WO2018036949A1

WO2018036949A1 - Injection mould comprising at least one cavity and method for at least partial extraction of a mould core

Info

Publication number: WO2018036949A1
Application number: PCT/EP2017/071000
Authority: WO
Inventors: Markus Deisinger
Original assignee: Gkn Driveline International Gmbh
Priority date: 2016-08-25
Filing date: 2017-08-21
Publication date: 2018-03-01
Also published as: DE102016115840A1; DE112017004186A5

Abstract

The invention relates to an injection mould comprising a cavity and a mould core that has an undercut and can be arranged in said cavity, with an inner core (16) and four groups (A, B, C, D) of segments, the groups (A, B, C, D) each consisting of two segments.

Description

Injection molding tool with at least one cavity and method for at least partial

Extraction of a mold core

The invention relates to an injection molding tool with a mold core having undercuts and a method for at least partial extraction of a mold core with at least one undercut from an injection molding tool. Furthermore, the invention relates to a mold core, a method for producing a bellows, the use of an injection molding tool for producing a bellows and a bellows made by injection molding.

From the state of the art injection molding tools are known, which are able to produce workpieces with undercuts. For example, go out

DE 10 2010 004 227 B4 discloses a method and a device for demoulding injection molded hollow bodies with undercuts in the inner contour. For this purpose, the mold core of the injection molding tool is divided into a plurality of segments, which can be moved in the direction of a central longitudinal axis after demolding of a central segment.

The methods known from the prior art and injection molding tools can achieve undercuts in inner contours of a workpiece up to about 40%. Stronger undercuts result in collisions between an embossing of the mandrel which forms the undercut and inner protrusions, such as an inner side of a folding valley of a bellows, or praise areas in the joint housing-side binder seat region in the case of bellows for tripod joints, which is the characteristic during demoulding happens.

The object of the present invention is to provide an improved injection molding tool and an improved mold core, an improved method for at least partially extracting a mold core forming at least one undercut, an improved method of manufacturing a bellows, an injection molding tool and an improved bellows , In particular, it is the task of the invention tion to provide an injection molding tool and a method for demolding the injection molding tool, which allows the provision of undercuts greater than about 40% in the inner contour of a workpiece, which is produced with the injection molding tool.

The object is achieved by means of an injection molding tool according to claim 1, a mandrel according to claim 15, a method for the extraction of a mandrel from an injection molding tool according to claim 1 6, a method for producing a bellows according to claim 18, a use of an injection molding tool according to claim 19 and by a bellows according to claim 20. Further advantageous embodiments can be taken from the following description, the figures and the dependent claims. However, the individual features of the described embodiments are not limited to these, but can be linked with each other with other features for further embodiments.

An injection molding tool is proposed having at least one cavity and a mold core which can be arranged in this cavity and has at least one undercut, with an inner core and four groups A, B, C and D of segments, the groups

A, B, C and D each consist of two segments, wherein preferably the groups A and D have different segments and / or the group B and C have mutually different or equal segments. The groups A, B, C and D preferably have mutually differently formed segments, that is to say all segment groups A,

B, C and D differ from each other in their design. The arrangement of the segments of the groups A to D in the tool, however, for example, mirror-inverted or rotated about the central longitudinal axis as the axis of symmetry can be carried out at structurally identical or mirror-symmetrical design of the segments.

Preferably, one group has exactly two segments. Advantage of the proposed injection molding tool is that by the pairwise design of the groups A to D of segments, which are preferably substantially simultaneously movable, workpieces with at least one undercut with a value greater than 40%, preferably greater than 45%, more preferably greater than 50% can be produced and the mandrel is extractable from the workpiece. The extraction of the mandrel takes place in particular after a molding of a hollow body. In particular, the extraction is carried out from the hollow body and the cavity in which the hollow body was formed.

For the purposes of the invention mold cores are used to inject hollow body made of plastic, in particular elastomeric or thermosetting plastics or other suitable for injection molding materials with internal threads, noses, depressions, notches, recesses and openings or recesses and other undercuts in its inner contour. Such hollow bodies are referred to below as workpieces. In a preferred embodiment, the workpiece comprises a number of undercuts. In one embodiment, the workpiece has at least one fold, preferably a number of folds. A fold includes in particular a fold valley and a fold tip. In one embodiment, the workpiece has different sized undercuts. In one embodiment, the workpiece has differently formed folds. In a further embodiment, it is provided that a covering the pleat tips changed in the longitudinal direction of the workpiece at least in a section in diameter. In a further embodiment, it is provided that a covering the pleat tips in the longitudinal direction of the workpiece at least in a portion tapers or decreases in diameter. In a further embodiment, it is provided that a covering the pleat tips in the longitudinal direction of the workpiece at least partially in diameter remains substantially the same. In a preferred embodiment, the workpiece is a

Bellows, preferably a bellows, in particular for automobiles of any kind, more preferably as trilobe bellows, in particular for tripod joints. Bellows have the particular task of preventing the ingress of dirt into a joint component and the escape of lubricants from the joint component. A pleat area of a bellows may have pleats of decreasing diameter from a hinged end have a shaft-side end, but also in a partial region of the fold region at least two folds may have a same diameter. Outside surfaces of the mandrel form the shape of the inner contour of the workpiece during spraying. In particular, the mold core is a bellows-forming mold core. Preferably, after a cooling time has ended, the mold core is extracted from the injection mold. Since the inner contour of the workpiece has undercuts, it is necessary that the mandrel has a smaller outer diameter than any inner diameter that is passed during the extraction. In particular, the outer diameter of the mandrel must be smaller than the smallest inner diameter of the workpiece. For this purpose, it is already known from the prior art to break the mold core into segments and to move the segments in the direction of the central longitudinal axis after the removal of an inner core, in order to move out manifestations of the mold core from the undercuts of the workpiece.

A value UC of an undercut in the sense of the invention is the percentage ratio of a first inner diameter DI of an inner contour of a workpiece to a second smaller inner diameter D2 of the inner contour of the workpiece, past which an expression of the mandrel for forming the first inner diameter during the extraction of the mandrel : UC = (D1 -D2) / D2 [%]

In the context of the invention, an undercut is an undercut of the inner contour of a workpiece, in particular a workpiece, which can be produced by means of the mandrel or by means of the injection molding tool. If the workpiece is, for example, a bellows, an undercut denotes the ratio of a maximum inner diameter of a pleat tip to a minimum inner diameter of a pleat valley, past which the characteristic for shaping the inner contour of the pleat tip is passed during the extraction from the injection mold. The mold core has a central longitudinal axis. The central longitudinal axis preferably extends in opening directions of the injection molding tool, preferably in the direction of movement of an actuator, by means of which the injection molding tool can be opened. With a substantially rotationally symmetrical workpiece along the longitudinal axis of the workpiece or hollow body, the central longitudinal axis preferably also extends along the central axis of the preferably substantially rotationally symmetrical workpiece.

If the term "substantially" is used in the context of the invention, this indicates a tolerance range which is to be considered by the skilled person from an economic and technical point of view, so that the corresponding feature can still be recognized or realized as such. In particular, a substantially rotationally symmetrical workpiece is at first glance to be rotationally symmetrical, wherein the workpiece may have details, for example flanges or other fastening means, which are not rotationally symmetrical.

