Mechanical ejector

Abstract

The invention relates to a device, in particular an inclined ejector (1), for removing a cast component (2) with an undercut from a mold for a casting process or an injection molding process using an ejector, comprising: an ejector head (16) with a profiled section which complements the cast component (2) with the undercut and which is movably mounted in a recess (8) between a casting position and an ejecting position; an ejector base (5) which can be moved in a translational direction; and a link chain (12) which mechanically connects the ejector head (16) and the ejector base (5) together in order to provide a force and movement deflection, wherein the link chain (12) has multiple chain segments (121) which engage into one another in the longitudinal direction and which have a low degree of play with respect to tension and compression in the longitudinal direction and allow a tilting movement relative to one another in at least one first transversal direction.

Description

[0001] MECHANICAL EJECTOR

[0002] Description

[0003] Technical area

[0004] The present invention relates to a device for demoulding undercuts within tools for plastic injection moulding or within tools for die casting.

[0005] Background of the invention

[0006] When injection molding any type of injection-molded or die-cast part, it is necessary to eject the cast or injection-molded part from the tool. For this purpose, cylindrical ejector pins are typically used in the main demolding direction. Demolding a cast or injection-molded part by means of a stroke or relative movement of the ejector pin(s) or the entire ejector device in relation to the tool plate(s) represents the state of the art.

[0007] If plastic injection-molded or die-cast parts cannot be demolded in the main demolding direction, this is referred to as an undercut. This is remedied by ejector mechanisms in the tool, which release the plastic injection-molded or die-cast part from the mold. In the case of injection molds or die-casting molds that have certain areas with the aforementioned undercuts due to the structure of the part to be demolded, demolding of the molded or injection-molded part by relative movement of ejector pins or the ejector plate in relation to a tool plate is not possible. It is therefore state of the art to use so-called inclined slides for the process of demolding undercuts. Such ejector devices, installed within the injection-mold or die-casting tool, are activated at the moment of ejection by means of inclined rods.Such ejectors, called inclined slides, are advanced by a hydraulic cylinder. The latter are also referred to as ejection cylinders and generate a stroke by means of which the inclined slide moves along a sliding device, through the tool, in the molding direction of the injection mold or die casting mold. The sliding device is often present as a separate element within the ejector plates of the tool. An ejector device implemented using an inclined slide is usually designed with regard to the sliding mechanism in such a way that it redirects the stroke movement of the inclined slide in the molding direction into a direction of movement at an angle to it. Consequently, the inclined slide moves at an angle to the stroke direction of the ejection cylinder; this angle is largely determined by the shape and angular position of the sliding mechanism.Ejector mechanisms designed in this way essentially consist of an inclined slide that slides along a sliding mechanism. The sliding mechanism is designed with a defined friction structure and can be replaceably mounted in the ejector plates. As described above, it often accommodates the inclined slide in a housing. The angle created by the movement of the inclined slide within the sliding mechanism more or less corresponds to the forming angle of the undercut to be demolded. The inclined slide thus moves within the tool during the demolding process, with the desired demolding being achieved depending on the angle created.

[0008] A first disadvantage of an ejector device designed in this way is that the desired angle must be individually manufactured for each geometry of the undercut to be formed, which requires considerable effort in the design of the ejector device. A further disadvantage is that the ejector device cannot be subsequently adapted in the relevant dimensions, for example, its length, for use in injection molds or die-casting molds with a variable number of plates in the tool. If a cast or injection-molded part has complex shapes with undercuts of varying strengths or negatives of different sizes, the described molding process becomes more complex, which increases the cost of the tool and thus the ejector mechanism, thus representing a further disadvantage.As described above, the complexity of applications involving designs with different forming angles that must be set up can increase, and thus also the space required to accommodate the aforementioned elements of an ejector device within the tool. Particularly when these elements must be provided in small injection molds or die-casting molds, e.g., for forming undercuts or negatives with small dimensions, there may be a lack of available space to accommodate all of the aforementioned elements and thus to provide the sometimes different forming angles required for efficient forming.

[0009] EP 2 261 000 B1 discloses an angled ejector whose main feature is a combination of an ejector pin with an attached, angled ejector head, wherein the ejector pin and the angled ejector head are guided in a replaceable sliding bushing within the tool. The ejector head is detachably connected to the ejector pin via a joint. This joint allows the ejector head to be angled relative to the longitudinal axis of the ejector pin in order to achieve a clearance angle required for forming an undercut. A first disadvantage of this solution is that only a limited lateral offset can be achieved due to the limited vertical stroke of the angled ejector and the limited cross-section of the opening in the inner wall of the sliding guide.A further disadvantage is that a sliding bushing adapted to both the plates and the ejector pin with an angled ejector head must be provided in the tool. This represents additional effort and requires a considerable amount of space. Furthermore, an inclined ejector designed in this way, like the solutions listed below according to EP 0498102 B1 or EP 3372377 B1, represents a custom solution whose effective length cannot be subsequently modified or adjusted.

