JP2562978B2 - Vertical injection device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a rigid injection device for injecting a melt into a mold cavity from directly below.

[Prior Art] For example, an aluminum disk wheel for automobiles is often cast by a rigid die-casting machine due to a small amount of gas entrainment during injection of molten metal. FIG. 3 is a schematic vertical cross-sectional view of a mold and an injection device of a conventional die casting machine of this kind. The description will be given with reference to FIG. 3 in which a fixed platen 1 fixed on a machine base has a center. A lower mold 2 having a cylindrical convex portion is attached to the part, and a movable platen 3 which is supported by a mold clamping cylinder (not shown) and can move up and down has a low convex portion at the center. The mold 4 is installed. Reference numeral 5 denotes a plurality of cores movably inserted in the horizontal direction from a position dividing the circumferential direction into two halves between the two dies 2 and 4, and a piston of a cylinder 6 supported on the movable platen 3 side. Rod 7
It is configured to move forward and backward in the horizontal direction by moving forward and backward. A cavity 8 is formed by the two dies 2 and 4 and the closed core 5. Fixed platen 1
An injection sleeve 9 is inserted into a sleeve hole formed in the lower mold 2 and the lower mold 2 so as to be freely inserted and removed from below, and a plunger tip 10 that advances and retracts by an injection cylinder (not shown) advances and retracts in the injection sleeve 9. It is fitted freely. Reference numeral 11 denotes a molten metal injected with the injection sleeve 9 removed from the sleeve hole.

With the above configuration, when the plunger tip 10 is advanced after the molten metal 11 is injected into the injection sleeve and inserted into the sleeve hole, the molten metal 11 is injected into the cavity 8, so that the molten metal 11 is After being solidified and cooled, the movable platen 3 is raised, the mold is opened, the core 5 is opened to the side, and the solidified product in the cavity is extruded by a product extruder (not shown) and the machine is extruded. To take out.

The molten metal 11 in the cavity 8 in such an injection operation
In order to explain the flow, the disk portion 8a of the cavity 8 which is the disk equivalent portion of the disk wheel in FIG.
4 is a disk shape as shown in FIG. 4, and the rim portion 8b of the cavity 8 that is a rim-corresponding portion is schematically shown as a cylindrical shape as shown in FIG. is there.
And the molten metal 11 pushed up by the plunger tip 10
After radially flowing through the disk portion 8a as shown by the arrow in FIG. 4, the rim portion 8b is suspended by its own weight as shown by the arrow in FIG. FIG. 6 is a perspective view showing the state of the molten metal flowing in this way. The molten metal 11 flowing as described above hangs down the rim portion 8b, so that at this time the temperature unevenness of the molds 2 and 4 The flowability of the mold may be uneven due to uneven release agent, flaws on the surfaces of the molds 2 and 4, and the gas may be confined by the melt 11 as shown by reference numeral 12 in FIG. When it is finished, the molten metal 11 entrains the gas to form a cavity in the molded product.

When the injection is performed with the cavity 8 in such a manner that the disk portion 8a is positioned on the upper side, the gas may be entrained as described above. Now on the lower side, rim 8b
Should be made to rise upwards. Then, the hub decorative surface of the product becomes the injection sleeve 9 side, and unnecessary molten metal solids called biscuits are attached to this surface. Since the appearance of the decorative surface is impaired by cutting after molding, the conventional molding has been unavoidably performed with the disk portion 8a facing upward.

[Problems to be Solved by the Invention] As described above, in the conventional case, the molding was performed with the disk portion 8a on the upper side. Therefore, in order to avoid the entrainment of the gas, injection must be performed at a relatively low speed. Must
Not only the productivity is lowered, but originally, in order to stabilize the quality of the product, the flow form of the molten metal 11 in the cavity 8 must be controlled by the speed of the plunger tip 10, which is possible for the above reason. There was a problem that it could not be called control and the quality could not be stabilized. However, if the speed is controlled by the speed of the plunger tip 10, the injection speed increases and the entrainment of the gas increases.

