JP3072682B2 - Cylinder block casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder block casting apparatus used for casting an engine cylinder block.

[0002]

2. Description of the Related Art A plurality of cylinders are formed at predetermined positions in a cylinder block, and the upper surface thereof is connected to a cylinder head. The lower part of the cylinder block is a crankcase (skirt part) for covering the crankshaft and the like, and a plurality of bearing holders for the crankshaft are formed at predetermined intervals inside the crankcase (skirt part). Further, a water jacket which is a passage of the cooling water is formed around the cylinder. A mold for casting this cylinder block is composed of a plurality of mold parts, and a cavity is formed inside the mold by combining these mold parts. Further, a sand core for forming the water jacket can be positioned inside the cavity. And
With the mold closed, molten metal is injected from a runner below the cavity to perform casting. That is, the molten metal passes through the skirt portion forming portion and the bearing holder forming portion of the cavity and is filled into the cylinder portion forming portion. Here, the bearing holder is a portion having the largest thickness in the cylinder block for reasons of strength. For this reason, the solidification speed of the molten metal during casting becomes slower than at other parts, particularly at the skirt part forming part near the runner. Further, since a sand core for forming a water jacket is disposed near the bearing holder, the molten metal at the bearing holder forming portion is hardly cooled by the sand core having high heat retention. As a result, the molten metal in the bearing holder portion solidifies last, and casting defects such as shrinkage cavities are likely to occur in this portion.

[0003] A casting apparatus which takes measures to solve this problem is described in Japanese Patent Application Laid-Open No. 61-180664. In this casting apparatus, a movable nest, which is one of mold parts, is formed with a projection which also serves as a cooling metal. And, by this projection, the thick part of the bearing holder,
Concave portions are provided from both sides in the width direction of the cylinder block to just below the water jacket, and lightening is performed so as not to reduce the strength. By thinning the thick part in this manner, the effect of reducing the thickness of the bearing holder and the effect of the chill of the projection part accelerate the solidification of the molten metal. As a result, the solidification of the molten metal at the bearing holder molding site is faster than the solidification of the molten metal at the skirt molding region near the runner, and casting defects are less likely to occur due to directional solidification.

[0004]

However, in the above-mentioned conventional casting apparatus, the protrusion formed on the movable nest always remains in the cavity by an amount equal to the depth of the recess formed in the thick part. It is protruding. For this reason, the molten metal injected into the cavity is guided to the cylinder portion forming portion above the cavity in a state in which the molten metal is in contact with the protrusion and loses heat. In other words, the effect of the protrusion as a cooler appears from the time when the molten metal is injected into the cavity, which adversely affects the filling of the molten metal into the cylinder molding portion. Further, as described above, since the cooling start timing by the chill cannot be controlled, it is difficult to control the directional solidification effectively. The technical problem of the present invention is to adjust the amount of protrusion of the protrusion,
For example, when the molten metal is injected into the cavity, the amount of protrusion should be minimized so as not to adversely affect the filling of the molten metal, and after the filling of the molten metal is completed, the amount of protrusion should be adjusted to a predetermined value. Accordingly, the solidification of the molten metal at the bearing holder molding site is efficiently accelerated to prevent the occurrence of casting defects.

[0005]

The above-mentioned object is achieved by a cylinder block casting apparatus having the following components. That is, the cylinder block casting apparatus according to the present invention forms a recess in a thick portion of a bearing holder of a cylinder block by a projection provided on a molding surface of a mold for casting a cylinder block. In the cylinder block casting device for punching, the protrusion of the mold has a function as a chiller for increasing the cooling rate of the molten metal, and has a structure capable of adjusting the amount of protrusion during casting. It is characterized by the following.

