JP5726985B2 - Mold for casting - Google Patents

Description

  The present invention relates to a casting mold used for low pressure casting of a cylinder head of an internal combustion engine, for example.

  Conventionally, an internal combustion engine such as an automobile is provided with a plurality of combustion chambers arranged in series, and a cylinder head of the internal combustion engine is manufactured by, for example, a low pressure casting method. In the low-pressure casting method, the surface of the molten metal that is heated and held in a sealed holding furnace is pressurized with a relatively low-pressure inert gas, compressed air, or the like, and the molten metal is connected to the mold cavity through a sprue. In this method, the cavity is filled and cast.

  In the low pressure casting method, pressurization with the inert gas, compressed air, or the like is maintained until the molten metal filled in the cavity is cooled and solidified. As the metal, for example, a light alloy such as an aluminum alloy is used.

  By the way, in the low-pressure casting method, the molten metal solidifies with directivity from the portion in contact with the inner wall of the cavity toward the pouring gate in order to prevent the formation of a cast hole (hereinafter abbreviated as directional solidification). ) Is preferred. The directional solidification is particularly important when manufacturing a relatively large casting such as the cylinder head.

  A mold used for the low pressure casting method is composed of, for example, an upper mold and a lower mold, the cavity is formed between the upper mold and the lower mold, and the gate is formed in the bottom of the lower mold with the plurality of combustion chambers. It is provided in a plurality of locations on both sides of the arrangement direction along the arrangement direction. In the mold having such a structure, the directional solidification can be relatively easily progressed in the vertical direction from the top surface to the bottom surface of the cavity, but the directional solidification is performed in the horizontal direction at the bottom of the cavity. There is a problem that it is difficult to progress.

  In order to solve the above-described problem in the casting mold used for low pressure casting of the cylinder head, for example, it extends along the direction corresponding to the arrangement direction of the plurality of combustion chambers inside the lower mold, and is cooled. 2. Description of the Related Art There is known a casting mold having a conduit for circulating a medium (for example, see Patent Document 1). In the casting mold, in the lower mold, the cooling medium is supplied from one side end surface in a direction orthogonal to the direction corresponding to the arrangement direction of the plurality of combustion chambers, and discharged from the other side end surface. Has been.

JP-A-5-42355

  However, in recent years, the cylinder head has a tendency to increase in thickness from the gasket surface to the bottom surface of the water jacket, and it is difficult to cause directional solidification to proceed in the horizontal direction in low pressure casting of such a cylinder head. There is an inconvenience that is likely to occur.

  The present invention eliminates such inconvenience, and at the time of low-pressure casting of the cylinder head, it is possible to advance directional solidification in the horizontal direction, and to obtain a cylinder head having excellent quality without a cast hole. An object of the present invention is to provide a casting mold that can be produced.

  According to the study by the present inventors, in the casting mold used for low pressure casting of the cylinder head, the molten metal filled in the cavity becomes particularly high at a portion sandwiched between the plurality of gates, It was found that this part hinders the directional solidification in the horizontal direction. The cylinder head formed in the cavity has a weight on one side that is lighter than the other side along a direction corresponding to an arrangement direction of the plurality of combustion chambers. It has been found that the directional solidification in the horizontal direction becomes non-uniform.

  Therefore, in order to achieve the above object, the casting mold of the present invention corresponds to a plurality of combustion chambers arranged in series and on one side along a direction corresponding to the arrangement direction of the plurality of combustion chambers. Is used when manufacturing a cylinder head lighter than the other side by low pressure casting, and is formed between the upper mold, the lower mold, and the upper mold and the lower mold, and conforms to the outer shape of the cylinder head And a plurality of gates provided on both sides of a portion corresponding to the combustion chamber along a direction corresponding to the arrangement direction of the plurality of combustion chambers in the lower mold. And from both side end surfaces in a direction orthogonal to the direction corresponding to the arrangement direction of the plurality of combustion chambers, along the direction corresponding to the arrangement direction of the plurality of combustion chambers, respectively, between the plurality of gates. Cylinder head formed in the cavity. The cooling medium is supplied from the light side of the cylinder toward the center of the lower mold, and the cooling is reversed from the side of the heavy side of the cylinder head formed in the cavity by reversing at the center. A first cooling medium passage for discharging the medium is provided.

