JPH09314624A - Plasticizing and injection apparatus of injection molding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily shorten an apparatus and to improve molding. SOLUTION: In an injection completion state shown by a drawing, when a screw 8 is rotated in the direction shown by an arrow by operating an rotary drive device 9, the resin in a hopper 5 is introduced into a heating cylinder 1 and plasticized while gradually sent toward a cover member 4 and passed through the resin passage (t) between a cavity hole 8a and a cylindrical body 4a to enter the storage chamber R in front of a back flow preventing mechanism 13. When a predetermined amt. of the resin is weighed in the storage chamber R and a plunger 11 retreats to a predetermined position, the rotary drive device 9 is stopped to stop the rotation of the screw 8. Almost at the same time, a moving drive apparatus 12 allows the plunger 11 to advance to inject the weighed resin in the storage chamber R from a nozzle 6.

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 resin and injecting it into a cavity.

[0002]

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

This plasticizing / injecting device can be said to be, so to speak, an in-line screw system and a screw pre-plastic system in the middle, and is roughly classified into one in which the storage chamber is formed in the nozzle and the other in the front end of the screw. There is something I did.

[0004]

In the former case where the storage chamber is formed in the nozzle, the nozzle has to be made large, and there is a problem that the device becomes long accordingly.

The latter, in which the storage chamber is formed at the front end of the screw, does not have the above-mentioned problems, but has the following other problems. (1) When the plunger is advanced to inject the resin,
The storage chamber, which had been communicated with the screw side of the heating cylinder until then, must be shut off from the screw side by bringing the storage chamber into close contact with the nozzle as the screw advances, which complicates the structure.

(2) The resin, which has been plasticized by the screw and is sent into the storage chamber from the mouth opening on the front end face of the screw toward the plunger in the inner depth, is pushed out by the plunger. Moreover, the new resin is injected earlier than the old resin in the inner part of the inner part, which causes a difference in the residence time of the resin and is likely to adversely affect the molding.

(3) Since the injection pressure of the resin is directly applied between the insertion hole and the plunger inserted in the insertion hole, the resin leakage easily occurs.

[0008]

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

A spiral can be provided on the outer peripheral surface of the cylindrical body, the front end portion of the plunger, or the inner peripheral surface of the cave.

A backflow preventing mechanism may be provided at the front end of the plunger to free the flow of the resin plasticized by the screw to the storage chamber and stop the reverse flow. in this case,
It is preferable that the backflow prevention mechanism be detachable, and that the tubular body be detachable from the heating barrel.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described based on examples with reference to the drawings. 1 and 2 show an embodiment of the present invention, in which reference numeral 1 is a heating cylinder. The heating cylinder 1 is provided on the machine base 3 by a slide device 2 so as to be movable back and forth (left and right in the drawing).

At the front end (the left end in the figure) of the heating cylinder 1, a cylindrical body 4 is provided.
A cover member 4 having a is detachably attached by a bolt or the like. The cylindrical body 4a has a circular cross section,
The center is fitted into the heating cylinder 1 with its center aligned with the center of the heating cylinder 1 to form a storage chamber 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 the outer circumference thereof. 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 by a rotation driving device 9 at a predetermined position. The screw 8 serves to plasticize a plastic material such as resin (hereinafter, resin) put in the heating cylinder 1 from the hopper 5 in cooperation with the heating cylinder, and has a cave 8a on the front end side thereof.
Insertion holes 8b are formed on the rear end side.

The inner diameter of the cavity 8a is made sufficiently larger than the outer diameter of the cylindrical body 4a, and a resin passage t communicating with the storage chamber R is formed between the inner peripheral surface of the cylindrical body 4a and the outer peripheral surface of the cylindrical body 4a. The body 4a is fitted inside. Although the inner diameters of the insertion hole 8b and the cylindrical body 4a are equal to each other in the figure, the inner diameter of the insertion hole 8b can be increased, or 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 moving drive device 12. Plunger 11
The plasticized resin stored in the storage chamber R through the resin passage t and stored (measured) in the storage chamber R is advanced to the storage chamber R by the operation of the moving drive device 12, and the nozzle 6 The 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 has a head member 13a that is detachably screwed to the front end of the plunger 11 and a backflow prevention mechanism that is loosely fitted to the shaft of the head member 13a. A ring 13b and a valve seat member 13c removably attached to the front end surface of the plunger 11, and a backflow prevention ring 13b for plasticizing the resin.
Frees the flow of plasticized resin into the storage chamber R away from the valve seat member 13c (see FIG. 3), and the plunger 1
At the time of forward (injection) movement of 1, the backflow prevention ring 13b contacts the valve seat member 13c to stop the reverse flow (see FIG. 4). In addition, the backflow prevention mechanism 1 in the figure
3 is well known.

