JP2005329446A - Metallic mold structure with core pin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a metallic mold structure with a core pin, the structure which secures the quality of a cast product by restraining the occurrence of a blow hole, shrinkage hole, etc., caused by a releasing agent intruded into a clearance between a pin fitting hole and the core pin, and which is excellent in durability. <P>SOLUTION: When stress acts on a product forming part 39 of the core pin 3 in the solidification of molten metal in a cavity 20 of the metallic mold, a silicone rubber 40 between the pin fitting part 22 and the core pin 31 is elastically deformed to bend the wide range of a small diameter shaft part 36, then, the stress is distributed, and consequently the stress developed at the root portion of the product forming part 39 is reduced. When the releasing agent is spray-coated onto the cavity side 12, the clearance between the pin fitting part 22 and the core pin 31 is kept in close contact through the silicone rubber 40 and the releasing agent therefore is not intruded in the clearance, and consequently the releasing agent is not sucked into the cavity with negative pressure in the cavity caused by the solidification shrinkage of the molten metal, so that the high quality cast product is obtained in which the occurrence of the blow hole, shrinkage hole, etc. are restrained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mold used for die casting, and more particularly, to a mold structure having a core pin protruding into a cavity.

  Die-casting is a highly accurate method in which a mold material that has been precisely machined is filled with a forming material, for example, a molten metal such as an aluminum alloy, at a high temperature and a high pressure, and then solidified in a short time. Since an excellent casting with a smooth casting surface can be mass-produced in a short time, it is widely used in the manufacture of automobile parts and the like that require high dimensional accuracy.

  In this die casting, a core pin incorporated in a die used in a die casting machine or the like is inserted into a pin mounting hole drilled from a cavity side of a fixed die or a movable die toward the back of the die. The mounting part to be formed and the product forming part protruding into the cavity from the tip of the insertion part are integrally formed.

  However, stress acts on the product forming part protruding from the cavity side due to shrinkage accompanying solidification of the molten metal filled in the cavity, and bending stress is concentrated and repeatedly applied to the base part of the product forming part, and is applied to the part. Cracks associated with metal fatigue occurred, and the product formed part was broken from the root part, causing the life of the core pin to be shortened.

  The temporary suspension of the casting operation accompanying the repair work to replace and restore the damaged core pin contributes to the thermal amplitude of the mold, which affects the hot water supply and causes the quality of the cast product to deteriorate and the quality to become unstable. Become.

  In particular, in the case of a core pin having a cooling hole that circulates and supplies cooling water into the core pin, cooling water leaks from the cracked part into the cavity during the fracture process, and the water leaks to vaporize into a cast product. It becomes a factor that a cast hole such as a gas hole is generated.

  As a countermeasure against this, as shown in FIG. 7, with respect to an insertion portion 106 inserted into a pin mounting hole 103 drilled from the cavity side 102 of the fixed mold or movable mold 101 forming the cavity 100 toward the back surface. Thus, in the core pin 105 in which the shaft portion of the product forming portion 107 protruding into the cavity 100 from the cavity side 102 has a small diameter, a small diameter shaft portion 108 having a smaller diameter than the insertion portion 106 is formed on the distal end side of the insertion portion 106. Then, a molten metal sealing portion 109 having an outer periphery where a gap is formed between the small diameter shaft portion 108 and the product forming portion 107 so as not to enter the molten metal between the inner surface of the pin mounting hole 103 is formed. With this configuration, when a stress acts on the product forming portion 107 due to shrinkage accompanying solidification of the molten metal filled in the cavity 100, the molten metal is sealed within the space between the inner surface of the pin mounting hole 103 and the molten metal sealing portion 109. The portion 109 can move, the wide range including the small-diameter shaft portion 108 is bent, the stress generated in the base portion of the product forming portion 107 is reduced, and metal fatigue of the portion is suppressed, so that the core pin 105 Can be extended (see, for example, Patent Document 1).

  In addition, as shown in FIG. 8, the cavity is formed from the cavity side 112 through the stepped portion 117 to the insertion portion 116 attached to the pin mounting hole 113 formed in the cavity side 112 of the fixed or movable die 111. In the core pin 115 having a small diameter shaft portion of the product forming portion 118 that protrudes into the 110, one or more annular grooves 119 are formed in the vicinity of the step portion 117 on the outer periphery of the insertion portion 116. When stress due to solidification of the molten metal filled in the product acts on the product forming portion 118, the bending stress received by the stepped portion 117 with the insertion portion 116 which is the root of the product forming portion 118 is dispersed by the groove 119, A core pin 115 for preventing breakage due to metal fatigue of a portion is known (see, for example, Patent Document 2).

Japanese Utility Model Publication No. 3-126268 Japanese Utility Model Publication No. 63-189462

  According to Patent Document 1, by forming the small-diameter shaft portion 108 and the molten metal sealing portion 109 on the distal end side of the insertion portion 106, the small-diameter shaft portion is applied when stress associated with the solidification shrinkage of the molten metal acts on the product forming portion 107. A wide range including 108 is deflected, the stress generated in the base portion of the product forming portion 107 is reduced, the metal fatigue of the portion is suppressed, and the life of the core pin 105 can be extended.

  However, the molten metal filled in the cavity 100 is formed from a gap formed between the inner peripheral surface of the pin mounting hole 103 and the outer peripheral surface of the molten metal sealing portion 109 and promoted by a wide range of bending including the small diameter shaft portion 108. The inner periphery of the pin mounting hole 103 is also caused by the negative pressure in the cavity 100 generated by the contraction when the solidifies, and also in the vacuum die casting by the negative pressure in the cavity 100 by artificial suction performed before casting. Gas existing between the surface and the outer peripheral surface of the insertion portion 106 of the core pin 105, the small diameter shaft portion 108, and the molten metal sealing portion 109 is sucked to the cavity 100 side. For this reason, there is a concern that the degree of vacuum in the cavity 100 is lowered, and casting defects such as cast holes and shrinkage occur in the cast product. This problem is great in vacuum die casting.

