JP2017087240A - Molding device, plunger tip and molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molding device, a plunger tip and a molding method capable of providing a molding product of an extremely high quality, by reducing gas in a metal mold space to the minimum, by discharging even gas of existing a little in front of the plunger tip.SOLUTION: A vent part 24 is constituted for discharging gas in a clearance between a cylindrical sleeve 7 for communicating with a molding metal mold 2 and a plunger tip 9 of a plunger 8 reciprocatably slidably provided in the axial direction in this sleeve 7. The vent part 24 is constituted of an outer peripheral surface 26a of a tip vent part 26 of the plunger tip 9 and an inner peripheral surface 7a of the sleeve 7, and is constituted of an annular ring-shaped first vent part 25 for setting a diameter difference (r) between the outer peripheral surface 26a and the inner peripheral surface 7a to 0.02-0.50 mm and a second vent 27 constituted wider than the first vent 25 so that ventilation resistance of the gas becomes small toward the rear in the axial direction from this first vent 25.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a molding apparatus used for casting of light metals such as aluminum and molding of resin, a plunger tip used in the molding apparatus, and a molding method, and in particular, by quickly discharging a gas present in front of the plunger chip. The present invention relates to a molding apparatus, a plunger tip, and a molding method capable of obtaining a high-quality molded product.

  For example, in casting by die casting, gas such as air and water vapor existing in a molding die enters the cavity by molten metal pressurized by a plunger. It is known that defects such as a nest of a die-cast molded product can be reduced by forming the cavity gas as much as possible to the outside. As a technique for reducing defects in a die cast product, a vacuum die casting method in which die casting is performed in a state where a cavity is decompressed is widely used.

  In the vacuum die casting method, there is a problem that equipment and maintenance for increasing the degree of vacuum of the cavity are required and the cost increases. As a method not using the vacuum die casting method, providing a vent portion for discharging gas to a molding die is performed. Generally, the cavity is provided with an overflow portion for accumulating molten metal, and a vent portion for discharging gas is formed so as to communicate with the overflow portion. The vent portion is usually provided with a predetermined gap on the opposite side of the overflow portion from the cavity, and the gap is gradually narrowed away from the cavity. By adopting such a vent structure, gas is discharged and molten metal is not blown out by casting pressure.

  However, since such a vent portion becomes narrower as it goes away from the cavity, the exhaust resistance of gas is large. Further, the molten metal enters the vent portion and solidifies, thereby inhibiting gas discharge. For this reason, it cannot be said that gas is exhausted sufficiently by the conventional vent part, and accordingly, it is difficult to improve the quality of the die cast product.

  In Patent Document 1, a wedge-shaped notch that narrows toward the rear is provided at the tip of an extrusion pin for extruding a molded product formed in a cavity, and gas is discharged by providing a groove behind the notch. An extrusion pin is described. Patent Document 2 describes a method of discharging gas by providing a similar notch at the tip of an extrusion pin that pushes out a runner connected to a cavity. As disclosed in Patent Document 3, a method of discharging gas by a chill vent provided in a cavity is also known.

Japanese Patent No. 4085182 Japanese Patent No. 5431780 JP 2003-132656 A

  At the time of molding, after the molten metal is supplied to the sleeve of the pressurizing mechanism that loads the molten material, the plunger moves forward in the sleeve, and the mold space is closed by the plunger tip. The gas of the runner and the gas of the cavity are exhausted at a vent portion provided in the runner and the cavity.

  On the other hand, gas is also present near the front of the plunger tip in the closed mold space. It is difficult to exhaust the gas existing in front of the plunger tip at a vent portion provided in the runner or the cavity as in Patent Documents 1 to 3. As shown in FIG. 10, a method is known in which a gas discharge groove 101 is provided in a part of the upper side of the sleeve 100 and the gas existing in front of the plunger tip 102 is discharged from the gas discharge groove 101 to the outside of the mold space. ing.

  Specifically, the molten metal supplied from the supply port 103 accumulates below the sleeve 100, and in this state, the plunger tip 102 advances from the left side to the right side in FIG. When the plunger tip 102 advances in a position corresponding to the gas discharge groove 101, the gas existing in front of the plunger tip 102 is discharged through the gas discharge groove 101. When the plunger tip 102 further advances and advances to the front of the gas discharge groove 101, the gas discharge groove 101 is closed and the mold space is closed.

