JPH0140709B2 - - Google Patents

Description

[Detailed description of the invention] A. Object of the invention (1) Industrial application field The present invention relates to a Siamese cylinder block material, particularly a Siamese cylinder barrel formed by connecting a plurality of cylinder barrels arranged in series; an outer wall of a cylinder block surrounding the barrel; a water jacket provided between the Siamese cylinder barrel and the outer wall of the cylinder block so that the entire circumference of the Siamese cylinder barrel faces; an outer wall of the cylinder block on the bottom side of the water jacket; The present invention relates to a method for casting an item including a crankcase connected to the crankcase; and a plurality of bearing holders protruding from the inner peripheral surface of the crankcase to support a crankshaft.

(2) Prior Art Conventionally, the cylinder block material has been cast by installing a sand core for a water jacket in the cavity of a mold.

(3) Problems to be Solved by the Invention However, in the bearing holder made of the above-mentioned material, since there is a thick wall part directly under the water jacket, the amount of molten metal in the thick wall part of the cavity during casting is large.
In addition, sand cores for water jackets, which have good heat retention properties, are located near the area where the thick wall is formed, which slows down the solidification rate of the molten metal and causes casting defects such as cavities and pitting in the thick wall. There's a problem.

In view of the above, the present invention forms a lightening recess at the time of casting in the thick wall part to eliminate places where casting defects occur,
Another object of the present invention is to provide the above-mentioned casting method, which makes it possible to obtain the above-mentioned material in which the metal structure in the vicinity of the lightening recess is made dense to ensure strength.

B. Structure of the Invention (1) Means for Solving Problems The present invention provides a sand core for a water jacket in the mold cavity, and a hollowed-out recess that is inserted into each bearing holder and extends directly below the water jacket. It is characterized by installing a core for the hollowed out recess which also serves as a chiller for forming the mold.

(2) Effect When the core for the hollowed-out recess, which also serves as a cooling metal, is placed in the cavity of the mold as described above, the areas where casting defects occur are eliminated by forming the hollowed-out recess, and at the same time, the surrounding areas of the hollowed-out recess are The metal structure can be made dense by rapidly solidifying the molten metal.

(3) Embodiment FIGS. 1 to 3 show a Siamese type cylinder block S, which consists of an aluminum alloy cylinder block body 2 and a cast iron sleeve 3 cast into the body 2. The cylinder block main body 2 includes a Siamese cylinder barrel 1 formed by connecting a plurality of cylinder barrels 11 to 14 in series, four cylinder barrels ₁₁ to ₁₄ in the illustrated example, and a cylinder block outer wall 4 surrounding the Siamese cylinder barrel 1.
and a crankcase 5 connected to the lower edge of the outer wall 4, and each cylinder barrel 1 ₁ to 1 ₄
The sleeves 3 are cast into each sleeve 3, and each sleeve 3 forms a cylinder bore 3a.

A water jacket 6 facing the entire circumference of the Siamese cylinder barrel 1 is formed between the Siamese cylinder barrel 1 and the cylinder block outer wall 4, and the crankcase 5 is attached to the bottom side of the water jacket 6.
will be placed. At the opening on the cylinder head side of the water jacket 6, the Siamese cylinder barrel 1 and the cylinder block outer wall 4 are connected by a plurality of reinforcing deck parts 8, and the adjacent reinforcing deck parts 8 are connected to each other through a communication port to the cylinder head side. Functions as 7. As a result, the cylinder block S is constructed into a closed deck type.

On the inner peripheral surface of the crankcase 5, both ends of the case 5 and the adjacent cylinder barrels 1 ₁ ,
A bearing holder 21 for supporting a crank journal is provided protrudingly between 1 ₂ , 1 ₂ , 1 ₃ and 1 ₃ , 1 ₄ .
Further, as clearly shown in FIGS. 1 and 2B, three bearing holders 21 excluding the bearing holders 21 at both ends are provided with a hollowed-out recess Co extending from the outer surface of the crankcase 5 to just below the water jacket 6. r is the recess
These are reinforcing ribs provided on both sides of Co.

