JPS63154318A - Injection device of injection molding machine - Google Patents

Abstract

PURPOSE:To contrive prevention of damage of a reinforcing fiber by reducing flow path resistance to be given to a molding material, by a method wherein a molding material within a barrel is injected by moving a plunger, screw and piston so as to press them into the barrel after interruption of communication between the barrel and the inside of the plunger by fitting the screw into a through hole formed on a piston. CONSTITUTION:A plasticized molding material is sent into a spatial part B of the inside of a barrel 17 through a gap between a screw head 25 and a projected part 14a and a through hole 18, in an opening part 12b of a plunger 12. Then at a point of time when the molding material within the spatial part B has arrived at a predetermined quantity, a position 14 is abutted against a screw head 25 by moving the piston 14 toward a screw 13 by actuating an actuator 15, and the through hole 18 is clogged. Then the plunger 12, the screw 13, the piston 14, the actuator 15, material filling equipment 22 and an intermediate cylinder 27 are moved toward the barrel 17 along with a slider 20 by actuating an injection cylinder 21. With this construction, the molding material within the spatial part B of the barrel 17 is injected and cast into an outside mold through a nozzle 16 by pressurizing the molding material by the piston 14.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to an injection device for an injection molding machine, and particularly relates to an injection device suitable for use when molding a resin to which [e] is added. be.

"Prior Art" Conventionally, as an injection device used for injecting a plasticized molding material into a mold, for example, those having structures shown in FIGS. 3 to 5 are known.

This injection device has a hopper 2 connected to one end of a cylindrical barrel 1 for injecting the molding material into the barrel l, and a hopper 2 at the end of the barrel to feed the molding material into a mold (not shown). A nozzle 3 is formed for injecting the molding material from the hopper 2 into the barrel 1.
A screw 4 for pressure-feeding is mounted rotatably and slidably in the length direction of the barrel 1, and one end of the screw 4 is made to protrude outside from one end of the barrel 1. A motor 5 for rotating the screw 4 and an injection cylinder 6 for reciprocating in the longitudinal direction are installed at the other end of the screw 4, and a cone whose diameter gradually becomes smaller toward the front in the injection direction is installed at the other end of the screw 4. a table-shaped taper ring 7;
The screw head 8 has an annular groove deeper than the helical groove 4a of the screw 4 between the screw head 8 and the tapered ring 7. Small diameter portion 8 forming 9
a, and a communication groove 8b which connects the annular groove 9 to the filter space A formed between the screw head 8 and the nozzle 3 of the barrel l in the circumferential direction as shown in FIG. A plurality of rings are formed at intervals, and in the annular shape 7119,
A backflow prevention ring lO is installed which has an outer diameter substantially the same as the inner diameter of the barrel l and is movable relative to the screw 4 and the screw head 8 in the length direction thereof.

The inner diameter of the backflow prevention ring 10 is set to be larger than the small diameter portion 8a of the screw head 8 and smaller than the maximum outer diameter of the tapered ring 7. A gap G is formed around the entire circumference between the tapered rings 7 and 7.
When brought into contact with the screw 4, communication between the gap G and the spiral groove 4a of the screw 4 is cut off.

On the other hand, in the conventional injection device configured in this way, the molding material introduced into the barrel l from the hopper 2 is transferred to the screw 4.
At the same time, the molding material is heated and plasticized during this pressure-feeding process, and the plasticized molding material is transferred from the spiral groove 4a to the gap between the tapered ring 7 and the backflow prevention ring 10, and into the backflow prevention ring 10. It is pushed out into the space A through the gap G between the prevention ring 10 and the small diameter part 8a of the screw head 8 and the communication groove 8b, and is pushed out into the space A.
When the extruded molding material reaches a predetermined amount, the screw 4 and screw head 8 are moved toward the nozzle 3 by the injection cylinder 6.
The molding material in the space A is injected from a nozzle 3 and injected into the mold.

During the above-described injection operation, as the screw 4 moves, the taper ring 7 provided on the screw L-4
As shown in FIG. 5, by bringing the screw into contact with the backflow prevention ring IO, the spiral M4a of the screw 4 is blocked from the gap G formed between the screw head 8 and the backflow prevention ring 10. This prevents the plasticized molding material in the space A from flowing back toward the screw 4, thereby improving the injection efficiency of the molding material.

