JP2000190059A - Combination of closed deck type cylinder block casting device and sand core used for the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cast a closed deck type cylinder block with high dimensional accuracy while a sand core is precisely held in a die, eliminate necessity of rigid dimensional management for a projection part of the sand core, and facilitate checking and removal of the sand left at a sand core holding part. SOLUTION: A projection part 52b extending towards an axial direction of a cylinder liner for holding a sand core is integrally protruded from a slide core 52 on a movable die side, and a holding hole 51c to be fitted with the projection part for holding the sand core is formed on a top deck side end face 51d of a sand core 51, so as to perform casting under the condition that the holding projection part is inserted in the holding hole. Additionally, the top deck side end face 51d is a flat face without projections or indentations, and a concave part 52a for bridge forming is formed on an end face 52d of the slide core. Then, casting is performed under the condition that the end face 52d except for the concave parts 52a abuts on the flat face.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combination of a closed deck type cylinder block casting apparatus and a sand core used in the apparatus, and more particularly, to a method for casting a sand core properly held in a casting apparatus. And a combination of a closed deck type cylinder block casting apparatus and a sand core used in the apparatus.

[0002]

2. Description of the Related Art In order to reduce engine vibration and reinforce a cylinder block, a closed deck type cylinder block having a bridge portion connecting a top deck of a cylinder head and an outer end of a cylinder is known. . In this configuration, a part of the upper end opening of the water jacket is covered by the bridge portion, in other words, the upper end opening of the water jacket is a window defined by the bridge portion. As described above, since the closed deck type cylinder block has an undercut in the water jacket portion, it is necessary to form the sand core and cast it, and then collapse and remove the sand core. During casting, it is necessary to properly hold the sand core in the mold.

Japanese Patent Application Laid-Open No. 1-178361 discloses a black
A method for holding a sand core in a mold when casting a pseudo-deck type cylinder block is described. In the invention described in this publication, a sand core 101 for forming a water jacket surrounding three cylinders as shown in FIG.
A projection 101a for forming a window, which engages with the second recess 102a, is protruded. In addition, independent of a driving device (not shown) for moving the movable die 102 toward and away from a fixed die (not shown), a driving means (not shown) for driving a holding pin is provided. It is provided so as to be able to penetrate through the movable die 102 by means and to enter and exit the cavity. A portion of the end surface of the sand core 101 where the window portion forming projection 101a is not protruded is filled with a molten metal to form a known bridge portion on the end surface of the water jacket.

The holding pin 103 is projected into the cavity, and a sand core for forming a water jacket is temporarily placed thereon (FIG. 12). Thereafter, a window for forming a window portion is provided on the axial end face of the sand core. The notch 102a formed on the movable die 102 is engaged with the protrusion 101a, and the protrusion 101b formed on the outer peripheral surface of the sand core is also engaged with a not-shown recess formed on the movable die. The child is held in a mold, and the holding pin 103 is retracted. The sand core 101 is properly held in the mold by the protruding and retracting operation of the holding pin 103.

[0005]

In the invention described in the publication, the final holding of the sand core 101 in the mold is performed by the projection 101a for forming the window and the recess 102a of the mold, and the projection 10 for holding.
1b is engaged with a not-shown recess. Therefore, in order to maintain the positional accuracy of the sand core 101, the mold recess 102a is required.
It is necessary to reduce the clearance between the projection and the window forming projection 101a. However, in order to reduce the clearance, strict dimensional control is required, which increases the cost. In detail, the sand core 101 is coated so that the molten aluminum does not penetrate into the core. However, the coating thickness of the coating agent varies. It is necessary to strictly control the coating amount of the coating agent.