  In the casting mold according to the present invention, the cooling medium is formed between the plurality of gates from the side end surface in a direction orthogonal to a direction corresponding to an arrangement direction of the plurality of combustion chambers by the first cooling medium passage. Is supplied along a direction corresponding to the arrangement direction of the plurality of combustion chambers. At this time, the cooling medium is supplied from the light side of the cylinder head formed in the cavity toward the center of the lower mold, and is inverted at the center of the lower mold to enter the cavity. The cylinder head to be formed is returned to the side end face on the side where it is supplied and discharged.

  As a result, according to the casting mold of the present invention, the plurality of molten metal filled in the plurality of gates is prevented from solidifying prematurely, and the plurality of the central portions of the lower mold are suppressed by the cooling medium. The part sandwiched between the gates can be locally cooled. Therefore, the molten metal filled in the cavity can be prevented from becoming high temperature at the portion sandwiched between the plurality of gates, and the directional solidification of the molten metal can proceed in the horizontal direction.

  In the casting mold of the present invention, the cooling medium is supplied from the light side of the cylinder head formed in the cavity and discharged from the heavy side of the cylinder head. It can be solidified first from the light side of the cylinder head. As a result, according to the casting mold of the present invention, the directional solidification of the molten metal can be progressed uniformly in the horizontal direction even in the portion where the weight of the cylinder head formed in the cavity is different.

  Therefore, according to the casting mold of the present invention, it is possible to obtain an excellent quality cylinder head without a cast hole.

  In the casting mold of the present invention, it is preferable that the first cooling medium passage is inverted below a portion corresponding to a combustion chamber located at a central portion of the plurality of combustion chambers. By doing in this way, the part pinched | interposed into the said plurality of gates of the center part of the said lower mold | type by the said cooling medium can be cooled locally better.

  Further, the casting mold of the present invention is below the first cooling medium passage of the lower mold, from the side end face of the lower mold in a direction along the direction corresponding to the arrangement direction of the plurality of combustion chambers. The cavity is formed between the two gates arranged in a direction corresponding to the direction corresponding to the arrangement direction of the plurality of combustion chambers, in a direction orthogonal to the direction corresponding to the arrangement direction of the plurality of combustion chambers. It is preferable to provide a second cooling medium passage to which a cooling medium is supplied after the molten metal filled in the solidification.

  Since the casting mold of the present invention includes the second cooling medium passage, the cooling medium is circulated through the second cooling medium passage after the molten metal filled in the cavity is solidified. Solidification of the molten metal filled in the gate is promoted. As a result, the casting mold of the present invention can shorten the cycle time.

The typical sectional view showing the example of 1 composition of the metallic mold for casting of the present invention. The top view which shows the shape of the lower mold | type of the casting mold shown in FIG. FIG. 2 is a schematic cross-sectional view of a cylinder head manufactured using the casting mold shown in FIG. 1.

  Next, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.

  A casting apparatus 1 of the present embodiment schematically shown in FIG. 1 is an apparatus used for low-pressure casting of a cylinder head of an internal combustion engine, and is provided below a casting mold 2 and a casting mold 2. And a holding furnace 3 in which a molten metal M such as aluminum is heated and held.

  The casting mold 2 includes an upper mold 4 and a lower mold 5, and a cavity 6 having a shape along the outer shape of the cylinder head as a cast product is formed between the upper mold 4 and the lower mold 5. Here, the upper die 4 is mounted on a movable die base 7 and can be moved up and down by an actuator (not shown). The lower die 5 is fixed to a die base 8 that closes the upper opening of the holding furnace 3. .

