JP4950720B2 - Casting apparatus and casting method - Google Patents

Description

  The present invention includes a plurality of mold members slidable with each other, molds the plurality of mold members to form a cavity, and pours molten metal into the cavity to obtain a cast product having an undercut portion. The present invention relates to a casting apparatus and a casting method.

  Generally, cast products manufactured by a casting apparatus are used for various machine parts. This type of casting has a complicated shape and often has an undercut portion. For this reason, the casting apparatus includes a sliding mold having a core and a core pin corresponding to the undercut portion.

  Specifically, a camshaft journal hole which is an undercut portion is provided in a cylinder head constituting the internal combustion engine. Therefore, a casting apparatus for casting the cylinder head uses a core pin corresponding to the camshaft journal hole.

  For example, a cylinder head manufacturing apparatus disclosed in Patent Document 1 includes a lower mold that is positioned and fixed, a pair of first sliding molds that face each other and are close to or away from the lower mold, and the first A pair of second sliding molds that face each other at different positions from the one sliding mold and that move forward and backward along the axial direction of the camshaft journal hole, and each of the second sliding molds can swing freely. An elastic member that constantly urges and energizes a pair of cast pins supported by the second slide mold and one of the second slide molds toward the remaining second slide mold. A drive mechanism capable of advancing and retracting each of the core pins in the axial direction and allowing the second sliding molds to advance and retract in the axial direction, the lower mold, the one set of the first sliding molds, and 1 And an upper die that forms a cavity together with the second sliding die of the set.

  In such a configuration, the lower mold, the first sliding mold, the second sliding mold, and the upper mold are clamped to form a cavity, and the core pin is inserted into the hole of the upper mold. Then, the molten metal is poured into the cavity, and the molten metal is cooled and solidified, whereby a cylinder head having a camshaft journal hole formed at a position corresponding to the core pin is obtained.

  Each core pin is then retracted from the hole along the axial direction of the upper camshaft journal hole, while each second sliding die is retracted together with the core pin. The mold is being opened. Further, each first sliding mold is retracted to perform mold opening, while the upper mold is separated from the lower mold to perform mold opening.

JP 2005-66642 A

  By the way, in particular, when casting a cast product having an undercut portion by a low pressure casting method, the mold is likely to thermally expand due to the heat of the molten metal. For this reason, in the above-described prior art, the mold mating surfaces of the upper mold, the first sliding mold, and the second sliding mold interfere with each other, and the first sliding is performed before the upper mold is opened. There is a problem that the mold and the second sliding mold cannot be moved backward.

  Therefore, it is conceivable to release the clamping force that holds the upper die against the lower die before the first sliding die and the second sliding die are opened (retracted). However, when the clamping force by the upper mold is released, the upper mold slightly rises, so that the cast product is easily pulled upward integrally with the upper mold. At that time, the core pin for forming the camshaft journal hole which is the undercut portion is arranged corresponding to the camshaft journal hole. Thereby, there exists a problem that destruction or a deformation | transformation is caused especially in the undercut part of a casting.

  The present invention solves this type of problem, and can cast a cast product having an undercut portion with high quality and easily, while improving the yield and capable of performing an efficient casting operation. An object is to provide an apparatus and a casting method.

  The present invention includes a plurality of mold members slidable with each other, molds the plurality of mold members to form a cavity, and pours molten metal into the cavity to obtain a cast product having an undercut portion. The present invention relates to a casting apparatus.

  In the casting apparatus, in order to prevent the mold-matching surface provided on at least one mold member from bulging outward from the reference surface position due to thermal expansion during casting, the die-matching surface faces inward from the reference surface position. It is formed in a concave shape that is recessed. Here, the reference surface position refers to the surface position of the mold matching surface that can be satisfactorily slid in a state where the mold members maintain a desired clearance.

  Moreover, it is preferable that the mold matching surface is formed in a curved shape in which the center side in the long side direction is most recessed inward from the reference surface position.

  Furthermore, it is preferable that the mold member includes a fixed mold and a movable mold that is movable forward and backward with respect to the fixed mold, and at least one of the movable molds is provided with a cast pin that is movable forward and backward with respect to the cavity.

  Furthermore, according to the present invention, a plurality of mold members that are slidable with each other are clamped to form a cavity, and a mold matching surface provided on at least one of the mold members is directed inward from a reference surface position. The present invention relates to a casting method in which a cast product having an undercut portion is obtained by pouring a molten metal into the cavity that is formed in a concave shape.

  In the casting method, a step of pouring molten metal into the cavity in a state in which a mold clamping force is applied to the movable mold that is a mold member, and a slide that is the mold member after the molten metal poured into the cavity is solidified. A sliding mold opening process for releasing the movable mold from the cavity; a mold clamping force releasing process for releasing the mold clamping force of the movable mold; and a mold release for opening the movable mold and releasing the cast product. Process.