Also, at the time of forming a sand core, a projection 10 for forming a window portion is formed.
The filling of the sand into 1a is worse than other parts, the strength of the part is lowered and the part is easily broken, and the core binder is burned by the heat at the time of casting, the core strength is reduced, and the protruding part is particularly difficult. It breaks and becomes dull. Further, if an excessive force is applied when the product is taken out, the window forming projection 101a is broken, and sand remains in the recess 102a. When the next sand core 101 is set and the mold is closed while the sand in the concave portion 102a remains, an excessive force acts on the sand core and the sand core is broken before casting. Therefore, the recess 102
Although it is necessary to remove the sand remaining in a, it is difficult to confirm the remaining sand because of the concave portion, and it is difficult to clean the sand. In addition, the mold on which the sand core can be set is limited to a device having a built-in slidable holding pin 103 for mounting the sand core.

Therefore, the present invention makes it possible to cast a closed deck type cylinder block having high dimensional accuracy by accurately holding a sand core in a mold, and to provide a projection for forming a window portion of the sand core. Strict dimensional control of the part is not required, and even if the sand core breaks and sand remains in the sand core holding part, the residual sand can be easily confirmed and cleaning can be easily performed, and the driving device for the holding pin An object of the present invention is to provide a combination of an unnecessary closed deck type cylinder block casting apparatus and a sand core used in the apparatus.

[0008]

In order to achieve the above object, the present invention provides a water jacket surrounding a plurality of cylinder liners arranged side by side, and a part of an upper end opening of the water jacket is formed on a top deck. In order to manufacture a closed deck type cylinder block covered with a bridge portion and a window portion other than the bridge portion serves as a window portion, a sand core for forming a water jacket is cast while being held in a mold that is opened and closed in a horizontal direction. In a combination of a closed deck type cylinder block casting apparatus and a sand core used in the apparatus, a projection for holding a sand core extending in the axial direction of the cylinder liner 5 is provided in the mold of the casting apparatus. 2b, 2
b ', 2b "and 52b are protruded in the horizontal direction integrally with the mold, and the sand cores 1 and 51 are provided with holding holes 1c and 1c' through which the sand core holding projections are inserted. , 1c ", 51c
Is formed, and the end surface on the top deck side of the sand core 51 is formed with a flat surface 51d without unevenness, and the facing surface 52d of the mold facing the flat surface 51d forms the bridge portion and the window portion. For this purpose, a concave portion 52a and a convex portion, which are uneven in the axial direction of the cylinder liner, are formed, and an end surface of the convex portion is provided so as to be in contact with the flat surface of the sand core. A closed deck type cylinder block casting apparatus in which casting is performed in a state in which a portion is inserted into the holding hole and an end surface of the projection is in contact with the flat surface, and a sand block used in the apparatus. Offers a combination with a child.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A closed deck type cylinder block casting apparatus according to a first embodiment of the present invention and a case where a sand core used in the apparatus is applied to the casting of a V-type 6 cylinder cylinder block. This will be described with reference to FIGS.

FIG. 1 shows a sand core 1 for forming a water jacket for three cylinders on one side when casting a V-type six-cylinder cylinder block.
Shows a state where the sand core 1 is set in the mold cavity. Here, the mold cavity 6 includes the slide core 2
And a fixed die 8 and a pair of first slide cores 22 and 2
2 and a pair of second slide cores 23, 23.

FIG. 2 is a sectional view taken along the dashed line II-II in FIG. 1 showing a state where the sand core 1 is held on the slide core 2. A concave portion 2a is formed on the cavity surface 2d of the slide core 2, and a window forming protrusion 1a inserted into the concave portion 2a is formed on an end surface 1d of the sand core 1 facing the cavity surface 2d. It is protruding. Here, a gap S1 is formed at a predetermined interval between the end face 1d of the sand core where the window forming projection 1a is not protruded and the cavity face 2d, and the gap S1 is filled with molten metal, and It becomes a known bridge portion on the jacket end surface.

A recess 23a is formed in the pair of second slide cores 23, 23. The recess 23a is formed on the outer peripheral surface of the sand core 1 in order to position and fix the sand core 1 in the cavity 6.
A pair of skirting boards 1b engaging with a are protruded.

Further, from the end face 1d of the sand core 1, a holding hole 1c having a circular cross section through which a holding projection 2b described later is inserted.
Are formed in four places. A portion 1e of the sand core 1 surrounding the adjacent portion of the cylinder liner 5 is formed thicker than other portions (FIGS. 1 and 3), and has a holding hole 1c.
Are formed in the thick portion 1e so as to withstand the casting pressure.

