JPH0724562A - Production of cast product small in quantity of mixed oxide - Google Patents

Abstract

PURPOSE:To prevent the entrapment of oxide by raising a molten metal buffering plate matched with rising speed of the molten metal surface after pouring the molten metal from the upper part of an injection sleeve, positioning the molten metal surface above the buffering plate and taking out the remaining oxide on the buffering plate together with the buffering plate. CONSTITUTION:The lower end part of a hollow shifting shaft 64 supporting the molten metal buffering plate 62 is opened. Further, at the time of pouring a prescribed quantity of molten aluminum alloy into the injection sleeve 24 from a ladle after blowing oxidation-preventing gas from the lower end part of the shifting shaft, the molten metal is stored in the injection sleeve 24. The produced oxide is stuck to the upper surface of the molten metal buffering plate 62 and taken out together with the molten metal buffering plate 62 by positioning the molten metal upper surface above the upper surface of the molten metal buffering plate 62 before completing the pouring of molten metal. By this method, oxide is hardly generated and the entrapment of the oxide into molten metal can be prevented so that a cast product having excellent quality can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cast product containing a small amount of an oxide so as to obtain a cast product containing a small amount of an oxide and excellent in mechanical properties.

[0002]

2. Description of the Related Art FIG. 10 is a front view of a conventional biscuit. An injection molding device such as a die casting machine includes a fixed mold attached to a fixed plate and a movable mold attached to a movable plate, and a joint portion between these molds clamped,
A cavity is formed. In addition, a fixed sleeve, which communicates with the cavity through a gate, is fitted in the sleeve hole of the fixed mold, and the injection sleeve of the injection cylinder supported by the fixed plate is attached to and detached from this fixed sleeve. Freely joined. With this configuration, when the molten metal is supplied to the injection sleeve and joined to the fixed sleeve, and the plunger tip provided in the injection cylinder is moved forward by hydraulic pressure or the like to push the molten metal in the injection cylinder, the molten metal is It is injected into the cavity through the fixed sleeve and the gate.

Since the molten metal in the cavity is solidified into a product, the mold is opened and the product is taken out.
The surplus casting material is separated from the product and left in the injection sleeve and the gate. That is, when the molten metal solidifies, a large-diameter thin columnar molten metal solidified material generally called a biscuit remains in the mold cavity, and also protrudes from the center of the molten metal solidified material in the gate together with the molten metal solidified material. A small-diameter cylindrical solidified metal remains (hereinafter, the entire cast surplus material consisting of the solidified solidified metal in the sleeve and the solidified solidified material in the gate is called a biscuit. The solidified solidified metal in the sleeve is a large diameter member. 72, and the molten metal solidified material in the gate is referred to as a small diameter member 73). When casting, if non-metallic inclusions such as molten oxide enter the cavity,
Since the quality of the product deteriorates, generally, the gate shown in FIG.
There is a case where the wire netting denoted by reference numeral 74 is loaded for each shot. Then, this wire net is left embedded in the small diameter member. The biscuit 71 is separated from the cast product thus formed.

[0004]

However, when the metal net is loaded into the gate from below as in the prior art, and the aluminum alloy poured into the injection sleeve is pushed up by the plunger tip to fill the mold cavity, The oxides and non-metal inclusions on the surface of the molten metal prevent a part of mixing into the product by the metal net 74, but the remaining oxides and non-metallic inclusions are finely crushed by the metal net 74 and filled in the cavity together with the molten metal. It As a result, good mechanical properties were obtained. However, the conventional biscuit 1 is integrally formed with the large diameter member 2 and the small diameter member 3 as described above, and the wire net 4 remains embedded in the small diameter member 3 which is the solidified material in the gate. However, there is a problem that the yield of the material is poor because it cannot be recovered and reused as it is.

In view of the above conventional problems, the present invention has an object to provide a method for producing a cast product containing a small amount of oxide mixed in the product during high pressure casting of an aluminum alloy or a magnesium alloy. is there.

