JPH0346221B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to a closed deck type cylinder block used in an engine, particularly a cylinder of a water jacket provided between a cylinder barrel and an outer wall surrounding the cylinder barrel. The present invention relates to a method of manufacturing a water jacket in which the cylinder barrel and the outer wall are connected by a plurality of reinforcing deck parts at the end on the head joint surface side, and a communication port on the cylinder head side of the water jacket is formed between the adjacent reinforcing deck parts.

(2) Prior Art Conventionally, in order to form the communication port and the reinforcing deck portion, a protrusion for forming the communication port was provided on the end face of the sand core for forming the water jacket on the cylinder head joint surface side, and the protrusion was It fits tightly into the recessed part that opens on the ceiling surface of the mold cavity. Therefore, degassing within the cavity is performed at a location other than the recess.

(3) Problems to be Solved by the Invention However, when the protrusion is tightly fitted into the recess as described above, the sand core expands due to the molten metal filling the cavity, causing the protrusion to move away from its base end. There is a problem that it easily breaks, resulting in defective products. Furthermore, since the concave portion protrudes from the cavity and is located at the upper part of the mold, it is efficient to vent gas from that portion.

In view of the above, the present invention avoids bending of the protrusion,
Another object of the present invention is to provide the aforementioned manufacturing method that allows efficient degassing.

B. Arrangement of the Invention (1) Means for Solving the Problems The present invention provides for a water jacket provided between a cylinder barrel and an outer wall surrounding the cylinder barrel, at an end portion on the cylinder head joint surface side of the cylinder barrel. In manufacturing a closed deck type cylinder block in which the outer wall parts are connected by a plurality of reinforcing deck parts, and the cylinder head side communication port of the water jacket is formed between the adjacent reinforcing deck parts, the cylinder head joint surface side A sand core for forming a water jacket having a protrusion for forming a communication port on the end face thereof is installed in the cavity of the mold, and the protrusion is loosely inserted into a recessed part opening in the ceiling surface of the cavity, and the end face is opposed to it. A space for forming a reinforcing deck part is formed between the ceiling surfaces of the cavity, and a gas venting passage is formed between the gas venting hole opening in the ceiling surface of the recessed portion and the inner peripheral surface of the gas venting hole. inserting a gas vent pin and arranging the conical tip of the gas vent pin in the recess; pouring molten metal into the cavity and pressure casting a cylinder block material; The method is characterized by using the steps of: cutting out the protruding portion surrounding the protruding portion to obtain the communication port and the reinforcing deck portion.

(2) Effect When the protrusion for forming the communication port of the sand core is loosely inserted into the recess opening into the cavity, when the sand core expands due to the molten metal, the protrusion is allowed to follow the expansion. Folding of the parts is avoided. In addition, the gas that collects in the recess is dispersed and distributed along the conical tip of the gas vent pin and guided to the gas vent passage, so that the gas does not stay in the recess and creates a cavity in the reinforced deck. No casting defects such as these occur.

(3) Embodiment Figures 1 and 1A show a closed deck type Siamese cylinder block S as a closed deck type cylinder block obtained by the present invention, and the cylinder block S includes an aluminum alloy cylinder block body 1 and its cylinder block body 1. It consists of a cast iron sleeve 2 cast into a main body 1. The cylinder block main body 1 includes a Siamese cylinder barrel 3 formed by connecting a plurality of cylinder barrels 3 ₁ to 3 ₄ (in the illustrated example, four cylinder barrels 3 1 to 3 4 ), an outer wall 4 surrounding the Siamese cylinder barrel 3 , and an outer wall 4 . It consists of a crankcase 5 connected to the lower edge, and the sleeve 2 is attached to each cylinder barrel 3 ₁ to _{3 4} .
A cylinder bore 2a is defined by each sleeve 2.

A water jacket 6 is formed between the Siamese cylinder barrel 3 and the outer wall portion 4, and the outer periphery of the Siamese cylinder barrel 3 is exposed to the water jacket 6. At the end of the water jacket 6 on the side of the cylinder head joint surface 1a, the Siamese cylinder barrel 3 and the outer wall 4 are connected to each other.
The spaces between the cylinders are connected by a plurality of reinforcing deck parts 7, and the space between adjacent reinforcing deck parts 7 functions as a communication port 8 to the cylinder head side. As a result, the Siamese cylinder block S is constructed into a closed deck type.

FIG. 2 shows a mold M as a mold for casting the cylinder block material Sm shown in FIGS. 9 and 10. It is composed of first and second side molds 10 ₁ , 10 ₂ arranged in left and right halves, and a lower mold 11 on which both side molds 10 ₁ , 10 ₂ are slidably placed.

