JPS60112413A - Pop-up core - Google Patents

Abstract

PURPOSE:To enable to form a molded part with deep undercut by a structure wherein the projection of a first side part sliding member is arranged nearer to the free end of a core bar than the projection of a second side part sliding member of an open core for an injection mold. CONSTITUTION:Firstly, movable forces 5 are separated from a fixed force after the forming of a molded part 8. Secondly, the molded part 8 is released from a second side part sliding member 3, on which a projection 36 is provided, by shifting guide plates 52, 53, 55, 56 and a removing plate 54 away from a base 51 along a core bar 1 equipped with different inclinations. Thirdly, when the guide plates 55 and 56 and the removing plate 54 are shifted further while the guide plates 52 and 53 being kept immobile, the member 3 does not shift because the member 3 is checked by the projection 36 while a first side part sliding member 2 is shifted along the slant surface of the core bar 1 by means of the projection 26 so as to be shifted axially and radially without being interferred with the member 3, resulting in releasing the molded part 8 from the first side part sliding member 2. Fourthly, the removing plate 54 is furthermore shifted upwards. Thus, the molded part with deep undercut can be removed from the molding forces and be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides a fixed end, a free end, and an outer surface that tapers in a conical shape from the fixed end toward the free end, and the fixed end is attached to a substrate of a mold for injection molding. Around the core rod fixed at A side sliding member is attached to the core rod so that it can slide in the axial direction over the outer surface of the core rod, and the side sliding member is attached to the core rod so that it can slide in the axial direction over the outer surface of the core rod, and the side sliding member is attached to the core rod so that it can slide in the axial direction over the outer surface of the core rod. The present invention relates to an open core in which first and second side sliding members are formed with partially annular protrusions that are moved by the user.

Open cores of this type are already known. An example thereof will be described below with reference to FIGS. 1a to 5e.

The known open core shown in FIGS. 1a to 5e has a core rod 1. FIG. There are two groups of side sliding members 2 around the core rod.
．． 6 is placed. The side sliding members belonging to each group are equally constructed. Each of the first side slides 2 is alternately spaced with a second side slide 3 around the core rod 1. The core rod 1 can include an attached central core 4 (FIGS. 3 and 4).

One or more open cores are a component of a mold 7 (shown particularly in FIG. 5c).

Briefly, the mold 7 consists of a fixed mold 6 and a movable mold 5 that are movable relative to each other, as shown in FIG. 5c, and an injection molded product 8 is formed between them.

The fixed mold 6 includes, for example, a mounting plate 61 and a hollow plate 62 attached thereto, and the mounting plate 61 is provided with a nozzle 9. The movable mold 5 has a base plate 5 to which the core rod 1 is screwed.
1. It has two guide plates 52, 53 and a removal plate 54.

The end of the core rod 1 is formed as a connecting part 11 for connection with a base plate 51 of the movable mold 5. At the free end of the connecting part 11 a screw 12 is provided. At the outer end of the connecting part 11 a central cooling aperture 13 opens, which extends over the entire core rod 1 to the region of the opposite end of the core rod 1 .

In the example shown in FIGS. 1a to 5e, the core rod 1 is provided with a conical outer surface portion 14, 15 which connects to the connecting portion 11.
The conical inclination of the conical outer surface portion 15 defined by the angle β is greater than the conical inclination of the conical outer surface portion 14 defined by the angle α, which in this example is approximately twice. along the conical outer surface portion 14 the first lateral sliding member 2;
slides, and the second side sliding member 3 slides along the conical outer surface portion 15. For retaining the first and second side sliding members 2, 3, the conical outer surface portion 14.15 has a dovetail groove 16.17.
Equipped with Conical outer surface portion 14.15 and dovetail groove 16
．． 17 starts at the connecting part 11 and ends at the end of the core rod 1 opposite the connecting part 11.

The first lateral sliding member 2, which slides along the conical outer surface portion 14 of the core rod 1 and is guided in a dovetail groove 16, has a substantially arcuate cross-section. Each arcuate string 21 is interrupted by a dovetail projection 22 that engages in a dovetail groove 16. The dovetail groove 16 and the dovetail projection 22 constitute a dovetail engagement, which can also be achieved by forming a dovetail groove on the first side sliding member 2 and providing a dovetail projection on the outer surface portion 14. It can be achieved.

Each first side sliding member 2 has a shoulder 24 at its free end, the outer surface 25 of which fits into the inner surface of the injection molded part 8 (FIG. 5C).
. In this embodiment the outer surface 25 is provided with parallel grooves. shoulder 24
At a distance from each other, each first lateral slide 2 has a partially annular projection 26, by means of which an axial movement of the first lateral slide 2 within the movable mold 5 of the mold 7 is achieved. Ru.

