Die-cast manufacturing method and die-cast manufacturing apparatus, and pressurization means

Abstract

A die-casting method and a die-casting apparatus effectively prevent backward flow of molten metal, and enable additional pressurization to a product injected within a cavity when pressurization of a runner is performed after molten metal injection by a plunger. An injecting portion including first pressurization means that injects a molten metal to a die-casting metallic mold, second pressurization means that pressurizes a runner communicated with the cavity, and an orifice formed on a surface corresponding to a rising runner portion directly connected to the cavity in the runner is provided. When the second pressurization means performs second pressurization through the runner directly connected to the cavity after the first pressurization means injects molten metal, the second pressurization means pressurizes while preventing the molten metal from flowing backward with the orifice in a pressurization passage of the second pressurization means.

Description

TECHNICAL FIELD

[0001] The present invention relates to a die-cast manufacturing method and a die-cast manufacturing apparatus, and pressurization means, and, in particular, relates to a die-cast manufacturing method and a die-cast manufacturing apparatus, and pressurization means that enable simultaneously eliminating shrinkage and blowholes.BACKGROUND ART

[0002] A method for casting a die-cast product includes pushing a molten metal, such as aluminum, into a cavity made by a metallic mold by a plunger and taking out a product in a shape following the cavity. Generation of shrinkage or a blowhole during shaping for a product turns out to be a product defect, and therefore, the generation thereof must be inhibited.

[0003] There has been proposed a runner pressurization method as a countermeasure for shrinkage in a die-cast product, and there also has been proposed a PF method (Pore Free: pore free die casting method) as a countermeasure for blowholes.

[0004] As the former countermeasure, there has been proposed a method that further pressurizes a runner in line with operating to pressurize a plunger. As the latter countermeasure, the inside of the cavity of the metallic mold is preliminarily substituted with oxygen and a chemical reaction with a molten metal filling the cavity is caused, and thus, a finer product is made.

[0005] The runner pressurization method is a method that further pressurizes the molten metal supplied in a pressurized manner to the cavity through a sleeve by further pressurizing a runner portion directly connected to the cavity by a pressure pin (Patent Document 1). However, this method has failed to obtain an expected cavity pushing effect as the molten metal pushed by the runner pressurization flows backward and is pushed back to a plunger side. From such an aspect, there has appeared a technique that ensures obtaining the pushing effect by reducing a gap between the pressure pin and a pressurization passage (Patent Document 2), but it has failed to provide a countermeasure for blowholes.

[0006] There also has been proposed a PF method as a countermeasure for not generating blowholes as a product failure. This is to manufacture a pressure casting product by substituting the inside of the cavity of the metallic mold with oxygen and locally pressurizing the molten metal filling the cavity by a squeeze pin or the like as described in Patent Document 3. However, this has failed to provide a countermeasure for shrinkage.

[0007] Furthermore, there is known a method described in Patent Document 4 as a method that has combined the PF method as a usual method supplying oxygen from a sleeve port and a local squeeze method in a product. This ejects oxygen from a pouring gate of a sleeve and supplies the oxygen to the sleeve, the runner, and the cavity, thereby having a problem of a reduced oxygen concentration. The local squeeze method performed as a countermeasure for shrinkage has a possibility of making a hit mark on a product, which may interfere with an ejector pin for the product or a cooling passage.CITATION LISTPatent Literature

[0008] Patent Document 1: JP-A-2000-117411

[0009] Patent Document 2: JP-A-2011-224650

[0010] Patent Document 3: JP-A-2019-188459

[0011] Patent Document 4: JP-A-2004-223610DISCLOSURE OF THE INVENTIONProblems to be Solved by the Invention

[0012] The present invention focuses on the above-described problems, and it is an object of the present invention to enable achieving a PF method that supplies oxygen to a cavity without reducing oxygen concentration and to inhibit generation of shrinkage of an entire product in a runner pressurization.Solutions to the Problems

[0013] The present invention has been configured as follows in order to solve the above-described problems. It is to provide a die-casting method and a die-casting apparatus that enable producing a fine die-cast product in which blowholes and shrinkage are simultaneously inhibited by performing a preparation reaching a PF method by substituting the inside of a cavity with oxygen before molten metal injection by a plunger when molds are clamped, and subsequently solidifying the molten metal by secondarily pressurizing a runner at a high pressure and continuously pressurizing the molten metal after the molten metal injection by the plunger.

[0014] Specifically, a die-cast manufacturing method according to the present invention includes: injecting a molten metal from a sleeve by first pressurization means;

[0015] subsequently pressurizing a runner by second pressurization means; using a pressure pin of the second pressurization means to allow an oxygen supply passage provided in the pressure pin to supply oxygen through a distal end valve; and after the pressure pin of the second pressurization means is preliminarily moved to project into the runner, filling the cavity with the oxygen via the distal end valve to draw the pressure pin, subsequently filling the runner and the sleeve with oxygen, and afterwards, injecting the molten metal with the first pressurization means through the sleeve, and then performing the runner pressurization by the second pressurization means. It is sufficient that an orifice in a middle of a runner pressurization passage of the pressure pin of the second pressurization means is provided to allow preventing a gas and the molten metal from flowing backward.

[0016] Further, the present invention includes: injecting a molten metal from a sleeve by first pressurization means after molds are clamped; pressurizing a runner portion directly connected to a cavity by second pressurization means; providing an orifice in a runner pressurization passage of a pressure pin of the second pressurization means to prevent a gas and the molten metal from flowing backward; before the injection by the first pressurization means from the mold clamping starts, operating the pressure pin of the second pressurization means to move to a runner side and preventing the gas from flowing backward with the orifice while supplying oxygen to the cavity with an oxygen supply valve disposed in the pressure pin to return the pressure pin; after the molten metal injection by the first pressurization means, causing the orifice with the second pressurization means to prevent the molten metal from flowing backward while performing runner pressurization.

[0017] The die-cast manufacturing method according to the present invention includes: injecting a molten metal from a sleeve by first pressurization means after molds are clamped; and pressurizing a runner portion directly connected to a cavity by second pressurization means. The method performs steps of: a mold clamping operation; an oxygen supplying operation to the cavity from an oxygen supply valve disposed in the pressure pin of the second pressurization means while an orifice prevents a gas from flowing backward; a drawn-in operation of the pressure pin; a molten metal injection operation by the first pressurization means via the sleeve; and a runner pressurization operation by the second pressurization means by the pressure pin while the orifice prevents the molten metal from flowing backward.

[0018] In these cases, the pressure pin of the second pressurization means is formed with a poppet-type valve at a distal end portion, and a valve opening / closing operation thereof opens and closes an oxygen supply passage formed in a center portion to stop the supply of oxygen. The orifice is formed on a surface corresponding to the runner portion directly connected to the cavity in the runner to prevent the gas or the molten metal from flowing backward.

[0019] The molten metal is injected into the cavity via a plurality of branching runners, and the orifice is formed on a rising runner portion of a selected branching runner or on a surface corresponding to a neighboring portion of the rising runner portion to prevent the gas or the molten metal from flowing backward.

[0020] The pressure pin of the second pressurization means has a moving direction that is a direction intersecting with a plunger operation direction of the first pressurization means, or has a moving direction that is a direction parallel to a plunger operation direction of the first pressurization means.

[0021] The second pressurization to the cavity may be performed through a new branching runner coupled to a portion where a density improvement is desired.

[0022] A die-cast manufacturing method according to the present invention includes: when second pressurization means performs second pressurization through a runner directly connected to a cavity after first pressurization means injects a molten metal to clamped metallic molds, using an auxiliary runner disposed at a position where the molten metal filling the cavity by the first pressurization means overflows; after mold clamping, operating a pressure pin of the second pressurization means before the injection by the first pressurization means and preventing a gas from flowing backward with the orifice while supplying oxygen to the cavity by an oxygen supply valve disposed in the pressure pin to return the pressure pin; and after the pressurization by the first pressurization means is terminated, operating the second pressurization means to pressurize the cavity from the auxiliary runner.

[0023] A die-cast manufacturing apparatus according to the present invention includes: first pressurization means that injects a molten metal to a die-casting metallic mold; second pressurization means that pressurizes a runner communicated with a cavity; an oxygen supply passage formed with a pressure pin of the second pressurization means as a hollow pipe structure; and the valve disposed at a distal end of the pressure pin that opens and closes the oxygen supply passage. An orifice may be formed on a surface corresponding to the runner directly connected to the cavity. The pressure pin is inserted through the orifice.

[0024] A die-cast manufacturing apparatus according to the present invention includes: first pressurization means that injects a molten metal to a die-casting metallic mold; second pressurization means that pressurizes a runner communicated with a cavity; an orifice formed on a surface corresponding to the runner directly connected to the cavity, a pressure pin of the second pressurization means being inserted through the orifice; an oxygen supply passage internally formed as a hollow pipe structure of the pressure pin and a valve disposed in a distal end portion of the pressure pin, the valve opening and closing the oxygen supply passage.

[0025] In this case, the orifice is formed at proximity of a boundary between a sprue core runner portion leading the molten metal injection from the second pressurization means to the cavity and a rising runner portion.

[0026] The runner is formed of a plurality of branching runners, the orifice is formed on a surface corresponding to a selected branching runner, and a valved pressure pin of the second pressurization means is insertable into the orifice.

[0027] The valved pressure pin of the second pressurization means has a moving direction that is a direction intersecting with a plunger direction of the first pressurization means or has a moving direction that is a direction parallel to a plunger direction of the first pressurization means.

[0028] A new branching runner may be provided in the first pressurization means. The new branching runner being coupled to a portion where a density improvement is desired and second pressurization means having a valved pressure pin that moves in a direction identical to a direction of a flow of the molten metal within the new branching runner may be provided.

