JPH0259160A - Apparatus for manufacturing casting having thick parts at both ends - Google Patents

Abstract

PURPOSE:To prevent enclosing defect of gas and shrinkage hole defect and to manufacture a casting having high quality by forming cross sectional area at molten metal flowing part in a gate to the specific times of cross sectional area at cavity space corresponding to lower thick part in a casting product. CONSTITUTION:The cross sectional area at the molten metal flowing part in the gate 19 is formed to 0.3-1 time of the cross sectional area of the cavity space 13c corresponding to the lower thick part of the casting product. By this constitution, sufficient directional solidification can be obtd. from the cavity apace 13c for the thick part toward the weir 19. By this method, the development of the shrinkage hole in the cavity space 13c for the lower thick part is prevented and also as the molten metal flowing cross sectional area in the gate 9 is large and the directional solidification is executed, the molten metal can be filled up at low velocity and enclosure of gas into the casting can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for manufacturing a casting having thick-walled portions at both ends, which manufactures a casting having thick-walled portions at both ends using a horizontal high-pressure casting technique using a low-speed filling method.

[Prior Art] High-pressure die casting is a highly productive casting method that can manufacture aluminum alloy parts in large quantities with high precision.

FIG. 2 is a sectional view showing a local pressurizing device in conventional high-pressure die casting. The fixed mold 2 and the movable mold 1 are installed to face each other in the horizontal direction. Then, the fixed mold 2
By overlapping the movable mold 1 and the cavity 3
Once formed, the cavity 3 is composed of cavity chambers 3a and 3C for thick-walled parts, and a cavity chamber 3b for thin-walled parts arranged between the cavity chambers 3a and 3c, and an upper cavity for thick-walled parts. The movable mold 1 and the fixed mold 2 are formed so that the chamber 3a and the lower thick wall cavity chamber 3C are vertically (vertically) separated from each other. Further, there is an extra wall portion 4a adjacent to the upper side of the cavity chamber 3a or the lower side of the cavity chamber 3C, respectively.

4b, and local pressurizing cores 7a, 7b, which are inserted through the movable mold 1, enter into the respective extra-thickness portions 4a, 4b. At the lower part of the excess portion 4b,
A sleeve 5 is attached to the fixed mold 2 with its axial direction being horizontal, and the space within the sleeve 5 communicates with the excess wall portion 4b via a runner. A plunger tip 6 is inserted into the sleeve 5, and the molten metal supplied into the sleeve 5 is forced into the cavity 3 by the tip 6 through the runner and the extra wall portion 4b. There is.

The chip 6 creates a cavity 3 and an extra wall portion 4a.

When the molten metal is press-fitted into the mold 4b, the molten metal is cooled and solidified in the cavity 3 by the fixed mold 2 and the movable mold 1. In this case, if the molten metal is allowed to solidify as it is, cavities will occur, so the cores 7a and 7b are advanced into the excess wall portions 4a and 4b in order to have a feeder effect on the areas where the cavities occur. It is designed to apply pressure locally.

Therefore, the local pressure device shown in FIG. 2 includes the core 7a,
The moving direction of 7b, ie, the pressing direction, is made to coincide with the mold opening direction in order to avoid problems such as stiffness and galling of the product.

However, in this case, the nest generation part 8a.

Since the core 8b does not exist in front of the cores 7a and 7b in the direction of movement, there is a drawback that the effect of preventing nests is low. For this reason, attempts have been made to increase the size of the core or increase the local pressing force, but the effect of preventing shrinkage cavities is not necessarily sufficient.

Therefore, a local pressurizing device (feeder device) has been proposed in which the pressurizing direction is directed vertically downward in order to directly pressurize the nest generating area (Japanese Patent Application Laid-open No. 76265/1983). That is, this proposal attempts to obtain a sufficient riser effect by applying pressure directly above the cavity chamber 4a for thick-walled portions in a vertically downward direction.

In this prior art, the molten metal in the lower thick wall cavity is solidified under pressure by high-speed injection of a plunger tip.

