MULTI-PART CORE INSERT

Abstract

The present invention concerns a multi-part core insert (1) for an injection molding mold (100) for the production of preforms having a two-part core having a longitudinal axis (10), wherein the two-part core has a lower core part (20) and an upper core part (30) arranged beside the lower core part (20) in the direction of the longitudinal axis, and a fixing element (40), wherein the fixing element (40) has an opening parallel to the longitudinal axis (10) for receiving the upper core part (30), and wherein the upper core part (30) can be fixed with the fixing element (40) at an end (22) of the lower core part (20). To provide a core insert for an injection molding mold, whose shaping portion can be easily and quickly exchanged, while at the same time ensuring the quality and functionality of the injection molding procedure, it is proposed according to the invention that the fixing element (40) and the upper core part (30) are of such a configuration that when the upper core part (30) is received in the opening a positively locking and/or force-locking connection can be produced at least in the axial direction between the upper core part (30) received in the fixing element (40) and the fixing element (40), and the fixing element (40) and the lower core part (30) are of such a configuration that the fixing element (40) can be fixed to the lower core part only in one position or in a plurality of positions which differ by rotation of the fixing element (40) relative to the lower core part (20) about the longitudinal axis (10), wherein only a finite number of positions, preferably a maximum of four positions, of the fixing element (40) relative to the lower core part (20) are possible.

Claims

1. A multi-part core insert (1) for an injection molding mold (100) for the production of preforms having a two-part core having a longitudinal axis (10), wherein the two-part core has a lower core part (20) and an upper core part (30) arranged beside the lower core part (20) in the direction of the longitudinal axis, and a fixing element (40), wherein the fixing element (40) has an opening parallel to the longitudinal axis (10) for receiving the upper core part (30), and wherein the upper core part (30) can be fixed with the fixing element (40) at an end (22) of the lower core part (20). characterised in that the fixing element (40) and the upper core part (30) are of such a configuration that when the upper core part (30) is received in the opening a positively locking and/or force-locking connection can be produced at least in the axial direction between the upper core part (30) received in the fixing element (40) and the fixing element (40), and the fixing element (40) and the lower core part (30) are of such a configuration that the fixing element (40) can be fixed to the lower core part only in one position or in a plurality of positions which differ by rotation of the fixing element (40) relative to the lower core part (20) about the longitudinal axis (10), wherein only a finite number of positions of the fixing element (40) relative to the lower core part (20) are possible.

2. A multi-part core insert (1) as set forth in claim 1 wherein the upper core part (30) and the opening of the fixing element (40) have mutually corresponding abutment surfaces (31, 42).

3. A multi-part core insert (1) as set forth in claim 2 wherein the corresponding abutment surfaces (31, 42) are conical.

4. A multi-part core insert (1) as set forth in claim 2 wherein the corresponding abutment surfaces (31, 42) have two mutually perpendicular abutment surface portions.

5. A multi-part core insert (1) as set forth in claim 1 wherein the fixing element (40) is of such a configuration that the abutment surface (42) of the fixing element (40) and the abutment surface (31) of the upper core part (30) are matched to each other with a clearance fit so that even in an assembled state of the multi-part core insert (1) the upper core part (30) is mounted floatingly in the fixing element (40) so that the abutment surfaces (31, 42) at least in the radial direction are not in contact with each other or not in contact over the full periphery.

6. A multi-part core insert (1) as set forth in claim 1 wherein the lower core part (20) and the fixing element (40) have mutually corresponding contact surfaces (27, 28, 47, 48) which are in contact with each other in an assembled state of the multi-part core insert (1).

7. A multi-part core insert (1) as set forth in claim 6 wherein the mutually corresponding contact surfaces of the lower core part (20) and the fixing element (40) have two mutually perpendicular contact surface portions (27, 28, 47, 48).

8. A multi-part core insert (1) as set forth in claim 7 wherein at least one projection are provided in the radial direction at one of the contact surface portions (28, 48) which are parallel to the longitudinal axis, and wherein provided at the corresponding contact surface (28, 48) which is parallel to the longitudinal axis (10) is a substantially L-shaped recess (29) into which the projection of the corresponding contact surface (28, 48) engages in an assembled state of the multi-part core insert (1) so that there is a positively locking and/or force-locking connection between the fixing element (40) and the lower core part (20).