5 to 9 show a casting device for the cylinder block material Sm shown in FIG. 4, and the device is equipped with a mold M as a casting mold. The first and second side molds 1 are disposed below the mold 9 and are divided into left and right halves in FIGS. 5 and 6.
0 ₁ , 10 ₂ and a lower mold 11 on which both side molds 10 ₁ , 10 ₂ are slidably placed.

A Siamese cylinder barrel 1 is attached to the lower surface of the upper mold 9 in cooperation with the upper portions of the opposing surfaces of both molds 10 ₁ and 10 ₂ .
and a mold clamping recess 12 defining a first cavity C1 for molding the cylinder block outer wall ₄ .
is formed, and mold clamping convex portions 13 that fit into the concave portions 12 are provided protrudingly on the upper surfaces of both side molds 10 ₁ and 10 ₂ .

The lower mold 11 has a molding block 18 projecting upward, and the molding block 18 has two molds 10 ₁ , 1 on both sides.
A second cavity C ₂ is defined for forming the crankcase 5 and each bearing holder 21 in cooperation with the lower part of the opposing surface of C 0 ₂ . The upper end of the cavity _C2 communicates with the first cavity _C1 .

The molding block 18 includes four tall semi-cylindrical first molding parts ₁₈₁ formed at predetermined intervals;
Between adjacent first molded parts 18 ₁ and both outermost first molded parts 18 1
It consists of a convex second molded part 182 located on the outside of the molded part ₁₈₁ , and each first molded part ₁₈₁ has a rotation _space 20 for the crankcase 5, crank pin, and crank arm (FIGS. 2 and 3). The second molding section ₁₈₂ is used to mold the crank journal bearing holder 21 (FIGS. 2 and 3).

Cores _10a and 10b for hollowed out recesses that can be positioned above each second molded portion ₁₈₂ are protruded from the lower portions of the opposing surfaces of both side walls ₁₀₁ and 102, and these cores 10a,
10b also functions as a chiller.

As shown in FIGS. 7 and 8, the lower mold 11 includes a sump 14 that receives molten metal made of aluminum alloy from a melting furnace (not shown), and a hot water supply cylinder 15 that communicates with the sump 14. The hot water cylinder 15
The plunger 16 is slidably connected to the plunger 16, and the second cavity _C2 is branched into two parts from the sump 14 in the longitudinal direction.
In addition, a pair of runners 17 are provided that extend over approximately the same length. Both lower ends of the second cavity C ₂ communicate with both runners 17 via a plurality of weirs 19 . Each weir 19 is provided corresponding to each second forming part 18 ₂ , and is designed to quickly fill the large volume portion of the second cavity C ₂ with molten metal.

Both runners 17 are located at the runner tip 17a from the water reservoir 14 side.
The bottom surface of the runner 17 is formed in the shape of several steps ascending from the trough portion 14 side so that the cross-sectional area gradually decreases toward the bottom. Each rising portion 17c connected to each stage 17b is formed obliquely so that the molten metal can be smoothly guided to each weir 19.

As shown in FIG. 5, a positioning protrusion 22 that fits into the inner peripheral surface of the cast iron sleeve 3 is protruded from the top surface of each first molded part ₁₈₁ .
A recess 23 is formed at the center. Further, in the two first molded parts 18 ₁ located on both sides, through holes 24 are formed that pass through the first molded parts 18 ₁ on both sides of the positioning protrusion 22 , and a pair of temporary installation pins 25 are inserted into these through holes 24 . These temporary installation pins 25 are used for temporary installation of a sand core for a water jacket, which will be described later. Both temporary installation pins 2
The lower end of 5 is fixed to a mounting plate 26 disposed below the forming block 18. Two support rods 27 are inserted through the mounting plate 26, and a coil spring 28 is compressed between the lower part of each support rod 27 and the lower surface of the mounting plate 26. When opening the mold, attach the mounting plate 2
6 rises under the elastic force of each coil spring 28 until it comes into contact with the stopper 27a at the tip of each support rod 27, and as a result, the tip of each temporary installation pin 25 moves to the first position.
The molded portion 18 ₁ protrudes from the top surface. A recess 25a that engages with the lower edge of the sand core is formed on the tip end surface of each temporary installation pin 25.

