JP2887709B2 - Sprueless disk mold - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold for an injection molding machine for manufacturing a disc, and more particularly to a sprueless disc mold from which sprue generated during molding is removed.

[0002]

2. Description of the Related Art Conventionally, in a plastic mold used for an injection molding machine or the like, a sprue bushing which is in close contact with a nozzle of the injection molding machine is fitted on a front surface of a fixed mold, and molten resin is directly injected from the nozzle. A sprue hole having a taper is formed in the sprue bush as a path for transfer to the cavity.

[0003] For this reason, sprue is always produced when a molded product is produced, and it is necessary to remove the sprue. The mold for manufacturing the disc has the same mold structure as the conventional one, for example, one disclosed in Japanese Patent Application Laid-Open No. 54-156062.

[0004] Referring to FIG. 7, the mold has a cavity 3 formed on an abutting surface between a fixed mold 1 and a movable mold 2. A sprue bush 4 having a sprue hole is attached to the fixed mold 1, and the sprue bush 4 forms a part of a wall whose end face on the mold contact surface side forms the cavity 3, On the side end surface, a spherical concave portion 5 for nozzle touch is provided.

On the other hand, a punch 6 and a center projecting pin 7 for projecting a sprue provided at the center thereof are attached to the movable mold 2. The leading end surface of the punch 6 constitutes a part of a wall forming the cavity 3. Reference numeral 10 denotes a punch driving cylinder, and reference numeral 11 denotes a center protruding pin cylinder.

The molding operation is performed by attaching such a mold to an injection molding machine and, after completion of mold clamping, injecting a molten resin from a nozzle 8 into a cavity 3 of the mold through a sprue hole. After the injection, the punch 6 is advanced to punch out a part of the molded product, and then the punch is retracted and the mold is opened to take out the molded product. At this time, the sprue 9 formed in the sprue bush 4 and the punched piece are taken out from the tip of the punch 6 in a state where they are solidified together. Then, the sprue 9 is moved from the punch tip by the protruding pin 7.
Etc. are excluded.

[0007]

In the above-mentioned conventional disk mold, a single-piece mold is usually used, and one sprue is generated for one product because a sprue bush is used. As a result, the amount of resin used in the sprue for the product is increased, and the material cost is increased.

[0008] Therefore, the use of sprueless dies has been gradually increasing due to the demand for reducing the amount of resin used and the product cost.

Further, since the sprue 9 has a relatively large diameter and requires a long time for cooling, it is the temperature at the root of the sprue that determines the manufacturing cycle time of the molded product. A sprueless mold is also required to reduce the cycle time.

Further, the generation of sprue requires a mechanism for removing the sprue, and requires the mold to be opened by the length of the sprue, which increases the manufacturing cost and affects the manufacturing cycle time. There was also a problem of giving.

In view of such circumstances, an object of the present invention is to provide a sprueless disk mold in which sprues are eliminated to reduce material costs for products and shorten the molding cycle.

[0012]

To achieve the above object, a sprueless disk mold according to the present invention has a cavity in an intermediate plate sandwiched between a mounting plate of a fixed mold and a mirror surface plate. A hot block member coaxially arranged opposite to the inlet member of the mounting plate is provided therein, and the inner peripheral surface of the inlet member and the hot block member are slidably contacted with each other so as to be movable forward and backward, and heated. A large-diameter portion formed with a plurality of flow paths communicating with the resin reservoir portion in both of the members, the tip of the small-diameter portion opens and closes the gate of the hot block member communicating with the cavity, and furthermore, the central portion of the disk A plunger that can be inserted into the protrusion hole of the movable mold together with the cut portion, a cylinder is arranged in the fixed mold, and a piston is inserted into the cylinder, and the piston is inserted. The rod is connected to an arm extending from the plunger into the cavity, and first and second springs are provided in the chamber of the cylinder so as to oppose each other with the piston interposed therebetween. Ejector for concentrically disposing the gate of the hot block member, providing another cylinder chamber communicating therewith, and projecting the cut portion from the ejection hole after opening the mold against a third spring provided in the cylinder chamber. A pin is provided, and when the tip of the plunger is in a position for sealing the gate, the cylinder is in a neutral position where the spring biasing force between the first and second springs is balanced. For cutting, the supply pressure to the cylinder chamber is switched according to the injection operation.

[0013]

According to this structure, the plunger is moved forward and backward by switching the driving source such as hydraulic pressure using the piston / cylinder, so that the mold gate is sealed, and the gate is opened to allow the molten resin to enter the cavity. The hot block that forms the path for the molten resin is always heated by the heating means, so sprue may be generated during the molding of the disk. Disappears.

