JP4134180B2 - Injection mold and injection molding method - Google Patents

Description

  The present invention relates to an injection mold and an injection molding method for manufacturing a molded product by filling a molten resin into a mold, and particularly to a technique for smoothly releasing a cylindrical part.

  An injection mold is known as an apparatus for molding a molded product made of a resin material. The mold for injection molding is configured such that the projections and depressions that form the mold of the molded product are pre-configured in a movable mold and a fixed mold, and these molds are brought into contact with each other to form a hollow cavity having irregular surfaces between these molds. . Molten resin is poured into the cavity from the injection machine, and when the resin is filled into the cavity, the resin is cooled and solidified. Then, when the movable mold and the fixed mold are opened and returned to the original state, a molded product in which the uneven shape is transferred to the resin surface is taken out. Various methods for manufacturing a cylindrical body made of a resin material having a constant outer diameter are known (see, for example, Patent Documents 1 and 2).

  In the molded product thus formed, a slightly raised linear portion called a parting line may be formed at the boundary portion between the movable die and the fixed die. If this parting line is formed in a connection part (for example, a pipe part) with other parts, there is a possibility that the sealing performance may deteriorate even if there is no problem in strength.

For this reason, when a molded product having a cylindrical portion protruding from the main body is injection-molded, a hollow portion is disposed on the outer peripheral side, a core pin is disposed on the inner peripheral side, and the pipe portion is formed by removing the mold in the axial direction It is conceivable that no parting line is left on the outer peripheral surface.
JP-A-7-152194 JP 2001-129858 A

  The injection molding method described above has the following problems. That is, after molding the connection part, if the mold on the outer peripheral side is moved in the axial direction and the mold is opened, the mold and the molded product are in close contact with each other, and the mold release resistance is large. There was a risk of scratching. In order to prevent this scratch, it can be improved if a large draft angle is provided on the outer peripheral side, but on the other hand, since the outer diameter cannot be kept constant, it has been avoided to provide a draft angle.

  Then, this invention aims at providing the injection mold and the injection molding method which can reduce the resistance at the time of a mold opening, when forming the molded article which has the cylindrical part protruded from the main body. Yes.

  In order to solve the problems and achieve the object, the injection mold and the injection molding method of the present invention are configured as follows.

In an injection mold for forming a molded product having a cylindrical portion protruding from a main body, the mold is provided so as to be closed, and at least a first mold and a second mold that form the main body, and the first A first slider having a hollow portion that is reciprocally movable along the axial center line direction of the cylindrical portion with respect to the mold and the second mold, and has a hollow portion that forms the outside of the cylindrical portion; mounted for reciprocating motion along a direction, while being formed so as to be inserted into and removed from the hollow portion, e Bei a second slider having a core pin which forms the inside of the tubular portion, the inside diameter of the hollow portion The core pin is set uniformly, and the outer diameter of the core pin is set to be smaller toward the main body .

In an injection molding method for forming a molded product having a cylindrical part protruding from a main body part, a first slider in which a hollow portion corresponding to the cylindrical part is formed is provided at least as a first cavity corresponding to the main body part A first slider moving step of moving toward the first cavity side along the axial direction of the second cavity corresponding to the cylindrical portion with respect to the first mold and the second mold forming A second slider disposed on the opposite side of the first slider with respect to the first slider is inserted into a hollow portion of a core pin provided on the second slider so that the second cavity is formed. A second slider moving step for moving the first die toward the first cavity, a mold closing step for closing the first die and the second die, and the first and second cavities. A resin filling step of filling the molten resin, a second slider releasing step of separating the second slider from the first cavity along the axial direction, and the first slider along the axial direction. A first slider releasing step of separating from the first cavity; and a mold opening step of opening the first mold and the second mold, wherein the inner diameter of the hollow portion is set uniformly, and the core pin The outer diameter is set such that a part that decreases toward the main body part is set .

  ADVANTAGE OF THE INVENTION According to this invention, when forming the molded article which has the cylindrical site | part protruded from the main body, it becomes possible to reduce the resistance at the time of mold opening.

  FIG. 1 is a perspective view showing an injection mold 10 according to an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing the injection mold 10. In the figure, P indicates a molded product body (main body part), and Q indicates a pipe portion (cylindrical part) formed to protrude from the molded product body P. Note that C in FIG. 2 indicates the axial direction of the pipe portion Q.

  The injection mold 10 includes a fixed mold 20 and a movable mold 30 that are arranged to face each other. The stationary mold 20 is provided with an uneven portion 21 (see FIG. 8) for forming the molded product body P. Similarly, an uneven portion 31 for forming the molded product body P is formed in the movable mold 30, and a first cavity corresponding to the molded product body P is formed.

  The movable mold 30 is formed with a groove 32 in which a first slider 40 and a second slider 50, which will be described later, are held so as to reciprocate along the axial direction C.

  A pair of first sliders 40 and a pair of second sliders 50 are held in the groove 32 of the movable mold 30 so as to be able to reciprocate so as to sandwich the pair of first sliders 40. .

  The first slider 40 includes a slider body 41 and a hollow portion 42 provided in the slider body 41 (see FIG. 4). The inner wall of the hollow portion 42 corresponds to the outer peripheral surface of the pipe portion Q. The second slider 50 includes a slider main body 51 and a core pin 52 formed to protrude from the slider main body 51 toward the slider main body 41 (see FIG. 4). The core pin 52 extends along the axial direction C, and the outer peripheral wall thereof corresponds to the inner peripheral surface of the pipe portion Q. That is, the second cavity for forming the pipe portion Q is formed by the hollow portion 42 and the core pin 52. The inner diameter of the hollow portion 42 can be set to a draft of 0 ° within the required accuracy range of the outer diameter of the pipe portion Q. The outer diameter of the core pin 52 is set so as to gradually decrease toward the first cavity side.