  The lower mold 5 includes a plurality of gates 9 communicating with the cavities 6, and a gate gate 10 is detachably attached to each gate 9. Moreover, the lower end of the gate sleeve 10 is connected to the intermediate stalk 11, and communicates with the stalk 12 through the intermediate stalk 11 penetrating the die base 8 up and down. The lower portion of the stalk 12 is inserted into the molten metal M that is heated and held in the holding furnace 3.

  As shown in FIG. 2, the lower mold 5 includes a recess 13 that forms a cavity 6 in the center, and the center of the recess 13 is four combustion chambers 14a, 14b, 14c, and 14d arranged in series. This is a portion corresponding to (indicated by a virtual line in FIG. 2).

  Two lower molds 5 are provided on both sides of the portion corresponding to the combustion chambers 14a, 14b, 14c, 14d along the direction corresponding to the arrangement direction of the four combustion chambers 14a, 14b, 14c, 14d. Four gates 9 are provided. Further, in the portion corresponding to the four combustion chambers 14a, 14b, 14c, 14d arranged in series in the lower mold 5, two intake valves are formed for each combustion chamber 14a, 14b, 14c, 14d. Protrusions 15 and 15 and exhaust valve forming protrusions 16 and 16 are formed. The intake valve forming projection 15 is arranged on the left side of the portion corresponding to the combustion chambers 14a, 14b, 14c, 14d, and the exhaust valve forming projection 16 is arranged on the right side of the portion corresponding to the combustion chambers 14a, 14b, 14c, 14d. Has been.

  Here, FIG. 1 shows a cross section corresponding to the line II in FIG. 2. The cavity 6 has a cross-sectional area on the side 6a on which the intake valve forming projection 15 is arranged, and the exhaust valve forming projection 16 is arranged. It is wider than the cross-sectional area of the side 6b. Accordingly, the cylinder head formed in the cavity 6 has a side 6b on which the exhaust valve forming projection 16 is disposed along a direction corresponding to the arrangement direction of the four combustion chambers 14a, 14b, 14c, 14d. Is lighter than the weight of the side 6a on which the intake valve forming projection 15 is disposed.

  Returning to FIG. 2, the lower mold 5 has two end faces 5 a and 5 b in a direction perpendicular to the direction corresponding to the arrangement direction of the four combustion chambers 14 a, 14 b, 14 c and 14 d. Between the gates 9 and 9, first cooling medium passages 17a and 17b are formed along a direction corresponding to the arrangement direction of the four combustion chambers 14a, 14b, 14c and 14d.

  The first cooling medium passage 17a is disposed toward the center of the lower mold 5 with the exhaust valve forming projection 16 side of the side end face 5a as the cooling medium supply port, and is a portion corresponding to the combustion chamber 14b. Inverted downwardly, the side of the intake valve forming projection 15 on the side end face 5a is used as the outlet for the cooling medium. The first cooling medium passage 17b is disposed toward the center of the lower mold 5 with the side of the exhaust valve forming projection 16 on the side end face 5b as the cooling medium supply port, and corresponds to the combustion chamber 14c. Inverted below the portion, the side of the intake valve forming projection 15 on the side end face 5b is used as the outlet for the cooling medium.

  As a result, the first cooling medium passages 17a and 17b supply the cooling medium from the light side (exhaust valve forming projection 16 side) 6b of the cylinder head formed in the cavity 6, and the cylinder head Is discharged from the heavy side (intake valve forming projection 15 side) 6a.

  In addition, second cooling medium passages 18a and 18b are formed in the lower mold 5 below the first cooling medium passages 17a and 17b. The second cooling medium passages 18a and 18b extend from the side end surfaces 5c and 5d of the lower mold 5 along the direction corresponding to the arrangement direction of the four combustion chambers 14a, 14b, 14c and 14d. Are formed in a direction perpendicular to the direction corresponding to the arrangement direction of the four combustion chambers 14a, 14b, 14c, 14d.