[Means for Solving Problems] In order to solve such problems, according to the present invention, the melt passage between the sleeve insertion hole of the lower mold and the mold cavity is made larger than the inner hole diameter of the sleeve. A pin with a small diameter is inserted into and removed from the melt passage so that the outer diameter of the fitting part is slightly smaller than the inner diameter of the melt passage so that it can be raised and lowered to the upper mold side. Then, the lower side of the melt passage was formed into a taper hole expanding downward.

[Operation] When the plunger tip is raised by the injection cylinder, the melt in the sleeve is injected into the mold cavity through the melt passage. Immediately before or immediately after the end of injection, when the pin is lowered with the force in the upward direction being applied to the plunger tip and it is projected downward from the upper movable mold, the tip end of this pin protruding into the melt passage of small diameter. When the pin is loaded and the pin descends, the molten material in the vicinity of the vertical axis in the cavity and in the molten material passage of the small diameter part is expelled by the pin and pushed into the other parts of the cavity, so the feeder action is performed. As a result, the molten metal is sufficiently distributed to every corner of the mold cavity, and a dense product can be obtained.

When the melt solidifies in this state, the solidified product in the melt passage of the small diameter portion becomes a thin-walled cylindrical shape formed around the pin. Therefore, after the solidification of the product, the pins are lifted and then the mold is opened, the product is lifted with respect to the upper movable mold. At this time, since the lower side of the melt passage is a tapered hole that widens downward, the width of the thin-walled cylindrical portion in the vertical direction is considerably narrowed, and the upper movable mold and When the product rises, the solidified material is reliably and easily cut from the thin-walled cylinder leaving a biscuit in the sleeve.

[Embodiment] This embodiment shows an example in which the present invention is applied to a die opening / closing unit of a rotary die casting machine. FIG. 1 is a vertical sectional view of a die opening / closing unit in which the present invention is implemented, and FIG. It is a side view.

In these figures, the rotary die casting machine
It has a rotary table and three sets of mold opening / closing units mounted at positions that divide the outer periphery into three equal parts in the circumferential direction. The three work stations including a mold clamping / injection station, a product removal station, and a mold cleaning / release agent application station are respectively disposed at positions that divide the circumferential direction into three equal parts. A mold is attached to each mold opening / closing unit, and at each of the three stations, mold clamping and injection, mold opening and product removal, mold cleaning and spraying of a release agent are performed. Then, the table is stopped every 120 ° rotation to perform each of these operations, and one rotation completes one cycle. The drawing shows the mold opening / closing unit stopped at the mold clamping / injection station, and a mold clamping device (not shown) and an injection device are arranged above and below in FIG.

In the figure, the mold opening / closing unit 20 includes a mounting plate 21 detachably fixed on a rotary table (not shown), and a hydraulic pressure of a pair of mold opening / closing cylinders 22 erected on both right and left sides of the mounting plate 21. A horizontal plate-shaped top plate 24 is fixedly supported at the working end of the piston rod 23 that moves up and down. Then, as the piston rod 23 advances and retreats, the top plate 24 and an upper mold, which is a movable mold described later, are guided by four guide rods (not shown) to move up and down, and mold opening and mold matching are performed. It is configured as follows. The mounting plate 21 is fixed to a sleep support plate 26 of a lower mold, which is a fixed mold indicated by reference numeral 25, and the lower mold, which is a fixed mold, is
The upper surface forms a part of the surface of the mold cavity 8, and has a mold body 32 having a vertical casting path 49 for molten metal casting at an axial center portion.
An annular mold holder 30 that holds the mold body 32 by fixing it with bolts 31 by contacting the lower surface and outer peripheral surface of the mold body 32, and fixes the mold holder 30 by contacting the lower surface of the mold holder 30. The sleeve support plate 26 is mounted so as to be capable of holding, and the lower end portion of a fixed sleeve 33, which is arranged by bringing the upper end surface into contact with the lower axial center portion of the mold body 32, is fixed and held. The mold holder 30 is
A plurality of guide pins 29 embedded in the sleeve support plate 26
The lifting cylinder 89 composed of a cylinder 90 and a piston 91 mounted between the sleeve supporting plate 26 and the mold holder 30 lifts the cylinder by a small stroke so that it can be separated from the sleeve supporting plate 26. But usually the mold holder
Since it is not necessary to lift 30, the operating hydraulic pressure is applied to the rod side chamber of the push-up cylinder 89 so that the mold holder 30 and the mold body 32 do not float above the sleep support plate 26 when the mold is opened. I have to. Therefore, it can be said that the mold holder 30 is substantially fixed to the sleeve support plate 26. Reference numeral 28 denotes an annular core stopper ring fixed to the upper surface of the sleeve support plate 26 with a plurality of bolts 27. Reference numeral 33 denotes a stepped cylindrical fixed sleeve which is inserted into sleeve holes formed in three members 26, 30, and 32 of the lower mold, and is screwed to the sleeve support plate 26. The ring 34 prevents the sleeve from being pulled out.