Further, in the two first molded parts 18 ₁ located on both sides, a through hole 29 is formed that penetrates the first molded part 18 ₁ at a bisecting position between both through holes 24 , and the lower end is inserted into the through hole 29 . An operating pin 30 fixed to the mounting plate 26 is slid together. When the mold is opened, the tip of the actuating pin 30 protrudes into the recess 23, and when the mold is closed, it is pushed down by a collect mechanism, which will be described later.
8 ₁ It is designed to be pulled in from the top surface.

Two core holders 31 are provided at the upper portions of the opposing surfaces of the first and second side molds 10 ₁ and 10 ₂ for actually installing the sand cores. Each core holder 31 includes an engagement hole 31a for positioning the sand core, and a clamping surface 31b formed on the outer periphery of the opening to clamp the sand core.

In the mold clamping recess 12 of the upper mold 9, there are a plurality of third cavities C3 for communicating with the first cavity _{C1 and} for overflowing the molten metal, and a plurality of fourth cavities _C4 for forming the communication port 7, respectively. The upper mold 9 has through holes 32, 3 communicating with each third cavity _C3 and fourth cavity _C4 .
3 are formed respectively.

The through holes 32 and 33 have closing pins 34 and 3.
5 are inserted, respectively, and the closing pins 34, 3
The upper end of 5 is a mounting plate 36 disposed above the upper mold 9.
Fixed.

Small diameter portions 32a and 33a of each through hole 32 and 34 extend upward for a predetermined length from the communication end with respect to cavities C ₃ and C ₄ .
The diameter of the outer portion thereof is larger than the diameter of each closing pin 34, 35, thereby closing the third cavity _C3 and the fourth cavity _C4 . Each through hole 32, 3
Air passages 37, 38 are formed between the three.

A hydraulic cylinder 39 is interposed between the top surface of the upper die 9 and the mounting plate 36, and the operation of the hydraulic cylinder 39 moves the mounting plate 36 up and down to close each closing pin 34, 3.
5 to open and close each small diameter portion 32a, 33a. 40 is a guide rod for the mounting plate 36.

As clearly shown in FIG. 5, the upper die 9 is provided with a collect mechanism 41 for holding the sleeve 3 cast into each cylinder barrel 1 ₁ to 1 ₄ , and the mechanism 41 is constructed as follows. be done.

A through hole 42 whose center line coincides with the extension axis of the operating pin 30 is formed in the upper mold 9, and a support rod 43 is loosely inserted into the through hole 42. The upper end of the support rod 43 is fixed to a bracket 44 erected on the top surface of the upper die 9, and a molten metal intrusion prevention plate 45 is fixed to the lower end. A convex portion 45 a that can fit into the concave portion 23 on the top surface of the first molded portion 18 ₁ in the lower mold 11 is formed on the lower surface of the molten metal intrusion prevention plate 45 .

The hollow holding cylinder 46 has a circular outer peripheral surface and a tapered hole 47 with a downward slope from the top to the bottom. The holding cylinder 46 is inserted loosely, and its upper end abuts a protrusion 48 protruding from the recess 12 of the upper mold 9, and its lower end abuts a molten metal intrusion prevention plate 45. As shown in FIG.
A plurality of slot grooves 49 extending radially from the inner circumferential surface and outer circumferential surface of the circumferential wall are formed alternately and at equal intervals on the circumference.

A hollow actuating rod 50 for expanding the diameter of the holding tube 46 is slid onto the supporting rod 43 over substantially the entire length of the supporting rod 43, and the actuating rod 50 has a tapered shape that fits into the tapered hole 47 of the holding tube 46. Part 50
a, and a perfectly circular portion 50b that is connected to the tapered portion 50a, slides into the through hole 42 of the upper mold 9, and projects from the upper mold 9. A plurality of pins 57 are protruded from the tapered portion 50b, and these pins 57 are inserted into pin holes 58 that are long in the vertical direction of the holding tube 46, thereby allowing the rotation of the holding tube 46 while allowing the vertical movement of the tapered portion 50a. A stop is made.