"Problems to be Solved by the Invention" However, in the conventional injection device having the above-described configuration, when the molding material is fed under pressure to the space A of the barrel 1 by the screw 4, the molding material is transferred to the tapered ring 7.
The screw must pass through the gap G between the backflow prevention ring IO and the small diameter portion 8a of the screw head 8, but when passing through these gaps, the molding There is a problem that a large flow path resistance acts on the material.

Such problems become particularly noticeable when reinforcing fibers such as glass fibers or additives such as fillers are added to the molding material, and the added reinforcing fibers may be damaged, causing damage to the added reinforcing fibers. This causes the problem that the effect is halved.

In addition, one way to suppress the occurrence of such problems is to make the above-mentioned gaps as large as possible to reduce the flow path resistance. In summary, it is necessary to increase the inner diameter of the backflow prevention ring 10 or to reduce the outer diameter of the small diameter portion 8a of the screw head 8.

However, in the method of the old book, it is regulated by the outer diameter of the backflow prevention ring IO or the inner diameter of the barrel l.
In addition, since the inner diameter is set in consideration with the small diameter portion 8a of the screw head 8, if the inner diameter is increased, the backflow prevention ring IO cannot have a sufficient wall thickness. Since the part 8a becomes a stress concentration point during injection, and as the diameter is made smaller, stress concentration becomes more pronounced, which results in restrictions from a structural or strength perspective, so either method is not an effective solution. It cannot be used as a means.

[Means for Solving the Problems] An object of the present invention is to provide an injection device that can effectively solve the problems in the conventional techniques described above. a cylindrical plunger having an inlet for discharging the molding material and an opening for discharging the molding material;
a screw that is rotatably installed in the plunger and forces the molding material introduced into the plunger toward the opening of the plunger; and a screw that covers the opening of the plunger and moves relatively in the length direction of the plunger. an actuator provided between the piston and the plunger for relative movement therebetween;
a barrel having a nozzle into which the piston is slidably fitted and from which a molding material is discharged, and
The piston is characterized in that a through hole is formed in the piston to communicate the inside of the plunger and the inside of the barrel, and the through hole is opened and closed by the screw as the piston and the plunger move relative to each other.

"Operation" The injection device according to the present invention separates the through hole formed in the piston from the screw by the relative movement of the piston and plunger by the actuator, thereby forming a flow path for the molding material to be pumped by the screw. By moving the piston toward the opening of the plunger and fitting a screw into the through hole formed in the piston, the through hole is closed and the barrel is closed. and the inside of the plunger, and then move the plunger, screw, and piston so as to push them into the barrel, thereby preventing the molding material in the barrel from flowing back into the plunger. The molding material in the barrel is injected through the nozzle of the barrel.

"Example" An example of the present invention will be described below based on FIGS. 1 and 2.

In FIGS. 1 and 2, reference numeral 11 indicates an injection device according to the present embodiment, and an input port 12a into which the molding material is input;
and a cylindrical plunger 12 equipped with an opening 12b for discharging the molding material; and a cylindrical plunger 12 rotatably mounted in the plunger 12 to direct the molding material introduced into the plunger 12 into the opening 12b of the plunger 12. A piston 14 that covers the opening 12b of the plunger 12 and is provided so as to be relatively movable in the longitudinal direction of the plunger 12, and a piston 14 provided between the piston 14 and the plunger 12. an actuator 15 that moves relative to the actuator 15, into which the piston 14 is slidably fitted, and a nozzle 1 into which the molding material is discharged.
6, and the piston 1
4, a through hole 18 is formed which communicates the inside of the plunger 12 and the inside of the barrel 17, and is opened and closed by the screw 13 as the piston 14 and the plunger 12 move relative to each other. The structure is as follows.

Next, to explain these details, the plunger 12 is supported by the base 19 of the injection device 11 so as to be slidable in the length direction via a slider 20, and in a state in which rotation around an axis is restricted. At the same time, an injection cylinder 21 provided on the base 19 is connected so that the injection cylinder 21 can reciprocate in the above-mentioned direction.

The molding material input 012a is formed near the end of the base 19 of the plunger 12 along the radial direction of the plunger 12, and a material filling device 22 is integrally attached to the side of the blunt gloss 12. has been contacted.

The material filling device 22 includes a guide member 23 that guides the molding material to the input port +2a when the molding material is fed into the material filling device 22.
and a hydraulic cylinder 24 that is attached to the guide tube 23 and pushes the forming material fed into the guide tube 23 toward the input port 12a.

