JPH06304698A - Device for casting cylinder head - Google Patents

Abstract

PURPOSE:To prevent the slippage of a core by holding the inside end part of the core with both of a partial mold having a part for hole as cast in a valve guide and the other partial mold. CONSTITUTION:By holding the inside end part 90a of the core with both of the part 20 for hole as cast at the tip part of a member 7 for hole as cast and the lower mold 2, shifting in the interval between abutting parts 7b, 2a is regulated. In the same way, shifting in the interval between abutting parts 8b, 2b is regulated with a member 8 for hole as cast. When molten metal flows into a cavity, even if the inside end parts 90a, 91a receive the force by the fluid pressure of the molten metal, as the shifting of the core is regulated with the abutting parts 7b, 2a, 8b, 2b, the slippage of the core can be prevented, and a cast product of cylinder head having good dimensional precision can be obtd. As the unevenness of the thickness can be reduced, the thinning and the lightening of the product 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 casting apparatus capable of improving the dimensional accuracy of a cylinder head casting in the casting of a cylinder head.

[0002]

2. Description of the Related Art The low pressure casting method is widely used for mass production of automobile parts and the like. What is this low-pressure casting method? The mold is placed on a closed furnace containing molten metal (molten metal), the closed furnace and the mold are connected by a conduit (stoke), and a slight atmospheric pressure is applied to the furnace to melt the molten metal. Casting is performed by rising in the stalk against gravity and injecting into the mold cavity from the lower gate of the mold attached to the upper part of the stalk. The low pressure casting method is often applied to aluminum-based light alloy castings, and the cylinder head is also generally cast using the low pressure casting method.

For example, Japanese Unexamined Patent Publication No. 64-53757 discloses a low pressure casting method for the cylinder head.
FIG. 7 shows a cylinder head casting apparatus used in Japanese Patent Laid-Open No. 64-53757. In FIG. 7, reference numeral 30 indicates a casting apparatus main body. The casting mold 32 that constitutes the casting apparatus 30 includes a lower mold 34, an upper mold 36, and a horizontal mold 3.
8a, 38b and 40a, 40b, and these lower mold 34, upper mold 36 and horizontal molds 38a, 3
A cavity 42 is defined by 8b and 40a, 40b. A stalk 47 for feeding the molten metal to the cavity 42 is connected to the nozzle 46, and the stalk 47 is provided in a heat-retaining furnace (not shown) installed below the lower mold 34 and is placed in a crucible in which the molten metal is stored. Be inserted. Cooling hole 48
Extends into the nest 49.

Further, as is clear from the figure, among the respective constituent parts of the cylinder head in the cavity 42,
In order to accelerate cooling of a relatively thick portion where a hole for inserting the valve guide is formed, the casting members (cooling plates) 54a and 54b having a cooling mechanism are mounted on the movable die base 50 It is inserted into holes 56a and 56b penetrating the mold 36. Here, the cast member (cooling metal) 54a, 5
4b does not come into contact with the cores 80b and 80c for forming the intake passage and the exhaust passage of the cylinder head.

Further, the cores 80b and 80c form the exhaust passage and the intake passage of the cylinder head, and the cores 80a and 80a
80d to 80f are for molding a water jacket through which cooling water flows. Cores 80b, 80c for molding the exhaust passage and the intake passage of the cylinder head
Are fitted in the horizontal molds 38a, 38b, 40a, 40b, respectively, and abutted on the insert 49.

[0006]

However, in the conventional cylinder head casting apparatus, when the molten metal flows into the cavity, the flow pressure due to the inflow of the molten metal causes the clearance between the core and the die to fluctuate and the position of the core to be changed. Because it shifts,
It was difficult to maintain stable dimensional accuracy of the cast cylinder head product. FIG. 6 shows an example of the cores 80b and 80c for forming the intake passage and the exhaust passage of the cylinder head, showing a state in which the core is displaced when the molten metal flows in (the casting member of the valve guide is omitted in the drawing). Available). The positions of the cores 80b, 80c before the inflow of the molten metal are shown by the solid lines 10 and 11, and the positions of the cores 80b, 80c after the inflow of the molten metal are indicated by the dashed lines 12, 13.
Shown in. As can be seen from FIG. 6, due to the displacement of the core due to the flow pressure of the molten metal when the molten metal flows into the cavity, especially around the core 14 for forming the intake passage and the exhaust passage of the cylinder head (indicated by the solid line The variation in the wall thickness in the area surrounded by the circle becomes large.