A group of segments is characterized in particular by the fact that the segments are or can be moved substantially simultaneously. In particular, the segments of a group are simultaneously movable on one or more planes whose vector is parallel to the central longitudinal axis. More preferably, a group of segments is formed from the segments that are at least partially extractable from the injection molding tool substantially simultaneously. The movement of the segments of a group may in one embodiment begin and / or end at different times.

Unless otherwise stated, the mandrel is described in its closed state. The closed mandrel is the mandrel in which the inner core and all segments of the groups A, B, C and D are composed and in particular are arranged in a composite which is suitable for the formation of a workpiece.

The inner core of the mold core is preferably designed in such a way that it is shaped along its central longitudinal axis from the corresponding cavity of the injection molding tool. se can be moved out of the workpiece. Preferably, the inner core in a section along at least one plane whose vector is arranged parallel to the central longitudinal axis, round or polygonal, for example, hexagonal or octagonal, designed. In one embodiment, the inner core has a number of different diameters along the central longitudinal axis, for example, the inner core can be configured conically or with shoulders, wherein in one embodiment, the diameter in the direction of demolding of the inner core are designed to be larger. In a preferred embodiment, the inner core is made coolable. Techniques for cooling a mandrel are known in the art.

In one embodiment, the two segments of the group A are mirror-symmetrical with respect to a plane on which the central longitudinal axis of the mandrel is arranged. More preferably, the segments of the group A are formed axially symmetrically with respect to the central longitudinal axis. More preferably, the segments of the group A are formed with opposite, preferably parallel, contact walls to the adjacent segments of the groups B and C.

In a further embodiment, the segments of the group A are constructed substantially identical. In particular, the segments of the group B are substantially the same design with respect to an outer contour and / or an embodiment of the contact walls. More preferably, the segments of the group A with respect to a plane on which the central longitudinal axis of the mandrel is arranged, arranged opposite one another.

In one embodiment, the two segments of the group B are mirror-symmetrical with respect to a plane on which the central longitudinal axis of the mandrel is arranged. More preferably, the segments of the group B are formed axially symmetrical with respect to the central longitudinal axis. More preferably, the segments of the group B are formed with opposite and preferably parallel formed contact walls to the adjacent segments of the groups A and / or D. In a further embodiment the segments of group B at least one further contact wall to segments of the group D.

In a further embodiment, the segments of the group B are formed substantially identical in construction. In particular, the segments of the group B are substantially the same design with respect to an outer contour and / or an embodiment of the contact walls. More preferably, the segments of the group B with respect to a plane on which the central longitudinal axis of the mandrel is arranged, arranged opposite one another. Preferably, the segments of the group B are rotationally symmetrical about the central longitudinal axis to each other.

In one embodiment, the two segments of the group C are mirror-symmetrical with respect to a plane on which the central longitudinal axis of the mandrel is arranged. Further preferably, the segments of the group C are formed axially symmetrically with respect to the center longitudinal axis. More preferably, these segments of the group C are formed with opposite and preferably parallel formed contact walls to the adjacent segments of the groups A and / or D. In a further embodiment, the segments of the group C have at least one further contact wall to segments of the group D.

In a further embodiment, the segments of the group C are formed substantially identical. In particular, the segments of the group C are formed substantially the same with respect to an outer contour and / or a configuration of the contact walls. More preferably, the segments of the group C with respect to a plane on which the central longitudinal axis of the mandrel is arranged, arranged opposite one another. Preferably, the segments of the group B are rotationally symmetrical about the central longitudinal axis to each other.

In one embodiment, the two segments of the group D are mirror-symmetrical with respect to a plane on which the central longitudinal axis of the mandrel is arranged. More preferably, the segments of the group D are formed axially symmetrical with respect to the central longitudinal axis. More preferably, the segments of the group D are formed with contact walls to the adjacent segments of the groups B and C. In particular, the segments of group D have a number of contact walls with segments of group B and / or C.

In a further embodiment, the segments of the group D are formed substantially the same. In particular, the segments of the group D are formed substantially the same with respect to an outer contour and / or a configuration of the contact walls. More preferably, the segments of the group D with respect to a plane on which the central longitudinal axis of the mandrel is arranged, arranged opposite one another.

More preferably, each of the segments of the group D each have a projection. More preferably, this projection is immediately adjacent to the inner core in the retracted state. Preferably, the projection has a contact wall to the inner core. More preferably, the projection between two contact walls of the segments of the group D to the segments of the groups B and C is arranged. In particular, by the projection are preferably by means of the segment of the group D, the segments of the groups B and C separated from each other and are not in direct contact. Preferably, the segments of the group D are rotationally symmetrical about 180 ° with respect to the central longitudinal axis of the mandrel formed and arranged in the mandrel. As a result, the projections of the two segments of the group D are not opposite. When carrying out a movement, the segments of the group D can be guided past one another perpendicular to the central longitudinal axis of the mandrel and along the central longitudinal axis, whereby an extraction of the segments of the group D from the cavity of the injection molding tool or from the workpiece or hollow body, preferably a bellows , is made possible even with training of undercuts of over 50%, in particular well over 50%. In a further preferred embodiment, the wall portion of the two segments of the group D adjacent to the inner core in a cross section perpendicular to the central longitudinal axis has a maximum of about 25%, more preferably not more than about 20%, even more preferably no more than about 15% of a total length, formed from the length of Contact walls of the two segments of the group D to the two adjacent segments of the groups B and C, the length of the adjacent to the inner core wall portion and from the side walls of the projection, on.

In one embodiment, the segments of group A adjoin the inner core in such a way that they project beyond the corners of the inner core. The first, second and / or third wall sections adjoining the inner core are preferably arranged in particular at an angle to one another in accordance with the shape of the inner core. In one embodiment, the inner core is designed to be round, wherein the wall section of the group A which borders on the inner core preferably also has a correspondingly round configuration.

The inner core of the mold core is preferably designed such that it can be moved out along its central longitudinal axis from the corresponding cavity of the injection molding tool or from the workpiece. Preferably, the inner core in a section along at least one plane whose vector is arranged parallel to the central longitudinal axis, round or polygonal, for example, hexagonal or octagonal, designed. In one embodiment, the inner core has a number of different diameters along the central longitudinal axis, for example, the inner core can be configured conically or with shoulders, wherein in one embodiment, the diameter in the direction of demolding of the inner core are designed to be larger. In a preferred embodiment, the inner core is made coolable. Techniques for cooling a mandrel are known in the art.

Preferably, the pairs of segments of each group A to D are substantially identical or mirror-symmetrical to one another. Preferably, the segments of the Groups A and D are larger in size, with respect to each cross-section of the mandrel, a larger area than the segments of groups B and C.

In a cross-section perpendicular to the central longitudinal axis, the segments of the group C preferably have a wall section which is at least approximately 30%, more preferably at least approximately 50% longer, which is adjacent to the inner core than the segments of the group B.

In a further preferred embodiment, the segments of the group A have at least two wall sections which are formed at an angle to one another and adjoin the inner core directly. More preferably, the segments of the groups A, B, C and / or D have a single, rectilinear wall portion that is immediately adjacent to the inner core.

In a further preferred embodiment, the segments of the groups A to D are rotationally symmetrical in a rotation about 180 ° about the central longitudinal axis formed and arranged. In particular, in each case the segments of the group A, B, C and / or D are substantially congruent, preferably the surfaces forming the workpiece are conical. More preferably, the geometric configurations are each two segments of a group A, B, C and / or D congruent. More preferably, the two segments of the group D are displaceable differently far perpendicular to the central longitudinal axis of the mandrel, so that at least one of the segments of the group D covers the central longitudinal axis in the shifted state.

