INJECTION MOLD WITH A SIDE GATE NOZZLE

Abstract

The disclosure is directed to an injection mold (1) comprising a mold insertframe (2) having several openings (3) extending in an axial direction (z). Each opening (3) accommodates a mold insert (4) encompassing a cavity (5), suitable to receive during operation melted plastic to form a plastic part. The several openings (3) with the mold inserts (4) are distributed around a center opening (6) of the mold insert frame (2). A nozzle head (7) is arranged in the center opening (6) of the mold insert frame (2). It comprises a primary melt channel (8), extending in the axial direction (z), and per cavity (5) a secondary melt channel (9) each interconnected at a dorsal end to the primary melt channel (8) and at a distal end to a cavity (5) by a nozzle tip (10) attached to the nozzle head (7). Each mold insert (4) comprises a first cooling channel (11) surrounding the cavity (5) and being in fluid communication with a first cooling circuit (12) across the mold insert frame (2).

Claims

1. An injection mold (1) comprising a. a mold insert frame (2) having several openings (3) extending in an axial direction (z) accommodating in each opening (3) a mold insert (4) encompassing a cavity (5), suitable to receive during operation melted plastic to form a plastic part; wherein b. the several openings (3) with the mold inserts (4) are distributed around a center opening (6) of the mold insert frame (2); c. a nozzle head (7) arranged in the center opening (6) of the mold insert frame (2) comprising a primary melt channel (8), extending in the axial direction (z), and per cavity (5) a secondary melt channel (9) each interconnected at a dorsal end to the primary melt channel (8) and at a distal end to a cavity (5) by a nozzle tip (10) attached to the nozzle head (7) wherein d. each mold insert (4) comprises a first cooling channel (11) surrounding the cavity (5) and being in fluid communication with a first cooling circuit (12) across the mold insert frame (2).

2. The injection mold (1) according to claim 1, wherein a second cooling channel (13) is present, wherein the first cooling channel (11) encompasses the cavity (5) distal from the nozzle tip (10) and the second cooling channel (13) encompasses the cavity (5) adjacent to the nozzle tip (10) and wherein the second cooling channel (13) is: a. in fluid communication with a second cooling circuit (14) across the mold insert frame (2); and/or b. the first and the second cooling channel (11, 13) are interconnected to the first cooling circuit (12).

3. The injection mold (1) according to claim 2, wherein the first cooling channel (11) is helix shaped and the second cooling channel (13) has, when seen in the axial direction (z) a C-shaped cross-section.

4. The injection mold (1) according to claim 1, wherein at least one cooling channel (11, 13) is arranged between an inner wall (15) of the opening (3) and a thereto corresponding outer wall (16) of the mold insert (4).

5. The injection mold (1) according to claim 1, wherein the mold insert frame (2) comprises a cylindrical outer side wall (17) in which a first supply channel (18) extends in circumferential direction.

6. The injection mold (1) according to claim 1, wherein the mold insert frame (2) comprises a bottom face (20) in which at least one electrical connector (21) is arranged.

7. The injection mold (1) according to claim 6, wherein the at least one electrical connector (21) is arranged displaceable perpendicular to the bottom face (20).

8. The injection mold (1) according to claim 7, wherein the position of the electrical connector (21) with respect to the bottom face (20) can be adjusted by a set screw (22) from the outside.

9. The injection mold (1) according to claim 7, wherein the at least one electrical connector (21) is arranged in a recess (23) of the mold insert frame (2) adjacent to the bottom face (20).

10. The injection mold (1) according to claim 1, wherein the mold insert frame (2) comprises a cable channel (44) extending between the center opening (6) and the outside of the mold insert frame (2) for routing of cables therein.

11. The injection mold (1) according to claim 1, wherein the nozzle head (7) is in at least one direction thermally separated with respect to a top face (24) by a spacer (25).

12. The injection mold (1) according to claim 11, wherein the spacer (25) is arranged concentric with respect to the primary melt channel (8).