[0014]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a main part of a sprueless disk mold according to the present invention. The mold is composed of a fixed mold 1 and a movable mold 2, and a cavity 3 for forming a disc is provided on the mating surface of the two. It has.

First, the fixed mold 1 will be described.

The fixed mold 1 includes a fixed mold body 12 having a mounting plate 12a, a first intermediate plate 12b, and a second intermediate plate 12c, and a hot mold for storing the molten resin therein and forming a passage for the molten resin. Block 13 and annular heater 14
A plunger 15 for opening and closing the passage of the molten resin to the cavity 3, an inlet member 16 having a concave spherical surface 16a abutting on the nozzle 8, and a fixed-side mirror plate having a concave portion forming a part of the cavity 3. Consists of 17

The stationary mold body 12 has a cavity 18 provided at the center of the first intermediate plate fixed and held between the mounting plate 12a and the second intermediate plate 12c. , In the figure, the structure penetrates vertically.

The cylindrical hot block 13 has a structure in which an annular heater 14 as a heating means is mounted on the outside, and is located in a cavity 18 of a fixed mold main body, and includes a fixed mirror plate 17 and an intermediate plate 12c. Are fixed so as to sandwich the flange portion 13a therebetween, and are arranged concentrically and opposed to the inlet member 16. The tip of the inner hole 13b of the hot block portion 13 communicates with a gate opening 19 to the cavity 3, and this inner hole 13b
The large diameter portion 15a of the plunger is slidably fitted in b. Further, a small diameter portion 15b of the plunger formed concentrically with the large diameter portion 15a of the plunger is provided.

The inlet member 16 is arranged such that the upper flange portion 16b is fixed to the mounting plate 12a using bolts or the like, and the tip of the nozzle 8 of the injection molding machine contacts the concave spherical surface 16a provided at the center. ing. An annular heater 14 is attached to the outside of the inlet member 16 in the same manner as the hot block portion 13, and the inside is provided with a through-hole 16c communicating with the concave spherical surface, and a resin reservoir is formed. Similarly, the large diameter portion 15a of the plunger is slidably fitted.

The annular heater 14 is attached to the outer periphery of each of the hot block portion 13, the plunger 15, and the inlet member 16. Although the drawing does not show the lead wire to the heater and the temperature control means, the hot block portion 13, the plunger 15 and the inlet member are supplied with electricity.
16 is heated to an appropriate temperature.

The plunger 15 has a large diameter portion 15a and a small diameter portion 15b extending toward the cavity 3. Large diameter part 15a
Both ends are respectively inserted and supported by the inner walls of the hot block portion 13 and the inlet member 16, and through holes for communicating the resin reservoir of the inlet member 16 with the inside of the hot block portion 13 are provided. 15c. As a result, the plunger 15 connects the injection port member 16 and the hot block portion 13 that are separately arranged, thereby forming a plurality of flow paths of the molten resin in the fixed mold 1. Also, the plunger 15 has a large diameter portion 15a.
Is connected to a drive source for controlling the flow of molten resin in response to opening and closing of the mold via an arm 20 extending from the central portion of the outer wall into the cavity 18.

This drive source comprises a hydraulic (or pneumatic) cylinder 21 formed in a mounting plate 12c. In a neutral state in which no oil liquid is supplied, a piston 22 sliding in a cylinder chamber is provided with springs 23, 24 from both sides. The balance is provided. At the tip of the rod 22a of the piston 22, an arm extending radially from the large diameter portion of the plunger 15
20 has been fixed. For this reason, the operation of the piston 22 can cause the plunger 15 to interlock in the range of the gap between the hot block portion 13 and the inlet member 16.

The cylinder 21 configured as described above performs a gate seal and a gate cut by moving the plunger 15 forward and backward, and in a neutral state in which no oil liquid is supplied into the cylinder 21, the tip of the plunger 15 Is fitted into the opening of the hot block portion 13 so that the tip surface of the plunger matches the cavity surface of the fixed-side mirror plate 17.

FIG. 1 shows a state in which the cylinder 21 is in a neutral state and the mold attached to the injection molding machine is in a mold closed state. The molten resin from the nozzle 8 is filled in the injection port member 16 and the hot block portion 13 of the mold.

Next, the movable mold 2 will be described.

The movable mold 2 is standardized as a mold member for resin molding, and is a movable mold body as a core plate.
26 and an attachment plate (not shown) attached to the movable platen of the injection molding machine.