[0029] A die-cast manufacturing apparatus according to the present invention includes: first pressurization means that injects a molten metal to a die-casting metallic mold; second pressurization means that pressurizes a runner communicated with a cavity; the runner serving as an auxiliary runner disposed at a position where the molten metal filling the cavity by the first pressurization means overflows; an orifice through which a pressure pin of the second pressurization means is inserted, the orifice being formed on a surface corresponding to the runner directly connected to the cavity in the auxiliary runner; an oxygen supply passage internally formed as a hollow pipe structure of the pressure pin and a valve disposed in a distal end portion of the pressure pin, the valve opening and closing the oxygen supply passage; and control means that controls a sequence of operations of: after mold clamping, operating a pressure pin of the second pressurization means before the injection by the first pressurization means and preventing a gas from flowing backward by the orifice while supplying oxygen to the cavity by an oxygen supply valve disposed in the pressure pin to return the pressure pin; and after the pressurization by the first pressurization means is terminated, operating the second pressurization means to pressurize the cavity from the auxiliary runner.

[0030] The present invention is pressurization means for performing runner pressurization of a die-casting metallic mold. The pressurization means includes: a main actuator; a pressure pin operated in and out by the main actuator; a ring passage disposed inside the pressure pin; a poppet valve mounted on a top end surface of the pressure pin opening and closing the ring passage, the poppet valve having a diameter smaller than a diameter of the top end surface; a stem shaft that operates the poppet valve and forms the ring passage; and a secondary actuator that drives the stem shaft.Effects of the Invention

[0031] The above-described configuration ensures that the operation of the pressure pin substitutes the inside of the cavity with oxygen, and next, the molten metal is able to be secondarily pressurized while preventing the molten metal from flowing backward by the pressure pin after the molten metal injection by the plunger, and thus, the action by the former performs a PF method and the secondary pressurization by the latter enables manufacturing a fine die-cast product under a high pressure. In this case, disposing an orifice through which the pressure pin is inserted on a surface corresponding to a runner directly connected to the cavity enables preventing the oxygen gas and the molten metal from flowing backward. Thus, the PF method and the runner secondary pressurization are simultaneously achievable with one component, and a die-cast product in which generation of blowholes and shrinkage is prevented is completed.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a cross-sectional view of a relevant portion of a die-cast manufacturing apparatus according to an embodiment.

[0033] FIG. 2 is a cross-sectional view and a side view of a pressure pin used for the die-cast manufacturing apparatus.

[0034] FIG. 3 is a hydraulic system diagram to the pressure pin.

[0035] FIG. 4 is a cross-sectional view of a relevant portion of the die-casting apparatus illustrating an operational configuration of the pressure pin.

[0036] FIG. 5 is an operational configuration diagram illustrating another modification that supplies an oxygen gas.

[0037] FIG. 6 is a layout cross-sectional view of second pressurization means according to a second embodiment.

[0038] FIG. 7 is a layout cross-sectional view of second pressurization means according to a third embodiment.

[0039] FIG. 8 is a layout cross-sectional view of second pressurization means according to a fourth embodiment.

[0040] FIG. 9 is a layout cross-sectional view of second pressurization means according to a fifth embodiment.DESCRIPTION OF PREFERRED EMBODIMENTS

[0041] The following will describe a die-cast manufacturing method and a die-cast manufacturing apparatus according to embodiments of the present invention in detail with reference to the drawings. Note that the following description is merely an example, and the present invention can include various kinds of modifications as long as the gist of the present invention is not changed.

[0042] FIG. 1 illustrates a cross-sectional view of a relevant portion of a die-cast manufacturing apparatus according to a first embodiment. A die-cast manufacturing apparatus 10 includes a movable metallic mold 12 mounted on a movable plate and a fixed metallic mold 14 mounted on a fixed plate. The die-cast manufacturing apparatus 10 injects a molten metal into a cavity 16 formed by bringing the two metallic molds 12 and 14 in contact, and thus, a product in a shape following the cavity 16 is made. The product can be taken out of the cavity 16 by separating the metallic molds 12 and 14 and operating a squeeze pin disposed in a back surface portion of the movable metallic mold 12.

[0043] As an injecting portion for supplying the molten metal to the cavity 16 of the die-cast manufacturing apparatus 10, molten supply means is disposed below the cavity 16. This is configured of first pressurization means 22 made of an injection sleeve 18 mounted passing horizontally through the fixed metallic mold 14 to reach the cavity 16, a plunger 20 arranged within the injection sleeve 18, and a pressure device (not illustrated) located at the rear of the plunger 20 and able to push and pull the plunger 20.

[0044] A runner 24 that serves as a passage of the molten metal reaching the cavity 16 is formed in a direction of a front end of the injection sleeve 18. This runner 24 is made of a sprue core runner portion 26 approximately horizontally extended from the injection sleeve 18 and a rising runner portion 28 oriented upward so as to be directly connected to a lower portion of the cavity 16. The runner 24 is configured such that the molten metal extruded by the plunger 20 of the first pressurization means 22 is injected out to the cavity 16 after the molten metal passes through the sprue core runner portion 26 and is orientated upward by the rising runner portion 28.

[0045] The rising runner portion 28 in such a runner 24 is provided with second pressurization means 30 that secondarily pressurizes the molten metal in the cavity 16. This second pressurization means 30 is configured of a main actuator (hydraulic cylinder) 32 equipped in the lower portion of the metallic molds 12, 14 and a pressure pin (operational piston) 34 mounted so as to be moved in and out from a lower portion of the rising runner portion 28 to an upper portion by the main actuator 32. The pressure pin 34 has a diameter d made to be smaller than an inner diameter D of the rising runner portion 28 so as to allow the pressure pin 34 to slide up and down in the rising runner portion 28. Accordingly, a press-fitting amount of the pressure pin 34 into the rising runner portion 28 improves a product density by the cavity 16.

[0046] In the embodiment, in particular, an orifice 36 that reduces the inner diameter is formed in a side of the rising runner portion 28 (the part B in FIG. 1) that is above an intersecting portion (the section A to B in FIG. 1) between the rising runner portion 28 and the sprue core runner portion 26. This is a ring projection 38 having a rectangular cross-section formed in an inner diameter portion of the rising runner portion 28 and serves to make a metallic seal in a gap between the projection 38 and the pressure pin 34, which is achieved by adjusting a height of the projection 38 (that is, an inner diameter dimension of the rising runner portion 28) to the outer diameter d of the pressure pin 34 as close as possible. Specifically, the height of the ring projection 38 is determined such that, while it depends on the size of the cavity 16, a gap dimension Δ, which is ½ of the difference between the inner diameter D of the rising runner portion 28 and the outer diameter d of the pressure pin 34, to be ½ to ⅓ or less. That is, ½ of the difference between the inner diameter of the ring projection 38 and the outer diameter d of the pressure pin 34 is a gap dimension δ of a metallic seal portion, where δ=Δ×½, preferably δ=Δ×⅓, and the lower limit value is a value at which the metallic seal breaks. The ring projection 38 has an axial length L of approximately 10 mm, which ensures reliable metallic sealing.

[0047] In the embodiment, as seen in FIG. 2, the pressure pin 34 has a stem shaft 40 axially inserted through an inside of the pin body to internally form a ring passage 42. The ring passage 42 has a hollow pipe structure opened on a top end surface of the pressure pin 34. On the top end surface of the pressure pin 34, a poppet valve 44 having a diameter smaller than the diameter of the pressure pin 34 is connected to an upper end of the stem shaft 40 so as to allow opening and closing the ring passage 42. The poppet valve 44 serves to open and close the ring passage 42 in association with the up and down movement of the stem shaft 40. The poppet valve 44 is flush with the top end surface of the pressure pin 34 when the valve is closed, and projects from the top end surface of the pressure pin 34 separating away from a V-shaped valve seat 46 by being pushed out by the stem shaft 40 to release the ring passage 42 on the top end surface of the pressure pin 34 when the valve is opened. A lower portion of the stem shaft 40 is connected to a secondary actuator (hydraulic cylinder) 48 disposed inside the pressure pin 34. Accordingly, the secondary actuator 48 moved up and down within the pressure pin 34 opens and closes the poppet valve 44 through the stem shaft 40.

[0048] In order to cause the pressure pin 34 to perform these sequence of operations, the oxygen / hydraulic system illustrated in FIG. 3 is used. First, the ring passage 42 disposed in the pressure pin 34 is connected to an oxygen supply port 50, and is able to supply oxygen to the cavity 16 through the pressure pin 34 while the valve is open from a tank 52 as an oxygen supply source. In the course of the passage from the tank 52 to the oxygen supply port 50, there are provided in parallel a flow passage 58 in which a large flow rate control valve 54 and an opening / closing valve 56 are disposed and a flow passage 64 in which a small flow rate control valve 60 and an opening / closing valve 62 are disposed, which allows adjustment of a supply amount of the oxygen.

[0049] Next, the configuration for causing the pressure pin 34 to perform the secondary pressurization and the configuration for opening and closing the poppet valve 44 mounted on the pressure pin 34 are as follows. The hydraulic pressure is generated from a hydraulic tank 66 using a pump 68, and the pump 68 is connected to the main actuator 32 via a direction switching valve 70 so as to drive the pressure pin 34 to move up and down. The hydraulic pressure of the pump 68 is also used for opening and closing the valve, and the hydraulic pressure is introduced to the secondary actuator 48 in a manner switchable up and down by a direction switching valve 72. This causes the main actuator 32 to move the pressure pin 34 up, and subsequently the secondary actuator 48 to open the poppet valve 44, thereby enabling the oxygen to be introduced into the cavity 16. Raising only the pressure pin 34 in a state where the oxygen supply is stopped by driving the secondary actuator 48 down to close the poppet valve 44 enables the second pressurization means 30 to cause the pressure pin 34 to operate to push the molten metal.

