INJECTION-MOLDING TOOL AND METHOD FOR MANUFACTURING AN INJECTION-MOLDED PRODUCT WITH A LONG, THIN CHANNEL

Abstract

An injection-molding tool has a cavity-forming die and a cavity-forming core pin, which form at least a part of a cavity, provision is made for the injection-molding tool to comprise at least one core-centering device for centering and supporting the core pin. The core-centering device comprises at least one retaining pin guided in a bore of the cavity-forming die. The retaining pin is in contact with the core pin by way of an end face in a retracted position and, in an extended position, is drawn back such that the end face does not project beyond an inner surface of the cavity-forming die, in which the bore ends.

Claims

1-15. (canceled)

16. An injection-molding tool with a cavity-forming die and a cavity-forming core pin, which form at least part of a cavity, wherein the injection-molding tool comprises at least one core-centering arrangement for centering and supporting the core pin, wherein the core-centering arrangement comprises at least one retaining pin guided in a bore of the cavity-forming die, which contacts the core pin with an end face in an extended position and is drawn back in a retracted position in such a way that the end face does not project beyond an inner surface of the cavity-forming die in which the bore ends.

17. The injection-molding tool according to claim 16, wherein the cavity-forming die in the area of the bore is designed in such a way that the end face of the retaining pin closes flush with the cavity-forming surface of the die in the retracted position, so that no undercut arises on the injection-molded product or in the cavity-forming die in a demolding direction of the injection-molded product.

18. The injection-molding tool according to claim 16, wherein the end face is shaped complementarily to a contact surface of the core pin, and a shape of a contact surface border corresponds to a shape of a bore border on the cavity-forming surface of the die.

19. The injection-molding tool according to claim 16, wherein the retaining pin has a front end with a concave recess, and an inner radius of the retaining pin end face complementary to an outer radius of the core pin in the area of the contact surface.

20. The injection-molding tool according to claim 16, wherein the cavity-forming die has a depression aligned parallel to the core pin, an inner radius of which in the area of the bore corresponds to an outer radius of the core pin in the area of the contact surface.

21. The injection-molding tool according to claim 16, wherein the injection-molding tool has two core-centering arrangements, each with a retaining pin.

22. The injection-molding tool according to claim 21, wherein retaining pins are aligned coaxially and arranged diametrically in relation to a longitudinal axis of the core pin.

23. The injection-molding tool according to claim 16, wherein a plurality of core-centering arrangements are arranged one after the other in a longitudinal direction of the core pin.

24. The injection-molding tool according to claim 16, wherein the core-centering arrangement has two retaining pins, which are arranged one after the other in a longitudinal direction of the core pin.

25. The injection-molding tool according to claim 16, wherein the retaining pin is arranged so as to be displaceable at a right angle to the core pin.

26. The injection-molding tool according to claim 16, wherein the core-centering arrangement has a front stop for limiting the extended position of the retaining pin and/or wherein the core-centering arrangement has a rear stop for limiting the retracted position of the retaining pin.

27. The injection-molding tool according to claim 16, wherein the core-centering arrangement has a sensor which detects the retracted position of the retaining pin.

28. An injection-molded product with a channel formed by a core pin, manufactured with an injection-molding tool according to claim 16.

29. The injection-molded product according to claim 28, wherein the injection-molded product has an oblong, preferably tubular, channel section, an exterior side of which has arranged on it a projection running in an axial direction of the channel section, wherein an outer radius of the projection corresponds to an inner radius of the channel section perpendicular to the longitudinal axis of the channel.