  At this point, much of the gas present in front of the plunger tip 102 has been exhausted, but there is a slight amount of gas. That is, when the gas discharge groove 101 is closed, there is no gas escape route that exists slightly in front of the plunger tip 102. This slight amount of gas has become a hindrance factor and has not led to a higher quality die-cast product.

  Therefore, in view of the problems of the prior art, the present invention obtains an extremely high-quality molded product by discharging even a slight amount of gas in front of the plunger tip and reducing the gas in the mold space to a minimum. It is an object of the present invention to provide a molding apparatus, a plunger tip, and a molding method that can perform the above-described process.

  The molding apparatus of the present invention includes a molding die that constitutes a cavity filled with a molten material, and a material supply mechanism that loads the molten material into the cavity, and the material supply mechanism is attached to the molding die. A cylindrical sleeve that communicates with the plunger and a plunger that is slidable in the axial direction in the sleeve and pressurizes the molten material supplied into the sleeve toward the cavity. In the molding apparatus provided with a plunger tip at the tip, a vent portion for discharging gas along the axial direction is configured in a gap between the plunger tip and the sleeve into which the plunger tip is inserted. The vent portion is composed of the outer peripheral surface of the tip of the plunger tip and the inner peripheral surface of the sleeve, and the diameter difference between the outer peripheral surface of the tip and the inner peripheral surface. An annular first vent having a diameter of 0.02 to 0.50 mm, and a second vent that is wider than the first vent so that the gas ventilation resistance decreases from the first vent toward the rear in the axial direction. It is characterized by having.

  According to the present invention, the vent portion constituted by the gap between the plunger tip and the sleeve is constituted by the tip outer peripheral surface of the plunger tip and the inner peripheral surface of the sleeve, and the tip outer peripheral surface and the inner peripheral surface An annular first vent having a diameter difference of 0.02 to 0.50 mm, and a larger vent than the first vent so that the gas ventilation resistance decreases from the first vent toward the rear in the axial direction. A second vent. The vent portion having the first vent and the second vent communicates directly with the mold space in front of the plunger tip. The vent portion is thin so that the first vent close to the mold space is thin, and the second vent that communicates with the first vent and is far from the mold space reduces the gas ventilation resistance. In the vent section, the first vent that once narrows the gas discharge passage increases the gas discharge speed, and the second vent that is wider than the first vent passes through the first vent. The gas flow resistance after the gas is reduced. Thereby, even after the mold space in front of the plunger tip that presses the molten material is closed, the gas existing slightly in front of the plunger tip can be discharged, and the gas in the mold space is reduced to the minimum. be able to.

  It is preferable that the axial length of the first vent is 5 to 30 mm. If the length of the first vent is 5 to 30 mm, an appropriate ventilation resistance can be obtained, and blowing of the molten material can be prevented.

The maximum depth h in the radial direction of the second vent preferably satisfies the following formula 1 and is 5.00 mm or less.
((R / 2) × 2) <h <((r / 2) × 10) (Formula 1)
Where r is the difference in diameter between the outer peripheral surface of the tip of the plunger tip and the inner peripheral surface of the sleeve.
In this case, it is possible to effectively reduce the gas ventilation resistance after passing through the first vent, and to prevent the molten material from blowing out.

  The second vent includes, for example, a plurality of chamfered portions extending in the axial direction formed at a predetermined interval in the circumferential direction on the peripheral surface of the plunger tip, and a plurality of inner peripheral surfaces of the sleeve. What is necessary is just to consist of this exhaust passage. In this case, it is possible to obtain an appropriate ventilation resistance of the gas after passing through the first vent.

The width M of each exhaust passage preferably satisfies the following formula 2. In this case, the gas after passing through the first vent can be quickly discharged.
1 mm ≦ M <(SQRT (t ² −D × t) × 2) mm (Formula 2)
Where D is the diameter of the plunger tip and t is the maximum depth of the chamfered portion of the plunger tip.

  The plurality of exhaust passages may be configured at equal intervals in the circumferential direction of the plunger tip. In this case, there is no bias in the discharge state of the gas after passing through the first vent, and the gas can be introduced uniformly along the periphery of the first vent.

