JP2007253191A - Apparatus and method for casting - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for casting, by which apparatus and method, the advancing speed of a pressing pin can be reduced after quickly pressing a solidified layer (a surface portion of a product) of molten metal. <P>SOLUTION: The apparatus for casting comprises a metallic mold 2 having a cavity 6 formed therein so as to be filled with the molten metal, a pressing pin 7 provided so as to enter and come-out from the cavity 6, and a cylinder 8 having a piston 9 to be connected to the pressing pin 7. As the piston 9 is advanced by supplying working fluid to a rear chamber 8c from a first communicating passage 11, a first passage 13 is changed from a closed state to an opened state and a second passage 14 is changed from an opened state to a closed state. As a result, the advancing speed of the pressing pin 7 is reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a casting apparatus that prevents generation of a cast hole by pressurizing a molten metal filled in a cavity, and a casting method using the casting apparatus.

  In die casting such as die casting, the molten metal in the cavity is pressurized in order to suppress the formation of a cast hole due to solidification shrinkage of the molten metal such as an aluminum alloy.

JP-A-1-205863

  When the molten metal is filled in the cavity, the surface of the molten metal (product surface portion) is solidified by heat exchange with the mold, so that it is necessary to apply a pressure sufficient to break this solidified layer at the start of pressurization. Once the solidified layer is broken by the pressure pin, the pressure pin pushes the unsolidified molten metal. However, in the pressurization apparatus described in the above publication, the pressure applied to pressurize the unsolidified molten metal is as large as in the initial stage of pressurization, so the pressurizing pin pushes through the molten metal at a stretch, and depending on the escape of the molten metal, There is a problem that the pressurization is insufficient and the cavity that causes the nest cannot be crushed.

  Then, an object of this invention is to provide the casting method which can slow down the advance speed of a pressurization pin after breaking through a solidification layer, and the casting method using this casting apparatus.

  In order to achieve the above object, a mold 2 forming a cavity 6 filled with molten metal, a pressure pin 7 provided so as to be able to protrude and retract with respect to the cavity 6, and a piston connected to the pressure pin 7 In the casting apparatus 1 including a cylinder 8 having a cylinder 9, the piston 9 is provided at one end of the piston 9 and slides on the inner wall 8 a of the cylinder 8. A second sliding portion 9b which is provided at the end and slides on the inner wall 8a of the cylinder 8, and a groove portion 9c formed between the first sliding portion 9a and the second sliding portion 9b. The cylinder 8 includes a front chamber 8b defined by the front surface 9d of the piston 9 and the inner wall 8a of the cylinder 8, and an intermediate chamber 8d defined by the groove 9c and the inner wall 8a of the cylinder 8. A rear surface 9e of the piston 9 and the cylinder 8 A rear chamber 8c defined by the inner wall 8a, a first circuit 13 and a second circuit 14 communicating the front chamber 8b and the intermediate chamber 8d, and a first circuit 13 communicating the rear chamber 8c and the external passage 10. A series communication path 11 and a second communication path 12 communicating the intermediate chamber 8d and the external path 10 are provided, and hydraulic oil is supplied from the first series path 11 to the rear chamber 8c so that the piston 9 As the forward movement progresses, the first circuit 13 changes from the closed state to the open state, the second circuit 14 changes from the open state to the closed state, and the forward speed of the pressure pin 9 is reduced. providing.

  Here, the cylinder 8 has a third circuit 15 that communicates the front chamber 8b and the intermediate chamber 8d and in which a check valve 16 is disposed, and is connected to the intermediate chamber from the second communication passage 12. When the hydraulic oil is supplied to 8d and the piston 9 moves backward, the third circuit 15 preferably causes the hydraulic oil to flow from the intermediate chamber 8d to the front chamber 8b.

  Furthermore, the present invention provides a casting method for casting using the casting apparatus 1 according to claim 1 or 2.

  According to the casting apparatus of the first aspect of the present invention, since the pressure pin quickly pressurizes the solidified layer (product surface portion) on the surface of the molten metal, the forward speed of the pressure pin is slowed down. Thus, the molten metal can be pressurized in accordance with the progress of solidification.

  According to the casting apparatus of the second aspect of the present invention, since the third circuit for flowing the hydraulic oil from the groove portion to the front chamber when the piston moves backward is provided, the pressure pin can be quickly returned to the retracted position. .

  According to the casting method of the third aspect of the present invention, since the casting is performed using the casting apparatus of the first or second aspect, the casting having a high quality while suppressing the generation of the cast hole due to the solidification shrinkage of the molten metal. The product can be cast stably.

 A casting apparatus according to an embodiment of the present invention will be described with reference to FIGS. In FIGS. 1 to 4, hatching indicating the cross section is omitted. As shown in FIG. 1, the casting apparatus 1 has a mold 2. The mold 2 includes a fixed mold 3 including a fixed holder 3a and a fixed die 3b, and a movable mold 4 including a movable holder 4a and a movable die 4b.