13. The injection mold (1) according to claim 1, wherein the secondary melt channels (9) extend from the primary melt channel (8) star-like in a radial direction.

14. The injection mold (1) according to claim 13, wherein two neighboring secondary melt channels (9) are thermally separated from each other by a gap (26) extending in axial direction (z).

15. The injection mold (1) according to claim 14, wherein several gaps (26) are arranged star-like in a radial direction.

16. The injection mold (1) according to claim 1, wherein the primary melt channel (8) is at least partially thermally separated from the secondary melt channels (9) by a circumferential gap (33) arranged circumferential to the primary melt channel (8).

17. The injection mold (1) according to claim 15, wherein the several gaps (26) in radial direction extend into the circumferential gap (33).

18. The injection mold (1) according to claim 1, wherein at least one heating element (32) is arranged adjacent to a secondary melt channel (9).

19. The injection mold (1) according to claim 18, wherein the at least one heating element (32) is arranged in a bore (34) in the nozzle head (7).

20. The injection mold (1) according to claim 1, wherein at least one sensor element (35) is arranged adjacent to a secondary melt channel (9).

21. The injection mold (1) according to claim 20, wherein the at least one sensor element (35) is arranged in a bore (36) in the nozzle head (7).

22. The injection mold (1) according to claim 19, wherein the heating element (32) and the sensor element (35) are arranged in the same bore (34, 36).

23. The injection mold (1) according to claim 19, wherein adjacent to each secondary melt channel (9) a thereto associated heating element (32) and an associated sensor element (35) are arranged, which in circumferential direction are separated from each other by at least one gap (26).

24. The injection mold (1) according to claim 1, wherein the cavity (5) is at least partially formed in a closed position of the injection mold (1) with a thereto in the axial direction (z) displaceable core (38).

25. The injection mold (1) according claim 24, wherein a centering bushing (39) comprising a centering recess (40) is arranged opposite of the core (38) in the axial direction (z) and adjacent to the mold insert (4), such that a core tip (41) of the core (38) is in the closed position at least partially accommodated in the centering recess (40).

26. The injection mold (1) according to claim 25, wherein the centering bushing (39) is held by a bushing support (42) in a floating manner and is aligned by an alignment surface (43) of the mold insert (4) and/or the bushing support (42) is in contact with the centering bushing (39), such that the centering recess (40) is coaxial with the core (38) in the closed position.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0020] The herein described invention will be more fully understood from the detailed description given herein below and the accompanying drawings which should not be considered limiting to the invention described in the appended claims. The drawings are showing:

[0021] FIG. 1 shows a first variation of an injection mold in a perspective manner in a partially sectioned view;

[0022] FIG. 2 shows the variation according to FIG. 1 in a perspective manner in an exploded view;

[0023] FIG. 3 shows a nozzle head according to FIG. 1 in perspective view.

[0024] FIG. 4 shows a second variation of the injection mold in a perspective manner in an exploded view;

[0025] FIG. 5 shows the variation according to FIG. 4 in a sectioned view; and

[0026] FIG. 6 shows a third variation of the injection mold in a perspective manner in an exploded view.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Reference will now be made in detail to certain embodiments, examples of which are illustrated in the accompanying drawings, in which some, but not all features are shown. Indeed, embodiments disclosed herein may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Whenever possible, like reference numbers will be used to refer to like components or parts.

[0028] FIG. 1 shows relevant aspects of a first variation of an injection mold 1 in a perspective manner in a partially sectioned view. FIG. 2 shows the variation according to FIG. 1 in a perspective manner in an exploded view and FIG. 3 shows a nozzle head according to FIG. 1 with hidden edges displayed as dash lines. Not shown is the complete mold comprising the hereinafter described elements. A mold usually comprises in addition a first mold half (nozzle side) in which the elements shown hereinafter are during production incorporated. Furthermore, the injection mold 1 usually comprises a second mold half (ejector side), as shown in FIGS. 4 to 6, which interacts in a closed position with the first mold half forming at least one cavity 5 as described hereinafter in more detail. FIG. 4 shows a second variation of the injection mold 1 in a perspective manner in an exploded view of the first mold half in an open position. Whereas FIG. 5 shows the variation according to FIG. 4 in a sectioned view and in a closed position. FIG. 6 shows a third variation of the injection mold 1 in a perspective manner in an exploded view of the first mold half in an open position