[0006]

In order to solve such a problem, in the method for manufacturing a cast product containing a small amount of oxide according to the present invention, a molten metal buffer plate having an annular gap between vertical injection sleeves. Is fixed to the tip of a hollow moving shaft that moves up and down coaxially with the injection sleeve, and an antioxidant gas is blown while being positioned at an appropriate height inside the injection sleeve, and then above the injection sleeve. After pouring more toward the molten metal buffer plate, while flowing down from the annular gap,
The molten metal buffer plate is raised in accordance with the rising speed of the molten metal, and the molten surface is positioned above the buffer plate before the completion of pouring to buffer the oxide remaining on the buffer plate. I took it out together with the board.

[0007]

[Function] The hollow moving shaft for supporting the molten metal buffer plate is opened at the lower end, and is positioned at a predetermined height with an appropriate annular gap provided between the molten metal buffer plate and the molten metal buffer plate inserted into the injection sleeve. I will let you. Next, blow an antioxidant gas from the lower end of the moving shaft to make the atmosphere of the antioxidant gas in the injection sleeve, and then pour a desired amount of molten aluminum alloy from the ladle to the injection sleeve. After dropping onto the buffer plate, it flows down through the annular gap on the inner wall surface of the injection sleeve as a rectifying flow, and is stored in the injection sleeve. Therefore, the molten metal poured into the injection sleeve is prevented from scattering with turbulence, and the molten metal is less likely to be newly oxidized in the injection sleeve. By placing the upper surface of the molten metal above the upper surface of the molten metal buffer plate before pouring is completed, the generated oxide is attached to the upper surface of the molten metal buffer plate and is taken out together with the molten metal buffer plate.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete embodiment of a method for producing a cast product having a small amount of mixed oxide according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a front view of a vertical casting die casting machine, FIG. 2 is a vertical sectional view of a vertical injection device, FIG. 3 is a sectional front view of an injection sleeve having an inert gas blowing device, and FIGS. 8 is an explanatory view showing a state of pouring molten metal into the injection sleeve according to the embodiment of the present invention, and FIG. 9 is another embodiment similar to the embodiment of the present invention.

In the figure, a pit 1 having a rectangular shape in plan view is provided below the floor, and both ends of this pit 1 are
A pair of machine bases 2 each having a frame shape made of a steel plate, a shaped steel or the like extend on the floor surface and stand upright. One end of each of the machine bases 2 has a fixed platen formed in a substantially square shape. 3 is placed and its leg portions 3a are fixed by bolting.

An end platen 4 is erected and fixed to the other end of the machine base 2 so as to be movable and adjustable. The fixed platen 3 and the end platen 4 are four corners with four tie rods 5. After being connected and adjusted for movement, they are fixed with a nut 6. Numeral 7 is a movable platen which is fitted into the tie rods 5 at the four corner holes so as to be able to move forward and backward with respect to the fixed platen 3. The movable platen 7 is provided between the piston rod 9 of the mold clamping cylinder 8 and the toggle mechanism 10. The piston plate 9 is moved forward and backward by hydraulic pressure to move forward and backward with respect to the fixed platen 3.

A fixed mold 11 having cavities 11a, 12a and a biscuit portion 15 and a movable mold 12 are mounted on the fixed platen 3 and the movable platen 7, respectively, and driven by a mold clamping cylinder 8 to move the movable platen. The mold is clamped as shown in FIG. 1 by advancing the mold 7 from the mold open state.