[0010] EP 0 498 102 B1 discloses a dimensionally stable and simply constructed inclined slide of an ejector device, which ejects undercuts in plastic injection molds. When installed in the mold, the inclined slide is designed at a predetermined angle within a square sliding guide in the manner of a sliding guide. This angle is achieved by attaching a first end of the inclined slide at a fixed angle to a coupling, which then slides along a holder attached to the mold ejection plates. The individually designed inclined slide is individually designed for each injection molding tool or die-casting tool and requires a sliding guide adapted to it, as well as at least one coupling element, in order to be able to replace the elements of the inclined slide if necessary. This usually requires the entire tool of the plastic injection mold to be dismantled.The size of the undercut to be demolded, the required horizontal displacement of the inclined slide, and the required travel of the entire ejector device determine the angle at which the inclined slide operates. A first disadvantage is that the inclined slide, which must be designed in relation to the dimensions of the injection molding tool or die casting tool, requires a special construction for each mold. A further disadvantage is that the square thrust guide must be laboriously inserted within the ejector plates of the injection mold or die casting mold. Each such ejector device therefore requires special adaptation of all its elements to the specific injection molding tool or die casting tool. Such adaptations are generally expensive and time-consuming, which represents a further disadvantage.

[0011] EP 3 372 377 B1 discloses an ejector whose main feature is a slide consisting of a flexible tension and compression element. The flexible element is represented by a helical spring that cannot be compressed within limits, with the coils of the helical spring ideally being in contact with one another at all times. A further feature of the ejector is an internal wire that runs between the base and head ends of the ejector, is clamped at these points, and gives the helical spring an initial preload when assembled. This is an ejector that, unlike the inclined slide known from EP 0 498 102 B1, is accommodated in bores within the ejector plates and therefore does not require a separate sliding element for guidance within the tool.A special feature of this solution is that this ejector design includes a tension and compression element with a predetermined initial length in the assembled state, which is supposedly designed to be neither further compressible nor extendable. Another special feature is that this ejector device exhibits a flexibility and elasticity that is more like a mechanical spring than a mechanical spindle. The flexibility of the mechanical spring allows the central element of the ejector device to adapt to the geometry of the aforementioned holes in the ejector plates. This allows the coil spring to flexibly follow the line defined by the holes in its angular position.

[0012] The described advantage of this solution, however, entails a first disadvantage, which lies in the flexibility and thus the elasticity of the coil spring used. This disadvantage manifests itself in a change in length caused by the elongation of the coil spring during operation. This elongation can only be limited to a limited extent by the internal wire, to which the elongation of the wire also contributes. The resulting change in length leads to a progressive loss of the coil spring's preload, which, together with the compressive and tensile loads that arise during operation, leads to premature fatigue of the tension and compression elements of the ejector device. In addition, due to its irregular shape factor, the coil spring causes increased friction on the walls of the bores within the tool. The non-removable abrasion generated by this friction represents a further disadvantage of this solution.Finally, the stretching of the coil spring as well as the resulting abrasion cause increased wear of the entire ejector device, which is a further disadvantage of this solution.

[0013] None of the solutions known from the aforementioned prior art has a modular concept that can be modified using simple solutions, which represents a suitable combination of similar elements with standard parts in order to produce adaptable embodiments corresponding to the respective application with little effort.

[0014] The invention is therefore based on the object of developing an inclined ejector as described above for an ejector device of an injection mold or die-casting mold in such a way that, on the one hand, it has a high degree of dimensional stability and low play to absorb large ejection forces, while at the same time being flexible, and, on the other hand, it is constructed from exchangeable, extendable and adjustable elements that are as similar as possible in order to eliminate the aforementioned disadvantages of the prior art.

[0015] Disclosure of the invention

[0016] This object is achieved by a device for demolding a cast component with an undercut from a casting mold for a casting process or an injection molding process with an ejector according to claim 1.

[0017] Further embodiments are specified in the dependent claims.

[0018] Accordingly, a device, in particular an inclined ejector, for demoulding a cast component with an undercut from a casting mould for a casting process, in particular for an injection moulding process or die-casting process with an ejector, is proposed, comprising:

[0019] - an ejector head with a profile that is complementary to the cast component with the undercut and is slidably mounted in a recess between a casting position and an ejection position,

[0020] - an ejector base movable in the translational direction;

[0021] - a link chain which mechanically connects the ejector head to the ejector base in order to realise a force and movement deflection, wherein the link chain has a plurality of chain segments which interlock in the longitudinal direction and which have little play with regard to tension and pressure in the longitudinal direction and which allow tilting against one another in at least one first transverse direction.

[0022] A first advantage of the solution according to the invention is the adaptability of the inclined ejector by lengthening or shortening it in order to adapt the inclined ejector to the geometry of the tool, in particular the functions and dimensions of the plates used therein. For this purpose, the link chain can advantageously be lengthened or shortened by adding or removing similar chain segments. In particular, the inclined ejector according to the invention combines the properties of rigid elements with the advantages of a flexible chain solution. In this context, flexible means that the link chain is designed with little play with regard to tension and compression in the longitudinal direction (i.e. an arrangement direction of the chain segments) and the chain segments of the link chain allow tilting relative to one another in at least one transverse direction, preferably the first transverse direction, which runs perpendicular to the longitudinal direction.The link chain is designed to be inelastic beyond the material elasticity that must be considered during construction and exhibits no spring properties, particularly in the longitudinal direction. This gives the link chain fatigue-resistant properties, in contrast to inclined ejector solutions that are merely designed for operational durability and incorporate springs or elastic link rods.

