Die-casting manufacturing method and device, and pressure means

Abstract

To provide a die cast method and device which effectively prevent backflow of molten metal when performing compression of a runner after molten metal injection by a plunger, and thereby activate additional compression to a product injected into a cavity.SOLUTION: There is provided an injection part which includes: first compression means that injects molten metal to a die-casting die; second compression means that compresses a runner communicating with a cavity; and an orifice that is formed on a surface corresponding to a standing runner part directly connected to the cavity in the runner. When performing the second compression through the runner directly connected to the cavity by the second compression means after injecting the molten metal by the first compression means, the compression is performed by the second compression means while preventing the backflow of the molten metal by the orifice to a compression path of the second compression means.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a die-casting manufacturing method and apparatus, and a pressurizing means, and more particularly to a die-casting manufacturing method and apparatus, and a pressurizing means, which can simultaneously eliminate shrinkage cavities and entrainment cavities. [Background technology]

[0002] The casting method for die-cast products involves forcing molten aluminum or other metal into a cavity made in a mold with a plunger, and then removing a product shaped to match the cavity. If shrinkage cavities or entrapment cavities occur during molding, they will result in product defects, so their occurrence must be prevented.

[0003] The runner pressurization method has been proposed as a countermeasure against shrinkage cavities in die-cast products, and the PF method (Pore Free die-casting method) has been proposed as a countermeasure against entrapment cavities. To address the former issue, a method has been proposed in which the runner is further pressurized in conjunction with the plunger pressurization operation, while to address the latter issue, the inside of the mold cavity is replaced with oxygen in advance, which then undergoes a chemical reaction with the molten metal filled into the cavity to produce a dense product.

[0004] In the runner pressurization method, the molten metal is supplied under pressure to the cavity through a sleeve, and then the runner portion directly connected to the cavity is further pressurized by a pressure pin to further pressurize it (Patent Document 1). However, with this method, the molten metal pushed in by the runner pressure flows back and is pushed back toward the plunger, so the desired effect of pushing into the cavity cannot be achieved. From this perspective, a technology has emerged that reduces the gap between the pressure pin and the pressure passage to achieve a pushing effect (Patent Document 2), but this does not provide a solution to the entrapment porosity.

[0005] Furthermore, the PF method has been proposed as a countermeasure to prevent the occurrence of defective product entrainment cavities. As described in Patent Document 3, this method aims to produce pressure-cast products by replacing the atmosphere inside the cavity of a mold with oxygen and locally pressurizing the molten metal filled in the cavity using a squeeze pin or other means. However, this method was unable to prevent shrinkage cavities.

[0006] Furthermore, Patent Document 4 describes a method that combines the conventional PF method, in which oxygen is supplied from the sleeve port, with a localized pressurization method within the product. This method releases oxygen from the inlet of the sleeve, and because it is supplied to the sleeve, runner, and cavity, there is a problem of a decrease in oxygen concentration. Furthermore, the localized pressurization method used to prevent shrinkage cavities can cause dents in the product, which can interfere with the product's ejector pins and cooling passages. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2000-117411 [Patent Document 2] Patent Publication No. 2011-224650 [Patent Document 3] Patent Publication No. 2019-188459 [Patent Document 4] Patent Publication No. 2004-223610 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention addresses the above-mentioned problems and aims to realize the PF method by supplying oxygen to the cavity without reducing its concentration, and to suppress the occurrence of shrinkage cavities throughout the product by applying pressure to the runner. [Means for solving the problem]

[0009] In order to solve the above problems, the present invention is configured as follows: To provide a die-casting method and apparatus that can produce dense die-cast products in which entrainment porosity and shrinkage porosity are simultaneously suppressed by replacing the atmosphere inside the cavity with oxygen before the plunger injects the molten metal during mold clamping to prepare for the PF method, and then, after the molten metal is injected by the plunger, applying a second high pressure to the runner to continue to pressurize the molten metal and solidify it.

[0010] Specifically, the die-casting method according to the present invention involves injecting molten metal from a sleeve using a first pressurizing means, then pressurizing the runner using a second pressurizing means. The pressurizing pin of the second pressurizing means is used to supply oxygen through a tip valve from an oxygen supply passage provided inside the pressurizing pin. After the pressurizing pin of the second pressurizing means is extended into the runner, the cavity is filled with oxygen via the tip valve and then retracted. The runner and sleeve are then filled with oxygen. The first pressurizing means then injects the molten metal through the sleeve, and the second pressurizing means pressurizes the runner. An orifice may be provided midway along the runner pressurization path of the pressurizing pin of the second pressurizing means to prevent backflow of gas and molten metal.

