JP5644311B2 - Casting apparatus and casting method - Google Patents

Description

  The present invention relates to a casting apparatus. In particular, the present invention relates to a so-called die casting machine that casts a product by injecting molten metal (molten metal) into a mold by applying pressure. In this specification, the die casting machine is referred to as a “casting apparatus”.

  A casting apparatus typically includes a mold, a sleeve for injecting molten metal into the mold, and a plunger. In such a casting apparatus, the molten metal temporarily stored in the sleeve is pushed out by the plunger, and the molten metal is injected into the mold.

  As the casting is repeated, the outer peripheral surface of the plunger slides and wears with the inner periphery of the sleeve. As wear progresses, a gap is formed between the sleeve and the plunger, and the molten metal may leak. Therefore, it is necessary to replace the plunger before the abrasion proceeds. Normally, the plunger is composed of a plunger tip corresponding to a piston and a rod that supports the plunger tip at its rear end. However, for the sake of simplicity in this specification, the term “plunger” is referred to as “plunger tip”. It is used as a term meaning.

  Non-Patent Document 1 discloses a technique for disposing a plunger once (or several times) as one technique for actively replacing the plunger (plunger tip) early. The casting apparatus disclosed in Non-Patent Document 1 is configured to push the rear end of the plunger with a rod after inserting the plunger (plunger tip) into the sleeve. The plunger and rod are not mechanically connected. Therefore, there is no need to connect the plunger and the rod, and when the rod is retracted after pushing the rod and injecting the molten metal in the sleeve, only the rod retracts and the plunger remains at the tip of the sleeve. Since the plunger adheres to the molten metal remaining at the tip of the sleeve, it can be taken out from the mold together with the design part (the part other than the product among the cast-formed objects). That is, the work cost required for exchanging the plunger can be reduced.

  Moreover, when making a plunger disposable, many plungers are required. In the technique disclosed in Non-Patent Document 1, a plunger casting cavity is provided in a mold separately from a product casting cavity, so that a plunger is simultaneously manufactured for each product casting. Since the technology of Non-Patent Document 1 also casts a plunger every time a product is cast, it is possible to prepare a sufficient number of plungers to be disposable each time. “Disposable” means that it is not necessary for the next product molding, and includes reuse as a molten metal. That is, since the plunger is made of the same material as the cast product, it can be reused as a molten metal together with the plan portion.

Japan Society of Invention and Innovation Technical Report 2010-501363

  In the casting apparatus of Non-Patent Document 1, the plunger that has been used can be reused as a molten metal, but it is better that there is less waste generated at the time of molding a single product. The inventor further developed the technique of Non-Patent Document 1 and created a technique for making the disposable part smaller than the conventional one.

  As described above, the advantage of making the plunger disposable is to prevent wear due to sliding with the sleeve. That is, it is not necessary to make the whole plunger (plunger tip) disposable, and it is only necessary that the portion sliding with the sleeve can be made disposable. The technology disclosed in the present specification realizes a casting apparatus that solves the above-described problems by disposing a ring-shaped member that slides on the sleeve, in addition to the plunger main body, in the sleeve.

  One embodiment of a casting apparatus disclosed herein comprises a mold, a sleeve, a plunger, and a plunger ring. As described above, the sleeve is a component for temporarily storing molten metal to be sent to the mold. The plunger is reciprocally disposed in the sleeve. The plunger (plunger tip) has a rod connected to the rear end, and is configured to advance / retreat by an actuator via the rod. A convex portion for loosely fitting the plunger ring is formed on the distal end surface of the plunger. The plunger ring is shaped so that the outer periphery thereof is in contact with the inner peripheral surface of the sleeve, and is arranged in front of the plunger in the sleeve. The plunger ring is loosely fitted to the convex portion, but is not fixed (connected) to the plunger. That is, when the plunger moves forward, the plunger ring is pushed forward by the plunger while loosely fitting to the convex portion. After the molten metal is pushed out of the sleeve, the plunger ring disengages from the plunger tip as the plunger retracts. Note that the “convex portion” is substantially equivalent to a notch that makes a round of the plunger in the circumferential direction at the edge of the distal end of the plunger when attention is paid to the shoulder portion.