[0023] A further advantage of the inventive solution lies in the possibility of combining elements of different designs and / or dimensions to provide various embodiments of the inventive inclined ejector for different tools with different plate geometries, numbers of plates, and / or plate functions. For example, the same base piece can be accommodated in a link chain of larger or smaller diameter or longer or shorter length, thanks to the standard design of the fastening means according to a standardized screw connection (ISO thread). In a further embodiment, the link chain of the aforementioned embodiment can be combined with a transition piece of larger or smaller diameter and / or different length.Finally, in a further embodiment, the transition piece of the aforementioned embodiment can be combined with an ejector head of different shape and / or larger or smaller diameter and / or different length. This allows different embodiments of the inclined ejector according to the invention to be provided from elements with the same function but different designs and / or dimensions.

[0024] In particular, at least two of the interlocking chain segments can be joined by inserting a chain segment head of one of the chain segments into a chain segment head receptacle of another chain segment in a second transverse direction, in particular perpendicular to the first transverse direction and perpendicular to the longitudinal direction. According to this first, advantageous aspect, the pliable, flexible element of the inclined ejector can be designed as a link chain consisting of similar chain segments as well as a base piece and head piece, wherein the elements of the link chain are pushed laterally into one another at joints for assembly. As a result, the link chain has a structurally designed pliability, in particular in a first transverse direction, whereas in a second transverse direction perpendicular to the first direction, the pliability is limited beyond the elasticity of the material used in the elements.The elements of the link chain can preferably be made of metallic material, although temperature-resistant plastics or ceramics can also be used as alternative materials.

[0025] In a preferred embodiment, the chain segment can have differently shaped sections. A first section is represented by a chain segment head, a second section by a chain segment neck, a third section by a chain segment shoulder, a fourth section by a chain segment body, and a fifth section by a chain segment foot.

[0026] It can be provided that at least one of the chain segments has one or two chain segment heads which project opposite one another in the longitudinal direction and which engage with little play in a correspondingly complementary chain segment head receptacle of another of the chain segments, so that tilting of the chain segments is possible only in the first transverse direction.

[0027] Furthermore, at least one of the interlocking chain segments can have at least one chain segment head projecting in the longitudinal direction, which is cylindrical and has an at least partially segment-like, circular-cylindrical outer surface, wherein a tapered chain segment neck is provided with respect to the longitudinal direction, so that two interlocking chain segments are each held together by the engagement of one of the chain segment heads in the corresponding chain segment head receptacle and are pivotable with respect to the first transverse direction.

[0028] In particular, the chain segments can have a circular-cylindrical base body with respect to the longitudinal direction and an axial through-opening in the longitudinal direction, wherein a flexible fixing element is guided through the through-openings of the chain segments in order to hold the chain segment head of one of the chain segments in the corresponding chain segment head receptacle of the further chain segment.

[0029] The axial through-hole, which can preferably be created by erosion or by means of a through-hole, can thus be located within the chain segment head of the preferred embodiment. The flexible fixing element, which can be designed as a wire or flexible rod, can be accommodated within this through-hole and fixates the assembled chain segments to each other within the link chain in a positionally accurate manner, similar to a core.

[0030] In particular, the chain segment neck can be received in a chain segment neck receptacle with play in the first transverse direction in order to allow tilting of the chain segments by a predetermined angle.

[0031] Within the chain segment body of the preferred embodiment, there can be a recess, which can preferably also be produced by erosion and is referred to as the chain segment head receptacle. This chain segment head receptacle accommodates a chain segment head, which is pivotally arranged therein. The shape of the chain segment head and the chain segment head receptacle have corresponding contours, whereby the contours of the chain segment head and the chain segment head receptacle can represent circular-segment-cylindrical bodies with different radii. With regard to their fit with one another, both the chain segment head and the chain segment head receptacle can be designed, in particular, with a clearance fit H7 / g6, which has a maximum bearing tolerance of up to 0.02 mm. This results in minimal clearance between the chain segment head and the chain segment head receptacle.

[0032] Furthermore, at least one of the chain segment heads can be arranged between two chain segment shoulders extending in the first transverse direction and / or lying opposite one another, wherein a chain segment head receptacle, in which the at least one chain segment head is received, is arranged between two chain segment feet extending in the first transverse direction and / or lying opposite one another, wherein the chain segment shoulders and chain segment feet lie opposite one another and enclose an angle within which tilting of the chain segments by a predetermined angle is possible. The chain segment neck of the preferred embodiment is located in the transition region between the chain segment head and the chain segment shoulder and has a relief cut. This relief cut is characterized by a radius and represents the base point of a joint.This joint is formed by the positive and frictional sliding play of the chain segment head in the chain segment holder above the chain segment neck, as well as by the mutual contact of the chain segment shoulder and the chain segment foot.