30. A method for manufacturing an injection-molded product with an oblong channel, the method comprising: introducing a cavity-forming core pin into a cavity-forming die; displacing at least one retaining pin into an extended position, so as to bring a contact surface of the core pin into contact with a complementary end face of the retaining pin; injecting at least one plastic melt until at least one area of a cavity formed by the core pin and the die is almost completely filled; displacing the at least one retaining pin in a retracted position, in which the end face closes flush with an inner surface of the cavity-forming die, or a partially retracted position, in which the end face is spaced apart from the core pin and projects completely over the inner surface of the cavity-forming die; concluding the injection of the at least one plastic melt until the cavity is completely filled; if necessary, displacing the at least one retaining pin into a completely retracted position, in which the retaining pin is drawn back in such a way that the end face does not project beyond the inner surface of the cavity-forming die, provided the retaining pin was in the partially retracted position; and demolding the injection-molded product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The invention will be described in more detail below based on exemplary embodiments in conjunction with drawing(s) thereof. Shown in:

[0026] FIG. 1 is a perspective, partial view of an injection-molded product with an oblong channel section;

[0027] FIG. 2 is a sectional view along I-I through the channel section from FIG. 1;

[0028] FIG. 3 is a perspective, partial view of the injection-molded product from FIG. 1 and two retaining pins;

[0029] FIG. 4 is a sectional view along II-II from FIG. 3;

[0030] FIG. 5 is a sectional view through a channel section with two channels;

[0031] FIG. 6A is a sectional view of an injection-molded tool with centering arrangement, and FIG. 6B is a detailed view A from FIG. 6A;

[0032] FIG. 7A is a sectional view along III-III of the injection-molding tool from FIG. 6A, and FIG. 7B is a detailed view B from FIG. 7A; and

[0033] FIG. 8A is a partially cut, perspective view of the injection-molding tool from FIG. 6A, and FIG. 8B is a detailed view C from FIG. 8A.

PREFERRED EMBODIMENTS OF THE INVENTION

[0034] FIG. 1 shows a perspective, partial view of an injection-molded product with an oblong channel section 1. FIG. 2 shows a sectional view along I-I through the channel section from FIG. 1. FIG. 3 shows a perspective, partial view of the injection-molded product from FIG. 1, and two retaining pins 31 as arranged in the injection-molding tool relative to the injection-molded product. FIG. 4 shows a sectional view along II-II from FIG. 3.

[0035] In the embodiment shown, the channel section 1 forms a continuous channel 4 in an axial direction with through holes on both sides. An oblong rib 3 running in an axial direction of the channel 4 is molded on the exterior side 2 of the channel section, and its function will be described further below.

[0036] The channel 4 usually has a slightly conical shape with an inclination of approx. 2 degrees, so that a cavity-forming core pin 11 necessary for forming the channel 4 (e.g., see FIGS. 6A and 6B) can be easily pulled out in a demolding direction A. If possible, the core pin 11 is retained on both sides in the closed tool. If a channel that can be several centimeters long is to be fabricated with a small diameter, e.g., of approx. 1 mm, the core pin 11 is most often not rigid enough, and it can happen during the injection-molding process that the latter is pushed away from a central position. In order to prevent this pushing away, the injection-molding tool for manufacturing the injection-molded product with an oblong channel section 1 has two core-centering arrangements 30 (e.g., see FIGS. 6A and 6B), each with one retaining pin 31. FIGS. 3 and 4 depict the retaining pins 31 in the manner in which they are arranged relative to the injection-molded product in the injection-molding tool. The two retaining pins 31 are arranged in the area of the molded-on ribs 3. These ribs 3 are shaped in such a way as to not form any undercuts, and allow the plastic product to be easily demolded. Depending on the positioning of the retaining pins, they can be longer or shorter.

[0037] In order to fix the core pin 11 in the central position, the two retaining pins 31 are made to abut against the core pin in an extended position before injecting the plastic melt. Only once the cavity 12 (e.g., see FIGS. 6A and 6B) that forms the channel section 1 is nearly completely filled are the two retaining pins 31 moved into a retracted position, and the resultant gap in the injection-molded part is filled with the still liquid plastic melt. This process is schematically depicted on FIG. 4. The core pin 11 is shown in the extended position on the left side. The core pin 11 is shown in the retracted position on the right side.

[0038] In order for the two retaining pins 31 to fully abut against the core pin 11 in the extended position, their front ends 33 have a concavely shaped end face 32, which has an inner radius corresponding to the outer radius of the core pin 11 or the inner radius 5 of the channel 4.

