JP2010110768A - Die for die-casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a die for die-casting which securely prevents a broken chip from mixing into a cavity. <P>SOLUTION: A gap 70 in a radial direction is arranged between an outer circumferential surface of an injection sleeve 30 and an inner circumferential surface of a through-hole 11a of a fixed die 10. Accordingly, thermal insulation is maintained between the injection sleeve 30 and the fixed die 10, and heat transfer from the injection sleeve 30 to the fixed die 10 is prevented, so that a melt inside the injection sleeve 30 is prevented from being solidified. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a die casting mold.

  Molding with a die-casting mold includes the process of pouring the molten metal into the injection sleeve attached to the mold, the process of pushing the molten metal inside the injection sleeve toward the cavity with the plunger tip, and cooling the mold to cool the molten metal. It is performed by going through a solidifying step. For example, in the die casting mold shown in Patent Document 1, a through hole is formed in the mold, and the tip of the injection sleeve is fixed to the inner periphery of the through hole.

JP-A-7-51830

  When the molten metal is supplied to the injection sleeve fixed to the inner periphery of the through hole of the mold as in the die casting mold of Patent Document 1, the heat of the molten metal is deprived by the mold through the injection sleeve. There is a risk that the molten metal partially solidifies. If the plunger tip is pushed in this state, a metal layer (breaking chill) solidified inside the injection sleeve may be mixed into the cavity.

  An object of the present invention is to provide a die casting mold that can surely prevent the possibility of a broken chill entering a cavity.

  In order to solve the above-described problems, a die casting mold of the present invention includes a fixed mold, a movable mold, a cavity formed by the fixed mold and the movable mold, a through hole formed in the fixed mold, and leading to the cavity. An injection sleeve having a tip inserted into the hole, and a plunger tip that is slidably provided in the injection sleeve and pushes the molten metal supplied into the injection sleeve into the cavity. A gap is provided between the peripheral surface.

  Thus, by providing a gap between the outer peripheral surface of the injection sleeve and the inner peripheral surface of the through hole, it is possible to insulate between the injection sleeve and the fixed mold. Thereby, the heat transfer from the injection sleeve to the stationary mold can be prevented, and the molten metal supplied to the inside of the injection sleeve can be prevented from solidifying.

  In the case of a so-called horizontal die casting mold in which the injection sleeve is arranged in a substantially horizontal direction and the molten metal is supplied from the side of the mold, the molten metal poured into the injection sleeve accumulates in the lower part of the internal space of the injection sleeve. (See FIG. 1). For this reason, the lower part of the injection sleeve has a long contact time with the molten metal and maintains a relatively high temperature state. On the other hand, the upper portion of the injection sleeve contacts the molten metal only when the molten metal is pushed in by the plunger (see FIG. 2), and does not contact the molten metal at other times. For this reason, the upper part of the injection sleeve has a short contact time with the molten metal, and the temperature tends to decrease. The temperature difference between the upper part and the lower part of the injection sleeve increases, the difference in thermal expansion increases, the cylindricality of the injection sleeve decreases, and the inner peripheral surface of the injection sleeve interferes with the plunger when the plunger is pushed in, There is a risk of so-called “galling”. Therefore, in the upper part of the injection sleeve, the contact area between the injection sleeve and the fixed mold is increased to enhance the heat insulation effect, and in the lower part of the injection sleeve, the contact area between the injection sleeve and the fixed mold is reduced to provide a heat insulation effect. By making the diameter relatively small, the temperature difference between the upper part and the lower part of the injection sleeve can be reduced, and the cylindricality of the injection sleeve can be maintained.

  As described above, in the die casting mold of the present invention, the injection sleeve and the mold are insulated to maintain the temperature of the injection sleeve, thereby preventing the molten metal supplied to the inside of the injection sleeve from being solidified. Mixing of broken chill into the cavity can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  A die casting mold 1 shown in FIG. 1 includes a fixed mold 10, a movable mold 20, an injection sleeve 30, a fixed platen 40, and a plunger chip 50. The die casting mold 1 is a horizontal die casting mold in which the central axis of the injection sleeve 30 is arranged in a substantially horizontal direction and the molten metal is supplied from the side. In the following, for convenience of explanation, in the direction of the central axis of the injection sleeve 30 (indicated by M in FIG. 1), the movable mold 20 side (left side in FIG. 1) is forward and the opposite side (right side in FIG. 1) is rearward. Say.

