JP2005161349A - Die casting molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a die cast product having little casting defect by pouring clean molten metal containing no solidified layer, oxidized film, etc., and little gas content into a cavity for product. <P>SOLUTION: A die casting molding method is is disclosed for performing casting by pouring the molten metal 30 injected from an injection sleeve 15 by shifting of an injection plunger 16 into the cavity for product in a die 6 through a runner 9 in the die 6. The die 6 is provided with a branching weir 17 at the circumference near the inlet 9a of the runner, a capturing cavity 18 around the branching weir 17 and an air-vent 20 communicating with the catching cavity 18. The molten metal 30 is branched into an impurity layer 30a and a clean layer 30b at the outer peripheral part by bumping the molten metal 30 injected from the injection sleeve 15 against the branching weir 17. The branched clean layer 30b is poured into the cavity for product through the runner 9, and the branched impurity layer 30a at the outer peripheral part is captured into the capturing cavity 18. Then, the gas collected in the capturing cavity 18 is exhausted externally through the air-vent 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a die casting method for casting aluminum or zinc alloy using a precise mold.

  In conventional die-casting, it is known that when gas containing mainly hydrogen or nitrogen is mixed in a die-cast product, the mechanical properties of the product deteriorate, or product defects such as blisters or casting holes occur. (For example, see Non-Patent Document 1).

  Here, the nitrogen gas is generated from the air remaining in the sleeve, the hot water pool, the runner and the cavity. On the other hand, a gas such as hydrogen is dissolved in the molten metal at the time of melting, and is generated in the middle of molding due to the mold release agent and dispersed and mixed in the molten metal due to the high pressure at the time of molding (for example, non (See Patent Document 2). The mold release agent is applied to the plunger, the sleeve, the mold and the like so that the molten metal does not adhere. In die-cast products with strict requirements for strength and pressure resistance, countermeasures against degassing treatment are taken in the melting furnace before molding for the gas that melts into the molten metal at the time of melting, but countermeasures are also desired for the gas generated in the molding process. ing. Of the countermeasures for the gas generated in the molding process, gas removal from the product cavity is performed as a technique mainly for countermeasures against air remaining in the product cavity (see, for example, Non-Patent Document 3).

  However, gas venting from the product cavity is not sufficient, and the gas dissolved in the high-temperature liquid cannot be dissolved rapidly due to cooling and solidification of the molten metal, and is also released from the molten metal of the stamp part and runner (for example, (See Patent Document 1).

  This released gas and the air remaining in the sleeve, the hot water pool, the runner, etc. are compressed by high pressure in the molding process, mixed into the molten metal and pumped into the product cavity, which is a cause of defects in the die cast product. Become. In particular, in semi-molten molding or semi-solid molding in which liquid and solid are mixed, the molten metal has a high viscosity. Compressed to a very high pressure by the injection pressure. For this reason, the trapped air is mixed into the molten metal without any escape space, and is pumped to the product cavity and confined as a void in the die cast product.

  As a countermeasure against the confined air described above, there is a vacuum method in which the product cavity is vacuumed from the sleeve before the molten metal is injected (see, for example, Non-Patent Document 4). It is insufficient to prevent the generation of gas.

  In die-casting, the release agent applied to the sleeve or mold for each molding cycle is mainly composed of inorganic substances such as graphite, oils and fats, moisture, etc., and these are evaporated or decomposed by touching high-temperature molten metal. To generate gas. In general, in die casting, the molten metal supplied to the sleeve before injection contacts the inner surface of the sleeve and the surface of the molten metal is cooled and solidified to form a thin solidified layer. This solidified layer is wound into the molten metal in a state where the release agent is scraped off from the inner surface of the sleeve along with the movement of the molten metal at the time of injection, and the release agent is adhered to the surface. Gas is generated during the entrainment process. This gas is discharged into the space of the sleeve and the product cavity and inside the molten metal. It is known that most of this gas is contained in a die-cast product, resulting in a product defect such as a cast or micro nest, or deformation or swelling after heat treatment.

  In this way, a large amount of release agent is often attached to the solidified layer, and the gas generated from the release agent leads to deterioration of the quality of the die cast product. Measures are taken to prevent fragments (solidified pieces) from entering. In addition, as a technique for suppressing gas generation related to the release agent, a blocking member that blocks the solidified piece in the runner is provided so that the solidified piece to which the release agent adheres does not enter the product cavity (for example, , Refer to Patent Document 1), and measures are taken such that a solidified layer capturing cavity is provided in the middle of the runner (for example, see Non-Patent Document 5).

