tool plate. Thus, straight and / or curved sections of the feed-through can be realized, in particular depending on the design of the transition between the various tool plates. In particular, a first curved section of the feed-through can be formed in the lower region of the feed-through, directly above the base region of the inclined ejector, followed by a first straight section in another path of the feed-through. It is conceivable that the first straight section is followed by a second curved section, which in turn merges into a second straight section. In this way, an inclined ejector can be advantageously used, which can be adapted to the corresponding sections of the feed-through in the plate and the special features of the ejector head or cavity plate. The feedthrough is preferably located in a cavity plate and / or other plate in an injection mold or a die casting mold, wherein the walls of the feedthrough and the guide in particular form a cylindrical contact surface for holding the chain and for holding the transition piece. In a first embodiment, the cross section of the bushing can be widened in sections, starting from the area of ​​the chain receiving part at the first end of the cavity plate, transitioning to a first widening in the area of ​​the guide of the transition piece, and ending with a second widening in the area of ​​the recess at the second end of the cavity plate, which is used to hold the ejector head. The angular position of the replaceable guide relative to the vertical axis of the tool ensures that the inclined ejector in the area of ​​the transition piece always returns to the same inclined position in the recess in the cavity plate, thereby always ensuring the limited clearance angle generated by the inclined ejector for forming the undercut. The guide is preferably detachably fixed in the first opening of the bushing by a press fit and can be replaced due to wear. The guide is installed in the first widening of the bushing and can be designed as a round tube, whereby the round tube can consist of metal or ceramic material.

[0039] According to another aspect, the ejector head can be designed in the form of a cone and can be accommodated in a conical recess in the head-side forming area of ​​the cavity plate. Due to the conical design of the ejector head and the wall of the recess in the cavity plate, a reduced resistance is achieved when forming the undercut. Another advantage of this design is that it effectively prevents the ejector head from being forced into the forming area of ​​the cavity plate. In another advantageous embodiment, the ejector head can be a two-component body, whereby the first component of the ejector head can be a cylindrical base with a smaller diameter, which is non-detachably connected to a second component with a larger diameter, in particular by a shrink fit, preferably arranged concentrically. The second component can be in particular a cone or a cylindrical body, the contour of which corresponds to the wall of the recess in the cavity plate for receiving the ejector head.

[0040] In another embodiment, the ejector head can be a cylindrical body having the same diameter as the transition piece and the chain head, chain and base piece. Such an embodiment can be used, for example, in the aforementioned injection tool or die-casting tool, which produces injection-molded or die-cast parts without undercuts and has only a vertical main demoulding direction. In a further development of this embodiment, the ejector head can be omitted and instead the transition piece can be designed as an ejector head in the form of an extendable or shortenable ejector rod.

[0041] Furthermore, in addition to the above-described embodiments of the tilting ejector according to the invention, it is also conceivable that in addition to the guide in the cavity plate, the sliding sleeve is embedded in the feed-through in the tool plate. Such a sliding sleeve can be used in injection tools or die-casting tool plates, wherein the elasticity of the plate causes deformation of the wall of the feed-through during continuous operation. Undesirable effects may be greater friction or deformation of the chain in the bushing, which can lead to chain breakage. Similar to the guide, such a sliding sleeve can be made of a metal material, in particular bronze or a bronze-graphite alloy or a ceramic material, and preferably has a flexibility corresponding to the chain and a friction coefficient adapted to the sliding pairing between the sliding sleeve and the chain. In particular, the sliding sleeve made of a metal material, in particular bronze or a bronze-graphite alloy or a ceramic material, can be designed as a cylindrical tubular body. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The details of the invention are explained in more detail with reference to the embodiment examples shown in the drawings. The same multiple references to components in the same graphic representation include both the singular and the plural of the elements shown in each case. They show: Figure 1a is a longitudinal section through an embodiment of an inclined ejector and an undercut of an injection molded or die cast part, showing the situation at the end of the molding process and immediately before demolding of the undercut; Figure 1b is a longitudinal cross-sectional view of an embodiment of a tilted ejector and a molded undercut of an injection molded or die cast part, showing the situation immediately after the ejection and separation of the undercut from the cavity plate and after demolding when the undercut is completely separated from the ejector head; Figure 2a is a side elevation view of a chain removed from an assembly of a tilt ejector and a transition piece in a straight position relative to one another; Figure 2b is a top view of a longitudinal section of a chain removed from an assembly of a tilt ejector and a transition piece in line with each other; Figure 3a is a longitudinal cross-sectional view of a chain removed from an assembly of an inclined ejector and a transition piece in an inclined position relative to each other; Figure 3bis a side elevation and partial longitudinal section of a chain removed from an assembly of an inclined ejector and a transition piece in an inclined position relative to each other; Figure 4 It is detail A of three links (three-part chain segments) tilted towards each other; Figure 5 are different views of a single link removed from a chain assembly. DETAILED DESCRIPTION