[0033] The contour of the chain segment foot and the chain segment shoulder can, in a preferred embodiment, be designed as a straight bevel. In this preferred embodiment, the bevel of the chain segment foot and the chain segment shoulder can enclose an angle with one another when the chain segments are assembled. This angle can be between 1° and 5°, preferably 3°. By means of closely dimensioned, complementary contact surfaces, on the one hand between the chain segment head and the receptacle of the chain segment head and on the other hand between the chain segment shoulder and the chain segment foot, limited, defined angulations can be created between the chain segments. In the preferred embodiment of the chain segments, the angulation between the chain segments occurs only in one plane; in contrast, there is no angulation in the plane perpendicular to this.This creates a flexible link chain which, in the spaces between the plates within the tool and without any guide, can perform an angled translational movement to move the ejector head between a casting position and an ejection position.

[0034] In a further conceivable embodiment of the chain segment, a "male" designed chain segment body is conceivable, wherein this chain segment body has a chain segment head and a chain segment neck as well as a chain segment shoulder at each of its ends. Complementary to this further conceivable embodiment of the chain segment, a "female" designed chain segment body is conceivable, wherein this chain segment body has a chain segment head receptacle and a chain segment foot at each of its ends. The "male" and "female" chain segment bodies can be inserted into one another in alternating sequence to obtain a further embodiment of the link chain. Within the "male" and "female" chain segment bodies of this further conceivable embodiment, there can be a through-opening, which can preferably be created by means of erosion or by means of a through-bore.Within this through-opening, a fixing element can be accommodated, which can be designed as a wire or flexible rod and fixes the mounted chain segments within the link chain in a positionally accurate manner in the manner of a core.

[0035] In a further conceivable embodiment, the contours of the chain segment base and the chain segment shoulder can be rounded. In this further embodiment, the rounding of the chain segment base and the chain segment shoulder can preferably have a mutually complementary forming radius or rolling radius. In this further embodiment of the chain segments, the angulation between the chain segments can occur in at least one first plane and additionally in at least one second plane at an angle to the first plane.This further embodiment of the chain segments can be used within tools in which, due to transverse forces acting on the link chain, it may be necessary for the link chain to deflect by a limited amount into at least a second plane in order, on the one hand, to create increased flexibility within the link chain and, on the other hand, to avoid breakage of the link chain.

[0036] In the preferred embodiment, as described above, the chain segments that can be joined together can be designed as a closely spaced joint in the manner of a hinge, using a low-play fit H / 7g6, whereby the resulting, flexible link chain has, on the one hand, high strength and dimensional stability and, on the other hand, flexibility that can be achieved in a defined direction. By means of the chamfering or rounding of the chain segment foot and the chain segment shoulder, a tilt angle ß can be created between the chain segments after joining, at which angle a first chain segment body can be tilted relative to another chain segment body. The larger this tilt angle ß is in relation to the diameter D of the link chain, the larger the bending lines the link chain can traverse, free-standing or in the lead-through or guide, characterized by an angle of inclination α.An achievable horizontal ejection offset S is proportional to the inclination angle α and runs perpendicular to the reference axis A. The inclination angle α results from the geometric addition of the tilt angle β that occurs between the chain segments. Consequently, the tilt angle β determines the movement of the inclined ejector at the inclination angle α relative to the reference axis A. This advantageously results in a predetermined lateral ejection offset S being able to be achieved by means of the vertical ejection stroke L, depending on the course of the movement of the inclined ejector, characterized by the inclination angle α of the link chain. The direction of the movement of the inclined ejector is thus geometrically determined from the superposition of the vertical ejection stroke L with the lateral ejection offset S. The greater the vertical ejection stroke L and the lateral ejection offset S, the larger the undercuts that can be demolded.Depending on the design of the undercut and the number of plates used in the mold, the required superposition of the vertical ejection stroke L with the lateral ejection offset S can be achieved to achieve optimal demolding and ejection results. A further advantage is that, with a constant ejection stroke L, the effective length of the inclined ejector can be changed by inserting additional chain segments into the link chain, depending on the number of plates used in the mold. When changing the mold, for example by changing either the number of plates in the mold or their respective thickness, particularly when changing the cavity plate, an appropriately configured inclined ejector can be varied to enable different demolding angles for differently shaped undercuts.The size of the vertical ejection stroke L and the adjusting lateral ejection offset S is therefore crucial for successful demoulding and the subsequent ejection of the undercut.

[0037] The base part of the link chain can have an internal threaded portion at a first end and a head at a second end, the contour of which corresponds to the chain segment head found in the link chain. The head part of the link chain can have an internal threaded portion at a first end and a receptacle at a second end, the contour of which corresponds to the receptacle for the chain segment head found in the link chain.

[0038] For this purpose, it can be provided that the fixing element is additionally slidably mounted in the through-opening in order to secure a foot part of the link chain and the chain segments and a head part of the link chain against mutual shearing out in the second transverse direction.