  In the injection mold 10 configured as described above, injection molding is performed as follows.

3 is a perspective view showing an essential part of the injection molding die 10 in the second slider releasing step, FIG. 4 is a longitudinal sectional view showing the essential part, and FIG. 5 is an injection molding die in the first slider releasing step. FIG. 6 is a longitudinal sectional view showing the main part, FIG. 7 is a perspective view showing the injection mold 10 in the mold opening process, and FIG. 8 shows the injection mold 10. It is a longitudinal cross-sectional view shown. 3 to 6, the illustration of the fixed mold 20 is omitted.

  First, as shown in FIGS. 1 and 2, the first slider 40 and the second slider 50 are arranged close to the concavo-convex portion 31 side (first slider moving step / second slider moving step). Next, the stationary mold 20 and the movable mold 30 are closed (mold closing process). As a result, a first cavity (corresponding to the P portion in FIG. 2) and a second cavity (corresponding to the Q portion in FIG. 2) are formed.

  Next, the molten resin is injected into the injection mold 10 and the first cavity and the second cavity are filled with resin (resin filling step). Thereby, as shown in FIG. 2, the molded product main body P and the pipe part Q are shape | molded.

  Next, as shown in FIGS. 3 and 4, the second slider 50 is separated from the first cavity along the axial direction C (second slider releasing step). Since the outer diameter of the core pin 52 is set so as to gradually decrease toward the first cavity, the core pin 52 can be easily released. Thereby, the resin of the pipe part Q in the second cavity slightly contracts, and a gap is generated between the pipe part Q and the inner wall surface of the hollow part 42.

  Next, as shown in FIGS. 5 and 6, the first slider 40 is separated from the first cavity along the axial direction C (first slider releasing step). Thereby, the hollow part 42 is separated from the pipe part Q in the second cavity. As described above, since a gap is generated between the pipe part Q and the inner wall surface of the hollow part 42, the release resistance is very small, and the outer periphery of the pipe part Q is not damaged.

  Finally, as shown in FIGS. 7 and 8, the molded product is taken out by opening the fixed mold 20 and the movable mold 30 (mold opening process).

  As described above, according to the injection molding die 10 according to the present embodiment, when the pipe portion Q protruding from the molded product body P is formed without leaving a parting line, the outer peripheral side of the pipe portion Q It is possible to reduce the mold release resistance between the pipe portion Q and the hollow portion 42, and to prevent the outer periphery of the pipe portion Q from being damaged.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

The perspective view which shows the metal mold | die for injection molding which concerns on one embodiment of this invention. The longitudinal cross-sectional view which shows the same metal mold | die for injection molding. The perspective view which shows the principal part of the metal mold | die for injection molding in a 2nd slider cancellation | release process. The longitudinal cross-sectional view which shows the principal part. The perspective view which shows the principal part of the metal mold | die for injection molding in a 1st slider cancellation | release process. The longitudinal cross-sectional view which shows the principal part. The perspective view which shows the metal mold | die for injection molding in a mold opening process. The longitudinal cross-sectional view which shows the same metal mold | die for injection molding.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Injection mold, 20 ... Fixed side mold | die, 21 ... Uneven part, 30 ... Movable side mold, 31 ... Uneven part, 40 ... 1st slider, 42 ... Hollow part, 50 ... 2nd slider, 52 ... core pin, P ... molded product body, Q ... pipe part (cylindrical part).

Claims (2)

In an injection mold for forming a molded product having a cylindrical portion protruding from the main body,
A first mold and a second mold which are provided so as to be mold-closable and form at least the main body;
A first slider having a hollow portion that is reciprocally movable along the axial direction of the cylindrical portion with respect to the first mold and the second die, and that forms a hollow portion outside the cylindrical portion;
Mounted for reciprocating along the axis line direction, while being formed so as to be inserted into and removed from the hollow portion, e Bei a second slider having a core pin which forms the inside of the tubular portion,
The inner diameter of the hollow part is set uniformly,
An injection mold, wherein an outer diameter of the core pin is set to become smaller toward the main body . In an injection molding method for forming a molded product having a cylindrical part protruding from a main body part,
The first slider in which a hollow portion corresponding to the cylindrical portion is formed is disposed in the cylindrical portion with respect to at least the first mold and the second mold that form the first cavity corresponding to the main body portion. A first slider moving step of moving toward the first cavity along the axial direction of the corresponding second cavity;
A second slider disposed on the opposite side of the first slider with respect to the first slider is inserted into a hollow portion of a core pin provided on the second slider so that the second cavity is formed. A second slider moving step of moving toward the first cavity side,
A mold closing step of closing the first mold and the second mold;
A resin filling step of filling the first cavity and the second cavity with a molten resin;
A second slider releasing step of separating the second slider from the first cavity along the axial direction;
A first slider releasing step of separating the first slider from the first cavity along the axial direction;
A mold opening step of opening the first mold and the second mold ,
The inner diameter of the hollow part is set uniformly,
An injection molding method characterized in that an outer diameter of the core pin is set at a portion that decreases toward the main body portion side .

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