  Further, the cavity of the fixed or movable mold 101 is formed from a gap formed between the inner peripheral surface of the pin mounting hole 103 and the outer peripheral surface of the molten metal sealing portion 109 and promoted by a wide range of bending including the small diameter shaft portion 108. When the mold release agent spray-coated on the side 102 enters and stays in the gap formed by the pin mounting hole 103 and the small-diameter shaft portion 108, the molten metal filled in the cavity 100 is solidified as it shrinks. Due to the generated negative pressure in the cavity 100 and also in the vacuum die casting, the negative pressure in the cavity 100 due to artificial suction performed before casting also causes the inner peripheral surface of the pin mounting hole 103 and the molten metal sealing portion 109 to The release agent that has entered and stayed between the outer peripheral surface is sucked toward the cavity 100 from the gap between the pin mounting hole 103 and the molten metal sealing portion 109, and the cavity 1 Release agent which is sucked into the 0 is the factor of evil water. In addition, the mold release agent sucked into the cavity 100 is rapidly vaporized, and there is a concern that gas defects such as a cast hole and shrinkage, a molten metal, a hot water boundary, and the like may occur in a cast product.

  Further, when the clearance between the inner peripheral surface of the pin mounting hole 103 and the outer peripheral surface of the molten metal sealing portion 109 is increased by a wide range of deflection including the small-diameter shaft portion 108, the molten metal filled in the cavity 100 is separated from the gap. From the inner peripheral surface of the pin mounting hole 103 to the outer peripheral surface of the small-diameter shaft portion 108 and the molten metal sealing portion 109 and stay and solidify. Due to this staying solidification, when the stress accompanying the solidification shrinkage of the molten metal acts on the product forming portion 107, a wide range including the small diameter shaft portion 108 does not bend, and therefore, the stress generated at the root portion of the product forming portion 107 is reduced. Thus, the metal fatigue of the portion cannot be suppressed and the life of the core pin 105 cannot be extended.

  Similarly, according to Patent Document 2, from the gap formed between the inner peripheral surface of the pin mounting hole 113 and the outer peripheral surface of the insertion portion 116 and promoted by a wide range of bending including the groove 119, the cavity 110 enters the cavity 110. The pin mounting hole 113 is caused by the negative pressure in the cavity 110 generated by the shrinkage of the filled molten metal as it solidifies, and also in the vacuum die casting by the negative pressure in the cavity 110 by artificial suction performed before casting. The gas existing between the inner peripheral surface of the inner peripheral surface and the insertion portion 116 of the core pin 115 and the outer peripheral surface of the groove 119 is sucked to the cavity 110 side. For this reason, there is a concern that the degree of vacuum in the cavity 110 is reduced, and gas defects such as cast holes and shrinkage, molten metal, and a hot water boundary are generated in the cast product.

  In addition, spray coating was applied to the cavity side 112 of the fixed mold or movable mold 111 from a slight gap formed in the fitting portion between the pin mounting hole 113 and the insertion portion 116 and promoted by a wide range of bending including the groove 119. When the mold release agent enters and stays in the gap formed by the pin mounting hole 113 and the groove 119, vacuum die casting is further performed by the negative pressure in the cavity 110 due to the solidification shrinkage of the molten metal filled in the cavity 110. In this case, the accumulated release agent is sucked from the fitting portion between the pin mounting hole 113 and the insertion portion 116 to the cavity 110 side even by the negative pressure in the cavity 110 due to artificial suction performed before casting. The mold release agent sucked into the cavity 110 becomes a factor of the hot water. In addition, there is a concern that gas defects such as a cast hole and shrinkage, a molten metal, a hot water boundary, and the like may occur in a cast product as the release agent sucked into the cavity 110 is vaporized.

  Accordingly, an object of the present invention made in view of such points is to provide gas intrusion between the pin mounting hole and the core pin and gas defects such as cast holes and shrinkage caused by the release agent, hot water bath, hot water boundary, etc. An object of the present invention is to provide a mold structure provided with a core pin that suppresses occurrence and ensures the quality of a cast product, and is excellent in durability and can avoid damage such as breakage of the core pin over a long period of time.

  The invention of a mold structure provided with a core pin according to claim 1, which achieves the above object, comprises a mold structure provided with a core pin provided in a fixed mold or a movable mold and projecting into a cavity. A pin mounting hole having a pin fitting portion that is drilled in a fixed type or a movable type and has a tip opening portion opened to the cavity side, and a fitting insertion shaft portion that can be fitted into the pin fitting portion from the fitting insertion shaft portion. A molten metal sealing portion that is fitted to the tip end portion of the pin fitting portion via a small-diameter small-diameter shaft portion is integrally formed and inserted into the pin mounting hole, and the molten metal sealing of the insertion portion Formed on the outer periphery of the small-diameter shaft portion by the core pin integrally formed with the product forming portion that is continuously formed in the portion and protrudes from the cavity side into the cavity, and the shaft-inserting portion, the small-diameter shaft portion, and the molten metal sealing portion Between the annular recess and the inner peripheral surface of the pin fitting portion of the pin mounting hole Characterized in that a filled elastic member.

  According to a second aspect of the present invention, in the mold structure including the core pin of the first aspect, the pin mounting hole has a diameter larger than that of the pin fitting portion, and a step portion is provided in the pin fitting portion. The core pin includes an insertion portion that is continuously formed and opens at the back of the mold, and the core pin is continuously formed on the insertion shaft portion via a step portion that can contact the step portion, and is fitted into the insertion portion. A base portion to be inserted is provided.

  The invention of a mold structure having a core pin according to claim 3, which achieves the above object, is provided in a mold structure having a core pin provided in a fixed mold or a movable mold and protruding into a cavity. Pin mounting hole with sleeve fitting part drilled in fixed type or movable type and with tip part opening to cavity side, and pin fitting to insert into sleeve fitting part and tip part open to cavity And a molten metal seal that is fitted to the tip end portion of the pin fitting portion via a small diameter shaft portion having a smaller diameter than the fitting insertion shaft portion. And a product forming portion that is continuously formed on the insertion portion inserted into the pin mounting hole and the molten metal sealing portion of the insertion portion and protrudes into the cavity from the cavity side. A core pin, the insertion shaft portion and the small diameter shaft portion, Characterized in that an elastic member is filled between the inner peripheral surface of the pin engaging portion of the annular recess and the sleeve is formed on the outer periphery of the small diameter shaft portion by the Yufutome portion.