The screw 13 is inserted over almost the entire length of the plunger 12, and one end thereof is located near the opening 12b of the plunger 12, and is connected to the spiral R13a formed on the outer periphery. A screw head 25 having an outer diameter approximately equal to the outer diameter of the bottom portion and having a conical tip portion is integrally provided. Further, a rotation drive device 26 such as a hydraulic motor is connected to the other end of the screw 13, and the rotation drive device 26 rotates relative to the plunger 12.

The piston 14 is formed into a disc shape and is arranged to face the opening 12b of the plunger 12,
The opening 1 is located in a portion facing the opening 12b.
2b, the opening 1 is axially slidably fitted within the opening 1.
A convex portion 14a that closes off the screw 2b is provided in a protruding manner, and the through hole 18 is formed in the center so as to be coaxial with the axis of the screw 13.

At the end of the through hole 18 on the screw 13 side,
Contact surface 1 having the same shape as the conical shape of the screw head 25
8a is formed.

Further, an intermediate cylinder 27 is connected to the piston 14, and is fitted onto the outer surface of the plunger 12 so as to be slidable in the axial direction, and has an outer diameter equivalent to the outer diameter of the piston 14.
The actuator 15 is provided between the intermediate cylinder 27 and the plunger 12 (in this embodiment, between the slider 20).

The piston 14 is actuated by the actuator 15 using the slider 20 as a support, and the piston 14 is moved into a plunger! The screw head 25 is moved relative to the plunger 2 in its length direction, and when brought closest to the opening 12b of the plunger 12, the screw head 25 is brought into contact with the contact surface 18a of the through hole 18. By being
The through hole 18 is then closed.

Furthermore, between the intermediate cylinder 27 and the plunger 12,
As mentioned above, screw head 25 and screws!・N14
The engaging portion 2 that brings the plunger 12 and the intermediate cylinder 27 into contact with each other in a state in which the plunger 12 and the intermediate cylinder 27 are brought into contact with the contact surface 18a
8 is formed.

The barrel 17 is integrally attached to the base 1'9 of the injection device 11 via a connecting member 29, and the nozzle 16 having a small inner diameter is connected to one end thereof.
The piston 14 and the intermediate cylinder 27 are fitted into the interior from the other end in a fluid-tight manner and slidable in the axial direction.

The barrel 17 is shaped and attached to the base 19 in such a way that a space B having a predetermined volume is formed between the piston 14 and the nozzle 16 when the plunger 12 is pulled out the most. is set.

Further, the barrel 17 or the plunger 12 is provided with a heater or a barrel (not shown) through which a heating medium is passed, which heats and plasticizes the molding material fed under pressure by the screw 13.

Next, the injection device 11 of this embodiment formed in this way
The effect of this will be explained as follows.

First, as shown in FIG.
is pushed into the actuator 15 and thus into the barrel 17, thereby forming a predetermined space B in the barrel 17, and separating the piston 14 and the screw head 25, so that the piston 1
By opening the through hole 18 formed in 4,
The space B and the inside of the plunger 12 are brought into communication through the through hole 18.

From this, the screw 13 is rotated by the rotary drive device 26, and the material filling device 22 is started to charge the screw 13.
By charging the molding material into the plunger 12 from 12a, the molding material is force-fed toward the opening 12b of the plunger 12 by the screw 13, and
The molding material is heated with a heater or a heat medium to plasticize it.

By continuously performing the second pumping operation and the plasticizing operation, the plasticized molding material is transferred to the opening 1 of the plunger 12.
2b, it is fed into the space B in the barrel 17 through the gap between the screw head 25 and the convex portion 14a and the through hole 18.

Then, when the molding material sent into the space B reaches a predetermined amount, the rotation of the screw 13 is stopped, and the actuator 15 is actuated to move the piston 14 toward the screw 13. and the piston 1 is brought into contact with the screw head 25.
The through hole 18 formed in 4 is closed.