In a further embodiment it is provided that in a circumferential direction of the mandrel alternately segments of the groups A and D and segments of the groups B and C are arranged. In one embodiment, the segments of the groups A, C, D, B, A, C, D, B or vice versa are arranged in the circumferential direction. In a further preferred embodiment, the segments of the groups A, B, D, C, A, B, D, C or vice versa are arranged in the circumferential direction. The two segments of the first groups A and D become preferably first (group A) and last (group D) proceed, whereas the two groups B and C of second segments are temporally moved between them, with a temporal overlap of stopping and incipient operation of successive groups, as geometrically possible, can take place.

In a further embodiment, it is provided that the groups A and D of segments in a direction of movement substantially perpendicular to the central longitudinal axis, preferably to this, are movable. The segments are preferably moved in a further step after their first movement along the central longitudinal axis of the mandrel.

In one embodiment, at least one of the groups B and / or C of segments can be moved in at least two directions of movement on at least one plane whose vector is arranged parallel to the central longitudinal axis. In one embodiment, the segments of the group B and / or C can be moved in a further step, for example after their movement on the central longitudinal axis, along the central longitudinal axis of the mold core. In a further embodiment, it is provided that at least one group B and / or C of segments can be moved in at least two directions of movement on at least one plane whose vector is arranged parallel to the central longitudinal axis. This group of segments is preferably moved in a further step after the first movement along the central longitudinal axis of the mandrel. The operation of the segments of the groups can be done for example hydraulically or pneumatically.

The individual segments each have an outer contour that lies opposite the workpiece to be sprayed. The outer contour in the sense of the present invention is thus the part of the surface of a segment which is shaping. In particular, the outer contour of a segment forms a partial surface of a preferably rotationally symmetrical body.

In one embodiment, it is provided that the group A of segments has an outer contour a and the group D of segments has an outer contour d, the outer Contours a and d are different. Preferably, the workpiece forming outer contour a and d are different in size. The surface of the outer contour a forming the workpiece is preferably larger than the outer contour d forming the workpiece. Furthermore, it is provided in one embodiment that in a cross section perpendicular to the central longitudinal axis, the cross-sectional area of a segment A is smaller than a cross-sectional area of the segment D.

In a further embodiment, it is provided that a surface of the outer contour a is smaller than a surface of the outer contour d. In particular, the outer contour a has a smaller surface forming the workpiece than the outer contour d. Furthermore, it is provided in one embodiment that in a cross section perpendicular to the central longitudinal axis, the cross-sectional area of a segment A is smaller than a cross-sectional area of the segment D.

In a further embodiment, it is provided that the groups A and D of the segments are movable in one or two directions of movement perpendicular to a central longitudinal axis of the mandrel. In a further embodiment it is provided that the groups B and C of the segments are movable in one or two directions of movement perpendicular to a central longitudinal axis of the mandrel. In a further embodiment, it is provided that at least segments of a group, preferably the segments of group B and / or C, are movable in at least two directions of movement on at least one plane whose vector is parallel to the central longitudinal axis of the mandrel. The movement on the plane, the vector of which is arranged parallel to the mid-perpendicular of the mold core, can be superimposed in one embodiment at least partially with a movement in the direction of the central longitudinal axis.

In one embodiment, at least one segment of the group B and / or C is preferably movable in at least two directions of movement, wherein the movements preferably take place substantially successively or simultaneously. In a further embodiment provided that at least one segment, preferably the group B and / or C, three, four or more directions of movement preferably substantially successively or simultaneously on at least one plane whose vector is parallel to the central longitudinal axis, can perform. It is further preferred that the directions of movement of at least individual segments of the group B and / or C are completely overlapped in time or in terms of time. In the case of an overlapping, an oblique or angular movement in the plane whose vector is arranged parallel to the central longitudinal axis, preferably directly or indirectly towards the central longitudinal axis, thus takes place. In one embodiment, it is provided that a group of segments, preferably at least one segment of the group B and / or C, moves at least in two directions of movement, in particular on at least one plane whose vector is parallel to the central longitudinal axis, wherein the movements essentially successively or take place simultaneously. In a further embodiment, it is provided that a group of segments, preferably at least one segment of the group B and / or C, three, four or more directions of movement preferably substantially successively or at least partially simultaneously on at least one plane whose vector is parallel to the central longitudinal axis , performs. If several directions of movement of a segment are superimposed, the result is a resulting direction of movement as a function of the motion vectors of the superimposed directions of movement. If, for example, two movements with different motion vectors are performed simultaneously, that is superimposed, then the resulting direction of motion is determined by the vector addition of the individual motion vectors. Preferably, a superimposition of a first movement directions or of a first movement vector with a second movement direction or with a second movement vector is provided substantially temporally towards the end of execution of a movement direction, so that movement directions are in particular only partially overlapped. In one embodiment, at least two directions of movement are carried out without superposition of the same time in succession. In one embodiment, it is provided that at least two directions of movement comprise at least one change of direction. It is preferably provided that at least two rectilinear movements tions on a plane whose vector is parallel to the central longitudinal axis, follow each other in time. In a further embodiment, it is provided that at least two straight-line movements on a plane whose vector is parallel to the central longitudinal axis are connected to a curved movement, in particular with a change in the direction of movement over time. In a further embodiment, it is provided that at least one segment of at least one group executes only a curved movement on a plane whose vector is parallel to the central longitudinal axis. A curved movement is carried out in particular by a superimposition of a plurality of directions of movement or addition of a plurality of motion vectors, which change in particular over time. In a further embodiment it is provided that at least one curved movement is provided on a plane whose vector is parallel to the central longitudinal axis. A superimposition of the movements leads to an oblique or angular movement in the plane whose vector is arranged parallel to the central longitudinal axis, in particular substantially to the central longitudinal axis. Further preferably, it is provided that each individual segment of the group can be moved successively or simultaneously. Further preferably, it is provided that each segment of the group moves in each case one of the other segments different direction of movement. It is particularly preferably provided that at least one direction of movement of the segments of the group takes place radially, that is to say in the direction of the central longitudinal axis. In a further preferred embodiment, it is provided that a movement takes place on at least one plane, the vector of which is parallel to the central longitudinal axis, and the movement along the central longitudinal axis occurs simultaneously or substantially one after the other. In particular, an embodiment provides that at least one movement of at least one segment of the group is carried out in exactly one or more directions of movement which accompanies a movement along the central longitudinal axis.

More preferably, it is provided that each individual segment of the groups A to D is successively or simultaneously movable. It is further preferred that each segment of the group B and / or C moves in each case in a different direction of movement of the other segments. It is particularly preferred that at least one movement tion direction of the segments of the group B and / or C radially, that is in the direction of the central longitudinal axis occurs. In a further preferred embodiment, it is provided that a movement takes place on at least one plane, the vector of which is parallel to the central longitudinal axis, and the movement along the central longitudinal axis occurs simultaneously or substantially one after the other. In particular, an embodiment provides that at least one movement of at least one segment of the group B and / or C is carried out in one or more directions of movement preferably successively or partially superimposed, which is at least partially superimposed by a movement along the central longitudinal axis.

