JP2016176364A - Casting method of cylinder block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for casting a cylinder block which is properly improved in rigidity by a journal piece, suppresses the leakage of oil to the outside, and is excellent in durability.SOLUTION: A light-alloy pressing member 20 which is arranged at a cavity face 42 of a cope 41 is made to abut on a journal piece 10 which is positioned by a journal piece support part formed at a cavity face 32 of a drag 31, the journal piece 10 is thus held, light-alloy metal molten metal is poured into a cavity 45, and a cylinder block is cast. The pressing member 20 is melted by the molten metal, and integrated with a raw material, the journal piece 10 is insert-cast, an interface between the journal piece 10 and the raw material is surely blocked from the outside of the cylinder block, and rigidity is properly improved by the journal piece 10.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a method for casting a cylinder block, and more particularly to a method for casting a cylinder block in which a journal piece is cast in a journal portion.

  2. Description of the Related Art Conventionally, for example, in a vehicle engine, a light alloy cylinder block such as an aluminum alloy has been widely used to reduce weight.

  A cylinder block made of such an aluminum alloy has a journal portion that supports the crankshaft, and a journal piece of iron-based material is cast into the journal portion for the purpose of improving the strength.

  When casting such a cylinder block, since the journal piece is covered with the base material of the aluminum-based alloy, the journal piece cannot be directly fixed to the casting mold. A method of casting by fixing to a child using a pin, a wire or the like is widely known.

  Further, for example, as disclosed in Patent Document 1, there is a method of casting an aluminum alloy cylinder block by inserting and fixing one end of a journal piece into a hole formed in a casting mold.

  Further, as disclosed in Patent Document 2, in a casting apparatus for casting a journal piece in which an oil hole and a bolt hole are formed in a journal portion of a cylinder block, a cast pin provided in a fixed mold and a positioning pin There is a method in which a pin is inserted into an oil hole and a bolt hole of a journal piece and the journal piece is fixed in a casting mold for casting.

  Further, in Patent Document 3, a holding pin is provided on the fixed die, a guide pin is fixed on the movable die, and the journal piece is held in the cavity by fitting the holding pin and the guide pin into the bolt hole of the journal piece. A method for casting the lower case for casting is disclosed.

Japanese Patent Laid-Open No. 11-210751 Japanese Utility Model Publication No. 2-93059 JP-A-11-336740

  However, when the journal piece is fixed to the core with a pin or wire as in Patent Document 1, there is a concern that the journal piece may be displaced during casting. When the journal piece is displaced, the desired strength by the journal piece cannot be obtained, the journal bearing surface becomes a distorted cylinder, and the coefficient of friction with the rotating crankshaft increases. Due to this increase in the coefficient of friction, wear of the crankshaft, journal, etc. becomes severe, resulting in a decrease in fuel consumption, performance, durability, etc. of the engine, and further causes vibration and noise.

  Moreover, according to the method of casting by fixing one end of a journal piece to a casting mold as in Patent Document 1, the journal piece is fixed during casting, and the positional deviation of the journal piece is suppressed. However, the size of the journal piece is increased, and in the cylinder block after casting, the interface between the journal piece and the base material is exposed on the outer surface of the cylinder block, so that, for example, via a bolt hole formed in the journal part. Therefore, there is a concern that the oil that has entered the fine gap between the journal piece and the base material from the bearing portion oozes out to contaminate the outer surface and the periphery of the cylinder block and increase the oil consumption. In addition, air or moisture permeates into the interface between the journal piece and the base material from the outside, the strength of the journal piece decreases due to a decrease in the joint strength of the portion, and the crankshaft rotating as the journal portion deforms. The friction coefficient is increased, the crankshaft and the journal are heavily worn, and the fuel consumption, performance, durability, etc. of the engine are lowered, and vibration and noise are generated.

  According to Patent Document 2, according to a method in which an oil hole or a bolt hole formed in a journal piece is inserted into a casting pin and a positioning pin of a mold and the journal piece is fixed and cast, There is a concern about misalignment of the journal piece such as the journal piece rising due to the molten metal introduced.

