JPH0466258A - Cast iron-made cylinder block and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture a compact cast iron-made cylinder block having easy machining, high wear resistance and high cooling efficiency by inserting a linear with the cast iron under condition of fitting a water jacket core at between both end thin parts. CONSTITUTION:In the inner 5 formed with iron series material having high wear resistance, an upper projecting part 11 and a lower projecting part 12 are formed. At near the upper projecting part 11 and the lower projecting part 12, the upper thin part 13 and the lower thin part 14 are formed as circular along outer periphery of the liner 5. In hollow part at inside of the above liner 5, bore core 3 is packed. Successively, the water jacket core 2 is fitted at between the upper thin part 13 and the lower thin part 14. Further, these are set to the master mold 1 and the molten cast iron is poured in cavity 4. In there, as both thin parts 13, 14 have thin thickness, these are perfectly melted and integrally melted with the molten iron.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cast iron cylinder block and a method for manufacturing the same.

[Prior Art] In order to reduce the weight and size of automobiles, Siamese type cylinder blocks or aluminum alloy cylinder blocks are often used. However, since aluminum alloy has low heat resistance and wear resistance, a method of manufacturing a cylinder block has been proposed in which only the liner (cylinder liner) is made of cast iron, and this cast iron liner is then cast with aluminum alloy ( For example, see Japanese Patent Application Laid-Open No. 58-211550).

However, in a diesel engine, since the heat load is high, sufficient durability cannot be obtained when an aluminum alloy cylinder block is used. In addition, since the vibration is strong, vibration noise (NV
H) becomes larger. For this reason, a cast iron cylinder block made of cast iron is generally used in a diesel engine.

[Problems to be Solved by the Invention] Incidentally, foreign matter such as dust may enter the piston sliding surface of the liner portion of the cylinder block, and this foreign matter may cause damage to the piston sliding surface. For this reason, it is necessary to sufficiently increase the wear resistance of the piston sliding surface of the liner, but it is said that ordinary cast iron cylinder blocks made by casting cannot sufficiently increase the wear resistance of the piston sliding surface. There's a problem.

One possible solution to this problem would be to press-fit a liner made of a highly wear-resistant material into the cast iron cylinder block body, but doing so would require ensuring a press-fit allowance around the liner press-fit portion. , the pitch between the bores of the cylinder block becomes longer. Therefore, there is a problem that the cylinder block becomes longer in the longitudinal direction and becomes larger.

Another option is to cast the cylinder block from a cast iron material with high hardness, but this increases the hardness of the entire Norinda block, making machining of the cylinder block body difficult.

Therefore, as shown in FIG.
In a mold DC consisting of a water jacket core 2 and a bore core 3, a liner 5 made of a highly wear-resistant material is fitted into the bore core 3, and a water jacket core is placed around the outer periphery of the liner 5. 2 is installed, the bore core 3 is set in the mother mold l to form a cavity 4 of a predetermined shape, and molten cast iron is poured into the cavity 4.
The main body 7 and the water jacket 8 as shown in FIG.
By obtaining a wet liner type cylinder block B having a liner section 9 and a liner section 9, the liner section 9 has high wear resistance, the main body section 7 can be easily machined, and the cooling efficiency is high. It was thought that a compact cylinder block B could be obtained.

However, in the cylinder block B cast in this manner, joint failures frequently occur at the joint surfaces of the liner and the cast material, which may deteriorate the sealing performance of the water jacket 8 and cause leakage of cooling water. The facts were revealed.

Of course, such leakage of cooling water can be prevented by forming a water jacket within the wall thickness of the cylinder block body, that is, by not using a wet liner type, but diesel engines have a high heat load. Therefore, a wet liner type cylinder block with high cooling efficiency is very effective.

The present invention has been made in view of the above-mentioned conventional problems, and has a compact main body that is easy to machine, has high wear resistance on the piston sliding surface of the liner, and has high cooling efficiency. The object of the present invention is to provide a wet liner type cast iron cylinder block and a method for manufacturing the same.

[Means for Solving the Problems] The present inventors conducted further detailed research on a method for manufacturing a wet liner type 7 linder block by casting a separately formed liner with cast iron, and found that the liner and It has been discovered that poor joining of casting materials is caused by the fact that the molten metal is rapidly cooled by contact with the liner during pouring, and the liner and the casting material are not completely fused and integrated. Therefore, the inventors of the present application have found that by reducing the heat capacity of the part of the liner that comes into contact with the molten metal, rapid cooling of the molten metal can be prevented and the fusion of the liner and the molten metal (casting material) can be promoted. I thought it would be.