Japanese Patent Laid-Open No. 7-204821 (page 2-3, FIG. 1-5) “Metal Handbook for Aluminum Technology” published by Karos Publishing, p. 351-354,410 Tomonobu Kanno and Yuzo Uehara “Aluminum Alloy Die Casting / Technology and Defects”, Karos Publishing, 2nd Edition, p. 365 Tomonobu Kanno and Yuzo Uehara “Aluminum Alloy Die Casting / Technology and Defects”, Karos Publishing, 2nd Edition, p. 124-126 “Metal Handbook for Aluminum Technology” published by Karos Publishing, p. 380-381, Table 4.2.14 Tomonobu Kanno and Yuzo Uehara “Aluminum Alloy Die Casting / Technology and Defects”, Karos Publishing, 2nd Edition, p. 447-449

  However, in the prior art described in Patent Document 1 and Non-Patent Document 5 described above, since the molten metal aggregated in the blocking member and the solidified layer capturing cavity contains a large amount of release agent, the gas generated there is also Become more. This gas also becomes a high pressure, mixes in the molten metal, flows into the product cavity, and is contained in the die-cast product, causing product defects such as casting holes, micropores, swelling, deformation, and deterioration of mechanical properties. With this conventional technology, it is difficult to significantly reduce the amount of gas contained in a die-cast product, and the amount of gas contained per 100 g of product will reach several to ten times that of an ideally molded product. Become.

  Further, when the solidified layer capturing cavity is set to the runner or the stamp portion, at the initial stage of molding, the molten metal is divided into a clean molten metal and a molten metal containing a large amount of solidified pieces at the outlet of the solidified layer capturing cavity. For this reason, the solidified layer capturing cavity is hermetically sealed, and the molten metal containing air and solidified pieces is contained therein. After that, as the molding progresses (the plunger moves forward), the molten metal containing solidified pieces flows into the solidified layer capturing cavity, and when the pressure at this part rises, the air is crushed, and the air enters the molten metal. It will flow into the product cavity.

  The present invention has been made in view of the above circumstances, and its purpose is to provide a die-cast product with few casting defects by injecting a clean molten gas containing no solidified layer and oxide film into the product cavity. An object of the present invention is to provide a die-cast molding method that can be molded.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a die casting method for performing casting by injecting molten metal injected from a sleeve by movement of a plunger into a product cavity of the mold through a runner of the mold. In the method, the mold has a shunt weir around the runner inlet, a trapping cavity around the shunt weir, an air vent in the trapping cavity, and the molten metal injected from the sleeve hits the shunt weir. Then, the molten metal is divided into a clean layer and an impurity layer, and the molten liquid in the separated clean layer is injected into the product cavity through the runner. The purpose is to discharge the collected gas to the outside through an air vent.

  According to the configuration of the present invention, the solidified layer formed on the outer periphery of the molten metal on the inner surface of the sleeve and the oxide film attached to the surface of the solidified layer are transferred to the diversion weir when the molten metal is injected from the sleeve by the movement of the plunger. At the end, it is scraped off by the diversion weir and trapped in the trapping cavity as molten impurity layer. Also, a clean layer of molten metal that does not include a solidified layer and an oxide film is injected into the product cavity as it is through the runner. Further, the gas mixed in the impurity layer and collected in the capture cavity is discharged to the outside through the air vent.

  In order to achieve the above object, according to a second aspect of the present invention, in the first aspect of the present invention, the mold includes a chill vent that allows passage of only gas in the middle of the air vent, and only the molten metal that flows into the air vent. The purpose of this is to close the door with chill vent.

  According to the configuration of the above invention, in addition to the operation of the invention described in claim 1, the molten metal flowing from the capture cavity to the air vent is blocked by the chill vent, and the molten metal does not leak out from the air vent.

  According to the first aspect of the present invention, it is possible to inject a molten molten metal that does not contain a solidified layer, an oxide film, and the like into the product cavity, and a die-cast product with few casting defects can be formed.

  According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, it is possible to prevent the molten metal or the like from inadvertently leaking to the outside, and to effectively discharge only the gas. Can do.