  As in Patent Document 3, when a journal pin is fixed to a fixed mold by a pressing pin and a movable guide pin, a through hole that communicates the interface between the journal piece and the base material to the outside by the pressing pin or the like in the lower case after casting As in Patent Document 1, oil that has entered the fine gap between the outer peripheral surface of the journal piece and the base material from the bearing portion side through the bolt hole oozes out to increase the oil consumption. On the other hand, there is a concern that air or moisture may permeate into the interface between the outer peripheral surface of the journal piece and the base material from the outside, and the bonding strength of the portion is reduced, so that the desired strength by the journal piece cannot be obtained.

  Accordingly, an object of the present invention made in view of such a point is to provide a method of casting a cylinder block which is suitable for improving strength with a journal piece and has excellent durability without leakage of oil to the outside.

  The method for casting a cylinder block according to claim 1, which achieves the above object, includes positioning and supporting a journal piece within a cavity surface formed with a journal portion shaping portion for shaping the journal portion shape of the cylinder block and the cavity. Using a casting mold having a lower mold having a journal piece support portion and an upper mold having a cavity surface that shapes the outer surface shape of the cylinder block, the journal piece of iron-based material is cast in the journal portion. In the method of casting a cylinder block made of light alloy, the journal piece is held by abutting a pressing member made of light alloy mounted on the cavity surface of the upper mold against the journal piece positioned by the journal piece support portion. In this state, the cylinder block is cast by filling the cavity with hot molten metal alloy. Characterized in that it.

  According to this, the journal piece is fixed and cast into a desired position by a journal piece support portion formed on the lower mold and a light alloy pressing member mounted on the cavity surface of the upper mold. It melts with the light alloy molten metal and is integrated with the base material so that the journal piece is cast, and the interface between the journal piece and the base material is reliably cut off from the outer surface of the cylinder block.

  As a result, the journal piece is cast in the desired position, the desired strength is obtained by the journal piece, the journal part is held with high accuracy, the friction coefficient with the rotating crankshaft is reduced, and the oil Consumption is suppressed and wear of the crankshaft and journal is reduced, improving the fuel efficiency, performance and durability of the engine, and further suppressing vibration and noise generation.

  The interface between the outer peripheral surface of the journal piece and the base material does not communicate with the outer surface of the cylinder block, and oil enters the interface between the journal piece and the base material from the bearing side through the bolt hole formed in the journal part. Even if water enters, the oil does not ooze out from the interface between the journal piece and the base material, and it is avoided that the outer surface of the cylinder block is contaminated with oil and the oil consumption is suppressed. .

  According to a second aspect of the present invention, in the casting method of the cylinder block according to the first aspect, the upper surface of the cavity can be brought into contact with a journal piece that protrudes from the cavity surface and is positioned on the journal support portion. A pressing member mounting step for mounting a pressing member, a journal piece setting step for setting a journal piece on the journal piece support portion, and a mold in which the pressing member is brought into contact with the journal piece set on the journal piece support portion. A mold clamping process for clamping, a hot water supply process for filling the mold-clamped cavity with a light alloy molten metal, a solidifying process for solidifying the light alloy melt filled with the hot water while maintaining the mold clamping state, A mold opening process for separating the mold and the upper mold is provided.

  According to this, a pressing member is attached to the cavity surface of the upper mold, and the journal member set on the journal piece support portion is clamped to clamp the pressing member against the journal piece set on the journal piece support portion. The method of casting a cylinder block according to claim 1 can be executed by filling the lightly molten alloy with a light alloy into the cavity which is held in contact with the journal piece and is clamped.

  According to a third aspect of the present invention, in the cylinder block casting method according to the first or second aspect, the pressing member has a shaft shape including a base portion and a position holding portion integrally formed with the base portion. The cavity surface of the upper mold has a recessed pressing member mounting hole, and the pressing member is mounted in a state where the base portion is fitted into the pressing member mounting hole and the position holding portion protrudes from the cavity surface. Features.

  According to this, the pressing member can be easily mounted on the upper mold by inserting the base of the pressing member into the pressing member mounting hole in which the cavity surface of the upper mold is recessed.

  A fourth aspect of the present invention is the cylinder block casting method according to the third aspect, wherein the position holding portion is subjected to a surface area expansion process on the outer periphery.

  According to this, for example, by performing a surface area expansion treatment of the bolt-shaped unevenness on the position holding portion of the pressing member, an area in contact with the light alloy molten metal is ensured during casting, and the light alloy molten metal is easily and efficiently used. Dissolved.

