JP2001225160A - Die for die casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent the occurrence of flaw and deformation on the front end of a core and wall surfaces facing the same of a die having the core projecting into a cavity. SOLUTION: The cavity is constituted between the stationary die 12 and the moving die 13 in the die clamping state of the die consisting of these dies. The moving die 13 is provided with the columnar core 45 which projects to the stationary die 12 side and is used to form the hollow part of a cylindrical part of a casting. At this time, the core 45 is constituted to have a size longer than the length size of the hollow part, i.e., to have an extra length at a front end 45b. The front end 45b of the core 45 is formed to a spherical shape. On the other hand, an insertion hole 51 to be inserted with the front end 45b of the core 45 is formed at a sufficient depth size at the stationary die 12. The front end 45b of the core 45 is inserted into the insertion hole 51 by having a slight spacing (about 0.05 mm over the entire circumference) from the inner peripheral surface of the insertion hole 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting mold having a cavity corresponding to the outer shape of a casting, and having a core projecting into the cavity and forming a through hole in the casting. .

[0002]

As a cast product manufactured by die casting, there is a switching operation body 1 used in a transmission gear device (transmission) as shown in FIGS. 11 and 12, for example. The switching operation body 1 integrally includes a main portion 2 having a substantially arc-shaped plate shape and a cylindrical portion 3 having a cylindrical shape extending and penetrating in a direction perpendicular to the main portion 2 (the left-right direction in FIG. 11). In preparation. Further, a circular hole 4 is formed in the main part 2, and a small hole 5 for screw insertion is formed in the cylindrical part 3 so as to penetrate in a vertical direction. As shown in FIG. 11, the cylindrical portion 3 is fixed by screws or the like through the small holes 5 in a state of being inserted into the shaft a, and the circular hole 4 is slidable on the guide shaft b. Is to be inserted.

In general, in die casting, a molten metal such as aluminum is injected and filled into a cavity formed between a fixed mold and a movable mold in a mold-clamped state. The product is taken out by opening the mold. In this case, when manufacturing a casting having the above-described cylindrical portion 3, the mold clamping and mold opening directions are made to coincide with the axial direction of the cylindrical portion 3, and, for example, the cylinder is moved to the movable mold side. A cylindrical (round bar) core corresponding to the hollow portion (through hole) 3a of the protruding portion 3 is provided so as to protrude into the cavity. It comes into contact with the wall surface.

[0004] However, in the case of the above, the length of the core changes due to thermal expansion.
At the time of mold clamping, the tip of the core and the opposing wall of the mold make strong contact with each other, and the tip and the wall of the core may be damaged or deformed. There was a disadvantage that it became shorter.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a core having a core projecting into a cavity. It is an object of the present invention to provide a die casting mold capable of effectively preventing the die casting.

[0006]

SUMMARY OF THE INVENTION A die casting mold of the present invention has a cavity corresponding to the outer shape of a casting, and projects into the cavity to form a core for forming a through hole in the casting. Wherein the core is configured to have an excess length at its distal end, and the portion for receiving the distal end of the core is deeper than the insertion length of the distal end of the core. The present invention is characterized in that an insertion hole having a size that forms a small gap with the outer periphery of the core is provided (the invention of claim 1).

[0007] According to this, the core projecting into the cavity in the mold clamped state has its tip end inserted into the insertion hole. At this time, the insertion hole is deeper than the insertion length of the tip of the core and has a size that forms a slight gap between the outer periphery of the core and the length thereof changes due to thermal expansion. Even if it does, it will not hit the wall of the cavity. As a result, it is possible to prevent the tip of the core and the wall surface facing the tip from being damaged or deformed.

By the way, the temperature of the core rises due to the heat of the molten metal at the time of casting. In order to prevent seizure or welding, it is desirable that heat is effectively radiated from the core. At this time, a heat radiation space is formed between the distal end portion of the core and the insertion hole, and the heat radiation effect from the distal end portion of the core can be enhanced. At this time,
If the tip of the core is formed in a spherical shape (the invention of claim 2), the surface area can be increased to further enhance the heat radiation effect. By making the distal end portion spherical, there is also an effect that insertion into the insertion hole is performed smoothly.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to casting of a switching operation body used in a transmission (transmission) will be described below with reference to the drawings.