  Hereinafter, an embodiment embodying a die casting method of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, the schematic block diagram of the die-cast molding apparatus 1 of a horizontal clamping vertical injection type is shown. The molding apparatus 1 includes, as a basic configuration, a fixed plate 3 and a movable plate 4 provided on a machine base 2, a fixed mold 5 provided on the fixed plate 3, and a movable die provided on the movable plate 4. 6 and an injection device 7 that can be tilted below the molds 5 and 6. Product cavities 8, runners 9, stamp portions 10, and the like are formed in both molds 5 and 6 by closing the molds. The product cavity 8 is a space for molding a target die-cast product. The runner 9 is a passage that guides the molten metal injected from the injection device 7 to the stamp unit 10 to the product cavity 8. The movable platen 4 is provided with a molded product extrusion device 11. The device 11 includes push pins 12 and 13 provided in the product cavity 8 and the stamp portion 10 so as to be able to appear and retract. The injection device 7 includes a cylinder device 14, an injection sleeve 15, and an injection plunger 16 that is fixed to the rod 14 a of the cylinder device 14 and that can reciprocate within the injection sleeve 15.

  In this die casting apparatus 1, the product cavity 8, the runner 9, the stamp part 10 and the like are formed between the molds 5 and 6 by operating the movable platen 4 and closing the mold. Thereafter, the injection device 7 is moved to the lower side of both molds 5 and 6, and the tip portion of the injection sleeve 15 is connected to the stamp portion 10. Thereafter, the molten metal supplied to the injection sleeve 15 is injected from the sleeve 15 to the stamp unit 10 by the movement of the injection plunger 16 and injected into the product cavity 8 through the runner 9. As the injected molten metal solidifies, a workpiece including a die-cast product is cast. Thereafter, the movable platen 4 is operated to open the mold, the molded product extrusion apparatus 11 is operated, and the workpiece is pushed out between the molds 5 and 6 by the extrusion pins 12 and 13.

  FIG. 2 is a cross-sectional view showing a main part in which the distal end portion of the injection sleeve 15 is connected to both molds 5 and 6. FIG. 3 is a plan view showing a main part of the mold matching surface 6a and the like of the movable mold 6 partially including a cross section. Both molds 5 and 6 have a diversion weir 17 around the inlet of the runner 9 (hereinafter referred to as “runner inlet”) 9 a, a capture cavity 18 around the diversion weir 17, and a capture cavity 18. An air vent 20 is provided. When the molten metal is supplied to the injection sleeve 16 and contacts the inner surface of the sleeve 16, the molten metal is cooled by the sleeve 16, and a solidified layer or the like is generated on the outer periphery of the molten metal. As a result, an “impurity layer” including a solidified layer, an oxide, a release agent, and the like, and a clean “clean layer” including no solidified layer or the like are generated. The diversion weir 17 diverts the “impurity layer” and the “clean layer”. The capture cavity 18 is provided in a flange shape with respect to the stamp portion 10 and captures the shunted impurity layer. The air vent 20 discharges the gas collected in the capture cavity 18 to the outside. A pair of air vents 20 are provided at both ends of the capture cavity 18, and are parallel to the runner 9 and the product cavity 8. The air vent 20 includes a chill vent 21. The chill vent 21 is formed of a filter member or the like that increases the surface area in contact with the molds 5 and 6, allows only air to pass through the sintered member, or has a small hole.

FIG. 4 is a simplified diagram showing the main part of FIG. The peripheral edge of the diversion weir 17 is set so as to be positioned inside the sleeve 15 with respect to the impurity layer 30 a formed on the outer periphery of the molten metal 30 on the inner surface of the injection sleeve 15. The dimension a1 of the runner inlet 9a is set smaller than the inner diameter d1 of the injection sleeve 15 by about “5 mm”. The corner 17a of the diversion weir 17 is set as acute as possible. The corner 18a on the stamp portion 10 side of the capture cavity 18 is set to a smooth curved surface. The volume (capture volume) Vc of the capture cavity 18 is set equal to or slightly larger than the volume of the impurity layer 30 a formed on the outer periphery of the molten metal 30. This capture volume Vc can be expressed as the following equation (1).
Vc ≧ πh (d1 ² −d2 ² ) / 4 (1)
Here, [h] means the height of the molten metal supplied to the injection sleeve 15, “d1” means the inner diameter of the injection sleeve 15, and “d2” means the inner diameter of the clean layer 30b excluding the impurity layer 30a.

  FIG. 5 is a conceptual diagram showing the cross section (cross section perpendicular to the mold fitting surface) of the capture cavity 18. As can be seen from FIG. 5, the trapping cavity 18 is provided with a gradient SP that converges from the center in the mold opening direction.

  FIG. 6 is a conceptual diagram showing the settable range SE of the runner inlet 9a. The runner inlet 9 a is set inside the impurity layer 30 a on the inner surface of the injection sleeve 15. Accordingly, in FIG. 6, the runner inlet 9 a is set inside the settable range SE indicated by a broken-line circle.