In a further embodiment, it is provided that the segments of group B and / or C are movable in one direction on a plane whose vector is parallel to the central longitudinal axis. In a further embodiment, it is provided that the segments of group A and / or D are movable in one direction on a plane whose vector is parallel to the central longitudinal axis.

In a further embodiment, it is provided that the groups B and C of segments have identical, mirror-inverted or mutually different outer contours b and c.

In one embodiment, it is provided that the group B of segments has an outer contour b and the group C of segments has an outer contour c, wherein the outer contours b and c are different, in particular of different sizes. In one embodiment, it is provided that the group B of segments has an outer contour b and the group C of segments has an outer contour c, wherein the outer contours b and c are the same, in particular the same size.

In one embodiment, contact walls of the segments of the groups A to D, preferably B and / or C, which are in contact with the inner core are formed differently or identically. More preferably, the contact walls of the segments of the groups b and / or c with the inner core are different or the same size. Preferably, the contact wall to the inner core of the segment of the group B larger or smaller than the contact wall to the inner core of the segment of the group C. In a further embodiment, the contact wall of a segment of the group B to the inner core is substantially as large as the contact wall of a segment of the group C to the inner core ,

In a further embodiment, it is provided that a surface of the outer contours b and / or c are the same size or smaller than the surface of the outer contour a.

In a further embodiment, it is provided that a surface of the outer contour b is smaller or larger than a surface of the outer contour c. Furthermore, it is provided in one embodiment that in a cross-section or all cross-sections perpendicular to the central longitudinal axis, the cross-sectional area of a segment B is smaller or larger than a cross-sectional area of the segment C. It is further provided in an embodiment that in a cross section perpendicular to the central longitudinal axis, the cross-sectional area of Segmentes B is formed the same as a cross-sectional area of the segment C. In particular, the segments of the groups B and C have a mutually identically formed or mirror-symmetrical outer contour b and c.

In one embodiment, the outer contours a, b, c, d, in particular an extension direction of at least one undercut, more preferably the ribs of a bellows, adapted to the movements of the individual segments in the extraction of the mandrel. Preferably, an adaptation takes place in such a way that the extraction of the segments, for example of the groups B and C, takes place without collision with the workpiece to be manufactured, in particular with superposed directions of movement on the central longitudinal axis to and along the central longitudinal axis. More preferably, an inner side of an edge of a fold of a bellows is angled so that a movement of at least one segment of the mandrel in the direction of the central longitudinal axis and preferably along the central longitudinal axis takes place without collision with the bellows. More preferably, a movement pattern of at least one segment is adapted to the shaping of a flank of the bellows. In one embodiment, it is provided that the respective two segments of the groups A and D and / or the groups B and C are identical. In one embodiment, it is provided that the respective two segments of the groups A and D and / or the groups B and C are mirror-symmetrical. In a further embodiment it is provided that the segments of at least one of the groups A, B, C and / or D are designed to be identical or mirror-symmetrical. For example, the segments of the group B and the segments of the group C are each formed the same and a segment of the group B have a mirror image of a segment of the group C.

In one embodiment, it is provided that the two segments of the group D are arranged asymmetrically opposite one another in the mold core. It is further preferred that the segments of the group D are arranged rotationally symmetrical to each other. In one embodiment, it is provided that the two segments of the group D are formed axially symmetrically opposite each other in the mold core.

In one embodiment, it is provided that between a first and a second contact wall of the segments of the group D, a projection is formed which adjoins the inner core. Preferably, the projection protrudes from a plane of at least one contact wall to a respective segment of the groups B and / or C. More preferably, the projection is at least partially in contact with at least one segment of the groups B and / or C.

In one embodiment, it is provided that the projections are arranged offset opposite to the two segments of the group D in a closed mold core. This has the advantage that the projections during removal from the mold, that is, in particular during the movement of the segments of the group D toward each other, can be guided past one another.

The projection has at least two, preferably at least three wall sections, wherein more preferably a first wall section of the projection has a contact with a segment of the group B and a second wall section of the projection has a contact with a segment of the group C. More preferably, a third wall section and further, a fourth wall portion of the protrusion preferably contacts the inner core. In one embodiment, the first wall section and the second wall section are configured parallel to one another. In a further embodiment, the first and the second wall section are configured at an angle to each other in a cross section perpendicular to the central longitudinal axis. Preferably, the angles of the first and / or second wall portions are configured such that the segments of group B and / or C can be moved past the projection substantially immediately perpendicular to the central longitudinal axis. In particular, the third and / or fourth wall section are designed such that they rest against the inner core. A fourth wall section is preferably provided when the projection adjoins a corner of the inner core. In one embodiment, the inner core is round, wherein preferably the third wall portion is designed to be round. In a further embodiment it is provided that the projection has a first or a second and a third and optionally a fourth wall section. Preferably, the protrusion is then configured such that the third or fourth wall section adjacent to the inner core connects to a contact wall of the segment to form another segment B or C. Preferably, the first wall portion having a segment of the group B adjoins the contact wall to a segment of the group B, and more preferably the second wall portion having a segment of the group C is adjacent to a contact wall to a segment of the group C. The first and second wall sections are to be addressed as contact walls to the segments B and C.

In a further embodiment, it is provided that the segments of the group D each have a first and a second contact wall to a respective segment of the groups B and C, which are formed linearly or collinearly in a cross section to each other. In a further embodiment, it is provided that the segments of the group D each have a first and a second contact wall to a respective segment of the groups B and C, which are arranged on one level or on substantially parallel planes. In a further embodiment, it is provided that the two segments of the group D are moved to different degrees perpendicular to a central longitudinal axis of the mandrel, so that at least one of the two segments of the group D at least partially covers the central longitudinal axis.

In a further embodiment, it is provided that the segments of the group D can be moved to a central longitudinal axis of the mandrel with different lengths paths. In one embodiment, the segments of the group D are moved differently far in the direction of the central longitudinal axis. In particular, the group D is movable in such a way that, in the case of the movement oriented in the direction of the central longitudinal axis, at least one segment can be moved closer to the central longitudinal axis than a further segment of the group. More preferably, the segments in the movement in the direction of the central longitudinal axis are asymmetrically positionable with respect to the central longitudinal axis. In a further embodiment, it is provided that at least one segment is at least partially movable beyond the central longitudinal axis.

Advantage of the different travel paths of the segments of the group D is that when extracting the segments from the workpiece a collision with characteristics of the inner contour of the workpiece, which differ for example from a rotational symmetry, is avoided. In a further embodiment it is provided that the individual segments of the

Groups A, B, C and / or D mirror-symmetrically or axially symmetrically to each other are movable, preferably axially symmetric with respect to the central longitudinal axis.

Furthermore, a mold core for an injection molding tool described above is proposed.

The mold core for an injection molding tool in one embodiment comprises an inner core and four groups A, B, C and D of segments, wherein the groups A, B, C and D each consist of two segments. In the circumferential direction of the mandrel, segments of the different groups are preferably arranged alternately, and the groups A, B, C, D of segments are movable in a direction of movement substantially perpendicular to a central longitudinal axis of the mandrel. In one embodiment, it is provided that the segments of the groups B and C are movable in two directions of movement on at least one plane whose vector is arranged parallel to the central longitudinal axis. Preferably, the segments of the groups A, B, C and / or D are also designed to be movable along the central longitudinal axis of the mandrel.