First, FIGS. 11 and 12 show the structure of a switching operation body 1 which is a cast product in this embodiment. The switching operation body 1 is made of, for example, an aluminum alloy, and has a substantially arc-shaped main part 2 and a main part 2.
And a cylindrical portion 3 having a straight pipe shape extending in a direction perpendicular to both sides (the left-right direction in FIG. 11). Therefore, the cylindrical portion 3 has a hollow portion 3a whose both ends are open and whose axis extends in the left-right direction. A circular hole 4 is formed in the main part 2.

Further, a small hole 5 for screw insertion is formed in a left portion of the cylindrical portion 3 in FIG. 11 so as to penetrate in a direction intersecting with the axis of the hollow portion 3a, in this case, perpendicularly to the vertical direction. Is formed. As shown in FIG. 11, the cylindrical portion 3 is fixed by screws or the like through the small holes 5 in a state of being inserted into the shaft a, and the circular hole 4 is slidable on the guide shaft b. Is to be inserted.

Next, the structure of the die casting apparatus 6 for casting the switching operation body 1 will be described below. FIG. 4 schematically shows the entire appearance of the die casting apparatus 6 according to the present embodiment.
Is roughly composed of a mold device 7 for performing casting, and an injection mechanism 8 for injecting and filling the mold device 7 with a molten metal.

In the mold apparatus 7, a fixed plate 10 is provided on the base 9 at the right end in the figure, and the movable plate 11 is moved in the contact / separation direction (left-right direction) facing the left side thereof. It is configured to be provided as possible. As will be described later in detail, the fixed die 12 provided on the fixed platen 10 and the movable die 13 provided on the movable platen 11 constitute a mold 14 according to the present embodiment. The movable platen 11 (movable mold 13) is moved by a mold drive mechanism 17 including a cylinder 15, a toggle link mechanism 16, and the like, so that mold clamping and mold opening are performed. The mold device 7 is also provided with a spray device (not shown) for spray-coating the mold 14 with the mold release agent.

On the other hand, as shown in FIG. 5, the injection mechanism 8 has an injection sleeve 19 whose tip is connected to a casting port 18 at the lower end of the fixed die 12 and extends rightward. Plunger 2 that moves forward and backward while sliding
0 and a drive unit (not shown) for reciprocating the plunger 20 at a variable speed. As shown in FIG. 4, a molten metal holding furnace 21 for holding a molten metal (aluminum alloy) at a substantially constant temperature (for example, 730 ° C.) is provided, and the molten metal in the molten metal holding furnace 21 is supplied to the injection sleeve. An automatic hot water supply device 22 is provided which pours a predetermined amount from the hot water supply port 19a (see FIG. 5) into the inside.

Here, the structure of the mold 14 will be described in detail with reference to FIGS. 1 to 3 and FIGS. FIG. 6 shows a longitudinal section along a substantially center line (line AA in FIG. 7) in the front-rear direction when the mold 14 is clamped. As shown in FIG. 7, the fixed mold 12 is fitted with a mold 24 made of a material having a predetermined strength and thermal stress or the like in a central rectangular recess of a base 23 having a rectangular block shape. It is fixed and configured. On the other hand, as shown in FIG. 8, the movable mold 13 is also formed by fitting and fixing a similar mold member 26 into a rectangular recess at the center of a base 25 having a rectangular block shape.

In the clamped state of the mold 14, a cavity 27 corresponding to the outer shape of the cast product (the switching operation body 1) is formed between the mold material 24 and the mold material 26, and is formed in the cavity 27. A runner 28 for guiding the molten metal is formed to extend vertically. A gate 28a is formed at the tip (upper end) of the runner 28. In this case, the cavity 27 is provided so that the switching operation body 1 has a parting surface divided into right and left by a center line in the thickness direction of the main part 2 (center line L shown in FIG. 11).
Details of the cavity 27 and the runner 28 will be described later.

The base 23 of the fixed mold 12 has
A circular through hole is formed below the mold member 24 and penetrates in the left-right direction, and a substantially cylindrical casting port bush 29 is fitted into the through hole. This casting port bush 2
The right end of 9 is a casting port 18 as also shown in FIG. The inner peripheral wall of the casting port bush 29 is formed in a tapered shape in which the right half in the drawing has a straight tubular shape and the left half has a diameter gradually increasing toward the left.