  The plunger ring is a part for preventing the molten metal from escaping to the rear of the plunger. That is, the plunger ring is a part for sealing a gap between the plunger (plunger tip) and the inner peripheral surface of the sleeve. Therefore, the above-mentioned “shape in contact with the inner peripheral surface of the sleeve” means a shape in contact with the entire inner peripheral surface of the sleeve without a gap. Since the plunger ring has a shape that is in contact with the inner peripheral surface of the sleeve without a gap, the plunger ring can be stabilized only by being fitted into the sleeve without a plunger. The casting apparatus described above typically completes preparation for casting by first inserting the plunger ring into the sleeve and then inserting the plunger to a position where the plunger ring is loosely fitted into the convex portion.

  In the above casting apparatus, the entire plunger (plunger tip) is not made disposable, but only the ring-shaped plunger ring that can be made smaller than the whole plunger is made disposable. Less is enough.

  In the casting apparatus, when the plunger is retreated after the molten metal is injected by the plunger, the plunger ring is fixed to the molten metal (that is, the plan portion) remaining at the tip of the sleeve and is detached from the convex portion of the plunger. The used plunger ring is taken out from the casting apparatus together with the plan portion. Therefore, it does not take time to take out the plunger ring.

  The above-described “free fitting” means that the inner diameter of the plunger ring is equal to or larger than the outer diameter of the convex portion. In other words, there is a predetermined clearance (for example, about 1 mm to 10 mm) between the inner diameter of the plunger ring and the outer diameter of the convex portion. In other words, the plunger ring is fitted (freely fitted) into the convex portion so as to be movable in the radial direction with respect to the plunger. With such a configuration, the plunger ring is passively adapted to the sleeve inner peripheral surface even when the shaft is displaced (eccentric) between the sleeve and the plunger during injection molding. Can move (i.e. align). The clearance can smoothly inject molten metal even when an eccentricity occurs between the sleeve and the plunger.

  In another embodiment of the casting apparatus disclosed in the present specification, the convex portion of the plunger tip surface may be gradually reduced in diameter from the root toward the tip. If there is a clearance between the plunger ring and the projection, the molten metal enters the clearance when the plunger is advanced. The molten metal in the clearance is solidified to become a plan part. If the convex portion is gradually reduced in diameter, when the plunger is retracted, the plunger is easily detached from the solidified plan portion.

  Further, as described above, the plunger ring is fixed to the molten metal (plan portion) remaining at the tip of the sleeve. At this time, it is preferable that the inner diameter of the plunger ring is gradually increased from the plunger front end side toward the rear end side so that the plunger ring is not easily detached from the design portion. Alternatively, a groove may be formed on the inner peripheral surface of the plunger ring. When the plunger is advanced, the molten metal enters the enlarged diameter portion in the former case and enters the groove in the latter case. When the molten metal that has entered the expanded diameter portion (or groove) is solidified, a so-called “prevention” function is exhibited, and the plunger ring is difficult to be detached from the design portion. The groove is preferably a groove that is not open on the distal end side of the plunger. Such shaped grooves provide a better “clamping” function.

The configuration in which the plunger ring is made disposable and the plunger including the convex portion is provided as a permanent (permanent) component of the apparatus is provided by providing a space through which the cooling medium passes inside the convex portion.
There is a further effect. That is, after the plunger is advanced and the molten metal is injected, the molten metal that contacts the front surface (top surface) of the convex portion (the molten metal remaining at the tip of the sleeve) can be cooled to promote solidification.

  The technology disclosed in this specification also provides a new casting method. This casting method is a casting method in which molten metal supplied to a sleeve is injected by a plunger and injected into a mold. This method includes the following steps. (1) A step of disposing a plunger ring in which the outer periphery is in contact with the inner peripheral surface of the sleeve and a plunger having a convex portion loosely fitted to the plunger ring at the tip. More specifically, both are placed in the sleeve so that the plunger ring is placed in front of the plunger (sleeve). (2) A step of supplying molten metal into the sleeve. (3) A step of advancing the plunger to inject molten metal into the mold. (4) A step of retracting the plunger by detaching the plunger ring from the plunger while the plunger ring is fixed to the molten metal remaining in the sleeve tip space. In the above casting method, the plunger ring that slides on the inner peripheral surface of the sleeve is made disposable for each casting. This casting method has the same effect as the casting apparatus described above.

