JP4520448B2 - Casting part manufacturing apparatus and manufacturing method - Google Patents

Description

  The present invention relates to an apparatus and a method for manufacturing a cast part such as a bracket of a DC brushless motor, for example.

  For example, a cylindrical part made of aluminum or aluminum alloy is used for a bracket (stator housing) of a DC brushless motor. The bracket is cast by an aluminum die casting method in which a molten metal melt (aluminum melt or aluminum alloy melt) is pressure-fed to a closed mold using a high-speed injection molding machine. The molded casting is separated into a product part and an unnecessary part, finished and cut, and assembled into a motor as a part.

  The mold has a fixed mold and a movable mold, and the movable mold moves in the horizontal direction with respect to the fixed mold, and the mold is opened and closed. Each of the fixed mold and the movable mold is provided with an insert block, and the insert block is formed with a cavity filled with a molten metal, a runner and a gate (gate) communicating with the cavity. When the molten metal is injected into the mold, it is trapped in the runner gate engraved in the mold, the air present in the cavity, or the gas generated by the reaction between the molten metal and the mold release agent, and is confined in the end part that forms the bag path End up. For this reason, a technique has been proposed in which air or gas mixed in the molten metal is released to the outside through a gap between the mold parting surface and the mold dividing surface (see Patent Documents 1 and 2).

Further, since the molten metal is cooled while being filled to the end in the cavity and the fluidity is lowered, the filling property to the end molding portion which becomes the bag path is lowered. For this reason, the mold parting surface is provided with an air vent or an oil reservoir pocket (portion for accumulating the molten metal), and the molten metal overflows (overflows) from the cavity.
Japanese Patent Laid-Open No. 04-2157055 JP 2002-178125 A

However, since the spout, air vent, and puddle pocket are formed on the mold parting surface, the molten metal is filled in the puddle pocket first in the case of castings with complicated shapes such as shafts and cylinders. If the upstream side is blocked, air or gas is trapped at the end side in the cavity and there is no escape. Therefore, a void is easily generated in the terminal molded portion of the cast product.
Moreover, when the cooled molten metal enters the product shape, the fluidity is lowered and unfilled portions are easily generated.

  The present invention has been made to solve these problems, and an object of the present invention is to provide an apparatus and a method for manufacturing a cast part which has no cast hole or unfilled portion in the molded product and has improved molding quality. There is to do.

In order to achieve the above object, the present invention comprises the following arrangement.
An apparatus for manufacturing a cast part that presses a molten metal into a mold and manufactures a cast part, wherein the first center is formed at the center of the cavity bottom on the downstream side away from the pouring gate into which the molten metal of the first insert block flows. A fixed mold having a projecting pin, and a movable mold having a second center pin projecting at the center of the cavity bottom on the upstream side near the gate into which the molten metal of the second insert block flows . on at least one side end surface of the second center pin, a concave portion surrounded by the slit and ridges formed in the ridge portion and the ridge portion of the annular are respectively formed, the clamps the mold A cavity space portion formed between the end faces of the first center pin and the second center pin and communicating with the inside and outside of the pin through a slit is formed from the gate to the outside of the first and second center pins. The filled molten metal, characterized in that overflowing to pin the cavity space through the slit.
The first, the both end surfaces of the second center pin, a first annular, second protrusions and the first, the slits each formed radially in second protrusions, the first The first and second center pins are formed so that the first and second recesses surrounded by the second protrusions are formed, and the mold is clamped so that the first and second recesses face each other. A cavity space portion that is in contact with each other and is communicated with the inside and outside of the pin through a slit is formed .

Further, in the casting part manufacturing method, the mold is clamped, and the first center pin projecting at the center of the bottom of the cavity on the downstream side away from the pouring gate into which the molten metal flows, and the upstream near the pouring gate into which the molten metal flows. A second center pin projecting at the center of the cavity bottom of the side and contacting the cavity space formed inside and outside the pin by abutting the end faces, and the molten metal through the runner formed in the mold From the mold to the cavity, filling the cavity space formed outside the first and second center pins and then overflowing into the cavity space inside the pin through the slit, and taking out from the mold opened It includes a trimming process for removing unnecessary metal portions formed inside and outside the molded product.
The first air and gas distally mixed in the cavity which molten metal is filled, the pins in the portion of the molten metal as well as discharge led to the mold parting surface through the gap of the second center pin and the insert block It is characterized by overflowing the cavity space and filling the cavity with molten metal.

  If the above-described casting part manufacturing apparatus and manufacturing method are used, at least one side end face of the first and second center pins is formed with an annular ridge and a recess surrounded by the ridge. The first and second center pins whose end faces are abutted by clamping the mold are communicated with the cavity space formed inside and outside the pin through the slit formed in the protrusion. Yes. Therefore, when the molten metal is injected into the clamped mold and pressed into the cavity, the molten metal is filled from the periphery of the first and second center pins and filled to the end of the cavity, and finally the slit. Overflows through and fills the space inside the pin. Further, the gas entrapped on the end side in the cavity filled with the molten metal is led to the mold dividing surface through the gap between the first and second center pins and the insert block and discharged. The hot water pool portion formed between the end surfaces of the first and second center pins is a portion that does not become a product, and therefore does not affect the molding quality. Therefore, air or gas mixed in the molten metal does not remain in the product, and it is possible to provide a high-quality precision cast part having no casting hole or unfilled portion.