The present invention has been made in view of such circumstances, and in a core for forming an intake passage and an exhaust passage of a cylinder head, an inner end for forming the intake passage and the exhaust passage of the core. To improve the dimensional accuracy of a cylinder head casting product by abutting the portion with both the die and the valve guide die-casting portion that is a part of the die to regulate core movement between the portions. With the goal.

[0008]

SUMMARY OF THE INVENTION A cylinder head casting apparatus according to the present invention comprises a mold for casting a cylinder head, the mold including a partial mold having a valve guide casting portion and another mold, and a cylinder head. In a cylinder head casting apparatus, which comprises a core for forming an intake passage and an exhaust passage, and an outer end of the core is fitted into or clamped in the mold, an inner end of the core has a valve guide casting. It is characterized in that it is sandwiched by both a partial mold having a cutout and another partial mold.

[0009]

The cylinder head casting apparatus of the present invention includes a mold for casting a cylinder head, which is composed of a partial mold having a valve guide casting part and another partial mold, and an intake passage and an exhaust passage of the cylinder head. A core for molding is formed, and an outer end portion of the core (hereinafter, referred to as a core outer end portion) is fitted or sandwiched in the mold. Further, the inner end of the core (hereinafter referred to as the inner end of the core) is held by both the partial mold having the valve guide cast-out portion and the other partial mold. As a result, when the molten metal flows into the mold, the core is subjected to the flow pressure of the molten metal, but the inner end of the core is contacted by the corresponding part of both the partial mold having the valve guide casting and the other partial mold. The movement of the inner side end of the core is restricted between the parts, and the outer side end of the core is clamped or fitted in the mold, so the movement of the outer side end of the core is also restricted to prevent the core from slipping. be able to.

[0010]

【Example】

(First Embodiment) FIG. 1 shows a partial sectional view of a cylinder head casting apparatus 6 according to a first embodiment of the present invention. The cylinder head casting device 6 is substantially composed of a mold for casting the cylinder head and a core for molding the cylinder head. The mold for casting the cylinder head is a partial mold, that is, the upper mold 1, the lower mold 2, the horizontal mold 3, and a valve guide blanking member having a valve guide blanking portion for forming a hole through which the valve guide is inserted. It is composed of 7 and 8. The core for molding the cylinder head is a core 9 for molding the exhaust passage and the intake passage of the cylinder head.
0 and 91 and cores 5c to 5f for forming a water jacket through which cooling water flows. The core outer end 90b of the core 90 for forming the exhaust passage of the cylinder head is sandwiched between the lower mold 2 and the horizontal mold 3, and the core of the core 91 for forming the intake passage of the cylinder head is formed. The outer end portion 91b is sandwiched between the upper die 1 and the lower die 2 (in the drawing, the portion of the lower die 2 with respect to the outer end portion 91b of the core is not shown).

Further, the lower mold 2 abuts the core inner end portions 90a and 91a of the cylinder head at the contact portions 2a and 2b, respectively.

A valve guide casting member 7 having casting portions 20, 21 (hereinafter referred to as valve guide casting portion) for molding an insertion passage portion of the valve guide in the upper mold 1.
8 (hereinafter, referred to as casting members 7 and 8) penetrates,
It projects into the cavity 9. The casting members 7 and 8 can be attached to and detached from the upper mold 1. The casting member 7 is the casting member 7
When the stepped portion 7a of the upper end hits the upper mold 1, the upper mold 1
The casting member 7 is positioned with respect to the casting die member 8 and the casting member 8 is positioned by the stepped portion 8a of the casting member 8 hitting the upper die 1.

Further, the cast-out portion 20, which is the tip of the cast-out member 7, is abutted against the abutting portion 7b at the core inner end 90a. Similarly, the casting portion 21 that is the tip of the casting member 8
Has abutted against the inner portion 91a of the core against the corresponding portion 8b.
“Abutting” refers to a state in which the inner end portions of the core are pressed with a pressing force that does not damage the inner end portions 90a and 91a of the core. Therefore, the core inner end 90a is
It is sandwiched by both the valve guide casting part 20 and the lower mold 2, and is restricted in movement (in this case, vertical movement in the drawing) between the contact parts 7b, 2a. For this reason,
When the molten metal flows into the cavity, even if the core inner end portions 90a, 91a receive a force in the vertical direction in the drawing due to the flow pressure of the molten metal flowing in from below in the drawing, the drawing between the corresponding portions by the contact portions 7b, 2a. By restricting the movement of the core in the vertical direction, it is possible to prevent the core from being displaced in the vertical direction of the drawing.

