JPH09220655A - Production of light alloy-made wheel hub kind - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a core made of a low m.p. metal and to obtain a wheel hub having good dimensional precision by casting molten metal under condition inserted an iron-made ring to a gate part at the lower surface of the core made of the low m.p. metal for undercut part. SOLUTION: In the casting of the light alloy-made wheel hub having the undercut part, in which a metallic mold is not taken out after casting, the annular core 5 composed of the low. m.p. metal of Zn or Al-containing Zn alloy, etc., is set in the undercut part 4c. The core 5 is integrally manufactured under condition of inserting the iron-made ring 11 at the upper part of the gate 10 on the lower surface of the core 5. At the time of casting, the core 5 made of the low m.p. metal and the iron-made ring 11 are set on a projecting part la of a fixed die 1, and a movable die 2 is lowered to execute the die clamping. At the time of casting the molten metal through the gate 10 and a passage 13, even in the case, the sensible heat and the solidified heat of molten metal intend to act to the core 5 made of the low m.p. metal, the deformation caused by melting of the surface of the core 5 is not developed because of the extence of the iron-made ring 11.

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 such as a wheel hub for an automobile made of a light alloy such as an aluminum alloy or a magnesium alloy.

[0002]

2. Description of the Related Art Conventionally, wheel hubs of automobiles are generally made of ductile cast iron, and when made of aluminum alloy, they are made of forged products, and are made of die cast aluminum alloy or magnesium alloy. No alloy castings are produced.

[0003]

A wheel hub is an important strength component in an automobile, and in order to maintain the strength and reduce the weight, it is necessary to form a divergent cylindrical shape as indicated by reference numeral 4 in FIG. However, when trying to manufacture this by die casting, the die cannot be pulled out after the completion of casting because of the undercut portion, and the sand die core or the low temperature molten metal core is placed in this undercut portion. I have no choice but to use it.

When a low-temperature molten metal core is used for the undercut portion, the surface of the low-temperature molten metal is usually protected by a heat-insulating film, and a low-temperature molten metal such as a zinc alloy that does not melt but absorbs the heat of solidification of the molten metal is usually used. Although it is used as a core, the upper part of the gate in the center has a large amount of molten metal, a large heat capacity of its sensible heat and solidification heat, a fast flow, and a large heat transfer. If the melting point is close to the melting point, the core will deform, resulting in poor casting. Therefore, it is necessary to prevent the surface of the core of the low-temperature molten metal from melting and deforming when casting a cast product such as a wheel hub that is in a molten metal flow state.

Further, when manufacturing the light alloy wheel hubs by die casting, the light alloy cast in the die is reused by reusing a portion which is not a product or a core of a low temperature molten metal. It is necessary to consider using it more effectively.
In addition, when casting wheel hubs, it is necessary to obtain a more compact product without cavities, and it is necessary to make it easier to separate the billet part from the cast product so that the cast product can be easily taken out of the mold. There is also.

[0006]

When casting a wheel hub made of light alloy, there is a possibility that the upper center gate of the lower surface of the core of the low-melting metal for the undercut portion is overheated and the surface of the low-melting metal is melted. Therefore, the present invention solves the problem of preventing the surface of the core of the low temperature molten metal from being melted by using an iron ring in this portion.

Further, in the present invention, when casting a light alloy wheel hub having an undercut portion in which the die does not come off using a die, a low temperature molten metal is used for the core of the undercut portion. ， Casting with the iron ring inserted in the gate part of the lower surface of the core of this low-temperature molten metal, take out the cast product from the mold after the casting is completed, and then remove the iron ring from the cast product by pressing, At the same time as melting the cast iron in a chemical furnace to melt and remove the core of the low-temperature molten metal, then water quenching and then age hardening in an aging furnace to manufacture wheel hubs, or At the same time, the low-temperature molten metal used for the core is solidified and recycled as a recycled ingot for use, or the iron ring taken out with the light alloy adhered is heated to separate and recycle the light alloy. It was to be used in cycles.

Further, the molten metal is cast into the mold cavity from below through a vertical gate having a diameter smaller than the inner diameter of the casting sleeve, and when the molten metal is filled in the mold cavity, it is leveled on the lower surface of the core of the low temperature molten metal. The tip of the feeder pin, which was placed with the tip facing downward to the inner diameter of the iron ring that was placed in this state, is advanced into the vertical gate to obtain a dense product with no cavities. The biscuit part can be separated from the cast product.