The movable mold body 26 has a movable mirror surface plate 27 attached to the upper end surface thereof to form a disk cavity 3 on the mating surface with the fixed mold 1 and a gate opening 19 of the hot block portion 13. And has a protruding hole 29 concentrically opposed thereto. A hydraulic chamber 30 as a cylinder chamber communicating with the hole 29 is provided, and an ejector pin for projecting a center cut portion of the disc against a spring 25 in the hydraulic chamber 30 is provided.
28 are arranged.

The ejector pin 28 has a large-diameter piston portion 28.
a and a small-diameter rod 28b, and when the oil liquid is supplied to the hydraulic chamber 30, the ejector pin 28 performs a protruding operation. A small-diameter stepped portion 30a is formed in the upper part of the hydraulic chamber 30, and the ejector pin 28 is always urged rearward by a spring 25 housed therein. Is located lower than the end face of. The piston portion 28a of the ejector pin 28 is located in the hydraulic chamber 30, and the pin portion 28b is fitted into a protrusion hole 29 that penetrates from the hydraulic chamber 30 to the movable mirror plate 27. It is arranged facing the surface.

In the hydraulic chamber 30, the small-diameter stepped portion 30a forming the seat of the spring 25 serves as a shoulder which determines the position where the ejector pin 28 stops to protrude, and the large-diameter cylinder inner wall 30b follows the piston portion 28a. Form a sliding surface. Also,
On the bottom side of the piston portion 28a, there is a concave portion 28c for a hydraulic reservoir, and the concave portion 28c communicates with a flow path 31 leading to the hydraulic circuit shown in FIG.

This hydraulic circuit is of a known type, and comprises a drain circuit 40 and a pressurizing circuit 42 connected to a hydraulic pump 41, both of which are selectively switched by the excitation of a solenoid 43, and whose pressure is appropriately relieved. It is configured to be adjusted by a valve 44.

The operation of this embodiment will be described below.

When the mold of the sprueless disk mold shown in FIG. 1 is closed, the spring 23 and the spring 24 are in a balanced state, that is, the hydraulic (or pneumatic) source A and the hydraulic (or pneumatic) source B are filled with hydraulic fluid. The arm 20 is in the neutral state where the supply is not performed, and the arm 20 is
Is located approximately in the middle of the gap between
Is inserted into the gate opening 19 of the hot block 13, and the molten resin is completely sealed by the plunger 15. On the other hand, the hydraulic (or pneumatic) source C on which the movable mold is disposed is also in a neutral state, and is urged by a spring 25 to eject eject pins 28 for ejecting cut residues.
Is in the last retreat position.

FIG. 3 shows the relationship between the drive source and the plunger 15 and the flow state of the molten resin during injection filling and injection holding pressure. Here, a hydraulic (or pneumatic) source A is supplied into the primary cylinder chamber 21a, and the piston 22 moves upward together with the arm 20 in the figure to press the spring 24, and the piston 22 of the cylinder 21 retreats last. Position. Therefore, the plunger 15 that operates in conjunction with the piston 22 also moves backward (upward in the figure) by the same distance. As a result, the gate is opened because the tip of the plunger 15 is retracted from the gate opening 19 of the hot block 13, and the resin inside the hot block is injected into the cavity 3.

FIG. 4 shows a state at the time of gate cutting. Immediately after the completion of the injection holding, the hydraulic (or pneumatic) source A is turned off, and at the same time, the hydraulic (or pneumatic) source B is turned on, and the secondary side is turned on. The oil liquid is supplied into the cylinder chamber 21b. Therefore, the piston 22 advances downward in the figure while pressing the spring 23, and the plunger 15 also advances by the same distance via the arm 20 connected to the piston rod 22a. Therefore, the tip of the plunger 15 cuts the center of the disk and fits into the protrusion hole 29 of the movable mold 2 together with the cut portion 32 which becomes a residue of the molded product. The cutting is completed.

FIG. 5 shows a state in which the gate is retracted.
The hydraulic (or pneumatic) source B is also turned off. As a result, the piston 22 is balanced by the springs 23 and 24, and enters the neutral state shown in FIG.
The resin is sealed at the tip of the hot block 13. The mold opening is performed in this state.

FIG. 6 shows a step of projecting the cut portion 32 after the mold opening is completed. Each member arranged on the fixed mold 1 is kept in the neutral state shown in FIG. In this step, the hydraulic (or pneumatic) source C of the movable mold 2 is turned on, so that the oil liquid is supplied from the flow path 31 into the hydraulic chamber 30.