The clearance S2 between the window forming projection 1a of the sand core 1 and the recess 2a formed in the slide core 2 is relatively large, for example, 0.5 to 1.0 mm.
It is about. By increasing the clearance, the clearance can be burred when filling the molten metal,
Residual sand in the concave portion 2a can be removed together with burrs. Since the purpose is to make burrs, the molten metal pressure acts on both end surfaces of the sand core 1 in the axial direction of the cylinder liner. The baseboard portion 1b and the concave portion 23a that engages with the baseboard portion 1b are required.

As shown in FIGS. 5 and 6, a pair of slide cores 2 and 2 are disposed on both sides of the movable die 12, respectively.
The first slide cores 22, 22 and the second slide cores 23, 23 described above are provided movably around the slide cores 2, 2, and the fixed die 8 and the slide cores 2, 2, first, second The outer surfaces of the cylinder block for the V-type six-cylinder engine are defined by the slide cores 22, 22, 23, and 23 and the movable die 12. Each of the slide cores 2 is provided with a cylindrical projection 2c for mounting the cylinder liner 5, and a sand core holding projection 2b extending in the axial direction of the cylinder liner 5 is integrated with the slide core 2. 2
From the inside toward the inside of the cavity 6. Here, the holding protrusion 2b has a circular cross section, and is provided with a tapered draft so that the holding protrusion 2b can be easily pulled out after casting, and the hole surface of the holding hole 1c is also a corresponding inclined surface. I have. FIGS. 5 and 6 show the respective cylinder liners 5.
2 shows a state in which the cylinder liner 5 is held so that the axis of the cylinder liner is in a horizontal plane. Reference numeral 7 denotes a runner for supplying molten metal into the cavity 6.

Next, the casting process according to the present embodiment will be described. In the mold opening state shown in FIG. 5, the sand core 1 is held on the slide core 2 by engaging the holding projection 2 b of the slide core 2 with the holding hole 1 c of the sand core. Then, after the cylinder liner 5 is mounted on the cylinder liner mounting projection 2c, the first slide core 22 and the second slide core 23 are moved to move the entire movable die, and the fixed die as shown in FIG. 8 define the cavity 6. Thereafter, the molten metal is filled from the runner 7 to cast a cylinder block.

Since the sand core 1 is supported by the holding projections 2b during casting, it is accurately held in the mold. Further, by the engagement between the baseboard portion 1b of the sand core 1 and the concave portion 23a, the sand core 1 is also acted upon by the action of the molten metal pressure before and after the sand core in the axial direction.
It is held without moving in the cavity 6. Since the clearance S2 between the window-forming projection 1a and the recess 2a is large, the clearance can be burred at the time of filling the molten metal, and the residual sand separated from the sand core projection 1a in the recess 2a is taken out. Sometimes it can be removed with burrs.
In detail, the binder contained in the sand core 1 is decomposed by the heat of the molten metal, the strength of the core is weakened, and a part of the sand of the window forming projection 1a may be detached. Since the clearance S2 can be increased, the molten metal penetrates into the clearance S2 to form burrs, and the periphery of the window forming projection 1a is surrounded by the burrs.

After casting, the mold is opened and the product is taken out. At this time, the sand detached by the window forming projection 1a can be taken out together with the product together with the burr, and the sand in the recess 2a can remain. Sex is extremely low. Although the product is taken out together with the sand core 1, a part of the sand may adhere to the periphery of the holding projection 2b. However, since the holding projection 2b is a protrusion, the fact that sand adheres can be easily confirmed, and the sand can be easily removed from the holding projection 2b. Next, the sand core 1 is taken out of the window of the water jacket. Then, as a post-process, in order to close a hole of the product corresponding to the baseboard portion 1b, the hole is formed with a female screw, and a plug with a male screw (not shown) is screwed into the female screw.