[0050] Note that, in a hydraulic pressure discharge path 74 when the pressure pin 34 is raised, a piston driving amount of the main actuator 32, eventually a stroke of the pressure pin 34 is measured from a discharged amount of oil. This stroke detecting device 76 is configured of a cylinder piston structure, and this is configured of a cylinder body 78 and a piston 80 slidable within the cylinder body 78. One chamber partitioned by the piston 80 in the cylinder body 78 is connected to a hydraulic oil outlet of the pressure pin 34, and the other chamber is connected to the direction switching valve 70. This causes the hydraulic oil exiting from the main actuator 32 to enter the stroke detecting device 76 by the exiting amount, and thus, the piston 80 is moved. The piston 80 is integrally provided with a rod 82, and this projects from one end portion of the cylinder body 78 and is coupled to a linear-type potentiometer 84. An operation starting point of the rod 82 is in one end portion side (the left end in FIG. 3) of the cylinder body 78, and at this time, it corresponds to a pressurization starting point (the lower end in FIG. 3) of the piston of the pressure pin 34. The linear-type potentiometer 84 is arranged parallel to the rod 82, moves with the rod 82, and obtains its movement distance. In such a stroke detecting device 76, its piston 80 is provided with a through-hole communicating through the chambers partitioned by the piston 80, and a check valve 86 and an orifice (throttle valve) 88 are mounted in this through-hole. This check valve 86 is a one-way valve that blocks the flow of the hydraulic oil discharged to the chamber in a side of the direction switching valve 70 from the chamber into which the hydraulic oil of the pressure pin 34 enters and allows the flow in the opposite direction. Thus, the whole amount of the hydraulic oil when the pressure pin 34 performs the pressurization operation is detected by the stroke detecting device 76. The orifice (throttle valve) 88 restricts a flow rate of the check valve 86. Since a weak cracking pressure (spring force) of the check valve 86 causes the hydraulic oil to flow through the check valve with the piston stopped, it is solvable by reducing the flow rate.

[0051] Note that control means that controls the operation system as described above is additionally disposed to control it to properly operate.

[0052] A manufacturing process by thus configured die-cast manufacturing apparatus 10 is illustrated in FIG. 4. The orifice 36 is disposed in the runner pressurization passage of the pressure pin 34 of the second pressurization means 30, and thus, the backward flow of the gas and the molten metal is preventable. First, the molds are clamped. When the molds are being clamped, the plunger 20 is advanced to make an occlusion so as to stop the oxygen from exiting from the sprue (FIG. 4(1)). At this time, the pressure pin 34 is at a standby position, that is, is in a drawn-in state from the rising runner portion 28.

[0053] After the molds are clamped, before the injection by the first pressurization means 22, the pressure pin 34 of the second pressurization means 30 is moved to the runner side (FIG. 4(2)), and after it passes the orifice 36, the poppet valve 44 is opened to supply oxygen to the cavity 16 from the released ring passage 42 disposed in the pressure pin 34 while the backward flow of the gas is prevented with the orifice 36 (FIG. 4(3)). The gas remaining in the cavity 16 is discharged by the oxygen and discharged from an air vent.

[0054] After an oxygen filling state is obtained, the poppet valve 44 is opened and the pressure pin 34 is returned to the standby position while the oxygen is discharged (FIG. 4(4)), and the poppet valve 44 is closed at the standby position (FIG. 4(5)). At this time, while the plunger 20 returns to the injection position, the internal gas is discharged from the pouring gate by the oxygen.

[0055] After the pressure pin 34 is returned to the standby position, the first pressurization means 22 causes the plunger 20 to inject the molten metal, thus performing casting (FIG. 4(6)). After the plunger 20 reaches the advance limit, the runner pressurization is performed while the second pressurization means 30 causes the orifice 36 to prevent the molten metal from flowing backward (FIG. 4(7)). For the casting pressure by the cavity 16 at this time, a pressure four times higher than the conventional pressure can be applied.

[0056] Thus, in the embodiment, while first, the molds are clamped and the plunger 20 is in an advanced state, the pressure pin 34 is passed through the orifice 36, and the poppet valve 44 disposed on the top end surface of the pressure pin 34 is opened to blow the oxygen out, and thus, the internally remaining gas is discharged to the air vent to allow the cavity to be filled with the oxygen at a high concentration. Subsequently, the reaction with the molten metal injected into the cavity 16 can be sufficiently caused.

[0057] The runner portion pressurization is also possible by using the backward flow prevention effect by the orifice 36, and this reaches an applied pressure four times more than the conventional applied pressure, thus being considerably beneficial. That is, the second pressurization means 30 thus configured provides a shielding function with a portion of the metallic seal formed of the molten metal in the upper side entering into the portion of the orifice 36 when the pressure pin 34 approaches the ring projection 38 after the plunger 20 of the first pressurization means 22 has completed the injection. In view of this, this metallic seal at the portion of the orifice 36 increases the molten metal filling amount into the cavity 16, and the pushing operation by the pressure pin 34 lengthens the stroke, then, the operation is completed. As the result, when a product made in an ordinary casting method without the runner pressurization is set to “0,” a conventional local squeeze method that pressurizes a center portion of the cavity 16 observed an increase of +4 g (0.5%), and the runner pressurization method of this embodiment method observed an increase of +14 g (1.7%). Thus, the embodiment presented a remarkable effect.

[0058] Next, another method for achieving an oxygen supply method for performing the PF method will be described with reference to FIG. 5. FIG. 5(1) illustrates a mold opened state where the pressure pin 34 is drawn from the rising runner portion 28 and is in a standby state. The movable metallic mold 12 and the fixed metallic mold 14 in the right and left are in a separated state, and the two-dot chain line in the center portion indicates a die-cast product, a runner, and a biscuit. When the mold clamping operation starts from such a state, as illustrated in FIG. 5(2), after the product is taken out, the hydraulic pressure is supplied to the secondary actuator 48 of the second pressurization means 30 while a spray of a mold release agent is operating, and the pressure pin 34 is advanced to the advance limit. As illustrated in FIG. 3(3), the mold clamping proceeds simultaneously with this, and the poppet valve 44 is opened in the middle of this mold clamping to discharge oxygen. This oxygen enters the cavity 16 and the remaining gas flows into the outside air through the air vent in the upper. The machining operation takes place while the oxygen is discharged, and as illustrated in FIG. 5(4), the discharge amount of the oxygen is switched to a small flow rate at the lower limit, the sleeve side is also filled up with the oxygen to prevent the air from entering the sleeve 18 from the pouring gate in the sleeve 18 side, and the valve 44 is closed. The oxygen supply for performing such a PF method is included.

[0059] Note that while the ring projection 38 forming the orifice 36 may have a square cross-sectional surface as in the embodiment, it is also allowed to have a cross-sectional shape in a V shape or an arc shape. In this case, if the tip of the V shape or the arc shape is sharp, the metallic seal is not taken, therefore, the shape of sharpened tip end is preferred.

[0060] The ring projection 38 forming the orifice 36 can be provided with cooling means. This can be a horizontal system, a water-cooling system, or an oil-cooling system, and cooling is preferably performed when the injection by the first pressurization means 22 is completed, and the pressure by the second pressurization means 30 is applied to the ring projection 38. Thus, the metallic seal is easily formed.

[0061] In the above-described embodiment, the ring projection 38 forming the orifice 36 may be formed as another component, and may be mounted in a fitting-in structure when the runner 24 is formed. This is because installation to the rising runner portion 28 having a semicircle structure can be easily performed since the runner 24 has a structure dividable on a splitting line of the metallic molds.

[0062] The above-described embodiment can be applied to pushing a runner of a hot chamber or to the case of forming a plastic.

[0063] Next, in the above-described embodiment, the second embodiment of the present invention will be described. FIG. 6 is an example in which the second pressurization means 30 is disposed in a branching runner. There has been a problem of easy occurrence of porosities when a molten metal injected from a branching runner 90a on the left side illustrated in FIG. 6 of these branching runners 90a to 90d solidifies within the product. Therefore, this branching runner 90a is selected as a runner coupled to the intended production portion, and after the first pressurization means 22 has injected a required amount of molten metal for a die-cast product 92, the second pressurization means 30 disposed in the selected branching runner 90a performs the secondary pressurization at a super high pressure that is approximately four times more of the primary pressurization. Obviously, it is needless to say that, also in this case, the casting is performed with the poppet valve 44 mounted on the pressure pin 34 substituting the internal gas with oxygen in advance. The moving direction of the pressure pin 34 in this case is a direction intersecting with a plunger operation direction of the first pressurization means.

[0064] FIG. 7 is a third embodiment. The pressure pin 34 may be in a direction parallel to the plunger operation direction of the first pressurization means 22 as in FIG. 6. In view of this, the rising runner portion 28 is flexed.

[0065] Furthermore, a new branching runner coupled to a portion where density improvement is desired is caused to perform oxygen supply and second pressurization to the cavity, and thus, a die-casting product in which blowholes and shrinkage are inhibited is manufacturable using the PF method and the runner pressurization.