  According to the present invention, the journal piece is fixed and cast at a desired position by the journal piece support portion formed in the lower mold and the light alloy pressing member mounted on the cavity surface of the upper mold, and the pressing member Is melted by the light alloy melt and integrated with the base material, the journal piece is cast, the interface between the journal piece and the base material is reliably shielded from the outside of the cylinder block, and oil does not leak to the outside, Furthermore, an appropriate strength improvement by the journal piece can be obtained, and a cylinder block having excellent durability can be obtained.

It is a whole perspective view which shows the outline | summary of the cylinder of an engine. It is a perspective view which shows the outline | summary of the cylinder block on the right side. It is explanatory drawing of a journal part, (a) is the III arrow directional view which shows the principal part of FIG. 2, (b) is a bb sectional view taken on the line (a). It is explanatory drawing of a journal piece, (a) is a perspective view, (b) is b of (a). It is a schematic explanatory drawing of a casting mold, (a) is principal part sectional drawing of a casting mold, (b) is the bb sectional view taken on the line of (a). It is a casting process diagram It is a casting process explanatory drawing, (a) is principal part sectional drawing of a casting mold, (b) is the bb sectional view taken on the line of (a). It is a casting process explanatory drawing, (a) is principal part sectional drawing of a casting mold, (b) is the bb sectional view taken on the line of (a). It is a casting process explanatory drawing, (a) is principal part sectional drawing of a casting mold, (b) is the bb sectional view taken on the line of (a). It is a casting process explanatory drawing, (a) is principal part sectional drawing of a casting mold, (b) is the bb sectional view taken on the line of (a). It is a casting process explanatory drawing, (a) is principal part sectional drawing of a casting mold, (b) is the bb sectional view taken on the line of (a).

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 11 by taking a cylinder block of a horizontally opposed engine as an example.

  1 is an overall perspective view showing an outline of a cylinder block of an engine, FIG. 2 is a perspective view of a right cylinder block, FIG. 3A is a view taken along an arrow III in FIG. 2, and shows a main part of FIG. It is a bb line sectional view of).

  Reference numeral 1 denotes a cylinder block of a horizontally opposed engine. The cylinder block 1 has a structure that can be divided into left and right with a central axis L of the crankshaft 5 as a center, and is integrally coupled by a plurality of coupling bolts (not shown). Is done.

  The left and right cylinder blocks 1A and 1B are separately cast and formed of a light metal such as an aluminum alloy, in this embodiment, an aluminum alloy, and the right and left cylinder blocks 1A and 1B include the right cylinder shown in FIG. As shown in the block 1B, a plurality of journal portions 2 having a bearing surface 4 which is a concave surface formed in a semicircular arc shape at the center portion of the flat contact surface 3 are formed.

  The crankshaft 5 is pivotally supported via a bearing metal 6 on a semicircular bearing surface 3 of each journal portion 2 facing the left and right cylinder blocks 1A, 1B. The crankshaft 5 is formed of an iron-based material, and rotates when the reciprocating motion of the piston due to combustion of the air-fuel mixture in the cylinder is transmitted through the connecting rod. During the rotation, the journal portion 2 has a large impact. A constant load is always received, and thermal expansion occurs due to heat propagation due to combustion of the air-fuel mixture.

  Journal pieces 10 made of an iron-based material, for example, an iron-based powder sintered body, are mainly casted in the journal portions 2 of the left and right cylinder blocks 1A and 1B mainly for the purpose of improving the strength.

  The journal piece 10 has a semicircular arc shape or a U-shape extending along the central axis direction as shown in a perspective view in FIG. A flange body 15 having a piece main body 11 having an inner peripheral surface 12 and an outer peripheral surface 13 and a pair of side surfaces 14 facing each other is formed integrally with both ends of the piece main body 11. Bolt holes 16 are formed in the holes.

  The inner peripheral surface 12 of the piece body 11 is a substantially semicircular arc-shaped first inner peripheral surface 12a extending in the direction of the central axis, and a planar second formed continuously at one end of the first inner peripheral surface 12a. A fourth inner surface 12b, a third inner peripheral surface 12c continuous with the other of the first inner peripheral surface 12a, and a second inner surface 12b continuous with the other end of the second inner peripheral surface 12b and the third inner peripheral surface 12c. It has an inner peripheral surface 12d and a fifth inner peripheral surface 12e.