Further, the valve guide casting portions 20, 21 which are the tip portions of the casting members 7, 8 are provided with machining allowances for the actual product insertion passage shapes (shown by broken lines in the drawing) 22, 23. Dimensions are used.

After the molten metal is poured into the cavity 9 using the above apparatus and the casting is completed, first, the cast members 7 and 8 are cast.
After the casting, the upper mold 1, the lower mold 2, and the horizontal mold 3 are separated from the cylinder head cast product after they are separately driven in the directions of arrows 24 and 25 before the product is demolded.

Further, the casting members 7 and 8 may be provided with a cooling mechanism for promoting cooling of a relatively thick portion where a hole for inserting the valve guide is formed. good. For example, a space may be provided inside the casting members 7 and 8 and the space may be filled with a cooling medium.

(Second Embodiment) FIG. 2 shows a partial sectional view of a cylinder head casting apparatus 6 according to a second embodiment of the present invention.
As shown in FIG. 2, the difference from the first embodiment is that the mold for casting the cylinder head is a partial mold such as an upper mold 1, a lower mold 2, a horizontal mold 3, casting members 7, 8 and a nesting member 4. , And a core inner end 90a,
It goes without saying that the same effect as in the first embodiment can be obtained even if 91a abuts on the nest 4. in this case,
The core inner end portions 90a and 91a are respectively cast members 7,
It is held by 8 and the nest 4. The outer core end 91b of the cylinder head is sandwiched between the upper mold 1 and the lower mold 2 (in the drawing, the portion of the lower mold 2 with respect to the outer core end 91b of the core is not shown).

(Third Embodiment) FIG. 3 shows a partial sectional view of a cylinder head casting apparatus 6 according to a third embodiment of the present invention.
As shown in FIG. 3, the point different from the first and second embodiments is that the casting members 7 and 8 which are partial molds do not penetrate the upper mold which is a partial mold. In this case, after the cylinder head is cast, when the cylinder head cast product is taken out of the mold, the mold is moved by first moving the upper mold to the upper side of the drawing, and then moving the cylinder head cast product (cavity 9 in the drawing).
The casting members 7 and 8 that are still fitted in the molten metal injected into the hardened shape) are removed from the cylinder head casting product. The outer core end 91b of the cylinder head is sandwiched between the upper mold 1 and the lower mold 2 (in the drawing, the portion of the lower mold 2 with respect to the outer core end 91b of the core is not shown). Also in the third embodiment, the same operation and effect as in the first embodiment can be obtained.

(Fourth Embodiment) FIG. 4 shows a partial sectional view of a cylinder head casting apparatus 6 according to a fourth embodiment of the present invention.
As shown in FIG. 4, the difference from the first to third embodiments is that the upper die 1 of the partial die has a valve guide casting portion 1a, 1
It is a structure having b. It goes without saying that the upper mold 1 may have a structure having a valve guide cast-out portion for molding the valve guide insertion passage depending on the shape of the product. This case is possible when the demolding direction of the upper mold 1 and the valve guide casting parts 20 and 21 are in a parallel relationship. Outer end 91b of the core of the cylinder head
Is sandwiched between the upper mold 1 and the lower mold 2 (in the figure, the lower mold 2
However, this portion is not shown with respect to the core outer end portion 91b. ).

(Fifth Embodiment) FIG. 5 shows a partial sectional view of a cylinder head casting apparatus according to a fifth embodiment of the present invention. The fifth embodiment differs from the first to fourth embodiments in that the partial die casting members 7 and 8 and the cores 90 and 91 are structured. FIG. 5 shows only the structure of the tip of the cast member 7 and the inner end 90a of the core. Corresponding to the first embodiment, not shown cast-out member 8 and core inner end 91
The structure of a is the same as the structure of the tip end of the cast member 7 and the inner end 90a of the core shown in the drawing. Here, the casting member 7 penetrates the through hole 5a of the core inner end 90a. Further, the casting member 7 is positioned by abutting the tip portion 7d of the casting member 7 with the insert 4.