[0066] FIG. 8 illustrates an apparatus according to a fourth embodiment. The runner subject to the second pressurization serves as a gas purge runner 94 for the cavity 16 (alternatively, a die-cast product) by the first pressurization means 22, and the orifice 36 through which the pressure pin 34 of the second pressurization means 30 is inserted is disposed on a surface corresponding to a runner directly connected to the cavity 16 in this gas purge runner 94. There are disposed the ring passage (oxygen supply passage) 42 formed inside the hollow pipe structure of the pressure pin 34 and the poppet valve 44 that is disposed at a distal end portion of the pressure pin 34 and opens and closes the ring passage (oxygen supply passage). When the molds are clamped, before the injection by the first pressurization means 22, the pressure pin 34 of the second pressurization means 30 is operated and the orifice 36 prevents the gas from flowing backward, and the poppet valve 44 disposed in the pressure pin 34 supplies oxygen to the cavity 16. This oxygen fills the cavity 16, and the gas that has previously filled the cavity 16 is discharged from a molten metal filling port opened in a sleeve through an air vent and via the branching runners 96a to 96d. Afterwards, the pressure pin 34 is returned to the standby position, and after molten metal filling by the first pressurization means 22, the second pressurization means 30 is operated again after the pressurization is terminated to pressurize the cavity 16 from the gas purge runner 94. There is provided control means (not illustrated) that controls this sequence of operations. This embodiment also achieves the PF method by oxygen supply to the cavity 16 and the secondary pressurization by the second pressurization means 30, thereby enabling obtainment of a die-cast product in which blowholes and shrinkage are improved.

[0067] FIG. 9 illustrates a fifth embodiment. This is applied to, in particular, a case where the secondary pressurization is partially performed in the fourth embodiment, and while the gas purge runner 94 is reached through a plurality of branching gas purge runners 94a, 94b, 94c, the branching gas purge runner 94c is used for disposing the second pressurization means 30. The orifice 36 is also disposed in this, and inserting the pressure pin 34 through the orifice 36 portion enables providing a similar effect to that of the above-described embodiments.

[0068] In the present invention, the above-described poppet valve 44 is set to be flush with the top end surface of the pressure pin 34. This poppet valve 44 requires a runner pressurization stroke of an amount of a height H of a flange if the poppet valve 44 has the same diameter as that of the pressure pin 34 and has a flange portion, but it has a diameter smaller than that of the pressure pin 34, and therefore, it can supply an oxygen gas with the shortest stroke after improvement. If there is a flange when pulling operation is performed after casting and runner pressurization, the amount of the height H is covered with aluminum, and therefore, it is anticipated that the poppet valve 44 is not able to be pulled out. This possibility is also eliminated after the modification. Furthermore, when the upper end portion of the pressure pin 34 is provided with a flanged valve, a distal end valve is rubbed because there is not much diameter difference with the orifice 36 when the pressure pin 34 is operated. However, since the valve 44 is formed to have a diameter smaller than that of the top end surface of the pressure pin 34, such an event is also preventable.INDUSTRIAL APPLICABILITY

[0069] The present invention is a method and an apparatus that enable pressurizing a runner by second pressurization means subsequently to plunger pressurization by first pressurization means in die-cast manufacturing, enable manufacturing a product without generating hit marks on the product caused by a PF method by oxygen supply in the former stage and a runner pressurization in the latter stage, and enable improving a product density.DESCRIPTION OF REFERENCE SIGNS10 die-cast manufacturing apparatus, 12 movable metallic mold, 14 fixedmetallic mold, 16 cavity, 18 injection sleeve, 20 plunger, 22 firstpressurization means, 24 runner, 26 sprue core runner portion, 28 risingrunner portion, 30 second pressurization means, 32 main actuator,34 pressure pin, 36 orifice, 38 ring projection, 40 stem shaft,42 ring passage, 44 poppet valve, 46 valve seat, 48 secondary actuator(hydraulic cylinder) for poppet, 50 oxygen supply port, 52 tank (oxygensupply source), 54 large flow rate control valve, 56 opening / closing valve,58 flow passage, 60 small flow rate control valve, 62 opening / closingvalve, 64 flow passage, 66 hydraulic tank, 68 pump, 70 directionswitching valve, 72 direction switching valve, 74 hydraulic pressuredischarge path, 76 stroke detecting device, 78 cylinder body, 80 piston,82 rod, 84 potentiometer, 86 check valve, 88 orifice, 90a to 90d branchingrunner, 92 die-cast product, 94 gas purge runner, 94a to 94c branching gaspurge runner, 96a to 96c branching runner.

Examples

first embodiment

[0042]FIG. 1 illustrates a cross-sectional view of a relevant portion of a die-cast manufacturing apparatus according to a A die-cast manufacturing apparatus 10 includes a movable metallic mold 12 mounted on a movable plate and a fixed metallic mold 14 mounted on a fixed plate. The die-cast manufacturing apparatus 10 injects a molten metal into a cavity 16 formed by bringing the two metallic molds 12 and 14 in contact, and thus, a product in a shape following the cavity 16 is made. The product can be taken out of the cavity 16 by separating the metallic molds 12 and 14 and operating a squeeze pin disposed in a back surface portion of the movable metallic mold 12.

[0043]As an injecting portion for supplying the molten metal to the cavity 16 of the die-cast manufacturing apparatus 10, molten supply means is disposed below the cavity 16. This is configured of first pressurization means 22 made of an injection sleeve 18 mounted passing horizontally through the fixed metallic mold 14 to ...

second embodiment

[0063]Next, in the above-described embodiment, the present invention will be described. FIG. 6 is an example in which the second pressurization means 30 is disposed in a branching runner. There has been a problem of easy occurrence of porosities when a molten metal injected from a branching runner 90a on the left side illustrated in FIG. 6 of these branching runners 90a to 90d solidifies within the product. Therefore, this branching runner 90a is selected as a runner coupled to the intended production portion, and after the first pressurization means 22 has injected a required amount of molten metal for a die-cast product 92, the second pressurization means 30 disposed in the selected branching runner 90a performs the secondary pressurization at a super high pressure that is approximately four times more of the primary pressurization. Obviously, it is needless to say that, also in this case, the casting is performed with the poppet valve 44 mounted on the pressure pin 34 substitutin...

third embodiment

[0064]FIG. 7 is a The pressure pin 34 may be in a direction parallel to the plunger operation direction of the first pressurization means 22 as in FIG. 6. In view of this, the rising runner portion 28 is flexed.

[0065]Furthermore, a new branching runner coupled to a portion where density improvement is desired is caused to perform oxygen supply and second pressurization to the cavity, and thus, a die-casting product in which blowholes and shrinkage are inhibited is manufacturable using the PF method and the runner pressurization.

TECHNICAL FIELD

[0001] The present invention relates to a die-cast manufacturing method and a die-cast manufacturing apparatus, and pressurization means, and, in particular, relates to a die-cast manufacturing method and a die-cast manufacturing apparatus, and pressurization means that enable simultaneously eliminating shrinkage and blowholes.BACKGROUND ART

[0002] A method for casting a die-cast product includes pushing a molten metal, such as aluminum, into a cavity made by a metallic mold by a plunger and taking out a product in a shape following the cavity. Generation of shrinkage or a blowhole during shaping for a product turns out to be a product defect, and therefore, the generation thereof must be inhibited.

[0003] There has been proposed a runner pressurization method as a countermeasure for shrinkage in a die-cast product, and there also has been proposed a PF method (Pore Free: pore free die casting method) as a countermeasure for blowholes.

[0004] As the former countermeasure, there has been proposed a method that further pressurizes a runner in line with operating to pressurize a plunger. As the latter countermeasure, the inside of the cavity of the metallic mold is preliminarily substituted with oxygen and a chemical reaction with a molten metal filling the cavity is caused, and thus, a finer product is made.

[0005] The runner pressurization method is a method that further pressurizes the molten metal supplied in a pressurized manner to the cavity through a sleeve by further pressurizing a runner portion directly connected to the cavity by a pressure pin (Patent Document 1). However, this method has failed to obtain an expected cavity pushing effect as the molten metal pushed by the runner pressurization flows backward and is pushed back to a plunger side. From such an aspect, there has appeared a technique that ensures obtaining the pushing effect by reducing a gap between the pressure pin and a pressurization passage (Patent Document 2), but it has failed to provide a countermeasure for blowholes.

[0006] There also has been proposed a PF method as a countermeasure for not generating blowholes as a product failure. This is to manufacture a pressure casting product by substituting the inside of the cavity of the metallic mold with oxygen and locally pressurizing the molten metal filling the cavity by a squeeze pin or the like as described in Patent Document 3. However, this has failed to provide a countermeasure for shrinkage.

[0007] Furthermore, there is known a method described in Patent Document 4 as a method that has combined the PF method as a usual method supplying oxygen from a sleeve port and a local squeeze method in a product. This ejects oxygen from a pouring gate of a sleeve and supplies the oxygen to the sleeve, the runner, and the cavity, thereby having a problem of a reduced oxygen concentration. The local squeeze method performed as a countermeasure for shrinkage has a possibility of making a hit mark on a product, which may interfere with an ejector pin for the product or a cooling passage.CITATION LISTPatent Literature

[0008] Patent Document 1: JP-A-2000-117411

[0009] Patent Document 2: JP-A-2011-224650

[0010] Patent Document 3: JP-A-2019-188459

[0011] Patent Document 4: JP-A-2004-223610DISCLOSURE OF THE INVENTIONProblems to be Solved by the Invention

[0012] The present invention focuses on the above-described problems, and it is an object of the present invention to enable achieving a PF method that supplies oxygen to a cavity without reducing oxygen concentration and to inhibit generation of shrinkage of an entire product in a runner pressurization.Solutions to the Problems

[0013] The present invention has been configured as follows in order to solve the above-described problems. It is to provide a die-casting method and a die-casting apparatus that enable producing a fine die-cast product in which blowholes and shrinkage are simultaneously inhibited by performing a preparation reaching a PF method by substituting the inside of a cavity with oxygen before molten metal injection by a plunger when molds are clamped, and subsequently solidifying the molten metal by secondarily pressurizing a runner at a high pressure and continuously pressurizing the molten metal after the molten metal injection by the plunger.