  According to a fourth aspect of the present invention, in the mold structure having the core pin of the third aspect, the pin mounting hole has a diameter larger than that of the pin fitting portion and a step portion is provided in the pin fitting portion. The sleeve includes an insertion portion that is continuously formed and opens to the back surface of the mold, and the sleeve includes a flange that can come into contact with the step portion while the proximal end of the pin fitting portion reaches the insertion portion. Has a base portion that is continuously formed through a stepped portion that can come into contact with the flange of the sleeve and is fitted into the insertion portion.

  According to a fifth aspect of the present invention, in the mold structure provided with the core pin of the third or fourth aspect, at least the cavity side is provided between the outer peripheral surface of the sleeve and the sleeve fitting portion in the pin mounting hole. The heat insulating layer is formed by closing and providing a gap.

  A sixth aspect of the present invention is the mold structure having the core pin according to any one of the first to fifth aspects, wherein the core pin is cooled over at least a small-diameter shaft portion on which an elastic member is mounted. A cooling hole for circulating and supplying water is formed.

  According to a seventh aspect of the present invention, in the mold structure including the core pin according to any one of the first to sixth aspects, the elastic member is silicon rubber.

  According to the first aspect of the present invention, when the molten metal filled in the cavity of the mold is solidified, if stress accompanying shrinkage due to solidification of the molten metal acts on the product forming portion of the core pin, the pin of the pin mounting hole The core pin in which the fitting insertion shaft portion and the molten metal sealing portion are fitted to and supported by the fitting portion is elastically deformed while the elastic member is elastically deformed. The stress generated at the root portion is reduced, metal fatigue is suppressed, and breakage such as breakage of the core pin can be avoided over a long period of time.

  On the other hand, between the annular recess formed on the outer periphery of the small diameter shaft portion by the shaft fitting insertion portion, the small diameter shaft portion and the molten metal sealing portion of the core pin, and the inner surface of the pin fitting portion of the pin mounting hole, Because it is held in close contact with an elastic member, there is no gas between the inner peripheral surface of the pin mounting hole and the outer peripheral surface of the core pin. In the solidification shrinkage of the molten metal and vacuum die casting, negative pressure is generated in the cavity due to artificial suction performed before casting, so that the gas existing between the pin mounting hole and the core pin is A high-quality cast product with reduced gas defects can be obtained by effectively avoiding problems such as the vacuum inside the cavity being lowered and the cavity inside the cavity being reduced, causing defects and shrinkage in the cast product. It is done.

  In addition, when spraying a release agent on each cavity side of the fixed and movable molds that are opened, the space between the inner peripheral surface of the pin fitting portion of the pin mounting hole and the outer peripheral surface of the core pin is elastic. Solidification and shrinkage of the molten metal filled in the cavity without being intruded between the inner peripheral surface of the pin mounting hole and the outer peripheral surface of the core pin by being held in close contact with the member, In vacuum die casting, even if negative pressure is generated in the cavity due to artificial suction performed before casting, the mold release agent that has entered the space between the pin mounting hole and the core pin, which has been a concern in the past, remains in the cavity. High quality that can effectively avoid defects such as casting voids, shrinkage, molten metal, and hot water boundaries in the cast product, and suppresses the occurrence of gas defects, unstable strength and poor hot water. The cast product can be obtained.

  According to the invention of claim 2, the pin mounting hole has a diameter larger than that of the pin fitting portion, the pin fitting portion is continuously formed through the stepped portion, and has an insertion portion that opens to the back surface. The insertion portion is provided with a base portion that is continuously inserted into the insertion portion via a step portion that can contact the step portion of the pin attachment hole, and the core pin is inserted into the pin attachment hole from the back side. When the stepped portion comes into contact with the stepped portion of the pin mounting hole, the fitting insertion shaft portion and the molten metal sealing portion can be easily and reliably held at the mounting positions fitted to the pin fitting portion.

  According to the invention of claim 3, when the melt filled in the cavity of the mold is solidified, if the stress due to the solidification shrinkage of the melt acts on the product forming portion of the core pin, the inner surface of the pin fitting portion of the sleeve The elastic member interposed between the core pin and the core pin is elastically deformed, and the wide area of the small-diameter shaft is deflected, the stress is dispersed and the stress generated at the base part of the product forming part is reduced, so that metal fatigue is suppressed and long-term It is possible to avoid breakage such as breakage of the core pin.

  On the other hand, a sleeve is inserted into the sleeve fitting portion of the pin mounting hole, and the inner peripheral surface of the pin fitting portion of the sleeve and the outer peripheral surface of the core pin are held in close contact with each other through an elastic member. Therefore, there is no gas between the pin mounting hole and the sleeve, and between the inner peripheral surface of the pin fitting portion of the sleeve and the outer peripheral surface of the core pin, which has been a concern in the past. In the solidification shrinkage of the molten metal filled in the vacuum and vacuum die casting, the gas existing between the pin mounting hole and the core pin is generated by the negative pressure generated in the cavity due to the artificial suction performed before casting. As a result, the vacuum inside the cavity is reduced and the degree of vacuum in the cavity decreases, which can effectively avoid defects such as casting holes and shrinkage in the cast product, resulting in gas defects, strength instability and poor hot water. High quality casting products with reduced It is.

  In addition, when spraying a release agent to each cavity side of the fixed mold and the movable mold that are opened, an elastic member is provided between the inner peripheral surface of the pin fitting portion of the sleeve and the outer peripheral surface of the core pin. In the cavity due to the solidification and shrinkage of the molten metal filled in the cavity without vacuum, and in the vacuum die casting, the mold is held in close contact with each other and the mold release agent does not enter. Even if negative pressure is generated in the mold, the release agent that has entered the gap between the pin mounting hole and the core pin, which has been a concern in the past, is sucked into the cavity and cast into the cast product. Thus, a high-quality cast product in which occurrence of gas defects, strength instability, poor hot water and the like is suppressed can be obtained.