For this reason, the ejector pin 28 advances upward in the drawing to project the cut portion 32 in the ejection hole 29 to the outside. The cut portion 32 is detected by a photoelectric tube or the like provided below a mold attached to the injection molding machine to detect its drop. Thereafter, the disk remaining in the movable mold is sucked to the tip of the arm of the product take-out device and taken out. Thus, one cycle of the mold opening / closing operation is completed.

[0039]

According to the present invention, the gate seal and the gate cut can be controlled by a driving source such as hydraulic pressure, and the hot block forming the molten resin passage is always heated by the annular heater. As a result, sprue does not occur during disk molding. As a result, material costs associated with sprue generation can be saved, and products can be manufactured at low cost.

Further, since there is no need to determine the cooling time with the sprue cooling as a standard, the manufacturing cycle time can be shortened, the cost can be reduced, and the mold opening can be reduced because the sprue is not taken out. So
The opening and closing time of the mold is shortened, which contributes to shortening of the manufacturing cycle time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing the arrangement of each member when a sprueless disk mold of the present invention is closed.

FIG. 2 is a hydraulic drive circuit for supplying hydraulic pressure to a hydraulic chamber of a movable mold.

FIG. 3 is a longitudinal sectional view similar to FIG. 1, showing a state of the sprueless disk mold of the present invention at the time of injection filling and at the time of injection holding pressure.

FIG. 4 is a longitudinal sectional view similar to FIG. 1, showing a state of the sprueless disk mold of the present invention at the time of gate cutting.

FIG. 5 is a longitudinal sectional view similar to FIG. 1, showing a state of the sprueless disk mold of the present invention when the gate cut is retracted.

FIG. 6 is a cut portion of the sprueless disk mold of the present invention.
FIG. 2 is a longitudinal sectional view similar to FIG.

FIG. 7 is a longitudinal sectional view showing a conventional disk mold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fixed mold 2 ... Movable mold 3 ... Cavity 4 ... Sprue bush 8 ... Nozzle 9 ... Sprue 12 ... Fixed mold main body 13 ... Hot block part 14 ... Annular heater 15 ... Plunger 16 ... Injection port member 18 ... Cavity 19 ... Gate opening 20 ... Arm 21 ... Piston cylinder 22 ... Piston 23,24,25 ... Spring 28 ... Ejector pin 29 ... Protruding hole 30 ... Hydraulic chamber 32 ... Cut part A, B, C ... Hydraulic (or pneumatic) )source

Continuation of front page (56) References JP-A-3-90324 (JP, A) JP-A-1-280519 (JP, A) JP-A-61-228924 (JP, A) JP-A-5-50464 (JP) JP-A-55-61438 (JP, A) JP-A-3-284918 (JP, A) JP-A-4-78515 (JP, A) JP-A-5-138688 (JP, A) 5-56421 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/26-45/44 B29C 45/73 G11B 3/70 G11B 7/26 511

Claims (1)

(57) [Claims] 1. A disk cavity is formed between a fixed mold and a movable mold, and a hot block heated by a heating means is provided between a gate communicating with the cavity and a molten resin injection port. In the sprueless disk mold provided, a cavity is provided in an intermediate plate sandwiched between a mounting plate and a mirror surface plate of the fixed mold, and the cavity is concentrically disposed in the cavity so as to face an inlet member of the mounting plate. A plurality of flow paths which are provided so as to be able to advance and retreat by slidingly contacting the respective inner peripheral surfaces of the injection port member and the hot block member, and communicate with the resin reservoir in both heated members. The large-diameter portion has a large-diameter portion, and the tip of the small-diameter portion opens and closes the gate of the hot block member that communicates with the cavity. A plunger that can be inserted together with the socket portion, a cylinder is arranged in the fixed mold, a piston is inserted into the cylinder, and an arm extending from the plunger into the cavity into the rod of the piston is provided on the arm of the piston. While consolidating,
The first and the first opposed to each other with a piston interposed in the chamber of the cylinder.
A second spring is provided. Further, in the movable mold, the protrusion hole is arranged concentrically with the gate of the hot block member, and another cylinder chamber communicating with the same is provided. An ejector pin for projecting the cut portion from the ejection hole after opening the mold against the spring, and the cylinder is a spring between the first and second springs when the tip of the plunger is at a position for sealing the gate. A sprueless disk mold, wherein a supply pressure to the cylinder chamber is switched in accordance with an injection operation to open and close the gate and cut a central portion of the disk in a neutral position where the urging force is balanced.