JP3144301B2 - Injection molding machine plasticizing / injection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasticizing / injecting apparatus of an injection molding machine for plasticizing a plastic material such as a resin and injecting it into a cavity.

[0002]

2. Description of the Related Art As a plasticizing / injection device of an injection molding machine,
The screw which is rotated in the circumferential direction by the rotation driving device to plasticize the resin and feed it into the storage chamber is inserted into a heating cylinder provided with a nozzle in the front end cover member, and is inserted into the insertion hole formed in the screw. There has been proposed a device in which a plunger is inserted into the storage chamber by a driving device to inject the plasticized resin in the storage chamber from a nozzle (Japanese Patent Laid-Open No. 7-164).
494, JP-A-7-195411).

[0003] This plasticizing / injecting apparatus can be said to be a so-called folding type of an in-line screw system and a screw pre-plasticizer system. Some have done.

[0004]

However, in the former case in which the storage chamber is formed in a nozzle, the size of the nozzle must be increased, which causes a problem that the apparatus becomes longer.

[0005] The latter, in which the storage chamber is formed at the front end of the screw, does not have the above-mentioned problem, but has another problem as follows. That is, (1) when injecting the resin by moving the plunger forward,
The storage chamber, which had been connected to the screw side of the heating cylinder until then, must be shut off from the screw side by, for example, bringing the storage chamber into close contact with the nozzle as the screw advances, which complicates the structure.

(2) Since the resin plasticized by the screw and fed into the storage chamber from the mouth opened to the front end face of the screw toward the inner plunger is pushed out by the plunger, the resin is put into the storage chamber later. The new resin is injected earlier than the old resin in the inner part, which causes a difference in the residence time of the resin, which tends to adversely affect molding.

(3) Since the injection pressure of the resin is directly applied between the insertion hole and the plunger inserted into the insertion hole, resin leakage is likely to occur.

[0008]

According to a first aspect of the present invention, a plasticizing / injecting apparatus for an injection molding machine is rotated in a circumferential direction by a rotation driving device to plasticize a resin. A screw to be fed into the storage chamber is inserted into a heating cylinder provided with a nozzle in a cover member at the front end, and is inserted into the storage chamber by a moving driving device into an insertion hole formed in the screw, and the plasticized resin in the storage chamber is inserted. In a plasticizing / injecting apparatus of an injection molding machine in which a plunger for injecting a screw from a nozzle is inserted, a hollow body is formed in a front end portion of the screw, and a cylinder having a storage chamber is formed in the force bar member. A resin passage communicating with the storage chamber was formed between the surface and the inner peripheral surface of the cave, and the resin passage was fitted into the cave.

A spiral can be provided on the outer peripheral surface of the cylinder, the front end of the plunger, or the inner peripheral surface of the cavity.

[0010] At the front end of the plunger, there can be provided a backflow preventing mechanism for freeing the flow of the resin plasticized by the screw to the storage chamber and stopping the reverse flow. in this case,
The backflow prevention mechanism is preferably detachable, and the tubular body is desirably detachable from the heating cylinder.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. 1 and 2 show an embodiment of the present invention. In the drawings, reference numeral 1 denotes a heating cylinder. The heating cylinder 1 is provided movably back and forth (left and right in the figure) on the machine base 3 by a slide device 2.

At the front end (left end in the figure) of the heating cylinder 1, a cylinder 4
A cover member 4 having a is detachably attached by bolts or the like. The cylindrical body 4a has a circular cross section,
The center is fitted into the heating cylinder 1 so as to coincide with the center of the heating cylinder 1 to form a storage room R. A hopper 5 is provided at the rear end of the heating cylinder 1, and a nozzle 6 is detachably screwed to the cover member 4. The heating cylinder 1 is provided with a heater (not shown) on its outer periphery. The cylindrical body 4a can be detachably attached to the cover member 4.

A screw 8 is inserted into the heating cylinder 1 with its center aligned with the center of the heating cylinder 1, and is rotated in a circumferential direction at a predetermined position by a rotation driving device 9. The screw 8 plasticizes a plastic material such as resin (hereinafter, resin) put into the heating cylinder 1 from the hopper 5 in cooperation with the heating cylinder, and has a cavity 8a at a front end side thereof.
An insertion hole 8b is formed on the rear end side.