[0014] Specifically, a die-cast manufacturing method according to the present invention includes: injecting a molten metal from a sleeve by first pressurization means;

[0015] subsequently pressurizing a runner by second pressurization means; using a pressure pin of the second pressurization means to allow an oxygen supply passage provided in the pressure pin to supply oxygen through a distal end valve; and after the pressure pin of the second pressurization means is preliminarily moved to project into the runner, filling the cavity with the oxygen via the distal end valve to draw the pressure pin, subsequently filling the runner and the sleeve with oxygen, and afterwards, injecting the molten metal with the first pressurization means through the sleeve, and then performing the runner pressurization by the second pressurization means. It is sufficient that an orifice in a middle of a runner pressurization passage of the pressure pin of the second pressurization means is provided to allow preventing a gas and the molten metal from flowing backward.

[0016] Further, the present invention includes: injecting a molten metal from a sleeve by first pressurization means after molds are clamped; pressurizing a runner portion directly connected to a cavity by second pressurization means; providing an orifice in a runner pressurization passage of a pressure pin of the second pressurization means to prevent a gas and the molten metal from flowing backward; before the injection by the first pressurization means from the mold clamping starts, operating the pressure pin of the second pressurization means to move to a runner side and preventing the gas from flowing backward with the orifice while supplying oxygen to the cavity with an oxygen supply valve disposed in the pressure pin to return the pressure pin; after the molten metal injection by the first pressurization means, causing the orifice with the second pressurization means to prevent the molten metal from flowing backward while performing runner pressurization.

[0017] The die-cast manufacturing method according to the present invention includes: injecting a molten metal from a sleeve by first pressurization means after molds are clamped; and pressurizing a runner portion directly connected to a cavity by second pressurization means. The method performs steps of: a mold clamping operation; an oxygen supplying operation to the cavity from an oxygen supply valve disposed in the pressure pin of the second pressurization means while an orifice prevents a gas from flowing backward; a drawn-in operation of the pressure pin; a molten metal injection operation by the first pressurization means via the sleeve; and a runner pressurization operation by the second pressurization means by the pressure pin while the orifice prevents the molten metal from flowing backward.

[0018] In these cases, the pressure pin of the second pressurization means is formed with a poppet-type valve at a distal end portion, and a valve opening / closing operation thereof opens and closes an oxygen supply passage formed in a center portion to stop the supply of oxygen. The orifice is formed on a surface corresponding to the runner portion directly connected to the cavity in the runner to prevent the gas or the molten metal from flowing backward.

[0019] The molten metal is injected into the cavity via a plurality of branching runners, and the orifice is formed on a rising runner portion of a selected branching runner or on a surface corresponding to a neighboring portion of the rising runner portion to prevent the gas or the molten metal from flowing backward.

[0020] The pressure pin of the second pressurization means has a moving direction that is a direction intersecting with a plunger operation direction of the first pressurization means, or has a moving direction that is a direction parallel to a plunger operation direction of the first pressurization means.

[0021] The second pressurization to the cavity may be performed through a new branching runner coupled to a portion where a density improvement is desired.

[0022] A die-cast manufacturing method according to the present invention includes: when second pressurization means performs second pressurization through a runner directly connected to a cavity after first pressurization means injects a molten metal to clamped metallic molds, using an auxiliary runner disposed at a position where the molten metal filling the cavity by the first pressurization means overflows; after mold clamping, operating a pressure pin of the second pressurization means before the injection by the first pressurization means and preventing a gas from flowing backward with the orifice while supplying oxygen to the cavity by an oxygen supply valve disposed in the pressure pin to return the pressure pin; and after the pressurization by the first pressurization means is terminated, operating the second pressurization means to pressurize the cavity from the auxiliary runner.

[0023] A die-cast manufacturing apparatus according to the present invention includes: first pressurization means that injects a molten metal to a die-casting metallic mold; second pressurization means that pressurizes a runner communicated with a cavity; an oxygen supply passage formed with a pressure pin of the second pressurization means as a hollow pipe structure; and the valve disposed at a distal end of the pressure pin that opens and closes the oxygen supply passage. An orifice may be formed on a surface corresponding to the runner directly connected to the cavity. The pressure pin is inserted through the orifice.

[0024] A die-cast manufacturing apparatus according to the present invention includes: first pressurization means that injects a molten metal to a die-casting metallic mold; second pressurization means that pressurizes a runner communicated with a cavity; an orifice formed on a surface corresponding to the runner directly connected to the cavity, a pressure pin of the second pressurization means being inserted through the orifice; an oxygen supply passage internally formed as a hollow pipe structure of the pressure pin and a valve disposed in a distal end portion of the pressure pin, the valve opening and closing the oxygen supply passage.

[0025] In this case, the orifice is formed at proximity of a boundary between a sprue core runner portion leading the molten metal injection from the second pressurization means to the cavity and a rising runner portion.

[0026] The runner is formed of a plurality of branching runners, the orifice is formed on a surface corresponding to a selected branching runner, and a valved pressure pin of the second pressurization means is insertable into the orifice.

[0027] The valved pressure pin of the second pressurization means has a moving direction that is a direction intersecting with a plunger direction of the first pressurization means or has a moving direction that is a direction parallel to a plunger direction of the first pressurization means.

[0028] A new branching runner may be provided in the first pressurization means. The new branching runner being coupled to a portion where a density improvement is desired and second pressurization means having a valved pressure pin that moves in a direction identical to a direction of a flow of the molten metal within the new branching runner may be provided.

[0029] A die-cast manufacturing apparatus according to the present invention includes: first pressurization means that injects a molten metal to a die-casting metallic mold; second pressurization means that pressurizes a runner communicated with a cavity; the runner serving as an auxiliary runner disposed at a position where the molten metal filling the cavity by the first pressurization means overflows; an orifice through which a pressure pin of the second pressurization means is inserted, the orifice being formed on a surface corresponding to the runner directly connected to the cavity in the auxiliary runner; an oxygen supply passage internally formed as a hollow pipe structure of the pressure pin and a valve disposed in a distal end portion of the pressure pin, the valve opening and closing the oxygen supply passage; and control means that controls a sequence of operations of: after mold clamping, operating a pressure pin of the second pressurization means before the injection by the first pressurization means and preventing a gas from flowing backward by the orifice while supplying oxygen to the cavity by an oxygen supply valve disposed in the pressure pin to return the pressure pin; and after the pressurization by the first pressurization means is terminated, operating the second pressurization means to pressurize the cavity from the auxiliary runner.

[0030] The present invention is pressurization means for performing runner pressurization of a die-casting metallic mold. The pressurization means includes: a main actuator; a pressure pin operated in and out by the main actuator; a ring passage disposed inside the pressure pin; a poppet valve mounted on a top end surface of the pressure pin opening and closing the ring passage, the poppet valve having a diameter smaller than a diameter of the top end surface; a stem shaft that operates the poppet valve and forms the ring passage; and a secondary actuator that drives the stem shaft.Effects of the Invention

[0031] The above-described configuration ensures that the operation of the pressure pin substitutes the inside of the cavity with oxygen, and next, the molten metal is able to be secondarily pressurized while preventing the molten metal from flowing backward by the pressure pin after the molten metal injection by the plunger, and thus, the action by the former performs a PF method and the secondary pressurization by the latter enables manufacturing a fine die-cast product under a high pressure. In this case, disposing an orifice through which the pressure pin is inserted on a surface corresponding to a runner directly connected to the cavity enables preventing the oxygen gas and the molten metal from flowing backward. Thus, the PF method and the runner secondary pressurization are simultaneously achievable with one component, and a die-cast product in which generation of blowholes and shrinkage is prevented is completed.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG. 1 is a cross-sectional view of a relevant portion of a die-cast manufacturing apparatus according to an embodiment.

[0033] FIG. 2 is a cross-sectional view and a side view of a pressure pin used for the die-cast manufacturing apparatus.

[0034] FIG. 3 is a hydraulic system diagram to the pressure pin.

[0035] FIG. 4 is a cross-sectional view of a relevant portion of the die-casting apparatus illustrating an operational configuration of the pressure pin.

[0036] FIG. 5 is an operational configuration diagram illustrating another modification that supplies an oxygen gas.

[0037] FIG. 6 is a layout cross-sectional view of second pressurization means according to a second embodiment.

[0038] FIG. 7 is a layout cross-sectional view of second pressurization means according to a third embodiment.

[0039] FIG. 8 is a layout cross-sectional view of second pressurization means according to a fourth embodiment.

[0040] FIG. 9 is a layout cross-sectional view of second pressurization means according to a fifth embodiment.DESCRIPTION OF PREFERRED EMBODIMENTS

[0041] The following will describe a die-cast manufacturing method and a die-cast manufacturing apparatus according to embodiments of the present invention in detail with reference to the drawings. Note that the following description is merely an example, and the present invention can include various kinds of modifications as long as the gist of the present invention is not changed.

[0042] FIG. 1 illustrates a cross-sectional view of a relevant portion of a die-cast manufacturing apparatus according to a first embodiment. A die-cast manufacturing apparatus 10 includes a movable metallic mold 12 mounted on a movable plate and a fixed metallic mold 14 mounted on a fixed plate. The die-cast manufacturing apparatus 10 injects a molten metal into a cavity 16 formed by bringing the two metallic molds 12 and 14 in contact, and thus, a product in a shape following the cavity 16 is made. The product can be taken out of the cavity 16 by separating the metallic molds 12 and 14 and operating a squeeze pin disposed in a back surface portion of the movable metallic mold 12.