Next, a vertical casting type injection device 13 arranged in the pit 1 will be described. Reference numeral 20 denotes an injection cylinder pivotally supported by a seat 18 fixedly provided on the bottom surface of the pit 1 via a pin 19, and the injection cylinder 20, the docking frame 22, and the injection sleeve 24 are sequentially arranged from the lower side. It has a staircase configuration. A piston 26 is installed in the injection cylinder 20.
A rod 28 extending upward is connected to the.
The docking frame 22 is provided with a cylinder hole 30 extending in the vertical direction, a docking ram 32 is inserted into the cylinder hole 30, and the lower end of the docking ram 32 is a flange 34 formed on the upper surface of the injection cylinder 20.
Is stuck to.

The injection sleeve 24 is connected to the upper side of the docking frame 22 via a connecting member 36, and the upper end thereof can be inserted into the lower end of the biscuit portion 15. A plunger tip 38 is slidably installed in the injection sleeve 24, and a lower end of a plunger 40 holding the plunger tip 38 is a coupling 42.
It is connected to the upper end of the rod 28 via. A tilting cylinder 44 is pivotally supported by a side wall of the pit 1 via a seat 46 and a pin 48, and a rod 52 connected to a piston 50 of the tilting cylinder 44.
Has its tip pivotally attached to the side surface of the flange 34 of the injection cylinder 20 via a joint 54 and a pin 56.

Reference numeral 60 shown in FIG. 3 is an oxide removing device, which comprises a molten metal buffer plate 62, a cover 63, and a moving shaft 64. The molten metal buffer plate 62 serves to straighten the molten metal 68 poured from the ladle 66 without causing a turbulent flow such as a twist to flow down the inner wall surface of the injection sleeve 24. The center portion of the molten metal buffer plate 62 and the tip of the hollow moving shaft 64 are fixed in the orthogonal direction, and the lower end 64a of the moving shaft 64 is opened. Also the moving axis 6
The other end of 4 is vertically movable in the axial direction of the injection sleeve 24 while holding an oxide removing device 60 (not shown). A cover 63 having an inner diameter portion that can be engaged with the outer diameter portion of the injection sleeve 24 is attached in the middle of the moving shaft 64 by upper and lower surface nuts 63a and 63b, and the shaft of the injection sleeve 24 of the molten metal buffer plate 62 is attached. The height of the direction can be adjusted. Reference numeral 61 is a pouring port, and 63C is a projecting portion, which is locked to the upper end of the injection sleeve 24 and regulates the lower limit of the cover 63. Above the moving shaft 64, an inert gas introduction tube 64b such as N2 gas is connected to an inert gas supply source (not shown), and a hollow portion 64c and a lower end portion 64a are provided in the central axial direction of the moving shaft 64. Is blown into the injection sleeve 24.

The projected area A1 of the molten metal buffer plate 62 is 60 to 95% of the sectional area A2 of the injection sleeve 24, preferably 75 to 9
A flat plate having a diameter of 0% is used. When the projected area A1 of the molten metal buffer plate 62 is 60% or less of the sectional area A2 of the injection sleeve 24, the molten metal 6 poured into the injection sleeve 24 is
Since the metal 8 once hits the molten metal buffer plate 62 and flows down without adjoining the inner wall surface of the injection sleeve 24, the metal 68 of molten metal scatters with turbulence and oxidizes the metal 68 of molten metal. Further, when the projected area A1 of the molten metal buffer plate 62 is 95% or more of the sectional area A2 of the injection sleeve 24, it is difficult to replace the molten metal 68 flowing down through the annular gap 69 with the air staying in the injection sleeve 24. The pouring speed from the ladle 66 to the injection sleeve 24 becomes very slow.

The molten metal buffer plate 62 is for temporarily receiving the molten metal 68 poured from the ladle 66, and its setting position.
When H2 is less than ⅕ of the height H1 of the injection sleeve 24, many bubbles are generated in the poured molten metal 68 because the molten metal 68 drop from the pouring position of the ladle 66 to the molten metal buffer plate 62 is large. As a result, the oxide 70 is more entangled. Further, the height H2 of the molten metal buffer plate 62 is the height of the injection sleeve 24.
When it exceeds 4/5 of H1, since the molten metal 68 drop from the pouring position of the ladle 66 to the molten metal buffer plate 62 is small, the generation of bubbles in the molten metal 68 is small, but The height to the upper end surface of the injection sleeve 24 is small and it is difficult to pour the molten metal 68 so as not to overflow. Therefore, the height H2 of the molten metal buffer plate 62 is ⅕ of the height H1 of the injection sleeve 24 before pouring the molten metal 68 into the injection sleeve 24.
4/5, preferably 2/5 to 3/5.