On the other hand, the base 25 of the movable mold 13 is provided with a shunt 30 located below the mold 24. The shunt 30 is formed in a tapered cylindrical shape so that the tip side projects rightward from the parting surface.
In the mold clamping state of the mold 14, the tip of the shunt 30 is inserted into almost half of the casting port bush 29, so that the hot water flows between the casting port bush 29 and the inner peripheral wall on the upper side. A thin molten metal guide groove 31 connected to the road 28 is formed.

In this state, when the mold 14 is clamped, the molten metal is supplied into the injection sleeve 19 of the injection mechanism 8, and the plunger 20 is advanced leftward. Is extruded from the casting port 18 into the large-diameter hollow portion in the right half of the casting port bush 29, and further passes through the molten metal guide groove 31 and the runner 28 in order, and is injected into the cavity 27 from the gate 28a. It is to be done. At this time, the distal end of the plunger 20 is advanced to a position close to the distal end of the splitter 30 with a slight gap therebetween. A biscuit e in which the molten metal is hardened is formed between the tip of the child 30.

Further, as shown in FIG. 7, the fixed die 12 is provided with four guide posts 32 which are located at the four corners of the base 23 and project leftward from the surface thereof. Further, the fixed mold 12 is provided with circulation paths 33 vertically circulating a fluid for adjusting the temperature of the mold 24 so as to penetrate both the base 23 and the mold 24 in the front-rear direction. Although not shown in detail, the fixed die 12 is provided with an extruding device 34 (only a part is shown in FIG. 6) including a plurality of extruding pins for extruding a cast product and a mechanism for driving the extruding pins. I have. In addition, the suction port 35 is formed in the base 23 so as to be located at two places and open to the surface.

On the other hand, as shown in FIG. 8, the base 23 of the movable die 13 is formed with four guide holes 36 which are inserted and slid into the respective guide posts 32 and are movable. Are guided by the guide posts 32 so as to be parallel to and away from the fixed mold 12. The movable die 13 is also provided with upper and lower two circulation paths 37 through which a fluid for adjusting the temperature of the mold member 24 circulates. Further, a cooling water circulation path 38 (see FIG. 6) is provided.

Although not shown, the circulation path 33, the circulation path 37, and the cooling water circulation path 38 are connected to a temperature control device via a pipe or the like so that a fluid having an appropriate temperature is circulated. I have. The temperature adjusting device adjusts the temperature of the mold members 24 and 26 to delay the solidification and shrinkage of the molten metal filled in the cavity 27, and adjusts the temperature of the shunt 30 to adjust the temperature. The biscuit e is brought into a semi-solid state at the same time as or slightly after the product.

As shown only partially in FIG. 6, the movable die 13 also includes an extrusion device 39 including a plurality of extrusion pins 39a for extruding a casting and a mechanism for driving the extrusion pins 39a. Is provided. As described below,
The extruding device 39 allows the semi-solidified cast product to escape from the core, so that the extruding device 39 functions as an escape mechanism. in this case,
The extrusion pin 39a is provided so as to extrude even a metal (so-called runner residue) hardened (semi-solidified) in the runner 28, the molten metal guide groove 31, and the like.

Now, the cavity 27 and the runner 28 will be described in detail. First, the mold 24 of the fixed mold 12
As shown in FIG. 7, a substantially arc-shaped chase 40 corresponding to the right half of the cast product (switching operation body 1) is recessed in the surface portion of FIG. Further, the chase 40 has a circular convex portion 40a for forming the circular hole 4 of the switching operation body 1, and also has a right half of the cylindrical portion 3 as shown in FIG. A circular hole 40b corresponding to the outer shape is formed. As shown in FIG. 9, a land 41 for forming a half part of the gate 28a is formed in an arc shape along the center of the lower edge of the chase 40 on the surface of the mold member 24. Have been.

On the other hand, as shown in FIG. 8, the surface of the mold member 26 of the movable die 13 corresponds to the left half of the cast product (switching operation body 1). A substantially arc-shaped chase 42 that forms the cavity 27 is recessed. A runner 28 having a lower end continuously extending upward from the melt guide groove 31 and an upper end serving as a gate 28 a connected to the chase 42 is formed in the mold member 26. The runner 28 has a form in which its upper end is fanned upward (injection angle θ), and as shown in FIGS. 6 and 9, the upper part has a shallow bottom toward the spout 28a. An inclined feed 28b is formed.