  You may form the groove | channel over the axial direction full length of a said 1st vent in the front-end | tip outer peripheral surface of the said plunger tip. In this case, it is possible to increase the gas flow rate while maintaining appropriate gas flow resistance in the first vent.

  The plunger tip of the present invention is a plunger tip used in the molding apparatus of the present invention, and a tip vent portion constituting the first vent with the inner peripheral surface of the sleeve, and the tip vent portion. And a rear vent portion that constitutes the second vent between the sleeve and the inner peripheral surface of the sleeve.

  The plunger tip of the present invention includes a tip vent portion that constitutes a first vent with the inner peripheral surface of the sleeve, and an axially rearward portion of the tip vent portion that is formed continuously with the inner peripheral surface of the sleeve. And a rear vent portion constituting the second vent, and the vent portion can be constituted between the sleeve and the sleeve. The vent portion having the first vent and the second vent communicates directly with the mold space in front of the plunger tip. The vent portion is thin so that the first vent close to the mold space is thin, and the second vent that communicates with the first vent and is far from the mold space reduces the gas ventilation resistance. In the vent section, the first vent that once narrows the gas discharge passage increases the gas discharge speed, and the second vent that is wider than the first vent passes through the first vent. The gas flow resistance after the gas is reduced. Thereby, even after the mold space in front of the plunger tip that presses the molten material is closed, the gas existing slightly in front of the plunger tip can be discharged, and the gas in the mold space is reduced to the minimum. be able to.

  The molding method according to the present invention is a molding method in which molding is performed using the molding apparatus according to the present invention, wherein the gas discharge rate is increased by the first vent and the first vent is passed through the first vent. It is characterized by reducing the gas flow resistance afterwards.

  In the molding apparatus used in the molding method of the present invention, the vent portion constituted by the gap between the plunger tip and the sleeve is constituted by the tip outer peripheral surface of the plunger tip and the inner peripheral surface of the sleeve, and the tip outer peripheral surface. And an annular first vent having a diameter difference between 0.02 and 0.50 mm, and the first vent so that the gas ventilation resistance decreases from the first vent toward the rear in the axial direction. And a second vent configured to be wider. The vent portion having the first vent and the second vent communicates directly with the mold space in front of the plunger tip. The vent portion is thin so that the first vent close to the mold space is thin, and the second vent that communicates with the first vent and is far from the mold space reduces the gas ventilation resistance. In the vent section, the first vent that once narrows the gas discharge passage increases the gas discharge speed, and the second vent that is wider than the first vent passes through the first vent. The gas flow resistance after the gas is reduced. Thereby, even after the mold space in front of the plunger tip that presses the molten material is closed, the gas existing slightly in front of the plunger tip can be discharged, and the gas in the mold space is reduced to the minimum. be able to.

  According to the present invention, even after the mold space in front of the plunger tip that presses the molten material is closed, the gas existing slightly in front of the plunger tip can be discharged, and the gas in the mold space is minimized. Since it can be reduced to the limit, an extremely high quality molded product can be obtained.

It is a schematic cross section of the shaping | molding apparatus which concerns on one Embodiment of this invention. It is sectional drawing of the metal mold | die for shaping | molding. It is principal part sectional drawing of the state in which the plunger is inserted in the sleeve. It is a front view of a plunger tip. It is a perspective view of a plunger tip. It is a principal part expanded sectional view of the state by which the plunger tip is inserted by the sleeve. (A) is the photograph of the die-cast molded product shape | molded using the plunger chip | tip of this embodiment, (b) is the photograph of the die-cast molded product shape | molded using the conventional plunger chip | tip. It is a perspective view which shows the example which provided the groove | channel in the front-end | tip outer peripheral surface of a plunger chip | tip. (A)-(b) is a side view which shows the modification of a plunger tip. It is sectional drawing explaining the method which provides a gas discharge groove in a sleeve and discharges gas out of a mold space.

  An embodiment of the present invention will be described by taking die casting as an example. FIG. 1 is a schematic cross-sectional view of a die casting apparatus (molding apparatus) 1 according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a molding die 2. This die casting apparatus 1 is a casting apparatus for obtaining a die-cast molded product, and pressurizes the molten metal to the mold 3 for forming the cavity 3 filled with aluminum (hereinafter referred to as molten metal) which is a molten material. And a pressurizing mechanism 4 for filling in a state.