On the other hand, on the lower surface of the top frame 24, a substrate 36 of an upper mold which is a movable mold generally indicated by reference numeral 35 is fixed,
The upper mold 35 includes a substrate 36, a support plate 38 integrally fixed thereto with a plurality of bolts 37, and a concave hole 38a of the support plate 38.
And a mold body 41 fitted in the recess 39a of the mold holder 39 and fixed with bolts 40.
It is formed by. At the lower end flange of the support plate 38,
Cylinder support plates 42 are fixed at equal intervals around the four locations. Reference numeral 44 denotes a core cylinder mounted on each cylinder support plate 42, and the piston rod of each core cylinder 44
A core 46 is fixed to each of the working ends 45. In the state shown in FIG. 1, the movement of each core 46 is restricted by the core stopper ring 28. However, when the lower surface of the core 46 is over the upper surface of the core stopper ring 28 due to the rise of the entire upper mold 35,
The piston rod 45 is configured to be simultaneously opened in the radial direction by retreating. When the four cores are closed as shown in FIG. 1, a perfect circle is formed by the four inner peripheral surfaces. The upper and lower mold bodies 41, 32
And the four closed cores 46 form a cavity 8 shown by the same reference numeral as in FIG. As is clear from a comparison between FIG. 1 and FIG.
However, the disk portion 8a is turned upside down as compared with the conventional case, and the disk portion 8a is located below the height of the entire cavity 8.

A cylindrical injection sleeve 47 supported via a block at the upper end surface of an injection cylinder (not shown) is inserted into the inner hole of the fixed sleeve 33 so as to be freely inserted and removed, and the hydraulic pressure of the injection cylinder is inserted into the inner hole. Plunger 48 going forward and backward
The plunger tip 48a as the head of the head is fitted. Inner holes 33a, 47a of both sleeves 33, 47 having the same diameter as each other
And a cavity center of the mold main body 32 between the cavity 8 and the cavity 8 as a passage for the molten metal injected into the inner hole 33a and injected into the cavity 8 by the advance of the plunger tip 48a.
Are provided in the vertical direction. The runner 49 includes a gate 49a as a cylindrical hole having a diameter considerably smaller than the inner holes 33a, 47a formed near the cavity 8 and a tapered hole 49b formed near the inner hole 33a and extending downward. The lower end surface of the disk portion 8a, which is formed and continues to the gate 49a, serves as a decorative surface of the product that is solidified in the cavity 8. Since the lower side of the melt passage, which is the runner 49, is formed as a tapered hole 49b, the vertical width of the gate 49a, which is a vertical portion, is relatively narrow.