[0043] Figure 1a The tilted ejector 1 is shown in a plastic injection mold or casting mold in a first position (casting position), which shows the situation immediately after the molding process of a molded part 2 (plastic injection molded part or die cast part) and before the molded part 2 is formed with an undercut.

[0044] The casting mold is formed by the recess 8 in the casting body. Immediately before the ejection process, the conical ejector head 16 is located in a first position in the conical recess 8 in the molding region of the cavity plate 3 and is precisely connected to the undercut.

[0045] The ejector plate 5 represents an ejector base or a part thereof, and a base member is provided inside the ejector plate 5. The base member has a fastening portion 11, which is located at a first position above the base plate 6.

[0046] Figure 1b The inclined ejector 1 in an injection mold or a die-casting mold is shown in a second position (ejection position) during the ejection process. The ejector plate 5 is moved into the second position, for example by means of a vertical ejection stroke L (34) by means of a piston of a hydraulic ejector cylinder (not shown). In this step of the demoulding process, the ejector head 16 is still precisely connected to the undercut and thus to the injection-molded or die-casting part. During the demoulding process, the conical ejector head 16 is moved to the second position, in which it is detached from the first wall 81 of the conical recess 8 in the head-side demoulding area of ​​the cavity plate 3, while the conical ejector head 16 slides in the main demoulding direction along the second wall 82 of the conical recess 8 in the head-side demoulding area of ​​the cavity plate 3.

[0047] A chain 12 consisting of interconnected chain links 121 is provided. Due to the mechanically positionally stable and low backlash connection of the chain links 121 to each other, the chain 12 can be advanced to a second position within the intermediate space 4, the bushing 7, the bushing 9 and the guide 91. In order to support the screwing of the chain 12 into the bushing 9, a chamfer 71 can be provided in the transition region between the bushing 7 and the bushing 9. Due to the dimensional stability and flexibility of the chain 12, it can be moved in the intermediate space 4, i.e. advanced, without guidance or support. A through hole 61 in the base plate 6, which is preferably designed as a hole, provides access to the base member with the fastening portion 11. A screwdriver or a hexagonal wrench or a multi-tooth wrench can be inserted into the through hole 61 (not shown), and the tightening torque of the base member with the fastening portion 11 can then be adjusted through the through hole 61 to readjust the bias / preload of the chain 12.

[0048] Figure 1b The upper region of the inclined ejector 1 in the injection mold or die casting mold, i.e. above the inclined ejector 1, is shown held in its second position during the ejection process. The notch 161 of the ejector head 16 releases the cast part 2. From this step of the ejection process, the ejector head 16 is no longer exactly connected to the undercut of the molded part 2. The injection molding plate (not shown) or the die casting plate (not shown) takes the plastic injection molded part, represented by its undercut, and guides it away from the ejector head 16. In this step, the undercut of the molded part 2 is completely ejected.

[0049] Figure 2a A side view and a partial longitudinal section of the chain 12 and the transition piece 13 are shown. These are positioned in a straight line relative to each other. In the straight position, the links 121 are not tilted towards each other and the contact area of ​​the link base 27 abuts against the complementary contact area of ​​the link shoulder 28 of the corresponding link 121. In this straight position, the maximum vertical lifting force can be generated by the tilted ejector 1, which represents an advantage in the design of the tilted ejector 1, in particular as a straight ejector rod.

[0050] Figure 2b A top view of a longitudinal section through the chain 12 and the transition piece 13 is shown. A threaded section 18 can be provided in the base 122 of the chain 12, which opens into a hole 19 in the longitudinal direction (via a passage through the chain link 121). A base element with a fastening section 11 in the form of a standard screw can be screwed into the threaded section 18 (not shown). The chain 12 can be detachably connected to the ejector plate 5 of the tool via the base element with the fastening section 11, and the preload of the chain 12 can be adjusted via the screwing depth and tightening torque of the base element with the fastening section 11 into the threaded section 18.