  A plurality of pin holes 5 are provided in the molding die 2, and cylindrical extrusion pins 6 are fitted into the pin holes 5. The pressurizing mechanism 4 is provided with a cylindrical sleeve 7 communicating with the molding die 2, and is capable of reciprocating in the axial direction within the sleeve 7. And a plunger 8 for pressurization. A conventional gas discharge groove 31 is formed in the vicinity of the molten metal supply port 10 formed in the sleeve 7. A substantially cylindrical plunger tip 9 that contacts the molten metal is provided at the tip of the plunger 8. Although the diameter of the plunger tip 9 of this embodiment is about 50 to 80 mm, the diameter is not limited. The molten metal introduced into the supply path 12 between the molding die 2 and the pressurizing mechanism 4 is filled into the cavity 3 by the pressure of the plunger 8.

  The molding die 2 is composed of a main mold 13 and a nest 14 fitted into the main mold 13. The main mold 13 includes a fixed main mold 15 and a movable main mold 16. A fixed side insert 17 is fitted into the fixed main mold 15, and a movable side insert 18 is fitted into the movable main mold 16. The nesting 14 includes a fixed nesting 17 and a movable nesting 18 that can be moved back and forth with respect to the fixed nesting 17 and can be changed between a mold closed state and a mold open state. The fixed side insert 17 and the movable side insert 18 constitute a cavity 3, and a gate, a runner, and the like serving as a runner are formed in the molding die 2.

  After the molding die 2 is closed, the molten metal is poured into the supply path 12 from the supply port 10, the plunger 8 of the pressurizing mechanism 4 moves forward, and the molten metal supplied to the supply path 12 is pressurized and molded. It is transferred to the metal mold 2. The molten metal flows into the cavity 3 through a runner, a gate, etc. and is filled. Thereafter, the molten metal is solidified in the cavity 3 to form a molded product. After the molding die 2 is opened, the solidified molded product is pushed out by the extrusion pin 6 and released from the molding die 2.

  FIG. 3 is a cross-sectional view of the main part in a state where the plunger 8 is inserted into the sleeve 7. FIG. 4 is a front view of the plunger tip 9, and FIG. 5 is a perspective view of the plunger tip 9. FIG. 6 is an enlarged cross-sectional view of a main part in a state where the plunger tip 9 is inserted into the sleeve 7. The plunger 8 has a substantially cylindrical plunger tip 9 that contacts the molten metal and an axially extending rod 11 fixed to the plunger tip 9. The plunger tip 9 is composed of a tip portion 20 having a contact surface that comes into contact with the molten metal, and a fixing portion 21 on the rear side in the axial direction of the tip portion 20. A raised portion 22 is formed on the contact surface of the tip portion 20. The fixing portion 21 has a smaller diameter than the tip portion 20, and a grip plane portion 23 is formed on a part of the peripheral surface thereof.

  In the gap between the plunger tip 9 and the sleeve 7, a vent portion 24 that discharges gas along the axial direction is configured. The tip portion 20 of the plunger tip 9 is formed continuously with the tip vent portion 26 constituting the first vent 25 between the inner peripheral surface 7a of the sleeve 7 and the tip vent portion 26 toward the rear in the axial direction. A rear vent portion 28 constituting a second vent 27 is provided between the inner peripheral surface 7 a of the sleeve 7.

  The vent portion 24 includes an annular first vent 25 including an outer peripheral surface 26 a of the tip vent portion 26 (tip outer peripheral surface of the plunger tip 9) and an inner peripheral surface 7 a of the sleeve 7, and the first vent 25. And a second vent 27 that is wider than the first vent 25 so that the gas ventilation resistance decreases in the axially rearward direction. Both the first vent 25 and the second vent 27 are formed in the gap between the tip portion 20 of the plunger tip 9 and the sleeve 7. The tip vent portion 26 on the inner peripheral side of the first vent 25 has a cylindrical shape.

  The diameter difference r between the outer peripheral surface 26a of the tip vent portion 26 and the inner peripheral surface 7a of the sleeve 7 is preferably 0.02 to 0.50 mm, and more preferably 0.05 to 0.35 mm. Accordingly, the gap interval r / 2 of the first vent 25 is preferably 0.01 to 0.25 mm, and more preferably 0.025 to 0.175 mm.