Further, the material of the oxide removing device 60 is, for example, a metal, a non-metal, or a composite material thereof which does not melt against the molten aluminum alloy or magnesium alloy. In the present embodiment, the molten metal buffer plate 62 and the moving shaft 64 are not limited to being orthogonal to each other as shown in FIG. 3, and the intersecting angle between the molten metal buffer plate 62 and the moving shaft 64 as shown in FIG. You may make it match with the inclination angle of. Reference numeral 58 is a fixed sleeve, 65 is a mold sleeve, and 6
Reference numeral 6 is a ladle, 67 is a gate portion, and 69 is an annular gap provided between the molten metal buffer plate 62 and the injection sleeve 24.

The operation of the vertical injection device configured as described above will be described. First, the movable platen 7 is advanced by the mold clamping cylinder 8 to clamp the molds 11 and 12, and then, as shown in FIG.
As shown in (3), the rod 52 of the tilt cylinder 44 is advanced and tilted to the chain line position, and the lubricant is spray-supplied to the injection sleeve 24 from a lubricant spray device (not shown). Next, while holding the moving shaft 64 of the oxide removing device 60 with a gripping device (not shown), the molten metal buffer plate 62 is lowered in the axial direction of the injection sleeve 24, and the cover 63 is attached to the injection sleeve 2.
4 is engaged. Next, the molten metal buffer plate 62 and the injection sleeve 24 are positioned so as to have an annular gap 69, and the height H2 of the molten metal buffer plate 62 in the injection sleeve 24 is set to the height of the injection sleeve 24 as shown in FIG. The position is set to be, for example, 2/5 of H1.

Next, an inert gas supply source (not shown), an inert gas introduction tube 64b, a hollow portion 64c, and a lower end portion 64a.
An appropriate amount of inert gas is blown into the injection sleeve 24 via the air to replace the air, and the inside of the injection sleeve 24 is made an inert gas atmosphere (FIG. 4). After tilting the ladle 66, for example, an aluminum alloy molten metal 68 is pumped from a molten metal holding furnace (not shown), and then once the molten metal 68 is gently poured onto the molten metal buffer plate 62 having a small head, the molten metal is poured on the injection sleeve 24. 6
8 flows down from the annular gap 69 on the inner wall surface of the injection sleeve 24 as a rectified flow, is replaced with air and is gradually stored in the injection sleeve 24 (FIG. 4). When the molten metal 68 flows down from the annular gap 69 into the injection sleeve 24,
The vortex flow of the molten metal 68 is made as slow as possible to prevent the entrainment of air and to reduce the entrainment of the compound 70 in the molten metal 68.

Subsequently, the molten metal buffer plate 6 is inserted into the injection sleeve 24.
When the molten metal 68 is poured through 2, the level of the molten metal 68 gradually increases, and the residual inert gas in the injection sleeve 24 is also replaced with the molten metal 69 and discharged from the annular gap 68 (FIG. 5). ). As the molten metal buffer surface 62 stored in the injection sleeve 24 gradually approaches the molten metal buffer plate 62, the molten metal buffer plate 62 is lifted while being careful to be constantly positioned above the molten metal 68 surface. Let Immediately before the completion of pouring the molten metal into the injection sleeve 24, the rising of the molten metal buffer plate 62 is stopped, and the molten metal surface of the molten metal 68 is positioned slightly above the upper surface of the molten metal buffer plate 62 (FIG. 6).