Further, when the lower end of the guide tube for the feeder pin is engaged with the inside of the upper surface of the iron ring, the casting operation is performed, and when the iron ring is removed from the cast product by a press, low temperature melting is performed. Use a push rod for iron ring removal that has a large diameter part smaller than the inner diameter of the metal core and larger than the inner diameter of the iron ring, and a small tip part that can be inserted into the inner diameter part of the iron ring. The ring can be removed easily.

[0010]

If the casting is performed from below, the molten metal that has passed through the gate will enter the cavity through the molten metal passage of the die and be filled. In order to ensure product performance, it is desirable to use the squeeze casting method. In this case, high pressure is applied to the plunger to pressurize the molten metal, and then the feeder pin, which is also called acurad pin according to solidification contraction, is used. Pressurize with.

In this case, the temperature of the molten metal is high near the upper surface of the molten metal passage of the die, the heat capacity is large, the flow is fast, and the heat transfer amount is large. It absorbs and prevents the temperature rise of the low-temperature molten metal core, and shields the high pressure applied to the molten metal to prevent core deformation.

When the casting is completed and the mold is opened and the cast product is taken out from the mold, the iron ring encircled in the cast product is sheared and separated by the press, and the cast product is sent to the heat treatment furnace. The iron ring to which the light alloy, which is a mass of molten metal, adheres is heated to melt and remove the light alloy for reuse.

When the molten metal passage of the lower die is formed and the protrusion receiving the core is small and it is overheated by the sensible heat and the solidification heat of the molten metal and the damage is remarkable, the shape of this iron ring is changed, It is also possible to form a receiving leg and form a molten metal passage therein.

In the case of the cast alloy AC4C, heat treatment is carried out in order to secure the strength. The solution temperature at this time is 530 ° C.
However, the melting temperature of zinc, which is an example of a core of low-temperature molten metal, is 420 ° C., and the heat of fusion is also 24.4 kcal /
Since it is as small as kg, it melts easily. Further, the boiling point of zinc is 907 ° C., and it does not evaporate at 530 ° C.
Therefore, if a receiving box for receiving molten metal is installed under the product pedestal during heat treatment, the molten metal in the core will flow down into this.

When solution cooling is completed and the solution is water-cooled for quenching, if both are placed in water, the cast product is quenched and zinc becomes an ingot. This is recovered and reused as a core. There is almost no consumption of low temperature molten metal.

[0016]

1 and 2 show a cast state of a wheel hub according to an embodiment of the present invention. 1 and 2, in a vertical mold vertical casting machine for casting molten metal from below, 1 is a fixed mold or a lower mold, 2 is a movable mold or an upper mold that moves up and down, 3 is a cast product 4. Wheel hub 4 for an automobile
Is a cavity for forming a wheel hub 4
Is composed of an upper horizontal flange portion 4a, a cylindrical portion 4b that widens toward the end, and an undercut portion 4c that is formed as a ring-shaped recess inside and cannot remove the mold after the completion of casting. .

A ring-shaped core 5 made of a low temperature molten metal is installed in the undercut portion 4c. This core 5
For example, JP-B-48-32053, JP-A-52-14521, and JP-A-53-46438.
JP-A-63-183769, JP-A-63
Zinc alloys containing a few percent of pure zinc or aluminum as disclosed in JP-A-199060, JP-A-63-273547 and JP-A-3-294055 are known. If the melting point is obviously lower than that of cast alloys such as aluminum alloys and magnesium alloys,
Other metals such as tin, lead and solder may be used. However,
If the melting point is too low, the molten metal such as an aluminum alloy cannot be easily melted by the heat when it is cast, so pure zinc having a melting point of 419 ° C. or a zinc alloy is usually used.

When the core 5 of the low temperature molten metal is used,
The outer circumference of the core body is coated with refractory. As the refractory material, various materials have been considered as described in the above publication, but in general, there are many mica-based coating materials. Alternatively, a mica-based coating material and a phenol resin, graphite, thermosetting resin, or the like may be used. The thickness of the coating is, for example, 100 to 300 μm.

Reference numeral 6 is a vertical casting sleeve joined to the lower surface of the fixed mold 1 so as to be able to come into contact with and separated from it, 7 is a plunger tip that slides up and down in the casting sleeve 6, and 8 is a plunger. 7 and the plunger 8 move up and down by the action of a casting cylinder (not shown). Reference numeral 9 denotes a pouring port having the same inner diameter as that of the pouring sleeve 6, 10 is a vertical gate provided in the upper center portion of the pouring port 9 and having a diameter smaller than the inner diameter of the pouring sleeve 6, Vertical gate 10
The inner peripheral surface of the taper has a tapered shape having a draft in a downward direction and an upward direction with the central portion as a boundary.