  Further, in the sliding mold opening step, it is preferable that the cast pin is separated from the cavity before the sliding mold is detached from the cavity.

  In the present invention, the mold matching surface provided on at least one mold member is formed in a concave shape that is recessed inward from the reference plane position. For this reason, even if a mold member thermally expands due to heat during casting, it is possible to prevent the mold mating surface of the mold member from bulging outward from the reference surface position. Accordingly, even during low-pressure casting, the mold members do not interfere with each other due to thermal expansion, and the mold member (sliding mold) slides smoothly and reliably in a state where the desired clamping force is acting. It becomes possible to make it.

  Thereby, before releasing the mold clamping force, the sliding mold as the mold member can be slid, and it is possible to prevent damage and deformation from occurring in the undercut portion of the cast product. For this reason, it is possible to easily cast a cast product having an undercut portion with high quality, reduce the generation of defective products, improve the yield, and perform an efficient casting operation.

  FIG. 1 is a schematic perspective explanatory view of a casting apparatus 10 for low pressure casting according to an embodiment of the present invention.

  The casting apparatus 10 includes a lower mold 12 that is positioned and fixed with respect to the substrate 11, first sliding molds 14a and 14b that are movable on the substrate 11 in the direction of arrow A and are opposed to each other, The second sliding molds 16a and 16b can be moved back and forth in the direction of the arrow B perpendicular to the direction of the arrow A on the substrate 11 and can be moved up and down in the direction of the arrow C at a position facing the lower mold 12. And an upper mold (movable mold) 18.

  The cavity 20 is formed by clamping the casting apparatus 10 (see FIG. 2 and FIG. 3). The cavity 20 corresponds to the shape of a desired casting, for example, a cylinder head.

  As shown in FIG. 1, a pair of guide rails 22 a and 22 b extending in the direction of arrow A and parallel to each other and guide rails 24 a and 24 b extending in the direction of arrow B are provided on the substrate 11. . The first sliding dies 14a and 14b are mounted on the guide rails 24a and 24b and can be advanced and retracted in the direction of arrow A via the cylinders 26a and 26b. The second sliding dies 16a and 16b are mounted on the guide rails 24a and 24b, and can be advanced and retracted in the direction of arrow B via the cylinders 28a and 28b.

  A predetermined number of hole forming pins 30 that enter the cavity 20 are attached to the upper plate 18 to the movable plate 32. The moving plate 32 can be advanced and retracted in the direction of arrow D via an actuator (not shown). For example, a cylinder 34 is connected to the upper mold 18 as a pressurizing unit. The upper mold 18 applies a desired clamping force to the lower mold 12 via the cylinder 34.

  The first sliding molds 14 a and 14 b are provided with mold-matching surfaces 36 a and 36 b on the horizontal plane that slide relative to the upper mold 18, and mold-matching surfaces 38 a and 38 b on the vertical plane side. As shown in FIG. 4, the mold matching surfaces 36 a and 36 b are formed in a concave shape, for example, a curved shape, in which the center side in the arrow B direction is recessed most downward (inward) in the arrow C direction with respect to the reference plane position MP. The As shown in FIG. 5, the mold matching surfaces 38 a and 38 b are formed in a concave shape (curved shape) where the center side in the arrow B direction is most concave inward in the arrow A direction with respect to the reference plane position MP.

  The second sliding molds 16 a and 16 b are provided with mold matching surfaces 40 a and 40 b on the horizontal plane that slide relative to the upper mold 18 and mold matching surfaces 42 a and 42 b on the vertical plane side. The mold matching surfaces 40a and 40b have a concave shape (curved shape) in which the center side in the arrow A direction is most concave inward (downward) in the arrow C direction with respect to the reference plane position MP, similarly to the mold matching surfaces 36a and 36b. It is formed. The mold matching surfaces 42a and 42b are formed in a concave shape (curved shape) where the center side in the arrow A direction is most concave inward in the arrow B direction with respect to the reference plane position MP, similarly to the mold matching surfaces 38a and 38b. (See FIG. 5).

  As shown in FIG. 2, the upper mold 18 includes a mold matching surface 44a, 44b facing the mold matching surfaces 36a, 36b of the first sliding molds 14a, 14b, and a mold matching surface facing the mold matching surfaces 38a, 38b. 46a and 46b are provided. The mold matching surfaces 44a and 44b are formed in a concave shape (curved shape) in which the center side in the arrow B direction is most concave inward with respect to the reference plane position MP, and the mold matching surfaces 46a and 46b are similarly The center side in the arrow B direction with respect to the reference plane position MP is formed in a concave shape (curved shape) that is most recessed inward in the arrow A direction.