The front end 11a of the plunger 11 is a cylindrical body 4a.
The inner diameter is smaller than the inner diameter to allow the resin to flow freely, and the rear end portion 11b of the plunger 11 is tightly fitted in the insertion hole 8b of the screw 8 to prevent the resin from leaking rearward. The plunger 11 can be configured to be separable into two or more members, for example, the front end 11a is detachably screwed to the rear end 11b.

The rotation drive device 9 shown in the figure includes an electric motor 9a such as a servomotor, a drive pulley 9b attached to the output shaft of the electric motor 9a, an annular driven pulley 9c attached to the screw 8, It consists of 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 transmission members such as gears and V-belts.

The moving drive device 12 is a hydraulic cylinder, and the plunger 11 is directly connected to its piston rod 12a. The electric motor such as a servomotor rotates the ball screw shaft or the like to move the plunger 11 back and forth. May be As described above, as the rotation drive device 9 and the movement drive device 12, the rotation drive device and the movement drive device used in the conventional injection molding machine can be used as they are or after being improved.

Next, the operation of the plasticizing / injecting apparatus of the injection molding machine having the above structure will be described. FIG. 1 shows the injection completion state. When the rotation driving device 9 is operated in this state 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. The resin passage t between the cavern 8a and the cylindrical body 4a is plasticized while being gradually fed.
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 the valve seat member 13c as shown in FIG.
Away, freeing the flow of resin to the storage compartment R. Further, the plunger 11 is gradually retracted by the resin press-fitted into the storage chamber R, and the moving drive device 12 applies a back pressure to the retracting of the plunger 11, which is the same as the conventional in-line screw injection molding machine. .

In this way, when a predetermined amount of resin is measured in the storage chamber R and the plunger 11 retracts to a predetermined position (see FIG. 2), as is well known, the retracting of the plunger 11 is detected by a sensor or the like, and rotation is performed. The driving device 9 stops and the rotation of the screw 8 stops. After that, the moving driving device 12 advances the plunger 11 to inject the measuring resin in the storage chamber 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 / injecting apparatus of the injection molding machine of this embodiment, the cylindrical body 4a forming the storage chamber R is provided in the cover member 4 and fitted in the cavern 8a formed in the screw 8. Therefore, it is easy to reduce the size of the device. Further, when the resin is injected, the backflow prevention mechanism 13 automatically cuts off the communication between the storage chamber R and the screw 8 side. Therefore, when the screw is moved forward or the nozzle is retracted, the both are brought into contact with each other so that the storage chamber and the screw side are connected. Unlike the conventional one, which cuts off communication to prevent backflow to the screw side, the structure is simple.

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

Since the tubular body 4a is detachably attached to the heating barrel 1 and the backflow prevention mechanism 13 is detachably attached to the plunger 11, the diameter and length of the tubular body 4a and the backflow prevention mechanism 13 are set. It is possible to easily change the volume of the storage chamber R by exchanging the storage chamber R with another one.

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

Further, the plasticizing of the injection molding machine shown in FIGS.
In the injection device, as shown in FIG. 7, a spiral (screw flight) is formed on the outer peripheral surface of the front end portion 11a of the plunger 11.
11c can be provided. This spiral 11c is spiral 4
Like b, it promotes plasticization of the resin.

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

As shown in FIG. 8, the backflow prevention mechanism may be omitted and the seal portion 15 may be provided on the plunger 11 instead. In the case of this embodiment, the sealing portion 15 is inserted into the insertion hole 8b.
To plasticize the resin. It is preferable that the sealing portion 15 is detachably attached to the plunger 11. The embodiment shown in FIG. 8 is plasticized by the injection molding machine shown in FIG. 1, 6 or 7.
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 less likely to malfunction.

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. 8 to start plasticizing (measuring) the resin, and the process is completed. The completion of the measurement can be known by providing a resin pressure sensor in the resin flow path and detecting an increase in the resin pressure. Apart from this, it is also possible to provide a margin for the backward stroke of the plunger 11 and to detect the movement of the plunger 11 which retracts by the above-mentioned margin due to the pressure increase when the measurement is completed, by detecting it with a sensor or the like.