The present invention alternatively proposes a mold core for an injection molding tool having an inner core and having four groups A, B, C and D of segments, wherein the groups A to D each consist of two segments and, in a circumferential direction of the mold core, alternately segments of different groups, preferably in the order A, C, D, B, A, C, D, B or A, B, D, C, A, B, D, C are arranged. Preferably, the two segments of the group A and / or D mirror-symmetrical with respect to a perpendicular extending through this and the central longitudinal axis of the mandrel in its length comprehensive plane formed. More preferably, the segments of the group A and / or D are formed mirror-symmetrically opposite. More preferably, these segments of the group A and / or D are formed with opposite, parallel and rectilinear contact walls to the adjacent segments of the groups B and C. More preferably, the mandrel according to the invention segments of the groups B and / or C, each with opposite, parallel and rectilinear contact walls each having a segment of the groups A and D.

In a further preferred embodiment, the segments of the group D in a cross-section rectilinear, preferably plane trained contact walls to the segments of the groups B and C. More preferably, each of the segments of the group D each have a projection. More preferably, this projection is immediately adjacent to the inner core in the retracted state. More preferably, the projection between the two contact walls of the segments of the group D to the segments of the groups B and C is arranged. Due to the advantage of the group D segment, the segments of Groups B and C are separated and not in direct contact. Preferably, the segments of the group D are rotationally symmetrical about 180 ° with respect to the central longitudinal axis of the mandrel formed and arranged in the mandrel. As a result, the projections of the two segments of the group D are not opposite. When carrying out a movement, the segments of group D can be guided past one another perpendicular to the central longitudinal axis of the mandrel and along the central longitudinal axis, thereby extracting the segments of group D from the cavity of the injection molding tool or from the workpiece or hollow body, preferably a bellows is also possible with the formation of undercuts of more than 50%.

In a further preferred embodiment, the wall portion of the two segments of group D adjacent to the inner core has a maximum of about 25%, more preferably not more than about 20%, even more preferably no more than about 15% of a total length formed by the length of the contact walls of the two segments of the group D to the two adjacent segments of the groups B and C, the length of the adjacent to the inner core wall portion and from the side walls of the projection, on.

Preferably, the pairs of segments of each group A to D are formed identically. Preferably, the segments of groups A to D have a larger size, with respect to each cross-section of the mandrel a larger area, than the segments of groups B and C.

The segments of the group C preferably have a wall section which is at least about 30%, more preferably at least 50% longer and which is adjacent to the inner core than the segments of the group B.

In a further preferred embodiment, the segments of group A have two wall sections which are formed at an angle to one another and which directly adjoin the inner core. More preferably, the segments of group B and / or C have a unique gene, rectilinear wall portion, which is immediately adjacent to the inner core.

In a further preferred embodiment, the segments of the groups A to D rotationally symmetrical in a rotation of 180 ° around the central longitudinal axis formed and arranged. More preferably, the two segments of the group D are displaceable differently far perpendicular to the central longitudinal axis of the mandrel, so that at least one of the segments of the group D covers the central longitudinal axis in the shifted state. Furthermore, a method for at least partial extraction of a mandrel from an injection molding tool described above having at least one cavity, in which the mandrel is arranged, is proposed

in a first step, the inner core is moved at least partially out of the mandrel along a central longitudinal axis of the mandrel,

in a second step, the group A of segments is moved in a direction of movement perpendicular to the central longitudinal axis,

in a third step, the group A is moved by segments along the central longitudinal axis,

in a fourth step, one of the groups B or C is moved by segments on at least one plane perpendicular to the central longitudinal axis, these being moved substantially successively or simultaneously in one or two directions of movement, in a fifth step one of the groups B or C of segments the middle longitudinal axis is moved,

in a sixth step, the fourth and the fifth step are repeated with the other group B or C of segments, wherein the fourth step step can already begin when the fifth step is partially, preferably about 25% of the travel preferably about 50% of the travel, more preferably about 75% of the travel, took place,

in a seventh step, the group D of segments is moved in a direction of movement perpendicular to the central longitudinal axis, and in an eighth step, the group D of segments is moved along the central longitudinal axis until the mold core is extracted from the injection mold.

An advantage of the proposed method over the prior art is that by arranging and dividing the groups A, B, C and D, even with undercuts of more than about 40%, preferably more than about 42%, more preferably more than about 45 %, and more preferably more than about 50% of the individual segments from the undercuts of the workpiece can be moved out. In one embodiment, it is provided that the group A is moved in a direction of movement perpendicular to the central longitudinal axis. It is preferably moved in a further step after the first movement along the central longitudinal axis of the mandrel. In particular, the group B or C is moved in at least two directions of movement on at least one plane whose vector is arranged parallel to the central longitudinal axis. Preferably in at least one second direction of movement substantially toward the central longitudinal axis. This group B or C is preferably moved in a further step after the first movement along the central longitudinal axis of the mandrel. The operation of the segments of the groups can be done for example hydraulically or pneumatically. In a further embodiment, it is provided that

in a second step, the group A is moved in a direction of movement perpendicular to the central longitudinal axis,

in a third step, the group A is moved along the central longitudinal axis,

in a fourth step, the group B or C is moved on at least the plane perpendicular to the central longitudinal axis, wherein these are moved essentially successively or simultaneously in at least two directions of movement,

- In a fifth step, the respective group B or C is moved along the central longitudinal axis, and - In subsequent steps, the steps two and three and / or four and five are repeated with further groups C and D until the mold core is extracted from the injection mold. In a further embodiment, it is provided that the segments of the group D are moved to a central longitudinal axis of the injection molding tool with different lengths way.

Furthermore, a method for producing a bellows is proposed with the steps:

Providing an injection molding tool described above,

Injecting at least one material into the injection molding tool, and

Removal of the molded bellows by means of a method described above.

Bellows are usually produced by injection blow molding. So far it was only possible in this process to realize undercuts of up to 40%. By contrast, the new injection molding process for producing a bellows allows undercuts of more than 40%, preferably more than 42%, more preferably more than 45%, and even more preferably more than 50%.

The injection-moldable material is preferably selected from at least one thermoplastic-elastomeric or duromer or thermosetting material formed. The thermoplastic elastomeric material is preferably selected from a group comprising polyurethanes, polyesters, in particular polyether esters or polyester esters, polyamides and / or polyolefins, in particular polypropylenes and / or polyethylenes. As thermosets, for example, phenol resins, vinyl ester resins and / or epoxy resins can be used. Furthermore, a use of an injection molding tool described above and / or a mold core described above for injection molding of a bellows is proposed.

Furthermore, a bellows made with an injection molding tool described above and / or a mold core described above is proposed.

In one embodiment, it is provided that the pleat bang has at least one undercut in the inner contour of more than 40%, preferably more than about 42%, more preferably about 45%, and even more preferably more than 50% or more. Preferably, the bellows is one having a trilobe configuration in the joint housing-side binder seat region, the trilobe regions defining an inner diameter of the bellows in relation to the demolding.