The second side sliding member 3, which slides on the conical outer surface portion 15 of the core rod 1 and is guided in a dovetail groove 17, has a substantially trapezoidal cross-section, which trapezoid forms on each first side. The sliding member 2 has an outer base 61 which is curved to match the arcuate roundness of the sliding member 2. The further base 32 is interrupted by a dovetail projection 33 which forms a dovetail engagement with the dovetail groove 17, by means of which the second lateral sliding member 1'5 is guided in the dovetail groove 17. Each trapezoid has a side 37 and a chord 2 of the adjacent first side sliding member 2.
Touches 1. The second side sliding member 5 further has a shoulder 3 at its free end.
4, the outer surface 35 of which matches the inner surface of the injection molded article 8 (FIG. 5c) to be manufactured. Remotely from the outer surface 35 each second lateral slide member 3 has a partially annular projection 66 .

Projections 26 and 66 form a complete annular band. An axial movement of the second lateral slide 3 within the stationary mold 5 (FIG. 5c) of the mold 7 is achieved by means of the annular band.

In the example shown in FIGS. 3 and 4, the core rod 1 is formed as a hollow body with an open outer end. The hollow body is filled with a central core 4 which is inserted from the open outer end side. The head 41 of the central core 40 serves as a molding core and is formed to correspond to the shape of the injection molded article 8 to be manufactured. If the core rod 1 has a central core 4, it is preferred that the cooling apertures 42 run axially through the central core 4. With this configuration, an injection molded article can be formed which has an extension, for example a cylindrical extension, with an axial hole behind the undercut.

The method of operation of the open core shown in Figures 1a to 5e will now be described. During the injection molding operation, the mold 7 is closed, that is, the movable mold 5 (and the open core attached thereto) and the fixed mold 6 are closed together, as shown in FIG. A molding material is injected into the cavity through a nozzle 9 to form an injection molded product 8. After the mold 7 has been opened after completion of the injection molding operation, i.e. after the movable mold 5 and the fixed mold 6 have been separated, the sliding member guide plate 52 is first moved as shown in FIG. 5b. .53 removed plate 54
At the same time, the substrate 51 is moved by a distance S in the axial direction. The slide guide plates 52, 53 are screwed together so that only a stroke S can be completed. Since the core rod 1 is rigidly connected to the base plate 51, the first and second lateral sliding members 2.3, which are entrained via the projections 26.56, move by a distance S.

The angle α (FIGS. 1b, 2b) defining the conical inclination of the outer surface 14 of the core rod 1 and the first lateral slide 2 is the angle α (FIGS. 1b, 2b) that defines the conical inclination of the outer surface 15 of the core rod 1 and the conical slope of the second lateral slide 3 Since the magnitude is approximately half of the angle β defining the degree of inclination, the second side sliding member 3 not only slides in the axial direction by a distance S, but also slides on the chord 21 of the adjacent first side sliding member 2. Slide inward along.

This allows movement of the first lateral sliding member 2 along the conical outer surface portion 14 of the core rod 1. Since the relationship β=2α exists, at the end of the axial movement the inner edge of the free end of the second lateral sliding member B is twice as large as the inner edge of the free end of the first lateral sliding member 2 relative to its starting position. is moved radially inward by a stroke of magnitude. In the state of FIG. 5C, the distance S1 of the inner edge of the second side sliding member 3 from the equal center line is
(FIG. 2b) is also smaller than the distance S2 of the inner edge of the first side sliding member 2 from the center line. After the course of the stroke S, the injection molded part 8 is freed inwardly from the first and second lateral slide members 2, 3 as a result of a continuous, harmonious parallel axial and radial movement. At this time, these side sliding members 2. The maximum outer diameter of B is smaller than the minimum inner diameter of the injection molded product 8. The viewing plate 54 can therefore be moved away from the sliding element guide plate 52,53 as shown in FIG. 5e. During the return movement of the component of the movable mold 5 of the mold 7 to its starting position, the first and second lateral sliding members 2
, 6 again slide along the core rod 1 and return to its starting position. A new injection molding operation can then be started. In this case, it is preferable that the mold be a multiple molding mold and equipped with many open cores.

Although the known open core illustrated in FIGS. 1a to 5e is suitable for forming injection molded parts with undercuts, for example, when the undercut is deep, side slippage occurs as shown in FIG. 5b. A disadvantage is that the side slides interfere with each other, ie, collide with each other, before the parts leave the injection molded part, so that no further movement of the side slides can be achieved.

The invention therefore aims to eliminate the disadvantages of the known open cores as mentioned above.

To achieve this object, the open core according to the invention, which is mounted on a mold for injection molding, is provided in a configuration as described at the outset, in which the projections of the first lateral sliding member are aligned with the projections of the second lateral sliding member. It is characterized by being closer to the free end of the core rod than the core rod.

Hereinafter, embodiments of the open core of the present invention will be described with reference to FIGS. 6a to 7c. This implementation f! The structure of the open core of No. 1 is exactly the same as the structure of the known open core shown in FIGS. The explanation for this will be omitted, and the explanation for the known open core will apply.