  According to the invention of claim 4, the pin mounting hole has an insertion portion that is larger in diameter than the pin fitting portion and is continuously formed through the step portion in the pin fitting portion, and is open to the back surface of the mold, and is provided at the proximal end of the sleeve. A core pin step is provided by providing a flange that reaches the insertion portion and can contact the step portion, and a core pin is inserted into the insertion portion through the step portion that can contact the flange of the sleeve. The contact portion of the core pin is brought into contact with the flange of the sleeve, so that the insertion insertion shaft portion and the molten metal sealing portion of the core pin are respectively attached and held at the setting positions set by fitting into the pin fitting portions of the sleeve, and the sleeve The inner peripheral surface of the pin fitting portion and the outer peripheral surface of the core pin are in close contact with each other through an elastic member. By inserting the integrally inserted core pin and sleeve from the back side, the flange is connected to the pin mounting hole. While contacting the step, the sleeve is a sleeve It can be easily and reliably attached held in mounting position set are inserted into engaging portion. In addition, by periodically replacing the sleeve or the sleeve and the core pin, the inner peripheral surface of the pin fitting portion of the sleeve, the outer peripheral surface of the molten metal sealing portion of the core pin, and the sleeve fitting portion of the pin mounting hole The promotion of the gap between the inner peripheral surface and the outer peripheral surface of the sleeve is suppressed, and casting can always be performed with an appropriate gap.

  According to the invention of claim 5, at least the cavity side is closed between the outer peripheral surface of the sleeve and the sleeve fitting portion in the pin mounting hole to form a heat insulating layer by providing a gap, whereby the thermal expansion of the elastic member And the elastic member can be prevented from appearing toward the cavity due to thermal expansion.

  According to the invention of claim 6, by forming a cooling hole in the core pin for circulating and supplying cooling water to at least the small diameter shaft portion on which the elastic member is mounted, the small diameter shaft portion is supplied by circulating and supplying the cooling water. Cooling the elastic member located on the outer periphery of the metal can suppress the heat damage and thermal deterioration of the elastic member, improve the durability, and accurately prevent the elastic member from appearing on the cavity side due to thermal expansion can do.

  According to the invention of claim 7, the above-mentioned object can be reliably achieved by using silicon rubber which is excellent in heat resistance and elastically deformable as the elastic member.

  Embodiments of a mold structure having core pins according to the present invention will be described below with reference to the drawings.

(First embodiment)
A first embodiment of a mold structure having a core pin according to the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic explanatory diagram of a die casting machine. The die casting machine 1 includes a fixed platen 3 and a movable platen 4 arranged on a base frame 2. A fixed mold 11 is provided on the fixed plate 3, and a movable mold 15 is provided on the movable plate 4 so as to face the fixed mold 11, and a molding space is formed by the cavity side 12 of the fixed mold 11 and the cavity side 16 of the movable mold 15. The mold 10 for forming the cavity 20 is configured. A sleeve 5 communicates with the fixed mold 11, and a molten metal such as aluminum is injected into the cavity 20.

  The sleeve 5 is provided with a plunger 6 for injecting the molten metal injected from the pouring port 5a into the cavity 20 of the mold 10 for press-fitting. The plunger 6 is composed of a plunger tip 6a that slides in the sleeve 5 and a plunger rod 6b that is provided integrally with the plunger tip 6a. The plunger tip 6a moves in the sleeve 5 by expansion and contraction of the piston rod 7a of the injection cylinder 7. Reciprocates. In FIG. 1, reference numeral 8 denotes a mold clamping cylinder that moves the movable platen 4 toward and away from the fixed platen 3 along the tie bar 9.

  Although not shown, the mold is moved forward between the mold-opened fixed mold 11 and the movable mold 15 to spray the mold release agent on the cavity sides 12 and 16 of the fixed mold 11 and the movable mold 15. An agent spray cassette and an air blow device for uniforming the release agent applied by applying air blow to the cavity sides 12 and 16 to which the release agent is applied are provided.

  As shown in FIG. 2 and an enlarged view of part A in FIG. 2, a pin mounting hole 21 is formed in the fixed die 11, and a core pin 31 is inserted and attached to the pin mounting hole 21. ing.

  The pin mounting hole 21 drilled in the fixed mold 11 penetrates from the cavity side 12 side to the back surface 13 side of the fixed mold 11, and the distal end portion 22 a opens in the cavity side 12 and is a pin fitting having the same diameter. A connecting portion 23 that is continuous with the pin fitting portion 22 and has a slightly larger diameter than the pin fitting portion 22, continues to the connecting portion 23 via a stepped portion 24, and has a base end 25 a that opens at the back surface 13. A large-diameter insertion portion 25 is continuously formed on the same axis.

  On the other hand, the core pin 31 is formed with an insertion portion 32 that is inserted into the pin fitting portion 22 of the pin mounting hole 21 formed in the fixed mold 11 and has a smaller diameter than the insertion portion 32. Thus, a product forming portion 39 protruding into the cavity 20 from the cavity side 12 of the fixed mold 11 is integrally formed.

  The insertion portion 32 to be attached to the pin attachment hole 21 includes a base 33 that can be inserted into the insertion portion 25 of the pin attachment hole 21 from the back surface 13 side and can be inserted into the insertion portion 25 of the pin attachment hole 21. A fitting insertion shaft portion 35 that is continuous via a step portion 34 that can come into contact with the step portion 24 and can be fitted to the pin fitting portion 22, a small-diameter shaft portion 36 having a smaller diameter than the fitting insertion shaft portion 35, and a pin A molten metal sealing portion 37 that is fitted to the distal end portion 22 a of the fitting portion 22 is continuously formed coaxially and continuously, and a product forming portion 39 having a smaller diameter than the molten metal sealing portion 37 is continuously formed in the molten metal sealing portion 37. ing.