[0011] Furthermore, the present invention is a method in which, after mold clamping, molten metal is injected from the sleeve by a first pressurizing means, and the runner portion directly connected to the cavity is pressurized by a second pressurizing means, wherein an orifice is provided in the runner pressurizing path of the pressurizing pin of the second pressurizing means to prevent backflow of gas and molten metal, and from the start of mold clamping until injection by the first pressurizing means, the pressurizing pin of the second pressurizing means is operated toward the runner, and oxygen is supplied to the cavity and returned by an oxygen supply valve provided on the pressurizing pin while preventing backflow of gas by the orifice, and after molten metal injection by the first pressurizing means, the runner is pressurized by the second pressurizing means while preventing backflow of molten metal by the orifice.

[0012] Furthermore, the die-casting manufacturing method according to the present invention is a method in which, after mold clamping, molten metal is injected from the sleeve by a first pressurizing means, and a runner portion directly connected to the cavity is pressurized by a second pressurizing means, and is characterized by carrying out the following steps: mold clamping operation; oxygen supply operation to the cavity from an oxygen supply valve provided on the pressurizing pin of the second pressurizing means while preventing backflow of gas by an orifice; retraction of the pressurizing pin; molten metal injection operation by the first pressurizing means via the sleeve; and runner pressurization operation by the second pressurizing means via the pressurizing pin while preventing backflow of molten metal by the orifice.

[0013] In these cases, the pressurizing pin of the second pressurizing means has a poppet-type valve formed at its tip, and the opening and closing operation of this poppet-type valve opens and closes the oxygen supply path formed in the center, thereby cutting off the supply of oxygen. The orifice is formed on the surface of the runner corresponding to the runner part directly connected to the cavity, preventing backflow of gas or molten metal.

[0014] Injection into the cavity is performed through a plurality of branch runners, and the orifice is formed on a surface corresponding to the rising runner portion of a selected branch runner or its vicinity to prevent backflow of gas or molten metal.

[0015] The direction of movement of the pressure pin of the second pressure means may be a direction intersecting the direction of movement of the plunger of the first pressure means, or may be a direction parallel to the direction of movement of the plunger of the first pressure means. A second pressurization may be applied to the cavity via a new branch runner connected to the portion where density improvement is desired.

[0016] In the die-casting manufacturing method according to the present invention, after molten metal is injected into a clamped mold by a first pressurizing means, a second pressurizing is performed by a second pressurizing means through a runner directly connected to the cavity, the runner being an auxiliary runner provided at a location where the molten metal filled into the cavity by the first pressurizing means will overflow, and after clamping, before injection by the first pressurizing means, the pressurizing pin of the second pressurizing means is operated to prevent backflow of gas at the orifice while supplying oxygen to the cavity and returning it via an oxygen supply valve provided on the pressurizing pin, and after pressurization by the first pressurizing means has ended, the second pressurizing means is operated to pressurize the cavity through the auxiliary runner.

[0017] The die-casting manufacturing apparatus according to the present invention comprises a first pressurizing means for injecting molten metal into a die-casting mold, a second pressurizing means for pressurizing a runner communicating with a cavity, an oxygen supply passage formed by a pressurizing pin of the second pressurizing means having a hollow tubular structure, and the valve provided at the tip of the pressurizing pin for opening and closing this oxygen supply passage. An orifice through which the pressurizing pin is inserted may be provided on a surface corresponding to the runner directly connected to the cavity.

[0018] The die-casting manufacturing apparatus according to the present invention is characterized by comprising: first pressurizing means for injecting molten metal into a die-casting mold; second pressurizing means for pressurizing a runner communicating with a cavity; an orifice formed on a surface corresponding to the runner directly connected to the cavity and through which a pressurizing pin of the second pressurizing means is inserted; an oxygen supply passage formed inside the pressurizing pin as a hollow tube structure; and a valve provided at the tip of the pressurizing pin for opening and closing the oxygen supply passage.

[0019] In this case, the orifice is formed in the vicinity of the boundary between the branch runner portion, which guides the molten metal ejected from the second pressurizing means to the cavity, and the rising runner portion.

[0020] The runner is made up of a plurality of branch runners, and an orifice is formed on a surface corresponding to a selected branch runner, and a valved pressure pin of the second pressure means can be inserted into the orifice. The direction of movement of the valved pressure pin of the second pressure means can be a direction intersecting the direction of the plunger of the first pressure means, or a direction parallel to the direction of the plunger of the first pressure means. A new branch runner connected to the portion where density improvement is desired may be provided in the first pressurizing means, and a second pressurizing means having a valved pressurizing pin that moves in the same direction as the flow of the molten metal within this new branch runner may be provided.

