JPH09308956A - Die having slide core and clamping method for die - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the development of flash at the time of die casting and to improve a vacuum casting function by facilitating the deformation in the radial direction at the time of acting a contact-pushing force of a slide core to the inner surface of a ring, in the structure of the tapered ring for pushing the slide core of a fixed die. SOLUTION: On the contact part of the lower surface of the tapered ring 4 with the upper surface of a fitting ring 8, three or more keys slidingly fitting parts composed of projecting key 4c and key groove 8a are respectively radially arranged at regular intervals in a peripheral direction and even in the case the tapered ring 4 deforms by the pushing force and thermal expansion, the key 4c is uniformly slid in each key groove 8a to keep the centering of the ring. Further, the width of the upper side of the tapered ring 4 is reduced in the radial direction, and when the pushing force acts to the inner peripheral surface of the ring, the deformation in the radial direction is facilitated. Further, a bolt 5 for fitting the tapered ring is made slidable in the radial oval-shaped hole 8b arranged at the lower part of the fitting ring key groove 8a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die casting mold and a mold clamping method, and more particularly to a mold having a plurality of slide cores and burr blow when the mold is clamped and cast. The present invention relates to a method that is useful for preventing vacuum and performing vacuum casting.

[0002]

2. Description of the Related Art Conventionally, for example, in the case of molding aluminum wheels for automobiles by die casting, a vertical type vertical casting die casting machine has been used. As shown in FIG. 9, for example, the die casting machine is divided into a fixed mold 1, a movable mold 2, and a movable mold 2 into right and left parts, which are attached so as to be openable and closable in a direction perpendicular to the mold opening / closing direction axis. A mold comprising two or four to four slide cores 3, a core cylinder 12 for opening and closing the slide core 3, and a taper ring 4 for holding the slide core so that the slide core 3 does not open during casting. The taper ring 4 was fixed to the fixed mold holder 13 and further mounted to the fixed platen 14. The movable mold 2 is attached to a movable platen 16 via a movable mold holder 15 and is vertically driven by a mold clamping cylinder (not shown). The tie bar 20 connects the fixed platen 14 and the mold clamping cylinder with a tie bar nut 21. 11 is a cavity, 17 is a casting sleeve, 18 is a plunger tip, and 19 is a plunger.

When casting is performed using such a device, 4
The split slide core 3 is closed by the core cylinder 12, and then the die casting machine is clamped to align the movable die 2 and the slide core 3 with the fixed die 1. In that case, the outer peripheral portion of the tip of the slide core 3 has a taper surface 3a, and when the slide core 3 is inserted into the taper recess 4a on the inner periphery of the taper ring 4 attached to the fixed mold 1, the slide core 3 is caused by the casting pressure. It prevents it from opening.

[0004]

As can be seen from the above, for example, when casting an aluminum wheel,
In order to take out the product, it is necessary to make a part of the die on the outer periphery of the product open and close the slide core 3 of 40 or 20 parts. On the other hand, when the mold is clamped, it is necessary to contact all the contact surfaces with the mating side in order to perform sealing for vacuum casting while preventing burr blow. However, when pouring is started, the molten metal enters the cavity 11 on the inner surface of the slide core 3, the slide core 3 receives the heat, and the temperature rises significantly. On the other hand, the taper ring 4 does not come into direct contact with the molten metal. The temperature of the taper ring 4 does not rise so much that a temperature difference occurs between the two.

For example, when the temperatures of the slide core 3 and the taper ring 4 are the same at the start of operation, the contact surface between the slide core 3 and the fixed mold 1, the slide core 3 and the taper ring 4 are formed.
When the operation is started after adjusting the clearance of the contact surface to 0, the temperature of the slide core 3 rises with the lapse of time, the outer diameter of the slide core 3 increases due to thermal expansion, and the taper increases. The contact surface with the ring 4 rises upward, and a gap is created in the contact surface between the fixed core 1 and the lower surfaces of the slide core 3 and the movable mold 2.