In the plasticizing / injecting device of the injection molding machine of FIG. 1, as shown in FIG. 9, a spiral (screw flight) 8c can be provided on the inner peripheral surface of the cavern 8a. Spiral 8c
Is formed on the tubular member 8d, and the tubular member 8d is mounted on the screw 8
It is fixed to. This spiral 8c also promotes plasticization of the resin. The spiral 8c may be provided directly on the inner peripheral surface of the screw 8 of the cave 8a. The embodiment of FIG. 9 is also shown in FIG. 6, FIG. 7 and FIG.
It 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 that of the plasticizing / injecting apparatus of the injection molding machine of FIG. In each embodiment, the shape 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, and the storage chamber R
It is also possible to extend a part of the above to the nozzle 6 side.

The spirals 4b, 8c and 11c in the figure are all continuous, but they may not be continuous. In addition, the resin feeding direction of the spirals 4b, 8c, 11c is determined by the screw 8
The flow direction of the resin flowing from the resin through the resin passage t to the storage chamber R is generally set, but in some cases, the spiral 4
One or more of b, 8c and 11c can be in the opposite direction. Further, the spirals 4b, 8c, 11c can be simply functioned as a stirring blade without feeding.

[0034]

As described above, in the plasticizing / injecting apparatus of the injection molding machine according to the first aspect, the screw which is rotated in the circumferential direction by the rotation driving device to plasticize the resin and send it to the storage chamber, A plunger that is inserted into a heating cylinder provided with a nozzle in the cover member at the front end, is inserted into the storage chamber by a moving drive device into an insertion hole formed in the screw, and injects a plasticized resin in the storage chamber from the nozzle. In the inserted plasticizing / injection machine of the injection molding machine, a cave is formed at the front end of the screw, and the force bar member has a cylindrical body that forms a storage chamber. Since the resin passage communicating with the storage chamber is formed between the inner peripheral surface and the inner peripheral surface, the device is configured so as to be fitted into the cavern, so that the device can be easily shortened and good Moldable and resin leakage It is possible to suppress.

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

When the backflow prevention mechanism is detachably attached to the plunger or the tubular body is detachably attached to the heating tube, one or both of the backflow prevention mechanism and the tubular body are replaced to change the capacity of the storage chamber. Makes it easy to change.

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view showing a plasticized state of a plasticizing / injecting apparatus of the injection molding machine of FIG.

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

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

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

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.

[Description of Reference Signs] 1 heating cylinder 4 cover member 4a cylindrical body 4b spiral 6 nozzle 8 screw 8a cave hole 8b insertion hole 8c spiral 9 rotation drive device 11 plunger 11a front end portion 11c spiral 12 movement drive device 13 backflow prevention mechanism R Storage room t Resin passage

Claims (7)

[Claims] 1. A screw which is rotated in the circumferential direction by a rotation driving device to plasticize resin and send it to a storage chamber is inserted into a heating cylinder having a nozzle in a cover member at a front end thereof, and the screw formed in the screw. Plasticization of the injection molding machine in which the plunger, which is inserted into the above-mentioned storage chamber by the moving drive device and injects the plasticized resin in the storage chamber from the nozzle, is inserted into the hole
In the injection device, a cave hole is formed in the front end portion of the screw, and the force bar member includes a tubular body forming a storage chamber.
A plasticization / injection of an injection molding machine, characterized in that the resin passage is formed between the outer peripheral surface and the inner peripheral surface of the cave so as to be inserted into the cave with a resin passage communicating with the storage chamber being formed. apparatus. 2. The plasticizing / injecting 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. A plasticizing / injecting apparatus for an injection molding machine according to claim 1, wherein a spiral is provided at a front end portion of the plunger. 4. The plasticizing / injecting apparatus for an injection molding machine according to claim 1, wherein a spiral is provided on the inner peripheral surface of the cave. 5. A backflow prevention mechanism is provided at the front end of the plunger to prevent the resin plasticized by the screw from flowing into the storage chamber and stop the reverse flow of the resin. 5. A plasticizing / injecting apparatus for an injection molding machine according to any one of 1. 6. The plasticizing / injecting apparatus of an injection molding machine according to claim 5, wherein the backflow prevention mechanism is detachably provided on the plunger. 7. The plasticizing / injecting apparatus for an injection molding machine according to claim 1, wherein the cylindrical body is detachable from the heating cylinder.