[0021] The die-casting production apparatus according to the present invention comprises: a first pressurizing means for injecting molten metal into a die-casting die; a second pressurizing means for pressurizing a runner connected to a cavity; the runner being an auxiliary runner provided at a location where the molten metal filled into the cavity by the first pressurizing means will overflow; an orifice formed in the auxiliary runner on a surface corresponding to the runner directly connected to the cavity and through which a pressurizing pin of the second pressurizing means is inserted; the pressurizing pin has a hollow tubular structure and an oxygen supply passage formed therein; and a valve provided at the tip of the pressurizing pin for opening and closing the oxygen supply passage; and control means for controlling a series of operations: after mold clamping and before injection by the first pressurizing means, operating the pressurizing pin of the second pressurizing means to supply oxygen to the cavity via the oxygen supply valve provided on the pressurizing pin while preventing gas backflow at the orifice; and, after pressurization by the first pressurizing means has ended, operating the second pressurizing means to pressurize the cavity through the auxiliary runner.

[0022] The present invention is a pressurizing means for pressurizing a runner of a die-casting mold, characterized in that it comprises a main actuator, a pressurizing pin that moves in and out by the main actuator, an annular passage provided inside the pressurizing pin, a poppet valve that is attached to the top end surface of the pressurizing pin and has a smaller diameter than the top end surface and opens and closes the annular passage, a stem shaft that operates the poppet valve to form the annular passage, and a sub-actuator that drives the stem shaft. [Effects of the Invention]

[0023] With the above configuration, the pressure pin operates to replace the air inside the cavity with oxygen, and then the pressure pin can perform secondary pressurization of the molten metal after the plunger has injected it while preventing backflow of the molten metal. The former action allows the PH method to be performed, while the latter secondary pressurization allows the production of high-pressure, dense die-cast products. In this case, an orifice formed on the surface corresponding to the runner directly connected to the cavity and through which the pressure pin is inserted can prevent backflow of oxygen gas and molten metal. In this way, the PF method and secondary pressurization of the runner can be performed simultaneously in a single part, resulting in a die-cast product that is free of entrainment porosity and shrinkage porosity. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view of a main part of a die-casting manufacturing apparatus according to an embodiment. [Figure 2] 1A and 1B are a cross-sectional view and a side view of a pressure pin used in a die-casting manufacturing apparatus. [Figure 3] FIG. 10 is a hydraulic system diagram for the pressure pin. [Figure 4] FIG. 4 is a cross-sectional view of a main part of a die-casting device showing the operation of a pressure pin. [Figure 5] FIG. 10 is an operational diagram showing another modified example of supplying oxygen gas. [Figure 6] FIG. 10 is a cross-sectional view showing the arrangement of a second pressurizing means according to a second embodiment. [Figure 7] FIG. 10 is a cross-sectional view showing the arrangement of a second pressurizing means according to a third embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing the arrangement of a second pressurizing means according to a fourth embodiment. [Figure 9] FIG. 10 is a cross-sectional view showing the arrangement of second pressure means according to the fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0025] A die-cast manufacturing method and manufacturing apparatus according to an embodiment of the present invention will be described in detail below with reference to the drawings. Note that the following description is merely one embodiment, and various modifications may be made to the present invention as long as they do not deviate from the spirit of the present invention.

[0026] Figure 1 shows a cross-sectional view of the main parts of a die-casting production apparatus according to a first embodiment. The die-casting production apparatus 10 comprises a movable die 12 attached to a movable platen and a fixed die 14 attached to a fixed platen, and molten metal is injected into a cavity 16 formed by bringing the two dies 12, 14 into contact, resulting in a product having a shape that conforms to the cavity 16. The product can be removed from the cavity 16 by separating the dies 12, 14 and operating an ejector pin attached to the back surface of the movable die 12.

[0027] A molten metal supply means is disposed below the cavity 16 as an injection section for supplying molten metal to the cavity 16 of the die-casting manufacturing apparatus 10. This is comprised of a first pressurizing means 22 which is attached by penetrating horizontally through the fixed mold 14 and reaches the cavity 16, a plunger 20 disposed within the injection sleeve 18, and a pressurizing device (not shown) located behind the plunger 20 and capable of pushing and pulling the plunger 20.

[0028] A runner 24 is formed toward the front end of the injection sleeve 18, serving as a passage for the molten metal to reach the cavity 16. This runner 24 is composed of a diverter runner portion 26 that extends almost horizontally from the injection sleeve 18 and a rising runner portion 28 that turns upward so as to connect directly to the bottom of the cavity 16. The molten metal extruded by the plunger 20 of the first pressurizing means 22 passes through the diverter runner portion 26, is turned upward by the rising runner portion 28, and is injected and sprayed into the cavity 16.

[0029] The rising runner portion 28 of the runner 24 is provided with a second pressurizing means 30 that secondarily pressurizes the molten metal in the cavity 16. This second pressurizing means 30 is composed of a main actuator (hydraulic cylinder) 32 mounted on the bottom of the molds 12, 14, and a pressurizing pin (operating piston) 34 attached so as to move in and out from the bottom to the top of the rising runner portion 28. The diameter d of the pressurizing pin 34 is made smaller than the inner diameter D of the rising runner portion 28, allowing the pressurizing pin 34 to slide up and down in the rising runner portion 28. Therefore, the amount by which the pressurizing pin 34 is pressed into the rising runner portion 28 improves the density of the product formed by the cavity 16.