[0039] During continuous operation, despite a tight fit, unavoidable bushing or hinge wear occurs between the chain segments. This can, on the one hand, reduce the dimensional stability of the link chain and, on the other hand, cause abrasion between the chain segments, which can lead to a minimal change in the length of the link chain. Due to dynamic elongation or compression of the link chain, the aforementioned effects can be intensified, resulting in a situation in which the ejector head of the inclined ejector either protrudes from the head-side molding area of ​​the cavity plate during the injection molding or die-casting process or is located below the head-side molding area, in other words, is no longer flush with the upper edge of the cavity plate.This can lead to irreparable defects during the molding and / or demolding of the undercut, even partially destroying the cavity plate or the molding area of ​​the injection plate within the mold. Consequently, the reject rate for faulty undercuts and thus defective plastic injection-molded or die-cast parts can significantly increase due to this misalignment of the ejector head. This situation can be prevented by adjusting the pretension of the link chain, which can be adjusted initially and during continuous mold operation, using an adjustable base with a fastening component.

[0040] Due to the strong mechanical stress during the injection molding or die casting process, the link chain of the inclined ejector is alternately either compressed or stretched, with the dynamic compression or elongation of the link chain occurring in the micrometer range. The pretension of the link chain is achieved using the adjustable foot piece with fastening part. The adjustable foot piece with fastening part is screwed into a thread within the foot section of the link chain during assembly and tightened using an initial torque. This screw connection can be retightened during continuous operation using a retightening torque. The pretension thus creates a pre-stretch of the link chain, which leads to an initial elongation of the link chain by 0.1 millimeters.

[0041] In all embodiments, the at least first and at least second chain segments can each have a recess, wherein the recess extends in the axial longitudinal direction of the chain segment and represents an internal bore arranged concentrically to the outer diameter of the chain segment. The chain segment(s) and the recess located therein can preferably be produced by wire erosion, in particular by electrical erosion or spark erosion, in order to create uniform, precise, and delicate contours on and within the chain segments. The recess can accommodate a fixing element, which can be designed as a wire or flexible rod and serves to fix the chain segments in a positionally accurate manner relative to one another and to prevent the chain segments from drifting or shifting relative to one another.A first advantage resulting from this is the internal position and loss protection of the chain segments during the assembly or disassembly process of the inclined ejector within the plates of the tool.

[0042] According to a further advantageous aspect, the link chain head and the transition piece of the inclined ejector can be slidably mounted on an inner wall of a passage and / or a guide, wherein the passage and / or guide can in particular have a round cross-section. The passage is preferably designed as a bore and can have several sections with different diameters and, depending on their dimensions and their geometric arrangement in the plates of the tool, can represent different contours in certain areas. This allows for straight and / or curved sections of the passage to be realized, particularly depending on the design of the transitions between the individual plates of the tool.In particular, a first curved section of the feedthrough can be formed in the lower area of ​​the feedthrough, directly above the base area of ​​the inclined ejector, which is followed by a first straight section further along the feedthrough. It is conceivable that a second curved section follows the first straight section, which in turn merges into a second straight section. This advantageously allows the use of an inclined ejector that can be adapted to the respective sections of the feedthroughs in the plates and to the specific features of the ejector head or cavity plate.The passage is preferably located in the cavity plate and / or other plates within the injection mold or die-casting mold, wherein the walls of the passage and the guide in particular represent a cylindrical contact surface for receiving the link chain as well as for receiving the transition piece. In a first embodiment, the cross-section of the passage can widen in sections, beginning in the region of the link chain receptacle at a first end of the cavity plate, transitioning into a first widening in the region of the guide of the transition piece, and ending in a second widening in the region of the recess at a second end of the cavity plate, which serves to receive the ejector head.The replaceable guide, through its angular position 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, angled position within the recess in the cavity plate. This ensures that the limited clearance angle created by the inclined ejector for forming the undercut is always maintained. The guide is preferably removably fixed by means of a press fit in the first widening of the feedthrough and can be replaced due to wear. The guide is mounted in the first widening of the feedthrough and can be designed as a round tube, whereby the round tube can be made of a metallic or ceramic material.

[0043] According to a further aspect, the ejector head can be designed in the form of a conical body and can be received 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 within the cavity plate, reduced resistance is achieved when forming an undercut. A further advantage is that this design effectively prevents the ejector head from being forced in the forming area of ​​the cavity plate. In a further advantageous embodiment, the ejector head can be a two-part body, wherein a first part of the ejector head can be a cylindrical base body of smaller diameter, which is permanently connected to a second part of larger diameter, in particular by means of a shrink fit, preferably in a concentric arrangement.The second member can in particular represent a conical or cylindrical body, the contour of which corresponds to the wall of the recess in the cavity plate for receiving the ejector head.

[0044] In a further embodiment, the ejector head can be a cylindrical body having the same diameter as the transition piece, as well as the link chain head, the link chain, and the foot piece. Such an embodiment can be used, for example, in the aforementioned injection molding tools or die-casting tools, which produce plastic injection-molded parts or die-cast parts without undercuts and have an exclusively vertical main demolding 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 manner of an extendable or shortenable ejector pin.