  As shown in FIG. 3, the upper mold 18 includes mold matching surfaces 48a and 48b facing the mold matching surfaces 40a and 40b of the second sliding molds 16a and 16b, and a mold matching surface facing the mold matching surfaces 42a and 42b. 50a and 50b are provided. The mold matching surfaces 48a and 48b are formed in a concave shape (curved shape) in which the center side in the arrow A direction is most concave inward with respect to the reference plane position MP, and the mold matching surfaces 50a and 50b are the reference plane positions. The center side in the direction of arrow A with respect to MP is formed in a concave shape (curved shape) that is most concave inward.

  As shown in FIGS. 1 to 3, a plurality of post members 52 are provided on the substrate 11 so as to hold the upper mold 18 in a predetermined lowered position and restrict the upper mold 18 from moving downward. The It is necessary to open the first sliding molds 14a and 14b and the second sliding molds 16a and 16b in a state where the upper mold 18 gives a desired clamping force to the lower mold 12, and the upper mold 18 This is to prevent the mold clamping force from being applied to the first sliding molds 14a and 14b and the second sliding molds 16a and 16b.

  The operation of the casting apparatus 10 formed as described above will be described below along the flowchart shown in FIG. 6 in relation to the casting method according to this embodiment.

  First, under the driving action of the cylinders 26a and 26b, the first sliding dies 14a and 14b move along the guide rails 22a and 22b in directions close to each other (inward in the direction of the arrow A) and contact the lower die 12. . On the other hand, the cylinders 28a and 28b are driven, and the second sliding dies 16a and 16b move in directions close to each other (inward in the direction of arrow B) under the guiding action of the guide rails 24a and 24b, and contact the lower die 12. Touch.

  In this state, the upper mold 18 descends under the driving action of the cylinder 34 and applies a desired mold clamping force to the lower mold 12. Thereby, the mold clamping of the casting apparatus 10 is performed, and the cavity 20 is formed inside the casting apparatus 10 (step S1). At that time, as shown in FIG. 2, the core pin 30 is disposed in the cavity 20.

  Next, the process proceeds to step S <b> 2, and the molten metal is poured into the cavity 20. Then, when the molten metal poured into the cavity 20 is cooled and solidified (step S3), the casting pin 30 moves the moving plate 32 while a desired clamping force is applied to the casting apparatus 10. It is retracted downward from the cavity 20 (step S4).

  Further, the cylinders 26a and 26b are driven, and the first sliding molds 14a and 14b move in a direction away from the cavity 20 to perform mold opening. On the other hand, under the driving action of the cylinders 28a and 28b, the second sliding dies 16a and 16b move in a direction away from the cavity 20 to perform mold opening (step S5).

  Then, after the clamping force of the upper mold 18 by the cylinder 34 is released (step S6), the process proceeds to step S7, and the upper mold 18 is raised. At that time, a product (cast product) solidified in the cavity 20 is stuck to the upper die 18, and this product is released from the upper die 18 (step S 8).

  As described above, when the low-pressure casting operation is performed by the casting apparatus 10, the lower mold 12, the first sliding molds 14a and 14b, the second sliding molds 16a and 16b, and the upper mold 18 are molds. It is exposed to relatively high heat and causes thermal expansion. For example, in the first sliding die 14a, both end sides in the direction of arrow B are exposed to the outside, so that they are maintained at a relatively low temperature, while the center side in the direction of arrow B is likely to be at a relatively high temperature.

  For this reason, as shown in FIG. 7, when the die-matching surface 36a1 of the first sliding die 14a is configured to be a flat surface (the same shape as the reference surface), the die-matching surface 36a1 is moved to an arrow by thermal expansion. The center side in the B direction has a convex shape that protrudes most outward (see a two-dot chain line in FIG. 7). As a result, even if the upper mold 18 is held by the plurality of post members 52 and the mold clamping force of the upper mold 18 is prevented from being applied to the first sliding mold 14a, the mold clamping force is reduced. There is a possibility that the mold fitting surface 36a1 is applied to the first sliding mold 14a and interferes with the upper mold 18, and the first sliding mold 14a cannot be opened.

  Therefore, in the present embodiment, the mold matching surface 36a of the first sliding mold 14a is formed in a concave shape in which the center in the arrow B direction is most concave inward. For this reason, as shown in FIG. 8, when the first sliding mold 14a is thermally expanded, the concave mold matching surface 36a is deformed along the substantially reference plane position MP (see the broken line in FIG. 8).

  On the other hand, the die matching surface 44a of the upper die 18 is formed in a concave shape in which the center in the arrow B direction is most concave inward. Therefore, when the upper mold 18 is thermally expanded, the mold matching surface 44a is deformed along the substantially reference plane position MP.