Further, as shown in FIG.
The gas vent holes 43a at both ends of the chase 42
, Two gas vent paths 43 for discharging air (or gas) in the cavity 27 are formed.
These gas vent paths 43 extend from the mold 26 to the base 25, and as shown in FIG. 10, the base ends of the gas vents 43 are connected to the suction ports 35 of the fixed mold 12 in a state where the mold 14 is clamped. It has become. The base end of the suction port 35 is connected to a pressure reducing device (not shown).

When the pressure reducing device is driven while the mold 14 is being clamped, the air (gas) in the cavity 27 passes from the gas vent 43 a through the gas vent 43 and further passes through the suction port 35. Through to the outside. At this time, a basin 44 is formed in the middle of the gas venting path 43 (near the gas venting port 43) to allow the molten metal overflowing from the inside of the cavity 27 to escape.

As shown in FIGS. 1 to 3, the chase 42 has a circular hole 42 a corresponding to the outer shape of the left half of the cylindrical portion 3. A cylindrical core 45 projecting rightward (toward the fixed die 12), which is the direction in which the cast product is removed, from the bottom of the cylindrical portion 3 to form the entire hollow portion 3a of the cylindrical portion 3 is provided. At this time, the core 45 is configured to be longer than the length of the cylindrical portion 3 (hollow portion 3a), that is, the core 45 is configured to have an excess length at the distal end portion 45b. Furthermore, this core 45
Is formed in a spherical shape. In the present embodiment, the core 45 has a uniform outer diameter having no draft except for the distal end portion 45b, and its outer peripheral surface is mirror-finished, so that a cylinder of a cast product is formed. Hollow part 3 of shape part 3
The surface state is transferred to a.

On the other hand, as shown in FIGS. 1 and 3, the end portion 45 b of the core 45 is attached to the mold 24 of the fixed mold 12 so as to be continuous from the bottom of the circular hole 40 b of the chase 40. An insertion hole 51 into which is inserted.
As shown in FIG. 3, when the mold 14 is clamped, the core 4
The distal end portion 45b of the fifth insertion hole 51 is inserted with an extremely small gap (for example, about 0.05 mm over the entire circumference) between the front end portion 45b and the inner peripheral surface of the insertion hole 51. In this case, the insertion hole 51 is formed sufficiently deeper than the insertion length of the distal end portion 45b of the core 45. It is desirable that the insertion amount of the core 45 into the insertion hole 51 of the straight portion be 2 mm or more.

At this time, as shown in FIG. 1 and FIG. 2, a part of the core 45 extends in the axial direction of the small hole 5,
A fitting hole 45a through which a core pin 46 for forming a small hole 5 described later penetrates is formed. The relationship between the outer diameter of the core 45 and the inner diameter of the hollow portion 3a of the tubular portion 3 is as shown in FIG. Further, in the present embodiment, as shown in FIG. 8, the core 45 is located at a position deviated from an imaginary line extending into the cavity 27 of the runner 28, that is, the gate 2
The cavity 27 is formed so as to be located outside the injection angle θ of the molten metal from 8a.

Further, the movable die 13 is provided with a core pin 46 as a core for forming the small hole 5 as follows. That is, as shown in FIG. 1, FIG. 2 and FIG.
A sliding recess 25a extending upward from the center of the mold member 26 and being slightly leftward is formed in the base 25 of the third member 3, and a sliding body 47 is slidably provided in the sliding recess 25a in the vertical direction. . The core pin 46 has a long round bar shape having a uniform outer diameter and no draft, and is provided on the sliding body 47 so as to protrude downward. The surface of the core pin 46 is also mirror-finished. The relationship between the outer diameter of the core pin 46 and the inner diameter of the small hole 5 formed in the cylindrical portion 3 is as shown in FIG. Although not shown, the core 45 has a length of 60 mm.

At this time, the mold member 26 includes the core 4
5 extends upward along the extension of the fitting hole 45a of FIG.
a is formed, and the tip of the core pin 46 is inserted through the through hole 26a. At this time, as shown in FIG. 13, the tip of the core pin 46 has a so-called chamfered form. As shown in FIGS. 1 and 2, the lower end of the inner peripheral wall of the circular hole 42 a of the chase 42 of the mold 26 is located below the extension of the fitting hole 45 a and is located at the tip of the core pin 46. Is formed with a fitting hole 42b into which the is fitted. As shown in FIG. 13, this fitting hole 42b
Is provided in such a form that its opening part expands in a tapered shape.