  The axial length n of the tip vent portion 26 constituting the first vent 25 in the tip portion 20 is preferably 5 to 30 mm, more preferably 10 to 20 mm. Accordingly, the first vent 25 is a cylindrical space having a diameter difference between the inner diameter and the outer diameter r: 0.02 to 0.50 mm and a length n: 5 to 30 mm.

  The second vent 27, which is configured wider than the first vent 25, has a plurality of chamfered portions extending in the axial direction formed at predetermined intervals in the circumferential direction on the outer peripheral surface 28a of the rear vent portion 28 of the plunger tip 9. 33 and a plurality of exhaust passages 34 constituted by the inner peripheral surface 7 a of the sleeve 7. The maximum depth h of each chamfered portion 33 is larger than the gap distance of the first vent 25 ((diameter difference r between the outer peripheral surface 26a of the tip vent portion 26 and the inner peripheral surface 7a of the sleeve 7) / 2).

  The plurality of exhaust passages 34 are configured at equal intervals in the circumferential direction of the plunger tip 9. The second vent 27 of the present embodiment is composed of four exhaust passages 34 provided at equal intervals with an angle of 90 ° in the circumferential direction. Each exhaust passage 34 is formed in a vertically long shape in plan view by chamfering a part of the peripheral surface of the rear vent portion 28 of the plunger tip 9. The axial front end portion of each exhaust passage 34 of the present embodiment is curved toward the front of the plunger tip 9. The number of exhaust passages constituting the second vent 27 is not limited, and may be two, three, or five or more.

The maximum depth h in the radial direction of each exhaust passage 34 constituting the second vent 27 preferably satisfies the following formula 1 and is 5.00 mm or less.
((R / 2) × 2) <h <((r / 2) × 10) (Formula 1)
However, r is the difference in diameter between the outer peripheral surface 26a of the tip vent portion 26 (the outer peripheral surface of the tip of the plunger tip 9) and the inner peripheral surface 7a of the sleeve 7.

The width M of each exhaust passage 34 preferably satisfies the following formula 2.
1 mm ≦ M <(SQRT (t ² −D × t) × 2) mm (Formula 2)
However, D is the diameter of the plunger tip 9, and t is the maximum depth of the chamfered portion 33 in the plunger tip 9. In Equation 2, SQRT (t ² −D × t) represents the square root of (t ² −D × t). The length of each exhaust passage 34 in the axial direction is not limited, and each exhaust passage 34 only needs to extend to the rear space of the tip portion 20.

  Here, the second vent 27 configured to be wider than the first vent 25 is configured such that the radial sectional area of the second vent 27 is larger than the radial sectional area of the first vent 25 and the second vent 27 is configured. It means that the space is larger than the configuration space of the first vent 25. Therefore, the sum of the radial cross-sectional areas of the plurality of exhaust passages 34 constituting the second vent 27 of the present embodiment is larger than the radial cross-sectional area of the annular first vent 25. Thereby, the gas ventilation resistance decreases from the outlet portion of the first vent 25 toward the rear in the axial direction. As described above, the vent portion 24 includes a first vent 25 having a thin gap space and a second vent 27 having a space wider than the first vent 25 on the exhaust tip side.

  The fixed portion 21 of the plunger tip 9 has a diameter smaller than that of the tip portion 20, and a grip plane portion 23 is formed on a part of the peripheral surface of the fixed portion 21, so that it becomes the exhaust tip side of the second vent 27. The fixing portion 21 is configured wider than the second vent 27. Since a rod 11 having a smaller diameter than the plunger tip 9 is provided behind the plunger tip 9, a wider gas flow path is formed.

  At the time of molding, after the molten metal is supplied to the sleeve 7 of the pressurizing mechanism 4, the plunger 8 advances in the sleeve 7, and the mold space is closed by the plunger tip 9. Most of the gas in the runner and the gas in the cavity 3 are discharged by another vent mechanism provided in the runner and the cavity 3. Until the plunger tip 9 comes in front of the gas discharge groove 31 formed in the sleeve 7, the gas existing in front of the plunger tip 9 is discharged from the gas discharge groove 31 to the rear of the plunger tip 9. After the gas discharge groove 31 is closed, a small amount of gas existing in front of the plunger tip 9 in the closed die space escapes to the rear of the plunger tip 9 through the vent portion 24 and out of the die space. Is discharged.