The typical sectional view of the casting device of the 1st example is shown. Fig. 3 shows a schematic cross-sectional view of a plunger ring and a plunger. The figure which shows operation | movement of a casting apparatus (at the time of molten metal injection). The figure which shows operation | movement of a casting apparatus (at the time of die cutting). FIG. 3 shows a schematic cross-sectional view of a plunger ring and a plunger of a second embodiment.

The technical features of the embodiments described below are listed.
(Mode 1) The mold includes a cavity (ring cavity) for casting the plunger ring. According to this structure, whenever a product is cast, a plunger ring is cast simultaneously. The cast plunger ring can be used in subsequent castings. There is no need to prepare a large number of disposable plunger rings in advance.
(Mode 2) Of the two end faces of the plunger ring, the end face facing the plunger comes into contact with the front end face of the plunger without any gap when the plunger ring is loosely fitted to the convex portion. When the molten metal in the sleeve is pushed out by the plunger, it is not good that the molten metal wraps around the rear side of the plunger. According to this configuration, when the molten metal is extruded, the molten metal does not enter between the end surface of the plunger ring facing the plunger and the tip surface of the plunger. Therefore, when the molten metal is extruded, the molten metal does not go around the plunger.

(First embodiment)
The casting apparatus 2 of the first embodiment will be described with reference to the drawings. The casting apparatus 2 of the present embodiment is an apparatus (die casting machine) for casting a product by injecting molten metal (molten metal) into a mold by applying pressure. As shown in FIG. 1, the casting apparatus 2 includes, as main components, a fixed mold 4, a movable mold 6 that is in close contact with and away from the fixed mold, a sleeve 20 that is fixed to the fixed mold 4, and a sleeve. 20 includes a plunger 30 that reciprocates in the inside 20 and a plunger ring 36 that is loosely fitted to the tip of the plunger 30. The casting apparatus 2 of the present embodiment is a horizontal casting apparatus in which the sleeve 20 is provided with its longitudinal direction substantially horizontal, and the plunger 30 reciprocates in the horizontal direction in the sleeve 20. In FIG. 1, the molds 4 and 6 and the sleeve 20 are shown in cross-section for easy understanding of the embodiment, but it should be noted that the plunger 30 and the plunger ring 36 are shown in side views. The same applies to FIGS. 3 and 4.

  Both the fixed mold 4 and the movable mold 6 are alloy steel molds. The fixed mold 4 is fixed to a fixed plate (not shown). The movable mold 6 is fixed to a movable plate (not shown). As the movable platen moves, the movable mold 6 comes into close contact with / separates from the fixed mold 4. Note that bringing the molds into close contact with each other is referred to as “closing the mold”, and separating the close molds is referred to as “opening the mold”. As shown in FIG. 1, when the mold is closed (when the movable mold 6 is in close contact with the fixed mold 4), the runner 8, the product cavity 10, and the ring cavity are between the two molds 4 and 6. 12. Overflow space 14 is formed. The runner 8 is a molten metal flow path that connects the space in the sleeve 20 and the product cavity 10. The product cavity 10 is a cavity for casting a product. The ring cavity 12 is a cavity for casting the plunger ring 36. The ring cavity 12 is formed in communication with the product cavity 10. The overflow space 14 is a space for accommodating the overflowed molten metal when an amount of molten metal exceeding the capacity of the cavities 10 and 12 is supplied to the product cavity 10 and the ring cavity 12. The overflow space 14 communicates with the ring cavity 12. Therefore, when the mold is closed, the molten metal is supplied to each part of the runner 8, the product cavity 10, the ring cavity 12, and the overflow space 14 between the two molds 4 and 6 in this order. It is formed.

  The sleeve 20 is a cylindrical member made of alloy steel. In the upper part near the rear end of the sleeve 20, a melt supply hole 22 for supplying the melt into the sleeve 20 from the outside is formed. The sleeve 20 communicates with the runner 8 at the front. In the upper part of the front end of the sleeve 20, a runner hole 24 that communicates the runner 8 and the inside of the sleeve 20 is opened. “Front (backward) of the sleeve 20” means the forward (backward) direction of the plunger 30 that reciprocates.