A hydraulic cylinder 51 is fixed to the top surface of the upper mold 9, and hollow piston rods 53 ₁ and 53 ₂ projecting from the upper and lower end surfaces of the hollow piston 52 respectively touch the upper and lower end walls of the cylinder body 54. Penetrating. A true circular portion 50b of the actuating rod 50 is inserted into a through hole 55 passing through the hollow piston 52 and the hollow piston rod 53, and a stopper 56 ₁ to prevent removal is fitted into an annular groove of the circular portion 50b.
56 ₂ on the hollow piston rods 53 ₁ and 53 ₂ ,
The actuating rod 50 is raised and lowered by a hollow piston 52, which is brought into contact with the lower end surface. The collector mechanism 41 is a cylinder block S.
Four cylinders are provided corresponding to each cylinder barrel 1 ₁ to 1 ₄ .

10 and 11 show a cylindrical sand core 59 for a water jacket, and the sand core 59 has four cylinders corresponding to the four cylinder barrels ₁₁ to ₁₄ of the cylinder block S. A core body 61 comprising portions 60 ₁ to 60 ₄ and lacking peripheral walls overlapping each other, a communication port 7 for communicating the water jacket with the water jacket of the cylinder head, and a reinforcing deck portion 8. A plurality of protrusions 62 protruding from the upper end surface of the core body 61 to form a
The illustrated example is composed of baseboards 63 protruding from both outer surfaces of two cylindrical portions 60 ₂ and 60 ₃ located in the middle in the cylinder barrel arrangement direction. Each baseboard 63 has a large diameter portion 6 integrated with the core body 61.
3a, and a small diameter portion 63b protruding from the end surface thereof.

Next, the cylinder block material is made by the casting machine.
I will explain the casting work of Sm.

First, as shown in FIG. 5, the upper mold 9 is raised,
Furthermore, the molds 10 ₁ and 10 ₂ on both sides are moved apart from each other to open the molds. In the collect mechanism 41, each hydraulic cylinder 51 is actuated to lower the actuating rod 50 using the hollow piston 52, and the diameter of the holding cylinder 46 is reduced by moving the tapered portion 50a downward. In addition, the hydraulic cylinder 39 on the upper die 9 is operated to raise the mounting plate 36, thereby moving each closing pin 34, 35 to the third and fourth cavities _C3 ,
It is separated from the small diameter portions 32a and 33a communicating with _C4 . Furthermore, the plunger 1 inside the hot water cylinder 15
Lower 6.

A substantially perfect circular cast iron sleeve 3 is loosely fitted into each holding cylinder 46, and the upper end opening of the sleeve 3 is inserted into the convex portion 48 of the upper die 9.
The lower end surface of the sleeve 3 is fitted to the lower end surface of the convex portion 45a of the molten metal infiltration prevention plate 45, and the lower end opening of the sleeve 3 is closed by the molten metal infiltration prevention plate 45. Then, the hydraulic cylinder 51 of the collect mechanism 41 is operated, and the hollow piston 52 raises the operating rod 50. As a result, the tapered portion 50a moves upward, so that the holding tube 46 expands in diameter, and the sleeve 3 is reliably held in the holding tube 46 by receiving the diameter expanding force.

As shown in FIGS. 5 and 11, the lower edges of the cylindrical portions 60 ₁ and 60 ₄ on both sides of the sand core 59 are connected to temporary installation pins that protrude from the top surface of the first molding portions 18 ₁ on both sides of the lower mold 11. The sand core 59 is temporarily installed by engaging the recess 25a of the sand core 59.

The sand cores 59 are permanently installed by moving the double-sided molds 10 ₁ and 10 ₂ a predetermined distance in the direction in which they approach each other, and engaging each core receiver 31 with each baseboard 63. That is, the sand core 59 is positioned by fitting the small diameter portion 63b of each baseboard 63 in the sand core 59 into the engagement hole 31a of each core receiver 31, and also aligning the cylinder barrel arrangement direction of each large diameter portion 63a. Connect the terminals parallel to each core holder 31
The sand core 59 is held between the holding surfaces 31b by the sand cores 31b.