A rim portion is provided outside the upper end of the annular rim portion 8b of the cavity 8.
An annular runner 50 concentric with 8b is provided on the lower end surface of the mold holder 39, and the runner 50 and the rim portion 8b are communicated with each other by a plurality of radial gates 51. . The reference numeral 52 indicates the cavity 8 at the time of injection.
A gas venting device for venting the internal gas to the outside of the machine, which is located between one adjacent core 46 and is disposed between the upper die 35 and the lower die 25. The device 52 is divided into a valve seat portion 53 and a cylinder portion 54. And the valve seat
53 is divided into a front side and a paper back side in FIG.
It is formed to open integrally with each core 46 on both sides,
The cylinder portion 54 is formed on a piston rod 56 of a degassing cylinder 55 pivotally attached to the support plate 38 so as to be movable in the axial direction via links 57 and 58. This degassing device 52 is a conventionally known cylinder type degassing device,
A gas path 59 communicating with the runner 50, and a valve 60 for opening and closing a terminal valve seat thereof are provided. During injection, the valve 60 is opened and gas is discharged by the pressure of the molten metal or a vacuuming device, and the inertia of the molten metal is reduced. The valve 60 is configured to be closed by a force or an electric signal so that discharge of the molten metal to the outside of the valve seat is shut off. Further, the cylinder portion 54 has a function of ensuring valve closing and holding the valve 60 at each opening / closing position, and when the upper die 35 is opened, the cylinder portion 35 is actuated to retreat from the valve seat 53 to open and close the valve. Forgive and rise with die 35.

Next, mold clamping and mold opening will be described. The mold clamping is performed by lowering the top plate 24 against the oil pressure of the mold opening / closing cylinder 22 by a mold clamping cylinder (not shown) from the mold matching state shown in FIG. 1, and the mold opening cylinder is retreated. Thereafter, the piston rod 23 of the mold opening / closing cylinder 22 is advanced from the state shown in the figure, and the top plate 24, the upper mold 35, the degassing device 52 and the like are integrally raised. Then, the product solidified in the cavity 8 reaches the upper mold 35 by the mold opening and rises.

Next, a feeder that operates in the latter half of the injection, a cutting device for the gate 49a, a cutting device for the runner 50, and a product pushing device when the mold is opened will be described.

A cylinder 61 for pin projection is fixed to the center of the top plate 24, and a piston rod 62 thereof penetrates a rod hole of the top plate 24 and is projected downward. Reference numeral 63 is a round rod-shaped pin that extends downward by screwing a screw hole into the protruding screw portion of the piston rod 62, and is joined after being divided into, for example, three upper and lower stages, and the diameter of the lower stage portion is the gate The diameter is slightly smaller than the diameter of 49a. When the inner diameter of the gate 49a is, for example, 40 to 60 mm, the outer diameter of the pin 63 is, for example, 1 to 5 mm from the inner diameter of the gate 49a.
It is formed small. The pins 63 are connected to the substrate 36 and the support plate.
The bearing 64 is fixed to the support plate 38, the support plate 38, the bearing 65 fixed to the support plate 38 and the mold body 41, the mold body 41, and the cartridge 66 fixed to the mold body 41, respectively. The piston rod 62 is supported by the shaft hole provided to be able to move up and down freely, and the hydraulic pressure of the cylinder 61 causes the piston rod 62 to advance and retreat,
The pin 63 is configured to move up and down between a solid line position and a two-dot chain line position in FIG. That is, the cavity 8
When the pin 63 descends to the position of the chain line before the molten metal 67 in the inside solidifies,
The pin 63 eliminates the molten metal 67 and acts as a feeder,
The gate 49a is configured to have a hole penetrating the thin molten metal solidified material 68. Then, as described later, the product and the biscuit 69 are separated by cutting the solidified molten material 68 when the mold is opened. A cooling device having a hole 71 for cooling water extending from the rear to the vicinity of the tip is provided inside the pin 63, and the pin 63 heated by the molten metal is cooled to prolong its life. In addition, when the feeder operation is completed, conversely, by the action of the cooling water in the pin 63, the boss portion in the central portion of the disk portion 8a, which is relatively thick and difficult to cool, is quickly cooled, The mold opening is expedited accordingly, the workability is increased, and the injection cycle time is considerably shortened.