If the gap between the molds 1 and 3 is set to 0 in the presence of a temperature difference, the taper ring 4 needs to be greatly extended and deformed. A large pressing force is required to greatly deform the taper ring 4, and the mold clamping force between the fixed mold 1 and the movable mold 2 is reduced by that amount, and when a large casting pressure is applied, the mold clamping force is reduced. The force is insufficient, and the mold opening force acts when the molten metal is cast, and a gap is created between the fixed mold 1 and the slide core 3 or the movable mold 2 to blow burrs.

When the taper ring 4 is largely deformed, a large circumferential stress is generated in the taper ring 4. Generally, the rigidity of the slide core 3 is much larger than that of the taper ring 4, and therefore the value is approximately σθ = E × 1.1 × 1
It becomes 0 ⁻⁵ × Δθ. Here, σθ: circumferential stress E: Young's modulus of taper ring 4 1.1 × 10 ⁻⁵ : coefficient of thermal expansion of slide core 3 Δθ: temperature difference between taper ring 4 and slide core 3 Normally, Δθ is It may exceed 100 degrees. At this time, σθ exceeds 30 kg / mm ² and is close to the fatigue strength of the taper ring 4 made of chromium molybdenum steel, etc. If there is a mounting bolt hole, the stress concentration causes fatigue. Since the strength exceeds the strength and the taper ring 4 is damaged, it is operated in a state where the deformation amount is small, but at this time, the fixed mold 1 and the slide core 3 or the movable mold 2 do not contact,
Burrs are easy to blow and vacuum casting is not possible due to the gap.

[0008]

According to the present invention, in order to solve such a problem, a fixed mold on the lower side, a movable mold on the upper side, and a direction perpendicular to the axial direction of the mold opening / closing direction. In a mold that has a plurality of slide cores that can be opened and closed and that are mounted on a movable mold, and a taper ring for pressing the slide core that is mounted on a fixed mold so that each slide core does not open during casting ∙ Provide three or more key-sliding fitting parts consisting of a protruding key and a key groove radially at the contact part between the lower surface of the taper ring and the upper surface of the mounting ring, and taper by reducing the radial width of the upper taper ring. When the contact pressing force acts on the inner peripheral tapered surface of the ring, the taper ring is easily deformed in the radial direction, and the threaded portion of the taper ring fixing bolt provided upward in the mounting ring is slidably fitted on the key. Placed at the joint And the mold having a slide core.

Further, the mold is clamped using the above-mentioned mold,
When the outer circumference of the slide core, which has expanded slightly in diameter due to thermal expansion, is inserted into the inner circumference of the taper ring by the action of the mold clamping force, the taper ring is easily deformed in the radial direction, and the bottom surface of the slide core is fixed to the lower fixed metal. In addition to making it easier to hit the upper surface of the mold, even if the average circumferential stress increases, the stress concentration in the bolt holes is eliminated to reduce the maximum stress and prevent fatigue failure of the tapering.

[0010]

[Operation] The mold is clamped with the slide core closed. Even when cold, even when the casting pressure acts on the inner surface of the slide core, there is a tightening margin between the outer peripheral surface of the slide core and the inner peripheral surface of the taper ring so that the tightening force does not open the mutual gap between the slide cores. Then, the mold is clamped and the lower surface of the slide core is applied to the upper surface of the lower fixed mold. When casting is performed, a force for opening the die is generated by the casting pressure, but since the die clamping force is large, it does not float between the movable die and the fixed die.

The temperature difference between the slide core and the taper ring becomes maximum when the temperature of the slide core rises after casting is started and the heat is not yet transmitted to the taper ring. In this case, the outer circumference of the slide core has a larger thermal expansion margin than the inner circumference of the taper ring, and in order for the lower surface of the slide core to hit the upper surface of the lower fixed mold, it is necessary to extend the taper ring in the radial direction with a large pressing force. , The effective mold clamping force is reduced accordingly.

In the present invention, in order to reduce the pressing force to reduce the decrease in the effective clamping force, the cross section of the taper ring is reduced to facilitate radial deformation, and the slide core is increased with a small pressing force. The lower surface of the mold was applied to the upper surface of the fixed mold to prevent the mold from opening even when a casting pressure was applied, so that burr was not blown. When casting is completed, the mold is opened, the movable mold is lifted by the movable plate, then the slide core is opened, and the cast product is taken out.