  The fixed mold 10 includes a main mold 11, a nested mold 12 fixed to the front end surface of the main mold 11, and a mold sleeve 13 fixed to the inner periphery of the nested mold 12. A through hole 11a is formed in the main mold 11, and the tip of the injection sleeve 30 is inserted and fixed to the inner periphery of the through hole 11a. A hole 12a is formed in the insert mold 12, and a mold sleeve 13 is fixed to the inner periphery of the hole 12a. In a state where the fixed mold 10 and the movable mold 20 are clamped (the state shown in FIG. 1), a runner 60, a gate, and a cavity (not shown) are formed between the nested mold 12 and the movable mold 20. The

  The injection sleeve 30 is attached to the fixed mold 10 with one end inserted into the through hole 11a of the main mold 11 and the other end protruding rearward from the main mold 11. A pouring port 31 for pouring the molten metal into the injection sleeve 30 is formed at the rear end of the injection sleeve 30. A cooling path 32 extending in the axial direction is formed in the lower portion 30 b of the injection sleeve 30, and the cooling path 32 is formed over substantially the entire length of the injection sleeve 30 in the illustrated example. The front end portion of the injection sleeve 30 is in contact with the mold sleeve 13 of the fixed mold 10, and the inner diameter dimension R1 of the injection sleeve 30 is set slightly smaller than the inner diameter dimension R2 of the rear end portion of the mold sleeve 13 ( R1 <R2). Thereby, even when the positions of the injection sleeve 30 and the mold sleeve 13 are slightly deviated, the undercut does not occur.

  The inner peripheral surface 33 of the injection sleeve 30 is formed in a cylindrical surface shape. A plunger tip 50 is slidably disposed in the inner periphery of the injection sleeve 30 in the axial direction, and the plunger tip 50 pushes the molten metal supplied into the injection sleeve 30 toward the cavity. The injection sleeve 30 extends further forward than the position where the plunger tip 50 is pushed most in (see FIG. 2). In other words, a sliding surface with the plunger tip 50 is integrally formed with the inner peripheral surface 33 of the injection sleeve 30 in the entire sliding region of the plunger tip 50. For this reason, the joint between members is not formed in the middle of the sliding surface, and the plunger tip 50 can be smoothly slid.

  The outer peripheral surface 34 of the injection sleeve 30 includes a first outer peripheral surface 34a provided at the front end portion, a second outer peripheral surface 34b provided behind the first outer peripheral surface 34a and having a larger diameter than the first outer peripheral surface 34a. The third outer peripheral surface 34c is provided behind the second outer peripheral surface 34b and is slightly smaller in diameter than the first outer peripheral surface 34a. A tapered surface 35 is formed between the first outer peripheral surface 34a and the second outer peripheral surface 34b. A radial shoulder surface 36 is formed between the second outer peripheral surface 34b and the third outer peripheral surface 34c.

  The distal end portion (front end portion) of the injection sleeve 30 is inserted into the inner periphery of the through hole 11 a of the main mold 11. In the illustrated example, the first outer peripheral surface 34 a, the second outer peripheral surface 34 b, and the tapered surface 35 of the injection sleeve 30 are arranged on the inner periphery of the through hole 11 a of the main mold 11, and the second outer peripheral surface 34 b is the main mold 11. Are fitted and fixed to the inner peripheral surface of the through hole 11a. A gap is formed between the outer peripheral surface of the injection sleeve 30 and the fixed mold 10, and in the illustrated example, the first outer peripheral surface 34 a or the tapered surface 35 of the injection sleeve 30 and the inner periphery of the through hole 11 a of the main mold 11. A radial gap 70 is formed between the surfaces. Specifically, in the radial gap 70, a region above the central axis M (hereinafter referred to as an upper region 71) reaches the tapered surface 35 from the front end of the injection sleeve 30, and is a region below the central axis M. (Hereinafter, the lower region 72) extends from the front end of the injection sleeve 30 to the middle of the first outer peripheral surface 34a. That is, the axial dimension L1 of the upper region 71 of the radial gap 70 is larger than the axial dimension L2 of the lower region 72 (L1> L2). Thereby, the contact area between the upper part 30 a of the injection sleeve 30 and the main mold 11 is smaller than the contact area between the lower part 30 b and the main mold 11. Further, the radial dimension D1 of the upper region 71 of the radial gap 70 is smaller than the radial dimension D2 of the lower region 72 (D1 <D2).

  The third outer peripheral surface 34 c of the injection sleeve 30 protrudes rearward from the main mold 11 and is fitted and fixed to the inner peripheral surface 41 of the fixed platen 40. Further, the shoulder surface 36 of the injection sleeve 30 is in contact with the front end portion 42 of the fixed platen 40. That is, the injection sleeve 30 is positioned in the axial direction by sandwiching the front end portion and the shoulder surface 36 between the mold sleeve 13 and the fixed platen 40.

  Next, a molding process using the die casting mold 1 having the above-described configuration will be described.