[Problems to be Solved by the Invention] However, although the conventional local pressurization device described above attempts to prevent gas entrainment by reducing the pressure inside the cavity, it is difficult to sufficiently prevent gas entrainment due to high-speed filling. The disadvantage is that it cannot be done. In addition, there is a problem in that the inside of the cavity for the lower thick-walled portion is likely to have a cavity defect.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a casting manufacturing apparatus having thick-walled parts at both ends, which can prevent gas entrainment defects and pull-out defects and can manufacture high-quality castings.

[Means for Solving the Problems] An apparatus for producing a casting having thick-walled parts at both ends according to the present invention includes:
In an apparatus for manufacturing a casting having a thin wall part in the center and thick wall parts at both ends, there is a cavity in which cavity chambers for the thick wall part are arranged above and below, and a cavity provided below this cavity whose cross-sectional area is for the lower thick wall part. 0.3 to 1 of the cross-sectional area of the cavity chamber
A local pressurizing means that locally pressurizes the molten metal in the upper cavity chamber substantially vertically downward, and directs the molten metal in the cavity chamber for the thin wall part and the molten metal in the lower thick wall part cavity chamber in this order. and means for causing sexual coagulation.

[Function] In the present invention, since the molten metal in the cavity chamber for the upper thick-walled portion is locally pressurized substantially vertically downward by the local pressurizing means, the generation of cavities due to the upper thick-walled portion is sufficiently prevented. Can be done. In addition, the cross-sectional area of the neck is as wide as 0.3 to 1 times the cross-sectional area of the lower thick-walled cavity, and the molten metal is solidified directionally from the thin-walled cavity to the lower thick-walled cavity. Therefore, the molten metal in the cavity for the lower thick-walled portion also solidifies without causing any evacuation defects, and a healthy lower thick-walled portion can be obtained.

In addition, since the cross-sectional area of the weir is large and directional solidification occurs, low-speed filling is possible and gas entrainment into the cast product is prevented.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing a die casting mold in a casting manufacturing apparatus according to an embodiment of the present invention. The movable mold 11 and the fixed mold 12 are installed horizontally to face each other, and a cavity 13 is formed by a recess formed in their mating surfaces. This cavity 13 is the cavity chamber 1 for the upper thick part.
3a, it has a cavity chamber 13b for a thin wall part and a cavity chamber 13c for a lower thick wall part, and the upper and lower cavity chambers 13a and 13c for a thick wall part have mating surfaces of the movable mold 11 and the fixed mold 12 in the center thereof. formed in such a way as to be located;
They are placed vertically apart. The movable mold 11 has holes 20 for cooling water flow surrounding the cavity 13.
and installed inside the fixed mold 12. Further, an extra wall portion 14 is formed in the upper part of the upper thick wall cavity chamber 13a, and a core 17a for local pressurization is connected to the movable mold 11 and the fixed mold 1.
2 is inserted into the extra wall portion 14, its longitudinal direction is vertical, and it is arranged to be movable up and down. This core 17a has a fixed mold 12 and a movable mold 1 in the center of its tip.
It is arranged so as to match the mating surface with 1.

In addition, a lubricating oil supply hole (not shown) is communicated with the insertion hole of the core 17a to supply lubricating oil between the core 17a and the insertion hole. It is preferable to prevent eccentricity of the pressing core 17a and to smooth its operation.

On the other hand, a weir 19 whose wall surface extends vertically is provided below the lower thick-walled cavity chamber 13c. A sleeve 15 into which the plunger tip 16 is fitted is attached to the lower part of the fixed mold 12.
When molten metal is supplied into the weir, the plunger tip 16 advances, and the molten metal is supplied at high pressure toward the weir 19 through the runner. The molten metal is then press-fitted into the cavity 13 via this weir 19.

The core 17b is inserted vertically from the lower surface of the movable mold 11, and the molten metal is pressurized vertically upward at the weir 19 by the core 17b, so that the interior of the lower thick-walled cavity chamber 13c is The molten metal may be locally pressurized.