The inner diameter of the cavity 8a is made sufficiently larger than the outer diameter of the cylinder 4a, and a resin passage t communicating with the storage chamber R is formed between the inner peripheral surface and the outer peripheral surface of the cylinder 4a to form a cylinder. The body 4a is fitted inside. Although the inner diameter of the insertion hole 8b and the inner diameter of the cylindrical body 4a in the figure are made equal to each other, the inner diameter of the insertion hole 8b can be increased, and conversely, the inner diameter of the cylindrical body 4a can be increased.

A plunger 11 is inserted into the insertion hole 8b of the screw 8, and can be moved back and forth by a movement driving device 12. Plunger 11
The plasticizing resin plasticized by the rotation of the screw 8 and stored (weighed) in the storage room R through the resin passage t is advanced into the storage room R by the operation of the moving drive device 12, and the nozzle 6 And a backflow prevention mechanism 13 is provided at the front end thereof. The plunger 11 is rotatable relative to the screw 8.

As shown in FIGS. 3 to 5, the backflow prevention mechanism 13 includes a head member 13a detachably screwed to the front end of the plunger 11, and a backflow prevention mechanism loosely fitted to the shaft of the head member 13a. It comprises a ring 13b and a valve seat member 13c detachably attached to the front end face of the plunger 11, and at the time of plasticizing and measuring the resin, the backflow prevention silling 13b
Makes the flow of the plasticized resin away from the valve seat member 13c into the storage chamber R free (see FIG. 3).
At the time of forward (injection) movement of No. 1, the backflow prevention ring 13b comes into contact with the valve seat member 13c to stop the reverse flow (see FIG. 4). The backflow prevention mechanism 1 shown in the figure
3 is a well-known thing.

The front end 11a of the plunger 11 has a cylindrical body 4a.
The inner diameter of the plunger 11 is made slightly smaller than the inner diameter of the screw to allow the resin to flow freely, and the rear end 11b of the plunger 11 is closely fitted into the insertion hole 8b of the screw 8 to prevent the resin from leaking to the rear. The plunger 11 can be divided into two or more members, for example, by detachably screwing the front end 11a to the rear end 11b.

The rotation driving device 9 shown in the figure includes a motor 9a such as a servomotor, a driving pulley 9b attached to an output shaft of the motor 9a, and an annular driven pulley 9c attached to the screw 8. And a timing belt 9d wound around pulleys 9b and 9c.
a may be a hydraulic motor, or the transmission mechanism in which the timing belt 9d is wound around the pulleys 9b and 9c may have another structure using a transmission member such as a gear or a V-belt.

The moving drive unit 12 is a hydraulic cylinder, and the plunger 11 is directly connected to the piston rod 12a. The plunger 11 is moved forward and backward by rotating a ball screw shaft or the like by an electric motor such as a servomotor. It may be. As described above, as the rotation driving device 9 and the movement driving device 12, the rotation driving device and the movement driving device used in the conventional injection molding machine can be used as they are or by improving them.

Next, the operation of the plasticizing / injection device of the injection molding machine having the above configuration will be described. FIG. 1 shows an injection completed state. In this state, when the rotation driving device 9 is operated to rotate the screw 8 in the direction of the arrow, the resin in the hopper 5 enters the heating cylinder 1 and moves toward the cover member 4. It is plasticized while being gradually fed, and the resin passage t between the cavity 8a and the cylindrical body 4a.
And enters the storage room R on the front side of the backflow prevention mechanism 13.

At this time, the backflow prevention ring 13b of the backflow prevention mechanism 13 is pushed by the resin, and as shown in FIG.
, And allows the resin to flow freely into the storage room R. Further, the plunger 11 is gradually retracted by the resin pressed into the storage chamber R, and the moving drive device 12 applies a back pressure to the retraction of the plunger 11, which is the same as the conventional in-line screw injection molding machine. .

When a predetermined amount of resin is metered into the storage chamber R and the plunger 11 retreats to a predetermined position in this way (see FIG. 2), the retraction of the plunger 11 is detected by a sensor or the like, as is well known. The driving device 9 stops, and the rotation of the screw 8 stops. Thereafter, the movement drive device 12 advances the plunger 11 to inject the metered resin in the storage room R from the nozzle 6. At this time, the ring 13b of the backflow prevention mechanism 13 contacts the valve seat member 13c as shown in FIG. 4 to prevent the backflow of the resin.