  The plunger 30 includes a plunger tip 32 and a plunger rod 34 that supports the plunger tip 32. The plunger tip 32 is a main member for extruding the molten metal, and is a substantially columnar member made of alloy steel. The plunger tip 32 is formed to have an outer diameter smaller than the inner diameter of the sleeve 20. A convex portion 37 for loosely fitting the plunger ring 36 is provided on the distal end surface 41 of the plunger tip 32. The convex portion 37 includes a tapered portion 40 and a columnar portion 38. The tapered portion 40 is a portion that gradually decreases in diameter from the distal end surface 41 side (root side) of the plunger tip 32 toward the front. The columnar portion 38 is a columnar portion formed at the tip of the tapered portion 40. The columnar portion 38 is not reduced in diameter. The columnar portion 38 faces the space in the sleeve 20 together with the surface 36a (see FIG. 2) of the plunger ring 36, and functions as a portion for extruding the molten metal. The front surface 36 a and the back surface 36 b of the plunger ring 36 correspond to the end surface of the plunger ring 36.

  The distal end of the plunger rod 34 is connected to the rear end of the plunger tip 32 and supports the plunger tip 32. Although not shown, the rear end of the plunger rod 34 is connected to a hydraulic device (actuator) or the like that moves the plunger 30. As the plunger rod 34 moves back and forth, the plunger tip 32 reciprocates back and forth within the sleeve 20. In this specification, attention is paid to the plunger tip, and it should be noted that the term “plunger 30” means “plunger tip 32” unless otherwise specified.

  The plunger ring 36 is a ring-shaped member having an outer diameter that is substantially the same as the inner diameter of the sleeve 20 (strictly, a slightly smaller diameter). As shown in FIG. 2, the outer periphery of the plunger ring 36 is in contact with the inner peripheral surface of the sleeve 20. The plunger ring 36 is disposed in front of the plunger 30 in the sleeve 20. When the plunger 30 moves to a position in contact with the plunger ring 36, the plunger ring 36 loosely fits on the convex portion 37 (taper portion 40) as shown in FIG. The inner diameter of the center hole of the plunger ring 36 gradually increases from the front surface 36a side to the back surface 36b side of the plunger ring 36. In other words, the inner diameter of the central hole of the plunger ring 36 gradually increases from the columnar portion 38 side toward the distal end surface 41 side when the plunger ring 36 is loosely fitted to the convex portion 37. Further, the inner diameter of the central hole of the plunger ring 36 is larger than the outer diameter of the tapered portion 40. Therefore, a clearance (gap) 45 is formed between the inner wall 42 of the center hole of the plunger ring 36 and the side surface of the tapered portion 40 in a state where the plunger ring 36 is loosely fitted to the convex portion 37. That is, the plunger ring 36 is not fixed to the convex portion 37. That is, the plunger ring 36 is pushed forward by the plunger 30 while loosely fitting to the convex portion 37 when the plunger 30 moves forward, and is detached from the plunger 30 when the plunger 30 moves backward. As the plunger 30 moves forward, the molten metal is injected from the sleeve 20 to the molds 4 and 6.

  The width of the clearance 45 described above is determined in advance, for example, about 1 mm to 10 mm. The presence of the clearance 45 allows the plunger ring 36 to move in the radial direction with respect to the center line of the plunger 30 in a state where the plunger ring 36 is loosely fitted to the convex portion 37. Further, in a state where the plunger ring 36 is loosely fitted to the convex portion 37, the surface 36 a of the plunger ring 36 faces the space in the sleeve 20 together with the columnar portion 38 and functions as a portion for extruding the molten metal. On the other hand, the back surface 36 b is in close contact with the distal end surface 41 of the plunger tip 32. Therefore, even when the molten metal enters the clearance 45, the molten metal does not leak to the rear side of the plunger tip 32 through the space between the back surface 36b and the tip surface 41. Further, as described above, since the outer periphery of the plunger ring 36 and the inner peripheral surface of the sleeve 20 are in contact with each other without a gap, the molten metal in the sleeve 20 is separated from the outer periphery of the plunger ring 36 and the inner peripheral surface of the sleeve 20 during molten metal extrusion. It does not leak to the rear side of the plunger tip 32 through the gap.