[0051] like Figure 2bAs shown, threaded portions 21, 22, 23 may be provided, which may be used to accommodate fasteners. In this case, the threaded portions 21, 22 accommodate a first fastener 14 in the form of a threaded pin (standard part), by means of which the chain 12 is detachably connected to the transition piece 13. The threaded portion 23 accommodates a second fastening device 15 in the form of a standard screw (not shown), by which the transition piece 13 is detachably connected to the ejector head 16. A fixing element 20 may be accommodated in the hole 19. The fixing element 20 may be in the form of a wire, a wire rope or another flexible element, for example.

[0052] The hole 19 extends centrally in the longitudinal axis 32 of the chain 12 and can preferably be provided during the manufacture of the chain link 121, as well as the base 122 and the head 123 of the chain 12. On the one hand, the fixing element 20 located in the hole 19 provides a position lock for the chain link 121, as well as the base 122 and the head 123 (starter and end piece) of the chain 12 during the assembly process or disassembly process of the tilting ejector 1 in the tool. On the other hand, the fixing element 20 provides an internal return spring for the chain 12 due to its elasticity, whereby the chain 12 can return to its original shape after deflection.

[0053] Figure 3a A side view of a transition piece 13 is shown, which is connected to the chain 12 in an inclined position relative to each other. The inclined position is produced by bending the links 121 towards and away from each other. The fixing element 20 located in the hole 19 (shown) is forced to bend by the bending of the links 121 relative to each other and, as mentioned above, represents a return spring for the chain 12 due to its elasticity. During assembly or disassembly of the tilting ejector 1, the fixing element 20 also ensures that the links 121 cannot be sheared off from each other in the second transverse direction and / or lost in the tool during assembly or disassembly of the tilting ejector 1.

[0054] Figure 3b The tilt angle α (31) produced by bending the chain link 121 is shown in a side view and in a partial longitudinal section. The tilt angle α (31) is arranged between the reference axis A (32) and the reference axis B (33) and can cover an angle range of 0 to 15 degrees, preferably an angle range of 5 to 10 degrees. Depending on the diameter D of the chain 12 and in particular the transition piece 13, a certain degree of fineness of the tilted ejector 1 is produced. The degree of fineness results from the ratio of its total length, which results from the length of the chain 12 and the length of the transition piece 13, to the diameter D. The thinner the tilted ejector 1 can be designed, the closer a plurality of similar tilted ejectors 1 can be positioned next to each other in an injection mold or a die-casting mold.

[0055] Figure 4 Shows Figure 3b1 . In this detail view, a plurality of mutually connected links 121 in a preferred embodiment are shown in an inclined position relative to one another. Due to the inclination of the links 121 relative to one another above the link neck 29, an inclination angle β (30) is formed after the links 121 have been assembled by means of the inclined surfaces of the link base 27 and the link shoulder 28. Within the assembly of the chain 12, there are a plurality of chain segments 24, wherein the link head 25 in each chain segment 24 is articulated in the link head receiving portion 26 in the manner of a low backlash hinge. In addition to the greatest possible flexibility, this design also ensures maximum profile accuracy of the chain 12 and therefore high dimensional stability and low elongation. In the design of the above-mentioned low backlash hinge, the bushing clearance / backlash between the individual links 121 is minimized, which reduces the wear of the chain 12 and, therefore, the tilting ejector 1 as a whole.

[0056] Figure 5 A preferred embodiment of a single link 121 disassembled from a chain 12 is shown in various views. This embodiment is characterized by a cylindrical link body 29, a cylindrical link head 25 and a complementary cylindrical link receiver 26, as well as complementary chamfers of the link shoulder 28 and the link base 27. Due to these chamfers, an angle of inclination β (30) with respect to the horizontal is formed between the link shoulder 28 and the link base 27, with the link neck 29 as a fulcrum, and the angle of inclination β is between 1° and 5°, preferably 3°. In the link head 25 there is a through opening 251, which together with the through openings 251 of the other links forms a hole 19 for receiving a fixing element 20 (not shown).