9. A multi-part core insert (1) as set forth in one of the preceding claims wherein at an end towards the fixing element (40) the lower core part (20) has an end portion (21) projecting from the end face (26) in the axial direction and wherein at an end towards the lower core part (20) the fixing element (40) has a depression corresponding to the end portion (21) of the lower core part (20) so that the depression in the fixing element (40) and the projecting end portion (21) of the lower core part (20) are in contact with each other or wherein the lower core part (20) has a depression at an end (26) towards the fixing element (40) and wherein at an end towards the lower core part (20) the fixing element (40) has a projecting end portion corresponding to the depression in the lower core part (20) so that the projecting end portion of the fixing element (40) and the depression in the lower core part (20) are in contact with each other.

10. A multi-part core insert (1) as set forth in claim 9 wherein the fixing element (40) in an assembled state of the multi-part core insert (1) is so arranged on the lower core part (20) that an outside surface of the fixing element (40) terminates flush with an outside surface of the lower core part (20).

11. A multi-part core insert (1) as set forth in claim 6 wherein the fixing element (40) is of such a configuration that the fixing element (40) has at least one through hole (49) in the region of the contact surfaces (27, 28, 47, 48) of the lower core part (20) and the fixing element (40) for at least one fixing means and wherein the lower core part (20) has at least one bore (25), preferably a threaded bore, wherein the at least one fixing mean is introduced through the through hole (49) in the fixing element (40) into the bore (25) of the lower core part (20) to make a positively locking and/or force-locking connection.

12. A multi-part core insert (1) as set forth in claim 1 wherein the fixing element (40) and the lower core part (20) respectively have at least one blow-out passage (23, 24, 43, 44) for blow-out air and wherein the fixing element (40) in an assembled state of the multi-part core insert (1) is so fixed to the lower core part (20) that the blow-out passages (23, 24, 43, 44) adjoin each other directly in the axial direction.

13. A multi-part core insert (1) as set forth in claim 1 wherein at an end (45) facing away from the lower core part (20) the fixing element (40) has a depression (45).

14. An injection molding mold (100) for the production of preforms comprising a multi-part core insert (1) as set forth in claim 1 and a cavity insert (70), wherein in an assembled state the injection molding mold (100) has a mold cavity (80) whose contour corresponds to the contour of the preform to be produced, wherein the core insert (1) and the cavity insert (70) respectively have shaping portions (32, 71) which in the assembled state of the injection molding mold (100) form at least a part of the contour of the mold cavity (80).

15. An injection molding mold as set forth in claim 14 having a collar (60), wherein the collar (60) has a shaping portion (61) for forming a thread on a preform, wherein there is provided a core insert (1) as set forth in claim 13 and the collar (60) at an end towards the fixing element (40) has contact surfaces (63) corresponding to the frustoconical depressions (45) in the fixing element (40) so that in the assembled state of the injection molding mold (100) the contact surfaces (63) of the collar (60) and the frustoconical depression (45) of the fixing element (40) are in engagement with each other in positively locking relationship.

16. A multi-part core insert (1) as set forth in claim 2, wherein the abutment surfaces are preferably of such a configuration that an axial relative movement of the fixing element (40) with respect to the upper core part (30) in the direction of the part of the upper core part (30), that is towards the lower core part (20) and/or a radial relative movement between the fixing element (40) and the upper core part (30) is limited.

17. A multi-part core insert (1) as set forth in claim 4 wherein a respective one of the abutment surface portions of the upper core part (30) and the opening of the fixing element (40) is parallel to the longitudinal axis (10) of the fixing element (40).

18. A multi-part core insert (1) as set forth in claim 7 wherein a respective one of the contact surface portions (28, 48) of the lower core part (20) and the fixing element (40) is oriented parallel to the longitudinal axis (10).

19. A multi-part core insert (1) as set forth in claim 8 wherein at least two projections are provided in the radial direction at one of the contact surface portions (28, 48) which are parallel to the longitudinal axis.

20. A multi-part core insert (1) as set forth in claim 8 wherein the L-shaped recess (29) and the projection or projections are of such a configuration that the lower core part and the fixing element can be connected together by interengagement along the longitudinal axis and opposite rotation about the longitudinal axis through an angle of rotation which is best between 20° and 50°.

Description

[0060] Further advantages, features and possible uses will be apparent from the following description of preferred embodiments and the accompanying Figures. The same components in the Figures are denoted by the same references. In the Figures:

[0061] FIG. 1 shows a sectional view of an injection molding mold with an embodiment of the core insert,

[0062] FIG. 2 shows a sectional view of an embodiment of the core insert with preform but without cavity insert and collar, and

[0063] FIG. 3 shows a sectional view of another embodiment of the core insert.