  On the other hand, a convex portion 13 a having a pair of flat top surfaces 13 b extending in the radial direction is formed at the central portion of the outer peripheral surface 13. Further, a set pin hole 18 penetrating between the second inner peripheral surface 12b and the outer peripheral surface 13 is formed. These bolt holes 16 and set pin holes 18 are formed in parallel.

  The left cylinder block 1A and the right cylinder block 1B are substantially symmetric, and the right cylinder block 1B will be described below, and the description of the left cylinder block 1A will be omitted.

  The die casting machine for casting the cylinder block 1B includes a casting mold 30 including a lower mold 31 and an upper mold 41. The main part of the casting mold 30 will be described with reference to FIG.

  Fig.5 (a) is principal part sectional drawing of the casting mold 30 in a mold open state, (b) is the bb sectional view taken on the line of (a).

  The shape of the bearing surface shaping portion 35 projecting into the cavity 45 and the shape of the contact surface 3 is shaped on the cavity surface 32 of the lower die 31 in a semicircular cross section that shapes the shape of the bearing surface 4 of the journal portion 2. A journal portion shaping portion 33 having a pair of contact surface shaping portions 34 is provided.

  Each contact surface shaping portion 34 is provided with a bolt hole pin 36 that can be inserted into the bolt hole 16 formed in the flange portion 15 of the journal piece 10 and that forms a bolt hole in the journal portion 2. A stepped flange for abutting the lower surface 15a of the flange portion 15 near the base portion of the bolt hole pin 36 from the side of the journal shaping portion 33 to secure a gap between the journal portion 15 and the contact surface shaping portion 35. A part contact part 36a is formed.

  In the bearing surface shaping portion 35, the tip end portion 37 a can be fitted into the set pin hole 18 formed in the piece main body 11 of the journal piece 10, and is in contact with the second inner peripheral surface 12 b from the journal shaping portion 33 side. A columnar journal piece set pin 37 having a stepped piece contact portion 37b for determining the set position of the journal piece 10 is erected.

  The bolt hole pins 36 and the journal piece set pins 37 contact the journal piece 10 to constitute a journal piece support portion that positions and supports the journal piece 10 at an intended position.

  On the other hand, the upper die 41 is formed with a cavity surface 42 for shaping the outer surface shape of the cylinder block 1B. The cavity surface 42 is formed with a bottomed cylindrical pressing member mounting hole 43 extending in the mold opening direction A so as to face each top surface 13 b of the journal piece 10 set in the lower mold 30. The pressing member 20 is mounted in the pressing member mounting hole 43 in advance before the journal piece 10 is cast.

  The holding member 20 is made of an aluminum-based alloy that is the same kind of light metal as the cylinder blocks 1A and 1B. It is formed in a shaft-like body having a position holding portion 20 b protruding from the hole 43. As will be described later, the position holding portion 20b is installed in such a length that the top end 20c can abut on each top surface 13b of the journal piece 10 in a state where the journal piece 10 is set on the lower die 31 and closed. Further, the outer periphery of the position holding portion 20b is subjected to a surface area expansion process that is formed into a bolt shape or a plurality of concave and convex surfaces such as a ring shape.

  A process of casting the cylinder block 1B using the casting mold configured as described above will be described with reference to a process chart shown in FIG.

  In casting the cylinder block 1A, FIG. 5 (a) shows a cross-sectional view of the main part in the mold open state in advance, and (b) shows a cross-sectional view taken along the line bb of (a). The base 20a is inserted into each formed pressing member mounting hole 43, and the positioning member 20 is mounted on the upper die 41 (pressing member mounting step S1).

  Next, as shown in FIG. 7, each bolt hole 16 and set of the journal piece 10 from above is set on each bolt hole pin 36 and journal piece set pin 37 erected on the journal portion shaping portion 33 of the lower mold 31. The pin hole 18 is fitted and the journal piece 10 is set in the lower mold 31 (journal piece setting step S2).

  In the journal piece 10 set on the lower die 31, the lower surface 1 a of each flange portion 15 abuts on the flange portion abutting portion 36 a of the bolt hole pin 38, and the second inner peripheral surface 12 b is on the journal piece set pin 37. The flange portion 15 and the inner peripheral surface 12 of the journal piece 10 and the cavity surface 32, that is, the contact surface shaping portion 34 and the bearing surface shaping portion 35 are positioned in the desired position by contacting the piece contact portion 37b. The desired state of separation distance is maintained.