At this time, a stepped portion 7c is provided at the boundary between the portion 15 of the casting member 7 where the valve guide casting hole is formed and the core insertion portion 16 inserted into the through hole 5a of the core. Has been formed. Further, the core insertion portion 16 has a tapered shape. The stepped portion 7c of this cast-out member 7 is the contact portion 7 with the core.
The core insertion portion 16 abuts on the inner core portion 90a and the contact portion 5b. Here, the core inner end 90a abuts the insert 4 and the contact portion 4a. As a result, the inner core portion 90a is sandwiched by both the stepped portion 7c of the cast member 7 and the insert 4. From the above, the core inner end portion 90a is moved between the contact portions 7e, 5b and 4a by the contact portions 7e, 5b, 4a (movement in the vertical and horizontal directions in the drawing and in the direction perpendicular to the drawing sheet). As a result, the core deviation can be prevented regardless of the inflow direction of the molten metal.

In the fifth embodiment, the tip portion 7d of the cast member 7 is
The cast-out member 7 is positioned by abutting the insert 4 against the insert 4, and thus the dimensional accuracy of the core to be abutted against the lower mold and the insert, which is a dimensional reference, against the influence of the mold warpage due to the heat of the molten metal. It will be further improved. If the dimensional deviation (deviation from the product specification on the drawing) of the cast product obtained by using the apparatus of Example 2 is ± 1.0, the cast product obtained by using the apparatus of Example 5 is Dimensional deviation is ± 0.
It was within 5.

The valve guide casting portion 20, which is the tip of the casting member 7, has a dimension in which a machining allowance is provided for an actual product insertion passage shape (shown by a broken line in the drawing) 22.

After the molten metal is poured into the cavity 9 using the above apparatus and the casting is completed, first the casting members 7 and 8 are cast.
Separates the upper die 1, the lower die 2 and the horizontal die 3 from the cylinder head casting after the die is separately driven in the direction of the arrow 27 before the die is removed.

Also here, naturally, the casting members 7, 8 are
Needless to say, the configuration may be provided with a cooling mechanism for promoting cooling of a relatively thick portion where a hole through which the valve guide is inserted is formed. For example, a space may be provided inside the casting members 7 and 8 and the space may be filled with a cooling medium.

[0026]

According to the present invention, a mold for casting a cylinder head, which is composed of a partial mold having a valve guide casting portion and another partial mold, and an intake passage and an exhaust passage of the cylinder head are formed. The inner end of the core is formed in both the partial mold having the valve guide cast-out portion and the other partial mold, and the outer end of the core is fitted or clamped in the partial mold. It is possible to prevent the core from slipping by sandwiching the core and restricting the movement of the core, and it is possible to obtain a cylinder head cast product with good dimensional accuracy. Further, in particular, since it is possible to reduce the variation in the wall thickness around the core for forming the intake passage and the exhaust passage of the cylinder head, it is possible to make the product as thin as possible and reduce the weight. it can. Furthermore, as various tasks to improve dimensional accuracy, for example, a partial presser seat is provided on a part of the baseboard, and while tuning the convex amount of the presser seat while watching the cylinder head casting, the baseboard size can be changed. Since it is not necessary to carry out work such as balancing for product dimensional deviations by setting a large value, dimensional determination can be made in a short time, production preparation efficiency can be improved, and production cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a cylinder head casting apparatus showing a first embodiment of the present invention.

FIG. 2 is a partial sectional view of a cylinder head casting apparatus showing a second embodiment of the present invention.

FIG. 3 is a partial sectional view of a cylinder head casting device showing a third embodiment of the present invention.

FIG. 4 is a partial sectional view of a cylinder head casting device showing a fourth embodiment of the present invention.

FIG. 5 is a partial sectional view of a cylinder head casting apparatus showing a fifth embodiment of the present invention.

FIG. 6 is a diagram showing a state of core misalignment at the time of inflow of molten metal.

FIG. 7 is a sectional view of a conventional cylinder head casting device.

[Explanation of symbols]

6 ... Mold for casting cylinder head 90 ... Core for forming intake passage of cylinder head 91 ... Core 90a for forming intake passage of cylinder head ... Inner end portion for forming intake passage in core 90b ... Outer end portion for forming exhaust passage in core 91a ... Inner end portion for forming intake passage in core 91b ... Outer end portion for forming exhaust passage in core 20, 21, ... Valve guide casting portion

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Okura 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd.

Claims (1)

[Claims] 1. A mold for casting a cylinder head, comprising a partial mold having a valve guide cast-out portion and another partial mold, and a core for molding an intake passage and an exhaust passage of the cylinder head. In a cylinder head casting device in which the outer end of the core is fitted into or sandwiched by the partial mold, the inner end of the core has a partial mold having the valve guide blank part and another partial mold. A cylinder head casting device characterized in that it is sandwiched by both.