[0030] In this embodiment, an orifice 36 that narrows the inner diameter is formed on the rising runner portion 28 side (part B in FIG. 2) above the intersection (section AB in FIG. 2) between the rising runner portion 28 and the diverter runner portion 26. This is an annular protrusion 38 with a rectangular cross section formed on the inner diameter portion of the rising runner portion 28, and the height of the protrusion 38 (i.e., the inner diameter dimension of the rising runner portion 28) is matched as closely as possible to the outer diameter d of the pressure pin 34 so that a metal seal can be formed in the gap therebetween. Specifically, although this depends on the size of the cavity 16, the gap dimension Δ is 1 / 2 of the difference between the inner diameter D of the rising runner portion 28 and the outer diameter d of the pressure pin 34, and the height of the annular protrusion 38 is determined so that the gap dimension Δ is 1 / 2 to 1 / 3 or less. That is, the gap dimension δ of the metal seal portion is 1 / 2 of the difference between the inner diameter of the annular protrusion 38 and the outer diameter d of the pressure pin 34, where δ = Δ × 1 / 2, and preferably δ = Δ × 1 / 3, with the lower limit being the value at which the metal seal breaks. Also, the axial length L of the annular protrusion 38 is set to about 10 mm to ensure a reliable metal seal.

[0031] 2, in this embodiment, the pressure pin 34 has a stem shaft 40 inserted axially into the pin body, forming an annular passage 42 therein, and the annular passage 42 has a hollow tube structure that opens to the top surface of the pressure pin 34. A poppet valve 44, having a diameter smaller than that of the pressure pin 34, is connected to the upper end of the stem shaft 40 on the top surface of the pressure pin 34 so as to open and close the annular passage 42, and the annular passage 42 opens and closes as the stem shaft 40 moves up and down. When the valve is closed, the poppet valve 44 is flush with the top surface of the pressure pin 34. When the valve is open, the poppet valve 44 is pushed out by the stem shaft 40, separating it from a V-shaped valve seat 46 and protruding from the top surface of the pressure pin 34, thereby opening the annular passage 42 to the top surface of the pressure pin 34. The lower end of the stem shaft 40 is connected to a sub-actuator (hydraulic cylinder) 48 provided inside the pressure pin 34. Therefore, when the sub-actuator 48 is raised and lowered within the pressure pin 34, the poppet valve 44 is opened and closed via the stem shaft 40.

[0032] An oxygen and hydraulic system as shown in Fig. 3 is used to cause these pressure pins 34 to perform a series of operations. First, the annular passage 42 provided in the pressure pin 34 is connected to an oxygen supply port 50, and when the valve is open, oxygen can be supplied from a cylinder 52, which is an oxygen supply source, to the cavity 16 through the pressure pin 34. On the path from the cylinder 52 to the oxygen supply port 50, there are provided in parallel a flow path 58 provided with a large flow rate adjustment valve 54 and an on-off valve 56, and a flow path 64 provided with a small flow rate adjustment valve 60 and an on-off valve 62, so that the amount of oxygen supplied can be adjusted.

[0033] The configuration for performing secondary pressurization using the pressurizing pin 34 and the configuration for opening and closing the poppet valve 44 attached to the pressurizing pin 34 are as follows. Hydraulic pressure is generated from a hydraulic tank 66 using a pump 68, which is connected to the main actuator 32 via a directional control valve 70 so as to drive the pressurizing pin 34 up and down. The hydraulic pressure from the pump 68 is also used to open and close the valve, and is introduced to the sub-actuator 48 via a directional control valve 72 so that the hydraulic pressure can be switched between up and down. This allows the pressurizing pin 34 to be moved upward by the main actuator 32, and then the poppet valve 44 to be opened by the sub-actuator 48, allowing oxygen to be introduced into the cavity 16. Furthermore, the sub-actuator 48 is driven downward to close the poppet valve 44 and stop the supply of oxygen, while only the pressurizing pin 34 is raised, allowing the pressurizing pin 34 to be pushed into the molten metal by the second pressurizing means 30.