In this embodiment, the holding projection 2 on the mold side is used.
b is inserted into the holding hole 1c formed in the sand core 1 to hold the sand core 1 in the mold, and the window core forming protrusion and the concave portion engaging with the window core hold the sand core 1 Therefore, the clearance between the two can be made relatively large.
For this reason, the binder contained in the core is decomposed by the heat of the molten metal, and the strength of the core is weakened. Since it can be made larger, the molten metal can enter the clearance and become burrs, and the sand released by the burrs around the window forming projections can be taken out together with the product, and the possibility of sand remaining in the recess is extremely low This has the effect.

Further, since the core is held by the holding protrusion 2b protruding from the mold and the holding hole 1c formed in the sand core, even if sand remains on the holding protrusion 2b. Since the holding projection 2b is a protrusion, it is easy to check the residual sand,
Cleaning of the mold is simple and reliable, and productivity can be improved.

Next, a closed deck type cylinder block casting apparatus according to a second embodiment of the present invention and a sand core used in the apparatus will be described with reference to FIGS. In the first embodiment, the recess 2 of the slide core 2
In order to prevent the residual sand in the a, a clearance S2 is also secured between the concave portion 2a and the window forming convex portion 1a of the sand core 1, and the molten metal is also positively contained in the clearance S2. , It is necessary to remove burrs after casting.
In addition, due to the filling of the molten metal, the molten metal pressure acts on the entire end face 1d of the sand core, and the sand core 1 is connected to the cylinder liner in relation to the molten metal pressure acting on the rear end face 1f of the sand core 1. The baseboard 1b is required to prevent the baseboard 1b from moving in the axial direction. Therefore, post-processing as described above is required. The second embodiment is an improvement on this point.

As shown in FIGS. 7 and 8, the sand core 51 according to the second embodiment has a flat end face 51d facing the slide core 52 without any unevenness, and a baseboard portion (FIG. 1). 1b) is different from the sand core 1 according to the first embodiment in that it is not provided. Then, the end surface (the surface facing the top deck side end surface 51d of the sand core 51) 52d of the slide core 52 according to the second embodiment 52d
Is formed with a concave portion 52a for forming a bridge portion, and the end surface 52d of the slide core 52 in a portion where the concave portion 52a is not formed abuts with the end surface 51d of the sand core 51 without a gap, so that the end surface of the water jacket is formed. It becomes a window. In other words, in the second embodiment, there is no need to provide the window forming projection 1a in the first embodiment on the end face of the sand core 1, and the sand core end face 51d may be flat. In addition,
The portion of the slide core 52 where the concave portion 52a is not formed
Can be said to be a convex portion. Further, in the top deck side end surface 51d of FIG. 7, the hatched portion is a place where a bridge portion is formed after casting.

As in the first embodiment, the movable die 1
A pair of slide cores 52, 52 are arranged on both sides of 2,
The first slide cores 22, 22 and the second slide cores 23A, 23A described above are movably provided around the slide cores 52, 52, and the fixed die 8 and the slide core 2,
2, the first and second slide cores 22, 22, 23A, 23
The outer surface of the cylinder block for a V-type 6-cylinder engine is defined by A and the movable die 12. Each of the slide cores 52 is provided with a cylindrical projection for mounting the cylinder liner 5, and the sand core holding projection 52 b extending in the axial direction of the cylinder liner 5 is integrated with the slide core 52. Projecting from the cavity 52 into the cavity 56. Here, the shape of the holding projection 52b and the shape of the holding hole 51c are the same as those of the first embodiment.

Here, the second slide cores 23A, 23A
Since there is no need to support the baseboard, the recess (23a) in the first embodiment is not formed. In the mold clamping state, the front end face 51 d of the sand core 51 is
Are set without any gap so as to abut the end face 52d of the second member.
The sand core 51 is securely held in the cavity 56 by the engagement between the sand core holding projection 52b and the holding hole 51c.