[0006]

According to the present invention, the projection used for forming the hollow for hollowing out the thickened portion of the bearing holder of the cylinder block has a function as a chiller. The amount can be adjusted. Therefore, if the amount of protrusion of the projection is minimized when pouring the molten metal into the cavity, the amount of heat taken by the protruding portion from the molten metal during the pouring becomes small, and the filling of the molten metal is not adversely affected. Also, after the cavity is filled with the molten metal, by projecting the protrusion by a predetermined dimension, a concave portion is formed in the thick portion of the bearing holder, and the thick portion can be lightened. . As a result, the solidification of the molten metal in the bearing holder portion is accelerated by the effect of reducing the thickness of the bearing holder thick portion and the effect of the chill of the projection. In addition, by adjusting the amount of protrusion of the protrusion, the thickness of the bearing holder and the amount of heat that the protrusion removes from the molten metal can be adjusted. The solidification of the molten metal in the thick part of the bearing holder can be accelerated. As a result, the directional solidification of the molten metal is performed, and casting defects hardly occur.
In addition, since the protrusion can be made to protrude after the filling of the molten metal into the cavity is completed, the protrusion also functions as a local pressure pin, and a more complete casting defect countermeasure can be performed. .

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cylinder block casting apparatus according to a first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 and FIG. 2 are longitudinal sectional views showing a main part of a cylinder block casting apparatus according to the present embodiment. The mold 10 used in the casting apparatus includes a movable mold 11 for molding the upper surface of the cylinder block, a fixed mold 12 for molding the lower surface of the cylinder block, and a plurality of movable nests 13 for molding the outer surface of the cylinder block. It is composed of The movable mold 11 is connected to an elevating device (not shown), and can be moved up and down within a predetermined range by operating the elevating device. Also each movable nest 1
Numeral 3 is connected to a horizontal moving device (not shown).
The upper part can be moved within a predetermined range. The movable mold 11, the fixed mold 12, and the movable nest 13
Are combined, a cavity 14 for forming a cylinder block is formed inside the mold 10.

Here, the cylinder block includes a cylinder portion in which a plurality of cylinders are formed in a line, and a crankcase portion located below the cylinder portion, and is provided inside the crankcase portion (skirt portion). A predetermined number of bearing holders for the crankshaft are formed. For this reason, as shown in FIGS. 1 and 2, the cavity 14 is provided with a cylinder portion forming portion 14c, a crankcase (skirt portion) forming portion 14k, and a bearing holder forming portion 14j. Further, the cavity 1
A sand core 15 for forming a water jacket, which is a passage for cooling water, is positioned at a prescribed position by a support mechanism (not shown) in the cylinder portion forming portion 14c of No. 4. When the mold 10 is clamped, molten metal is injected from a runner below the cavity 14 by an injection device (not shown) to perform casting. That is, the molten metal passes through the skirt portion forming portion 14k and the bearing holder forming portion 14j of the cavity 14, and is filled into the cylinder portion forming portion 14c. The bearing holder has the largest thickness in the cylinder block for reasons of strength.

The movable nest 13 has a recess forming mechanism 2.
0 is attached. The recess forming mechanism 20 includes a recess 14p for thinning the thick portion of the bearing holder from both sides in the width direction of the cylinder block to immediately below the water jacket within a range that does not reduce the strength of the bearing holder.
Is formed. Here, the recess 14p for lightening of the bearing holder is formed from both sides in the width direction of the cylinder block to immediately below the water jacket, so that the recess forming mechanism 20 is provided for one bearing holder. Two sets are needed. For example, series type 4
In the case of a cylinder engine, since a total of three bearing holders are provided, one for each cylinder, six sets of the recess forming mechanisms 20 are provided.