[0057] List of reference numerals 1 Tilt ejector 2 Casting parts 3 Cavity Plate 4 Clearance in the tool 5 Ejector plate 6 substrate 61 Through hole in substrate 6 7 Feedthrough in the foot end region of cavity plate 3 71 Chamfer in the transition area between bushing 7 and bushing 9 8 Recesses in the head-side molding area of ​​cavity plate 3 81 First wall of the conical recess 8 82 Second wall of the conical recess 8 9 Feedthrough in cavity plate 3 91 Guide member in cavity plate 3 10 Hole in ejector plate 5 11 Base member having a mounting portion 12 Chain 121 links 122 Chain 12 foot 123 Chain 12 head 13 Transition piece 14 First fastener of transition piece 13 15 Second fastener of transition piece 13 16 Ejector head 161 Notch in ejector head 16 17 Hole in ejector head 18 Threaded section in the base area of ​​the chain 12 19 Holes in the base 122 and head 123 of the chain 12 20 Fixing elements 21 Threaded section in the chain head 22 Threaded portion of the base region of the transition piece 13 23 Threaded portion of the head region of the transition piece 13 24 chain segments (three parts) 25 Link head 251 Through opening in link head 25 26 Chain link 261 Link head receiving part 27 Link Base 271 Rounding in the transition area between the link base 27 and the link head support 261 28 Link Shoulder 29 Link Neck 30 Tilt angle β 31 Tilt angle α 32 Reference axis A 33 Reference axis B 34 Vertical ejection stroke L 35 Lateral ejection offset S

Claims

1. A device for demoulding a cast part (2) with an undercut from a casting mold, in particular a tilting ejector (1), for carrying out a casting process or an injection molding process with the ejector, the device comprising: - an ejector head (16) having a profile complementary to the cast part (2) with the undercut and mounted in the recess (8) so as to be displaceable between a casting position and an ejection position; - an ejector base (5), the ejector base (5) being movable in a translation direction; - a chain (12) mechanically connecting the ejector head (16) to the ejector base (5) to achieve force and motion deflection; The chain (12) has a plurality of chain links (121) engaged with each other in a longitudinal direction, wherein the chain links (121) particularly have a low backlash relative to pushing and pulling in the longitudinal direction and allow tilting relative to each other in at least a first transverse direction.

2. The device according to claim 1, wherein: At least one of the chain links (121) has one or two chain link heads (25) protruding opposite to each other in the longitudinal direction, the chain link heads (25) engaging with corresponding complementary chain link head receiving portions (261) of another of the chain links (121) without play / backlash, so that tilting of the chain link (121) is possible only in the first transverse direction.

3. The device according to claim 2, wherein: At least one of the joining links (121) has at least one link head (25) protruding in the longitudinal direction, the link head (25) being cylindrical and having an at least partially segmented, cylindrical side surface, wherein a conical link neck (29) is arranged relative to the longitudinal direction, so that two joining links (121) are each held together by the engagement of one of the link heads (25) in a corresponding link head receiving portion (261) and are pivotable relative to the first transverse direction.

4. The device according to claim 3, wherein: The link neck (29) is received in a link head receiving portion (261), and the link head receiving portion (261) has a clearance / backlash in the first transverse direction to allow the link (121) to tilt at a predetermined angle.

5. The device according to claim 2, wherein: At least one of the link heads (25) is arranged between two link shoulders (28) extending along the first transverse direction and / or facing each other, wherein a link head receiving portion (261) receiving at least one link head (25) is arranged between two link bases (27) extending along the first transverse direction and / or facing each other, and the link shoulders (28) and the link bases (27) face each other and enclose an angle within which the link (121) can be tilted at a predetermined angle.

6. The device according to any one of claims 1 to 5, wherein: At least two of the engaging links (121) are configured to be engaged by inserting a link head (25) of one of the links (121) into a link head receiving portion (261) of the other link (121) along a second transverse direction, in particular perpendicular to the first transverse direction.

7. The apparatus according to any one of claims 2 to 3, wherein: The chain link (121) has a cylindrical base body relative to the longitudinal direction and an axial through-opening (251) along the longitudinal direction, wherein a bendable fixing element (20) is guided through the through-opening (251) of the chain link (121) to hold the link head (25) of one of the chain links (121) in a corresponding link head receiving portion (261) of the other chain link (121).

8. The device according to claim 7, wherein: The fixing element (20) can also be slidably mounted in the through opening (251) to fix the base (122) of the chain (12), as well as the head (123) of the chain (12) and the chain link (121) to prevent mutual shearing in the second transverse direction.

9. The device according to any one of claims 1 to 8, wherein: The chain (12) is guided in feed-throughs (7, 9) and / or guides (91) in order to redirect forces and movements acting on the ejector base (5) to the ejector head (16) in the main demoulding direction.

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