JPH07108449B2 - Cylinder block manufacturing method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a cylinder block of an internal combustion engine by a pressure casting method, and more particularly to a method for manufacturing a so-called semi-closed type cylinder block having an upper deck.

2. Description of the Related Art As a method of manufacturing a cylinder block of this type, there is one disclosed in Japanese Patent Laid-Open No. 232654/1984.

In this conventional method, a plurality of notches that open downward in advance are formed in an annular water jacket mold for forming a water jacket, and a sand core is formed by leaving a predetermined space above the notches. Casting is performed in the set state, and the sand core is discharged after the casting to integrally obtain an upper deck that closes a part of the upper surface of the water jacket.

However, according to the conventional method as described above, it is extremely difficult to maintain the shape of the core due to the high pressurizing force of the molten metal as a peculiarity of the pressure casting method, and the core is cracked. Alternatively, deformation is likely to occur, and the positioning accuracy between the water jacket mold and the core is not sufficient due to the contact between metal and sand, which limits the improvement of the shape accuracy of the product.

Also, by discharging the sand core after casting, a cooling water passage will be formed in the core part, but the molten core is inserted into the sand core, so the sand core must be completely discharged and removed. Is difficult, and the formation of the cooling water passage is likely to be uncertain.

The present invention has been made in view of the above problems,
A water channel piece made of metal that is easy to handle is used instead of the sand core, and the channel piece is machined after casting so that a cooling water passage can be reliably secured at the same time when the upper deck is formed. It is intended to provide a manufacturing method.

MEANS FOR SOLVING THE PROBLEMS The present invention relates to a method of manufacturing a cylinder block having an upper deck by a pressure casting method as described above, in a portion corresponding to the upper deck in a mold of an annular water jacket for forming a water jacket. Forming a notch, and fitting a metal water channel piece of hollow closed cross-section structure to this notch while leaving a predetermined space to serve as an upper deck on the cylinder head side of the notch before casting. After the casting, the cooling water passage is formed by cutting and removing both side surfaces of the water passage piece cast into the cylinder block.

Action According to the above method, when the casting is completed, the water channel piece having the hollow closed cross-section structure is integrally cast under the upper deck, so for example, a water channel piece is inserted by inserting a drill or the like from the upper opening of the water jacket. A cooling water passage is formed below the upper deck by cutting and removing both side surfaces of the upper deck.

EXAMPLE FIGS. 2 to 5 are views showing an example of a product manufactured by the method of the present invention, in which 1 is a cylinder block, 2 is a cylinder bore, 3 is a water jacket, 4 is an upper deck, and FIG. In the lower part, a box-shaped water channel piece 5 is integrally cast with the cylinder block 1. Since both side surfaces of the water channel piece 5 are open, the adjacent water jackets 3, 3 are in communication with each other via the cooling water passage 6 in the water channel piece 5.

The cylinder block 1 is manufactured by a pressure casting method (pressure die casting method) using, for example, a die 7 shown in FIG. 6, and includes a crankcase die 9 on the lower die 8 side,
This is performed by filling the product part space (cavity) 13 defined by the pair of horizontal molds 10 and 10 and the bore mold 12 on the upper mold 11 side with the molten metal M of aluminum alloy from the gate 14. 15
Is a water jacket mold integrally formed with the bore mold 12, 16 is a sleeve, and 17 is a plunger.

In such pressure casting, as shown in FIG. 1, notches 18 are previously formed at a predetermined pitch in a portion of the water jacket mold 15 corresponding to the upper deck 4 of the product, and the notches 18 are hollow-closed. Sectional metal water channel piece 5
Casting is carried out in the state of fitting.

As the water channel piece 5, for example, as shown in FIG. 7, a steel plate having a predetermined thickness and formed by deep drawing into a bottomed box shape is used, which is covered with a lid by welding or the like, and has a structure in which the entire four sides of the top and bottom are sealed, As shown in FIG. 1, the water channel piece 5 is positioned and fitted into the notch 18 while leaving a space 19 to be the upper deck 4 on the cylinder head side.

When casting is performed using the water jacket mold 15 fitted with such a waterway piece 5, the waterway piece 5 is integrally cast below the upper deck 4 as shown in FIGS. 8 and 9. It is surrounded.

Next, as shown in FIGS. 10 and 11, for the cylinder block 1 in which the water channel piece 5 was cast, a drill D was inserted from the upper opening of the water jacket 3 to perform cutting work, and both side surfaces of the water channel piece 5 were cut. 5a and 5a are removed by cutting. As a result, the inside of the water channel piece 5 functions as a cooling water passage 6 which is a part of the water jacket 3 by cutting and removing both side surfaces 5a, 5a, and the adjacent water jackets 3, 3 will be communicated with each other.

Here, steel is not necessarily used as the material of the water channel piece 5, and any metal material having a melting point equal to or higher than that of the aluminum alloy may be used. Further, depending on the material of the waterway piece 5, the rigidity or pressure resistance of the waterway piece 5 itself may be insufficient. In such a case, the waterway piece 5 is filled with granular material such as sand and then cast. It is preferable that the filling is discharged after the whole body is machined as described above.

EFFECTS OF THE INVENTION According to the present invention, as described above, after cooling the water channel piece having the hollow closed cross-section structure integrally, the both sides of the water channel piece are cut and removed by machining after casting to cool the water passage. Since the contact between the water jacket mold and the water channel piece is metal, the positioning accuracy of the water channel piece is good, and unlike the conventional sand core, there is no occurrence of cracking or deformation. It is possible to obtain a stable quality cylinder block without variations in shape and dimensions.

In addition, since the water channel piece is made of metal, not only is the molten metal not inserted, but after casting, a part of the water channel piece is cut off by machining to form a cooling passage, so the sand core is removed. The formation of the cooling water passage does not become uncertain as in the conventional method of discharging and forming the cooling water passage.

In addition, since the water channel piece is made of metal, it is easy to handle, and, for example, automation of the work of setting the water channel piece on the water jacket mold can be easily realized.

[Brief description of drawings]

FIG. 1 is a perspective view of a water jacket core used in the present invention, FIG. 2 is a plan view of a cylinder block obtained by the present invention, and FIG. 3 is a perspective view of an essential part in which the cylinder block is partially broken. 4, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is a plan view of an essential part of FIG. 3, and FIG. FIG. 7 is a perspective view of a water channel piece, FIG. 8 is a perspective view showing a main part of a cylinder block after casting and before machining, which is broken away, and FIG. 9 is a cross section taken along line IX-IX in FIG. 10 and 11 are perspective views of a cylinder block in which a part of the cylinder block is broken, and FIG. 11 is a sectional view taken along line XI-XI of FIG. 1 ... Cylinder block, 3 ... Water jacket,
4 ... upper deck, 5 ... waterway piece, 5a ... side,
6 ... Cooling water passage, 15 ... Water jacket mold, 18
…… Notch, 19 …… Space, D …… Drill.

Claims (1)

[Claims] 1. A method for manufacturing a cylinder block having an upper deck by a pressure casting method, wherein a notch is formed in a portion of an annular water jacket mold for forming a water jacket, the notch corresponding to the upper deck. On the other hand, a step of casting after fitting a metal water channel piece having a hollow closed cross-section structure leaving a predetermined space to serve as an upper deck on the cylinder head side of the cutout part, A step of cutting and removing both side surfaces of the cast water channel piece to form a cooling water channel, and a method for manufacturing a cylinder block.