[0034] The hydraulic pressure discharge path 74 is configured to measure the piston drive amount of the main actuator 32, and therefore the stroke of the pressure pin 34, from the amount of oil discharged when the pressure pin 34 rises. The stroke detection device 76 has a cylinder-piston structure, consisting of a cylinder body 78 and a piston 80 that slides inside it. One chamber of the cylinder body 78, partitioned by the piston 80, is connected to the hydraulic oil outlet of the pressure cylinder 34, and the other chamber is connected to the directional switching valve 70. As a result, the hydraulic oil discharged from the main actuator 32 flows into the stroke detection device 76, moving the piston 80. A rod 82 is integrally provided with the piston 80, which protrudes from one end of the cylinder body 78 and is connected to a linear potentiometer 84. The actuation start point of the rod 82 is located at one end of the cylinder body 78 (the left end in FIG. 3), and coincides with the pressure start point of the piston of the pressure pin 34 (the lower end in FIG. 3). The linear potentiometer 84 is disposed parallel to the rod 82 and moves with the rod 82 to measure its travel distance. In this stroke detection device 76, the piston 80 has a through-hole that connects the chambers separated by the piston 80. A check valve 86 and an orifice (throttle valve) 88 are attached to this through-hole. The check valve 86 is a one-way valve that blocks the flow of hydraulic oil from the chamber containing hydraulic oil in the pressure pin 34 to the chamber on the directional control valve 70 side, allowing flow in the opposite direction. This allows the stroke detection device 76 to detect the total amount of hydraulic oil when the pressure pin 34 performs a pressure application operation. The orifice (throttle valve) 88 regulates the flow rate of the check valve 86. Furthermore, if the cracking pressure (spring force) of the check valve 86 is weak, hydraulic oil will flow through the check valve when the piston is stopped; this problem can be solved by restricting the flow rate. A control means for controlling the above-described operating system is provided separately to ensure proper operation.

[0035] The manufacturing process using the die-casting manufacturing apparatus 10 configured as described above is shown in Figure 4. An orifice 36 is provided in the runner pressurizing path of the pressurizing pin 34 of the second pressurizing means 30 to prevent backflow of gas and molten metal. First, the mold is closed, and when this is done, the plunger 20 is advanced to block the sprue so that oxygen does not escape (Figure 4(1)). At this time, the pressurizing pin 34 is in a standby position, i.e., retracted from the rising runner portion 28.

[0036] After mold clamping and before injection by the first pressurizing means 22, the pressurizing pin 34 of the second pressurizing means 30 is moved toward the runner (FIG. 4(2)), and after passing through the orifice 36, the poppet valve 44 is opened, and oxygen is supplied to the cavity 16 from the open annular passage 42 provided in the pressurizing pin 34 while preventing backflow of gas through the orifice 36 (FIG. 4(3)). Any gas remaining in the cavity 16 is pushed out by the oxygen and discharged from the air vent. After the air is filled with oxygen, the poppet valve 44 is opened to release the oxygen while the pressure pin 34 is returned to the standby position (Fig. 4(4)), and the poppet valve 44 is closed at the standby position (Fig. 4(5)). At this time, the plunger 20 returns to the injection position, but the internal gas is expelled from the pouring spout by the oxygen.

[0037] After the pressure pin 34 is returned to its standby position, the first pressure means 22 injects the molten metal into the plunger 20, thereby performing casting (Fig. 4(6)). After the plunger 20 reaches its forward limit, the second pressure means 30 applies pressure to the runner while preventing backflow of the molten metal through the orifice 36 (Fig. 4(7)). At this time, the casting pressure exerted by the cavity 16 can be four times higher than in the past.

[0038] As described above, in this embodiment, the mold is first clamped, and the plunger 20 is advanced to pass through the orifice 36, and the poppet valve 44 provided on the top surface of the pressure pin 34 is opened to blow out oxygen. This forces the residual gas inside to the air vent, filling the cavity with a high concentration of oxygen. After that, the reaction with the molten metal injected into the cavity 16 can be fully carried out.

[0039] Furthermore, the runner section can be pressurized by utilizing the backflow prevention effect of the orifice 36. This is extremely beneficial, as it is four times the pressure applied in the conventional method. Specifically, with the second pressurizing means 30 configured as described above, after injection by the plunger 20 of the first pressurizing means 22 is completed, when the pressurizing pin 34 approaches the annular protrusion 38, the molten metal from above penetrates the orifice 36, forming a metal seal and providing a shielding function. This metal seal at the orifice 36 increases the amount of molten metal filling the cavity 16, and the pushing action of the pressurizing pin 34 lengthens the stroke, completing the process. As a result, compared to a product produced using a conventional casting method without runner pressurization, a +4 g increase (0.5%) was observed with the conventional localized pressurization method that pressurizes the center of the cavity 16. However, the runner pressurization method of this embodiment achieved a +14 g increase (1.7%), demonstrating a significant effect.