  The fixed mold 3 is provided with a sleeve 5. When the mold is clamped from the mold open state of FIG. 1, the cavity 6 is defined by the fixed die 3b and the movable die 4b. A plunger tip (not shown) is filled in the cavity 6 with a molten metal such as an aluminum alloy via the sleeve 5.

  A pressure pin 7 is slidably held on the movable die 4b. The pressurizing pin 7 can be moved in and out of the cavity 6. When the pressurizing pin 7 enters the cavity 6, the molten metal filled in the cavity 6 is pressurized. . The pressure pin 7 is connected to a piston 9 described later.

  A cylinder 8 is provided on the movable die 4b. A piston 9 is provided inside the cylinder 8. A first sliding portion 9 a is provided at one end of the piston 9, and the first sliding portion 9 a slides on the inner wall 8 a of the cylinder 8 when the piston 9 moves back and forth in the cylinder 8. A second sliding portion 9 b is provided at the other end of the piston 9, and this second sliding portion 9 b slides on the inner wall 8 a of the cylinder 8 when the piston 9 moves back and forth in the cylinder 8. . The piston 9 has a groove portion 9c between the first sliding portion 9a and the second sliding portion 9b.

  As shown in FIG. 2, in the cylinder 8, a front chamber 8b is defined by a front surface 9d of the piston 9 and an inner wall 8a of the cylinder 8, and a rear chamber 8c is defined by a rear surface 9e of the piston 9 and an inner wall 8a of the cylinder 8. Is defined. In the cylinder 8, an intermediate chamber 8 d is defined by the groove 9 c of the piston 9 and the inner wall 8 a of the cylinder 8.

  The cylinder 8 has a first series passage 11 that communicates the rear chamber 8 c with the external passage 10. The first series passage 11 supplies hydraulic oil from the external passage 10 into the rear chamber 8c when the piston 9 moves forward, and discharges the hydraulic oil from the rear chamber 8c to the external passage 10 when the piston 9 moves backward. To do. In addition, the cylinder 8 has a second communication passage 12 that communicates the intermediate chamber 8 d with the external passage 10. The second communication passage 12 discharges hydraulic oil from the intermediate chamber 8d to the external passage 10 when the piston 9 moves forward, and supplies hydraulic oil from the external passage 10 into the intermediate chamber 8d when the piston 9 moves backward. To do.

  The cylinder 8 has a first circuit 13 and a second circuit 14 that communicate the front chamber 8b and the intermediate chamber 8d. The cross-sectional area of the first circuit 13 is smaller than that of the second circuit 14. When the piston 9 is in the retracted position of FIG. 2, the first circuit 13 is closed by the first sliding portion 9a of the piston 9, and as the piston 9 moves forward, as shown in FIG. The front chamber 8b and the intermediate chamber 8d are communicated with each other in the open state. The second circuit 14 is open when the piston 9 is in the retracted position of FIG. 2 and communicates the front chamber 8b and the intermediate chamber 8d. As shown, the closed state is achieved by the first sliding portion 9a. When the first circuit 13 is in the open state and the second circuit 14 is in the closed state, the first circuit 13 has a smaller cross-sectional area. The amount of hydraulic oil moving to 8d is reduced, and the forward speed of the piston 9 is reduced.

  As shown in FIG. 4, the cylinder 8 has a third circuit 15 that communicates the front chamber 8b and the intermediate chamber 8d in a cross section different from the cross section in which the first circuit 13 and the second circuit 14 are provided. The cross-sectional area of the third circuit 15 is larger than that of the first circuit 13. The third circuit 15 is closed by the first sliding portion 9a of the piston 9 when the piston 9 is in the retracted position of FIG. 1, and is opened by the piston 9 moving forward. A check valve 16 is disposed inside the third circuit 15, and when the third circuit 15 is open, hydraulic oil can flow only from the intermediate chamber 8d toward the front chamber 8b. When the hydraulic oil is supplied from the second communication passage 12 to the intermediate chamber 8d and the piston 9 is moved backward, only the first circuit 13 having a small cross-sectional area takes time, but the third circuit 15 having a large cross-sectional area is provided. Thus, the piston 9 can be quickly returned to the retracted position in FIG.

  The external passage 10 is connected to the hydraulic control means 17. The hydraulic control means 17 includes a hydraulic source (not shown), an electromagnetic switching valve, and the like.

  Next, a casting method using the casting apparatus 1 according to the embodiment of the present invention will be described. In the present casting method, first, the mold is clamped from the state shown in FIG. 1, and the cavity 6 is defined by the fixed die 3b and the movable die 4b. Next, a molten metal such as an aluminum alloy is supplied into the sleeve 5 through a hot water supply hole (not shown) of the sleeve 5, and the molten metal is filled into the cavity 6 with a plunger tip (not shown).