The recess forming mechanism 20 includes a hydraulic cylinder 2
2, a piston rod 24 operated by the hydraulic cylinder 22, and a rod-shaped chiller 26 fixed to the tip of the piston rod 24. On the other hand, the movable nest 13 has through-holes 13 a and 13 b for accommodating the hydraulic cylinder 22 and the piston rod 24,
A recess 13c for accommodating the chill 26 is formed horizontally with the center lines aligned. The hydraulic cylinder 22 is fixed to the movable nest 13 while being housed in the through hole 13a. The piston rod 24 and the chill 26 are slidably housed in the through hole 13b and the recess 13c, respectively. Here, the hydraulic cylinder 22 is divided into a first oil chamber 22a and a second oil chamber 22b by a piston portion of a piston rod 24, and a hydraulic pipe (shown in the figure) is provided to these oil chambers 22a and 22b. Not connected). When the hydraulic pressure from the hydraulic device acts on the first oil chamber 22a, the hydraulic cylinder 22 is driven in a direction in which the piston rod 24 extends, and
The chiller 26 fixed to the end of the movable nest 13
Protrudes from the molding surface by a predetermined amount. In addition, the protrusion amount of the cooling metal 26 can be set to an arbitrary value. Conversely, when hydraulic pressure from a hydraulic device acts on the second oil chamber 22b, the hydraulic cylinder 22
Is driven in the direction in which is stored, and the chill 26 is stored in the recess 13 c of the movable nest 13. In a state in which the cooling metal 26 is accommodated in the movable nest 13 to the maximum extent, as shown in FIG.
3 is kept slightly protruding from the molding surface. That is,
The rod-shaped chill 26 functions as a projection used to form a hollow for hollowing out the thick part of the bearing holder.

Next, the operation of the cylinder block casting apparatus according to this embodiment will be described. First, each movable nest 1
The molds 10 are clamped by moving the movable molds 11 to a position where they engage with each other by the horizontal moving device, and further lowering the movable mold 11 to a position where it contacts the movable nest 13 by the elevating device. At this time, the chill 26 of the concave forming mechanism 20 mounted on the movable nest 13 is held in a state in which it is accommodated in the concave 13c of the movable nest 13 to the maximum. When the clamping of the mold 10 is completed, the cavity 1 is removed from the runner below the mold 10 by the injection device.
The molten metal is injected into 4. Here, since the chill 26 of the recess forming mechanism 20 is housed in the movable nest 13 as described above, the amount of heat that the chill 26 takes away from the molten metal in the course of pouring is small. The filling of the molten metal up to the part forming portion 14c is favorably performed.

After a predetermined time has elapsed since the cavity 14 was filled with the molten metal, solidification of the cylinder molding portion 14c progressed to some extent, and the bearing holder molding portion 14j
Then, the oil pressure acts on the first oil chamber 22a of the hydraulic cylinder 22 at a timing when the oil has not yet solidified. As a result, as shown in FIG. 2, the chill 26 protrudes from the molding surface of the movable insert 13 by a predetermined dimension. A concave portion 14p is formed in the thick portion of the bearing holder from both sides in the width direction of the cylinder block to immediately below the water jacket 15, and the thick portion is lightened. As a result, the solidification of the molten metal is accelerated by the effect of reducing the thickness of the bearing holder and the effect of cooling the chiller 26. As a result, the solidification of the molten metal in the bearing holder molding portion 14j is faster than that of the molten metal in the skirt molding portion 14k located near the runner, and directional solidification is performed, so that casting defects are less likely to occur. Since the chill 26 is projected at a timing when the molten metal in the bearing holder forming portion 14j is not solidified, an uneven force is not applied to the sand core 15, and the sand core 15 may be damaged or deformed. There is no.

