JP3623194B2 - Support structure for sand core for cylinder block - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is disposed in a mold for casting the cylinder block, it relates to a support structure of a cylinder block for sand in children for forming a water jacket on the wall of the cylinder block.
[0002]
[Prior art]
Generally, a cylinder block constituting an internal combustion engine is manufactured by high pressure casting. In this high pressure casting, a sand core for cylinder block is used to form a water jacket on the wall surface of the cylinder block.
[0003]
In order to position and support this type of sand core in the mold, various proposals have been conventionally made. For example, a technique disclosed in Japanese Patent Laid-Open No. 9-271924 is known. As shown in FIG. 5, the above-described prior art includes a fixed die 1, slide cores 2 a and 2 b, and a slide core 3, and a cylinder block cavity 4 is formed between them, A sand core 5 is disposed in the cavity 4.
[0004]
The end surface 3a of the slide core 3 is in contact with the end surface 5a of the sand core 5 without a gap, thereby forming a window portion at the end of the water jacket. A sand core holding projection 6 protrudes from the end surface 3 a of the slide core 3 toward the cavity 4, and the sand core holding projection 6 is formed inward from the end surface 5 a of the sand core 5. It is inserted into the hole 7. As a result, the sand core 5 is positioned and held in the cavity 4.
[0005]
[Problems to be solved by the invention]
However, in the above prior art, the sand core holding projection 6 provided on the slide core 3 which is a mold is inserted into the holding hole 7 of the sand core 5. Damage is likely to occur. For this reason, it has been pointed out that the positioning accuracy of the sand core 5 tends to be lowered, and it becomes difficult to efficiently cast a cylinder block having a good water jacket.
[0006]
The present invention has been made to solve this kind of problem, it is possible to reliably prevent damage to the sand core, the cylinder block sand in the child capable of casting a high-precision cylinder block efficiently The object is to provide a support structure.
[0007]
[Means for Solving the Problems]
In the structure for supporting a sand core for a cylinder block according to the present invention, a sand core that is disposed in a mold for casting the cylinder block and forms a water jacket on the wall surface of the cylinder block is disposed inside the mold. The sand core is supported by a sand block, and the sand core is provided with a leg portion parallel to an axial direction of a cylinder bore constituting the cylinder block. A joint hole is formed, a window member forming pin member at the end of the water jacket is attached to the engagement hole, a base plate portion is formed on the side opposite to the cylinder bore side of the cylinder block, and the base plate portion Around the periphery is provided a hot water circulating part that allows the flow of molten metal, and the mold is provided with a support pin that engages with the baseboard part to support the sand core, and positions the sand core. When supporting The Goana, the pin member is inserted, and the pin member is characterized by circumscribing at three points in a recess formed on the mold.
[0009]
As a result, the sand core can be accurately positioned and supported with respect to the cavity only by engaging the pin member mounted on the sand core with the concave portion of the mold. Accordingly, the sand core is prevented from being damaged, the positioning accuracy of the sand core is improved, and the cylinder block having the water jacket can be cast efficiently and with high accuracy.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a partial cross-sectional explanatory view of a mold 12 incorporating a support structure 10 for a cylinder block sand core according to an embodiment of the present invention.
[0011]
The mold 12 includes a fixed mold 14, intermediate movable molds 16 a and 16 b, and a movable mold 18, and a bore pin 20 is provided on the fixed mold 14. A cylinder block cavity 24 is formed in the mold 12 by covering the bore pin 20 with a sleeve 22. A sand core 34 for forming the water jacket 32 of the cylinder block 30 is disposed in the cavity 24 via the first and second support portions 26 and 28 constituting the support structure 10.
[0012]
As shown in FIGS. 1 and 2, the sand core 34 surrounds each cylinder bore 36 of the cylinder block 30, and includes a plurality of legs 38 constituting the first support portion 26, and the sand core body 40. Provided integrally. On the side surface (outer surface) 42a opposite to the cylinder bore 36 of the sand core body 40, a baseboard portion 44 constituting the second support portion 28 is formed at a predetermined position.
[0013]
The leg portion 38 is parallel to the axial direction of the cylinder bore 36, and as shown in FIG. 1, an engagement hole 46 is formed from the distal end surface of the predetermined leg portion 38 to a predetermined depth. A pin member 48 for forming a window at the end of the water jacket 32 is inserted into each engagement hole 46. The pin member 48 is made of, for example, aluminum, and integrally includes a columnar portion 50 that fits into the engagement hole 46 and a head portion 52 that abuts against the distal end surface of the leg portion 38.
[0014]
As shown in FIG. 3, the movable mold 18 is formed with a substantially triangular recess 54 for accommodating the head 52 of the pin member 48. The recess 54 is constituted by three wall surfaces 56a, 56b and 56c, and the head 52 is contacted and supported by the wall surfaces 56a to 56c at three points of contact points 58a to 58c.
[0015]
As shown in FIG. 2, the baseboard portion 44 is configured in a substantially half ring shape that protrudes from the side surface 42 a by a predetermined length. As shown in FIG. 1, in the state where the sand core 34 is disposed in the cavity 24, a hot water circulating portion 62 that allows the flow of molten metal is provided between the baseboard portion 44 and the intermediate movable dies 16a and 16b. It is done.
[0016]