[0029] The injection mold 1 partially shown in FIGS. 1, 2, 4, 5 and 6 comprises a mold insert frame 2 having several openings 3 extending in an axial direction (z-direction). Each of the openings 3 accommodates a mold insert 4 encompassing a (first) cavity half 5. The (first) cavity half 5 forms in combination with a corresponding (second) cavity half in a closed position of the injection mold 1 a cavity suitable to receive during operation melted plastic to form a plastic part, as best visible in FIG. 5. The openings 3 with the mold inserts 4 are distributed around a center opening 6 of the mold insert frame 2.

[0030] A nozzle head 7 as best visible in FIG. 3 is arranged in the center opening 6 of the mold insert frame 2. The nozzle head 7 comprises a primary melt channel 8, extending in the axial direction z, or more specifically around a central axis 28. Per cavity 5 a secondary melt channel 9 interconnects at a dorsal end to the primary melt channel 8 and at a distal end to a cavity 5 by a nozzle tip 10, which is attached to the nozzle head 7.

[0031] A nozzle body 37 is during production accommodated in the center opening 6 and said nozzle body 37 is interconnected to the primary melt channel 8 of the nozzle head 7, as shown in FIG. 1.

[0032] As illustrated in FIG. 2 each mold insert 4 comprises a helix shaped first cooling channel 11, which surrounds and encompasses the cavity 5 distal from the nozzle tip 10. The first cooling channel 11 is in fluid communication with a first cooling circuit 12 across the mold insert frame 2 and its inlet and outlet openings are on essentially the same level in the axial direction. When seen in the axial direction z a C-shaped second cooling channel 13 encompasses the cavity 5 adjacent to the nozzle tip 10 and is in fluid communication with a second cooling circuit 14 across the mold insert frame 2. In the displayed variations of FIGS. 1, 2, 4, 5 and 6 the second cooling channel 13 comprises two C-shaped circulations, however different number of circulations are thinkable. In the shown variation, at least one cooling channel 11, 13 is arranged between an inner wall 15 of the opening 3 and a thereto corresponding outer wall 16 of the mold insert 4. In the case at hand the first cooling channel 11 is arranged between an inner wall 15 of the opening 3 and a thereto corresponding outer wall 16 of the mold insert 4.

[0033] In the first variation, as visible in FIGS. 1 and 2 a first and a second supply channel 18, 19 are arranged in a cylindrical outer side wall 17 of the mold insert frame 2, each extending in circumferential direction. In the second and third variation, shown in FIGS. 4, 5 and 6, the first and the second supply channel 18, 19 are passing through the outer side wall 17 of the cuboid-shaped mold insert frame 2, each extending in a direction perpendicular to the axial direction, as indicated in FIG. 6.

[0034] The exploded views of FIGS. 2 and 4 give insight into the layered construction of the mold insert frame 2 comprising a bottom face 20 in which at least one electrical connector 21 is arranged and a top face 24. In the third variation of the injection mold 1, as shown in FIG. 6 the mold insert frame 2 comprises a cable channel 44 connecting the center opening 6 and rectangular the outer side wall 17 of the mold insert frame 2 for an electrical connection made from a lateral side of the mold insert frame 2. This allows a more compact construction of the injection mold 1 in the axial direction z compared to the first and second variation. In the shown third variation the electrical cables supplying the heating elements 32 run through the cable channel 44 and in addition the cable for the sensor elements 35 is also routed through said cable channel 44.

[0035] Between the top face 24 and the bottom face 20 in the axial direction z the mold insert frame 2 and the nozzle head 7 are arranged in the assembled state as shown in FIGS. 1, 5 and 6.