When the cavity 56 is filled with the molten metal in this state, the advance limit of the sand core 51 in the axial direction of the cylinder liner 5 is defined by the contact with the facing surface 52d of the slide core 52, but the retreat limit is defined. It has not been. However, due to the difference in the melt pressure acting on the front end face 51d and the rear end face 51f of the sand core 51, the sand core 51 is urged in a direction in which the front end face 51d comes into close contact with the opposing face 52d of the slide core 52. That is, the force (melt pressure) F1 acting on the front end face 51d side of the sand core 51 is F1 = P × (ab), but the sand core 5
The force (melt pressure) F2 acting on the rear end face 51f of the first F1 is F2 =
P × a, and F2> F1. Here, P is the casting pressure, a is the area of the sand core front end face 51d (or rear end face 51f), and b is the area where the sand core front end face 51d and the facing surface 52d of the slide core 52 are in contact. As described above, due to the difference in the molten metal pressure caused by the difference in the molten metal contact area between the front end surface 51d and the rear end surface 51f of the sand core, the sand core 51 is urged in the forward limit direction at the time of casting, thereby positioning in the axial direction. So that
In the second embodiment, the baseboard portion (1b) becomes unnecessary.

By casting, the molten metal enters the recess 52a to form a bridge portion, and the portion where the front end face 51d of the sand core and the opposing face 52d of the slide core 52 are in close contact is the window portion at the end of the water jacket. Becomes After casting, the mold is opened and the product is taken out. At this time, the front end face 51 d of the sand core 51 has no irregularities, and the opposing face 52 of the slide core 52.
Since it is not engaged with d, there is no sand residue in the mold.

In the second embodiment, similarly to the first embodiment, the sand core holding projection 52b and the holding hole 51 are provided.
c, the sand core 51 is surely secured to the cavity 56.
Is held within. However, unlike the first embodiment, since it is not necessary to actively form burrs for the purpose of removing sand, the sand core front end face 51d side can be in close contact with the slide core, and as a result, as described above, The difference in the molten metal contact area between the front end face 51d and the rear end face 51f of the sand core is increased, and the entire sand core 51 can be urged forward by the molten metal pressure to position the core. Therefore, post-processing (filling of a cast product when there is a baseboard) is unnecessary.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope described in the claims. For example, in the above-described embodiment, the holding projections 2b and 52b and the holding holes 1c and 51c are provided at four places, respectively. However, as long as the sand cores 1 and 51 can be held, two or more places. Good. The dice on which the sand core can be set is applicable to any dice as long as the core does not fall under its own weight.

Further, the above-described embodiment is applied to a V-type six-cylinder closed type cylinder block, but is a series-closed cylinder block, for example, a cylinder block for an in-line four-cylinder or an in-line six-cylinder engine. Needless to say, the present invention can be applied also to this.

In addition, the shapes of the holding projections 2b and 52b and the holding holes 1c and 51c are not limited to circular cross-sections, but are shown in FIG.
A holding projection 2b 'having a substantially triangular shape (FIG. 10) or a square shape (FIG. 11) like a cross section along the X-ray or the XI-XI line;
2b "and holding holes 1c 'and 1c". Also,
The depth of the holding hole 1c may be any depth as long as it can be held, and may be appropriately selected depending on the size and type of the cylinder block and the degree of inclination during casting. Holding hole 1
The positions of c and 51c are not limited to the portion surrounding the adjacent cylinder liner, and as long as the mechanical strength is secured, 1c ″ in FIG.
As in the above, it may be formed at a position other than the adjacent part of the cylinder liner.

[0031]

According to the combination of the closed deck type cylinder block casting apparatus and the sand core used in the apparatus, the sand core is held at a holding position at a part of the sand core. And a holding projection that can be inserted into the holding hole is provided integrally with the mold, so that the position of the core at the window forming projection and the mold recess is different from the conventional case. It is not necessary to ensure accuracy, and the position accuracy of the sand core can be improved without strictly controlling the clearance between the two.

Further, since the core is held by the holding projections formed in the mold and the holding holes formed in the sand core, even if the sand remains on the holding projections, the holding is performed. Since the protruding portion is a protruding material, it is easy to check the residual sand, and the cleaning of the mold is simple and reliable, so that the productivity can be improved.