[0064] FIG. 1 shows an injection molding mold 100 having a multi-part core insert 1 which is rotationally symmetrical about a longitudinal axis 10, a collar 60 and a cavity insert 70. The multi-part core insert 1 has a lower core part 20, an upper core part 30 and a fixing element 40, all components being of a substantially cylindrical structure. The fixing element 40 has an opening in the axial direction. The diameter of the opening however varies in the axial direction to ensure a positively locking connection both to the upper core part 30 and also the lower core part 20.

[0065] The lower core part 20 has an end portion 21 which projects in the axial direction from the end face 26, wherein provided in the end portion 21 are two threaded bores 25 which serve for fixing the fixing element 40 to the lower core part 20. The threaded bores 25 are arranged at an acute angle relative to the longitudinal axis 10.

[0066] The upper core part 30 is fixed to the lower core part 20 by means of the fixing element 40. For that purpose at an end towards the lower core part 20 the opening of the fixing element 40 is of such a diameter that the projecting end portion 21 of the lower core part 20 can be received in positively locking relationship. In that way the fixing element 40 and the lower core insert 20 have two mutually perpendicular contact surface portions 27, 28, 47, 48, with the contact surface portions 28, 48 being arranged parallel to the longitudinal axis 10 of the fixing element 40.

[0067] Disposed in the region of the parallel contact surfaces 28, 48 in the fixing element 40 are through bores 49 into which a fixing means, for example a screw (not shown) can be introduced, which engages into the threaded bores 25 in the lower core part 20. In that way a force is produced in particular in the radial direction between the fixing element 40 and the lower core part 20.

[0068] The outside diameters of the lower core part 20 and the fixing element 40 are so selected that their outside surfaces terminate flush.

[0069] To receive the upper core part 10 in the fixing element 40 the opening of the fixing element 40 is further of such a configuration that the upper core part 30 can be received in the opening. The upper core part 30 and the opening of the fixing element 40 have mutually corresponding abutment surfaces 31, 42 of a conical configuration. Adjoining the conical abutment surfaces in the direction of the lower core part 20 are two contact surface portions which are perpendicular to each other, one of the contact surface portions in turn extending parallel to the longitudinal axis 10.

[0070] A fixed connection is achieved between the fixing element 40 and the upper core part 30 by the combination of mutually perpendicular contact surface portions and conical contact surfaces 31, 42. The same applies to the connection between the fixing element 40 and the lower core part 20 so that overall tilting of the upper core part 30 relative to the lower core part 20 is prevented.

[0071] In order to be able to release a preform which is formed in a mold cavity 80 from the injection molding mold 100 as quickly as possible the multi-part core insert 1 has a cooling system. For that purpose a through bore in which a cooling liquid is guided is disposed in the lower core part 20. The upper core part 30 has a blind bore for guiding cooling liquid, the diameter thereof corresponding to the diameter of the through bore in the lower core part 20.

[0072] By virtue of the fixing of the fixing element 40 to the lower core part 20 the upper core part 30 is arranged on the lower core part 20 in such a way that there are only two possible positions for the arrangement of the fixing element 40, wherein the bores of the upper and lower core parts 20, 30 for carrying the cooling fluid in any event adjoin each other in flush relationship.

[0073] To produce a preform the injection molding mold 100 has a mold cavity 80, the contour of which corresponds to the contour of the preform to be produced. The upper core insert 30 and the cavity insert 70 have respective shaping portions 32, 71 which form a part of the contour of the mold cavity 80. The other part of the mold cavity 80 is formed by a shaping portion 61 of the collar 60, the shaping portion 61 of the collar 60 being of such a configuration that a thread is formed on a preform.

[0074] At an end towards the fixing element 40 the collar has contact surfaces 63 which correspond to a frustoconical depression 45 of the fixing element 40 at an end 46 thereof, that is towards the lower core part 20, so that the contact surfaces 63 of the collar 60 and the surface of the frustoconical depression 45 of the fixing element 40 are in mutual engagement in positively locking relationship. In addition the collar 60 has contact surfaces 62 which are parallel to the longitudinal axis 10 and which are in contact with the upper core part 30. In that way the upper core insert 30 is additionally stabilized even more.

[0075] The cavity insert 70 has a gate 72, by way of which the plasticized melt is injected into the mold cavity 80 during the injection molding operation, thereby forming a preform.