Further advantageous embodiments will become apparent from the following figures. However, the further developments shown there are not to be construed restrictively, but the features described there can be combined with each other and with the features described above for further embodiments. Furthermore, it should be noted that the reference numbers given in the description of the figures do not limit the scope of the present invention, but merely refer to the embodiment shown in the figures. Identical parts or parts with the same function have the same reference numerals below. Show it:

A schematic representation of a known from the prior art

Mold core;

FIG. 2A shows a mold core according to the invention in a plan view;

FIG. 2B shows the mold core according to FIG. 2A with the movement directions of the segment groups A to D indicated; FIG. 3 shows the mold core according to FIG. 2, with extracted inner core in different

views;

4 shows the mold core according to FIG. 2, in which a group A of segments in one

Movement direction is perpendicular to a central longitudinal axis method is in different views;

5 shows the mold core in which a group _B of segments on a plane perpendicular to the longitudinal axis is moved in different views;

6 shows the mold core, in which a group C of segments on the plane perpendicular to the central longitudinal axis is moved in different views;

7 shows the mold core, in which a group D segments is moved in the direction of movement perpendicular to the central longitudinal axis in different views;

8 shows a drive for demoulding a mold core;

9 shows a partial view of a guide section of a segment in combination with guide pins in different views;

10 shows the partial view from FIG. 9 in a first direction in different directions

views; FIG. 1 shows the partial view from FIG. 9 in a second direction in different views; FIG.

Fig. 1 2 four further embodiments of a mold core; and Fig. 1 3, the embodiment of Fig. 12C in detail. 1 shows a similarly known from EP 0 630 734 AI mold core 1 of an injection molding tool in a schematic representation. 1 A shows a mold core 1 comprising an inner core 3 and segment groups 5 and 7 mounted around it. FIG. 1B shows how the inner core 3 is extracted from the injection mold in the direction of the vector of the image plane and as a result thereof the segments 5.1, 5.2 and 5.3 of the segment group 5 in the direction of a central longitudinal axis 2 from an indicated outer circumference 9 of the undercut of a shaped workpiece, which is not shown for simplicity, is led out. 1C shows that the inner core 3 and the group of segments 5 are extracted from the injection molding tool and a group 7 with the segments 7.1, 7.2 and 7.3 is guided out of the undercut 9 in the direction of the central longitudinal axis 2. The minimum distance 1 3 of the group 7 to the circumference 9 of the undercut is about 25% of the radius of the undercut. Also by variations of the segment geometry or the number of segments is not known from the prior art, undercuts of the inner contour of more than 35% to achieve.

2A shows a mold core 10 of an injection molding tool according to the invention. The mandrel 10 comprises an inner core 1 6, the at least partially in a first section perpendicular to the central longitudinal axis 20 of the mandrel 10 circular and in a further section perpendicular to the central longitudinal axis 20 polygonal, in particular octagonal, is configured. Around the inner core 16 around segments 18.1 to 1 8.8 are arranged. Fig. 2B illustrates the directions of movement of the individual segments 18.1 to 18.8 by the arrows 1 7, 19, 23, 24, 25 and 26. The two segments 18.1 and 18.2 of group A have contact walls 50.1 to 50.2, which are parallel and rectilinear are each adjacent to a segment of groups B and C. The segments 18.3 and 18.4 of the group B likewise have parallel and rectilinearly formed contact walls 52.1 and 52.2, which each adjoin a segment of the groups A and D. Similarly, the segments 18.5 and 18.6 of the group C are formed with contact walls 54.1 and 54.2 formed parallel to each other and rectilinear. These contact walls 54.1 and 54.2 respectively adjoin a segment of the groups A and D. The in the supervision area-largest segments 18.7 and 18.8 of group D each have a contact wall

56.1, which adjoins a second segment 18.5 or 18.6 of the group C. Each of the segments 1 8.7 and 18.8 of the group D further has a contact wall 56.2, which in each case is adjacent to a segment 18.4 and 18.3 of the group B. The contact walls 56.1 and 56.2 of the segments 18.7 and 18.8 of group D are interrupted by a projection 58 which has a third wall section 60 immediately adjacent to the inner core 16. This wall section 60 is adjacent to a first wall section 64.1 and a second wall section 64.2 of the projection. The length of the third wall portion 60 in a circumferential direction 62, as illustrated by the corresponding arrow in FIG. 2A, is only about 8% of a total length formed by the length of the third wall portion 60, the length of the first and second wall portions 64.1 and

64.2 and the length of the contact walls 56.1 and 56.2 of each of the segments 18.7 and 18.8 of the group D. In the circumferential direction 62, the segments of the groups A to D alternate. The segments 18.1 to 18.8 are arranged rotationally symmetrical in a rotation about the central axis 20 of 1 80 °. Each pair of segments of each group A to D is formed identically.

The mandrel 10 thus has an inner core 16 and two first groups A and D of first segments 18.1, 8.2, 18.7 and 18.8 and two second groups B and C of second segments 18.3 to 18.6, the groups A to D each consist of two segments 18.1 and 18.2 and 18.7 and 1 8.8 and in a circumferential direction of the mandrel alternately first and second segments of the first and the second group. In Fig. 2A it can be seen that the segments are arranged in the circumferential direction in the order A, B, D, C, A, B, D, C. Preferably, the segments of the groups in the order A, B, C, D or A, C, B, D are moved. In particular, the segments of a group are moved substantially simultaneously.

3 shows the mold core of Figure 2, wherein the inner core is at least partially extracted. It can be seen in FIG. 3A that the inner core 16 is moved along the central longitudinal axis 20 at least to the extent that the segments 18. 1 and 18. 2 in the direction of the central longitudinal axis 20 can be moved. Fig. 3B shows the top view of the mold core, in which the inner core 16 has been extracted. On the division of the segments 1 8.1 to 18.8 can be seen that only the segments 18.1 and 1 8.2 can be moved directly in the direction of the central longitudinal axis 20.

4 shows in a sectional view in FIG. 4A and in a plan view in FIG. 4B the segments 18.1 and 18.2 of the mandrel and the workpiece 21. The segments 18.1 and 18.2 are moved in a direction of movement 1 7 perpendicular to a central longitudinal axis 20. Furthermore, it can be seen from FIG. 4A that the characteristics 1 1 of the segments 1 8. 1 and 18. 2 are led out of the undercuts 1 2 of the workpiece 21. It can also be seen that the outer contour a forms the inside of the workpiece 21.

The workpiece 21 is configured as a trilobal bellows for tripod joints and has a number of undercuts 1 2, which are defined as the section between the inside of a pleat tip 1 3 and the inside of a pleat 15, which the expression 1 1, the Wrinkle tip 1 3 forms, at the extraction of the segment 1 8 happens. The bellows has a first inner diameter DI at the level of the pleat tip 1 3, on which an expression 1 1 of the mandrel 10 for forming the first inner diameter DI in the extraction of the mandrel 10 is guided past. Furthermore, the bellows has a second inner diameter D2 at the height of the Faltentales 1 5. The value UC of the undercut 12 is the percentage ratio of the first inner diameter DI to the second inner diameter D2: UC = (D1 -D2) / D2 [%]. The undercut 1 2 shown in FIG. 4A has a value of UC of 51%.

As can be seen in particular from FIG. 4A, the segments have moved completely out of the undercuts 12 so that they can be extracted from the injection molding tool in the next step along the central longitudinal axis 20. FIG. 4B furthermore shows that the segments 1, 8.1 and 18.2 are moved in the direction of the central longitudinal axis 20 so far that they touch each other. FIG. 5A shows the mold core 10, wherein the segments 18.3 and 1 8.4 are moved on a plane 22 whose vector 23 is arranged parallel to the central longitudinal axis 20. 5C, it can be seen that the movement, for example, of the segment 18.3 is divided into a first movement direction 24 and a second movement direction 26, wherein the second movement direction 26 is directed perpendicular to the central longitudinal axis 20 and the first movement direction 24 is perpendicular to the second movement direction 26 is directed.