[0040] Next, another method for supplying oxygen for the PF method will be described with reference to FIG. 5. FIG. 5(1) shows the mold open state in which the pressure pin 34 is retracted from the rising runner portion 28 and is in a standby state. The left and right movable molds 12 and the fixed mold 14 are separated, and the two-dot chain line in the center indicates the die-cast product, runner, and biscuit. When the mold clamping operation begins from this state, as shown in FIG. 5(2), after the product is removed, hydraulic pressure is supplied to the auxiliary actuator 48 of the second pressurizing means 30 while the release agent is being sprayed, causing the pressure pin 34 to advance to its limit of advancement. As shown in FIG. 3(3), the mold clamping proceeds simultaneously, but the poppet valve 44 opens during this clamping process, releasing oxygen. This oxygen enters the cavity 16, and residual gas flows to the outside air through the air vent above. Then, the machining operation begins while oxygen is being discharged, and as shown in Figure 5 (4), the oxygen discharge rate is switched to a small flow rate at the lower limit, filling the sleeve side as well, preventing air from entering the sleeve 18 from the inlet port on the sleeve 18 side, and then the valve 44 is closed. This includes the supply of oxygen to carry out the PF method.

[0041] The annular protrusion 38 forming the orifice 36 may have a rectangular cross section as in the embodiment, but it may also have a V-shaped or arc-shaped cross section. In this case, if the tip of the V-shaped or arc-shaped protrusion is sharp, it will be difficult to remove the metal seal, so it is desirable to have a shape with the tip cut off.

[0042] Furthermore, a cooling means can be placed on the annular protrusion 38 that forms the orifice 36. This can be a horizontal water-cooling type or an oil-cooling type, and it is advisable to cool the annular protrusion 38 when injection by the first pressurizing means 22 is completed and pressure is applied to the annular protrusion 38 by the second pressurizing means 30. This makes it easier to form a metal seal.

[0043] In the above embodiment, the annular protrusion 38 that forms the orifice 36 may be formed as a separate part and attached by a fitting structure when forming the runner 24. This is because the runner 24 is structured to split at the parting line of the mold, making it easy to attach to the rising runner portion 28, which has a semicircular structure. The above embodiment can also be applied to pushing a runner in a hot chamber and when molding plastics.

[0044] Next, a second embodiment of the present invention will be described. Figure 6 shows an example in which a second pressurizing means 30 is provided on a branch runner. Of the branch runners 90a-90d, the left branch runner 90a shown in Figure 6 has a problem with the tendency for porosity to form when the molten metal injected from it solidifies within the product. Therefore, this branch runner 90a is selected as the runner leading to the intended product. After the first pressurizing means 22 injects the amount of molten metal required for the die-cast product 92, the second pressurizing means 30 attached to the selected branch runner 90a applies a secondary pressurization at an ultra-high pressure approximately four times higher than the primary pressurization. Of course, in this case, the internal gas is replaced with oxygen before casting using the poppet valve 44 attached to the pressurizing pin 34. In this case, the movement of the pressurizing pin 34 intersects with the direction of the plunger movement of the first pressurizing means.

[0045] 7 shows a third embodiment. The pressure pin 34 may be oriented parallel to the direction of plunger movement of the first pressure means 22, as shown in FIG. 6. For this reason, the rising runner portion 28 is bent. Furthermore, by supplying oxygen to the cavity and performing second pressurization using a new branch runner connected to the area where density improvement is desired, it is possible to manufacture die-cast products that suppress entrainment porosity and shrinkage porosity caused by the PF method and runner pressurization.

[0046] 8 shows an apparatus according to a fourth embodiment. The runner to be second-pressurized is a degassing runner 94 for the cavity 16 (or alternatively, a die-cast product) by the first pressurizing means 22. This degassing runner 94 is formed on a surface corresponding to the runner directly connected to the cavity 16, and an orifice 36 is provided through which the pressurizing pin 34 of the second pressurizing means 30 is inserted. The pressurizing pin 34 has a hollow tubular structure and is provided with an annular passage (oxygen supply passage) 42 formed therein and a poppet valve 44 provided at the tip of the pressurizing pin 34 for opening and closing the annular passage (oxygen supply passage). During mold clamping, before injection by the first pressurizing means 22, the pressurizing pin 34 of the second pressurizing means 30 is operated to supply oxygen to the cavity 16 through the poppet valve 44 provided on the pressurizing pin 34 while preventing backflow of gas through the orifice 36. This oxygen fills the cavity 16, and the previously filled gas is discharged through the air vent and the branch runners 96a-96d from the molten metal filling port opened in the sleeve. The pressurizing pin 34 is then returned to its standby position, and after the first pressurizing means 22 has filled the molten metal and pressurization has finished, the second pressurizing means 30 is activated again to pressurize the cavity 16 through the gas vent runner 94. A control means (not shown) is provided to control this series of operations. This embodiment also achieves the PF method by supplying oxygen to the cavity 16 and secondary pressurization by the second pressurizing means 30, resulting in a die-cast product with reduced entrainment porosity and shrinkage cavities.

[0047] 9 shows a fifth embodiment. This is an application of the fourth embodiment, particularly to the case where secondary pressurization is performed partially, in which the gas flows through a plurality of branch gas vent runners 94a, 94c, and 94c to a gas vent runner 94, and the branch gas vent runner 94c is used to provide a second pressurizing means 30. This embodiment also has an orifice 36, and by inserting a pressurizing pin 34 into the orifice 36, it is possible to achieve the same effect as the above-mentioned embodiment.