  The plunger ring 36 is cast in the ring cavity 12 described above. Therefore, the plunger ring 36 is formed of the same metal (for example, aluminum) as the product. In this embodiment, the plunger ring 36 is a disposable member that is discarded every time injection molding is performed. Since the plunger tip is made of the same material as the cast product, it can be reused as a molten metal together with the plan portion. That is, “disposable” as used herein includes reusing as molten metal.

  As shown in FIG. 2, a coolant flow path 64 is formed inside the plunger tip 32. In addition, a supply path 60 and a discharge path 62 communicating with the cooling medium flow path 64 are provided inside the plunger rod 34. The supply path 60 is a flow path for supplying a cooling medium into the cooling medium flow path 64. The discharge path 62 is a flow path for discharging the cooling medium from the cooling medium flow path 64. With this configuration, when the molten metal in the sleeve 20 is pushed out by the plunger 30, the molten metal that contacts the columnar portion 38 of the convex portion 37 of the plunger tip 32 can be cooled, and solidification of the molten metal is promoted.

  In addition to the above members, the casting apparatus 2 includes a controller (not shown) for controlling the operation of the movable mold 6 and the plunger 30. Further, the casting apparatus 2 is provided with a molten metal supply device (not shown) for supplying an amount of molten metal necessary for casting the product into the sleeve 20.

  A method of casting a product using the casting apparatus 2 of the present embodiment will be described with reference to FIGS. This casting method includes a step of arranging the plunger ring 36 and the plunger 30 in the sleeve (arrangement step, see FIG. 1), a step of supplying the molten metal H into the sleeve 20 (melt supply step, see FIG. 1), and the plunger 30. 4 steps of advancing and injecting the molten metal into the dies 4 and 6 (injection step, see FIG. 3), performing die cutting and returning the plunger 30 to the retracted end (die cutting step, see FIG. 4) Divided. Hereinafter, each process will be described.

(1. Arrangement process)
As described above, the outer diameter of the plunger ring 36 is formed to be approximately the same as the inner diameter of the sleeve 20. Therefore, if the plunger ring 36 is fitted into the sleeve 20, the plunger ring 36 is stable without the plunger 30. Therefore, first, the operator fits the plunger ring 36 into the sleeve 20. Next, the controller advances the plunger 30 to a position where the plunger ring 36 is loosely fitted to the convex portion 37. That is, the plunger ring 36 is disposed in the sleeve 20 in front of the plunger 30. At this time, as shown in FIG. 1, the plunger ring 36 and the plunger 30 are located behind the molten metal supply hole 22 (backward in the plunger reciprocating movement). This position corresponds to the position where the plunger 30 is most retracted (retracted end). Thereby, the casting apparatus 2 shown in FIG. 1 is completed, and preparation for casting of the product is completed.

(2. Molten metal supply process)
As shown in FIG. 1, the controller closes the mold by operating the movable platen (the movable mold 6 is brought into close contact with the fixed mold 4), and the runner 8 is placed between the two molds 4 and 6. The product cavity 10, the ring cavity 12, and the overflow space 14 are formed. As described above, both the columnar portion 38 of the convex portion 37 of the plunger tip 32 and the surface 36 a of the plunger ring 36 are located behind the molten metal supply hole 22. In this state, the molten metal H is supplied into the sleeve 20 from the molten metal supply hole 22 by a molten metal supply device (not shown).

(3. Injection process)
Next, as shown in FIG. 3, the controller advances the plunger 30 to the advance end (position shown in FIG. 3). At this time, the plunger ring 36 is also moved forward by being pushed by the plunger 30. When the plunger 30 moves forward, the molten metal H in the sleeve 20 is pushed by the distal end surface of the plunger tip 32. The molten metal H in the sleeve 20 is injected into the product cavity 10, the ring cavity 12, and the overflow space 14 through the runner hole 24 and the runner 8. The injected molten metal H is filled in each of the product cavity 10, the ring cavity 12, and the overflow space 14. At this time, as shown in FIG. 3, a part of the molten metal H to be pushed also enters the clearance 45 between the plunger ring 36 and the convex portion 37.