FIG. 5A shows that the movement component 24 in combination with the movement component 26 successfully completes a complete release or a complete withdrawal from undercuts 1 2 of the workpiece 21, even in the case of strong undercuts.

Furthermore, FIG. 5B shows that the segments 18.3 and 18.4 are moved along the central longitudinal axis 20 in the direction of the injection-molding train or out of the workpiece 21.

6A shows a partial view of the segment 1 8.5, which has moved out of the undercuts 12 of the workpiece 21. FIG. 6B shows the position of the segments 18.3 to 1 8.6. The segments 18.3 and 1 8.4 are already partially moved along the central longitudinal axis 20 out of the injection mold when the segments 18.5 and 18.6 are moved. As can be seen from FIG. 6C, the segments 18.3 to 18.6 form a package which is extracted together from the injection molding tool. In order to reach the position shown of the segments 18.5 and 1 8.6, they have been moved on the plane 22. 7A shows the remaining segments 1 8.7 and 18.8, which are moved in the direction of the central longitudinal axis 20, in order to extract them likewise from the workpiece 21 or the injection molding tool. The workpiece 21 is a bellows with a hinge-housing-side binder seat region which has trilobe regions 23.1 to 23.3. Such a bellows makes the application of an adapter ring superfluous. It is suitable for tripod joints. 7B it can be seen that the workpiece 21, the triloben regions 23.1 to 23.3 having. These deviate from the rotational symmetry of the workpiece 21. In order to demould the segments 1 8.7 and 18.8 from the workpiece 21 without colliding with the trilobes 23.1 to 23.3, the segments 1 8.7 and 18.8 of this group are moved differently far in the direction of the central longitudinal axis 20 of the injection molding tool. In FIG. 7B it can be seen that the segment 18.8 has traveled a greater travel path in the direction of the central longitudinal axis 20 than the segment 1 8.7 and thus the segments 1 8.7 and 18.8 occupy an asymmetrical holding position or position with respect to the central longitudinal axis 20, from which the segments 1 8.7 and 18.8 are extracted from the workpiece or the injection molding tool. 7C shows the segments 18.7 and 1.8.8 with respect to the central longitudinal axis 20 in a position before they are moved in a direction of movement perpendicular to the central longitudinal axis 20. Fig. 7D shows the segments 1 8.7 and 18.8 with respect to the central longitudinal axis 20 in a position after they have been moved in a direction perpendicular to the central axis. Fig. 8 shows schematically a drive 28 for demolding a mandrel of a

Injection molding tool 14, wherein the drive 28 comprises an actuator 36 which is designed here as a hydraulic cylinder. Furthermore, the drive 28 comprises at least one control plate 30, which comprises guide pins 32. The guide pins 32 engage in guide recesses 34 which are arranged in guide sections 38 of the segments 18. The movement of a segment 18 and the control plates 30 in the direction of movement along the central longitudinal axis 20 of the mandrel 10 is made possible by latch trains, which are not shown in the figures for the sake of simplicity.

FIG. 9 shows, in a schematic view, a guide section 38 of a segment 1 8 which is not further illustrated here. The guide section 38 has two guide recesses 34.1 and 34.2. By the guide portion 34.1 engages a guide pin 32.1 and through the guide recess 34.2 a guide pin 32.2.

Fig. 9B shows the section BB of Fig. 9A. Fig. 9C shows the section CC of Fig. 9A. 9D shows the guide section 38 in an isometric view. It can be seen that the leaders ment pins 32.2 and 32.1 each have curvatures. The curvatures of the guide pins 32.2 and 32.1 are designed in such a way that they effect in operative connection with the guide section 38 in the relative passage of the same through the recesses 34.1 and 34.2, respectively in different directions, in particular in mutually perpendicular directions of movement. Furthermore, it can be seen in particular from FIG. 9A that the guide recesses 34.1 and 34.2 are formed by two elongate recesses whose longitudinal extension is arranged at right angles to each other. In the embodiment shown, the guide recesses 34.1 and 34.2 have passage radii 40, which facilitate sliding of the guide section 38 on the guide pins 32 as they pass through the guide recesses 34.

Fig. 10B shows the section B-B of Fig. 10A. Fig. 10C shows the section C-C of Fig. 10A. 10D shows the guide section 38 in an isometric view. 10A to 10D show the movement of the guide portion 38 and thus a segment 1 8, not shown, by means of the movement of the guide pin 32.1 through the guide recess

34.1 through. The curvature of the guide pin 32.1 forces the guide portion 38 in a direction of movement of the arrow 42, being moved by the longitudinal extent of the recess 34.2 of the guide pin 32.2 in this relative to the control plate 38 and the control plate 38 is moved past this, without the guide pin

32.2 the control plate is blocked.

FIG. 11B shows the section B-B of FIG. 11A. FIG. 11C shows the section C-C of FIG. 11A. FIG. 11D shows the guide section 38 in an isometric view. 1 1 A to 1 1 D show the movement of the guide portion 38 upon movement of the guide pin 34.2 through the recess 34.2 through, being guided by the curvature of the guide portion 38 in the direction of arrow 44, wherein the guide pin 32.1 by the longitudinal design of the Guide recess 34.1 does not block the control plate.

FIGS. 12A to 2D show four further embodiments of a mandrel 10. The arrangement of the segment groups A to D of the mandrel 10 of FIG. 12A in the circumferential direction 62 is A, B, D, C, A, B, D, C. By this division and the geometric configuration of the individual segments 1 8.1 to 18.8, the segment groups A to D successively substantially perpendicular relation Wese radially to the central longitudinal axis 20 on this to be dealt with. The segment 1 8.8 of the group D is preferably moved further in the direction of the center longitudinal axis 20 than the segment 18.7 of the group D. More preferably, the segment 18.8 is moved so far radially in the direction of the central longitudinal axis 20 that it covers the central longitudinal axis 20. The segment groups A to D are preferably moved only in one direction on a plane perpendicular to the central longitudinal axis. In one embodiment, outer contours a, b, c, d, in particular an extension direction of the ribs of a bellows, adapted to the movements of the individual segments 1 8.1 to 18.8 in the extraction of the mandrel, so that in particular the segments 1 8.3 to 18.6 of Groups B and C can be extracted from the workpiece.

Fig. 12B shows a further embodiment of the mold core in a plan view. The segments 18.7 and 18.8 each have a projection 58. 1 and 58.2. The projection 58.1 is designed such that the segments 18.3 and 18.5 are moved in two directions of movement on a plane whose vector is parallel to the central longitudinal axis 20. By contrast, the projection 58.2 is configured in such a way that the segment 18.6 is moved in two directions of movement on a plane whose vector is parallel to the central longitudinal axis 20. By contrast, the adjoining segment 1 8.4 is moved essentially directly perpendicular in the direction of the central longitudinal axis 20.

FIG. 12C shows an embodiment of the mandrel 10 in which the segments 1 have 8.7 and 18.8 protrusions 58.1 and 58.2. The projections 58.1 and 58.2 are configured such that the segments 18.3 to 1 8.6 can be moved substantially directly perpendicular to the central longitudinal axis 20. The segments 18.1 to 1 8.8 of gezeig th in Fig. 1 2C embodiment are for the extraction of the workpiece or injection molding tool in exactly one direction on a plane whose vector is parallel to the central longitudinal axis 20, movable. 12D shows a further variant of the mold core 10, from which the principle of the division of the segments 18.1 to 1 8.8 into the groups A to D can be seen. The segments 1 8.1 to 18.8 of the groups A to D are groupwise substantially perpendicular to the central longitudinal axis movable.