When pouring is completed, the ladle 66 is ready to pump the molten aluminum alloy 68 into the molten metal holding furnace. On the other hand, when the molten metal buffer plate 62 is pulled up from the injection sleeve 24, the molten metal 68 is on the upper surface of the molten metal buffer plate 62, and the oxide 70 floating on the molten metal surface.
Are attached, and it is retracted to an appropriate position as it is (FIG. 7).
After this, the oxide 70 attached to the upper surface of the molten metal buffer plate 62
Are mechanically removed by collision, vibration, gas (including air) blowing, etc. in the next step (FIG. 8).

On the other hand, when pouring into the injection sleeve 24 is completed, pressure oil is introduced to the piston rod 52 side of the tilt cylinder 44 to erect the injection device 13. Next, when pressure oil is introduced into the cylinder hole 30, the docking frame 22 starts to rise at a predetermined speed to bring the injection sleeve 24 into contact with the fixed sleeve 58. Further, pressure oil is introduced to the head side of the piston 26 to raise the plunger tip 38 and raise the molten metal 68 into the mold sleeve 65. Finally, pressure oil is introduced into the injection cylinder 20 to further raise the plunger tip 38 and to fill the molten metal 68 into the cavities 11a and 12a.
To be filled. Molten metal 68 into the cavities 11a, 12a
After completion of the solidification, the injection plunger 20 and the docking frame 22 are lowered and tilted to the chain line position shown in FIG. 2, and the molds 11 and 12 are opened to open the cavity 11
The cast product in a and 12a is taken out, but when the mold is opened, the product and the biscuit 71 are cut and separated to complete one cycle.

Next, the rectangular flat plate casting product (18 × 100 × 200 mm) obtained by the above-mentioned high-pressure casting method was cut in the vertical and horizontal directions to make 20 test pieces (18 × 50 × 20 mm). The amount of oxide 70 contained in the test piece was measured and Table 1
I got a result like.

The casting conditions and the conditions of the molten metal buffer plate 62 at the time of high pressure casting shown in Table 1 are as follows. Casting conditions: Gate speed 50.0 mm / s Injection sleeve inner diameter 80 mm (Cross sectional area A2 = 50.2 mm ² ) A1 / A2 = 0.77 (-) Molten metal pressure 800 kgf / cm ² Cast material: AC4CH (T6) Molten metal Buffer plate condition: Molten metal buffer plate 70 mm (projected area A1 =
38.5mm ² ) Height from plunger tip surface (H2) 120mm Length from plunger tip surface to top of injection sleeve (H1) 210mm H2 / H1 = 0.57 (-)

[0026]

[Table 1]

In Table 1, the amount of oxide 70 mixed in the cast product obtained by the casting method according to the present invention is the value when the wire net 74 is attached to the gate 67 portion which has been conventionally performed (Comparative Example 1). It can be seen that it is less than or equal to. On the other hand, in the cases of Comparative Examples 3 and 4, it was found that the amount of oxide mixed in the cast product was large, which was almost the same as that of Comparative Example 2 in which the wire net was not attached to the gate 67 portion. The tensile strength (σ
B) and elongation (δ) become smaller.

The oxide amount (%) shown in Table 1 was calculated as follows. When observing the amount of oxide, a notch is formed in each test piece (18 × 50 × 20 mm) to form a fracture surface, and the fracture surface is used as an observation surface. The size of the oxide exposed on these observation surfaces is 1 mm or less, 1-2.
mm, 2 to 3 mm, and 3 to 4 mm, the number of oxides falling within these size ranges was visually observed, and the amount of oxides mixed in the cast product was calculated by the following formula.