Thereafter, the injection cylinder 21 is actuated to move the plunger 12, screw 13, piston 14, actuator 15, material filling device 22, and intermediate cylinder 27 together with the slider 20 toward the barrel 17. Pressurizing the molding material in the space B of the barrel 17 and injecting the molding material into the external mold (path shown) through the nozzle 16 of the barrel 17;
It is something that

In the process of a series of operations as described above, when extruding the plasticized molding material into the space B in the barrel 17, the gap between the screw head 25 and the convex portion 14a of the piston 14 and the piston 14 are Although it must pass through the formed through hole 18, the convex portion 14a and the screw head 2
5 can be arbitrarily adjusted by appropriately setting the amount of movement of the piston 14, and since the through hole 18 is formed in the center of the piston 14 and has a sufficient wall thickness, It is possible to increase the inner diameter of the piston 14 while suppressing a decrease in its strength, thereby reducing flow path resistance to the molding material. Furthermore, as the inner diameter of the through hole 18 of the piston 14 increases, it may be necessary to increase the outer diameter of the screw head 25 that opens and closes the through hole 18. Since the shape change is in the direction of increasing the strength, it is easy to deal with it. Furthermore, in this embodiment, the force at the time of injection is distributed and supported also in the engagement portion provided between the intermediate cylinder 27 and the blunt gear 12, so that the stress generated in the screw head 25 is reduced. This also increases the degree of freedom in strength design.

Therefore, even when Nti strong fibers such as glass fibers are added to the molding material, damage to these additives and shear damage within the screw grooves can be prevented.

On the other hand, since the opening/closing operation of the through hole 18 formed in the piston 14 is reliably performed by forced movement of the piston 14 by the actuator 15, the barrel 17
The extrusion and injection operations of the molding material into the interior are performed smoothly and reliably.

It should be noted that the shapes and dimensions of each component shown in the above embodiments are merely examples, and can be changed in various ways based on design requirements and the like.

"Effects of the Invention" As explained above, the injection device of the injection molding machine according to the present invention includes a cylindrical plunger equipped with an inlet into which a molding material is introduced and an opening through which the molding material is discharged; A screw that is rotatably installed in the plunger and forces the molding material introduced into the plunger toward the opening of the plunger, and a screw that covers the opening of the plunger and is movable relative to the length of the plunger. a barrel provided with a piston, an actuator provided between the piston and the plunger for relative movement therebetween, and a nozzle into which the piston is slidably fitted and into which molding material is discharged; and, the piston is provided with a through hole that communicates the inside of the blunt and the inside of the barrel and that is opened and closed by the screw as the piston and the plunger move relative to each other. It produces the following immersive effects.

The flow path when extruding the plasticized molding material into the barrel is
Due to the gap between the piston and the screw and the through hole formed in the piston, it is possible to position the screw in an extension of the axial center line of the screw. The gap formed between the piston and the screw can be easily enlarged by changing the relative movement of the piston and the plunger by a large amount, and by ensuring a sufficient wall thickness of the piston, the gap can be easily expanded. The diameter of the hole can be easily increased, and the flow path can be enlarged.

Therefore, it is possible to suppress this breakage by reducing the filtration flow path resistance of the molding material, especially when the molding material contains strong fibers such as glass fibers and fibers. can.

In addition, by opening and closing the through-hole formed in the piston by forcibly moving the piston and the plunger using an actuator, the molding material can be extruded into the barrel, and the molding material extruded into the barrel. The pressurizing operation, that is, the injection operation is performed smoothly and reliably.

[Brief explanation of the drawing]

In the drawings, FIGS. 1 and 2 show one embodiment of the present invention, so FIG. 1 is a cross-sectional side view of the main part, and FIG. 2 is a diagram similar to FIG. 1 for explaining the operation. Figures 3 to 5
The figures show an example of the structure of a conventional injection device, and FIG. 3 is a cross-sectional side view of the main parts, FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3, and FIG. Third to explain the operation
FIG. 11... Injection device, 12... Plunger, 12a... Inlet, +2b... Opening, 13... Screw, 14...
・Piston, 14a...Convex portion, 15...
...Actuator, 16...Nozzle,
17... Barrel, 18... Through hole,
18a... Contact surface, 21... Injection cylinder, 25... Screw head, 27...
...Intermediate cylinder, 28...Engagement portion, 29.
...Connecting member, B...Space part.

Claims (1)

[Claims] A cylindrical plunger equipped with an inlet into which molding material is input and an opening through which the molding material is discharged; and a cylindrical plunger which is rotatably installed in the plunger and which discharges the molding material input into the plunger through the opening of the plunger. a screw for pressure-feeding the plunger; a piston that covers the opening of the plunger and is movable relative to the plunger in the length direction; a barrel having a nozzle into which the piston is slidably fitted and from which a molding material is discharged; An injection device for an injection molding machine, characterized in that a through hole is formed that is opened and closed by the screw as the piston and plunger move relative to each other.