  In addition, annular first and second protrusions are formed on both end surfaces of the first and second center pins, respectively, and the first and second recesses are formed in portions surrounded by the protrusions. The first and second center pins, which are formed and clamped by the mold and faced with each other so that the first and second recesses face each other, are located on the first and second protrusions. The space inside and outside the pin communicates with each other through the formed slit. As a result, the molten metal overflowed from the cavity is filled into the space formed by the first and second recesses in the pin facing each other. In this case, since the volume of the hot water reservoir formed by the first and second recesses can be increased, the molten metal can be reliably overflowed to stabilize the molding quality of the cast product.

  BEST MODE FOR CARRYING OUT THE INVENTION The best embodiment of a casting part manufacturing apparatus and manufacturing method according to the present invention will be described below in detail with reference to the accompanying drawings. In the present embodiment, a bracket of a DC brushless motor will be described as an example of a cast part.

First, a schematic configuration of a casting part manufacturing apparatus will be described with reference to FIG.
A casting part manufacturing apparatus manufactures a casting part by using a die casting method in which aluminum or an aluminum alloy is melted and a molten metal is pressure-fed to a molding die 1 by an injection apparatus including a screw (not shown).

  In FIG. 1A and FIG. 1B, the fixed mold | type 2 has the 1st insert block 6 provided in the fixed base block 3 in the nested form. The fixed base block 3 is formed with an injection port 4 and a metal hot water channel 5 through which molten metal is injected from an injection device (not shown). The first insert block 6 is provided with a cavity (mold recess) 7 that defines the outer shape of the cast part. A first center pin 8 projects from the center of the bottom of the cavity 7. The first center pin 8 is fixed to the fixed base block 3.

1A and 1C, the movable die 9 has a movable base block 10 and a second insert block 11 provided in a nested manner. In the movable base block 10, a runner 12, a gate (gate) 13, and a cavity (mold recess) 14 that are continuous with the metal runway 5 are formed.
A second center pin 15 protrudes from the cavity center of the second insert block 11. When the mold is closed, the second center pin 15 enters the cavity 7 facing the tip, and the first center pin 8 and the end surfaces are abutted against each other. The second center pin 15 is fixed to the movable base block 10. The cavities 7 and 14 are formed according to the shape of the molded product, and may be formed in any one of the first and second insert blocks 6 and 11.

  Further, in FIG. 1C, a hot water pool pocket (a portion for accumulating the molten metal) 16 is provided around the cavity 14 and part of the runner 12. An air vent 17 communicates with the hot water pocket 16, and the air vent 17 is formed up to the mold dividing surface of the second insert block 11 and the base block 10. Air or gas mixed in the molten metal is allowed to escape from the air vent 17 to the outside through a gap formed on the mold dividing surface.

  Here, the shape of the first and second center pins 8 and 15 will be described with reference to FIGS. On at least one side end surface of the first and second center pins 8 and 15, a concave portion is formed in an annular ridge portion and a portion surrounded by the ridge portion. In addition, the first and second center pins 8 and 15 that are clamped by the mold 1 and abutted against each other are communicated with a space formed inside and outside the pin through a slit formed in the protrusion. It has become.

  4A and 5A, annular first and second protrusions 18 and 19 are formed on both end surfaces of the first and second center pins 8 and 15, respectively. 4B and 5B, first and second recesses 20 and 21 are formed in portions surrounded by the first and second protrusions 18 and 19, respectively. 4A and 5A, slits (dents) 22 and 23 are formed radially at a plurality of locations on the first and second protrusions 18 and 19.

In FIG. 2ABC, when the mold 1 is clamped, the end surfaces (first and second protrusions 18, 19) are abutted so that the first and second recesses 20, 21 face each other. The first and second center pins 8 and 15 communicate with the space inside and outside the pins through slits 22 and 23 formed in the first and second protrusions 18 and 19, respectively.
In the above-described embodiment, the first and second recesses 20 and 21 are provided on both end surfaces of the first and second center pins 8 and 15, but either one, preferably the first center pin 8 is provided. What is necessary is just to provide the recessed part in the side. The protrusion and the slit may be provided on any end face.

Next, the manufacturing process of a cast part will be described with reference to FIGS.
First, in FIG. 1A, the mold 1 is clamped and the first center pin 8 projecting from the cavity center of the first insert block 6 and the second center projecting from the cavity center of the second insert block 11 are shown. The center pin 15 is inserted into the opposite cavity 7 and the space (cavity 7 and the first and second recesses 20 and 21) formed inside and outside the pin is communicated with each other through the slits 22 and 23 so that the end faces are projected. Hit it.