A support pin 64 that supports the sand core 34 is fixed to the intermediate movable dies 16a and 16b by welding or screwing corresponding to the hot water runner 62. The support pin 64 is formed of the same material as the intermediate movable molds 16a and 16b, and engages with a pedestal 66 that is fixed to the intermediate movable molds 16a and 16b and the baseboard 44 of the sand core 34. It is comprised integrally from the cylindrical part 68 to do.
[0017]
Operations of the sand core 34 and the support structure 10 configured as described above will be described below.
[0018]
First, as shown in FIG. 1, in a state where the mold 12 is clamped, for example, a molten metal such as molten aluminum is filled into the cavity 24 via a runner and a gate (not shown). Then, the molten metal in the cavity 24 is high-pressure cast at a pressure of about 85 MPa to 100 MPa, and solidification of the molten metal is started.
[0019]
At that time, a high pressure acts on the sand core 34 and the sand core 34 contracts. Specifically, as shown in FIG. 4, a casting pressure F <b> 1 acts on the surface 42 b of the sand core 34 on the cylinder bore 36 side toward the outside, while the sand core 34 has a side facing the cylinder bore 36 side. The casting pressure F1 is acting inward on the opposite side surface 42a.
[0020]
In this case, in the second support portion 28, the baseboard portion 44 of the sand core 34 is provided with a hot water supply portion 62 that allows the flow of molten metal, and the intermediate movable dies 16a and 16b have the hot water supply portion. Corresponding to 62, a support pin 64 that engages with the baseboard portion 44 is provided.
[0021]
Therefore, a uniform casting pressure F1 acts on the side surface 42a of the sand core 34 over substantially the entire surface, and this casting pressure F1 is balanced with the casting pressure F1 acting on the surface 42b of the sand core 34. Therefore, partial deformation of the sand core 34 can be reliably prevented.
[0022]
On the other hand, in the first support portion 26, the pin member 48 is inserted into the engagement hole 46 formed in the leg portion 38, and the head 52 of the pin member 48 is accommodated in the concave portion 54 of the movable mold 18. Yes. At that time, as shown in FIG. 3, the head 52 is supported by contact with the three wall surfaces 56 a to 56 c of the recess 54 at three points of contact points 58 a to 58 c.
[0023]
As a result, the leg portion 38 can be easily and reliably positioned and supported with respect to the concave portion 54, and the sand core 34 can be positioned in the cavity 24 with high accuracy. In addition, a metal (for example, aluminum) pin member 48 is mounted in advance on the leg portion 38, and the head 52 of the pin member 48 is engaged with the recess 54. For this reason, compared with the conventional configuration in which the protrusion provided on the mold side is inserted into the sand core 5 to position the sand core 5, the occurrence of cracks and damage of the sand core 34 is effectively prevented. be able to.
[0024]
Therefore, in this embodiment, the effect that the cylinder block 30 which has the water jacket 32 of a desired shape can be manufactured efficiently and with high precision is acquired.
[0025]
【The invention's effect】
In the sand core support structure for a cylinder block according to the present invention, since the pin member for forming the window portion at the end of the water jacket is mounted in the engagement hole formed in the leg portion, the sand core is Therefore, it is not necessary to insert a protrusion on the mold side into the sand core, and damage to the sand core can be reliably prevented.
[0026]
Further, in the sand core support structure for a cylinder block according to the present invention, the sand core can be made into the cavity only by engaging the pin member mounted on the sand core with the recess formed in the mold. On the other hand, it is possible to accurately support the positioning. Therefore, the sand core is prevented from being damaged, the positioning accuracy of the sand core is improved, and the cylinder block having the water jacket can be cast efficiently and with high accuracy.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional explanatory view of a mold incorporating a support structure for a cylinder block sand core according to an embodiment of the present invention.
FIG. 2 is a schematic perspective view of the sand core disposed in the mold.
FIG. 3 is an explanatory plan view of a first support portion constituting the support structure.
FIG. 4 is an explanatory view when casting pressure acts on the sand core in the mold.
FIG. 5 is a schematic explanatory diagram of a sand core holding device according to the prior art.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Support structure 12 ... Mold 14 ... Fixed type 16a, 16b ... Intermediate movable type 18 ... Movable type 20 ... Bore pin 22 ... Sleeve 24 ... Cavity 26, 28 ... Support part 30 ... Cylinder block 32 ... Water jacket 34 ... In sand Child 36 ... Cylinder bore 38 ... Leg 40 ... Sand core body 44 ... Baseboard 46 ... Engagement hole 48 ... Pin member 50 ... Cylindrical part 52 ... Head 54 ... Recess 56a-56c ... Wall surface 58a-58c ... Contact point 62 ... Hot watering part 64 ... Support pin

Claims (1)

Arranged in a mold for casting the cylinder block,
A sand core for forming a water jacket on the wall surface of the cylinder block is a support structure for a sand core for a cylinder block for supporting the sand core in the mold,
In the sand core,
Legs are provided in parallel with the axial direction of the cylinder bores constituting the cylinder block,
The engagement Goana is formed in the leg portion, a window portion forming pin member of the water jacket end is attached to the engagement hole,
A baseboard portion is formed on the side opposite to the cylinder bore side of the cylinder block,
Around the baseboard part, a hot water circulating part that allows the flow of molten metal is provided,
In the mold,
Provide a support pin that engages with the baseboard and supports the sand core,
Wherein when the sand core is positioned and supported, the engagement hole, the pin member is inserted, and the cylinder block the pin member is characterized that you circumscribing at three points in a recess formed in the mold Support structure for sand core.

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