  The second cooling medium passage 18a is disposed between the gates 9 and 9 from the side end surface 5c of the lower mold 5 toward the center of the lower mold 5, and below the portion corresponding to the outer edge of the combustion chamber 14b. Bent once at the side end face 5c, bent again before the side end face 5c, toward the center of the lower mold 5, and bent three times below the portion corresponding to the outer edge of the combustion chamber 14c. It is made to return to the end surface 5c. The second cooling medium passage 18b is disposed between the gates 9 and 9 from the side end surface 5d of the lower mold 5 toward the center of the lower mold 5, and corresponds to the outer edge of the combustion chamber 14b. And bent once again in the direction of the side end face 5d, bent again before the side end face 5d, toward the center of the lower mold 5, and bent three times below the portion corresponding to the outer edge of the combustion chamber 14c. And return to the side end face 5d.

  In the casting apparatus 1 of the present embodiment, a relatively low pressure gas such as compressed air is supplied from a pressure inlet (not shown) into the holding furnace 3 to pressurize the surface of the molten metal M. It is raised into the intermediate stalk 11 and press-fitted into the cavity 6 through the gate sleeve 10. And the cylinder head 21 shown in FIG. 3 as a cast product can be obtained by cooling and solidifying the molten metal M in the cavity 6 while maintaining the pressurized state by the gas such as the compressed air.

  3 shows a cross section corresponding to the line III-III in FIG. 2, and the cylinder head 21 is provided with an intake passage 22 on the left side of FIG. 3 and an exhaust passage 23 on the right side. The intake passage 22 and the exhaust passage 23 are curved and open to the side surfaces 21a and 21b and the bottom surface 21c of the cylinder head 21, respectively.

  Such an intake passage 22 and an exhaust passage 23 can be formed by placing and casting a sand core on the intake valve forming protrusion 15 and the exhaust valve forming protrusion 16 shown in FIG. The cylinder head 21 includes cavities 24 a, 24 b and 24 c used for cooling water passages and the like, and the cavities 24 a, 24 b and 24 c also have sand cores at corresponding positions in the cavity 6. Formed by placing and casting.

  The cross-sectional area of the cylinder head 21 shown in FIG. 3 corresponds to the side 6a of the cavity 6 shown in FIG. 1 where the intake valve forming projection 15 is arranged and the side 6b where the exhaust valve forming projection 16 is arranged. The cross-sectional area on the side including the passage 22 is larger than the cross-sectional area on the side including the exhaust passage 23. Therefore, it can be seen from FIG. 3 that the weight of the cylinder head 21 on the side including the exhaust passage 23 is lighter than the weight on the side including the intake passage 22.

  When casting the cylinder head 21 as described above, the molten metal M filled in the cavity 6 progresses directional solidification in the vertical direction from the upper mold 4 to the lower mold 5. On the other hand, in the horizontal direction, the molten metal M has a portion where the heat is high at the center of the cavity 6 surrounded by the gates 9 and 9.

  Therefore, in the casting apparatus 1 of the present embodiment, first, a cooling medium, for example, water is circulated through the first cooling medium passages 17a and 17b. The water is supplied from the side of the side end faces 5a, 5b of the lower mold 5 to the central portion of the lower mold 5 between the gates 9, 9 from the exhaust valve forming projection 16 side, and is inverted at the central portion of the lower mold 5. After that, it returns to the same side end surfaces 5a and 5b as the supplied side, and is discharged from the intake valve forming projection 15 side. As a result, the central portion of the cavity 6 surrounded by the gates 9 and 9, more specifically, the two combustion chambers 14b and 14c at the center of the four combustion chambers 14a, 14b, 14c and 14d arranged in series. The portion corresponding to is locally cooled, and the directional solidification proceeds from the periphery of each gate 9 toward each gate 9.