[0045] In addition to the previously described embodiments of the inclined ejector according to the invention, embodiments are also conceivable in which, in addition to the guide in the cavity plate, sliding sleeves are embedded in the feedthrough in the plates of the tool. Such sliding sleeves can be used in plates of injection molding tools or die-casting tools, where the elasticity of the plates causes deformation of the feedthrough walls during continuous operation. An undesirable effect could be increased friction or distortion of the link chain within the feedthrough, which could lead to a link chain break.Such sliding sleeves, similar to the guide, can be made of a metallic material, in particular a bronze or bronze-graphite alloy or ceramic material, and preferably have a flexibility corresponding to that of the link chain and a friction coefficient adapted to the sliding pairing between the sliding sleeve and the link chain. In particular, the sliding sleeve, made of a metallic material, in particular a bronze or bronze-graphite alloy or ceramic material, can be designed as a cylindrical tubular body.

[0046] Short description of the characters

[0047] Details of the invention are explained in more detail with reference to an exemplary embodiment illustrated in the accompanying figures. Identical multiple references to a component in one and the same figurative representation include both the singular and plural of the respective element depicted. Therein:

[0048] Figure 1a shows a longitudinal section of an embodiment of the inclined ejector and an undercut of an injection-molded or die-cast part, illustrating the situation at the end of the molding process and immediately before demolding of the undercut; Figure 1b shows a longitudinal section of an embodiment of the inclined ejector and a formed undercut of an injection-molded or die-cast part, illustrating the situation immediately after ejection and separation of the undercut from the cavity plate, as well as the undercut completely detached from the ejector head after demolding;

[0049] Figure 2a is a side view of the link chain removed from the assembly of the inclined ejector and the transition piece, in a straight line position relative to each other;

[0050] Figure 2b shows a plan view of a longitudinal section of the link chain removed from the assembly of the inclined ejector and of the transition piece, in a straight line position relative to each other;

[0051] Figure 3a shows a longitudinal section of the link chain removed from the assembly of the inclined ejector and the transition piece, in an inclined position to each other;

[0052] Figure 3b is a side view and partial longitudinal section of the link chain removed from the assembly of the inclined ejector and the transition piece, in an inclined position relative to each other;

[0053] Figure 4 shows detail A of three chain segments inclined relative to each other (three-part link chain section);

[0054] Figure 5 shows a single chain segment, which is removed from the link chain, in different views.

[0055] Description of embodiments

[0056] Figure 1a shows the inclined ejector 1 located in a plastic injection mold or die-casting mold in a first position (casting position), illustrating the situation immediately after the molding process of a cast component 2 (plastic injection-molded part or die-cast part) and before the molding of the cast component 2 with an undercut. The mold is formed by a recess 8 in a casting body. A conical ejector head 16 is located in a first position within the conical recess 8 in the molding area of ​​the cavity plate 3 immediately before the ejection process and is positively connected to the undercut.

[0057] A foot piece is located within an ejector plate 5, which constitutes an ejector base or a part thereof. The foot piece has a fastening part 11, which is located in a first position above the base plate 6.

[0058] Figure 1b shows the inclined ejector 1 located in a plastic injection mold or die-casting mold in a second position (ejection position) during the demolding process. The ejector plate 5 is moved into the second position, for example, by a piston of a hydraulic ejection cylinder (not shown) by means of a vertical ejection stroke L (34). In this step of the demolding process, the ejector head 16 is still positively connected to the undercut and thus to the plastic injection-molded part or die-cast part. The conical ejector head 16 moves into the second position during the demolding process, in which it detaches from the first wall 81 of the conical recess 8 in the head-side demolding area of ​​the cavity plate 3, while sliding along the second wall 82 of the conical recess 8 in the head-side demolding area of ​​the cavity plate 3 in the main demolding direction.

[0059] A link chain 12 is provided, which consists of interconnected chain segments 121. Due to the mechanically stable and low-play connection of the chain segments 121 to one another, the link chain 12 can be advanced into the second position within a gap 4, a passage 7, a passage 9, and a guide 91. To assist in threading the link chain 12 into the passage 9, a bevel 71 can be provided in the transition area between the passage 7 and the passage 9. Due to the dimensionally stable and flexible nature of the link chain 12, it can be moved, i.e. advanced, within the gap 4 without guidance and support. A passage 61 within the base plate 6, which is preferably designed as a bore, provides access to the foot piece with the fastening part 11.A screwdriver or a hexagon key or a multi-tooth key (not shown) can be inserted within the passage 61, by means of which the tightening torque of the base piece with fastening part 11 can be subsequently adjusted in order to readjust the pretension of the link chain 12.

[0060] Figure 1b shows the upper region of the inclined ejector 1, i.e., located above the inclined ejector 1 in a plastic injection mold or die-casting mold, remaining in its second position during the ejection process. The notch 161 of the ejector head 16 releases the cast component 2. From this step of the ejection process, the ejector head 16 is no longer positively connected to the undercut of the cast component 2. The injection molding plate (not shown) or die-casting plate (not shown) takes the plastic injection-molded part, represented by its undercut, and guides it away from the ejector head 16. The undercut of the cast component 2 is completely ejected in this step.

[0061] Figure 2a shows a side view and partially a longitudinal section of the link chain 12 and the transition piece 13. Here, these are in a straight position relative to each other. In the straight position, the chain segments 121 are not tilted relative to each other and the support areas of the chain segment feet 27 rest against complementary contact areas of the chain segment shoulders 28 of the respective chain segment 121. In this straight position, maximum vertical lifting forces can be achieved by means of the inclined ejector.