When the taper ring is largely deformed, large stress is generated. This has bolt holes and keyways,
When the stress concentration of that shape is applied, the maximum stress increases and it leads to fracture. The stress concentration generated in the bolt holes, the key grooves, etc. is generally 2 to 3, and if the stress concentration is made small, the destruction can be prevented even if the average stress becomes high. In the present invention, in order to eliminate stress concentration, a key for positioning is cut out from the taper ring and provided in a protrusion shape, and a screw hole for a mounting bolt is provided in the protrusion to avoid a force flow. The stress increase due to stress concentration could be eliminated. This made it possible to use a taper ring with a small cross section that has a large amount of deformation and a high average stress.

[0014]

1 and 2 show a case where a die is attached to a vertical die casting machine as one embodiment of an apparatus for carrying out the present invention, and a conventional apparatus shown in FIG. The same parts are denoted by the same reference numerals as those in FIG. 9, and the description thereof is omitted. The casting sleeve 17 and the plunger 19 are provided, for example, in Japanese Patent Publication No. 57-20061 and Japanese Patent Publication No. 57-2141.
By the method described in No. 4, the operations of pouring, tilting, docking, and injecting are performed, and casting is performed in the cavity 11.

As shown in FIGS. 1 and 4 to 7, the taper ring 4 and the mounting ring 8 are mounted on the fixed holder 13, and the shape of the taper ring 4 and the fixed holder 13 contacting the slide core 3 is fixed. It is composed of a mounting ring 8 to be mounted and has a protruding key 4c on the lower surface of the taper ring 4.
Are provided on the outer peripheral side of the taper ring bottom surface 4b at equal intervals in the circumferential direction, three or more, for example, four in a radial pattern, and the key groove 8 has a longer dimension than the key 4c provided on the upper surface of the mounting ring 8.
While being inserted and positioned in a, the taper ring 4 is deformed by pressing force and thermal expansion, and several keys 4c are formed in each key groove 8
The inside of a is slid evenly and the center of the taper ring 4 is maintained. The taper ring mounting bolt 5 is tightened via the spacer 6 and the washer 7, so that when the taper ring 4 is deformed, the spacer 6 and the bolt 5 can slide in the elongated holes 8b radially provided in the mounting ring 8. It has become.

A key groove is also machined on the lower surface of the mounting ring 8, positioned by the key 10, and mounted on the fixed holder 13 by the mounting bottle 9. When the taper ring 4 is pressed by the slide core 3, the outer peripheral surface 3b of the slide core 3 contacts the taper inner peripheral surface 4a of the taper ring 4, and the taper ring 4 is extended in the radial direction.
At this time, a large circumferential stress is generated in the taper ring 4. However, the screw hole 4d for mounting the tapering ring mounting bottle 5 is provided within the range of the height of the protruding key 4c as shown in FIG. 7, and the influence of stress concentration is almost negligible. In FIG. 7, what is indicated by the alternate long and short dash line at the taper ring 4 is the stress line 23, which appears almost horizontally.

Further, the protruding key 4c and the screw hole 4 are provided.
By providing d on the outer peripheral side where the circumferential stress is relatively small as shown in FIG. 8, the stress generated in the portion of the key 4c and the screw hole 4d exceeds the circumferential stress generated in the inner circumference of the taper ring 4. Since this is not the case, a taper ring with a small cross section could be used. In FIG. 8, Dc represents the average inner diameter of the taper ring 4. Further, when a high-grade material having high fatigue strength is used for the taper ring, the taper ring 4 has a small cross section and is deformed by a small force. Therefore, even if the slide core 3 is expanded by thermal expansion, the effective mold clamping force is not significantly reduced.

Next, the operation of the present invention will be described. 4 to 6 are enlarged views for explaining the movements of the slide core and the taper ring. The slide core 3 which is divided and opened is closed, and the mold is clamped in a stationary state. When the movable platen 16 descends, first, the outer peripheral tapered surface 3a of the slide core 3 comes into contact with the inner peripheral tapered surface 4a of the taper ring 4. When the pushing force is 0 in the cold state, as shown in FIG. 4, the lower surface of the slide core 3 does not contact the upper surface of the fixed mold 1 and has a gap of δ. In FIG. 4, β indicates the angle of the tapered surfaces 3a and 4a.