The core 5 of the low-temperature molten metal is integrally formed with the iron ring 11 inserted in the upper part of the gate 10 on the lower surface of the core 5. A protrusion 1a having a seat 12 for mounting and holding an iron ring 11 is provided at the upper outlet of the gate 10 of the fixed mold 1. The protrusions 1a are provided in a state of being separated from each other in the circumferential direction, and the space between the adjacent protrusions 1a is a passage 1 through which molten metal flows into the cavity 3.
3 is formed.

Reference numeral 14 is a feeder pin, which is also called an acurad pin, and is arranged downward at the center of the movable mold 2. Reference numeral 15 is a guide tube portion for the feeder pin 14 which forms a part of the movable mold 2. The tip of the guide tube portion 15 can be engaged with a recess provided on the upper surface of the iron ring 11. The iron ring 11 can be installed in a stable state. The outer peripheral surface of the guide tube portion 15 can also contact the inner peripheral surface of the core 5.

The tip of the feeder pin 14 is on the lower surface of the iron ring 11 as shown by the solid line in FIG. 1 before and during casting, and as soon as the molten metal is cast into the cavity 3, the A cylinder (not shown) can be operated to move downward in accordance with solidification and solidification of the molten metal, as shown by a two-dot chain line in FIG. The tip of the feeder pin 14 can pass through the smallest diameter portion of the gate 10 and can be advanced to near the upper end of the pouring port 9. The outer diameter of the feeder pin 14 is smaller than the inner diameter of the smallest diameter portion of the gate 10 by, for example, 1 to 5 mm, and the biscuit portion remaining in the casting opening 9 at the time of mold opening is the portion from the casting product. So that it will be disconnected. Reference numeral 16 is a bolt hole pressing pin, and 17 is an overflow portion.

When casting is performed, the core 5 of the low temperature molten metal is used.
The iron ring 11 is installed on the protrusion 1a of the fixed mold 1, the movable mold 2 is lowered, and the mold is clamped as shown in FIG. In this way, with the iron ring 11 inserted in the gate 10 on the lower surface of the core 5, the casting sleeve 6 containing the molten metal is docked under the fixed mold 1, and then the plunger tip 7 is raised. The molten metal is cast into the cavity 3 through the gate 10 and the passage 13, and the plunger tip 7 applies a high pressure to the molten metal. At the time of casting, even if the sensible heat and solidification heat of the molten metal try to act on the core 5 of the low-temperature molten metal, the surface of the core 5 is not melted and deformed because of the iron ring 11.

The molten metal is cast into the mold cavity 3 from below through the vertical gate 10 having a diameter smaller than the inner diameter of the casting sleeve 6, and when the molten metal is filled in the cavity 3, the lower surface of the core 5 of the low temperature molten metal is formed. The tip of the feeder pin 14 having its tip facing downwardly inside the inner diameter of the iron ring 11 arranged horizontally is advanced into the vertical gate 10. By this operation, the molten metal in the cavity 3 is pressed by a high pressure according to the solidification state, and the cast product 4 of the wheel hub becomes a cast product 4 with no cavities, which is dense and has high mechanical strength and good mechanical properties. Along with that, casting 4
The biscuit part and the biscuit part are connected by the narrow passage part between the smallest inner diameter part of the gate 10 and the outer peripheral surface of the feeder pin 14, so that the biscuit part is easily and easily separated from the cast product 4 when the mold is opened. Like

After the casting is completed, the feeder pin 14 is retracted and the movable mold 2 is raised to open the mold. At this time, the wheel hub 4, which is the cast product 4, rises while it is attached to the movable mold 2. Therefore, the biscuit portion is cut at the minimum diameter portion of the gate 10, leaves the cast product, and remains in the casting port 9. In this biscuit part, after the casting sleeve 6 is separated from the lower part of the fixed mold 1, the biscuit part is pushed out by an unillustrated extruding pin and taken out from the casting port 9 part.

After the mold is opened and the cast product 4 is taken out from the movable mold 2, the core 5 and the iron ring 11 of the low temperature molten metal are integrated in the cast product 4. Therefore, first, the iron ring 11 is separated from the cast product 4, and then the core 5 is removed.
When separating the iron ring 11 from the casting 4, for example,
As shown in FIG. 3, the iron ring 11 is removed from the cast product 4 by pressing.