[0076] When the injected plasticized melt is cooled the cavity insert 70 and the collar 60 are removed by the components being moved away in the axial direction from the multi-part core insert 1. The preform initially remains on the core insert as shown in FIG. 2. To remove the finished preform from the upper core part 30 blow-out air is blown through blow-out passages 23, 24, 43, 44, which exerts a force on the preform parallel to the longitudinal axis 10 so that the preform is detached from the upper core part 30.

[0077] The blow-out passage 23 and the blow-out passage 24 of the lower core part 20 are arranged at opposite sides of the lower core part 20. The two blow-out passages 43, 44 of the fixing element 40 are directly in communication with the blow-out passages 23, 24 of the lower core part 20 and are arranged between the through bores 49. The blow-out passages 43 and 44 of the fixing element 40 open into the depression 45 of the fixing element 40, which is at an end 46 of the fixing element 40, that is facing away from the lower core part 20. The depression 45 is of a frustoconical configuration. By virtue of the defined positioning of the fixing element 40 relative to the lower core part 20 the openings of the blow-out passages 23, 24, 43, 44 are disposed in mutually superposed relationship directly in the direction of the longitudinal axis 10. The defined positioning is achieved by an arresting pin 50.

[0078] The material of the upper core part 30, the cavity insert 70 and the collar 60 is so selected that it has particularly high thermal conductivity in order of cool down the preform as quickly as possible. In addition the portions of those components, that form the mold cavity 80, are coated with a coating to facilitate release of the preform from the injection molding mold 100. The fixing element 40 and the lower core part 20 in contrast are made from a particularly robust steel which particularly well withstands the forces acting thereon.

[0079] FIG. 3 shows an embodiment of a multi-part core insert 1 in which a different fixing mechanism for the fixing element 40 on the lower core part 20 was adopted. The upper core part 30 can be received in the fixing element 40 as described hereinbefore.

[0080] To fix the fixing element 40 to the lower core part 20 an L-shaped recess 29 is arranged in the end portion 21. For making the force-locking connection between the fixing element 40 and the lower core part 20 the fixing element 40 at the inside surface delimiting the depression in the radial direction further has a projection which engages into the L-shaped recess 29 when the fixing element 40 is pushed in the axial direction on to the lower core part 20. By virtue of a subsequent rotary movement about the longitudinal axis 10 the projection moves into the portion of the L-shaped recess 29, that is oriented perpendicularlly to the longitudinal axis 10, and provides that the fixing element 40 and the lower core part 20 are clamped relative to each other.

[0081] This connection based on the principle of a bayonet fixing allows particularly rapid and simple replacement of the upper core part 30 when it is worn or if another mold cavity 80 is to be formed.

[0082] For the purposes of the original disclosure it is pointed out that all features as can be seen by a man skilled in the art from the present description, the drawings and the claims, even if they are described in specific terms only in connection with certain other features, can be combined both individually and also in any combinations with others of the features or groups of features disclosed here insofar as that has not been expressly excluded or technical aspects make such combinations impossible or meaningless. A comprehensive explicit representation of all conceivable combinations of features is dispensed with here only for the sake of brevity and readability of the description.

[0083] While the invention has been illustrated and described in detail in the drawings and the preceding description that illustration and description is only by way of example and is not deemed to be a limitation on the scope of protection as defined by the claims. The invention is not limited to the disclosed embodiments.

[0084] Modifications in the disclosed embodiments are apparent to the man skilled in the art from the drawings, the description and the accompanying claims. The drawings are true to scale. In the claims the word ‘have’ does not exclude other elements or steps and the indefinite article ‘a’ does not exclude a plurality. The mere fact that certain features are claimed in different claims does not exclude the combination thereof. References in the claims are not deemed to be a limitation on the scope of protection.

LIST OF REFERENCCES

[0085] 1 multi-part core insert
10 longitudinal axis
20 lower core part
21 projecting end portion
22 end of the lower core part
23, 24 blow-out passage of the lower core part
25 threaded bore
26 end face of the lower core part
27, 28 contact surfaces of the lower core part
29 L-shaped recess
30 upper core part
31, 42 abutment surfaces of the upper core part and the fixing element
32 shaping portion of the upper core part
40 fixing element
43, 44 blow-out passage of the fixing element
45 depression
46 end of the fixing element
47, 48 contact surfaces of the fixing element
49 through bore
50 arresting pin
60 collar
61 shaping portion of the collar
62 contact surface of the collar that is parallel to the longitudinal axis
63 conical contact surface of the collar
70 cavity insert
71 shaping portion of the cavity insert
72 gate
80 mold cavity
100 injection molding mold