JPS62238058A - Metallic mold casting method for cylinder block raw material - Google Patents

Abstract

PURPOSE:To improve the uniformity in solidification of molten metal, the water- tightness of a water jacket and the strength of a cylinder barrel by cooing a sand core for forming water jacket at below the specific temp. and setting the sand core in a cavity of a metallic mold. CONSTITUTION:The mold is opened, and a sleeve 3 having almost real circle section, is fixed to insert in a positioning projection 22, to set a standing. Next, the sand core 59 is cooled at <=0 deg.C, and id really set by engaging the core seats 31 with each core print 63. Then, a core bar 70 is inserted as movable in the cylinder part of the sand core 59, under descending the upper mold 9. After that, the molten metal is supplied into the well part 14 of the lower mold 11 and filled up into the cavities C1 and C2 by ascending a plunger 16. The plunger 16 is shifted at the prescribed velocity, and so the sand core 59 is perfectly enclosed by the molten metal. As the sand core 59 is cooled, the molten metal brought into contact with it is promoted to cool near the cooling velocity for the molten metal at a metallic mold M side. In this way, all over the molten metal is uniformly solidified in the mold, and so development of the casting defects is prevented. Further, the circumferences of the barrel 1 and the outer wall of block 4 are chilled, to show layer-state having fine structure.

Description

Detailed Description of the Invention A0 Object of the Invention (11 Industrial Field of Application) The present invention relates to a cylinder block material, particularly a cylinder barrel, an outer wall of the cylinder block surrounding the cylinder barrel, and a structure between the cylinder barrel and the outer wall of the cylinder block. The present invention relates to a mold casting method for a cylinder having a water jacket facing the outer periphery of the cylinder barrel.

(2) Conventional technology Conventionally, in this type of mold casting method, a sand core used to form a water jacket is placed in a mold cavity at room temperature, and then the cavity is filled with molten metal. .

(3) Problems to be Solved by the Invention In the above-mentioned mold casting method, the molten metal on the sand core side is thermally insulated by the sand core, so the cooling rate is relatively slow;
The molten metal on the side of the work die is cooled by the die, so the cooling rate tends to be relatively fast.

Under these conditions, the molten metal does not solidify uniformly throughout the entire body, causing casting defects such as microporosity and cracking to occur on the inner circumference of the outer wall of the cylinder block that defines the water jacket. There is a problem that watertightness is impaired and the strength of the cylinder barrel is reduced.

An object of the present invention is to provide the above-mentioned die casting method that can solve the above-mentioned problems.

B1 Structure of the Invention (1) Means for Solving the Problems The present invention provides a sand core used for forming the water jacket at 0°C.
The method is characterized in that the sand core is cooled, and then the sand core is placed in a cavity of a mold, and then the cavity is filled with molten metal.

(2) Effect When the cavity is filled with molten metal while the sand core is cooled to below O'C as described above, the cooling of the molten metal in contact with the sand core is accelerated, so the molten metal in the sand core example is The cooling rate of the molten metal approximates the cooling rate of the molten metal on the mold side. This makes it possible to solidify the molten metal substantially uniformly over its entirety, thereby avoiding the occurrence of casting defects.

In addition, the outer periphery of the cylinder barrel and the inner periphery of the outer wall of the cylinder block exhibit a chilled and dense structure due to the cooling promotion effect of the sand core, so that the watertightness of the water jacket and the strength of the cylinder barrel can be improved.

(3) Embodiment Figures 1 to 3 show a Siamese-type cylinder block S in a row, and the cylinder block S includes an aluminum alloy cylinder block body 2 and a cast iron sleeve 3 cast into the body 2. It becomes more. The cylinder block body 2 includes a Siamese cylinder barrel 1 formed by connecting a plurality of cylinder barrels II to 14 in series, in the illustrated example four cylinder barrels II to 14,
It is composed of a cylinder block outer wall 4 surrounding the Siamese cylinder barrel l, and a crankcase 5 connected to the lower edge of the cylinder block outer wall 4, and the sleeve 3 is cast around each cylinder barrel II to 14. , each sleeve 3 forms a cylinder bore 3a.