  Thus, even after the mold space in front of the plunger tip 9 that presses the molten metal is closed by the vent portion 24, the gas slightly present in front of the plunger tip 9 can be discharged. The gas that has escaped to the rear of the plunger tip 9 is discharged to the outside through the joint of the sleeve 7 and the like. The molten metal pressurized by the plunger 8 is solidified in the vicinity of the entrance of the first vent 25 and does not enter deep into the gap space of the first vent 25.

  By configuring the vent part 24 with the first vent 25 having a thin gap space and the second vent 27 having a space wider than the first vent 25 on the exhaust tip side, the following action can be obtained. In a state where the molten metal is pressurized by the plunger 8 and the molten metal is in contact with the front surface of the plunger tip 9, the vicinity of the entrance of the first vent 25 constituted by the narrow gap space is decompressed to a vacuum state, and the plunger tip 9 The discharge speed of the slight gas existing in front of the is increased.

  Since the second vent 27 including the plurality of exhaust passages 34 is wider than the first vent 25, the gas ventilation resistance after passing through the first vent 25 can be reduced. That is, the first vent 25 increases the discharge speed of the gas slightly present in front of the plunger tip 9, and the gas ventilation resistance after passing through the first vent 25 by the second vent 27 including the plurality of exhaust passages 34. Can be reduced. Accordingly, a molding method can be performed in which the gas venting resistance after passing through the first vent 25 by the second vent 27 is increased by increasing the gas discharge speed by the first vent 25 and a slight amount of gas is reliably discharged. it can.

  By setting the length n in the axial direction of the first vent 25 to 5 to 30 mm, appropriate ventilation resistance can be obtained, and blowing out of the molten metal can be prevented. By setting the maximum depth h in the radial direction of each exhaust passage 34 constituting the second vent 27 to satisfy the above formula 1 and not more than 5.00 mm, the gas ventilation resistance after passing through the first vent 25 can be reduced. It can reduce effectively and can prevent blowing out of a molten metal with it.

  By setting the width M of each exhaust passage 34 to satisfy the above formula 2, the gas after passing through the first vent 25 can be quickly discharged. By setting the size of each part of the first vent 25 and each exhaust passage 34 within the above range, the slightly present gas present in front of the plunger tip 9 is reliably discharged while preventing the molten metal from blowing out. be able to.

  In the molding apparatus 1, the plunger tip 9, and the molding method of the present embodiment, the vent portion 24 formed by the gap between the plunger tip 9 and the sleeve 7 is connected to the outer peripheral surface 26 a of the tip vent portion 26 of the plunger tip 9. An annular first vent 25 constituted by the inner peripheral surface 7a of the sleeve 7 and having a diameter difference r between the outer peripheral surface 26a and the inner peripheral surface 7a of 0.02 to 0.50 mm, and the first vent 25 And a second vent 27 that is wider than the first vent 25 so that the gas ventilation resistance decreases from the rear toward the axial direction.

  The vent portion 24 having the first vent 25 and the second vent 27 communicates directly with the mold space in front of the plunger tip 9. The vent portion 24 is thin so that the first vent 25 close to the mold space is thin, and the second vent 27 that communicates with the first vent 25 and is far from the mold space is wide so as to reduce the gas ventilation resistance. In the vent portion 24, the first vent 25 that once narrows the gas discharge path increases the gas discharge speed, and the second vent 27 that is wider than the first vent 25 is the first vent 25. The gas ventilation resistance after passing through the vent 25 is reduced.

  Thereby, even after the mold space in front of the plunger tip 9 that presses the molten material is closed, the gas slightly present in front of the plunger tip 9 can be reliably discharged, and the gas in the mold space can be discharged. Can be reduced to a minimum. By using the molding apparatus 1, the plunger tip 9, and the molding method of the present embodiment, a high-quality die-cast molded product with extremely few defects such as a nest can be obtained.