As shown in FIG. 1, the core pin 46 projects into the cavity 27 through the through hole 26a in the state where the sliding member 47 is located at the lower end of the sliding recess 25a, and the fitting pin 46 The distal end penetrates through the hole 45a and is located at a protruding position in which the distal end is inserted into the insertion hole 42b. On the other hand, when the sliding body 47 is moved to the upper part of the sliding recess 25a, the core pin 46 is retracted from the cavity 27 as shown in FIG. It is designed to be moved to the immersion position.

As shown in FIGS. 1 and 8, an upwardly extending bar 48 is provided above the sliding member 47, and this bar 48 is urged upward by a spring 49 at the upper end of the movable die 13. It is supported in the state where it was done. With this,
As shown also in FIG.
A guide hole 47a which is inclined downward (to the right) is formed therethrough. On the other hand, the fixed pin 12 has a guide pin 50 which is inclined upward to the left corresponding to the guide hole 47a. Are provided to protrude toward the movable mold 13 side.

As shown in FIG. 2, the guide pin 50 is separated from the guide hole 47a of the sliding member 47 when the mold 14 is opened, so that the core pin 46 is located at the retracted position. On the other hand, when the movable mold 13 is moved in a direction in which the movable mold 13 comes into contact with the fixed mold 12, the guide pins 50 are relatively inserted into the guide holes 47a. Moves downward against the force of the spring 39. And, as shown in FIG.
When the mold 14 is clamped, the core pin 46 is positioned at the projecting position. Therefore, the guide hole 47a
A moving mechanism for moving the core pin 46 between the protruding position and the retracted position from the guide pin 50 and the like is configured.

Next, a casting method for casting the switching operation body 1 using the die casting apparatus 6 having the above-described structure will be described with reference to FIG.
5 and FIG. FIG. 15 shows the casting conditions in this embodiment, and FIG. 16 shows the relationship between the casting process of one cycle and the operation of each device in this embodiment. As shown in FIG.
Is performed through the following six steps.

That is, first, in the first step, with the mold 14 in the mold open state, the spray device is operated to activate the core 4 of the mold 14.
The mold release agent is spray-coated on the cavity 27 including the core pin 5 and the core pin 46, the runner 28, and the like. With respect to the core pin 46, a release agent is applied to a portion exposed from the mold 26. At this time, since the movable mold 13 is separated from the fixed mold 12, the core pin 46 is located at the immersion position as shown in FIG. The temperature control device is continuously operated from the first step to the sixth step, and the mold 14 is controlled to a predetermined temperature.

In the next second step, the mold driving mechanism 17 clamps the mold 14. By this mold clamping, FIG.
As shown in the figure, the movable mold 13 is joined to the fixed mold 12, and the cavity 27, the runner 28 and the molten metal guide groove 3 are interposed therebetween.
1 and the like are formed. At this time, as shown in FIG. 1, the core 45 provided on the movable mold 13 side is
Of the cylindrical portion 3
Is formed.

The distal end 45b of the core 45 is inserted into the continuous insertion hole 51 from the bottom surface of the circular hole 40. The insertion is smooth because the distal end 45b has a spherical shape. Done. Further, since the insertion hole 51 is formed deep, the tip 45b of the core 45 does not abut against the bottom of the insertion hole 51.
A heat radiation space is formed therein.

At the same time, due to the action of the guide hole 47a and the guide pin 50, the core pin 46 moves downward, protrudes into the cavity 27 through the through hole 26a, and penetrates the fitting hole 45a so that the tip ends. The core pin 46 is moved to a position where the fitting hole 42b is fitted, and the core pin 46 is located at a position corresponding to the small hole 5.

Subsequently, in the third step, while the mold 14 is being clamped, the pressure reducing device is operated to suck air (gas) in the cavity 27 to be in a negative pressure state. Is injected into the mold 14 from the injection sleeve 19 through the casting port 18. Thus, the molten metal is injected and filled into the cavity 27 from the gate 28a through the molten metal guide groove 31 and the runner 28 in this order. At this time, since the interior of the cavity 27 is in a negative pressure state, the molten metal to be filled can run well. In addition, the metal melt is filled slightly excessively, but the surplus can be discharged to the well 44. Moreover,
Although a small gap is formed between the core 45 and the insertion hole 51, the molten metal hardly penetrates into the gap, and the generation of burrs and the like can be almost eliminated.