In Figures 6a to 7C, 1 is the core rod, 2 is the first
side sliding members, 6 are second side sliding members, 26 and 66;
indicates a partially annular protrusion. The feature of this embodiment is the core n1
The distance from the free end 1B to the projection 26 of the first side sliding member 2 is smaller than the distance from the free end 16 to the projection 36 of the second side sliding member 3.

The molding die 7 to which the open core is attached is made up of a movable die 5 and a fixed die 6 in the same way as in the known example described above, and the fixed die is composed of, for example, a mounting plate 61 and a hollow plate 62 attached thereto. A nozzle 9 is provided on the mounting plate 61. Movable type 5
is a board 51 to which the core rod 1 is fixed; four guide plates 52;
．． 53, 55, 56 and a removing plate 54. Protrusion 36
The guide plates 52 and 56 that clamp the projection 26 and the guide plates 55 and 56 that clamp the protrusion 26 are respectively movable as a unit by screw connection, for example.

The method of operating the open core shown in Figures 6a to 7c will now be described. During an injection molding operation, the mold 7 is closed, i.e. the movable mold 5 (and the open core attached thereto) is closed, as shown in FIGS. 6a and 7a.
and fixed mold 6 are closed together, and a molding material is injected into the cavity between them through nozzle 9 to form injection molded product 8.

After the mold 7 is opened after the injection molding operation is completed, that is, after the movable mold 5 and the fixed mold 6 are separated, the guide plates 52, 53 are first installed as shown in FIGS. 6b and 7b.
．． 55.5<S together with the remover plate 54 are moved axially relative to the substrate 51.

At that time, the first side sliding member 2 and the second side sliding member 3
The movement is similar to that described for the example of the known open core, and at the end of the movement, the first side sliding member 2 and the second side sliding member 3 do not interfere, but if this movement continues further, they will interfere. happens.

At the end of this movement, the injection molded part 8 has also become free of the second lateral slide 6 but not the first lateral slide 2.
I have not been free from it. 6c and 7c while the guide plate 52,53 remains immobile relative to the base plate 1.
The guide plates 55, 56 are moved further relative to the substrate 1 together with the removing plate 54 as shown in the figure. Due to this movement, the second side sliding member 6 remains stationary, but the first side sliding member 2 moves axially and radially inward without interfering with the second side sliding member B. This also frees the injection molded part 8 from the first lateral slide 2 . Next, the removal plate 54 is moved to the guide plate 55 in the same manner as shown in FIG. 5e.
56.

Since the open core of the present invention is constructed and operates as described above, it can be effectively used for injection molded products with deep undercuts.

[Brief explanation of the drawing]

FIG. 1a is an end view of the known open core in the injection state shown in FIG. 1b, FIG. 1b is a cross-sectional view through the axis of FIG. 1a, and FIGS. 2a and 2b are the known open core in the opened state. 1a and 1b, FIG. 3 is a sectional view taken along the axis of a known opening core with a central core attached in the injection state, and FIG. 4 is the opening shown in FIG. 6 in the mold opening state. Figure similar to Figure @5 showing the core, 5th
Fig. 5a is an end view of the known open core in the injection molded state attached to the mold, Fig. 5b is a sectional view through the axis of Fig. 5a, and Figs. 5c, 5d, and 5e are Figures 6a, 6b and 6c sequentially show the positions of the components of a known mold with an open core in the opening stage; Figures 6a, 6b and 6c show a mold with an open core according to the invention shown in vertical section; Figures 7a, 7b and 7c are end views of the opening core shown in Figures 6a, 6b and 6c. In the drawing, 1 is the core rod, 2 and 3 are the first and second
Side sliding member, 4 is the central core, 16 is the cooling hole, 1
4 and 15 are the outer surface parts of the core rod. 16 and 17 are dovetail grooves, 26 is a projection of the first side sliding member, 27 is a side wall of the first sliding member, 2nd is an inner surface of the first side sliding member, 36 is a projection of the second sliding member, 38 is a projection of the second sliding member. The inner surface of the second side sliding member, 39 designates the side wall of the second sliding member.

Claims (1)

[Claims] A groove 9 of a core rod having a fixed end, a free end and an outer surface terminating in a conical shape from the fixed end to the free end and fixed at the fixed end to the substrate of a mold for injection molding. , a first side sliding member and a second side sliding member having a larger conical slope are arranged every other side in the circumferential direction, and the first and second side groove members are arranged on the core rod. A partially annular protrusion is attached to the core rod so as to be able to slide in the axial direction along the outer surface thereof, and is trapped in the axial direction by a guide plate of the mold that is movable in the axial direction of the core rod with respect to the substrate of the mold. In the open core formed in the first and second side sliding members, the protrusion of the first side sliding member is closer to the free end of the core rod than the protrusion of the second side sliding member. An open core that is attached to a mold for injection molding.