  An elastic member excellent in heat resistance in an annular recess 38 formed on the outer periphery of the small-diameter shaft portion 36 by the fitting insertion shaft portion 35, the small-diameter shaft portion 36, and the molten metal sealing portion 37, which is cylindrical in the present embodiment. The silicon rubber 40 is fitted.

  The core pin 31 formed in this manner is inserted into the pin mounting hole 21 from the base end 25a side of the insertion portion 25, so that the step portion 34 abuts on the step portion 24 of the pin attachment hole 21 and moves. In addition to being restricted, the fitting insertion shaft portion 35 and the molten metal sealing portion 37 are each fitted to the pin fitting portion 22 to be easily and reliably attached and held at a preset attachment position. On the other hand, silicon rubber 40 fitted in the recess 38 is filled between the small diameter shaft portion 36 and the pin mounting hole 21, and the inner peripheral surface of the pin fitting portion 22 of the pin mounting hole 21 and the outer periphery of the core pin 31. The surface is tightly sealed with silicon rubber 40 interposed.

  Next, the casting process by the die casting machine 1 configured as described above will be described based on the casting process diagram shown in FIG.

  In a mold open state in which the fixed plate 3 and the movable plate 4 are separated from each other by the mold clamping cylinder 8 and the fixed die 11 and the movable die 15 are separated, the release agent spray cassette is placed between the fixed die 11 and the movable die 15. The release agent is spray applied to the cavity sides 12 and 16 of the fixed mold 11 and the movable mold 15 by being advanced. Further, air blow is applied to each of the cavity sides 12 and 16 to which the release agent is applied by an air blowing device, so that the release agent applied by spraying is made uniform, moisture in the release agent is evaporated, and excess release is performed. The agent is blown away (release agent application step S1).

  In spraying the release agent, the inner peripheral surface of the pin fitting portion 22 of the pin mounting hole 21 and the outer peripheral surface of the core pin 31 through the silicon rubber 40 fitted in the recess 38 of the core pin 31. Are kept in close contact with each other, and the release agent is prevented from entering between the inner peripheral surface of the pin mounting hole 21 and the outer peripheral surface of the core pin 31.

  Next, after the release agent spray cassette is retracted from between the fixed mold 11 and the movable mold 15 of the mold 10, the plunger tip 6a is retracted by contraction of the piston rod 7a of the injection cylinder 7, and the plunger tip 6a Is put on standby at a standby position located behind the pouring port 5a of the sleeve 5 (plunger retracting step S2).

  Next, the movable platen 4 is moved close to the fixed platen 3 by the mold clamping cylinder 8 or the like, and the fixed die 11 and the movable die 15 are combined to perform mold clamping (die clamping step S3).

  In a state in which the mold 10 is clamped by the mold clamping cylinder 8 or the like, a predetermined amount of molten metal is poured into the sleeve 5 from the pouring port 5a from a heat retaining furnace (not shown) with a ladle or the like (pouring step S4). Next, the plunger tip 6a is advanced together with the plunger rod 6b by extension of the piston rod 7a of the injection cylinder 7. At this time, in the case of vacuum die casting, the gas in the cavity 20 is sucked out of the cavity 20 by a vacuum pump or a vacuum tank (not shown). In this gas suction, the inner peripheral surface of the pin fitting portion 22 of the pin mounting hole 21 and the outer peripheral surface of the core pin 31 are brought into close contact with each other through the silicon rubber 40 fitted in the recess 38 of the core pin 31. Since it is held, excessive suction of the gas and the release agent from between the inner peripheral surface of the pin mounting hole 21 and the outer peripheral surface of the core pin 31 is prevented.

  Then, the molten metal in the sleeve 5 is injected and filled into the cavity 20 of the mold 10 by the advancement of the plunger tip 6a (injection step S5).

  Next, the molten metal filled in the cavity 20 of the mold 10 is solidified in a state where the plunger chip 6a is maintained at the advanced position and the molten metal filled in the cavity 20 is held in a pressurized state (melted solidification step S6). ).

  In the molten metal solidification step S6, when stress accompanying solidification shrinkage of the molten metal filled in the cavity 20 acts on the product forming portion 39 of the core pin 31, it fits with the inner peripheral surface of the pin fitting portion 22 of the pin mounting hole 21. The core pin 31 in which the insertion shaft portion 35 and the molten metal sealing portion 37 are fitted and supported is between the inner peripheral surface of the pin fitting portion 22 of the pin mounting hole 21 and the outer peripheral surface of the core pin 31. A wide range of the small-diameter shaft portion 36 is deflected while elastically deforming the intervening silicon rubber 40, the stress is dispersed, the stress generated in the base portion of the product forming portion 39 is reduced, and the metal fatigue of the portion is reduced.

  After the molten metal in the cavity 20 is solidified with the plunger tip 6a held at the forward position, the movable platen 4 is separated from the fixed platen 3 by the mold clamping cylinder 8 or the like, and the fixed die 11 and the movable die 15 are separated from each other. Opening (mold opening step S7) and carrying out the cast product (product taking out step S8).

  According to the present embodiment configured as described above, the core pin 31 is inserted into the pin mounting hole 21 from the proximal end 25a side of the insertion portion 25, that is, the back surface 13 side, so that the stepped portion 34 is pin-attached. The movement of the core pin 31 is restricted by contacting the stepped portion 24 of the hole 21, and the fitting shaft portion 35 and the molten metal sealing portion 37 are fitted to the inner peripheral surface of the pin fitting portion 22 to attach the pin. The inner peripheral surface of the pin fitting portion 22 of the pin mounting hole 21 and the outer peripheral surface of the core pin 31 are held in close contact with each other through the silicon rubber 40 excellent in heat resistance and elastic deformation.