A water jacket 6 facing the entire outer circumference of the Siamese cylinder barrel 1 is formed between the Siamese cylinder barrel 1 and the cylinder block outer wall 4. At the opening of the cylinder head example in the water jacket 6, the Siamese cylinder barrel l and the cylinder block outer wall 4 are connected by a plurality of reinforcing deck parts 8, and adjacent reinforcing deck parts 8
The space between the cylinders functions as a lower communication link to the cylinder head side. As a result, the cylinder block S is configured into a closed deck type.

Figures 5 to 8 show the cylinder block material S shown in Figure 4.
5. m, the apparatus is equipped with a mold M, and the mold M includes an upper mold 9 that can be raised and lowered, and is disposed below the upper mold 9. In Figure 6, the first and second halves of the left and right halves are
Side type 10. ．． 10° and both sides type 10. ．． It is composed of a lower die 11 on which a 10□ is slidably placed.

A mold clamping recess 12 defining the upper surface of the first cavity CI is formed on the lower surface of the upper mold 9, and mold clamping protrusions 13 that fit into the recess 12 protrude from the upper surfaces of both molds 101°10. will be established. As shown in FIG. 6, the first cavity CI includes a Siamig cylinder barrel molding cavity Ca defined between a water jacket sand core 59 and a mandrel 70 in the mold closed state, and a cavity Ca for forming a Siamig cylinder barrel between the sand core 59 and both sides. Type 10. ．． 1
02 and a cylinder block outer wall molding cavity cb.

7th. As shown in FIG. 8, the lower die 11 includes a sump 14 that receives molten metal made of aluminum alloy from a melting furnace (not shown), a hot water supply cylinder 15 communicating with the sump 14, and a hot water supply cylinder 15 that communicates with the sump 14. A plunger 16 that is slidably engaged with the sump 14 and a pair of runners 17 that branch into two from the sump 14 and extend in the cylinder barrel arrangement direction are provided. Further, the lower mold 11 has a molding block 18 projecting upward between both runners 17, and the molding block 18 includes the molds 10 on both sides,
．． A second cavity C2 for molding the crankcase 5 is defined in cooperation with the second cavity C2. The upper end of the cavity C1 communicates with the first cavity C3, and the lower ends on both sides communicate with both runners 17 via a plurality of gates 19.

The molding block 18 includes four tall semicylindrical first molding parts 18. which are formed at predetermined intervals. , the adjacent first molding section 181 and the outermost brush 1 molding section 18. and a convex-shaped second molded part 18 □ located on the outside of each first molded part 18 . is used to form the crank bin and crank arm rotation space 20 (Figs. 2 and 3), and the second forming part 18□ is used to form the bearing holder 21 of the crank journal (Figs. 2 and 3). used for

Each gate 19 is provided corresponding to each second molding part 18□, so that the large-capacity portion of the second cavity CA is quickly filled with molten metal.

The cross-sectional area of both runners 17 is larger than the tip portions 1 and 7 from the sump portion 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 as to decrease stepwise toward point a.

Each rising portion 17C connected to each step portion 17b is formed diagonally so that the molten metal can be smoothly guided to each gate 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 gate 19 at a slow speed in the large cross-sectional area, and a small amount of molten metal is filled in the small cross-sectional area. Gate 19 at a fast speed
Since the second cavity C2 can be filled through the molten metal, the molten metal rises almost evenly over the entire length from the lower ends of both sides within the cavity Ct, and therefore the molten metal does not cause turbulent flow within the cavities C+ and Cz. This prevents gas 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.

Fifth. As shown in FIG. 6, a positioning protrusion 22 that fits into the inner circumferential surface of the sleeve 3 is protruded from the top surface of each first molded part 181, and a recess 23 is formed in the center of the positioning protrusion 22. Also, two first molded parts 18 located on both sides. Through-holes 24 passing through the first molded part 18I are formed on both sides of the positioning protrusion 22, and a pair of temporary installation pins 25 are slid into the through-holes 24, respectively. It is used for temporary installation of the child 59. The lower ends of both plate installation pins 25 are 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 2 is inserted between the lower part of each support rod 27 and the lower surface of the mounting plate 26.
8 will be reduced.