  The sleeve 20 may be thermally deformed by the heat of the molten metal H supplied into the sleeve 20 in the molten metal supply step. Therefore, a displacement (eccentricity) between the center line of the sleeve 20 and the center line of the plunger 30 may occur during the extrusion of the molten metal. In this regard, in the casting apparatus 2 of the present embodiment, since the clearance 45 is formed between the plunger ring 36 and the convex portion 37, even if the eccentricity occurs, the plunger ring 36 is connected to the plunger 30. It moves in the radial direction with respect to the center line. That is, even when the sleeve 20 is eccentric, the plunger ring 36 can passively move (ie, align) according to the inner peripheral surface of the sleeve 20. Even if the clearance 45 causes an eccentricity between the sleeve 20 and the plunger 30, the molten metal H can be smoothly injected.

  When the plunger 30 is advanced to the forward end (position shown in FIG. 3), the controller in that state is in the sleeve 20, the runner 8, the product cavity 10, the ring cavity 12, the overflow space 14, and the clearance 45. It waits for predetermined time until each molten metal H of the inside solidifies. The controller supplies the cooling medium into the cooling medium flow path 64 (see FIG. 2) inside the plunger tip 32, cools the molten metal H that contacts the columnar portion 38 of the convex portion 37 of the plunger tip 32, and solidifies the molten metal H. Promote.

  As the molten metal H in the product cavity 10 solidifies, the product 50 is molded. Further, the molten plunger H in the ring cavity 12 is solidified to form a new plunger ring 52. The other portion (in the sleeve 20, in the runner 8, in the overflow space 14, in the clearance 45, etc.) solidifies the molten metal H, whereby the design part 51 is formed. The product 50, the new plunger ring 52, and the plan part 51 are integrally formed. The “plan portion 51” in the present embodiment means a portion other than the product 50 and the new plunger ring 52 in the molten metal solidified portion. Note that the molten metal H that has entered the clearance 45 also solidifies as part of the design part 51 (the locking part 53). Along with this, the plunger ring 36 used for extruding the molten metal H is fixed to the molten metal H (plan portion 51) solidified in the sleeve 20.

(4. Die cutting process)
When the predetermined time elapses and the molten metal in each part is solidified, the controller operates the movable platen to open the mold (see FIG. 4). After opening the mold (or at the same time as opening the mold), the controller advances the plunger 30 further. In this way, the plunger 30 pushes out the product 50, the plunger ring 52, and the design part 51 from the fixed mold 4.

  After the product 50, the new plunger ring 52, and the plan portion 51 are separated from the fixed mold 4, the plunger 30 is retracted to the retracted end as shown in FIG. At this time, as described above, the plunger ring 36 fixed to the design part 51 is detached from the convex part 37 of the plunger 30. Since the inner diameter of the center hole of the plunger ring 36 gradually increases from the front surface 36a side to the back surface 36b side, a portion 53 (hereinafter referred to as a solid portion) formed by solidification of the molten metal in the clearance 45 in the design portion 51. , Referred to as “locking portion 53”) exhibits a so-called “detachment prevention” function. As a result, the plunger ring 36 does not leave the design part 51 when the plunger 30 is retracted. On the other hand, since the convex portion 37 of the plunger 30 is gradually reduced in diameter from the tip surface 41 side (base side) toward the columnar portion 38 side (tip side), when the plunger 30 is retracted, the locking portion 53 is large. Resistance is not easily applied, and the plunger 30 can be easily detached from the locking portion 53. After the molding of the product is completed, the plunger ring 36 remains fixed to the design part 51, so that the plunger ring 36 is taken out of the mold together with the design part 51. That is, there is no need to take out the plunger ring 36 after use.

  When the plunger 30 is retracted to the retracted end, the product 50, the new plunger ring 52, and the design part 51 remaining in the movable mold 6 are taken out from the movable mold 6 by a predetermined carry-out device. The new plunger ring 52 is separated from the product 50 and the plan portion 51, and is used as a plunger ring that is loosely fitted to the convex portion 37 at the next and subsequent castings. Moreover, the used plunger ring 36 is melted together with the plan part 51 and reused as a molten metal.