  Accordingly, when the molten metal filled in the cavity 20 of the mold 10 is solidified in the molten metal solidifying step S6, if stress due to shrinkage due to the solidification of the molten metal acts on the product forming portion 39 of the core pin 31, The core pin 31 in which the insertion shaft portion 35 and the molten metal sealing portion 37 are fitted and supported on the inner peripheral surface of the pin fitting portion 22 of the attachment hole 21 is formed on the pin fitting portion 22 of the pin attachment hole 21. A wide range of the small-diameter shaft portion 36 is bent while elastically deforming the silicon rubber 40 interposed between the inner peripheral surface and the outer peripheral surface of the core pin 31. Stress is dispersed by a wide range of bending of the small-diameter shaft portion 36, the stress generated at the base portion of the product forming portion 39 is reduced, metal fatigue is suppressed, and excellent durability can be ensured for a long time. Breakage such as breakage of the child pin 31 can be avoided. Since the damage to the core pin 31 is suppressed in this way, the temporary stop of the casting operation required for the restoration work of replacement and replacement of the core pin 31 can be suppressed, the thermal amplitude of the mold can be suppressed, and stable hot water can be obtained. The surroundings can be secured, the quality of the cast product can be secured, the quality of the cast product becomes uniform, and the reliability of the cast product is improved.

  On the other hand, in the release agent application step S1, when the release agent is spray-applied to the cavity sides 12 and 16 of the fixed mold 11 and the movable mold 15 that are opened, they are fitted into the recesses 38 of the core pin 31. The inner surface of the pin fitting portion 22 of the pin mounting hole 21 and the outer peripheral surface of the core pin 31 are held in close contact by the silicon rubber 40 with the silicon rubber 40 interposed therebetween. Intrusion of the mold release agent between the peripheral surface and the outer peripheral surface of the core pin 31 is avoided, and negative pressure is generated in the cavity 20 due to the solidification contraction of the molten metal filled in the cavity 20 in the molten metal solidifying step S6. Even if it occurs, the mold release agent that has entered between the pin mounting hole and the core pin, which has been a concern in the past, is sucked into the cavity 20 to cause casting defects, shrinkage, hot water, and hot water boundaries in the cast product. Effectively avoids malfunctions that cause gas Recessed, high-quality cast product of the intensity instability and hot water around the occurrence of failure or the like is suppressed is obtained.

  Further, in vacuum die casting, when the gas in the cavity 20 is sucked out of the cavity 20 in the injection step S5, the pin fitting of the pin mounting hole 21 by the silicon rubber 40 fitted in the recess 38 of the core pin 31 is performed. Since the inner peripheral surface of the joint portion 22 and the outer peripheral surface of the core pin 31 are held in close contact with the silicon rubber 40 interposed therebetween, the inner peripheral surface of the pin mounting hole 21 and the outer periphery of the core pin 31 are retained. Over-suction of gas and release agent from the surface is avoided, and negative pressure is generated in the cavity 20 due to artificial suction performed before casting, which has been a concern in the past. The gas and mold release agent existing between the core pin 31 and the core pin 31 are sucked into the cavity 20 and the degree of vacuum in the cavity 20 is lowered, and a cast product, shrinkage, hot water, hot water boundary, etc. are generated in the cast product. There is a problem such as To be avoided, gas defects, strength unstable and high-quality cast products which occurrence of the hot water around defect is suppressed may be obtained.

  In the present embodiment, the mold 10 in which the core pin 31 is provided in the fixed mold 11 has been described as an example. However, the present invention can be applied to the case in which the core pin is provided in the movable mold 15.

(Second Embodiment)
A second embodiment of the die core pin according to the present invention will be described with reference to FIGS. 5 and FIG. 6, parts corresponding to those in FIG. 1 to FIG. 4 are given the same reference numerals as in FIG. 1 to FIG. .

  As shown in FIG. 5 and an enlarged view of part B in FIG. 5, a pin mounting hole 51 is formed in the fixed mold 11, and a core pin 71 is interposed in the pin mounting hole 51 with a sleeve 61 interposed. Is attached.

  The pin mounting hole 51 drilled in the fixed mold 11 penetrates from the cavity side 12 side to the back surface 13 side of the fixed mold 11, and the distal end portion 52 a is opened in the cavity side 12 and the sleeve fits continuously. A large-diameter insertion portion 54 is formed coaxially with the portion 52 and the sleeve fitting portion 52 through a stepped portion 53 and having a base end 54a open on the back surface 13.

  The sleeve 61 has a cylindrical pin fitting portion 62 in which the tip end portion 52a of the sleeve fitting portion 52 of the pin mounting hole 51 and the tip portion 62a are fitted to the sleeve fitting portion 52 in a corresponding manner. A flange 63 that can contact the stepped portion 53 is formed while the proximal end of the portion 62 reaches the insertion portion 54.

  Further, the outer peripheral surface excluding the distal end portion 62a and the base end of the pin fitting portion 62 of the sleeve 61 has a small diameter, and at least the cavity side between the outer peripheral surface of the sleeve 61 and the sleeve fitting portion 52 in the pin mounting hole 51. The heat insulation layer is formed by closing the 12 side and providing a gap 90.

  On the other hand, the core pin 71 has an insertion portion 72 attached to the insertion portion 54 of the pin mounting hole 51 formed in the fixed mold 11 and the pin fitting portion 62 of the sleeve 61, and a smaller diameter than the insertion portion 72. A product forming portion 79 that is formed and protrudes into the cavity 20 from the tip end portion 62 a of the pin fitting portion 62 of the sleeve 61 is integrally formed.

  The insertion portion 72 attached to the insertion portion 54 of the pin attachment hole 51 and the pin fitting portion 62 of the sleeve 61 is a base portion that can be inserted into the insertion portion 54 of the pin attachment hole 51 from the back surface 13 side. 73, a fitting insertion shaft portion 75 which is continuous to the base portion 73 via a stepped portion 74 capable of contacting the flange 63 of the sleeve 61 and can be fitted to the pin fitting portion 62 of the sleeve 61, and the fitting insertion shaft. A small-diameter shaft portion 76 having a smaller diameter than the portion 75 and a molten metal sealing portion 77 fitted to the tip end portion 62 a of the pin fitting portion 62 are integrally and continuously formed on the same axis, and the molten metal sealing portion 77 is connected to the molten metal sealing portion 77. A product forming portion 79 having a diameter smaller than 77 is continuously formed. A cooling hole 80 for circulating and supplying cooling water is formed in the core pin 71 from the insertion portion 72 to the product forming portion 79.