[0043] As an injecting portion for supplying the molten metal to the cavity 16 of the die-cast manufacturing apparatus 10, molten supply means is disposed below the cavity 16. This is configured of first pressurization means 22 made of an injection sleeve 18 mounted passing horizontally through the fixed metallic mold 14 to reach the cavity 16, a plunger 20 arranged within the injection sleeve 18, and a pressure device (not illustrated) located at the rear of the plunger 20 and able to push and pull the plunger 20.

[0044] A runner 24 that serves as a passage of the molten metal reaching the cavity 16 is formed in a direction of a front end of the injection sleeve 18. This runner 24 is made of a sprue core runner portion 26 approximately horizontally extended from the injection sleeve 18 and a rising runner portion 28 oriented upward so as to be directly connected to a lower portion of the cavity 16. The runner 24 is configured such that the molten metal extruded by the plunger 20 of the first pressurization means 22 is injected out to the cavity 16 after the molten metal passes through the sprue core runner portion 26 and is orientated upward by the rising runner portion 28.

[0045] The rising runner portion 28 in such a runner 24 is provided with second pressurization means 30 that secondarily pressurizes the molten metal in the cavity 16. This second pressurization means 30 is configured of a main actuator (hydraulic cylinder) 32 equipped in the lower portion of the metallic molds 12, 14 and a pressure pin (operational piston) 34 mounted so as to be moved in and out from a lower portion of the rising runner portion 28 to an upper portion by the main actuator 32. The pressure pin 34 has a diameter d made to be smaller than an inner diameter D of the rising runner portion 28 so as to allow the pressure pin 34 to slide up and down in the rising runner portion 28. Accordingly, a press-fitting amount of the pressure pin 34 into the rising runner portion 28 improves a product density by the cavity 16.

[0046] In the embodiment, in particular, an orifice 36 that reduces the inner diameter is formed in a side of the rising runner portion 28 (the part B in FIG. 1) that is above an intersecting portion (the section A to B in FIG. 1) between the rising runner portion 28 and the sprue core runner portion 26. This is a ring projection 38 having a rectangular cross-section formed in an inner diameter portion of the rising runner portion 28 and serves to make a metallic seal in a gap between the projection 38 and the pressure pin 34, which is achieved by adjusting a height of the projection 38 (that is, an inner diameter dimension of the rising runner portion 28) to the outer diameter d of the pressure pin 34 as close as possible. Specifically, the height of the ring projection 38 is determined such that, while it depends on the size of the cavity 16, a gap dimension Δ, which is ½ of the difference between the inner diameter D of the rising runner portion 28 and the outer diameter d of the pressure pin 34, to be ½ to ⅓ or less. That is, ½ of the difference between the inner diameter of the ring projection 38 and the outer diameter d of the pressure pin 34 is a gap dimension δ of a metallic seal portion, where δ=Δ×½, preferably δ=Δ×⅓, and the lower limit value is a value at which the metallic seal breaks. The ring projection 38 has an axial length L of approximately 10 mm, which ensures reliable metallic sealing.

[0047] In the embodiment, as seen in FIG. 2, the pressure pin 34 has a stem shaft 40 axially inserted through an inside of the pin body to internally form a ring passage 42. The ring passage 42 has a hollow pipe structure opened on a top end surface of the pressure pin 34. On the top end surface of the pressure pin 34, a poppet valve 44 having a diameter smaller than the diameter of the pressure pin 34 is connected to an upper end of the stem shaft 40 so as to allow opening and closing the ring passage 42. The poppet valve 44 serves to open and close the ring passage 42 in association with the up and down movement of the stem shaft 40. The poppet valve 44 is flush with the top end surface of the pressure pin 34 when the valve is closed, and projects from the top end surface of the pressure pin 34 separating away from a V-shaped valve seat 46 by being pushed out by the stem shaft 40 to release the ring passage 42 on the top end surface of the pressure pin 34 when the valve is opened. A lower portion of the stem shaft 40 is connected to a secondary actuator (hydraulic cylinder) 48 disposed inside the pressure pin 34. Accordingly, the secondary actuator 48 moved up and down within the pressure pin 34 opens and closes the poppet valve 44 through the stem shaft 40.

[0048] In order to cause the pressure pin 34 to perform these sequence of operations, the oxygen / hydraulic system illustrated in FIG. 3 is used. First, the ring passage 42 disposed in the pressure pin 34 is connected to an oxygen supply port 50, and is able to supply oxygen to the cavity 16 through the pressure pin 34 while the valve is open from a tank 52 as an oxygen supply source. In the course of the passage from the tank 52 to the oxygen supply port 50, there are provided in parallel a flow passage 58 in which a large flow rate control valve 54 and an opening / closing valve 56 are disposed and a flow passage 64 in which a small flow rate control valve 60 and an opening / closing valve 62 are disposed, which allows adjustment of a supply amount of the oxygen.

[0049] Next, the configuration for causing the pressure pin 34 to perform the secondary pressurization and the configuration for opening and closing the poppet valve 44 mounted on the pressure pin 34 are as follows. The hydraulic pressure is generated from a hydraulic tank 66 using a pump 68, and the pump 68 is connected to the main actuator 32 via a direction switching valve 70 so as to drive the pressure pin 34 to move up and down. The hydraulic pressure of the pump 68 is also used for opening and closing the valve, and the hydraulic pressure is introduced to the secondary actuator 48 in a manner switchable up and down by a direction switching valve 72. This causes the main actuator 32 to move the pressure pin 34 up, and subsequently the secondary actuator 48 to open the poppet valve 44, thereby enabling the oxygen to be introduced into the cavity 16. Raising only the pressure pin 34 in a state where the oxygen supply is stopped by driving the secondary actuator 48 down to close the poppet valve 44 enables the second pressurization means 30 to cause the pressure pin 34 to operate to push the molten metal.

[0050] Note that, in a hydraulic pressure discharge path 74 when the pressure pin 34 is raised, a piston driving amount of the main actuator 32, eventually a stroke of the pressure pin 34 is measured from a discharged amount of oil. This stroke detecting device 76 is configured of a cylinder piston structure, and this is configured of a cylinder body 78 and a piston 80 slidable within the cylinder body 78. One chamber partitioned by the piston 80 in the cylinder body 78 is connected to a hydraulic oil outlet of the pressure pin 34, and the other chamber is connected to the direction switching valve 70. This causes the hydraulic oil exiting from the main actuator 32 to enter the stroke detecting device 76 by the exiting amount, and thus, the piston 80 is moved. The piston 80 is integrally provided with a rod 82, and this projects from one end portion of the cylinder body 78 and is coupled to a linear-type potentiometer 84. An operation starting point of the rod 82 is in one end portion side (the left end in FIG. 3) of the cylinder body 78, and at this time, it corresponds to a pressurization starting point (the lower end in FIG. 3) of the piston of the pressure pin 34. The linear-type potentiometer 84 is arranged parallel to the rod 82, moves with the rod 82, and obtains its movement distance. In such a stroke detecting device 76, its piston 80 is provided with a through-hole communicating through the chambers partitioned by the piston 80, and a check valve 86 and an orifice (throttle valve) 88 are mounted in this through-hole. This check valve 86 is a one-way valve that blocks the flow of the hydraulic oil discharged to the chamber in a side of the direction switching valve 70 from the chamber into which the hydraulic oil of the pressure pin 34 enters and allows the flow in the opposite direction. Thus, the whole amount of the hydraulic oil when the pressure pin 34 performs the pressurization operation is detected by the stroke detecting device 76. The orifice (throttle valve) 88 restricts a flow rate of the check valve 86. Since a weak cracking pressure (spring force) of the check valve 86 causes the hydraulic oil to flow through the check valve with the piston stopped, it is solvable by reducing the flow rate.

[0051] Note that control means that controls the operation system as described above is additionally disposed to control it to properly operate.

[0052] A manufacturing process by thus configured die-cast manufacturing apparatus 10 is illustrated in FIG. 4. The orifice 36 is disposed in the runner pressurization passage of the pressure pin 34 of the second pressurization means 30, and thus, the backward flow of the gas and the molten metal is preventable. First, the molds are clamped. When the molds are being clamped, the plunger 20 is advanced to make an occlusion so as to stop the oxygen from exiting from the sprue (FIG. 4(1)). At this time, the pressure pin 34 is at a standby position, that is, is in a drawn-in state from the rising runner portion 28.

[0053] After the molds are clamped, before the injection by the first pressurization means 22, the pressure pin 34 of the second pressurization means 30 is moved to the runner side (FIG. 4(2)), and after it passes the orifice 36, the poppet valve 44 is opened to supply oxygen to the cavity 16 from the released ring passage 42 disposed in the pressure pin 34 while the backward flow of the gas is prevented with the orifice 36 (FIG. 4(3)). The gas remaining in the cavity 16 is discharged by the oxygen and discharged from an air vent.

[0054] After an oxygen filling state is obtained, the poppet valve 44 is opened and the pressure pin 34 is returned to the standby position while the oxygen is discharged (FIG. 4(4)), and the poppet valve 44 is closed at the standby position (FIG. 4(5)). At this time, while the plunger 20 returns to the injection position, the internal gas is discharged from the pouring gate by the oxygen.

[0055] After the pressure pin 34 is returned to the standby position, the first pressurization means 22 causes the plunger 20 to inject the molten metal, thus performing casting (FIG. 4(6)). After the plunger 20 reaches the advance limit, the runner pressurization is performed while the second pressurization means 30 causes the orifice 36 to prevent the molten metal from flowing backward (FIG. 4(7)). For the casting pressure by the cavity 16 at this time, a pressure four times higher than the conventional pressure can be applied.