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 condo 2, so that the tip of each temporary installation pin 25 touches the first molded part 18. protrudes from the top surface. Four parts 25a that engage with the lower edge of the sand core 59 on the tip surface of each temporary installation pin 25
is formed.

In addition, a through hole 29 is formed in the two first molded parts 1B located on both sides at a position trisecting between the re-through holes 24,
The operating pin 30 is slid into the through hole 29 . The lower end of the actuation pin 30 is fixed to the mounting plate 26. When opening the mold,
The tip of the actuating pin 29 protrudes into the recess 23 and is pushed down by the mandrel 70 when the mold is closed, thereby causing the plate installation pins 25 to move into the first molding part 18. It is designed to be pulled in from the top.

First and second side molds 101, 10! Core holders 31 for actually installing sand cores 59 are provided at two locations in the central portion of the wall defining the second cavity C2. Each core holder 31 has a retaining hole 31a for positioning the sand core 59.
and a clamping surface 31b that is formed on the outer periphery of the opening and clamps the sand core.

The upper die 9 includes a plurality of third cavities C1 for communicating with the first cavities CI to overflow the molten metal, a fourth cavity C4 for forming a communicating lower, and each third cavity C1 and fourth cavity C4. Gas vent holes 32 and 33 communicating with each other are formed respectively.

Closing pins 34 and 35 are inserted into the gas vent holes 32 and 33, respectively, and the upper ends of the closing pins 34 and 35 are fixed to a mounting plate 36 disposed above the upper mold 9.

Both cavities c, of each vent hole 32,34.

Small diameter portions 32a and 33a extending upward over a predetermined length from the communicating end with respect to C4 are fitted with respective closing bins 34 and 35 to close the third cavity C1 and the fourth cavity C4. .

A hydraulic cylinder 39 is interposed between the upper surface of the upper die 9 and the mounting plate 36, and the operation of the hydraulic cylinder 39 causes the mounting plate 36 to
Each small diameter portion 32a is raised and lowered by each closing bin 34,35.
, 33a are opened and closed. 40 is the mounting plate 3
6 guidance loft.

The upper die 9 has the mandrels 70 on its lower surface corresponding to each sleeve 3, and a convex portion 70a is formed on the lower surface of each mandrel 70.

9th. FIG. 10 shows a sand core 59 for a water jacket, and the sand core 59 has four cylindrical portions 60.corresponding to the four cylinder barrels 11-14 of the cylinder block S. ~60
In order to form a core main body 61 which is provided with a core body 4 and lacks a peripheral wall that overlaps with the adjacent ones, and a communicating lower and reinforcing deck part 8 that communicates the water jacket 6 with the water jacket of the cylinder head, A plurality of protrusions 62 protruding from the upper end surface of the core body 61, and two cylindrical portions 60□, 60. It is comprised of baseboards 63 protruding from both outer surfaces of the baseboard. Each baseboard 6
3 is formed by a large diameter portion 63a integral with the core body 61 and a small diameter portion 63b protruding from the end face thereof.

Next, a description will be given of the casting operation of the cylinder block material Sm using the casting apparatus.

First, as shown in FIG. 5, the upper mold 9 is raised and the molds 10+ and 10g on both sides are moved apart from each other to open the mold. In addition, the hydraulic cylinder 39 on the upper die 9 is operated to raise the mounting plate 36, thereby causing each closing bin 34 to
．． 35 as the third. It is separated from the small diameter portions 32a and 33a communicating with the fourth cavities ci and c. Further, the plunger 16 in the hot water supply cylinder 15 is lowered.

The lower opening of the approximately perfect circular cast iron sleeve 3 is formed into the first molded part 18.
．． The sleeve 3 is fitted into the positioning protrusion 22 of the first molded part 18. erected above.

Fifth. As shown in Fig. 10, the sand core 59 is
Cool to 0°C, preferably -10°C to -15°C, and lower the lower edges of the cylindrical parts 60 = 60n on both sides of the sand core 59,
The sand core 59 is temporarily installed by being engaged with the recess 25a of each temporary installation pin 25 protruding from the top surface of the first molded part 181 on both sides.

The two-sided molds 1oe and tow are moved a predetermined distance in the direction in which they approach each other, and each core holder 31 and each baseboard 63 are engaged with each other to perform the actual installation of the sand core 59.