At this time, there is a situation where the molten metal is injected into the cavity 27 in a torrent like a waterfall. In this case, as shown in FIG. 8, the core 45 (and the core pin 46) is used. ) Is located outside the imaginary line extending into the cavity 27 of the runner 28, so that the molten metal injected into the cavity 27 from the gate 28 a does not directly hit the core 45 and the core pin 46. Instead, it comes into contact with the inner wall of the cavity 27 and is dispersed and then filled. Thereby, an excessive rise in temperature of the core 45 and the core pin 46 can be prevented. The plunger 20 of the injection mechanism 8 advances in the pouring bush 29 to a position shown by a two-dot chain line in FIG. 6, but is held at that position at least until the molten metal is in a semi-solid state. become.

When the filling of the molten metal into the cavity 27 is completed, the temperature of the molten metal in the cavity 27 starts to decrease. In the next fourth step, while keeping the mold 14 in the clamped state, This is a step of waiting for the molten metal to be in a semi-solid state. More specifically, the semi-solidified state of the molten metal is a state in which the molten metal in the cavity 27 is in a solidified state on the surface thereof but is still a molten material in the inside (gel state), and is solidified and contracted. Before starting. The term “melt” as used herein refers to a state like rice cake, or a state like pudding or tofu when its hardness is sensuously expressed. In this embodiment, the temperature adjusting device
This semi-solid state is made to last relatively long.

When the molten metal in the cavity 27 is in a semi-solid state, in the next fifth step, the mold 14 is opened by the mold driving mechanism 17 and the extrusion device 34 on the fixed mold 12 side is driven. Become so. As a result, the semi-solidified cast product is released from the fixed die 12 integrally with the movable die 13, and the core pin 46 comes out of the cavity 27 by the movement of the movable die 13 to the immersion position. To move. At this time, the core pin 46 can be pulled out with little or no tightening force applied to the core pin 46 due to the shrinkage of the molten metal. In addition, a large stress does not act on the elongated core pin 46, and no trouble such as breakage occurs.

Subsequently, in the sixth step, when the molten metal (cast product) is in a semi-solid state, the extrusion device 39 of the movable mold 13 is moved.
Is driven, and the casting (the switching operation body 1) escapes from the core 45. Also at this time, the cast product can escape from the core 45 in a state where there is almost no generation of a tightening force on the core 45 due to the contraction of the molten metal, and even when the draft of the core 45 is zero, it can be smoothly performed. The casting can be released. At this time, the runner solidified in the runner 28 and the molten metal guide groove 31 and the biscuit e are also removed from the movable mold 13 and separated from the casting (the switching operation body 1).

The switching operation body 1 cast as described above
Has a cylindrical portion 3 having a hollow portion 3a integrally formed therein, and a small hole 5 is formed in the cylindrical portion 3 in advance. At this time, it is no longer necessary to provide the core 45 and the core pin 46 with a draft, so the hollow portion 3a of the tubular portion 3 is not required.
The dimensional accuracy with respect to the inner peripheral surface and the inner peripheral surface of the small hole 5 is also high, so that precise cutting or the like for obtaining subsequent dimensions can be omitted.

As described above, according to the present embodiment, the core 45 protruding into the cavity 27 is formed to be long, and the tip end portion 45 b is inserted into the insertion hole 51 while the mold 14 is clamped. With such a configuration, even if the length of the core 45 changes due to thermal expansion, it does not come into contact with the wall surface of the cavity 27. As a result, it is possible to effectively prevent the tip portion 45b of the core 45 and the wall surface of the cavity 27 opposed thereto from being damaged or deformed, and to extend the life of the core 45 and the like. is there.

In addition, the heat radiation effect of the core 45 can be enhanced by securing a heat radiation space in the insertion hole 51. In particular, the tip 45b of the core 45 is formed in a spherical shape. Accordingly, the heat radiation effect can be further enhanced by increasing the surface area, and the effect of preventing the heat accumulation phenomenon at the tip of the core 45 can also be obtained.

In the present embodiment, in particular, in manufacturing the cylindrical part 3 having the hollow part 3a and the casting (switching operation body 1) having the small hole 5 intersecting with the cylindrical part 3, the inside of the cavity 27 of the mold 14 is required. The core 45 for forming the hollow portion 3a having no draft is arranged, and the core pin 45 for forming the small hole 5 having no draft is provided while the mold 14 is clamped.
In a state of being inserted into the fitting hole 45a of the core 45, in a semi-solid state before solidification shrinkage of the molten metal,
The core pin 46 is withdrawn from the casting, and the casting is released from the core 45.