In the plasticizing / injection apparatus of the injection molding machine according to this embodiment, a cylinder 4a having a storage chamber R is provided on a cover member 4 and fitted into a cavity 8a formed on a screw 8. Therefore, it is easy to reduce the size of the device. Also, at the time of resin injection, the backflow prevention mechanism 13 automatically shuts off the communication between the storage chamber R and the screw 8 side. The structure becomes simple unlike the conventional one in which communication is cut off to prevent backflow to the screw side.

Further, since the resin is injected from the nozzle 6 in the order in which the resin is fed into the storage room R, there is no difference in the residence time of the resin, and therefore, the molding can be performed satisfactorily. In addition, during the resin injection process, the injection pressure is not directly applied to the insertion hole 8b and the rear end 11b of the plunger 11, so that leakage of the resin to the rear end 11b is prevented.

Since the cylinder 4a is detachably attached to the heating cylinder 1 and the backflow prevention mechanism 13 is detachably attached to the plunger 11, the diameter and length of the cylinder 4a and the backflow prevention mechanism 13 are reduced. The volume of the storage room R can be easily changed by replacing the storage room R with another one having a different one.

In the plasticizing / injection apparatus of the injection molding machine of the above embodiment, a spiral (screw flight) 4b can be provided on the outer peripheral surface of the cylindrical body 4a as shown in FIG. The spiral 4b improves kneading of the resin and promotes plasticization.

The plasticization of the injection molding machine shown in FIGS.
In the injection device, a spiral (screw flight) is formed on the outer peripheral surface of the front end 11a of the plunger 11, as shown in FIG.
11c can be provided. This spiral 11c is a spiral 4
Like b, it promotes plasticization of the resin.

By the way, during the plasticizing (measuring) step, the plunger 11 is usually retracted without rotating, but the plunger 11 is rotated so that the plasticization of the resin by the spiral 11c is further improved. Can be. In this case, the plunger 11 is connected to the movement driving device 12 via a rotary joint. When the plunger 11 is rotated, the plunger 11 may be connected to the screw 8 with a sliding key, and the plunger 11 may be rotated at the same speed and in the same direction as the screw 8 by the rotation driving device 9. The rotation driving device may be configured to rotate in the same direction as the screw 8 at the same speed or at a different speed, or in the opposite direction to the screw 8. The shape, pitch, or direction of the spiral 11c is variously changed in accordance with the rotation direction, speed, and the like of the plunger 11. In the plasticizing / injection device of the injection molding machine shown in FIG. 1, if necessary, the plunger 11 can be rotated as described above.

As shown in FIG. 8, the backflow prevention mechanism can be omitted and the sealing portion 15 can be provided on the plunger 11 instead. In this embodiment, the sealing portion 15 is inserted into the insertion hole 8b.
To plasticize the resin. Preferably, the sealing portion 15 is detachably attached to the plunger 11. The plasticizer of the injection molding machine shown in FIG. 1, FIG. 6 or FIG.
It can be applied to an injection device. When the sealing portion 15 is used, the backflow prevention mechanism 13 having a complicated structure is not required, so that it is inexpensive and has few failures.

When the sealing portion 15 is provided instead of the backflow prevention mechanism 13, the plunger 11 is stopped in the state shown in FIG. Completion of the measurement can be known by providing a resin pressure sensor in the flow path of the resin and detecting an increase in the pressure of the resin. Apart from this, it is also possible to provide a margin for the retraction stroke of the plunger 11, and to detect the movement of the plunger 11 retreating by the above-mentioned margin due to the pressure increase when the measurement is completed, by using a sensor or the like.

In the plasticizing / injection apparatus of the injection molding machine shown in FIG. 1, a spiral (screw flight) 8c can be provided on the inner peripheral surface of the cavity 8a as shown in FIG. Spiral 8c
Is formed in a cylindrical member 8d, and the cylindrical member 8d is
It is fixed to. The spiral 8c also promotes plasticization of the resin. The spiral 8c may be provided directly on the inner peripheral surface of the screw 8 in the cavity 8a. The embodiment of FIG. 9 is also similar to FIGS.
Can be applied to the plasticizing / injection device of the injection molding machine.

The operation of each embodiment after FIG. 6 is basically the same as the plasticizing / injection device of the injection molding machine in FIG. In each embodiment, the shapes of the inner peripheral surface of the heating cylinder 1 and the outer peripheral surface of the screw 8 can be tapered as described in JP-A-7-164494.
Can be extended to the nozzle 6 side.