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 sand core 59 is clamped by the clamping surfaces 31b of each core holder 31 by abutting the end surfaces parallel to the clamping surfaces 31b of each core holder 31.

As shown in FIG. 6, the upper die 9 is lowered and the mandrel 70 is attached to each cylindrical portion 60 of the sand core 59. ~60. Insert it loosely into the core 7
The convex portion 70a of No. 0 is fitted into the concave portion 23 on the top surface of the first molded portion 181. As a result, the operating pin 30 is pushed down, and each temporary installation pin 24 is lowered to lower the first molded part 18. Pull in from the top. Also, the mold clamping recesses 12 of the upper mold 9 are connected to the mold 10 on both sides.
．． The mold clamping is performed by fitting into the mold clamping convex portion 13 of 102. Furthermore, each protrusion 62 of the sand core 59 is loosely inserted into each fourth cavity C4.

Molten aluminum alloy is supplied from the melting furnace to the sump 14 of the lower die 11, and the plunger 16 is raised to allow the molten metal to flow from both runners 17 through the gate 19 to the second cavity C! from the lower edge of the cavity C2 and the first cavity C.
The gas such as air in the cavities C+ and Ct filled in I is pushed up by the molten metal and flows into the third cavity. It exits above the upper mold 9 through gas vent holes 32, 33 communicating with the fourth cavities C, C4.

In this case, the runner bottom surface is formed in the shape of several steps ascending from the sump portion 14 side so that the cross-sectional area of both runners 17 gradually decreases toward the tip portion 17a as described above. As the plunger 16 rises, the molten metal is smoothly pushed up into the cavity C2 by both runners 17 through each gate 19 from the lower ends of both sides of the second cavity C2 over its entire length. Therefore, the molten metal does not cause turbulent flow within the cavities C, , C, and gases such as air are prevented from being drawn into the molten metal, thereby avoiding the formation of cavities.

Third. After the fourth cavities C3, C, are filled with molten metal, the hydraulic cylinder 39 on the upper die 9 is operated to remove the mounting plate 36.
is lowered, and the small diameter portions 32a and 33a communicating with both cavities Cs and Ca are closed by the closing pins 34 and 35.

In the pouring operation, the first and second cavities CI
,C! The displacement of the plunger 16 and the pressure of the molten metal to fill it with molten metal are controlled as shown in FIG.

That is, the plunger 16 changes its moving speed to the first to third speeds v.
It is controlled in three stages: 1 to V. In this embodiment, the first speed V is 0.08 to 0.12 m/sec.

2nd speed ■2 is 0.14-0.18 m/sec, 3rd speed
The speed V is 0.04 to 0.0 to achieve a significant deceleration state.
The speed is set at 8 m/sec, and this three-step speed control prevents the molten metal from undulating and forms a quiet molten metal flow that does not involve air or other gases, and efficiently flows the molten metal into both cavities CI and C2. Can be filled well.

In addition, at the first speed V of the plunger 16, the molten metal only fills both runners 17, etc., so the pressure P1 of the molten metal is kept substantially constant, and at the second speed V of the plunger 16. 3rd speed V,,V
, the molten metal fills both cavities C1 and CZ, so the pressure Pt of the molten metal rises rapidly. After the plunger 16 is moved at the third speed V for a predetermined time, the pressure P3 of the molten metal is maintained at 150 to 400 kg/cIll for about 1.5 seconds, thereby completely surrounding the sand core 59 with the molten metal.

After the time has elapsed, the plunger 16 is moved at a speed of V,
Since the molten metal is moved at a reduced speed, the pressure P4 of the molten metal increases, and when the pressure P reaches 200 to 600 kg/cIA, the movement of the plunger 16 is stopped and the molten metal is solidified in this state.

When the sand core 59 is completely wrapped in the molten metal as described above, since the sand core 59 has been cooled to below 0°C, the sand core 59
The cooling of the molten metal in contact with the sand core 59 side is accelerated, and the cooling rate of the molten metal on the sand core 59 side is lowered to the mold M side, and therefore the core metal 70 and both side molds 1
It approximates the cooling rate of molten metal on the 0+, Lot side, etc. This makes it possible to solidify the molten metal substantially uniformly over the entire surface of the molten metal, thereby avoiding the occurrence of casting defects.