  In the above, the casting apparatus 2 of a present Example was demonstrated. As described above, the casting apparatus 2 according to the present embodiment does not make the entire plunger tip 32 disposable, but only the plunger ring 36 having a smaller size than the plunger tip 32 is made disposable. Is less.

  Further, in the casting apparatus 2 of this embodiment, when the plunger 30 is retracted after the molten metal is injected by the plunger 30, the plunger ring 36 is fixed to the molten metal remaining at the tip of the sleeve 20 (that is, the design part 51). It separates from the 30 convex portions 37 (see FIG. 4). The used plunger ring 36 can be taken out from the casting apparatus 2 together with the design part 51. Therefore, it does not take time to take out the plunger ring 36 after casting.

  Furthermore, in the casting apparatus 2 of the present embodiment, the inner diameter of the central hole of the plunger ring 36 is equal to or larger than the outer diameter of the convex portion 37 (see FIG. 2). That is, a clearance 45 exists between the inner wall 42 of the center hole of the plunger ring 36 and the convex portion 37. Therefore, the plunger ring 36 is movable in the radial direction with respect to the center line of the plunger 30 while loosely fitting to the convex portion 37. Therefore, even when eccentricity occurs between the sleeve 20 and the plunger 30 during injection molding, the plunger ring 36 can passively move (ie, align) according to the inner peripheral surface of the sleeve 20. it can. Even if the clearance 45 causes an eccentricity between the sleeve 20 and the plunger 30, the molten metal H can be smoothly injected.

  Furthermore, the convex part 37 is gradually diameter-reduced toward the front-end | tip (columnar part 38) from the base side. Moreover, since the clearance 45 exists between the plunger ring 36 and the convex part 37, when the plunger 30 is advanced, the molten metal H enters the clearance 45 (see FIG. 3). The molten metal in the clearance 45 is solidified to form the plan part 51. According to this configuration, since the convex portion 37 is gradually reduced in diameter, a large resistance is not applied between the design portion 51 and the convex portion 37 formed in the clearance 45 when the plunger 30 is retracted. The plunger 30 can be easily detached.

  The plunger ring 36 is a portion formed by solidification of the molten metal that has entered the clearance 45 because the inner diameter of the central hole gradually increases from the front surface 36a side to the back surface 36b side. The stop part 53 exhibits a so-called “prevention” function. As a result, the plunger ring 36 does not leave the design portion 51 when the plunger 30 is retracted.

  In the present embodiment, a cooling medium flow path 64 is provided in the plunger tip 32 to cool the molten metal H in contact with the columnar portion 38 of the convex portion 37 and promote solidification thereof. The molten metal H in the sleeve 20 is easily solidified early, and the productivity is improved.

(Second embodiment)
With reference to FIG. 5, the casting apparatus of 2nd Example is demonstrated centering on a different point from 1st Example. The casting apparatus of the second embodiment is different from the first embodiment in that a groove 44 is formed in the inner wall 42 of the center hole of the plunger ring 36. As shown in FIG. 5, the groove 44 opens toward the convex portion 37, but does not open on the front surface 36 a and the back surface 36 b of the plunger ring 36. The groove 44 of this embodiment is formed together when the plunger ring is cast in the ring cavity 12.

  The case where the plunger ring 36 is loosely fitted to the convex portion 37 to cast the product and the plunger ring is the same as in the case of the casting apparatus 2 of the first embodiment. In the casting apparatus of the second embodiment, when the plunger is advanced to push the molten metal H in the sleeve 20, the molten metal H enters not only the clearance 45 but also the groove 44. The locking portion 53 formed by the solidification of the molten metal H in both the groove 44 and the clearance 45 can more effectively exhibit the function of “preventing slipping”. That is, the plunger ring 36 is firmly fixed to the design part 51. As a result, when the plunger 30 is retracted, the plunger ring 36 is less likely to be detached from the design part 51.

