JPS6338259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of Industrial Application The present invention relates to a mold used for casting a cylinder block material for a multi-cylinder internal combustion engine.

(2) Prior Art Conventionally, as this type of mold, one in which a pair of runners are arranged along both lower edges parallel to the crankshaft of a cylinder block molding cavity is known.
In this case, the top and bottom surfaces of both runners are formed substantially horizontally from their upstream ends on the hot water supply section side to their downstream ends.

(3) Problems to be Solved by the Invention However, if the cross-sectional area of each runner is made to be the same over almost the entire length as described above, the timing of filling the molten metal between the hot water supply section side of the cavity and the opposite side thereof is different. Because of this difference, the molten metal causes turbulent flow within the cavity and entrains gases such as air, resulting in the formation of cavities in the material.

In view of the above, an object of the present invention is to provide a mold as described above, in which the rise of the molten metal level within the cavity is substantially uniform over the entire cavity, thereby preventing turbulence of the molten metal.

B. Structure of the Invention (1) Means for Solving Problems The present invention provides a cylinder block molding cavity, a pair of runners along both lower edges of the cavity that are substantially parallel to the crank axis, and both runners. It includes a plurality of weirs that communicate between the cavities and a hot water supply section that communicates with the upstream ends of both runners. The feature is that the top surface of the runner is formed approximately horizontally, and the cross-sectional area of both runners is gradually reduced.

(2) Effect When the cross-sectional area of the runner is gradually reduced as described above, a large amount of molten metal is filled into the cavity through the weir at a slow speed in the large cross-sectional area, and a small amount is filled in the small cross-sectional area. molten metal can be filled into the cavity through the weir at a high speed,
Inside the cavity, the molten metal level rises almost evenly over the entire length from both lower edges, so the molten metal does not cause turbulent flow within the cavity, and gases such as air are prevented from being drawn into the molten metal. It is possible to prevent the occurrence of nests.

(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, an outer wall portion 4 surrounding the Siamese cylinder barrel 1, and an outer wall. The sleeve 3 is connected to each cylinder barrel 1 ₁ to 1 ₄ .
Each sleeve 3 forms a cylinder bore 3a.

A water jacket 6 is formed between the Siamese cylinder barrel 1 and the outer wall portion 4, and the outer periphery of the Siamese cylinder barrel 1 is exposed to the water jacket 6. At the end of the water jacket 6 on the cylinder head side, the Siamese cylinder barrel 1 and the outer wall 4 are partially connected by a plurality of reinforcing deck parts 8, and the adjacent reinforcing deck parts 8 communicate with each other to the cylinder head side. It functions as a mouth 7. As a result, the cylinder block S is constructed into a closed deck type.

5 to 9 show an apparatus for casting the cylinder block material Sm shown in FIG. and the first and second side molds 10 ₁ , 10 ₂ which are divided into left and right halves in FIGS. Fourth side mold 10 ₃ , 10 ₄
and a lower mold 11 on which the side molds 10 ₁ to 10 ₄ are slidably placed.

A first cavity C ₁ is provided on the lower surface of the upper mold 9 for molding the Siamese cylinder barrel 1 and the outer wall portion 4 in cooperation with the upper half of each of the side molds 10 ₁ to 10 ₄ .
A mold clamping recess 12 is formed, and a mold clamping convex 13 that fits into the recess 12 is formed on each side of the mold 10.
₁ to 10 ₄ protrudingly provided on the upper surface.

As shown in FIGS. 7 and 8, the lower mold 11 is provided with a hot water supply section A, and the hot water supply section A includes a sump section 14 that receives molten metal made of aluminum alloy from a melting furnace (not shown), and It consists of a hot water supply cylinder 15 that communicates with the hot water reservoir 14 and a plunger 16 that is slidably engaged with the hot water supply cylinder 15. In addition, the lower mold 11 has a first cavity branched into two from the sump part 14.
A pair of runners 17 are formed that extend substantially parallel to the crank axis direction of _C1 . Further, the lower mold 11 has a molding block 18 projecting upward between the two runners 17.
The molding block 18 has molds 10 ₁ to 10 on each side.
A second cavity C ₂ for forming the crankcase 5 is defined in cooperation with the lower half of the crankcase 10 ₄ . The upper end of the cavity _C2 is connected to the first cavity _C1.
The two lower edges, which are substantially parallel to the crank axis, communicate with both runners 17 via a plurality of weirs 19. These first and second cavities C ₁ and C ₂ constitute a cylinder block molding cavity C.