In addition, due to the cooling promotion effect of the sand core 59, the outer circumferential portion of the Siamese cylinder barrel 1 and the inner circumferential portion of the cylinder block outer wall 4 exhibit a layered structure with a chilled dense structure. The strength of No. 1 can be improved. In this case, since the sand core 59 is covered with the layer, the sand core 59 is protected by the layer and will not be damaged during the next pressurization of the molten metal.

Also, the sand core 59 is connected to the both side mold 1 through each baseboard 63 of the sand core 59.
0. ．． 10. Because it is held in a more accurate position,
The sand core 59 does not rise when filling the first cavity C1 with molten metal and when pressurizing the molten metal in the cavity C1. Also, the large diameter portion 6 of each skirting board 63
3a has both side types 101, 10. Core holder 31 in
When the sand core 59 tends to swell, the deformation force is supported by each clamping surface 31b, thereby preventing the sand core 59 from deforming and causing each sleeve to swell. A Siamese cylinder barrel l having uniform wall thickness around the three circumferences is obtained.

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

When the cylinder block material Sm is subjected to a grinding process and the protrusions 64 formed by the fourth cavities C4 and which incorporate the protrusions 62 of the sand core 59 are removed, each communicating lower is connected to the adjacent communicating lower. A reinforcing deck portion 8 is formed between each, and water jackets 6 are formed by removing sand.
is obtained, and the inner circumferential surface of each sleeve 3 is machined into a perfect circle, and further other predetermined processing is performed to obtain the first to third sleeves.
The cylinder block S shown in the figure is obtained.

Note that the present invention is applicable not only to the production of Siamese-type cylinder blocks in rows but also to the production of Siamese-type cylinder blocks such as V-type cylinder blocks.

C8 Effects of the Invention According to the present invention, since the cavity is filled with molten metal while the sand core is cooled to below 0°C, the cooling rate of the molten metal in contact with the sand core is accelerated and the cooling rate is controlled by the mold side. This makes it possible to approximate the cooling rate of the molten metal, thereby making it possible to solidify the molten metal substantially uniformly throughout the entirety of the molten metal, thereby avoiding the occurrence of casting defects.

Furthermore, the outer circumferential portion of the cylinder barrel and the inner circumferential portion of the outer wall of the cylinder block exhibit a chilled, dense structure due to the cooling promotion effect of the sand core, so that the watertightness of the water jacket and the strength of the cylinder barrel can be improved.

[Brief explanation of drawings]

Figures 1 to 3 show the Siamese type cylinder block, Figure 1 is a perspective view seen from above, Figure 2 is Figure 1 n-
N-line sectional view, Figure 2A is the 2-a-Ila sectional view,
Figure 3 is a perspective view from below, Figure 4 is a perspective view of the Siamese type cylinder block material seen from above, Figure 5 is a longitudinal sectional front view of the casting machine when the mold is opened, and Figure 6 is a front view of the casting machine when the mold is opened. 7 is a sectional view taken along the line nn in FIG. 1, FIG. 8 is a sectional view taken along the nn line in FIG. 1, and FIG. 9 is a perspective view of the sand core seen from above. , FIG. 10 is a sectional view taken along line x-xvA in FIG. 9, and FIG. 11 is a graph showing the relationship between time and the displacement of the plunger and the relationship between time and the pressure of the molten metal. C8...first cavity, M...mold, Sm...
Siamese type cylinder block material, 1... Siamese cylinder barrel, 1. ~14...
・Cylinder barrel, 4...Cylinder block outer wall, 6
...Water jacket, 59...Sand core time Applicant Honda Motor Co., Ltd. Figure 11 Daily Ordinance fJ (St'C)

Claims (1)

[Claims] For mold casting a cylinder block material comprising a cylinder barrel, a cylinder block outer wall surrounding the cylinder barrel, and a water jacket that is located between the cylinder barrel and the cylinder block outer wall and faces the outer periphery of the cylinder barrel. The method is characterized in that the sand core used to form the water jacket is cooled to below 0°C, then the sand core is placed in a cavity of a mold, and then the cavity is filled with molten metal. , Mold casting method for cylinder block material.