7A and 7B are conceptual diagrams showing the relationship among the injection plunger 16, the injection sleeve 15, the runner 9, and the product cavity 8. FIG. 7A and 7B show the difference between the front surface and the side surface of the product cavity 8. In this embodiment, the inlet sectional area of the product cavity 8 is “A × C”, the sectional area of the runner 9 is “K × L”, the tip sectional area of the injection plunger 16 is “M”, and the sectional area of the injection sleeve 15 is Assuming “S”, these relationships can be expressed as in the following equation (2).
A × C ≦ K × L ≦ M <S (2)

8A and 8B are conceptual diagrams showing the dimensions of the runner 9. FIGS. 8A and 8B show the vertical and horizontal differences of the runner 9. In this embodiment, the exit dimensions of the runner 9 are indicated as “K1” and “B1”. Further, the inlet dimensions of the runner 9 are indicated as “K2” and “B2”. The exit dimensions K1 and B1 of the runner 9 are set with respect to the longitudinal dimension A and lateral dimension C of the product cavity 8 according to the relationship of the following expressions (3) and (4).
K1 ≧ A × 0.9 (3)
B1 ≧ C × 0.9 (4)

  The vertical gradient of the runner 9 is expressed as “(K1−K2) / L”, where the length of the runner 9 is “L”. The lateral gradient is expressed as “(B1-B2) / L”. In this embodiment, these gradients are set to be “0.23” or less.

  Next, a die casting method performed using the above-described die casting apparatus 1 will be described. 9 to 11 show the main parts and the like in a simplified diagram.

  In this die casting molding apparatus 1, the product plate 8, the runner 9, the stamp portion 10, the capture cavity 18, the air vent 20, and the like are formed between the molds 5 and 6 by closing the mold by operating the movable platen 4. The Thereafter, the injection device 7 is moved to the lower side of both molds 5 and 6, and the tip portion of the injection sleeve 15 is connected to the stamp portion 10. Thereafter, as shown in FIG. 9, the molten metal 30 is supplied to the injection sleeve 15. At this time, an impurity layer 30 a is generated on the outer periphery of the molten metal 30 on the inner surface of the injection sleeve 15. On the surface of the impurity layer 30a, a release agent, an oxide film or the like applied and peeled off on the surface of the sleeve 15 adheres. That is, the outer periphery of the molten metal 30 supplied to the injection sleeve 15 becomes an impurity layer 30a, and the inner side of the impurity layer 30a becomes a clean layer 30b that does not include a solidified layer and an oxide film.

  Next, as shown in FIG. 10, the injection plunger 16 is moved to inject the molten metal 30 from the injection sleeve 15 onto the stamp unit 10. At this time, the impurity layer 30 a that is the outer peripheral portion of the molten metal 30 abuts against the diversion weir 17. Then, the impurity layer 30a hitting the diversion weir 17 is scraped from the molten metal 30 at the corner 17a of the diversion weir 17 without entering the runner inlet 9a, and is captured in the capture cavity 18 as shown in FIG. . Further, the clean layer 30 b not including the solidified layer and the oxide film enters the runner inlet 9 a as it is and is injected into the product cavity 8 through the runner 9. At this time, the gas contained in the impurity layer 30a or generated by a release agent or the like collects in the capture cavity 18 without being mixed into the molten metal of the clean layer 30b. The gas collected in the capture cavity 18 is discharged to the outside through the air vent 20 as shown by arrows in FIGS. Since the molten metal of the impurity layer 30a flowing into the air vent 20 from the capture cavity 18 is blocked by the chill vent 21, the molten metal does not leak out from the air vent 20.

  Thereafter, the melt of the cleaning layer 30b injected into the product cavity 8 is solidified, whereby a workpiece including a die-cast product is cast.

  Next, the movable platen 4 is operated to open the mold, and the extrusion pins 12 and 13 of the molded product extrusion apparatus 11 are ejected, whereby the work is pushed out between the molds 5 and 6. In this embodiment, since the gradient SP is set in the capture cavity 18, the mold opening after molding can be performed smoothly. By removing unnecessary portions solidified by the runner 9, the capture cavity 18, and the like from this work, a target die-cast product can be obtained. In this way, a clean and low-gas-containing clean layer 30b containing no solidified layer and oxide film can be injected into the product cavity 8, and die casting with less casting defects such as casting defects and mechanical strength reduction is achieved. The product can be molded.