[0036] The at least one electrical connector 21 is arranged displaceable perpendicular to the bottom face 20 and the position of the electrical connector 21 with respect to the bottom face 20 can be adjusted by a set screw 22 from the outside as best visible in FIG. 1. A recess 23 of the mold insert frame 2 adjacent to the bottom face 20 accommodates the electrical connector 21.

[0037] The nozzle head 7 is in at least the axial direction thermally separated with respect to a top face 24 by a spacer 25 and the spacer 25 is arranged concentric with respect to the primary melt channel 8. To achieve a thermal decoupling of the top face 24 from the nozzle head 7 the connecting spacer 25 consists of a material with low thermal conductivity, in this case a ceramic.

[0038] FIG. 3 allows insight into the inner structure of the nozzle head 7 as hidden edges are displayed. It can be seen that the secondary melt channels 9 extend star-like from the primary melt channel 8 in a radial direction. Further, two neighboring secondary melt channels 9 are in circumferential direction thermally separated from each other by a gap 26 extending in axial direction z across the nozzle head 7 thereby forming segments 29. In the variation shown several slit-like gaps 26 are arranged star-like around the primary melt channel 8 and form a rotationally symmetric pattern. In addition, the primary melt channel 8 is partially thermally separated from the secondary melt channels 9 by a circumferential gap 33 arranged circumferential to the primary melt channel 8. In the embodiment displayed in FIG. 3 the gaps 26 extend in radial direction into the circumferential gap 33 forming segments 29 of the nozzle head 7.

[0039] As shown in FIGS. 1 and 2, and best visible in FIG. 6, heating elements 32 are arranged adjacent to each secondary melt channel 9 each in a respective bore 34 in the nozzle head 7. In addition, one sensor element 35 is arranged adjacent to each secondary melt channel 9 a respective bore 36 in the nozzle head 7. More particularly the heating elements 32 and the sensor elements 35 are arranged together in the same bore 34, 36. In other words, adjacent to each secondary melt channel 9 a thereto associated heating element 32 and an associated sensor element 35 are arranged, which in circumferential direction are separated from each other by at least one gap 26.

[0040] The injection mold 1, as illustrated in FIGS. 4, 5 and 6, comprises a core 38 per mold insert 4 forming part of a second mold half of the injection mold 1. The cavity 5 is essentially formed in a closed position of the injection mold 1 between the in the axial direction z displaceable core 38 and the associated mold insert 4. Here the second mold half comprises the same number of cores 38 as the first mold half comprises mold inserts 4.

[0041] In case of the production of tubular plastic parts (like pipettes, not shown) the contact region of the core 38 and first mold half is subjected to wear, as a contact of the core 38 and the first mold half in the contact region is made each cycle in the closed position of the injection mold 1.

[0042] In order to minimize wear and/or to make the part subject to wear easily replaceable, a centering bushing 39 comprising a centering recess 40 is arranged opposite of the core 38 and adjacent to the mold insert 4 in the axial direction z. This can be observed in the second and third variation of the injection mold 1 as shown in FIGS. 4 to 6. The centering bushing 39 is arranged, such that a core tip 41 of the core 38 is in the closed position at least partially accommodated in the centering recess 40. To allow a precise positioning of the centering bushing 39, it is held by a bushing support 42 in a floating manner and is in the second variation aligned by an alignment surface 43 of the mold insert 4 in contact with the centering bushing 39, such that the centering recess 40 is coaxial with the core 38 in the closed position of the injection mold 1.

[0043] Alternatively, as shown in the third variation the alignment surface 43 is arranged at the bushing support 42. The bushing support 42 holds the centering bushing 39 in a floating manner in a plane perpendicular to the axial direction z. The alignment surface 43 is in the second and third variation respectively, as shown in FIGS. 4 to 6, conical in order to achieve the coaxial alignment of the core 38 and the centering recess 40.

[0044] Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the Spirit and scope of the invention.