The gap δ is a dimension for generating a tightening force on the taper ring 4 necessary to prevent the burr from blowing due to the vertical alignment surface of the slide core 3 being opened during casting, and as shown in FIG. By applying the pushing force P _C , the taper ring 4 is deformed and the slide core 3 is lowered, and the slide core 3 comes into contact with the upper surface of the fixed mold 1 and becomes zero. The amount of deformation of the taper ring 4 at that time is ΔR ₁ . When the mold clamping force of the mold clamping device is P _O , the effective mold clamping force Pa ₁ between the movable mold 2 including the slide core 3 and the fixed mold ₁ is Pa ₁ = P _O −P _C.

When casting is started, the slide core 3 is heated by the sensible heat and the solidification heat of the molten metal, and a temperature difference is generated between the slide core 3 and the taper ring 4. For this reason, the outer circumference of the slide core 3 is thermally expanded and increased by Δα = (Dc / 2) × 1.1 × 10 ⁻⁵ × Δθ. Δα is the deformation amount of the slide core 3, Dc
Is the average diameter of the tapered surfaces 3a and 4a, and Δθ is the temperature difference between the taper ring 4 and the slide core 3. Therefore, when hot, it is necessary to push in with a larger force P _H to eliminate the gap between the slide core 3 and the fixed mold 1. At this time, if the deformation amount of the taper ring 4 is taken substantially in the radial direction, the circumferential stress σθ of the taper ring 4 is approximately σθ = E × 1.1 × 10 ⁻⁵ × Δθ, and Δθ is When the temperature exceeds 100 degrees, a large stress is applied, so a material having a large fatigue strength is used.

This state is shown in FIG. Here, ΔR ₂ represents the change in the position of the taper ring 4 during cold pressing and hot pressing, and approximately Δα = ΔR ₂ , so the amount of stress increase is the temperature difference Δ regardless of the cross-sectional area.
It depends on θ. Thus, using a high-level material, using the tapering 4 of the small cross-sectional area in a range capable of securing the clamping force required at the start a cold state, the increase of the pressing force at the time of hot (P _H -P _C ) becomes small, the effective clamping force Pa ₂ during hot working does not decrease so much, and stable casting is possible.

Although the circumferential stress is increased by using the taper ring 4 having a small cross-sectional area, the screw hole of the mounting bolt 5 is arranged outside the range of the force flow of the circumferential stress, so that the stress is not increased due to the stress concentration. By arranging it on the outer peripheral side where the circumferential stress is relatively low, there is almost no fracture due to stress concentration.

The magnification of the force for tightening the slide core 3 depends on the taper angle and the friction coefficient. It can be set by adjusting the radial displacement of the taper ring 4 when a load is applied and the dimensions of each part of the taper ring 4 to optimum values. If the mold is clamped by this method, the contact surfaces of the slide core 3 and the fixed mold 1 and the contact surface of the split surface 3b in the circumferential direction of the slide core 3 will have contact surfaces of the slide core 3 and the taper ring 4. Since sealing can be performed with a constant contact pressure regardless of changes in each temperature, air can be prevented from entering from the outside when the inside of the cavity 11 is evacuated before casting, and when the casting is completed Even if pressure is applied, there is no gap and no burr is blown.

When the casting is completed and the cast product is cooled, the mold is opened as shown in FIG. 3, the slide core 3 is also opened, and the cast product 22 is taken out.

In the first embodiment, three or more key-sliding fitting portions each having the protruding key 4c and the key groove 8a are radially provided at the contact portion between the lower surface of the taper ring 4 and the upper surface of the mounting ring 8. In this case, the key 4c is
In this example, the key groove 8a is provided on the upper surface of the mounting ring 8, but in some cases, the protruding key is provided on the upper surface of the mounting ring 8 and the key groove is provided on the lower surface of the taper ring 4. It is also possible to provide.