  Next, as shown in FIG. 8, the upper mold 41 is moved closer to the lower mold 31 on which the journal piece 10 is set, and the lower mold 31 and the upper mold 41 are combined to perform mold clamping (mold clamping process). S3).

  In the clamped state where the lower mold 31 and the upper mold 41 are combined and closed, the top ends 20c of the pressing members 20 provided on the cavity surface 42 of the upper mold 41 are the top surfaces of the convex portions 13a of the journal piece 10. 13b, the journal piece 10 is clamped by the bolt hole pin 38 and the journal piece set pin 37 and the pressing member 20 provided on the cavity surface 42 of the upper die 41, and fixed at an intended position in the cavity 45. Retained. At this time, the position holding portion 20 b of the pressing member 20 is exposed in the cavity 45.

  Subsequently, as shown in FIG. 9, a casting mold 30 formed by cavity surfaces 32 and 42 of a lower mold 31 and an upper mold 41 in which a light metal molten metal, that is, an aluminum-based alloy molten metal M is clamped from a hot water supply port (not shown). Hot water is filled into the cavity 45 (hot water supply step S4).

  After the hot water filling, the molten aluminum alloy is solidified while maintaining the mold clamping state (solidification step S5). At this time, the journal piece 20 is securely held between the bolt hole pin 36 and the journal piece set pin 37 formed in the lower die 31 and the top end 20c of the pressing member 20 protruding from the cavity surface 42 of the upper die 41. Since it is fixed, it is cast in the desired position without causing a positional shift. On the other hand, the holding member 20, particularly the position holding portion 20 b exposed in the cavity 45, is melted and integrated by the molten aluminum alloy M filled with hot water in the cavity 45. At this time, a surface area expansion process in which the outer peripheral surface of the position holding portion 20b of the pressing member 20 is formed in a concavo-convex shape is performed so that a large contact area with the aluminum-based alloy molten metal M is easily formed by the molten aluminum-based alloy. And efficiently dissolved.

  10A and 10B, the inner peripheral surface 12 of the journal piece 10, the lower surface 15a of the flange portion 15 and the lower mold 31 The molten aluminum-based alloy also flows between the bearing surface shaping portion 35 and the contact surface shaping portion 34, and the inner peripheral surface 12 of the journal piece 10 is covered with the aluminum alloy with the desired thickness. 10 outer peripheral surfaces 13 are covered with an aluminum-based alloy including the holding member 20 dissolved.

  After the molten aluminum alloy injected into the cavity 45 of the casting mold 30 is solidified, the upper mold 41 is moved to the mold opening position indicated by the imaginary line 41a in FIG. 10 to separate the lower mold 31 and the upper mold 41 from each other. Mold opening is performed (mold opening process S6).

  The cylinder block 101 cast in the cavity 45 from the opened mold 30 is grasped and taken out by a robot or the like (product take-out step S7).

  A mold release agent is spray applied to the cavity surfaces 32 and 42 of the lower mold 31 and the upper mold 41 that have been opened (release agent application step S8). From the pressing member mounting step S1 for mounting the pressing member 20 to the casting mold 30 From the journal piece setting step S1 for setting the journal pin 10 to the casting mold 30, the release agent applying step for applying the release agent to the cavity surfaces 32 and 42 The cylinder block is sequentially cast by repeating the steps up to S8.

  The cylinder block 1 </ b> B manufactured in this way is held by a bolt hole pin 36 in which the journal piece 20 is formed in the lower die 31, a journal piece set pin 37, and a pressing member 20 attached to the cavity surface 42 of the upper die 41. With the aluminum alloy melt M being fixed and held at the desired position, the molten aluminum alloy M is fed into the cavity 45 and cast, and the holding member 20 is melted by the aluminum alloy melt and integrated with the base material to form a journal piece. By casting 10, the journal piece 10, the base material, and the interface are reliably cut off from the outer surface of the cylinder block 1 </ b> B.

  As a result, the journal piece 10 is cast into a desired position, the desired balanced strength of the journal part 2 by the journal piece 10 is obtained, and the bearing surface 4 of the journal part 2 is held in a cylindrical shape with high accuracy. Thus, the friction coefficient with the rotating crankshaft 5 is reduced, the oil consumption is suppressed, and the wear of the crankshaft 5 and the journal portion 2 is reduced, so that the fuel consumption, performance, durability, etc. of the engine are reduced. The vibration and noise generation are further suppressed.