  Next, a pressurizing step of pressurizing the molten metal filled in the cavity 6 with the pressurizing pin 7 is performed. When a solenoid valve (not shown) of the hydraulic control means 17 is switched at a predetermined timing after the completion of filling, and hydraulic fluid is supplied from the external passage 10 into the rear chamber 8c through the first series passage 11 of the cylinder 8, the piston 9 advances from the retracted position shown in FIG. 2 and pressurization of the molten metal 6 by the pressure pin 7 is started. As the piston 9 moves forward, the hydraulic oil in the front chamber 8b moves to the intermediate chamber 8d via the second circuit 14, and the hydraulic oil in the intermediate chamber 8d is discharged from the second communication passage 12 to the external passage 10. The

  The pressurizing pin 7 quickly pressurizes the solidified layer (the product surface portion) on the surface of the molten metal, and then enters the unsolidified portion of the molten metal. As shown in FIG. When the second circuit 14 is closed by the advance of 9a and the first circuit 13 is opened, the sectional area of the first circuit 13 is smaller than the sectional area of the second circuit 14, Since the forward speed is slowed down, the forward speed of the pressure pin 7 is also slowed down. Therefore, the pressure pin 7 moves forward to a predetermined position while reliably crushing the cavity in the molten metal due to the occurrence of the cast hole.

  When cooling of the molten metal is completed, a solenoid valve (not shown) of the hydraulic control means 17 is switched, and hydraulic fluid is supplied from the external passage 10 to the intermediate chamber 8d via the second communication passage 12 of the cylinder 8. Moves to the front chamber 8b via the first circuit 13 and the third circuit 15. When the hydraulic oil moves from the intermediate chamber 8d to the front chamber 8b, the piston 9 moves backward, and the hydraulic oil in the rear chamber 8c is discharged from the first series passage 11 to the external passage 10. The pressurizing process is performed until the piston 9 is retracted to the position shown in FIG.

  When the pressurizing step is completed, the mold 2 is opened and the cast product is taken out.

  The casting apparatus and the casting method of the present invention are not limited to the above-described embodiments, and various modifications or improvements can be made within the scope described in the claims.

  The casting apparatus and the casting method of the present invention are extremely useful in the field of casting in which the molten metal in the cavity is pressurized in order to suppress the formation of a cast hole.

Sectional drawing which shows the mold open state of the casting apparatus by this Embodiment. The expanded sectional view which shows the state which has the piston of the casting apparatus of FIG. 1 in the retreat position in a cylinder. The expanded sectional view which shows the state which the piston of the casting apparatus of FIG. 1 advanced in the cylinder. FIG. 4 is an enlarged cross-sectional view of a section different from that of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casting apparatus 2 Mold 6 Cavity 7 Pressurizing pin 8 Cylinder 8a Inner wall 8b Front chamber 8c Rear chamber 8d Intermediate chamber 9 Piston 9a First sliding portion 9b Second sliding portion 9c Groove portion 10 External passage 11 First series passage 12 Second communication path 13 First circuit 14 Second circuit 15 Third circuit 16 Check valve 17 Hydraulic control means

Claims (3)

In a casting apparatus, comprising: a mold that forms a cavity filled with molten metal; a pressure pin that is provided so as to be able to project and retreat with respect to the cavity; and a cylinder having a piston that is coupled to the pressure pin. A first sliding portion provided on one end of the piston and sliding on the inner wall of the cylinder; a second sliding portion provided on the other end of the piston and sliding on the inner wall of the cylinder; and the first sliding portion. And a groove formed between the moving portion and the second sliding portion, the cylinder including a front chamber defined by the front surface of the piston and an inner wall of the cylinder, the groove and the cylinder. An intermediate chamber defined by an inner wall, a rear chamber defined by a rear surface of the piston and an inner wall of the cylinder, a first circuit and a second circuit communicating the front chamber and the intermediate chamber; The rear chamber communicates with the external passage. A communication passage, and a second communication passage communicating the intermediate chamber and the external passage. When hydraulic oil is supplied from the first series passage to the rear chamber and the piston advances, A casting apparatus, wherein one circuit is changed from a closed state to an open state, and the second circuit is changed from an open state to a closed state, so that a forward speed of the pressure pin is reduced. The cylinder has a third circuit that communicates the front chamber and the intermediate chamber and in which a check valve is disposed, and hydraulic oil is supplied to the intermediate chamber from the second communication passage, and the piston The casting apparatus according to claim 1, wherein the hydraulic fluid flows from the intermediate chamber into the front chamber when the third circuit moves backward. Casting using the casting apparatus according to claim 1 or 2.

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