[0026]

According to the present invention, the taper ring for tightening the slide core is structured so as to eliminate stress concentration and to be easily displaced in the radial direction with a small cross section. Regardless of the above, the maximum tensile stress generated in the taper ring is kept lower than the fatigue strength to prevent damage, and both the gap between the fixed mold and the movable mold and the gap on the split surface of the slide core are reduced to zero. Therefore, stable operation is possible without blowing burrs during operation, it is possible to create a vacuum inside the mold, and air is not entrained even when performing high-speed casting. ， It becomes possible to cast thin products.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

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

FIG. 3 is a vertical cross-sectional view of a state in which a mold is opened and a product is taken out in one embodiment of the present invention.

FIG. 4 is a vertical cross-sectional view showing a displacement state of a slide core and a taper ring in a cold unloaded state according to an embodiment of the present invention.

FIG. 5 is a state diagram following FIG. 4 and is a vertical cross-sectional view showing a state during cold pressing in the present invention.

FIG. 6 is a vertical sectional view showing a state during hot pressing according to the present invention.

FIG. 7 is a vertical cross-sectional view showing a stress concentration state of a screw hole portion for a bolt of a taper ring in one embodiment of the present invention.

FIG. 8 is a diagram showing changes in circumferential stress in a cross section of a taper ring according to an embodiment of the present invention.

FIG. 9 is a vertical sectional view showing an example of a conventional device similar to the present invention.

[Explanation of symbols]

 1 Fixed Mold 2 Movable Mold 3 Slide Core 3a Slide Core Outer Tapered Surface 4 Tapered Ring 4a Tapered Ring Inner Tapered Surface 4b Tapered Ring Bottom 4c Tapered Ring Protrusion Key 4d Tapered Ring Bottle Screw Hole 5 Tapered Ring Mounting Bolt 6 Spacer 8 Mounting ring 8a Mounting ring key groove 9 Mounting ring mounting bolt 10 Key 11 Cavity 12 Core cylinder 13 Fixed type holder 14 Fixed platen 15 Movable type holder 16 Movable plate 17 Casting sleeve 18 Plunger tip 19 Plunger 22 Casting product

Claims (2)

[Claims] 1. A lower fixed mold and an upper movable mold,
Mold opening / closing direction A plurality of slide cores that are attached to the movable mold by being divided so that they can be opened / closed in the direction perpendicular to the axis.
For a die that has a taper ring for pressing the slide core that is attached to a fixed die so that each slide core does not open during casting, use a protruding key and key groove at the contact area between the bottom surface of the taper ring and the top surface of the attachment ring. Key slip fitting part consisting of 3
The radial width of the upper taper ring is made smaller by reducing the width of the upper taper ring in the radial direction so that the taper ring is easily deformed in the radial direction when a contact pressing force acts on the inner peripheral tapered surface of the taper ring. A mold having a slide core in which a threaded portion of a bolt for fixing a taper ring provided upward is arranged in the key slip fitting portion. 2. A lower fixed mold and an upper movable mold,
Mold opening / closing direction A plurality of slide cores that are attached to the movable mold by being divided so that they can be opened / closed in the direction perpendicular to the axis.
It has a taper ring and a mounting ring for pressing the slide core that is attached to a fixed mold so that each slide core does not open during casting, and a protruding key and key are provided at the contact part between the lower surface of the taper ring and the upper surface of the mounting ring. Three or more key-sliding mating parts consisting of grooves are provided radially, and the width of the upper taper ring in the radial direction is reduced to make the taper ring radial when the contact pressing force acts on the inner peripheral tapered surface of the taper ring. The bolt of the bolt for fixing the taper ring, which is easily deformed and is provided upward in the mounting ring, is clamped using a mold having a slide core in which the key slip fitting part is arranged. Clamping force between the fixed mold and the movable mold is eliminated even if the outer peripheral dimension of the slide core changes due to thermal expansion by eliminating stress concentration in the hole and increasing by the shape of large circumferential stress generated during deformation. Large Maintaining the mold clamping force of the slide core without reducing Ku and clamping method of a mold having a slide core which is adapted to prevent breakage of tapering to reduce the maximum stress generated in the tapering.