  A cylindrical silicon rubber 40 having excellent heat resistance and elastic deformation characteristics is formed in an annular recess 78 formed on the outer periphery of the small diameter shaft portion 76 by the insertion shaft portion 75, the small diameter shaft portion 76, and the molten metal sealing portion 77. Is fitted.

  The core pin 71 formed in this way is inserted into the pin fitting portion 62 of the sleeve 61 from the flange 63 side, whereby the stepped portion 74 abuts against the flange 63 and the movement is restricted, and the insertion is performed. The shaft portion 75 and the molten metal sealing portion 77 are respectively fitted in the pin fitting portion 62 and are attached and held at preset attachment positions, and the silicon rubber 40 fitted in the recess 78 is the small diameter shaft portion 76. The inner peripheral surface of the pin fitting portion 62 of the sleeve 61 and the outer peripheral surface of the core pin 71 are in close contact with each other via the silicon rubber 40.

  The core pin 71 and the sleeve 61, which are integrally fitted with the silicon rubber 40 interposed therebetween, are inserted into the pin mounting hole 51 formed in the fixed mold 11 from the base end 54a side, that is, the back surface 13 side. As a result, the flange 63 of the sleeve 61 abuts on the stepped portion 53 of the pin mounting hole 51 to restrict the movement, and the pin fitting portion 62 is fitted to the sleeve fitting portion 52 so that it can be easily and surely set. Attached and held. For this attachment, the core pin 71 is integrally coupled to the sleeve 61 with the silicon rubber 40 interposed therebetween, and the sleeve 61 is inserted into the pin mounting hole 51 so that the silicon rubber 40 is protected by the sleeve 61 and the core pin 71. Thus, the silicon rubber 40 can be easily attached to the pin attachment hole 51 while maintaining a good state without being damaged.

  Further, cooling water is circulated and supplied to the cooling holes 80 formed in the core pin 71 by the cooling water supply means to be cooled.

  According to the present embodiment configured as described above, in the molten metal solidification step S6, when the molten metal filled in the cavity 20 of the mold 10 is solidified, the stress due to the solidification shrinkage of the molten metal is the product of the core pin 71. When acting on the forming portion 79, the fitting insertion shaft portion 75 and the molten metal sealing portion 77 are formed on the inner peripheral surface of the pin fitting portion 62 of the sleeve 61 fitted and held in the pin mounting hole 51 formed in the fixed mold 11. The core pin 71 fitted and supported has a small-diameter shaft portion while elastically deforming the silicon rubber 40 interposed between the inner peripheral surface of the pin fitting portion 62 of the sleeve 61 and the outer peripheral surface of the core pin 71. A wide area of 76 is deflected, stress is dispersed and stress generated at the base portion of the product forming portion 79 is reduced, metal fatigue of the portion is suppressed, excellent durability can be secured, and the core can be secured over a long period of time. Breakage such as broken pins 71 can be avoided and the core Corruption down 71 is suppressed. Therefore, it is possible to suppress the temporary stop of the casting work required for replacement and restoration of the core pin 71, to suppress the heat amplitude of the mold, to ensure a stable hot water supply, and to further supply the cooling water circulated to the cooling hole 80 to the cavity 20 The quality of the cast product is uniform and the reliability of the cast product is improved.

  On the other hand, in the release agent application step S1, when the release agent is spray-applied to the cavity sides 12 and 16 of the fixed mold 11 and the movable mold 15 that are opened, they are fitted into the recesses 78 of the core pin 71. The inner peripheral surface of the pin fitting portion 62 of the sleeve 61 and the outer peripheral surface of the core pin 71 are held in close contact with each other through the silicon rubber 40, and the inner peripheral surface of the pin fitting portion 62 and the middle The mold release agent is prevented from entering between the outer peripheral surfaces of the child pins 71. As a result, in the molten metal solidification step S6, even if a negative pressure is generated in the cavity 20 due to the solidification shrinkage of the molten metal filled in the cavity 20, it has entered between the pin mounting hole and the core pin, which have been concerned in the past. The mold release agent is sucked into the cavity 20 to effectively avoid defects such as casting defects, shrinkage, molten metal, and hot water boundaries in the cast product, such as gas defects, strength instability and poor hot water. A high-quality cast product with reduced generation can be obtained.

  In vacuum die casting, when the gas in the cavity 20 is sucked out of the cavity 20 in the injection step S5, the pin of the sleeve 61 is interposed via the silicon rubber 40 fitted in the recess 78 of the core pin 71. Since the inner peripheral surface of the fitting portion 62 and the outer peripheral surface of the core pin 71 are held in close contact with each other, from between the inner peripheral surface of the pin fitting portion 62 and the outer peripheral surface of the core pin 71. Gas and mold release agent over-suction is avoided, and the vacuum in the cavity 20, which has been a concern in the past, is reduced, effectively causing defects such as castholes, shrinkage, molten metal, and hot water boundaries in the cast product. As a result, it is possible to obtain a high-quality cast product in which the occurrence of gas defects, strength instability and poor hot water is suppressed.

  Further, by periodically replacing the sleeve 61 or the sleeve 61 and the core pin 71, the inner peripheral surface of the pin fitting portion 62 of the sleeve 61, the outer peripheral surface of the molten metal sealing portion 77 of the core pin 71, and a pin mounting hole. The gap between the inner peripheral surface of the sleeve fitting portion 52 and the outer peripheral surface of the sleeve 61 is suppressed, and casting can be performed with a proper gap always provided.

  Further, a cooling hole 80 for circulating and supplying cooling water is formed in the core pin 71 from the insertion portion 72 to the product forming portion 79, that is, at least to the small diameter shaft portion 76 to which the silicon rubber 40 is attached. Therefore, the silicon rubber 40 located on the outer periphery of the small-diameter shaft portion 76 is cooled by the circulation supply of the cooling water, the heat damage and thermal deterioration of the silicon rubber 40 can be suppressed, and the durability can be improved. The appearance of the silicon rubber 40 to the cavity 20 side due to the expansion can be accurately prevented.