  Further, the interface between the journal piece 10 and the base material does not communicate with the outer surface of the cylinder block 1A, and oil is introduced from the bearing portion side to the interface between the journal piece 10 and the base material through a bolt hole formed in the journal portion. Even if the water enters, the oil does not ooze out from the interface between the journal piece 10 and the base material, the outer surface of the cylinder block 1A is prevented from being contaminated with oil, and the oil consumption is suppressed. The Further, air and moisture do not permeate into the interface between the journal piece 10 and the base material from the outside, and a decrease in the bonding strength of the portion is suppressed.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the meaning of invention. For example, in the above embodiment, the journal piece 10 is fixed to the lower mold 31 by the bolt hole pin 36 and the journal set pin 37, but the journal piece is supported by other means such as forming a protrusion on the cavity surface 32 of the lower mold 31. The journal piece 10 can also be held by the section.

  In the above embodiment, the pressing member mounting hole 43 is formed opposite to the top surface 13b of the convex portion 13a formed on the outer peripheral surface 13 of the journal piece 10. However, as shown in FIG. When the upper mold 41 is a casting mold in which the width direction of the journal piece 10 is the mold opening direction A, the cavity that the holding member mounting hole 43 is on the side of the convex portion 13b of the journal piece 10 set in the journal support portion It is formed in a bottomed cylindrical shape extending in the mold opening direction A at the position of the surface 43. The presser member 20 is inserted or press-fitted into the presser member mounting hole 43 and the presser member 20 extends in the mold opening direction A so that the outer periphery of the journal piece abutting portion 20b is closed with the journal piece 10 set on the lower die 31. It installs so that it can contact | abut to each top surface 13b of the journal piece 10. FIG.

  The casting by the casting mold is different from the above embodiment in the mold opening direction A, but the casting process and the effect of the cast cylinder block are substantially the same as the above embodiment. These descriptions are omitted.

DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Journal part 10 Journal piece 11 Piece main body 20 Holding member 20a Base 20b Position holding part 30 Casting die 31 Lower mold 32 Cavity surface 33 Journal part shaping part 34 Contact surface shaping part 35 Bearing surface shaping part 36 Bolt hole pin (journal piece support)
37 Journal piece set pin (journal piece support)
41 Upper mold 42 Cavity surface 43 Holding member mounting hole 45 Cavity

Claims (4)

The cavity surface on which the journal part shaping part for shaping the journal part shape of the cylinder block is formed, the lower mold having the journal piece support part for positioning and supporting the journal piece in the cavity, and the outer surface shape of the cylinder block are shaped. In a method of casting a light alloy made syrup darlock in which a journal piece of a ferrous material is cast in a journal portion using a casting mold having an upper mold with a cavity surface to be shaped,
A light alloy pressing member mounted on the cavity surface of the upper mold is brought into contact with the journal piece positioned by the journal piece supporting portion to hold the journal piece, and in this state, the light alloy is held in the cavity. A cylinder block casting method comprising casting a cylinder block by filling molten metal with hot water. A pressing member mounting step of mounting a pressing member that can contact a journal piece that protrudes from the cavity surface and is positioned on the journal support portion on the cavity surface of the upper mold,
A journal piece setting step for setting a journal piece on the journal piece support,
A mold clamping step in which the pressing member is brought into contact with a journal piece set in the journal piece support portion and clamped;
A hot water supply step of filling the mold-clamped cavity with hot melt of light alloy,
A solidification step of solidifying the molten metal filled with the hot water supply while maintaining the clamping state;
The cylinder block casting method according to claim 1, further comprising a mold opening step for separating the lower mold and the upper mold. The pressing member has a shaft shape including a base portion and a position holding portion integrally formed with the base portion,
The cavity surface of the upper mold has a recessed pressing member mounting hole,
The cylinder block casting method according to claim 1 or 2, wherein the pressing member is mounted in a state in which the base portion is fitted into the pressing member mounting hole and the position holding portion protrudes from the cavity surface.   4. The cylinder block casting method according to claim 3, wherein the position holding portion is subjected to a surface area expansion process on an outer periphery.

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