As shown by the dashed line in Figure 5 and also in Figures 6 and 7,
The upper mold 9 is lowered and each sleeve 3 is inserted into each cylindrical part 60 ₁ to 60 ₄ of the sand core 59, and the convex part 45a of the molten metal intrusion prevention plate 45 is inserted into the concave part 23 on the top surface of the first molded part ₁₈₁ . Fits in. As a result, the molten metal intrusion prevention plate 4
Since the operating pin 30 is pushed down by the convex portion 45a of No. 5, each temporary installation pin 24 is lowered and retracted from the top surface of the first molded portion ₁₈₁ . Also, the mold clamping recess 12 of the upper mold 9 is the mold clamping convex part 13 of the both molds 10 ₁ , 10 ₂ .
The mold is clamped by fitting into the mold.

Molten metal made of aluminum alloy is supplied from the melting furnace to the sump 14 of the lower mold 11, and the plunger 16 is raised to allow the molten metal to flow from both runners 17 through the weir 19 and from the lower ends of both sides of the second cavity _{C2 .} and fill the first cavity _C1 . Gas such as air in both cavities C ₁ and C ₂ is pushed up by the molten metal and escapes above the upper mold 9 through air passages 37 and 38 communicating with the third and fourth cavities C ₃ and C ₄ .

In this case, as described above, the cross-sectional area of the runner 17 gradually decreases toward the runner tip 17a, so in the large cross-sectional area, a large amount of molten metal is slowly filled into the second cavity C ₂ through the weir 19. In addition, in a part with a small cross-sectional area, a small amount of molten metal can be filled into the second cavity C ₂ through the weir 19 at a high speed, so that the molten metal is poured almost evenly from the lower ends of both sides over the entire length of the cavity C ₂ . The surface rises, and therefore the molten metal does not cause turbulence within the cavity _C2 , and gases such as air are prevented from being drawn into the molten metal, thereby avoiding the formation of cavities. Further, since the molten metal filling operation is performed efficiently, casting efficiency can be improved.

When the third and fourth cavities C ₃ and C ₄ are filled with molten metal, the hydraulic cylinder 39 on the upper mold 9 is operated to lower the mounting plate 36 and the closing pins 34 and 3
5 closes the small diameter portions 32a and 33a communicating with both cavities C ₃ and C ₄ .

In the pouring operation, the displacement of the plunger 16 and the pressure of the molten metal for filling the second cavity C ₂ and the first cavity C ₁ with molten metal are controlled as shown in FIG. 12.

That is, the plunger 16 changes its moving speed from the first to
The third speed is controlled in three stages, _V1 to _V3 . In this example, the first speed V ₁ is 0.08 to 0.12 m/sec, and the second speed V ₂ is
0.14 to 0.18 m/sec, and the third speed V ₃ is set to 0.04 to 0.08 m/sec to achieve a significant deceleration state. By controlling the speed in these three stages, the molten metal is prevented from rippling and air etc. Forms a quiet flow of molten metal without involving any gases, and directs the molten metal into both cavities.
C ₂ and C ₁ can be efficiently filled.

In addition, at the first speed V ₁ of the plunger 16, the molten metal only fills both runners 17, etc., so the pressure P ₁ of the molten metal is kept approximately constant, and at the second and third speeds V ₂ and V of the plunger 16. In ₃ , the molten metal is in both cavities C ₁ ,
Since C ₂ is filled with molten metal, the pressure P ₂ of the molten metal rises rapidly. After moving the plunger 16 at the third speed _V3 for a predetermined time, the molten metal filling pressure _P3 is increased to 150°C for about 1.5 seconds.
~400 Kg/cm ² , thereby completely covering the sand core 59 with the molten metal and forming a molten metal coagulation film on its surface.

After the above-mentioned time has elapsed, the plunger 16 is moved at a reduced speed _V4 , so the pressure _P4 of the molten metal rises, and when the pressure _P5 reaches 200 to 600 kg/ ^cm2 , the plunger 16 stops moving. solidify the molten metal.

As a result, each lightening recess Co is formed by the cores 10a, 10b, and at the same time, the cores 10a, 10b
As the molten metal in the vicinity of each lightening recess Co rapidly solidifies due to its action as a cooling metal, its metallographic structure becomes dense.

If a molten metal coagulation film is formed on the surface of the sand core 59 by keeping the pressure of the molten metal substantially constant for a predetermined period of time as described above, the sand core 59 will be protected by the film and damaged during the next pressurization of the molten metal. There is no.