[0029]

[Equation 1]

Here, Y is the total observation area of 20 test pieces,
X represents the amount (%) of oxide mixed in the cast product. In this embodiment, the case of horizontal vertical casting is described, but the present invention is not limited to this, and other methods such as vertical vertical casting can also be used. Note that, as the antioxidant gas, there are an inert gas (N2 gas, argon gas) and sulfur hexafluoride gas, and in the present embodiment, the case of using N2 gas was described, but the present invention is not limited to this, carbon dioxide gas, and Sulfur hexafluoride gas (used to prevent oxides of magnesium metal)
Etc. may be used. Further, in the present embodiment, the case where the cover 63 is attached at the time of blowing the antioxidant gas into the injection sleeve 24 has been described, but the cover 63 may not be attached.

[0031]

As is apparent from the above description, in the casting method for casting products with a small amount of oxides according to the present invention, the molten metal buffer plate having an annular gap between the vertical injection sleeves is used for the injection sleeves. It is fixed to the tip of a hollow moving shaft that moves up and down in the same axial direction as above, and an antioxidant gas is blown into the injection sleeve while being positioned at an appropriate height in the injection sleeve, and then the molten metal buffer plate is placed from above the injection sleeve. After pouring the molten metal toward the pipe, it is made to flow down from the annular gap, the molten metal buffer plate is raised in accordance with the molten metal surface rising speed, and the molten metal surface is located above the buffer plate before pouring is completed. Since the oxide remaining on the buffer plate is taken out integrally with the buffer plate at the position, the generation of oxide is reduced and the inclusion of the oxide in the molten metal can be prevented. , Very quality excellent casting products can be obtained compared to the casting products come. Further, since the wire mesh is not buried in the biscuit portion, the surplus casting material (biscuit) can be effectively used, and the yield is improved.

[Brief description of drawings]

FIG. 1 is a front view of a vertical casting die casting machine.

FIG. 2 is a vertical cross-sectional view of a vertical injection device.

FIG. 3 is a vertical sectional view of an oxide removing device.

FIG. 4 is an explanatory diagram showing a state of pouring molten metal into the injection sleeve according to the embodiment of the present invention.

FIG. 5 is an explanatory view showing a state of pouring molten metal into the injection sleeve according to the embodiment of the present invention.

FIG. 6 is an explanatory view showing a state of pouring molten metal into the injection sleeve according to the embodiment of the present invention.

FIG. 7 is an explanatory view showing a state of pouring molten metal into the injection sleeve according to the embodiment of the present invention.

FIG. 8 is an explanatory view showing taking out of an oxide obtained by a casting method according to an example of the present invention.

FIG. 9 is another embodiment similar to the present invention.

FIG. 10 is a front view of a conventional biscuit.

[Explanation of symbols]

 3 Fixed Platen 4 End Platen 5 Tie Rod 10 Toggle Mechanism 11 Fixed Die 12 Movable Dies 11a, 12a Cavity 13 Injection Device 15 Biscuit Part 20 Injection Cylinder 22 Docking Frame 24 Injection Sleeve 32 Docking Ram 38 Plunger Chip 44 Tilting Cylinder 58 Fixed Sleeve 60 Oxide removal device 62 Molten metal buffer plate 63 Cover 64 Moving shaft 64a Lower end 64c Hollow portion 65 Mold sleeve 68 Molten metal 69 Annular gap 70 Oxide 71 Biscuit 74 Wire mesh

Claims (1)

[Claims] 1. A molten metal buffer plate having an annular gap between vertical injection sleeves is fixed to the tip of a hollow moving shaft that moves up and down in a direction coaxial with the injection sleeve, and an appropriate height inside the injection sleeve is secured. In the state of being positioned at the height of the molten metal, an antioxidant gas is blown into the molten metal, and then the molten metal is poured from above the injection sleeve toward the molten metal buffer plate and then allowed to flow down through the annular gap. An oxide that raises the buffer plate and positions the molten metal surface above the buffer plate before the completion of pouring so that the oxide remaining on the buffer plate is taken out integrally with the buffer plate. A method for manufacturing cast products with a small amount of inclusion.