  First, the molten metal is poured into the injection sleeve 30 from the pouring port 31 in a state where the plunger tip 50 is arranged behind the pouring port 31 of the injection sleeve 30 (see FIG. 1). At this time, as described above, the radial clearance 70 is provided between the injection sleeve 30 and the fixed mold 10, specifically, between the first outer peripheral surface 34 a of the injection sleeve 30 and the inner peripheral surface of the through hole 11 a of the main mold 11. Therefore, the contact area between the injection sleeve 30 and the fixed mold 10 can be reduced. Thereby, the heat insulation effect between the injection sleeve 30 and the fixed mold | type 10 can be heightened, and solidification of the molten metal supplied into the inside of the injection sleeve 30 can be prevented.

  Further, since the molten metal accumulates in the lower portion 30b of the injection sleeve 30, the temperature of the lower portion 30b tends to be higher than that of the upper portion 30a. When the temperature difference between the lower portion 30b and the upper portion 30a increases, the difference between the expansion amounts increases, and the injection sleeve 30 may be deformed. As described above, if the axial dimension L1 of the upper region 71 of the radial gap 70 formed between the injection sleeve 30 and the fixed mold 10 is larger than the axial dimension L2 of the lower region 72, the injection sleeve 30 is provided. The contact area between the upper part 30 a and the fixed mold 10 can be made smaller than the contact area between the lower part 30 b and the fixed mold 10. Thereby, while the heat insulation effect of the upper part 30a with few contact with molten metal can be heightened and the temperature fall of the upper part 30a is suppressed, the heat insulation effect of the lower part 30b with many contact with molten metal can be reduced. Accordingly, the temperature difference between the upper portion 30a and the lower portion 30b of the injection sleeve 30 can be reduced to reduce the difference in the expansion amount in the circumferential direction, thereby reducing the cylindricity of the inner peripheral surface of the injection sleeve 30. Can be suppressed.

  Further, as described above, the cooling passage 32 extending in the axial direction is provided in the lower portion 30b of the injection sleeve 30, and only the lower portion 30b is cooled, thereby reducing the temperature difference between the upper portion 30a and the lower portion 30b. be able to. Thereby, the difference of the expansion amount (elongation) in the axial direction between the upper portion 30a and the lower portion 30b of the injection sleeve 30 can be reduced, and the possibility that the rear end portion of the injection sleeve 30 warps upward is prevented. Can do.

  Thereafter, the plunger tip 50 is pushed forward, and the molten metal supplied into the injection sleeve 30 is injected into the cavity through the runner 60 and the gate (see FIG. 2). And while pressurizing molten metal with the plunger chip | tip 50, a cooling water is poured in the cooling path (illustration omitted) formed in the metal mold | die, and a metal mold | die is cooled. Thereby, the molten metal in the cavity, the gate, and the runner 60 is sequentially solidified, and finally the molten metal at the front end portion of the injection sleeve 30 is solidified. After solidification, the mold is opened to separate the product from the mold.

  The present invention is not limited to the above embodiment. For example, in the above description, the axial dimensions of the upper region 71 and the lower region 72 of the radial gap 70 are different from each other. However, the present invention is not limited to this, and for example, when it is desired to enhance the heat insulation effect between the injection sleeve 30 and the fixed mold 10. As shown in FIG. 3, the axial dimension of the radial gap 70 may be increased over the entire circumference of the injection sleeve 30.

  On the other hand, when the temperature difference between the upper portion 30a and the lower portion 30b of the injection sleeve 30 is large, the difference in the axial dimension between the upper region 71 and the lower region 72 of the radial gap 70 is increased. What is necessary is just to enlarge the difference of a contact area with the fixed mold | type 10. For example, as shown in FIG. 4, only the upper region 71 may be formed and the lower region 72 may be omitted.

It is sectional drawing of the injection sleeve vicinity of a die-casting metal mold | die (plunger retreat position). It is sectional drawing of the injection sleeve vicinity of a die-cast metal mold | die (plunger pushing position). It is sectional drawing of the injection sleeve vicinity of the die-casting die concerning another example. It is sectional drawing of the injection sleeve vicinity of the die-casting die concerning another example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die-cast metal mold 10 Fixed mold 11 Main mold 11a Through hole 12 Nest mold 20 Movable mold 30 Injection sleeve 30a Upper part 30b Lower part 31 Pouring port 32 Cooling path 33 Inner peripheral surface 34 Outer peripheral surface 40 Fixed platen 50 Plunger chip 60 Hot water Road 70 Radial gap 71 Upper region 72 Lower region

Claims (2)

A fixed mold, a movable mold, a cavity formed by the fixed mold and the movable mold, a through hole formed in the fixed mold, leading to the cavity, an injection sleeve having a tip inserted into the through hole, and a slide in the injection sleeve A plunger tip that is provided so as to push the molten metal supplied into the injection sleeve into the cavity;
A die casting mold in which a gap is provided between the outer peripheral surface of the injection sleeve and the inner peripheral surface of the through hole.   The horizontal die casting mold for supplying molten metal from the side, wherein the contact area between the upper part of the injection sleeve and the fixed mold is smaller than the contact area between the lower part of the injection sleeve and the fixed mold. Die casting mold.

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