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 molding part ₁₈₂ located outside the molding part 181, and each first molding part ₁₈₁ is for molding a rotation space 20 for a crank pin and a crank arm (FIGS. 2 and 3). The second molded part 18 ₂ is used for the bearing holder 2 of the crank journal.
1 (Figures 2 and 3). 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 1
The bottom surface 17b of 7 is formed in the shape of several ascending steps,
Moreover, the top surface 17c of both runners 17 is formed substantially horizontally. As a result, the cross-sectional area of both runners 17 gradually decreases from the hot water supply section A toward the runner tip 17a.
Each rising portion 17e connected to each step portion 17d is arranged corresponding to each weir 19, and is formed diagonally so that the molten metal can be smoothly guided to each weir 19.

When the cross-sectional area of the runner 17 is reduced stepwise in this way, a large amount of molten metal is filled into the second cavity _C2 through the weir 19 at a slow speed in the large cross-sectional area, and a small amount is filled in the small cross-sectional area. can be filled into the second cavity C ₂ through the weir 19 at a high speed, so that the cavity C ₂
Inside the cavity, the molten metal level rises almost evenly over the entire length from both lower edges, and therefore the molten metal rises in the cavity C ₂
This prevents gases such as air 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.

As shown in FIGS. 5 and 6, each first molding section 18 ₁
A positioning protrusion 22 that fits into the inner peripheral surface of the cast iron sleeve 3 is protruded from the top surface of the cast iron sleeve 3, and a recess 23 is formed in the center of the positioning protrusion 22. Furthermore, in the two first molded parts 18 ₁ located on both sides, through holes 24 are formed that penetrate through the first molded parts 18 ₁ on both sides of the positioning protrusion 22 .
4, a pair of temporary installation pins 25 are slid together, respectively.
These temporary installation pins 25 are used for temporary installation of a sand core for a water jacket, which will be described later. The lower ends of both temporary installation pins 25 are fixed to a mounting plate 26 disposed below the forming block 18. Its mounting plate 2
Two support rods 27 are inserted through the support rods 6, 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 the mold is opened, the mounting plate 26 receives the elastic force of each coil spring 28 and rises until it comes into contact with the stopper 27a at the tip of each support rod 27, so that the tip of each temporary installation pin 25 is attached to the first molded part 18 ₁ It protrudes from the top. 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 which 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 30 . An operating pin 30 fixed to the mounting plate 26 is slid together. When the mold is opened, the tip of the operating pin 29 protrudes into the recess 23, and when the mold is closed, it is pushed down by a diameter expanding mechanism, which will be described later, so that both temporary pins 25 are retracted from the top surface of the first molding section ₁₈₁ . It's summery.

The second in the first and second side molds 10 ₁ , 10 ₂
Two core holders 31 for permanently installing the left core are provided in the center of the wall defining the cavity _C2 . 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 thereof 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.

Both cavities C ₃ and C ₄ of each through hole 32 and 34
The small diameter portions 32a, 33a extend upwardly over a predetermined length from the communicating ends of the respective closing pins 34, 3.
5 to close the third cavity C ₃ and the fourth cavity C ₄ , the diameter of the outer portion thereof is larger than the diameter of each closing pin 34 , 35 , so that each closing pin 34 , 35 and each through hole 32,
Air passages 37 and 38 are formed between 33.

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.

The upper mold 9 has a diameter expanding mechanism 4 for holding the sleeve 3 cast into each cylinder barrel 1 ₁ to 1 _{4 .}
1 is provided, and its mechanism 41 is constructed as follows.