As a result, as shown in FIG. 14, the casting using the core 45 and the core pin 46 as shown in FIG. 14 results in a cast product having the hollow portion 3a and the small hole 5 of the product dimensions. Could be cast. That is, it is possible to form the cylindrical portion 3 having a regular size in the casting and also to form the small hole 5. This eliminates the need for precise cutting for obtaining dimensions, and also eliminates the need for complicated machining such as drilling after casting. Therefore, no post-processing is performed on the removed casting (the switching operation body 1) or the remaining gate is processed,
It is only necessary to apply a slight finishing to the extent that the appearance such as deburring is adjusted, and it is possible to significantly reduce the manufacturing cost.

Further, in the present embodiment, when the cavity 27 is formed in the mold 14, the core 45 and the core pin 46 are used.
Is configured so as to deviate from the injection angle θ of the molten metal from the gate 28a, so that an excessive rise in temperature of the core 45 and the core pin 46 due to the direct injection of the molten metal can be prevented. It is also possible to obtain the advantage that seizure, welding and the like can be prevented beforehand.

In the above embodiment, the draft of the core 45 and the core pin 46 is configured to be zero, but a draft may be provided. The same operation and effect can be obtained by providing an insertion hole in a portion of the cavity where the tip of the cavity faces. In addition, the present invention is not limited to the above-described embodiment. For example, the present invention is not limited to the switching operation body 1 as a cast product, and may be appropriately modified without departing from the gist, for example, the present invention can be applied to general die casting. It can be implemented.

[0053]

As is apparent from the above description, according to the die casting mold of the present invention, the core is provided with a core projecting into the cavity. A size that is deeper than the insertion length of the tip of the core and forms a slight gap between the core and the outer periphery of the core at the portion that receives the tip of the core of the cavity. Since the insertion hole is provided, there is an excellent effect that it is possible to effectively prevent occurrence of scratches and deformation on the tip portion of the core and the wall surface facing the tip portion.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, and is a longitudinal sectional front view of a mold in a mold-clamped state (a cross-sectional view along line BB in FIG. 8).

FIG. 2 is a longitudinal sectional front view of a movable mold in a mold open state (FIG. 8)
Cross-sectional view along the line BB)

FIG. 3 is an enlarged vertical sectional view of a core portion.

FIG. 4 is a schematic front view of the entire die casting apparatus.

FIG. 5 is a vertical sectional front view of an injection mechanism.

6 is a vertical sectional front view of the mold in a mold-clamped state (a cross-sectional view along line AA in FIG. 7).

FIG. 7 is a left side view of the fixed type.

FIG. 8 is a right side view of a movable mold.

FIG. 9 is an enlarged vertical sectional front view of a gate section.

FIG. 10 is an enlarged vertical sectional view of a suction port portion along the line CC in FIG. 8;

FIG. 11 is a front view of a switching operation body.

FIG. 12 is a longitudinal sectional side view of the switching operation body along the line DD in FIG. 11;

FIG. 13 is an enlarged view of a fitting hole portion.

FIG. 14 is a diagram showing a dimensional relationship of each part.

FIG. 15 is a view showing casting conditions.

FIG. 16 is a diagram showing the relationship between the process and the operation of each mechanism.

[Explanation of symbols]

In the drawing, 1 is a switching operating body (cast product), 3 is a cylindrical portion, 3a
Is a hollow part, 5 is a small hole, 6 is a die casting apparatus, 8 is an injection mechanism, 12 is a fixed type, 13 is a movable type, 14 is a mold, 1
7 is a mold driving mechanism, 27 is a cavity, 28 is a runner, 28
a is a gate, 39 is an extrusion device (escape mechanism), 45 is a core,
45a is a fitting hole, 45b is a tip, 46 is a core pin,
Reference numeral 1 denotes an insertion hole.

Claims (2)

[Claims] 1. A mold having a cavity corresponding to the outer shape of a casting, and having a core projecting into the cavity and forming a through hole in the casting, wherein the core is formed at a tip end thereof. In addition to having a surplus length, a portion of the cavity that receives the tip of the core is slightly deeper than the insertion length of the tip of the core and slightly between the outer periphery of the core. A die casting die having an insertion hole having a size to form a gap. 2. The die casting die according to claim 1, wherein a tip portion of said core is formed in a spherical shape.