  Next, the molten metal is pressure-fed to the cavities 7 and 14 through the runner 12 and the spout 13 formed in the mold 1, and the molten metal is transferred to the space formed inside and outside the first and second center pins 8 and 15. Fill. At this time, in FIG. 2A, the molten metal is filled from the periphery of the first and second center pins 8 and 15 and filled to the end of the cavity, and then overflows through the slits 22 and 23 to finally reach the cavity space in the pin. Filled into the part. The cavity space (bath pool) formed between the end surfaces of the first and second center pins 8 and 15 is a portion that does not become a product, and therefore does not affect the molding quality.

  Further, the molten metal overflowed from the cavities 7 and 14 is accommodated in the hot water pool pocket 16, and air and gas are vented through the air vent 17. Air or gas that has entered the first and second recesses 20 and 21 passes through the gap between the first and second center pins 8 and 15 and the first and second insert blocks 6 and 11 and the gap between the mold dividing surfaces. Discharged.

  3A and 3B show the molded product 24 after molding. In addition to the product (bracket), an unnecessary metal portion is integrally formed in the molded product 24 after molding. The molded product 24 is released from the molding die 1 by ejecting an unillustrated ejector pin into the cavity, and unnecessary metal portions 26a and 26b formed inside and outside the molded product 24 are removed (trimming step). ).

  FIG. 3C shows a state where the metal portion 26a connected to the outside of the cast part 25 is removed. In the cylindrical body of the cast part 25, the overflowed metal portion 26 b is formed in the portions corresponding to the slits 22 and 23 and the first and second concave portions 20 and 21 facing each other. The metal portion 26 b corresponds to a terminal portion where the molten metal is filled in the cavity 7. Even if a cast hole is generated in the metal portion 26, it is a portion to be removed, so there is no influence on the product.

  In the above-described embodiment, the bracket of the DC brushless motor is illustrated. However, the cast part is not limited to this, and the present invention can be applied to parts having other complicated shapes.

It is a front view of a shaping | molding die, and explanatory drawing of the clamp surface of a fixed mold | type and a movable mold | type. It is state explanatory drawing before and after the abutting of the 1st, 2nd center pin. It is the front view of a molded article, the left view, and explanatory drawing of the product separated into pieces. It is an end view and a partial sectional view of the first center pin. It is the end view and the fragmentary sectional view of the 2nd center pin.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Fixed mold 3 Fixed base block 4 Injection port 5 Metal runner 6 First insert block 7, 14 Cavity
8 First center pin
9 Movable type
10 Movable base block
11 Second insert block
12 Lanna
13 Yuguchi
15 Second center pin
16 Hot water pocket
17 Air Vent
18 First ridge
19 Second ridge
20 first recess
21 Second recess
22, 23 Slit
24 Molded products
25 Casting parts 26 Metal parts

Claims (4)

A casting part manufacturing apparatus for manufacturing a cast part by pressure feeding a molten metal to a mold,
A fixed mold in which a first center pin protrudes at the center of the cavity bottom on the downstream side away from the gate into which the molten metal of the first insert block flows ;
A movable mold having a second center pin protruding from the center of the cavity bottom on the upstream side near the gate into which the molten metal of the second insert block flows ;
First, on at least one side end surface of the second center pin, a concave portion surrounded by the slit and ridges formed in the ridge portion and the ridge portion of the annular are respectively formed, the mold Cavity is formed by abutting the end surfaces of the first and second center pins to form a cavity space that communicates with the inside and outside of the pin through a slit, and is formed from the gate to the outside of the first and second center pins. An apparatus for manufacturing a cast part that causes the molten metal filled in the space to overflow into the cavity space inside the pin through the slit . First, both of the end face of the second center pin, a first annular, second protrusions and the first, the slits each formed radially in second protrusions, the first, second End surfaces of the first and second center pins are formed so that the first and second recesses surrounded by the two protrusions are formed and the mold is clamped so that the first and second recesses face each other. The casting part manufacturing apparatus according to claim 1, wherein a cavity space portion is formed in which the spaces are abutted to communicate with each other through a slit inside and outside the pin . The mold was clamped and protruded at the center of the cavity bottom on the upstream side close to the first center pin and the bottom of the cavity where the molten metal flows in, with the first center pin protruding from the center of the cavity at the downstream side away from the gate where the molten metal flows in . Contacting the cavity space formed inside and outside the pin by abutting the end faces with the second center pin;
The molten metal is pressure-fed from the gate to the cavity through the runner formed in the molding die, filled into the cavity space formed outside the first and second center pins, and then into the cavity space inside the pin through the slit. An overflow process;
A casting part manufacturing method including a trimming step of removing unnecessary metal portions formed inside and outside of a molded product taken out of a mold that has been opened. The air or gas molten metal is mixed in terminal side of the cavity to be filled first, cavity of the pin in the portion of the molten metal as well as discharge led to the mold parting surface through the gap of the second center pin and the insert block The method of manufacturing a cast part according to claim 3, wherein the molten metal is filled into the cavity by overflowing the part.

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