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 mold 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 surface abuts a protrusion 48 protruding from the recess 12 of the upper mold 9, and its lower end surface 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 50a that is connected to the tapered portion 50a, slides into the through hole 42 of the upper mold 9, and protrudes 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 die 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. Four diameter expanding mechanisms 41 are provided corresponding to each of the cylinder barrels ₁₁ to ₁₄ of the cylinder block S.

Figures 10 and 11 are sand cores 59 for water jackets.
The sand core 59 is the cylinder block S.
The core body 61 is provided with four cylindrical parts 60 ₁ to 60 ₄ corresponding to the four cylinder barrels 1 ₁ to 1 ₄ , and has a core body 61 lacking a circumferential wall that overlaps the adjacent ones, and A plurality of protrusions 62 protruding from the upper end surface of the core body 61 and a cylinder barrel arrangement of the core body 61 form a communication port 7 and a reinforcing deck portion 8 that communicate the jacket 6 with the water jacket of the cylinder head. 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. Each baseboard 63 has a large diameter portion 63a integrated with the core body 61,
It is formed with a small diameter portion 63b protruding from the end surface thereof. In this case, the protrusion 62 is connected to the fourth cavity.
Its dimensions are set so that it can be inserted loosely into _C4 .

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,
Also, opposing both sides 10 ₁ , 10 ₂ ; 10 ₃ , 1
0 ₄ are moved apart from each other to open the mold. In the diameter expanding mechanism 41, each hydraulic cylinder 51 is operated to lower the actuating rod 50 using the hollow piston 52, and the holding cylinder 46 is contracted in diameter by moving the tapered portion 50a downward. Also upper mold 9
The upper hydraulic cylinder 39 is actuated to raise the mounting plate 36, thereby opening the small diameter portion 3 that communicates each closing pin 34, 35 with the third and fourth cavities _C3 , _C4 .
It is separated from 2a and 33a. Further, the plunger 16 in the hot water supply cylinder 15 is lowered.

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 diameter expansion mechanism 41 is operated, and the hollow piston 52
to raise the actuating rod 50. As a result, the tapered portion 50a moves upward, so that the holding cylinder 46
expands in diameter, and the sleeve 3 receives the diameter expansion force and retains the holding cylinder 4.
6.

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. The end surface parallel to each core receiver 31
The sand core 59 is held between the holding surfaces 31b by the sand cores 31b. Further, the other double-sided molds 10 ₃ and 10 ₄ are also moved in the same manner.

As shown in FIG. 6, the upper mold 9 is lowered and each sleeve 3 is inserted into each cylindrical portion 60 ₁ to 60 ₄ of the sand core 59, and the convex portion 45a of the molten metal intrusion prevention plate 45 is first formed. Part 18 ₁ fits into the recess 23 on the top surface. As a result, the operating pins 30 are pushed down by the convex portions 45a of the molten metal intrusion prevention plate 45, so that each temporary installation pin 2
4 descends and retracts from the top surface of the first molded part ₁₈₁ .
Moreover, the mold clamping recess 12 of the upper mold 9 is connected to each side mold 10 ₁ to
The mold clamping is performed by fitting into the mold clamping convex portion 13 of 10 ₄ .

A 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 pass through the weir 19 from both runners 17 and into the cavity from both lower edges of the second cavity _C2 .
Fill C ₂ and the first cavity C ₁ . 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, both runners 17 are connected to the water reservoir 1 as described above.
Since the molten metal is formed so that the cross-sectional area gradually decreases from the runner 4 side toward the runner tip 17a, the molten metal flows from both runners 17 to each weir 19 as the plunger 16 rises.
Through this, the inside of the second cavity C ₂ can be smoothly pushed up from both lower edges of the second cavity C ₂ substantially evenly over the entire length thereof. Therefore, the molten metal does not cause turbulence in both cavities C ₁ and C ₂ .
It is possible to prevent gases such as air from being drawn into the molten metal, thereby avoiding the formation of cavities.