  The second vent 27 includes a plurality of chamfered portions 33 extending in the longitudinal direction and formed on the circumferential surface of the rear vent portion 28 of the plunger tip 9 at predetermined intervals in the circumferential direction, and the inner circumferential surface 7 a of the sleeve 7. Therefore, it is possible to obtain an appropriate gas flow resistance after passing through the first vent 25. Since the plurality of exhaust passages 34 are configured at equal intervals in the circumferential direction of the plunger tip 9, there is no bias in the discharge state of the gas after passing through the first vent 25, and the periphery of the first vent 25. Gas can be introduced evenly along.

  A comparison was made between a case where the bent portion 24 was configured using the plunger tip 9 according to the present embodiment and die casting was performed, and a case where a die casting was performed using a conventional plunger tip. FIG. 7A is a photograph of a die-cast molded product molded using the plunger tip of this embodiment, and FIG. 7B is a photograph of a die-cast molded product molded using a conventional plunger tip. In the photograph of FIG. 7 (b), the inner surface of the die-cast molded product has no gloss, whereas in the photograph of FIG. 7 (a), it is recognized that a strong gloss appears on the inner surface of the die-cast molded product. .

  Thus, when the vent part 24 is configured using the plunger tip 9 according to the present embodiment and die casting is performed, a die casting product having a very smooth surface with a small surface roughness can be obtained. . The reason why the surface roughness of the die cast product molded by the die casting apparatus 1 of the present embodiment is remarkably reduced is that there is no slight gas between the cavity 3 of the molding die 2 and the molded product. This is considered to be due to the fact that there is no gap between the molded product and the molded product.

  The die-cast molded product molded by the die-casting apparatus 1 of the present embodiment has a significantly reduced amount of distortion compared to the conventional case. This is considered to be due to the following reason. Conventionally, molding is performed with a slight amount of gas between the cavity and the molded product. Upon completion of molding, the molded product is cooled in the cavity immediately before being released from the mold, and the volume of gas existing between the cavity and the molded product is reduced. By reducing the volume of the gas, the molded product is attracted to the cavity like a suction cup. In this state, the mold release proceeds, an excessive force is applied to the molded product at the time of mold release, and the die cast product is distorted.

  On the other hand, in the die-casting apparatus 1 of this embodiment, since the gas existing in front of the plunger tip 9 can be reliably discharged, molding can be performed in a state where there is no slight gas between the cavity 3 and the molded product. Done. Even when the molded product is cooled when the molding is completed, there is almost no space between the cavity 3 and the molded product, so that the force that the molded product is attracted to the cavity 3 does not act as in the prior art. As a result, an excessive force is not applied to the molded product at the time of mold release, and the die-cast molded product can be prevented from being distorted.

  The present invention is not limited to the above embodiment. The said embodiment is an illustration of the shaping | molding apparatus, plunger tip, and shaping | molding method which concern on this invention. The molding apparatus, plunger tip, and molding method of the present invention can be applied not only to aluminum but also to other metals, and can also be applied to injection molding for molding a synthetic resin. In particular, by molding magnesium using the molding apparatus, plunger tip and molding method according to the present invention, a high-quality magnesium molded product can be obtained.

  The plunger tip in the present invention includes all forms of plunger tip. The shape of the sleeve into which the plunger tip is inserted is not limited as long as the vent portion can be configured. As shown in FIG. 8, a plurality of grooves 36 may be formed on the outer peripheral surface 26 a of the tip vent portion 26 of the tip portion 20, which is the tip outer peripheral surface of the plunger tip 35, over the entire axial length of the first vent. In this case, it is possible to increase the gas flow rate while maintaining appropriate gas flow resistance in the first vent. Such a plurality of grooves 36 may be provided so as to correspond to a plurality of exhaust passages.

  The second vent may have any shape as long as the second vent is configured wider than the first vent so that the gas ventilation resistance decreases from the first vent toward the rear in the axial direction. The shape of the chamfered portions of the plurality of exhaust passages constituting the second vent is not limited. The shape of the tip portion in the axial direction of each chamfered portion is not limited, and may be linear, or may be curved in the direction opposite to the tip direction of the plunger tip.

  FIGS. 9A to 9B show modified examples of the plunger tip. The plunger tip 37 of FIG. 9A shows an example in which the second vent is simply configured by making the rear vent portion 28 of the tip portion 20 smaller in diameter than the tip vent portion 26. The plunger tip 38 in FIG. 9B shows an example in which the chamfered portion 39 constituting each exhaust passage is widened toward the rear in the axial direction of the plunger tip 38. The plunger tip 40 in FIG. 9C shows an example in which the number of chamfered portions 41 is increased and more exhaust passages are provided.