Although the spirals 4b, 8c and 11c in the figure are all continuous, they may not be continuous. The screw 4b, 8c, and 11c are fed in the same direction as the screw.
In general, the flow direction of the resin flowing into the storage room R through the resin passage t through the resin passage t is,
One or more of b, 8c and 11c can be in the opposite direction. Further, the spirals 4b, 8c and 11c can be simply made to function as stirring blades without feeding.

[0034]

As described above, the plasticizing / injecting device of the injection molding machine according to the first aspect of the present invention is a plasticizing / injecting device which is rotated in a circumferential direction by a rotation driving device to plasticize the resin and feed the resin into the storage chamber. A plunger that is inserted into a heating cylinder provided with a nozzle at a front end cover member, and is inserted into the storage chamber by a moving drive device and injected into the storage chamber from the nozzle through a nozzle formed in the screw. In the plasticizing / injection device of the inserted injection molding machine, a cavity is formed at the front end of the screw, and a cylindrical body having a storage chamber is formed in the force bar member. Since the configuration is such that the resin passage communicating with the storage chamber is formed between the inner peripheral surface and the inner peripheral surface, the resin passage is formed so as to be fitted into the cave hole. Molding is possible and resin leakage It is possible to suppress.

When a spiral is provided on one or more of the outer peripheral surface of the cylindrical body, the front end of the plunger, and the inner peripheral surface of the cavity, plasticization of the resin can be promoted. Further, when the backflow prevention mechanism is provided in the plunger, communication between the storage chamber and the screw side is automatically cut off at the time of injection, so that the structure is simplified.

When the backflow prevention mechanism is detachably attached to the plunger or the cylinder is configured to be detachable from the heating cylinder, one or both of the backflow prevention mechanism and the cylinder are replaced to replace the capacity of the storage chamber. Can be easily changed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an injection-completed state showing an embodiment of a plasticizing / injection apparatus of an injection molding machine according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which plasticization of the plasticizing / injection device of the injection molding machine in FIG. 1 is completed.

FIG. 3 is a cross-sectional view showing an open state of the backflow prevention mechanism.

FIG. 4 is a sectional view showing a closed state of the backflow prevention mechanism.

FIG. 5 is a front view of the backflow prevention mechanism along the line (VV) in FIG. 4;

FIG. 6 is a sectional view showing another embodiment of the present invention.

FIG. 7 is a sectional view showing another embodiment of the present invention.

FIG. 8 is a sectional view showing still another embodiment of the present invention.

FIG. 9 is a sectional view showing still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heating cylinder 4 Cover member 4a Cylindrical body 4b Spiral 6 Nozzle 8 Screw 8a Cavity hole 8b Insertion hole 8c Spiral 9 Rotating drive device 11 Plunger 11a Front end 11c Spiral 12 Moving drive device 13 Backflow prevention mechanism R Storage chamber t Resin passage

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B29C 45/52-45/54

Claims (7)

(57) [Claims] A screw, which is rotated in a circumferential direction by a rotation driving device to plasticize a resin and feed the resin into a storage chamber, is inserted into a heating cylinder provided with a nozzle in a front end cover member, and is inserted into the screw. The plunger of the injection molding machine into which the plunger inserted into the storage chamber by the moving drive device and injecting the plasticized resin in the storage chamber from the nozzle is inserted.
In the injection device, a cavity is formed at the front end of the screw, and the force bar member has a cylindrical body forming a storage chamber,
A plasticizing / injection of an injection molding machine, wherein the resin passage is formed between the outer peripheral surface and the inner peripheral surface of the cave so as to be fitted into the cave while forming a resin passage communicating with the storage chamber. apparatus. 2. A plasticizing / injection apparatus for an injection molding machine according to claim 1, wherein a spiral is provided on the outer peripheral surface of the cylindrical body. 3. The plasticizing / injection apparatus of an injection molding machine according to claim 1, wherein a spiral is provided at a front end of the plunger. 4. A plasticizing / injection apparatus for an injection molding machine according to claim 1, wherein a spiral is provided on an inner peripheral surface of the cavity. 5. A backflow prevention mechanism is provided at a front end of the plunger, wherein a backflow preventing mechanism for freeing the flow of the resin plasticized by the screw to the storage chamber and stopping the reverse flow is provided. A plasticizing / injection device for an injection molding machine according to any one of the above. 6. The plasticizing / injection device of an injection molding machine according to claim 5, wherein the backflow prevention mechanism is detachably provided on the plunger. 7. The plasticizing / injection apparatus for an injection molding machine according to claim 1, wherein the cylinder is detachable from the heating cylinder.