[0048] In the present invention, the poppet valve 44 is set to be flush with the top surface of the pressure pin 34. If this poppet valve 44 had the same diameter as the pressure pin 34 and a flange, a runner pressurization stroke equivalent to the flange height H would be required. However, since the diameter is smaller than that of the pressure pin 34, oxygen gas can be supplied with the shortest stroke after the improvement. Furthermore, if the flange is present during the casting process, when the runner is pressurized and then removed, it is expected that the poppet valve 44 would become stuck because it is enclosed in aluminum by the height H. However, this possibility is eliminated after the modification. Furthermore, if a flanged valve is provided on the top end of the pressure pin 34, the tip valve would rub when the pressure pin 34 is operated due to the small diameter difference between the orifice 36. However, since the valve 44 is formed with a smaller diameter than the top surface of the pressure pin 34, this problem can be prevented. [Industrial Applicability]

[0049] The present invention provides a method and apparatus for die casting production in which, following plunger pressure by a first pressure means, runner pressure is applied by a second pressure means, and products can be manufactured without dents due to the PF method using oxygen supply in the first stage and runner pressure in the second stage, thereby improving product density. [Explanation of symbols]

[0050] 10... Die-casting manufacturing apparatus, 12... Movable mold, 14... Fixed mold, 16... Cavity, 18... Injection sleeve, 20... Plunger, 22... First pressurizing means, 24... Runner, 26... Diverter runner portion, 28... Rising runner portion, 30... Second pressurizing means, 32... Main actuator, 34... Pressurizing pin, 36... Orifice, 38... Annular protrusion, 40... Stem shaft, 42... Annular passage, 44... Poppet valve, 46... Valve seat, 48... Sub-actuator (hydraulic cylinder)... For poppet, 50... Oxygen supply port, 52... Cylinder (oxygen supply source), 54 ……Large flow rate adjustment valve, 56……Opening / closing valve, 58……Flow path, 60……Small flow rate adjustment valve, 62……Opening / closing valve, 64……Flow path, 66……Hydraulic tank, 68……Pump, 70……Directional switching valve, 72……Directional switching valve, 74……Hydraulic discharge path, 76……Stroke detection device, 78……Cylinder body, 80……Piston, 82……Rod, 84……Potentiometer, 86……Check valve, 88……Orifice, 90a-90d……Branched runner, 92……Die-cast product, 94……Gas vent runner, 94a-94c……Branched gas vent runner, 96a-96c……Branched runner.

Claims

1. A method in which molten metal is injected from a sleeve by a first pressurizing means, and then a runner is pressurized by a second pressurizing means, The pressure pin of the second pressure means is used to supply oxygen from an oxygen supply path provided inside the pressure pin through a tip valve, A die casting manufacturing method characterized by first causing the pressure pin of the second pressure means to protrude into the runner, then filling the cavity with oxygen through the tip valve and drawing it in, then injecting the material through a sleeve by the first pressure means, and then pressurizing the runner by the second pressure means.

2. 2. The die casting manufacturing method according to claim 1, wherein an orifice is provided midway along the runner pressurizing path of the pressurizing pin of said second pressurizing means to prevent backflow of gas and molten metal.

3. In this method, after mold clamping, molten metal is injected from a sleeve by a first pressurizing means, and a runner portion directly connected to a cavity is pressurized by a second pressurizing means, An orifice is provided in the runner pressurizing path of the pressurizing pin of the second pressurizing means to prevent backflow of gas and molten metal, From the start of mold clamping until injection by the first pressurizing means, the pressurizing pin of the second pressurizing means is operated to the runner forward limit, and oxygen is supplied to the cavity by the oxygen supply valve provided on the pressurizing pin while preventing gas backflow by the orifice, and returned; After the molten metal is injected by the first pressurizing means, the second pressurizing means pressurizes the runner while preventing backflow of the molten metal at the orifice. A die casting manufacturing method characterized by the above.

4. In this method, after mold clamping, molten metal is injected from a sleeve by a first pressurizing means, and a runner portion directly connected to a cavity is pressurized by a second pressurizing means, supplying oxygen to the cavity from an oxygen supply valve provided on the pressure pin of the second pressure means while preventing backflow of gas through an orifice, simultaneously with the start of clamping; a molten metal injection operation by the first pressurizing means via the sleeve; a second pressurizing means for pressing the runner by a pressurizing pin while preventing backflow of the molten metal by the orifice; A die casting manufacturing method comprising the steps of:

5. 5. A die casting manufacturing method according to claim 1, 3 or 4, wherein the pressure pin of the second pressure means has a poppet-type valve at its tip, and opening and closing the valve opens and closes an oxygen supply passage formed in the center.