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
0.14~0.18m/sec, 3rd speed _V3 is set to 0.04~0.08m/sec to achieve a significant deceleration state, respectively.
This three-stage speed control prevents the molten metal from undulating and forms a quiet molten metal flow that does not involve gases such as air, and the molten metal is transferred to both cavities C ₂ ,
C ₁ can be filled efficiently.

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. 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 increases, and when the pressure _P5 reaches 200 to 600 kg/ ^cm2 , the plunger 16 stops moving and this solidify the molten metal.

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.

Also, the sand core 59 expands due to the molten metal, but since the protrusion 62 is loosely inserted into the fourth cavity _C4 , the protrusion 62 follows the expansion of the sand core 59, thereby preventing the protrusion 62 from breaking. Avoided.

Furthermore, since the sand core 59 is held in an accurate position by the molds 10 ₁ and 10 ₂ on both sides through its baseboards 63, the sand core 59 is held in an accurate position by the molds 10 1 and _{10 2} on both sides. When the molten metal in ₁ is pressurized, the sand core 59 does not float or sag. In addition, since the end surfaces of the large diameter portions 63a of each baseboard 63 abut against the clamping surfaces 31b of the core receivers 31 in the double-sided molds 10 ₁ and 10 ₂ , when the sand cores 59 tend to swell, The deformation force is supported by each clamping surface 31b, thereby preventing deformation of the sand core 59, and providing a Siamese cylinder barrel 1 with uniform wall thickness around each sleeve 3.

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 solidified, the hydraulic cylinder 51 of the diameter expansion 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. The cylinder block material Sm shown is obtained.

When the cylinder block material Sm is subjected to a grinding process to remove the protrusions 64 formed by the cooperation between the fourth cavities _C4 and the protrusions 62 of the sand core 59, the protrusions 62 form the communication ports 7. Further, reinforcing deck portions 8 are formed between adjacent communication ports 7, respectively. Thereafter, a water jacket 6 is obtained by removing sand, and the inner circumferential surface of each sleeve 3 is machined into a perfect circle, and other predetermined processes are performed to form a cylinder block S shown in FIGS. 1 to 3. is obtained.

C. Effects of the Invention According to the present invention, the cross-sectional area of the runner along both lower edges of the cylinder block molding cavity that are substantially parallel to the crank axis is gradually reduced from upstream to downstream on the hot water supply section side. Therefore, the molten metal level in the cavity can be raised almost uniformly over the entire cavity to prevent gases such as air from getting into the molten metal, thereby avoiding the formation of cavities in the cylinder block material. can. Furthermore, since the cavity is filled with molten metal from both lower edges thereof, the filling operation can be performed efficiently and casting efficiency can be improved.

[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 figures are a sectional view taken along the line in Fig. 1, Fig. 2A is a sectional view taken along the line a-a in Fig. 2, Fig. 3 is a perspective view taken from below, and Fig. 4 is a perspective view taken from above of the Siamese type cylinder block material. 5 is a longitudinal sectional front view of a casting apparatus to which an embodiment of the present invention is applied when the mold is opened, FIG. 6 is a longitudinal sectional front view of the casting apparatus when the mold is closed, and FIG. 8 is a sectional view taken along the line from FIG. 7, FIG. 9 is a sectional view taken along the line taken from FIG. 5, and FIG. 10 is a perspective view of the sand core seen from above.
Figure 11 is a sectional view taken along the line of Figure 10, and Figure 12 is
The figure is a graph showing the relationship between the displacement of the plunger with respect to time and the pressure of molten metal with respect to time. A... Hot water supply part, C... Cavity for cylinder block molding, M... Mold as a casting mold, Sm...
Cylinder block material, 17... Runway, 17b...
...bottom, 17c...top, 19...weir.

Claims (1)

[Claims] 1 A mold for casting a cylinder block material for a multi-cylinder internal combustion engine, which includes a cylinder block forming cavity, a pair of runners along both lower edges of the cavity that are substantially parallel to the crank axis, and both runners. It includes a plurality of weirs that communicate between the cavities and a hot water supply section that communicates with the upstream ends of both runners. A mold for cylinder block material in which the top surface of the runner is formed approximately horizontally and the cross-sectional area of both runners is gradually reduced.