Further, a plurality of product extrusion cylinders 72 are fixed on the upper surface of the top plate 24,
An ejector plate 74 parallel to the top plate 24 is fixedly supported on the upper end of the 73, and the plurality of pins 75 fixed to the ejector plate 74 are connected to the top plate 24.
After projecting downward through the hole of the base plate 36, it is screwed into the screw hole of the extruding plate 76 provided in the space member of the supporting plate 38 so as to be vertically movable. Extruded plate 76 divided into upper and lower two
Plural extruding pins 7 with the head held between
7,78 have a lower end abutting on the hub extruding plate 79 provided vertically movable in the space of the die holder 39 and the upper end of the rim portion 8b, and the product extruding cylinder 72 after the die is opened. When the ejector plate 74 is lowered by operating the ejector plate 74, the pin 75, the extruding plate 76, the extruding pins 77 and 78, the hub extruding plate 79, and the extruding member that is supported by the hub extruding plate 79 and abuts on the disk portion 8a that is also the hub portion. It is configured to push the product downward from the cavity 8 via the pin 80. The hub push-out plate 79 is
It is guided by the guide pin 81 and moves up and down.
And is returned to the ascending position.

Further, a plurality of stoppers 83 formed in a columnar shape are provided at positions provided at positions where the outer periphery of the lower end of the mold holder 39 is equally divided into a plurality of parts in the circumferential direction. Mated and tapered holes provided in each stopper 83
The tapered ends of the rods 85 suspended from the extruded plate 76 by their own weights are engaged with 83a. And the extrusion plate 76
1 is moved down by a stroke indicated by a in FIG. 1, the pushing plate 76 and the rod 85 are integrated with each other, and the rod 85 starts to move down, and the stopper 83 is moved outward by the taper action. In addition, each of the push-out pins 86 supported and hung at a position where the outer peripheral portion of the push-out plate 76 is equally divided in the circumferential direction.
The lower end of the runner is in contact with the runner 50, and
A circular projection 83b provided on the stopper 83 is inserted into the recessed hole of the stopper 50 in a freely insertable and removable manner to seal the molten metal solidified material in the runner 50, and after the stopper 83 retracts and the projection 83b comes off, When the push-out plate 76 is lowered and is lowered by the stroke indicated by reference numeral 2a in FIG. 1, the push-out pin 86 is started to be lowered. Then, the protrusion 83 of the stopper 83
When the extruded plate 76 starts to descend when b is inserted,
First, the product is extruded by the extrusion pins 78 and 80 and the gate 5
It is cut at 1, and the ring-shaped solidified matter is retained in the runner 50 by the projection 83b. After that, the stopper 83 moves in the stroke a as described above, and the solid matter in the runner 50 is extruded in the stroke 2a.

1 is a cylinder for regulating the extrusion timing fixed to the upper surface of the top plate 24. The cylinder 85 is located between the piston rod 88 and the ejector plate 74 at the upper limit. When the ejector plate 74 descends and comes into contact with the piston rod 88, the descending stops once and then descends again by the control of an electromagnetic valve or the like. That is, this stop position is the lowering start position of the rod 85 and the position where the product is extruded by only a, so that the runner 50 does not wrap around and be extruded below the product. This eliminates the need for difficult runner removal work, thereby avoiding product damage during removal.

Next, the operation of the apparatus configured as described above will be described. The mold opening / closing unit 21, which has been sprayed with the mold release agent at the upstream work station and has been mold-set, circulates to the mold-clamping / injection station by rotation of the rotary table and stops. The mold is clamped by pressing. When the injection sleeve 47 in which the molten metal 69 is injected at the same time as the mold clamping is inserted into the inner hole of the fixed sleeve 33 and joined, and the plunger tip 48 is advanced, the molten metal 69 is injected into the cavity 8 and filled.
The solid line in FIG. 2 shows the end of injection.

Immediately before or immediately after the end of the injection, that is, before the molten metal 69 does not start to solidify, when the piston rod 62 of the pin projecting cylinder 61 is advanced hydraulically, the pin 63 descends and projects from the cartridge 66, and FIG. As shown by a two-dot chain line, the molten metal 69 in the gate 49a is pushed into the molten metal 69. At this time, the projected path of the pin 63 at the center of the longitudinal axis in the cavity 8 and the molten metal 69 in the gate 49a are eliminated by the pin 63. Since the molten metal 69 flows into the cavity 8, it acts as a feeder, and the molten metal 69 spreads to every corner of the cavity 8.