In FIG. 3, 4 is a wheel hub which is a casting, and 5 is a core. A cast product 4 having a core 5 and an iron ring 11 is placed on a shear pedestal 18, and a large diameter portion having a diameter smaller than the inner diameter of the core 5 of the low temperature molten metal and larger than the inner diameter of the iron ring 11. The iron ring 11 is pushed down by using a push rod 19 for removing the iron ring 11 having a small diameter portion 19b that can be inserted into the inner diameter portion of the iron ring 11. Then, as shown in FIG. 3, the iron ring 11
Then, a part 4d of the cast product 4 located immediately below the iron ring 11 is extracted from the cast product 4. At that time, the overflow cutting blade 20 also cuts the overflow portion 17.

After the iron ring 11 is removed from the cast product 4 by pressing, the cast product 4 is solutionized in the solution heat treatment furnace at the same time, the low temperature molten metal core 5 is melted and removed, and then water-cooled quenching is performed. Further, the wheel hub 4 is manufactured by age hardening in an aging furnace. At the same time, the low-temperature molten metal used for the core 5 is solidified and recycled as a recycled ingot for use, and the iron ring 11 is taken out with light metal such as aluminum alloy in which the molten metal is solidified attached.
Is heated to separate light metals for recycling and use.

[0029]

EXAMPLE In the present invention, the light metal used as the molten metal is
For example, an aluminum alloy or a magnesium alloy is used. As described above, the core 5 of the low temperature molten metal is
For example, pure zinc or a zinc alloy containing a few percent of aluminum is used. The outer periphery of the core body is coated with a refractory made of a mica-based coating material to a thickness of 100 to 300 μm, for example. As for the iron ring 11, if it is made of iron, the type thereof does not matter.

FIG. 4 shows a flow sheet according to an embodiment of the process of the present invention. Fig. 4 shows an example in which an aluminum alloy is used as the molten metal, and an aluminum ingot is melted and cast, trimming of the iron ring 11 etc., solution heat treatment by a solution heat treatment furnace, water cooling, aging treatment by an aging furnace, machining , A state in which the wheel hub 4 as a product is obtained is shown.

Before casting, the core 5 is manufactured by melting an ingot of low temperature molten metal, and the core 5 is mounted in the mold together with the iron ring 11. On the other hand, after casting, when the iron ring 11 and a part 4d of the aluminum casting 4 were removed from the casting 4 by trimming, the iron ring 11 was cleaned and reused as it was, and a part 4d of the casting 4 was obtained. The deposited aluminum is melted and reused. The cutting powder obtained by machining the wheel hub 4 can also be dissolved and reused. Further, the core 5 of the low temperature molten metal solution-treated by the solution heat treatment is water-cooled to be reused as a recycled ingot.

[0032]

EFFECT OF THE INVENTION By manufacturing wheel hubs by the method of the present invention, it is
It is possible to manufacture wheel hubs with a weight of two, which contributes to weight reduction of automobiles, and can significantly reduce costs compared to aluminum forged wheel hubs.

Further, when a light alloy wheel hub having an undercut portion where the die cannot be removed is cast using the die, a low-temperature molten metal is used for the core for the undercut portion. The molten metal of the light alloy was cast into the mold cavity with the iron ring inserted in the gate of the lower surface of the core, so the surface of the core of the low-temperature molten metal was sensible heat and solidification heat of the melt. It is possible to reliably and easily prevent the molten metal from trying to deform. as a result,
Products with good dimensional accuracy can be obtained, and casting can be performed relatively easily.

After the casting is completed, the cast product is taken out of the mold, the iron ring is removed from the cast product by a press, and the cast product is solutionized in a solution heat treatment furnace during heat treatment, and at the same time, the core of the low-temperature molten metal is melted and removed. Then, water-cooled quenching is performed, and then age hardening is performed in an aging furnace to manufacture wheel hubs, and the low temperature molten metal used for the core is solidified and recycled as a recycled ingot. , The iron alloy ring with the light alloy attached is heated to separate the light alloy for recycling and use, so it is possible to efficiently manufacture good quality wheel hubs or to use it as a core. The used low temperature molten metal and iron ring can be recycled and used effectively.

Further, the molten metal is cast into the mold cavity from below through a vertical gate having a diameter smaller than the inner diameter of the casting sleeve, and when the molten metal is filled in the mold cavity, the molten metal is leveled on the lower surface of the core of the low temperature molten metal. Since the tip of the feeder pin, which was placed with the tip facing downward to the inner diameter of the iron ring that was placed in this state, is made to advance to the inside of the vertical gate, the feeder action is sufficient. By doing so, it is possible to easily obtain a dense and strong product without cavities, and the biscuit part can be easily separated from the cast product when the mold is opened, and the subsequent work can be facilitated. .