Note that it is preferable that the tip of the core 17a be provided with a portion of a taper that is inclined at an angle of 0.2 to 2 degrees with respect to the axial direction. The angle of a part of the taper of this core 17a is 0
．． If the groove is not 2°, the movement of the core 17a, especially the core 17
The movement of a when moving it in and out will be poor, leading to galling. On the other hand, if the angle of a part of the taper exceeds 2 degrees, a hole will be inserted between the local pressure core 17a and its insertion hole (provided in the fixed mold 12 or the movable mold 11).
The local pressure core 17a tends to become stuck.

Further, the cross-sectional area S2 of the molten metal return part of one weir is 0 of the cross-sectional area S1 of the cavity chamber 13c corresponding to the lower thick-walled part of the casting product.
．． Increase by 3 to 1 times. If the cross-sectional area S2 is less than 0.3 of the area S1 of the thick-walled portion, the cross-sectional area of the molten metal flowing through the weir 19 becomes too narrow, making it impossible to achieve sufficient directional solidification as described below. For this reason, a shrinkage cavity defect occurs in the lower thick-walled part of the casting.

On the other hand, if the weir section M S 2 exceeds 1 times the area S1 of the thick part, the material yield will decrease and the manufacturing cost will increase. Therefore, the cross-sectional area ratio S2/St is set to 0.3 to 1.0.

Furthermore, in order to reliably prevent gas entrainment and improve water circulation, one weir and one cavity chamber for thick-walled parts were installed.
It is desirable to provide gas venting slits in 3a, 13c and the extra wall portion 14.

The thickness of this slit is preferably 0.05 to 0.5 mm. When the thickness of the slit is 0.05 longweigou, gas is not vented sufficiently;
If it exceeds +n, there is a risk that the molten metal will blow out from the gap between the mold mating surfaces.

In the embodiment device configured in this way, the movable type 1
1 and the fixed mold 12 are butted against each other, the core 17a is placed in a predetermined position, and cooling water is made to flow into the hole 20. After supplying the molten metal into the sleeve 15, the plunger tip 16 is advanced to force the molten metal into the cavity 13 and the excess wall portion 14 through one weir. Then, the molten metal is cooled in the cavity 13 by the movable mold 11 and the fixed mold 12 and starts solidifying.

Then, the local pressure core 17a is lowered to
The molten metal in the cavity 13 is locally pressurized to provide a feeder effect to the molten metal in the upper cavity chamber 3a of the cavity 13, thereby preventing the generation of evacuation cavities. In this case, in this embodiment, the cavity chamber 13a exists directly below the core 17a, and the molten metal is pressurized vertically downward, so that an extremely excellent feeder effect can be obtained.

Furthermore, since the center of the tip of the core 17a is aligned with the mold matching surface, galling or the like is prevented from occurring when the movable mold 11 is opened from the fixed mold 12.

On the other hand, the cooling water flowing through the communication holes 20 causes the cavity chambers 13b for thin wall portions and the cavity chambers 13a, 13 for thick wall portions to
c is being cooled. By adjusting the cooling water flow rate or the distance between the hole 20 and each cavity chamber,
By adjusting the intensity of cooling by this cooling water, the molten metal first starts to solidify from the cavity chamber 13b for the thin-walled part, and then the front surface of this solidification flows from the lower cavity chamber 13c for the thick-walled part to the weir 19.
Coagulate directionally so that it moves to Due to this,
This prevents the formation of evacuation cavities within the lower thick-walled portion cavity chamber 13c.

In this case, in order to realize such directional solidification, the molten metal flow cross-sectional area S2 of the weir 19 becomes an important factor as well as cooling the vicinity of the thin-walled portion cavity chamber 13b described above. That is, in the present invention, the cross-sectional area S of this weir 19
2 is 0.3 of the cross-sectional area of 8 ri of the cavity chamber 13c for thick-walled parts.
Since it is set extremely wide, more than double, sufficient directional solidification can be obtained from the cavity chamber 13c for thick wall portion toward the weir 19. This prevents the generation of evacuation cavities in the lower thick-walled cavity chamber 13c, and since the molten metal flow cross-sectional area of the weir 19 is large and directional solidification occurs, low-speed filling is possible, and it is possible to fill the casting at a low speed. Gas entrainment is also prevented.