  Thereby, the mold clamping surface 36a of the first sliding mold 14a and the mold matching surface 44a of the upper mold 18 do not interfere with each other, and a desired mold clamping force is applied between the upper mold 18 and the lower mold 12. In this state, the first sliding die 14a can be opened smoothly and reliably.

  Furthermore, the die-matching surface 38a on the vertical surface side of the first sliding die 14a and the die-matching surface 46a on the vertical surface side of the upper die 18 are formed in concave shapes that are recessed toward the inside, respectively. It becomes possible to prevent the mating surfaces 38a and 46a from interfering with each other. Furthermore, the first sliding mold 14b and the upper mold 18, and the second sliding molds 16a and 16b and the upper mold 18 are configured in the same manner as the first sliding mold 14a and the upper mold 18. .

  For this reason, in the casting apparatus 10, after the molten metal is solidified in the cavity 20 and before releasing the clamping force by the upper mold 18, the first sliding molds 14 a and 14 b and the second sliding mold are released in addition to the core pin 30. The molds 16a and 16b can be smoothly and reliably retracted. As a result, it is possible to effectively prevent the undercut portion of the product from being damaged or deformed, and it is possible to easily cast various products having the undercut portion with high quality. It is done.

  Moreover, wear due to interference between the upper mold 18 and the first sliding molds 14a and 14b and the second sliding molds 16a and 16b is greatly reduced, and the durability of the casting apparatus 10 can be improved.

  Furthermore, the cast product (product) manufactured according to the present embodiment is obtained with high accuracy without deformation or damage of the undercut portion. For this reason, there is an advantage that the number of post-processing steps can be effectively reduced and it is economical.

  In addition, the clearance between the upper mold 18 and the first sliding molds 14a and 14b and the second sliding molds 16a and 16b can be maintained satisfactorily, and the gas venting performance is effectively improved. Thereby, defective products due to casting defects are effectively reduced, and the yield can be easily improved.

It is a schematic perspective explanatory drawing of the casting apparatus for low pressure casting which concerns on embodiment of this invention. It is sectional explanatory drawing along the arrow A direction of the said casting apparatus. It is sectional explanatory drawing along the arrow B direction of the said casting apparatus. It is explanatory drawing of the 1st sliding type | mold which comprises the said casting apparatus. It is a plane explanatory view of the casting apparatus. It is a flowchart explaining the casting method which concerns on embodiment of this invention. It is explanatory drawing of a common 1st sliding type. It is explanatory drawing of the type | mold matching surface of the said casting apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Casting apparatus 12 ... Lower mold | type 14a, 14b, 16a, 16b ... Sliding mold | type 18 ... Upper mold | type 20 ... Cavity 30 ... Casting pin 36a, 36a1, 36b, 38a, 38b, 40a, 40b, 42a, 42b, 44a , 44b, 46a, 46b, 48a, 48b, 50a, 50b ... mold matching surface

Claims (5)

A casting apparatus comprising a plurality of mold members slidable relative to each other, forming a cavity by clamping the plurality of mold members, and pouring a molten metal into the cavity to obtain an undercut portion. And
The mold member includes a fixed mold, a slide mold that is slidable with respect to the fixed mold, and a movable mold that is close to or spaced from the fixed mold and forms a mold matching surface between the mold and the slide mold. And
Die matching surface between the sliding type as before Symbol movable type, in order to suppress the bulging outward from the reference plane position due to thermal expansion during casting, concaved inwardly from said reference surface position A casting apparatus having a concave shape.   The casting apparatus according to claim 1, wherein the die-matching surface is formed in a curved shape in which a center side in the long side direction is most concave inward from the reference surface position. In casting apparatus according to claim 1 or 2 wherein, prior to SL to the movable mold or the sliding type, casting apparatus and providing a freely core pin advancing and retracting with respect to said cavity. A mold member comprising: a stationary mold; a sliding mold that is slidable with respect to the stationary mold; and a movable mold that approaches or separates from the stationary mold and forms a mold matching surface with the sliding mold. together with and clamping to form a cavity, a casting method to obtain a cast product having an undercut portion by pouring the molten metal into the mold clamping has been said cavity,
The die matching surface between the sliding mold and the movable mold, so as to form a concave shape that is recessed toward the reference surface located inward, before while applying a clamping force to hear dynamic type, the cavity Pouring the molten metal;
After the molten metal is poured into the cavity has solidified, a step to open a sliding type in which the front Kisuri dynamic type is removed from the cavity,
A mold clamping force releasing step of releasing the movable mold clamping force;
A mold release step of opening the movable mold and releasing the cast product;
A casting method characterized by comprising:   5. The casting method according to claim 4, wherein, in the sliding mold opening step, the core pin is detached from the cavity before the sliding mold is detached from the cavity.

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