[0062] I can be generated, which represents an advantage in the design of the oblique ejector 1, in particular as a straight-shaped ejector pin.

[0063] Figure 2b shows a top view of a longitudinal section through the link chain 12 and the transition piece 13. In the base part 122 of the link chain 12, a threaded section 18 can be provided, which merges longitudinally into a bore 19 (through channel through the chain segments 121). A base piece with a fastening part 11 in the form of a standard screw can be screwed into the threaded section 18 (not shown). By means of the base piece with fastening part 11, on the one hand, the link chain 12 can be detachably connected to the ejector plate 5 of the tool, and on the other hand, by means of the screw-in depth and the tightening torque of the base piece with fastening part

[0064] II in the threaded section 18 the pretension of the link chain 12 can be adjusted.

[0065] As shown in Figure 2b, threaded sections 21, 22, 23 can be provided, which can serve to receive fastening means. The threaded sections 21 and 22 receive a first fastening means 14 in the form of a threaded pin (standard part), by means of which the link chain 12 is detachably connected to the transition piece 13. Threaded section 23 receives a second fastening means 15 in the form of a standard screw (not shown), by means of which the transition piece 13 is detachably connected to the ejector head 16. A fixing element 20 can be received within the bore 19. The fixing element 20 can be designed, for example, in the form of a wire, a wire rope or another flexurally elastic element.

[0066] The bore 19 runs centrally in the longitudinal axis 32 of the link chain 12 and can preferably be provided during the manufacture of the chain segments 121 as well as the foot and head sections 122, 123 of the link chain 12. The fixing element 20 located in the bore 19, on the one hand, represents a positional lock for the chain segments 121 as well as for the foot and head sections 122, 123 (starting and ending sections) of the link chain 12 during the assembly or disassembly process of the inclined ejector 1 in the tool. On the other hand, the fixing element 20, due to its elasticity, represents an internal return spring for the link chain 12, whereby the link chain 12 can return to its original shape after deflection.

[0067] Figure 3a shows a side view of the transition piece 13 connected to the link chain 12 in an inclined position relative to one another. The inclined position is created by the angling of the chain segments 121 relative to one another and relative to one another. The fixing element 20 (shown in outline) located in the bore 19 is forcibly bent by the angling of the chain segments 121 relative to one another and, as described above, represents a return spring for the link chain 12 due to its elasticity. The fixing element 20 also ensures, during assembly or disassembly of the inclined ejector 1, that the chain segments 121 do not deviate from one another in a second transverse direction and / or become lost within the tool during assembly or disassembly of the inclined ejector 1.

[0068] Figure 3b shows, in a side view and partly in a longitudinal section, the angle of inclination a (31) generated by bending the chain segments 121. The angle of inclination a (31) is established between the reference axis A (32) and the reference axis B (33) and can cover an angular range of 0 to 15 degrees, preferably an angular range of 5 to 10 degrees. Depending on the diameter D of both the link chain 12 and, in particular, the transition piece 13, a certain degree of slenderness of the inclined ejector 1 results. The degree of slenderness results from the ratio of its overall length, resulting from the length of the link chain 12 and the length of the transition piece 13, to the diameter D. The slimmer the inclined ejector 1 can be designed, the closer several similar inclined ejectors 1 can be positioned next to one another in the injection molding tool or die-casting tool.

[0069] Figure 4 shows a side view of detail A referenced in Figure 3b. In this detailed illustration, several interconnected chain segments 121 of a preferred embodiment are shown in a position inclined towards one another. By tilting the chain segments 121 relative to one another above the chain segment neck 29, a tilt angle ß (30) is formed after assembly of the chain segments 121 by means of the bevel of the chain segment foot 27 and the chain segment shoulder 28. Within the assembly of the link chain 12, several link chain sections 24 are formed, in each of which a chain segment head 25 is articulated into a chain segment head receptacle 26 in the manner of a low-play hinge. By means of this design, in addition to the greatest possible flexibility, maximum contour accuracy of the link chain 12 is achieved, which therefore has high dimensional stability and low linear expansion.The bushing play between the individual chain segments 121 is minimized in the design of the aforementioned low-play hinge, which reduces the wear of the link chain 12 and thus of the inclined ejector 1 as a whole.

[0070] Figure 5 shows various views of a single chain segment 121 of a preferred embodiment, removed from the assembly of the link chain 12. This embodiment is characterized by a circular-cylindrical chain segment body 29, a circular-cylindrical chain segment head 25, a complementary circular-cylindrical chain segment receptacle 26, and complementary bevels of the chain segment shoulder 28 and the chain segment foot 27. Due to these bevels, a tilt angle ß (30) of between 1° and 5°, preferably 3°, relative to the horizontal is formed between the chain segment shoulder 28 and the chain segment foot 27, with the chain segment neck 29 as the base point.Within the chain segment head 25 there is a through-opening 251 which, together with the through-openings 251 of the other chain segments, forms the bore 19 for receiving the fixing element 20 (not shown).