In this state, the molten metal 69 begins to solidify, but since cooling water is flowing through the holes 71 inside the pin 63, the molten metal 69 in the portion around the pin 63 where the wall is thickest and hard to solidify is relatively It solidifies quickly, and mold opening can be performed faster accordingly.

After a certain time has passed since the hot water was poured, solidification was completed and the product was obtained. Then, after the pin 63 is retracted, when the rotary table rotates 120 ° and the mold opening / closing unit 21 stops at the product removal station, the piston rod 23 moves forward by the hydraulic pressure of the mold opening / closing cylinder 22, and the top plate 24 rises. Therefore, the entire upper mold 35 integral with the mold is lifted and the mold is opened. In this case, as described above, since the pin 63 is inserted into the gate 49a and the diameter difference from the gate 49a is small, a thin cylindrical molten metal solidified around the portion where the pin 63 is located. The gate is formed
A tapered hole 49b is provided immediately below 49a, and the vertical width of the thin-walled cylindrical portion of the molten metal solidified product generated between the pin 63 and the gate 49a is extremely narrow, and the molten metal in the tapered hole 49b is formed. Since the solidified material has a small diameter on the upper side so that it does not come out upwards, when the mold is opened, the product inside the cavity that reaches the upper mold 35 and rises, holds the biscuit inside the fixed sleeve 33 and the tapered hole 49b. It is easily cut from the thin-walled cylindrical portion while remaining inside and rises together with the upper die 35.

After the mold is opened in this manner, when the piston rod 73 is retracted by the hydraulic pressure of the product extrusion cylinder 72, the top plate 24 starts to descend. As a result, first, the push pins 77 and 78 integrated with the push plate 76 are lowered, and the products whose tips are in contact with each other start to be pushed out from the cavity 8. At this time, as shown in FIG. 2, since the projection 83b of the stopper 83 is engaged with the concave hole of the runner 50, the runner 50 is pushed down even if the product is pushed down.
The product and the runner 50 are separated from the gate 51. When the top plate 24 descends by the stroke a, it abuts on the upper end of the piston ton rod 88 of the cylinder 87, so that the descending is once stopped, and after a predetermined timing, it begins to descend again. At the time of restarting the lowering, the rod 85 is also lowered because the pushing plate 76 and the rod 85 are integrated by the stroke a. When the rod 85 descends, its lower end pushes the taper hole 83a of the stopper 83, and the stopper 83 retreats outward by the taper action.
Get out of the concave hole. When the top plate 24 continues to descend and further descends by the stroke a, and the total descends by 2a, the push-out plate 76 and the push-out pin 80 become integral with each other, so that the push-out pin 86 also starts to descend, and the lower end thereof is in contact with the annular shape. The runner 50 is extruded.

Next, an extruder for extruding a biscuit (not shown) is moved between the opened molds, and the piston rod is advanced, whereby the biscuit is extruded. The extrusion device for biscuit extrusion is composed of a cylinder, a piston rod that faces downward, and a moving device that moves the cylinder between the upper and lower mold bodies 41 and 32 that open the mold and the outside. The upper end side of the cylinder is brought into contact with the lower end surface of the pin 63 retracted into the upper mold body 41, and the tip end portion of the piston rod provided at the lower end side of the lower mold body 32. By inserting the biscuit into the small-diameter portion and pushing down the upper surface of the biscuit, the biscuit is projected downward.

In the case of a disk wheel, the product taken out of the mold in this manner has a decorative surface on the lower side of the hub in the figure, but only a thin cylindrical solidified material is attached here. Is easy to remove, and does not impair the aesthetic appearance even after the removal.

In addition, although the present embodiment shows an example in which the present invention is applied to a rotary die casting machine, it goes without saying that the present invention can be applied to a stationary die casting machine as well. Further, the present invention can be applied to an injection molding machine for plastics.