6. 6. The die casting manufacturing method according to claim 5, wherein the poppet type valve has a diameter smaller than the outer diameter of the pressure pin and is opened and closed by the top end surface of the pressure pin.

7. 5. The die casting method according to claim 3, wherein the orifice is formed on a surface of the runner corresponding to the runner portion directly connected to the cavity to prevent backflow of gas or molten metal.

8. 5. The die casting manufacturing method according to claim 3, wherein injection into the cavity is performed via a plurality of branch runners, and the orifice is formed on a surface corresponding to the rising runner portion of a selected branch runner or a portion in the vicinity thereof to prevent backflow of gas or molten metal.

9. 5. The die casting manufacturing method according to claim 1, wherein the direction of movement of the pressure pin of the second pressure means is a direction intersecting the direction of movement of the plunger of the first pressure means.

10. 5. The die casting manufacturing method according to claim 1, wherein the direction of movement of the pressure pin of the second pressure means is parallel to the direction of movement of the plunger of the first pressure means.

11. 5. The die casting manufacturing method according to claim 1, wherein a second pressurization is performed on the cavity by a new branched runner connected to a portion where density improvement is desired.

12. After the molten metal is injected into the clamped mold by the first pressurizing means, the second pressurizing means applies second pressure through a runner directly connected to the cavity, The runner is made into a degassing runner for the cavity by a first pressurizing means, After mold clamping is started, before injection by the first pressurizing means, the pressurizing pin of the second pressurizing means is operated to prevent backflow of gas by the orifice, and oxygen is supplied to the cavity by the oxygen supply valve provided on the pressurizing pin and returned; a second pressurizing means for pressing the cavity through the gas vent runner after the first pressurizing means has finished pressing the cavity;

13. a first pressurizing means for injecting molten metal into a die-casting mold; a second pressurizing means for pressurizing a runner communicating with the cavity; an oxygen supply path in which the pressure pin of the second pressure means is formed as a hollow tube structure; a valve provided at the tip of the pressure pin that opens and closes the oxygen supply path; Die casting manufacturing equipment consisting of:

14. 14. The die-casting manufacturing apparatus according to claim 13, further comprising an orifice formed in a surface corresponding to the runner directly connected to the cavity, the orifice through which a pressure pin is inserted.

15. a first pressurizing means for injecting molten metal into a die-casting mold; a second pressurizing means for pressurizing a runner communicating with the cavity; an orifice formed on a surface corresponding to the runner directly connected to the cavity, through which a pressure pin of the second pressure means is inserted; the pressure pin has a hollow tubular structure and an oxygen supply path formed therein; and a valve provided at the tip of the pressure pin for opening and closing the oxygen supply path; A die-casting manufacturing apparatus comprising:

16. 16. The die casting manufacturing apparatus according to claim 15, wherein the orifice is formed in the vicinity of a boundary between a branch runner portion that guides the molten metal ejected from the second pressurizing means into the cavity and a rising runner portion.

17. 16. The die casting manufacturing apparatus according to claim 13 or 15, wherein the runner comprises a plurality of branch runners, and an orifice is formed in a surface corresponding to a selected branch runner, and a valve-equipped pressure pin of the second pressure means can be inserted into the orifice.

18. 16. The die-casting manufacturing apparatus according to claim 13, wherein the direction of movement of the valved pressure pin of the second pressure means is a direction intersecting the direction of the plunger of the first pressure means.

19. 16. The die-casting manufacturing apparatus according to claim 13, wherein the direction of movement of the valved pressure pin of the second pressure means is parallel to the direction of the plunger of the first pressure means.

20. 16. The die casting manufacturing apparatus according to claim 13 or 15, wherein the first pressurizing means is provided with a new branch runner connected to a portion where density improvement is desired, and second pressurizing means is provided with a valved pressurizing pin that moves within the new branch runner in the same direction as the flow of the molten metal.

21. a first pressurizing means for injecting molten metal into a die-casting mold; a second pressurizing means for pressurizing a runner communicating with the cavity; the runner is an auxiliary runner provided at a location where the molten metal filled into the cavity by the first pressurizing means overflows, an orifice formed on a surface of the auxiliary runner corresponding to the runner directly connected to the cavity, through which a pressure pin of the second pressure means is inserted; the pressure pin has a hollow tubular structure and an oxygen supply path formed therein; and a valve provided at the tip of the pressure pin for opening and closing the oxygen supply path; a control means for controlling a series of operations, which includes operating a pressurizing pin of the second pressurizing means after mold clamping has started and before injection by the first pressurizing means, supplying oxygen back into the cavity through an oxygen supply valve provided on the pressurizing pin while preventing gas backflow at the orifice, and operating the second pressurizing means after pressurization by the first pressurizing means has finished, thereby pressurizing the cavity from the auxiliary runner; A die-casting manufacturing apparatus comprising:

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