Modifications of the above embodiments are listed below.
(1) In each of the above-described embodiments, the plunger ring 36 is made of the same metal (for example, aluminum) as the product cast by the mold. Instead of this, the plunger ring 36 may be made of a metal different from the product, such as an alloy steel. In that case, the plunger ring 36 may be reusable without being disposable.
(2) In each of the above-described embodiments, an example in which the plunger ring 36 after molten metal extrusion is fixed to the design portion 51 and is detached from the convex portion 37 while being fixed to the design portion 51 when the plunger 30 is retracted. did. Instead of this, the plunger ring 36 after molten metal extrusion may not be fixed to the design part 51. In that case, the plunger ring 36 may drop from the convex portion 37 when the plunger 30 moves backward.
(3) In each of the above-described embodiments, an example in which the mold is provided with the ring cavity 12 and the plunger ring 36 is cast at the same time each time the product is cast has been described. Alternatively, the ring cavity 12 may not be provided in the mold, and the plunger ring 36 may be made of a mold other than the mold or a non-casting manufacturing method.
(4) In each of the above embodiments, the example in which the plunger ring 36 is first fitted into the sleeve 20 and then the plunger 30 is advanced to the position where the plunger ring 36 is loosely fitted to the convex portion 37 has been described. Instead, the plunger ring 36 is loosely fitted in advance to the convex portion 37 of the plunger 30 before being inserted into the sleeve 20, and the plunger 30 with the plunger ring 36 being loosely fitted is inserted into the sleeve 20. Then you may move forward.
(5) In the second embodiment, the central hole of the plunger ring 36 is tapered and has a groove 44. The plunger ring 36 may have a structure that has a cylindrical center hole that is not tapered, and a groove is formed on the inner wall of the center hole. If the groove is formed, the “prevention of slipping” effect can be obtained even if the center hole is not tapered.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: casting apparatus, 4: fixed mold, 6: movable mold, 8: runner, 10: product cavity, 12: ring cavity, 14: overflow space, 20: sleeve, 22: molten metal supply hole, 24: hot water Passage hole, 30: plunger, 32: plunger tip, 34: plunger rod,
36: Plunger ring, 36a: Front surface, 36b: Back surface, 37: Convex part, 38: Columnar part, 40: Tapered part, 41: Tip surface, 42: Inner wall, 44: Groove, 45: Clearance, 50: Product, 51 : Plan part, 52: New plunger ring, 53: Locking part, 60: Supply path, 62: Discharge path, 64: Coolant flow path, H: Molten metal

Claims (6)

Mold,
A sleeve for temporarily storing molten metal to be sent to the mold,
A convex portion is formed on the distal end surface, and a plunger that is reciprocally disposed in the sleeve;
A plunger ring which is placed in front of the plunger in the sleeve and whose outer periphery is in contact with the inner peripheral surface of the sleeve;
With
The plunger ring is fitted on the convex portion so that there is a clearance between the inner diameter of the plunger ring and the outer diameter of the convex portion, and when the plunger moves forward , the plunger ring can move in the radial direction with respect to the plunger. A casting apparatus, wherein the casting apparatus moves forward by being pushed by the plunger while being fitted to the convex portion, and is detached from the plunger when the plunger moves backward.   The casting apparatus according to claim 1, wherein the convex portion is gradually reduced in diameter from the root toward the tip.   The casting apparatus according to claim 1 or 2, wherein the inner diameter of the plunger ring is gradually increased from the front end side of the plunger toward the rear end side.   The casting apparatus according to claim 1, wherein a groove is formed on an inner peripheral surface of the plunger ring.   The casting apparatus according to any one of claims 1 to 4, wherein a space for passing a cooling medium is formed inside the convex portion. A casting method in which molten metal supplied to a sleeve is injected into a mold by a plunger,
A plunger ring whose outer periphery is in contact with the inner peripheral surface of the sleeve, and a plunger having a convex portion inserted through the plunger ring at the tip , the plunger ring having an inner diameter of the plunger ring and an outer surface of the convex portion. Disposing the plunger within the sleeve so that there is a clearance between the diameters, and when the plunger moves forward, the convex portion is fitted so that the plunger can move in the radial direction; ,
Supplying molten metal into the sleeve;
Injecting molten metal into the mold by advancing the plunger;
With the plunger ring fixed to the molten metal remaining in the sleeve tip space, the plunger ring is detached from the plunger and the plunger is retracted;
A casting method comprising:

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