[Effects of the Invention] As is clear from the above description, according to the present invention, in the rigid injection device, the melt passage between the sleeve insertion hole of the lower mold and the mold cavity is defined by the inner diameter of the sleeve. Is also formed to have a small diameter, and a pin whose outside diameter of the fitting portion that can be inserted into and removed from the melting passage is slightly smaller than the inside diameter of the melt passage can be raised and lowered to the upper mold side. By supporting and making the lower side of the melt passage into a tapered hole that spreads downward, a thin solidified product is formed in the melt passage by the action of a pin, and downwardly below the melt passage. Since there is a widened tapered hole, it is possible to provide a relatively narrow gate portion in the vertical direction only in the upper portion in contact with the cavity in the melt passage, so that the vertical width of the thin solidified product can be reduced. It can be formed in a narrow upper position,
As a result, the pin can be reliably and easily advanced at least into the gate section each time, and the cutting distance of the gate section can be shortened, so that the product and the biscuit can always be secured at a predetermined position when the mold is opened. It can be easily separated. In addition, it is possible to form a disc foil with a low hub portion without impairing the aesthetic appearance of the makeup surface, and there is no gas entrapment, which greatly improves the product quality and
There is no need to reduce the injection speed in order to avoid gas entrapment, which improves productivity. Further, since the lower side of the melt passage is formed as a taper hole spreading downward, the biscuit in the fixed sleeve or the like can be easily pushed out and taken out after the mold is opened. Further, since there is a gap between the pin and the melt passage, the pin does not hit or contact the inner peripheral surface of the mold or the melt passage, and the life of the pin is extended.

In addition, the pin eliminates the molten metal in the pin's protruding path at the longitudinal center of the cavity and in the small diameter part, which results in a feeder action that spreads the molten metal to every corner of the cavity. It is possible to easily obtain a dense and high-strength product that is improved and has no nest. In particular, in the present invention, since the pin having a diameter slightly smaller than the diameter of the melt passage can be advanced into the melt passage, the melt passage does not regulate the advance limit of the pin, and the pin melts. Even if it enters the material passage, it can advance sufficiently, and the feeder effect that acts on the molten metal in the cavity is correspondingly increased.

And, of course, this feeder operation can be performed before the injection operation is finished, but at that time, the injection pressure acting on the molten metal by the plunger tip acts on the molten metal in the cavity through the narrow gap around the pin. Therefore, sufficient injection pressure acts until the end of the injection operation, and a more dense product can be obtained.

Further, after injection, a pin having a diameter slightly smaller than the diameter of the melt passage is advanced into the melt passage having a diameter smaller than the inner diameter of the injection sleeve to form a thin molten metal solidification product therebetween. Since the thin part cools and solidifies immediately, the amount of molten metal cooling in the product equivalent part decreases, and even when the thick part biscuit part in the fixed sleeve or injection sleeve has not completely solidified, the inside of the cavity When the relatively thin product portion has completely solidified, the mold can be opened immediately. As a result, the cycle time is shortened and the productivity is improved in this respect as well.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIGS. 3 to 6 illustrate a conventional apparatus similar to the present invention. , FIG. 3 is a schematic longitudinal sectional view of a mold and an injection device, FIG. 4 is a schematic view of a disk unit, FIG.
The figure is a schematic view of the rim portion, and FIG. 6 is an explanatory view showing the flow state of the molten metal. 8 …… cavity, 25 …… lower mold, 35 …… upper mold, 33, 47 …… sleeve, 49 …… runner (melt passage), 49a …… gate, 49b …… taper part, 61… … Cylinder for pin projection, 62… Piston rod, 63… Pin.

Claims (1)

(57) [Claims] 1. A melt passage between a sleeve insertion hole of a lower die and a die cavity is formed to have a diameter smaller than an inner hole diameter of the sleeve, and the melt passage is fitted in the melt passage so as to be insertable and removable. A pin whose outer diameter of the fitting portion is slightly smaller than the inner diameter of the melt passage is supported on the upper die side so as to be able to move up and down,
A rigid injection device in which a lower side of the melt passage is a downwardly widening tapered hole.