[0039] In order to prevent the two retaining pins 31 from remaining immersed in the injection-molded product in the retracted position and also forming a depression in the cavity-forming die 10, the molded-on rib 3 has an outer radius 6 that also corresponds to the inner radius 5 of the channel 4 or outer radius of the core pin 11 or the inner radius of the end face 32. In this way, the end face 32 of the retaining pin 31 closes flush with the cavity-filming die. An immersion of the retaining pins 31 or a depression or undercut in the cavity wall is prevented.

[0040] FIG. 5 shows a sectional view through a channel section 1 with two channels. As opposed to the injection-molded product described above, two channels are formed here. A sickle-shaped channel 7 that is rigid enough owing to the sickle shape, and a circular, eccentrically arranged channel 4. The channel 4 is also formed by a thin core pin, which is supported on both sides by retaining pins. For this purpose, the channel section has two molded-on projections 3, the outer radius 6 of which also corresponds to the inner radius 5 of the channel 4. The two projections or ribs 3 are arranged offset to the midpoint of the channel section corresponding to the displacement direction of the retaining pins.

[0041] It would also be conceivable to form two circular channels, the core pins of which are each fixed in place with retaining pins.

[0042] FIGS. 6A and 6B show a sectional view of a cutout or parts of an injection-molding tool with two core-centering arrangements 30 in FIG. 6A and a detailed view from FIG. 6A (a) in FIG. 6B. A cavity-forming die 11 and the cavity-forming core pin 11 form the cavity 12 for the channel section 1 of the injection-molded product. A depression or groove 16 is formed in the cavity-forming die 11, and comprises the projection or rib 3 of the channel section 1. Present in the cavity-forming die 11 for each core-centering arrangement is a bore 13 in which the respective retaining pin 31 is guided. In the core-centering arrangement 30 depicted at the top of FIG. 6A, the retaining pin 31 is in the extended position, and its end face 32 contacts the contact surface 14 of the core pin 11. In the core-centering arrangement 30 shown below, the retaining pin 31 is in the retracted position, and closes flush with the cavity-forming surface 15 of the die 10 that surrounds the bore 13.

[0043] The core-centering arrangement 30 further comprises a contact sensor 36, which detects whether the retaining pin 31 is in the retracted position. Only once the retaining pins 31 are in the retracted position can the injection-molding tool be opened, and the injection-molded product be demolded.

[0044] FIGS. 7A and 7B present a sectional view along III-III of the injection-molding tool from FIGS. 6A and 6B in FIG. 7A, and a detailed view B from FIG. 7A in FIG. 7B. Visible among other things in this illustration are a front stop 34 and a rear stop 35. These limit the maximum displacement of the retaining pins 31, so that the end face 32 of the latter abuts precisely against the core pin 11 in the extended position, and the end face 32 closes flush with the surface of the cavity-forming die 10 in the retracted position. In FIG. 7A, the retaining pin 31 above is in the extended position, and the retaining pin 31 below is in the retracted position.

[0045] FIGS. 8A and 8B present a partially cut, perspective view of the injection-molding tool from FIGS. 6A and 6B in FIG. 8A, and a detailed view C from FIG. 8A in FIG. 8B. In FIG. 8A, the retaining pin 31 on the right is in the retracted position, and the retaining pin 31 on the left is in the extended position. As evident from this illustration, the end face 32 closes flush with the surface 15 of the cavity-forming die 10 that surrounds the bore 13. The end face 32 of the extended retaining pin 31 rests on the contact surface 14 of the core pin 11.

REFERENCE LIST

[0046] 1 Channel section [0047] 2 Exterior side of the channel section [0048] 3 Projection, rib [0049] 4 Channel [0050] 5 Inner radius of the channel [0051] 6 Outer radius of the projection [0052] 7 Sickle-shaped channel [0053] 10 Cavity-forming die [0054] 11 Cavity-forming core pin [0055] 12 Cavity [0056] 13 Bore [0057] 14 Contact surface [0058] 15 Cavity-forming surface [0059] 16 Depression, groove [0060] 30 Core-centering arrangement [0061] 31 Retaining pin [0062] 32 End face [0063] 33 Front end [0064] 34 Front Stop [0065] 35 Rear stop [0066] 36 (Contact) sensor [0067] 37 Concave recess [0068] A Demolding direction