When the solidification of the entire cylinder block is completed in this way, the second oil chamber 2 of the hydraulic cylinder 22 is
Hydraulic pressure acts on 2b, and the hydraulic cylinder 22 is driven in a direction in which the piston rod 24 is housed, and the chiller 26 is housed in the recess 13c of the movable nest 13. Next, the movable mold 11 is raised, and the movable nest 13 is moved in a direction away from each other, whereby the mold 10 is opened and the cylinder block is taken out. Then, the sand core 15 in the cylinder block is taken out to form a water jacket. When the casting of the cylinder block is completed and the cylinder block is removed from the mold 10, the hydraulic pressure from the hydraulic device acts on the first oil chamber 22 a of the hydraulic cylinder 22, and the hydraulic cylinder 22 extends the piston rod 24. Driven in this direction, the chill 26 protrudes as much as possible from the molding surface of the movable nest 13. Then, the chill 26 is cooled for the next casting, and a release agent is applied to its surface. Next, hydraulic pressure acts on the second oil chamber 22 b of the hydraulic cylinder 22, and the chiller 26 moves the recess 1 of the movable nest 13.
3c. At the same time as applying the release agent to the cooling metal 26, the release agent is also applied to the molding surface of the mold 10 for the next casting. Here, after the solidification of the entire cylinder block is completed, the chiller 26 is driven in the extending direction or remains at the time of completion of the solidification, and after the movable mold 11 is raised, the movable nest 13 is retracted to cool down. The gold 26 may be pulled out of the cylinder block. According to the cylinder block casting apparatus according to the present embodiment, by controlling the amount of protrusion of the chill 26, the thickness of the bearing holder and the amount of heat taken by the chill 26 from the molten metal can be adjusted. Therefore, it is possible to obtain a high-quality cast product by experimentally obtaining the optimum protrusion amount of the chill 26 in advance and performing the operation with the optimum protrusion amount.

FIGS. 3 and 4 are longitudinal sectional views showing a main part of a cylinder block casting apparatus according to a second embodiment of the present invention. The cylinder block casting apparatus according to the present embodiment improves the structure of the recess forming mechanism 20 used in the first embodiment so that the cooling water can flow at a predetermined timing inside the chiller 26. It was done. The other structure is the same as that of the cylinder block casting apparatus according to the first embodiment. As shown in FIGS. 3 and 4, the recess forming mechanism 120 includes a hydraulic cylinder 122, a piston rod 124 operated by the hydraulic cylinder 122, and a rod-shaped chiller 126 fixed to the tip of the piston rod 124. Be composed. On the other hand, movable nest 113
The hydraulic cylinder 122, the piston rod 124
Through holes 113a and 113b for accommodating the chiller and a recess 113c for accommodating the chiller 126 are formed horizontally with the center lines aligned. The hydraulic cylinder 122 is fixed to the movable insert 113 while being housed in the through hole 113a. The piston rod 124 and the chill 126 are slidably accommodated in the through hole 113b and the recess 113c, respectively.

A hole 1 is formed in the piston rod 124 and the chill 126 in the axial direction from the end of the piston rod 124 to the vicinity of the tip of the chill 126.
26h is drilled. A double pipe 127 having an outer diameter substantially equal to the inner diameter of the hole 126h is housed and fixed inside the hole 126h. Further, the double pipe 127 is slidably inserted into a double pipe through hole 122 k formed in the rear wall of the hydraulic cylinder 122. The through-hole 122 for the double pipe of the hydraulic cylinder 122
k and the double pipe 127, a hydraulic cylinder 122
A sealing material (not shown) is provided so as to prevent oil from leaking from the seal member. Further, the hydraulic cylinder 122
An opening 127a of an inner pipe 127b of the double pipe 127 and an opening 127d of an outer pipe 127c are provided at an end of the double pipe 127 located outside the double pipe 127. It has a structure that can pass through. That is,
The cooling water flowing in from the opening 127a (inlet 127a) of the inner pipe 127b passes through the inner pipe 127b and the cooling water 12 flows through the inner pipe 127b.
6 to the inside of the tip (cooling chamber), and further the outer tube 127
c through the opening 127d of the outer tube 127c (the outlet 127).
d). Here, a cooling water supply pipe (not shown) is connected to the inflow port 127a of the double pipe 127, and a cooling water return pipe (not shown) is connected to the outflow port 127d. . Then, a supply amount of the cooling water flowing in the double pipe 127, a supply start timing of the cooling water, a supply stop timing of the cooling water, and the like can be controlled by a flow rate adjusting device (not shown).