The present invention thus provides a method and an injection molding tool with which workpieces, in particular bellows, can be produced for the first time by injection molding, the undercuts having a value greater than 40%, preferably greater than approximately 50%, more preferably greater than approximately 52%. Furthermore, with the invention, a bellows is provided which is produced efficiently and with high quality in Spritzgu ssverfahren with undercuts greater than about 40%, preferably greater about 50%.

Fig. 1 3 shows the embodiment of Fig. 1 2C in an enlarged view. It can be seen that the projections 58.1 and 58.2 of the segments 1 8.7 and 1.8.8 of the group D each have a first wall section 64.1 and a second wall section 64.2, which are angled towards one another. Due to the shape of the inner core 1 6, the third wall section 60. 1 and the fourth wall section 60. 2 are at an angle to one another, since the projections 3, 5 are adjacent to the inner core 1 6 by a third wall section 60. 1 and a fourth wall section 60 58.1 and 58.2 corners 66 of the inner core 1 6 adjacent.

It can also be seen from FIG. 13 that the segments 18.1 and 18.2 of the group A adjoin the inner core 16 in such a way that they project beyond the corners 66 of the inner core 16. The adjoining the inner core first, second and third wall sections 68.1, 68.2 and 68.3 are arranged according to the shape of the inner core 16 at an angle to each other.

Claims

claims

1 . Injection molding tool (14) having at least one cavity and a mold core (10), which can be arranged in this cavity and has at least one undercut (12), with an inner core (1 6),

four groups A, B, C and D of segments (18.1, 1 8.2, 18.3, 18.4, 18.5, 18.6, 18.7, 18.8), where the groups A, B, C and D each consist of two segments (18.1, 18.2, 18.3 , 18.4, 18.5, 18.6, 1 8.7, 1 8.8).

2. Injection molding tool according to claim 1, characterized in that in a circumferential direction (62) of the mandrel (10) alternately segments (1 8.1, 1 8.2., 1 8.7,

18.8) of groups A and D and segments (18.3, 1 8.4, 1 8.5, 18.6) of groups B and C are arranged.

3. Injection molding tool according to one or more of the preceding claims, characterized in that the groups A and D of segments (18.1, 18.2, 18.7, 18.8) in a direction of movement (1 7, 19) perpendicular to a central longitudinal axis (20) are movable.

4. Injection molding tool according to one or more of the preceding claims, characterized in that the group A of segments (18.1, 18.2) has an outer contour a and the group D of segments (18.7, 1 8.8) has an outer contour d, wherein the outer contours a and d are different.

5. Injection molding tool according to claim 4, characterized in that a surface of the outer contour a is smaller than a surface of the outer contour d.

6. Injection molding tool according to one or more of the preceding claims, characterized in that the groups B and C of segments (18.3, 18.4, 18.5, 18.6) in one or two directions of movement (24, 25, 26, 27) perpendicular to a central longitudinal axis ( 20) of the mold core (10) are movable.

7. Injection molding tool according to one or more of the preceding claims, characterized in that the groups B and C of segments (18.3,18.4, 18.5, 18.6) have an identical or different outer contour b and c.

8. Injection molding tool according to claim 7, characterized in that a surface of the outer contours b and c are equal to or smaller than the surface of the outer contour a.

9. injection molding tool according to one or more of the preceding claims, characterized in that the two segments (18.1, 18.2, 18.3, 18.4, 18.5, 18.6, 1 8.7, 1 8.8) of the groups A and D and the groups B and C identical are formed.

0. Injection molding tool according to one or more of the preceding claims, characterized in that the two segments (1 8.1, 18.7) of the group D are formed asymmetrically opposite in the mold core (10).

1 . Injection molding tool according to one or more of the preceding claims, characterized in that between a first and a second contact wall (56.1, 56.2) of the segments (18.7, 1 8.8) of the group D, a projection (58) is formed, which on the inner core (16 ) borders.

2. Injection molding tool according to claim 1 1, characterized in that the projections (58) offset from one another are arranged on the two segments (1 8.7, 18.8) of the group D in a closed mold core (10). Injection molding tool according to one or more of the preceding claims, characterized in that the segments (18.7, 18.8) of the group D each have a first and a second contact wall (56.1, 56.2) for each segment (18.3, 18.4, 18.5, 18.6) of the groups B and C, which are formed in cross-section linear or collinear with each other.

Injection molding tool according to one or more of the preceding claims, characterized in that the two segments (18.7, 18.8) of the group D are moved to different degrees perpendicular to a central longitudinal axis (20) of the mold core (10), so that at least one of the two segments (18.7 , 18.8) of the group D, the central longitudinal axis (20) at least partially covered.

Mold core (10) for an injection molding tool (14) according to one or more of claims 1 to 14.

Method for at least partially extracting a mold core (10) from an injection molding tool (14) according to one or more of claims 1 to 14 with at least one cavity in which the mold core (10) is arranged, wherein in a first step the inner core (16) along a central longitudinal axis (20) of the mandrel (10) at least partially from the mandrel (10) is moved, in a second step, the group A of segments (18.1, 18.2) in a direction of movement (1 7) perpendicular to the central longitudinal axis (20) is moved, in a third step, the group A of segments (18.1, 18.2) along the central longitudinal axis (20),

in a fourth step, one of the groups B or C of segments (18.3, 18.4, 18.5, 18.6) is moved on at least one plane (22) perpendicular to the central longitudinal axis (20), these being substantially successively or simultaneously in one or two directions of movement ( 24, 25, 26, 27) are moved, in a fifth step one of the groups B or C of segments (18.3, 18.4, 18.5, 1 8.6) is moved along the central longitudinal axis (20), in a sixth step, the fourth and the fifth step are repeated with the other group B or C of segments (18.3, 18.4, 18.5, 18.6), wherein the procedure in the fourth step can already begin when the procedure of the fifth step is partially, preferably to 50% of the travel, was carried out, - in a seventh step, the group D of segments (1 8.7, 1 8.8) in a direction of movement (19) is moved perpendicular to the central longitudinal axis (20), and in an eighth step, the group D of Is moved segments (1 8.7, 18.8) along the central longitudinal axis (20) until the mold core (10) is extracted from the injection molding tool (14).

1 7. The method according to claim 16, characterized in that the segments (18.7, 18.8) of the group D are moved to a central longitudinal axis (20) of the injection molding tool (14) out with different lengths way. 18. A method for producing a bellows (21) comprising the steps of:

Providing an injection molding tool (14) according to one or more of claims 1 to 14,

Injecting at least one material into the injection molding tool (14), and removing the molded bellows (21) by means of a method according to one or more of claims 16 or 17.

Use of an injection molding tool (14) according to one or more of claims 1 to 14 and / or a mold core (10) according to claim 1 5 for injection molding of a bellows (21).

A bellows (21) made with an injection molding tool (14) according to one or more of claims 1 to 14 and / or a mold core (10) according to claim 21. Bellows (21) according to claim 20, characterized in that it has at least one undercut (1 2) in the inner contour of more than 40%.