In order to make the cast product obtained in this example heat treatable, the cooling of the sleeve 15 and the flow divider (the movable part facing the sleeve) is weakened, or the cooling is stopped during casting, and the cooling is stopped after injection is completed. It is preferable to perform cooling from the time to the opening of the mold, and to stop the cooling at the time of opening the mold to prevent the formation of a solidified layer when the molten metal is poured into the sleeve. Since the product is filled at a low speed and no solidified layer is generated, there is no entrainment of gas into the product and heat treatment is possible.

The method of the present invention has JIS symbols such as ADCI2, AC
4C, AC4D, AC8A, AC8C.

It can be applied to various materials such as aluminum alloys for casting such as AC9A, AC9B, and A390, and alloys for die casting. Moreover, by the method of the present invention, various castings having thick walled portions at both ends, such as a swash plate piston, can be manufactured.

Next, AC8A and AC8C were obtained by the method of the present invention.

The results of actually manufacturing a swash plate piston using ADC12 and A390 alloys will be described.

The casting results of each swash plate piston are shown in Table 1 below. In addition, T6 heat treatment was performed after casting, and the presence or absence of blisters and strength at that time were also examined. The results and the measurement results of the wear resistance of the test piece cut out with the swash plate piston were also included in the first report.
Shown in the table.

As is clear from Table 1, in the case of Examples 1 to 8 of the present invention, extremely good results were obtained in all respects of shrinkage defects, blistering, strength, and abrasion resistance.

On the other hand, in Comparative Example 1, the ratio S2/
Because Sl was as small as 0.2, a shrinkage cavity defect occurred in the lower thick-walled part of the casting. In addition, in Comparative Example 4, no shrinkage defects occurred and the strength was sufficient, but the ratio S2/St was 1.
2, the product yield is as low as 30 to 60%. Incidentally, the product yield in this example is 40 to 80%.

On the other hand, in Comparative Example 2, although local pressure was applied, the thin wall portion was not cooled and directional solidification was not performed, so a shrinkage cavity defect occurred in the lower thick wall portion. Further, in Comparative Example 3, since no local pressure was applied, a shrinkage cavity defect occurred in the upper thick part.

[Effects of the Invention] According to the present invention, the upper thick-walled portion is locally pressurized and the lower thick-walled portion is directionally solidified to produce a casting having thick-walled portions at both ends, thereby preventing gas entrainment defects and pull-out. Cavity defects are prevented and high quality castings can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a mold showing an embodiment of the present invention, and FIG. 2 is a sectional view of a mold showing a conventional manufacturing apparatus. 1.11; Movable type, 2, 12; Fixed type, 3, 13; Cavity, 3a, 13a; Cavity chamber for upper thick part, 3
b, 13b, cavity chamber for thin wall part, 3c, 13c; cavity chamber for lower thick wall part, 4a, 4b, 14; excess wall part,
6, 16; plunger tip, 7a, 7b, 17a,
17b; Core for local pressure

Claims (3)

[Claims] (1) In an apparatus for manufacturing a casting having a thin wall part in the center and thick wall parts at both ends, there is a cavity in which cavity chambers for the thick wall part are arranged above and below, and a cavity provided below this cavity whose cross-sectional area is the thickness of the lower part. 0.3 of the cross-sectional area of the meat cavity chamber
1 to 1 times, a local pressurizing means for locally pressurizing the molten metal in the upper cavity chamber substantially vertically downward, and the molten metal in the cavity chamber for the thin wall portion and the molten metal in the lower thick wall portion cavity chamber. 1. An apparatus for manufacturing a casting having thick-walled parts at both ends, the apparatus comprising: means for sequentially directional solidifying. (2) The apparatus for manufacturing a casting having thick-walled parts at both ends according to claim 1, wherein the means for directional solidifying the molten metal is a cooling means for cooling the vicinity of the cavity chamber for the thin-walled part. (3) The thick-walled portion at both ends according to claim 1 or 2, further comprising a second local pressurizing means for locally pressurizing the molten metal in the lower thick-walled portion cavity chamber substantially vertically upward. Casting manufacturing equipment with.