In view of these facts and considerations, and in order to achieve the above object, the invention of claim 1 provides a wet liner type cast iron cylinder block in which a separately formed liner is cast in cast iron. In this process, a liner is formed with thin-walled parts around the upper end and around the lower end that are exposed inside the mold cavity during casting, and a water jacket core is attached between the two thin-walled parts. To provide a cast iron cylinder block characterized in that it is formed by casting.

Further, the invention of claim 2 provides a method for manufacturing a cast iron cylinder block in which a wet liner type cylinder block is cast by casting a separately formed liner with cast iron, in which the upper end of the liner is Thin-walled parts were provided around the circumference and around the lower end, and a water jacket core was attached to the liner between the thin-walled parts, and then molten cast iron was poured into the mold cavity to cast the cylinder block. A method for manufacturing a cast iron cylinder block is provided.

[Operations and Effects of the Invention] According to the invention of claim 1, since the heat capacity of the thin wall portion of the liner is small, the molten metal around the thin wall portion is not rapidly cooled during pouring. Therefore, since the thin-walled portion comes into contact with the high-temperature molten metal, the thin-walled portion is completely melted, the molten metal (casting material) and the liner are completely fused and integrated, and the bonding strength between the casting material and the liner is increased. Therefore, the sealing performance of the water jacket is improved. In addition, since it is a wet liner type, it goes without saying that the cooling efficiency is increased.

According to the second aspect of the invention, the thin walled portion of the liner is exposed to the cavity so that the liner is cast, but since the heat capacity of the thin walled portion is small, the molten metal around the thin walled portion is not rapidly cooled during pouring. Therefore, since the thin wall portion can be brought into contact with the high temperature molten metal, the thin wall portion can be completely melted and the molten metal and the liner can be completely fused and integrated.

Therefore, the liner and the casting material can be firmly joined, and a cylinder block with high water jacket sealing performance can be manufactured.

[Example] Examples of the present invention will be specifically described below.

<First Example> In the first example, a mold DC similar to the conventional one is basically provided with a mother mold l, a water jacket core 2, and a bore core 3 as shown in FIG. By pouring molten cast iron into cavity 4 using to be cast.

However, the configuration of the liner 5 used for casting is different from conventional ones.

That is, as shown in FIG. 1, an upper end protrusion 11 and a lower end protrusion 12 are formed at the upper and lower ends of the liner 5, which is made of a highly wear-resistant iron-based material, respectively. .

The upper end protrusion 11 and the lower end protrusion 12 are respectively connected to the liner 5.
It is formed in an annular or flange shape over the entire circumference, and its thickness (in the vertical direction) is set relatively thick.

Both protrusions 11.12 are attached to the liner part 9 (after casting).
This is provided to firmly fix the liner section 9 (see FIG. 5) to the main body section 7 (see FIG. 5) and to prevent the liner section 9 (see FIG. 5) from shifting. In addition, both protrusions 11.12
may be formed partially along the circumference of the liner 5 instead of over the entire circumference of the liner 5.

Further, an upper thin wall portion 13 is formed slightly below the upper end protrusion 11 of the liner 5, and a lower thin wall portion 14 is formed slightly above the lower end projecting portion 12. Upper thin wall portion 13
The lower thin wall portion 14 is formed in an annular or fin shape along the outer periphery of the liner 5, and the thickness thereof is set to be relatively thin in order to reduce heat capacity. Both thin-walled portions 13° and 14 protrude into the cavity 4 during casting, and as will be explained later, during the melting process. h (casting material) and liner 5 are completely joined, and water jacket 8 (fifth
(see figure) is provided to improve sealing performance.
It is also used to hold the water jacket core 2 during mold assembly.

The method for manufacturing the Norinda block B (see FIG. 5) will be described below.

(2) Fill the hollow part inside the liner 5 with a bore core 3 made of foundry sand.

(2) Attach the water jacket core 2 to the outer peripheral surface of the liner 5 between the upper thin wall portion 13 and the lower thin wall portion 14. At this time, the water jacket core 2 has both thin wall portions 1
3.14 and is securely held by the liner 5. Therefore, there is no need to provide any particular means for holding the water jacket core 2.

■Set the liner 5 together with the bore core 3 and the water jacket core 2 on the matrix l. Here, both protrusions 11.
12 and both thin-walled portions 13 and 14 each protrude into the cavity 4 in a direction perpendicular to the axis of the liner 5.

■Pour molten cast iron into cavity 4.