[0056] Thus, in the embodiment, while first, the molds are clamped and the plunger 20 is in an advanced state, the pressure pin 34 is passed through the orifice 36, and the poppet valve 44 disposed on the top end surface of the pressure pin 34 is opened to blow the oxygen out, and thus, the internally remaining gas is discharged to the air vent to allow the cavity to be filled with the oxygen at a high concentration. Subsequently, the reaction with the molten metal injected into the cavity 16 can be sufficiently caused.

[0057] The runner portion pressurization is also possible by using the backward flow prevention effect by the orifice 36, and this reaches an applied pressure four times more than the conventional applied pressure, thus being considerably beneficial. That is, the second pressurization means 30 thus configured provides a shielding function with a portion of the metallic seal formed of the molten metal in the upper side entering into the portion of the orifice 36 when the pressure pin 34 approaches the ring projection 38 after the plunger 20 of the first pressurization means 22 has completed the injection. In view of this, this metallic seal at the portion of the orifice 36 increases the molten metal filling amount into the cavity 16, and the pushing operation by the pressure pin 34 lengthens the stroke, then, the operation is completed. As the result, when a product made in an ordinary casting method without the runner pressurization is set to “0,” a conventional local squeeze method that pressurizes a center portion of the cavity 16 observed an increase of +4 g (0.5%), and the runner pressurization method of this embodiment method observed an increase of +14 g (1.7%). Thus, the embodiment presented a remarkable effect.

[0058] Next, another method for achieving an oxygen supply method for performing the PF method will be described with reference to FIG. 5. FIG. 5(1) illustrates a mold opened state where the pressure pin 34 is drawn from the rising runner portion 28 and is in a standby state. The movable metallic mold 12 and the fixed metallic mold 14 in the right and left are in a separated state, and the two-dot chain line in the center portion indicates a die-cast product, a runner, and a biscuit. When the mold clamping operation starts from such a state, as illustrated in FIG. 5(2), after the product is taken out, the hydraulic pressure is supplied to the secondary actuator 48 of the second pressurization means 30 while a spray of a mold release agent is operating, and the pressure pin 34 is advanced to the advance limit. As illustrated in FIG. 3(3), the mold clamping proceeds simultaneously with this, and the poppet valve 44 is opened in the middle of this mold clamping to discharge oxygen. This oxygen enters the cavity 16 and the remaining gas flows into the outside air through the air vent in the upper. The machining operation takes place while the oxygen is discharged, and as illustrated in FIG. 5(4), the discharge amount of the oxygen is switched to a small flow rate at the lower limit, the sleeve side is also filled up with the oxygen to prevent the air from entering the sleeve 18 from the pouring gate in the sleeve 18 side, and the valve 44 is closed. The oxygen supply for performing such a PF method is included.

[0059] Note that while the ring projection 38 forming the orifice 36 may have a square cross-sectional surface as in the embodiment, it is also allowed to have a cross-sectional shape in a V shape or an arc shape. In this case, if the tip of the V shape or the arc shape is sharp, the metallic seal is not taken, therefore, the shape of sharpened tip end is preferred.

[0060] The ring projection 38 forming the orifice 36 can be provided with cooling means. This can be a horizontal system, a water-cooling system, or an oil-cooling system, and cooling is preferably performed when the injection by the first pressurization means 22 is completed, and the pressure by the second pressurization means 30 is applied to the ring projection 38. Thus, the metallic seal is easily formed.

[0061] In the above-described embodiment, the ring projection 38 forming the orifice 36 may be formed as another component, and may be mounted in a fitting-in structure when the runner 24 is formed. This is because installation to the rising runner portion 28 having a semicircle structure can be easily performed since the runner 24 has a structure dividable on a splitting line of the metallic molds.

[0062] The above-described embodiment can be applied to pushing a runner of a hot chamber or to the case of forming a plastic.

[0063] Next, in the above-described embodiment, the second embodiment of the present invention will be described. FIG. 6 is an example in which the second pressurization means 30 is disposed in a branching runner. There has been a problem of easy occurrence of porosities when a molten metal injected from a branching runner 90a on the left side illustrated in FIG. 6 of these branching runners 90a to 90d solidifies within the product. Therefore, this branching runner 90a is selected as a runner coupled to the intended production portion, and after the first pressurization means 22 has injected a required amount of molten metal for a die-cast product 92, the second pressurization means 30 disposed in the selected branching runner 90a performs the secondary pressurization at a super high pressure that is approximately four times more of the primary pressurization. Obviously, it is needless to say that, also in this case, the casting is performed with the poppet valve 44 mounted on the pressure pin 34 substituting the internal gas with oxygen in advance. The moving direction of the pressure pin 34 in this case is a direction intersecting with a plunger operation direction of the first pressurization means.

[0064] FIG. 7 is a third embodiment. The pressure pin 34 may be in a direction parallel to the plunger operation direction of the first pressurization means 22 as in FIG. 6. In view of this, the rising runner portion 28 is flexed.

[0065] Furthermore, a new branching runner coupled to a portion where density improvement is desired is caused to perform oxygen supply and second pressurization to the cavity, and thus, a die-casting product in which blowholes and shrinkage are inhibited is manufacturable using the PF method and the runner pressurization.

[0066] FIG. 8 illustrates an apparatus according to a fourth embodiment. The runner subject to the second pressurization serves as a gas purge runner 94 for the cavity 16 (alternatively, a die-cast product) by the first pressurization means 22, and the orifice 36 through which the pressure pin 34 of the second pressurization means 30 is inserted is disposed on a surface corresponding to a runner directly connected to the cavity 16 in this gas purge runner 94. There are disposed the ring passage (oxygen supply passage) 42 formed inside the hollow pipe structure of the pressure pin 34 and the poppet valve 44 that is disposed at a distal end portion of the pressure pin 34 and opens and closes the ring passage (oxygen supply passage). When the molds are clamped, before the injection by the first pressurization means 22, the pressure pin 34 of the second pressurization means 30 is operated and the orifice 36 prevents the gas from flowing backward, and the poppet valve 44 disposed in the pressure pin 34 supplies oxygen to the cavity 16. This oxygen fills the cavity 16, and the gas that has previously filled the cavity 16 is discharged from a molten metal filling port opened in a sleeve through an air vent and via the branching runners 96a to 96d. Afterwards, the pressure pin 34 is returned to the standby position, and after molten metal filling by the first pressurization means 22, the second pressurization means 30 is operated again after the pressurization is terminated to pressurize the cavity 16 from the gas purge runner 94. There is provided control means (not illustrated) that controls this sequence of operations. This embodiment also achieves the PF method by oxygen supply to the cavity 16 and the secondary pressurization by the second pressurization means 30, thereby enabling obtainment of a die-cast product in which blowholes and shrinkage are improved.

[0067] FIG. 9 illustrates a fifth embodiment. This is applied to, in particular, a case where the secondary pressurization is partially performed in the fourth embodiment, and while the gas purge runner 94 is reached through a plurality of branching gas purge runners 94a, 94b, 94c, the branching gas purge runner 94c is used for disposing the second pressurization means 30. The orifice 36 is also disposed in this, and inserting the pressure pin 34 through the orifice 36 portion enables providing a similar effect to that of the above-described embodiments.

[0068] In the present invention, the above-described poppet valve 44 is set to be flush with the top end surface of the pressure pin 34. This poppet valve 44 requires a runner pressurization stroke of an amount of a height H of a flange if the poppet valve 44 has the same diameter as that of the pressure pin 34 and has a flange portion, but it has a diameter smaller than that of the pressure pin 34, and therefore, it can supply an oxygen gas with the shortest stroke after improvement. If there is a flange when pulling operation is performed after casting and runner pressurization, the amount of the height H is covered with aluminum, and therefore, it is anticipated that the poppet valve 44 is not able to be pulled out. This possibility is also eliminated after the modification. Furthermore, when the upper end portion of the pressure pin 34 is provided with a flanged valve, a distal end valve is rubbed because there is not much diameter difference with the orifice 36 when the pressure pin 34 is operated. However, since the valve 44 is formed to have a diameter smaller than that of the top end surface of the pressure pin 34, such an event is also preventable.INDUSTRIAL APPLICABILITY

[0069] The present invention is a method and an apparatus that enable pressurizing a runner by second pressurization means subsequently to plunger pressurization by first pressurization means in die-cast manufacturing, enable manufacturing a product without generating hit marks on the product caused by a PF method by oxygen supply in the former stage and a runner pressurization in the latter stage, and enable improving a product density.DESCRIPTION OF REFERENCE SIGNS10 die-cast manufacturing apparatus, 12 movable metallic mold, 14 fixedmetallic mold, 16 cavity, 18 injection sleeve, 20 plunger, 22 firstpressurization means, 24 runner, 26 sprue core runner portion, 28 risingrunner portion, 30 second pressurization means, 32 main actuator,34 pressure pin, 36 orifice, 38 ring projection, 40 stem shaft,42 ring passage, 44 poppet valve, 46 valve seat, 48 secondary actuator(hydraulic cylinder) for poppet, 50 oxygen supply port, 52 tank (oxygensupply source), 54 large flow rate control valve, 56 opening / closing valve,58 flow passage, 60 small flow rate control valve, 62 opening / closingvalve, 64 flow passage, 66 hydraulic tank, 68 pump, 70 directionswitching valve, 72 direction switching valve, 74 hydraulic pressuredischarge path, 76 stroke detecting device, 78 cylinder body, 80 piston,82 rod, 84 potentiometer, 86 check valve, 88 orifice, 90a to 90d branchingrunner, 92 die-cast product, 94 gas purge runner, 94a to 94c branching gaspurge runner, 96a to 96c branching runner.