In addition, since the sand core 59 is held in an accurate position by the molds 10 ₁ and 10 ₂ on both sides via its respective baseboards 63, when filling the first cavity C ₁ with molten metal, When the molten metal in ₁ is pressurized, the sand core 59 does not float or sag. Further, the end surface of the large diameter portion 63a of each baseboard 63 is the clamping surface 3 of the core receiver 31 in the double-sided types 10 ₁ and 10 _{2 .}
1b, so when the sand core 59 tends to swell, the deformation force is supported by each clamping surface 31b, thereby preventing the deformation of the sand core 59 and causing the rotation around each sleeve 3. A Siamese cylinder barrel 1 having a uniform wall thickness is obtained.

By controlling the moving speed of the plunger 16 and the pressure of the molten metal as described above, a closed deck cylinder block material can be cast with substantially the same production efficiency as die casting.

After the molten metal has completely solidified, the hydraulic cylinder 51 of the collect mechanism 41 is operated, the operating rod 50 is lowered to remove the diameter expansion force of the holding cylinder 46 against the sleeve 3, and the mold is opened, as shown in FIG. A cylinder block material Sm is obtained.

When the cylinder block material Sm is ground and the protrusions 64 formed by the cooperation of the fourth cavities _C4 and the protrusions 62 of the sand core 59 are removed, the communication ports 7 and the reinforcing deck parts 8 are removed. is formed, and by removing sand, a water jacket 6 is obtained.Furthermore, the inner peripheral surface of each sleeve 3 is machined into a perfect circle, and further other prescribed processing is performed to obtain the water jackets shown in Figs. 1 to 3. The cylinder block S shown is obtained.

Note that each lightening recess Co may be opened on the side surface of the bearing holder 21.

C. Effects of the Invention According to the present invention, since the core for the lightening recess, which also serves as a cooling metal, is provided in the cavity of the mold, it is possible to eliminate casting defects by forming the lightening recess. At the same time, it is possible to rapidly solidify the molten metal in the area surrounding the lightening recess, thereby making the metal structure denser, and ensuring the strength of the area surrounding the lightening recess.

[Brief explanation of drawings]

Figures 1 to 3 show a Siamese type cylinder block, with Figure 1 being a perspective view from above and Figure 2 being a perspective view from above.
The figure is a cross-sectional view taken along the line of Figure 1, Figure 2A is a cross-sectional view taken along the line a-a of Figure 2, and Figure 2B is a cross-sectional view taken along the line of Figure 2 b-b.
3 is a perspective view from below, FIG. 4 is a perspective view of the Siamese-type cylinder block material seen from above, and FIG. 5 is a vertical cross-section of the casting device used to carry out the present invention when the mold is opened. The front view corresponds to the sectional view taken along the line V-V in FIG. 7, and FIG. 8 is a sectional view taken along the lines of FIG. 7, FIG. 9 is a sectional view taken along the lines of FIG. 10 is a sectional view taken along the line XI-XI, and FIG. 12 is a graph showing the relationship between the displacement of the plunger with respect to time and the pressure of the molten metal with respect to time. C ₁ , C ₂ ... first and second cavities, Co ... lightening recess, M ... mold as mold, S ... cylinder block, Sm ... cylinder block material,
1...Siamese cylinder barrel, 1 ₁ to 1 ₄ ...
...Cylinder barrel, 5...Crankcase, 6...
... Water jacket, 10a, 10b ... Core for hollowed out recess, 21 ... Bearing holder, 59 ... Sand core for water jacket.

Claims (1)

[Claims] 1. A Siamese cylinder barrel formed by connecting a plurality of cylinder barrels arranged in series; A cylinder block outer wall surrounding the Siamese cylinder barrel; A circumference of the entire circumference of the Siamese cylinder barrel between the Siamese cylinder barrel and the cylinder block outer wall; a water jacket provided so as to face; a crankcase connected to the outer wall of the cylinder block at the bottom side of the water jacket; and a plurality of crankcases protruding from the inner circumferential surface of the crankcase to support the crankshaft. with a bearing holder;
When casting a Siamese-type cylinder block material with A method for casting a Siamese-type cylinder block material, characterized by installing a core for a hollowed-out recess that also serves as gold.