  In this embodiment, the chill vent 21 provided in the middle of the air vent 20 allows only gas to pass, and only the molten metal of the impurity layer 30 a flowing into the air vent 20 is blocked by the chill vent 21. For this reason, it is possible to prevent the molten metal or the like from inadvertently leaking to the outside, and only gas can be effectively discharged.

  In this embodiment, since the “blocking member” as in the conventional example is not provided in the middle of the runner 9, the molten metal of the clean layer 30 b can be smoothly flowed to the runner 9, and the shape of the runner 9 is complicated. There is nothing to do. Further, the gas is not blocked in the middle of the runner 9, and the gas is not mixed into the molten metal of the clean layer 30b in the middle of the runner 9. Further, in this embodiment, unlike the solidified layer trapping cavity of the conventional example, the gas flowing into the trapping cavity 18 is not mixed into the molten metal of the clean layer 30b.

  In this embodiment, since the corner 18a of the capture cavity 18 is set to a smooth curved surface, the flow of the impurity layer 30a can be smoothly changed to easily enter the capture cavity 18. Further, since the corner 17a of the diversion weir 17 is set to an angle that sandwiches a right angle (for example, “120 ° or less”), the impurity layer 30a can be surely scraped, and the fragment of the impurity layer 30a enters the runner 9. Can be prevented in advance. Further, in this embodiment, the runner inlet 9a is set in a range inside the impurity layer 30a, so that in this sense, the impurity layer 30a can be surely scraped off, and a fragment of the impurity layer 30a is transferred to the runner 9. Intrusion can be prevented in advance. In this sense, it is possible to prevent the impurity layer 30a from entering the product cavity 8 and generating gas from the impurity layer 30a therein.

  In this embodiment, since the dimensional relationship among the injection plunger 16, the injection sleeve 15, the runner 9, and the product cavity 8 is set as in the above equation (2), the hot water boundary near the inlet of the product cavity 8 can be reduced. The breakage of the impurity layer 30a can be reduced.

  In this embodiment, since the relationship between the dimension of the injection sleeve 16 and the capture volume Vc is set as in the above equation (1), the impurity layer 30a captured in the capture cavity 18 does not flow backward to the runner inlet 9a. . Also in this sense, it is possible to prevent the impurity layer 30a from entering the product cavity 8 and generating gas from the impurity layer 30a therein.

  In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the meaning of invention, it can also implement as follows.

  In the above embodiment, the shape of the capture cavity 18, the runner 9 and the product cavity 8 is set so that the cross-sectional area change becomes discontinuous as shown in FIG. 2, but this shape is shown in FIG. In addition, the cross-sectional area change may be set to be continuous. That is, in this other example, the runner 9 is set to gradually increase or decrease from the runner inlet 9a toward the runner outlet 9b. For this reason, the injection resistance of the molten metal can be reduced.

The schematic block diagram which shows a die-casting apparatus. Sectional drawing which shows the main parts etc. of both molds etc. by which the mold was closed. The top view which shows main parts, such as a mold fitting surface of a movable metal mold | die. FIG. 4 is a simplified diagram showing the main part of FIG. 3. The conceptual diagram which shows the cross-sectional shape of a capture | acquisition cavity. The conceptual diagram which shows the settable range of a runner entrance. The conceptual diagram which shows the relationship between an injection sleeve, a runner, a product cavity, etc. The conceptual diagram which shows the dimension of a runner. A simplified diagram showing the main parts and the like. A simplified diagram showing the main parts and the like. A simplified diagram showing the main parts and the like. Sectional drawing which shows the main parts etc. of both molds etc. by which the mold was closed.

Explanation of symbols

5 fixed mold 6 movable mold 8 product cavity 9 runner 15 injection sleeve 16 injection plunger 17 diversion weir 18 capture cavity 20 air vent 21 chill vent 30 molten metal 30a impurity layer 30b clean layer

Claims (2)

In the die-cast molding method of casting by injecting the molten metal injected from the sleeve by the movement of the plunger into the product cavity of the mold through the runner of the mold,
The mold includes a shunt weir around the runner inlet, a capture cavity around the shunt weir, and an air vent in the capture cavity.
By abutting the molten metal injected from the sleeve against the diversion weir, the molten metal is divided into a clean layer and an impurity layer, and the diverted clean layer melt is injected into the product cavity through the runner, A die casting method characterized in that the molten metal in the impurity layer is captured in the capture cavity and gas collected in the capture cavity is discharged to the outside through the air vent. The mold includes a chill vent that allows only gas to pass in the middle of the air vent,
2. The die casting method according to claim 1, wherein only the molten metal flowing into the air vent is blocked by the chill vent.

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