Further, when the casting operation is performed while the lower end of the guide tube portion for the feeder pin is engaged with the inside of the upper surface of the iron ring and the iron ring is removed from the cast product by a press,
Use a push rod for removing the iron ring that has a large diameter part smaller than the inner diameter of the core of the low temperature molten metal and larger than the inner diameter of the iron ring, and a small tip part that can be inserted into the inner diameter part of the iron ring. Therefore, the iron ring can be easily removed.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of a wheel hub and a mold device for carrying out the method of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a vertical cross-sectional view showing an example of an operating state when removing an iron ring.

FIG. 4 is a flow sheet showing the steps of the present invention.

[Explanation of symbols]

 1 Fixed mold (lower mold) 2 Movable mold (upper mold) 3 Cavity 4 Wheel hub (cast product) 5 Low temperature molten metal core 6 Casting sleeve 7 Plunger tip 9 Casting port 10 Gate 11 Iron ring 13 Passage 14 Feeder pin 18 Shear cradle 19 Push rod

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B22D 29/00 B22D 29/00 F B60B 27/00 B60B 27/00 B M N

Claims (7)

[Claims] 1. When casting a light alloy wheel hub having an undercut portion that prevents the die from coming off, a low temperature molten metal is used for the core for the undercut portion,
A method for manufacturing light alloy wheel hubs in which a light alloy melt is cast into a mold cavity with an iron ring inserted in the gate portion on the lower surface of the core of this low-temperature molten metal. 2. When casting a light alloy wheel hub having an undercut portion that prevents the die from coming off using a die, a low temperature molten metal is used for the core for the undercut portion,
Casting is performed with the iron ring inserted in the gate part on the lower surface of the core of this low-temperature molten metal, and after the casting is completed, the cast product is taken out of the mold, and then the iron ring is removed from the cast product by pressing and solutionized during heat treatment. A light alloy made by melting the core of low-temperature molten metal at the same time as melting the cast product in a furnace, then water quenching and then age hardening in an aging furnace to manufacture wheel hubs. Manufacturing method of wheel hubs. 3. When casting a light alloy wheel hub having an undercut portion that prevents the die from coming off using a die, a low temperature molten metal is used for the core for the undercut portion,
Casting is performed with the iron ring inserted in the gate part on the lower surface of the core of this low-temperature molten metal, and after the casting is completed, the cast product is taken out of the mold, and then the iron ring is removed from the cast product by pressing and solutionized during heat treatment. At the same time as casting the solution into a solution in the furnace, the core of the low-temperature molten metal is melted and removed, then water-cooled and quenched, and then age hardened in the aging furnace to manufacture wheel hubs and used for the core. The low-temperature molten metal solidified is recycled and used as a recycled ingot, and the iron ring extracted with the light alloy attached is heated to separate the light alloy for recycling and use. Method for manufacturing alloy wheel hubs. 4. The molten metal is cast into the mold cavity from below through a vertical gate having a diameter smaller than the inner diameter of the casting sleeve, and when the molten metal is filled in the mold cavity, the molten metal is leveled on the lower surface of the core of the low temperature molten metal. The iron tip arranged in a state in which the tip end portion of the feeder pin is arranged so that the tip end portion of the iron ring is directed downward, and the tip end portion of the feeder pin is advanced into the vertical gate. The method for manufacturing a light alloy wheel hub according to claim 3. 5. The method of manufacturing light alloy wheel hubs according to claim 1, wherein aluminum alloy wheel hubs are manufactured as the light alloy wheel hubs. 6. A low temperature molten metal core is cast by casting a molten metal of a light alloy into a mold cavity with an iron ring inserted in the gate portion of the lower surface of the low temperature molten metal core, and sensible heat and solidification heat of the molten metal. The method for manufacturing a wheel hub made of a light alloy according to any one of claims 1 to 5, wherein the surface of the wheel is prevented from melting and deforming. 7. When the iron ring is pulled out from the cast product by a press operation while the lower end of the guide tube portion for the feeder pin is engaged with the inside of the upper surface of the iron ring, low temperature melting is performed. A push rod for removing the iron ring is used, which has a large diameter part smaller than the inner diameter of the metal core and larger than the inner diameter of the iron ring, and a small tip part that can be inserted into the inner diameter part of the iron ring. A method for manufacturing a wheel hub made of a light alloy according to claim 2 or claim 3.