Furthermore, since the end surface of the sand core on the top deck side is formed as a flat surface without irregularities, not only the manufacturing of the sand core is simplified, but also because of the flat surface, the problem of sand residue occurs. Absent. Then, a concave portion is formed on the opposite surface of the mold facing the flat surface to cast the bridge portion. During casting, the surface of the flat surface other than the portion facing the concave portion is in close contact with the mold. Therefore, there is a difference between the molten metal pressures acting on the flat surface side and the rear end surface side of the sand core, so that the entire sand core is urged toward the facing surface of the mold, and Since the core is positioned, there is no need to provide a skirting part in the sand core, making it easier to manufacture the sand core and eliminating the need for post-processing of the cast product due to the skirting part. To play.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a sand core for forming a water jacket used for casting a closed deck type cylinder block according to a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a mold including a slide core of a casting apparatus for a closed deck type cylinder block according to a first embodiment of the present invention and a sand core for forming a water jacket held by the slide core. FIG.

FIG. 3 is a plan view showing the vicinity of a holding hole of a sand core for forming a water jacket according to the first embodiment of the present invention.

FIG. 4 is a schematic sectional view taken along the line IV-IV of FIG. 6 showing a mold and a sand core for forming a water jacket of the casting apparatus for the closed deck type cylinder block according to the first embodiment of the present invention; .

FIG. 5 is a cross-sectional view showing a closed deck type cylinder block casting apparatus in a mold opened state and a sand core for forming a water jacket mounted on the apparatus according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a closed deck type cylinder block casting apparatus in a mold-clamped state and a sand core for forming a water jacket mounted on the apparatus according to the first embodiment of the present invention.

FIG. 7 is a perspective view showing a sand core for forming a water jacket used for casting a closed deck type cylinder block according to a second embodiment of the present invention.

FIG. 8 is a schematic sectional view showing a mold including a slide core of a casting apparatus for a closed deck type cylinder block according to a second embodiment of the present invention, and a sand core for forming a water jacket held by the slide core. FIG.

FIG. 9 is a partially omitted perspective view showing a modification of the embodiment according to the present invention.

FIG. 10 is a sectional view taken along the line XX of FIG. 9;

FIG. 11 is a sectional view taken along the line XI-XI in FIG. 9;

FIG. 12 is a perspective view showing a sand core for forming a water jacket used for casting a conventional closed deck type cylinder block.

FIG. 13 is a schematic sectional view showing a slide core of a conventional closed deck type cylinder block casting device and a part of a water jacket held by the slide core.

[Explanation of symbols]

 1, 51 Water core forming sand core 1a Window forming protrusion 1c, 1c ', 1c ", 51c Holding hole 2, 52 Slide core 2b, 2b', 2b", 52b Holding protrusion 5 Cylinder liner 1d , 51d Sand core front end face (top deck side end face) 52a, recessed part 1f, 51f Sand core rear end face

Claims (1)

[Claims] 1. A closed structure in which a water jacket surrounding a plurality of cylinder liners arranged side by side is formed, a part of an upper end opening of the water jacket is covered with a bridge part on a top deck, and a part other than the bridge part is a window part. In order to manufacture a deck-type cylinder block, a closed deck-type cylinder block casting apparatus for holding a sand core for forming a water jacket in a mold that is opened and closed in a horizontal direction and casting the same is used for the apparatus. In a combination with a sand core, a sand core holding projection extending in the axial direction of the cylinder liner is provided in the mold of the casting device so as to project in a horizontal direction integrally with the mold. The sand core is formed with a holding hole through which the sand core holding projection is inserted, and the top deck side end surface of the sand core is formed with a flat surface without irregularities. Opposite surfaces of the mold facing each other are formed with a concave portion and a convex portion having irregularities in the axial direction of the cylinder liner to form the bridge portion and the window portion, and the end surface of the convex portion is formed of the sand core. Casting is performed in a state where the flat surface is in contact with the flat surface, and the sand core holding projection is inserted into the holding hole, and the end surface of the projection is in contact with the flat surface. A combination of a closed deck type cylinder block casting apparatus and a sand core used in the apparatus.