Here, since both thin-walled portions 13.14 are thin and therefore have a small heat capacity, the molten metal that comes into contact with them is not rapidly cooled, and the high-temperature molten metal remains around both thin-walled portions 13.14. Therefore, both thin-walled portions 13.14 are completely melted by contact with the high-temperature molten metal, and the molten metal and both thin-walled portions 13.1 are completely melted.
The fusion and integration of 4 will be promoted.

■ Cool and solidify the molten metal. At this point, the casting material and both thin-walled portions 13, 14 are sufficiently fused into a single body, so that the casting material and the liner 5 are completely joined at this portion. Furthermore, the upper end protrusion 11 and the lower end protrusion 12 prevent the liner 5 from shifting.

■Remove the mother mold 1, water jacket core 2, and bore core 3 to obtain a cylinder block B as shown in FIG. This cylinder block B has a thin wall portion 13 before pouring.
．． 14 (see FIG. 1), the liner portion 9 and the main body portion 7 are completely joined, so that the water jacket 8 is completely sealed and no cooling water leaks.

Note that since the cylinder block B is of the wet liner type, it goes without saying that the cooling efficiency is high.

<Second Embodiment> As shown in FIG. 2, in the second embodiment, the thickness of the liner 5 is made thinner at the upper end portion and the lower end portion, thereby forming the upper thin portion 17 and the lower thin portion 18. is forming. In this case, both thinned portions 17 , 18 project in the axial direction of the liner 5 within the cavity 4 . Even if you do this, the first
As in the embodiment, the casting material and both thin-walled portions 17 and 18 are completely joined, so that the sealing performance of the water jacket 8 (see FIG. 5) is improved. Note that in the second embodiment,
Since the liner 5 does not come into contact with the molten metal in the area between the two thin-walled parts 17 and 18 (the area in contact with the water jacket core 2), the liner 5 is made thicker than a normal liner. This increases the strength of the piston and suppresses the vibration of the cylinder block caused by the reciprocating movement of the piston.

Third Embodiment> As shown in FIG. 3, in the third embodiment, the upper thin part 21
and the lower thin wall portion 22 have the same structure as in the second embodiment, and similarly to the second embodiment, the cast material and both thin wall portions 2
1.22 is completely joined and the water jacket 8 (
(see Fig. 5). however,
The thickness of the portion of the liner 5 between the two thin-walled portions 21 and 22 (the portion in contact with the water jacket core 2) is not particularly thick. Therefore, a vibration suppressing bulge 23 is provided on the outer peripheral surface of the liner 5 to suppress vibration. The vibration suppressing bulge 23 is formed in a ring shape along the outer periphery of the liner 5. In order to enhance the vibration damping effect, the vibration damping bulges 23 are formed on both thin walled portions 21 of the liner 5.
．． 22 (the contact portion with the water jacket core 2), it is formed at a position that is I/3 downward from the upper end.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view of a cylinder block casting mold, showing a first embodiment of the present invention. FIG. 2 is an explanatory longitudinal cross-sectional view of a cylinder block casting mold, showing a second embodiment of the present invention. FIG. 3 is an explanatory longitudinal cross-sectional view of a cylinder block casting mold showing a third embodiment of the present invention. FIG. 4 is an explanatory longitudinal cross-sectional view of a conventional cylinder block casting mold, and is basically common to the first to third embodiments. FIG. 5 is an explanatory longitudinal cross-sectional view of a cylinder block cast using the mold shown in FIG. 4. B...Cylinder block, DC...Mold, l...
Matrix, 2...Water jacket core, 3...Bore core, 4...Cavity, 5...Liner, 7...
Main body part, 8... Water jacket, 9... Liner part, 11... Upper end protruding part, 12... Lower end protruding part, 1
3, 17.21...Top thin interior, 14.18 22...Lower thin part. Figure 1

Claims (2)

[Claims] (1) In a wet liner type cast iron cylinder block in which a separately formed liner is cast in cast iron, the upper end and lower end are respectively injected into the mold cavity during casting. 1. A cast iron cylinder block characterized in that a liner having a thin wall portion exposed to the outside is formed by casting cast iron with a water jacket core attached between both thin wall portions. (2) In a method for manufacturing a cast iron cylinder block in which a wet liner type cylinder block is cast by casting a separately formed liner with cast iron, the upper and lower ends of the liner are A cylinder block is cast by providing a thin-walled part around each circumference, attaching a water jacket core to the liner between the thin-walled parts, and then pouring molten cast iron into the cavity of the mold. A method of manufacturing a cast iron cylinder block.