The upper mold 9 has four mandrels 12 protruding from its lower surface.
A first cavity C ₁ for molding the Siamese cylinder barrel 3 and outer wall 4 is defined between the mandrel 12 and the molds 10 ₁ and 10 ₂ on both sides, and the molds 10 ₁ and 10 ₂ on both sides and the lower mold A second cavity C ₂ in which the crankcase 5 is formed is defined between the two cavities 11 and 11 .
The upper end of the second cavity _C2 is connected to the first cavity _C1 ,
Moreover, the lower end is a pair of runners 13 formed in the lower mold 11.
are connected to each other via a weir 14.

As shown in FIGS. 3 and 4, the first
A plurality of recesses 15 are formed opening in the ceiling surface of the cavity C ₁ , and small-diameter gas vent holes 16 are opened in the ceiling surface of each recess 15 . Each gas vent hole 16
A gas vent pin 17 is inserted into the gas vent pin 17 to form a gas vent passage p between the inner peripheral surface thereof and the gas vent pin 17 .

As clearly shown in FIGS. 3, 5, and 6, the degassing pin 17 consists of a large-diameter head 17a and a small-diameter shaft portion 17b connected to the large-diameter head 17a.
b is composed of a non-grooved portion 18 on the side of the large-diameter head 17a and a grooved portion 19 connected to the non-grooved portion 18. At the end of the large diameter head 17a on the non-grooved portion 18 side,
Four notches 20 are formed at equal intervals, opening in the annular end surface and the outer peripheral surface on the side of the non-grooved portion 18. The tip 19a of the grooved portion 19 is formed into a conical shape,
Further, the plurality of grooves 21 extend in the axial direction and are arranged at equal intervals in the circumferential direction, and each groove 21 converges at the tip of the conical tip portion 19a.

The enlarged head 17a of the gas vent pin 17 is loosely fitted into the large diameter portion 16a at the top of the gas vent hole 16, and the grooved portion 19 is press-fitted into the small diameter portion 16b at the bottom of the gas vent hole 16. The conical tip 19a is disposed within the recess 15.

Thus, between the large diameter portion 16a and the large diameter head 17a,
Each notch 20, small diameter portion 16b and non-grooved portion 18
Meanwhile, each groove 21 constitutes a gas venting passage p. The cross-sectional area of this gas venting passage p is small, thereby making it possible to suppress pressure leakage during pressure casting.

Figures 7 and 8 show a sand core 22 for forming a water jacket.
The sand core 22 is the cylinder block S.
A core body 24 is provided with four cylindrical portions 23 ₁ to 23 ₄ corresponding to the four cylinder barrels 3 ₁ to 3 ₄ , and has a core body 24 lacking a circumferential wall that overlaps the adjacent ones, and a water A plurality of protrusions 25 protrude from the end surface of the core body 24 on the cylinder head joint surface side to form a communication port 8 that communicates the jacket 6 with the water jacket of the cylinder head, and a cylinder barrel of the core body 24. It is composed of baseboards 26 protruding from both outer surfaces of two cylindrical portions 23 ₂ and 23 ₃ located in the middle in the illustrated example.
The dimensions of each protrusion 25 are set so that it can be loosely inserted into each of the recesses 15.

During pressure casting, each mandrel 12 is fitted into the sleeve 2 in the mold closed state as shown in FIG.
Further, the sand core 22 is sandwiched between the molds 10 1 and ₁₀ 2 on both sides with the cylindrical portions 23 ₁ to 23 ₄ loosely fitted onto the outer periphery of the sleeve ₂ via the baseboards 26 . As a result, each protrusion 25 of the sand core 22 is loosely inserted into the recess 15, a space _s1 is defined around the protrusion 25, and the conical tip 19a of each degassing pin 16 is inserted into each protrusion. It faces the top surface of the section 25. Furthermore, a reinforcing deck molding space _s2 is defined between the end surface of the sand core 22 on the side of the cylinder head joint surface 1a, the inner surface of the first cavity _C1 opposing thereto, and therefore the lower surface of the upper mold 9. . Further, a space s ₃ for forming a Siamese cylinder barrel is defined between the sand core 22 and the sleeve 2, and a space s ₄ for forming an outer wall portion is defined between the sand core 22 and the molds 10 ₁ and 10 ₂ on both sides.

Molten aluminum alloy is supplied from a melting furnace to a sump (not shown) of the lower mold 11, and a planer (not shown) is raised to send the molten metal through both runners 13 and weir 14 from the lower part of the second cavity C ₂ to the second cavity C ₂ . and fills the first cavity _C1 under a predetermined pressure. Gas such as air in both cavities C ₁ and C ₂ is pushed up by the molten metal, and the gas in each cavity C 1 and C 2 is pushed up by the molten metal and
From there, the gas is dispersed and distributed along the conical tip 19a of the gas venting pin 17, and exits above the upper die 9 through the gas venting passage p. In this case, the direction of gas flow is regulated by each groove 21, so that the distributed flow is performed smoothly.