The hydraulic cylinder 122 is connected to a first oil chamber 122a and a second oil chamber 122a by a piston portion of a piston rod 124.
And an oil chamber 122b.
Hydraulic piping (not shown) from a hydraulic device is connected to a and 122b. When the hydraulic pressure from the hydraulic device acts on the first oil chamber 122a, the hydraulic cylinder 122 is driven in the direction in which the piston rod 124 extends, and the chiller 126 fixed to the tip of the piston rod 124 moves. It protrudes from the molding surface of the nest 113 by a predetermined amount. The amount of protrusion of the chill 126 can be set to an arbitrary value. Conversely, when the hydraulic pressure from the hydraulic device acts on the second oil chamber 122b,
The hydraulic cylinder 122 is driven in a direction in which the piston rod 124 is housed, so that the cooling
13 are housed in the recess 113c. In a state in which the cooling metal 126 is accommodated in the movable nest 113 to the maximum extent, the distal end thereof is held in a state of slightly protruding from the molding surface of the movable nest 113.

Next, the operation of the cylinder block casting apparatus according to this embodiment will be described. First, each movable nest 1
The molds 100 are clamped by moving the movable molds 111 to a position where they engage with each other by the horizontal moving device, and further lowering the movable mold 111 to a position where the movable mold 111 comes into contact with the movable nest 113 by the elevating device. At this time, the chill 126 of the concave forming mechanism 120 attached to the movable nest 113 is held in a state where it is accommodated in the concave 113c of the movable nest 113 to the maximum. Is not supplied with cooling water. When the mold 100 is completely clamped, the injection device (not shown) removes the cavity 114 from the runner below the mold 100.
The molten metal is injected into the inside. Here, as described above, the chill 126 of the recess forming mechanism 120 is accommodated to the maximum in the movable nest 113 and is not cooled by the cooling water. The amount of heat is small, and the filling of the molten metal to the depth of the cavity 114, that is, the cylinder forming portion 114c is favorably performed.

When the filling of the molten metal in the cavity 114 is completed, the first oil chamber 122a of the hydraulic cylinder 122 is
As shown in FIG. 3, the chill 126 protrudes from the molding surface of the movable nest 113 by a predetermined dimension as shown in FIG. As a result, a concave portion 114p is formed in the thick portion of the bearing holder from both sides in the width direction of the cylinder block to immediately below the water jacket 115, and the lightening is performed. In this state, since the cooling water has not yet flowed into the chill 126, the amount of heat that the chill 126 takes away from the molten metal is small. Therefore, when the molten metal filled in the cylinder portion forming portion 114c of the cavity 114 solidifies and contracts, it is possible for the molten metal supplied to compensate for this to pass through the bearing holder forming portion 114j. Then, after the molten metal in the cylinder molding portion 114c of the cavity 114 is substantially solidified and the supply of the molten metal to the cylinder molding region 114c becomes almost unnecessary, a predetermined flow rate of the cooling water flows into the double pipe 127. Then, the cooling metal 126 is cooled. Due to the cooling effect of the chill 126 and the effect of thinning the bearing holder, the molten metal in the bearing holder forming portion 114j is solidified faster than the molten metal in the skirt portion forming portion 114k near the runner. That is, the molten metal is moved from the cylinder portion forming portion 114c of the cavity 114 to the bearing holder forming portion 1
14j, directional solidification that solidifies in the order of the skirt portion forming portion 114k becomes possible. This makes casting defects less likely to occur.