Examples

first embodiment

[0042]FIG. 1 illustrates a cross-sectional view of a relevant portion of a die-cast manufacturing apparatus according to a A die-cast manufacturing apparatus 10 includes a movable metallic mold 12 mounted on a movable plate and a fixed metallic mold 14 mounted on a fixed plate. The die-cast manufacturing apparatus 10 injects a molten metal into a cavity 16 formed by bringing the two metallic molds 12 and 14 in contact, and thus, a product in a shape following the cavity 16 is made. The product can be taken out of the cavity 16 by separating the metallic molds 12 and 14 and operating a squeeze pin disposed in a back surface portion of the movable metallic mold 12.

[0043]As an injecting portion for supplying the molten metal to the cavity 16 of the die-cast manufacturing apparatus 10, molten supply means is disposed below the cavity 16. This is configured of first pressurization means 22 made of an injection sleeve 18 mounted passing horizontally through the fixed metallic mold 14 to ...

second embodiment

[0063]Next, in the above-described embodiment, the present invention will be described. FIG. 6 is an example in which the second pressurization means 30 is disposed in a branching runner. There has been a problem of easy occurrence of porosities when a molten metal injected from a branching runner 90a on the left side illustrated in FIG. 6 of these branching runners 90a to 90d solidifies within the product. Therefore, this branching runner 90a is selected as a runner coupled to the intended production portion, and after the first pressurization means 22 has injected a required amount of molten metal for a die-cast product 92, the second pressurization means 30 disposed in the selected branching runner 90a performs the secondary pressurization at a super high pressure that is approximately four times more of the primary pressurization. Obviously, it is needless to say that, also in this case, the casting is performed with the poppet valve 44 mounted on the pressure pin 34 substitutin...

third embodiment

[0064]FIG. 7 is a The pressure pin 34 may be in a direction parallel to the plunger operation direction of the first pressurization means 22 as in FIG. 6. In view of this, the rising runner portion 28 is flexed.

[0065]Furthermore, a new branching runner coupled to a portion where density improvement is desired is caused to perform oxygen supply and second pressurization to the cavity, and thus, a die-casting product in which blowholes and shrinkage are inhibited is manufacturable using the PF method and the runner pressurization.

Claims

1. A die-cast manufacturing method comprising:injecting a molten metal from a sleeve by first pressurization means;subsequently pressurizing a runner by second pressurization means;using a pressure pin of the second pressurization means to allow an oxygen supply passage provided in the pressure pin to supply oxygen through a distal end valve; andafter the pressure pin of the second pressurization means is preliminarily moved to project into the runner, filling the cavity with the oxygen via the distal end valve to draw the pressure pin, and subsequently injecting the molten metal with the first pressurization means through the sleeve, and afterwards, performing the runner pressurization by the second pressurization means.

2. The die-cast manufacturing method according to claim 1, whereinproviding an orifice in a middle of a runner pressurization passage of the pressure pin of the second pressurization means to prevent a gas and the molten metal from flowing backward.

3. A die-cast manufacturing method comprising:injecting a molten metal from a sleeve by first pressurization means after molds are clamped;pressurizing a runner portion directly connected to a cavity by second pressurization means;providing an orifice in a runner pressurization passage of a pressure pin of the second pressurization means to allow preventing a gas and the molten metal from flowing backward;before the injection by the first pressurization means from the mold clamping starts, operating the pressure pin of the second pressurization means to move to a runner advance limit and preventing the gas from flowing backward with the orifice while supplying oxygen to the cavity with an oxygen supply valve disposed in the pressure pin to return the pressure pin; andafter the molten metal injection by the first pressurization means, causing the orifice with the second pressurization means to prevent the molten metal from flowing backward, and performing runner pressurization.

4. A die-cast manufacturing method comprising:injecting a molten metal from a sleeve by first pressurization means after molds are clamped; andpressurizing a runner portion directly connected to a cavity by second pressurization means, whereinthe method performs steps of:an oxygen supplying operation to the cavity from an oxygen supply valve disposed in a pressure pin of the second pressurization means while an orifice prevents a gas from flowing backward, together with a mold clamping starting operation;a molten metal injection operation by the first pressurization means via the sleeve; anda runner pressurization operation by the second pressurization means by the pressure pin while the orifice prevents the molten metal from flowing backward.

5. The die-cast manufacturing method according to claim 1, whereinthe pressure pin of the second pressurization means is provided with a poppet-type valve at a distal end portion, and a valve opening / closing operation thereof opens and closes an oxygen supply passage formed in a center portion.

6. The die-cast manufacturing method according to claim 5, whereinthe poppet-type valve has a diameter smaller than an outer diameter of the pressure pin, and is opened and closed on a top end surface of the pressure pin.

7. The die-cast manufacturing method according to claim 1, whereinthe orifice is formed on a surface corresponding to a runner portion directly connected to the cavity in the runner to prevent the gas or the molten metal from flowing backward.

8. The die-cast manufacturing method according to claim 1, whereinthe molten metal is injected into the cavity via a plurality of branching runners, and the orifice is formed on a rising runner portion of a selected branching runner or on a surface corresponding to a neighboring portion of the rising runner portion to prevent the gas or the molten metal from flowing backward.

9. The die-cast manufacturing method according to claim 1, whereinthe pressure pin of the second pressurization means has a moving direction that is a direction intersecting with a plunger operation direction of the first pressurization means.

10. The die-cast manufacturing method according to claim 1, whereinthe pressure pin of the second pressurization means has a moving direction that is a direction parallel to a plunger operation direction of the first pressurization means.

11. The die-cast manufacturing method according to claim 1, whereina new branching runner coupled to a portion where a density improvement is desired performs second pressurization to the cavity.

12. A die-cast manufacturing method comprisingwhen second pressurization means performs second pressurization through a runner directly connected to a cavity after first pressurization means injects a molten metal to clamped metallic molds,using the runner as a gas purge runner of the cavity by the first pressurization means;after mold clamping starts, operating a pressure pin of the second pressurization means before the injection by the first pressurization means and preventing a gas from flowing backward with an orifice while supplying oxygen to the cavity by an oxygen supply valve disposed in the pressure pin to return the pressure pin; andafter the pressurization by the first pressurization means is terminated, operating the second pressurization means to pressurize the cavity from the gas purge runner.

13. A die-cast manufacturing apparatus comprising:first pressurization means that injects a molten metal to a die-casting metallic mold;second pressurization means that pressurizes a runner communicated with a cavity;an oxygen supply passage formed with a pressure pin of the second pressurization means as a hollow pipe structure; anda valve disposed at a distal end of the pressure pin that opens and closes the oxygen supply passage.

14. The die-cast manufacturing apparatus according to claim 13, further comprisingproviding an orifice formed on a surface corresponding to the runner directly connected to the cavity, the pressure pin being inserted through the orifice.

15. A die-cast manufacturing apparatus comprising:first pressurization means that injects a molten metal to a die-casting metallic mold;second pressurization means that pressurizes a runner communicated with a cavity;an orifice formed on a surface corresponding to the runner directly connected to the cavity, a pressure pin of the second pressurization means being inserted through the orifice;an oxygen supply passage internally formed as a hollow pipe structure of the pressure pin and a valve disposed in a distal end portion of the pressure pin, the valve opening and closing the oxygen supply passage.

16. The die-cast manufacturing apparatus according to claim 13, whereinthe orifice is formed at proximity of a boundary between a sprue core runner portion leading the molten metal injection from the second pressurization means to the cavity and a rising runner portion.

17. The die-cast manufacturing apparatus according to claim 13, whereinthe runner is formed of a plurality of branching runners, the orifice is formed on a surface corresponding to a selected branching runner, and a valved pressure pin of the second pressurization means is insertable into the orifice.

18. The die-cast manufacturing apparatus according to claim 13, whereinthe valved pressure pin of the second pressurization means has a moving direction that is a direction intersecting with a plunger direction of the first pressurization means.

19. The die-cast manufacturing apparatus according to claim 13, whereinthe valved pressure pin of the second pressurization means has a moving direction that is a direction parallel to a plunger direction of the first pressurization means.

20. The die-cast manufacturing apparatus according to claim 13, further comprisinga new branching runner in the first pressurization means, the new branching runner being coupled to a portion where a density improvement is desired; andsecond pressurization means having a valved pressure pin that moves in a direction identical to a direction of a flow of the molten metal within the new branching runner.

21. A die-cast manufacturing apparatus comprising:first pressurization means that injects a molten metal to a die-casting metallic mold;second pressurization means that pressurizes a runner communicated with a cavity;the runner serving as an auxiliary runner disposed at a position where the molten metal filling the cavity by the first pressurization means overflows;an orifice through which a pressure pin of the second pressurization means is inserted, the orifice being formed on a surface corresponding to the runner directly connected to the cavity in the auxiliary runner;an oxygen supply passage internally formed as a hollow pipe structure of the pressure pin and a valve disposed in a distal end portion of the pressure pin, the valve opening and closing the oxygen supply passage; andcontrol means that controls a sequence of operations of: after mold clamping starts, and before the injection by the first pressurization means, operating a pressure pin of the second pressurization means and preventing a gas from flowing backward by the orifice while supplying oxygen to the cavity by an oxygen supply valve disposed in the pressure pin to return the pressure pin; and after the pressurization by the first pressurization means is terminated, operating the second pressurization means to pressurize the cavity from the auxiliary runner.

22. (canceled)

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