After each concave portion 15 is filled with the molten metal, the molten metal is completely solidified under a predetermined high pressure.

As a result, the cylinder block material Sm shown in FIGS. 7 and 8 is obtained. In this cylinder block material Sm, each protrusion ₂ is
A protrusion 27 made of aluminum alloy is formed so as to surround 5 .

When the protruding portion 27 shown in FIGS. 7 and 8 is removed together with the protruding portion 25 of the sand core 22 to remove sand, it communicates with the opening on the side of the cylinder head joint surface 1a of the water jacket 6 as shown in FIG. 7A. A reinforcing deck portion 7 is formed at the opening of the water jacket 6 on the cylinder head joint surface 1a side, as shown in FIG. 8A.

As described above, the conical tip 19a of the degassing pin 17 allows smooth degassing, which prevents the formation of cavities in the reinforcing deck portion 7 and the reinforcement deck portion 7 and the sleeve due to the entrainment of gas into the molten metal. Casting defects such as poor welding with 2 do not occur.

C. Effects of the Invention According to the present invention, since the protrusion for forming the communication port of the sand core is loosely inserted into the recess opening into the cavity, when the sand core expands due to the molten metal, the protrusion can follow the expansion. This avoids bending of the protrusions, making it possible to obtain a closed-deck cylinder block with excellent casting quality.

Furthermore, since the concave portion protrudes from the cavity and is located at the top of the mold, gas is collected in the concave portion, and by distributing the gas along the conical tip of the gas vent pin, it is distributed and guided to the gas vent passage. This makes it possible to prevent gas from accumulating in the recessed portions, thereby avoiding the formation of cavities and other casting defects in the reinforcing deck portion.

[Brief explanation of drawings]

Fig. 1 is a plan view of the cylinder block, Fig. 1A is a cross-sectional plan view of the cylinder block, and Fig. 2 is a plan view of the cylinder block.
Figure 3 is an enlarged view of the main parts of Figure 2, Figure 4 is an enlarged sectional view of the mold corresponding to Figure 1 - line cross section, Figure 5 is an enlarged sectional view of the mold corresponding to the line cross section.
Figure 6 is an enlarged view of the main parts of the figure, Figure 6 is a cross-sectional view taken along the line shown in Figure 5, Figure 7 is a perspective view of the sand core, Figure 8 is a cross-sectional view taken taken along Figure 7, and Figure 9 is shown in Figure 3. Fig. 9A is an enlarged sectional view of the main part of the cylinder block material corresponding to Fig. 9; Fig. 10 is an enlarged sectional view of the main part of the cylinder block material corresponding to Fig. 4. , FIG. 10A is an enlarged sectional view of the main part of the cylinder block corresponding to FIG. 10. C ₁ , C ₂ ... First and second cavities, M ... Mold as mold, p ... Gas vent passage, s ₂ ... Space, 1a ... Cylinder head joint surface, 3 ... Siamese cylinder barrel , 4...Outer wall section, 6...
Water jacket, 7...Reinforcement deck portion, 8...Communication port, 15...Concave portion, 16...Gas vent hole, 17
...Gas vent pin, 19a...Conical tip, 2
2...Sand core, 25...Protrusion, 27...Protrusion.

Claims (1)

[Claims] 1 At the end of the cylinder head joint surface side of the water jacket provided between the cylinder barrel and the outer wall surrounding the cylinder barrel, the cylinder barrel and the outer wall are connected by a plurality of reinforcing deck parts, A sand core for forming a water jacket having a protrusion for forming a communication port on the end face on the cylinder head joint surface side when manufacturing a closed deck type cylinder block with a communication port on the cylinder head side of the water jacket between the reinforcing deck parts. is installed in a cavity of a mold, the protrusion is loosely inserted into a recessed part opening in the ceiling surface of the cavity, and a space for forming a reinforcing deck part is formed between the end surface and the ceiling surface of the cavity opposite thereto; Further, a gas venting pin that forms a gas venting passage between the gas venting hole and the inner peripheral surface of the gas venting hole is inserted into the gas venting hole opening in the ceiling surface of the concave portion, and the conical tip of the gas venting pin is arranging the protrusion in the recess; pouring molten metal into the cavity and pressure-casting the cylinder block material; cutting off the protrusion surrounding the protrusion from the cylinder block material to form the communication port and the reinforcing deck part. A method for producing a closed deck type cylinder block, characterized by using the steps of: obtaining;