  A passage portion that extends between adjacent exhaust passages may be provided. You may provide the island-shaped part which protrudes from the inner surface of each said exhaust passage in each exhaust passage. When using the shaping | molding apparatus, plunger tip, and shaping | molding method of this invention, as long as the various members provided as needed do not impair the effect of this invention, the thing of what forms may be sufficient.

DESCRIPTION OF SYMBOLS 1 Die casting apparatus 2 Mold for shaping | molding 3 Cavity 4 Pressurization mechanism 7 Sleeve 7a Inner peripheral surface 8 Plunger 9, 35, 37, 38, 40 Plunger tip 11 Rod 12 Supply path 20 Tip part 21 Fixed part 22 Raised part 23 Grip plane portion 24 Vent portion 25 First vent portion 26 Tip vent portion 26a Outer peripheral surface 27 Second vent 28 Rear vent portion 28a Outer peripheral surface 31 Gas discharge groove 33, 39, 41 Chamfered portion 34 Exhaust passage 36 Groove n Tip vent portion R / 2 Diameter difference between inner and outer diameters r / 2 Clearance distance between first vents h Maximum chamfer depth M Exhaust passage width 100 Sleeve 101 Gas discharge groove 102 Plunger tip 103 Supply port

Claims (9)

A mold for forming a cavity filled with a molten material, and a pressurizing mechanism for charging the cavity with the molten material,
The pressurizing mechanism is provided with a cylindrical sleeve that communicates with the molding die, and is slidable in the axial direction within the sleeve, and the molten material supplied into the sleeve is directed toward the cavity. In a molding apparatus provided with a plunger for pressurization, and provided with a plunger tip at the tip of the plunger,
In the gap between the plunger tip and the sleeve into which the plunger tip is inserted, a vent part for discharging gas along the axial direction is configured,
The vent portion is formed of an annular outer peripheral surface of the plunger tip and an inner peripheral surface of the sleeve, and an annular shape having a diameter difference between the distal outer peripheral surface and the inner peripheral surface of 0.02 to 0.50 mm. It has a 1st vent and the 2nd vent comprised more widely than the said 1st vent so that the ventilation resistance of gas may become small from the 1st vent toward the axial direction back. Molding equipment.   The molding apparatus according to claim 1, wherein an axial length of the first vent is 5 to 30 mm. 3. The molding apparatus according to claim 1, wherein the maximum depth h in the radial direction of the second vent satisfies the following formula 1 and is 5.00 mm or less.
((R / 2) × 2) <h <((r / 2) × 10) (Formula 1)
Where r is the difference in diameter between the outer peripheral surface of the tip of the plunger tip and the inner peripheral surface of the sleeve.   The second vent includes a plurality of chamfered portions extending in the axial direction formed at predetermined intervals in the circumferential direction on the circumferential surface of the plunger tip, and a plurality of chamfered portions configured by an inner circumferential surface of the sleeve. The molding apparatus according to claim 1, comprising an exhaust passage. The molding apparatus according to claim 4, wherein the width M of each exhaust passage satisfies the following expression (2).
1 mm ≦ M <(SQRT (t ² −D × t) × 2) mm (Formula 2)
Where D is the diameter of the plunger tip and t is the maximum depth of the chamfered portion of the plunger tip.   The molding apparatus according to claim 4 or 5, wherein the plurality of exhaust passages are configured at equal intervals in a circumferential direction of the plunger tip.   The molding apparatus according to any one of claims 1 to 6, wherein a groove is formed on the outer peripheral surface of the distal end of the plunger tip over the entire axial length of the first vent. A plunger tip used in the molding device according to claim 1,
A tip vent portion constituting the first vent with the inner peripheral surface of the sleeve;
A plunger tip having a rear vent portion which is continuously formed axially rearward of the tip vent portion and forms the second vent with the inner peripheral surface of the sleeve. . A molding method for performing molding using the molding apparatus according to claim 1,
A molding method characterized by increasing the gas discharge speed by the first vent and reducing the gas ventilation resistance after passing through the first vent by the second vent.