  Further, in the casting apparatus 1 of the present embodiment, the first cooling medium passages 17a and 17b are for exhaust valve formation with respect to the direction corresponding to the arrangement direction of the four combustion chambers 14a, 14b, 14c, and 14d. The cooling medium is supplied from the projection 16 side, that is, from the light side of the cylinder head 21 formed in the cavity 6, and discharged from the intake valve formation projection 15 side, that is, from the heavy side of the cylinder head 21. . As a result, the molten metal M forming the light side of the cylinder head 21 formed in the cavity 6 is first cooled and solidified, and the horizontal direction is also applied to portions having different weights of the cylinder head 21. Sexual coagulation can proceed uniformly.

  At this time, by preventing the cooling medium from flowing through the second cooling medium passages 18a and 18b, the melt M filled in the pouring gate 9 is prevented from solidifying prematurely, while entering the cavity 6. It is possible to solidify the filled molten metal M to obtain an excellent quality cylinder head 21 without a cast hole.

  Next, when the molten metal M filled in the cavity 6 is solidified, a cooling medium, for example, air is circulated through the second cooling medium passages 18a and 18b. The air is supplied from the side end surfaces 5c and 5d of the lower mold 5 toward the center of the lower mold 5, and the side ends 5c and 5d and the center of the lower mold 5 are formed according to the shape of the second cooling medium passages 18a and 18b. Are returned to the same side end surfaces 5c and 5d as the supplied side, and discharged. As a result, solidification of the molten metal M filled in the gate 9 can be promoted, and the casting cycle time by the casting apparatus 1 can be shortened.

  When the pressurization is released after the molten metal M in the cavity 6 is solidified, the unsolidified molten metal M in the gate 9 is returned to the holding furnace 3 through the intermediate stalk 11 and the stalk 12. Also, the cylinder head 21 as a cast product is taken out by moving the upper mold 4 upward and opening the casting mold 2.

  2 ... Casting die, 4 ... Upper die, 5 ... Lower die, 6 ... Cavity, 9 ... Sprue, 17a, 17b ... First cooling medium passage, 18a, 18b ... Second cooling medium passage, 21 ... Cylinder head.

Claims (3)

It is used when producing a cylinder head corresponding to a plurality of combustion chambers arranged in series and having a weight on one side that is lighter than the other side along the arrangement direction of the plurality of combustion chambers by low pressure casting,
An upper die, a lower die, a cavity formed between the upper die and the lower die and shaped along the outer shape of the cylinder head, and a direction corresponding to the arrangement direction of the plurality of combustion chambers in the lower die A plurality of gates provided on both sides of the portion corresponding to the combustion chamber along the communication with the cavity,
A direction corresponding to the arrangement direction of the plurality of combustion chambers between the plurality of gates from both side end surfaces in a direction orthogonal to the direction corresponding to the arrangement direction of the plurality of combustion chambers inside the lower mold The cooling medium is supplied from the light side of the cylinder head formed in the cavity toward the center of the lower mold, and is inverted in the center to be formed in the cavity. A casting mold comprising a first cooling medium passage for discharging the cooling medium from the side end face on the heavy side of the cylinder head.   2. The casting mold according to claim 1, wherein the first cooling medium passage is inverted below a portion corresponding to a combustion chamber located in a central portion of the plurality of combustion chambers. 3. Type.   The casting mold according to claim 1 or 2, wherein the lower mold in a direction along a direction corresponding to an arrangement direction of the plurality of combustion chambers is below the first cooling medium passage of the lower mold. Formed in a direction orthogonal to the direction corresponding to the arrangement direction of the plurality of combustion chambers between the two gates arranged in the direction corresponding to the direction corresponding to the arrangement direction of the plurality of combustion chambers from the side end face A casting mold comprising a second cooling medium passage to which a cooling medium is supplied after the molten metal filled in the cavity is solidified.