  Further, at least the cavity side 12 side is closed between the outer peripheral surface of the sleeve 61 and the sleeve fitting portion 52 in the pin mounting hole 51 so as to correspond to the fitting position of the silicon rubber 40 on the inner peripheral surface. Since the heat insulating layer is formed, the effect of suppressing the thermal expansion of the silicon rubber 40 is enhanced, and the appearance of the silicon rubber 40 on the cavity 20 side due to the thermal expansion is accurately prevented.

As shown in FIG. 6, since the gap is held between the insertion portion 54 of the pin mounting hole 51 and the base portion 73 of the core pin 71, the heat insulation is further improved.
In the present embodiment, the mold 10 in which the core pin 71 is provided in the fixed die 11 has been described as an example.

  The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, a cooling hole can be formed in the core pin 31 in the first embodiment, and cooling water can be circulated and cooled by the cooling water supply means, and formed in the core pin 71 in the second embodiment. The cooling hole 80 can also be omitted.

It is a schematic explanatory drawing of the die-casting machine explaining 1st Embodiment of the metal mold | die structure provided with the core pin by this invention. It is principal part sectional drawing of a metal mold | die. It is the A section enlarged view of FIG. It is a casting process figure which shows the effect | action of a die-casting machine. It is principal part sectional drawing of the metal mold | die explaining 2nd Embodiment of the metal mold | die structure provided with the core pin by this invention. It is the B section enlarged view of FIG. It is principal part sectional drawing of the metal mold | die which shows the outline | summary of the conventional core pin for metal mold | dies. It is principal part sectional drawing of the metal mold | die which shows the outline | summary of the conventional core pin for metal mold | dies.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die-casting machine 10 Mold 11 Fixed mold 12 Cavity side 13 Back surface 15 Movable mold 16 Cavity side 20 Cavity 21 Pin mounting hole 22 Pin fitting part 24 Step part 25 Insertion part 25a Base end 31 Core pin 32 Insertion part 33 Base part 34 Step part 35 Insertion shaft part 36 Small diameter shaft part 37 Molten metal sealing part 38 Concave part 39 Product formation part 40 Silicon rubber (elastic member)
51 Pin mounting hole 52 Sleeve fitting portion 52a Tip portion 53 Step portion 54 Insertion portion 54a Base end 61 Sleeve 62 Pin fitting portion 62a Tip portion 63 Flange 71 Core pin 72 Insertion portion 73 Base portion 74 Step portion 75 Insertion shaft Part 76 small diameter shaft part 77 molten metal sealing part 78 concave part 79 product forming part S1 mold release agent application process S2 plunger retraction process S3 mold clamping process S4 pouring process S5 injection process S6 molten metal coagulation process S7 mold opening process S8 product removal process

Claims (7)

In a mold structure provided with a core pin provided in a fixed mold or a movable mold and projecting into a cavity,
A pin mounting hole having a pin fitting portion which is drilled in the fixed mold or the movable mold and has a tip portion opened to the cavity side;
A molten metal sealing portion that is fitted to the tip end portion of the pin fitting portion is integrally formed on the fitting shaft portion that can be fitted to the pin fitting portion via a small-diameter shaft portion that is smaller in diameter than the fitting insertion shaft portion. A core pin integrally formed with an insertion portion to be inserted into the pin mounting hole and a product forming portion which is continuously formed in the molten metal sealing portion of the insertion portion and protrudes into the cavity from the cavity side;
Elasticity filled between the annular recess formed on the outer periphery of the small-diameter shaft portion by the shaft-inserting portion, the small-diameter shaft portion, and the molten metal sealing portion and the inner peripheral surface of the pin fitting portion of the pin mounting hole And a die structure having a core pin. The pin mounting hole has an insertion portion that is larger in diameter than the pin fitting portion and is continuously formed through a step portion in the pin fitting portion and opens to the back surface of the mold,
The said core pin was provided with the base part which is continuously formed in the said insertion shaft part via the step part which can contact | abut to the said step part, and is inserted and inserted in the said insertion part. Mold structure with core pin. In a mold structure provided with a core pin provided in a fixed mold or a movable mold and projecting into a cavity,
A pin mounting hole provided with a sleeve fitting portion that is drilled in the fixed type or the movable type and has a distal end portion that opens to the cavity side;
A sleeve having a pin fitting portion inserted into the sleeve fitting portion and having a tip portion opened to the cavity;
A molten metal sealing portion that is fitted to the tip end portion of the pin fitting portion is integrally formed on the fitting shaft portion that can be fitted to the pin fitting portion via a small-diameter shaft portion that is smaller in diameter than the fitting insertion shaft portion. A core pin integrally formed with an insertion portion to be inserted into the pin mounting hole and a product forming portion which is continuously formed in the molten metal sealing portion of the insertion portion and protrudes into the cavity from the cavity side;
An elastic member filled between the annular recess formed on the outer periphery of the small-diameter shaft portion by the fitting insertion shaft portion, the small-diameter shaft portion, and the molten metal sealing portion, and the inner peripheral surface of the pin fitting portion of the sleeve; A mold structure with a core pin, characterized by comprising The pin mounting hole has an insertion portion that is larger in diameter than the pin fitting portion and is continuously formed through a step portion in the pin fitting portion and opens to the back surface of the mold,
The sleeve includes a flange that can come into contact with the step portion while the proximal end of the pin fitting portion reaches the insertion portion,
4. The core pin according to claim 3, wherein the core pin includes a base portion that is continuously formed through a step portion that can come into contact with the flange of the sleeve and is fitted into the insertion portion. Mold structure provided.   5. The core according to claim 3, wherein at least the cavity side is closed between the outer peripheral surface of the sleeve and the sleeve fitting portion in the pin mounting hole to form a heat insulating layer. Mold structure with pins.   6. A cooling hole for circulating and supplying cooling water to at least the small diameter shaft portion to which the elastic member is mounted is formed in the core pin. Mold structure with core pin described.   The mold structure having a core pin according to any one of claims 1 to 6, wherein the elastic member is silicon rubber.

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