When the solidification of the entire cylinder block is completed in this manner, the second oil chamber 1 of the hydraulic cylinder 122 is
Hydraulic pressure acts on 22 b, and the hydraulic cylinder 122 is driven in a direction to house the piston rod 124, and the chiller 126 is housed in the recess 113 c of the movable nest 113. Next, the movable mold 111 is raised, and the movable nest 113 is moved in a direction away from each other, whereby the mold 100 is moved.
Is opened and the cylinder block is taken out. When the cylinder block is removed and casting is completed, the hydraulic pressure from the hydraulic device acts on the first oil chamber 122a of the hydraulic cylinder 122, and the hydraulic cylinder 122 is driven in the direction in which the piston rod 124 extends, and the chiller 126 protrudes as much as possible from the molding surface of the movable insert 113. Then, a release agent is applied to the surface of the chill 126 for the next casting. Next, the second oil chamber 122b of the hydraulic cylinder 122
Hydraulic pressure acts on the movable nest 1
13 are housed in the recess 113c. Here, after the solidification of the entire cylinder block is completed, the chiller 126 is driven in the extending direction, or the movable mold 111 is raised in a state where solidification is completed, and the movable nest 113 is retracted to cool down. The gold 126 may be pulled out of the cylinder block. When the cylinder block is removed from the mold 100, the mold 10 is prepared for the next casting.
The mold release agent is also applied to the molding surface of No. 0.

According to the present embodiment, by controlling the flow rate of the cooling water flowing in the double pipe 127, the supply start timing, and the supply stop timing, the amount of heat taken by the chiller 126 from the molten metal can be controlled. This allows the chiller 12 to adjust the solidification rate of the molten metal.
It is not necessary to finely adjust the amount of protrusion of 6. In this embodiment, an example in which the chill 126 is cooled by cooling water has been described. However, the present invention is not limited to this, and it is needless to say that air or another cooling medium can be used. Further, in the first embodiment and the present embodiment, the method of projecting the chill by a predetermined dimension (L) at a time has been described, but the method of projecting the chill is performed in two steps (L).
= L1 + L2). With this configuration, the chill can be used as a coolant for the molten metal in a state where the chill first protrudes by the dimension L1, and can be used as a local pressure pin in a process of further protruding by the dimension L2 from this state. As a result, even if the solidification of the molten metal at the bearing holder forming portion is delayed, the formation of a cavity can be prevented by the action of the chiller as a local pressure pin. In addition, since the local pressurization is performed after the molten metal in the cylinder portion forming portion is substantially solidified, no pressure is applied to the sand core, so that breakage or deformation of the sand core can be prevented.

[0021]

According to the present invention, the solidification speed of the molten metal in the bearing holder portion of the cylinder block can be controlled by adjusting the amount of projection of the projection serving also as a chiller. For this reason, the solidification of the molten metal in the bearing holder can be accelerated as compared with the molten metal located near the runner in the cavity, and directional solidification can be performed. Thereby, casting defects are less likely to occur and casting quality is improved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a main part of a cylinder block casting apparatus according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view illustrating a main part of a cylinder block casting apparatus according to a first embodiment of the present invention.

FIG. 3 is a longitudinal sectional view illustrating a main part of a cylinder block casting apparatus according to a second embodiment of the present invention.

FIG. 4 is a longitudinal sectional view illustrating a main part of a cylinder block casting apparatus according to a second embodiment of the present invention.

[Description of Signs] 10 Mold 11 Movable mold 12 Fixed mold 13 Movable insert 14 Cavity 15 Sand core 20 Concavity forming mechanism 22 Hydraulic cylinder 24 Piston rod 26 Chiller (protrusion)

Continuation of the front page (51) Int.Cl. ⁷ identification code FI B22D 27/04 B22D 27/04 A F02F 1/00 F02F 1/00 K (58) Field surveyed (Int.Cl. ⁷ , DB name) B22D 15/02 B22C 9/24 B22D 15/00 B22D 17/00 B22D 17/22 B22D 27/04

Claims (1)

(57) [Claims] 1. A cylinder block casting in which a concave portion is formed in a thick portion of a bearing holder of a cylinder block by a projection provided on a molding surface of a cylinder block casting mold, and the bearing holder is lightened. In the apparatus, the protrusion of the mold has a function as a chiller for increasing a cooling rate of the molten metal, and further has a structure capable of adjusting a protrusion amount during casting. Casting equipment.