[0071] List of reference symbols

[0072] Inclined ejector

[0073] Cast component

[0074] Cavity plate

[0075] Space in the tool

[0076] Ejector plate

[0077] Base plate

[0078] Implementation within the base plate 6

[0079] Implementation in the foot area of ​​the cavity plate 3

[0080] Chamfer in the transition area between passage 7 and passage 9

[0081] Recess in the head-side forming area of ​​the cavity plate 3

[0082] First wall of the conical recess 8

[0083] Second wall of the conical recess 8

[0084] Implementation within the cavity plate 3

[0085] Guide within the cavity plate 3

[0086] Hole in the ejector plate 5

[0087] Base with fastening part

[0088] link chain

[0089] Chain segment

[0090] Foot part of the link chain 12

[0091] Head part of the link chain 12

[0092] transition piece

[0093] First fastener of the transition piece 13

[0094] Second fastening element of the transition piece 13

[0095] Ejector head

[0096] Notch in the ejector head 16

[0097] Hole in the ejector head

[0098] Threaded section in the foot area of ​​the link chain 12

[0099] Hole in the foot part 122 and head part 123 of the link chain 12

[0100] Fixing element threaded section in the head part of the link chain

[0101] Threaded section in the foot area of ​​the transition piece 13

[0102] Threaded section in the head area of ​​the transition piece 13

[0103] Chain segment section (three-part)

[0104] Chain segment head

[0105] Through hole in the chain segment head 25

[0106] Chain segment body

[0107] Chain segment head holder

[0108] Chain segment foot

[0109] Rounding in the transition area between chain segment foot 27 and

[0110] Chain segment head holder 261

[0111] Chain segment shoulder

[0112] Chain segment neck

[0113] Tilt angle ß

[0114] Angle of inclination a

[0115] Reference axis A

[0116] Reference axis B

[0117] Vertical ejection stroke L

[0118] Lateral ejection offset S

Claims

Claims: Device, in particular inclined ejector (1), for demolding a cast component (2) with an undercut from a mold for a casting process or an injection molding process with an ejector, comprising: an ejector head (16) with a profile that is complementary to the cast component (2) with the undercut and is slidably mounted in a recess (8) between a casting position and an ejection position, an ejector base (5) movable in a translational direction; a link chain (12) that mechanically connects the ejector head (16) with the ejector base (5) to achieve a force and motion redirection, wherein the link chain (12) has several longitudinally interlocking chain segments (121) that are in particular free of play with respect to tension and compression in the longitudinal direction and allow tilting relative to each other in at least one first transverse direction.Device according to claim 1, wherein at least one of the chain segments (121) has one or two opposing, longitudinally projecting chain segment heads (25) which engage without play in a correspondingly complementary chain segment head receptacle (261) of a further chain segment (121), so that tilting of the chain segments (121) is enabled only in the first transverse direction. Device according to claim 2, wherein at least one of the interlocking chain segments (121) has at least one longitudinally projecting chain segment head (25) which is cylindrical and has a circular cylindrical surface that is at least partially segmented, wherein a tapered chain segment neck (29) is provided with respect to the longitudinal direction, so that two interlocking chain segments (121) are each engaged by one of the chain segment heads (25) in the corresponding chain segment head receptacle (261). The chain segments (121) are held against each other and are pivotable with respect to the first transverse direction. The device according to claim 3, wherein the chain segment neck (29) is received in a chain segment head receptacle (261) with clearance in the first transverse direction to allow the chain segments (121) to tilt by a predetermined angle. The device according to claim 2, wherein at least one of the chain segment heads (25) is arranged between two chain segment shoulders (28) extending in the first transverse direction and / or opposing each other, wherein a chain segment head receptacle (261) in which the at least one chain segment head (25) is received is arranged between two chain segment feet (27) extending in the first transverse direction and / or opposing each other, wherein the chain segment shoulders (28) and chain segment feet (27) are opposite each other and enclose an angle within which tilting of the chain segments (121) by a predetermined angle is possible.A device according to any one of claims 1 to 5, wherein at least two of the interlocking chain segments (121) can be joined by inserting a chain segment head (25) of one of the chain segments (121) into a chain segment head receptacle (261) of a further chain segment (121) in a second transverse direction, in particular perpendicular to the first transverse direction. A device according to any one of claims 2 to 3, wherein the chain segments (121) have a circular cylindrical base body with respect to the longitudinal direction and an axial through-opening (251) in the longitudinal direction, wherein a flexible fixing element (20) is guided through the through-openings (251) of the chain segments (121) in order to hold the chain segment head (25) of one of the chain segments (121) in the corresponding chain segment head receptacle (261) of the further chain segment (121).Device according to claim 7, wherein the fixing element (20) is additionally slidably mounted in the through-openings (251) to secure a foot part (122) of the link chain (12) and the chain segments (121) and a head part (123) of the. The link chain (12) is secured against mutual shearing in the second transverse direction. Device according to one of claims 1 to 8, wherein the link chain (12) is guided in a passage (7, 9) and / or a guide (91) to redirect a force and movement acting on the ejector base (5) to the ejector head (16) in the main demolding direction.

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